Qualification: 
Ph.D, MSc
t_rajagopalan@cb.amrita.edu
Phone: 
+91 422 2685000 Ext. 5734

Dr. Rajagopalan Thiruvengadathan received Ph.D. (2002) in the field of Thin Films from Indian Institute of Technology (IIT) Delhi with specialization towards materials physics. He has over fifteen years of post-doctoral research experience till date at various places including in Texas Tech University, Lubbock, USA, Ben Gurion University of the Negev, Beer Sheva, Israel, and then as a research assistant professor at University of Missouri – Columbia, USA previous to joining Amrita School of Engineering, Coimbatore, INDIA in May 2014 as Associate Professor in the Department of Electronics and Communication. He is also an adjunct research assistant professor (courtesy) at University of Missouri – Columbia.

His numerous publications - peer reviewed journals, book chapter, peer review proceedings and many conference presentations stand testimony to his vast expertise in the synthesis, characterization and testing of a rich variety of nanostructured materials including silicon, carbon nanotubes, graphene, metal oxides, metals and polymers with specific focus towards application development. He had received grants for his projects during his tenure as a research faculty in USA. He is also co-editing a book on Nanoenergetic Materials in association with a few faculty from IIT Kanpur, to be published by Dec 2018. As a co-inventor, he has received 2 US patents and two more applications are under review. He is a member of the Technology Team at University of Missouri, Columbia that received Nanotech Briefs’ Nano50 2007 Technology Award for Nanoengineered Superthermites and Shock Wave and Energy Generation. He has received over 1300 citations till date. As a co-author, he has received a few poster awards at conferences. He is a member of editorial board for the SCI journal, “Materials Science in Semiconductor Processing” and he is also recognized as an official reviewer for many SCI journals like Materials Research Express, Nanotechnology, Microsystem Technologies, Combustion and Flame, Journal of Applied Physics, Materials & Design etc. published by IOP and Elsevier besides others. He is a member of MRS, ACS and IEEE societies. He has also chaired a few sessions in International Conferences besides giving several invited talks at various Universities, Colleges and Research Institutes. His current research include nanoenergetic materials, RF detectors, carbon nanotubes and graphene & its derivative materials and their application aspects.

Education

  • 2002: Ph. D. in Thin Films: Synthesis & Characterization
    Indian Institute of Technology (IIT) - Delhi, INDIA
  • 1994: Masters in Physics
    Loyola College, Chennai

Qualified GATE – 1994 (Ph.D. Fellowship)

Professional Experience

Year Affiliation
May 2014 - Present Associate Professor, Dept. of Electronics and Communication Engineering, Amrita School of Engineering, Coimbatore
Domain : Teaching and Research
March 2014 - Present Adjunct Research Assistant Professor, Department of Electrical and Computer Engineering, University of Missouri – Columbia, Columbia, MO, USA
Domain : Teaching
October 2007 – February 2014 Research Assistant Professor, Dept. of Electrical & Computer Engineering, University of Missouri - Columbia, Columbia, MO, USA.
Domain : Research
October 2012 – May 2013 Senior Project Manager, NEMS/MEMS Works LLC - On sabbatical from University of Missouri)
Domain : Research & Projects’ management
June 2006 – September 2007 Post-doctoral Research Associate, Dept. of Electrical & Computer Engineering, University of Missouri, Columbia MO, USA
Domain : Research
January 2004 – April 2006 Visiting Scientist, Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva ISRAEL
Domain : Research
February 2003 - December 2003 Project Scientist, Indian Institute of Technology Delhi, INDIA
Domain : Research
March 2001 – November 2002 Research Associate, Department of Physics, Texas Tech University, Lubbock, Texas, USA
Domain : Research

Academic Responsibilities

S.No Position Class / Batch Responsibility
1. Course Mentor (Solid State Devices – Code: 15ECE111 ) 2015-16; 2016-17 and 2017-18 Organizing class committee meetings; Devising lecture & course plan; Question Paper & Quiz in consultation with other subject handling faculty
2. Class Adviser 2015 - 19 Counseling and Monitoring Academic Progress

Undergraduate Courses Handled

  1. Applied Electromagnetics
  2. Solid State Devices
  3. Analytical Instrumentation
  4. Electrical and Electronic Measurements

Post-Graduate / PhD Courses Handled

  1. Nanomaterials for Biomedical Engineering
  2. Nanosystems Design (Ph.D. coursework)
  3. Characterization of Nanomaterials (Ph. D. coursework)

Academic Research – PhD Guidance

SNo Name of the Scholar Specialization / Title Duration / Registration Status / Year
1. K A Pradeep Kumar Nuclear Radiation Monitoring using RF Detectors Deployed on an Air-borne Platform 2014 On-Going

Sponsored Research

S. No Title Agency Amount Duration Status
1. Design and Evaluation of a DRFM Mitigation System. National Instruments Academic Research, TX, USA $118000 USD 2016 -2019 On-going

Research Laboratories – Developed / Associated

Location Name and Year Sponsoring Agency Domain No. of Publications No. of Funded Projects No. of PG / PhDs
F-Block, AB-III SIERS LABORATORY National Instruments RF Engineering 5 1 1 (On-going)

Publications

Publication Type: Book

Year of Publication Title

2019

S. Bhattacharya, Agarwal, A. K., Dr. T. Rajagopalan, and Patel, V. K., Nano-Energetic Materials. Singapore: Springer , 2019.[Abstract]


This book presents the latest research on the area of nano-energetic materials, their synthesis, fabrication, patterning, application and integration with various MEMS systems and platforms. Keeping in mind the applications for this field in aerospace and defense sectors, the articles in this volume contain contributions by leading researchers in the field, who discuss the current challenges and future perspectives. This volume will be of use to researchers working on various applications of high-energy research.

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Publication Type: Book Chapter

Year of Publication Title

2019

Dr. T. Rajagopalan, “Aluminum-Based Nano-energetic Materials: State of the Art and Future Perspectives”, in Nano-Energetic Materials, 2019, pp. 9-35.[Abstract]


Technological innovations are indeed driven by enhanced abilities to understand and manipulate matter at molecular and atomic scale. Engineering energetic nanocomposites with tailored and tunable combustion characteristics is indispensable for their deployment in both civilian and defense applications. Specifically, a heterogeneous mixture of fuel [aluminum (Al), boron, magnesium, silicon, etc.] and oxidizer [cupric oxide, bismuth trioxide (Bi2O3), ferric oxide, etc.] with both the constituents having nanoscale dimensions constitutes a class of energetic material known as nanothermites. Among various fuels employed in nano-energetic formulations, the number of theoretical and experimental investigations on the utilization of Al outweighs that of any other metallic fuel. Knowledge on the physical and chemical characteristics of the constituents and their impact on combustion performance are fundamental to accelerate the pace of research and development in nano-energetic composites. Efforts to develop comprehensive understanding of the oxidation behavior are discussed in this article. Furthermore, the organization, intimacy, and dimensions of discrete fuels and oxidizers apart from their chemistry largely dictate the combustion kinetics exhibited by nanothermites. For a given nanocomposite, increasing the interfacial contact area between fuel and oxidizer improves its reaction rate by 3–5 orders of magnitude as a result of drastic reduction in mass and heat transport lengths. The bottom-up self-assembly process offers the most realistic solution to enhance the interfacial contacts between nanoscale constituents employing different approaches. This review summarizes the key findings in this area of research and lists the key challenges and opportunities for furthering the application aspects. Enhancement of combustion characteristics of energetic liquids through the utilization of Al and metal oxide nanoparticles as additives is another area of related research that continues to receive increasing attention (Sundaram et al. 2017). Energetic liquids possess unique characteristics such as lower activation temperature, higher pressure, and better volume expansion. Experimental research efforts have demonstrated ample promise for overcoming the inherent problems such as lower energy density and slow burn kinetics associated with energetic liquids. In gist, the central theme of this chapter is devoted to highlight and analyze the recent advancements on aluminum-based nano-energetic materials besides presenting the challenges and opportunities in the domain of nano-energetic materials development.

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2019

S. Bhattacharya, Agarwal, A., Patel, V., Dr. T. Rajagopalan, Basu, A., and Saha, A., “Introduction to Nano-energetic Materials”, in Nano-Energetic Materials, 2019, pp. 3-7.[Abstract]


With the advent of micro- and nano-scale devices, the energy management at molecular level is vital for performance enhancement. The field of nano-energetics focuses on the study of synthesis and fabrication of energetic materials or composites at nano-level. The nano-energetic materials may include almost all materials associated with the generation and storage of energy in all forms, viz., thermal, electrical, chemical, etc. The advantages of nano-scale are many which include characteristics like overall small particle size, large specific surface area, high surface energy and strong surface activity, and all these properties associated with the nano-scale provide a key to obtain an overall high energy turnover from such materials and composites and provide solutions to some very pressing current technology needs. The primary requirement of nano-energetic materials is to obtain an efficient energy release through combustion and other processes at the nano-scale. This is regulated by tuning the proportion of the oxidizer and fuel in combusting materials during the synthesis stage so that the thermite reaction can be stoichiometrically starved or over bred for different energy releases. These materials after synthesis are then interfaced with micro-/nano-scale electromechanical devices so that they can be put to use for concentrated blast release, pulse power generation, thrust generation, energy conversion and various other applications. These nano-structured energetic materials can be utilized as propellants, explosives and pyrotechnics on the basis of their specific spatial arrangements, enactments, and presentation spaces, etc. The various methods that are deployed to fabricate these energetic materials include wet chemical synthesis, DC reactive magnetron sputtering, electrocatalysis, molecular self-assembly. Since these nano-energetic materials and composites have wide scope in micro-/nano-energetic arena of applications, the corresponding book discusses some of the detailed and novel synthesis, fabrication, characterization, tunability, storage and application aspects of these materials.

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2018

Dr. T. Rajagopalan and Mahadevan, S., “Experimental and Computational Aspects of Electronic Properties of Carbon-Based Polymer Nanocomposites”, in Carbon-Based Polymer Nanocomposites for Environmental and Energy Applications, A. Fauzi Ismail and Goh, P. Sean, Eds. Elsevier, 2018, pp. 175 - 198.[Abstract]


The electronic properties of polymer nanocomposites with either carbon nanotubes (CNTs) or graphene inclusions as fillers are presented and discussed. The electron transport mechanisms in nanocomposites are described in this chapter. The percolation behavior of these conducting fillers in a polymer matrix is systematically discussed through electrical conductivity measurements as a function of filler (CNTs/graphene) and as a function of applied frequency. The computational efforts carried out to investigate the formation of conducting networks of CNT/graphene are also highlighted. The computational efforts can be classified into two major categories: finite element method (FEM) and non-FEM. In general, FEM-based methods are more comprehensive in facilitating a profound understanding of electron transport through the nanocomposites. The extent of correlation between the experimental and the computational values of conductivity and percolation threshold is also dealt within this chapter

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2010

Dr. T. Rajagopalan, Bezmelnitsyn, A., Apperson, S. J., Tappmeyer, D., Redner, P., Balas, W. A., Nicolich, S., Kapoor, D., Gangopadhyay, K., and Gangopadhyay, S., “Combustion Behavior of Nanoenergetic Material Systems in Energetic Materials Thermophysical Properties”, in Predictions, and Experimental Measurements (INVITED), Ed. Veera Boddu and Paul Redner., CRC Press (Taylor & Francis Group), 2010, pp. 221 - 262.

Publication Type: Journal Article

Year of Publication Title

2018

A. Wang, Bok, S., Dr. T. Rajagopalan, Gangopadhyay, K., McFarland, J. A., Maschmann, M. R., and Gangopadhyay, S., “Reactive Nanoenergetic Graphene Aerogel Synthesized by One-step Chemical Reduction”, Combustion and Flame, vol. 196, pp. 400 - 406, 2018.[Abstract]


Adoption of nanoenergetic materials into large-scale applications is hindered by problems associated with scalability, particle aggregation, stability, and electrostatic discharge (ESD) sensitivity. We report a macroscale energetic graphene aerogel that simultaneously overcomes each of these problems while increasing the energy production and flame speed with respect to neat nanothermite sample. The aerogel is comprised of reduced graphene oxide (RGO), aluminum (Al) nanoparticles, and bismuth oxide (Bi2O3) nanoparticles. Synthesis of the aerogel requires chemical reduction and gelling that preserves the reactivity of embedded fuel and oxide nanoparticles. A new gelation process is adopted in which ethylenediamine was added to a propylene carbonate dispersion to gel and reduce RGO while retaining material reactivity. The energetic aerogel enhances the heat of reaction to 967 J/g, which is 36% higher than that from loose Al/Bi2O3 powder. A combustion speed of 960 ± 190 m/s under open ambient is measured for RGO/Al/Bi2O3 gel, which is the highest value reported for an Al/Bi2O3 system. Further, the underlying reduced graphene oxide scaffold reduces ESD sensitivity of the aerogel by three orders of magnitude.

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2018

N. Zakiyyan, Wang, A., Dr. T. Rajagopalan, Staley, C., Mathai, J., Gangopadhyay, K., Maschmann, M. R., and Gangopadhyay, S., “Combustion of Aluminum Nanoparticles and Exfoliated 2D Molybdenum Trioxide Composites”, Combustion and Flame, vol. 187, pp. 1 - 10, 2018.[Abstract]


Exfoliated two-dimensional (2D) molybdenum trioxide (MoO3) of approximately 3-4 monolayers in thickness was produced from sonicating bulk MoO3 powder, and then mixed with 80 nm diameter Al nanoparticles to prepare nanoenergetic composites with high interfacial contacts between the fuel and oxidizer. Combustion measurements demonstrated peak pressures as high as 42.05 ± 1.86 MPa, pressurization rates up to 3.49 ± 0.31 MPa/µs, and linear combustion rates up to 1,730 ± 98.1 m/s, the highest values reported to date for Al/MoO3 composites. TGA/DSC measurements indicate energetic reactions between the Al and 2D MoO3 sheets occur prior to the melting temperature of Al. SEM and TEM analysis of the composites prior to combustion suggests high interfacial contact area between the Al and MoO3. After reaction, we observe that the 2D MoO3 sheets are converted to extended alumina flakes during reaction in a process attributed to Al adsorption and diffusion processes. These alumina features act as a physical barrier against Al NP sintering while also provide separation for reaction gases to flow and preheat unreacted materials.

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2017

S. S. Prabhu, Bhavani, R., Dr. Gireesh K. T., and Dr. T. Rajagopalan, “A computational approach to determine shielding effectiveness of carbon nanotube-based nanocomposites for \EMC\ application”, Computational Materials Science, vol. 126, pp. 400 - 406, 2017.[Abstract]


Abstract A computational method to determine the shielding effectiveness against electromagnetic interference of carbon nanotube (CNTs)-based nanocomposites through modelling of its electrical properties is presented. Specifically, simulations based on Ant Colony Optimization (ACO) were implemented to evaluate the electrical conductivity (σ) of \{CNTs\} (used as a filler in a polymer matrix) that formed electrical network inside a representative cuboid volume of the sample. A pseudo three-dimensional (3D) percolation model was developed to study the effects of random connectivity of \{CNTs\} to one another on the conductivity of nanocomposites. In our approach, both contact and intrinsic resistances were taken into account. The tunneling resistance between \{CNTs\} was also taken into account while dealing with single-walled \{CNTs\} (SWCNTs). A resistor network recognition method that optimizes connective paths was built using \{ACO\} method and conductivity was subsequently computed as a function of \{CNTs\} concentration. Then, the shielding effectiveness was computed using the conductivity data. It is remarkable that the calculated \{SE\} values as a function of frequency of \{EM\} waves at a constant weight percent of \{CNTs\} were in agreement with the experimental data for CNT-based nanocomposites reported in literature. More »»

2015

Dr. T. Rajagopalan, Staley, C., Geeson, J. M., Chung, S., Raymond, K. E., Gangopadhyay, K., and Gangopadhyay, S., “Enhanced Combustion Characteristics of Bismuth Trioxide-Aluminum Nanocomposites Prepared through Graphene Oxide Directed Self-Assembly”, Propellants, Explosives, Pyrotechnics, vol. 40, pp. 729–734, 2015.[Abstract]


We present a facile, spontaneous, and surfactant-free method to controllably self-assemble aluminum and bismuth trioxide nanoparticles through the introduction of graphene oxide as a self-assembly directing agent. The self-assembled nanocomposites demonstrate significant combustion performance improvements in comparison to randomly mixed aluminum and bismuth trioxide nanoparticles with enhanced pressure generation from 60 to 200 MPa, pressurization rate from 3 to 16 MPa μs−1, burning rate from 1.15 to 1.55 km s−1, and specific impulse from 41 to 71 s. The sensitivity of the self-assembled aluminum and bismuth trioxide to electrostatic discharge was reduced by four orders of magnitude, without decreasing the combustion performance. Graphene oxide directed self-assembly can be used to synthesize nanocomposites with diverse combustion properties and controlled ignition sensitivity, which lays the foundation for preparing multi-functional, highly-reactive, combustion systems in the future. More »»

2014

C. S. Staley, Raymond, K. E., Dr. T. Rajagopalan, Herbst, J. J., Swaszek, S. M., Taylor, R. J., Gangopadhyay, K., and Gangopadhyay, S., “Effect of Nitrocellulose Gasifying Binder on Thrust Performance and High-g Launch Tolerance of Miniaturized Nanothermite Thrusters”, Propellants, Explosives, Pyrotechnics, vol. 39, pp. 374–382, 2014.[Abstract]


Nanothermites are promising propellants for miniaturized thruster applications, but in their pure state can be very sensitive to ignition stimuli and prone to phase separation. Consequentially, a need exists for desensitizing binders that do not inhibit nanothermite thrust performance. We investigate the effects of incorporating small weight concentrations of nitrocellulose as a gasifying binder in bismuth trioxide-aluminum nanothermites. Thrust measurements revealed improvements in specific impulse up to 63.2 s using nitrocellulose. The launch tolerance of the nanothermites in response to high-g acceleration was also explored and substantial improvements were realized for nanothermites prepared with nitrocellulose. As small as 5 % nitrocellulose content suppressed the sensitivity of the nanothermites to less than 1 % ignition probability after exposure to 30 kg acceleration events. Some nanothermite charges experimentally survived up to 90 kg loads. Most importantly, nitrocellulose predictably modulated the thrust performance and ignition sensitivity of the nanothermites as a function of weight content. Employing nitrocellulose as a binder, high performance nanothermite propellants can be synthesized for miniaturized thruster applications with tailored impulse generation and ignition sensitivity. More »»

2014

Dr. T. Rajagopalan, Chung, S. W., Basuray, S., Balasubramanian, B., Staley, C. S., Gangopadhyay, K., and Gangopadhyay, S., “A Versatile Self-Assembly Approach toward High Performance Nanoenergetic Composite Using Functionalized Graphene”, Langmuir, vol. 30, pp. 6556-6564, 2014.[Abstract]


Exploiting the functionalization chemistry of graphene, long-range electrostatic and short-range covalent interactions were harnessed to produce multifunctional energetic materials through hierarchical self-assembly of nanoscale oxidizer and fuel into highly reactive macrostructures. Specifically, we report a methodology for directing the self-assembly of Al and Bi2O3 nanoparticles on functionalized graphene sheets (FGS) leading to the formation of nanocomposite structures in a colloidal suspension phase that ultimately condense into ultradense macrostructures. The mechanisms driving self-assembly were studied using a host of characterization techniques including zeta potential measurements, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), particle size analysis, micro-Raman spectroscopy, and electron microscopy. A remarkable enhancement in energy release from 739 ± 18 to 1421 ± 12 J/g was experimentally measured for the FGS self-assembled nanocomposites. More »»

2013

B. - D. Lee, Sengupta, S., Gangopadhyay, S., and Dr. T. Rajagopalan, “Ultra-rapid elimination of biofilms via the combustion of a nanoenergetic coating”, BMC Biotechnology, vol. 13, p. 30, 2013.[Abstract]


Background Biofilms occur on a wide variety of surfaces including metals, ceramics, glass etc. and often leads to accumulation of large number of various microorganisms on the surfaces. This biofilm growth is highly undesirable in most cases as biofilms can cause degradation of the instruments and its performance along with contamination of the samples being processed in those systems. The current “offline” biofilm removal methods are effective but labor intensive and generates waste streams that are toxic to be directly disposed. We present here a novel process that uses nano-energetic materials to eliminate biofilms in 2500 K) for an extremely brief period (~100 ms) that destroys the biofilm underneath. However, since the total amount of heat produced is low (~0.1 kJ/cm2), the underlying surface remains undamaged. Surfaces with biofilms of Pseudomonas aeruginosa initially harboring ~ 107 CFU of bacteria /cm2 displayed final counts of less than 5 CFU/cm2 after being subjected to our process. The byproducts of the process consist only of washable carbonaceous residue and gases, making this process potentially inexpensive due to low toxic-waste disposal costs. Conclusions This novel method of biofilm removal is currently in the early stage of development. However, it has potential to be used in offline biofilm elimination as a rapid, easy and environmentally friendly method. More »»

2013

C. S. Staley, Raymond, K. E., Dr. T. Rajagopalan, Apperson, S. J., Gangopadhyay, K., Swaszek, S. M., Taylor, R. J., and Gangopadhyay, S., “Fast-Impulse Nanothermite Solid-Propellant Miniaturized Thrusters”, Journal of Propulsion and Power, vol. 29, pp. 1400-1409, 2013.[Abstract]


Highly reactive nanothermites prepared by mixing bismuth trioxide or cupric oxide nanoparticles with aluminum nanoparticles were evaluated as solid propellants for small-scale propulsion applications. Miniaturized engines were fabricated from steel in three-piece configurations without a converging/diverging nozzle. Bismuth trioxide-aluminum generated 46.1 N average thrusts for 1.7 ms durations with a specific impulse of 41.4 s. Cupric oxide-aluminum generated 4.6 N thrusts for 5.1 ms durations with a specific impulse of 20.2 s. Convective and conductive reaction regimes were identified as functions of bulk packing density and confinement geometry. Average thrusts and burning durations differed by greater than an order of magnitude for equivalent nanothermites dependent on the reaction regime. Adding small amounts of nitrocellulose to the nanothermites increased specific and volumetric impulses to maximum values of 59.4 s and 2.3  mN·s/mm3 while controllably reducing average thrusts and prolonging burning durations. The energy-conversion efficiencies of the thrusters were evaluated using a rotary-arm measurement, and a maximum efficiency of 0.19% was observed. Last, a miniaturized four-engine array was fabricated with micromachined initiators and sequentially fired. The high specific and volumetric impulses, fast combustion, and tailored reactions of nanothermites are appealing for many small-scale propulsion applications.

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2013

Dr. T. Rajagopalan, Korampally, V., Ghosh, A., Chanda, N., Gangopadhyay, K., and Gangopadhyay, S., “Nanomaterial Processing using Self-assembly-Bottom-up Chemical and Biological Approaches”, Reports on Progress in Physics (Invited Review) , vol. 76, p. 066501, 2013.[Abstract]


Nanotechnology is touted as the next logical sequence in technological evolution. This has led to a substantial surge in research activities pertaining to the development and fundamental understanding of processes and assembly at the nanoscale. Both top-down and bottom-up fabrication approaches may be used to realize a range of well-defined nanostructured materials with desirable physical and chemical attributes. Among these, the bottom-up self-assembly process offers the most realistic solution toward the fabrication of next-generation functional materials and devices. Here, we present a comprehensive review on the physical basis behind self-assembly and the processes reported in recent years to direct the assembly of nanoscale functional blocks into hierarchically ordered structures. This paper emphasizes assembly in the synthetic domain as well in the biological domain, underscoring the importance of biomimetic approaches toward novel materials. In particular, two important classes of directed self-assembly, namely, (i) self-assembly among nanoparticle–polymer systems and (ii) external field-guided assembly are highlighted. The spontaneous self-assembling behavior observed in nature that leads to complex, multifunctional, hierarchical structures within biological systems is also discussed in this review. Recent research undertaken to synthesize hierarchically assembled functional materials have underscored the need as well as the benefits harvested in synergistically combining top-down fabrication methods with bottom-up self-assembly.

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2012

Dr. T. Rajagopalan, Belarde, G. Maria, Bezmelnitsyn, A., Shub, M., Balas-Hummers, W., Gangopadhyay, K., and Gangopadhyay, S., “Combustion Characteristics of Silicon-Based Nanoenergetic Formulations with Reduced Electrostatic Discharge Sensitivity”, Propellants, Explosives, Pyrotechnics, vol. 37, pp. 359–372, 2012.[Abstract]


This paper details the synthesis and combustion characteristics of silicon-based nanoenergetic formulations. Silicon nanostructured powder (with a wide variety of morphologies such as nanoparticles, nanowires, and nanotubes) were produced by DC plasma arc discharge route. These nanostructures were passivated with oxygen and hydrogen post-synthesis. Their structural, morphological, and vibrational properties were investigated using X-ray diffractometry, transmission electron microscopy (TEM), nitrogen adsorption-desorption analysis, Fourier transform infrared (FTIR) spectrometry and Raman spectroscopy. The silicon nanostructured powder (fuel) was mixed with varying amounts of sodium perchlorate (NaClO4) nanoparticles (oxidizer) to form nanoenergetic mixtures. The NaClO4 nanoparticles with a size distribution in the range of 5–40 nm were prepared using surfactant in a mixed solvent system. The combustion characteristics, namely (i) the combustion wave speed and (ii) the pressure-time characteristics, were measured. The observed correlation between the basic material properties and the measured combustion characteristics is presented. These silicon-based nanoenergetic formulations exhibit reduced sensitivity to electrostatic discharge (ESD). More »»

2012

M. Korampally, Apperson, S. J., Staley, C. S., Castorena, J. A., Dr. T. Rajagopalan, Gangopadhyay, K., Mohan, R. R., Ghosh, A., Polo-Parada, L., and Gangopadhyay, S., “Transient pressure mediated intranuclear delivery of FITC-Dextran into chicken cardiomyocytes by MEMS-based nanothermite reaction actuator”, Sensors and Actuators B: Chemical, vol. 171–172, pp. 1292 - 1296, 2012.[Abstract]


We have developed a novel, operator-friendly, nanothermite reaction actuator which generates transient pressures comprised of a shock wave superimposed on a broad pressure pulse to facilitate intranuclear molecular transport. The actuator demonstrates the delivery of ∼70 kDa FITC-Dextran into chicken cardiomyocytes with cytoplasmic delivery efficiency greater than 90%, maximum intranuclear delivery efficiency of 84%, and cell survival rates exceeding 95% in minimum operating pressure conditions. Tunable nanothermite reactions enable versatile pressure generating characteristics which can extend the technology to a spectrum of biomedical molecular delivery applications. More »»

2011

C. S. Staley, Morris, C. J., Dr. T. Rajagopalan, Apperson, S. J., Gangopadhyay, K., and Gangopadhyay, S., “Silicon-based bridge wire micro-chip initiators for bismuth oxide–aluminum nanothermite”, Journal of Micromechanics and Microengineering, vol. 21, p. 115015, 2011.[Abstract]


We present a micro-manufacturing process for fabricating silicon-based bridge wire micro-chip initiators with the capacity to liberate joules of chemical energy at the expense of micro joules of input electrical energy. The micro-chip initiators are assembled with an open material reservoir utilizing a novel 47 °C melting point solder alloy bonding procedure and integrated with a bismuth oxide–aluminum nanothermite energetic composite. The electro-thermal conversion efficiency of the initiators is enhanced by the use of a nanoporous silicon bed which impedes thermal coupling between the bridge wire and bulk silicon substrate while maintaining the structural integrity of the device. Electrical behaviors of the ignition elements are investigated to extract minimum input power and energy requirements of 382.4 mW and 26.51 µJ, respectively, both in the absence and presence of an injected bismuth oxide–aluminum nanothermite composition. Programmed combustion of bismuth oxide–aluminum nanothermite housed within these initiators is demonstrated with a success rate of 100% over a 30 to 80 µJ range of firing energies and ignition response times of less than 2 µs are achieved in the high input power operation regime. The micro-initiators reported here are intended for use in miniaturized actuation technologies. More »»

2011

Dr. T. Rajagopalan, Bezmelnitsyn, A., Apperson, S., Staley, C., Redner, P., Balas, W., Nicolich, S., Kapoor, D., Gangopadhyay, K., and Gangopadhyay, S., “Combustion characteristics of novel hybrid nanoenergetic formulations”, Combustion and Flame, vol. 158, pp. 964 - 978, 2011.[Abstract]


This paper presents the combustion characteristics of various copper oxide (CuO) nanorods/aluminum (Al) nanothermite compositions and hybrid nanoenergetic mixtures formed by combining nanothermites with either ammonium nitrate (NH4NO3) or secondary explosives such as \{RDX\} and CL-20 in different weight proportions. The different types of nanorods prepared in this study are referred to as CuO-VD (dried under vacuum at 25 °C for 24 h), CuO-100 (at 100 °C for 16 h) and CuO-400 (short time (1 min) calcination at 400 °C). The physical and chemical characteristics of these different kinds of CuO nanorods were determined using a variety of analytical tools such as X-ray diffractometer, transmission electron microscope (TEM), Fourier transform infrared spectrometer (FTIR), surface area analyzer and simultaneous differential scanning calorimeter (DSC)/thermogravimetric analyzer (TGA). These measured characteristics were correlated with the combustion behavior of the nanoenergetic compositions synthesized in this work. The use of different drying and calcination parameters produced the synthesis of CuO nanorods with varying amount of hydroxyl (OH) and \{CHn\} (n = 2, 3) functional groups. The experimental observations confirm that the presence of these functional groups on the surface of CuO nanorods enabled the formation of assembled nanoenergetic composite, upon mixed with Al nanoparticles. A facile one-step synthesis of assembled composite through surface functionalization is reported and it can be extended to large-scale preparation of assembled nanoenergetic mixtures. The combustion behavior was studied by measuring both combustion wave speed and pressure–time characteristics. Pressurization rate was determined by monitoring the pressure–time characteristics during the combustion reaction initiated by a hot wire in a fully-confined geometry. Different amounts of nanothermite powder were packed in the same volume of combustion chamber by applying different packing pressures and the pressure–time characteristics were measured as a function of varying percent theoretical maximum density (% TMD). The experimental setup used in this work enabled us to study the functional behavior of initiating explosives such as \{NH4NO3\} nanoparticles, \{RDX\} and CL-20 using nanothermites under fully-confined test geometry. The dent tests performed on lead witness plates support the experimental observations obtained from pressure–time and combustion wave speed measurements of hybrid mixtures. More »»

2010

S. Gangopadhyay, Apperson, S. J., Gangopadhyay, K., Dr. T. Rajagopalan, and Bezmelnitsyn, A., “Multi-mode nanothermite thrusters with tunable impulse”, Abstracts (Missouri Technology Expo 2010), 2010.[Abstract]


Microthrusters have applications in projectile guidance systems, and micro-nano-satellite control. Thrusters are an integral part of a guidance system that includes orientation and trajectory sensors and target recognition components. The thrusters provide the actuation force to move the projectile. Nanothermite composites containing metallic fuel and inorganic oxidizer have unique combustion properties that make them potentially useful for microthruster applications. The nanothermite formulation can be tuned to achieve specific impulse characteristics. Depending on the application of the thruster, nanothermite formulation and motor design can be chosen to meet the application requirements. If properly configured, the reaction can have a velocity of 1000m/s. The efficiency of the thrusters is not drastically affected by the duration of reaction More »»

2010

Dr. T. Rajagopalan, Bezmelnitsyn, A., Apperson, S. J., Staley, C., Gangopadhyay, K., and Gangopadhyay, S., “Design and development of nanoenergetic materials with tunable combustion characteristics [abstract]”, Abstracts (Missouri Technology Expo 2010), 2010.[Abstract]


In recent years, nanoengineered thermites with tunable and tailored characteristics have attracted a great deal of attention owing to their enormous potential as excellent reactive materials, green primers, and structural energetic materials etc. Nanothermites are typically composed of metal oxide (oxidizer) and metal (fuel) nanoparticles. A variety of nanostructured oxidizers such as Fe2O3, CuO, Bi2O3 and MoO3 etc have been prepared in our laboratory. Various morphologies of oxidizers include nanorods, nanoparticles, and mesoporous structures exhibiting high surface area. Surfactant templating method has been developed for the synthesis of ammonium nitrate (NH4NO3) nanoparticles with a size distribution of 10–100nm. The physical and the chemical properties such as morphology, surface area, purity, composition, crystal structure of these metal oxide nanostructures have been determined by a host of characterization tools. Among the nanothermites, CuO nanorods/Al nanoparticles exhibit the best combustion performance measured in terms of combustion wave speed of 2600 ± 100 m/s and reactivity of 11± 1 MPa/msec. Nanothermites based on CuO nanorods/Al nanoparticles were then modified by mixing with polymers such as nitrocellulose (NC) and/or explosives such as (NH4NO3) nanoparticles, RDX (micron and nano size) and CL20 and the reaction rates of these nanocomposites were determined. Among the polymers, nitrocellulose coating of nanothermites is very interesting. Both the NC and the Teflon coated CuO/Al based nanothermite systems exhibit the ability to generate shock waves during their fast combustion. The NC coating has shown tremendous potential to reduce the high sensitivity of nanothermites to electrostatic discharge (ESD), friction and impact. Experimentally measured combustion characteristics are found to correlate very well with the physical and chemical characteristics of metal oxide nanostructures. The developed technology in our lab demonstrates the potential to tune and tailor the combustion characteristics of nanothermites to the desired level by proper choice and combination of fuel and oxidizer materials, their dimensions, and the process of self-assembly with reduced sensitivity. Potential Areas of Applications: * Microthrusters; * Propellants; * Propellant Initiators; * Suitable Replacements for Lead and Sulfur based Primers; * Shockwave drug delivery systems; More »»

2010

Dr. T. Rajagopalan, Lee, B. Doo, Smith, B., Sengupta, S., Polo-Parada, L., Gangopadhyay, S., and Gangopadhyay, K., “Applications of Energetic Materials and Copper Oxide Nanorods for Decontamination [abstract]”, 2010.

2010

M. Korampally, Apperson, S. J., Korampally, V., Bok, S., Dr. T. Rajagopalan, Bezmelnitsyn, A., Polo-Parada, L., Gangopadhyay, K., and Gangopadhyay, S., “Shock Wave Based Cell Transfection and Fluorescent Organosilicate Nanoparticles for Targeted Drug Delivery [abstract]”, Abstracts (Missouri Regional Life Sciences Summit 2010), 2010.

2010

Dr. T. Rajagopalan, Bezmelnitsyn, A., Apperson, S. J., Tappmeyer, D., Redner, P., Balas, W. A., Nicolich, S., Kapoor, D., Gangopadhyay, K., and Gangopadhyay, S., “Combustion behavior of nanoenergetic material systems”, Energetic Materials: Thermophysical Properties, Predictions, and Experimental Measurements, p. 221, 2010.

2010

A. Bezmelnitsyn, Dr. T. Rajagopalan, Barizuddin, S., Tappmeyer, D., Apperson, S., Gangopadhyay, K., Gangopadhyay, S., Redner, P., Donadio, M., Kapoor, D., and Nicolich, S., “Modified Nanoenergetic Composites with Tunable Combustion Characteristics for Propellant Applications”, Propellants, Explosives, Pyrotechnics, vol. 35, pp. 384–394, 2010.[Abstract]


This work reports on the synthesis and tunable characteristics of nanothermite compositions based on mesoporous Fe2O3 as an oxidizer and Al nanoparticles as a fuel. The reactivity (rate of increase of pressure) and the combustion wave speed were determined to evaluate the performance of these composites for various applications. A gas generating polymer, (acrylamidomethyl) cellulose acetate butyrate (AAMCAB), was loaded in the mesopores of Fe2O3 matrix following wet-impregnation technique. The samples prepared in this work were characterized by a number of analytical techniques such as Fourier transform infrared (FTIR) absorption spectroscopy, transmission and scanning electron microscopy (TEM, SEM), energy dispersive X-ray analysis, X-ray diffraction, and nitrogen adsorption–desorption isotherms. Then, mesoporous Fe2O3 powder was mixed with Al nanoparticles to prepare nanoenergetic composites. The main characteristics such as peak pressure, reactivity, combustion wave speed, and pressure sustenance were determined as a function of polymer loading. The dependence of combustion wave speed on the pressure was established following the well-known Vieille's law. The small value of 0.408 for the pressure exponent indicates the suitability of these nanothermite compositions for propellant applications. By reducing the percentage of polymer, the characteristic properties of nanoenergetic composite can be suitably tuned for other applications. More »»

2009

V. Korampally, Yun, M., Dr. T. Rajagopalan, Dasgupta, P. K., Gangopadhyay, K., and Gangopadhyay, S., “Entropy driven spontaneous formation of highly porous films from polymer–nanoparticle composites”, Nanotechnology, vol. 20, p. 425602, 2009.[Abstract]


Nanoporous materials have become indispensable in many fields ranging from photonics, catalysis and semiconductor processing to biosensor infrastructure. Rapid and energy efficient process fabrication of these materials is, however, nontrivial. In this communication, we describe a simple method for the rapid fabrication of these materials from colloidal dispersions of Polymethyl Silsesquioxane nanoparticles. Nanoparticle–polymer composites above the decomposition temperature of the polymer are examined and the entropic gain experienced by the nanoparticles in this rubric is harnessed to fabricate novel highly porous films composed of nanoparticles. Optically smooth, hydrophobic films with low refractive indices (as low as 1.048) and high surface areas (as high as 1325 m 2 g −1 ) have been achieved with this approach. In this communication we address the behavior of such systems that are both temperature and substrate surface energy dependent. The method is applicable, in principle, to a variety of nanoparticle–polymer systems to fabricate custom nanoporous materials. More »»

2009

S. J. Apperson, Bezmelnitsyn, A. V., Dr. T. Rajagopalan, Gangopadhyay, K., Gangopadhyay, S., Balas, W. A., Anderson, P. E., and Nicolich, S. M., “Characterization of nanothermite material for solid-fuel microthruster applications”, Journal of Propulsion and Power, vol. 25, pp. 1086–1091, 2009.

2008

Dr. T. Rajagopalan, .Bok, S., .A.Lubguban, A., .Gao, Y., .Bhattacharya, S., .Korampally, V., and .Hossain, M., “Electro Chemical Properties of Carbon Nanoparticles Entrapped in a Silica Matrix”, Journal ofthe ElectrochemicalSociety, vol. 155, no. 5, 2008.[Abstract]


Carbon-based electrode materials have been widely used for many years for electrochemical charge storage, energy generation, and catalysis. We have developed an electrode material with high specific capacitance by entrapping graphite nanoparticles in a sol-gel network. Films from the resulting colloidal suspensions were porous due to the removal of the entrapped organic solvents from the sol-gel matrix giving rise to high Brunauer–Emmett–Teller specific surface areas Formula and a high capacitance density Formula . An exponential decrease of capacitance was observed with increasing scan rates in cyclic voltammetry studies on these films, suggesting the presence of pores ranging from micro- Formula to mesopores. Nitrogen adsorption–desorption analysis and scanning electron microscope images of these films also confirmed the presence of the micropores as well as mesopores. A steep drop in the double-layer capacitance with polar electrolytes was observed when the films were rendered hydrophilic upon exposure to mild oxygen plasma. We propose a model whereby the microporous hydrophobic sol-gel matrix perturbs the hydration of ions which moves ions closer to the graphite nanoparticles, consequently increasing the capacitance of the film.

More »»

2008

M. Jin, Chen, P., Boolchand, P., Dr. T. Rajagopalan, Chopra, K. L., Starbova, K., and Starbov, N., “Inhomogeneous, disordered, and partially ordered systems-Origin of giant photocontraction in obliquely deposited amorphous GexSe1-x thin films and the intermediate phase”, Physical Review B Condensed Matter And Materials Physics, vol. 78, p. 214201, 2008.

2008

Dr. T. Rajagopalan, Lahlouh, B., Chari, I., Othman, M. T., Biswas, N., Toma, D., and Gangopadhyay, S., “Hexamethyldisilazane vapor treatment of plasma damaged nanoporous methylsilsesquioxane films: Structural and electrical characteristics”, Thin Solid Films, vol. 516, pp. 3399 - 3404, 2008.[Abstract]


Repair of plasma damaged nanoporous organosilicate films carried out by hexamethyldisilazane (HMDS) vapor treatment was investigated as a function of temperature. Capacitance–voltage measurements were carried out before and after \{HMDS\} vapor treatment. The dielectric constant measurements confirm that the \{HMDS\} vapor treatment facilitates only partial curing of the plasma damaged films, as also observed from the Fourier transform infrared absorption measurements. Bias temperature stress measurements for samples with copper (Cu) metal electrodes reveal a shift of − 35 V in the capacitance–voltage curve for samples cured at 55 °C whereas negligible shift is observed for samples treated above 80 °C. This behavior suggests the existence of a dense solid layer on the top surface of the samples treated above 80 °C, hindering the diffusion or movement of Cu ions into the dielectric. Direct imaging of the \{HMDS\} vapor treated plasma damaged films using scanning electron microscope clearly shows the existence of two distinct layers, with the top layer (at the film–air interface) being denser than the bottom layer at the film–substrate interface. More »»

2008

M. Jin, Chen, P., Boolchand, P., Dr. T. Rajagopalan, Chopra, K. L., Starbova, K., and Starbov, N., “Origin of giant photocontraction in obliquely deposited amorphous $\textGe}_x\textSe}_1\ensuremath-x}$ thin films and the intermediate phase”, Phys. Rev. B, vol. 78, p. 214201, 2008.[Abstract]


Obliquely deposited amorphous GexSe100−x thin films at several compositions in the 15%25%, the stressed rigid phase, and at x More »»

2008

R. Shende, Subramanian, S., Hasan, S., Apperson, S., Dr. T. Rajagopalan, Gangopadhyay, K., Gangopadhyay, S., Redner, P., Kapoor, D., Nicolich, S., and , “Nanoenergetic Composites of CuO Nanorods, Nanowires, and Al-Nanoparticles”, Propellants, Explosives, Pyrotechnics, vol. 33, pp. 122–130, 2008.[Abstract]


This paper reports on the synthesis of the nanoenergetic composites containing CuO nanorods and nanowires, and Al-nanoparticles. Nanorods and nanowires were synthesized using poly(ethylene glycol) templating method and combined with Al-nanoparticles using ultrasonic mixing and self-assembly methods. Poly(4-vinylpyridine) was used for the self-assembly of Al-nanoparticles around the nanorods. At the optimized values of equivalence ratio, sonication time, and Al-particle size, the combustion wave speed of 1650 m s−1 was obtained for the nanorods-based energetics. For the composite of nanowires and Al-nanoparticles the speed was increased to 1900 m s−1. The maximum combustion wave speed of 2400 m s−1 was achieved for the self-assembled composite, which is the highest known so far among the nanoenergetic materials. It is possible that in the self-assembled composites, the interfacial contact between the oxidizer and fuel is higher and resistance to overall diffusional process is lower, thus enhancing the performance. More »»

2007

D. Tappmeyer, Dr. T. Rajagopalan, Shende, R., Gangopadhyay, K., Apperson, S. J., and Gangopadhyay, S., “Nano-synthesis of Energetic Materials”, 2007.[Abstract]


Energetic materials are defined as substances in which fuel and oxidizer react chemically to release energy. The amount and rate of energy released by this reaction can be improved by increasing the amount of interfacial contact between fuel and oxidizer. In conventional energetic materials macroscopic particles of fuel and oxidizer are mixed randomly. In this arrangement energy is lost due decreased contact between fuel and oxidizer as a result of the large particle size and random distribution. To reduce the amount of energy lost much smaller nano-particles can be used. The smaller particles allow for increased interfacial contact between fuel and oxidizer, resulting in improved performance. Even with smaller particles some energy is still lost due to the random arrangement. In order to further improve performance it is necessary to order the arrangement of fuel and oxidizer. Utilizing a method known as surfactant templating ordered structures such as nanorods, nanowires, and nanowells (similar to a honeycomb) can be created from oxide materials such as Copper Oxide, and Iron Oxide. When Aluminum Nano-particle fuel is mixed with these ordered oxide materials the resulting material has greatly increased interfacial contact between fuel and oxidizer. When reacted, these materials have minimal energy loss and greatly improved energetic performance. The increased performance of this type of material has created the possibility of many new applications for energetic materials. The potential uses for this material range from on chip power generation, to shockwave generation for medical imaging. More »»

2007

Dr. T. Rajagopalan, Levi-Kalisman, Y., and Regev, O., “Synergetic effect of ultrasound and sodium dodecyl sulphate in the formation of CdS nanostructures in aqueous solution”, Ultrasonics Sonochemistry, vol. 14, pp. 398 - 404, 2007.[Abstract]


High aspect ratio (>1000) CdS nanostructures were prepared via ultrasound treatment of parent nanowires (NWs) dispersed in sodium dodecyl sulfate (SDS) aqueous solution. The CdS parent \{NWs\} were prepared using ordered mesoporous silica, SBA-15, as a template. The elongated nanostructures (ENS), namely, NWs, nanoribbons and nanotubes, form stable dispersions in aqueous solutions. Electron microscopy and X-ray diffraction techniques were used to characterize both the parent \{NWs\} and the ENS. While the structure of the parent \{NWs\} is crystalline cubic, the \{ENS\} are amorphous. We show that the amorphous \{ENS\} bud from the parent bundled NWs. Ultrasound power and duration, presence of commensurate surfactant and calcination temperature of the templating SBA-15 are critical parameters in the formation of \{ENS\} in aqueous solution. More »»

2007

N. Geblinger, Dr. T. Rajagopalan, and Regev, O., “Preparation and characterization of a double filler polymeric nanocomposite”, Composites Science and Technology, vol. 67, pp. 895 - 899, 2007.[Abstract]


Single walled carbon nanotubes (SWNTs) with an anisotropic morphology (rod) are currently being employed as fillers in polymer matrix to produce novel nanocomposites with enhanced properties and performance in a wide variety of applications. We investigate the effect of the addition of second isotropic (spherical) filler, antimony tin oxide (ATO) particles to the anisotropic SWNT-polymer composites. Cryogenic transmission electron microscope (cryo-TEM) and scanning electron microscope (SEM) were employed to image the aqueous dispersions of the SWNTs–ATO–Latex solution and composite thin films respectively. The \{SEM\} imaging of these films shows that \{SWNTs\} (rods) tend to aggregate in the presence of \{ATO\} clusters, indicating depletion interactions between the rods and the spheres. The difference in the value of electrical conductivity of the films measured along the radial and the tangential directions to the spinning lines is probably due to the preferred orientation of the \{SWNTs\} in the matrix during the spin coating process. More »»

2006

B. Lahlouh, Dr. T. Rajagopalan, Biswas, N., Sun, J., Huang, D., Simon, S. L., Lubguban, J. A., and Gangopadhyay, S., “Post treatments of plasma-enhanced chemical vapor deposited hydrogenated amorphous silicon carbide for low dielectric constant films”, Thin Solid Films, vol. 497, pp. 109 - 114, 2006.[Abstract]


Post treatments by annealing or supercritical carbon dioxide (SCCO2) exposure of plasma-enhanced chemical vapor deposited hydrogenated amorphous silicon carbide (a-SiC:H) films are reported to reduce the dielectric constant up to 2.1. The a-SiC:H films were prepared using diethylsilane diluted in methane. The deposition precursors and conditions were chosen to fabricate a thermally unstable a-SiC:H film with a high concentration of \{CHn\} (n = 1, 2, 3) functional groups. The Fourier transform infra-red spectroscopy measurements of as-deposited films show a-SiC:H networks and presence of a-C:H moieties throughout the film. The films were then annealed in vacuum up to 450 °C to remove thermally unstable \{CHn\} as well as other species. After annealing, the dielectric constant of the films decreased from 4.2 up to 2.1 due to the decrease in film density. The reduction suggests the presence of molecular voids/pores. Annealing produced a stable film with thickness decreasing by a maximum of 6% only. \{SCCO2\} treatment was also explored and found to be more effective in the extraction of \{CHn\} and other species at 200 °C. More »»

2006

Dr. T. Rajagopalan, Lahlouh, B., Lubguban, J. A., Biswas, N., Gangopadhyay, S., Sun, J., Huang, D. H., Simon, S. L., Toma, D., and Butler, R., “Investigation on hexamethyldisilazane vapor treatment of plasma-damaged nanoporous organosilicate films”, Applied Surface Science, vol. 252, pp. 6323 - 6331, 2006.[Abstract]


Hexamethyldisilazane (HMDS) vapor treatment of plasma-damaged nanoporous organosilicate thin films has been studied as a function of treatment temperature in this work. Although, the \{HMDS\} vapor treatment facilitated incorporation of methyl (CH3) groups subsequent to the removal of free hydroxyl (OH) groups in the damaged films at treatment temperature as low as 55 °C, the bonded \{OH\} groups were not removed. More significantly, detailed analysis of the results reveals that \{HMDS\} vapor modified only the surface of the plasma-damaged samples and not the entire film as expected. This is attributed to the formation of a thin solid layer on the surface, which effectively prevents penetration of \{HMDS\} vapors into the bulk. The Fourier transform-infrared (FT-IR) absorption and dielectric constant measurements confirm that the vapor treatment assists only partial curing of the plasma-damaged films. Alternative processes of curing the films with \{HMDS\} dissolved in supercritical carbon dioxide (SCCO2) as a medium of reaction in static and pulsed modes were also attempted and the results are presented in this paper. More »»

2006

V. Weiss, Dr. T. Rajagopalan, and Regev, O., “Preparation and characterization of a carbon nanotube-lyotropic liquid crystal composite”, Langmuir, vol. 22, pp. 854–856, 2006.[Abstract]


We present a detailed study on the integration of individual single-walled carbon nanotubes (SWNTs) within a lyotropic hexagonal liquid crystal (LC) for the first time. Two systems are studied in this work; in the first, the same surfactant is used for both the dispersion of the SWNTs and the formation of the LC. In the second system, we use different surfactants for the dispersion of SWNTs and LC formation. Light microscopy imaging combined with small-angle X-ray scattering (SAXS) indicates that the nanotubes (NTs) are well dispersed and aligned along the LC director. The macroscopic property, namely, the viscosity, is strongly enhanced by the presence of the NTs. More »»

2006

S. Attal, Dr. T. Rajagopalan, and Regev, O., “Determination of the concentration of single-walled carbon nanotubes in aqueous dispersions using UV-visible absorption spectroscopy”, Analytical Chemistry, vol. 78, pp. 8098-8104, 2006.[Abstract]


Stable, homogeneous, aqueous dispersions of single-walled carbon nanotubes (SWNTs) are prepared by nonspecific physical adsorption of surfactants enhanced by sonication. Upon centrifugation, supernatant and precipitate phases are obtained. The initial weights of the SWNTs and the surfactant are divided between these two phases, and the respective SWNT concentration in each phase is unknown. The focus of this work is on the determination of the true concentration of raw, exfoliated HiPCO SWNTs in the supernatant phase. A UV−visible absorption-based approach is suggested for a direct measurement of the SWNT and the surfactant concentration in the supernatant. UV−visible absorbance spectra of SWNTs−surfactant dispersions and surfactants alone reveal that the intensity of a certain peak, attributed to the π-plasmon resonance absorption, is unaffected by the presence of most surfactants. A calibration plot is then made by monitoring the intensity of the peak as a function of the true concentration of the exfoliated SWNTs. Thus, we are able to determine the unknown concentration of surfactant-dispersed HiPCO SWNTs in the supernatant solution, simply by measuring its optical absorbance. Moreover, we can now calculate the surfactant efficiency in dispersing SWNTs. Cryogenic-transmission electron microscopy and thermogravimetric analysis techniques are used for the characterization of these dispersions and to complement the UV−visible measurements. More »»

2005

Dr. T. Rajagopalan, Levi-Kalisman, Y., and Regev, O., “Templating nanostructures by mesoporous materials with an emphasis on room temperature and cryogenic \TEM\ studies”, Current Opinion in Colloid & Interface Science, vol. 10, pp. 280 - 286, 2005.[Abstract]


Rapid strides realized in the field of ordered mesoporous silica (OMS) with a well-defined pore shape and nanometric sizes, provide new gateways for the preparation of nanostructured materials having controlled shape and size with a very narrow distribution. The focus of the current review is on the synthesis of nanostructures templated by \{OMS\} either in bulk or in thin film form. The importance of electron microscopy as an indispensable technique in the structural characterization of \{OMS\} templated nanostructures, including cryo-TEM, electron tomography and HR-SEM, is highlighted in this review. More »»

2005

Dr. T. Rajagopalan and Regev, O., “Hierarchically ordered cadmium sulfide nanowires dispersed in aqueous solution”, Chemistry of Materials, vol. 17, pp. 3281-3287, 2005.[Abstract]


The paper reports on the preparation, characterization, and dispersion of cadmium sulfide (CdS) nanowires using ordered mesoporous silica, SBA-15, as a template. A homogeneous and stable dispersion of hierarchically ordered CdS nanowires in water solubilized with sodium dodecyl sulfate (SDS) has been obtained. Direct imaging of the nanoconnectors (templated by the micropores in SBA-15) between the bundled nanowires has been accomplished by high-resolution transmission electron microscope (HRTEM). Cryogenic-TEM (cryo-TEM) measurements carried out on the dispersed samples complemented by small-angle X-ray (SAX) diffraction and HRTEM examination of the dry CdS powder clarify the role played by the micropores in the formation of a hierarchically ordered array of nanowires in the meso- and atomic scale. The amount of nanoconnectors is controlled by varying the calcination temperature of SBA-15, which tunes the formation of either bundled or individual CdS nanowires. The effect of such organizations is discussed in view of optical absorption and fluorescence measurements. More »»

2004

J. A. Lubguban, Gangopadhyay, S., Lahlouh, B., Dr. T. Rajagopalan, Biswas, N., Sun, J., Huang, D. H., Simon, S. L., Mallikarjunan, A., Kim, H. - C., and al., et, “Supercritical CO2 extraction of porogen phase: An alternative route to nanoporous dielectrics”, Journal of Materials Research, vol. 19, pp. 3224–3233, 2004.[Abstract]


We present a supercritical CO2 (SCCO2) process for the preparation of nanoporous organosilicate thin films for ultralow dielectric constant materials. The porous structure was generated by SCCO2 extraction of a sacrificial poly(propylene glycol) (PPG) from a nanohybrid film, where the nanoscopic domains of PPG porogen are entrapped within the crosslinked poly(methylsilsesquioxane) (PMSSQ) matrix. As a comparison, porous structures generated by both the usual thermal decomposition (at approximately 450 °C) and by a SCCO2 process for 25 and 55 wt% porogen loadings were evaluated. It is found that the SCCO2 process is effective in removing the porogen phase at relatively low temperatures (<200 °C) through diffusion of the supercritical fluid into the phase-separated nanohybrids and selective extraction of the porogen phase. Pore morphologies generated from the two methods are compared from representative three-dimensional (3D) images built from small-angle x-ray scattering (SAXS) data.

More »»

2004

S. Gangopadhyay, Lubguban, J. A., Lahlouh, B., Sivaraman, G., Biswas, K., Dr. T. Rajagopalan, Biswas, N., Kim, H. - C., Volksen, W., and Miller, R. D., “Supercritical CO2 Treatments for Semiconductor Applications”, MRS Proceedings, vol. 812, 2004.[Abstract]


Supercritical fluids (SF) have been used in a wide variety of applications: in industrial processes, analytical, waste detoxification, etc. Recently, its usefulness extends to the semiconductor industry. Researches have shown that supercritical CO2 (SCCO2) can be used to remove photoresists and significantly reduce the amount of waste from solvents in comparison to conventional stripping techniques. SF will also find its usefulness in cleaning high aspect ratio vias and deep trenches as semiconductor features shrink to submicron levels. We will report here the use of supercritical CO2 treatments in extraction of porogens from a nanohybrid film fabricated via templated-porogen approach. Its use as a medium to repair the damage in porous films from plasma ashing will also be presented. The ability to tune the solvation and diffusion power of SCCO2 and to swell the film matrix make it a good medium for silylation to restore hydrophobicity and functionalize the film. More »»

2003

B. Lahlouh, Dr. T. Rajagopalan, Lubguban, J. A., Biswas, N., Gangopadhyaya, S., Sun, J., Huang, D., Simon, S. L., Kim, H. C., Volksen, W., and Miller, R. D., “Creating Nanoporosity by Selective Extraction of Porogens Using Supercritical Carbon Dioxide/Cosolvent Processes”, MRS Proceedings, vol. 766, 2003.[Abstract]


AbstractThis work presents a novel approach using supercritical carbon dioxide (SCCO2) to selectively extract poly(propylene glycol) (PPG) porogen from a poly(methylsilsesquioxane) (PMSSQ) matrix, which results in the formation of nanopores. Nanoporous thin films were prepared by spin-casting a solution containing appropriate quantities of PPG porogen and PMSSQ dissolved in PM acetate. The as-spun films were thermally cured at temperatures well below the thermal degradation temperature of the organic polymer to form a cross-linked organic/inorganic polymer hybrid. By selectively removing the CO2 soluble PPG porogen, open and closed pore structures are possible depending upon the porogen load and its distribution in the matrix before extraction. In the present work, two different loadings of PPG namely 25 wt.% and 55 wt.% were used. Both static SCCO2 and pulsed SCCO2/cosolvent treatments were used for PPG extraction. The initial results indicate that the pulsed SCCO2/cosolovent treatm" # "ent was more efficient. Fourier transform infrared spectroscopy (FTIR) and refractive index measurements further corroborate the successful extraction of the porogens at relatively low temperatures (2000C). For the pure PMSSQ film, the k value is 3.1, whereas it is 1.46 and 2.27 for the open and closed pore compositions respectively after the static SCCO2 extraction and 430°C subsequent annealing. The reduction in the k-value is attributed to the formation of nanopores. The pore structure was verified from transmission electron microscopy (TEM), and from small-angle x-ray scattering (SAXS) measurements, the pore size was determined to be 1-3 nm for these films. More »»

2003

Dr. T. Rajagopalan, Wang, X., Lahlouh, B., Ramkumar, C., Dutta, P. S., and Gangopadhyay, S., “Low temperature deposition of nanocrystalline SiC films by PECVD and their structural and optical characterization”, J. Applied Physics, vol. 94, pp. 5252–5260, 2003.

2003

Dr. T. Rajagopalan, Lahlouh, B., Lubguban, J. A., Biswas, N., Gangopadhyay, S., Sun, J., Huang, D. H., Simon, S. L., Mallikarjunan, A., Kim, H. - C., and , “Supercritical carbon dioxide extraction of porogens for the preparation of ultralow-dielectric-constant films”, Applied physics letters, vol. 82, pp. 4328–4330, 2003.[Abstract]


Supercritical carbon dioxide extraction of poly(propylene glycol) porogen from poly(methylsilsesquioxane) (PMSSQ) cured to temperatures adequate to initiate matrix condensation, but still below the decomposition temperature of the porogen, is demonstrated to produce nanoporous, ultralow-dielectric-constant thin films. Both closed and open cell porous structures were prepared simply by varying the porogen load in the organic/inorganic hybrid films. 25 and 55 wt % porogen loads were investigated in the present work. Structural characterization of the samples conducted using transmission electron microscope, small angle x-ray scattering, and Fourier transform infrared spectroscopy, confirms the extraction of the porogen from the PMSSQ matrix at relatively low temperatures (⩽200 °C). The standard thermal decomposition process is performed at much higher temperatures (typically in the range of 400 °C–450 °C). The values of dielectric constants and refractive indices measured are in good agreement with the structural properties of these samples. More »»

2003

Dr. T. Rajagopalan, Wang, X., Lahlouh, B., Ramkumar, C., Dutta, P., and Gangopadhyay, S., “Low temperature deposition of nanocrystalline silicon carbide films by plasma enhanced chemical vapor deposition and their structural and optical characterization”, Journal of applied physics, vol. 94, pp. 5252–5260, 2003.[Abstract]


Nanocrystalline silicon carbide ~SiC! thin films were deposited by plasma enhanced chemical vapor deposition technique at different deposition temperatures (Td) ranging from 80 to 575 °C and different gas flow ratios ~GFRs!. While diethylsilane was used as the source for the preparation of SiC films, hydrogen, argon and helium were used as dilution gases in different concentrations. The effects of Td , GFR and dilution gases on the structural and optical properties of these films were investigated using high resolution transmission electron microscope ~HRTEM!, micro-Raman, Fourier transform infrared ~FTIR! and ultraviolet-visible optical absorption techniques. Detailed analysis of the FTIR spectra indicates the onset of formation of SiC nanocrystals embedded in the amorphous matrix of the films deposited at a temperature of 300 °C. The degree of crystallization increases with increasing Td and the crystalline fraction (f c) is 65%62.2% at 575 °C. The f c is the highest for the films deposited with hydrogen dilution in comparison with the films deposited with argon and helium at the same Td . The Raman spectra also confirm the occurrence of crystallization in these films. The HRTEM measurements confirm the existence of nanocrystallites in the amorphous matrix with a wide variation in the crystallite size from 2 to 10 nm. These results are in reasonable agreement with the FTIR and the micro-Raman analysis. The variation of refractive index ~n! with Td is found to be quite consistent with the structural evolution of these films. The films deposited with high dilution of H2 have large band gap (Eg) and these values vary from 2.6 to 4.47 eV as Td is increased from 80 to 575 °C. The size dependent shift in the Eg value has also been investigated using effective mass approximation. Thus, the observed large band gap is attributed to the presence of nanocrystallites in the films. More »»

2002

J. A. Lubguban, Sun, J., Dr. T. Rajagopalan, Lahlouh, B., Simon, S. L., and Gangopadhyay, S., “Supercritical Carbon Dioxide Extraction to Produce Low-k plasma Enhanced Chemical Vapor Deposited Dielectric Films”, Applied Physics Letters, vol. 81, pp. 4407-4409, 2002.[Abstract]


A treatment to reduce the dielectric constant of plasma enhanced chemical vapor deposition (PECVD) films is presented. The method involved extracting low molecular weight or CO2 soluble species in the films by post deposition supercritical CO2 pressurization (SCCO2). We observed a decrease in k value of about 10%–14% in a composite film of organosilicate and a-C:F after SCCO2 treatment at 200 °C for 8 h. The composite films were deposited by PECVD using C4F8 and tetravinyltetramethylcyclotetrasiloxane (TVTMCTS) liquid source and H2 carrier gas at room temperature. As-deposited films were also annealed at 200 °C for 8 h in N2 atmosphere to compare the effect of thermal annealing without SCCO2 treatment. The result shows that there is no change in the k of the films after annealing. Thus, SCCO2 extraction is a good method for reducing the dielectric constant of these PECVD composite films. Supercritical CO2 pressurization of the film deposited using TVTMCTS and H2 only without the addition of C4F8 has no effect on the dielectric properties of the film while SCCO2 treatment of a-C:F samples deposited using C4F8 only dissolved the film. Therefore, in the composite film, we expect that CFx species dissolve during SCCO2 treatment while the organosilicate structure is preserved. Analysis of the Fourier-transform infrared spectra of the samples supports this hypothesis based on the decrease in the C–F absorption intensity after SCCO2 treatment.

More »»

2002

J. Lubguban, Dr. T. Rajagopalan, Mehta, N., Lahlouh, B., Simon, S. L., and Gangopadhyay, S., “Low-k organosilicate films prepared by tetravinyltetramethylcyclotetrasiloxane”, Journal of Applied Physics, vol. 92, pp. 1033-1038, 2002.[Abstract]


Low-kfilms with k of 2.5–2.9 were deposited under different conditions of pressures and temperatures using a plasma-enhanced chemical vapor deposition(PECVD) system. These films were prepared using a new liquid precursor, tetravinyltetramethylcyclotetrasiloxane (TVTMCTS) and H2H2 carrier gas. The rf power was kept as low as possible to maintain the original ring structure in the films. The as-deposited films were annealed and the dielectric and optical properties were investigated. Identification of the absorption bands in the IR spectra for as-deposited films reveals a broadband around 950–1200 cm−1cm−1 arising from the Si–O stretching mode of the ring (1065 cm−1)cm−1) and chain structure (1000 cm−1),cm−1), respectively; a band at 750–900 cm−1cm−1 due to Si–O bending (790 cm−1);cm−1); Si–CH3Si–CH3 rocking mode (760 cm−1);cm−1); a sharp band centered at 1260 cm−1cm−1 due to a Si–CH3Si–CH3 bending mode; and a broadband at 2800–3000 cm−1cm−1 due to the CH group. A comparison of the IR spectra of the PECVDfilm and TVTMCTS liquid reveals that vinyl vibrations (Si–CH=CH2)(Si–CH=CH2) at 960, 1410, and 3030–3095 cm−1cm−1 for CH2CH2 and at 1598 cm−1cm−1 for C=C present in the liquid were not detected in the CVDfilms. Hence C=C bonds were broken in the plasma polymerization process. As the pressure and the depositiontemperature(TD)(TD) increased, the intensity of the Si–O vibration arising from the ring structure increased and decreased, respectively. Thus by tuning the pressure and TDTD we can control the structure of the film. There is a good correlation found between the Si–CH3Si–CH3 and Si–O ring intensities and k values; the increasing Si–CH3Si–CH3 and Si–O ring is accompanied by decreasing k. The films were thermally stable up to 400 °C400 °Cannealingtemperature. More »»

2000

Dr. T. Rajagopalan and Reddy, G. B., “Formation of highly oriented GeBiSe films from the as-deposited amorphous state by annealing”, Thin Solid Films, vol. 377–378, pp. 501 - 506, 2000.[Abstract]


As-deposited amorphous GeBiSe films were crystallized by thermal and laser annealing. Their structural properties were studied using a glancing angle X-ray diffractometer (GAXRD) and a transmission electron microscope (TEM). Films were crystallized into either a polycrystalline or a highly oriented state, depending on the choice of parameters, such as annealing temperature, rate and duration, and substrate nature and composition. All phases have been identified. The effect of annealing conditions on the relative proportion of these phases has been investigated. A wide range of surface topographical features, such as pyramidal needle shapes of 3 μm length and spherical crystallites with average sizes of 0.35–2 μm, were observed on annealing. The laser scan parameters have been optimized to only obtain crystallization. The film composition and annealing parameters have been optimized in order to obtain strongly oriented crystalline films with a smooth surface topography. More »»

2000

Dr. T. Rajagopalan and Reddy, G. B., “Thermal and optical properties of Ge5Bi18Se77 films”, Journal of Materials Science: Materials in Electronics, vol. 11, pp. 397–400, 2000.[Abstract]


Amorphous films of Ge5Bi18Se77 deposited by vacuum evaporation have been studied for their thermal and optical properties. Differential scanning calorimetry (DSC) has been used to perform the thermal analysis to estimate the activation energy for crystallization (Ec) and the order of crystallization (m) of this material. The high value of (Ec), 1.672 eV, indicates good stability of the amorphous phase. The optical constants of the as-deposited, amorphous and the thermally annealed crystalline films indicate semiconducting behavior and the band gap (Eg) determined from Tauc's plot are 0.92 eV and 0.8 eV for the amorphous and crystalline films, respectively. The value of the absorption coefficient ($\alpha$) is of the order of 104cm-1 in the optical range for both amorphous and crystalline films. The studies on optical and thermal properties confirm the suitability of these firms in phase change optical recording. More »»

1999

Dr. T. Rajagopalan and Reddy, G. B., “Effect of annealing rate on the crystallization process in Ge5Bi18Se77 films”, Thin Solid Films, vol. 353, pp. 254 - 258, 1999.[Abstract]


Amorphous Ge5Bi18Se77 thin films deposited by thermal evaporation were crystallized by thermal annealing at their crystallization temperature (Tc). The composition, determined using EDAX, does not indicate any significant variation in both as-deposited films and films annealed with different annealing rates from that of bulk alloy. The effect of annealing rate on the nature and the degree of crystallization has been investigated by studying the structure using TEM/XRD and the surface morphology using SEM. It is found that the annealed films crystallized into a face centred cubic (FCC) phase with a lattice constant of 6.2084±0.0015 Å. Further, it is also seen that depending on the annealing rate, the as-deposited films crystallized into either single crystal films or polycrystalline films. A detailed analysis of the structural properties has been presented. More »»

1998

Dr. T. Rajagopalan and Reddy, G. B., “Study of surface topography and optical properties of Ge15Bi38Se47 films”, Journal of Materials Science: Materials in Electronics, vol. 9, pp. 133–137, 1998.[Abstract]


Adherent and smooth amorphous GeBiSe films deposited by vacuum evaporation at substrate temperatures less than 30 °C have been studied for their structural and optical properties. The films were crystallized by thermal annealing and they were found to be polycrystalline in nature. A correlation between X-ray diffraction (XRD) data and surface topography is reported. Optical constants calculated from reflectance and transmittance data indicate semiconducting behaviour. The optical band gap of the as-deposited film is 1.0 eV. The measured optical contrast at 0.8 $μ$m is 44{%}. No significant changes in the optical parameters have been observed after exposing the samples to laboratory ambient for a period of six months. More »»

Publication Type: Conference Paper

Year of Publication Title

2017

M. Sidhaarth, Suriyanarayanan, R., Srigovindan, G., and Dr. T. Rajagopalan, “A holistic approach to evaluate EMI shielding characteristics of carbon nanotube-based polymer composites”, presented at the 10, 2017.[Abstract]


The work presents a comprehensive methodology to determine the Shielding Effectiveness (SE) of single-walled carbon nanotubes (SWCNTs)/polymer nanocomposites. Here, an algorithm based on Ant Colony Optimization (ACO) was employed to determine the electrical conductivity ({\sigma}) of these nanocomposites as a function of SWCNT concentration. Then, these {\sigma} values were used to compute the SE values as a function of frequency and concentration. Specifically, a pseudo three-dimensional (3D) percolation model was developed to study the effects of random connectivity of SWCNTs to one another on the {\sigma} values of the nanocomposites. Both intrinsic and tunneling resistances were taken into account. The consequences of the presence of both well-exfoliated and aggregated SWCNTs with varying lengths distributed inhomogeneously on {\sigma} and SE values were investigated.

More »»

2017

J. Geeson, Staley, C., Bok, S., Dr. T. Rajagopalan, Gangopadhyay, K., and Gangopadhyay, S., “Graphene-based Al-Bi2O3 nanoenergetic films by electrophoretic deposition”, in IEEE 12th Nanotechnology Materials and Devices Conference (NMDC), 2017.[Abstract]


The combustion performance of aluminum-bismuth trioxide (Al/Bi2O3) nanoenergetic films with and without graphene additive prepared through electrophoretic deposition was evaluated. The role of graphene in minimizing phase separation and promoting self-assembly of Al and Bi2O3 nanoparticles was investigated. The neat Al/Bi2O3 films exhibited an average combustion wave speed of 206.0±30.0 m/s and energy release of 733±30 J/g. Incorporation of graphene improved average combustion wave speed to 244±8 m/s, raised energy release to 1071±23 J/g, and reduced the onset ignition temperature by 11±3°C in comparison to that of neat samples. The obtained results confirm that graphene is an appealing additive for nanoenergetic films produced by EPD.

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2017

Dr. T. Rajagopalan and Dr. Shanmugha Sundaram G. A., “Electromagnetic fields for propagation and confinement of high current heavy ion beam towards conformal thin film deposition”, in 2016 IEEE Asia-Pacific Conference on Applied Electromagnetics, APACE 2016, 2017, pp. 68-72.[Abstract]


Uniform thin layers of heavy elements such as niobium (Nb) have been found to possess superior superconductivity characteristics in applications like radio frequency cavity resonators. The experimental process to realize conformal coating with reproducible characteristics especially on non-planar, cavity resonators rests on the generation of high-current beam of Nb ions. Here, the fundamental principles that govern the motion of such ions in an electromagnetic (e-m) field are investigated. An electric quadrupole is designed via modelling so as to generate desired e-m fields that support parallel propagation as well as confinement of the Nb ions to a desired beam size and shape in ultrahigh vacuum (UHV) conditions. The simulation study presented here considers the case of Nb ions whose currents are of the order of 5 A, that traverse a length of 130 cm and have a cross-section radius of 3.75 cm. The trajectories for Nb ions are simulated, and the effect of external fields on the trajectory of ions is evaluated using appropriate performance metrics. © 2016 IEEE.

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2008

P. E. Anderson, Balas, W., Dr. T. Rajagopalan, Bezmelnitsyn, A. V., Gangopadhyay, K., and Gangopadhyay, S., “Sensitivity and Performance of Solution-phase synthesized Nanothermite Materials”, in INTERNATIONAL ANNUAL CONFERENCE-FRAUNHOFER INSTITUT FUR CHEMISCHE TECHNOLOGIE, 2008.

2008

D. Tappmeyer, Gangopadhyay, S., Gangopadhyay, K., Dr. T. Rajagopalan, Bezmelnitsyn, A., Apperson, S., and Newport, N., “Electric Arc Production of Nanoparticles for Energetic Materials”, in The 2008 Annual Meeting, 2008.

2007

D. Tappmeyer, Dr. T. Rajagopalan, Bezmelnitsyn, A., Apperson, S., Gangopadhyay, K., Gangopadhyay, S., Redner, P., Balas, W., Kapoor, D., and Nicolich, S., “Novel Nanoenergetic Material Using Porous Copper Oxide Nanoparticles and Aluminum Nanoparticles”, in The 2007 Annual Meeting, 2007.[Abstract]


We are currently developing nanoengineered thermites (nanothermite) with tailored properties that are expected to replace lead azide and lead styphnate primers in the near future. Nanothermites are comprised of a mixture of nanoscaled fuel and oxidizer. Typically Al nanoparticles are used as fuel and metal oxides like CuO, MoO3, Bi2O3 are used as oxidizers. Herein we combine two methodologies namely surfactant templating and sol-gel approach to synthesis porous CuO nanoparticles. The formation and the stability of the gel were optimized by varying the proportions of the precursors. The gel was then washed and heated for complete removal of surfactant. The nanoparticles were characterized using Transmission Electron Microscopy and Fourier transform infrared (FTIR) spectroscopy. Micrographs revealed the formation of nano-porous particles with a diameter of 75-100 nm with 4-6 nm pores. FITR was performed on all samples to confirm the formation of copper oxide and the successful removal of impurities. The combustion characteristics were determined by performing burn rate and reactivity measurements. Burn rate was measured using an optical method. The inner walls of a lexane tube were coated with nanothermite slurry. The combustion speed of the energetic material was obtained from the propagation distance traveled and measured time of propagation. The porous nanoparticles exhibit very high combustion speeds of 1900 m/s. In conclusion, the results clearly reveal that the nanothermites prepared with porous CuO nanoparticles (oxidizer) and Al nanoparticles (fuel) are indeed very promising for both military and civilian applications. More »»

2007

A. Bezmelnitsyn, Dr. T. Rajagopalan, Apperson, S., Shende, R., Gangopadhyay, K., Gangopadhyay, S., Redner, P., Balas, W., Kapoor, D., and Nicolich, S., “Reactivity of Conventional and Modified Nanothermites”, in The 2007 Annual Meeting, 2007.[Abstract]


Nanoengineered composites of metal oxide (oxidizer) and metal(fuel)have shown to exhibit enhanced combustion properties. More specifically, when the sizes of oxidizer and fuel particles are in nanoscale, the heat and the mass transport length scales are drastically reduced, leading to enhanced combustion speeds and reaction rates. Thus, it is quite possible to achieve tunable reaction rates by proper choice and combination of fuel, oxidizer and other chemicals, their dimensions in nanoscale and the mixing ratio. The present work is devoted to the study of reaction rates of conventional and modified nanothermites. We have used a variety of metal oxides, namely, Fe2O3, CuO and MoO3 and Al as the fuel. The conventional nanothermites were also modified by mixing with ammonium nitrate (AN) nanoparticles. The reactivity was determined by monitoring the pressure as a function of time generated during the energetic reaction. The rate of increase in the pressure generated during combustion process is a measure of the reactivity of the material system. Reactivity rate tests were performed in a closed volume using a typical mass of 20 mg in a milli-well with a packing density of 0.33g/cm3. Among the conventional nanothermites studied in this work, CuO-Al system possesses the highest reactivity. The rate of pressure increase is about 3.23MPa/�s and the peak pressure recorded is 40MPa. In comparison, it is 0.01MPa/s for Fe2O3/Al nanocomposite. The reactivity of self-assembled CuO nanorod (NR) - Al nanoparticle composite (3.81 MPa/�s) is higher than that of the one prepared by random mixing of CuO NR and Al nanoparticle (3.23MPa/�s). The CuO NR � Al based conventional nanothermites were modified by mixing with low-grade explosives, such as ammonium nitrate (AN) nanoparticles. These nanoparticles were prepared by employing microemulsion route. The reactivity increases to about 250 MPa/�s and the peak pressure to 600 MPa for the modified thermite composition with 60 % AN nanoparticles. Mixing of micron size AN particles reduced the reactivity drastically. Our studies clearly show that nanoscale mixing of thermites with explosives is necessary to enhance the reactivity of the mixture. More »»

2007

S. Apperson, Bezmelnitsyn, A., Dr. T. Rajagopalan, Tappmeyer, D., Chen, Z., Gangopadhyay, K., and Gangopadhyay, S., “Characterization Of Shock Waves Produced By Nanothermites”, in The 2007 Annual Meeting, 2007.

2007

Dr. T. Rajagopalan, Apperson, S., Bezmelnitsyn, A., Gangopadhyay, K., Gangopadhyay, S., Redner, P., Balas, W., Kapoor, D., and Nicolich, S., “Reduced Electrostatic Discharge Sensitivity Of Nanothermites”, in The 2007 Annual Meeting, 2007.[Abstract]


Nanoenergetic materials with very high combustion speeds are ideal for use as green primers, kinetic rods, and reactive materials. However, their high sensitivity to ESD remains a major challenge for practical applications. These static sensitive materials may cause accidental ignition posing a major safety hazard. It is known that Al nanoparticles are typically used as the fuel component along with nano-sized metal oxides as oxidizers to prepare nanothermites. These Al nanoparticles are highly sensitive to the ESD, thereby making nanothermites vulnerable to ignition at extremely very low ESD energy. We explore the possibility of reducing the ESD sensitivity of Al nanoparticles through coating with fluoropolymers such as Teflon. Teflon being an energetic fluoropolymer is expected to sustain the reactivity of nanothermite while helping to reduce the ESD sensitivity. Well dispersed Al nanoparticles in Teflon were obtained by coating the surface of Al nanoparticles first with perfluorooctal mono-functional trimethoxy silane and then with teflon AF solution. Our measurements show that uncoated Al nanoparticles have a very low ESD energy of 0.98mJ. On the other hand, Al nanoparticles coated with 1 and 2 % of teflon have ESD energy 2.6 mJ and 4.7 mJ respectively. With increasing teflon weight to 4% and 10 %, the ESD energy increases to 25 mJ and 60mJ respectively. We have also studied the combustion properties and reactivity of the Teflon coated nanoparticles with copper oxide nanorods. Although there is a reduction in the burn rate due to Teflon coating, the peak pressure and reactivity of the material increases with the increase in percent of Teflon coating. In conclusion, our results clearly demonstrate that coating with fluoropolymers is very effective in reducing the ESD sensitivity of nanothermite materials. More »»

2006

M. Jin, Boolchand, P., Dr. T. Rajagopalan, and Chopra, K. L., “Giant photocontraction effects in obliquely-deposited chalcogenide glass thin-films”, in APS Meeting Abstracts, 2006.[Abstract]


GexSe1-x thin-films at several obliqueness angles α (= 0, 20, 45, 60, 80) and compositions x ( = 0.15, 0.20, 0.23, 0.25 and 0.33) were vapor-deposited, and examined in Raman scattering and SEM measurements both in the pristine and illuminated state. The films, placed in an inert ambient, were exposed to Hg lamp radiation, and photo-contraction of the films established using a profilometer. Raman scattering of the pristine and exposed films were studied as a function of depth using a confocal microscope attachment. Our results show (i) Raman scattering of the normally deposited (α = 0) films in the pristine state are similar to those of corresponding bulk glasses, (ii) obliquely deposited films at x = 1/3 reveal Raman lineshapes that change qualitatively with α, suggestive of nanoscale phase separation of the films, while those at x = 0.23 show Raman lineshapes that are largely independent of α, (iii) the photocontraction effect maximizes in the 0.20 More »»

2004

S. Gangopadhyay, Lahlouh, B., Dr. T. Rajagopalan, Biswas, N., Mehta, N., and Lubguban, J. A., “Creating Voids by Annealing a-SiC: O: H Films Prepared by Plasma-enhanced Chemical Vapor Deposition”, in APS March Meeting Abstracts, 2004.[Abstract]


Hydrogenated amorphous silicon carbide (a-SiC:H) films were prepared by plasma-enhanced chemical vapor deposition from diethylsilane (C4H12Si) diluted in methane (CH4). The deposition conditions resulted in a highly unstable a-SiC:H film, which reacted with oxygen when exposed to air, forming Si-OH and H-OH bonds and Si-O networks as well. The Rutherford Back Scattering analysis shows 15incorporation. The Fourier transfom infra-red (FT-IR) measurement suggests the presence of a-SiC:O:H component and a-C:H moieties throughout the film. The films were then thermally annealed in vacuum at 450C to removed unstable C-H bonds and Si-OH and H-OH groups creating voids in the film. The removal of C-H, Si-OH and H-OH is evident from the FT-IR spectra. During the annealing process, the film also cross-links and formed a stable a-SiC:O:H film. After annealing, the dielectric constant of the films decreased from 4.2 to 2.1 suggesting the presence of voids/pores in the films. More »»

2003

B. Lahlouh, Dr. T. Rajagopalan, Lubguban, J., Biswas, N., Gangopadhyay, S., Sun, J., Huang, D. H., Simon, S. L., Toma, D., and Butler, R., “Supercritical Carbon Dioxide/Hexamethyldisilazane Treatment of Plasma-Damaged Low Dielectric Constant Films”, in APS Meeting Abstracts, 2003.[Abstract]


Etching, ashing and cleaning are very essential processes in semiconductor manufacturing. During these processes porous low dielectric constant (low-k) materials can be heavily damaged with a concomitant increase in dielectric properties. Fourier transform infrared spectroscopy (FTIR) measurements of the nanoporous films exposed to these manufacturing processes show that the methyl groups in these films were replaced by the silanol group during the plasma process. The highly polar silanol group increases the film's dielectric constant and makes the film more hydrophilic. In this work, supercritical carbon dioxide (SCCO2) with hexamethyldisilazane (HMDS) is used as a potential treatment to fix the plasma-damaged porous low-k films. Comparing the FTIR spectra for the films before and after SCCO2/HMDS treatment shows that it was successful in replacing silanol groups with methyl groups. The dielectric constant of the films was measured before and after the plasma treatment, as well as before and after the SCCO2/HMDS treatment, using CV measurements on a metal/insulator/semiconductor (MIS) structure. The dielectric constant of the plasma-damaged films was 3.71. When the sample was treated with SCCO2/HMDS, the dielectric constant decreased to 2.49. The dielectric constant and the FTIR measurements of the SCCO2/HMDS treated samples are comparable to those of the undamaged films. More »»

2003

J. A. Lubguban, Lahlouh, B., Biswas, N., Dr. T. Rajagopalan, and Gangopadhyay, S., “Selective Extraction of Porogens in Hybrid Films by Supercritical Carbon Dioxide”, in APS Meeting Abstracts, 2003.[Abstract]


The need for low dielectric constant materials with k More »»

Publication Type: Conference Proceedings

Year of Publication Title

2015

Dr. T. Rajagopalan, Gangopadhyay, K., Staley, C., and Gangopadhyay, S., “Experimental and Computational Studies Towards Combustion Characteristics of Novel Nanoenergetic Materials”, CAMX 2015 - Composites and Advanced Materials Expo, Annual Composites and Advanced Materials Expo, CAMX 2015; Dallas Convention Center Dallas. United States, 2015.

2008

Dr. T. Rajagopalan, Bezmelnitsyn, A., Shub, M., Apperson, S., Gangopadhyay, K., Gangopadhyay, S., Anderson, P., and Balas, W., “Production and Characterization of Silicon Nanostructures for the advancement of Novel Energetic Formulations”, Proceedings of the Army Science Conference (26th). Orlando, Florida, 2008.[Abstract]


This paper details the synthesis and characterization of Silicon (Si) nanostructured&nbsp;powder with a wide variety of morphologies such as nanoparticles, nanowires, nanotubes etc., produced by DC plasma arc discharge route. These nanostructures were synthesized by controlling the synthesis parameters such as current, voltage, catalyst, gas pressure, etc The structural, morphological and vibrational properties were investigated using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, nitrogen

More »»

2008

S. Apperson, Dr. T. Rajagopalan, Bezmelnitsyn, A., Gangopadhyay, K., Gangopadhyay, S., and Polo-Parada, L., “Nanothermite-Based Microsystem for Drug Delivery and Cell Transfection”, Proceedings of the Army Science Conference (26th). Orlando, Florida, 2008.

2006

Dr. T. Rajagopalan, Levi-Kalisman, Y., and Regev, O., “A Simple Route to the Preparation of High Aspect Ratio Cadmium Sulfide Nanostructures In Aqueous Solution”, Proceedings of the Eastern Mediterranean Chemical Engineering Conference (EMMC4). Dead Sea, Israel, 2006.

Publication Type: Patent

Year of Publication Title

2015

S. Gangopadhyay, Chung, S. W., Dr. T. Rajagopalan, Staley, C. S., Gangopadhyay, K., and Raymond, K. E., “Hierarchical self-assembled energetic materials and formation methods”, 2015.

2014

ShubhraGangopadhyay, StephenChung,, Dr. T. Rajagopalan, Staley, C., and KeshabGangopadhyay, “HierachicalSelf-Assembled Compositesof Functionalized GrapheneSheets-NanothermiteMaterialSystemswith Enhanced Combustion Characteristics”, 2014.

2012

S. Gangopadhyay, Tappmeyer, D., Bezmelnystin, A., Dr. T. Rajagopalan, Shende, R., Mehendale, B., Apperson, S., Barizuddin, S., and Gangopadhyay, K., “Homogeneous mesoporous nanoenergetic metal oxide composite fabrication methods”, 2012.

2011

S. Gangopadhyay, Apperson, S., Gangopadhyay, K., Dr. T. Rajagopalan, and Bezmelnitsyn, A., “Nanothermite thrusters with a nanothermite propellant”, 2011.

2011

S. Gangopadhyay, Apperson, S., Gangopadhyay, K., AndreyBezmelnitsyn,, Dr. T. Rajagopalan, Kraus, M., RajeshShende,, Hossain, M., Subramanian, S., Bhattacharya, S., and Gao, Y., “Shockwave and Power Generation using On-chip Nanoenergetic Material”, 2011.

2008

S. Gangopadhyah, Dr. T. Rajagopalan, Bezmelnytsin, A., Apperson, S., and Gangopadhyay, K., “Reducing electrostatic discharge ignition sensitivity of MIC materials”, 2008.[Abstract]


The invention provides metastable intermolecular composites that have good thermite properties while also being relatively insensitive to electrostatic discharge ignition. A preferred embodiment metastable intermolecular composite has a metal oxide nanostructure, which can be coated with an energetic polymer via a molecular linker or loaded with a gas generating polymer. Metal fuel nanoparticles coated with an energetic polymer via a molecular linker are closely associated with said metal oxide nanostructure. Methods of making metastable intermolecular composites are also provided by the invention. More »»

Publication Type: Thesis

Year of Publication Title

2001

Dr. T. Rajagopalan, “STUDY OF STRUCTURAL AND OPTICAL PROPERTIES OF AS-DEPOSITED AND THERMAL/LASER ANNEALED GeBiSe THIN FILMS”, INDIAN INSTITUTE OF TECHNOLOGY, DELHI, 2001.[Abstract]


Phase change optical recording (PCOR) medium is considered as a potential replacement for conventional magnetic recording medium due to its large data storage and archival stability. The basic principle of PCOR is based on the r&versible switching of the structure, usually, between amorphous and crystalline states using the heat of a focused laser beam. The difference in optical reflectivity of these states, defined as optical contrast, is utilized to know the data status ('0'or'1'). For a material to be an ideal PCOR medium it. More »»

Presentations at Conferences

  1. Naadaa Zakiyyan, Biyan Chen, Matthew Riehn, Aaron Wood, Sangho Bok, Rajagopalan Thiruvengadathan, Cherian Mathai, Syed Barizuddin, Keshab Gangopadhyay, Matthew Maschmann, and Shubhra Gangopadhyay, “Laser Ignition on Aluminum-Polymer Nanoenergetic Systems Using Plasmonic Gratings” (Accepted for MRS Fall Meeting 2017)
  2. Anqi Wang, Sangho Bok, Rajagopalan Thiruvengadathan, Cherian Mathai, Syed Barizuddin, Keshab Gangopadhyay, Matthew Maschmann, and Shubhra Gangopadhyay, “Synthesis and Characterization of a 3D-Macroscale RGO/Al/Bi2O3 Nanoenergetic Organogel” (Accepted for MRS Fall Meeting 2017)
  3. Naadaa Zakiyyan, Rajagopalan Thiruvengadathan, Haisheng Zheng, Angi Wang, Keshab Gangopadhyay Matthew Maschmann and Shubhra Gangopadhyay, “Hierarchical Assembly of Molybdenum Trioxide 2D Sheets and Aluminum Nanoparticles” Poster presented at MRS Spring Meeting 2017 held at Phoenix, Arizone on April 17 -21, 2017.
  4. Naadaa Zakiyyan, Haisheng Zheng, Connor Wolenski, Angi Wang, Brandon Smith, Rajagopalan Thiruvengadathan, Keshab Gangopadhyay, Matthew Maschmann, Shubhra Gangopadhyay,
    2D MoO3 Processing by Top Down and Bottom Up Techniques and Enhanced Combustion of 2D MoO3/Al Energetic Composites”, Presented at EMRS Spring Meeting 2017 under the symposium “Processing, characterization, modelling and applications of nanoenergetic materials (Energy Session) held at Strasbourg (France), from May 22 to 26, 2017.
  5. “Miniaturized Nanoenergetic Divergence Thrusters for Impulsive Projectile Control, (Honorable Mention) Nanotechnology for Defense Conference (NT4D), Tucson, Arizona, 2013.
  6. W.Chung,RThiruvengadathan,C.S.Staley,K.E.Raymond,KGangopadhyay, and S Gangopadhyay, “Functionalized Graphene for Formation of Self-Assembled Nanoenergetic Composites with Enhanced Combustion Performance” (Best PosterAward),Nanotechnologyfor DefenseConference(NT4D),Summerlin, Nevada,2012.
  7. Staley, K. Raymond, R. Thiruvengadathan, R. Taylor, S. Swaszek, K. Gangopadhyay, and S. Gangopadhyay, “Fast Impulse Nanothermite Miniaturized Thrusters”Nanotechnology for Defense Conference (NT4D), Summerlin, Nevada, 2012.
  8. ShramikSengupta,RajagopalanThiruvengadathan,Byung-DooLee,BrandonM. Smith,Sachidevi Puttaswamy,Keshab Gangopadhyayand Shubhra Gangopadhyay,Ultra-Rapid EliminationofBiofilmsOn Metal and Ceramic SurfacesViatheCombustionofa NanoenergeticCoating,2011AIChE Annual Meeting.
  9. S. Apperson, R. Thiruvengadathan, A. Bezmelnitsyn, S. Gangopadhyay, and L. Polo-Parada, “Nanothermite-based microsystem for drug delivery and cell transfection”, Presented in APS Shock Compression of Condensed Matter, AIP Conference Proceedings 1195, 2009, (Nashville, TN).
  10. RajagopalanThiruvengadathan,AndreyBezmelnitsyn, MaximShub, Steven Apperson, KeshabGangopadhyay, Shubhra Gangopadhyay, Paul Anderson and WendyBalas, “ProductionAndCharacterizationofSiliconNanostructuresforThe AdvancementofNovelEnergeticFormulations”,Oral Presentationatthe26thArmy ScienceConference, to beheld at Orlando,Florida,December1-4,2008.
  11. S. Apperson, R. Thiruvengadathan, A. Bezmelnitsyn,K. Gangopadhyay, S. GangopadhyayandL. Polo-Parada, “Nanothermite-BasedMicrosystemforDrug DeliveryandCellTransfection”,PosterPresentationatthe26thArmyScience Conference,tobeheldatOrlando,Florida,December 1-4,2008.
  12. SteveApperson,Luis Polo-Parada,RajagopalanThiruvengadathan,Keshab Gangopadhyay, andShubhraGangopadhyay, “Nanothermite-Based Micro- ImpulseGeneratorforCellTransfectionandParticleDelivery”,Posterpresented attheGordonResearchConferenceonEnergeticMaterialsheldonJune15-20, 2008,TiltonSchoolTilton, NH.
  13. SteveApperson,Andrey Bezmelnitsyn,RajagopalanThiruvengadathan,Keshab Gangopadhyay,Wendy Balas,PaulAnderson,SteveNicolich,andShubhra Gangopadhyay,“NanothermiteCharacterization:Reactivityand Mini/Micro- ThrusterPerformance”Poster presentedat theGordonResearchConferenceon Energetic Materialsheld onJune15-20,2008,TiltonSchoolTilton,NH.
  14. PEAnderson,WBalas,RThiruvengadathan,AVBezmelnitsyn,KGangopadhyay, S Gangopadhyay, ”SensitivityandPerformanceof Solution-phasesynthesizedNanothermiteMaterials” , International Annual Conference- FraunhoferInstitutFur ChemischeTechnologie,Volume39 (2008).
  15. DanielTappmeyer,Maxim Shub,Rajagopalan Thiruvengadathan,Andrey Bezmelnitsyn,Keshab Gangopadhyay,SteveApperson,and Shubhra Gangopadhyay, “Electric Arc Production of Nanoparticles for Energetic Materials”,PosterPresentation, NationalAIChEConference,Philadelphia,PA, November16-21,2008.
  16. Daniel Tappmeyer,RajagopalanThiruvengadathan,AndreyBezmelnitsyn,Steven Apperson,KeshabGangopadhyay,ShubhraGangopadhyay,PaulRedner, Wendy Balas, Deepak KapoorandSteven Nicolich “NovelNanoenergetic Material Using PorousCopperOxideNanoparticlesand Aluminum Nanoparticles”,2007AIChE Annual Meeting
  17. SteveApperson, AndreyBezmelnitsyn,RajagopalanThiruvengadathan,Dan Tappmeyer,ZhenChen, KeshabGangopadhyay,,ShubhraGangopadhyay,Paul Redner, WendyBalas,DeepakKapoor, andStevenNicolich,“Characterizationof Shock WavesProducedByNanothermites”,Presentedatthe“Nano-Energetic Materials”technicalsession of 2007AIChEAnnual Meeting heldat SaltLake City, Utah onNovember4-9,2007.
  18. AndreyBezmelnitsyn,RajagopalanThiruvengadathan,SteveApperson,Rajesh Shende,KeshabGangopadhyay,ShubhraGangopadhyay, Paul Redner,Wendy Balas,DeepakKapoor, andStevenNicolich,“ReactivityofConventionaland ModifiedNanothermites”,Presentedat the“Nano-EnergeticMaterials”technical session of 2007 AIChE Annual Meeting held at Salt Lake City, Utah on November4 -9,2007.
  19. RajagopalanThiruvengadathan,SteveApperson,AndreyBezmelnitsyn,Keshab Gangopadhyay,ShubhraGangopadhyay, Paul Redner,WendyBalas,Deepak Kapoor,andStevenNicolich.,“ReducedElectrostatic DischargeSensitivityOf Nanothermites”,Presentedatthe“Nano-EnergeticMaterials”technicalsession of 2007AIChEAnnualMeetingheldat SaltLakeCity,Utahon November4-9, 2007.
  20. OrenRegev,Rajagopalan ThiruvengadathanandAttalShay,“Evaluation of NanotubesConcentration in Solution via UV-VisibleSpectroscopy”.SESSIONEE7: PosterSession: NanotubesandNanowires;Spectroscopic PropertiesandMedical andClinicalApplications,SymposiumEE:Applicationsof Nanotubesand Nanowires,April9-13,2007.ProceedingsMRSSpringMeeting,SanFrancisco, CA held onApril9- 13,2007.
  21. Vered Weiss, Rajagopalan Thiruvengadathan and Oren Regev, “Carbon Nanotubes-LyotropicLiquidCrystalComposite”Poster presentedat the Jubilee NanotechnologySymposiumheldatBarIlanUniversity,RamatGan, ISRAELheld onMay 29– 31,2006.
  22. M.Jin,P.Boolchand,T. RajagopalanandK.L. Chopra, “Giantphotocontraction effects inobliquely-depositedchalcogenideglassthinFilms”,Presentedat the American Physical Society (APS) Meeting held on March 13–17, 2006 at Baltimore,MD, USA
  23. RajagopalanThiruvengadathan,YaelLevi-KalismanandOrenRegev, “A Simple Route to the Preparation of High Aspect Ratio Cadmium Sulfide Nanostructures inAqueous Solution”,PresentedatEastern MediterraneanChemical Engineering Conference(EMMC4) heldonJanuary9-11,2006atDeadSea,Israel.
  24. V. Korampally; M.R. Monique; S. Gangopadhyay and T. Rajagopalan, Semiconductor Quantum Wires ThroughOrdered Mesoporous Silica Templating, Posterpresentedat52nd MidwestSolidStateConferenceheldonOct8–9, 2005at Columbia,MO,USA.
  25. Rajagopalan Thiruvengadathan and Oren Regev, “CdS Nanostructures Templated by MesoporousSBA-15Silica”,Posterpresentedat the25thGIF Meeting:NanotubesandNanowiresDresden(Germany),20– 23June2005.
  26. Rajagopalan Thiruvengadathan and Oren Regev, Hierarchically Ordered Cadmium SulfideNanowiresdispersed in AqeuousSolution,OralPresentation at the41AnnualMeetingofIsraelInstituteof Chemical Engineers(IIChE2005),Tel Aviv (Israel) 9June2005.
  27. S. Gangopadhyay,J.A. Lubguban,B. Lahlouh,G. Sivaraman,K.Biswas, T.Rajagopalan,N.Biswas,H.-C. Kim,W.VolksenandR. D. Miller,“Supercritical CO2Treatments for Semiconductor Applications”,OralPresentationMaterials ResearchSymposium ProceedingsVol.812F 4.6.1-F4.6.6 Materials,Technology andReliability forAdvancedInterconnectsand Low-k Dielectrics) MRS Spring Meeting,SanFrancisco,CA2004.
  28. S. Gangopadhyay, B. Lahlouh, T. Rajagopalan, N. Biswas, N. Mehta and J. A. Lubguban,“CreatingVoidsbyAnnealinga-SiC:O:HFilmsPreparedbyPlasma- enhanced Chemical Vapor Deposition”, Oral Presentation at the American PhysicalSociety (APS) Spring Meeting heldatPalais desCongres deMontreal, Montreal,Quebec,Canada, March22-26,2004.
  29. J.A.Lubguban,B.Lahlouh,G.Sivaraman,K.Biswas,M.R.Ali,T.Rajagopalan,J. Sun, D.H.Huang,N. Biswas,S.L.Simon,R.Gale,LatikaMenon,and S.Gangopadhyay, “Supercritical CO2 Treatments ofPlasma-DamagedPorous Films”,OralpresentationPaperpresentedattheSecondInternational Surface CleaningWorkshop,Boston,MA,November 9–12,2003.
  30. B. Lahlouh,T.Rajagopalan,J.A. Lubguban, N. Biswas,S.Gangopadhyay,J. Sun, D. Huang,S.L. Simon,H.C. Kim,W. Volksen,andR.D. Miller, “Creating nanoporositybyselectiveextraction ofporogensusing supercritical carbon dioxide/cosolventprocessesin Materials”,OralpresentationTechnologyand Reliability for AdvancedInterconnectsandLow-kDielectrics—2003,editedbyA.J.McKerrow, J.Leu,O.Kraft,andT.Kikkawa(Mater.Res.Soc.Symp.Proc.766,Warrendale, PA,2003,p. 291.
  31. B.Lahlouh, N.Biswas,T.RajagopalanJ. LubgubanandS.Gangopadhyay,“Selective Extraction ofPorogensin Hybrid FilmsbySupercriticalCarbon Dioxide”Oral PresentationattheAmericanPhysicalSociety (APS) Spring Meeting heldat Austin,TXonMarch3–72003.
  32. B. Lahlouh, Rajagopalan, J.Lubguban, N.Biswas, S.Gangopadhyay, J.Sun, D. Huang, S.L.Simon, D.Tomaand R.Butler, “Supercritical Carbon Dioxide/HexamethyldisilazaneTreatmentofPlasma-DamagedLow DielectricConstant Films”,Oral presentation,AmericanPhysicalSociety(APS)SpringMeetingheldatAustin,TXonMarch 3–72003.
  33. S.Gangopadhyay, J.Lubguban, T.Rajagopalan, B.Lahlouh, J.Sun, D.Huang, S.L.Simon,W.Volksen, H.C.KimandR.D.Miller, “SupercriticalCarbonDioxide ProcessforFormingNanoporousDielectrics”OralPresentation, workin collaborationwithIBM,AlmadenResearchCenter,SanJose,CAattheUltra-Low KworkshoporganizedbyInternational SEMATECHatSanFrancisco,CA, USAon June6-7,2002.
  34. S.Gangopadhyay, T.Rajagopalan, B.Lahlouh, J.Lubguban, J.Sun, D.Huang, S.L.Simon,D.Tomaand R.Butler, “HMDS/SupercriticalCarbon DioxideTreatment ofPlasma DamagedNanoporousLowk Films”,Oral presentationTheFirst InternationalSurfaceCleaningWorkshopheldatBoston,MAonNov11–14, 2002.
  35. D.Toma, M.Biberger, R.Butler, J.Sun,T.Rajagopalan, B.Lahlouh, D.Huang, J.Lubguban, S.L.SimonandS.Gangopadhyay,UseofSCCO2Processing for IntegrationandFormationofUltra-LowKDielectrics;OralPresentation,at the Ultra-Low K workshop organized by International SEMATECH atSanFrancisco,CA, USAonJune6-7,2002.
  36. T.RajagopalanandG.B.Reddy,“FormationofhighlyorientedGeBiSeFilmsfrom As-depositedAmorphousStatebyAnnealing”,Oral presentation atThe International Conference on Metallurgical Coatings and Thin Films (ICMCTF 2000)heldatSan Diego,CA, USAon10-14 April2000.