Publication

Abstract : This study reports the synthesis, characterization, and multi-performance evaluation of Dy3+-doped Sr2MgSi2O7 (SMSDx; x = 1, 3, 5, 7, and 9 mol%) nanophosphors prepared via a solution auto-combustion method using Aloe vera gel as fuel. Rietveld-refined PXRD patterns showed a dominating tetragonal phase (P-421 m, JCPDS Card No. 42-0932) next to a minor monoclinic phase (P21/a, JCPDS Card No. 75-1736) with no notable peak shifts but varying intensity, suggesting effective Dy3+ replacement. While HRTEM projected an interplanar d-spacing of 0.285 nm, FESEM and TEM studies found quasi-spherical particles in the 29.85 nm range. Sr2+, Mg2+, Si4+, O2−, and Dy3+'s existence and oxidation states were verified by XPS and EDS. Increasing dopant concentration adjusted optical band gap values from 4.76 eV to 4.80 eV; Raman spectra showed changes in Si–O–Si and Mg–O vibrational modes caused by local lattice distortion. With SMSD3 displaying the greatest intensity, photoluminescence experiments under 352 nm excitation showed strong emissions at 483 nm (4F9/2 → 6H15/2), 575 nm (4F9/2 → 6H13/2), and 662 nm (4F9/2 → 6H11/2). With a Q-value of about 6, showing dipole–dipole interaction, Dexter's hypothesis verified the concentration quenching process. Suitable for cool white-light phosphors, chromaticity study put all samples in the yellow-to-near-white area with CCT values between 4500 and 6000 K. A DOS study indicates that the interactions between the oxygen 2p and metal d orbitals govern the transitions. Additionally, DFT calculations revealed distinct electrical properties for each phase, with phase I exhibiting a direct band gap of 4.602 eV, while phase II has an indirect band gap of 4.969 eV. Conventional powder dusting forensic assessment revealed obvious Type-III level latent fingerprint visibility on surfaces, including ceramic, glass, and metal. Electrochemical sensing through CV and impedance studies, using SMSD-modified SPCEs revealed significant redox response, especially for SMSD9, with anodic/cathodic peaks at 0.57 V/0.31 V and large current densities for paracetamol oxidation, verifying diffusion-adsorption controlled two-electron, two-proton transfer. The Liner dynamic range (LDR) and limit of detection obtained for paracetamol were 0–10 μM and 0.2945 μM respectively. The sensor demonstrated commendable recovery (∼92.4 %) for paracetamol from acidified real water samples over a 15-day period, confirming its precision, dependability, and short-term operational stability in practical settings. The results show SMSDx nanophosphors as flexible nanophosphors linking luminous, forensic, and electrochemical domains—providing a hopeful answer to the rising need for application-integrated multifunctional materials.