IMPROVED SPECTRAL FEATURES OF SILVER NANOPARTICLES SENSITIZED SAMARIUM DOPED ZINC-SODIUM-TELLURITTE GLASS

Abstract

Rare earth doped inorganic glasses with enhanced up-conversion emission and absorption properties are demanding for solid state lasers. Sensitizing the local environment of dopants/co-dopants via surface plasmon resonance (SPR) mediated effects of embedded metallic nanoparticles (NPs) is demonstrated to be prospective towards such endeavor. Silver (Ag) NPs being the creator of sharp SP is incorporated into the optimized glass composition to improve its spectral features. Glasses with chemical composition TeO₂-ZnO-Na₂O-Sm₂O₃-AgCl is prepared using melt-quenching method, where the concentration of AgCl (in excess) is varied and Sm³⁺ kept constant. Synthesized glasses are thoroughly characterized via UV-Vis-NIR absorption, photoluminescence and XRD measurements. The influence of varying Ag NPs contents on the spectral features of samarium (Sm³⁺) doped zinc-sodium tellurite glasses is determined. XRD pattern confirmed the amorphous nature of as-prepared glasses. Ag NPs growth is primarily ascribed to the Ostwald ripening and coalescence processes. The absorption spectra revealed six peaks centered at 472, 943, 1089, 1237, 1392, and 1491 nm, which are allocated to 6H5/2→4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2 transitions, respectively. Furthermore, the evaluation of refractive indices, polarizability, density, molar refraction, optical band gap and Urbach energy clearly exhibited the strong participation of Ag NPs in the glass network. PL spectra showed three emission bands located at 561, 599 and 643 nm, which are assigned to 4G5/2→6H5/2, 6H7/2 and 6H9/2 transitions, respectively. The observed enhancement in PL intensity is attributed to the highly localized electric field (SPR) of Ag NPs positioned in the vicinity of Sm³⁺ ion. The mechanism of enhancement is identified, analyzed and understood via partial energy level scheme of Sm³⁺ ion. The admirable features of this glass composition are highly beneficial for solid-state laser and optical device fabrication