Localized Surface Plasmon Absorption and Photoluminescence of In Situ-Generated Nano Silver in a Novel Chloroborosilicate Glass and Glass Ceramics

Abstract

Silver (Ag) nanoparticles (NPs) have been generated in situ in a novel chloroborosilicate glass system SiO2–B2O3–BaO–K2O–Al2O3–BaCl2 in the presence of a small amount of SnO as a reducing agent. The glass–metal nanocomposite has been synthesized by a single-step melt-quenching technique followed by a carefully designed heat treatment schedule. Absorption and photoluminescence properties have been studied before and after matrix crystallization along with the progress of heat treatment. The x-ray diffraction and transmission electron microscopy confirms the crystallization of the glass matrix at higher temperature. Both UV–Vis absorption and photoluminescence (PL) spectra of the samples reveal the formation of Ag NPs. Multiple peaks in the UV–Vis absorption spectra of Ag-doped samples have been explained by combined surface plasmon resonance and highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) of inter (d–sp) and intra (sp–sp) band transitions. The observed PL bands have been considered to be originated from the radiative decay of the surface plasmon resonance and inter-band (sp–d) LUMO-HOMO transitions. The PL intensity is found to increase with heat treatment up to 40 min, and then, decreases. This indicates that when larger than a certain size limit of nano silver (∼6.5 nm), they are not photoluminescent. Crystallization of glass matrix has also a significant effect on the PL intensity and intensity distribution of different emission bands along with band shapes. These nanocomposites are promising materials for various nanophotonic applications as revealed in their different properties.