Spectral Properties of Composite Materials Based on Nanoporous High-Silica Glasses Activated by Silver and Lanthanum Ions

Abstract

Spectral properties of composite materials based on matrices of high-silica porous glasses activated by silver ions and lanthanum ions have been investigated. The optical density spectra (270–900 nm) and infrared transmittance spectra (11 000–9000 and 9000–4000 cm^–1) of composite materials of different compositions subjected to heat treatment according to one of three modes (120, 500 and 800°C) have been considered. The synthesized composite materials were investigated by X-ray powder diffraction method and energy-dispersive X-ray spectroscopy. The analysis of optical spectra permitted to identify the formation of molecular clusters, clusters, dimers and silver nanoparticles, as well as absorption bands related to charge transfer O²⁺ → La³⁺ (282, 285, 300 nm) and to lanthanum nanoparticles (282, 285 nm) under different conditions of synthesis of composite materials. It was found that the change in the mode of thermal treatment of composites leads to changes in the IR spectra of composites, and the change in their composition leads to the appearance of additional bands associated with the oxygen atom of the OH-group, which can coordinate with several neighboring lanthanum atoms.