A. I. Ignat’ev

Formation of silver nanoparticles in photothermorefractive glasses during electron irradiation

The formation of silver nanoparticles in photothermorefractive glasses during electron irradiation and subsequent heat treatment is experimentally studied. The optical density spectra of samples at various stages of heat treatment are compared. The formation of metallic nanoparticles is shown to occur during both electron irradiation and subsequent heat treatment. Nanoparticles are localized in layers parallel to the surface. At the initial stage of nanoparticle formation, the key role is played by the appearance of a negative bulk charge in the near-surface layer in glass, which results in the field-assisted migration of positive metal ions and a characteristic layered distribution of metallic nanoparticles in the glass volume.

Influence of UV irradiation and heat treatment on the luminescence of molecular silver clusters in photo-thermo-refractive glasses

The luminescence spectra of photo-thermo-refractive (PTR) glasses containing cerium, silver, and antimony ions before and after UV irradiation and after heat treatment have been thoroughly investigated for the first time. It is shown that silver is present in the initial PTR glass in the form of ions and positively charged molecular clusters. After UV irradiation into the absorption band of cerium ions, silver partially passes to the neutral state in the form of atoms and neutral molecular clusters Ag2, Ag3, and Ag4, which exhibit bright luminescence in the visible spectral range. Subsequent heat treatment at a temperature below the glassformation temperature leads to an increase in the luminescence intensity due to the increase in the concentration of neutral molecular clusters. Heat treatment at a temperature above the glass-formation temperature leads to the formation of silver nanocrystals and luminescence quenching. It is proposed to use PTR glasses with molecular silver clusters as phosphors for converting UV radiation into the visible range for solar power engineering and white LEDs.

Holographic characteristics of a modified photothermorefractive glass

The spectral and holographic characteristics of classical and modified photothermorefractive glass are compared. It shows that modified photothermorefractive glass has no additional absorption bands in the blue–green region, as is the case in classical photothermorefractive glass. This makes it possible to record purely phase holograms in modified photothermorefractive glass. The refractive-index increment is a factor of 2 greater in modified photothermorefractive glass than in classical photothermorefractive glass.

Spectral components that form UV absorption spectrum of Ce3+ and Ce(IV) valence states in matrix of photothermorefractive glasses

We have measured the UV absorption spectra of photothermorefractive glasses of the system Na2O-ZnO-Al2O3-NaF-SiO2 doped by cerium oxide in the range of (2.8–5.0) × 104 cm−1 (360–200 nm). The spectra have been processed by the method of dispersion analysis based on the analytical convolution model for the complex dielectric function of glasses. We show that the absorption band centered at 3.3 × 104 cm−1 (∼303 nm) that is attributed to the transition 2F5/2 → 5d in the Ce3+ ion, is an envelope of three spectral components. The broad absorption range (3.5–4.7) × 104 cm−1 (200–270 nm) that is commonly interpreted as a charge transfer band of the Ce(IV) valence state, is an envelope of at least three spectral components.

Specific features of the luminescence of silicate glasses with silver introduced by ion exchange

The luminescence spectra of silicate glasses with silver introduced by ion exchange have been investigated. It is shown that silver introduced into glass by ion exchange exists not only in the form of ions, but also as neutral atoms and charged and neutral molecular clusters, which provide intense luminescence in the visible spectral range. Cerium ions in glass facilitate the formation of neutral molecular silver clusters, due to which the luminescence intensity increases. It is shown that Agn-Cex+ complexes can be formed in glass containing cerium ions and neutral molecular silver clusters.

Comparison of the formation kinetics of silver nanoparticles of photo-thermo-refractive glass after ultraviolet and electron irradiation

We present experimental results on the formation of silver nanocrystals in photo-thermo-refractive glasses during heat treatment after ultraviolet and fast-electron irradiation. We compare the optical density spectrum of samples at different stages of heat treatment. We show that the difference in the formation kinetics of silver nanoparticles is determined by the spatial redistribution of silver ions during electron irradiation and the change in the chemical composition of near-surface layers of glass.

Effect of electron irradiation on the formation of silver nanoclusters in photothermorefractive glasses

The dynamics of formation of silver nanocrystals under the action of an electron beam in the near-surface layer of photothermorefractive glasses containing Ag+ ions has been experimentally studied. It is shown that the irradiation by electrons leads to the field-induced diffusion of Ag+ ions and the appearance of primary silver nanoclusters. The role of nanostructures of the core-shell type in the formation of these nanoclusters and the subsequent growth of metallic silver nanoparticles with plasmon resonances is determined.

Recording holographic marks for telescopic systems in photo-thermo-refractive glass

The basic possibility of forming a holographic image of a two-dimensional object mark in photothermo-refractive (PTR) glass is demonstrated. The parameters of a hologram in a three-dimensional medium are calculated, and a subsequent analysis of the characteristics of the recorded mark prototype is performed. The advantages are shown of PTR glass as a holographic medium in telescopic systems in comparison with existing analogs. Samples with high transmission in the visible spectral range (more than 85%) and high diffraction efficiency (more than 95%) are obtained that show all the effects inherent in holographic marks in existing telescopic systems.

Influence of halogenides on luminescence from silver molecular clusters in photothermorefractive glasses

It is shown experimentally that a rise in the sodium halogenide (NaCl, NaBr) concentration in photothermorefractive glasses increases the intensity of luminescence from silver neutral molecular clusters. Substitution of NaBr for NaCl with their concentration being the same shifts the luminescence band toward longer waves and raises its intensity. These findings can be explained by the formation of molecular clusters of type Agn-Hal (Hal = Cl, Br) in photothermorefractive glass.

Spectral-luminescent properties of silver molecular clusters and nanoparticles formed by ion exchange in antimony-doped photo-thermo-refractive glasses

The formation of silver molecular clusters and nanoparticles in photo-thermo-refractive (PTR) glasses with different antimony contents has been investigated using ion exchange with subsequent thermal treatment. The influence of the antimony oxide (Sb2O3) concentration and treatment temperature on the spectral-luminescent properties of silver molecular clusters and nanoparticles in glass has been investigated. It is shown that silver molecular clusters in PTR glasses are characterized by strong broadband luminescence in the visible and near-IR ranges and that the formation of silver nanoparticles leads to luminescence quenching.