Photoluminescence of Gallate Glass-Ceramics: Al2O3 Influence

Glass and Ceramics - The influence of Al2O3 as an additive and the heat-treatment regime on the luminescence spectra of gallate glass-ceramics was investigated. It is shown that its luminescence...     

Raman and dielectric spectra of the glass and single crystal of the composition Li2Ge7O15 in the frequency range 3–1000 cm−1: II. The influence of phase separation

The Raman spectra of Li₂O · 7GeO₂ glasses, which are heat treated under different conditions at temperatures near the temperature corresponding to the first exothermal peak in the DTA curve, are measured in the frequency range 20–1100 cm^?1. A comparative analysis of the measured spectra with the use of the data available in the literature and the X-ray diffraction results demonstrates that the glass undergoes phase separation and that phases of compositions close to GeO₂ and Li₂O · 4GeO₂ precipitate at the initial stage. The ordering of both phases varies significantly within the sample and, on the average, is substantially higher than that in the initial glass. This confirms the known assumptions made by researchers that crystal nuclei with a Li₂O · 4GeO₂ structure arise during heat treatment of lithium germanate glasses. At the phase separation stage under investigation, the phases are formed as nanoinhomogeneities that only slightly affect the transparency and, in the course of heat treatment, increase in size with a further ordering of the structure.     

Nonlinear Optic Nanocomposites Based on Oxide Glasses

The first nonlinear optic nanocomposite based on a low-melting vitreous matrix and a ferrielectric crystal has been obtained. The matrix consists of lead-borate glass and the filler is single-phase powder of ferrielectric KNbSi₂O₇. The quadratic optical nonlinearity of composites was studied depending on temperature and time of dissolution of crystals in the glass matrix. Conditions for producing transparent nanocomposites that generate the second optic harmonic are identified.     

Precision Laser Welding of Silica Glass with Iron-Nickel Alloy

Glass and Ceramics - The possibilities of strong local bonding of glasses and metals with close linear thermal expansion coefficients by means of welding using a femtosecond laser beam were...