Glasses of the K ₂ O–B ₂ O ₃ –GeO ₂ system were studied by means of Raman and IR spectroscopy.

The Raman spectra of borosilicate glass containing 35, 40, and 45 mol % of alkali-earth metal oxide (SrO and BaO) are studied. The structural changes taking place at a gradual substitution of boron oxide by silica are determined. At a high boron oxide content, transformations among borate structural units are predominant because the main part of the modifying oxide reacts with the borate network. When boron is replaced by silicon, the appearance of borosilicate ring structures is observed in alkali-earth borosilicate glass. At the ratio of SiO₂/B₂O₃ > 0.5, a part of the triborate groups and borate structural units containing nonbridging oxygen atoms decreases gradually. When SiO₂/B₂O₃ > 1, the character of the transformations among the Q ⁿ structural units changes.

Glass-containing materials are widely considered among the most reliable materials for the immobilization of radioactive waste materials. The present work considers the synthesis of glass–ceramic and glass crystalline composite materials based on borosilicate glasses. The synthesis of glass–ceramic materials was carried out by a gradual temperature decrease, followed by crystallization for several hours. Sintering of crushed samples with crystalline components was carried out as an alternative procedure. Porous glasses were produced from glass melts by quenching. After impregnating the resulting porous materials with aqueous solutions of cesium nitrate, compaction of the glass was carried out to form glass crystalline composites. The thermochemical characteristics of the parent glasses were determined using the differential scanning calorimetry method. The phase composition and structure of the glass-containing materials were determined using X-ray phase analysis, X-ray spectral microanalysis, and Raman spectroscopy.

The structural origin of the germanate anomaly in glasses, which involves complex Ge–O coordination environments, is frequently studied using crystalline analogs. This study aims to provide reliable spectroscopic fingerprints by performing a detailed structural and thermal analysis of crystalline A₄Ge₉O₂₀ model systems with A = Li, Na, K. The compounds were synthesized via melt crystallization and characterized using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), and Raman spectroscopy techniques. The results demonstrate clear cation-dependent crystallization pathways. The Li-containing system predominantly forms Li₂Ge₇O₁₅ in mixture with Li₄Ge₉O₂₀, indicating a preference for thermodynamically stable phases. The Na-system successfully yields the target Na₄Ge₉O₂₀ compound. In contrast, the K-system primarily produces the likely metastable K₂Ge₄O₉ phase with a significant amorphous fraction, highlighting the role of kinetic limitations. This comparative study demonstrates that the size of the alkali cation is a critical factor for controlling phase formation under identical stoichiometric and thermal conditions.