Structural Features of Mineral Crystalline Phases and Defectiveness of Bismuth Organosiliconate Crystals at High Temperatures

Resumo

Structural features of mineral crystal phases and defectiveness of bismuth organosiliconate crystals are inspected at various temperatures of treatment (from 100 to 500°C). X-ray diffraction enables evaluation of crystal lattice periods from spectrograms recorded in СuK_α radiation. The approximation analysis of the broadening of the most intense diffraction lines in crystals from (hkl) crystallographic indices allows one to determine the coherent domain sizes and microdistortions Δа/а of a crystal lattice. It is found that exposure of the Na₂O–Bi₂O₃–SiO₂ system (NBS material) to temperatures of 300–500°C leads to a decrease in amorphism, microdistortions, and the density of dislocations in a crystal lattice of Bi₁₂SiO₂0 sillenite. The formation of a denser structure of sillenite crystal with higher X-ray density (9.210 g/cm³) and greater cubic crystal lattice parameter (a = 10.1335 Å) is detected. The presented Bi₁₂SiO₂₀ material can be used as a gamma and protective filler of radiation protective polymers and in the design of electro-and magneto-optical laser radiation modulators.