Nanocrystallization of Bi2O3 based system from the glassy state under high compression

This report presents the pressure-temperature (p-T) plane of Bi2O3-Al2O3-SiO2 ternary system in the context of nanocrystallite formation from its amorphous state. The diagram was constructed through differential thermal analysis (DTA) performed in situ under high-pressure-high-temperature (HP-HT) conditions, with nitrogen serving as the pressurizing medium. Above the glass transition temperature Tg, a wide ultraviscous, supercooled liquid state spanning approximately 150 K is observed. Later heating transforms this state into nanocrystallites embedded within an amorphous matrix, thereby keeping distinctive structural characteristics even after the decompression process. The p-T plane serves as a fundamental prerequisite for the design of nanocrystallites within a glass matrix, a well-established technique known as glass-ceramics. Various paths within the p-T plane, followed by annealing just below Tg, can be explored, potentially leading to the development of Bi2O3-based materials with enhanced electrical, dielectric, photonic, and mechanical properties, predicated on nano-crystallites formed by high-pressure treatment.