Exploring the dielectric properties, glass ability and ferroelectric phases in the BaO-Bi2O3-TiO2-B2O3-Al2O3 system

Abstract

In this study, Bi- and Ti-rich glasses have been designed and investigated for the development of ferroelectric glass-ceramics (GCs). The glass formation range, the structure of the glass network and the crystalline phases obtained in the glass-ceramics were explored. Glass compositions within the xBaO-(90-x)(40Bi₂O₃-25TiO₂-35B₂O₃)-10Al₂O₃ system were synthesized through rapid press quenching of the melt, with a controlled melting temperature of 1000°C. Raman spectroscopy was carried out to investigate the impact of Bi₂O₃, TiO₂ and BaO on the arrangement of the structural units in these glasses. Subsequent thermal treatment in the temperature range of 500–700°C led to the formation of glass-ceramics containing the ferroelectric Bi₄Ti₃O₁₂ crystal phase in all compositions. Notably, glass-ceramics containing 10–16 mol% of BaO exhibited a single Bi₄Ti₃O₁₂ crystal phase upon complete crystallization. The microstructure and temperature-dependent dielectric properties of glasses and GCs were investigated as a function of the Ba content. The permittivity ε_r of the glasses is quite high compared to other glass systems, ranging between 22 and 28, and it is greatly increased in the crystallized samples (up to 70). Furthermore, no phase transitions up to 300 °C are observed, especially in GCs with a single Bi₄Ti₃O₁₂ crystal phase, making these materials strong candidates for energy storage dielectrics. The samples developed in this study demonstrate the potentiality of obtaining piezoelectric glass-ceramics in network former-poor matrices.