Electrical properties of bismuth germanate (Bi2GeO5) ferroelectric glass-ceramics prepared by two different methods

Abstract

Ferroelectric Bi2GeO5 glass-ceramics were fabricated using conventional and incorporation method. Glasses have been prepared from BiO1.5-GeO2-BO1.5 ternary glass system by focusing on the region of 59 mol%BiO1.5: 23 mol%GeO2: 18 mol%BO1.5. The resulting glass was analyzed by using differential thermal analysis (DTA) for determining the crystallization temperature (Tp). Then, the prepared glass pieces were heat treated at Tp. Effects of different fabrication methods on structure and electrical of the glass-ceramics were investigated. X-ray diffraction result of all glass-ceramics suggested that the main peak of glass-ceramics matched the orthorhombic structure of the pure Bi2GeO5 phase. Microstructures of the prepared glass-ceramics have been found to change from rod-like crystallites to bulk crystallites on modifying the fabrication method. The Bi2GeO5 glass-ceramics prepared by incorporation method presented higher dielectric constant than those of the Bi2GeO5 glass-ceramics prepared by conventional method. Moreover, the Bi2GeO5 glass-ceramic prepared by incorporation method possesses a large value of Pmax (0.94 µC/cm2) comparing to that of the glass-ceramics prepared by conventional method (Pmax = 0.73 µC/cm2). Thus, this study suggests that the incorporation method can effectively modify the microstructure of Bi2GeO5 glass-ceramics, resulting in the improvement of dielectric and ferroelectric properties.