Influences of phase transition and microstructure on dielectric properties of Bi0.5Na0.5Zr1-xTixO3 ceramics

Abstract

Bismuth sodium zirconate titanate ceramics with the formula Bi 0.5 Na 0.5 Zr 1-x Ti x O 3 [BNZT], where x = 0.3, 0.4, 0.5, and 0.6, were prepared by a conventional solid-state sintering method. Phase identification was investigated using an X-ray diffraction technique. All compositions exhibited complete solubility of Ti 4+ at the Zr 4+ site. Both a decrease of unit cell size and phase transition from an orthorhombic Zr-rich composition to a rhombohedral crystal structure in a Ti-rich composition were observed as a result of Ti 4+ substitution. These changes caused dielectric properties of BNZT ceramics to enhance. Microstructural observation carried out employing SEM showed that average grain size decreased when addition of Ti increased. Grain size difference of BNZT above 0.4 mole fraction of Ti 4+ displayed a significant increase of dielectric constant at room temperature.