Effects of chemical modification on the structural and electrical properties of (Ba 0.90Ca 0.10) 0.90(Na 0.5Bi 0.5) 0.10TiO 3 ceramics

Abstract

The structural, dielectric and ferroelectric properties of chemical modified (Ba 0.90Ca 0.10) 0.90(Na 0.5Bi 0.5) 0.10TiO 3 (BCT-NBT) ceramics prepared through solid-state reaction technique were investigated. X-ray powder diffraction study shows that bismuth evaporation and titanium excess result in the formation of the secondary nonperovskite phase and the deterioration of the sintering ability. The excessive bismuth and titanium cause the peak dielectric constant ( K m ) decrease and the temperature of the peak dielectric constant ( T m ) shifts to lower temperature in the BCT-NBT systems. The appropriate bismuth oxide as a sintering aid leading to liquid phase sintering causes ceramics densification, increases the room temperature dielectric constant ( K) and the remnant polarization ( P r) of BCT-NBT ceramics, and decreases the dielectric loss tangent (tan δ) and the coercive field ( E c ) of the BCT-NBT ceramics. However, the excessive titanium causes a slight improvement of tan δ and E c . These results indicate that this chemical modification is necessary to synthesize BCT-NBT ceramics with better electrical properties in order to realize its practical applications.