Temperature stability of dielectric properties for xBiAlO3–(1 − x)BaTiO3 ceramics

Abstract

xBiAlO3–(1−x)BaTiO3 [xBA–(1−x)BT] polycrystalline ceramics were prepared by solid-state reaction method and sol–gel method, respectively. The ceramics were in tetragonal phase when x≤0.1, transformed to pseudocubic at x>0.1. The temperature stability of the dielectric constant for BA–BT was improved with BA contents increasing. Of particular interest was that the ceramics prepared by sol–gel method had less secondary phase, exhibiting much improved dielectric behavior. Among them, 0.3BA–0.7BT met the requirement of capacitance variation (ΔC/C≤±15%) in the temperature range of −55 to 440°C with moderate dielectric constant (ɛ=660) and low dielectric loss (tanδ=1.2%) at room temperature (1kHz). Nb-doped 0.2BA–0.8BT ceramics were investigated to improve the dielectric temperature stability at high-temperature end. It is found that all samples with 0.01–0.04mol Nb addition satisfied the X8R specification.