Correlation between dielectric relaxation time and piezoelectric property in Ba1-xCaxZr0.1Ti0.9O3

Abstract

The Ba1-xCaxZr0.1Ti0.9O3 (BCZT) material system (with x=0.075-0.175) was fabricated by the solid-state reaction method at a sintering temperature of 1450oC for 4 hours. The results of structural analysis by X-ray diffraction (XRD) showed that different phase structures of typical BCTZ materials coexist in the material system. When the Ca doping ratio increased above 17.5%, an additional CaTiO3 structural phase appeared in the material sample. The results of impedance analysis at frequencies in the range of 100-2.5 MHz at room temperature and dielectric relaxation time for all samples in both disc and cylindrical shapes showed that the impedance and dielectric relaxation time tended to decrease as the Ca ratio increased. These results showed that substituting Ca2+ ions in place of Ba2+ ions significantly affected the dielectric relaxation time and piezoelectric properties of BCZT samples. The piezoelectric properties were improved and optimised at 15% Ca doping concentration, where the dielectric relaxation time had the smallest value. The relationship between the dielectric relaxation time and piezoelectric properties was found to be related to the coexistence of structural phases in the morphological phase boundary region as demonstrated by XRD results.