Effect of Zr~(4+) content on the T_C range and dielectric and ferroelectric properties of BaZr_xTi_(1-x)O_3 ceramics prepared by microwave sintering

摘要

Single phase and dense BaZr_xTi_(1-x)O_3 (BZT) ceramics (x=0.05, 0.1, 0.15, 0.2, 0.25) were obtained by microwave sintering and the powders of these ceramics were synthesized by conventional hydrothermal method. The microstructural, dielectric and ferroelectric properties of BaZr_xTi_(1-x)O_3 ceramics sintered at 1300°C were investigated. The XRD analysis revealed that the synthesized compound was formed with no second phase. As x was increased from 0.05 to 0.25, the average grain size was observed on the SEM micrographs to decrease from ～6 μm to ～3 μm. The dielectric constant as a function of temperature showed a decrease in Curie temperature (T_C) with an increasing x, while the maximum value of dielectric loss occurred (tan δ) at x=0.1. A ferroelectric-relaxor crossover was observed to take place with increasing x by using the modified Curie-Weiss law. The remnant polarization (P_r) decreased from 9.45 to 4.4 C/cm~2 with an increasing x, while the maximum value of P_T= 11.84 also occurred at x=0.1. The breadth of T_C range increased rapidly when x< 0.15, but no significant difference was observed with further doping of Zr~(4+). The full width at half maximum (FWHM) was used to show the degree of the broadening in Curie peak.