Study on low temperature sintering and electrical properties of CuO-doped Ca_(0.28)Ba_(0.72)Nb_2O_6 ceramics

摘要

Ca_(0.28)Ba_(0.72)Nb_2O_6 (CBN28) ceramics with different content of CuO were prepared by the conventional ceramic fabrication technique. The effects of CuO content on the phase structure, microstructure, dielectric and ferroelectric properties of obtained CBN28 ceramics were investigated. XRD results showed that pure tungsten bronze structure was obtained in all ceramics and CuO additive could accelerate the phase formation at lower temperatures. The CuO aid was effective for the uniform grain size in CBN28 ceramics, as it could facilitate the sintering behavior and suppress the anisotropic growth behavior obviously. The dielectric and ferroelectric properties of CBN28 ceramics depended greatly on the CuO content. Curie temperature T_c and dielectric loss tanδ both shifted downward, whereas the maximum dielectric constant ε_m and the dielectric constant around room temperature ε_r all increased initially and then decreased as x increased from 0.1 to 0.4 wt%. Normal ferroelectric hysteresis loops could be observed in all compositions, and the remnant polarization P_r decreased gradually. It was found that the comprehensive electric performance was optimized in CBN28-0.2 wt% CuO ceramics: ε_r = 453, ε_m = 3,371, T_c = 226 ℃,tanδ = 0.048, P_r = 4.72μC/cm~2 and E_c = 13.81 kV/cm, showed that CuO sintering aid could not only ameliorate the sintering behavior but also improve the electrical properties.