Dielectric properties of BZN ceramics doped with Ca2+ in A/B-sites

Bi1.5ZnNb1.5O7 ceramics doped with Ca2+ in A-site and B-sites were prepared by the conventional solid state reaction method. The effect of Ca2+ doping on structure and dielectric properties has been investigated. The results showed that solid solubility of Ca2+ doping A-site, (Bi1.5−xCaxZn0.5)(Nb1.5Zn0.5)O7 (BCZN), was 0.25 mol, and B-site (Bi1.5Zn0.5)(Nb1.5−yCayZn0.5)O7 (BZNC) was 0.1 mol. With increasing Ca2+ content, the dielectric dispersion behavior of the BCZN and BZNC ceramics was qualitatively similar. The dielectric peak shifted to lower temperature in the case of A-sites doping (BCZN), while higher temperature in the case of B-sites doping (BZNC). In the same case of Ca2+ content, compared with A-site doping (BCZN), an decreasing dielectric relaxation for B-site doping (BZNC) occurs, which is attributed to the larger the bond valence sums (AVs) of O′ for B-site doped ceramics than A-site doped ceramics. The dielectric relaxation degree of BZN ceramics is closely related to the change from perfect octahedral to regular cube.