Effect of Cr2O3 addition on the structure and electrical properties of Pb((Zn1/3Nb2/3)0.20(Zr0.50Ti0.50)0.80)O3 ceramics

The structure and electrical properties of Cr2O3-doped Pb(Zn1/3Nb2/3)0.20(Zr0.50Ti0.50)0.80O3 system (0.2PZN-0.8PZT) were described in this paper. Materials with pure perovskite structure were fabricated by the columbite precursor method. Addition of Cr2O3 stabilized the tetragonal phase against the rhombohedral one, moving morphotropic phase boundary (MPB) composition toward the PbTiO3-deficient side. The grain size was steadily enhanced when small amounts of Cr2O3 were added to system. However, addition of Cr2O3 above the solubility of 0.3 wt.% inhibited the grain growth due to accumulation of Cr ion at the grain boundary. The values of electromechanical coupling factor, kp, piezoelectric constant, d33 are optimized for 0.3 wt.% Cr2O3-doped samples (kp = 0.70, d33 = 491 pC/N), which suggested that the effects of grain size plays a dominant role on improving the piezoelectric properties than that of oxygen vacancies in the low Cr2O3 doping region of 0-0.3 wt.%.