Effects of rare-earth Sm2O3 addition on relaxation behavior and electric properties of 0.5PNN-0.5PZT ceramics

Rare-earth Sm2O3-doped Pb(Ni1/3Nb2/3)(0.5) (Zr0.3Ti0.7)(0.5)O-3 (0.5PNN-0.5PZT + xSm) piezoelectric ceramics were prepared by a two-step solid-state reaction method. The effects of Sm2O3 doping on phase structure, electric properties and dielectric relaxation of 0.5PNN-0.5PZT ceramics were investigated. The results showed that Sm3+ tended to occupy the B-site of Zr4+. The XRD patterns showed that all ceramics had a pure perovskite phase structure. With the increasing of Sm2O3 addition, Curie temperature moved towards low temperatures obviously and dispersion coefficient gamma first increased and then decreased gradually. When x = 0.2 wt%, the gamma reaches at maximum (1.998), it was indicated that a nearly complete diffuse phase transition existed and relaxation behaviors enhanced. But the ceramics with x = 0.2 wt% exhibited terrible electric properties: d(33) = 605 pC/N, k(p) = 0.55, epsilon(r) similar to 5020, tan delta similar to 2.20 %. It showed that the relaxation behaviors have relationships with electric properties to some extent.