The effect of PSN content on MPB of 0.3Pb(Ni_1/3Nb_2/3)O₃–0.7Pb(Zr_1−xT_x)O₃ system

In this work Pb(Sb_1/2Nb_1/2)O₃–Pb(Ni_1/3Nb_2/3)O₃–Pb(Zr, Ti)O₃ (PSN–PNN–PZT) ceramics were prepared by a conventional mixed oxide method. The morphotropic phase boundaries (MPBs) of yPSN–0.3PNN–(0.7 − y)PZT (y = 0, 0.005, 0.01, 0.015 and 0.02) ceramics with a variable PSN were investigated. The MPB compositions, possessing high performances, were identified using X-ray diffraction and further confirmed by their piezoelectric/dielectric properties. The MPBs shifted to a PT-rich region as PSN increased. The optimal electric properties of 0.015PSN–0.3PNN–0.685PZT were found to be d ₃₃ = 660pC/N, k _p  = 0.68, ε ₃₃ ^T /ε ₀ = 4279, tan δ = 1.56 % for the MPB composition. The remanent polarizations and poling strain gradually increased and then decreased as the PSN content increased. The remanent polarizations (Pr) and poling strains of 0.015PSN–0.3PNN–0.685PZT ceramics at MPB were 33.5 μC/cm² and 0.39 %, respectively. Furthermore, the electrical performances were also related to the cooling speed in the poling process, where the poling field was 3 kV/mm, the poling temperature was 120 °C and the poling time was 15 min.