Structure and enhanced properties of perovskite ferroelectric PNN–PZN–PMN–PZ–PT ceramics by Ni and Mg doping

Perovskite ferroelectric oxide ceramics of 0.1Pb(Ni1/3Nb2/3)O3–0.35Pb(Zn1/3Nb2/3)O3–0.15Pb(Mg1/3Nb2/3)O3–0.1PbZrO3–0.3PbTiO3 (0.10PNN–0.35PZN–0.15PMN–0.10PZ–0.30PT) with excess MgO and NiO were investigated in this work. The effects of the excess MgO and NiO doping on the ceramic structure, density, dielectric, ferroelectric and piezoelectric properties were studied. The chemical states of nickel were examined using X-ray photoelectron spectroscopy (XPS). Both XPS experimental results and theoretical analyses on the basis of ionic packing indicated that the excess valence-two ions substituted the A-sites in the ABO3 perovskite structure. By completely eliminating the pyrochlore phase and enhancing densification with the excess NiO and MgO, improved piezoelectric coefficient d33 up to 459 pC/N, higher ferroelectric remnant polarization and dielectric constant were demonstrated when sintered at temperature as low as 850–950 °C.