Effects of Zn/Ni Ratio and Doping Material on Piezoelectric Characteristics of Pb((Zn, Ni)1/3Nb2/3)O3–Pb(Zr, Ti)O3 Ceramics

This study investigates the effects of the Zn/Ni composition ratio and doping materials on the piezoelectric properties of PZNN-PZT ceramics for the fabrication of piezoelectric ceramics with excellent characteristics. A soft relaxor was used to improve the electrical characteristics and sinterability. The ceramics were fabricated with a base composition ratio of 0.13Pb((Zn 1– x Ni x ) 1/3 Nb 2/3 )O 3 –0.87Pb(Zr 0.5 Ti 0.5 )O 3 . The columbite phase was formed by reacting NiO and Nb 2 O 5 , which have low reactivity, as the first calcination, and the columbite precursor method was applied for the second calcination with PbO. Although the pellet was produced by sintering at a relatively low temperature of 950 °C, we obtained a dense ceramic with a high density of 7.9 g/cm 3 . To improve the quality factor in the composition with a Ni/(Ni + Zn) molar ratio of 0.1, the doping materials MnO 2 , Fe 2 O 3 , CuO, and Bi 2 O 3 were added and their properties were confirmed. Pure perovskite phases were formed in the ceramics of all compositions and doping materials. In particular, the PZNN-PZT ceramics doped with 0.3 wt% MnO 2 showed a piezoelectric coefficient of 348 pC/N, electromechanical coupling factor of 0.59, mechanical quality factor of 345, and Curie temperature of 316 °C, which are excellent piezoelectric characteristics.