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((Zn1-xNix)(1/3)Nb-2/3)O-3-0.87Pb(Zr0.5Ti0.5)O-3. The columbite phase was formed by reacting NiO and Nb2O5, 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 degrees 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 MnO2, Fe2O3, CuO, and Bi2O3 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% MnO2 showed a piezoelectric coefficient of 348 pC/N, electromechanical coupling factor of 0.59, mechanical quality factor of 345, and Curie temperature of 316 degrees C, which are excellent piezoelectric characteristics.