Effect of MnO2 doping on piezoelectric, dielectric and ferroelectric properties of PNN-PZT ceramics

Traditional solid state reaction method was adopted to synthesize ternary piezoelectric ceramics 0.55Pb(Ni1/3Nb2/3)O-3-0.45Pb(Zr0.3Ti0.7)O-3 (abbreviated as PNN-PZT) with MnO2 additive (0-3.5% in molar ratio) in order to develop composition ceramics for low dielectric loss multilayer piezoelectric electroacoustic device. Effect of MnO2 doping on electric properties of PNN-PZT ceramics was systematically investigated. The results show that MnO2 doping significantly reduces dielectric loss (tg delta), increases phase transition temperature (T-max) at a maximum value of relative permittivity, and weakens ferroelectricity. The 1.0 mol% MnO2 doped PNN-PZT ceramics have optimal piezoelectric, dielectric and ferroelectric properties with d(33)=710 pC/N, k(p)=0.595, Q(m)=176, epsilon(r)=3092 (1 kHz), tg delta=0.0149 (1 kHz), P-r = 15.45 mu C/cm(2), and E-c=4.98 kV/cm. A modified Curie Weiss law revealed the behavior of diffuse relaxor phase transition of the ceramics. All these results (high d(33), high k(p), and low tg delta) make the modified PNN-PZT ceramics promising candidates for electromechanical devices. The mechanism of effect of MnO2 doping on electric properties was discussed. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.