Dielectric, piezoelectric, and ferroelectric properties of Al2O3 and MnO2 modified PbSnO3-PbTiO3-Pb(Mg1/3Nb2/3)O3 ternary ceramics

The PbSnO3-PbTiO3-Pb(Mg1/3Nb2/3)O3 (PST-PMN) ternary system with morphotropic phase-boundary (MPB) compositions were fabricated using a two-step columbite precursor method. The effects of Al2O3 and MnO2 addition on the dielectric, piezoelectric, and ferroelectric properties of PST-PMN were investigated. MnO2 acted as an acceptor dopant and induced a ''hardening'' effect in PST-PMN, with decreased piezoelectric coefficients d33 and increased mechanical quality factors Qm, while the addition of Al2O3 led to the significant decrease of piezoelectric properties, attributed to the second phase. Of particular interest is the fact that the Mn-doped PST-PMN exhibited excellent properties when the doping level was in the range of 0.2-0.5 wt%, with piezoelectric d33, planar electromechanical coupling kp, dielectric permittivity εr, Qm, remnant polarization Pr and coercive field EC being on the order of ∝510 pC N-1, ∝57%, 3120-3500, 530-600, 27-30 μC cm-2, and ∝8 kV cm-1, respectively, showing advantages over commercial PZT4-type ceramics, which are promising for high-power electromechanical applications. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)