PMN-PT Ceramics Research Articles

Effect of excess MgO on dielectric properties of PMN-PT ceramics with ZnO additive

Abstract PMN-PT ceramics with ZnO additive were prepared by the columbite precursor method and their microstructure and dielectric properties were investigated as a function of excess MgO content. The PMN-PT ceramics with pure perovskite phase and relative density of 95% were obtained at 1150°C by the addition of 2 mol% ZnO. For the 2 mol% ZnO-added PMN-PT, the addition of excess MgO up to 2 mol% led to increases in grain size, dielectric constant and electrostrictive strain. Further addition of excess MgO degraded these values, mainly due to the inhibited grain growth resulting from the precipitation of an Mg-rich phase. For the no-ZnO-added specimen, the grain size and dielectric properties increased with increasing excess MgO up to 5 mol% and then decreased with further excess MgO addition.

Influence of domain walls on piezoelectric and electrostrictive properties of PMN-PT (65/35) ceramics

Polarization and strain measurements on lead magnesium niobate-lead titanate ceramic (0.65PMN-035PT) are performed. Quasi-static P(E) and S(E) loops and dynamic measurements of the dielectric constant, piezoelectric d33 and electrostrictive Q11 coefficients are made. The relation between piezoelectricity and electrostriction in polydomain materials is discussed. The relation d33 = 2εε0Q11P0 which is true for monodomain materials is not verified in the case of ceramics. The influence of domain walls motion on dielectric constant and piezoelectric coefficient is shown. The calculation of the ratio of 180° and 90° domains in the sample is made using the characteristic values related to the hysteresis loops and shows the larger amount of 180° domains in this material.

The electrostrictive and dielectric properties in the ion-doped pzn-basbd ceramics

Abstract Abstract The effects of several dopants on the material properties of the PZN—BT and the PZN—PMN—PT ceramics were studied. The investigated dopants are La3+, Y3+, K+and W6+. The structural order characteristics of the ion doped ceramics were examined with XRD. It is demonstrated that the donor-doping with La3+, Y3+and W6+enhances the ordering degree. And that the acceptor—doping with K+suppressed the ordering degree. The decreasing of the maximum value on dielectric constant is contributed by the amount of pyrochlore phase, lattice constant and diffusion parameter. Furthermore, it is found that the electrostrictive coefficient could be increased with either the donor doping or the acceptor doping.

Electromechanical properties of new electrostrictive materials for underwater acoustical applications

Electrostrictive ceramics are known to be capable of generating strains that far exceed those of conventional piezoelectric lead–zirconate–titanate (PZT) ceramics. Several lead–magnesium–niobate (PMN) compositions developed earlier were useful only at higher temperatures than those of interest to the sonar community. A new barium‐modified PMN–PT ceramic is described. This material can operate at lower temperatures and has very low losses, making it a prime candidate for high‐power sonar transducer applications. Another family of electrostrictive materials capable of generating large strains is lanthanum‐modified PZT (or PLZT). These materials exhibit strains up to 0.1% along with extremely high dielectric strength, but their hysteresis losses are higher than those of PMN or PMN–PT ceramics. Since the maximum possible strain output is usually the important parameter in actuator applications, the PLZT family may have potential for new actuator designs. Strain measurements for these new electrostrictive cera...