Effects of preparation process on the properties of PMN based electrostrictive materials

In this study, the effects of preparation process on the properties of lead magnesium niobate (PMN) based electrostictive materials, such as phase structure, microstructure and electrical property, are investigated and discussed. The results of experiment show the powder samples, fabricated by a modified two-step synthesis method with alkaline-earth metal dopants introduced in the preparation of common electrical materials, has pure perovskite phase in XRD patterns without pyrochlore structure. From SEM figures, it can be seen the sinter temperature has certain influences on grain size and morphology. Especially, the sinter temperature is elevated over 124degC that the grain overgrows and grain boundaries become ambiguous. Moreover, the additive dopant can suppress the grain growth and reduce the grain size, which benefits to lowering sintering temperature and improves the density of materials. The induced strain curve measured by the optic fiber method shows the PMN based electrostrictive materials has a large strain, ~0.8times10^-3 under a 2000 V/mm bias field.