Dielectric and piezoelectric properties of lanthanum-modified lead magnesium niobium-lead titanate ceramics

Abstract Dielectric and piezoelectric properties of relaxor ferroelectrics in the solid solution, formulated (1−x)(Pb1–1.5yLay)(Mg1/3Nb2/3)—x PbTiO3, have been investigated. The dielectric properties show typical first order ferroelectric behavior for PT ≥ 35% and relaxor type below being indicative of the morphotropic phase boundary. Lanthanum doping resulted in reduction of grain size and shifting of the Tc (Curie Temperature) −25 °C/mole% downward in PMN-PT polycrystalline ceramics. The optimum value of piezoelectric constant, d 33, obtained was 560 pC/N for compositions near the morphotropic phase boundary. Based on this investigation, La doped PMN-PT compositions appear to be promising candidates, for fine grain size piezoelectrics, pyroelectric bolometers, and through hot pressing or hot isostatic pressing, for electro-optic applications.