Dielectric tunability and imprint effect in Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramics

For (1 − x)Pb(Mg1/3Nb2/3)O3-xPbTiO3, composition dependence of dielectric tunability under the dc bias field and dielectric hysteresis during the circle of external electric field were studied. The highest dielectric tunability of 71% (at the dc bias of 1000 V/mm) and the lowest dielectric hysteresis were observed in the 0.9PMN-0.1PT sample. The effect of circled electric field on the dielectric hysteresis was more remarkable than that on the dielectric aging. Moreover, the effect of the filed-cooled process on the ferroelectric properties was also investigated. In the polycrystalline 0.7PMN-0.3PT sample cooled under a strong dc electric field, a remarkable imprint effect was reported. The preferred direction induced by a strong external electric field was partially reserved after removing the electric field. This imprint effect and the dielectric hysteresis have been tentatively interpreted by reorientation and alignment of polar vectors.