Study of the structural and electrical properties of PMNT 68/32 ceramic prepared by a sol–gel process

Abstract

Lead magnesium niobate titanate, PMNT 68/32, ceramic was prepared by a sol-gel technique using alkoxide precursors. Perovskite phases with mixed structure (rhombohedral and tetragonal) were identified by X-ray diffraction (XRD). A dense and homogeneous distribution of sub-micron-size grains was obtained from a scanning electron microscopy (SEM) study. The dielectric response showed relaxor behavior of the material with a transition temperature of $130 C at 1 kHz. The polarization versus electric field (P-E) hysteresis loop with a remnant polarization, P r , of $28 mC/cm 2 and a coercive field, E c , of $4.2 kV/cm confirmed the ferroelectric nature of the material. The room temperature values of the piezoelectric coefficient, d 33 , and the pyroelectric coefficient, p i , were found to be $300 pC/N and $56 nC/cm 2 K, respectively. The development of high strain with a large hysteresis in the strain versus electric behavior was related to the morphotropic phase boundary (MPB) nature of the material.