Piezoelectric and Dielectric Properties of ((K0.475Na0.495Li0.03)NbO3-0.003ZrO2)/PVDF Composites

摘要： The (K0.475Na0.495Li0.03) NbO3-0.003ZrO2 (KNNL-Z) ceramic was synthesized by the conventional solid-state reaction and (KNNL-Z)/PVDF composites were fabricated by hot-pressing process using polyvinylidene fluoride (PVDF) and KNNL-Z ceramic. The effects of the ceramic content on the crystalline structures, morphology, densities, dielectric and piezoelectric properties of (KNNL-Z)/PVDF 0–3 composites were systemically studied. The KNNL-Z ceramic possesses a perovskite phase with orthorhombic symmetry and the PVDF polymer mainly possesses a, b and c phases. Interestingly, the incorporation of the ceramic particles can decrease the crystallite size of the PVDF matrix. In addition, the b phase content increases and the a phase decreases when the ceramic particles are added. When the ceramic content increases from 40 wt.% to 80 wt.%, the relative fraction of b phase increases from 47.7% to 53.8%. Successful incorporation of ZrO2 into the KNN ceramic has been demonstrated by energy-dispersive x-ray spectroscopy and the most elements are homogeneously distributed in the composites. The dielectric and piezoelectric properties are found to be improved with the increase of KNNL-Z content. When 80 wt.% KNNL-Z is added, the dielectric permittivity reaches the value of 272 (100 Hz) at room temperature and the piezoelectric coefficient is 39 pC/N. After 30 days of aging, it is obvious that all the composites present a good stability of their piezoelectric property.