The positive effect of A-site nonstoichiometry on the electrical properties of Sr2Nb2O7 ceramics for high temperature piezoelectric sensor application

The structure and electrical properties of A-site nonstoichiometric perovskite layered structured (PLS) Sr2-xNb2O7-x piezoelectric ceramics prepared by the traditional solid-state reaction method are studied. The piezoelectric constant increases from 1.0 pC/N to 2.1 pC/N. Through XRD refinement and Raman analysis, the enhancement of the piezoelectric performance is mainly achieved by enhancing the distortion and/or rotation of the oxygen octahedron. The dielectric breakdown field strength at room temperature increases from 206 kV/cm to 435 kV/cm. The mechanism of dielectric breakdown enhancement has been explored by intrinsic factors such as dielectric constant and band gap. The resistivity at 700 °C increases from 6.7 × 105 Ω cm to 1.1 × 107 Ω cm which meets the requirements of high temperature vibration sensors at 650 °C. The improvement of high temperature resistance may be related to the inversion of oxygen vacancies. This work provides promising PLS piezoelectric ceramics for potential applications in high-temperature piezoelectric vibration sensors which uses a simple synthesis method without doping any elements.