Large strain under low driving field in lead‐free relaxor/ferroelectric composite ceramics

• DOI: 10.1111/jace.16256
• Publication Date: 2018-12-13T06:39:53Z
• Authors: Pengyuan Fan; Yangyang Zhang; Yiwei Zhu; Weigang Ma; Kai Liu; Xueting He; Mohsin Ali Marwat; Bing Xie; Ming Li; Haibo Zhang
• Keywords: 02 engineering and technology; 0210 nano-technology

Abstract0.75(Na0.5Bi0.5)TiO3–0.25SrTiO3 lead‐free incipient piezoceramic is a promising candidate for actuator applications due to their large reversible electromechanical strains at the relatively low driving field of 40 kV/cm. In order to further reduce the driving field of 0.75(Na0.5Bi0.5)TiO–0.25SrTiO3 relaxor ceramic to meet the requirements for real actuators application, the relaxor/ferroelectric (RE/FE) 0‐3 composite ceramics method was employed. The polarization and strain behaviors were examined as a function of the weight ratio of the relaxor/ferroelectric phases. It was found that 90 wt% 0.75(Na0.5Bi0.5)TiO3–0.25SrTiO3/10 wt% 0.96(Na0.84K0.16)1/2Bi1/2TiO3–0.04SrTiO3 RE/FE 0‐3 type composite samples provided a high unipolar strain of 0.25% and the corresponding large‐signal piezoelectric coefficient, d*33 of 833 pm/V at 30 kV/cm, which are 32% higher than the values of the pure 0.75(Na0.5Bi0.5)TiO3–0.25SrTiO3. The enhanced electric‐field‐induced strain at relatively lower field was attributed primarily to the reduction in the RE‐FE phase transition electric field. It was also found that the RE/FE composite ceramics exhibited significantly reduced frequency dependence in the unipolar strain behavior at room temperature.