Effect of composition on the structure and piezoelectricity of Na0.5Bi4.5Ti4O15-based flexoelectric-type polar ceramics

► Na0.5Bi4.5Ti4O15-based flexoelectric-type polar ceramics is first fabricated. ► Effect of composition on the structure and piezoelectricity of ceramics is studied. ► We propose the possible poling mechanism of these polar ceramics. ► These polar ceramics possess depoling temperatures higher than 700 °C.