Dielectric and pyroelectric properties of Sr-modified (Na0.5Bi0.5) Bi4Ti4O15 ceramics

Polycrystalline (Na0.5Bi0.5) Bi4Ti4O15 (NBT) ceramics were prepared by the solid-state reaction method with the Sr substitution in place of divalent pseudo-cation (Na+, Bi3+) with Sr = 0.1, 0.2, 0.3. X-ray diffraction measurements indicate an increase in the orthorhombic distortion and cell volume with the increase of Sr content in the ceramics. Dielectric measurements show the diffuse type transitions with the change in composition. The reduction in Curie temperature can be attributed to the increased tolerance factor due to the substitution of relatively bigger ion in the pseudo cation- (Na+, Bi3+). Pyroelectric data indicate that the samples with x = 0.2 exhibits the better pyroelectric activity than other components of the series. Pyroelectric figures of merit are calculated from the pyroelectric coefficients.