Dielectric and structural properties of layer-structured Sr1-xCaxBi2Nb2O9

Sr1-xCaxBi2Nb2O9 (x=0, 0.2, 0.4, 0.6, 0.8 and 1) ceramics were prepared by a conventional solid-state reaction method. Their dielectric and structural properties were investigated. X-ray diffraction analysis indicated that single-phase layered perovskites were obtained. For Ca-substituted specimens, a dielectric relaxation peak is observed in the temperature range of 30 degrees-150 degrees C, and there is a broader para-ferroelectric phase transition peak. The temperature of the maximum dielectric constant T-m increases linearly with increasing Ca content. Raman spectra indicate that a small amount of Ca2+ is incorporated into Bi sites in the Bi2O2 layers, and an increase in the degree of distortion of NbO6 octahedra for Ca-substituted specimens should be one of the reasons for the increase in T-m compared with SrBi2Nb2O9.