Crystal structure and dielectric properties of novel ordered perovskite oxides A(Sc_1/2M_1/2)O₃ (A = Ca, Sr, M = Nb, Ta)

Abstract

Novel perovskite compounds A(Sc_1/2M_1/2)O₃ (A = Ca, Sr; M = Nb, Ta) were prepared at high temperature in air. Analyses of the XRD data with the Rietveld method revealed that the Sc and M cations were almost ordered, making a NaCl-like arrangement. The structures of the Ca-compounds could be successfully refined in the space group P2₁/n while the XRD of the Sr-compounds showed pseudocubic symmetry. Relative dielectric constants of these compounds are in the range /in = 20 /backsim 40, and gradually increase with increasing temperature. They show a low dielectric loss (tanδ 10⁻⁴) and small frequency dependence.

Keywords:

• Ordered Perovskite Oxides
• Dielectric Properties
• Rietveld Refinements