Structural and Dielectric Properties of Strontium Bismuth Samarium Tantalate Layered Perovskites

Abstract

The polycrystalline Sr(Bi_0.9Sm_0.1)₂Ta₂O₉ (SBSmT) ceramics were fabricated via the promising low temperature molten salt synthesis route using KCl as flux material. The X-ray powder diffraction patterns of these ceramics confirmed the existence of monophasic perovskite crystal structure. The scanning electron microscopic studies revealed the presence of plate shaped morphological features of the SBSmT ceramics. Interestingly, the dielectric constant of the SBSmT ceramics in the frequency range of 20 Hz - 1MHz could be tuned as a function of sintering duration. It is observed that the SBSmT ceramics sintered at 1050°C for 10h exhibited higher dielectric constant (ϵ_r = 76) at 100 kHz than those of ceramics sintered at other durations. The magnitude of the electrical conductivity of the order of 10⁻⁷ - 10⁻⁹ S/cm at 300 K indicates that the conductivity mechanism might be attributed to the migration of oxygen ion vacancies in these ceramics.

Keywords:

• Sintering
• X-ray methods
• dielectric properties
• tantalates