Application of bismuth copper tantalate in internal barrier layer capacitors

The paper presents synthesis and sintering procedure and dielectric properties of a new high permittivity perovskite material with the composition Bi_2/3CuTa₄O₁₂ and the structure similar to that of Cu₂Ta₄O₁₂. Complex impedance spectroscopic studies carried out at frequencies 10 Hz-2 MHz and in a wide temperature range from -55 to 700°C reveal two types of dielectric response of ceramic samples. The high-frequency and low-temperature response was attributed to grains, and the low-frequency and high-temperature one - to grain boundaries. The high dielectric permittivity at a level of 10⁵ was suggested to be related to spontaneous formation of internal barrier layer capacitors. SEM and EDS studies confirmed the existence of semiconducting grains and more resistive grain boundaries in Bi_2/3CuTa₄O₁₂ ceramics.