Characterization of samarium copper tantalate - a new perovskite material with high dielectric permittivity

A permanent progress in miniaturization of electronic capacitive elements requires development of new materials exhibiting a high dielectric constant. The paper reports on synthesis and sintering conditions and dielectric properties of a new ceramic material with the composition Sm2/3CuTa4O12 . This material has a complex perovskite structure analogous to that of CuTa4O12 . Its high dielectric permittivity reaching 10 5 could be attributed to spontaneous formation of internal barrier layer capacitors (IBLC). Complex impedance spectroscopic studies carried out at frequencies of 10 Hz – 2 MHz and in a wide temperature range from -55 to 700°C reveal two types of dielectric response of the ceramic samples. A high-frequency and low-temperature response is related to grains, whereas a low-frequency and high-temperature response is attributed to grain boundaries. Scanning electron microscope images and energy-dispersive X-ray microanalysis confirmed the existence of semiconducting grains and more resistive grain boundaries in the investigated ceramic material. Key words: samarium copper tantalate, perovskite ceramic, dielectric properties, internal barrier layer capacitor