Giant dielectric constant response of the composites in ternary system CuO–TiO2–CaO

The subsolidus phase relations of the ternary system CuO–TiO2–CaO sintered at 950 °C in air have been determined by powder X-ray diffraction method. Only one ternary compound CaCu3Ti4O12 was found in this system. From room-temperature dielectric property mapping at 10 kHz, a giant dielectric constant (εr>104) was observed for most of the ceramic composites in the CuO-rich region and in the region along the CaO–CuO binary line. The composites in the CaCu3Ti4O12-rich region were found to give a comparable giant dielectric constant when sintered at 1050 °C. The particular microstructure of larger grains with predominant phase surrounded by smaller grains with the secondary phases was found in such composites with a high dielectric constant. The relations between structures and dielectric properties were investigated. An internal barrier layer capacitance effect is the most probable mechanism to explain this particular dielectric behavior.

Graphical AbstractIn the ternary system, CuO–TiO2–CaO, a giant dielectric constant (εr) above 104 (red color) was observed in most of the composites sintered at only 950 °C in the CuO-rich region. Dashed lines show the phase boundaries.Figure optionsDownload full-size imageDownload as PowerPoint slide