Influence of donor doping on dielectric properties of calcium copper titanate ceramics

Calcium Copper Titanate ceramics (CaCu3Ti4O12) doped with Yb were prepared by the traditional solid–state reaction method. It is found by x-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, and X-ray photoelectron spectroscopy that Yb prefers to locate at the A site as a donor, which gives rise to the inhibition of oxygen vacancies in the grains and the segregation of Cu to the grain boundaries. Dielectric properties of the samples and electronic structure at grain boundary were investigated further by dielectric spectroscopy and specific impedance spectroscopy, respectively. It is revealed that medium frequency dielectric relaxation is restrained obviously for the decrease of oxygen vacancy, while giant dielectric permittivity (higher than 104) is maintained for the decrease of depleted layer thickness after donor doping. Therefore, the research of this paper offers an effective way to improve the dielectric properties of CaCu3Ti4O12 based on the modulation of intrinsic point defects.