Influence of MgTiO3-Doping on Microstructure and Dielectric Properties of CaCu3Ti4O12 Ceramics

Abstract

The application of CaCu3Ti4O12 (CCTO) is limited due to its high low-frequency dielectric loss. An internal barrier layer capacitance effect seems to be the most widely accepted explanation for the giant-e′ phenomenon of CCTO ceramics. According to the effect, wrapping the semiconducting grains of CCTO ceramics in insulating materials is an effective way to reduce the low-frequency dielectric loss. CCTO/MgTiO3 composite ceramics were prepared, and their crystalline structures, microstructures, dielectrical properties and complex impedance were systematically investigated. The results show that MgTiO3 has been wrapped around the CCTO grains in our CCTO-based ceramics. Compared with pure CCTO ceramics, the low-frequency dielectric loss was not reduced by MgTiO3-doping, because the resistance of MgTiO3 phase boundaries in the CCTO/MgTiO3 composite ceramics as prepared is lower than the grain boundaries resistance of pure CCTO ceramics. After annealing in oxygen, the low-frequency permittivity and dielectric loss of CCTO/MgTiO3 composite ceramics significantly decreased, which should be attributed to the increase of the resistance of insulating MgTiO3 phase boundaries and CCTO grains.