Effect of excess TiO2 in CaCu3Ti4O12 on the microstructure and dielectric properties

Abstract

Dielectric material CaCu3Ti4O12 (CCTO) was prepared by a solid state technique. CaCO3, TiO2 and CuO powders were mixed thoroughly in a ball mill for one hour. The reagent ratios were modified for TiO2 contents (2-6 mol). The mixed powder were calcined at 900 oC for 12 hours and sintered at 1040 oC for 10 hours. The sintered samples were subjected to XRD phase analysis. The microstructures of sintered pellets were observed by SEM. The effects of TiO2 content on the phase formation,density, microstructure and dielectric properties are reported. XRD results show that the different phase formation depends on the TiO2 content. Increasing the TiO2 content reduces the density. At the surface regions, clear grain boundaries and a dense microstructure were observed. The results show that a sample sintered at 1040 oC for 10 hours give a clearly uniform grain size with the highest dielectric constant (33, 210). The degree of nonstoichiometry of TiO2 influenced the dielectric properties by reducing its dissipation factor.