Influence of sintering parameters on melting CuO phase in CaCu3Ti4O12

Dielectric material CaCu3Ti4O12 (CCTO) was prepared by solid state technique. CaCO3, TiO2, and CuO powders were mixed thoroughly in a ball mill for an hour and were calcined at 900 °C for 12 h. This is followed by sintering at a defined standard temperature for this work (1050 °C for 24 h). Other samples were prepared in a similar manner but with different sintering durations. Each of the sample’s microstructure was observed by a Scanning Electron Microscope (SEM). Meanwhile, Energy-dispersive X-ray Spectroscopy (EDX) analysis was done on fracture surfaces in order to examine the elements present at grain boundaries. Microstructure observations show the melting and abnormal grain growth with large pores. The solidified liquid at grain boundaries was verified as Cu rich region, as confirmed by EDX analysis. By using the SEM, microstructure of small grains with clear grain boundaries were obtained when sintering was done at temperatures lower than 1050 °C. The microstructure of CCTO was very sensitive to sintering parameters.