Decrease of dielectric loss in giant dielectric constant CaCu3 Ti4 O12 ceramics by adding CaTiO3

CaCu3 Ti4 O12–xx CaTiO3 ceramics (x=0,0.1,0.2,0.3,0.4x=0,0.1,0.2,0.3,0.4 and 0.5) was studied by X-ray diffraction, scanning electron microscope and dielectric measurements. It was indicated that some CaTiO3 entered the boundaries of CaCu3 Ti4 O12 grains and/or subgrains. Dielectric measurement showed that the addition of CaTiO3 lowered the dielectric loss remarkably, especially at low frequencies, while the giant dielectric constant still remained. At room temperature, the dissipation factor of the x=0.5x=0.5 sample was decreased to ∼0.02∼0.02 over the frequency range from 50 to 2000 Hz, and the dielectric constant was kept to be 4000. We explain this phenomenon in terms of internal barrier layer capacitance model by using the impedance spectroscopy analysis.