High permittivity and low dielectric loss in ceramics with the nominal compositions of CaCu3-xLa2x/3Ti4O12

Ceramics with the nominal compositions of CaCu3-xLa2x/3Ti4O12 were prepared by the conventional solid-state reaction technique. It was found that these ceramics have the properties of rather high dielectric permittivity and sufficiently low dielectric loss. In particular, CaCu2.9La0.2/3Ti4O12 ceramics sintered at 1050 degrees C for 20 h showed the high dielectric permittivity of 7500 with weak frequency dependence below 1 MHz, the low dielectric loss less than 0.05 in the wide frequency range of 120 Hz-200 kHz (with the minimum 0.012 at 20 kHz), and the small temperature coefficient about +/- 15 ppm/degrees C between -80 and 125 degrees C. From the analysis, it was suggested that CaTiO3 secondary phase due to Cu deficiency and La doping plays the important roles in the observed excellent dielectric properties in CaCu3-xLa2x/3Ti4O12 ceramics. The results indicated that they are a very promising class of high-permittivity materials for practical applications. (C) 2007 American Institute of Physics.