High permittivity and low dielectric loss of the Ca1-xSrxCu3Ti4O12 ceramics

The Ca1-xSrxCu3Ti4O12 (CSCTO) giant dielectric ceramics were prepared by conventional solid-state method. X-ray diffraction patterns revealed that a small amount of Sr2+ (x < 0.2) had no obvious effect on the phase structure of the CSCTO ceramics, while with increasing the Sr2+ content, a second phase of SrTiO3 appeared. Electrical properties of CSCTO ceramics greatly depended on the Sr2+ content. The Ca0.9Sr0.1Cu3Ti4O12 ceramics exhibited a higher permittivity (71,153) and lower dielectric loss (0.022) when measured at 1 kHz at room temperature. The ceramics also performed good temperature stability in the temperature range from -50 degrees C to 100 degrees C at 1 kHz. By impedance spectroscopy analysis, all compounds were found to be electrically heterogeneous, showing semiconducting grains and insulating grain boundaries. The grain resistance was 1.28 Omega and the grain boundary resistance was 1.31 x 10(5) Omega. All the results indicated that the Ca1-xSrxCu3Ti4O12 ceramics were very promising materials with higher permittivity for practical applications. (C) 2011 Elsevier B.V. All rights reserved.