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 °C to 100 °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 Ω and the grain boundary resistance was 1.31 × 105 Ω. All the results indicated that the Ca0.9Sr0.1Cu3Ti4O12 ceramics were very promising materials with higher permittivity for practical applications.

• The Ca1−xSrxCu3Ti4O12 (x = 0, 0.10, 0.15, 0.20, 0.25) giant dielectric ceramics were prepared by conventional solid-state reaction method.
• The Ca0.9Sr0.1Cu3Ti4O12 ceramics exhibited a higher permittivity (71,153) and lower dielectric loss (0.022) at 1 kHz at room temperature.
• The ceramics also showed good temperature stability from −50 °C to 100 °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 Ω and the grain boundary resistance was 1.31 × 105 Ω.