An effective method to decrease dielectric loss of CaCu3Ti4O12 ceramics

Ceramics with the chemical compositions of CaCu3−xSrxTi4O12 (0 ≤ x ≤ 0.4) (CCSTO) were prepared by the conventional solid-state reaction method and the dielectric properties were investigated. It is found that the dielectric loss decreases with increasing x and reaches 0.03 for x = 0.4, meanwhile, the permittivity remains above 3000. Scanning electron microscopy and Energy Dispersive X-ray results indicate the solutions of SrTiO3 and CaTiO3 emerge at grain boundaries. Correspondingly, the impedance spectroscopy analysis confirms that the decrease of dielectric loss is mainly attributed to the increase in the resistivity of the grain boundary. The permittivity and dielectric loss of CCSTO ceramics exhibit very little dc bias dependence (Δɛ′/ɛ′ < 3% up to 0.8 kV/cm) at 10 kHz. These results indicate that CCSTO ceramics have a promising applied prospect with high-permittivity, sufficiently low dielectric loss, and better dc bias voltage stability.