Effects of Nb and Ni co-doped on dielectric properties of CaCu 3 Ti 4 O 12 ceramics

Nb and Ni co-doped CaCu 3 Ti 4 O 12 ceramic samples (CaCu 2.8 Nb 0.2 Ti 3.9 Ni 0.1 O 12 ) were obtained via the solid-state reaction method. We focused on the effect of sintering temperature (1020°C, 1040°C and 1060°C for 6 h) on phase compositions, microstructure, impedance and dielectric properties. X-ray diffraction (XRD) studies confirmed the constitution of a body-centered cubic perovskite structure. Scanning electron microscopy (SEM) micrographs revealed that average grain size increased with the rise of temperature. Dielectric properties ranging from 103 Hz to 106 Hz were tested at room temperature. CaCu 2.8 Nb 0.2 Ti 3.9 Ni 0.1 O 12 sample sintered at 1040°C attained the highest dielectric constant, whereas the sample sintered at 1060°C achieved effective frequency stability for dielectric constant along with the smallest grain resistance Rg. The sample sintered at 1060°C possesses the lowest dielectric loss and maintains a high dielectric constant; thus it has optimal comprehensive dielectric properties.