Enhanced dielectric properties and electrical responses of cobalt-doped CaCu3Ti4O12 thin films

This work firstly reported preparation of cobalt-doped CaCu3Ti4O12 (CCCTO) thin film by a sol-gel modified method. It was concluded that a relatively high dielectric constant ε' (2326, at 1 kHz), low dielectric loss tan δ (0.012, at 1 kHz) and high nonlinear coefficient α (4.9) were simultaneously obtained in the CaCu2.95Co0.05Ti4O12 thin film at room temperature. The decrease of the dielectric loss was associated with the increase in the density of the insulating grain boundary layer, which was governed by the grain size reduction and densification of CCCTO films due to Co doping. Monovalent cation Cu+ detected by X-ray photoelectron spectroscopy (XPS) of the CaCu2.95Co0.05Ti4O12 thin film decreased leakage current. These excellent electrical properties provided a viable solution to the application of CCTO materials in capacitive-varistors.