Influence of interface point defect on the dielectric properties of Y doped CaCu3Ti4O12 ceramics

Abstract

CaCu3Ti[Formula: see text]YxO[Formula: see text] (0[Formula: see text]0.12) ceramics were fabricated with conventional solid-state reaction method. Phase structure and microstructure of prepared ceramics were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The impedance and modulus tests both suggested the existence of two different relaxation behavior, which were attributed to bulk and grain boundary response. In addition, the conductivity and dielectric permittivity showed a step-like behavior under 405[Formula: see text]K. Meanwhile, frequency independence of dc conduction became dominant when above 405[Formula: see text]K. In CCTO ceramic, rare earth element Y[Formula: see text] ions as an acceptor were used to substitute Ti sites, decreasing the concentration of oxygen vacancy around grain-electrode and grain boundary. The reason to the reduction of dielectric behavior in low frequencies range was associated with the Y doping in CCTO ceramic.