Inter-grain mediated intrinsic and extrinsic barrier layer network mechanism involved in Ca1Cu3Ti4O12 bulk ceramic

Abstract

This paper reports colossal dielectric constant (105 order) in the low-frequency region for sintered bulk ceramics of Ca1Cu3Ti4O12 (CCTO) super-capacitor. X-ray diffraction of sintered CCTO sample confirms cubic structure with Im3 space group. Analysis of micrograph on the parallel surfaces of the sintered solid exhibits the homogeneous distribution of grains and grain boundaries on the surface of the pellet. Detail study of Raman scattering data suggests the appearance of polarizable relaxation mode. Studies of capacitive and resistive characteristics of the material in a wide range of frequency of applied electric field and temperature shows that dielectric permittivity, energy loss, impedance, electric modulus and electrical conduction of the material are strongly affected by experimental conditions (frequency and temperature). A good correlation between above electrical parameters (resistance, capacitance, conductance, etc.) and the contents of microstructure (grains and grain boundary) of the material are established. It is expected that use of nano-size TiO2 and CuO2 powders in the initial stage with micron size powder of CaCO3 can help for rapid solid state reaction at microscopic level which is likely to be responsible for high dielectric constant of the material. Present findings suggest that CCTO can be considered as a potential candidate for super-capacitor devices.