Dielectric and charge carriers hopping studies of sol–gel grown and spark plasma sintered CaCu3Ti4O12 nanocrystals
摘要
This work reports the study of dielectric and charge carriers hoping process of CaCu3Ti4O12 (CCTO) nanocrystals grown by sol–gel method and sintered by spark plasma sintering. The sintering is conducted at 1050 °C for 20 min with the simultaneous application of uniaxial pressure of 50 MPa. An effective approach is considered to integrate a colossal dielectric constant into the material within a short sintering time of 20 min that led to low energy consumption. The dielectric and conduction process are explored in the frequency range of 10 Hz to 8 MHz at the temperatures 30−110 °C. Dielectric spectra inferred that sintered sample possesses a colossal dielectric constant of 2.0 × 104 at 100 Hz and ambient temperature. The phase angle response identifies the resistive and capacitive characteristic of the sample. The complex impedance analysis indicates that charge carrier dynamics has multiple relaxation times, and grains are highly conducting than grain boundary. The activation energy for grain and grain boundary is calculated to be 0.074 eV and 0.376 eV, respectively. The AC conductivity analysis attributes that motion of mobile charge is translational with sudden hoping. The characteristic temperature disorder for variable range hopping, density of localised states at Fermi level, hopping range of polaron and hopping energy are studied. The frequency range for long-range and short-range mobility of charge carriers is identified by electric modulus. These findings present a perspective to understand the dielectric polarisation and charge transport dynamics. The observed colossal dielectric permittivity is offering this material as a promising and cost-effective candidate for electronic and energy storage application.