Study of the Electrical and Dielectric behaviour of selenium doped CCTO ceramics prepared by a facile sol-gel route

A facile sol-gel technique was successfully employed to prepare CaCu3-xSexTi4O12 (x = 0, 0.1, 0.2, 0.3 mM) nanoparticles and after subsequent calcination and sintering at 950 degrees C and 1050 degrees C respectively, ceramics of these nanoparticles were obtained. The powder XRD profile reveals that samples have the perovskite phase of CaCu3Ti4O12. SEM micrograph shows the dense microstructure of the ceramics and EDX analysis illustrates the elemental composition of the products. The dielectric behaviour of these ceramics was studied as a function of frequency (1 Hz-1 MHz) with different selenium concentrations at ambient temperature. The results indicate that doping of selenium over the copper (Cu) site enhances the dissipation factor and depresses the dielectric constant (epsilon(r)) of CaCu3Ti4O12 ceramics. The AC conductivity of the substance was found to decrease with an increase in selenium concentration. The magnitude of high resistivity at high concentrations was mainly caused by the rapid increase in mobility of the charge carriers in the ceramics and follows the positive temperature coefficient of the resistance (PTCR) type behaviour. Electric modulus spectrum of undoped and selenium doped CaCu3Ti4O12 samples indicate that the existence of the non-Debye type of relaxation behaviour. The results suggest that the change in dielectric properties of selenium doped CaCu3Ti4O12 samples may be associated with the lack of oxygen vacancies in the ceramic specimens.