Dielectric properties, ac conductivity and thermal behaviour of flux grown cadmium titanate crystals

The dependence of loss tangent (tan δ) and both real and imaginary parts of the dielectric constant (ɛ′ and ɛ″) on temperature in the range 298-923 K and frequency in the range 103-106 Hz for flux grown CdTiO3 single crystals is reported. The ln σac versus T plots suggest the conduction mechanism to be ionic hopping conduction. From ln σac versus frequency curves, it can be seen that the slope decreases with the rise in temperature, suggesting that the ionic hopping conduction diminishes with the rise in temperature. The activation energy at various fixed frequencies is calculated from the slope of the graph between ln σac versus 1/T (×103 K−1). Thermal behaviour of flux grown CdTiO3 crystals using thermoanalytical techniques including TG, DTA and DTG is discussed. Thermal analysis suggests decomposition of CdTiO3 in the temperature interval of 1386-1693 K leading to the formation of TiO2 as the final product. Results obtained on application of TG based models viz. Horowitz-Metzger, Coats-Redfern and Piloyan-Novikova are reported. The results of kinetics of thermal decomposition suggest contracting cylinder model as the one that is relevant to the decomposition of CdTiO3. The kinetic parameters viz. the order of reaction, activation energy, frequency factor, and entropy of activation using the above mentioned models are computed.