Synthesis and Characterization of AND Lanthanum Doped by Auto-Combustion Technique

Abstract

(CCTO) is a well known nonferroelectric material possessing high and nearly constant (room temperature to 300oC) dielectric constant at 1 kHz. It is being widely used in the electronic industries to manufacture electronic components such as multilayer capacitor (MLCC), DRAMs, microwave devices, electronic devices in automobiles and aircrafts. The properties like high permittivity of CaCu3Ti4O12 depend upon the particle size and powder morphology. The particle size and powder morphology of CaCu3Ti4O12 depend on the different processing parameters that are temperature, heating rate, duration and atmosphere. Several powder synthesis processes have been tried for the synthesis of CaCu3Ti4O12 among which solution combustion process have got enough emphasis now a days. CaCu3Ti4O12 synthesized using combustion synthesis techniques possess high purity and close control of powder morphology, which will result in the desired microstructure and dielectric behavior. Under this context the present study was carried out to evaluate the effect of different processing parameters on the phase purity, particle size, and powder morphology of CaCu3Ti4O12 and to study the effect of microstructure, sintering condition on the dielectric behavior of CaCu3Ti4O12. The study includes the optimization of different process parameters (ammonium nitrate, citric acid, pH) for synthesis of phase pure CCTO powder following solution combustion route. The optimization of process parameters were based on the phase purity, crystallite size and density. The optimized ratio for synthesis of CaCu3Ti4O12 was found to be 1:3:4:1.5:4 for CaCO3,CuO, TiO(NO3)2, citric acid and ammonium nitrate respectively at pH 1.The powder morphology, particle size, densification behavior and dielectric behavior of the sintered samples has been studied. Increasing sintering time found to enhance the density. The dielectric study showed its dependence upon sintering time, grain size and density. Dielectric property increases with increase in sintering time and density. An attempt has also been made to study the effect of lanthanum substitution at A site on the properties of CCTO ceramics.