Influence of synthesis methods and calcination temperature on electrical properties of La1−xCaxMnO3 (x=0.33 and 0.28) ceramics

La1−xCaxMnO3 (x=0.33 and 0.28) powders were prepared by both coprecipitation and sol-gel methods. Circular pellets with different radial shrinking ratios (RSR) were obtained by changing the calcination temperature of the powders. The influence of the powder synthesis process and the shrinking ratio of the sample on the structural, morphological and electrical properties of the ceramics were investigated. It has been found that sol-gel method is more efficient and stable to obtain ceramic samples with good electrical properties. The radial shrinking ratio of the ceramic increases with the decreasing calcination temperature. The experimental results show that RSR significantly affects the electrical properties of the ceramics prepared by coprecipitation method and has negligible influence on the samples made by sol-gel method. The coprecipitation samples with larger RSR have higher insulator to metal transition temperature Tp which is comparable to that of the sol-gel samples.