Improvement in electronic and magnetic transport of La0.67Ca0.33MnO3 manganites by optimizing sintering temperature

La0.67Ca0.33MnO3 samples with high temperature coefficient of resistance have been synthesized by sol-gel method using methyl alcohol as solvent. Nitrates of La, Ca and Mn were heated with a controlled amount of methyl alcohol to get a dry powder which on suitable heat treatment gave high grade La0.67Ca0.33MnO3 powder/pellets. The samples were sintered in the temperature varied from 1000 degrees C to 1550 degrees C. The effects of sintering temperature (T-s) on phase purity, microstructure, morphology, electrical and magnetic transport properties have been investigated. The results confirm that elevated sintering temperature at sintering processing accelerates the growth of the specimen grains, influence microstructure and improves chemical homogeneity, which leads to the increased lattice distortion and thus contributes to the enhancement of magneto-resistance. The reduction of the grain boundaries contributes to the reduction of resistivity and the enhancement of the coefficient of resistance. The increase of the oxygen vacancy induced by the increase of Ts will lead to mono-tonous decrease of the metal-insulator transition tempera-ture (T-p), the peak of temperature for the maximum temperature coefficient of resistance (T-k) and for the peak of maximum magneto-resistance (T-m).