Effect of the annealing temperature on the structural and magnetic behaviors of 0.875La0.6Ca0.4MnO3/0.125La0.6Sr0.4MnO3 composition

Abstract

The polycrystalline compounds of La0.6Ca0.4MnO3 (S0C1) and La0.6Sr0.4MnO3 (S1C0) were prepared using the citric–gel method. With the resultant nanoparticle powders having crystallite size of 22.51nm from S0C1 and 27.39nm from S1C0, the 0.875(S0C1)0.125(S1C0) composition was sintered at different temperatures: SC. 4-1 (at 700°C), SC. 4-2 (at 900°C), SC. 4-3 (at 1100°C) and SC. 4-4 (at 1300°C). XRD data were analyzed by Rietveld refinement technique. The two S0C1 and S1C0 mother compounds were found to crystallize in the rhombohedral and orthorhombic structure, respectively. The compounds sintered at 700°C (SC. 4-1) and 900°C (SC. 4-2) were found to present the two rhombohedral and orthorhombic phases corresponding to the mother compounds, which indicates that no interfacial reaction occurs. However, when augmenting the sintering temperature, the formation of the 0.875(S0C1)0.125(S1C0) new phase was observed. These observations were confirmed from the magnetization study, which revealed that the SC. 4-1 and SC. 4-2 compounds present two magnetic transitions temperature corresponding to the two mother compounds. For higher sintering temperature (1100 and 1300°C), we have noted the presence of a new magnetic transition corresponding to the composition 0.875(S0C1)0.125(S1C0) compound. The variation of the M(T) curves were discussed in terms of the orthorhombic distortion σ2(Mn–O).