Influence of alkali substitution in La0.7Ca0.3Mn0.8Cr0.2O3 perovskite manganite on structural, magnetic, and transport properties

摘要： In order to study the effect of A-site cation mismatch on the structural, magnetic, and transport properties, a systematic investigation of La0.7Ca0.25A0.05Mn0.8Cr0.2O3 (A = Ca, Li, Na, K) has been undertaken. The XRD data of the materials, prepared by glycine-nitrate combustion method, have been analyzed by Rietveld refinement technique. The iodometric and EDX results show that except K doped sample, the desired stoichiometry of all the phases remains the same. The phases display a paramagnetic to ferromagnetic transition at low temperature with Tc found to decrease with decreasing ?rA?. It has been concluded that the conduction mechanism was dominated by small polaron hopping model in the high temperature paramagnetic semiconducting region.