The magnetic properties and charge-ordering state in La1-xCaxMnO3 (x = 0.46; 0.50) compounds

Abstract

The compounds of La1-xCaxMnO3-δ with x=0.46 and 0.50 occupy special positions in the phase diagram of La1-xCaxMnO3-δ system due to their interesting properties and charge-ordering phase transition. The samples were prepared by a solid-state reaction method. The XPD patterns show that the samples are of a single-phase orthorhombic-perovskite structure. The chemical compositions of the samples are investigated by EDS. The concentrations of oxygen and Mn3+; Mn4+ ions have been determined by dichromate method. The charge-ordering state have been found below 150 K by magnetic and resistance measurements. This phenomenon relates to metal-insulator transition. The results are discussed in competition between double exchange (DE) and super-exchange (SE) interaction