Structural and magnetic properties of LaMn1−xFexO3 (0<x<1.0)

Electronic, structural, and magnetic properties of Mn-doped lanthanum ferrites were studied by neutron diffraction, superconducting quantum interference device, and impedance spectroscopy. Neutron diffraction refinements were performed with the constraint of full La occupancy, which showed the presence of excess oxygen when x 0.7 are magnetically ordered at room temperature with orthorhombic symmetry (Pbnm). When x<0.3 the structure is rhombohedral and magnetically disordered above 16K. The majority carriers, electron holes, correspond to high oxidation states of Mn. The carrier concentration is determined from the Seebeck coefficients, and is a function of temperature and Fe concentration. The measurements of conductivity and Seebeck coefficients show polaron hopping at elevated temperatures.