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 < 0.4. Mixed valent Mn cations and cation vacancies, therefore, exist in all the samples. The samples with 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 16 K. 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.
X. Zhou and L. R. Pederson and Q. Cai and J. Yang and B. J. Scarfino and M. Kim and W. B. Yelon and W. J. James and H. U. Anderson and C. Wang, "Structural and Magnetic Properties of La Mn₁₋ₓFeₓO₃ (0 < x < 1.0)," Journal of Applied Physics, vol. 99, American Institute of Physics (AIP), Apr 2006.
The definitive version is available at https://doi.org/10.1063/1.2176389
Materials Science and Engineering
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© 2006 American Institute of Physics (AIP), All rights reserved.
01 Apr 2006