Structural and Electrical conductivity of Mn doped Hematite (α-Fe2O3) phase

We investigate the structural and transport properties of Mn doped hematite (alpha-Fe2O3). The X-ray diffraction pattern identifies the single-phase and corundum (Al2O3) type structure of the polycrystalline samples Fe2-xMnxO3 (x = 0, 0.01, 0.10 and 0.50). The resistivity curve shows a Morin transition (T-M) in hematite (alpha-Fe2O3) at about 262 K. As the Mn-content increases in the solid solution of hematite (alpha-Fe2O3), the number of pairs of (Fe2+, Fe3+) and (Mn2+, Mn3+) in the solid solution increases which changes the conductivity of the solid solution. The Mn doping influences the Morin transition and TM shifts towards lower temperatures on enhanced doping. For higher doping, TM is further suppressed significantly. The Raman measurements of alpha-Fe2O3 samples shows seven Raman active modes at A(1g)(1) congruent to 225 cm(-1), E-g(1) congruent to 249 cm(-1), E-g(2) congruent to 292 cm(-1), E-g(3) congruent to 297 cm(-1), E-g(4) congruent to 409 cm(-1), E-g(5) congruent to 496 cm(-1), and A(1g)(2) congruent to 609 cm(-1). Mossbauer spectroscopy probes the site preference of the substitutions and their effect on the hyperfine magnetic fields clearly show the presence of ferric (Fe3+) state and strong magnetic ordering in all samples. (C) 2011 Elsevier B.V. All rights reserved.