Structural and Electrical conductivity of Mn doped Hematite (α-Fe 2O 3) phase

Abstract

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