Influence of Cr and Mn substitution on the structural and spectroscopic properties of doped haematite: α-Fe2−xMxO3 (0.0 ⩽ x < 0.50)

Abstract

Solid-state ceramic route technique is used for synthesizing Cr and Mn doped haematite α-Fe2−xMxO3. The X-ray diffraction pattern identifies the single phase and corundum (Al2O3) type structure of the polycrystalline samples α-Fe2−x MxO3 (M=Cr and Mn; x=0, 0.10, and 0.50). The Raman measurements of α-Fe2O3 samples shows seven Raman active modes at A1g(1)≅225cm−1, Eg(1)≅249cm−1, Eg(2)≅292cm−1, Eg(3)≅297cm−1, Eg(4)≅409cm−1, Eg(5)≅496cm−1, and A1g(2)≅609cm−1.On substitution of Cr and Mn (x=0.1, and 0.50) at Fe site, all Raman active modes are shifted to higher wavenumber. The observed isomer shift values from room temperature Mössbauer data clearly show the presence of ferric (Fe3+) state and strong magnetic ordering in all samples. The observed isomer shift δ values from room temperature Mössbauer data clearly show the Fe is in Ferric (Fe+3) nature. In doped haematite Cr+3 and Mn2+ ions illustrating strong Ferro magnetic ordering up to (x=0.10) and weak Ferro magnetic ordering for α-Fe2−xMxO3 (x>0.10) haematite.