Polarized Infrared Spectroscopy of Textured Hematite (α-Fe2O3) Microcrystals

Polarized far-infrared spectroscopy analysis is presented on highly [210] textured α-Fe₂O₃ microcrystals grown on pure Fe substrate, using a facile and one step process. Main objective is to understand relationship between intensity of A_2u and E_u modes with incident polarization. In literature, the shape of E_u band at 460 cm⁻¹ was shown to be sensitive on crystallinity, particle shape and size. In this report it is shown that shape of this E_u band also varies the most with polarization compared to the other bands. The observed variation is attributed to different response of LO and TO components of the E_u band to incident polarization. The intensity of A_2u modes remains almost unchanged whereas that of the E_u modes shows a systematic variation. The observed intensity variation has been elucidated on the basis of direction of the texture and experimental geometry of measurement. A simulation of intensity of the E_u modes is presented, which shows cos²θ variation with different phase shifts and matches well with the experimental data.