Optical properties of α-Fe2O3microcrystals in the infrared

Abstract
Since haematite ( alpha -Fe2O3) microcrystals are available with well defined shape (sphere, spindle and disc) and size homogeneity, the authors have been able to check the validity of the classical theory of absorption of radiation by small particles in the infrared. The agreement between observed and calculated infrared spectra is very good once particle aggregation is taken into consideration. Comparison between calculated and experimental IR spectra also affords a useful method for determination of the relative orientation of the crystallographic axes in the morphological coordinate frame.