THE INFRARED DIELECTRIC-PROPERTIES OF MAGHEMITE, GAMMA-FE2O3, FROM REFLECTANCE MEASUREMENT ON PRESSED POWDERS

The infrared complex permittivity functions of three varieties of magh emite, gamma - Fe2O3, having different degrees of vacancy ordering, ha ve been determined from their IR reflectance spectra, measured at near to normal incidence on pressed powder pellets. The optical constants therefrom obtained have been verified by using them in the simulation of the corresponding absorption spectra for KBr-diluted pellets, and t hese are in excellent agreement with the experimental spectra. All cal culations are based on a procedure for the estimation of the effective dielectric function of a mixture, which incorporates percolation feat ures, recently developed by the authors.