CHEMICAL AND STRUCTURAL-PROPERTIES OF THE SYSTEM FE2O3-IN2O3

The system Fe2O3-In2O3 was studied using X-ray diffraction, Fe-57 Mossbauer spectroscopy and infrared spectroscopy. The samples were prepared by chemical coprecipitation and thermal treatment of the hydroxide coprecipitates. For samples heated at 600-degrees-C, a phase, alpha-(Fe(1-x)In(x))2O3, isostructural with alpha-Fe2O3, exists for 0 less-than-or-equal-to x less-than-or-similar-to 0.8, and a phase C-(Fe(1-x)In(x))2O3, isostructural with cubic In2O3, exists for 0.3 less-than-or-similar-to x less-than-or-equal-to 1. In the two-phase region these two phases are poorly crystallized. An amorphous phase is also observed for 0.3 less-than-or-similar-to x less-than-or-similar-to 0.7. For samples heated at 900-degrees-C the two-phase region is wider and exists for 0.1 less-than-or-similar-to x less-than-or-similar-to 0.8 with the two phases well crystallized. In these samples an amorphous phase is not observed. Fe-57 Mossbauer spectroscopy of samples prepared at 600-degrees-C indicated a general tendency of the broadening of spectral lines and the decrease of numerical values of the hyperfine magnetic field (HMF) with increasing molar fraction In2O3 in the system Fe2O3-In2O3. The samples prepared at 900-degrees-C, in the two-phase region, are characterized by a constant HMF value of 510 kOe at room temperature. Infrared spectroscopy was also used to follow the changes in the infrared spectra of the system Fe2O3 In2O3 with gradual increase of molar fraction of In2O3. A correlation between X-ray diffraction, Mossbauer spectroscopic and infrared spectroscopic results was obtained.