FORMATION AND PROPERTIES OF OXIDE PHASES IN THE SYSTEM ER2O3-FE2O3

Mixed hydroxide, 3Er(OH)(3)+5Fe(OH)(3) was prepared by chemical coprec ipitation. X-Ray diffraction showed that the samples obtained by heati ng the mixed hydroxide at 650 degrees C were amorphous, and contained Er2O3, alpha-Fe2O3, ErFeO3 and Er3Fe5O12 (ErIG) at 750 degrees C. The changes in phase composition of the samples were also monitored by FT- IR spectroscopy. The Mossbauer spectrum of mixed hydroxide, 3Er(OH)(3) +5Fe(OH)(3), at RT was characterized with a quadrupole doublet (delta( Fe)=0.38, Delta=0.80, and Gamma=0.50 mm s(-1)). After heating the star ting material up to 650 degrees C, the superposition of two quadrupole doublets and of a sextet of very small intensity with H=506 kOe was o bserved. This result indicated that the amorphous fraction, as detecte d by XRD, actually contained additional Fe-bearing oxide phase of very fine particles and probably of poor crystallinity. The sample obtaine d at 1300 degrees C was characterized by two hyperfine magnetic fields at RT with H-d=394 and H-a=489 kOe corresponding to ErIG. The results of magnetometric measurements of selected samples were discussed. (C) 1997 Elsevier Science S.A.