CHARACTERIZATION OF OXIDE PHASES FORMED DURING THE SYNTHESIS OF ER3FE5O12

The mixed hydroxide 3Er(OH)(3) + 5Fe(OH)(3) was thermally treated up t o 1300 degrees C. The samples obtained up to 650 degrees C were amorph ous as observed by X-ray diffraction (XRD), The first appearance of Er 3Fe5O12 (ErIG) was observed in the sample obtained at 750 degrees C. T he Fe-57 Mossbauer spectrum of the mixed hydroxide 3Er(OH)(3) + 5Fe(OH )(3) at room temperature was characterized by a quadrupole doublet (de lta(Fe) = 0.38, Delta = 0.80, and Gamma = 0.50 mm s(-1)). After heatin g the starting material to 650 degrees C, the superposition of two qua drupole doublers and of a sextet of very small intensity with H = 506 kOe was observed. This result indicated that the amorphous fraction, d etected by XRD, actually contained an additional Fe-bearing oxide phas e of very fine particles which probably exhibited poor crystallinity, The sample obtained at 1300 degrees C was characterized by two hyperfi ne magnetic fields at room temperature with H-d = 394 and H-a = 489 kO e corresponding to ErIG, Selected samples were also characterized by l aser Raman spectoscopy. (C) 1997 Elsevier Science B.V.