Characterization of oxide phases formed during the synthesis of Er3Fe5O12

The mixed hydroxide 3Er(OH)(3) + 5Fe(OH)(3) was thermally treated up to 1300 degrees C. The samples obtained up to 650 degrees C were amorphous as observed by X-ray diffraction (XRD), The first appearance of Er3Fe5O12 (ErIG) was observed in the sample obtained at 750 degrees C. The Fe-57 Mossbauer spectrum of the mixed hydroxide 3Er(OH)(3) + 5Fe(OH)(3) at room temperature was characterized by a quadrupole doublet (delta(Fe) = 0.38, Delta = 0.80, and Gamma = 0.50 mm s(-1)). After heating the starting material to 650 degrees C, the superposition of two quadrupole doublers and of a sextet of very small intensity with H = 506 kOe was observed. This result indicated that the amorphous fraction, detected by XRD, actually contained an additional Fe-bearing oxide phase of very fine particles which probably exhibited poor crystallinity, The sample obtained at 1300 degrees C was characterized by two hyperfine magnetic fields at room temperature with H-d = 394 and H-a = 489 kOe corresponding to ErIG, Selected samples were also characterized by laser Raman spectoscopy. (C) 1997 Elsevier Science B.V.