engleski

Formation of Eu3Fe5O12 studied by XRD, 57Fe and 151Eu Moessbauer and FT-IR spectroscopies

The evolution of oxide phases in the Eu2O3-Fe2O3 system was investigated by X ray powder diffraction, 57Fe and 151Eu Mössbauer spectroscopy and Fourier transform infrared spectroscopy. Samples were prepared by the solid state reaction of the corresponding oxides for two molar ratios, Eu2O3 : Fe2O3 = 1 : 1 and 3 : 5. After heating the mixed oxide powder with molar ratio Eu2O3 : Fe2O3 = 1 : 1 up to 900 oC, EuFeO3 and traces of Eu2O3 were detected by XRD, while after additional heating up to 1100 oC traces of Eu3Fe5O12 (EuIG) were also detected. 57Fe and 151Eu Mössbauer spectroscopy showed the presence of EuFeO3. For the molar ratio Eu2O3 : Fe2O3 = 3 : 5, EuIG was formed between 1100 and 1300 oC. In the sample produced at 1300 oC, the measured hyperfine fields at the iron sites at room temperature were Ha = 495 and Hd = 402 kOe, and the hyperfine fields at the europium sites, at 90 K, were HI = 631 kOe and HII = 572 kOe. Europium orthoferrite was the intermediate phase in the garnet formation. The assignations of IR bands corresponding to EuFeO3 and EuIG were discussed. Mechanical activation of the mixed oxide powder was important for the formation of polycrystalline EuIG, as a single phase.

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