A combined temperature dependent57Fe Mössbauer and single crystal X-ray diffraction study of synthetic almandine: evidence for the Gol'danskii-Karyagin effect
✍ Scribed by C. A. Geiger; Th. Armbruster; G. A. Lager; K. Jiang; W. Lottermoser; G. Amthauer
- Publisher
- Springer-Verlag
- Year
- 1992
- Tongue
- English
- Weight
- 630 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0342-1791
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✦ Synopsis
Synthetic almandine garnet, Fe3A12Si3012, has been studied by temperature -dependent single crystal X-ray diffraction and 57Fe M6ssbauer spectroscopy. The Fe 2+ doublet in almandine is characterized by a small asymmetry between the high and low-velocity peaks that decreases in magnitude with decreasing temperature from 420 to 15 K. The X-ray results show that the Fe 2+ cation is dynamically disordered with an anisotropic motion within the eight-coordinated site in garnet. The magnitudes of the X-ray determined mean-square-vibrational amplitudes of this motion parallel, x It, and perpendicular, x• to the principle axes of the electric field gradient give a calculated angular dependence of the electric quadrupole interaction of the I1/2 to I3/2 transitions that agree with the experimentally measured peak ratios. This is the first recognition of anisotropic recoil free fraction of 57Fe in silicates.