57Fe NCR of Fe phases in “magnetic cassiterites” |
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Authors: | B J Evans E W Sergent Jr |
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Institution: | 1. Department of Chemistry, The University of Michigan, 48104, Ann Arbor, Michigan
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Abstract: | A pyralspite garnet from an anomalously magnetic concentrate of a pegmatitic cassiterite ore has been investigated using 57Fe nuclear gamma-ray resonance spectroscopy. The quadrupole splitting and isomer shift values of 3.6 mm/s and 1.4 mm/s, respectively, are among the largest observed for Fe2+ ions and indicate a very low covalency of the dodecahedral Fe2+ — O2-bonds. These data support the more recent and lower value (10.2–10.1 kcal/ mole) of White and Moore (1972) for the CFSE of the dodecahedral Fe2+ ion and suggest that the CFSE should be a useful approximation to the site preference energy of Fe2+ for this site. |
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