A Mössbauer effect investigation of site preferences and Fe environments in Ga-substituted Sm2Fe17 compounds |
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Authors: | R A Dunlap G R MacKay Z Wang |
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Affiliation: | Department of Physics, Dalhousie University, Halifax, Nova Scotia, Canada B3H 3J5 |
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Abstract: | Room temperature 57Fe Mössbauer studies of the 2:17 compounds Sm2Fe17?xGax with x=0, 1, 2, 3, 4 and 5 are reported. These measurements yield values of the Fe hyperfine field and relative concentration of Fe atoms at the four inequivalent transition metal sites, 6c, 9d, 18f and 18h, in the rhombohedral Th2Zn17 structure. Changes in the Fe hyperfine field as a function of Ga content can be correlated to changes in lattice parameter and Curie temperature and are the result of changes in the transition metal-transition metal exchange coupling. The relative intensity of the various spectra components shows that for small concentrations, Ga preferentially enters into the 18h sites. For x & 1 a substantial quantity of Ga also enters into the 18f sites. It is the Ga which enters into the 18f sites which is responsible for the formation of a uniaxial anisotropy in these materials for higher Ga content. |
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Keywords: | Rare earth iron compounds Gallium substitution Site preference 57Fe Mössbauer spectra |
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