A single-crystal sample of a DO3-ordered Fe3Si compound was studied by means of the 57Fe Mossbauer spectroscopy. Spectra have been recorded in a transmission geometry in the temperature range between 5 and 850 K. They have been analyzed either in terms of five sextets or five hyperfine field distribution curves. Concerning the former three sub spectra have been attributed to Fe atoms occupying the B sites and having 8Fe, 7Fe1Si and 6Fe2Si atoms in the first coordination shell (1NN), respectively, and two have been attributed to Fe atoms residing on the A and C sites and having 4Fe4Si and 3Fe5Si atoms in the 1NN, respectively. Based on the temperature dependence of the center shifts values the Debye temperature, T_D, have been determined. TD was found to be equal to 491 (11) K for the sites A and C, and to 403 (3) K the site B. The smaller value of T_D coincides with the smaller values of the hyperfine field, H. Changes in H caused by one Si atom present in the 1NN have been determined as ca.13 kOe for Fe atoms occupying the A and C sites and ca.54 kOe for Fe atoms present on the B sites. These changes have been also expressed in terms of the underlying number of polarized s-like electrons, dNs. For the Fe atoms situated on the A and C sites dNs=0.03 was found while for those occupying the B sites dNs=0.17.
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