Double coordinence du fer dans la phase Fe xZrSe 2 (0 < x < 0,25): propriétés magnétiques et caractéristiques Mössbauer

The Fe _xZrSe ₂ compounds have been studied from the structural, magnetic, and Mössbauer points of view. The structure of a Fe _0.18ZrSe ₂ single crystal has been refined to a final 0.067 R factor value. Iron disorderly occupies both octahedral and tetrahedral voids of the Van der Waals gap of ZrSe ₂. The Curie constants are consistent with the Fe(II) state. Negative θ_p show that interactions are predominantly A.F. For x < 0.18, χ^-1 tends toward zero with temperature. For x ≥ 0.18, a susceptibility maximum occurs for T ⋍ 7 K. Mössbauer spectra have been fitted considering two components: a singlet (tetrahedral Fe ^II) and a doublet octahedral Fe ^II) broadened by the □-Fe disorder. The Mössbauer parameters and their thermal evolution are discussed.