The BM5Se9 phases: Moessbauer studies of the superconductors and the ferromagnets

Syntheses performed in the A3B/MSe2 (A = Sb, Ga, Sn) (B = Nb, V, Ta) (M = V, Nb, Ta) systems lead to the formation of B(M/A)5Se9 phases which could be ferromagnets or superconductors. It has been shown that the presence of V modifies the superconducting exchanges and allows ferromagnetic couplings. Moessbauer spectroscopy of both 121Sb and 119Sn gives local electronic structure of the SbNb5Se9 superconductor and the Sn0.94Ga0.06V0.30Nb4.70Se9 ferromagnet. For the latter compound, a complete study as a function of temperature is carried out showing that the Sn environment is not modified when the ferromagnetic transition occurs. The Debye temperature is calculated and compared to those obtained for other selenide compounds.