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57Fe Mössbauer Spectroscopy on Disordered Crystalline Media with Ca-Gallogermanate Type Structure, II Below the Magnetic Ordering Temperature

Domenii publicaţii > Fizica + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: D.Barb, S.Constantinescu and D.Tarina

Editorial: Hyperfine Interactions, 96, p.83-89, 1995.


Magnetic phase transitions in disordered crystalline iron germanates of the type Sr2 LnFe3 Ge3 O14 (Ln= La; Nd) were observed at low temperatures by means of 57Fe Mössbauer spectroscopy. The hyperfine interactions of Fe3+ magnetic moments ordered in one octahedral and two tetrahedral magnetic sublattices are discussed. A local environment computation on the octahedral sites confirms the assumption that the wide distribution found for the 4.2K octahedral hyperfine fields is due to the random occupation by Fe3+ and Ge4+ ions of the nearest cation environment of the octahedral iron. The effect of the substituting Ln rare earth ions in the Thompson cubes on the magnetic behavior of these compounds is pointed out.

Cuvinte cheie: Ca-gallogermantes, Magnetig ordering, Mossbauer spectroscopy