Stability and phase changes in thin layers of rare-earth metals/iron and other binary compounds

The structure, thermal stability and phase transformations in thin Gd-Fe films have been studied. The films were obtained by means of thermal evaporation in vacuum. At room temperature of substrates (T-s) amorphous films were formed, at T-s = 300-500 K - amorphous-crystal condensates, and at T-s > 500K - polycrystalline films. The crystal structure of condensates was determined at various temperatures and crystallization of amorphous films was found to have a heterogeneous character. During crystallization of Gd2Fe17 amorphous films, formation of two phases, viz. Gd6Fe23 and a-Fe was observed. In the films obtained at substrates temperature > 500K, the presence of three phases was established: a hexagonal phase Gd2Fe17 of the Th2Ni17-type structure, a rhombohedral phase Gd2Fe17 of the Th2Zn17-type structure and a hexagonal phase GdFe5 of the CaCu5-type structure. GdFe2 films had a face-centered cubic structure, expected in bulk GdFe2. (C) 2008 Published by Elsevier B.V.