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 (Ts) amorphous films were formed, at Ts = 300–500 K – amorphous–crystal condensates, and at Ts > 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.