Abstract:
X-ray diffractometric studies of the structural state of simple rare-earth oxides Gd$_2$O$_3$, Sm$_2$O$_3$ and Eu$_2$O$_3$ were carried out, synthesized by different methods, at the first stages of crystal formation. It was found that the first crystalline phase of these compounds in the nanocrystalline state is not a known cubic modification with the spatial symmetry group S.G. Ia-3 (206), but tetragonal phases, whose spatial groups are not established due to the small number of strong reflexes in the nanostate. It is also shown that the same tetragonal phases are formed in industrial powders of these compounds subjected to long-term storage.
Keywords:synthesis of Re$_2$O$_3$, glycine-nitrate method, nanocrystalline state, X-ray diffraction research methods, phase transitions.
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