The influence of crystalline grain size on the thermal stability of the Er0.45Ho0.55Fe2 compound

The phase composition and the temperature dependence of the magnetization of the Er_0.45Ho_0.55Fe₂ compound in coarse-grained, microcrystalline, and submicrocrystalline states are investigated experimentally. It is found that, upon heating under vacuum, the Er_0.45Ho_0.55Fe₂ microcrystalline powder with a crystalline grain size of ～1 µm undergoes decomposition into pure iron and rare-earth (erbium and holmium) oxides and nitrides at a temperature of 500 K. The changes observed in the phase composition of the microcrystalline powder due to annealing are confirmed by x-ray diffraction analysis. Heating of the Er_0.45Ho_0.55Fe₂ submicrocrystalline sample leads to a partial change in the phase composition. The phase composition of a large crystal (～1 mm in size) remains unchanged upon heating to 1080 K. It is shown that the thermal stability of the Er_0.45Ho_0.55Fe₂ compound depends on the crystalline grain size.