Fe-57 Mossbauer spectroscopy study of the AFe(x)Al(12-x) intermetallics (A=Y, Tm, Lu and U, 4 <= x <= 4.3)

AFe(x)Al(12-x) intermetallics (A=Y, Tm, Lu and U, 4 less than or equal tox less than or equal to4.3) were synthesized as polycrystalline material and as large single crystals by the Czochralski method from bulk charges contai ning A, Fe and Al in the atomic I ratios 1/4/8. The purity of the studied s amples was checked hv powder X-ray diffraction and their final composition was estimated using the Rietveld method of structure refinement, The Fr-S7 Mossbauer spectra of samples with final composition x>4 have revealed that the Fe atoms on the same crystallographic site may have different magnetic moments, mu (Fe), whose values increase with the number of Fe nearest neigh bours. Tile strong sensitivity of the mu (Fe), on small deviations from the ideal 1/4/8 stoichiometry has clearly shown that while the single crystals of UFe4Al8 grown by the Czochralski method have the expected composition, those grown from YFe4XL8 and LuFel(4)Al(8) bulk charges have actual composi tions YFe4.2(1)Al7.S(1) and LuFe4.2(1)Al7.8(1) thus explaining contradictor y results that have been previously published. (C) 2001 Elsevier Science B. V. All rights reserved.