Ab-initio, Mossbauer spectroscopy, and magnetic study of the approximant Al72Ni9Fe19 to a decagonal Al-Ni-Fe quasicrystal

作者：Nejadsattari Farshad; Stadnik Zbigniew M; Przewoznik Janusz; Grushko Benjamin

来源：Journal of Alloys and Compounds, 2016, 689: 726-732.

DOI：10.1016/j.jallcom.2016.08.021

• Paramagnet
• Fe-57 Mossbauer spectroscopy
• Electric quadrupole splitting
• Pseudogap in the density of states
• Debye temperature

We report the results of ab-initio electronic structure and electric field gradient calculations and of X-ray diffraction, Fe-57 Mossbauer spectroscopy, and magnetic studies of the approximant Al72Ni9Fe19 to a decagonal Al-Ni-Fe quasicrystal. The approximant crystallizes in the hexagonal space group P63/mmc with the lattice parameters a = 7.6989(2) A ($) over circle and c = 7.6724(2) A ($) over circle. A pseudogap in the density of states, centered at similar to 0.30 eV above the Fermi level and with a width of similar to 0.35 eV, is found. Evidence for the covalent nature of the chemical bonding and good metallicity of Al72Ni9Fe19 is provided. The Mossbauer spectra and a 1/T-like dependence of the magnetic susceptibility indicate that Al72Ni9Fe19 is a paramagnet down to 2.0 K. The shape of the Mossbauer spectra is accounted for by a superposition of two quadrupole doublets corresponding to Fe atoms located at two inequivalent crystallographic sites. A sudden change of the quadrupole splittings of the two doublets at similar to 200 K indicates a possible structural phase transition. Excellent agreement between the calculated and measured quadrupole splittings is observed. The Debye temperature of Al72Ni9Fe19 is found to be 431 (3) K.

• 出版日期2016-12-25