title: Mössbauer investigations of crystalline and quasicrystalline Al3(Mn, Fe) compounds.
abstract: (57)Fe Mössbauer and magnetic measurements are reported on Taylor phase compounds T-Al(3)(Mn,Fe), which can be seen as complex metallic alloys. The orthorhombic unit cell contains 156 atoms. These investigations are further extended to Al(71)Mn(19)Fe(10) crystallizing as a decagonal quasicrystal. Common to both structures are layers, which are oriented perpendicular to the b axis in the crystalline or to the periodic axis in the quasicrystalline compound, allowing the formation of characteristic building blocks. At low temperatures for all samples spin glass behavior is observed with freezing temperatures T(f) increasing with Fe content. Above T(f) the (57)Fe Mössbauer spectra were analyzed by a superposition of two subspectra with intensity ratio around 75:25, which can be allocated to Fe substituted on Mn sites surrounded either by Al and Mn or solely by Al with Mn only at the edge of the nearest neighbor shell. For both subspectra quadrupole splitting and center shift do not change significantly with Fe content and with structure. Below T(f) broad hyperfine field distributions with non-vanishing contributions at zero hyperfine field are present. Magnetic and electrostatic hyperfine interactions are governed by length scales which are determined by the very similar interatomic configurations forming the T-Al(3)Mn phase as well as the decagonal compound. The presence of long range atomic order is of less importance.
authors.affiliation: Institut für Festkörperphysik, Technische Universität Wien, Austria.
authors.forename: K
authors.initials: K
authors.lastname: Ali
authors.forename: M
authors.initials: M
authors.lastname: Reissner
authors.forename: W
authors.initials: W
authors.lastname: Steiner
authors.forename: M
authors.initials: M
authors.lastname: Feuerbacher