563 research outputs found
Electronic structure of the sigma-phase in paramagnetic Fe-V alloys. Experimental and theoretical study
The electronic structure of -phase FeV compounds with
33.3 was calculated from the charge self-consistent
Korringa-Kohn-Rostoker method. For the first time, charge densities
and electric field gradients were determined at Fe nuclei, that occupy five
nonequivalent lattice sites. The highest values were found on sites
A and D, and the lowest one on site B, the difference ranging between 0.162 and
0.174 -like electrons per Fe atom for and ,
respectively. The calculated quantities combined with experimentally determined
site occupancies were successfully applied to analyze Fe M\"ossbauer
spectra recorded on a series of 8 samples in a paramagnetic state.Comment: 4 pages, 4 figures, 15 reference
Anomalous behavior of the Debye temperature in Fe-rich Fe-Cr alloys
Debye temperature, , of Fe-rich FeCr disordered
alloys with was determined from the temperature dependence of
the central shift of M\"ossbauer spectra recorded in the temperature range of
60 -- 300 K. Its compositional dependence shows a maximum at with
a relative increase of % compared to a pure iron. The composition at
which the effect occurs correlates well with that at which several other
quantities, e. g. the Curie temperature and the spin-wave stiffness
coefficient, , show their maxima, but the enhancement of is
significantly greater and comparable with the enhancement of the hyperfine
field (spin-density of itinerant -like electrons) in the studied system. The
results suggest that the electron-phonon interaction is important in this alloy
system
Short-Range Order in Fe-Rich Fe-Cr Alloys as Revealed by M\"ossbauer Spectroscopy
Distribution of Cr atoms in Fe_{100-x}Cr_x alloys with x \le 25 within the
first two coordination shells, 1NN-2NN, around probe 57Fe atoms was studied by
means of the M\"ossbauer Spectroscopy. Clear evidence was found that the
distribution is characteristic of a given atomic configuration. Only the
configurations with Cr atoms situated in 2NN exhibit a quiasi-random
distribution, while those with Cr atoms present in 1NN shell and those with Cr
atoms in both shells is evidently not random showing clastering or
anticlastering features. These findings are novel and much more complete than
the up-to-date knowledge according to which there is an inversion of the
short-range order parameter at x = 11. The inversion in the present study was
found only for the configuration with one Cr atom in 1NN. On average, Cr atoms
are distributed almost randomly within the 1NN-2NN volume for x \eq ~10, and do
cluster for larger x.Comment: 4 pages and 4 figure
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