NUKLEONIKA 2004, 49(Supplement 3):s3-s6

FIRST PRINCIPLES STUDY OF THE ISOMER SHIFT IN Fe44M6Al50 (M = Ti, V, Cr, Co, Ni, Cu) ALLOYS WITH B2 STRUCTURE

Tomasz Michalecki, Józef Deniszczyk, Janusz E. Frąckowiak

Institute of Material Science, University of Silesia, 12 Bankowa Str., 40-007 Katowice, Poland

The 57Fe isomer shift for Fe44M6Al50 intermetallics with the B2 structure doped with M = Ti, V, Cr, Co, Ni and Cu additions has been calculated with the tight-binding linear muffin-tin orbital (TB-LMTO) method. The effect of variation of Wigner-Seitz (WS) spheres radii on the calculated equilibrium lattice parameter (a) and isomer shift (IS) was analyzed. The calculations have shown that the 57Fe isomer shift in Fe44M6Al50 intermetallics is directly proportional to the changes in the local 4s electronic charge at Fe atoms involved by M addtions. The screening effect of 4s electrons due to changes in (4p + 3d) electronic charge is of secondary importance. The calculated dependence of the average IS on nuclear charge (Z) of the alloying metal (M) follows qualitatively the tendency observed experimentally for the M impurities in the Fe host.