Surface structure of the (111) face of the non-ordered Fe32%Ni alloy

The structure of the fcc (111) face of the Fe32%Ni alloy has been determined by LEED intensity analysis. The choice of an alloy with two constituents of similar Z number simplified modeling of the non-ordered structure and resulted in one of the best R-factors in a structure determination by this lab. In this study both the Debye temperature and the “bulk” lattice constant were determined experimentally since reliable data is not available as a function of concentration. IV profiles using models with a range of different lattice constants led to different results for best value of contraction (relaxation) of surface interlayer spacing upon comparison with experiment. The negative correlation between surface interlayer spacing and bulk lattice constant for good R-factor shows importance of using correct lattice constant in alloy studies.