METHOD OF OBTAINING THE EMPIRICAL SCATTERING PARAMETERS FOR THE FE-B PAIR FROM THE EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE DATA OF FE-2(B) - POSSIBLE LIMITATIONS

Fe2B as well as Ni2B belong to the Al2Cu(C16)-type structure: body-centered tetragonal. When the Fe K-edge extended x-ray-absorption fine structure (EXAFS) for Fe2B is Fourier transformed with k weighting, the radial structure function (R) shows two well-separated peaks with a sharp minimum in between. Exactly the same shape of (R) was previously obtained in the case of similarly Fourier-transformed Ni K EXAFS for Ni2B, and an approximation was made that the first radial peak in the low-R region comes from the first shell of four B atoms. Thus, for the case of Ni2B, the empirical phase shift and envelope functions for the Ni-B pair were obtained by inverse transforming the low-R-side peak region. However, a careful simulation of the Fourier-transform peaks for Fe2B shows that the first radial peak has some contribution from the next Fe shell and that the sharp minimum originates from the interference between the contributions of closely spaced shells. © 1990 The American Physical Society.