Electronic structure of the Fe-Cu-Nb-Si-B alloys by x-ray absorption spectroscopy

We measured x-ray absorption near-edge-structure (XANES) spectra of nanocry stalline- (nc-) and amorphous- (a-) Fe73.5Cu1Nb3Si13.5B9 (nc-FCNSB and a-FC NSB) and Fe78Si13B9 (a-FeSiB) alloys at the Fe L-3,L-2 edge using the sampl e drain current mode and at the Cu L-3,L-2, and Nb L-3 edge and Si K edge u sing the fluorescence mode. The features in the Fe L-3-edge XANES spectrum of nc-FCNSB changed shape significantly with the addition of Cu and Nb to t he Fe-Si-B alloy under the optimum annealing conditions, indicating that Cu and Nb strongly influence the Fe 3d local electronic structure. Closely ex amining the Cu L-3,L-2-edge XANES spectrum of nc-FCNSB reveals that the Cu clusters essentially have a body-centered-cubic structure. The white-line f eatures at the Nb L-3 edge suggest a slight increase in delocalization of N b 4d orbits when a-FCNSB is crystallized into nc-FCNSB. The Si K-edge XANES spectrum demonstrates the dominance of Fe-Si bonds around the Si atom in n c-FCNSB. (C) 2000 American Institute of Physics. [S0003-6951(00)00424-1].