Ga site occupancy in HDDR-treated Nd2Fe14B-based alloy by XAFS

The changes of local structure far Ga in Nd13.0Fe68.2Co10.8Ga1.0Zr0.1B6.9 d uring hydrogenation, disproportionation, desorption and recombination (HDDR ) process are studied by fluorescence XAFS in order to understand the evolu tion of magnetic anisotropy by HDDR process. Comparing the observed Ga XAFS data with the calculated ones, using ab initio calculation (FEEF), Ga is p roved to occupy preferentially an Fe(c) site in the Nd2Fe14B structure befo re disproportionation and dissolves in alpha-Fe after the disproportionatio n. In the recombined state Ga redistributes into two phases, i.e. Nd2Fe14B and a Nd-rich phase. The behavior of Ga during the HDDR process differs fro m Zr which occupies Fe(j(2)) sites before disproportionation and after the disproportionation. (C) 1999 Elsevier Science S.A. All rights reserved.