Magnetostrictive Fe 100−x Ga x alloys over the composition range 0 < x < 36 have been prepared by combinatorial sputtering methods. These films were investigated by x-ray diffraction and 57 Fe Mössbauer effect spectroscopy techniques that have been adapted for the efficient study of combinatorial samples. X-ray diffraction measurements show the presence of a disordered bcc phase with a lattice parameter that increases with increasing Ga content. Mössbauer effect measurements show that even for low Ga content the disordered alloys are not truly random but show some degree of short range Ga clustering. For x > 20, the Mössbauer effect results suggest the presence of short range D0 3 type order. This persists up to the maximum Ga content studied here (x = 36), although there is no evidence to support the formation of long range D0 3 structural order in any of the films prepared in this study.

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Synchrotron radiation S K-and L-edge X-ray absorption near-edge structure (XANES) spectra are reported for the cubic, rocksalt (B1) structure sulfides niningerite (MgS), alabandite (MnS), and oldhamite (CaS), and for their solid solutions (Mn,Fe)S and (Mg,Mn)S, and S L-edge XANES spectra are reported also for (Mg,Fe)S solid solutions. Pre-edge features at the S K-edge are attributed to transition of S 1s electrons to the lowest available unoccupied S 3p s* antibonding states hybridized with metal 3d(e g ) states, and at the S L-edge to transition of S 2p electrons to unoccupied S 3s s*, 4s s*, and 3d antibonding states hybridized with metal 3d(e g ) states, and to a lesser extent 3d(t 2g ) states.The S K-edge XANES spectra for the solid solutions show a progressive participation of 3d orbitals in metal-S bonding with increase in substitution by Fe in (Mn,Fe)S and (Mg,Fe)S and Mn in (Mg,Mn)S through progressive increase in the area of the pre-edge feature. However, the pre-peak area does not increase linearly in each solid solution series showing that a real change in bulk electronic properties has occurred. Increase in pre-peak area reflects an increase in overall attainability of metal 3d states for hybridization with S 3p s* antibonding states as proportionally more metal 3d orbitals become available. The S L-edge XANES spectra show progressive evolution of pre-edge features at the L 3 -and L 2 -edges (a 1 and a 2 , respectively). Only a 2 is present in the S L-edge XANES spectrum of FeS (troilite), and with progressive decrease in Fe content in (Mn,Fe)S and (Mg,Fe)S solid solutions, a 1 first appears, then becomes dominant. Since a 1 is attributed to transition of S 2p 3/2 electrons to S 3s s* states hybridized with metal 3d(e g ) and 3d(t 2g ) states, this appears to represent an increased contribution from metal-S p-bonding. The results show that the size and position of the pre-edge features to the S K-and L-edges are controlled more by the DOS of hybridized 3d(e g b ) and 3d(t 2g b ) states and nearest-neighbor coordination of the metal atoms than by the precise coordination of S and the extended structure of the sulfide.The full multiple scattering approach has been applied to the calculation of the S K-edge XANES spectra of MgS, MnS, and CaS. Results are consistent with experimental XANES spectra, especially for the pre-edge features, which are often neglected in such calculations.Brought to you by |