Next-nearest neighbour contributions to P 2p3/2 X-ray photoelectron binding energy shifts of mixed transition-metal phosphides M1−xM′xP with the MnP-type structure

X-ray photoelectron (XPS) and X-ray absorption (XANES) spectroscopic measurements have been made for several series of mixed transition-metal phosphides M1−xM′xP (Co1−xMnxP, Mn1−xVxP, and Co1−xVxP), which adopt the MnP-type structure (M is more electronegative than M′). The P 2p binding energy shifts displayed by the mixed metal phosphide members do not follow the trend shown by the simple binary phosphides, a deviation which arises from the contribution of next-nearest neighbour effects operating on the primary photoemission site. The magnitude of this contribution can be derived from a simple charge potential model taking the metal electronegativity differences into account. It is suggested that these next-nearest neighbour contributions induce a charge transfer between the two dissimilar metals via metal–metal bonding, which modifies the Madelung potential experienced at the photoemission site. This charge transfer has been confirmed by analysis of the Co 2p XPS spectra as well as the P and Mn K-edge XANES spectra.

Graphical abstractThe mixed phosphides Co1–xMnxP, Mn1–xVxP, and Co1–xVxP with the MnP-type structure have been studied by use of XPS and XANES. The P 2p binding energies in the mixed phosphides display shifts relative to the binary phosphides that cannot be explained by interaction of the nearest neighbours alone.Figure optionsDownload full-size imageDownload as PowerPoint slide