From Chemical to Structural Order of Electrodeposited Ni22P Alloy: An XPS and EDXD Study

Amorphous electrodeposited nickel-phosphorus alloys with 22 at. % of phosphorus (Ni22P) have been analyzed in the amorphous and re-crystallized state by EDXD and XPS surface analysis. The re-crystallization kinetics have been determined following in situ structural changes by EDXD. Distinct diffraction patterns indicating the presence of Ni3P confirm alloy recrystallization at 645 C. The XPS results show that all the core level binding energies of nickel such as Ni2p3/2 and Ni2p1/2 and phosphorus (P2p, P2s) remained constant after the change from X-ray amorphous to crystalline structure of the NiP alloy. Differences observed were as follows: (a) the binding energy difference between the Ni2p main lines and the satellite, (b) the fine structure of the NiLMM Auger lines, and (c) the density of states in the valence band in the region of the Ni3d electrons. On the basis of these results from EDXD and XPS, it can be concluded that the change in alloy structure from Xray amorphous to crystalline influences the electronic structure of the NiP alloy but not the chemical state of phosphorus. An explanation based on the screening model proposed in the literature is discussed.