Studying Ni-B alloys with X-ray photoelectron spectroscopy

Ni and Ni-B films that contain 4–20 at % boron are produced by electroplating from baths containing sodium decahydroclovodecarborate and borane-morpholine as boron sources. The chemical state of Ni, B, and O atoms on the original film surface, as well as in that etched to 1 μm or annealed in air at 700°C was determined using X-ray photoelectron spectroscopy (XPS). Judging from the absolute values and directions of the peak shifts in XPS spectra of freshly obtained films, it is assumed that Ni and B atoms chemically interact with each other and Ni-Ni bonds are replaced by shorter Ni-B bonds. Boron is segregated in the surface layer of Ni-B films and hampers the thermal oxidation of nickel.