Abstract
Ni-Mo deposits were obtained from ammoniacal tartrate baths containing various amounts of molybdate and Ni ions. The partial current efficiency of Mo deposition increased gradually with increasing Mo content of the deposits and then decreased to zero after a maximum was achieved. X-ray photoelectron spectra of Mo3d and Ni2p3/2 levels for the deposits showed that these elements existed in a metallic state before a maximum partial current efficiency of Mo deposition was achieved. When the Mo content became higher than the one at a maximum partial current efficiency of Mo deposition, high valency Mo compounds were also detected. At the limit where the efficiency of Mo deposition decreased to nearly zero, the spectra of the deposits agreed with those of low valency Mo oxides. From these results, the step-wise reduction mechanism of molybdate ion was verified in the induced codeposition of Mo with Ni.
