We investigated the effects of pyrophosphate ions on tin-nickel alloy deposition from pyrophosphate-glycine complex baths. The potential - current density curves for the alloy deposition were measured using a rotating-disk electrode system and the cathodic current for each metal deposition was evaluated quantitatively based on the polarization curves. Pyrophosphate ions promoted the dissolution of both tin ions and nickel ions in the alloy baths. Addition of pyrophosphate ions, however, polarized the reduction potential for metal deposition in the baths containing either tin ions or nickel ions. On the other hand, the inhibition effect caused by addition of pyrophosphate ions was weakened greatly in the tin-nickel alloy deposition from the baths having mixed ligand complexes consisted of pyrophosphate ions and glycine, which might indicate that tin ions facilitated nickel deposition and nickel ions also did tin deposition.
Crystallization behavior of electrodeposited Pd-Ni-P metallic glass films in the supercooled liquid region was investigated. The Pd40Ni40P20, which has the highest glass formability, and other metallic glass Pd44Ni39P17 and Pd41Ni42P17 were prepared. The crystallization temperature (Tx) of Pd44Ni39P17 and Pd41Ni42P17 were lower than that of Pd40Ni40P20 by differential scanning calorimetry (DSC) analysis. X-ray diffractometry (XRD) patterns show that all samples were crystallized after isothermal annealing below Tx. The Pd5P2 and Ni3P were observed using XRD analysis after annealing of Pd40Ni40P20 and Pd44Ni39P17 at 603 K for 60 min and 30 min, respectively. Furthermore, in Pd44Ni39P17, the Pd2Ni2P was observed after annealing at 603 K for 120 min.
Important factors for fabricating thinner and more uniform films by electroless Ni-B plating using dimethylamine borane (DMAB) as the reducing agent were discussed. The number density of initial deposits was pointed out as the important factor for fabrication of thinner and more uniform films. Transmission electron microscope observations were performed for initial deposits plated from baths of different pH. The number density was lower in deposits plated from pH 9-10 than in those plated from pH 6-8. Dimethylamine produced through an oxidation reaction of a reducing agent (DMAB) prevents the initial deposition. Such a lower number density appeared in pH 9-10. Nickel citrate - ammonia complex was formed under ammoniacal conditions. The nickel citrate - ammonia complex contributed to the increase in the number density of grains. It was possible to eliminate deposition prevention through the appropriate selection of nickel complexes. Results show that the initial deposition with higher number density of grains was achieved at all pH of Ni-B plating baths.
Pyranine (trisodium 8-hydroxypyrene-1,3,6-trisulfonate) molecules were embedded in anodic porous alumina at varying pH. The UV-Vis absorption spectra of pyranine embedded in anodic porous alumina showed a peak at around 405 nm that was attributable to the protonated form of pyranine (PyOH). The amount of adsorbed pyranine, which was dependent on the aqueous dye solution pH, reached a maximum at around pH 5, indicating that the adsorption of pyranine results from electrostatic interaction between the anodic porous alumina positive surface charges and negative pyranine sulfonate groups. The fluorescence spectra had a peak at around 510 nm that was attributable to the deprotonated form of pyranine (PyO－), suggesting that the anodic porous alumina provides a water-rich environment. Before sealing, the fluorescence intensity of the material decreased during continuous excitation. However, the fluorescence remained more or less constant after sealing. These results indicate that sealing decreases the photochemical decomposition of pyranine with oxygen molecules because oxygen molecule diffusion can be suppressed.