Metastable Structures of Co and Co-Ag Detected in Electrodeposited Coatings

Silver and cobalt were simultaneously electrodeposited from a perchlorate electrolytic bath containing complexing agents and additives. Rough black Co-Ag deposits were obtained with variable composition determined by the deposition potential. The characterization of these deposits, by both X-ray diffraction and transmission electron microscopy analysis, revealed that electrodeposition in the selected bath induced metastable structures in both Co-Ag and pure-cobalt coatings. In cobalt-silver deposits, a metastable hexagonal close-packed phase (hP2) with cell parameters of a = 2.887 (2) angstrom, c = 4.745 (6) angstrom, and c/a = 1.644 was detected. The Co-Ag coatings exhibited ferromagnetic behavior. In cobalt deposits, a primitive cubic structure (cP20), with a cell parameter of a = 6.093 (1) angstrom, was detected.