Electrodeposition of Pt1-XMx (M=Ni,Co) Alloys for Magnetic Thermometry

Electrodeposited Pt 1-x M x (M=Ni,Co) alloys were studied for possible use in a magnetic thermometry application. The effects of boric acid and potential on the deposition process and on magnetic properties of the resulting films were examined. Both alloy series showed a monotonic decrease in platinum content as the potential was stepped to progressively more reducing potentials. While films in the Pt 1-x Ni x series were all face centered cubic (fcc), those in the Pt 1-x Co x series showed a transition from fcc to hexagonal close packed as the films became more cobalt rich. For the Pt 1-x Ni x system, the presence of B(OH) 3 during deposition was accompanied by decreased Coulombic efficiency at more reducing deposition potentials, increased oxygen incorporation, and decreased magnetization relative to films deposited in the absence of boric acid.[1] For the Pt 1-x Co x system, the presence of B(OH) 3 also resulted in lower Coulombic efficiency and in lower magnetizations over an intermediary potential range. In contrast to the Pt 1-x Ni x , the decreased Coulombic efficiency for the Pt 1-x Co x system was also accompanied by a strong suppression of the deposition process. For both series, the Curie temperature decreased with increasing platinum content, allowing the magnetic thermosensitivity to be optimized for a particular temperature range of interest by appropriate selection of the deposition potential.