Electrodeposition of Co-W Alloys with P and Ni


  • Henrikas CESIULIS∗, Xiaogang XIE, Elizabeth PODLAHA-MURPHY 1Department of Physical Chemistry, Vilnius University


tungsten alloys, phosphorous alloys, electrodeposition, nanowires, nanotubes


The aim of the present study is to explore the electrolyte composition in order to obtain Co-W, Co-Ni-W, Co-P-W, Co-Ni-P-W alloys with smooth morphology, high reaction rate, and underscoring the interactive reduction behavior of the codepositing elements. The recommended electrolyte formulation: 0.2 M MeSO4, 0.4 M Na2WO4, 0.5 M citric acid, and 1.5 M ammonia (“Me” represents the iron group metal); provides an optimal pH buffer capacity in the range of 7.5 to 8.5 at 70 °C. Smooth and crack free films of Co-W, Co-P-W, Co-Ni-W, and Co-Ni-P-W alloys were electrodeposited. Nanowires and nanotubes of the alloys were realized in alumina templates with constant potential and pulsed potential, respectively. The amount of W in the alloys, deposited on a rotating cylinder electrode galvanostatically, decreased with an increase in P incorporation (from 30 at.% to 15 at.% in alloys Co-P-W, and up to 30 at.% to 1.3 at.% in Co-Ni-P-W at the content of P up to 11 at.%) and also with the amount of Ni (from 30 at.% to 14 at.% in Co-Ni-W) . The partial current densities were determined from WDS chemical analyses and weight of the deposits. The Co partial current density was reduced when codeposited with W, and the W partial current density was reduced when P was incorporated into the deposit. The ratio of Ni to Co in the deposited ternary alloys differs from that of the electrolytes, characteristic of the anomalous co-deposition behavior. The anomalous co-deposition of Co with Ni is eliminated when phosphorous is incorporated into the alloys. These interacting reduction observations can be explained by a competing adsorption mechanism. The described baths can be used both for thin film and nanostructures electrodeposition.