Morphology, structure and magnetic properties of cobalt-nickel films obtained from acidic electrolytes containing glycine

This paper focuses on the development and optimization of electroplated cobalt-nickel (CoNi) alloys for use in biomedical microdevices. CoNi films were electrodeposited from glycine-containing electrolyte solutions at acidic pH. The influence of pH (2.5-5), temperature (55 and 80 °C), current density (from -5 to -40 mA cm-2), glycine concentration (0.5 and 1 mol dm -3) and the nature of the metal salts (chlorides or sulphates) on the composition and the magnetic properties of the films were systematically analyzed. The cobalt content varied between 50 and 83 wt% depending on the applied conditions. As a result, deposits showed variable morphologies, different structures (either hexagonal close-packed (hcp) or mixed hcp and face-centered cubic phases) and tunable magnetic properties, ranging from semi-hard (18.51 kA m-1, i.e. 233 Oe) to very soft (1.43 kA m -1, i.e. 18 Oe). To understand the role of glycine in this system, a comparison of the electrochemical processes, and the structural and magnetic properties is made for samples produced in glycine-containing and glycine-free baths. © 2010 Elsevier Ltd. All rights reserved.