The effect of lanthanum chloride on the electrocrystallization behavior of cobalt and grain refinement in deposition layers

Abstract

This study investigates the effect of different concentrations of lanthanum chloride on the grain refinement of cobalt deposition layers during the electrochemical deposition process in industrial electrolytes. The impact of different lanthanum chloride concentrations on cobalt electrodeposition behavior was analyzed using the Liner sweep voltammetry curve, cyclic voltammetry curve, and chronoamperometry curve. The microstructure morphology and grain size of the deposition layers were analyzed using scanning electron microscopy and atomic force microscopy and the preferred orientation and crystal structure were analyzed using X-ray diffraction. The results show that the addition of different concentrations of lanthanum chloride to the industrial electrolyte leads to a negative shift in the starting deposition potential of cobalt, an increase in cathode polarization degree, an increase in overpotential, a shortened nucleation relaxation time, and an accelerated nucleation rate during cobalt electrodeposition, resulting in grain refinement of the deposition layers. However, the addition of lanthanum chloride does not change the cobalt electrocrystallization mechanism, nor does it alter the crystal structure of the cobalt deposition layers, which remain in a close-packed hexagonal structure. When 0.2-g L⁻¹ lanthanum chloride is added, the grain growth orientation changes from the (11$\bar{\text{2}}$0) plane to the (11$\bar{\text{2}}$0) and (10$\bar{\text{1}}$0) planes, resulting in a uniform distribution of grain size and obvious grain refinement of the deposition layers.

Graphical abstract