Diffusion-Controlled Solid-State Formation of CoSb Phase from Co/Sb-Multilayered Nanowires

The physical properties of materials on a nanometer scale are known to be different from those of bulk form due to dimensional confinement effects and high specific surface-to-volume ratio. In this study, the size effects on the diffusion and reaction at the interface of dissimilar nanowires (NWs) were investigated. Co/Sb-multilayered NWs of15±1and19±2 nm in radius have been grown within anodic aluminum oxide templates using a pulsed potentiodynamic electrodeposition method. XRD and TEM results demonstrated that the multilayered NWs were transformed to a CoSb phase through a solid-state reaction at the temperature in the range of 653 to 693 K. The kinetics of the solid-state reaction was analyzed and found to be diffusion controlled at the interface between Co and Sb phases. The reaction was controlled by the dominant diffusion of Sb atoms. The activation energies for the solid-state reaction were estimated to be 0.9 and 0.7 eV/atom for the multilayered NWs with radii of 15 and 19 nm, respectively.