Ultra-small Cd@NiAg and Cr@NiAg nano-clusters with enhanced mixing

Structural, mixing vs segregation, and electronic properties of Cd-doped and Cr-doped ultrasmall NiAg nanoclusters have been analyzed here using first principles density functional theory based electronic structure calculations. The optimized structures of the doped clusters assume a core-shell-like structural pattern, similar to that of the undoped NiAg clusters. Both the dopings induce an enhanced mixing trend keeping intact the core-shell structural pattern of the host NiAg nanoclusters. Between the two types of dopings, the Cr-doping appears more effective for providing enhanced mixing of the NiAg clusters. Enhanced orbital hybridization for the doped NiAg clusters plays an important role in increasing the mixing trend. In the present work, we use a new formulation of mixing energy for such ternary nanoclusters to assess the merit of the doped binary NiAg nanoclusters compared to a similar doping in the associated monometallic nanoclusters of same size. This analysis indicates that the Cd-doping indeed is efficient for enhancing the mixing of the NiAg nanoclusters, while the Cr-doping would be more favorable for the monometallic Ni-cluster compared to the binary NiAg nanocluster of similar size.