Understanding Interface Stability in RENi2/Ni through First-Principles Calculations

Abstract

Crystallographic orientation analysis revealed that DyNi2 grew epitaxially on Ni, whereas NdNi2 does not. To elucidate the microscopic origin of this contrasting behavior, we constructed atomistic models of Ni/Rare-earth (RE)Ni2 interfaces with well-defined crystallographic alignment and performed first-principles calculations based on density functional theory (DFT). The computed interfacial energies exhibit a clear correlation with lattice mismatch: larger mismatch leads to higher interfacial energy and reduced interface stability. Consequently, Ni/DyNi2 exhibits a significantly lower interfacial energy than Ni/NdNi2, consistent with experimental observations. A comparison between interfacial and strain energies for Ni/RENi2 (RE = Sc, Y, Nd, Gd, Dy, and Lu) reveals that the elemental dependence of interfacial stability is dominated by elastic strain rather than chemical bonding. Based on this insight, we developed a simple regression model using the absolute lattice mismatch as a descriptor, enabling qualitative predictions of stability for Ni/RENi2 interfaces with RE other than those examined in DFT.