First Principles Study of CoSb3/Ni Interface Structure and Mechanical Properties

Mechanical stability is critically essential in the design of thermoelectric devices. In this study, we employed first-principles calculations based on density functional theory to investigate the failure mechanisms at the CoSb3/Ni interface. Our findings reveal that the CoSb3(100)/Ni(100) and CoSb3(100)/Ni(111)_1 configurations are favorable interface structures. The ideal tensile strength of the CoSb3/Ni interface is markedly lower than that of bulk CoSb3, which can be attributed to structural rearrangements near the interface that weaken the strength of the Co-Sb bonds. Interface failure occurs in CoSb3, where covalent Sb-Sb bonds exhibit a tendency to soften prior to the ionic Co-Sb bonds due to their comparatively lower rigidity. Consequently, the breakage of the Co-Sb bonds leads to interface failure. Structural failure at both single-layer Sb_CoSb3(100)/Ni(100) and single-layer Sb_CoSb3(100)/Ni(111)_1 interfaces results from ruptures in intermediate Co-Sb bonds in CoSb3, whereas failures at double-layer Sb_CoSb3(100)/Ni(100) and double-layer Sb_CoSb3(100)/Ni(111)_1 interfaces stem from fractures in the uppermost Co-Sb bonds. This behavior is primarily driven by atomic rearrangements near the single-layer Sb_CoSb3 interface, which promote bond formation between Sb-Ni and Co-Ni, thereby enhancing stability within the superstructure of CoSb3. This study will provide a theoretical basis for the interface design of thermoelectric devices.