Concentration-dependent regulation of Cu/diamond interfacial bonding by transition metal doping: A first-principles study

Cu/diamond composites face significant challenges due to poor interfacial bonding, which transition metal doping can mitigate. However, the critical role of dopant concentration remains poorly understood. In this study, first-principles calculations are employed to systematically investigate how Cr, Mo, and W doping concentrations (12.5–62.5 at. %) influence the interfacial properties of Cu(111)/diamond(111). The work of adhesion reveals a notable concentration-dependent trend: at lower concentrations (<31.2 at. %), interfacial strength follows W > Mo > Cr, while this order reverses at higher concentrations, where Cr performs optimally. Comprehensive electronic structure analyses, including Bader charge, charge density difference, and partial density of states, elucidate the underlying electronic origins. The superior low-concentration performance of W is attributed to the spatial extensibility of its 5d orbitals, whereas Cr's advantage at high concentrations stems from favorable energy level alignment and highly localized 3d-2p hybridization. These findings establish a quantitative relationship between doping concentration and interfacial adhesion, providing crucial theoretical guidance for optimizing the interfacial design of high-performance Cu/diamond thermal management materials.