Adhesion behavior and bonding mechanism of W/La₂O₃ interfaces: First-principles calculations

Based on the first-principles calculation, the stability, work of adhesion, and bonding performance of the W (100) (2 x 2)/La2O3 (11 (2) over bar0) and W (111) (root 3 x root 3 )/La2O3 (0001) (2 x 2) interfaces are investigated. The nucleation ability of heterogeneous phases with different terminals of lanthanum oxide in the W matrix is analyzed. The surface energy revealed that the stability of the O-2-terminated surface is higher than the La-terminated surface at high oxidation potential. The stability of the La-terminated surface gradually increases with the decrease of mu(slab)(O). The adhesion work of the W-2/La2O3-O-2 interface is the highest, indicating the strongest bonding strength. The interface energy curves of different structures intersect indicates that the interface structures could coexist at the intersection point. The electronic structure indicates that the charge of the W atoms in the inner layer is transferred to the surface atoms, the W-2/La2O3-O-2 interface is mainly covalent W-O bonds, while the W-1/La2O3-O-2 interface possibly exhibits the mixed covalent and ionic bonds.