Investigation on WC/LaAlO3 heterogeneous nucleation interface by first-principles

In this work, the adhesion energy, interfacial energy, electronic structure and bonding of WC/LaAlO3 interface were investigated by first-principles method. Meanwhile, the stable interface structure for LaAlO3 as the heterogeneous nucleus of WC was also analyzed. The results show that LaAlO3 (111) slab and WC (0001) slab can reach bulk-like characteristics when the atomic layers N ≥ 9 and N ≥ 7, respectively. For LaAlO3 (111) surface, in the whole range of ΔμAl, the LaO3-terminated structure is more stable than the Al-terminated one. For WC (0001) surface, the W-terminated structure is more stable than the C-terminated one. For the four LaAlO3/WC interfaces, the LaO3-W-terminated interface exhibits the largest Wad, which is 2.42 J/m2. The LaO3-C-terminated interface follows, which is 1.26 J/m2. Both of them are larger than those of the Al-terminated interfaces. In the whole range of ΔμAl and ΔμC, the interfacial energy of the four LaAlO3/WC interfaces exhibits the following sequence: LaO3-W interface < LaO3-C interface < Al-W interface < Al-C interface. Especially, the interfacial energy of LaO3-W-terminated interface is much lower than the other ones, which suggests the much higher stability of the LaO3-W-terminated interface. Compared to other LaAlO3/WC interfaces, LaAlO3 is more likely to be the heterogeneous nucleus of WC. The bonding of the LaO3-W-terminated interface is a combination of polar covalent bond and metallic bond, and that of the LaO3-C-terminated interface is covalent and ionic. Both of them exhibit stronger binding strength than the Al-terminated interfaces.