Heterogeneous Nucleation Interface Between LaAlO3 and Niobium Carbide: First-principles Calculation

This paper aimed to investigate the interface relationship between LaAlO3 and niobium carbide and possibility of LaAlO3 as heterogeneous nucleus to refine niobium carbide by first principles method. Niobium carbide (NbC) is a transition metal carbide with high hardness. Primarily, the lattice mismatch relationship of LaAlO3/NbC was calculated. Then, the interface models were established for the calculation of adhesive work and interface energy of LaAlO3/NbC. Finally, the interfacial bonding types were analyzed with charge density, electron localized function (ELF) and partial density of states (PDOS). The results indicate that the interface mismatch between LaAlO3(0 0 1) plane and NbC(1 1 1) plane is the smallest (8.4%), which indicates that LaAlO3 can be as a moderately heterogeneous nucleus of NbC. Four interfacial models of LaAlO3(1 1 0)/NbC(1 1 1) interface were established, which are named as LaAlO-NbT interface, LaAlO-CT interface, OT-NbT interface and OT-CT interface. The adhesive work of the OT-NbT interface is the largest (0.60 J/m2) and its interface energy is the smallest (4.02 J/m2), which indicates that the binding adhesive ability of the OT-NbT interface is the strongest. The bonding types of the OT-NbT interface are the combination of metallic, ionic and covalent bonds. Therefore, LaAlO3 can act as the heterogeneous nucleus of NbC and refine it.