First principles calculation on the interface behavior of LaAlO3/(Ti,Nb)(C,N)

Abstract

The present study investigated the binding energy and the crystal, interfacial, and electronic structural stabilities of LaAlO3(1 1 1)/(Ti,Nb)(C,N)(1 1 1) heterogeneous nucleation interfaces and analyzed the effectiveness of LaAlO3 as the heterogeneous nucleus of (Ti,Nb)(C,N) by the application of a first principles method. The results indicated that the lattice constant and elastic modulus of (Ti0.5,Nb0.5)(C0.5,N0.5), which were calculated using the virtual crystal approximation method, were similar to those of the actual crystal. The bonding mode between the (Ti0.5,Nb0.5)(C0.5,N0.5) (1 1 1)/LaAlO3 (1 1 1) interface was determined to be a combination of covalent, ionic, and metallic bonds, and the interface exhibited strong bonding effects. Furthermore, the LaAlO3 (1 1 1) interface contained two termination interfaces: Al and LaO3. The surface energies of the LaO3 and Al terminations exhibited positive and negative correlations with the Al chemical potential, ΔμAl, respectively. For most values of ΔμAl, the surface energy of the LaO3 termination was lower than that of the Al termination, which indicates that the LaO3 termination surface was more stable than the latter. For the LaAlO3 (1 1 1)/MX (1 1 1) interface with different termination types, the LaO3-X-terminated interface exhibited the largest interfacial binding energy. Interfacial atoms exhibited the greatest bond strengths, specifically the covalent and polar covalent bonds formed at the interface, indicating that the LaO3-terminated interface containing La atoms was more likely to act as the heterogeneous nucleus of (Ti,Nb)(C,N).