First-principles calculation of W/WC interface: Atomic structure, stability and electronic properties

The structural, adhesive, and electronic properties of alpha-W(1 1 0)/alpha-WC(0 0 0 1) interfaces are studied by first-principles calculation based on density functional theory (DFT). Six different W/WC interface geometries are considered in this study, including two terminations of WC(0 0 0 1) surface, and each of them involves three different stacking sequences. It is demonstrated that whatever stacking sequence is, the interfacial separations of C-terminated interfaces decrease after optimization, and the lateral movement of the interfacial W atoms will bring three nearest neighbor C atoms around it. Therefore, the C-terminated interfaces are stable geometries, and yield larger adhesion energy, W-ad. Using several analytic techniques including charge density distribution and its difference, and density of states, we characterized the electronic properties and determined the interfacial bonding of W-terminated hollow-site interface to be of metallic nature while the interfacial bonding of C-terminated hollow-site interface to be of a mixed covalent-ionic nature. (C) 2014 Elsevier B.V. All rights reserved.