Interface structure of Ag (111)/SnO₂ (200) composite material studied by density functional theory

Electric contact material of Ag/SnO₂ was successfully synthesized by in situ process method. The interface structure was characterized by high-resolution transmission electron microscopy (HTEM) and simulated at atomic scale on computer. The mean-square displacements of atoms near the interface were calculated, and the results showed that near the interface both Ag side and SnO₂ were mismatched and this effect decays rapidly far from the interface. By inspecting the calculated density of states (DOS), we found that the electric-conductivity of this composite material was decreased because of the localized 4d and 2p electrons of Ag and O near the Fermi surface, respectively. Electron density changed acutely across the interface, so that there was no extra compound precipitated. A micro-electric field also formed in the whole material due to the interface structure, and this may affect the electron conduction and the related electric-conductivity of the composite. It is found that the interface cohesive energy of Ag (111)/SnO₂ (200) was -3.50 J/m², which is higher than the experimental results.