HRTEM, EELS and Ab-initio Calculation in Atomic and Electronic Structures of Pd/ZnO Polar Interfaces
Abstract: The detailed atomic and electronic structures of the interfaces between ZnO precipitate and palladium were examined employing high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS), and ab-initio calculation. It was indicated that (1–11)Pd//{0002}ZnO polar planes tend to be parallel to the interface. A ZnO precipitate was terminated by oxygen on (000-2) surface at one end of the precipitate and by zinc on (0002) surface at the other end of the precipitate. The presence of both zinc- and oxygen-terminated interfaces was also indicated by the EEL spectra acquired from both the interfaces. At the oxygen-terminated interface, a shoulder was detected in O-K energy-loss near-edge structure (ELNES) below the first peak in the O-K ELNES. From the ab-initio calculation, it was suggested that the origin of the shoulder could be attributed to the strong chemical bonding and hybridization of Pd-d and O-p orbital at the oxygen-terminated polar interface.
Key words: polar interface, terminated-atom, interfacial bonding state, electron density-of-state, electron energy-loss near-edge structure