Imaging insulating oxides by elevated-temperature STM

By using elevated-temperature scanning tunnelling microscopy (STM) we have imaged the UO2(111), UO2(110), and NiO(001) surfaces, and have obtained atomic resolution data that are comparable in quality with images of other oxides that can be imaged at room temperature. Electronic structure modelling is used to interpret the STM images. On the UO2(111) surface we image the U sites in empty states, and it is also possible to observe interstitial oxygen on this surface that packs into a (√(3) x √(3))R30 oxygen overlayer. The UO2(110) surface has been imaged at atomic resolution and displays a row structure commensurate with the (1 x 1) bulk termination. On NiO(001), Ni and O sites are imaged in empty and filled states, respectively, which is demonstrated by comparing the lattices around characteristic defect sites. (orig.)