Lithium-molybdate nanostructures grown on the Mo(001) surface

Ordered LiMo mixed-oxide films of different compositions have been grown on a Mo(001) surface and analysed by means of scanning tunnelling microscopy, low-energy-electron-diffraction and cathodoluminescence spectroscopy. Starting from a disordered LixO ad-layer grown at room temperature, a scheelite-type Li2MoO4 phase develops on the Mo surface after annealing to 700 K. The building blocks of this structure are regular nanorods of approximately 30 nm length, which exhibit strong light emission in the green spectral range upon electron injection. Further annealing induces a restructuring of the film that evolves into various mixed-oxide phases of decreasing Li content. The Li fully desorbs from the surface above 1000 K, leaving behind a nano-crystalline Mo-oxide. Our approach demonstrates that ternary LiMo oxides of high structural quality can be grown as thin films, making them accessible to conventional surface science techniques without charging problems.