Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 10: Oxides I: Growth and Characterization
O 10.5: Talk
Monday, March 16, 2020, 11:30–11:45, WIL B321
Growth and Characterization of Calcium-Molybdate Thin Films on Mo(001) — Maike Lockhorn1, Sergio Tosoni2, Gianfranco Pacchioni2, and •Niklas Nilius1 — 1Institute of Physics, Carl von Ossietzky University Oldenburg, Germany — 2Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Italy
Ca-Mo mixed oxide films were grown on a Mo(001) surface and characterized by various surface science techniques and DFT. Several highly crystalline phases were observed with rising annealing temperature, before the mixed oxide decays to binary MoOx. The stoichiometry of the low-temperature phase was determined to CaMo3O6, and resembles a CaMo5O8 bulk structure. A corresponding DFT model consists of alternating flat-lying and upright-standing Mo octahedrons, separated by Ca2+ ion rows. As the Ca and O content decreases upon heating, the central Mo units grow in size and the film evolves through distinct (3x3), (4x4) and (6x6) reconstructions. This leads also to an increasing metallicity of the film, as probed with STM conductance spectroscopy. Our work presents an easy approach towards crystalline ternary oxide films that exploits the inter-diffusion of substrate atoms into a suitable binary oxide.