Formation of titanium monoxide (001) single-crystalline thin film induced by ion bombardment of titanium dioxide (110)

© 2015 Macmillan Publishers Limited. Financial support from the Spanish Ministry of Economy and Competitiveness under projects MAT2012-38045-C04-03 and MAT2012-38045-C04-04 is acknowledged. A.M. also acknowledges project MAT2010-21156-C03-02 for financial support. We thank A. Tejeda for critical discussions. We acknowledge the Spanish Ministry of Economy and Competitiveness and Consejo Superior de Investigaciones Científicas for both financial support under project PIE 201060E013 and provision of synchrotron radiation facilities. We would also like to thank the SpLine beamline staff for their assistance during the SR experiments. GSS and the microscopy effort were supported by the ERC starting Investigator Award, grant #239739 STEMOX. Electron microscopy observations were carried out at the Centro Nacional de Microscopía Electrónica, CNME-UCM. Part of the XRD measurements were performed at the C.A.I. de Difracción de Rayos X-UCM. Computational calculations were performed at the Supercomputing Centre of Galicia (CESGA). Author contributions: O.R.d.l.F. conceived the project and coordinated the research. B.M., I.P. and O.R.d.l.F. prepared the samples and performed the Auger and LEED measurements and the ion beam modifications. B.M., I.P., A.M., J.L.-S, O.R.d.l.F., J.R.-Z., P.F. and G.C. performed the X ray diffraction measurements. G.S.-S. and M.V. performed the STEM measurements. J.I.B. and M.C.M. carried out the Density Functional Theory calculations. All authors wrote and revised the manuscript and extensively discussed the results and their interpretation. Supplementary Information: accompanies this paper at http://www.nature.com/ naturecommunications.
A plethora of technological applications justify why titanium dioxide is probably the most studied oxide, and an optimal exploitation of its properties quite frequently requires a controlled modification of the surface. Low-energy ion bombardment is one of the most extended techniques for this purpose and has been recently used in titanium oxides, among other applications, to favour resistive switching mechanisms or to form transparent conductive layers. Surfaces modified in this way are frequently described as reduced and defective, with a high density of oxygen vacancies. Here we show, at variance with this view, that high ion doses on rutile titanium dioxide (110) induce its transformation into a nanometric and single-crystalline titanium monoxide (001) thin film with rocksalt structure. The discovery of this ability may pave the way to new technical applications of ion bombardment not previously reported, which can be used to fabricate heterostructures and interfaces.
Unión Europea. FP7
Ministerio de Economía y Competitividad (MINECO), España
Consejo Superior de Investigaciones Científicas (CSIC), España
ERC starting Investigator Awards
European Research Council (ERC)
Depto. de Estructura de la Materia, Física Térmica y Electrónica
Fac. de Ciencias Físicas
TRUE
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