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

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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.
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© 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.
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1. Facsko, S. et al. Formation of ordered nanoscale semiconductor dots by ion sputtering. Science 285, 1551–1553 (1999). 2. Valbusa, U., Boragno, C. & de Mongeot, F. B. Nanostructuring surfaces by ion sputtering. J. Phys.: Condens. Matter 14, 8153–8175 (2002). 3. Rodríguez de la Fuente, O. et al. Surface defects and their influence on surface properties. J. Phys.: Condens. Matter 25, 484008 (2013). 4. Diebold, U. The surface science of titanium dioxide. Surf. Sci. Rep. 48, 53–229 (2003). 5. Luttrell, T., Li, W. K., Gong, X. Q. & Batzill, M. New directions for atomic steps: step alignment by grazing incident ion beams on TiO2(110). Phys. Rev. Lett. 102, 166103 (2009). 6. Karmakar, P., Liu, G. F. & Yarmoff, J. A. Sputtering-induced vacancy cluster formation on TiO2(110). Phys. Rev. B 76, 193410 (2007). 7. Gross, H. & Oh, S. Efficient resistive memory effect on SrTiO3 by ionic-bombardment. Appl. Phys. Lett. 99, 092105 (2011). 8. Rogala, M., Klusek, Z., Rodenbücher, C., Waser, R. & Szot, K. Quasi-two-dimensional conducting layer on TiO2(110) introduced by sputtering as a template for resistive switching. Appl. Phys. Lett. 102, 131604 (2013). 9. Reagor, D. W. & Butko, V. Y. Highly conductive nanolayers on strontium titanate produced by preferential ion-beam etching. Nat. Mater. 4, 593–596 (2005). 10. Singh, A. et al. Transforming insulating rutile single crystal into a fully ordered nanometer-thick transparent semiconductor. Nanotechnology 21, 415303 (2010). 11. Kan, D. et al. Blue-light emission at room temperature from Ar+-irradiated SrTiO3. Nat. Mater. 4, 816–819 (2005). 12. Bruno, F. Y. et al. Anisotropic magnetotransport in SrTiO3 surface electron gases generated by Ar+ irradiation. Phys. Rev. B 83, 245120 (2011). 13. Sánchez-Santolino, G. et al. Characterization of surface metallic states in SrTiO3 by means of aberration corrected electron microscopy. Ultramicroscopy 127, 109–113 (2013). 14. Verrelli, E., Tsoukalas, D., Normand, P., Kean, A. H. & Boukos, N. Forming-free resistive switching memories based on titanium-oxide nanoparticles fabricated at room temperature. Appl. Phys. Lett. 102, 022909 (2013). 15. Carrasco, E., Rodríguez de la Fuente, O., González, M. A. & Rojo, J. M. Characterising and controlling surface defects. Eur. Phys. J. B 40, 421–426 (2004). 16. Palacio, I., Rojo, J. M. & Rodríguez de la Fuente, O. Surface defects activating new reaction paths: formation of formate during methanol oxidation on Ru(0001). Chem. Phys. Chem. 13, 2354–2360 (2012). 17. Behrisch R. (ed.). in Topics in Applied Physics. vol. 47, Sputtering by Particle Bombardment I Springer (1981). 18. Malherbe, J. B., Hofmann, S. & Sanz, J. M. Preferential sputtering of oxides: A comparison of model predictions with experimental data. Appl. Surf. Sci. 27, 355 (1986). 19. Choudhury, T., Saied, S. O., Sullivan, J. L. & Abbot, A. M. Reduction of oxides of iron, cobalt, titanium and niobium by low-energy ion bombardment. J. Phys. D 22, 1185–1195 (1989). 20. Caballero, A., Espinós, J. P., Fernández, A., Leinen, D. & González-Elipe, A. R. Surface modification of oxide materials subjected to low energy ion bombardment: a XAS study. Nucl. Instr. Meth. B 97, 397–401 (1995). 21. Mayer, J. T., Diebold, U., Madey, T. E. & Garfunkel, E. J. Titanium and reduced titania overlayers on titanium dioxide(110). Electr. Spec. Rel. Phen. 73, 1–11 (1995). 22. Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758 (1999). 23. Beltrán, J. I. & Muñoz, M. C. Ab initio study of decohesion properties in oxide/metal systems. Phys. Rev. B 78, 245417 (2008). 24. Pennycook, S. J. et al. Misfit accommodation in oxide thin film heterostructures. Acta Mater. 61, 2725–2733 (2013). 25. Hirth, J. P. & Lothe, J. Theory of Dislocations McGraw-Hill (1968). 26. Ziegler, J. F. The Stopping and Range of Ions in Matter SRIM Co. (2008) www.srim.org. 27. Henderson, M. A. A surface perspective on self-diffusion in rutile TiO2. Surf. Sci. 419, 174–187 (1999). 28. Jug, K., Nair, N. N. & Bredow, T. Molecular dynamics investigation of oxygen vacancy diffusion in rutile. Phys. Chem. Chem. Phys. 7, 2616–2621 (2005). 29. Kresse, G. & Hafner, J. Ab initio molecular dynamics for liquid metals. Phys. Rev. B 47, 558 (1993). 30. Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169 (1996). 31. Glassford, K. M. & Chelikowsky, J. R. Structural and electronic properties of titanium dioxide. Phys. Rev. B 46, 1284 (1992). 32. Landmann, M., Rauls, E. & Schmidt, W. G. The electronic structure and optical response of rutile, anatase and brookite TiO2. J. Phys. Condens. Matter 24, 195503 (2012). 33. Leung, C., Weinert, M., Allen, P. & Wentzcovitch, R. First-principles study of titanium oxides. Phys. Rev. B 54, 7857 (1996).
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