Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)A comprehensive study of nonstoichiometry titanium oxide thin films (TiOx, 0.3 <= x <= 2) prepared by ion beam deposition technique is reported. The physical properties of the material are studied by ultraviolet and x-ray photoelectron, Raman, and Fourier transform infrared spectroscopies, and atomic force microscopy. An abrupt transition from metallic characteristics to a wide gap semiconductor is observed in a very narrow range of oxygen variation. Concomitantly with this change the crystal structure and morphology suffer remarkable physical properties modifications. This transformation is ascribed to surface-volume energy minimization due to the influence of oxygen determining the size of the TiO2 particles during coalescence. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3481442]1086Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)ANPCyT [PICT-0633973]CONICET [PIP 2533]UBACyT [X-003]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [05/53926]ANPCyT [PICT-0633973]CONICET [PIP 2533]UBACyT [X-003]