Formation of TiO2 nanorods by ion irradiation.

Ion beam irradiation is a powerful method to fabricate and tailor the nanostructured surface of materials. Nanorods on the surface of single crystal rutile TiO₂ were formed by N⁺ ion irradiation. The dependence of nanorod morphology on ion fluence and energy was elaborated. With increasing ion fluence, nanopores grow in one direction perpendicular to the surface and burst finally to form nanorods. The length of nanorods increases with increasing ion energy under same fluence. The development of the nanorod structure is originated from the formation of the nanopores while N₂ bubbles and aggregation of vacancies were responsible for the formation of nanopores and nanorods. Combining C⁺ ion irradiation and post-irradiation annealing experiments, two qualitative models are proposed to explain the formation mechanism of these nanorods. [ABSTRACT FROM AUTHOR]