Significantly enhanced structural and thermal stability of anodized anatase nanotube arrays induced by tensile strain

Anatase nanotube arrays were grown by anodization with high crystallinity and a well ordered nanotubular structure. Nanotubes were stable to 800 °C, and this enhanced thermal stability of anatase nanotube arrays (without Ti support) was related to the induced tensile strain/stress inside the nanotube wall. The anatase-to-rutile phase transformation of titania nanotube arrays induces a tensile stress inside the nanotube wall that increases the critical nucleation size of rutile phase, as opposed to a compressive stress usually occurred on the surface of titania thin films or nanoparticles.

► A simple and efficient method to obtain well organized anatase nanotube arrays is reported.
► The anatase-to-rutile phase transformation of titania nanotube arrays without Ti support induces a tensile stress inside the nanotube wall, increasing the critical nucleation size of rutile phase.
► A model is proposed to explain the stress-induced anatase–rutile phase transformation inside nanostructured titania materials.