Ti-Zr-O nanotube arrays with controlled morphology, crystal structure and optical properties.

A series of Ti-Zr-O nanotube arrays on Ti-Zr alloys with different ratios of Ti to Zr were prepared by a simple anodization process, and their morphologies, crystal structures and optical properties were investigated. It is found that the morphology, length, crystal structure and optical properties of Ti-Zr-O tubes can be well controlled by adjusting the ratio of Ti to Zr in Ti-Zr alloys. The tubes obtained evolved from circa (ca.) 100 nm to 50 nm in diameter, from ca. 2 to 10 microm in length with increasing Zr content in Ti-Zr alloys. As-prepared tubes grown on the alloys with a Zr content of <70 mol% are amorphous, while cubic phase of ZrO2 is predominately formed in the 90 mol% Zr-Ti alloy. The absorption edge of such tubes was found to span from 250 to 370 nm, and their emission band from 400 nm to 750 nm in photoluminescence spectra decays with the decrease of Zr content. In addition, upon calcination of varied Zr content Ti-Zr-O nanotubes, Zr doped anatase TiO2, zirconium titanate and Ti doped ZrO2 in were obtained.