Field emission properties of TiO2 nanotubes fabricated on Ti wire

The present work reports the field emission (FE) properties of well-aligned TiO2 nanotubes (TNTs) grown on Ti wire. Vertically-oriented, and highly-ordered TNTs with high aspect ratio are synthesized on Ti wire by electrochemical anodization in ethylene glycol (EG) electrolyte containing a small amount of ammonium fluoride (NH4F) and de-ionized (DI) water. The as-anodized TNTs have been characterized using FESEM, HRTEM, EDAX, XRD, and XPS. FESEM study shows that the average diameter of the nanotubes is similar to 90 nm and the wall thickness is similar to 25 nm. GAXRD and HRTEM analyses indicate that the as-anodized TNTs are amorphous. EDX analysis confirms that TNTs are composed of Ti and 0 along with considerable amount of F. XPS results reveal the oxide state of TiO2. FE studies of the nanotubes showed that the turn-on field is 6 V/mu m with corresponding emission current density of similar to 10 mu A/cm(2) and field enhancement factor (beta) of similar to 1000. The emission current increases exponentially with increase in applied field and reaches to the maximum value of similar to 150 gm at 15 V/mu m. The FE properties of TNTs on Ti wire show their potential applications in the future display devices as a point electron source with small optical size. It can also be a good candidate for the fabrication of miniature X-rays tubes for industrial and medical applications.