Effect of energy deposition on TiO2 nanosized powder synthesized by pulsed wire discharge

Titanium dioxide (TiO2) nanosized powder was synthesized by pulsed wire discharge (PWD) using Ti wire in O2 gas. The pressure of O2 gas (P) and relative energy (K), which is defined as the ratio of the charged energy of the capacitor to the vaporization energy in the wire, were varied from 10 to 100 kPa and 4.3–51.9, respectively. The density of the plasma/vapor (Dexp), determined by the maximum volume, was decreased with decreasing P and increasing K as observed by high-speed photography during PWD. X-ray diffraction analysis confirmed that the rutile content (CR) was increased from 7 to 84 vol% with decreasing Dexp. The median diameter (D50), determined from scanning electron microscopy, was decreased from 36.5 to 10 nm with decreasing Dexp. Therefore, an increase in CR and decrease in D50 both accompany the decrease in Dexp.