Synthesis of the Titanium Oxides Using a New Microwave Discharge Method

This research highlights the different behaviors of titanium (Ti) wires under the action of 500 W and 800 W microwave power levels. Following the interaction between microwaves and a titanium wire placed in the node of the (TM₀₁₁-transverse magnetic mode) waveguide in air at atmospheric pressure, plasma was generated. Using optical emission spectroscopy technique it was observed that during plasma generation at 500 W and 800 W microwaves powers, metallic ions, and gas ions were created, and the plasmas fulfilled the local thermodynamic equilibrium (LTE) conditions. The XRD analysis showed that on the surface of the Ti wire exposed to 500 W microwave power a mixture of titanium dioxide (TiO₂) and titanium oxide (TiO) grew, while the Ti wire exposed to 800 W microwave power was completely vaporized and a mixture of TiO₂ and TiO nanoparticles was synthesized. The SEM analysis showed that the dimensions of the titanium oxide (TiO_x) nanoparticles generated by both microwave discharges ranged from 5 nm to 200 nm. The results of EDS analysis showed that the power of microwaves plays an important role in quantitative conversion from Ti wire into a TiO_x mixture. The TEM analysis indicates that most of the nanoparticles are either amorphous or nanocrystalline. Using this simple and inexpensive technique one can grow a TiO_x layer on the surface of titanium electrodes or can synthetize nanocrystalline TiO_x particles.