| Summary: | 碩士 === 國立臺北科技大學 === 製造科技研究所 === 96 === By a modified plasma arc gas condensation technique, in this study we synthesized evaporated the tungsten target and titanium dioxide nanoparticles into tungsten oxide nanostructures and titanium oxide nanostructures with different phases. The influence on preparing tungsten oxide nanostructures with different Plasma gas（argon or argon+10%hydrogen）and chamber pressures(200~760Torr) will also be considered. It can be shown that the size of nanoparticles increases with the increment of chamber pressures. And the corresponding phases of tungsten oxide and titanium oxide are W24O68 and Ti2O3 when argon is used for Plasma gas; when argon+10% hydrogen is used, the phases are W3O and TiO2. Under the first setting, The optical absorption appears as wavelength of tungsten oxide - titanium oxide nanoparticles is approximately less than 326 nm. For the second setting, using argon+10%hydrogen, it will appear as wavelength is less than 367 nm.
Some further consequences are also obtained under the second setting. First, from the aspect of thermal stability, the phase tungsten oxide - titanium oxide nanoparticles won’t be changed as long as the temperature is below 300℃ and chamber pressures is under 200 Torr and 760 Torr. However, when the temperature is up to 600℃, the phase starts changing.
Second, from the aspect of gas sensing, due to energy, nanoparticles is not able to get out of NO2 gas completely when the temperature is around 150℃. Not Until the temperature is increased to 200℃ will nanoparticles accumulate enough energy to get out of NO2 gas. This accomplishes the application of gas sensing.
Via using argon for Plasma gas, tungsten oxide - titanium oxide nanoparticles also has gas sensing for NO2 (3 ppm) when the temperature is below 200℃ and chamber pressures is under 200 Torr. But as the temperature increases up to 250℃, nanoparticles will be poisoned by NO2. Then the ability of gas sensing might be affected.
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