Influence of Heating Temperature in Thermal Oxidation to Prepare Titanium Oxide /Aluminum-doped Zinc Oxide Films for Multi-functional-energy-saving Glass

This study reports the feasibility of thermal oxidation to prepare titanium oxide/aluminum-doped zinc oxide (TiO _x /AZO) films on glass for multi-functional-energy-saving glass: self-cleaning and low emissivity. The titanium/aluminum-doped zinc oxide films were deposited on glass substrates first. Thermal oxidation of on titanium was then carried in a furnace with feeding oxygen gas flow. The heating temperature was set at 300°C, 400°C and 500°C. Structural, optical and hydrophilic properties of the TiO _x /AZO samples were measured. Results indicate heating temperature in thermal oxidation treatment indeed influence the properties of TiO _x /AZO significantly especially for 500°C. Particulate agglomeration on surface of TiO _x /AZO samples increases with heating temperature seen from scanning electron microscope. Zinc substitution with aluminum in zinc oxide is observed from zinc oxide (002) X-ray diffraction peak shifting to high angle when heating temperature increases. The average visible transmittance of TiO _x /AZO samples increases from 41 % to 81 % as heating temperature raising from 300 to 500° C. The contact angle of TiO _x /AZO samples after ultraviolet radiation is 7.17 °, 8.16°, and 31.26° respect heating temperature: 300, 400 and 500°C. High heating temperature like 500°C makes titanium reacts with oxygen and zinc replace with aluminum more complete in TiO _x /AZO films. This makes visible transmittance high and emissivity (corresponding to the value of electrical resistivity) low appropriate for low emissivity glass. The good hydrophilic property also observed from low contact angle of TiO _x /AZO samples reveals the prepared TiO _x /AZO samples can be also acted as self-cleaning glass.