New mechanisms for defect engineering in titanium dioxide

defect engineering;titanium dioxide;oxygen interstitials;photo-illumination;surface;electrostatic interaction

Hollister, Alice G.

关键词: defect engineering;    titanium dioxide;    oxygen interstitials;    photo-illumination;    surface;    electrostatic interaction;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/15558/3_Hollister_Alice.pdf?sequence=4&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The technologically useful properties of a solid often depend upon the types and concentrations of crystalline defects it contains. The concentrations of various defects can alter the electrical properties of a solid.Currently, defect engineering is applied extensively within the microelectronic industry but has not been utilized much in catalysis research.However, defects can be useful in altering the effectiveness of catalysts (including photocatalysts), the performance of photo-active devices, the sensitivity of solid-state electrolyte sensors, and the efficiency of devices for converting sunlight to electrical power.TiO2, in particular, is widely used as a catalyst and photocatalyst and is being explored for applications in sensor technology and coatings. This thesis involves identifying new mechanisms for defect engineering in titanium dioxide based on surface-bulk coupling, photo-stimulation, and interaction of charged defects at the surface.While titanium dioxide is utilized as a model, the principles observed for titanium dioxide will translate well into other metal oxide semiconductors.Through isotopic oxygen bulk diffusion studies done in an ultrahigh vacuum chamber, it has been observed that having a surface free from contamination increases the self-diffusion of oxygen in titanium dioxide.Photo-illumination effects were also observed for the defects in titanium dioxide.In addition an 18O pile-up in dopant concentration at the surface is evidence of an interaction between charged defects and the charged surface.Two models have been developed to help understand these mechanisms.