Crystallisation of amorphous TiO2 during vacuum annealing studied by X-ray absorption spectroscopy
Kavanagh, Benjamin (2021)
Kavanagh, Benjamin
2021
Bachelor's Programme in Science and Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2021-05-21
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202105104696
https://urn.fi/URN:NBN:fi:tuni-202105104696
Tiivistelmä
X-ray Absorption Spectroscopy (XAS) is an analysis method providing elemental specificity and details of the bonding structure in solid state materials. The performance of TiO2 as a pho- tocatalyst within a photoelectrochemical cell is strongly dependent on its crystal structure. In this work XAS have been used in the analysis of the crystallisation of amorphous TiO2 under vacuum annealing. Firstly the application of TiO2 in photoelectrochemical cells as a photocatalyst material has been presented, followed by an overview of the crystalline phases of TiO2 and their properties. Then the principles of XAS and the experimental set up required to carry out XAS measurements has been discussed. Next is the details of the experimental methods used in this study, including a description of the sample preparation of ALD grown amorphous TiO2. The XAS measurements conducted and the development of a method of data processing to remove overlapping spectral features. Finally the results of the analysis are presented.
The analysis of the XAS data measured revealed that samples at all 3 ALD growth temper- atures crystallised during the annealing process. Using O K-edge reference spectra for rutile and anatase phases led to the identification of the crystallised samples deposited at 100 °C and 150 °C as anatase crystal structure. Furthermore, the temperature at which crystallisation of the amorphous TiO2 occurs has been identified, revealing a trend that an increase in ALD growth temperature results in a decrease in the temperature required for crystallisation to occur.
The analysis of the XAS data measured revealed that samples at all 3 ALD growth temper- atures crystallised during the annealing process. Using O K-edge reference spectra for rutile and anatase phases led to the identification of the crystallised samples deposited at 100 °C and 150 °C as anatase crystal structure. Furthermore, the temperature at which crystallisation of the amorphous TiO2 occurs has been identified, revealing a trend that an increase in ALD growth temperature results in a decrease in the temperature required for crystallisation to occur.
Kokoelmat
- Kandidaatintutkielmat [7083]