Properties of binary oxides: a DFT study

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Linnanmaa, hall TA105 (Arina Hall)

Topic of the dissertation

Properties of binary oxides: a DFT study

Doctoral candidate

Master of Science Olga Miroshnichenko

Faculty and unit

University of Oulu Graduate School, Faculty of Science, Nano and Molecular Systems Research Unit

Subject of study

Theoretical Physics

Opponent

Professor Adam Kiejna, University of Wrocław, Poland

Custos

Professor Matti Alatalo, University of Oulu

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Properties of binary oxides have been explored theoretically giving insight into the effect of environment

One particular binary oxide, titanium dioxide or TiO2, is used in an enormous amount of applications across different fields. Due to its refractive properties, relatively large TiO2 particles are used as pigments. TiO2 is used in virtually everything that has a white color. Very small particles are used, for example, in sunscreens and as catalysts. By changing the size, properties of particles are also changing, and they become more sensitive to their structure, size, and environment.

In this dissertation, the effect of SO4 and OH groups on the properties of very small (1-2 nanometers) TiO2 particles was studied by quantum mechanical calculations. These groups are present on the surface during manufacturing. It was found that the abovementioned groups change properties of particles, altering their geometrical structure as well as electronic, which is reflected in their optical properties. These effects should be taken into account in quality control and when comparing computed data with experimental.

The second part of the dissertation is dealing with computed partial charges of atoms in binary oxides and their oxidation states. Partial charges show the distribution of electrons among atoms and they are relatively easy obtained from quantum mechanical electronic structure calculations. Oxidation state is a theoretical concept that identifies how many electrons an atom has gained or lost. It has been debatable whether these two concepts have a correlation. The conducted research shows that connection between them exists by analyzing thousands of records of data for binary oxides from open materials databases. This correlation enables fast oxidation state estimation and therefore accelerates scientific discovery.
Last updated: 5.8.2019