TY  - UNPB
N2  - In this thesis, three di?fferent model metal-oxide semiconductor systems will be discussed.
First, the impact of hydroxyl vacancies, OHvac, on the geometry, electronic
structure, and mechanical properties of single-walled aluminosilicate, (Al2SiO7H4)N,
and aluminogermanate, (Al2GeO7H4)36, nanotubes is investigated. It is found that,
with the exception of one OHvac localised on the outer wall of the (Al2GeO7H4)36 tube,
these defects induce occupied and empty states in the band gap. Those states are found
to be highly localised both in energy and in real space. Different magnetisation states
are also found, depending on both the chemical composition and the specifi?c side with
respect to the tube cavity.
The focus of the thesis then shifts to one of the most important and well-studied metaloxide
surfaces, the rutile TiO2(110) surface. The reactivity of the surface is revisited,
in view of the discrepancy between theory and experiment on the interaction between
molecular oxygen and surface hydroxyls. This discrepancy is resolved by proposing that
excess charge, associated with the oxygen vacancy and originating from Ti interstitials,
is present on the surface. This surface charge opens new reaction channels not theoretically
possible otherwise. The study utilises hybrid Density Functional Theory (DFT)
calculations and Scanning Tunneling Microscopy (STM) simulations to provide evidence
for the proposed surface charging.
The last part of the thesis focuses on another surface of TiO2, the (011) surface.
TiO2(011) has recently attracted attention due owing to its reported high photocatalytic
activity. Several proposed structures of the surface are inconsistent with each
other. Recent developments, based on Surface X-Ray Diffraction (SXRD) data and
DFT simulations, now agree on a new structure. In this part a review of the various
structures is provided and further evidence is given on the validity of the new proposal
by providing further insight on the appearance of the surface on the STM.
ID  - discovery1324515
UR  - https://discovery.ucl.ac.uk/id/eprint/1324515/
PB  - UCL (University College London)
M1  - Doctoral
A1  - Beglitis, N.
TI  - First-principles studies of surface defects of model metal-oxide semiconductors
Y1  - 2011/08/28/
AV  - public
EP  - 167
N1  - Unpublished
ER  -