Crumpton, Galen David ORCID: https://orcid.org/0000-0001-9725-8486 (2023) A Density Functional Theory Study of Copper-Doped Nickel Oxide Supercells. MSc by research thesis, University of York.
Abstract
Understanding the effects of defects on the properties of transition metal oxides is of great
importance to the chemical, biological and sustainability industries. Nickel oxide is one
such material that is widely used in various forms, and continues to be studied; most notably
with vacancies and dopants both being introduced into the material through experiment. The
electronic properties of bulk NiO have been calculated using the RSCAN and PBE XC-functionals,
with particular focus on spectral and optical properties.
Additionally, 108-atom supercells have been constructed, with intrinsic and extrinsic defects
being placed in the supercell. The copper-doped supercell has been studied for various copper
atom positions and concentrations. The doping site type altered the electronic properties in
different ways, with clear n-type behaviour being exhibited by substitution on oxygen sites and
interstitial doping. This increased n-type behaviour and narrowing of the band gap suggests that
careful engineering of the chemical environment to favour forming these defects will produce a
material with higher conductivity and charge transfer rates, which is essential for photocathode
applications.
By varying the distance between dopant Cu atoms, it was found that it is energetically
favourable for the Cu atoms to be closer together than further apart, with an energy difference
of approximately 70 meV. Additionally, the preferential alignment of multiple Cu atom dopants
was found to be along the same [111] plane.
An exploratory study into the different stable compounds containing Ni, Cu and O has been
carried out, with a 2D ternary convex hull being plotted to investigate these compounds’ stability.
There is only one predicted stable compound containing all three species, the rhombohedral
structure Ni9CuO10.
Metadata
Supervisors: | Hasnip, Phil and Lazarov, Vlado |
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Keywords: | density functional theory, DFT, nickel oxide, copper, copper doping, doping, supercells, RSCAN, meta-GGA, spectral, optical, simulation, convex hull, LBFGS, EELS, core-hole EELS, photocathodes |
Awarding institution: | University of York |
Academic Units: | The University of York > School of Physics, Engineering and Technology (York) |
Depositing User: | Mr Galen David Crumpton |
Date Deposited: | 03 May 2024 14:37 |
Last Modified: | 03 May 2024 14:37 |
Open Archives Initiative ID (OAI ID): | oai:etheses.whiterose.ac.uk:34836 |
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