Phonons, Defects and the Thermal Conductivity of ZnO

Research output: ThesisDoctoral Thesis

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ZnO is an important semiconductor with a wide range of applications. The high thermal stability, corrosion resistance, non-toxicity and abundance, coupled with excellent charge carrier transport, make it an attractive candidate for thermoelectric applications, particularly in reducing wasted heat energy in high temperatures processes. A combination of first-principles calculations using Density Functional Theory, large-facility neutron scattering experiments and in situ characterisation experiments were used to investigate the lattice dynamics, intrinsic defect structures and thermoelectric properties of ZnO. Calculated phonon modes are in excellent agreement with those directly measured using inelastic scattering. Powder inelastic neutron scattering measurements of bulk and nano-structured ZnO reveal the presence of anharmonic, multi-phonon scattering processes. A novel model for fitting this multi-phonon density of states is presented which relies only on the size of the nanocrystals. The calculated thermal conductivity is in excellent agreement with experimental data. Finally, the intrinsic defect structure was found to be 5% oxygen vacancies with hydrogen interstitials.
Original languageEnglish
Awarding Institution
  • Royal Holloway, University of London
  • Goff, Jon, Supervisor
  • Potter, Robert, Supervisor, External person
Thesis sponsors
Award date1 Mar 2020
Publication statusUnpublished - 2019

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