About the Project
Location: Streatham Campus, University of Exeter, EX4 4QJ
Academic Supervisors:
Prof Yanqiu Zhu, University of Exeter
Prof Euan Hendry, university of Exeter
Project description:
When geometry and composition changes in nanomaterials, extremely unusual behaviour occurs. We have preliminarily verified this behaviour, for the first time, in WOx nanowires. With the assistance of two current PhD students, we have observed the semiconducting to metallic transition in WOx nanowires which occurs upon diameter shrinkage or oxygen vacancy, which generates a plasmon resonance observed in the THz frequency region. To understand, control and explore the advantages of this transition is not only fundamentally important in materials science, but also is very important for future optical nanodevice development. Therefore, to investigate the THz characteristics of these interesting WOx nanowires, and to design and create various nanowires with desired transmission behaviours, form the core objectives of this joint project between the Functional Materials Group and THz photonic group.
Despite being the second most studied bulk oxide, with numerous potentials for application in sensors, electrodes and chromic devices, the inherited interesting features of nanoscale tungsten oxide, particularly in the 1D nanowire forms, are not well understood. WOx has almost countless stable compositions with x between 2-3, and almost all of them exhibit six stable crystalline structures and various oxygen vacancies. The geometry, diameter, compositional and vacancy status all have strong influences on the material properties. However, conventional materials characterisation techniques are not enough to unlock these complex behaviours. Cross-disciplinary research is required to gain understanding on this complex system at nanoscale.
In the project, we will use hydrothermal and CVD processes to create 1D nanowires of defined diameters and length, ranging from 5-200 nm in diameter and 1-10 um in length, and with three defined compositions, WO2, W18O49 and WO3. Conventional electron microscopic characterisation techniques and XRD will be used to obtain a general structural and compositional feature of the resulting nanowires. Once fully characterised, the investigation will then focus on the THz transmission behaviours of these different nanowires, to specifically understand the semiconducting to metallic transition, and obtain the affecting factors of these transitions. Further validation will be carried out by creating new nanowires with specific geometry and composition combinations, to tune and achieve desired THz characteristics. This validation is the core element of the project, because these outcomes will offer true impacts for other research by providing guidance and design criteria.
For more information about the project and informal enquiries, please contact the project supervisors: Prof Yanqiu Zhu (http://emps.exeter.ac.uk/engineering/staff/yz329) and Prof Euan Hendry (http://emps.exeter.ac.uk/physics-astronomy/staff/eh246)
Entry requirements:
Applicants for this research project must have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK, in an appropriate area of science or technology.
If English is not your first language you will need to meet the English language requirements and provide proof of proficiency.
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