Hydrogen doping and the metal-insulator phase transition in vanadium dioxide

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dc.contributor.advisorNatelson, Douglasen_US
dc.contributor.committeeMemberDu, Rui-ruien_US
dc.contributor.committeeMemberBiswal, Sibani Len_US
dc.creatorJi, Hengen_US
dc.date.accessioned2016-01-29T17:14:43Zen_US
dc.date.available2016-01-29T17:14:43Zen_US
dc.date.created2015-05en_US
dc.date.issued2015-04-22en_US
dc.date.submittedMay 2015en_US
dc.date.updated2016-01-29T17:14:43Zen_US
dc.description.abstractStrongly correlated systems represent a major topic of study in condensed matter physics. Vanadium dioxide, a strongly correlated material, has a sharp metal-to-insulator phase transition at around 340 K (67 °C), a moderate temperature which can be easily achieved. Its potential as a functional material in optical switches and semiconductor applications has attracted a great deal of attention in recent years. In this thesis, after a detailed introduction of this material and the methods we used to grow VO2 in our lab (Chapter 1), I will discuss our attempts to modulate the electronic properties and phase transition of single-crystal VO2 samples. It started with a plan to use ionic liquid to apply an electrostatic gate to this material. Although modulation of the resistance was observed, we also discovered an unexpected electrochemical reaction, leading to a suspicion that hydrogen doping is the reason for the change of properties of VO2 (Chapter 2). Next, a series of experiments were performed to systematically study the mechanism of this hydrogen doping process and to characterize the hydrogenated VO2. Our collaborators also provided supporting simulation results to interpret these phenomena from a theoretical point of view, as well as results from synchrotron x-ray diffraction and neutron diffraction experiments. From all these studies, we confirmed the existence of the hydrogen intercalation in VO2 (Chapter 3), and further, plotted the phase diagram as a function of temperature and hydrogen concentration (Chapter 5). We also found that this diffusion process prefers the rutile crystal structure of VO2 (i.e. metallic phase) and specifically, its c-axis (Chapter 4). Finally, the low-temperature electric transport properties of the hydrogenated VO2 material have been studied for the first time, and interesting magneto-resistance responses will be discussed (chapter 6).en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.citationJi, Heng. "Hydrogen doping and the metal-insulator phase transition in vanadium dioxide." (2015) Diss., Rice University. <a href="https://hdl.handle.net/1911/88259">https://hdl.handle.net/1911/88259</a>.en_US
dc.identifier.urihttps://hdl.handle.net/1911/88259en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectVO2en_US
dc.subjectVanadium dioxideen_US
dc.subjecthydrogenationen_US
dc.subjectphase transitionen_US
dc.titleHydrogen doping and the metal-insulator phase transition in vanadium dioxideen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentPhysics and Astronomyen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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