{"629561":{"#nid":"629561","#data":{"type":"event","title":"PhD Defense by Lei Zhang","body":[{"value":"\u003Cp\u003E\u003Cstrong\u003ESCHOOL OF MATERIALS SCIENCE AND ENGINEERING\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EGEORGIA INSTITUTE OF TECHNOLOGY\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EUnder the provisions of the regulations for the degree\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u003Cstrong\u003EDOCTOR OF PHILOSOPHY\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u003Cstrong\u003Eon Thursday, December 19, 2019\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003E2:00 PM\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cstrong\u003Ein MoSE 3201A\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003Ewill be held the\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EDISSERTATION\u0026nbsp;DEFENSE\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u003Cstrong\u003Efor\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ELei\u0026nbsp;Zhang\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003E\u0026quot;Atomic Level Computational Probes on Ionic Defect and Transport Properties in Solid State Ionics\u0026quot;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ECommittee Members:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Meilin Liu, Advisor, MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Rampi Ramprasad, MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Ting Zhu, ME\/MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Angus Wilkinson, CHEM\/MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Jean Luc Bredas, CHEM\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EAbstract:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESolid state ionics plays a key role in energy conversion purpose. Ionic defect and transport properties at atomic level is precisely probed by a combination of computational techniques, including density functional theory calculations, phonon calculations, molecular dynamics simulations, cluster-expansion and Monte-Carlo modeling. Within this type of material family, key physics including elastic and electrostatic interactions, configurational entropy-enthalpy competition, chemo-mechanical coupling, collective behavior of ion transport are unveiled by advanced computation techniques.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EBarium hafnate, i.e. BaHfO\u003Csub\u003E3\u003C\/sub\u003E is one of the promising proton conducting, as similar as BaZrO\u003Csub\u003E3\u003C\/sub\u003E. The proton conductivity at relatively high temperature range, i.e. 400~700 \u0026deg;C, can be utilized as the electrolyte layer in solid oxide fuel cells (SOFCs). A wide spectrum of relevant properties, including hydration percentage, proton diffusion, stability against CO\u003Csub\u003E2\u003C\/sub\u003E, are sensitive to chemical dopants in the lattice, i.e. Li, Na, K, Rb, Cs on A-site, and Sc, Y, La, Gd, Lu, Al, Ga, In on B-site. Fundamental mechanism behind those properties upon various chemical dopants are investigated to achieve a rational design of doped-BaHfO\u003Csub\u003E3\u003C\/sub\u003E.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDislocation in Y:BaZrO\u003Csub\u003E3\u003C\/sub\u003E affects oxygen ion transport, due to the distinct strain and local environment w.r.t bulk lattice. To probe the ion mobility, a reactive molecular dynamics simulation based on ReaxFF are utilized to simulate the large supercell with such microstructural feature. Radial distribution function is used to analyze the local structure feature, mean-square displacement is used to calculate diffusivity. Dislocation is found to have an impact on ionic transport, however, in a different way for oxygen ions and protons. This could be due to the distinct ionic size, as well as electrostatic charge of oxygen ions and protons.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EStrain also affects another type of ionic materials, i.e. fluorite-structured CeO\u003Csub\u003E2\u003C\/sub\u003E, which is one of the most common oxygen ion conducting electrolyte in SOFCs, as well as oxygen buffering\/catalyzing material. Unlike BaZrO\u003Csub\u003E3\u003C\/sub\u003E perovskite, which has merely no electronic conductivity, ceria can create intrinsic oxygen vacancies and electron-polarons easily under reducing conditions. We propose a unique way of tuning vacancy-polaron configurational relationship, by applying tensile and compressive epitaxial strain on (111) slab. Interesting stability cross-over on surface\/sub-surface vacancy, 1NN\/2NN polaron, isolated\/dimer vacancies through strain are discovered. This might give a hint of various observed surface vacancy patterns in prepared ceria samples.\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"Atomic Level Computational Probes on Ionic Defect and Transport Properties in Solid State Ionics"}],"uid":"27707","created_gmt":"2019-12-02 19:18:28","changed_gmt":"2019-12-02 19:18:28","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2019-12-19T14:00:00-05:00","event_time_end":"2019-12-19T16:00:00-05:00","event_time_end_last":"2019-12-19T16:00:00-05:00","gmt_time_start":"2019-12-19 19:00:00","gmt_time_end":"2019-12-19 21:00:00","gmt_time_end_last":"2019-12-19 21:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"100811","name":"Phd Defense"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"78771","name":"Public"},{"id":"174045","name":"Graduate students"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}