{"id":{"repo_id":"rice","oai_identifier":"oai:repository.rice.edu:1911/118662"},"canonical_url":"https://search.dev.ndltd.org/etd/rice/oai:repository.rice.edu:1911/118662","repository":{"repo_id":"rice","name":"Rice University","base_url":"https://repository.rice.edu/server/oai/request"},"display":{"title":"Beyond Flash Joule Heating: Advanced Non-equilibrium Synthesis and Electron Microscopy Characterization","abstract":"Flash Joule heating (FJH) has emerged as a highly efficient method for synthesizing a diverse array of advanced materials. This ultrafast, non-equilibrium technique has demonstrated significant potential in transforming various carbon sources into turbostratic flash graphene, synthesizing refractory materials such as metal carbides, converting 2H-phase MoS2 into 1T-phase MoS2, and extracting valuable hydrogen gas from plastic waste. Despite these impressive achievements, FJH still faces critical limitations, including its requirement for material conductivity, restricted generality, and an inability to facilitate non-solid-state reactions. To overcome these limitations, several innovative strategies have been developed. One notable approach involves introducing immiscible conductive additives, specifically copper (Cu), into highly resistive amorphous boron (B), effectively enabling flash Joule heating. Surprisingly, during this modified process—termed plasma flash Joule heating (PFJH)—we observed spontaneous plasma generation, surpassing conventional temperature limits (~3000 K) and facilitating rapid crystallization of amorphous boron into crystalline form. Subsequent analysis revealed an unexpected and significant discovery: even after thorough removal of excess copper, copper atoms remained homogeneously embedded within the crystalline boron matrix, resulting in the unprecedented synthesis of copper-doped crystalline boron (Cu-B). Further investigation using 3D micro electron diffraction demonstrated that the rapid heating and cooling intrinsic to PFJH prevented phase segregation, effectively trapping immiscible copper atoms within the boron lattice. This Cu-B composite exhibited notably altered mechanical properties, including a reduced modulus (~267 GPa) and Vickers hardness (~20 GPa), alongside a remarkable optical transition from indirect to direct bandgap. This unexpected change in bandgap structure induced pronounced photoluminescence (PL), revealing a novel material functionality unattainable through conventional methods. These findings highlight PFJH's potential as an ultrafast, non-equilibrium approach for synthesizing novel materials exhibiting extraordinary and unforeseen physical properties. To expand the versatility of Joule heating further, we introduced an indirect heating method called Flash-within-Flash (FWF) Joule heating. This innovative approach greatly broadens the applicability of FJH, enabling the synthesis of 22 different compounds with properties comparable or superior to commercially available materials. Emphasizing sustainability, FWF addresses critical issues such as energy efficiency, minimal water consumption, scalability, and diverse material synthesis. FWF rapidly produces 10 transition metal dichalcogenides (TMDs), 3 Group-XIV dichalcogenides, and 9 non-TMD materials, with each synthesis completed within five seconds under ambient conditions. Moreover, FWF uniquely allows phase-selective synthesis and generates single-crystalline bulk powders. The enhanced tribological performance of FWF-produced MoSe2 compared to commercial materials further demonstrates the technique's effectiveness. Additionally, the versatility of FWF in facilitating atom substitution and doping establishes it as a robust protocol for general inorganic material synthesis. Acknowledging the limitations associated with non-solid-state reactions, we developed Flash Vapor Deposition (FVD), a novel reactor design combining chemical vapor deposition (CVD) with the rapid heating principles of FWF Joule heating. Traditional CVD methods suffer from slow temperature ramping, restricting their effectiveness for rapid monolayer synthesis and complex coatings. Our redesigned FVD apparatus incorporates an outer tube containing carbon felt within an inert atmosphere, enabling rapid, uniform radiative heating. The inner tube, isolated from direct contact with heating components, contains reagents and substrates, with precise mass transport achieved through controlled gas flow. This innovative design facilitates the rapid synthesis of high-quality monolayer TMDs directly on substrates such as Si/SiO2. Collectively, these advancements significantly enhance the versatility and efficacy of flash Joule heating, transforming it into a comprehensive, ultrafast, non-equilibrium synthesis platform. By overcoming previous limitations, these developed techniques pave the way for broad and impactful applications across various domains in materials science, positioning flash Joule heating as a critical enabler of future material innovations. The logical sequence of the PhD work and findings are summarized in Figure 1 for visualization.","abstract_html":"Flash Joule heating (FJH) has emerged as a highly efficient method for synthesizing a diverse array of advanced materials. This ultrafast, non-equilibrium technique has demonstrated significant potential in transforming various carbon sources into turbostratic flash graphene, synthesizing refractory materials such as metal carbides, converting 2H-phase MoS2 into 1T-phase MoS2, and extracting valuable hydrogen gas from plastic waste. Despite these impressive achievements, FJH still faces critical limitations, including its requirement for material conductivity, restricted generality, and an inability to facilitate non-solid-state reactions. To overcome these limitations, several innovative strategies have been developed. One notable approach involves introducing immiscible conductive additives, specifically copper (Cu), into highly resistive amorphous boron (B), effectively enabling flash Joule heating. Surprisingly, during this modified process—termed plasma flash Joule heating (PFJH)—we observed spontaneous plasma generation, surpassing conventional temperature limits (~3000 K) and facilitating rapid crystallization of amorphous boron into crystalline form. Subsequent analysis revealed an unexpected and significant discovery: even after thorough removal of excess copper, copper atoms remained homogeneously embedded within the crystalline boron matrix, resulting in the unprecedented synthesis of copper-doped crystalline boron (Cu-B). Further investigation using 3D micro electron diffraction demonstrated that the rapid heating and cooling intrinsic to PFJH prevented phase segregation, effectively trapping immiscible copper atoms within the boron lattice. This Cu-B composite exhibited notably altered mechanical properties, including a reduced modulus (~267 GPa) and Vickers hardness (~20 GPa), alongside a remarkable optical transition from indirect to direct bandgap. This unexpected change in bandgap structure induced pronounced photoluminescence (PL), revealing a novel material functionality unattainable through conventional methods. These findings highlight PFJH's potential as an ultrafast, non-equilibrium approach for synthesizing novel materials exhibiting extraordinary and unforeseen physical properties. To expand the versatility of Joule heating further, we introduced an indirect heating method called Flash-within-Flash (FWF) Joule heating. This innovative approach greatly broadens the applicability of FJH, enabling the synthesis of 22 different compounds with properties comparable or superior to commercially available materials. Emphasizing sustainability, FWF addresses critical issues such as energy efficiency, minimal water consumption, scalability, and diverse material synthesis. FWF rapidly produces 10 transition metal dichalcogenides (TMDs), 3 Group-XIV dichalcogenides, and 9 non-TMD materials, with each synthesis completed within five seconds under ambient conditions. Moreover, FWF uniquely allows phase-selective synthesis and generates single-crystalline bulk powders. The enhanced tribological performance of FWF-produced MoSe2 compared to commercial materials further demonstrates the technique's effectiveness. Additionally, the versatility of FWF in facilitating atom substitution and doping establishes it as a robust protocol for general inorganic material synthesis. Acknowledging the limitations associated with non-solid-state reactions, we developed Flash Vapor Deposition (FVD), a novel reactor design combining chemical vapor deposition (CVD) with the rapid heating principles of FWF Joule heating. Traditional CVD methods suffer from slow temperature ramping, restricting their effectiveness for rapid monolayer synthesis and complex coatings. Our redesigned FVD apparatus incorporates an outer tube containing carbon felt within an inert atmosphere, enabling rapid, uniform radiative heating. The inner tube, isolated from direct contact with heating components, contains reagents and substrates, with precise mass transport achieved through controlled gas flow. This innovative design facilitates the rapid synthesis of high-quality monolayer TMDs directly on substrates such as Si/SiO2. Collectively, these advancements significantly enhance the versatility and efficacy of flash Joule heating, transforming it into a comprehensive, ultrafast, non-equilibrium synthesis platform. By overcoming previous limitations, these developed techniques pave the way for broad and impactful applications across various domains in materials science, positioning flash Joule heating as a critical enabler of future material innovations. The logical sequence of the PhD work and findings are summarized in Figure 1 for visualization.","abstract_has_math":false,"creators":["Choi, Will"],"institution":"Rice University","degree_name":"Doctor of Philosophy","degree_level":"Doctoral","degree_discipline":"Engineering","degree_department":null,"school":null,"contributors":[],"advisors":["Tour, James","Han, Yimo"],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-08-13","date_published":"2025-08-13","updated_at":"2026-07-24T04:10:28Z","subjects":["Flash Joule Heating","Flash-within-flash Joule Heating","Ultrafast Material Synthesis","Electron Microscopy","Non-equilibrium Kinetics","Semiconductor","Characterization"],"languages":["eng"],"rights":["Copyright 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."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/1911/118662","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Tour, James","Han, Yimo"]},{"key":"dc:creator","label":"Author","values":["Choi, Will"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-09-04T15:55:45Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-08-13"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Rice University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Flash Joule Heating","Flash-within-flash Joule Heating","Ultrafast Material Synthesis","Electron Microscopy","Non-equilibrium Kinetics","Semiconductor","Characterization"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 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."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/1911/118662"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Flash Joule heating (FJH) has emerged as a highly efficient method for synthesizing a diverse array of advanced materials. This ultrafast, non-equilibrium technique has demonstrated significant potential in transforming various carbon sources into turbostratic flash graphene, synthesizing refractory materials such as metal carbides, converting 2H-phase MoS2 into 1T-phase MoS2, and extracting valuable hydrogen gas from plastic waste. Despite these impressive achievements, FJH still faces critical limitations, including its requirement for material conductivity, restricted generality, and an inability to facilitate non-solid-state reactions. To overcome these limitations, several innovative strategies have been developed. One notable approach involves introducing immiscible conductive additives, specifically copper (Cu), into highly resistive amorphous boron (B), effectively enabling flash Joule heating. Surprisingly, during this modified process—termed plasma flash Joule heating (PFJH)—we observed spontaneous plasma generation, surpassing conventional temperature limits (~3000 K) and facilitating rapid crystallization of amorphous boron into crystalline form. Subsequent analysis revealed an unexpected and significant discovery: even after thorough removal of excess copper, copper atoms remained homogeneously embedded within the crystalline boron matrix, resulting in the unprecedented synthesis of copper-doped crystalline boron (Cu-B). Further investigation using 3D micro electron diffraction demonstrated that the rapid heating and cooling intrinsic to PFJH prevented phase segregation, effectively trapping immiscible copper atoms within the boron lattice. This Cu-B composite exhibited notably altered mechanical properties, including a reduced modulus (~267 GPa) and Vickers hardness (~20 GPa), alongside a remarkable optical transition from indirect to direct bandgap. This unexpected change in bandgap structure induced pronounced photoluminescence (PL), revealing a novel material functionality unattainable through conventional methods. These findings highlight PFJH's potential as an ultrafast, non-equilibrium approach for synthesizing novel materials exhibiting extraordinary and unforeseen physical properties. To expand the versatility of Joule heating further, we introduced an indirect heating method called Flash-within-Flash (FWF) Joule heating. This innovative approach greatly broadens the applicability of FJH, enabling the synthesis of 22 different compounds with properties comparable or superior to commercially available materials. Emphasizing sustainability, FWF addresses critical issues such as energy efficiency, minimal water consumption, scalability, and diverse material synthesis. FWF rapidly produces 10 transition metal dichalcogenides (TMDs), 3 Group-XIV dichalcogenides, and 9 non-TMD materials, with each synthesis completed within five seconds under ambient conditions. Moreover, FWF uniquely allows phase-selective synthesis and generates single-crystalline bulk powders. The enhanced tribological performance of FWF-produced MoSe2 compared to commercial materials further demonstrates the technique's effectiveness. Additionally, the versatility of FWF in facilitating atom substitution and doping establishes it as a robust protocol for general inorganic material synthesis. Acknowledging the limitations associated with non-solid-state reactions, we developed Flash Vapor Deposition (FVD), a novel reactor design combining chemical vapor deposition (CVD) with the rapid heating principles of FWF Joule heating. Traditional CVD methods suffer from slow temperature ramping, restricting their effectiveness for rapid monolayer synthesis and complex coatings. Our redesigned FVD apparatus incorporates an outer tube containing carbon felt within an inert atmosphere, enabling rapid, uniform radiative heating. The inner tube, isolated from direct contact with heating components, contains reagents and substrates, with precise mass transport achieved through controlled gas flow. This innovative design facilitates the rapid synthesis of high-quality monolayer TMDs directly on substrates such as Si/SiO2. Collectively, these advancements significantly enhance the versatility and efficacy of flash Joule heating, transforming it into a comprehensive, ultrafast, non-equilibrium synthesis platform. By overcoming previous limitations, these developed techniques pave the way for broad and impactful applications across various domains in materials science, positioning flash Joule heating as a critical enabler of future material innovations. The logical sequence of the PhD work and findings are summarized in Figure 1 for visualization."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Beyond Flash Joule Heating: Advanced Non-equilibrium Synthesis and Electron Microscopy Characterization"]}]}],"canonical_facts":{"dc:contributor.advisor":["Tour, James","Han, Yimo"],"dc:creator":["Choi, Will"],"dc:date.accessioned":["2025-09-04T15:55:45Z"],"dc:date.issued":["2025-08-13"],"dc:description.abstract":["Flash Joule heating (FJH) has emerged as a highly efficient method for synthesizing a diverse array of advanced materials. This ultrafast, non-equilibrium technique has demonstrated significant potential in transforming various carbon sources into turbostratic flash graphene, synthesizing refractory materials such as metal carbides, converting 2H-phase MoS2 into 1T-phase MoS2, and extracting valuable hydrogen gas from plastic waste. Despite these impressive achievements, FJH still faces critical limitations, including its requirement for material conductivity, restricted generality, and an inability to facilitate non-solid-state reactions. To overcome these limitations, several innovative strategies have been developed. One notable approach involves introducing immiscible conductive additives, specifically copper (Cu), into highly resistive amorphous boron (B), effectively enabling flash Joule heating. Surprisingly, during this modified process—termed plasma flash Joule heating (PFJH)—we observed spontaneous plasma generation, surpassing conventional temperature limits (~3000 K) and facilitating rapid crystallization of amorphous boron into crystalline form. Subsequent analysis revealed an unexpected and significant discovery: even after thorough removal of excess copper, copper atoms remained homogeneously embedded within the crystalline boron matrix, resulting in the unprecedented synthesis of copper-doped crystalline boron (Cu-B). Further investigation using 3D micro electron diffraction demonstrated that the rapid heating and cooling intrinsic to PFJH prevented phase segregation, effectively trapping immiscible copper atoms within the boron lattice. This Cu-B composite exhibited notably altered mechanical properties, including a reduced modulus (~267 GPa) and Vickers hardness (~20 GPa), alongside a remarkable optical transition from indirect to direct bandgap. This unexpected change in bandgap structure induced pronounced photoluminescence (PL), revealing a novel material functionality unattainable through conventional methods. These findings highlight PFJH's potential as an ultrafast, non-equilibrium approach for synthesizing novel materials exhibiting extraordinary and unforeseen physical properties. To expand the versatility of Joule heating further, we introduced an indirect heating method called Flash-within-Flash (FWF) Joule heating. This innovative approach greatly broadens the applicability of FJH, enabling the synthesis of 22 different compounds with properties comparable or superior to commercially available materials. Emphasizing sustainability, FWF addresses critical issues such as energy efficiency, minimal water consumption, scalability, and diverse material synthesis. FWF rapidly produces 10 transition metal dichalcogenides (TMDs), 3 Group-XIV dichalcogenides, and 9 non-TMD materials, with each synthesis completed within five seconds under ambient conditions. Moreover, FWF uniquely allows phase-selective synthesis and generates single-crystalline bulk powders. The enhanced tribological performance of FWF-produced MoSe2 compared to commercial materials further demonstrates the technique's effectiveness. Additionally, the versatility of FWF in facilitating atom substitution and doping establishes it as a robust protocol for general inorganic material synthesis. Acknowledging the limitations associated with non-solid-state reactions, we developed Flash Vapor Deposition (FVD), a novel reactor design combining chemical vapor deposition (CVD) with the rapid heating principles of FWF Joule heating. Traditional CVD methods suffer from slow temperature ramping, restricting their effectiveness for rapid monolayer synthesis and complex coatings. Our redesigned FVD apparatus incorporates an outer tube containing carbon felt within an inert atmosphere, enabling rapid, uniform radiative heating. The inner tube, isolated from direct contact with heating components, contains reagents and substrates, with precise mass transport achieved through controlled gas flow. This innovative design facilitates the rapid synthesis of high-quality monolayer TMDs directly on substrates such as Si/SiO2. Collectively, these advancements significantly enhance the versatility and efficacy of flash Joule heating, transforming it into a comprehensive, ultrafast, non-equilibrium synthesis platform. By overcoming previous limitations, these developed techniques pave the way for broad and impactful applications across various domains in materials science, positioning flash Joule heating as a critical enabler of future material innovations. The logical sequence of the PhD work and findings are summarized in Figure 1 for visualization."],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["https://hdl.handle.net/1911/118662"],"dc:language.iso":["eng"],"dc:rights":["Copyright 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."],"dc:subject":["Flash Joule Heating","Flash-within-flash Joule Heating","Ultrafast Material Synthesis","Electron Microscopy","Non-equilibrium Kinetics","Semiconductor","Characterization"],"dc:title":["Beyond Flash Joule Heating: Advanced Non-equilibrium Synthesis and Electron Microscopy Characterization"],"dc:type":["Thesis"],"thesis:degree_discipline":["Engineering"],"thesis:degree_level":["Doctoral"],"thesis:degree_name":["Doctor of Philosophy"],"thesis:institution_name":["Rice University"]},"updated_at":"2026-07-24T04:10:28Z"}