{"id":{"repo_id":"adelaide","oai_identifier":"oai:digital.library.adelaide.edu.au:2440/132531"},"canonical_url":"https://search.dev.ndltd.org/etd/adelaide/oai:digital.library.adelaide.edu.au:2440/132531","repository":{"repo_id":"adelaide","name":"University of Adelaide","base_url":"https://digital.library.adelaide.edu.au/server/oai/request"},"display":{"title":"Predictive Model of Cap Formation for Carbon Nanotube Synthesis via Chemical Vapour Deposition","abstract":"Since their discovery in 1993, carbon nanotubes have been studied for their unique properties which make them an attractive option for many potential applications. Often such applications require the use of nanotubes with specific chiralities and therefore properties. Because of this, methods by which the structure of carbon nanotubes can be controlled during synthesis are desirable. Such methods may represent a significant decrease in the cost of producing carbon nanotubes for new technologies. In this thesis we develop a model for the growth and dewetting of graphene caps via chemical vapour deposition. This model will allow us to predict the conditions which favour the production of carbon nanotubes with a specific chirality. To model the growth of graphene caps wetted to a metallic catalyst particle, we use the calculus of variations to determine the optimal configuration of the system for various cap sizes. The growth of graphene caps is simulated by treating their surface area as a time-like variable. We use this model to predict when dewetting from the metallic catalyst particle becomes energetically favourable by comparing the optimal energies of the wetted and dewetted states. When dewetted, the structure of the graphene cap determines the structure of the resultant nanotube. Testing our model on three metallic catalysts we found that our model consistently predicted lower CNT diameters than those observed in experiments by other researchers. For iron carbide we predicted diameters of 6.5-7.1 A compared to 30 A in experiments, and for gold we predicted diameters of 7-9 A compared to 9-18 A in experiments. For nickel carbide our model predicted no CNT production despite it being a common catalyst material in CVD. Our model predicted that iron carbide catalyst particles would produce more metallic CNTs compared to gold, with 50% of CNTs produced using iron carbide predicted to be metallic compared to 33-46% of CNTs produced using gold. Due to the inaccuracy of our model when compared to experimental results, we recommend that future research focuses on improving the model. This could be achieved by reducing the amount or restrictiveness of our assumptions, or increasing the detail with which our model accounts for various factors of the cap growth and dewetting processes.","abstract_html":"Since their discovery in 1993, carbon nanotubes have been studied for their unique properties which make them an attractive option for many potential applications. Often such applications require the use of nanotubes with specific chiralities and therefore properties. Because of this, methods by which the structure of carbon nanotubes can be controlled during synthesis are desirable. Such methods may represent a significant decrease in the cost of producing carbon nanotubes for new technologies. In this thesis we develop a model for the growth and dewetting of graphene caps via chemical vapour deposition. This model will allow us to predict the conditions which favour the production of carbon nanotubes with a specific chirality. To model the growth of graphene caps wetted to a metallic catalyst particle, we use the calculus of variations to determine the optimal configuration of the system for various cap sizes. The growth of graphene caps is simulated by treating their surface area as a time-like variable. We use this model to predict when dewetting from the metallic catalyst particle becomes energetically favourable by comparing the optimal energies of the wetted and dewetted states. When dewetted, the structure of the graphene cap determines the structure of the resultant nanotube. Testing our model on three metallic catalysts we found that our model consistently predicted lower CNT diameters than those observed in experiments by other researchers. For iron carbide we predicted diameters of 6.5-7.1 A compared to 30 A in experiments, and for gold we predicted diameters of 7-9 A compared to 9-18 A in experiments. For nickel carbide our model predicted no CNT production despite it being a common catalyst material in CVD. Our model predicted that iron carbide catalyst particles would produce more metallic CNTs compared to gold, with 50% of CNTs produced using iron carbide predicted to be metallic compared to 33-46% of CNTs produced using gold. Due to the inaccuracy of our model when compared to experimental results, we recommend that future research focuses on improving the model. This could be achieved by reducing the amount or restrictiveness of our assumptions, or increasing the detail with which our model accounts for various factors of the cap growth and dewetting processes.","abstract_has_math":false,"creators":["Bowe, Patrick James"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Cox, Barry","Chen, Michael"],"committee_chairs":[],"committee_members":[],"year":2021,"date_issued":"2021","date_published":"2021","updated_at":"2026-07-24T00:51:02Z","subjects":["Nanotubes","mathematical modelling","chemical vapour deposition"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2440/132531","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Cox, Barry","Chen, Michael"]},{"key":"dc:creator","label":"Author","values":["Bowe, Patrick James"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.issued","label":"Date","values":["2021"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Nanotubes","mathematical modelling","chemical vapour deposition"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/2440/132531"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Since their discovery in 1993, carbon nanotubes have been studied for their unique properties which make them an attractive option for many potential applications. Often such applications require the use of nanotubes with specific chiralities and therefore properties. Because of this, methods by which the structure of carbon nanotubes can be controlled during synthesis are desirable. Such methods may represent a significant decrease in the cost of producing carbon nanotubes for new technologies. In this thesis we develop a model for the growth and dewetting of graphene caps via chemical vapour deposition. This model will allow us to predict the conditions which favour the production of carbon nanotubes with a specific chirality. To model the growth of graphene caps wetted to a metallic catalyst particle, we use the calculus of variations to determine the optimal configuration of the system for various cap sizes. The growth of graphene caps is simulated by treating their surface area as a time-like variable. We use this model to predict when dewetting from the metallic catalyst particle becomes energetically favourable by comparing the optimal energies of the wetted and dewetted states. When dewetted, the structure of the graphene cap determines the structure of the resultant nanotube. Testing our model on three metallic catalysts we found that our model consistently predicted lower CNT diameters than those observed in experiments by other researchers. For iron carbide we predicted diameters of 6.5-7.1 A compared to 30 A in experiments, and for gold we predicted diameters of 7-9 A compared to 9-18 A in experiments. For nickel carbide our model predicted no CNT production despite it being a common catalyst material in CVD. Our model predicted that iron carbide catalyst particles would produce more metallic CNTs compared to gold, with 50% of CNTs produced using iron carbide predicted to be metallic compared to 33-46% of CNTs produced using gold. Due to the inaccuracy of our model when compared to experimental results, we recommend that future research focuses on improving the model. This could be achieved by reducing the amount or restrictiveness of our assumptions, or increasing the detail with which our model accounts for various factors of the cap growth and dewetting processes."]},{"key":"dc:title","label":"Title","values":["Predictive Model of Cap Formation for Carbon Nanotube Synthesis via Chemical Vapour Deposition"]}]}],"canonical_facts":{"dc:contributor.advisor":["Cox, Barry","Chen, Michael"],"dc:creator":["Bowe, Patrick James"],"dc:date.issued":["2021"],"dc:description.abstract":["Since their discovery in 1993, carbon nanotubes have been studied for their unique properties which make them an attractive option for many potential applications. Often such applications require the use of nanotubes with specific chiralities and therefore properties. Because of this, methods by which the structure of carbon nanotubes can be controlled during synthesis are desirable. Such methods may represent a significant decrease in the cost of producing carbon nanotubes for new technologies. In this thesis we develop a model for the growth and dewetting of graphene caps via chemical vapour deposition. This model will allow us to predict the conditions which favour the production of carbon nanotubes with a specific chirality. To model the growth of graphene caps wetted to a metallic catalyst particle, we use the calculus of variations to determine the optimal configuration of the system for various cap sizes. The growth of graphene caps is simulated by treating their surface area as a time-like variable. We use this model to predict when dewetting from the metallic catalyst particle becomes energetically favourable by comparing the optimal energies of the wetted and dewetted states. When dewetted, the structure of the graphene cap determines the structure of the resultant nanotube. Testing our model on three metallic catalysts we found that our model consistently predicted lower CNT diameters than those observed in experiments by other researchers. For iron carbide we predicted diameters of 6.5-7.1 A compared to 30 A in experiments, and for gold we predicted diameters of 7-9 A compared to 9-18 A in experiments. For nickel carbide our model predicted no CNT production despite it being a common catalyst material in CVD. Our model predicted that iron carbide catalyst particles would produce more metallic CNTs compared to gold, with 50% of CNTs produced using iron carbide predicted to be metallic compared to 33-46% of CNTs produced using gold. Due to the inaccuracy of our model when compared to experimental results, we recommend that future research focuses on improving the model. This could be achieved by reducing the amount or restrictiveness of our assumptions, or increasing the detail with which our model accounts for various factors of the cap growth and dewetting processes."],"dc:identifier.uri":["https://hdl.handle.net/2440/132531"],"dc:language.iso":["en"],"dc:subject":["Nanotubes","mathematical modelling","chemical vapour deposition"],"dc:title":["Predictive Model of Cap Formation for Carbon Nanotube Synthesis via Chemical Vapour Deposition"],"dc:type":["Thesis"]},"updated_at":"2026-07-24T00:51:02Z"}