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Title: Making and manipulating nanowires inside carbon nanotubes
Author: So, Karwei
ISNI:       0000 0004 7652 3799
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2017
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This thesis summaries the study of various aspects related to the growth of multi-wall carbon nanotubes (MWCNTs) filled with metals and their post-synthesis processing to form macroscopic papers, known as buckypapers (BPs). Fe-filled MWCNTs (Fe@MWCNTs) and Fe/Co-filled MWCNTs (Fe/Co@MWCNTs) were produced by chemical vapour deposition (CVD), with the objective of growing sufficient quantities of these materials, whilst retaining their quality. A systematic study was carried out to investigate the effects of changing the synthesis parameters (sublimation and pyrolysis temperature, furnace gap and Ar flow) on the quality of Fe@MWCNTs produced. Crucially, this systematic study revealed the conditions to produce Fe@MWCNTs of high enough quality and quantity for post-synthesis processing. In situ residual gas analysis (RGA) revealed that regardless of pyrolysis temperature, the detected high mass fragments were broken down over the course of the reaction to ethene and methane, which continued to break down and release H2 even after exhaustion of ferrocene. In situ TEM studied passing current through a Co- NP decorated Fe@MWCNT and emphasised the importance of discerning the affects of current on the structure of the metal filling before utilising them in electrical applications. Fe@MWCNTs were processed to form BPs (4 cm diameter), constructed by depositing layers of Fe@MWCNTs and conventional MWCNTs. Strips of these BPs were successfully prototyped as the moving component in a non-metallic electromechanical relay. I/V measurements showed these ferromagnetic BPs were capable of consistently carrying the same current at a given voltage, up to 3 V, for a minimum of 50 cycles. Selectively depositing the Fe@MWCNTs produced BPs which responded in pre-selected regions to external magnetic stimuli. Tensile tests performed on BPs formed of conventional and N-doped MWCNTs, of two different lengths each, revealed that CNT length and type influence different aspects of the BP's mechanical properties.
Supervisor: Grobert, Nicole ; Dillon, Frank Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available