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Title: Synthesis and characterisation of novel solids
Author: Collins, C.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2000
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Abstract:
Two distinct types of solid are characterized using an array of structure elucidation techniques. Part One of this thesis describes the characterization techniques employed, Part Two describes studies of fullerene C60 and its derivatives and Part Three examines the silica garden. Highly-crystalline face-centred-cubic (fcc) C60 spontaneously forms crystalline solvates through the incorporation of solvents, used to separate C60 from raw soot, into the host lattice. The intercalated solvent is often difficult to remove completely, which makes pure C60 difficult to prepare. The structure and molecular motion of C60/CHBr3 is examined as a model solvate system. Pure C60 readily forms intercalates by admitting gaseous molecules into the interstitial voids, which is of interest for gas storage. C60/gas intercalates also affords the opportunity to observe the behaviour of trapped molecular species separated by the large C60 cages. Deuterated water within a C60 intercalate is examined for the first time using 2H solid-state nuclear magnetic resonance (NMR). It has recently been suggested that, in addition to the well-known phase transition of C60 at 260K, there is a phase transition at a higher temperature (ca. 435 K). High-temperature powder X-ray diffraction is used in an attempt to confirm this transition and to study the thermal stability of solid fcc C60 and C70. The thermal expansion of C60 and C70 is also studied. The silica garden, a structural precipitate made by seeding a solution of sodium silicate with crystals of water soluble metal salts, is studied with electron microscopy. When aluminium nitrate is used as a seed, the bulk precipitate has a hierarchic substructure comprising fine tubes ca. 44 nm in diameter composed of amorphous silica rods. A unique "from-the-inside" degradation of a silica garden precipitate under beam irradiation in a high-resolution electron microscope is also described.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.597871  DOI: Not available
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