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Computer programs have been written which allow morphological calculations based on a knowledge of internal crystal structure to he carried out. Details of the programs are presented along with the guidelines developed for their use. The programs were used to compare and contrast the current methods employed for relating crystal shape to structure and to confront specific problems in that field. Calculations on a range of compounds show that the morphologies derived from the simple Donnay-Harker (DHI) model give almost as good a fit to the observed form as the more sophisticated attachment energy (AE) calculations except when strong bonding directions were present. In the first study of its type all the methods currently favoured in the literature including the Ising and PBC approaches as well as DH and AE models were applied to benzophenone. All the models gave the same theoretical morphology. One problem remaining in the field of relating crystal structure and morphology is that of polar morphology. None of the current methods can account for a polar morphology. Surface, bulk, isolated molecule charge distributions were used in a modification of the classical attachment energy model to account for urea exhibiting a polar morphology when growth from the vapour phase. For the disruptive type of tailor made additives an improvement in the current methodology is proposed with the calculation of an additional parameter. This additional parameter accounts for the morphology with an additive present and gives good agreement with the test case of benzamide crystals grown with benzoic acid as an additive. The additive approach also allowed the effects of toluene solvent on the crystal habit of benzophenone to be considered By treating toluene as a tailor made additive it was possible from calculations to identify the likely sites of toluene incorporation and the subsequent effect on crystal growth. The results from the calculation were consistent with experiment.

Metal nanoparticles can possess intriguing properties due to their nanoscale dimensions, and are intensively applied in research. With the development of synthetic systems, classic crystal growth theories become limited and cannot explain current conditions very well. The aim of this project is to find out the factors that influence crystal growth at the nanoscale and develop general methods to prepare shape-controlled nanomaterials. The growth process of CuPt nanorods is studied and a ligand mediated mechanism is proposed. It reveals that surface ligands are crucial in guiding the one dimensional growth through their mutual interactions. Solvent effect is discovered to be able to control the nanoparticles morphology, by indirectly tuning the interactions between ligands and the surface of a particle. Based on this mechanism, titanate nanosheets with a monolayer thickness are prepared with the assistance of surface ligands. An effective, one-step method is developed to prepare CuPd nanowire networks, which demonstrates its versatility in the preparation of other alloyed networks. The growth process of CuPt nanoparticles are investigated, and show that the growth pathway can be a reversed, surface-to-core crystallization route. The effect of dealloying, including acid etching and galvanic replacement, is studied and used to fabricate nanoparticles with various morphologies. The findings in this project highlight the influence of surface ligands in the synthesis of nanocrystals, provide new perspectives of crystal growth mechanisms and offer practical knowledge for nanostructuring materials.

by Yang Hua. / "August 1999." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese. / by Yang Hua.

by Leung Kwok Kuen. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1997. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / by Leung Kwok Kuen.

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