This thesis presents the development of the experimental techniques required to study microstructure in powder samples at high pressure through the use of 2-d data. A description is given of the upgrade and installation of new experimental apparatus constructed to permit routine investigation of microstructure in samples under pressure. The experimental techniques have been applied to the modelling of preferred orientation in powders at high pressure. A demonstration of the qualitative information about preferred orientation in powders available from a 2-d detector is given. Details are presented of a quantitative model applied to image-plate data based on preferred orientation corrections commonly used in Rietvald refinement programs. It is shown that this quantitative model is not completely adequate for describing the extremely strong preferred orientation often found in powder samples at high-pressure and a new more general model based on a commonly used model of texture used by the texture analysis community is presented and shown to work well. The structural pressure dependence of the cinnabar phase of HgS is presented. Strong preferred orientation can be induced in HgS at high pressure, it is shown that, by using the preferred orientation modelling techniques presented in this thesis, it has been possible to de-correlate the effect of preferred orientation from the refined structural parameters.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:641515 |
| Date | January 1998 |
| Creators | Belmonte, Scott A. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13951 |
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