In this dissertation, two advanced TEM techniques, image spectroscopy and electron tomography, are applied to the quantitative structural and chemical characterisation of nanostructured magnetic materials, in both two and three dimensions (3D), at nanometre spatial resolution. In image spectroscopy, chemical information is obtained by acquiring extended energy-selected series of images, which are interpreted using a combination of computer processing and traditional electron energy-loss spectroscopy (EELS) analysis. In tomography, 3D microstructural and chemical information is obtained by acquiring ultra-high tilt series of high-angle-annular dark field (HAADF) or energy-filtered TEM (EFTEM) images, and subsequently applying tomographic reconstruction and visualisation algorithms to the data. The techniques are applied to the characterisation of materials that include closely-spaced FeNi nanoparticles coated in oxide shells, lithographically patterned Ni pillars, platinum nanoparticles, chromium carbides in stainless steel, titanomagnetite and an ALH meteorite sample. Biological samples include magnetotactic crystals and bacteria cells, greigite-containing bacterial cells and amyloid plaque cores. The chemical data from image spectroscopy and morphological data from electron tomography are cross-correlated. Furthermore, experimental tomographic data are compared with tomographic reconstructions of image simulations.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:597636 |
| Date | January 2007 |
| Creators | Chong, K. K. R. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.001 seconds