From crystals to nanocrystals: Semiconductors and beyond
Conference
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OSTI ID:1008875
- MSU
Knowledge of the atomic-scale structure is an important prerequisite to understand and predict the physical properties of materials. In the case of crystals it is obtained from the positions and the intensities of the Bragg peaks in the diffraction data. However, many materials of technological importance are not perfectly crystalline but contain significant disorder at the atomic scale. The diffraction patterns of such materials show only a few Bragg peaks, if any, and a pronounced diffuse component. This poses a real challenge to the usual techniques for structure characterization. The challenge can be met by employing the so-called atomic pair distribution function (PDF) technique. The atomic PDF gives the number of atoms in a spherical shell of unit thickness at a distance r from a reference atom. It peaks at characteristic distances separating pairs of atoms and thus describes the structure of materials. The atomic PDF technique can be applied with success to study the structure of complex materials with intrinsic positional and/or chemical disorder. Key to the success is that both Bragg and the diffuse component of diffraction data are collected over a wide range of wave vectors before converted into the corresponding PDF. This makes the PDF a structure-sensitive quantity reflecting both the average and local structure of materials. By employing new sources of radiation such as x-ray synchrotrons, diffraction data extended to at least 40 {angstrom}{sup -1} can be collected even for materials composed of light, weakly scattering, atomic species and fine structural features differing in as little as 0.1 {angstrom} revealed. We hope that the examples shown here will motivate further development of the PDF technique as a routine tool in materials structure studies.
- Research Organization:
- Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1008875
- Country of Publication:
- United States
- Language:
- ENGLISH
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