Atomic-scale structure of materials with intrinsic disorder by the atomic Pair Distribution Function Technique and High energy x-ray diffraction
Valeri Petkov
Mt. Pleasant, MI 48858
Knowledge of the atomic-scale structure is an important prerequisite to understand and predict the 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 perfect crystals. The diffraction patterns of such materials show only a few Bragg peaks and a pronounced diffuse component. This poses a real challenge to the usual techniques for structure determination. The challenge can be met by employing the so-called atomic pair distribution function technique and high energy x-ray diffraction. The basic features of the technique will be introduced and it potential demonstrated with results from recent structure studies of In-Ga-As semiconductor alloys [1], V2O5 nanotubes [2], dendritic and hyper-branched macromolecules, Ca/Al silicate glasses [3] and gold nanoparticles.
[1] V.Petkov, I-K. Jeong,, J.S. Jung, M.F. Thorpe, S.Kycia and S.J.L. Billinge,
'High-resolution local structurein In xGa 1-xAs semiconductor alloys by high-energy X-ray diffraction', Phys. Rev. Lett. 83(1999) 4089.
[2] V. Petkov, P. Y. Zavalij, S. Lutta, M. S. Whittingham, V. Parvanov and S. Shastri, "Structure beyond Bragg: Study of V2O5 nanotubes", Phys. Rev. B 69 (2004) 085410.
[3] V.Petkov , S,J.L. Billinge, S. Shastri and B. Himmel, "Polyhedral units and network connectivity in calcium aluminosilicate glasses from high-energy x-ray diffraction" Phys. Rev. Lett. 85 (2000) 3436.
