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X-Ray Characterization of Nanostructured Materials

Roman Pielaszek 3,4Stanisław Gierlotka 4Ewa Grzanka 3,4Svitlana Stelmakh 4Bogdan F. Palosz 4

1. Warsaw University, Faculty of Physics, Hoża 69, Warszawa 00-681, Poland
2. Polish Academy of Sciences, High Pressure Research Center (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland
3. Warsaw University, Faculty of Physics, Hoża 69, Warszawa 00-681, Poland
4. Polish Academy of Sciences, High Pressure Research Center (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland

Abstract


One of most general diffraction laws, Debye formula, allows to
calculate X-Ray powder diffraction pattern of any cluster of atoms,
with no additional assumptions about its structure. Nowadays computers
enable a direct ('ab initio') calculations of diffraction profiles for
clusters as large as several hundred in diameter, fairly covering
scale of nanomaterials.
Population of atomic models of SiC, GaN and diamond nanocrystals used
for calculations of the diffraction effects were built to examine the
effects of average grain size, grain size distributions, presence of
stacking faults, shape anisotropies, surface strains, bulk strains or
a combination of above. Genetic Algorithm (GA) survives the fittest
individual model, with compliance to experimental data as a fitness
function.
Here we give some examples of X-Ray-based analysis of nanocrystalline
materials and we will concentrate on sensitivity of the method to some
specific structural properties, in particular to determination of
grain size distribution and presence of stacking faults in individual
crystallites.
In this work we will present the method of performance of 'ab initio'
calculations of the diffraction profiles of nanocrystalline powders
which we developed and we present here as rpnano package being a
software tool for X-Ray characterization of nanostructured materials.
Acknowledgements
This work was supported by the State Committee for Scientific
Research, Grants No. 7/T08A/036/18 and 7/T08A/030/19.

 

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Related papers

Presentation: oral at High Pressure School 2001 (4th), by Roman Pielaszek
See On-line Journal of High Pressure School 2001 (4th)

Submitted: 2003-02-16 17:33
Revised:   2009-06-08 12:55