ISSRNS 2012: Abstracts / Synchrotron Radiation in Natural Science Vol. 11, No 1 – 2 (2012) P 68
SIZE DEPENDENCE OF MICROSTRAIN FLUCTUATIONS IN NANOCRYSTALLINE CHROMIUM
D. Wardecki1∗, R. Przenios lo1, A. Fitch2, M. Bukowski3, and R. Hempelmann3
1Faculty of Physics, University of Warsaw, Ho˙za 69, 00–681 Warsaw, Poland
2European Synchrotron Radiation Facility, BP 220 F–38043, Grenoble Cedex, France
3Institute of Physical Chemistry, University of Saarbr¨ucken, D–66123, Saarbr¨ucken, Germany Keywords: nanocrystalline chromium, synchrotron radiation, crystallite growth, microstrain fluctuations
∗e-mail : dward@fuw.edu.pl
The microstructure of nanocrystalline chromium (n-Cr) has been studied by high resolution powder diffraction on beamline ID-31 at ESRF. During the diffraction measurements the samples of n-Cr, ob- tained by the electrodeposition method, were an- nealed in-situ at temperatures 400◦C, 600◦C and 800◦C. In order to obtain the crystallite size D and the microstrain fluctuations ∆d/d as a function of the annealing time, the ’double-Voigt’ [1] analysis was performed.
For all n-Cr samples the annealing process leads to relatively fast crystallite size growth in the first
6 min. At the same time there is a rapid decrease
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
0 20 40 60 80 100 120 140
∆d/d [%]
D [nm]
800oC 600oC
400oC 300oC
as prepared Chojnowski et al.
n-Cr poly-Cr
Figure 1 : Microstrain fluctuations as a function of the crystallite size.
of the microstrain fluctuations. The final values of D and ∆d/d in n-Cr depend on the annealing tem- perature [2].
The results shows the clear relation between the crystallite size and the strains, which has been also noticed by other autors [3] for different nanocrystal- lline materials. Figure 1 shows the values of strains as a function of the crystallite size for n-Cr after 45 min. annealing at the three temperatures 400◦C, 600◦C and 800◦C (open circles). The points are compared with the data from Chojnowski et al. [4]
(black dots). One can see that for D > 100 nm the values of ∆d/d vary slightly as compared with the polycrystalline specimen.
References
[1] D. Balzar, Defect and Microstructure Analysis from Diffraction (Oxford University Press, New York, 1999).
[2] D. Wardecki, R. Przenios lo, A. Fitch, M. Bukowski, and R. Hempelmann, J. Nanopart. Res. 13 (2011) 1151.
[3] E. Roduner, Nanoscopic Materials. Size-Dependent Phenomena (RSC Publishing, 2006).
[4] G. Chojnowski, R. Przenios lo, I. Sosnowska, M. Bukowski, H. Natter, R. Hempelmann, A. Fitch, and V. Urban, J. Phys. Chem. C 111 (2007) 5599.
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