Microstructure Analysis on Nanocrystalline Materials COMMISSION ...
Microstructure Analysis on Nanocrystalline Materials COMMISSION ...
Microstructure Analysis on Nanocrystalline Materials COMMISSION ...
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200 Å<br />
Fig. 10. HRTEM micrograph of the sample with the<br />
overall chemical compositi<strong>on</strong> Cr0.91Al0.08Si0.01N.<br />
CONCLUSIONS<br />
It was shown that broad reciprocal lattice points from<br />
nanosized crystallites can overlap each other. This<br />
overlap of the reciprocal lattice points reduces the<br />
broadening of the diffracti<strong>on</strong> lines as seen by X-ray diffracti<strong>on</strong>.<br />
In the direct space, the overlap of the reciprocal<br />
lattice points is equivalent to the partial coherence<br />
of adjacent crystallites that “enlarges” their size as seen<br />
by X-rays. As the overlap of the reciprocal lattice<br />
points decreases with increasing size of the diffracti<strong>on</strong><br />
vector, the effect of the partial coherence of crystallites<br />
<strong>on</strong> the line broadening varies with the diffracti<strong>on</strong> angle,<br />
which can be used to obtain the following microstructural<br />
informati<strong>on</strong> from the XRD line broadening.<br />
• Size of individual partially coherent crystallites<br />
can be calculated from the maximum (saturated)<br />
diffracti<strong>on</strong> line broadening observed for large diffracti<strong>on</strong><br />
angles.<br />
• Mean local disorientati<strong>on</strong> of the individual partially<br />
coherent neighbouring crystallites is related<br />
to the size of the diffracti<strong>on</strong> vector, for which the<br />
partial coherence of crystallites disappears.<br />
• Size of the blocks composed of individual partially<br />
coherent crystallites can be estimated from the extrapolati<strong>on</strong><br />
of the diffracti<strong>on</strong> line broadening to q =<br />
0.<br />
The partial coherence of neighbouring crystallites was<br />
observed in materials c<strong>on</strong>sisting of nanocrystalline<br />
domains with a str<strong>on</strong>g local preferred orientati<strong>on</strong> of<br />
crystallites. <strong>Nanocrystalline</strong> domains are necessary for<br />
getting broadened reciprocal lattice points; str<strong>on</strong>g local<br />
texture is needed for a sufficient overlap of the reciprocal<br />
lattice points from neighbouring crystallites. The<br />
last requirement for the partial coherence of nanocrystallites<br />
is that the distance of such nanocrystallites must<br />
be smaller than the coherence length of the X-rays used<br />
for the experiment, which is a general optical requirement<br />
for interference of scattered waves.<br />
ACKNOWLEDGEMENTS<br />
The authors appreciate the financial support of the project<br />
number RA-1050/9-1 through the German Research<br />
Council (DFG). The HRTEM JEM 2010 FEF<br />
was financed through DFG in the frame of the Priority<br />
program number 1062. Furthermore, we thank Dr. M.<br />
Šíma and M. Růžička (SHM Ltd., Šumperk, Czech Republic)<br />
for providing us with samples of the Ti-Al-Si-N<br />
and Cr-Al-Si-N thin films nanocomposites.<br />
REFERENCES<br />
* On leave from the Department of C<strong>on</strong>densed<br />
Matter Physics, Faculty of Mathematics and<br />
Physics, Charles University Prague, Czech Republic<br />
[1] R.L. Snyder, J. Fiala, H.J. Bunge: Defect and <str<strong>on</strong>g>Microstructure</str<strong>on</strong>g><br />
<str<strong>on</strong>g>Analysis</str<strong>on</strong>g> by Diffracti<strong>on</strong>, Oxford<br />
University Press, 1999.<br />
[2] N. Guillou, J.P. Auffrédic, D. Louër, Powder Diffracti<strong>on</strong><br />
10 (1995) 236.<br />
[3] J.I. Langford, D. Louër, P. Scardi, J. Appl. Cryst.<br />
33 (2000) 964.<br />
[4] A. Cervellino, C. Giannini, A. Guagliardi, J.<br />
Appl. Cryst. 36 (2003) 1148–1158.<br />
[5] D. Rafaja, M. Šíma, V. Klemm, G. Schreiber, D.<br />
Heger, L. Havela, R. Kužel, J. Alloys Comp. 378<br />
(2004) 107.<br />
[6] D. Rafaja, V. Klemm, G. Schreiber, M. Knapp,<br />
R. Kužel, J. Appl. Cryst. 37 (2004) 613.<br />
[7] G. Ribárik, N. Auderbrand, H. Palancher, T. Ungár,<br />
D. Louër, J. Appl. Cryst. 38 (2005) 912.<br />
[8] A. Cervellino, C. Giannini, A. Guagliardi, M.<br />
Ladisa, Phys. Rev. B72 (2005) 035412.<br />
[9] D. Rafaja, A. Poklad, V. Klemm, G. Schreiber,<br />
D. Heger, M. Šíma, M. Dopita, Thin Solid Films<br />
514 (2006) 240-249.<br />
[10] C. Giacovazzo, H.L. M<strong>on</strong>aco, G. Artioli, D. Viterbo,<br />
G. Feraris, G. Gilli, G. Zanotti, M. Catti:<br />
Fundamentals of Crystallography, 2 nd Editi<strong>on</strong>,<br />
IUCr Texts <strong>on</strong> Crystallography 7, Oxford University<br />
Press, 2002.<br />
[11] M. Born, E. Wolf: Principles of Optics, 7 th Editi<strong>on</strong>,<br />
University Press, Cambridge, 1999.<br />
[12] U. Pietsch, V. Holý, T. Baumbach: High-<br />
Resoluti<strong>on</strong> X-Ray Scattering – From Thin Films<br />
to Lateral Nanostructures, Springer, Berlin,<br />
2004.<br />
[13] H.-D. Männling, D.S. Patil, K. Moto, M. Jílek, S.<br />
Veprek, Surf. Coat. Technol. 146 (2001) 263.<br />
[14] A.E. Santana, A. Karimi, V.H. Derflinger, A.<br />
Schutze, Thin Solid Films 469 (2004) 339.<br />
[15] A. Hörling, L. Hultman, M. Odén, J. Sjölén, L.<br />
Karlss<strong>on</strong>, Surf. Coat. Technol. 191 (2005) 384.<br />
[16] A. Flink, T. Larss<strong>on</strong>, J. Sjölen, L. Karlss<strong>on</strong>, L.<br />
Hultman, Surf. Coat. Technol. 200 (2005) 1535.<br />
[17] D. Rafaja, M. Dopita, M. Růžička, V. Klemm, D.<br />
Heger, G. Schreiber, M. Šíma, Surf. Coat. Technol.<br />
201 (2006) 2835-2843.<br />
[18] D.B. Williams, C.B. Carter: Transmissi<strong>on</strong> Electr<strong>on</strong><br />
Microscopy III – Imaging, Plenum Press,<br />
New York, 1996.<br />
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