Cylindrical specimen, 2θ scan

Parrish, W.; Langford, J. I.

doi:10.1107/97809553602060000578

International
Tables for
Crystallography
Volume C
Mathematical, physical and chemical tables
Edited by E. Prince

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International Tables for Crystallography (2006). Vol. C. ch. 2.3, pp. 57-58

Section 2.3.2.2. Cylindrical specimen, 2θ scan

W. Parrish^a ^‡ and J. I. Langford^b

^a IBM Almaden Research Center, San Jose, CA, USA, and ^bSchool of Physics & Astronomy, University of Birmingham, Birmingham B15 2TT, England

2.3.2.2. Cylindrical specimen, 2θ scan

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The flat specimen can be replaced by a thin cylindrical [Fig. 2.3.2.4(c)] specimen as used in powder cameras. The powder can be coated on a thin fibre or reactive materials can be forced into a capillary to avoid contact with air. The intensity is lower than for flat specimens because of the smaller beam, and less powder is required. Thompson, Cox & Hastings (1987) used the method to determine the structure of Al₂O₃ by Rietveld refinement. They used a two-crystal incident-beam Si(111) monochromator; the first crystal was flat and the second a cylindrically bent triangular plate for sagittal focusing to form a $[4 \times 2]$ mm beam with spectral bandwidth $[\Delta\lambda/\lambda \simeq 10^{-3}]$ .

The method can also be used with a receiving slit or position-sensitive detectors (Lehmann et al., 1987; Shishiguchi, Minato & Hashizume, 1986). The latter can be a short straight detector, which can be scanned to increase the data-collection speed (Göbel, 1982), or a longer curved detector.

References

Göbel, H. E. (1982). A Guinier diffractometer with a scanning position sensitive detector. Adv. X-ray Anal. 25, 315–324.Google Scholar

Lehmann, M. S., Christensen, A. N., Fjellvåg, H., Feidenhans'l, R. & Nielsen, M. (1987). Structure determination by use of pattern decomposition and the Rietveld method on synchrotron X-ray and neutron powder data; the structures of Al₂Y₄O₉ and I₂O₄. J. Appl. Cryst. 20, 123–129.Google Scholar

Shishiguchi, S., Minato, I. & Hashizume, H. (1986). Rapid collection of X-ray powder data for pattern analysis by a cylindrical position-sensitive detector. J. Appl. Cryst. 19, 420–426.Google Scholar

Thompson, P., Cox, D. E. & Hastings, J. B. (1987). Rietveld refinement of Debye–Scherrer synchrotron X-ray data from Al₂O₃. J. Appl. Cryst. 20, 79–83.Google Scholar

International Tables for Crystallography (2006). Vol. C. ch. 2.3, pp. 57-58