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Structural characterization of a coarse-grained transparent silicon carbide powder by a combination of powder diffraction techniques

Burkhard Peplinski 1Andy Fitch 2Alexander Evans 2Richard M. Ibberson 3Daniel M. Többens 4,5Lachlan M. Cranswick 6Ilona Dörfel 1Franziska Emmerling 1Ralf Matschat 1

1. Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, Berlin D-12489, Germany
2. European Synchrotron Radiation Facility (ESRF), Grenoble 38043, France
3. ISIS Facility, Rutherford Appleton Laboratory (ISIS), Oxon, Chilton Didcot OX110QX, United Kingdom
4. Hahn-Meitner-Institute (HMI), Glienicker Str. 100, Berlin D-14109, Germany
5. Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52, Innsbruck A-6020, Austria
6. Chalk River Laboratories, NRC, Chalk River ON K0J1J0, Canada


Silicon carbide powders having extremely low levels of chemical impurities (a few μg per g or even less), high perfection of the crystalline lattice and a grain size of up to a hundred μm show exceptional chemical resistance (insolubility in any kind of acid), high hardness as well as unique electronic and optical properties.

Along with the lack of reliable analytical techniques for the quantitative determination of chemical trace impurities in such materials, their structural characterization is very challenging, too. One of the main problems is the considerable discrepancy between the actual grain size of the coarse-grained SiC powder samples and the ideal size for powder diffraction measurements. Any grinding bears a high risk of changing/destroying the original real structure characteristics of the sample, e.g. the degree of stacking disorder and the polytype composition. Thus, grinding can significantly distort the outcome of the structural investigation and, therefore, should be avoided.

In an attempt to characterize the structural properties of such a material as fully as possible powder diffraction data of a large number of samples were collected applying conventional X-ray diffractometry (Bragg-Brentano geometry), constant-wavelength neutron diffractometry, time-of-flight neutron diffractometry and finally synchrotron radiation (SR) diffractometry at a dedicated beamline. All neutron and SR diffraction measurements were carried out on capillary specimens. Data evaluation was carried out with the program packages TOPAS, GSAS and FULLPROF.

The present investigation demonstrates how the specific strengths of each of these four non-destructive powder diffraction techniques complete each other very nicely. Their results go together with the outcome of a TEM investigation for which individual grains of the powder sample were thinned into 100 nm thick slices by the focused ion beam (FIB) sample preparation technique.

Section of the high-resolution powder diffraction pattern of a coarse-grained transparent silicon carbide powder sample collected with synchrotron radiation at the ESRF beam-line ID31 (λ = 0.050 nm)


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Related papers

Presentation: Poster at 11th European Powder Diffraction Conference, Poster session, by Burkhard Peplinski
See On-line Journal of 11th European Powder Diffraction Conference

Submitted: 2008-04-30 10:27
Revised:   2009-06-07 00:48