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Thermal Expansion Behavior of Pure and Doped Cordierite by Time-of-Flight Neutron Diffraction

Published online by Cambridge University Press:  06 March 2019

J. Haas
Affiliation:
University of Denver, Denver, CO 80208
Paul Predecki
Affiliation:
University of Denver, Denver, CO 80208
J. Faber Jr.
Affiliation:
Argonne National Lab, Argonne, IL 60439
R. L. Hitterman
Affiliation:
Argonne National Lab, Argonne, IL 60439
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Abstarct

In order to reveal the mechanism of the negative c-axis expansion in cordierite (4 MgO 4 Al2O3 10 SiO2), the thermal expansion of cordierite containing small amounts of Cs, Li, B, Ge, Sc and Ni-cations was investigated by time-of-flight neutron diffraction at temperatures between 22 and 750°C. The samples were prepared by melting the constituent oxides followed by quenching and devitrification to obtain the hexagonal form (Indialite). Using the neutron powder diffraction data, the atom positions in the space group P6/mcc were refined by Rietveld least squares analyses.

The expansion behavior of the cordierite structure could be explained in terms of the various kinds of constraints and the interatomic bond strengths of the structure. It was found that cordierite doped with Cs-cations shows the largest volume expansion, followed by the Li-doped sample. So-doped cordierite has the lowest volume expansion. All cordierite samples show positive expansion along the a-axis and negative expansion along the c-axis, except the Cs-doped sample which has positive expansion in both directions.

Type
VII. Synchrotron and Neutron Diffraction
Copyright
Copyright © International Centre for Diffraction Data 1986

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Footnotes

*

Work supported by Division of Basic Energy Sciences, DOE, Washington, D.C., on grant #DE-FG02-84ER45053. One of the authors (JF) also acknowledges support of the U.S. DOE, BES-Materials Sciences, under contract W-31-109-Eng-38.

References

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2. Predecki, F.K., Haas, J., Faber, J. Jr., and Hitterman, R.L., “Lattice Thermal Expansion Effects in Pure and Doped Cordierite by Time-of- Flight Neutron Diffraction”, advances in X-ray Analysis, Vol. 29, p. 173184 (1986).Google Scholar
3. Robinson, K., Gibbs, G.V. and Bibbe, P.H., “Quadratic Elongation: A Quantitative Measure of Distortion in Coordination Polyhedra,“ Science 172: 567 (1971).Google Scholar
4. Haas, J., “Mechanism of Lattice Thermal Expansion in Pure and Doped Cordierite”, M. S. Thesis, Physics Dept., University of Denver, Denver, CO. (1986)Google Scholar