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Lattice Thermal Expansion Effects in Pure and Doped Cordierite by Time-of-Flight Neutron Diffraction*

Published online by Cambridge University Press:  06 March 2019

F. K. Predecki
Affiliation:
University of Denver, DenverCO 80208
J. Haas
Affiliation:
University of Denver, DenverCO 80208
J. Faber Jr.
Affiliation:
Argonne National Laboratory, ArgonneIL 60439
R. L. Hitterman
Affiliation:
Argonne National Laboratory, ArgonneIL 60439
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Abstract

The thermal expansion behavior of pure, Ge-doped and Li-doped hexagonal cordierites with respective compositions: 2MgO 2Al2O3 5Si02 2Mg0 2Al2O3 4Si02 Ge02) and 2MgO (2+x)AL203 (5-2x)Si02 xLi20 with x = .174, was investigated using time-of-flight neutron powder diffraction at temperatures from 22 to 750°C in vacuum. The data were refined in space group P6/mcc using the Rietveld method. The lattice thermal expansion curves of all 3 samples were quite similar. The negative axis expansion is associated with (1)displacement of the T2 cations generally toward the axis channels and (2) changes in the distortion of the coupled T1/M tetrahedra/octahedra in the structure. Both contributions were present in all 3 samples but the first was more dominant in the Ge doped sample. The nature and origin of the distortions in T1 and M are discussed.

Type
Research Article
Copyright
Copyright © International Centre for Diffraction Data 1985

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Footnotes

*

Work supported by Division of Basic Energy Sciences, DOE, Washington, D.C. on grant # DE-FG02-84ER45053,

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