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Inhomogeneous distribution of Cr impurities in α–Al2O3 during refractory aging

Published online by Cambridge University Press:  31 January 2011

Laurence Galoisy
Affiliation:
Laboratoire de Minéralogie-Cristallographie, URA CNRS 09, Universités de Paris 6 et 7 et IPGP, 75252 Paris Cedex 05, France
Georges Calas
Affiliation:
Laboratoire de Minéralogie-Cristallographie, URA CNRS 09, Universités de Paris 6 et 7 et IPGP, 75252 Paris Cedex 05, France
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Abstract

Aged alumina refractories have been investigated by EPR (Electron Paramagnetic Resonance) and EPMA (Electron Probe Micro-Analysis). EPMA shows that Cr is homogeneously distributed inside the corundum grains within spatial resolution (1 μm). Cr3+ concentration at the atomic scale is obtained by EPR by the magnitude of dipolar broadening due to Cr-Cr interactions. This local concentration appears to be systematically higher (up to a factor of 10) than the average chromium content of the corundum crystals determined by EPMA. Cr3+ ions may be preferentially concentrated at the vicinity of extended lattice defects which help in accommodating the lattice strain due to the size difference between Al3+ and Cr3+ cations. A random location of these defects explains the apparent homogeneous chromium distribution found by EPMA in these aged refractories.

Type
Articles
Copyright
Copyright © Materials Research Society 1993

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References

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