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Aem Investigation of Tetrahedrally Coordinated TI4+ in Nickel-Titanate Spinel

Published online by Cambridge University Press:  21 February 2011

Ian M. Anderson ,
Jim Bentley  and
C. Barry Carter
Ian M. Anderson
Affiliation:
Oak Ridge National Laboratory, Metals and Ceramics Division, P.O. Box 2008, M.S. 6376, Oak Ridge, TN 37831-6376 University of Minnesota, Department of Chemical Engineering and Materials Science, 421 Washington Ave. S.E., Minneapolis, MN 55455-0132
Jim Bentley
Affiliation:
Oak Ridge National Laboratory, Metals and Ceramics Division, P.O. Box 2008, M.S. 6376, Oak Ridge, TN 37831-6376
C. Barry Carter
Affiliation:
University of Minnesota, Department of Chemical Engineering and Materials Science, 421 Washington Ave. S.E., Minneapolis, MN 55455-0132
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Abstract

The stoichiometry and site distribution of metastable nickel-titanate spinel has been studied with AEM. The results of EDXS and EELS agree that the metastable spinel is nonstoichiometric and titanium-deficient relative to its hypothetical endmember composition, “Ni2TiO4”. The titanium deficiency has been determined by EELS to be Δ = 0.025 ± 0.005. Channeling-enhanced microanalysis and ELNES studies indicate that the Ti4+ and Ni2+ cations are in tetrahedral and octahedral coordination, respectively, so that the metastable spinel has the normal cation distribution: Til−Δ[Ni2(1+Δ)]O4. This result is consistent with neutron powder-diffraction studies and SiO2-solubility measurements of similar equilibrated and quenched spinel-containing specimens. Metastable nickel-titanate spinel therefore contrasts with stable stoichiometric spinels which tend to the inverse cation distribution, Me[MeTi]O4.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 332: Symposium U – Determining Nanoscale Physical Properties of Materials by Microscopy and Spectroscopy , 1994 , 309
Copyright
Copyright © Materials Research Society 1994

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