Phase Equilibria in Systems Involving the Rare-Earth Oxides. Part I. Polymorphism of the Oxides of the Trivalent Rare-Earth Ions

The polymorphic relationships of the pure rare-earth oxides have been reinvestigated using X-ray diffraction methods for identification of phases. The oxides of the trivalent rare earth ions crystallize in three different types: A, B, and C. Each oxide has only one truly stable polymorph: La(2)O(3),...

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Autores principales: Roth, R. S., Schneider, S. J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: [Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology 1960
Materias:
Article
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5287085/
https://www.ncbi.nlm.nih.gov/pubmed/32196170
http://dx.doi.org/10.6028/jres.064A.030
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author Roth, R. S.
Schneider, S. J.
author_facet Roth, R. S.
Schneider, S. J.
author_sort Roth, R. S.
collection PubMed
description The polymorphic relationships of the pure rare-earth oxides have been reinvestigated using X-ray diffraction methods for identification of phases. The oxides of the trivalent rare earth ions crystallize in three different types: A, B, and C. Each oxide has only one truly stable polymorph: La(2)O(3), Ce(2)O(3), Pr(2)O(3), and Nd(2)O(3) belong to the A type; Sm(2)O(3), Eu(2)O(3), and Gd(2)O(3) to the B type; Tb(2)O(3), Dy(2)O(3), Ho(2)O(3), Er(2)O(3), Tm(2)O(3), Yb(2)O(3), and Lu(2)O(3) to the C type. In addition Nd(2)O(3), Sm(2)O(3), Eu(2)O(3), and Gd(2)O(3) have low-temperature, apparently metastable, C-type polymorphs. The low-temperature form inverts irreversibly to the stable form at increasingly higher temperatures for decreasing cation radius.
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spelling pubmed-52870852020-03-18 Phase Equilibria in Systems Involving the Rare-Earth Oxides. Part I. Polymorphism of the Oxides of the Trivalent Rare-Earth Ions Roth, R. S. Schneider, S. J. J Res Natl Bur Stand A Phys Chem Article The polymorphic relationships of the pure rare-earth oxides have been reinvestigated using X-ray diffraction methods for identification of phases. The oxides of the trivalent rare earth ions crystallize in three different types: A, B, and C. Each oxide has only one truly stable polymorph: La(2)O(3), Ce(2)O(3), Pr(2)O(3), and Nd(2)O(3) belong to the A type; Sm(2)O(3), Eu(2)O(3), and Gd(2)O(3) to the B type; Tb(2)O(3), Dy(2)O(3), Ho(2)O(3), Er(2)O(3), Tm(2)O(3), Yb(2)O(3), and Lu(2)O(3) to the C type. In addition Nd(2)O(3), Sm(2)O(3), Eu(2)O(3), and Gd(2)O(3) have low-temperature, apparently metastable, C-type polymorphs. The low-temperature form inverts irreversibly to the stable form at increasingly higher temperatures for decreasing cation radius. [Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology 1960 1960-08-01 /pmc/articles/PMC5287085/ /pubmed/32196170 http://dx.doi.org/10.6028/jres.064A.030 Text en https://creativecommons.org/publicdomain/zero/1.0/ The Journal of Research of the National Bureau of Standards Section A is a publication of the U.S. Government. The papers are in the public domain and are not subject to copyright in the United States. Articles from J Res may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright.
spellingShingle Article
Roth, R. S.
Schneider, S. J.
Phase Equilibria in Systems Involving the Rare-Earth Oxides. Part I. Polymorphism of the Oxides of the Trivalent Rare-Earth Ions
title Phase Equilibria in Systems Involving the Rare-Earth Oxides. Part I. Polymorphism of the Oxides of the Trivalent Rare-Earth Ions
title_full Phase Equilibria in Systems Involving the Rare-Earth Oxides. Part I. Polymorphism of the Oxides of the Trivalent Rare-Earth Ions
title_fullStr Phase Equilibria in Systems Involving the Rare-Earth Oxides. Part I. Polymorphism of the Oxides of the Trivalent Rare-Earth Ions
title_full_unstemmed Phase Equilibria in Systems Involving the Rare-Earth Oxides. Part I. Polymorphism of the Oxides of the Trivalent Rare-Earth Ions
title_short Phase Equilibria in Systems Involving the Rare-Earth Oxides. Part I. Polymorphism of the Oxides of the Trivalent Rare-Earth Ions
title_sort phase equilibria in systems involving the rare-earth oxides. part i. polymorphism of the oxides of the trivalent rare-earth ions
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5287085/
https://www.ncbi.nlm.nih.gov/pubmed/32196170
http://dx.doi.org/10.6028/jres.064A.030
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