Ordering in HfO/sub 2/-Ln/sub 2/O/sub 3/ systems where Ln is Dy, Er, or Yb
Journal Article
·
· High Temp. Sci.; (United States)
OSTI ID:6233050
The regions in which high temperature solid solutions based on HfO/sub 2/ and Ln/sub 2/O/sub 3/ (Ln = Dy, Er, and Yb) exist were determined using the lattice parameter method. At low temperature, long-range ordering occurred at 40 mol % Ln/sub 2/O/sub 3/ (Ln = Dy, Er and Yb), and the corresponding ordered phases were Hf/sub 3/Er/sub 4/O/sub 12/ and Hf/sub 3/Yb/sub 4/O/sub 12/, respectively. These compounds have rhombohedral symmetry, are isostructural with UY/sub 6/O/sub 12/, and decompose above 1500 and 1700/sup 0/C, respectively, into solid solutions of the fluorite type. No evidence for ordering phenomena was found in the HfO/sub 2/-Dy/sub 2/O/sub 3/ system for the same composition. At high Ln/sub 2/O/sub 3/, content another compound, also with rhombohedral symmetry, was found in all of the three systems. The corresponding ordered phases were of the Ln/sub 6/HfO/sub 11/ type. This compound is formed within the Ln/sub 2/O/sub 3/ concentration range between 70 and 90 mol % Ln/sub 2/O/sub 3/. Above 1700/sup 0/C, this compound undergoes a transformation into a cubic solid solution of C-type. In the case of the HfO/sub 2/-Dy/sub 2/O/sub 3/ system, another hexagonal compound of an M/sub 7/O/sub 11/ /sub 5/-type was found. This is formed at about 55 mol % Dy/sub 2/O/sub 3/ and possesses a very narrow homogeneity range. At approximately 1750/sup 0/C this compound undergoes a transformation into cubic solid solutions of fluorite and C-type. 5 figures, 7 tables.
- Research Organization:
- Instituto de Ceramica y Vidrio, Madrid, Spain
- OSTI ID:
- 6233050
- Journal Information:
- High Temp. Sci.; (United States), Journal Name: High Temp. Sci.; (United States) Vol. 13:1; ISSN HITSA
- Country of Publication:
- United States
- Language:
- English
Similar Records
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Journal Article
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Sat Dec 31 23:00:00 EST 1977
· J. Am. Ceram. Soc.; (United States)
·
OSTI ID:6427150
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Journal Article
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Fri Oct 01 00:00:00 EDT 1976
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Journal Article
·
Thu Feb 29 23:00:00 EST 1996
· Journal of the American Ceramic Society
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OSTI ID:230745
Related Subjects
36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
CHALCOGENIDES
COHERENT SCATTERING
DIFFRACTION
DISPERSIONS
DYSPROSIUM COMPOUNDS
DYSPROSIUM OXIDES
ERBIUM COMPOUNDS
ERBIUM OXIDES
HAFNIUM COMPOUNDS
HAFNIUM OXIDES
LATTICE PARAMETERS
MIXTURES
ORDER-DISORDER TRANSFORMATIONS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RARE EARTH COMPOUNDS
SCATTERING
SOLID SOLUTIONS
SOLUTIONS
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION
YTTERBIUM COMPOUNDS
YTTERBIUM OXIDES
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
CHALCOGENIDES
COHERENT SCATTERING
DIFFRACTION
DISPERSIONS
DYSPROSIUM COMPOUNDS
DYSPROSIUM OXIDES
ERBIUM COMPOUNDS
ERBIUM OXIDES
HAFNIUM COMPOUNDS
HAFNIUM OXIDES
LATTICE PARAMETERS
MIXTURES
ORDER-DISORDER TRANSFORMATIONS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RARE EARTH COMPOUNDS
SCATTERING
SOLID SOLUTIONS
SOLUTIONS
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION
YTTERBIUM COMPOUNDS
YTTERBIUM OXIDES