PHASE EQUILIBRIA IN SYSTEMS INVOLVING THE RARE-EARTH OXIDES. PART I. POLYMORPHISM OF THE OXIDES OF THE TRIVALENT RARE-EARTH IONS

Journal Article · Fri Jul 01 04:00:00 EDT 1960 · J. Research Natl. Bur. Standards

DOI:https://doi.org/10.6028/jres.064A.030· OSTI ID:4172966

Roth, R S; Schneider, S J

The polymorphic relationships of the pure rare-earth oxides were reinvestigated usirg 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/sub 2/O/sub 3/, Ce/ sub 2/C/sub 3/, Pr,O/sub 3/, and Nd/sub 2/C/sub 3/ belong to the A type; Sm/sub 2/ )/sub 3/ Eu/sub 2.O/sub 3/, and Gd/sub 2/0/sub 3/ to the B type; Tb/sub 2/,0/sub 3/, Dy/sub 2/O/sub 3/ Ho/sub 2/Cl, Er/sub 2/C/sub 3/, Tm/sub 2/O/sub 3/, Yb/sub 2/ O/sub 3/, and Lu/sub 2/O/sub 3/ to the C type. In addition Nd/sub 2/O/sub 3/, Sm/ sub 2/, C/sub 2/, Eu/sub 2/O/sub 0/, and Gd/su b 2/O/sub 3/ have lowtemperature, apparently metastable, C-type polymorphs. The low-temperature form inverts irreversibly to the stable form at increasingly higher temperatures for decreasing cation radius. (auth)

• Research Organization: Originating Research Org. not identified
• Sponsoring Organization: USDOE
• NSA Number: NSA-14-021465
• OSTI ID: 4172966
• Journal Information: J. Research Natl. Bur. Standards, Journal Name: J. Research Natl. Bur. Standards Vol. Vol: 64A
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ALLOTROPY
BEHAVIOR
CERIUM OXIDES
CHEMISTRY
DIFFRACTION
DYSPROSIUM OXIDES
ERBIUM OXIDES
EUROPIUM OXIDES
GADOLINIUM OXIDES
HOLMIUM OXIDES
LANTHANUM OXIDES
LOW TEMPERATURE
LUTETIUM OXIDES
NEODYMIUM OXIDES
OXIDES
PHASE DIAGRAMS
PRASEODYMIUM OXIDES
RARE EARTHS
SAMARIUM OXIDES
TERBIUM OXIDES
THULIUM OXIDES
X RADIATION
YTTERBIUM OXIDES