RARE-EARTH POLYMORPHISM AND PHASE EQUILIBRIA IN RARE-EARTH OXIDE-WATER SYSTEMS

Journal Article · Sun Nov 01 04:00:00 EST 1959 · Journal of the American Ceramic Society (U.S.)

DOI:https://doi.org/10.1111/j.1151-2916.1959.tb13574.x· OSTI ID:4236973

Shafer, M W; Roy, R

A high-water-pressure high-temperature study was conducted of the systems Y/sub 2/O/sub 3/-H/sub 2/O, Sm/sub 2/O/sub 3/-H/sub 2/O, N d/sub 2/O/sub 3/-H/sub 2/O, and La/sub 2/O/sub 3/-- H/sub 2/O. The trihydroxides La(OH)/sub 3/ , Nd(OH)a, an d this group. On the other hand, the oxyhydroxides YOOH, SmOOH, and NdOOH are isomorphous; LaOOH, if it exists, cannot be stable in the presence of water at room temperature. Pressure-temperature curves for the equilibrium between the trinydroxide, oxyhydroxide, and a new hydroxy compoud were determined for each of the three smaller ions. The reversibility of the transition between the A-, B-, and C-type rare earths was established, and new x-ray data on the B structure are listed. Ths relations between the polymorphs as a function of ionic size are changed from those given by Goldschmidt. The very marked difference in stability in air between the A- and C-type structures suggests the obvious desirability of converting rareearth oxide cermnics into the C structure with proper compositional variation and thermal treatment. (auth)

• Research Organization: Pennsylvania State Univ., University Park
• Sponsoring Organization: USDOE
• NSA Number: NSA-14-002380
• OSTI ID: 4236973
• Journal Information: Journal of the American Ceramic Society (U.S.), Journal Name: Journal of the American Ceramic Society (U.S.) Vol. Vol: 42; ISSN JACTA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

AIR
ALLOTROPY
CERAMICS
CHEMISTRY
HEAT TREATMENTS
HIGH TEMPERATURE
LANTHANUM HYDROXIDES
LANTHANUM OXIDES
LATTICES
NEODYMIUM HYDROXIDES
NEODYMIUM OXIDES
OXIDES
PRESSURE
RARE EARTHS
SAMARIUM HYDROXIDES
SAMARIUM OXIDES
STABILITY
WATER
X RADIATION
YTTRIUM HYDROXIDES
YTTRIUM OXIDES