Preparation, phase equilibria, and crystal chemistry of lanthanum, praseodymium, and neodymium hydroxide chlorides

Journal Article · Sat Jan 31 23:00:00 EST 1976 · J. Solid State Chem.; (United States)

DOI:https://doi.org/10.1016/0022-4596(76)90201-2· OSTI ID:7355369

Lance, E T; Haschke, J M

The preparation of hydroxide chlorides of lanthanum, praseodymium, and neodymium has been achieved by hydrothermal methods at 550/sup 0/C and 1530 atm. Three phases (Ln(OH)/sub 3/, Ln(OH)/sub 2/./sub 55/-Cl/sub 0/./sub 45/, and Ln(OH)/sub 2/Cl) have been characterized by analytical and x-ray methods. The observed compositions are closely defined by the x = 0, 0.5, and 1 members of the homologous anion substitution series, Ln(OH)/sub 3-x/Cl/sub x/. The previously unreported Ln(OH)/sub 2/./sub 55/Cl/sub 0/./sub 45/ phases are clearly substoichiometric in chloride and are described by the Ln/sub 7/(OH)/sub 18/Cl/sub 3/ composition. X-ray diffraction data for the phases at x = 0.45 show a pronounced UCl/sub 3/-type substructure and complex superstructure reflections that have been indexed on a hexagonal cell. For the lanthanum phase, a = 17.662 (6) and c = 3.914(1) A. Efforts to obtain single crystals have been unsuccessful. Thermal decomposition processes of the hydroxide chlorides have been investigated, and the characterization of LaO(OH)/sub 0/./sub 55/Cl/sub 0/./sub 45/, a monoclinic YOOH-type intermediate phase, is reported. Structural features and phase equilibria of the hydroxide chlorides are discussed and analogies with the hydroxide nitrate systems are drawn.

• Research Organization: Univ. of Michigan, Ann Arbor
• OSTI ID: 7355369
• Journal Information: J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 17:1-2; ISSN JSSCB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DECOMPOSITION
DIFFRACTION
HALIDES
HALOGEN COMPOUNDS
HIGH TEMPERATURE
HYDROGEN COMPOUNDS
HYDROXIDES
LANTHANUM COMPOUNDS
NEODYMIUM COMPOUNDS
OXYGEN COMPOUNDS
PHASE STUDIES
PRASEODYMIUM COMPOUNDS
PYROLYSIS
RARE EARTH COMPOUNDS
SCATTERING
STOICHIOMETRY
SYNTHESIS
VERY HIGH PRESSURE
X-RAY DIFFRACTION