Structure and stability of the low-temperature modification compounds Cs[sub 3]LnCl[sub 6] (Ln = La-Gd)

Journal Article · Mon Nov 01 00:00:00 EST 1993 · Journal of Solid State Chemistry; (United States)

DOI:https://doi.org/10.1006/jssc.1993.1318· OSTI ID:7072220

Seifert, H J; Fink, H ^[1]; Baumgartner, B ^[2]

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1. Univ. Gh Kassel (Germany)
2. Fa, Stoe, Darmstadt (Germany)

The crystal structure of the low-temperature modification of Cs[sub 3]LaCl[sub 6] has been determined from X-ray powder diffraction data by the Rietveld method. The monoclinic lattice with a = 27.286(5) [angstrom]; b = 8.291(1) [angstrom]; c = 13.305(2) [angstrom]; [beta] = 99.64(1)[degrees] belongs to the Cs[sub 3]BiCl[sub 6]-type (space group C2/c). All other compounds Cs[sub 3]LnCl[sub 6] (Ln = Gd) and the analogous Rb-compounds are isotypic. Emf measurements in a galvanic cell for solid electrolytes for the reactions CsCl + Cs[sub 2]LnCl[sub 5] = Cs[sub 3]LnCl[sub 6] reveal that the compounds with Ln = La,Ce,Pr,Nd are formed with a loss of lattice enthalpy, compensated by a considerable gain in entropy; they therefore are stable only at temperatures higher than O K. The compounds with Ln = Sm,Eu,Dg are formed with a gain in lattice enthalpy and are stable at T = OK, too. This difference is attributed to the different crystal structures of the neighboring compounds Cs[sub 2]LnCl[sub 5]: they crystallize with the K[sub 2]PrCl[sub 5]-structure (CN = 7 for Ln[sup 3+]) for the compounds with Ln = La-Nd, while the other compounds belong to the Cs[sub 2]DyCl[sub 5]-type with octahedral surroundings for the Ln[sup 3+] ions.

• OSTI ID: 7072220
• Journal Information: Journal of Solid State Chemistry; (United States), Vol. 107:1; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
CERIUM CHLORIDES
STABILITY
CESIUM CHLORIDES
EUROPIUM CHLORIDES
GADOLINIUM CHLORIDES
LANTHANUM CHLORIDES
NEODYMIUM CHLORIDES
PRASEODYMIUM CHLORIDES
PROMETHIUM CHLORIDES
SAMARIUM CHLORIDES
CRYSTAL STRUCTURE
LATTICE PARAMETERS
MONOCLINIC LATTICES
X-RAY DIFFRACTION
ALKALI METAL COMPOUNDS
CERIUM COMPOUNDS
CESIUM COMPOUNDS
CHLORIDES
CHLORINE COMPOUNDS
COHERENT SCATTERING
CRYSTAL LATTICES
DIFFRACTION
EUROPIUM COMPOUNDS
GADOLINIUM COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
LANTHANUM COMPOUNDS
NEODYMIUM COMPOUNDS
PRASEODYMIUM COMPOUNDS
PROMETHIUM COMPOUNDS
RARE EARTH COMPOUNDS
SAMARIUM COMPOUNDS
SCATTERING
400201* - Chemical & Physicochemical Properties
360602 - Other Materials- Structure & Phase Studies