Synthesis and atomic structure of pyrochlore-type Yb/sub 2/Ge/sub 2/O/sub 7/ crystals

Journal Article · Tue Nov 01 00:00:00 EST 1988 · J. Struct. Chem. (Engl. Transl.); (United States)

OSTI ID:5833868

Dem'yanets, L N; Radaev, S F; Mamin, B F; Maksimov, B A

The pyrochlore-type compound Yb/sub 2/Ge/sub 2/O/sub 7/ was obtained by hydrothermal synthesis in studying crystallization in the system Yb/sub 2/O/sub 3/-GeO/sub 2/-KF-H/sub 2/O. In contrast to most analogous rare-earth systems, in the present system, i.e., the pyrogermanate Ln/sub 2/Ge/sub 2/O/sub 7/ (Ln = Yb), there are two polymorphic modifications: tetragonal (L/sub 2/) and cubic (F). The L/sub 2/ region occupies a large part of the diagram. The F boundaries are much narrower, i.e., L/sub 2/ overlaps F with rising KF content and excess germanium dioxide in the system. The x-ray diffraction studies involved a crystal of Yb/sub 2/Ge/sub 2/O/sub 7/ /mu/ = 557 cm/sup /minus/1/ rolled to a /O/ 0.18 mm sphere. Extinction patterns of hkO (h + k = 2n + 1) and h00 (h = 4n + 1) uniquely fixed the Fd3m Fedorov group which, like a sequential analysis of the Patterson function, again confirmed the compound studied to have a pyrochlore structure.

• OSTI ID: 5833868
• Journal Information: J. Struct. Chem. (Engl. Transl.); (United States), Vol. 29:3; Other Information: Translated from Zh. Strukt. Khim.; 29: No. 3, 150-152(May-Jun 1988)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
GERMANIUM OXIDES
STRUCTURAL CHEMICAL ANALYSIS
YTTERBIUM OXIDES
BOND ANGLE
BOND LENGTHS
CRYSTAL LATTICES
CRYSTALLIZATION
INTERATOMIC DISTANCES
LATTICE PARAMETERS
MOLECULAR STRUCTURE
PATTERSON METHOD
PHASE DIAGRAMS
PYROCHLORE
X-RAY DIFFRACTION
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIAGRAMS
DIFFRACTION
DIMENSIONS
DISTANCE
GERMANIUM COMPOUNDS
LENGTH
MINERALS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RARE EARTH COMPOUNDS
SCATTERING
YTTERBIUM COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies
400201 - Chemical & Physicochemical Properties