Ternary carbides Ln/sub 2/Mn/sub 17/C/sub 3-x/ (Ln = La, Ce, Pr, Nd, Sm) with filled Th/sub 2/Zn/sub 17/ type structure
The new title compounds were prepared by reaction of the elemental components at high temperatures. They crystallize with a rhombohedral cell in space group R 3m. The structure was determined for Pr/sub 2/Mn/sub 17/C/sub 3-x/ (x = 1.23), which has the lattice constants a = 8.8714 (7) A and c = 12.783 (2) A with Z = 3 formula units in the hexagonal setting of the cell. The structure refinement from single-crystal X-ray data resulted in a residual of R = 0.023 for 25 variable parameters and 414 unique structure factors. The Pr and Mn positions correspond to those of the Th and Zn positions in Th/sub 2/Zn/sub 17/. The carbon atoms fill voids of nearly octahedral shape formed by a rectangle of Mn atoms (Mn-C distances 1.94 and 1.95 A) and two Pr atoms at 2.57 A. The idealized composition with all octahedral voids filled is Pr/sub 2/Mn/sub 17/C/sub 3/. The refinement of the occupancy parameter for this position resulted in a value of 59 +/- 3% for the crystal used for the structure determination. The discussion reviews the correspondence of binary intermetallic and ternary complex carbide phases. 28 references, 2 figures, 5 tables.
- Research Organization:
- Univ. of Muenster, West Germany
- OSTI ID:
- 5819210
- Journal Information:
- Inorg. Chem.; (United States), Vol. 25:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CERIUM COMPLEXES
CHEMICAL PREPARATION
CRYSTAL STRUCTURE
LANTHANUM COMPLEXES
MANGANESE CARBIDES
NEODYMIUM COMPLEXES
PRASEODYMIUM COMPLEXES
SAMARIUM COMPLEXES
BOND ANGLE
BOND LENGTHS
EXPERIMENTAL DATA
HIGH TEMPERATURE
LATTICE PARAMETERS
VERY HIGH TEMPERATURE
CARBIDES
CARBON COMPOUNDS
COMPLEXES
DATA
DIMENSIONS
INFORMATION
LENGTH
MANGANESE COMPOUNDS
NUMERICAL DATA
RARE EARTH COMPLEXES
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication
360202 - Ceramics
Cermets
& Refractories- Structure & Phase Studies