Preparation and crystal structure of superconducting Y/sub 2/FeC/sub 4/ and isotypic lanthanoid iron carbides

Journal Article · Tue Sep 01 04:00:00 EDT 1987 · J. Solid State Chem.; (United States)

DOI:https://doi.org/10.1016/0022-4596(87)90173-3· OSTI ID:5740805

Gerss, M H; Jeitschko, W; Boonk, L; Nientiedt, J; Moersen, E; Leson, A

The new compounds R/sub 2/FeC/sub 4/ (R = Y, Tb, Dy, Ho, Er, Tm, Yb, Lu) were prepared by arc melting of the elemental components. They are formed by a peritectic reaction of the carbides RC/sub 2/ with iron. Their crystal structure was determined from X-ray powder diffraction data for Tm/sub 2/FeC/sub 4/ and from neutron diffraction data for Er/sub 2/FeC/sub 4/. It is orthorhombic, space group Ibam with Z = 4 formula units per cell. The lattice constants for Er/sub 2/FeC/sub 4/ are a = 750.6(1) pm, b = 942.6(2) pm, c = 500.6(1) pm, V = 0.3542 nm/sup 3/. The residual for a Rietveld peak shape refinement of the Er/sub 2/FeC/sub 4/ neutron diffraction data is R = 0.024 (295 data and 14 variable parameters). The structure is of a new type with carbon pairs (bond distance 133 pm) in an environment of five rare earth atoms and two adjacent iron atoms. Hydrolysis with hydrochloric acid yields mainly C/sub 2/H/sub 6/, C/sub 2/H/sub 4/, and CH/sub 4/ with minor amounts (depending on the reaction temperature) of C/sub 3/H/sub 8/, C/sub 3/H/sub 6/, and C/sub 4/H/sub x/. Er/sub 2/FeC/sub 4/ is paramagnetic at room temperature. /sup 57/Fe Moessbauer spectra for Y/sub 2/FeC/sub 4/ and Er/sub 2/FeC/sub 4/ were measured at 295 and 4.2 K. The isomer shifts are in agreement with those for metallic iron. The quadrupole splittings reflect a previously unencountered distorted tetrahedral carbon coordination of the iron atoms. No indication for magnetic order above 4.2 K was obtained. Induction measurements show a transition to a superconducting state for Y/sub 2/FeC/sub 4/ at 3.6 K, while Lu/sub 2/FeC/sub 4/ does not become superconducting down to 1.8 K.

• Research Organization: Universitaet Muenster, Germany, F.R.
• OSTI ID: 5740805
• Journal Information: J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 70:1; ISSN JSSCB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
CARBIDES
CARBON COMPOUNDS
COHERENT SCATTERING
CRYSTAL GROWTH
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DATA
DIFFRACTION
DYSPROSIUM CARBIDES
DYSPROSIUM COMPOUNDS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ERBIUM CARBIDES
ERBIUM COMPOUNDS
EXPERIMENTAL DATA
HOLMIUM CARBIDES
HOLMIUM COMPOUNDS
HYPERFINE STRUCTURE
INFORMATION
IRON CARBIDES
IRON COMPOUNDS
LATTICE PARAMETERS
LUTETIUM CARBIDES
LUTETIUM COMPOUNDS
NEUTRON DIFFRACTION
NUMERICAL DATA
ORTHORHOMBIC LATTICES
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SCATTERING
SPACE GROUPS
SUPERCONDUCTIVITY
TERBIUM CARBIDES
TERBIUM COMPOUNDS
THULIUM CARBIDES
THULIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION
YTTERBIUM CARBIDES
YTTERBIUM COMPOUNDS
YTTRIUM CARBIDES
YTTRIUM COMPOUNDS