Structural chemistry and magnetic properties of the compounds EuOs/sub 4/B/sub 4/ and EuIr/sub 4/B/sub 4/ and of the solid solutions (RE)Os/sub 4/B/sub 4/-(RE)Ir/sub 4/B/sub 4/(RE = Ce, Pr, Sm)
- Cornell Univ., Ithaca, NY
New ternary metal borides, EuOs/sub 4/B/sub 4/ and EuIr/sub 4/B/sub 4/, have been synthesized from the elements. The compounds were found to crystallize with the structure type of NdCo/sub 4/B/sub 4/. Effective paramagnetic moments derived from chi/sup -1/vs. T plots over the range 1.8-800 K are in good agreement with theoretical values according to a Hund's rule ground-state /sup 8/S/sub 1/2/ for a free Eu/sup 2 +/ ion. Complete solid solution was found for mixed crystals of CeOs/sub 4/B/sub 4/-CeIr/sub 4/B/sub 4/ (arc melted, quenched, NdCo/sub 4/B/sub 4/-type structure) revealing a positive deviation from Vegard's law. Magnetic susceptibilities were determined for the temperature range 1.8-1000 K. At high temperature the magnetic properties are characterized by Van Vleck paramagnetism of closely spaced multiplets due to admixture of the excited term J = /sup 7///sub 2/ of the Ce/sup 3 +/F/sub 5///sub 2/ ground state. At lower temperatures the paramagnetic behavior of cerium changes from that of a practically pure Ce/sup 4 +/ state in CeOs/sub 4/B/sub 4/ (..mu../sub eff/ = 0.49 ..mu beta..) to that of a pronounced Ce/sup 3 +/ state in CeIr/sub 4/B/sub 4/ (..mu../sub eff/ = 2.21 ..mu beta..) presumably due to the larger iridium metal framework and/or the higher electron-to-atom ratio. At very low temperatures, less than or equal to 3.5 K, ferromagnetic ordering was observed for CeIr/sub 4/B/sub 4/ and CeIr/sub 3/Os/sub 1/B/sub 4/. For comparison, the magnetic behavior was studied over the range 1.5-300 K of the pseudobinary sections PrOs/sub 4-x/Ir/sub x/B/sub 4/ and SmOs/sub 4-x/Ir/sub x/B/sub 4/. Although a slight negative deviation from Vegard's law was observed, there was practically no change from a valence state of Sm/sup 3 +/ for samarium. On the basis of Miedema's model, a thermodynamic calculation for the valence change (Ce/sup III/ ..-->.. Ce/sup IV/, Eu/sup II/ ..-->.. Eu/sup III/) has been found to be in good accord with the magnetic behavior observed. 7 figures, 4 tables.
- OSTI ID:
- 5455832
- Journal Information:
- Inorg. Chem.; (United States), Vol. 21:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CERIUM BORIDES
LATTICE PARAMETERS
SOLID SOLUTIONS
EUROPIUM BORIDES
CRYSTAL STRUCTURE
MAGNETIC SUSCEPTIBILITY
IRIDIUM BORIDES
OSMIUM BORIDES
PRASEODYMIUM BORIDES
SAMARIUM BORIDES
ARGON
DIFFRACTION METHODS
EXPERIMENTAL DATA
HIGH TEMPERATURE
INERT ATMOSPHERE
INTERMETALLIC COMPOUNDS
LOW TEMPERATURE
MEDIUM TEMPERATURE
MELTING
METALLOGRAPHY
MIXTURES
NITROGEN
TEMPERATURE DEPENDENCE
ULTRALOW TEMPERATURE
VERY HIGH TEMPERATURE
VERY LOW TEMPERATURE
X-RAY DIFFRACTION
ALLOYS
BORIDES
BORON COMPOUNDS
CERIUM COMPOUNDS
COHERENT SCATTERING
DATA
DIFFRACTION
DISPERSIONS
ELEMENTS
EUROPIUM COMPOUNDS
FLUIDS
GASES
INFORMATION
MAGNETIC PROPERTIES
NONMETALS
NUMERICAL DATA
OSMIUM COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PRASEODYMIUM COMPOUNDS
RARE EARTH COMPOUNDS
RARE GASES
SAMARIUM COMPOUNDS
SCATTERING
SOLUTIONS
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties