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1
Synthesis and Crystallization of TernaryUranium Transition Metal Chalcogenides
Danielle DeCicco
Northwestern University
Adam Raw
George OhLuc KoscielskiMatt WardDr. Jim Ibers
August 13, 2010 [www.esslab.com/iv/elements]
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This presentation covers a few topics including:
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Background on Uranium1
Synthesis
1. [www.whatisnuclear.com]
Characterization
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According to the US Environmental Protection Agency,nineteen percent of electricity comes from nuclear power.
[papundits.files.wordpress.com/2009/04]
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What if we could turn the uranium waste into somethingmore useful?
[www.treehugger.com]
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One of the simplest ternary uranium chalcogenides is acompound with the structure AMQ3
Chalcogenides : Q= S, Se, Te
Metal: M= any 2+ transitionmetal to charge balance
For Example: UNiS3
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Ternary: 3 elements in thecompound
UNi
S
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There are different methods for solid state crystal growth
Crystal Growth Methods- Low Melting Salts (NaCl/CsCl)
- Provide liquid medium
- Promote nucleation and growth
- Reactive Flux (Cs2Se3)- Elements from the flux can
incorporate into product
- Vapor Transport (I2, TeCl4)
- Crystal Growth agents (Sb2S3)- Low melting inorganic compounds
- Molten Metals (Ga, Pb)
Remaining sodium
chloride after reaction
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The type of procedure implemented includes 5 steps
1. Gather starting materials (elements,binaries, fluxes etc)
2. Use a mortar and pestle to grind and
have the elements associate3. Seal reactant under vacuum in fused
silica tubes
4. Place them in a furnace using a heatingprofile based on the flux melting point
5. Slow cool to promote crystal growth
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Exploratory Reactions in pursuit of UMS3 type compounds:
Co + U + 3S US2 + CoSNi + U + 3SUNiS3Ti + U + 3S US2 + TiS
CoS + US2 CoS + US2
NiS + US2 NiS + US2ZnS + US2 ZnS + US2
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0 C
900 C 900 C
600 C
20 C
0 12 180 280 285
Heating Profile
Hours
3 C/Hr
A majority of these reactions simply produced thebinaries.
NiS + US2 + CsCl UNiS3
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X Ray Powder Diffraction of UNiS3:
9 [Noel, Padious, Prigent. C. R. Acad. Sc. Paris, t. 272. Jan 11 1971]
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Using Uranium Selenide, syntheses were attempted usingNaCl as a flux. The same reactions were also attemptedusing Sb
2
Se3
as a flux and the same heating profile.
Co + Se + USe2 + NaCl no reaction
Ni + Se + USe2+ NaCl NiSe + USe2Zn + Se + USe2 + NaCl no reaction
Nb + Se + USe2 + NaCl no reaction
V + Se + USe2 + NaCl USe2 + VSe
Cd + Se + USe2 + NaCl CdSe +USe2
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0 C
900 C 900 C
600 C
20C
0 12 180 230 235
Heating Profile
Some more reactions using Uranium Sulfide:
NbS2 + US2+ NaCl
V2S3 + US2 + NaCl
CdS + US2 + NaCl
NbS2 + US2+ Sb2S3
V2S3 + US2 + Sb2S3
CdS + US2 + Sb2S3
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6 C/Hr
Hrs
These reactions did not crystallize ternaryproducts, but addition of CsCl to the previouslysynthesized powders resulted in crystals of UNiS3
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Using a number of characterization techniques, such asXRD and SEM/EDS, the products were analyzed. Crystals ofthe ternary compound UNiS
3
were grown as were binaries.
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US2 crystalsOn the tenthof a mm scale
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Crystallographic data on UNiS3
U
Ni
S
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Crystallographic data on UNiS3
OrthorhombicSpace Group: Pnma
a= 7.04
b=6.14c= 8.82= = = 90Z = 4
R=4.79
U
Ni
S
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Coordination Environments and Bond Lengths:
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Uranium CoordinationBicapped trigonal prismaticU-S 2.69(6) - 3.00(4)
Nickel CoordinationOctahedralNi-S 2.33(2)- 2.51(4)
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What can UNiS3 be used for and is it reproducible?
Future Steps:
Reproducibility
Magnetic Property Measurements
Electrical Conductivity Measurements
Preparation of Samples for NeutronDiffraction Measurements
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Acknowledgements:
National Science FoundationSummer Program in Solid-State
Chemistry, Grant No. DMR-0804648
Adam RawGeorge Oh
Luc Koscielski
Matt WardDr. Jim Ibers
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Questions??
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