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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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