isl presentation
TRANSCRIPT
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Mechanochemical Synthesis of Bismuth Oxyhalides Scott Shaw Department of Physics and Astronomy, The University of Sheffield Summer Research Presentation, ISL Meeting, Sheffield, UK, 26 September 2014. ISL_Sheffield
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Sco-ShawDepartmentofPhysicsandAstronomy
Bismuth Oxyhalides
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BiOX;X=F,Cl,Br,IFormatetragonalmatlockitestructure.Thisisalayerstructurecharacterisedby[Bi2O2]slabsinterleavedbydoubleslabsofhalogenatoms.BismuthoxyhalidessemiconductorshavedemonstratedexcellentphotocatalyOcacOviOesandareofferinganewfamilyofpromisingphotocatalysts.BiOIcouldbeaneffecOvestoragesitefor129Iwhichremainsasignificantconcernforsafenuclearwastestorage.
BiOCl matlockite structure:Bismuth atoms shown as grey,
oxygen red, chlorine green
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Sco-ShawDepartmentofPhysicsandAstronomy
Bismuth Oxyhalides (2)
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ProducOonofBismuthoxyhalidesiscurrentlydoneviaawetchemistryroute.BiOX;X=F,Cl,Br,IReagents:Bi2O3andNH4X;SigmaAldrichandAlfaAesar,Purity98%
Bi2O3+2(NH4X)2BiOX+2NH3+H20
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Sco-ShawDepartmentofPhysicsandAstronomy
Mechanochemical Processes
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Mechanicalmillingiss-llmainlyusedtoreducepar-clesizeMechanicallyAlloying(MA):Dry,highenergymilling.Usedtoproduceadvancedmaterials. ThiscanbeseenasMechanicalAcOvaOon.Mechanochemistry/Reac-onMilling(RM): InducechemicalreacOonthroughsolelymechanicalenergy.CommonalityHighStresses( 200MPainasteelballSPEXmill)ParOclesarerepeatedlyfla-ened,fracturedandweldedMixingofelementstakesplaceonanatomicscaleDisorderinganddislocaOonsareintroducedrepeatedlyintothesystem.
Time to reach similar particle sizes during milling of Pr16Fe76B8 powder1
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Sco-ShawDepartmentofPhysicsandAstronomy
ProcessforReac-onMilling
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FritschMini-MillPulveriseBe23isconsideredalowenergymillMillingcontainer:ZirconiaOxide Frequency:30HzMillingSpeed:0.27ms-1MillingMedia:ThreeSpherical10mmZirconiaOxideMediaAllmillingwasconductedatapproximatelySATP.
BallMassRaOo:Withinboundsofbetween1/50andReagentscomposiOon:Stoichiometric(Otherwisestated)MillingTime:StatedMillingFluid:Noneotherwisestated.
Ifstated;sumofreagentsmasstotal1gwith1mloffluid
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Sco-ShawDepartmentofPhysicsandAstronomy
ProcessforSolidStateSynthesis
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Reagentsmasses:Stoichiometric(Otherwisestated)
FritschMini-MillPulveriseBe23usedtomillreagents.
UnderthesamecondiOonsstatedpreviously
MillOme3minutes.
ProductwasthenplacedintoAluminium(III)oxidecrucibles
Placedintofurnaceat350C
Quenchedat:(3,10,15,30,45,90)minutesintervals
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Sco-ShawDepartmentofPhysicsandAstronomy
Characterisa-on
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Diffrac-onPaBernforchemicalcharacterisa-onBrukerD2Phaser
Current: 10mA Voltage: 30kV CuKX-rayTube:=1.54184 Range: 20