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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

  • Sco-ShawDepartmentofPhysicsandAstronomy

    Bismuth Oxyhalides

    2

    BiOX;X=F,Cl,Br,IFormatetragonalmatlockitestructure.Thisisalayerstructurecharacterisedby[Bi2O2]slabsinterleavedbydoubleslabsofhalogenatoms.BismuthoxyhalidessemiconductorshavedemonstratedexcellentphotocatalyOcacOviOesandareofferinganewfamilyofpromisingphotocatalysts.BiOIcouldbeaneffecOvestoragesitefor129Iwhichremainsasignificantconcernforsafenuclearwastestorage.

    BiOCl matlockite structure:Bismuth atoms shown as grey,

    oxygen red, chlorine green

  • Sco-ShawDepartmentofPhysicsandAstronomy

    Bismuth Oxyhalides (2)

    3

    ProducOonofBismuthoxyhalidesiscurrentlydoneviaawetchemistryroute.BiOX;X=F,Cl,Br,IReagents:Bi2O3andNH4X;SigmaAldrichandAlfaAesar,Purity98%

    Bi2O3+2(NH4X)2BiOX+2NH3+H20

  • Sco-ShawDepartmentofPhysicsandAstronomy

    Mechanochemical Processes

    4

    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

  • Sco-ShawDepartmentofPhysicsandAstronomy

    ProcessforReac-onMilling

    5

    FritschMini-MillPulveriseBe23isconsideredalowenergymillMillingcontainer:ZirconiaOxide Frequency:30HzMillingSpeed:0.27ms-1MillingMedia:ThreeSpherical10mmZirconiaOxideMediaAllmillingwasconductedatapproximatelySATP.

    BallMassRaOo:Withinboundsofbetween1/50andReagentscomposiOon:Stoichiometric(Otherwisestated)MillingTime:StatedMillingFluid:Noneotherwisestated.

    Ifstated;sumofreagentsmasstotal1gwith1mloffluid

  • Sco-ShawDepartmentofPhysicsandAstronomy

    ProcessforSolidStateSynthesis

    6

    Reagentsmasses:Stoichiometric(Otherwisestated)

    FritschMini-MillPulveriseBe23usedtomillreagents.

    UnderthesamecondiOonsstatedpreviously

    MillOme3minutes.

    ProductwasthenplacedintoAluminium(III)oxidecrucibles

    Placedintofurnaceat350C

    Quenchedat:(3,10,15,30,45,90)minutesintervals

  • Sco-ShawDepartmentofPhysicsandAstronomy

    Characterisa-on

    7

    Diffrac-onPaBernforchemicalcharacterisa-onBrukerD2Phaser

    Current: 10mA Voltage: 30kV CuKX-rayTube:=1.54184 Range: 20