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第1页共8页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第1页共8页AsimplesynthesisofFe3O4powdersandtheirStructure,magneticandelectricaltransportpropertiesK.L.Liu*,Y.D.Du,C.Y.LiDepartmentofPhysics,ZhenzhouelecticlpowercollagezhanghaiyangPeople’sRepublicofChina.ABSTRACTFe3O4powderswithhighlycrystallinehavebeensynthesizedbyasol-gelautocombustionsynthesismethodaccompanyingthermalprocess.Thephasestructures,morphologiesofFe3O4havebeencharacterizedbyx-raydiffraction(XRD)andscanningelectronmicroscopy(SEM)equippedwithenergydispersivex-rayspectrometer(EDX).Theresultsshowthatcompleteandhighlycrystallinenaturemagnetitepowderscanbeobtained.Furthermore,theroom-temperaturemagnetizationsandtheresistanceofFe3O4powderswerealsomeasured.ThemaximummagnetizationofsampleS1,S2andS3is88.3,87.32and89.4emu/gattheappliedmagneticfield5kOe,respectively,whicharelargerthanthesaturationmagnetizationofthebulkγ-Fe2O3(76emu/g).ItisprovedfurtherthatFe3O4powderscanbesynthesizedbythecitrate-nitratesol-gelautocombustionreactionmethod.Thepreliminaryreactionmechanismisalsodiscussed.Keywords:Fe3O4;Magneticmaterials;Sol-gelpreparation;Halfmetallic1.IntroductionMagnetite,Fe3O4,isferromagneticinversespinelstructurewithananomaloushighCurietemperatureof860Kandanexceptionallyhighconductivity[1].Inaddition,theband-structurecalculationsformagnetitehaveindicatedthatFe3O4ishalf-metallicandtheconductionelectrons*Correspondingauthor.Address:DepartmentofPhysics,ZhoukouNormalUniversity,Zhoukou466000,PRChina.Tel:15936017799;E-mailaddress:liukuili@163.com第2页共8页第1页共8页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第2页共8页are100%spinpolarized[2].Thesepropertiesmakemagnetitetobeappliedextensivelyinmagnetoresistivedevices,magneticstorageandbiomedicine[3-7].Thenanocrystallinemagnetitewithauniformparticlesizehasbeensuccessfullysynthesizedbychemicalco-precipitation[8,9],thermaldecomposition[10],hydrothermalreaction[11]andsol–gel[12]andothermethod[13].Inthiswork,uniformFe3O4powdersweresynthesizedbythecitrate-nitratesol-gelautocombustionreactionmethod.Thesol-gelautocombustionsynthesismethodforpreparingnanoparticlesofferritespinelssuchasMFe2O4(M=Ni,Zn,Co)[14-18]hasbeendevelopedsuccessfully,whichcanbeanalternativemethodtothoselistedabove.Inthismethod,intermediatedecompositionandcalciningstepsarenotinvolved.Moreover,itiseasytocontrolpreciselythestoichiometriccompositionandcrystallitesize,whichhaveimportanteffectsonthemagneticpropertiesandapplicationsofthemagnetite.Here,forthefirsttimethesynthesisofferritespinelFe3O4powders,usingcitricacidasreducingagentandironnitrateasstartingmaterial,isreported,andthemagnetizationsandresistancesofthesamplesarealsocarriedout.2.ExperimentalprocedureThechemicalmaterialsFe(NO3)3·9H2OandcitricacidwithanalyticalgradewereemployedasrawmaterialstoprepareFe3O4ferrite.Anaqueoussolutioncontainingferricnitrate(0.8M)waspreparedfirst.Withconstantstirring,anappropriateamountofcitricacidwasaddedtothissolutiontoproduceclearcationicsolution.InordertopreparetheperfectFe3O4powders,thedifferentmolarratioofironnitratetocitricacidwasintroduced.S1,S2,andS3wereusedtopresentthesamplessynthesizedatthedifferentmolarratioof1:1,2:1and3:1,respectively.Theresultingsolutionwasevaporatedat348Kandstirredtoformatransparentsol.Then,thetransparentsolwasdriedat403Kforhalfanhourtofurtherremovewater.Thesol...