低維非晶氧化鐵的相轉變及殼-芯復合納米線的制備.pdf

1、燕山大學博士學位論文低維非晶氧化鐵的相轉變及殼芯復合納米線的制備姓名：諶巖申請學位級別：博士專業(yè)：材料學指導教師：張湘義20060301燕山大學工學博士學位論文AbstractTheenhancementofthestructuralstabilityofamorphousnanostructuredmaterialsisveryimportantfortheirpracticalapplicationssincetheyhavealo

2、tofsurfacesandinterfacesaswell砸themetastabilitynatureofamorphoussolidsManyresearchworkshavebeenfocusedontheshelFcorecompositenanowiresduetotheirnovelphysicalandchemicalpropertiesInpresentwork，boththestructuralstabilityof

3、amorphousnanostrucuredironoxideandthesynthesisofNi／rFe203shell／corenanowirchavebeeninvestigatedbytheemploymentofaxraydiffractometer(XRD)，atransmissionelectronmicroscopy(TEM)，anddifferentialscanningcalorimetry(DSC)measure

4、ments，etcNanosizedamorphousironoxidepowderswerepreparedbychemicalmethodandtheir舒lrlbcewereprocessedbyemployingtheNaOHsolutionComparedwithaSpreparednanosizedironoxidepowdersthecrystallizationtemperatureofsurfaceprocessedp

5、owdersWaSincreaSedbyavalueof493oCandthecrystallizationactivationenergyincreasesfrom815kJ／molt01568kJ／m01ThesurfacemodifiedamorphousFe203powdersshowanentirelydifferentcrystallizationbehaviorascomparedwitllaspreparedamorph

6、ouspowdersTheenhancedstructuralstabilityisattributedtotheincreaseoftheamotmtofhydroxidegroupingsatthesurfacesofamorphouspowders，whichlowerstheirsurfaceenergyandsuppressesthecrystalsurfacenucleationAmorphousironoxidenanow

7、ireswerepreparedbychemicalmethodusingtheporousanodicaluminatemplate(PAAT)TheamorphousironoxidenanowireswithoutPAAThaveacrystallizationtemperatureofaboutTx3656‘)Candacrystallizationactivationene旭yof883kJ／mol，alittlehigher

8、thanthatoftheaSpreparednanosizedamorphousironoxidespowdersHowevertheamorphousnanowiresshowalargercrystallizationactivationenergyofabout115kJ／toolattheinitialstageofcrystallizationtransition11碡crystallizationtransitionofa