低維非晶氧化鐵的相轉(zhuǎn)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(zhuǎn)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