1155_Synthesis-of-powders-and-films-using-a-new-laser-ablation-technique

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1、NanoStructuredMaterials,Vol.11,No.8,pp.1155±1163,1999ElsevierScienceLtdPergamonCopyright©2000ActaMetallurgicaInc.PrintedintheUSA.Allrightsreserved.0965-9773/99/$±seefrontmatterPIIS0965-9773(99)00406-7SYNTHESISOFPOWDERSANDFILMSUSINGANEWLASERABLATIONTECHNIQUER.Houriet,R.VacassyandH.HofmannPowderTe

2、chnologyLaboratory,DepartmentofMaterialsScience,EPFL,CH-1015Lausanne,Switzerland(ReceivedSeptember27,1999)(AcceptedNovember21,1999)AbstractÐAnovelmethodtoproducepowdersandfilmsfromceramictargetsispresented.Itisshownthatthelasersparkatomizer(LINA-SPARKy),LSA,combinestheadvantagesofoperatingatatmo

3、sphericpressureandambienttemperaturetoproducehighlyuniformfilmswithaweb-likestructurewhichcanbedepositedatrelativelyhigh21depositionrates(ca.1mmzmin).Thepreparationofpowderparticlesandcoatingstartingfromcommercialceramicspecimen(Al2O3)isinvestigated.Highlyagglomeratednanopowdersandhomogeneousmes

4、oporouscoatingsformingaweb-likestructurearepreparedusingthisnewtechnique.Theformationofthenanoparticlesisexplainedfollowingaliquefactionprocesswhichgeneratesanaerosol,followedbythecooling/solidificationofthedropletswhichresultsintheformationofasmoke.Thegeneraldynamicofboththeaerosolandthesmokefa

5、vorstheaggregationprocessandmicrometer-sizedfractal-likeparticlesareformed.Thelasersparkatomizercanbeusedtoproducehighlymesoporousthickfilms.Theporositycanbemodifiedbythecarriergasflowratethusenablingforacontrolofthemicrostructureofthecoatingswhichmakethesenanoparticulatethickfilmssuitablecandid

6、atesforapplicationinmembranetechnology,catalysisandlithiumionbatteries.ZrO2andSnO2nanoparticulatethickfilmsarealsosynthesizedsuccessfullyusingthisnewprocesswithquiteidenticalmicrostructure.©2000ActaMetallurgicaInc.1.IntroductionThesynthesisofnanoparticlesintheformofhomogeneouscoatingshasshowngro

7、winginterestduringrecentyearsduetotheirsmallsizeandfinemicrostructurewhich,inmostcases,exhibitnovelpropertiesdifferentfromthebulkmaterialone.Thecontrolofthechemistryandmicrostructureofthinorthickfilmsisofprimaryimportance.Ak