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1、Polyhedron26(2007)356–368www.elsevier.com/locate/polyOpalandinverseopalphotoniccrystals:Fabricationandcharacterizationa,bb,*GeoffreyI.N.Waterhouse,MarkR.WaterlandaDepartmentofChemistry,UniversityofAuckland,PrivateBag92019,Auckland,NewZealandbNanomaterialsResear
2、chCentreandMacDiarmidInstituteforAdvancedMaterialsandNanotechnology,MasseyUniversity,PrivateBag11222,PalmerstonNorth,NewZealandReceived14April2006;accepted21June2006Availableonline5July2006AbstractThree-dimensionalphotoniccrystalsmadeofclose-packedpolymethylme
3、thacrylate(PMMA)spheresorairspheresinsilica,titaniaandceriamatriceshavebeenfabricatedandcharacterizedusingSEM,XRD,RamanspectroscopyandUV–Vistransmittancemeasure-ments.ThePMMAcolloidalcrystals(opals)weregrownbyself-assemblyfromaqueoussuspensionsofmonodispersePM
4、MAsphereswithdiametersbetween280and415nm.SEMconfirmedthePMMAspherescrystallizeduniformlyinaface-centredcubic(fcc)array,andUV–Vismeasurementsshowthatthecolloidalcrystalspossesspseudophotonicbandgapsinthevisibleandnear-IRregions.Inverseopalswerepreparedbydepositi
5、ngsilica(SiO2),titania(TiO2)orceria(CeO2)inthevoidsofthePMMAcolloidalcrystalsusingsol-gelprocedures,thencalciningtheresultingstructureat550°Ctoremovethepolymertemplate.Theresultingmacroporousmaterialsshowedfccorderingofairspheresseparatedbythinframeworksofamor
6、phoussilica,nanocrystallinetitaniaornanocrystallineceriaparticles,respectively.Opticalmeasurementsconfirmedthephotonicnatureoftheinverseopalarrays.UV–VisdatacollectedfortheopalsandinverseopalsobeyedamodifiedBragg’slawexpressionthatconsidersbothdiffractionandrefra
7、ctionoflightbythephotoniccrystalarchitectures.Theversatilityofthecolloidalcrystaltemplateapproachforthefabricationofmacroporousoxidestructuresisdemonstrated.Ó2006PublishedbyElsevierLtd.Keywords:Colloidalcrystals;Opals;Inverseopals;Macroporousoxides;Photonicban
8、dgaps1.Introductiondirection[1].EversinceYablonovitch[2]andJohn[3]firstdemonstratedthepossibilityofaphotonicbandgapinPhotoniccrystalsarehighlyorderedmaterialsthatpos-suchperiodicstr