资源描述：
《纳米材料和纳米结构第四讲.ppt》由会员上传分享，免费在线阅读，更多相关内容在应用文档-天天文库。
1、纳米材料和纳米结构水解和化学共沉淀法ForcedHydrolysisandChemicalCo-Precipitation第四讲BothmethodsaretechniquestoseparatemetalionsfromasaltsolutionAdvantagesofchemicalco-precipitationCheaprawmaterialsEaseofhandlingLarge-scaleproductionAdvantagesofforcedhydrolysisProducingfine,sphericalnanoparticlesImprovingchemicalpu
2、rity,chemicalhomogeneityControllingparticlesizeABriefDescription：ForcedHydrolysisandChemicalCo-PrecipitationTheeasiestwaytoprepareuniformcolloidalmetalhydrousoxides（胶体状的金属氢氧化物）isbasedonforcedhydrolysisofmetalsaltsolutions.1ForcedHydrolysisMostpolyvalentcationscanbeeasilyhydrolyzed,andthehydroly
3、sisproductsareintermediatestoprecipitationofmetalhydrousoxides.Oncethesolutionreachesacriticalsuper-saturationoftheparticle-formingspecies,onlyoneburstofnucleioccurs.Acontinuousdiffusionofsolutesontotheexistingnucleileadstothegrowthoftheparticles.1-1KeyFactorsAffecttheSynthesizingProcessConcent
4、rationofReactantsAgingTemperatureHeatingTimeTypesofAnionsNote:Itisthetypesofanionsotherthanhydroxideionscanaffectthehomogeneousprecipitationofmetalions!EffectofAnionsAgingasolutionof0.001MAl（ClO4）3+0.003MAl(NH4)(SO4)2at100°Cfor72hrsinasealedtesttube,wecanobtainsphericalaluminumhydroxide(Al(OH)3
5、)withadiameterof500nm.Agingaluminumnitrate(Al（NO3）3)solutioncanyieldcrystallineboehmite（勃姆石，α-AlO(OH)）Mono-dispersedcubicparticlesofCo3O4arepreparedbyagingCo(II)-acetatesolutionsat100°Cinthepresenceofoxygen,butnosuchparticlesprecipitatedfromCoSO4,Co(NO3)2,orCoCl2solutions.Agingasolutionof0.02MF
6、eCl3+0.001MHClat100°Cfor24hrsinasealedtesttube,wecanobtainhematite（赤铁矿，Fe2O3）;BychangingtheconcentrationsofFeCl3andHCl,theagingtemperature,andtheheatingtime,theparticlesize,thecompositionandtheshapecanbechanged,suchasintheshapeofdouble-ellipsoidal,ellipsoidal,irregular,rod-like,andspherical.Eff
7、ectofOtherFactorsMostofthehomogeneousprecipitationprocessesinvolveionicsolutions.Mono-dispersiveparticlescanbepreparedbycarefullycontrollingthekineticsoftheprecipitation.Thekineticsofnucleationandparticlegrowthcanbeadjustedbythesp
