南邮材料化学答案-第五章习题答案

第五章材料的制备1.提拉法中，控制晶体品质的因素主要有哪些？Inthepreparationofcrystalwithpullingmethod,whatfactorscaninfluencethequalityofcrystal?答：提拉法中，控制晶体品质的主要因素有固液界面的温度梯度、生长速率、转晶速率以及熔体的流体效应等。Answer：Inthepreparationofcrystalwithpullingmethod,factorsinfluencethequalityofcrystalincludetemperaturegradientonsolid-liquidinterface,growthrate,crystalspinrate,andfluideffectofmelt.2.单晶硅棒和厚度约1μm的薄膜分别可用什么方法制备？HowtoprepareSiliconrodsandthickfilmabout1μm?答：1）单晶硅棒可以用晶体生长技术中的提拉法来制备，即将硅原料熔体盛放在坩埚中，籽晶杆带着籽晶由上而下插入熔体，由于固液界面附近的熔体维持一定的过冷度，熔体沿籽晶结晶，以一定速度提拉并且逆时针旋转籽晶杆，随着籽晶的逐渐上升，生长成单晶硅棒。2）厚度约1μm的单晶硅薄膜可用阴极溅射法制备，即利用高能粒子轰击固体靶材表面（Si），使得靶材表面的原子或原子团获得能量并逸出表面，然后在基片的表面沉积形成单晶硅薄膜。Answer:1)SiliconrodscanbepreparedbyCzochralskicrystalgrowthtechnology,thatistosay,putthesiliconrawmaterialmeltinthecrucibleandinserttheseedrodwithaseedcrystalintothemeltfromtoptobottom.Meltnearthesolid-liquidinterfacemaintainsacertaindegreeofsupercooling,thenthemeltcrystallizealongtheseed.Pulltheseedrodatacertainspeedandrotateitcounterclockwise,withthegradualincreaseoftheseed,growintosiliconrods.2)Monocrystallinesiliconthinfilmof1μmthickcanbepreparedbycathodesputtering.Usingenergeticparticlebombardthesurfaceofthesolidtarget(Si),andthetargetsurfaceatomsorgroupsofatomsgainenergyandescapefromthesurface,andthendepositonthesurfaceofthesubstratetoformamonocrystallinesiliconthinfilm.3．液相外延法和气相沉积法都可制备薄膜，如果要制备纳米厚度的薄膜，应采用哪种方法？Bothliquidphaseepitaxymethodandvapordepositioncanbeusedtoprepairfilm,ifyouwanttoobtainfilmofnmthickness,whichmethodshouldbeselected?答：液相外延法具有设备简单、纯度高的特点，但是由于晶体成核和生长的速率较快，得到的膜较厚，很难得到纳米厚度的薄膜。物理气相沉积可通过调控蒸镀源与靶之间的距离来调控膜沉积的速率，化学气相沉积可通过体系的温度、压力等因素来调控膜沉积的速率。因此，如果要制备纳米厚度的薄膜，应采用气相沉积法比较好。Answer:Liquidphaseepitaxymethodissimple,andthepurityoffilmishigh,however,becausetherateofnucleateformationandcrystalgrowthisfast,itisdifficulttogetthemembraneofnmthickness.ForPhysicalvapordeposition,wecancontroltherateoffilmdepositionthroughregulatingthedistancebetweenthesourceandtarget.Forchemicalvapordeposition,wecancontrolthefilmdepositionratebycontrollingtemperatureandpressure.Soifyouwanttopreparefilmofnanometerthickness,vapordepositionshouldbeselected.4.CVD法沉积SiO2可通过哪些反应实现？写出相关化学方程式。WhichreactionscanbeusedtodepositeSiO2withCVD?Writetherelevantchemicalequation.答：CVD法沉积SiO2可通过以下几种反应来实现。1）烷氧化物的热分解：Si(OC2H5)4→SiO2+C2H4+H2O2）硅化合物的氧化反应：SiCl4(g)+O2(g)→SiO2(s)+2Cl2(g)SiH4(g)+O2(g)→SiO2(s)+2H2(g)SiCl4(g)+2CO2+2H2(g)→SiO2(s)+4HCl(g)+2CO(g)3）硅化合物的水解反应：SiCl4(g)+2H2O(g)→SiO2(s)+4HCl(g)Answer:CVDdepositionofSiO2canbeachievedthroughthefollowingreaction:1)Thealkoxidethermaldecomposition:Si(OC2H5)4→SiO2+C2H4+H2O2)Oxidationofsiliconcompounds:SiCl4(g)+O2(g)→SiO2(s)+2Cl2(g)SiH4(g)+O2(g)→SiO2(s)+2H2(g)SiCl4(g)+2CO2+2H2(g)→SiO2(s)+4HCl(g)+2CO(g)3)Hydrolysisofsiliconcompounds:SiCl4(g)+2H2O(g)→SiO2(s)+4HCl(g)5.用什么方法可以对Cu和Cu2O进行分离？写出相关化学方程式。WhatmethodcanbeusedforseparationofCuandCu2O?Writetherelevantchemicalequation答：对Cu和Cu2O进行分离，可以采用化学气相输运技术，以HCl作为输运气体。过程中发生如下反应：由于从Cu2O生成CuCl为放热反应，而从Cu生成CuCl为吸热反应，因此Cu2O在较高温度处沉积，而Cu则在较低温度处沉积，从而可以对Cu和Cu2O进行分离。Answer:CuandCu2OcanbeseparatedbychemicalvaportransportwithHClasthetransportgas.Thefollowingreactionsoccurduringtheprocess：DuetogenerationofCuClfromCu2Oisexothermicreaction,whilegenerationofCufromCuClisendothermicreaction.,ThereforeCu2Oaccumulateathighertemperature,whileCuaccumulateatarelativelylowtemperature,therebywecanseparateCuandCu2O.6.溶胶-凝胶法制备纤维材料，应采用怎样的条件较合适？请解释。Preparingfibermaterialbysol-gel,whatconditionsshouldbemoreappropriate?Pleaseexplainit.答：溶胶－凝胶法制备纤维材料，应在拉纤阶段控制合适的粘度，选择合适的催化剂，选择合适的成纤方法。因为拉纤阶段溶胶的粘度会影响纤维的直径和纤维的质量，粘度大时得到的纤维直径较大，粘度小时得到的纤维直径较小。其次，因为是要得到纤维材料，所以缩聚的中间体应该是线形分子链，所以应使用酸催化，因为碱催化会得到三维网络结构的中间体。此外，如果要得到长纤维的话，可以用拉纤法，而要得到短纤维的话，应采用离心喷出法。Answer:Preparingfibermaterialsbythesol-gel,appropriateviscosityshouldbecontrolledinordertochooseasuitablecatalystandtherightmethodtoformthefiberinthetowstage.Becausethesol'sviscosityinthetowstagewillaffectthequalityanddiameterofthefiber,thediameteroffiberisbiggerwithhighviscosityandsmallerwithlowviscosity.Secondly,inordertogetfibermaterials,theintermediatesofthepolycondensationshouldbelinearmolecularchain,soacidcatalysisshouldbeused,duetoalkalicatalysisleadingtothree-dimensionalnetworkstructureoftheintermediate.Inaddition,ifyouwantalongfiber,towmethodshouldbeused,whilethecentrifugalspraymethodshouldbeusedforshortfiber.7.怎样用均匀沉淀法合成硫化锌颗粒？写出相关化学方程式。HowtosynthesizeZnSparticlesbyhomogeneousprecipitation?Writetherelevantchemicalequation.答：用均匀沉淀法合成ZnS颗粒，可以采用硫代乙酰胺（CH3CSNH3）作为硫源，以乙酸锌（（CH3COO）2Zn）为原料制得，反应方程式如下：Answer:SynthesizeZnSparticlesbyhomogeneousprecipitationmethod,thioacetamide(CH3CSNH3)canbeusedasasulfursourceandzincacetate((CH3COO)2Zn)canbeusedasrawmaterials,thereactionequationisasfollows:3232CHCSNHCHCN+HS3232CHCSNHCHCN+HS