简介:AnewtechniqueofthesynthesisofNanocrystallineDiamond(NCD)Filmsbyheliconwaveplasma(HWP)chemicalvapordepositionatroomtemperaturewasreported.ThegrowthmorphologyandtheroughnessofNCDsampleswascharacterizedusingfiledemissionscanningelectronmicroscopy(SEM-SU8010)andatomforcemicroscopy(AFM),respectively.Theresultsshowthegrowthrateofthefilmwasveryfast,about833nm/min.TypicalG,Dbands
简介:NanocrystallineNi粉末成功地被制作由机械地在有1个wt.%Y_2O_3粒子的低温实验法的温度(cryomilling)的milling。试验性的结果证明了Ni谷物尺寸面对Y_2O_3粒子在cryomilling的2h以后被归结为25nm。cryomilledNi/Y_2O_3粉末能维持他们的nanocrystalline结构直到900℃,否则融化中的62%个Ni指。有约100nm的athermally稳定的谷物尺寸的体积nanocrystallineNi/Y_2O_3材料被cryomilling生产,冷均衡说的紧迫,由热均衡说的压列在后面。体积nanocrystallineNi/lwt.%Y_2O_3的微坚硬是315DPH,它二倍高于常规Ni的。
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简介:DiffusionofAlinthinfilmnanocrystallineCu(18nm)hasbeeninvestigatedbymeansofsecondionmassspectroscopy(SIMS).Intheexperimentaltemperaturerangesfrom421to773K,thereseem-inglyexiststwodiffusionmechanisms.TheimpurityelementsOandCaresupposedtoaccumulatetothegrainboundariesandinhibitthefastgrainboundarydiffusion.
简介:Extendedx-ray-absorptionfine-structuremeasurements(EXAFS)wereperformedonnanocrystalline(nc)elementalSesampleswithgrainsizesrangingfrom13to60nm.Accompaniedwiththepreviousstudy,weconcludedthat,withtherefinementinnc.Se.theintrachainstructure(thebondlength,thecoordinationnumber)isunchangedwhiletheinterchainspacingisenlarged.ThegrainboundaryinthencSeisfoundtobeinalow-energyconfigurationthatisdifferentfromthedisorderedgaslikegrainboundarystructure.
简介:Micro-/nanocrystallinediamondfilmsdepositedinAr/H2/CE4microwaveplasmashavebeenstudied,withargonflowratesintherangeof70-100seem.Theeffectsofargonadditiononmorphology,surfaceroughness,qualityandstructurewereinvestigatedbyscanningelectronmicroscopy,surfaceprofiler,RamanspectrometerandX-raydiffraction(XRD).Itisdemonstratedthatwhentheargonflowrateis70sccmor75sccm,well-facetedpolycrystallinediamondfilmscanbegrownatalowsubstratetemperaturelessthan610℃.Withtheincreaseintheargonflowrate,thesmoothcrystallographicplanesdisappeargradually.Instead,roughcrystallographicplanesmadeupofsmallaggregatesbegintotakeshape,resultingfromtheincreaseinthesecondarynucleationrate.Nanocrystallinediamondfilmswereobtainedataflowrateof100sccm,andalloftheprepareddiamondfilmsweresmooth,withasurfaceroughness(Ra)lessthan20nm.Ramananalysesrevealthattheamountofamorphouscarbonincreasessignificantlywiththeincreaseinargonflow.TheresultsofXRDshowthatcrystallinesizeandpreferentialorientationofdiamondfilmsdependontheargoncontentintheplasmas.
简介:ZrO2-SnO2compositenanoparticleswerepreparedbyheatingthehydrateprecursorssynthesizedbythechemicalco-precipitationreactionofZrOCl2andSnCl4.Theprecursorswereexaminedbydifferentialthermalanalysis(DTA)andthermogravimetricanalysis(TGA).ThecompositepowderwascharacterizedusingX-raydiffraction(XRD),transmissionelectronmicroscopy(TEM)anddesorptionisotherm(Barrett-Joyner-Halendamethod).Theaveragecrystalsizeofthenanoparticlerangesfrom15to30nmforthesamplecontaining5%-25%ZrO2(massfraction).MostoftheporesintheZrO2-SnO2nanoparficlesareabout10-20nmindiameter.Thecompositepowderispromisingforchemicalsensors.
简介:Themicrostructureofstress-inducedmartensite(SIM)inthenanocrystallineNiTialloywasinvestigatedbymeansoftransmissionelectronmicroscopy(TEM).Theresultshowsthatthemulti-variantstructureofthemartensiteissuppressedandonlysingle-variantmartensitictwinsformaftertensiledeformationwhenthegrainsizeissmallerthan80nm.Thenormaldirectionsofthe(001)B190twinplanesareallwithintherangeof45°fromtheaxialdirectionofthewire.Theanglebetweentwincrystals(1'11)Mand(111)ToftheSIMisalsofoundtobesmallerthanthatofthermallyinducedmartensiteinnanocrystallineNiTi.
简介:Inthiswork,boththethermalexpansionandelectricalconductivityofnanocrystallineLa2Mo2O9werestudied.ThenanocrystallinepowderofLa2Mo2O9wasobtainedbysol-gelmethod,andwiththehelpofSHP(superhighpressure)upto4.5×104atmat700℃forashorttime,andthenanocrystallinepowderwasdensifiedwithoutobviousparticlesizegrowth.TheelectricalconductivityofnanocrystallineLa2Mo2O9wasoneorderofmagnitudelowerthanthatofthemicrocrystallinesampleatthesametemperature.Owingtothephasetransition,themicrocrystallineLa2Mo2O9hasanabruptincreaseofthermalexpansionwithapeakvalueof48×10-6K-1at556℃.Forthenanocrystallinematerial,thepeakvalueincreasesto112×10-6K-1at520℃.Ontheotherhand,above600℃thesignificantgrowthofparticlesizeofthenanocrystallineLa2Mo2O9wasobserved,accompanyingbyatremendousincreaseofthermalexpansionwithapeakvalueofthirdhigherthanthatofLa2Mo2O9.
简介:有关于30-50nm的谷物尺寸的nanocrystallineMg2Si(n-Mg2Si)的Densification行为被hot-pressing在显示的400°C.The结果调查n-Mg2Si的那个thedensification过程展出了三线性segments:p<0.3GPa,0.3GPa
1.2GPa由Heckel决定了公式,在哪个之中在高压力范围p>1.2GPa的第三个快增加片断很少在常规纹理粗糙的polycrystallinematerials.Nevertheless被报导了,在调查的整个压力范围(0.125-1.500GPa),n-Mg2Si的densificationbehavior能是Kawakita公式p/C=(1/a)描述的井有在对协议的起始的孔的好同意的constanta=0.452的p+1/(ab)。
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