简介:Inthisstudy,theeffectofmulti-walledcarbonnanotubes(MWCNTs)additiveonthedehydridingpropertiesoftheZn(BH4)2/NaCIcompositepreparedbyhighenergyballmillingwereinvestigated.X-raydiffraction(XRD),Fouriertransforminfraredspectroscopy(FTIR)resultsdemonstratedthatZn(BH4)2wasproducedfrommechanochemicalreactionbetweenZnCI2andNaBH4.Comparedwiththeundopedsample,10wt%MWCNTseffectivelyloweredthedecompositiontemperatureofZn(BH4)2by15℃.Thecomplexreleased3.6wt%hydrogenwithin250sat100℃andtotallyreleased4.5wt%hydrogenwithin2500s,indicatingithasaconsiderablepotentialasahydrogenstoragematerial.
简介:Inthisstudy,Almatrixcompositesreinforcedby7.5and15vol.%B4CparticlesandalsomonolithicAl(AlwithouttheB4Cparticles)wereproducedbywetattritionmillingandsubsequenthotforwardextrusionprocesses.Themicrostructureofthecomposites,evaluatedbyscanningelectronmicroscopy(SEM),showedthattheB4CparticleswereproperlydistributedintheAlmatrix.MechanicalpropertiesoftheAI/B4CcompositesandmonolithicAlwereinvestigatedbytensile,wearandhardnesstests.TheresultsrevealedthatwithincreasingcontentofB4Cparticles,thetensilestrengthandmicrohardnessofcompositesincreasedbuttheelongationdecreased.Inaddition,thetensilestrengthandmicrohardnessofcompositesampleswerehigherthanthoseofmonolithicAl.ThedensitymeasurementsrevealedthatthedensityofcompositesdecreasedwithincreasingcontentoftheB4Cparticles.
简介:Atomized,pre-alloyedTi—24Nb—4Zr—7.9Sn(wt%)powderwasusedtofabricatesolid,prototypecomponentsbyelectronbeammelting(EBM).Vickersmicroindentationhardnessvalueswereobservedtoaverage2GPafortheprecursorpowderand2.5GPaforthesolid,EBM-fabricatedproducts.Thepowderandsolidproductmicrostructureswereexaminedbyopticalandelectronmicroscopy.X-raydiffractionanalysesshowedthattheyhadbccβ-phasemicrostructure.However,itwasfoundbytransmissionelectronmicroscopythattheEBM-fabricatedproducthadplatemorphologywithspace~100—200nm.Althoughthecorrespondingselectedareadiffractionpatternscanbeindexedbyβ-phaseplusα'-martensitewithorthorhombiccrystalstructure,thedark-fieldanalysesfailedtoobservethea'-martensite.Suchphenomenonwasalsofoundindeformedgummetalsandexplainedbystress-induceddiffusionscatteringduetophononsoftening.
简介:Themetalorganicvaporphaseepitaxy(MOVPE)growthofindiumgalliumnitride(InGaN)hasbeendiscussedindetailtowardsthefabricationofsolarcell.TheInGaNfilmwithIncontentsupto0.4aresuccessfullygrownbycontrollingthefundamentalgrowthparameterssuchastheprecursorgasflowrates,temperatureetc.TheformationofmetallicInoriginatesfromthehighervalue(0.74)oftrimethylindium/(trimethylindium+triethylgallium)(TMI/(TMI+TEG))molarratiowithlow(4100)V/Ⅲweightmolarratiowhilethelowervalue(0.2)ofTMI/(TMI+TEG)causesthephaseseparation.Itisalsonecessarytocontrolthegrowthrateandepitaxialfilmthicknesstosuppressthephaseseparationinthematerial.ThecrystallinequalityofgrownfilmsisstudiedanditisfoundtobemarkedlydeterioratedwithincreasingIncontent.ThelatticeparametersaswellasthethermalexpansioncoefficientmismatchbetweenGaNtemplateandInGaNepi-layerareprimarilyconsideredasthereasonstodeterioratethefilmqualityforhigherIncontent.ByusingIn0.16Ga0.84Nfilms,ann+-phomo-junctionstructureisfabricatedon0.65mmGaNtemplate.Forsuchadevice,theresponsetothelightillumination(AM1.5)isobservedwithanop-ncircuitvoltageof1.4Vandtheshortcircuitcurrentdensityof0.25mA/cm2.Toimprovetheperformanceaswellasincreasesolarphotoncapturing,thedeviceisfurtherfabricatedonthickGaNtemplatewithhigherIncontent.TheIn0.25Ga0.75Nn+-pjunctionsolarcellisfoundbetterperformancewithanop-ncircuitvoltageof1.5Vandtheshortcircuitcurrentdensityof0.5mA/cm2.ThisistheInGaNp-nhomo-junctionsolarcellwiththehighestIncontenteverreportedbyMOVPE.