简介:采用水热法制备平均粒度约300nin的六方相Bi2Te3纳米粉末。再以Bi2Te3粉末为原料,采用封管熔炼法制备N型(Bi2Te3)0.9(AgxBi2-xSe3)0.1(x为Ag的摩尔分数。x=0.1,0.2,0.3,0.4)合金粉体材料,通过快速热压制备N型(Bi2Te3)0.9(AgxBi2-xSe3)0.1块状热电材料。在300~550K温度范围内研究该材料的热电性能与Ag掺杂量之间的关系,以及热压工艺对材料热电性能的影响。结果表明在775K,40MPa条件下烧结20min后材料的相对密度达到97%以上,晶粒大小在3gm左右。当Ag掺杂量x=0.2时,在300K温度下热导率达到最小值0.71W/mK,同时获得最高的热电优值(ZT值)1.07。
简介:EffectofMnsubstitutionforFeincubicLavesZr0.1Tb0.9(Fe1-xMnx)2andY0.1Tb0.9(Fe1-xMnx)2com-poundsispresented.Similarresultsinbothsystemsareobtained:ThestructureandthemagnetismofTbFe2arebothinfluencedslightlybyasmallamountofYorZrsubstitutionforTb;Withincreasingxvalue,thelatticeconstantincreasesmonotonously;theCurietemperaturedecreaseslinearly;whilesaturationmagnetizationincreaseslinearly.ForthesmallamountofMnsubstitutionforFeinbothsystems,magnetostrictionissignificantlylargerthanthatinthepureironalloys.Thelargestmagnetostrictionof|γ‖-|γ|=2200×10-6atmagneticfieldof2×107/4πA/misobtainedforY0.1Tb0.9(Fe0.95Mn0.052.
简介:将95%Mg+3%Ni+2%MnO2混合粉末在行星式高能球磨机中充氢反应球磨100h,利用X射线衍射(XRD)和扫描电镜(SEM)对球磨后的粉体进行表征,并研究其与水反应的动力学性能。结果表明,充氢球磨能对Mg-3Ni-2MnO2进行充分的氢化,Mg全部形成MgH2。制备的氢化态Mg-3Ni-2MnO2复合粉末的颗粒尺寸为0.1~5gm,晶粒尺寸在1~40nm之间。复合物在二次去离子水中水解时,随温度升高,放氢量增加,当温度为343K时,在20min内放出的氢气达到理论放氢量的91-3%,有望成为1种新的安全高效氢源技术。Avrami指数的数值变化表明,氢化态Mg-3Ni-2MnO2复合粉体的水解过程中,不同阶段其水解机理有所不同。
简介:Awhitelong-lastingphosphorCa2MgSi2O7:Dy3+waspreparedbythesolid-statereaction.Astrongbandpeakedat260nmwasshownintheexcitationspectrumof578nmemission,whichmightbeattributedtotheoxygendeficiencyofthehost.Afterirradiatedwith254nmfor4min,thewhiteafterglowofthesamplecouldbeseenfor3h.Moreover,thedepthsandfrequencyfactorsoftrapcenterswerecal-culatedfromthethermo-luminescencecurveofthesample,whichindicatedthatthetrapcenterscorrespondingtothe414Kbandweremorehelpfultothelong-lastingphosphorescence.
简介:TheTiO2nanomembranedopedbyREionswerepreparedbymixingREionsintoTiO2solutionandthephoto-catalyticpropertiesofthecoatingglasswithTiO2membranedopedbyREionstomethylbenzenedegradationunderultravioletwereinvestigated.AFMphotoesshowthatthesurfaceofcoatingglasswithTiO2nanomembranedopedbyCe3+,Ce4+,Y3+arecomposedofparticleswithdiametersof30~50nm.Theresearchesonphoto-catalyticpropertiesprovethatthesurfaceofcoatingglasswithTiO2nanomembranedopedbyREionspossessesgoodphotocatalyticpropertiesunderultravioletandthedegradationpercentsofmethylbenzenearemorethan90%whenthedegradationtimeisshorterthan160min.WhenthemoleratioofCe3+,Y3+,Ce4+toTiO2is0.002thedegradationpercentsofmethylbenzenearerespectively92.85%,91.87%and91.15%under254~365nmultravioletin50μg·ml-1methylbenzenesolution.ThephotocatalyticabilityofthesurfaceofcoatingglasswithTiO2nanomembranedopedbyCe3+underultraviolettodegrademethylbenzeneincreasesastheconcentrationsofREionsincreaseandtheiroptimumpercentageofdegradationare98.50%,97.50%and96.35.5%respectively.Thehighertheconcentrationofmethylbenzenesolutionthelowerthepercentsofthemethylbenzenedegradationofthecoatingglassare,andthebiggertheratiooftheareasofcoatingglasstothevolumeofmethylbenzenesolutionthehigherthedegradationeffectofmethylbenzeneis.
简介:Ceriasphereswithdifferentsizesandsulfurizedproductswithcorrespondingmorphologywerepreparedbyhydrothermalandgas-solidreactionmethodat600–800°CunderCS2atmosphereforashorttime,respectively.Dimensionaleffectinpreparationofγ-Ce2S3wasfirstlyinvestigatedbymeansoftechniquessuchasscanningelectronmicroscopy(SEM),X-raydiffraction(XRD),thermalgravimetricanalysis(TGA)andspectrophotometer.Theresultsshowedthatwhenceriananoparticleswithsmallsizewereusedasprecursors,theγ-Ce2S3couldbepreparedatthelowertemperatureandthebadlysinteredproductswereobtained;whenceriananoparticleswithlargesizewereemployedasprecursors,pureγ-Ce2S3wasdifficultlyobtainedevenifthetemperaturewasupto800°Candtheproductstendedtokeeptheiroriginalsize.Theheat-resistancepropertyoftheγ-Ce2S3withlargesizewasbetterthanthesmallerone,andthepureγ-Ce2S3preparedfromprecursorwithsmallsizehadagoodpigmentaryperformance.
简介:Thedifferencesofreductionbehaviorsbetweenironorelumpandpelletswerestudiedbyconductinglowtemperaturereductiondegradation,staticloadreductionanddroplettests.Thesetestssimulatedtheconditionsofreductiontemperatureandhydrogen-containinggasinCOREX.Duetoitsdensestructureandlowporositycomparedwithpellets,lumporepossessespoorreductiondegradationindex(RDI)andslowerreductionrateinearlyandmediumreactionstages,showingsignsoflowerstrength,lowersofteningandmeltingtemperatures,aswellasawidermeltingzoneandhigherΔP.Thatprovidessomebasistoexplainthephenomenaofdifferentialpressurerise,metallizationdeclineandmorestickingaftertheusageoflumporeinCOREXplant.
简介:CeO2nanoparticles(nano-CeO2p)wereaddedintolasercladdedNiCoCrAlYcoatingsonNi-basedsuperalloysubstratetoimprovethemicrostructureandproperties.Scanningelectronmicroscope(SEM),X-raydiffractometer(XRD),micro-hardnesstester,andheattreatmentfurnacewereemployedtoinvestigatetheirmorphologies,phases,micro-hardnessandthermalshockresistance,comparedwiththecoatingwithoutnanoparticlesadded.Theresultsshowedthatthemicrostructureandpropertiesofthecoatingswiththeaddition...
简介:Inthepresentstudy,sampleswereextensivelycollectedthroughoutthestainlesssteelmanufacturingprocess.Thethree-dimensionalmorphologyofinclusionswasrevealedbynon-aqueoussolutionelectrolysis.Thehighconcentrationofaluminuminferrosiliconcausedtheincrementof[Al]sinsteelandAl2O3ininclusions,whichledtothehighermeltingtemperatureofinclusions.ItwasconcludedthattheapplicationoflowAlferrosiliconandcalciumtreatmentcouldpreventtheformationofAl2O3-richinclusions.