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简介:Theeffectsoflanthanum-praseodymium-ceriummischmetal(LPC)onthemicrostructureandmechanicalpropertiesofMg-Alalloywereinvestigated.WiththeadditionofLPC,anadditionalrod-likeAl11La3phasewasdepositedinthealloy.LPCgreatlyimprovesthetensilestrengthofcastMg-Alalloysbutnegativelyaffectstheelongationofcastalloysabove473K.Castalloysarestrengthenedbybothprecipitationstrengtheninganddispersionstrengtheningatambienttemperature.Whenthetemperatureexceeds473K,onlythedispersionoperatesasastrengtheningmechanism.
简介:微距镜头是定焦镜头中的精品,是近距摄影的利器。在佳能EF系列庞大的镜头群中.生产在线的微距镜头仅有四款:EF50mm/1:2.5CompactMacroMP-E65mm/1:2.8Macro:EF100mm/1:2.8USMMacro:EF180mm/1:3.5LUSMMacro.唯独这款180mm的长焦微距是“L”级。从外形来看.这款EF180mm镜头实在有点貌不惊人,黝黑的镜体苗条得体,长而不肥,硕而不壮,比佳能EF70~200mm/2.8L的个儿“矮”了7mm,仅为186.6mm;“腰围”也细了2.1mm,仅为82.5mm;滤镜口径也小了5mm.仅为72mm。1090克的重量.适配于专业机身上,平衡性显得很好。
简介:从同样渗出的镁合金Mg-3%Al-1%Zn(AZ31)营舍准备的样品在低周期的疲劳测试被利用以便调查频率依赖者疲劳生活。充分颠倒的控制紧张的紧张压缩疲劳测试在空中在1Hz和10Hz的频率被执行。微观结构被光显微镜学(OM)和扫描电子显微镜学(SEM)检验。当紧张振幅比0.2%低时,疲劳生活与装载频率展出了积极关联,并且twinning的活动在10Hz被增加。当紧张振幅比0.2%高时,重要twinning在生活被发现独立于频率的这二频率,和疲劳被观察。为这频率相关的疲劳一生的可能的原因可能由于在装载频率和紧张振幅之上的twinning的依赖。
简介:单独螺旋状的碳的材料为潜在的应用的变化吸引了许多注意。此处,单独螺旋状1,4苯撑衔接了polybissilsesquioxanenanofibers用一双enantiomers通过一条超分子的templating途径被准备。在在是为获得激活的最普通的方法的700一方法的碳化以后,精力,和TGA的试验性的条件如下被设置:在氮气氛,与20mL/min的煤气的流动率,加热5-50的率??????????????????六吗??
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.
简介:采用多孔氧化铝模板,通过直流电化学沉积法成功制备出不同掺杂浓度的Cd1-xMnxS纳米线,用XRD、SEM、HRTEM对纳米线的成分、形貌、结构进行了系统分析,并用SQUID对样品进行了磁性测量,结果表明,制得的Cd1-xMnxS纳米线呈单晶CdS纤锌矿结构,而且沿002方向有择优取向性,没有发现其它含Mn的化合物生成。从ZFC/FC曲线看出样品的居里温度接近于室温,且在低温处存在奇异现象。45K和300K下测量的的M-H曲线显示磁滞现象,测得的矫顽力分别是300Oe和100Oe,说明样品具有铁磁性。样品的紫外-可见光反射谱显示Cd1-xMnxS纳米线的吸收边并不随掺杂浓度x单调变化,而是随着掺杂量的增大能隙先减小后增大。掺杂度在1%处能隙有最小值。