Optical Properties of diamond.docx
- 文档编号:30660014
- 上传时间:2023-08-19
- 格式:DOCX
- 页数:11
- 大小:255.28KB
Optical Properties of diamond.docx
《Optical Properties of diamond.docx》由会员分享,可在线阅读,更多相关《Optical Properties of diamond.docx(11页珍藏版)》请在冰豆网上搜索。
OpticalPropertiesofdiamond
OpticalProperties
PROPERTY
PolycrystallineCVDdiamond
SinglecrystalCVDdiamond
RefractiveIndex
2.432forL=0.5um
2.432forL=0.5um
dn/dt
9.6x10-6K-1
9.6x10-6K-1
AbsorptionCoefficient8-12um
AbsorptionCoefficient3-5um
<0.07
Min0.8at3.7um
Emissivityat10um
0.20at573K
0.03at773K
Integratedforwardscatter8-12um
Integratedforscattervisible
0.1-0.7%
<4%
<0.6%
<0.6%
Transmission8-200 um(1mmthick)
Transmission633nm(1mmthick)
71.4%
>64%
71.4%
>66%
Notethemaximumtransmissionof71.2%resultsfromreflectionatthetwodiamond/airinterfacesbecauseofthehighrefractiveindexofdiamond.
ThermalProperties
PROPERTY
PolycrystallineCVDdiamond
SinglecrystalCVDdiamond
ThermalConductivity
@20DegC(W/m.K)
2000*
>2000
ThermalConductivity
@200DegC(W/m.K)
500-1500
>1000
ThermalDiffusivity(cm2/s)
2.8-11.6
10-12
ThermalExpansionCoefficient
100DegC at250DegC(ppm/K)
500DegC(ppm/K)
750DegC(ppm/K)
1.21
3.84
4.45
1.21
3.84
4.45
ThermalShockFigureofmeritW/m
>1100
*OpticalGradeCVD
MechanicalProperties
Thehighstrengthofthecarbontocarbonbondisthesourceoftheexceptionalmechanicalpropertiesofdiamond.Dislocationoftheatomsisdifficultandconsequentlydiamondisthehardestknownsubstance.
Onanymeasurementscale,diamondisthehardestknownmaterial.Mohshardnessisascratchhardnesstestforsolidsrelatedtoindentationhardness.TherelationshipbetweentheMohsnumber,M,andtheindentationhardness,H,measuredinkg/mm2is
LogH=0.2M+1.5
Whilethereisreasonable"intervalequality"betweenthefirst9integersontheMohsscale,theintervalbetween9(siliconcarbide,aluminiumoxide,tungstencarbide)and10(diamond)representsamuchlargerdifferenceinindentationhardnessthanasingleunitonthisscalewouldsuggest.
Indentationhardness(Knoopscale).
Forcrystallinesolids,theKnoopindenterisconsideredtobemostaccurate.Indentationhardnessvariesaccordingtocrystallographicdirection.Forthe{001}diamondsurfacethevalueis570-10,400kgmm-2andwithnormalloadsof500g,1kgand2kg. Fordiamond({111}surface<110>direction,500gload),theKnoophardnessis9000kgmm-2;forcubicboronnitrideunderthesameconditionsandorientationthefigureis4500kgmm-2whichisthenexthardestmaterialtodiamond.
Inaddition,themechanicalpropertiesofCVDdiamondwillvaryaccordingtothegradeofthematerialanditsapplicationarea.
SummaryofMechanicalPropertiesforCVDdiamond
PROPERTY
POLYCRYSTALLINECVDDIAMOND
SINGLECRYSTALCVDDIAMOND
HARDNESS(GPa)
85-100
70-100
FractureToughness(MPa)
5.5
3.4
TensileStrength*(MPa)
400 800
(growth)(nucleation)
2000-3000
Compressivestrength
9.0
9.0
RainImpactDTV2mmdropsize
525ms-1
Sanderosionat80ms-1C25/52sand
0.18mgkg-1
*dependsongradeofpolycrystallinediamond
Electronicproperties
Diamondhasimmensepotentialinelectronics.Intrinsicdiamondhasacombinationofhighmobility,breakdownandthermalconductivitywhichresultsinthelargestJohnsonandKeyesfiguresofmeritobtainedforanymaterial.Thesefigurescombineamaterial'selectricalandthermalpropertiestoindicatedtheirrelativecapacitytohandlehighpowerorhighspeeddeviceoperation.
PROPERTY
PolycrystallineCVDdiamond
Electronicgrade
SinglecrystalCVDdiamond
Electronicgrade
Holemobility(cm2/Vs)
1,000
3,800
Electronmobility(cm2/Vs)
1,800
4,500
Carrierlifetime(ns)
~1-10
~2,000
Voltagebreakdown(MV/cm)
~0.5
~4
Chargecollectiondistanceum
~250at1V/umfield
CCDisthicknesslimited*
Bandgap(eV)
5.47
5.47
Electronsaturationvelocity(cm.s-1)X107
2
2
Johnson'sfigureofmerit
8,200
Keyes'figureofmerit
32
Baligasfigureofmerit
17,200
*Inavailablesizes,eg500umthick
Diamonddoping
ThemostcommondopantsusedinCVDdiamond,withtheirassociatedionizationenergies,are:
-
Element
ActiviationEnergy(eV)
n-type
Nitrogen
1.70
Phosphorous
0.60
p-type
Boron
0.37
Electrochemistry
BoronDopedSingleCrystalDiamond
Borondopeddiamondisuniqueasanelectrochemicalmaterialforanumberofreasons:
∙Thematerialisverychemicallyinertandiscapableofwithstandingveryaggressivechemicalenvironments.
∙Relatedtoitschemicalinertness,itcanoperateoveraverywidepotentialwindowwithoutparasiticsurfacereactionseitherbreakingdownthesolventorcausinglocalsurfacereactionswiththesolute.Assuch,inelectrochemicalsensingapplicationsitenablesthesolutetobefullyandaccuratelycharacterised,andinprocessingapplicationsitenablesefficientelectrochemicalprocessingofthesolute,withoutexpensiveparasiticreactions,suchasthebreakdownofwaterinaqueoussolutions.
∙Thesurfaceofdiamondisnotpronetofouling,enablinglongreliableoperationwithoutmaintenance,andincircumstanceswherefoulingdoesoccuritcanbeeasilyremovedeithermechanicallyorchemicallywithoutdamagingtheelectrode.
PropertiesofBoronDopedSingleCrystalDiamond
∙WidePotentialWindowinAqueousSolution
∙Oxygen ReductionSignificantly Retarded
∙LowBackgroundCurrents
∙CorrosionStabilityinaggressivemediaandathightemperaturesandpressures
∙UniformElectricalConductivity
Note:
-Theelectrochemicalperformanceofborondopeddiamond is dependantonthesurfacefinish.
ChemicalProperties
Diamondischemicallyinertand(duetothehighstrengthofthecovalentbonds)ishighlyresistanttochemicalattackbyacidsorotherchemicalreagents.Theonlyexceptionsarematerialsthatathightemperaturesactasoxidisingagents-theseprovidetheonlyeffectivewaytoattackdiamondatnormalpressuresandtemperatures(belowabout1000DegC).Salts,suchassodiumnitrate,areknowntoattackdiamondwheninthemoltenstateattemperaturesaslowas450DegC.Inthepresenceofoxygen,diamondstartstobeoxidisedataround650DegC.
Theonlyotherpossibleformofchemicalattackisbytwogroupsofmetals.Themembersofthefirstgrouparestrongcarbideformers,andincludetungsten,tantalum,titaniumandzirconium.Athightemperatures,thesewillreactchemicallywithdiamondtoformtheirrespectivecarbides.Thesecondgroupofmetalsincludesiron,cobalt,manganese,nickelandchromium(andalsotheplatinumgroupofmetals).Inthemoltenstatethesemetalsaretruesolventsforcarbon.
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- Optical Properties of diamond