《材料测试技术及方法》课程教学资源（讲稿）1-材料现代分析方法_1-上课课件_06 X射线衍射分析的应用

Back reflectionsWSi261大Front refections

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The Bragg-Brentano diffractometere-2epowderdiffractometerDetector20AnalysercrystalX-ray sourceFilters2SampleholderDivergenceslitReceiving slitThe Bragg-Brentano :2 geometry is the most commonly used.Theincident beam hits the sample in angle and reflected at the same angleHence the detector is placed at 2 from the incident beam.The detectorrotates at twice angular speed than the sample

The Bragg-Brentano diffractometer The Bragg-Brentano ￾ :2￾ geometry is the most commonly used. The  incident beam hits the sample in angle ￾  and reflected at the same angle.  Hence the detector is placed at 2￾  from the incident beam. The detector  rotates at twice angular speed than the sample

Bragg-Brentano衍射几何设计原理：R1=R2=R，试样转8角，探测器转2e角（2e/偶合），或试样不动，光管转e，探测器转e（e/偶合）TubeDetectorRIR2020聚焦圆Sample测量圆要求：聚焦圆随衍射角大小而变化，衍射角越大、聚焦圆半径越小，当29=0，聚焦圆半径r=80：当20=1800时，聚焦圆r=R/2，且r=R/2sin。4

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Focusing circles forvarious geometriesG2so00SourceaeonDetectorG1Randompowdermount(planesdi,d2,d3..)Goniometerciicle5

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View of an instrumentCrystalMonochromator-DetectorX-RayTube

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TheBragg-BrentanoGeometryMono-chromatorAntiscatter-DivergenceslitslitDetector-slitTubeSample

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Crystal MonochromatorX-ray beammonochromatizationcanbeachievedby diffractionfrom singlecrystals:Si,Ge,Lidl,andgraphite2d sing=2MonochromatolSlitChromaticBeamPolychromaticDivergenceLongerwavelengthsSlitBeam-ShorterWavelengths78202e1e1MonochromatorSufficienttoseparateKaandKpNotsufficienttoseparateKa,andKa,8

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PowderPattern=Cell+Structure+Sample&InstrumentUnitCella20sAtomicStructureb26Sample&Instrument26=AiSuLMPowderPattern20

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La(Ni4.asSno.15), CuKa252.0aoooDiffractometers1.5113,Ka,131,Ka1.0032.Ka115113,Ka2131Ka032,Kz茶0.5PowderDiffractometel100.080818283845-AAA.7020304050608090100110120Braggangle,20 (deg.)CAUTIONV.K.AecharskyandP.Y.ZavaljFundamentalsofPowderDiffactiorandStructuralCharacterizationafMatenals

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