粉末衍射基本原理课件.ppt

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1、RietveldRefinement---GeneralStructureAnalysisSystem(GSAS)contentIntroductionoftheGSASTodeducetheintensityofthereflectedray(Intheory)HowRMworks?ThepoliciesoftherefinementThepracticesabout(Sr1-xCax)3Ru2O7refinement(Includingthesampleswithsinglephaseandtwophases)-astandardtrea

2、tmentofpowderdiffractiondatatomakethefinalstructuralmodelachievetheacceptedcriterion;-abestknownmethodthatfullymakesuseofthestep-modescanneddatatodigoutalotofstructuralandotherinformation;-aprocedureforstructuralsolutioninnature.IIntroductionoftheGSAS1.WhatisaRietveldRefine

3、ment?LatticeParametersQuantitativephaseAnalysisAtomicPositionsGrainsizeAtomicOccupancyIncommensurateStructureDebyeTemperaturesStructurefactorsCrystallinityPhasetransitionsMagneticstructures……2.WhatcanwegettoperformaRietveldrefinement?IntroductionoftheGSAS3.HistoryReviewRiet

4、veldoriginallyintroducedtheProfileRefinementmethod(Usingstep-scanneddataratherthanintegratedPowderpeakintensity)(1966,1967)RietvelddevelopedfirstcomputerProgramfortheanalysisofneutrondataforFixed-wavelengthdiffractometers(1969)Malmos&ThomasfirstappliedtheRietveldrefinementm

5、ethod(RR)foranalysisofx-raypowderdatacollectedonaGinierHaggfocusingCamera(1977)Khattack&CoxfirstappliedtheRRtox-raypowderdatacollectedonadiffractometer(1977)ConferenceonDiffractionProfileAnlysisSponsoredbyIUCrinPoland,suggestedtheterm“RietveldMethod”(1978)WilesandYangdevelo

6、pedageneralcomputerprogram(D.B.W)forbothx-ray&neutrondiffractiondata(fixedwavelength)(1981)VonDreele,JorgensenandWindsorextendedtotheprogramtotheneutrondiffractiondata(1982)Fitchetal,193refinedparameters,UO2DAs.4D2O(1982)IntroductionoftheGSASAminoffPrize,Stockholm,1995H.M.R

7、ietveldActacrystallogr.,22,151(1967).H.M.Riveted,J.Appl.Crystallogr.,2,65(1969).IntroductionoftheGSASIITodeducetheintensityofthereflectedray1.Thomsonformula(oneelectron)TodeducetheintensityofthereflectedraySo,thetotalscatteringintensityIeisTodeducetheintensityofthereflected

8、ray2.ThescatteringintensityofXraybyoneatomincidentrayscatteredrayTodeducetheintens