中科大晶体学与材料结构表征第2次作业参考答案.docx
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中科大晶体学与材料结构表征第2次作业参考答案.docx
MSEN6414PHomeworkIIDue1/7/20211. HereisalistofintegratedintensitiesandBragganglesasdeterminedfromthediffractionpatternshowninthefigurebelow.ThedatawascollectedusingCuKaradiation(wavelength1.5405A).a) Knowingthatthesampleissingle-phasewiththecubiccrystalsystemandthattheedgeoftheunitcella=10.4857A,assignMillerindicestoalllistedBraggpeaksbycompletingthetablebelow.b) Basedonthesolutionof(a),determinetheBravaislatticetowhichthematerialbelongs.Explainyouranswer(25points)a入a) ANSWER：d：庐M/二管Intensity(1)20(o)dhkl(A>hkl19.30%14.66.061911110.50%16.95.2417200100.00%24.03.704722012.40%28.23.161831174.80%29.53.025322283.00%34.22.61954006.00%37.32.40863316.50%38.42.342142046.40%42.22.13964221.20%44.92.01703335113.30%44.92.017033351155.60%49.11.85384404.50%51.51.77305312.80%52.31.7477442600)0.70%52.31.747744260021.00%55.41.65706201.60%57.61.598853327.50%58.31.581362218.60%61.21.51314441.20%63.31.46797115511.20%63.31.46797115511.60%64.01.453564024.10%66.71.40116420.90%68.71.36517312.00%68.71.36517315538.60%72.01.31048000.80%73.91.28147331.10%74.61.27118206441.10%74.61.27118206444.00%77.11.23608226608.10%77.11.23608226600.20%79.01.21097515551.30%79.01.2109(75155511.20%79.61.2033664b) ANSWER:ThecubiccrystalsystemincludesSC、FCCandBCC,BCCforbidsdiffractionfromthosewithh+k+1=odd,butthereis111,FCCforbidsdiffractionfromplaneswithmixedoddandevenmillerindices,butthereis311.So,theBravaislatticebelongstoSC(simplecubic).2. ShowninthefollowingpagearetheelectrondiffractionpatternandHAADF-STEMimageofSrTiOs(spacegroupPm3m,latticeparametera=3.905A)alongacertainzoneaxis.a) Inthediffractionpattern,indicatethemillerindicesofthethreespotspointedbyarrows.(15points)Whatisthezoneaxisalongwhichthediffractionpatternwastaken?(5points)b) Opentheattached.ciffileinVESTAorCrystalMaker,androtatetheatomicmodeltothezoneaxisfoundin(a).ComparetheatomicmodelwiththeHAADF-STEMimage,andindicatewhichspotsintheimagecorrespondtoSratomiccolumns,andwhichtoTi-Ocolumns.(10points)c) Alongthezoneaxisidentifiedin(a),someatomiccolumnsintheSrTiO3structuralmodelcontainOonly.ArethesecolumnsvisibleintheHAADF-STEMimage?(5points)NameoneSTEMimagingmodethatmaybettervisualizeO.(5points)Forbothquestions,explainyouranswers.(10points)a) ANSWER:Themillerindicesareindicatedinthefollowingpicture.Thezoneaxisis001.ElectrondiffractionpatternofSrTiO3b) ANSWER:ThebiggerspotsareSratomscolumnsandthesmallerspotsareTi(O)columns.HAADF-STEMimageofSrTiO3c) ANSWER:Oisinvisible.HAADF-STEMimageisdeterminedbyatomicnumber(Z).Thelargerthenumberofatoms,thebrighterthespot.Asaresult,thenumberofOatomistoosmalltobevisible.ABFSTEMissuitableforOelement,becauseit,scontrastisproportionaltoZ1/3.
