中科大晶體學與材料結(jié)構(gòu)表征第2次作業(yè)參考答案

MSEN6414P

HomeworkII

Due1/7/2021

HereisalistofintegratedintensitiesandBragganglesasdeterminedfromthediffractionpatternshowninthefigurebelow.ThedatawascollectedusingCuKradiation(wavelength1.5405?).

a)Knowingthatthesampleissingle-phasewiththecubiccrystalsystemandthattheedgeoftheunitcella=10.4857?,assignMillerindicestoalllistedBraggpeaksbycompletingthetablebelow.

b)Basedonthesolutionof(a),determinetheBravaislatticetowhichthematerialbelongs.Explainyouranswer(25points)

a)ANSWER:

Intensity(I/Imax)

2()

dhkl(?)

{hkl}

19.30%

14.6

6.0619

{111}

10.50%

16.9

5.2417

{200}

100.00%

24.0

3.7047

{220}

12.40%

28.2

3.1618

{311}

74.80%

29.5

3.0253

{222}

83.00%

34.2

2.6195

{400}

6.00%

37.3

2.4086

{331}

6.50%

38.4

2.3421

{420}

46.40%

42.2

2.1396

{422}

1.20%

44.9

2.0170

{333}{511}

3.30%

44.9

2.0170

{333}{511}

55.60%

49.1

1.8538

{440}

4.50%

51.5

1.7730

{531}

2.80%

52.3

1.7477

{442}{600}

0.70%

52.3

1.7477

{442}{600}

21.00%

55.4

1.6570

{620}

1.60%

57.6

1.5988

{533}

27.50%

58.3

1.5813

{622}

18.60%

61.2

1.5131

{444}

1.20%

63.3

1.4679

{711}{551}

1.20%

63.3

1.4679

{711}{551}

1.60%

64.0

1.4535

{640}

24.10%

66.7

1.4011

{642}

0.90%

68.7

1.3651

{731}

2.00%

68.7

1.3651

{731}{553}

8.60%

72.0

1.3104

{800}

0.80%

73.9

1.2814

{733}

1.10%

74.6

1.2711

{820}{644}

1.10%

74.6

1.2711

{820}{644}

4.00%

77.1

1.2360

{822}{660}

8.10%

77.1

1.2360

{822}{660}

0.20%

79.0

1.2109

{751}{555}

1.30%

79.0

1.2109

{751}{555}

11.20%

79.6

1.2033

{664}

b)ANSWER:

ThecubiccrystalsystemincludesSC、FCCandBCC,BCCforbidsdiffractionfromthosewithh+k+l=odd,butthereis{111},FCCforbidsdiffractionfromplaneswithmixedoddandevenmillerindices,butthereis{311}.So,theBravaislatticebelongstoSC(simplecubic).

ShowninthefollowingpagearetheelectrondiffractionpatternandHAADF-STEMimageofSrTiO3(spacegroupPm3m,latticeparametera=3.905?)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)

ANSWER:

Themillerindicesareindicatedinthefollowingpicture.Thezoneaxisis[001].

ElectrondiffractionpatternofSrTiO3

ANSWER:

ThebiggerspotsareSratomscolumnsandthesmallerspotsareTi(O)columns.

HAADF-STEMimageofSrTiO3

ANSWER:

Oisinvisible.HAADF-STEMimageisdeterminedbyatomicnumber(Z).Thelargerthenumberofatoms,theb