(Transmission)+Electron+ Microscopy+for+Multi6Scale+ Porous+Materials+ + I6+Basic+principles+and+techniques!

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1 (Transmission)+Electron+ Microscopy+for+Multi6Scale+ Porous+Materials+ + I6+Basic+principles+and+techniques! A.BARONNET,J.BERTHONNEAU&O.GRAUBY! Aix3MarseilleUniversité CentreInterdisciplinairedeNanosciencede Marseille(CINaM) FourthWinterSchoolonMulKscalePorousMaterials January,20173Marseilles,France

2 I" "Basic"principles"of"Transmission"Electron"Microscopy"(TEM)" The$TEM$machine$ " 3Ofwhatitismadeof,andhowitworks 3SomeaWachedtechniques Sample$prepara0on$techniques$ $ $ Very$high9resolu0on$Imaging$and$diffrac0on$ " Useofthe(Fast)FourierTransform(FFT)inTEMatveryhighresoluKon " II"8"Some"applica:ons"of"high8resolu:on"TEM"on"non"conven:onal" minerals" " 3Ultrastructures*and*pores*down*to*the*atomic*scale

3 The transmission electron microscope upside down a "light" microscope in which electrons replace photons air* Fixedlens focaldistances vacuum torr Varyinglens focaldistances Moving equipment Fixed equipment high tension Kv

4 MET 200 kv (CRMCN) Complexitydueto: 3 BadelectronopKcs 3 Needofvacuum anywhereinside

5 Thecomplexelectronpath throughatem In a TEM, you may switch immediately from the direct space (image) to the reciprocal space (diffraction) crystal incidentbeam objeckve lens backfocal plane diffrackon pawern image plane

6 1.25 MV HRTEM RUCA (Anvers) Biggerandbigger? BeWerandbeWer? Image3corrected300keVHRTEM Aix3MarseilleUniversité Notsuitedfor beam3sensikve materials Topassthrough«thick»samples Desperateguy(redface))tryingtoimageanKgorite

7 Electron sources and acceleration voltage Classical tungsten filament A LaB 6 tip True Ponctual source Cold and warm cathode field emission tip coherent beam accelerakonvoltage300kev= bestagainstbeamdamages notsocoherentbeam suitedforbeam3sensikvematerials

8 Material"responses" under"electrons" Incidentbeame BackscaWerede (SEMZ3imaging ElectronBackScaWeringDiffracKon(EBSD)) X3rays EnergyDispersiveSpectroscopy(EDS) WavelengthDispersiveSpectroscopy(WDS) Augere Surfacechemicalanalysis specimen InelasKcally scawerede High3AngleAnnularDarkField (HAADF)imaging ElectronEnergy LossSpectroscopy(EELS) UnscaWerede (transmiwedbeam) Bright3Field(BF)imaging ElectronTomography Cathodaluminescence Secondarye (stdsemimaging) ElasKcally scawerede (SelectedArea) ElectronDiffracKon(SAED) Dark3Field(DF)imaging

9 Sample volumes analyzed with Electron microprobe/ TEM EDS (ATEM) Detector (λ analysis) 30 kev EDS (hν analysis) 300 kev X X Sample Sample Analysed zone 15µm QuanKtaKvedata foroxygenand above;z 8 X3rayenergy0320keV V analyzed = 10 µm 3 V analyzed = 10-6 µm 3 ATEMisasatellitetoolabsolutely*neededforcomplex materialstudiesdealingwithmicrotonanosizeofcrystals

10 ThecriKcalpointinaTEMstudy:ThesamplepreparaKon An ideal sample to enter the TEM should be: : Transparent for standard acceleration ( kv) => 0 < thickness < 500 nm for oxides (silicates) HRTEM --> 5-10 nm Manipulable (support inscribed in diam. 3 mm) Conductive or rendered conductive by metallization => amorphous C-coating Representative of the bulk of the materials => structures, microstructures, defects, chemical compositions, be saved (preparation and observation)

11 Thethin3samplepreparaKontechniques Which*materials*do*you*want*to*look*at?* * organic,*mineral,*hard,*so:,*coherent,*porous,* granular,*fibrous,*composite,,*hydroxylated,* hydrated,...* * What*do*you*want*to*see*in*this*material?* * shape,*size,*crystallinity,*chemical*composi?on,*defects,* texture,*ultrastructure,*...*

12 conduckng: Cu,Ni, Mo,Au,... TEMgridsandslots WhereshouldIputthespecimen? meshgrids "bivalve"grids 3mm + SupporKng Cfilm + amorphousc sample coakng honeycomb grid slots "stadium"slotsfor ionthinning EvacuaKonofelectriccharges=imagestability

13 The "drop deposition" technique Advantages - the simplest and quickest 3 mm - for powder characterization - (size, shape, diffraction, composition) Drawbacks -not for water soluble minerals -Particle density adjustment -drift and tilt under the beam (no clean HRTEM) - +-noise from C-film background (holey, lacey C-films- C-film wettability 1 µm Celadonite mica crystals (O. Grauby) synthekcchrysoklecharge

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15 Ultramicrotoming(conKnue) Advantages 3uniqueforpowders,fibers, synthesischarges 3chemicallyextremelyclean 3readyfortheTEM Drawbacks" 3notforbigandhardmaterials 3samplebentandcracked:avoid formicrostructureanddefect observakons 3Longtrainingforembedding samplesandtocutwell 3expensivediamondknives 3mechanicaldrirunderthee3 beam:notgoodforhrtem

16 Focusedionbeam(FIB)milling Slicingthenacreouslayer ofanoystershell3o.grauby Advantages 3samplebelowasurfacefeature readyfortem 3normaltothesurface 3sorandhard,poroussamples drawbacks Achemically*dirty:Ga&PtimplantaKons 3smearingofchemicalcomposiKon 3strongstructuraldamages

17 RecentFIBspecimenholder 3mm halfslot

18 A$phytolithe:a*mesoporous*material*made*of*amorphous*silica* * * * *Storage*of*Si*by*plants* Pt Thinnedwindow Pt welded Nanopillar SeeJérémieB.tomorrow forelectrontomography ofthisslice

19 Theroyalroad From*the*rock*to*the*atomic*image*by*TEM* diamond saw therockslice Thin3secKon facilityofa geological laboratory uncoveredrockslate doubleface1µmpolish 30850"µm3thick Thermofusibleresin (Lakeside,crystalbond) glassplate thinseckon sugarpiece 300µm diamond wire saw polishing machines aspecialthinseckon

20 Crossed"nicols"light"microscopy"to"place"the"slots thinseckon 3 recognizethemineralsfromtheir opkcalproperkes(refringence& 3 Birefringence) 3 crystallographicorientakonwith15 accuracy(forhrtem) microdrillingaroundtheslot andmelttheglueunderneath(<200 C) Araldite slot film Rockslice glue Glassslide <50µm readyforthepipsmilling detachwithatwizzerandwashthegluewithalcohol

21 Thetopforhigh3resoluKon electronmicroscopy(hrtem) ofmostminerals Ion3millingsystems Precision ion polishing system (PIPS) Ar+ ions, 5 -->2 kev, two guns 7-4 incidence. Polishing time 0.5h to 5 days for 50µm - thick thin section Advantages 3largeandthinsurfacestolookat 3wedge3shapedsample:extra3thinzones 3gentleheaKng 3highmechanicalstability 3reasonabledamages(amorphisaKon) Drawbacks 3polluKonbyspuWering:grid, specimenholder 3needstobetrainedforopKmum use

22 Aroundthehole:hoursofTEMexploraKontocome 1mm Ultrathinwedgearoundtheholeborder OnlypartsuitableforTEM

23 PreparaKonofTEMspecimens: Thesamplingproblem:toberepresentaKve forupscalingtobeuseful "All*thinned*samples*of*the*Earth*crust*for*TEM*enter*a* thimble*while*the*crust*volume*is*roughly*75.*10 7 *km 3.* ** * *So,*be*careful*with*sampling!* * David*Veblen,** * * * * * * * *Johns*Hopkins*University,*Bal?more * * *

24 Electron"diffrac:on"by"crystals" " Thedirectlauce(blue)andthereciprocallauce(green) A23Dcase DiffracKon pawern HRTEM image Lauce fringes Perpendicularrows Inversemetrics

25 Electron diffraction by crystals Bragg's law 2d (hkl) sinθ = nλ andforhigh3energyelectrons: 2d (hkl) θ nλ 1/λ θ < >only lattice planes // to the incident beam are diffracting very thin specimen ---> elongation of reciprocal lattice nodes --- >relaxation of Bragg's conditions > many reflections at a time

26 Slight curvature of the Ewald's sphere (R= 1/λ) intersecting the 3D arrangement of the reciprocal lattice (RL) The SAED pattern = Visualisation of sub planar sections of the reciprocal lattice Tilting the sample in diffraction mode is exploring the RL in 3-D Double tilt, high-resolution, specimen holder ± 15 Procedure of alignment of a single crystal: find a crowdy SAED, put the zero-order Laue zone(zolz) perfectly symetrical around the transmitted beam by centring the first - order Laue zone (FOLZ) when visible! FOLZ ZOLZ

27 MicrodiffracKonpaWernsofsomestatesofmaWer amorphous polycrystalline singlecrystal+disorder cylindrical lauce Quasicrystal seenalonga 23foldaxis B.Devouard

28 Towardveryhigh3resoluKonTEM(HRTEM) Introducing Atomicstructureimages

29 TheobjecKvelensistheonlyonethatmaWers In its focal plane, the diffraction pattern of the object!! In its image plane, the microscope performs!!a Fourier photosummation! A biperiodic image = discrete sum (troncated) of sine variations of fringe contrast along diffraction vectors The Graal: the charge density projection! of the crystal structure!! In the trigonometric form:!! ρ(y,z)= k l F 0kl cos 2π (ky + lz +α 0kl )!! = F 000!! + F 010 cos 2π (y +α 010 ) + F 020 cos 2π (2y+α 020 ) +...!! + F 001 cos 2π (z+α 001 ) + F 002 cos 2π (2z+α 002 ) +...!! + F 011 cos 2π (y+z+α 011 ) + F 022 cos 2π (2y+2z+α 022 ) +...! Amplitude Wavelength Phase

30 Point-to-point resolutions at CINaM: 2.8 Å for 200 kv TEM 1.6Å or 2.1Å for 300kV TEM 0.5Å somewhere in the world Electronic image = recombination of discrete diffracted beams that keep amplitudes and phases of diffracted waves not a «shadow» image but: dynamical diffraction + phase offsets due mainly to spherical aberration The Scherzer defocus (critical underfocusing) roughly compensate for those phase offsets within the transfer window toward the structure image d r = 0, 65λ 3 / 4 Cs 1/ 4 sin χ Fenêtre résolution R0 0,1 0,2 0,3 0, ,3 diaphragme de contraste R (Å -1 ) d (Å)

31 Outoffocus Scherzerdefocus Samethickness

32 CorrectphasesareessenKeltogetacorrectstructureimage ObjecKve Aperture Backfocal plane DiffracKon vectors Wave shir

33 VeryHRnumericalscan oftheimage«nuclear»film circularseleckon FFTprocessing (FIJIapplicaKon) l* 04l* 02l* 00l* 5nm Recorded DiffpaWern Quasi3atomicimageof thebioktemicaseen along<100> FFTnowrealisKc subsktutetothe microdiffrackon

34 Summingupprogressively TheFourierterms Lauceimage Thehigh3resoluKonTEM Imageofa2M1phengite 00l* 02l* 04l* Fromlauceimages to structureimages Quasistructureimage

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37 Towardthe3DviewwithaTEM SeeTimm*Weitkamp* wednesdayevening Stereoimaging Electrontomography (JérémieB.tomorrow) SeeJérémie*Berthonneau* tomorrow