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(Electron) microscopy at MTM

Discover state-of-the-art Electron Microscopy (EM) techniques like SEM, TEM, EDS, and crystallography. Learn sample preparation methods and imaging analysis for research at MTM. Enhance your skills and knowledge in electron microscopy through hands-on workshops.

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(Electron) microscopy at MTM

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  1. (Electron) microscopy at MTM SIM² workshop HiTemp group – MTM Annelies Malfliet 23 January 2013

  2. Content • Microscopy at MTM: in general • Sample preparation • In particular • SEM XL30 FEG/XL40 LAB6 • FEG-EPMA JXA-8530F • TEM CM 200 FEG • FEI Nova NanoSEM • Contact details

  3. Microscopy at MTM

  4. Overview microscopy • https://www.mtm.kuleuven.be/English/Research/Equipment/List#_Microscopy New µscope FEI Nova NanoSEM

  5. Core facility ‘Electron microscopy’ • State-of-the-art Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM)

  6. (Electron) microscopy’ • Imaging: phase distribution, particle size, topography, ... • Light Optical Microscopy (LOM) • Secondary Electron (SE) or Backscattered Electron (BSE) imaging (on SEM) • Bright-Field (BF) imaging (on TEM) • Chemical analysis: phase composition, presence of impurity elements, element distribution, ... • Energy Dispersive Spectroscopy (EDS) (on SEM/TEM) • Wavelength Dispersive Spectroscopy (WDS) (on FEG-EPMA) • Electron Energy Loss Spectroscopy (EELS) (on TEM) • Crystallography: crystal structure + texture • Electron Backscatterd Diffraction (EBSD) (on SEM) • Selected Area Electron Diffraction (SAED) or Convergent Beam Electron Diffraction (CBED) (on TEM)  Broad spectrum of equipment and preparation facilities

  7. Electron microscopy • Difference LOM – EM • Source: light vs. electrons • Optical lenses vs. eletromagnetic lenses • Eye vs. Detectors • Resolution • Most used electron microscope is Scanning Electron Microscope (SEM)

  8. SEM detectors • Typical detectors • Secondary electron detector (SE) • Good spatial resolution • Topography • Backscattered electron detector (BSE) • Strong atomic number contrast • X-ray detector • Elemental analysis • Different signals originate from different interaction volumes • Effect of voltage on interaction volume

  9. Composition analysis • Based on emission of characteristic X-rays caused by excitation from eletron beam • X-ray can be detected by: • Energy Dispersive Spectroscopy • X-ray are separated based on their energy • Result is an energy-intensity spectron with peaks • Peak position identifies the element • Height ~ its concentration (standardless quantification) • Energy resolution ~127eV • Measuring time: 10-100s (all elements measured at the same time) • Wavelength Dispersive Spectroscopy • not on SEM, but on Electron Probe Micro Analysis (EPMA) • Higher spectral resolution • Typically quantification with standards • More time consuming (5 spectrometers  up to 5 elements measured at the same time)

  10. SEM - TEM • Difference SEM – TEM • Higher eV with TEM  beam with smaller wavelength  higher spatial resolution • Observe electrons passed through (and interacted with) the sample • Much smaller and especially thinner sample electron source D = 3 mm sample screen

  11. Overview table

  12. Effort - information • Microscopy technique is mainly determined by • What information you would like to have • Size of the features of interest • Depending on technique, material and required sample ‘perfectness’, the parameters that determine effort are: • Sample preparation • Embedding: 15 min – 1 day curing/ conductive resin (under pressure) • Grinding/polishing: hard/brittle/porous/soluble in water(ethanol)/... • Conductive coating needed: thickness, homogeneity • Preventing contamination (air, moisture): storing in desiccator/vacuum/cryo cleaner/... • Removing contamination: plasma cleaner/... • Learning process • Training • Experience/practice! • Literature reading

  13. Effort - information map • In general ...

  14. Sample preparation

  15. Sample preparation at MTM • https://www.mtm.kuleuven.be/English/Research/Equipment/List#_Sample_preparation

  16. Sample preparation grinding • In general: for LOM/SEM/EBSD (room 02.33) • Cutting • Ultrasonic cleaning: remove particles from pores • Embedding with • Technovit: cures very fast (15 min) • Epofix: better infiltrates pores  better for powder or porous material (1 day curing under vacuum) • Predopress (pressure/hot mounting): harder resin  better for harder materials (also conductive powder available for conductive resin  no need for coating in case of conductive sample) • Grinding/polishing/OPS • Manual or automatic • Cooling + removing debris: water/ethanol/oil • OPS: soft/ductile materials • Different materials require different grinding + polishingprocedure  best to talk with responsible technician polishing

  17. Sample preparation • Especially for evaluation of interfaces or for soft material: Cross section ion polishing • Clean surface on large area (~ 1 mm²) • Disadvantage: more time consuming than mechanical polishing Au Ni-P Cu CP method Polishing time: 4 hours Mechanical polishing

  18. Sample preparation • Etching (for metals) • In acid, electrolytically • Coating with C/Au/Pt/Au-Pd/Pt-Pd • Au-Pd: imaging surface topography/gives higher resolution • C: Chemical analysis, mapping, EBSD • Carbon rod: better suited for thin homogeneous layer than carbon wire • For EDS/WDS: Pay attention to overlap of peaks of coating and sample • Degassing in vacuum chamber Coating units at MTM

  19. Sample preparation • TEM: more complicated + different methods depending on material • Separate TEM sample preparation room at MTM • Possible at MTM • Thin film: grinding/polishing/thinning/breakthrough (electrolytic,ion miller) • Replica method • Depositing on support grid • Ultramicrotome to cut slices • FIB • ...

  20. SEM XL30 FEG/XL40 LaB6

  21. SEM XL30 FEG • Equipment details • 0.2-30 kV • SE/BSE detector • EDS (detection from B) • Most frequent used EM • User-friendly • Many users • 1 day training • Reservation per 2 hour • 1-3 samples • Many users  highly occupied (24h/d; 7d/w) • Alternative is SEM XL40 LaB6: • similar possibilities (SE/BSE, EDS, ...) • Particle analysis software • LaB6 vs. FEG: LaB6 has larger probe diameter and less brightness, but for many applications it can be sufficient • Almost not used XL30: BSE image + EDS analysis XL40: BSE image

  22. FEG-EPMA

  23. FEG-EPMA JEOL JXA 8530F

  24. Main features • In-Lens Schottky Field Emission Gun (FEG) • 1 - 30 kV, 50 pA – 500 nA, 40 nm minimum probe size • Imaging • Electron detectors: SE + BSE • 40x to 300,000x magnification • Cathodeluminescence system • Monochromatic + panchromatic • Phase composition • EDS system: Resolution: 129 eV @ MnKa • WDS system: 5 full scanner type X-ray spectrometers

  25. FEG-EPMA: Use • Typical analysis type • Composition quantification using standards • Including minor and light elements • Mapping elemental distribution • Better spectral resolution  oxidation state of elements • 0.5-1 day/sample • Possible to let it run overnight by setting measurement points or mapping area • 3-day training • Users are through promotors of the FEG-EPMA • For external and occasional measurements, technical responsible at MTM can do the measurement

  26. Transmission Electron microscopy (TEM)

  27. TEM CM 200 FEG • Details • 20-200 kV • Resolution < nm • EDS/EELS • GATAN Tridiem Image Filter • Few users • Several day training

  28. TEM: Use • Characterization of nanoscale particles with respect to their shape, size, structure, chemical composition and distribution. • Imaging • Diffraction: crystal structure • Composition analysis • EDS • EELS: especially useful for light elements

  29. FEI Nova NANOSEM

  30. FEI Nova Nanosem • FEI Nova Nanosem • Imaging (SEM with TLD) • High resolution • Low keV imaging • ‘Pure’ samples (not coated) • Difficult samples (magnetic, non-conductive) • Chemical analysis (EDS) • Phase/ texture analysis (EBSD) • Chrystallographic characterisation • Integration with EDS  phase analysis • Plasmacleaner • Just installed, about to be operational Anodized Ti EDS+EBSD

  31. What if you would like to use one of the microscopes at MTM?

  32. Contact details • For more information: • Core facility Electron microscopy: Tom Van der Donck (tom.vanderdonck@mtm.kuleuven.be) • SEM XL30/XL40: Rudy De Vos (rudy.devos@mtm.kuleuven.be) • Annelies.malfliet@mtm.kuleuven.be • If you are advised to have a training, use the training request form available at https://ppms.info/kuleuven/treq/?pf=2

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