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Characterisation of porous materials using Electron Microscopy

Characterisation of porous materials using Electron Microscopy. Dr. Patricia J. Kooyman DelftChemTech / National Centre for HREM Delft University of Technology p.j.kooyman@tudelft.nl. Bulk (structural) information. Transmission Electron Microscopy (TEM). Surface information.

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Characterisation of porous materials using Electron Microscopy

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  1. Characterisation ofporous materials usingElectron Microscopy Dr. Patricia J. Kooyman DelftChemTech / National Centre for HREM Delft University of Technology p.j.kooyman@tudelft.nl

  2. Bulk (structural) information Transmission Electron Microscopy (TEM) Surface information Scanning techniques Scanning probe microscopy: STM, AFM Scanning Electron Microscopy (SEM)

  3. ElectronMicroscopyTechniques

  4. What is TEM? • A technique using high-energy electrons to obtain a 2D projection of a 3D structure. • The highest possible resolution is currently about 0.1 nm.

  5. Electron-solid interactions TEM EDX Specimen Element Elastically specific X-rays scattered Secondary electrons electrons ED / HREM Visible light Incident electrons Direct beam Backscattered SEM Inelastically electrons scattered Auger electrons electrons EELS

  6. The SEM

  7. SEMTEM particle morphology(particle morphology) surface morphology2D projection - internal structure elemental analysis elemental analysis 5 nm - 500 micron1 nm - 5 micron electr backscatter diffr electron diffraction EELS

  8. General features of SEM • Electrons interact with specimen • High vacuum necessary • Specimen should be conducting (sputter with Au) • Particle morphology • Surface imaging • Elemental analysis • Resolution ~ 1 nm

  9. General features of TEM • Electrons interact with specimen • High vacuum necessary (~ 10-7 Torr for HREM) • Specimen should be very thin (< 10 nm for HREM) • 2D projection of 3D structure • Structural analysis • Elemental analysis • Resolution ~0.1 nm

  10. Optical systems http://www.vcbio.sci.kun.nl/fesem/info/

  11. Optical system of a TEM specimen focus plane for diffraction intermediate 1 focus plane for image image cross-section TEM intermediate 2 final image imaging diffraction

  12. Electron diffraction (TEM) MFI HR bright-field image ED pattern Fourier transform

  13. Electron backscatter diffraction(EBSD - SEM) High quality EBSD pattern

  14. Electron backscatter diffraction (EBSD - SEM) MFI SEM image Stavinski et al. Angew. Chem. 120 (2008) 5719 EBSD patterns spots A and D Indexed EBSD patterns spots A and D

  15. TEM imaging centered dark field HREM bright field dark field

  16. Ru/aluminaSoede, DUT Bright field image

  17. d-spacing Ru/aluminaSoede, DUT Electron Diffraction Pattern

  18. Dark field image with Ru-diffracted beam Bright field image Ru/alumina Soede DUT

  19. TEM - information obtained • Method Information • * bright-field * microstructural • imaging nb: 2D info of 3D • * high resolution structure! • imaging * electron diffraction * crystallographic pattern (cf XRD) * generated X-rays *elemental analysis (EDX)

  20. Sample preparationpowders / suspensions / sols

  21. Samplepreparationpowders / suspensions / sols

  22. Sample preparation: crushing suspension in eg ethanol crush deposit on grid with carbon film 3 mm

  23. Microgrid carbon film Quantifoil

  24. MOF on microgrid carbon film Gascon, TUD

  25. TEM Fe-MFI Taboada, TUD

  26. SEM of same sample

  27. Samplepreparationone-piece samples

  28. Samplepreparationone-piece samples

  29. Sample preparation: ion milling specimen polishing holder polishing 5-10 micron thick Ar ion beams

  30. Sample preparation: ultramicrotomy catalyst core slices < 50 nm glue mantle diamond knife slices on grid water bath also possible at liquid nitrogen temperature

  31. Ultramicrotomy powder specimen ultramicrotomed specimen

  32. MCM-41 mesoporous zeotype material pore size > 3 nm possibility to convert larger molecules different phases are found

  33. MCM-41

  34. HPA/MCM-41 fresh Verhoef, TUD Ordered Disordered

  35. HPA/MCM-41 used

  36. HPA/MCM-41 XRD patterns

  37. Fe-Si-SBA-15: TEM Li, Hensen, TU/e J. Phys. Chem. B 110 (2006) 26114 -26121

  38. Fe-Si-SBA-15: EDX

  39. Pt-Rh/alumina (Grisel, UL) Particle size distribution? Alloying? Use TEM/HREM in combination with EDX

  40. overview cluster Pt-Rh/alumina (Grisel, UL)

  41. full scale enlarged scale Pt-Rh/alumina (Grisel, UL)

  42. optimal imaging zeolite 5 degree tilt zeolite amorphised Pt/zeolite

  43. TiO2 in TUD-1 Hamdy-Saad, TUD Peeters, TUE

  44. 3D TEM Reconstruct 3D structure from tilt series at different angles of the same area of material “Electron Tomography”

  45. 3D TEM Procedure: Acquire tilt series of a particle from +70 to -70 degrees at 1 or 2 degrees steps Recombine these images to 3D reconstruction Depict as slices through the particle or as volume rendering

  46. 2D TEM - loss of information

  47. 3D TEM - cycle

  48. 3D TEM - result Single image from series Slice of reconstruction Jansen et al., Utrecht University

  49. New mesoporous mat: SEM

  50. New mesoporous mat: TEM MSU-3 Prouzet et al., J.Mater.Chem. 12 (2002) 1553

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