Conventional Transmission Electron Microscopy. Introduction. Text Books. Text Books. EMSE-509 CWRU Frank Ernst

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1 Text Books Conventional Transmission Electron Microscopy EMSE-509 CWRU Frank Ernst D. B. Williams and C. B. Carter: Transmission Electron Microscopy, New York: Plenum Press (1996). L. Reimer: Transmission Electron Microscopy, Vol. 36, 4 th edition (Springer Series in Optical Sciences), Berlin: Springer (1997). G. Thomas and M. J. Goringe: Transmission Electron Microscopy of Metals, New York: Wiley (1979). P. B. Hirsch, A. Howie, R. B. Nicholson, D. W. Pashley and M. J. Whelan: Electron Microscopy of Thin Crystals, 2 nd edition, Huntington, New York: Krieger (1977). 1 2 Text Books B. Fultz and J. M. Howe: Transmission Electron Microscopy and Di ractometry of Materials, 2 nd edition, Berlin: Springer (2002). Marc De Graef: Introduction to Conventional Transmission Electron Microscopy, Cambridge: Cambridge University Press (2003). P. J. Goodhew: Specimen Preparation for Transmission Electron Microscopy of Materials, New York: Oxford University Press (1984). Introduction 3 4

2 Materials Science and Engineering Importance of the Microstructure Materials Science Structural Materials Functional Materials Materials Engineering 5 6 Microscopy! Microstructure: Bronze 7 8

3 Crystal Structures Microstructure: 9 10 Superconducting Ceramics: 2 11 Superconducting Ceramics: 4 12

4 Superconducting Ceramics: 8 Superconducting Ceramics: Resolution Resolving Power of a Microscope? definition of resolving power smallest distance two details must have in order to appear separate often briefly called magnification: resolution only meaningful with sufficient resolution up to where can you resolve two points? 15 16

5 Interference Interference Pattern as a Function of Object d ϕ 1 ϕ Abbe Theory Abbe: Include the 1 st Maximum! zero-order maximum corresponds to cone with semi-angle 1 (angle between axis and first-order di raction maximum) for semi-angle, this implies Sin[ ] = Sin[ 1 ] = d inner part of zero-order cone corresponds to simple, spherical wave emitted from single hole if only inner part of zero-order cone passes through aperture, the points will not be resolved Sin[ϕ 1 ]= λ D = Sin[ϕ] = D = λ Sin[ϕ] λ 19 20

6 Abbe Theory Resolution Limit Result to resolve object points, at least the first minimum must also pass microscope aperture must capture at least entire zeroorder cone! resolution limit: minimum distance d 0 between two object points required to let entire zero-order cone pass since Sin[ ] 1, the resolution limit is d 0 = Sin[ ] Why Electron Microscopy? Electrons Propagate Like Waves superposition interference amplitude: magnitude + phase = 0 Exp[2 ikr ] (plane wave) λ = h p superposition of waves may locally reduce intensity di raction Louis de Broglie,

7 Electrons Propagate Like Waves The Proof The Transmission Electron Microscope 50kV Two slits Fluorescent screen 1931 Ernst Ruska Filament Electrons Vacuum Electron diffraction fringes on the screen Scanning Electron Microscopy TEM TEM versus SEM images interior, provides di raction patterns coherent imaging, atomic resolution possible scanning possible (STEM) SEM images surface, enables channeling patterns incoherent imaging, atomic resolution?? Both: microanalysis 27 28

8 Imaging the Interior Electron Diffraction specimen edge, electron transparent hole electron beam specimen ø = 3 mm 0.2 mm objective lens Conventional TEM 31 CTEM: CdSe Layer for the Retina of an Artificial-Eye 32

9 HRTEM versus CTEM Experimental HRTEM Analytical TEM Spectrometry 35 ARM Stuttgart Atomic Resolution Microscope 36

10 Tecnai F30 at Case Zeiss Libra 200FE at CWRU 300 kv = 1.97 pm Field-Emission Gun Energy Filtering High-Resolution Analytical TEM/STEM 200 kv = 2.51 pm Field-Emission Gun Side-Entry Conventional Analytical TEM/STEM Conventional TEM Example for Synergy of TEM Techniques: Cu2O/Si Interfaces 39 40

11 Orientation Relationship Orientation Relationship Bright-Field Image HRTEM 43 44

12 ESI Oxygen Map HAADF STEM BF ESI XEDS Linescans HAADF XEDS 47