上海交通大学：《Structural and Chemical Characterization of Materi》教学资源_EM1.2_Specimen preparation for TEM

Specimen preparation for TEM A well-prepared specimen is half done！ 1

Specimen preparation for TEM A well-prepared specimen is half done! 1

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Specimens used in TEM oo6o可 φ3mm 3

Specimens used in TEM 3 3 mm

specimen 1A 1B IC ID nm 5.nm Microscopy and Microanalysis Volume 14/ Supplement S2/August 2008,pp 382-383 4

4 Microscopy and Microanalysis / Volume 14 / Supplement S2 / August 2008, pp 382-383 specimen

Why should the specimens be thin? Electron transparency ·Depth of field Chromatic aberration limited resolution Conventional TEM HRTEM/EELS Thickness(nm) <100 <20 5

Why should the specimens be thin? • Electron transparency • Depth of field • Chromatic aberration limited resolution 5 Conventional TEM HRTEM/EELS Thickness (nm) <100 <20

Challenge How to prepare electron transparent specimen(20-100 nm thick)without introducing artifacts? Providing adequate facilities are available,there is no real barrier to the preparation of good,thin- film specimens from any engineering material, and no excuse whatsoever for wasting time on the examination of a poor specimen in the microscope. -From David Brandon and Wayne D.Kaplan,Microstructural characterization 6 of materials

Challenge Providing adequate facilities are available, there is no real barrier to the preparation of good, thin￾film specimens from any engineering material, and no excuse whatsoever for wasting time on the examination of a poor specimen in the microscope. -From David Brandon and Wayne D. Kaplan, Microstructural characterization of materials 6 How to prepare electron transparent specimen (20-100 nm thick) without introducing artifacts?

Bulk sample Thin film Fibers and powders Reduce to disk Look through: Support on (3-mm diameter plan view grid or film or smaller)with electron-transparent Look parallel Make bulk-like regions to surface: cross section Look at surface at glancing angle: reflection FIGURE 10.2.Flow chart summarizing the different sample geometries you may encounter. 7 From David B.Williams and C.Barry Carter,Transmission electron microscopy

7 From David B. Williams and C. Barry Carter, Transmission electron microscopy

Particulate materials Powders,nanoparticles,nanowires etc. Grinding (if necessary)and dispersion in solvent Drip on carbon coated grids Van der Waals cohesion Strong enough for nano- particles 8

Particulate materials • Powders, nanoparticles, nanowires etc. • Grinding (if necessary) and dispersion in solvent • Drip on carbon coated grids • Van der Waals cohesion – Strong enough for nano￾particles 8

Particulate materials Silver nanoparticles synthesized free of stabilizing ligands.from Quantum plasmon resonances of individual metallic nanoparticles,Jonathan A.Scholl,Ai Leen Koh Jennifer A.Dionne,Nature 483,421-427(22 March 2012) 3 nm 5.nm Nb-O-F compound,specimen prepared by pulverization 9

Particulate materials 9 Silver nanoparticles synthesized free of stabilizing ligands. from Quantum plasmon resonances of individual metallic nanoparticles, Jonathan A. Scholl, Ai Leen Koh & Jennifer A. Dionne, Nature 483, 421–427 (22 March 2012) Nb-O-F compound, specimen prepared by pulverization 3 nm

Bulk materials Thin foil It isn't realistic to thin the specimen mechanically to electron transparency. 10

10 Bulk materials Thin foil It isn’t realistic to thin the specimen mechanically to electron transparency