FEI Tecnai G2 F20

The Tecnai G2 F20 is a versatile field emission transmission electron microscope ideally suited for studying a wide range of solid state materials. This analytical instrument, which is equipped with a compustage-driven side-entry double-tilt goniometer stage and an assortment of specimen holders, is optimised for imaging at medium resolution or for performing elemental microanalysis.
Equipped with a post-column GATAN image filter (GIF) and an energy dispersive X-ray (EDX) detector, the setup allows for a variety of experiments such as conventional imaging and diffraction, recording of bright- and dark-field scanning electron transmission electron microscopy (STEM) images, or acquiring elemental maps extracted from energy electron loss spectra (EELS) or EDX signals. Addionally the instrument is equipped with a NanoMegas ASTAR system for Precession Electron Diffraction (PED).

Typical Applications and Limitations of Use

Since the FEI Tecnai G2 F20 is not equipped with any Cs corrector its resolution is limited to 2.4 Å in TEM mode (point to point resolution) and 1.9 Å in STEM mode. However, the large tilt angles of the specimen stage and the EELS and EDX capabilities make this instrumenta attractive for medium resolution work, e.g. for analyses of diffraction contrast and diffraction patterns or for determination of the chemical composition on the nanometer scale by electron energy loss spectroscopy, energy filtered transmission electron microscopy (EFTEM) or energy dispersive X-ray analysis. The NanoMegas ASTAR system combining Precession Electron Diffraction with orientation or phase mapping allows the characterisation of crystalline materials resulting in maps with a special resolution down to 1 nm.

Sample Environment

Samples are investigated either under room temperature or liquid nitrogen cooling conditions at a vacuum level of about 10–8 mbar. Besides this standard setup, the sample environment can be adapted to various conditions, e.g. the thermal treatment or the application of external electric or magnetic fields to samples, making use of a wide portfolio of in situ TEM holders available through the ER-C user services. In general, all types of materials can be investigated which do not harm the microscope and the specimen holders and which obey the ER-C’s safety rules.

Technical Specifications

Electron acceleration voltage120 kV … 200 kV
TEM – point to point resolution at 200 kV2.4 Å
TEM – information limit at 200 kV1.4 Å
TEM – objective lens Cs1.2 mm
TEM – objective lens Cc1.2 mm
TEM – magnification range25 kx … 1030 kx
STEM – HAADF resolution1.9 Å
STEM – probe Cs1.2 mm
STEM – probe Cc1.2 mm
STEM – magnification range150 x … 230 Mx

Specimen Stages

Double tilt low background holder± 40 °
High field of view single tilt tomography holder± 70 °
Dual-axis tomography holder± 50 °
On axis rotation tomography holder360°
Further in situ specimen stages available 

Detectors

UltraScan 1000P (2k x 2k) charge coupled digital camera equipped with a standard phosphor scintillator. (Gatan)

Tridiem 863P post column image filter (GIF) with fully 2nd order and partially 3rd order corrected prisms yielding a total system energy resolution of 0.65 eV or better at a maximum field of view of 15 µm for imaging and 100 mR for diffraction analyses. (Gatan)

High angle energy dispersive X-ray detector with a resolution of 136 eV or better for Mn K-alpha radiation. High angle energy dispersive X-ray detector with a resolution of 136 eV for Mn K-alpha radiation.

Model 3000 HAADF detector. (Fischione)

Instrument related Publications

Rieger T, Luysberg M, Schäpers T, Grützmacher D and Lepsa MI. Molecular beam epitaxy growth of GaAs/InAs core-shell nanowires and fabrication of InAs nanotubes. Nano letters. 12 (2012) 5559-5564. doi:10.1021/nl302502b.

Imlau R, Kovács A, Mehmedovic E, et al. Structural and electronic properties of β-FeSi2 nanoparticles: The role of stacking fault domains. Physical Review B. 89 (2014) 054104. doi:10.1103/PhysRevB.89.054104.

Friedrich M, Penner S, Heggen M and Armbrüster M. High CO2 Selectivity in Methanol Steam Reforming through ZnPd/ZnO Teamwork. Angewandte Chemie Int. Ed. 52 (2013) 4389–4392. doi:10.1002/ange.201209587.

Gan L, Heggen M, Cui CH and Strasser P. Thermal facet healing of concave octahedral Pt-Ni Nanoparticles imaged in-situ at the atomic scale: Implications for the rational synthesis of durable high performance ORR electrocatalysts. ACS Catalysis 6 (2016) 692–695. doi:10.1021/acscatal.5b02620.