Some examples of environmental experiments under gas and temperature conditions in the Ly-EtTEM microscope

updated June 06 2015

Ly-EtTEM stands for Lyon - Environmental tomographic Transmission Electron Microscope.
This instrument is based on a FEI-Titan ETEM, 80-300 kV, equipped with a X-MAX SDD EDX detector from Oxford-Instrument and a Tridiem ERs GIF from Gatan. It has been installed in January 2013 in a dedicated building of the IRCELYON laboratory, one of the 13 CLYM partners. Gas inputs are handled through a high purity, high accuracy 5 channels mixing system provided by Serv'Instrumentation (2015).

A silver nanoparticle deposited on a carbon supporting film is observed at 300 kV under an oxygen pressure of 0.6 mbar at 495C. O2 molecules dissociated at the surface of the Ag NP and further reacts with the carbon film to produce volatile CO2: the supporting film is thus consumed and the NP runs on it to maintain the contact. Short sequence of about 2', low res.; (c) Ly-EtTEM team, (2013).
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Left: the same Ceria NP particle is successively observed at RT under 1 mbar of oxygen (left) and high vacuum (right): note the high surfaxce mobilty of the 'top' (001) surface in the second case. Right: EELS spectra of the O-K edge recorded under the same two conditions; no change occurs under oxygen whereas reduction of Ce4+ into Ce3+ is revealed by the decrease of the first peak of the O-K edge under HV. Short 'looped' sequences, low res. (c) T. EPICIER, M. AOUINE, F.J. CADETE SANTOS AIRES, C. DANIEL, IRCELYON, (2014).
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Due to European standards since Euro 4, Diesel Particulate Filters are now compulsory on Diesel car motors to diminish Particle Matter emissions through a regeneration phase in which the collected soot is oxidized. A catalyst, here Yttria-Stabilised Zirconia is then used to optimize the soot oxidation. In this low res video sequence recorded at 495C under 10-2 mbar of oxygen in the EtTEM (full time about 4'), a soot particulate is consumed at the contact with a ZrO2 crystallite. Magnification is increased at the end of the sequence to insure atomic resolution; it is seen that some (metallic) impurity present in this soot synthetized in the laboratory does not  burn [A. SERVE et al., Applied Catalysis A: General, (2015), online].
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Here are some examples of high resolution micrographs recorded under environmental conditions.

Top left : Oxygen terminating surface of the (001) facet of a CeO2 nanocube after stabilisation under 5 10-2 mbar of oxygen (c) T. EPICIER, MATEIS/IRCELYON), K.P. MANN, Z. WU, S.H. OVERBURY (ORNL, USA), (2015). Top Right: Atomic STEM imaging of the "M1" phase (Mo,V,Te,O) under 1 mbar of a C2H6 + air mixture at 350C (c) J.M. MILLET et al., IRCELYON. Bottom: evidence of transfer of information down to 0.11 nm during the in situ oxidation of a silver NanoParticle under 5 mbar of oxygen above 350C.

  Fast acquisitions of tilting series allows the same object to be followed in 3D during its in situ evolution under environmental conditions; the example shown below illustrates the coaelescence and decomposition of Ag nanoparticles encaged in slicalites 'boxes' under oxygen as a function of temperature (c)  T. EPICIER, L. ROIBAN, S. LI, M. AOUINE, F.C. SANTOS AIRES, A. TUEL, D. FARRUSSENG, Proceed. IMC2014, ISBN 978-80-260-6721-4.
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