Nobuo Tanaka and Shigeo Arai
Institute of Materials and Systems for Sustainability (IMaSS), Nagoya University, Nagoya, 464-8603, Japan
Environmental transmission electron microscopy (E-TEM) attracts recently a strong interest of materials researchers, particularly, those of fuel cells and lithium batteries, because the actual chemical reaction processes in gases and liquids need to be clarified in real space and in atomic level. E-TEM observations of thicker samples of a few micron in a gas environment, particularly in hydrogen and oxygen gases, become very important for cutting-edge materials in practical use. 3D observation of samples is also necessary for clarifying morphologies of various active materials such as practical catalysts.
We have developed 1MV TEM/STEM equipped with an open-type environmental cell which enables observations in 100 Torr atmosphere of hydrogen, oxygen, nitrogen and carbon mono-oxide, named "Reaction Science HVEM"(RSHVEM)[1]. The transmission of high-energy electrons has realized point-to-point resolution less than 0.2 nm even in gas-environment such as 100 Torr. High-speed beam blanking system reduces irradiation effects of incident electrons, and potentially realizes so-called "in place observation" without effects of beams [1].
In this talk, I would like to present some application data obtained by the E-HV(S)TEM such as (1) in-situ observation of porous gold (Au) catalyst, whose inner surface with zigzag atom arrangement enhances the catalytic oxidation in carbon-mono oxide (CO) gas of 30 Pa[2], (2)observation of diesel soot oxidized in air, and (3) in-situ observation of mechanical test related to "hydrogen brittleness" on a copper(Cu)/silicon(Si) interface and as well as Ni3Al structural materials in mixed gas of hydrogen and nitrogen[3][4]. Observation of Li-related battery materials is also available using a non-exposure transfer holder[5].
Acknowledgements are due to Prof. Muto and Drs. Fujita, Ogura and Takahashi for their kind collaboration of the present study.
[1] N. Tanaka et al., Microscopy, 62 (2014) 305
[2] T. Fujita et al., Nature Mater., 16, August (2012)
[3] Y. Takahashi et al., Mater. Sci. Eng. A, 661 (2016) 211
[4] Y. Takahashi et al. JSME, doi: 10.1299 (2014)
[5] N. Tanaka et al. AMTC Lett., 5 (2016) 60
