Abstracts Book - IMRC 2018

• SD5-O008
DIRECT OBSERVATION OF THREE-DIMENSIONAL DISTRIBUTION
AND DYNAMICS OF SINGLE IONS IN AN IONIC LIQUID
Yuki Sugimori 1 , Tomohiro Miyata 1 , Teruyasu Mizoguchi 1
1 The University of Tokyo, Institute of Industrial Science, Japan.
Ionic liquid is composed of cationic and anionic molecules and one of the most
promising material for next generation electric and battery devices because of
their characteristic properties, namely non-evaporate even under ultrahigh
vacuum and electric conductive. Furthermore, their properties, such as viscosity,
melting temperature, and electro-conductivity, can be controlled by selecting
the combination of the cationic and anionic molecules. On the other hand,
analyzing their nano-structures and atomic/molecular behavior is indispensable
to grasp their mechanisms. We have established the method for observing the
single atoms in an ionic liquid by using scanning transmission electron
microscopy (STEM), and we achieved the visualization of single atoms and nanoinhomogeneous
structures in an ionic liquid. On the other hand, only twodimensional
information could be observed so far. Here, three-dimensional
distribution and dynamics of single ions in the ionic liquid is reported.
We selected an ionic liquid, C 8 mim-Cl, as a solvent and Barium stearate as a
solute. The concentration of the Barium stearate was set to ~0.02M. Then, about
2L of the solution was dropped onto a holey carbon film, and thin liquid film in
the holes was fabricated by the surface tension. The sample thickness at the
center of the liquid film reaches several nm, it enables us to perform the atomic
resolution observation.
We observed this Barium dispersed samples using high-angle annular dark field
scanning transmission electron microscopy (HAADF-STEM). The intensity of the
HAADF image is approximately proportional to square of the atomic number Z,
which allows us to observe heavy element as bright spots. In this experiment,
Barium (Z = 56) ion was expected to be observed as the brightest spot. For
observation, an aberration-corrected STEM (JEM-ARM200CF, JEOL Ltd.) equipped
with a cold-type field-emission gun operating at an accelerating voltage of 200kV
was used. In addition to the experiment, HAADF image simulation was
conducted using a multislice method with Dr.Probe software. Based on the
experimental and theoretical results, the three-dimensional distribution and