[M-IS17] Interface- and nano-phenomena on crystal growth and dissolution

[MIS17-06] Control of particles by electric field and its applicability in LC-TEM for observing crystallization and dissolution processes

*Tomoya Yamazaki¹, Hiromasa Niinomi², Yuki Kimura¹ (1.Institute of Low Temperature Science Hokkkaido University, 2.Institute for Materials Research, Tohoku University)

Keywords:crystallization, electric field, colloid, dissolution, liquid-cell transmission electron microscopy, particle manipulation

Crystallization and dissolution in a solution are quite important not only for generation of new functional materials and protein crystallization, but also for understanding geochemical processes of ubiquitous phenomena on the Earth. Recent advances in microfabrication techniques have made it possible to fabricate liquid cells for observing liquid samples in electron microscopy. This combined technique is called liquid-cell transmission electron microscopy (LC-TEM) and allows us to visualize crystallization and dissolution processes in spatial and temporal resolution of TEM. However, this method is still struggling at observing these processes because decreasing temperature and concentration of sample, which are crucial parameters for crystallization, at observing area is still difficult. To solve this problem, here we focus on the technique of particle manipulation by applying electric field using electrodes in a liquid sample. We expect this technique to increase local concentration (number density) of particles, such as nanoparticles and colloidal particles, in a liquid sample. To introduce this technique into LC-TEM, it is required to develop liquid cells with adequate design for the particle manipulation by electric field. Firstly, we performed experiments using a existing liquid cell with electrodes and optical microscopy to confirm the effectiveness of the manipulation technique for increasing local concentration of nanoparticles in the cells. We used colloids to observe the electromechanics of each particle under electric field by an optical microscopy. In addition, we considered that the efficiency of electric field to control crystallization and dissolution processes of colloidal crystals.

Acknowledgement
This work was supported partly by the GIMRT Program of the Institute for Materials Research, Tohoku University (Proposal No. 20K0038) and JSPS KAKENHI Grant Numbers JP18J01470 and 20H02580.