Environment-Controlled Microscopy Group

Material properties are closely related to microstructure, and therefore, microstructural analysis is extremely important for material researches and developments. Transmission electron microscopy (TEM) is one of the most powerful tools to analyze structures at the atomic level. However, because of the use of electron beams, a material should be placed in a vacuum for observation, its observation condition is different from an environment where the material is actually used. Therefore, our group works on in situ and operando TEM observations, especially in gas and in liquid phases. We develop specimen holders for in situ observation because the holders that hold specimens in a microscope are independent of the microscope and therefore, can be easily developed and improved. Recent microfabrication techniques such as micro electro mechanical systems (MEMS) have made it possible to create various environments by inserting parts into the tip of a holder with only a few millimeters thick. We also do in situ observations using the developed specimen holders. By capturing changes in structure and composition, we aim to elucidate the reaction and degradation mechanisms that are the key to higher efficiency, longer life, and lower cost.

We have developed a gas-heating specimen holder for in situ observation of gas reaction catalysts. Most commercially available holders use a membrane, but we have also developed a specimen holder that uses differential pumping effects to create a gas environment without a membrane. Because of no membrane, the chemical state analysis and phase measurement are not affected by a membrane. In situ observation of catalysts allows us to capture not only the microstructural changes of catalyst particles, but also the oxidation and reduction reactions locally, in combination with chemical analysis instrument.

Gas-heated sample holder developed in-house (left) and in-situ observation during analysis (right)

Liquid cell transmission electron microscopy (LCTEM) is a technique for in situ observation of samples in liquid phase using liquid enclosable environmental, in which samples in liquid can be observed through ultra-thin membranes that allow an electron beam pass. LCTEM has recently attracted attention because of the capability of observation of not only sample morphology and structure but also chemical reactions with high-spatial resolution. However, it still has many issues for high-resolution imaging and therefore it has not become widespread yet. We study optimum cell membrane materials and methodologies for high-resolution imaging such as a double-tilt LC and a graphene LC. We also develop new LC holders equipped with light illumination and electrochemical functions for conducting application research of in situ TEM observations of photocatalysts and electrocatalysts.

Two-axis tiltable electrochemical liquid cell holder (left), in situ STEM observation of zinc dendrite growth on platinum electrode during ZnSO₄ electrolysis (center), atomic-resolution STEM imaging of water/SrTiO₃ interface (right).

• Solid-State Battery Group
• Battery Interface Control Group
• Battery Materials Analysis Group
• Photovoltaic Materials Group
• Rechargeable Battery Materials Group
• Solid State Battery Ionics Group
• Environment-Controlled Microscopy Group
• Automated Electrochemical Experiments Team
• Functional Electrolyte Synthesis Team