Isao Nagaoki

Design of a 300-kV gas environmental transmission electron microscope equipped with a cold field emission gun

A new in situ environmental transmission electron microscope (ETEM) was developed based on a 300 kV TEM with a cold field emission gun (CFEG). Particular caution was taken in the ETEM design to assure uncompromised imaging and analytical performance of the TEM. Because of the improved pumping system between the gun and column, the vacuum of CFEG was largely improved and the probe current was sufficiently stabilized to operate without tip flashing for 2-3 h or longer. A high brightness of 2.5 × 10(9) A/cm(2) sr was measured at 300 kV, verifying the high quality of the CFEG electron beam. A specially designed gas injection-heating holder was used in the in situ TEM study at elevated temperatures with or without gas around the TEM specimen. Using this holder in a 10 Pa gas atmosphere and specimen temperatures up to 1000°C, high-resolution ETEM performance and analysis were achieved.

In situ observation of degradation of electrocatalysts in humidified air atmosphere using a cold FE 60-300 kV ETEM

Polymer electrolyte fuel cells (PEFCs) attract a great attention as new generation power devices for automobile and cogeneration systems. Yet, the durability of electrocatalysts is one of the most critical issues that are delaying the commercialization of this technology. To improve the durability PEFCs, we focus on studying the degradation mechanism of the electrocatalysts in their real-time evolution during operation. For this purpose, in situ observation using an environmental transmission electron microscope (ETEM) is one of the most powerful techniques. We have developed a CFE-ETEM with capabilities of simultaneous SEM with STEM image observation and applied it to the study of Pt/CB electrocatalysts degradation mechanism [1]. Previous study revealed that the Pt particles on the carbon support were aggregated and the carbon support was depressed by the Pt particles under a dry air atmosphere at 200 °C. However, the mechanism of the particles penetration into the carbon support is an open question. In the present study, we have investigated the behavior of Pt particles and related corrosion of the carbon support of electrocatalysts in a highly humidified air atmosphere.

Application of Lattice Strain Analysis of Semiconductor Device by Nano-beam Diffraction Using the 300 kV Cold-FE TEM

The evaluation of lattice strain is important to control the electrical characteristic of semiconductor devices. We investigated the lattice strain of the device by nano-beam diffraction (NBD [1-3]) using the HF-3300 Cold FE-TEM [4] with the acceleration voltage of 300 kV. As a result, the rate of the lattice strain in device increased with changing specimen thickness. The effective alteration of the lattice strain in device could be observed more than 300 nm specimen thickness by the NBD.