Development of Environmental Cell and its Application to Hydrogen Storage Materials
- PDF / 3,013,043 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 52 Downloads / 163 Views
0971-Z07-12
Development of Environmental Cell and its Application to Hydrogen Storage Materials Koya Okudera1, Koichi Hamada1, Takanori Suda1, Naoyuki Hashimoto1, Somei Ohnuki1, Yasuaki Kawai2, and Yoshitsugu Kojima3 1 Division of Materials Science and Engineering, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan 2 Toyota Central R&D Labs. Inc., Nagakute, Aichi, 480-1192, Japan 3 Institute for Advanced Materials Research, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8530, Japan
ABSTRACT “Environmental cell” microscopy was applied for surveying the reaction of hydrides in vanadium and magnesium based alloys, which are candidates for hydrogen storage materials of advanced hydrogen energy systems. In order to clarify the mechanism of hydrogenation process, in-situ experiment was carried out by using a 200 kV transmission electron microscope (TEM) equipped with a newly developed environmental cell (EC), which is capable to investigate transmitted image and electron-diffraction under gas hydrogen environment of 0.1 MPa at room temperature. In case of vanadium, under hydrogen-gas of 0.1 MPa, bending fringe was created probably due to local stress induced with the hydrogen solution. On the other hand, when hydrogen gas reacted with magnesium powders, swelling due to volume expansion was occurred. In practice, surface steps with several ten nm became straightened, and additionally, the formation of MgH2 was indicated in selected-area diffraction pattern (SADP). In-situ experiment for hydrogenation reaction by using the environmental cell was recently started. The precise studies, as well as its improvement, will be continued, especially in the transparence films. INTRODUCTION The hydrogen storage alloy attracts attention as one of the hydrogen storage materials. Although many studies have been done for development of better materials, microscopic observation of the hydrogen absorption reaction process aiming at evaluation or control of material has not been performed. TEM observation and in-situ XRD analysis are carried out to understand effects of microstructures and temporal structure changes. (e.g. reference [1],[2]). Although these ways are very effective for understanding of material properties, it isn’t able to observe successive microstructural changes with hydrogenation. We thought the environmental cell enables to observe them and it is useful to the development of advanced hydrogen storage materials. Environmental cell is a technique for in-situ observation in TEM. In the past study, insitu observation of the oxidation process of Ni-Cr alloy was performed using the HVEM which is the acceleration voltage of 1.2 MV (pressure 2.4-2.8 kPa, temperature of 500 °C) [3]. In the catalytic reaction, P. L. Gai et al. are performing in-situ observation for the catalytic reaction of molybdic acid bismuth which is a heterogeneous catalyst on 100 Torr and 400-500 °C conditions using C3H6 gas [4]. As an example of the in-situ observation of crystal growth, cryostat is
introduc
Data Loading...
