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Electron radiation damage of natural zeolites at room and low temperature

1990; Cambridge University Press; Volume: 48; Issue: 4 Linguagem: Inglês

10.1017/s0424820100177179

2690-1315

Y. Yokota, Hatsujiro Hashimoto, Terutoshi Yamaguchi,

Ion-surface interactions and analysis

Zeolites are easily changed to amorphous under electron beam irradiation. Bando reported that this phenomena take place at low temperature with 1/20 dose of room temperature. In the present work this phenomena was investigated using two kinds of specimens, by changing temperature, electron energy (100 kV-350 kV) and also by applying an electron energy loss spectrometer. Mesolite is from Yaizu, Sizuoka Prefecture and Thomsonite is from Nishijima, Yamanasi Pref. , Japan. The specimen were ground to fine powder and dispersed on a microgrid. A Faraday gage which was installed in the observing chamber of the microscope was used for measure the dose rate. Decomposition was determined by measuring the current of a diffracted spot by the Faraday gage. Observation at low temperature was carried out using low temperature specimen holders fabricated to 200 kV and 400 kV electron microscopes. Fig. 1 (a), (b) are high resolution lattice images of Mesolite by 200 kV TEM operated in room temperature, (b) was taken 20 second after the same part of (a). The thickness of amorphous region in (a) is 8 nm, in (b) the amorphous region increased to 30 nm.