The cooling history of the Crateceous Toki granite, exposed in the eastern Sanyo Belt, Central Japan, was constructed from various geochronological data. The granite yields K-Ar biotite ages of 74±2 to 72±2 Ma (±1σ) and K-Ar hornblende ages of 75±4 to 74±4 Ma, which are concordant with a previously reported Rb-Sr whole-rock isochron age. Fission-track ages of zircon and apatite in the granite give ages 73±3 to 64±3 Ma and 40±4 to 37±4 Ma, respectively. These above thermochronological data suggests two distinctive cooling stages for the Toki granite; 1) a first rapid cooling stage in which the granitic magma was cooled to the temperature of host rock soon after intrusion at depths of 5-7 km in the upper crust, and 2) second slow cooling stage (7-9 °C/m.y.) associated with the uplift and subsequent erosion of the granite intrusion after ∼ 70 Ma.

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  Rock polarization microscope is applied to the observation of micro-pores and interstices of electrode materials for lithium ion battery. The sample is solidified in resin doped with fluorescent dye and is observed under the plane- and cross-polarized conditions by an incident-light type polarization microscope. In the cross-polarized condition most part of reflected light which is initially polarized by the polarizer, is cut off by the analyzer and only the fluorescent light goes through the analyzer, which relatively emphasizes the fluorescence to highlight the material pores and interstices.
  In the lithium ion battery the electrode materials should be coated finely, densely and uniformly on the metal thin plate and therefore the micro-pores and interstices also should be distributed in the same way. In this study the distributions of particles and interstices were clearly observed in the polarization microscope, including pore sizes, pore shapes, their distributions and even the material detachment from metal plate. This observation contributes to the improvement of electrode coating in the production process.

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[in Japanese]

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