| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1985: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
Chemical formula of hollandite type compounds is generally <A_x(M^(3+)M^(2+))_yM_(8-y)O_(16)> (0<x<2). Cations M (Mn, Ti, Fe, Al etc.) locate on the octahedral sites of oxygen and construct double strings of octahedron. The four strings make one dimensional tunnel structure formed tetragonal prism. Large cations A (K,Na,Ba etc.) occupy on the pseudo-cube sites of oxygen. It is expected that this type compounds are used for one dimensional ion conductor, absorbent and SYNROC which trap radioactive waste large ions (Cs, etc.). In this work, crystals of this type compound were synthesized and were characterized for understanding of the tunnel. In the first year, hollandite ( <Ba_xMn_8O_(16)> , 1.23<x<1.36) was synthesized for the first time in the air up to 880 C by means of solid state reaction. Although the compound exists in nature, it had never been synthesized so far. The occupancy of hollandite was changed from low to high occupancy according as the temperature increases. This phenomena had been observed in cryptomelane. In the next year, solid solutions of cryptomelane ( <K_xMn_8O_(16)> , 1.0<x<2.0) were synthesized and the relationship between the compositions and the decomposition temperatures of them was derived by DTA. The occupancy of cryptomelane with high occupancy was decreased up to about 60% in the hot water for three weeks. The occupancy of K-ion sites of natural cryptomelane is about 50% in nature. Perhaps natural cryptomelane was washed out by natural water and then the occupancy of K-ion sites fell to half. These informations were very available for understanding the tunnel structure.
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