クリプトメレンにおけるKの充填率と熱的挙動

抄録

Thermal behaviors of cryptomelane (K_xMn₈O₁₆ ; 0≤x≤2) have been examined with DTA and TGA. The differences in thermal decomposition of various cryptomelanes depend on the K-ions occupancy in its one-dimensional tunnels. Arising temperature from 630°C to 860°C, cryptomelane with lower occupancy is gradually converted to one with higher occupancy accompanied by producing bixbyite (Mn₂O₃) . After the tunnels are filled up with K-ions at 860°C, the cryptomelane is converted to bixbyite and K₂Mn₄O₈ phase. Subsequently, the bixbyite is transformed to hausmannite (Mn₃O₄) . According to the above fact, cryptomelanes with various occupancies have been obtained by means of solid state reaction. [J. Cryst. Soc. Jpn. 26, 278 (1984) ] .