鉱物学会2001年シンポジウム
「シリカ鉱物—広く議論しよう地球科学から材料科学まで」
「シリカ鉱物—広く議論しよう地球科学から材料科学まで」
SiO2多形と構造転移
2002 年 31 巻 1 号 p. 38-41
詳細
2002 年 31 巻 1 号 p. 38-41
Except for a high pressure polymorph,silicas crystallize with the frameworks of corner-linked SiO4 tetrahedra. Electrostatic valence at an atomic site is fully compensated by its neighbor atoms with opposite charges, and therefore, no foreign cation can enter into the frameworks. This is probably the cause of negligible long-range interactions in the silica structures. Many topologically different linkages are possible in the absence of the long-range interactions. As the result, we have silicas in more than 20 different phases. We review the recent structural problems in the low-pressure polymorphs of silicas, ie. quartz, tridymite and cristobalite. Silica clathrates are also introduced, stressing their potential importance in material sciences.
