架状硅酸盐的氧平均体积

OXYGEN-SHARED VOLUMES OF FRAMEWORK SILICATES

架状硅酸盐的氧平均体积与晶体结构有如下关系:V_o=a+bf(s)。对于每种结构类型而言,a和b是常数。f(s)是结构函数,它取决于离子半径、离子电价以及类质同象替代关系。文中给出了长石型、白榴石型、鳞石英型以及β石英型架状硅酸盐的V_0与结构函数之间的定量关系。沸石中虽含有大量水,但其V_o并未增大,平均值为22.25A^3,标准方差σ_(n-1)=0.82A^3,与石英玻璃V_o值近于相等。

The oxygen-shared volume of a framework silicate mlneral (V_o value) iscalculated to be: V_o=V(the unit-cell volume)/∑_o(the total number of oxygen and water in the unit cell) In this paper a new concept, the structural function, is introduced by theauthors, It is defined as: f(s) (structural function)=sub from m to (m×r)/∑_o×R_t/0.39×T/T+Si, where m, r and e are the number, radius and valence, respectively, of the non-framework cation, R_t is the radius of the cation T substituting for siliconT/(T+Si) is the occupancy of T, and 0.39A is the radius of Al^(3+). The V_o values of framework silicate minerals are linearly correlated withtheir structural functions, i.e.; V_o=a+bf (s),where a and b are constants for a certain structural type of framework silica-tes, and a corresponds to the V_o value of a certain silica polymorph. V_o=16. 52+151. 0f(s) r=0.989 (feldspar group) V_o=21. 59+20. 10f(s) r=0.947 (tridymite group) V_o=20. 18+29. 81f(s) r=0.92 (β-quartz group) V_o=21. 49+48. 17f(s) r=0.951 (leucite group) Though zeolitic minerals contain much water, their V_o values do not incr-ease, the mean value being 22. 25 A^3 with б_(n-1)=0. 82 A^3, which is approximatelythe same as that of silica glass.