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对星叶石K_2Na(Fe,Mn,Mg,□),[Ti_2(St_4O_(12))_2| O_3](OH,F)_4进行了晶体结构的精测, 求得晶胞参数:a=0.535 9(2)um,b=1.1614(4)um,c=1.1861(4)um,α=113.16(2)°,β =103.04(2)°,γ=94.56(2)°.晶胞体积V=0.6495(5)nm~3.单位晶胞中的分子数Z=1,空 间群为P1.结构测定的精度,其偏离因子为R=0.057.根据其晶体结构的特征,与曾测 定的单斜星叶石 K_2NaNa(Fe,Mn)_4Mg_2Ti_2[Si_4O_(12)]_2(OH)_4(OH,F)_2对比,指出两者为不同种 矿物,建议单斜星叶石应重新命名.将星叶石、单斜星叶石、钡铁钛石及问叶石这一类 钛硅酸盐的结构与云母进行类比,提出了晶体化学中的功能性替代的概念
The crystal structure of the aspartolite K_2Na (Fe, Mn, Mg, □), [Ti_2 (St_4O_ (12)) _2_O_3] (OH, F_ .5359 (2) um, b = 1.1614 (4) um, c = 1.1861 (4) um,? = 113.16 (2) °, 94.56 (2) °. The unit cell volume V = 0.6495 (5) nm ~ 3. The unit cell in the number of molecules Z = 1, the space group P1. The accuracy of the structure determination, the deviation factor is R = 0.057. According to the characteristics of its crystal structure, it is pointed out that the two kinds of minerals are different from those of K_2NaNa (Fe, Mn) _4Mg_2Ti_2 [Si_4O_ (12)] _2 (OH) _4 Proposed monoclinic leaf stone should be renamed. The concept of functional substitution in crystalline chemistry was proposed by the analogy of the structure of titanosilicates like stellate, monoclinic, barium, titanite and mica