【摘要】 化合物Ca₁₀Si₆O₂₁Cl₂是一种五色透明柱状晶体,在1100℃左右与水汽作用时生成C₃S₂和β-C₂S,它是一种以[Si₂O₇]为基团的岛状硅酸盐矿物。文献在报导该化合物晶体的晶胞参数时,因未考虑（?）向回摆照相的系统弱衍射,错误地将其定成为正交晶系。该晶体应属于单斜晶系,晶胞参数a=7.5166（12）（?）,b=17.3311（21）（?）,c=8.6754（12）（?）,α=102.513°,空间群P2₁/a。用SHELXTL中直接法程序解得晶体的粗结构.对坐标参数及各向异性热因子进行了四轮最小二乘修正后,偏差因子为R=0.0716,R_W=0.0631。晶体是一种近程有序远程无序的结构。平均结构的对称性为P2₁/a,有序部分的对称性为P2₁。更多还原

【Abstract】 The synthetic compound of Ca₁₀Si₆O₂₁Cl₂ is a colorless, transparent, prismatic crystal, forming C₃S₂ and β-C₂S when reacting with water vapour at about 1100℃. It is a kind of nesosilicate minerals with isolated group of [Si₂O₇] as its basic skeleton. The crystal system of the compound was incorrectly considered as orthorhombic, based on its unit cell parameters in reference, because the author of the reference neglected the weak diffraction layer in the oscillating photo along the （?） axis. The actual crystal system should be monoclinic with unit cell parameters α=7.5166（12）（?）, b=17.3311（21）（?）, c=8.6754（12）（?）, β=102.513° and space group p2₁/α. Direct method in programme SHELXTL was used to obtain the contour of the structure. Modified by the least-square method four circles for the coordinates and enantiomorphic thermal factors, the discrepance factors became R=0.0716, R_W=0.0631 at last. The crystal is of an ordered structure in the short range and of a disordered structure in the long range. The symmetry based on the average structure is P2₁/α and that of the ordered domain is P2₁.更多还原