利用CCD单晶衍射仪对草莓红绿柱石进行晶体结构测定,测定其空间群为R3c,并讨论了结构中Li^+有序地置换Be^2+造成c/a值的变化特征。晶体中发现复三方偏三角面体的负晶包裹体,其宏观对称属^-3m,它与空间群R^-3c相对应,但与测出晶体结构的空间群有矛盾。X射线结构测定已否定了其空间群为R^-3m的看法。要解决草莓红绿柱石晶体空间群是否有对称中心(R^-3c或R^-3c)的问题,还需进一步将X射线结构的数据及其有关的电性实验结合分析。
CCD single-crystal X-ray diffractometer was employed to analyze the crystal structure of pezzottaite with space group = R3c. The variation characteristics of c/a ratio of unit celt, which is caused by the regular replacement of Li^+ to Be^2 + in the structure, has been discussed. In contrast with the detected space group of the crystal, the newly discovered ditrigonal scalenohedral negative crystal inclusions showed the m symmetry of the crystal with space group symmetry R^-3c. Our structural analysis of pezzottaite revealed that the previous assumption of the space group (R^-3m) of the crystal was incorrect. Further experiments are required to determine the true space group (R3c or R^-3c) of pezzottaite and reveal whether it has the symmetrical centre or not.