Rosales Ivonne, Orozco Eligio, Bucio Lauro, Fuentes Maria E, Fuentes Luis
Acta Crystallogr Sect E Struct Rep Online. 2009 Apr 8;65(Pt 5):i33. doi: 10.1107/S1600536809011866.
A well crystallized powder sample of sodium holmium orthosilicate oxyapatite, Na(2.27)Ho(7.73)(SiO(4))(6)O(0.72), was obtained after mechanical milling and thermal treatment at 1123 K. Crystal structure analysis was performed from the results of Rietveld refinement of the synchrotron diffraction data. As in other rare-earth orthosilicate apatites, sodium cations appear located sharing with holmium the 4f Wyckoff position at the center of a tricapped trigonal prism. In its turn, holmium almost fully occupies the 6h position at the center of a seven-coordinated penta-gonal bipyramid. A small quantity of Na atoms was found at this site. No vacancies are present in the two independent crystallographic sites available for Ho and Na atoms.
通过机械研磨并在1123 K下进行热处理后，获得了结晶良好的原硅酸钬钠氧磷灰石粉末样品，化学式为Na(2.27)Ho(7.73)(SiO(4))(6)O(0.72)。根据同步辐射衍射数据的Rietveld精修结果进行了晶体结构分析。与其他稀土原硅酸磷灰石一样，钠阳离子似乎与钬共享位于三帽三角棱柱中心的4f Wyckoff位置。相应地，钬几乎完全占据七配位五角双锥中心的6h位置。在该位置发现少量钠原子。对于钬和钠原子可用的两个独立晶体学位置中不存在空位。
