氟碳铈矿和氟铈矿晶体结构的精确测定

CRYSTAL STRUCTURE REFINEMENT OF BASTNAESITE-(Ce) AND FLUOCERITE-(Ce)

用强功率四圆单晶衍射仪精确地修正了氟碳铈矿和氟铈矿的晶体结构．氟碳铈矿（ｂａｓｔｎａｅｓｉｔｅ，Ｃｅ（ＣＯ３）Ｆ）属六方晶系，其晶胞参数为：ａ＝０．７１４３８（９）ｎｍ，ｃ＝０．９８０８（２）ｎｍ，γ＝１２０°，Ｚ＝６，空间群Ｐ６－２ｃ．使用３６７个（Ｆ≥３σ（Ｆ））独立衍射点，经多轮最小二乘法修正后，最终获得偏离因子Ｒ＝０．０４９９．氟碳铈矿的晶体结构特征表现为［ＣＯ３］平面三角形平行ｃ轴分布，铈的配位数为９，Ｃｅ－Ｏ（Ｆ）平均键长为０．２５１５ｎｍ，Ｃ－Ｏ平均键长０．１３２７ｎｍ，每个氟原子与周围三个铈原子相连．氟铈矿（ｆｌｕｏｃｅｒｉｔｅ，ＣｅＦ３）属六方晶系，其晶胞参数为：ａ＝０．７１４１２（２１）ｎｍ，ｃ＝０．７２９８９（２１）ｎｍ，γ＝１２０°，Ｚ＝６．其空间群为：Ｐ３－ｃ１（Ｎｏ．１６５）．使用３２１个（Ｆ≥３σ（Ｆ）））独立衍射点，经多轮最小二乘法修正后，最终获得偏离因子Ｒ＝０．０５４２．氟铈矿的晶体结构表现为每个氟原子与周围三个铈原子相连接，每个铈原子与周围９个氟原子相连，铈的配位数为９，Ｃｅ－Ｆ平均键长为０．２４６８ｎｍ．

The crystal structures of bastnaesite-(Ce) and fluocerite-(Ce) was refined by high power four-circle X-ray diffractometer.Bastnaesite, Ce (CO 3)F,is hexagonal with a =0 714 38(9)nm, c =0 980 8(2)nm,γ=120°, Z =6,space group P6- 2c.A total of 367 independent reflections ( F≥3σ(F) ) were collected and employed for intensity calculation.The least-squares refinement of the atomic coordinates and thermoparameters led to R =0 049 9. The triangle plane of is parallel to c axis. The coordination number of Ce is nine.Average distances are Ce-O(F)=0 251 5nm and C-O=0 132 7nm.Fluocerite, CeF 3 belongs to hexagonal system,and its lattice parameters are a =0 714 12(21)nm, c =0 729 89(21)nm,γ=120° and Z =6.The space group was confirmed as P3-c l(No.165).A total of 321 independent reflections ( F≥3σ(F) ) were collected and employed for intensity calculation.The least-square refinement led to R =0 054 2.Each atom is linked with three cerium atoms;each cerium with nine fluorine fluorine atoms.The mean bond distance of Ce-F is 0 246 8nm.