沂蒙矿的晶体结构

本文应用RASA-ⅡS型自动四圆单晶衍射仪,对沂蒙矿收集了独立的749个衍射强度。用RASA-SAP解析系统及XTL结晶学程序求得了晶体中各原子的坐标、温度因子、占有度,并计算了各原子的间距和键角。结构修正后的偏离因子R=0.080。通过结构测定,搞清了高压条件下一价碱金属离子K等的配位形式,测定了一种Fe的五次配位形式——Fe—O正三方双锥配位多面体,并对金伯利岩中Cr,Ti等元素的地球化学行为提供了一些新的认识。     

THE CRYSTAL STRUCTURE OF YIMENGITE

Yimengite is a new species of mineral discovered in Shandong Province in 1980, with crystal chemical formula K(Cr, Ti, Fe, Mg, Al, Si)_(12)O_(19). It belongs to hexagonal system, and its cell parameters α_0=5.857 and c_0=22.940. 749 separate diffraction intensities of crystal were collected on RASA=IIS auto-four-circle single crystal diffractometer.All atomic coordination, temperature factor and degree of occupation were obtained by RASA-SAP interpretation system, and XTL crystallographic procedure, atomic distances and bond angles for each atom were calculated. Deviation factor R is 0.080.Through the medium of determination of the crystal structure of the new mineral yimengite, coordination form of monovaleace alkali metal element—potassium, etc. in high pressure have been cleared, a five fold coordination form of Fe cations—regular bipyramid has been established, and some new information on the geochemical state of some elements, such as Cr, Ti, etc. have been provided.     

Fibonacci序列在准晶体结构研究中的应用

1984年底关于具有五次对称的准晶态的发现,冲破了一百多年来建立起来的经典晶体学的现有理论基础.在随后得到的锰-铝准晶体高分辨电子显微图中,呈环状分布的亮点在直线方向或相间或重叠,而结点分布服从 Fibonacci 排列.本文介绍了含有五次对称的新点群和新单形;研究了 Fibonacci 排列的一些性质;提出了一个有趣的排队规则,证明了有关的定理,从而较圆满地描述了准晶体结构的一些特征.     

THE REFINEMENT OF CRYSTAL STRUCTURE OF BALIPHOLITE

Balipholite is a new mineral discovered in China. Its space group is C cca with the lattice parameters a=13.587(6), b=20.164(10), c=5.144(1). The structure was refined to an R value of 0.047 for 949 independent reflections with (|F_0|>3σ|F_0|). Balipholite has the simailar structure as that of the carpholite group but with large cations Ba occupying the caves of the structure. It is very interesting to point out that the additional anions F and OH occupy different crystallographic positions. Formula of balipolite can he written a BaMg_2LiAl_3(Si_2O_6)_2(OH)_4F_4.     

葡萄石的结构

葡萄石的组成为 Ca_2Al_2Si_3O_(10)(OH)_2。晶体的 Laue 对称性确定为 D_(2h)。正交晶胞的参数为α=4.64(?),b=5.50(?),c=18.4(?)。晶体的密度为2.925克/厘米~3。正交晶胞中当含有2{Ca_2Al_2Si_3O_(10)(OH)_2}。晶体的可能空间群为 D_(2h)~7-Pncm 或 C_(2v)~6-Pnc2。为推引正离子在晶胞中各种可能的分布方式,计算若干 Patterson 函数,然后逐步按照对称性、空间考虑以及硅酸盐的其他晶体化学特点,对正离子和负离子的位置作出安排,从而取得到一合理的试用结构。这个结构具有 D_(2h)~7的对称性。最后,按照这个模型计算电子密度分布函数ρ(x,z)和ρ(y,z)。计算结果肯定试用结构。葡萄石结构系由 Ca~(2+),Al~(3+),OH~-和[Si_3AlO_(10)]_(?)~(5(?)-)等离子组成,其中层型硅氧骨干系与(001)面平行,相隣的骨干通过离子 Al~(3+)得以结合。在这结构中,离子 Al~(3+)有两种配位型式,一半在四面体中,另一半在4个氧原子和2个氢氧基组成的八面体中。离子Ca~((?)+)则处在5个氧原子和2个氢氧基形成的配位中。葡萄石中[Si_3AlO_(10)]_n~(5n-)的结构型式与一般层型硅氧骨干不同,实际上是一种层型骨架。在上述结构模型的基础上,葡萄石的组成和性能已可得到充分阐明。     

DEDUCTION OF QUASILATTICE WITH FIVE-FOLD SYMMETRY AND PARTICLE FRACTAL STRUCTURE MODEL

In the structure of quasicrystal, the coordination icosahedron has long ordering but no translation ordering. The author dealt with the building principle ofquasicrystal and thought that two principles played a certain role in the quasicrystal structure, i.e. the icosahedron principle and the golden mean principle. We obtained the most simple.structure model of quasicrystals, and could explain all details of the high-resolution electron microscopic image of the A1-Mn quasicrystal based on the two principles. The author's model has the characteristic of fractal structure, therefore, we call it the particle fractal structure madeh The author has made a systematic deduction of quasicrystal point group, forms, possible type of quasicrystal lattice.     

青河石(Qingheiite)的晶体结构

本文根据帕特逊法及富利叶合成测定了青河石的晶体结构,结构参数经最小二乘法修正后R=0.055,结构分析表明,青河石为wyllieite族中其M(2a)位置为Mg端员,M(1)位置为Mn端员的新矿物,晶体化学式为:Na_2NaMnMn_2Mg_2(Al,Fe)_2(PO_4)_6。     

纤钡锂石晶体结构的精测

纤钡锂石是一种在中国发现的新矿物,晶胞参数为α=13.587(6),b=20.164(10),c=5.144(1),空间群C cca。利用949个独立的衍射点(|F_0|>3σ|F_0|)对该结构进行修正,R=0.047。纤钡锂石的结构与纤锰柱石族相似,但大阳离子Ba占据了结构中的空洞位置。有趣的是该结构中附加阴离子F和OH占有不同的结晶学位置,因此,纤钡锂石的晶体化学式可写作BaMg_2LiAl_3(Si_2O_6)_2(OH)_4F_4。     

CRYSTAL STRUCTURE OF A NEW PHOSPHATIC MINERAL——QINGHEIITE

The Qingheiite is a new mineral in the phosphate Wyllieite family. Space group P_(z1)/n, a=11.856, b=12.411, c=6.421, β=114.45°.The correct structure model has been obtained by using the Patterson method and Fourier synthesis. After the Structure parameter refinement, the R-factor reduced to 0.055. The structure analysis indicates that it is a new mineral in Wyllieite family which is Mg-end member in the M(2a) and Mn~(2 )-end member in the M(1). The crystallochemical formula is Na_2NaMn_2Mg_2 (Al, Fe)_2(PO_4)_6.     

用中子衍射法测定锡石(SnO_2)的晶体结构

本文用中子衍射法测量了 ＳｎＯ２单晶［００１］晶带的 ２９个衍射峰,用富利叶综合法进行了 计算,得出ＳｎＯ２在（００１）的原子核密度投影,由此求出了氧原子坐标参数ｘ＝０．３０６±０．００１．