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首页> 外文期刊>Journal of Alloys and Compounds: An Interdisciplinary Journal of Materials Science and Solid-state Chemistry and Physics >A novel boroncarbide, Y_2B_3C_2 X-ray single crystal and neutron powder diffraction analysis
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A novel boroncarbide, Y_2B_3C_2 X-ray single crystal and neutron powder diffraction analysis

机译：新型碳化硼，Y_2B_3C_2 X射线单晶和中子粉末衍射分析

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The crystal structure of Y_2B_3C_2 was analysedby means of room temperature X-ray single crystal and neutronpowder diffractometry. Y_2B_3C_2 crystallises with theGd_2B_3C_2-type (space group: Cmmm - No.65, Z=2). The unitcell dimensions are: a=0.3405(5), b=1.3765(6), c=0.3631(6) nm,b/a=4.044, V=0.1702 nm~3 the X-ray density is: #rho#_x=4.57Mgm~(-3). The structure was solved by combined Patterson-Difference Fourier methods. Residual values are: R_F =#SIGMA#|#DELTA#F|/#SIGMA#|F_o|=0.027, R_w =0.020, foran asymmetric set of 232 independent reflections(|F_o|>3#sigma#(|F_o|)). Boron atoms B1, each in triangularmetal co-ordination, form infinite zigzag chains (d_(B1-B1) =0.1923 nm) branched with carbon atoms. Bond angles in the chainare #phi#_(B1-B1-B1)=124.60 deg. Carbon atoms are at adistance of d_(Bl-c) =0.1552 in rectangular co-ordination of fourmetal atoms. The branched boron chains are connected by abridging boron atom B2 linking the carbon atoms in form of alinear bridge at d_(C-B2) = 0.1442 nm. Rietveld refinement of theneutron powder data from Y_2B_3C_2(~(11)B-isotope) confirmsthe nuclear structure arrangement as well as the full occupancy ofall the non-metal atom sites.
机译：通过室温X射线单晶和中子粉末衍射法分析了Y_2B_3C_2的晶体结构。 Y_2B_3C_2结晶为Gd_2B_3C_2型（空间群：Cmmm-No.65，Z = 2）。晶胞尺寸为：a = 0.3405（5），b = 1.3765（6），c = 0.3631（6）nm，b / a = 4.044，V = 0.1702 nm〜3 X射线密度为：＃rho＃_x = 4.57Mgm〜（-3）。通过组合的Patterson-Difference Fourier方法解决了该结构。残留值为：R_F =＃SIGMA＃|＃DELTA＃F | /＃SIGMA＃| F_o | = 0.027，R_w = 0.020，用于一组不对称的232个独立反射（| F_o |> 3＃sigma＃（| F_o |） ）。硼原子B1各自呈三角形金属配位，形成无定形之字形链（d_（B1-B1）= 0.1923 nm），并带有碳原子分支。链中的键角为#phi #_（B1-B1-B1）= 124.60度。碳原子在四金属原子的矩形配位中的距离为d_（B1-c）= 0.1552。支化的硼链通过在d_（C-B2）= 0.1442 nm处以线性桥的形式桥接连接碳原子的硼原子B2连接。对Y_2B_3C_2（〜（11）B-同位素）中子粉末数据的Rietveld精炼证实了其核结构排列以及所有非金属原子位点的完全占据。

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