Synthesis and crystal structures of CaY2Ge3O10 and CaY2Ge4O12
Synthesis and crystal structures of CaY2Ge3O10 and CaY2Ge4O12
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DOI：
10.1016/j.jssc.2005.10.023
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发表时间：
2006
影响因子：
3.3
通讯作者：
H. Yamane;R. Tanimura;Takahiro Yamada;J. Takahashi;T. Kajiwara;M. Shimada
中科院分区：
文献类型：
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作者：
H. Yamane;R. Tanimura;Takahiro Yamada;J. Takahashi;T. Kajiwara;M. Shimada
用CaCO_3、Y_2O_3和GeO_2的混合物在1200 ℃下加热，合成了CaY_2Ge_3O_（10）和CaY_2Ge_4O_（12）。CaY 2Ge 3 O 10在1300°C下稳定，而CaY 2Ge 4 O 12在约1250°C下分解成熔体和CaY 2Ge 3 O 10。我们通过以−6°C/h的速率将初始组成为Ca：Y：Ge=1：2：8的样品从1300°C冷却，获得了CaY 2Ge 3 O 10的单晶。用X射线单晶衍射法测定了CaY_2Ge_3O_（10）的晶体结构。CaY_2Ge_3O_（10）晶体属单斜晶系，空间群为P21/c，晶胞参数为：a=6.0906（8），B=6.8329（8），c=18.752（2）π，β=109.140（3）°，Z=4，当I>2σ（I）时，R_1 =0.029。在CaY_2Ge_3O_（10）的结构中，Ca和Y原子无序地位于GeO_（4）四面体的锗酸盐基团之间的三个7重配位上。CaY 2Ge 3 O 10的结构式表示为（Ca0.45Y0.55）（Ca0.46Y0.54）（Ca0.09Y0.91）Ge 3 O 10。用Rietveld方法对CaY 2Ge 4 O 12的X射线粉末衍射图进行了结构分析。CaY_2Ge_4O_（12）与SrNa_2P_4O_（12）属同型晶系，空间群为P_4/nbm，a=9.99282（6），c=5.06701（4）nm，Z=2，Rwp=0.092，Rp=0.067。CaY 2Ge 4 O 12含有四元GeO 4四面体环，Ge 4 O 12。Ge_4 O_（12）环层间的八重配位正方反棱柱位和六重配位八面体位分别被Y原子和Ca/Y原子占据，结构式为Y（Ca_（0.5）Y_（0.5））_2Ge_4 O_（12）。
New compounds CaY2Ge3O10and CaY2Ge4O12were prepared by heating mixtures of CaCO3, Y2O3and GeO2at 1200°C. CaY2Ge3O10is stable at 1300°C, while CaY2Ge4O12decomposes into a melt and CaY2Ge3O10at approximately 1250°C. We obtained single crystals of CaY2Ge3O10by cooling a sample with an initial composition of Ca:Y:Ge=1:2:8 from 1300°C with a rate of −6°C/h. The crystal structure of CaY2Ge3O10was determined by single crystal X-ray diffraction. CaY2Ge3O10crystallizes in the monoclinic space group P21/c with a=6.0906(8), b=6.8329(8), c=18.752(2)Å and β=109.140(3)°, Z=4, and R1=0.029 for I>2σ(I). In the structure of CaY2Ge3O10, Ca and Y atoms are situated disorderly in three 7-fold coordination sites between isolated germanate groups of triple GeO4tetrahedra, Ge3O10. The structural formula of CaY2Ge3O10is expressed as (Ca0.45Y0.55)(Ca0.46Y0.54)(Ca0.09Y0.91)Ge3O10. The crystal structure of CaY2Ge4O12was analyzed by the Rietveld method for the X-ray powder diffraction pattern. CaY2Ge4O12is isotypic with SrNa2P4O12, crystallizing in the orthorhombic space group P4/nbm, a=9.99282(6), c=5.06701(4)Å, Z=2, Rwp=0.092, Rp=0.067. CaY2Ge4O12contains four-membered GeO4-tetrahedra rings, Ge4O12. Eight-fold coordinated square-anitiprism sites and 6-fold octahedral sites between the layers of the Ge4O12rings are occupied by Y atom and Ca/Y atoms, respectively The structural formula is Y(Ca0.5Y0.5)2Ge4O12.