Structural Evolutions in the Sr1−xBaxZrSe3Series
Structural Evolutions in the Sr1−xBaxZrSe3Series
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Sr1−xBaxZrSe3 系列的结构演变
DOI：
10.1006/jssc.1996.7253
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发表时间：
1997
影响因子：
5.4
通讯作者：
B. Eichhorn
中科院分区：
文献类型：
--
作者：
L. J. Tranchitella;Bai;J. Fettinger;B. Eichhorn
在90 0~95 0℃的温度范围内，由SrSe、碱、Zr和Se在真空和密封的硅胶安瓶中合成了Sr1−xBaxZrSe3系列化合物，其中0≤x≤0.6 8，在反应过程中竞争性地形成了非晶态的Zr-Se相，因此合成混合物需要分别增加20%和40%的摩尔过量的Zr和Se。Sr1−xBaxZrSe3化合物为NH4CDCl3结构，由扭曲的(Sr，BaSe9)Se9三角棱柱连接而成的双边共享的ZrSe6八面体。对于0.68x3-和NH4CdCl3型化合物。X≈相是通式为Ba1.07ZrSr3的不匹配链状化合物。在Sr1−xBaxZrSe3系列中，随着Ba2+浓度的增加，(SR，BA)Se9三层棱镜的键距各向异性显著减小。粉末X-射线衍射数据的Rietveld轮廓分析确定了其结构，而单晶X-射线衍射法确定了Sr0.74 Ba0.26和Sr0.32 Ba0.68的结构。(293K)-正交晶系，空间群Pnma，V=513.1(1)A3，Z=4，R=5.39%，Rwp=6.55%，a=8.915(1)，b=3.965(1)，c=14.514(2)A；空间群Pnma，a=8.9305(2)，b=3.9796(13)，c=14.611(2)A，V=14.611(2)A，Z=4，R(F0)=3.04%，WR(F20)=5.95%；空间群Pnma，a=531.66(11)，b=4.0065(4)，c=14.7868(12)A，V=0.32(9)A3，Z=4，R(F0)=4.12%，WR(F20)=9.94%。
Abstract Compounds in the Sr 1− x Ba x ZrSe 3 series, where 0≤ x ≤0.68, were prepared from SrSe, BaSe, Zr, and Se in evacuated and sealed silica ampules, at temperatures between 900 and 950°C. An amorphous Zr–Se phase is competitively formed in the reaction thus synthesis mixtures require 20 and 40% mole excess of Zr and Se, respectively. The Sr 1− x Ba x ZrSe 3 compounds adopt the NH 4 CdCl 3 structure type, containing columns of double edge-sharing ZrSe 6 octahedra linked by distorted (Sr, Ba)Se 9 tricapped trigonal prisms. For 0.68 x 3 - and NH 4 CdCl 3 -type compounds are obtained. The x ≈1.0 phase is a commensurate mismatched chain compound of formula Ba 1.07 ZrSr 3 . The (Sr, Ba)Se 9 tricapped prisms show a marked decrease in bond distance anisotropy as the Ba 2+ concentration increases in the Sr 1− x Ba x ZrSe 3 series. The structure of SrZrSe 3 was determined from Rietveld profile analysis of the powder X-ray diffraction data whereas Sr 0.74 Ba 0.26 ZrSe 3 and Sr 0.32 Ba 0.68 ZrSe 3 were structurally characterized from single crystal X-ray studies. Crystallographic data for: (293 K)—orthorhombic, space group Pnma , a =8.915(1), b =3.965(1), and c =14.514(2) A, V =513.1(1) A 3 , Z =4, R =5.39%, and R wp = 6.55%; Sr 0.74 Ba 0.26 ZrSe 3 (293 K)—orthorhombic, space group Pnma , a =8.9305(2), b =3.9796(13), and c =14.611(2) A, V =519.3(2) A 3 , Z =4, R ( F 0 )=3.04%, wR ( F 2 0 )=5.95%; Sr 0.32 Ba 0.68 ZrSe 3 (293 K)—orthorhombic, space group Pnma , a =8.9741(11), b =4.0065(4), and c =14.7868(12) A, V = 531.66(9) A 3 , Z =4, R ( F 0 )=4.12%, wR ( F 2 0 )=9.94%.