Determination of the modulated structure of Sr14/11CoO3 through a (3 + 1)-dimensional space description and using non-harmonic ADPs.
Determination of the modulated structure of Sr14/11CoO3 through a (3 + 1)-dimensional space description and using non-harmonic ADPs.
复制标题
通过 (3 1) 维空间描述并使用非谐波 ADP 确定 Sr14/11CoO3 的调制结构。
DOI：
10.1107/s0108768199006485
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Evain
中科院分区：
文献类型：
--
作者：
Gourdon;Petrı́cek;Dušek;Bezdicka;Durovic;Gyepesova;Evain
制备了六方钙钛矿结构Sr（x）CoO（3）体系中的一个新相Sr（14/11）CoO（3）（即Sr（14）Co（11）O（33），tetradecastrontiumundecacobalttritriacontaoxide），并利用（3 + 1）维方法从单晶X射线数据解出了它的结构。Sr（14/11）CoO（3）晶体属于三角对称R3;m（00 gamma）0 s超空间群，晶格参数为：a（s）= 9.508（2），c（s）= 2.5343（7）<$，q = 0.63646（11）c（*），V（s）= 198.40（13）<$（3）。由于相称性与不相称性测试没有结论性，该结构被认为是相称的（P32三维空间群），但在（3 + 1）维形式体系内细化为47个参数和1169个独立反射的残差因子R = 0.0351。Crenel函数被用于氧和钴的描述和Gram-Charlier扩展到第三阶的原子位移参数被用于一个Co原子。其结构与Sr（6/5）CoO（3）的结构相似，但沿着[CoO（3）]链的八面体和三角棱镜多面体的顺序不同。一个有趣的功能证明了非谐波膨胀是位移的棱柱Co原子从网站中心，对棱柱矩形面。
Sr(14/11)CoO(3) (i.e. Sr(14)Co(11)O(33), tetradecastrontium undecacobalt tritriacontaoxide), a new phase in the hexagonal perovskite Sr(x)CoO(3) system, has been prepared and its structure solved from single-crystal X-ray data within the (3 + 1)-dimensional formalism. Sr(14/11)CoO(3) crystallizes in the trigonal symmetry, R3;m(00gamma)0s superspace group with the following lattice parameters: a(s) = 9.508 (2), c(s) = 2.5343 (7) Å, q = 0.63646 (11)c(*) and V(s) = 198.40 (13) Å(3). With the commensurate versus incommensurate test not being conclusive, the structure was considered as commensurate (P32 three-dimensional space group), but refined within the (3 + 1)-dimensional formalism to a residual factor R = 0.0351 for 47 parameters and 1169 independent reflections. Crenel functions were used for the oxygen and cobalt description and a Gram-Charlier expansion up to the third order of the atomic displacement parameter was employed for one Co atom. The structure is similar to that of Sr(6/5)CoO(3), but with a different sequence of the octahedra and trigonal prism polyhedra along the [CoO(3)] chains. An interesting feature evidenced by the non-harmonic expansion is the displacement of the prismatic Co atoms from the site center, towards the prism rectangular faces.