Synthesis and crystal structures of BaLaSi2 with cis-trans Si chains and Ba5LaSi6 with pentagonal Si rings
Synthesis and crystal structures of BaLaSi2 with cis-trans Si chains and Ba5LaSi6 with pentagonal Si rings
复制标题
顺反式硅链BaLaSi2和五方硅环Ba5LaSi6的合成及晶体结构
DOI：
10.1021/acs.inorgchem.5b01604
复制
发表时间：
2015
影响因子：
4.6
通讯作者：
Takashi Sekiguchi
中科院分区：
文献类型：
--
作者：
Takayuki Hashimoto;Hisanori Yamane;Takahiro Yamada;Takashi Sekiguchi
在有或没有Na助熔剂的情况下，从元素合成了新型化合物BaLaSi_2和Ba_5LaSi_6的棱柱形单晶。用X射线衍射分析了化合物的晶体结构。BaLaSi_2晶体为正交晶系（a= 4.6414（2）B= 14.8851（7），c= 6.7519（5）;空间群Cmcm（No.63），Z= 4），含有顺-反∞1[Si]链，与LaSi的低温相是同型的。Ba_5LaSi_6（a= 17.1447（5），B= 4.8767（1），c = 17.9102（4），空间群Pnma（No.62），Z= 4）的晶体结构是一种含有孤立的阴离子基团（O [Si_5-Si]）的五角Si环和Si-Si茎的新型结构。在300 K下，多晶BaLaSi 2和Ba 5LaSi 6烧结样品的电阻率分别为0.31和0.48 mΩ·cm，且随温度升高而增大。BaLaSi 2和Ba 5LaSi 6的Seebeck系数在296 K时分别为−7.6和−11 μV·K-1。
Prismatic single crystals of novel compounds BaLaSi2and Ba5LaSi6were synthesized from the elements with or without a Na flux. The crystal structures of the compounds were analyzed by X-ray diffraction. BaLaSi2, containing cis–trans∞1[Si] chains, crystallizes in an orthorhombic cell (a= 4.6414(2) Å,b= 14.8851(7) Å,c= 6.7519(5) Å; space group,Cmcm(No. 63),Z= 4) and is isotypic with the low-temperature phase of LaSi. The crystal structure of Ba5LaSi6(a= 17.1447(5) Å,b= 4.8767(1) Å, andc= 17.9102(4) Å; space groupPnma(No. 62),Z= 4) is a new type containing isolated anionic groups (0[Si5–Si]) of a pentagonal Si ring with a Si–Si stem. The electrical resistivities measured for the polycrystalline BaLaSi2and Ba5LaSi6sintered samples were 0.31 and 0.48 mΩ·cm, respectively, at 300 K and increased with temperature. The Seebeck coefficients of BaLaSi2and Ba5LaSi6were −7.6 and −11 μV·K–1, respectively, at 296 K.