Superconductivity of metal deficient silicon clathrate compounds, Ba8-xSi46 (0 < x ≤ 1.4)
Superconductivity of metal deficient silicon clathrate compounds, Ba8-xSi46 (0 < x ≤ 1.4)
复制标题
DOI：
10.1021/ic020676q
复制
发表时间：
2003-05-05
影响因子：
4.6
通讯作者：
Yamanaka, S
中科院分区：
文献类型：
--
作者：
Fukuoka, H;Kiyoto, J;Yamanaka, S
采用高压高温条件（3GPa，1300 ℃）制备了含Ba的硅笼形超导体Ba7.76Si46的单晶。晶体属立方晶系，空间群Pm-3 n，a = 10.3141（7）埃，Z = 1。在Si十四面体笼（Ba@Si-20）和Si四面体笼（Ba@Si-24）的中心存在两种晶体学上不同类型的Ba位。在527 ℃下抽真空时，一部分Ba原子从Ba@Si-20位点上除去。随着Ba含量从7.76降低到6.63 Ba/Si-46，超导转变温度（Tc）从9.0降低到6.0 K。通过单晶X射线分析中的结构精修确定了Ba缺陷位点和缺陷。
Single crystals of the Ba-containing silicon clathrate superconductor Ba7.76Si46 were prepared using a high-pressure and high-temperature condition (3 GPa, 1300 degreesC). It crystallized in the cubic space group Pm-3n with a = 10.3141(7) Angstrom and Z = 1. There are two crystallographically different types of Ba sites, at the centers of Si clodecahederal (Ba@Si-20) and Si tetrakaidecahedral (Ba@Si-24) cages. On evacuation at 527 degreesC, a part of Ba atoms were removed from the Ba@Si-20 sites. The superconducting transition temperature (T-c) decreased from 9.0 to 6.0 K with the decrease of the Ba content from 7.76 to 6.63 Ba/Si-46. The Ba deficient sites and the deficiency were determined by the structural refinement in the single-crystal X-ray analyses.