TOF-neutron diffraction study of liquid Tl-As2X3 systems (X: Se, Te)
TOF-neutron diffraction study of liquid Tl-As2X3 systems (X: Se, Te)
复制标题
液体 Tl-As2X3 系统的 TOF 中子衍射研究（X：Se、Te）
DOI：
10.1016/s0022-3093(96)00374-2
复制
发表时间：
1996
影响因子：
3.5
通讯作者：
O. Uemura
中科院分区：
文献类型：
--
作者：
Y. Kameda;T. Usuki;O. Uemura
测量了液体Tl-As2Te3和Tl-As2Se3体系的飞行时间中子衍射谱，这两个体系在富Tl组分上都表现出金属-非金属相变。液态As_2Te_3在第一配位壳层中含有直接的As-As键以及As-Te和Te-Te键，而液态As_2Se_3在第一配位壳层中只含有As-Se键。通过与观测强度函数的最小二乘拟合，确定了As和Te、Se的配位数分别为3个和2个。在液体As_2X_3(X：Te或Se)中，S(Q)的第一个尖锐衍射峰与-As-X-As键有关，随着Tl的加入，第一个锐利衍射峰迅速减小，并在Tl-As_2X_3系的过渡区完全消失。在液态Tl-As2Te3体系中，随着Tl含量的增加，Ass-Te键逐渐被部分离子的Tl-Te键取代，导致Tl6As2Te3处急剧的金属-非金属转变。另一方面，液体硒系中的As-Se键即使在过渡组分附近仍然存在，在很大的组成范围内强烈地影响着电子性质。
Time-of-flight neutron diffraction has been measured on both liquid Tl-As2Te3and Tl-As2Se3systems, which exhibit the metal-non-metal transition at the Tl-rich composition. Liquid As2Te3contains direct As-As bonds in the first coordination shell as well as As-Te and perhaps Te-Te bonds, while liquid As2Se3contains only As-Se bonds in the first coordination shell. The coordination number of component atoms in both liquids was determined to be three for As, and two for Te and Se, through a least-squares fit to the observed intensity function. The first sharp diffraction peak in S(Q) in liquid As2X3(X: Te or Se), relating to -As-X-As- linkages, rapidly decreases upon the addition of Tl and disappears completely in the transition composition range in both liquid Tl-As2X3systems. In the liquid Tl-As2Te3system, Ass-Te bonds are gradually replaced by partially ionic Tl-Te bonds with increasing Tl content, leading to the sharp metal-non-metal transition at Tl6As2Te3. On the other hand, As-Se bonds in the liquid selenide system remain even in the vicinity of the transition composition, strongly influencing the electronic properties over a wide composition range.