Various ternary chalcogenide systems and their properties are one of the hot topics for researchers nowadays. In this article, one of the ternary chalcogenide compounds, CdTl2Te4 is studied including its electronic structures and optical properties via first principles calculations using SIESTA code. The structure of the compound has a tetragonal crystal system and the unit cell is periodic in all directions. The band structure showed it is a direct band gap semiconductor which is explained by the density of states. The energy gap obtained is seen to increase on employing external electric field perpendicular to the xy plane, but does not increase on increasing the magnitude of field strength. The optical properties which includes absorption coefficient, reflectance, real & imaginary parts of dielectric function, refractive index and extinction coefficient were calculated for polarized light both in plane and out of the plane, but the interesting modulation in properties were seen for the latter which can open up applications of the compound in UV absorbers, making solar cells, etc. So, the compound being a narrow-gap semiconductor along with its tunable electronic and optical properties can have potential application in the fields such as optoelectronics.
First-Principles Thermodynamic Analysis of Ternary Chalcogenide Phase Change Materials
University of Maryland（马里兰大学）；Institute for Research in Electronics and Applied Physics, University of Maryland（马里兰大学电子与应用物理研究所）；Maryland Energy Innovation Institute, University of Maryland（马里兰大学马里兰能源创新研究所）
Dye-Sensitized Ternary Copper Chalcogenide Nanocrystals: Optoelectronic Properties, Air Stability and Photosensitivity
我们报告的铜硫硒化物以及硒化铜纳米晶体与有机π系统钴β-四氨基酞菁的配体交换的效果，并分析这些混合材料的薄膜的结构，光学和电学性质的变化。紫外-可见吸收光谱和拉曼光谱表明配体与纳米晶表面有很强的相互作用。掠入射小角度X射线散射研究表明，在配体交换后，粒子间距离显着收缩。对于缺铜的硒化铜，这种收缩对电传输的影响可以忽略不计，而对于缺铜的硫化硒化铜，电导率增加了8个数量级，并导致类似金属的温度依赖性传输。我们讨论了这些差异，在光的电子与离子传输在两种材料中的不同贡献，并强调其在环境条件下的传输性能的稳定性的影响。与光电流测量，我们证明了高的光响应度为200-400 A W-1的酞菁封端的硫化硒化铜，并强调在这方面的有机π-系统，作为一个电子连接器和光敏剂在同一时间的有益作用。
Robustness against Disorder of Relativistic Spectral Properties in Chalcogenide Alloys
为了仔细解决替代无序和自旋轨道耦合之间的相互作用，在IV-VI合金，我们提出了一种新的理论方法，集成的可靠性，平面波为基础的密度泛函理论超出局域密度近似与相干势近似。通过将所提出的方法应用于三元硫属合金，我们预测接近费米能的光谱特征对替代无序的实质性鲁棒性。补充我们的第一性原理计算与分析的$k \cdot p$模型的岩盐硫族化物，我们表明，无序自能是消失的小接近带隙，从而允许体拉什巴样自旋分裂观察铁电合金，如PbS $_x$ Te $_{1-x}$，以及保护与最近发现的拓扑晶体绝缘体Pb $_{1-x}$ Sn $_x$ Te中的拓扑转变相关的带特性反转。
Understanding Bulk Defects in Topological Insulators from Nuclear-Spin Interactions
非侵入性的局部探针需要在二元和三元硫属化合物的体缺陷的特征。这些缺陷导致了拓扑绝缘体的非理想行为。用$^{125}$ Te核磁共振研究了Bi $_2$ Te $_3$，Sb $_2$ Te $_3$，Bi $_{0.5}$ Sb $_{1.5}$ Te $_3$，Bi $_2$ Te $_2$ Se和Bi $_2$ $_2$ Te $_2$ S.缺陷的分布引起粉末线形的不对称性。我们展示了如何骑士移位，线的形状和自旋晶格弛豫报告载流子密度，自旋轨道耦合和相分离的散装。本研究证实了有序三元化合物Bi $_2$ Te $_2$ Se是目前最好的TI候选材料。我们的研究结果，这是在良好的协议与运输和ARPES研究，帮助建立NMR探针作为一个有价值的方法来表征这些材料的本体属性。
