Rational synthesis planning, structure systematics and physical properties of rare earth metal polytellurides RETe2-x

基于热分析和张力学研究，采用模型计算，研究了二元稀土金属多碲化物RETe2-x （RE = Y, La - Lu; 0 < x <0.2）的相平衡、稳定场和精确化学组成。澄清同一种稀土金属不同成分的多碲化物的存在，即不同的含硫缺陷。一个问题是阐明RE4Te7组成的化合物，这些化合物在旧文献中经常被引用，但没有结构数据可用。然后根据合理的合成计划制备多碲化物相，并确定晶体生长的适当参数。然后在单晶上阐明多碲化物的晶体结构。这些结构将被系统化，化学键，特别是在多碲阴离子中，将被研究。与具有类似组成的多硫化物和多硒化物相比，所述组合物中少数已知的土金属多碲化物表现出具有较高缩合等级的硫族化合物单元，从而产生不同的电子性质。在多碲化物中，特别是在聚阴离子亚结构中的化学键将被详细地分析，特别是用基于位置空间的方法。此外，磁性和光学性质以及电输运性质将被研究。作为该项目的结果，我们期望对理解稀土金属多碲化物RETe2-x的相关系和分解机制，它们的结构分类和化学和物理性质，最后但并非最不重要的是，对这类化合物的化学键的理解做出重大贡献

Based on thermal analysis and tensiometric studies and employing modeling calculations the phase equilibria, stability fields and precise chemical compositions of binary rare earth metal polytellurides RETe2-x (RE = Y, La - Lu; 0 < x <0.2) shall be examined In this project. The existence of polytellurides with different compositions of one and the same rare earth metal, i. e. different chalcogen defects shall be clarified. One issue is to shed light on compounds of the composition RE4Te7 which are quoted quite often in the older literature but for which no structural data are available. The polytelluride phases shall then be prepared based on a rational synthesis planning and appropriate parameters for the crystal growth shall be determined. The crystal structures of the polytellurides shall then be elucidated on single crystals. The structures will be systematized, and the chemical bonding, particularly in the polytelluride anions, will be investigated. In contrast to polysulfides and polyselenides of similar composition, the few known earth metal polytellurides of the compositions in question exhibit chalcogenide units with higher grades of condensation, resulting, e. g., in different electronic properties. The chemical bonding in the polytellurides, particularly in the polyanionic substructures are to be analyzed in detail, especially with position-space based methods. In addition magnetic and optical properties as well as electrical transport properties will be investigated.As results of the project, we expect significant contributions to the understanding of phase relationships and decomposition mechanisms of earth metal polytellurides RETe2-x, to their structural classification and to chemical and physical properties and, last but not least, to the chemical bonding in this class of compounds