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

点击翻译按钮获取中文摘要

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