Phase relations and kinetics of phase formation of non-equilibrium-solids of pnicogens and chalcogens - Mechanisms of structure formation, synthesis and characterization of element allotropes and compounds -

磷族和硫族非平衡固体的相关系和相形成动力学 - 元素同素异形体和化合物的结构形成、合成和表征的机制 -

• 批准号: 140698662
• 负责人: Professor Dr. Tom Nilges
• 金额: --
• 依托单位: Institut für Materials Resource Management
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/140698662?language=en
• 关键词: Phase; relations; kinetics; phase; formation

In this project, different methods are summarized in the EnPhaSys-concept: quantum chemical modeling and determination of the energy landscape of investigated systems, analysis of phase formation, and inorganic solid state synthesis. This concept is applied to determine the thermodynamic relations of metastable and stable phases, the kinetics of phase formation and transformation of allotropes and compounds of pnicogenes and chalcogenes, and the processes of nucleation and seed growth of the non-equilibrium phases.Three sub-projects are to be processed:A) Mechanisms of phase formation and transformation of allotropes of Phosphorus and Arsenic; investigation of nucleation and seed growth processes by using in-situ-NMR, in-situ-neutron diffraction, and gas phase analysisThis partial project shall fully clarify the thermodynamic relations of allotropes of the elements phosphorus and arsenic. The mechanisms of phase formation and transformation of allotropes are to describe, and the effect of mineralization is to elucidate. Complementary investigations of the kinetics of phase formation by time dependent, isothermal pressure measurements, solid state and gas phase NMR spectroscopy, and powder neutron diffraction of the crystalline phases growth supply information on the identification of formation mechanism and on the nucleation and seed growth processes of the allotropes.B) Identification of metastable and stable candidates showing polymorphism of polyanionic phases MX2 and MXY (X, Y = P, As, Se, Te) and their directed synthesisOrdering phenomena and thus the relations of polymorphism of binary and ternary compounds MX2 and MXY consisting of polyanionic substructures with dumbbells X-X and X-Y shall be investigated. By using the EnPhaSyn concept there is the potential of ordering the polymorphic phases by thermodynamic stability and directing the synthesis in a systematic way depending on different phase stabilities.C) Investigation of order-disorder phenomena of ternary intermetallic LAVES phases; determination of stability criteria of ordered, partially ordered, and disordered phases; directed synthesisTernary LAVES phases commonly exist with random distribution of components and therefore show distinct disordering. Besides these obviously stable phases a plethora of ordered compounds of various compositions is conceivable. It is aim of the project to determine their stabilities and to analyze the phase formation. Based on the discovery of the new representative of ordered LAVES phases, A4B7B‘, by the EnPhaSyn concept, more ordered metastable transition metal - arsenic compounds shall be synthesized. A comparison of the stabilities and the conditions for directed growth of phases of different ordering is intended.

在这个项目中，不同的方法总结了EnPhaSys概念：量子化学建模和确定所研究系统的能量景观，相形成分析和无机固态合成。应用这一概念确定了亚稳相和稳定相的热力学关系，同素异形体和磷属元素、硫属元素化合物的相形成和转变动力学，以及非平衡相的形核和晶种生长过程。利用原位核磁共振、原位中子衍射和气相分析研究成核和晶种生长过程这一部分项目将充分阐明元素磷和砷的同素异形体的热力学关系。阐述了同素异形体的形成和转变机理，阐明了矿化作用。通过随时间变化的等温压力测量、固态和气相NMR光谱以及晶相生长的粉末中子衍射对相形成动力学的补充研究提供了关于同素异形体的形成机制的鉴定以及关于成核和晶种生长过程的信息。B）显示聚阴离子相MX 2和MXY的多晶型的亚稳和稳定候选物的鉴定（X，Y = P，As，Se，Te）及其定向合成研究了由聚阴离子亚结构组成的二元和三元化合物MX2和MXY的有序化现象及其与哑铃X-X和X-Y的多晶型关系。通过使用EnPhaSyn概念，存在通过热力学稳定性使多晶相有序化的可能性，并根据不同的相稳定性以系统的方式指导合成。C）研究三元金属间LAVES相的有序-无序现象;确定有序、部分有序和无序相的稳定性标准;定向合成三元LAVES相通常以组分的随机分布存在，因此显示出明显的无序。除了这些明显稳定的相之外，还可以想象出许多不同组成的有序化合物。本项目的目的是确定它们的稳定性和分析相形成。基于发现有序LAVES相的新代表，A4 B7 B '，通过EnPhaSyn概念，将合成更有序的亚稳过渡金属-砷化合物。比较的稳定性和条件的不同顺序的阶段定向生长的目的。