Solid State Chalcogenides From Intermediate Temperatures. Exploratory Synthesis in Molten Salts

9622025坎纽乌夫 本研究是关于使用熔融多硫族化物盐作为反应介质，探索在低温和中温（200-500 ℃）下合成新的硫族化物材料。各种A2 QX盐（A=碱金属阳离子，Q=S、Se、Te）将用于与后过渡金属和主族元素的反应。 重点将在四元相的稳定。本阶段将探索三种季铵化合物。一种是混合金属体系A/M/M ′/Q（M=后过渡金属，M ′ =镧系元素，锕系元素）。 第二种是混合硫属元素体系A/M/S/Te。合成方法将使用二元合金化合物作为起始材料和混合焊剂，例如混合A2 TexSy。 第三类是硫代和硒代磷酸盐助熔剂在材料合成中的应用.这些助熔剂是新的，并且被设计用于产生含有PxQy n-聚阴离子（其中Q=S，Se）的新型硫代磷酸盐和硒代磷酸盐固体。新化合物的物理性质，如光谱，热和磁性将作为温度的函数进行研究。为了探测不寻常的电子现象，新化合物的电荷传输特性将通过变温四探针电阻率和热电功率（塞贝克）测量单晶进行详细研究。 这项研究关注的是发现具有各种重要技术性能的新型固态材料的新方法。将进一步研究有前途的材料，并评估其应用潜力。该提案的主题是使用熔融盐作为溶剂进行反应。熔盐用于高温单晶生长已有100多年的历史。 虽然许多盐是高熔点物质，但二元盐和多原子物质的盐的低共熔组合通常具有远低于经典固态合成的温度的熔点，使得它们有可能在中间温度下用于探索新化学。在某些情况下，这些盐不仅作为溶剂，而且作为反应物，提供可以掺入最终产物中的物质。这些研究是重要的，因为多硫化物配体已经涉及原油的加氢脱硫，其中它们被认为存在于金属硫化物催化剂的表面。多硫族化物玻璃作为非线性光学、IR波导、光开关和光信息存储的材料也是重要的，但是由于化合物的无定形性质，结构/性能关系还没有很好地确定。

9622025 Kannewurf This research is concerned with the use of molten polychalcogenide salts as reactive media to explore the synthesis of new chalcogenide materials at low and intermediate temperatures (200-500 C). Various A2QX salts (A=alkali cation, Q=S, Se, Te) will be used in reactions with late transition metals and main-group elements. Emphasis will be given in the stabilization of quaternary phases. Three kinds of quaternary compounds will be explored in this stage. One kind involves the mixed-metal system A/M/M'/Q (M=late transition metal, M'=lanthanide, actinide). The second involves the mixed-chalcogen system A/M/S/Te. The synthetic approach will use binary alloy compounds as starting materials and mixed fluxes such as mixed A2TexSy. The third kind involves the use of the thio- and seleno- phosphate fluxes in materials synthesis. These fluxes are new and are designed to yield novel thiophosphate and selenophosphate solids containing the PxQy n- polyanions (where Q=S, Se). The physical properties of the new compounds, such as spectroscopic, thermal and magnetic will be studied as a function of temperature. In order to probe for unusual electronic phenomena, the charge transport properties of the new compounds will be studied in detail via variable temperature four-probe resistivity and thermoelectric power (Seebeck) measurements on single crystals. %%% This research is concerned with new methodologies to discover new solid state materials having various technologically important properties. Promising materials will be studied further and their potential for applications will be evaluated. The subject of this proposal is performing reactions using molten salts as solvents. Molten salts have been employed for well over 100 years for high temperature single crystal growth. Although many salts are high melting species, eutectic combinations of binary salts and salts of polyatomic species often have melting points well below the temperatures of class ical solid-state synthesis, making possible their use in the exploration of new chemistry at intermediate temperatures. In some cases, such salts act not only as solvents, but also as reactants, providing species which can be incorporated into the final product. Such studies are important because polysulfide ligands have been implicated in the hydrodesulfurization of crude oil, where they are thought to be present at the surface of metal sulfide catalysts. Polychalcogenide glasses also are important as materials for non-linear optics, IR wave guides, optical switching, and optical information storage, but the structure/property relationships have not been well determined due to the amorphous nature of the compounds.