Synthesis and Properties of Complex Crystalline and Glassy Metal Chalcogenides

新材料不仅影响物理科学，也影响经济增长。在基层，固态和材料化学社区认识到开发合理的材料发现策略和识别在我们对物理化学性质和技术进步的理解中具有变革性的材料的巨大挑战。在材料研究部固态和材料化学项目的支持下，该项目通过开发金属硫族化合物的化学来帮助解决这一挑战。在此背景下，研究团队正在构建一个理性的、科学驱动的基础，以获取最大的科技效益。该项目的主要目标是发现和表征新型金属硫系化合物，并了解它们的结构、化学键和物理性质。如果成功，将出现新的材料，使新的应用或提高现有技术应用的有效性。该项目采用熔盐作为强大的反应介质，在其中寻求具有不同寻常物理性质的新材料的形成。该项目对固态和材料化学领域研究生的培训和教学做出了重大贡献，并有助于培养理解新材料作为新现象和新技术驱动力重要性的未来劳动力。本研究的主要目标是发现和表征新型金属硫系化合物，并了解其结构、化学键和物理性质。该项目采用盐通量合成技术寻求具有新颖结构和成分的新材料。良好定义的构建块存在于通量反应中，通过调节通量组成和温度来指导它们的形成，从而控制刘易斯碱度和氧化还原电位。在这个合成程序中，一个重要的问题是，是否可以使用中间温度来指导熔盐中发生的基本化学反应，以抑制不良化合物的形成，并有利于新化合物的结晶。该项目基于结构-组成-属性关系的总体主题，并以以下问题为中心：如何开发工具和概念，无论是智力还是实验，以发现新的功能材料。以硫族化合物为重点，本项目有以下几个方向：(a)多硫族化合物助熔剂的合成，重点研究早期过渡金属和主族金属、混合金属体系以及硫、碲、砷酸盐和锑酸盐化学；(b)使用含氧化盐的混合硫系熔剂合成；(c)从晶体化合物及其相变行为中创造新的玻璃；(d)对选定的有前途的硫系物相进行溶解研究，以评估其加工成更有用形式的潜力。该项目有望丰富人们对不同寻常和多样化的金属chalcommetalallate构建块的认识，以及它们在创造新化合物中所起的作用。实验表征工具包括x射线晶体学、光学、红外和拉曼光谱、扫描和透射电子显微镜、差热分析和扫描量热，以及电导率和光学二次谐波产生的测量。

Non-technical SummaryNew materials impact not only the physical sciences but also economic growth. At a grassroots level, the solid state and materials chemistry community recognizes the grand challenge of developing rational materials discovery strategies and identifying materials that are transformative in our understanding of physicochemical properties and in technological progress. With support from the Solid State and Materials Chemistry Program in the Division of Materials Research, this project help address this challenge by developing the chemistry of metal chalcogenides. In this context, the research team is building a rational, science-driven foundation to extract maximum scientific and technological benefit. The primary goals of this projecct are to discover and characterize new types of metal chalcogenide compounds, and to understand their structures, chemical bonding and physical properties. If successful, new materials enabling new applications or enhancing the effectiveness of existing technological applications will emerge. The project employs molten salts as powerful reaction media in which to seek formation of new materials with unusual physical properties. The project contributes significantly to the training and teaching of graduate students in the field of solid state and materials chemistry and helps to create a future workforce that understands the importance of new materials as drivers for new phenomena and technologies. Technical SummaryThe primary goals of this research are to discover and characterize new types of metal chalcogenide compounds, and to understand their structures, chemical bonding and physical properties. The project employs salt flux syntheses to seek new materials with novel structure and compositions. Well-defined building blocks are present in the flux reactions and their formation is guided by tuning the flux composition and temperature, which controls Lewis basicity and redox potential. An important question in this synthesis program is whether, using intermediate temperatures, one can guide the fundamental reaction chemistry occurring in molten salts to suppress the formation of undesirable compounds and favor crystallization of new ones. The project is based on the general theme of structure-composition-property relationships with the following question being central: How does one develop the tools and concepts, both intellectual and experimental, to discover new functional materials. Focusing on the chalcogenide class the project has the following directions: (a) synthesis in polychalcogenide fluxes focusing on early transition and main group metals, mixed metal systems and also on thio and telluro-arsenate and antimonate chemistry; (b) synthesis using mixed chalcogenide fluxes incorporating oxide salts; (c) creation of novel glasses from the crystalline compounds and their phase change behavior and (d) dissolution studies of selected promising chalcogenide phases to assess their potential for processing into more useful forms. The project is expected to enrich the knowledge of unusual and diverse chalcometallate building blocks and role they play in creating new compounds. Experimental characterization tools to be employed include X-ray crystallography optical, infrared and Raman spectroscopy, scanning and transmission electron microscopy, differential thermal analysis and scanning calorimetry, and measurements of electrical conductivity as well as optical second harmonic generation.