Solid State Chemistry of Crystalline and Glassy Chalcogenides

目前的研究计划旨在通过追求和开发金属硫化物的新合成方法来扩大固态可能的范围。该项目涉及盐助剂在广泛的硫族化合物类化合物中发现新材料的有效性以及对这些材料的深入研究。通过发展一般的合成方法来控制化学反应系统和发现新材料的需要定义了我们理解复杂固体中化学、晶体结构和性质之间的关系的主要挑战之一。许多关系都很微妙，也很难理解。特别是，该项目侧重于复杂的三元和四元金属磷酸盐和硫砷酸盐材料。这门课继续提出惊人的科学挑战，它与许多技术应用广泛相关。将应用一套广泛和多样化的定性工具。令人兴奋的新材料有望具有有趣的和潜在的有用的物理性质，如半导体行为、非线性光学活性、玻璃形成和可逆相变晶体到玻璃的转变。该项目将探索(A)多硫代磷酸锂和多硒磷酸盐熔剂，以发现新的无碱金属相和含锂相；(B)合成低价硒磷酸盐和硫代磷酸盐(即含磷原子处于低价态的化合物)；(C)碱金属多硫代砷酸盐和多硒砷酸盐熔剂，以进一步发展这一化学并发现新材料；(D)调查和研究某些硫族化合物化学计量比中玻璃形成系统的性质。这些材料被称为相变材料，与非易失性数据存储和计算机存储器应用相关。本研究的结果将加深我们对硫系化合物的相稳定性、结构、成键和性质的理解。这个项目将教育学生，并让他们接触到有价值的知识话语。参与该项目的学生将接受合成固态化学和材料研究方面的杰出培训。他们将直接认识到他们的材料与科学和技术的相关性。拟议中的活动将努力为学生提供一个有意义的、连贯的研究和教育计划，以便他们作为未来的独立科学家，能够合成、操作和操纵新型固态材料。在美国，提供这种综合培训的实验室相对较少。本科生也参与这种类型的研究，这对他们的大学实验室经历和未来的职业选择产生了持久的影响。非技术摘要新材料是许多先进技术和产品的核心。这个项目寻求使用新的合成技术来发现新材料，并训练学生在这类研究的话语中。这些材料属于更广泛的半导体类别，预计将具有潜在的有用的物理特性和经济价值。这些特性包括可控的导电性、光活性、玻璃形成特性和相变特性。在这个项目中，将研究与非易失性数据存储和计算机存储器应用以及环境中的化学物质传感相关的新的相变材料。在这项工作中开发的方法和在这项工作中获得的关于不寻常固体的形成、化学和性质的见解，可以支持或促进有用的技术，从而可能对科学做出重要贡献，并可能对许多技术产生重大影响，进而对美国经济产生重大影响。毕业生和本科生参与了这类研究，预计这将对他们的大学实验室经历和未来的职业选择产生持久的影响。这项研究的结果将向公众开放，并在发表之前进行同行审查。通过传播媒体、网络和期刊出版物广泛传播科学成果和知识，将有助于提高公众对正在产生的新知识以及对科学的理解和欣赏的认识。

The present research program aims to expand the boundaries of what is possible in the solid state by pursuing and developing new synthetic methodologies for metal chalcogenides. The project deals with the effectiveness of salt fluxes to discover new materials in the broad chalcogenide class of compounds as well as with the in-depth studies of these materials. The need to control chemical reaction systems and to discover new materials through developing general synthetic methodologies defines one of the main challenges to our understanding of the relationships between chemistry, crystal structures, and properties in complex solids. Many of the relationships are subtle and poorly understood. In particular, the project focuses on complex ternary and quaternary metal chalcophosphate and chalcoarsenate materials. This class continues to present marvelous scientific challenges and it is broadly relevant to many technological applications. An extensive and diverse set of characterization tools will be applied. Exciting new materials are anticipated with interesting and potentially useful physical properties such as semiconducting behavior, non-linear optical activity, glass formation, and reversible phase-change crystal to glass transitions. The project will explore (a) lithium polythiophosphate and poly-selenophosphate fluxes to discover new alkali metal-free phases and also lithium-containing phases; (b) the synthesis of low valent selenophosphates and tellurophosphates (i.e. compounds with phosphorous atoms in a low valent state); (c) alkali metal polythioarsenate and polyselenoarsenate fluxes to further develop this chemistry and discover new materials; (d) investigation and study of the properties of glass forming systems occurring in certain chalcogenide stoichiometries.. These are called phase-change materials and are relevant in non-volatile data storage and computer memory applications. The results obtained from this research will enhance our understanding of chalcogenide phase stability, structure, bonding and properties. This project will educate and expose students in a worthwhile intellectual discourse. The students working on the project will receive outstanding training in synthetic solid state chemistry and materials research. They will acquire a direct awareness of the relevance of their materials to science and technology. The proposed activity will strive to furnish a meaningful, coherent research and education program for students so they, as future independent scientists, are able to synthesize, handle and manipulate novel classes of solid-state materials. Relatively few laboratories in the US provide this type of synthesis training. Undergraduate students also participate in this type of research, which has a lasting impact on their college laboratory experience and future career choices. Non-Technical Abstract New materials are at the core of many advanced technologies and products. This project seeks to discover new materials using novel synthesis techniques and to train students in the discourse of this type of research. The materials belong to the broader class of semiconductors and are expected to possess potentially useful physical properties and economic value. These include controllable electrical conductivity, photoactivity, glass forming properties and phase-change properties. In this project will investigate new phase-change materials which are relevant in non-volatile data storage and computer memory applications and in the sensing of chemicals in the environment. The methodology developed and the insights gained during this work, about the formation, chemistry and properties of unusual solids, could enable or facilitate useful technologies and thus could make an important contribution to science and could have a significant impact in a number of technologies and by extension on the US economy. Graduates and undergraduate students participate in this type of research, which is expected to have a lasting impact on their college laboratory experience and future career choices. The results of this research will be open to the public and will undergo peer-review before being published. The broad dissemination of scientific results and knowledge through the communications media, the web and journal publications will help enhance the public's awareness in the new knowledge being generated as well as its scientific understanding and appreciation of science.