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属化合物的新合成方法来扩大固态可能的范围。该项目涉及盐通量在广泛的硫系化合物类别中发现新材料的有效性以及对这些材料的深入研究。控制化学反应系统和通过开发通用合成方法发现新材料的需要，是我们理解复杂固体中化学、晶体结构和性质之间关系的主要挑战之一。其中许多关系都很微妙，而且很难理解。特别是，该项目侧重于复杂的三元和四元金属铜磷酸盐和铜酸盐材料。这门课继续呈现出奇妙的科学挑战，它与许多技术应用广泛相关。一套广泛而多样的表征工具将被应用。令人兴奋的新材料有望具有有趣和潜在有用的物理性质，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)聚硫代磷酸锂和聚硒代磷酸锂助熔剂，以发现新的无碱金属相和含锂相；(b)合成低价的硒磷酸盐和碲磷酸盐（即磷原子处于低价状态的化合物）；(c)碱金属多硫胂酸盐和多硒胂酸盐助熔剂，以进一步发展这种化学和发现新材料；(d)在某些硫化物化学计量学中发生的玻璃形成系统的性质的调查和研究。这些被称为相变材料，与非易失性数据存储和计算机内存应用有关。本研究结果将加深我们对硫系化合物相稳定性、结构、键合和性能的认识。这个项目将在一个有价值的知识话语中教育和暴露学生。参与该项目的学生将在合成固体化学和材料研究方面接受出色的培训。他们将直接意识到他们的材料与科学技术的相关性。拟议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、处理和操纵新型固态材料。在美国，提供这类合成训练的实验室相对较少。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有持久的影响。新材料是许多先进技术和产品的核心。该项目旨在利用新颖的合成技术发现新材料，并训练学生进行这类研究。这种材料属于更广泛的半导体类别，有望具有潜在的有用物理特性和经济价值。这些特性包括可控电导率、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对环境中的化学物质的感知有关的新的相变材料。在这项工作中开发的方法和获得的见解，关于不寻常固体的形成，化学和性质，可以推动或促进有用的技术，从而可以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。研究生和本科生参与这类研究，预计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，并在发表之前经过同行评审。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的认识，以及对科学的理解和欣赏。

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.