CAREER: Control of Functionality in Transition Metal Oxides with Metal-Metal Bonding

这项由固态和材料化学计划支持的研究旨在通过“内部设计”原则而不是通过不太直接的结构-性能关系来控制材料的功能。 这种方法将被用来寻找新的热电材料的过渡金属氧化物类与直接金属-金属键合，从而提升了典型的d-电子状态的简并性，从而产生小带隙半导体和高密度的状态金属。 将对物理性质（如电阻率、磁性、热电势和热导率）进行彻底的研究，以探索这些化合物的类f电子状态是否可以被调节以产生改进的材料性能，以及这些不寻常的电子状态是否会引起任何意想不到的现象。 此外，还将对这些材料进行光谱研究，以测试这些材料作为稳定的小带隙半导体用于光学应用的潜力。 通过这些研究，应该可以开发一个框架，以更好地理解这类有趣的化合物。 这项工作将得到支持的努力，以发展同步加速器微晶技术的长期目标，获得单晶衍射数据的微晶在典型的粉末samples.Non-Technical摘要：许多高科技设备的性能是有限的固态材料的属性，从它们被建立。 该项目将测试用于能源应用的固态材料设计的新策略，直接将理论计算纳入设计过程，以有效地发现改进的材料。 该项目的主要目标是更好的热电材料，通过废热回收，卫星发电和高效固态制冷应用于电力生产。 正在研究的金属氧化物系统还可以提供用于红外（IR）检测应用的新的超导化合物和新的小带隙半导体，其可以用作基于碲化镉汞化合物的当前系统的空气稳定且无毒的替代物。基本的合成，表征和必要的理解和进行材料的“内部设计”的理论技能将被纳入教学和推广工作，因为它们提供了产生能源和其他社会挑战的材料解决方案所需的关键见解。 特别强调晶体学，包括旨在解决典型学术课程中的缺陷和扩大在X射线和中子国家实验室设施的实验参与的国家教育努力。 对各级对能源研究感兴趣的学生进行积极的研究指导将是这一努力的一个关键组成部分，包括纽约市大都会区的各种本科生和高中生。

TECHNICAL SUMMARY:This research supported by the Solid State and Materials Chemistry program aims to control the functionality of materials by targeting specific electronic structures through "internal design" principles rather than through less direct structure-property relationships. This approach will be used to find new thermoelectric materials within the class of transition metal oxides with direct metal-metal bonding, which lifts the typical degeneracy of the d-electron states giving rise to both small band gap semiconductors and high density-of-states metals. A thorough investigation of physical properties (such as resistivity, magnetism, thermopower, and thermal conductivity) will be undertaken to explore whether the f¬-electron-like states of these compounds can be tuned to produce improved materials performance, and whether these unusual electronic states give rise to any unexpected phenomena. In addition, spectroscopic studies of these materials will be carried out to test the potential of these materials as stable small band gap semiconductors for optical applications. Through these investigations, it should be possible to develop a framework for better understanding this intriguing class of compounds. This work will be supported by efforts to develop synchrotron microcrystallography techniques with the long term goal of obtaining single crystal diffraction data from the crystallites in typical powder samples.NON-TECHNICAL SUMMARY:The performance of many high-tech devices is limited by the properties of the solid state materials from which they are built. This project will test new strategies for designing solid state materials for energy applications, directly incorporating theoretical calculations into the design process to efficiently discover improved materials. The primary target of this project is better thermoelectric materials, which have applications for electricity production through waste heat recovery, satellite power generation, and efficient solid state refrigeration. The metal oxide systems being studied may also provide new superconducting compounds and new small band gap semiconductors for infrared (IR) detection applications that can serve as air stable and non-toxic alternatives to current systems based on cadmium mercury telluride compounds. The fundamental synthesis, characterization, and theoretical skills necessary to understand and carry out the "internal design" of materials will be integrated into teaching and outreach efforts, as they provide the key insights needed to generate materials solutions for energy and other societal challenges. Particular emphasis is placed on crystallography, including national educational efforts aimed at addressing deficiencies in typical academic curricula and at broadening participation in experiments at x-ray and neutron national laboratory facilities. Active research mentoring of students interested in energy research at all levels will be a key component of this effort, including the diverse undergraduate and high school students in the New York City Metropolitan area.