High-pressure synthesis and crystal growth of the polar metal LiOsO3

第一部分：非技术概述晶体是许多现代技术的基础。由于其高度的结构完美性和化学可调成分，晶体是微电子学，光学和激光技术以及光化学的核心。掌握最先进材料的晶体生长技术是美国科技竞争力的关键。该项目由材料研究部的固态和材料化学项目支持，重点关注新发现的氧化物材料晶体的生长，其中包括很少研究的元素锇。 为了充分理解这种材料的奇异物理特性和潜在的微观相互作用，需要大而高质量的晶体。本项目所获得的知识将有益于传感器技术和光电子学中新型功能材料的设计。 本科生将参与该项目，还将参与外展计划，如女高中生的爱丽丝梦游仙境和学生，家长和教师的年度探索UT活动。第二部分：钛铁矿LiOsO 3于2013年首次报道，是一种极性金属固体，是研究金属和铁电性能之间相互作用的绝佳候选材料。它在0.1 K时是金属的，在130 K时经历二级非极性到极性的结构转变。向极性结构的转变极大地改变了电子行为，但是移动的电子仍然屏蔽偶极子彼此相互作用，因此极性状态是不可切换的。电子在偶极子存在下如何运动仍然知之甚少。为了可靠地揭示物理特性，必须使用先进的探针对大型高质量晶体进行测量，但晶体生长仍然是LiOsO 3研究的瓶颈。该项目由材料研究部门的固态和材料化学计划支持，旨在通过使用高温和高压条件生长高质量的LiOsO 3大晶体。通过（1）绘制压力-温度相图中的生长条件和（2）起始材料和助熔剂的最佳选择来促进晶体生长。晶体质量将通过劳厄背反射和X射线衍射摇摆曲线扫描来检查。该项目中生长的晶体不仅将在PI的实验室中进行研究，还将提供给其他具有先进表征设施但缺乏高压下晶体生长手段的研究实验室，这将有助于研究的更广泛影响。本科生将参与该项目，也将参与外展计划，如女高中生的爱丽丝梦游仙境和学生，家长和教师的年度探索UT事件。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

PART I: NON-TECHNICAL SUMMARYCrystals are the basis for many modern technologies. With their high degree of structural perfection and chemically tunable compositions, crystals are at the heart of microelectronics, optics and laser technologies, and photovoltaics. Keeping an edge on the technology of crystal growth for the most advanced materials is a key in US competitiveness in science and technology. This project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, focuses on the growth of crystals of a newly discovered oxide material that includes the rarely studied element osmium. Large, high-quality crystals are needed in order to fully understand the exotic physical properties of this material and the underlying microscopic interactions. The knowledge gained from the project will benefit the design of new functional materials in sensor technology and photovoltaics. Undergraduate students will work on the project and will also be involved in outreach programs such as Alice in Wonderland for female high school students and the annual Explore UT event for students, parents, and teachers. PART II: TECHNICAL SUMMARYThe ilmenite LiOsO3, first reported in 2013, is a polar metallic solid that is an excellent candidate for examining the interplay between metallic and ferroelectric properties. It is metallic to 0.1 K and undergoes a second order non-polar to polar structural transition at 130 K. The transition to a polar structure changes the electronic behavior dramatically, but mobile electrons remain to screen the dipoles from interacting with one another so the polar state is not switchable. How electrons move in the presence of dipoles remains poorly understood. To reveal physical properties reliably, measurements with advanced probes on large, high-quality crystals are necessary, but crystal growth remains a bottleneck in the study of LiOsO3. This project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, aims to grow high quality, large crystals of LiOsO3 by using high-temperature and high-pressure conditions. The crystal growth will be enhanced by (1) mapping the growth conditions in the pressure-temperature phase diagram and (2) optimal selection of the starting materials and flux. Crystal quality will be checked by Laue back reflection and X-ray diffraction rocking-curve scans. Crystals grown in this project will be not only studied in the PI's lab, but also provided to other research laboratories with advanced characterization facilities but lacking the means for crystal growth under high pressure, which will contribute to the broader impacts of the research. Undergraduate students will work on the project and will also be involved in outreach programs such as Alice in Wonderland for female high school students and the annual Explore UT event for students, parents, and teachers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.