Chemically Tunable Acoustic Phonons in 2D Materials

非技术概述声学声子是在材料中移动并控制重要特性（如刚度、热传导以及材料在电子设备中的工作方式）的声波。通过这个项目，由材料研究部的固态和材料化学项目支持，加州大学戴维斯分校的Kristie Koski教授将研究新的二维（2D）材料中的声学声子，这些材料只有几个原子厚，声子的行为非常不寻常，也没有得到很好的理解。2D材料对于从电子到能源到传感器的广泛应用是令人兴奋的。为了充分实现这些应用，需要了解和控制材料特性。该项目使用精确的激光光谱测量来详细绘制声子行为，并探索如何使用化学来修改和定制声子行为，以生产以前从未存在过的2D材料。这是设计为未来设备，能源系统和服务于国家利益的行业优化的2D材料所需的知识。 教育和更广泛的推广目标包括为科学界和更广泛的公众社区建立一个在线布里渊光谱数据库。招募美国退伍军人参与这项研究工作。本科生，有针对性地招聘妇女和少数民族，培养在科学和工程的职业生涯。技术概述随着2D材料融入新技术，材料尺寸达到量子极限，声学声子效应改变材料的机械性能，影响热传输，影响电子传输。在这个项目中，由材料研究部的固态和材料化学计划支持，旨在了解二维材料中的声学声子，填补基础知识的主要空白，同时解决悬而未决的问题：在哪里从体材料到量子声学声子行为的交叉在二维材料中？这项工作开发了一套变革性的固态化学技术，以合成和化学控制2D氧化物和硫属化物（S，Se，Te基）材料的基本声学声子行为。这些材料是使用新的合成路线产生的异质结构和新的零价插层化学。布里渊激光光散射光谱用于测量和理解二维层状材料中的声学声子。测量给出完整的声学声子色散关系，声速，折射率，机械性能和刚度系数的2D材料从散装到单层。这项工作为未来应用二维材料中声子的基本理解和化学控制奠定了重要基础。这项工作的发展，增强，并扩大了在线布里渊光谱数据库补充类似的可用数据库在拉曼和X射线衍射。这项工作培训大学生从事研究，重点是招聘妇女和少数民族。退伍军人通过加州大学戴维斯分校退伍军人成功中心招募参与研究。该奖项反映了NSF的法定使命，并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，被认为值得支持。

NON-TECHNICAL SUMMARYAcoustic phonons are sound waves that move in materials and control important properties like stiffness, heat conduction, and how materials work in electronic devices. With this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, Professor Kristie Koski at the University of California, Davis, will study acoustic phonons in new two-dimensional (2D) materials that are only a few atoms thick, where the behavior of phonons is very unusual and not well understood. 2D materials are exciting for a wide range of applications from electronics to energy to sensors. To fully realize these applications requires understanding and controlling material properties. This project uses precise laser-light spectroscopy measurements to map out the phonon behavior in detail, and it also explores how to modify and customize the phonon behavior using chemistry to produce 2D materials that have never before existed. This is the kind of knowledge needed to design 2D materials optimized for future devices, energy systems, and industries serving the national interest. Educational and broader outreach goals include an online Brillouin spectroscopy database for the scientific and broader public communities. US Military Veterans are recruited for participation in this research effort. Undergraduate students, with targeted recruitment of women and minorities, are trained for careers in science and engineering.TECHNICAL SUMMARYAs 2D materials become integrated into new technologies, and material dimensions reach quantum limits, acoustic phonon effects alter material mechanical properties, affect heat transport, and impact electronic transport. In this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, aims to understand acoustic phonons in 2D materials, filling a major gap in fundamental knowledge while addressing the outstanding question: Where is the cross-over from bulk to quantum acoustic phonon behavior in a 2D material? This effort develops a transformative set of solid-state chemistry techniques to synthesize and chemically control the fundamental acoustic phonon behavior of 2D oxide and chalcogenide (S, Se, Te-based) materials. These materials are generated using new synthetic routes to heterostructures and new zero-valent intercalation chemistries. Brillouin laser light scattering spectroscopy is used to measure and understand acoustic phonons in 2D layered materials. Measurements give complete acoustic phonon dispersion relations, sound velocities, refractive indices, mechanical properties, and stiffness coefficients of 2D materials from the bulk to a monolayer. This effort lays critical foundation for the fundamental understanding and chemical control of phonons in 2D materials for future application. This work develops, enhances, and expands upon an online Brillouin spectroscopy database complementing similarly available databases in Raman and X-ray Diffraction. This work trains undergraduates in research with emphasis on recruitment of women and minorities. Military Veterans are recruited for participation in research through the UC Davis Veteran Success Center.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.