Two-Dimensional Layered Materials: Thermodynamic and Electrical Studies

本项目由材料研究部固体与材料化学学科资助，主要开展小晶体性质的基础科学研究、研究生和本科生的教育以及纳米热法等专业科学仪器的进一步开发。使用一种新发现的方法，将生长出重要材料的小的二维晶体，并研究其熔化温度和导电电子性能。对这些晶体的全面研究将有助于开发电子材料的突破性技术，并将为生物膜科学提供新的认识。快速扫描纳米量热法的进一步发展也将加强国家科学仪器的基础设施。其中一个重要的更广泛的影响目标将是通过在美洲土著社区内建造设备（例如电压表和学生纳米热量计测量太阳能和电池热量）来增加对科学和技术教育的参与。黑脚社区学院（BFCC）位于蒙大拿州布朗宁，这是黑脚国家的中心。活动包括为当地初高中和社区大学的学生举办的科学夏令营。研究团队包括来自BFCC和伊利诺伊大学的教师和学生。技术摘要：研究小组将制备和表征极薄的二维层状材料晶体（如石墨烯和硫族化合物）。所有二维层状材料的一个关键属性是层之间非常弱的范德华键，这使得只有几层的堆叠。这些材料的特殊热力学和电子特性只有在晶体非常薄的情况下才能显现出来——薄到像单层原子或分子一样。该项目的重点是利用在首席研究员实验室开发的新开发的气相沉积技术合成和表征银烷硫酸酯（AgSCn）和硫属化合物的变化。AgSCn晶体的刚性中心（Ag-S）平面控制着晶体结构，是其独特电子性能的关键。合成活性主要集中在逐渐减少AgSCn（和硫属化合物）的层数至单层，并减少烷烃侧链的链长(n)至单碳（AgSC1）硫酸盐。利用能够测量单层原子熔化的纳米量热法，首席研究员将测量AgSCn晶体的熔化特性。研究小组还将使用导电探针原子力显微镜研究AgSCn和硫族化合物晶体的垂直和横向导电性能。这种双重合成和表征方法将揭示这两种材料系统的最终结构和电子特性。对这些系统的新认识适用于生物脂质膜，这是单层材料的另一个例子，由单个双层有机分子组成。

Non-Technical AbstractWith support from the Solid State and Materials Chemistry Program in the Division of Materials Research, this project focuses on the basic scientific research of the properties of small crystals, the education of graduate and undergraduate students, and the further development of specialized scientific instruments such as nanocalorimetry. Using a newly discovered method, small, two-dimensional crystals of important materials will be grown and the melting temperature and conductive electronic properties will be investigated. The comprehensive study of these crystals will help develop breakthrough technologies in electronic materials and will provide a new understanding in biological membrane science. Further development of fast-scanning nanocalorimetry will also enhance the national infrastructure of scientific instrumentation. One of the important broader impact goals will be to increase participation in scientific and technical education through the building of devices (e. g. voltmeter and student nanocalorimeter measuring solar and battery heat) within the Native American community. Blackfeet Community College (BFCC) is located in Browning, Montana, which is the center for the Blackfeet Nation. The activities include a Science Summer Camp at the BFCC for the local students from the middle school, high school and the community college. The research team includes faculty and students from BFCC and the University of Illinois. Technical AbstractThe research team will prepare and characterize extremely thin crystals of two-dimensional layered materials (e.g. graphene and chalcogenides). One key attribute of all two-dimensional layered materials is the very weak van der Waal bonding between layers which allows the stacking of just a few layers. Special thermodynamic and electronic properties of these materials are only revealed if the crystals are extremely thin - as thin as a single layer of atoms or molecules. The focus of this project is to synthesize and characterize variations of silver alkanethiolates (AgSCn) and chalcogenides using a newly developed vapor deposition technique developed in the principal investigator's laboratory. The rigid central (Ag-S) plane of the AgSCn crystal controls crystal structure and is the key to its unique electronic properties. The synthesis activity focuses on incrementally decreasing the number layers of AgSCn (and chalcogenides) down to a single layer and decreasing the chain-length (n) of the alkane side chains down to one-carbon (AgSC1) thiloate. Using nanocalorimetry, which has the capability of measuring the melting of a single layer of atoms, the principal investigator will measure the melting characteristics of AgSCn crystals. The research team will also study the vertical and lateral conductive properties of the AgSCn and chalcogenides crystals using conductive probe atomic force microscopy. This dual synthesis and characterization approach will uncover the ultimate structural and electronic properties of these two material systems. New understanding of these systems is applicable to biological lipid membranes which are another example of single-layer materials, consisting of a single bilayer of organic molecules.