学术报告:Nanomechanical Characterization and Strain Engineering of Two Dimensional Materials
报告人:楼峻(Department of Materials Science and NanoEngineering, Rice University)
报告时间:7月7日15:00
报告地点:主楼10层小松讲学堂
报告简介:
Two-dimensional (2D) materials, such as Graphene, hBN and MoS2, are promising candidates in a number of advanced functional and structural applications, owing to their exceptional electrical, thermal and mechanical properties. Understanding mechanical properties of 2D materials is critically important for their reliable integration into future electronic, composite and energy storage applications. However, it has been a significant challenge to quantitatively measure mechanical responses of 2D materials, due to technical difficulties in the nanomechanical testing of atomically thin membranes. Additionally, actively tuning functional properties of 2D materials by stress/strain is a very attractive approach for engineering these atomically thin components in practical applications. In this talk, we will discuss our recent effort to determine the engineering relevant fracture toughness of graphene, rather than the intrinsic strength that governs the uniform breaking of atomic bonds in perfect graphene. Our combined experiment and modeling verify the applicability of the classic Griffith theory of brittle fracture to graphene. Strategies on how to improve the fracture resistance in graphene will be discussed. In another example, we systematically characterize chemical vapour deposition-grown MoS2 by photoluminescence spectroscopy and mapping and demonstrate non-uniform strain in single-crystalline monolayer MoS2 and strain-induced bandgap engineering. By evaluating the effective strain transferred from polymer substrates to MoS2 using three-dimensional finite element analysis, we demonstrate how strain concentration propagates in a triangular MoS2 monolayer crystal and propose substrates’ Young’s modulus as dominating mechanisms of strain loss.
Short Bio:
Jun Lou obtained B.E. and M.S. degrees in Materials Science and Engineering from Tsinghua University and Ohio State University, respectively, and his Ph.D. degree from the Department of Mechanical and Aerospace Engineering and Princeton Materials Institute at Princeton University. After a brief postdoc at Brown University he joined Rice University, and directs the Nanomaterials, Nanomechanics and Nanodevices Lab (N3L). He is currently a full professor and the associate chair of the department of Materials Science and NanoEngineering. Lou is an AFOSR Young Investigator and a recipient of Charles Duncan Award for Outstanding Academic Achievement at Rice. He is currently the Editor-in-Chief of Materials Today, the Elsevier flagship journal (Impact factor: 21.7) covering original research and reviews in the broader materials science community. He currently serves as the site director for the NSF industry university collaborative research center (IUCRC) of Atomically Thin Multifunctional Coatings (ATOMIC) that has 13 member companies, exploring potential applications of 2D materials in different industries with commercial partners. Lou has extensive experience in the synthesis and design of 2D materials beyond Graphene and other nanomaterials; mechanical and multi-physics characterization, and fabrication of advanced material systems and devices. His group has made pioneering contributions in the area of nanomechanics including discovering of the “cold welding” phenomena in Au nanowires and performing the first experimental measurement of the fracture toughness of graphene.
联系人:慈立杰