SEMINAR
The State Key Lab of
High Performance Ceramics and Superfine Microstructure
Shanghai Institute of Ceramics, Chinese Academy of Sciences

　　中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室

　　From MAX to MXene - from 3D to 2D

　　Speaker

　　Michel W. Barsoum

　　Department of Materials Science and Engineering

　　Drexel University, Philadelphia

　　时间：4月23日 （星期三）下午3:00

　　地点：2号楼607会议室

　　Dr. Michel Barsoum is Distinguished Professor in the Department of Materials Science and Engineering at Drexel University. He is an internationally recognized leader in the area of MAX phases with over 250 papers on the these phases alone including ones in top-tier journals such as Nature and Science. With an h index > 50, his work has been highly cited and is on ISI’s most highly cited authors list. He is the author of the two entries on the MAX phases in the Encyclopedia of Materials Science, and a book, MAX Phases: Properties of Machinable Carbides and Nitrides, published last year. He is also the author of Fundamentals of Ceramics, a leading textbook in his field. He is fellow of the American Ceramic Society and the World Academy of Ceramics. In 2000 he was awarded a Humboldt-Max Planck Research Award for Senior US Research Scientists and spent his sabbatical year at the Max Planck Institute in Stuttgart, Germany. In 2008 he spent his last sabbatical at Los Alamos National Laboratory as the prestigious Wheatly Scholar. Since 2008 he has also been a visiting professor at Linkoping University in Sweden and in 2013 at Ningbo Institute of Material Technology, in Ningbo, China.

　　Abstract

　　The layered, hexagonal carbides and nitrides with the general formula, Mn+1AXn, (MAX) where n = 1 to 3, M is an early transition metal, A is an A-group (mostly IIIA and IVA) element and X is either C and/or N – sometimes referred to as polycrystalline nanolaminates because every basal plane is a potential deformation or delamination plane - combine some of the best attributes of metals and ceramics.1 Like metals, they are electrically and thermally conductive, most readily machinable (manual hack saw will suffice) not susceptible to thermal shock, plastic at high temperatures, and exceptionally damage tolerant. Like ceramics, they are elastically rigid, lightweight, and maintain their strengths to high temperatures. The ternaries Ti3SiC2 and Ti2AlC are also creep, fatigue and oxidation resistant. Over the past decade we have also shown that the MAX phases are but a subset of solids that we termed kinking nonlinear elastic, KNE, because one of their important deformation mode is the formation of fully reversible, dislocation-based incipient kink bands. The latter is the main reason why the MAX phases combine record combinations of stiffness and damping. In this talk, special emphasis will be given to creep, crack healing and oxidation resistance.

　　More recently we showed that by simply soaking MAX phase powders at room temperature in HF, it is relatively easy to etch out the A-layers of select MAX phases.2 We labeled the resulting 2D materials MXenes to emphasize the loss of the A-group element and their similarities to graphene. Unlike hydrophobic graphene, MXenes are hydrophilic and can be thought of as “conductive clays”, a hitherto rare combination. MXenes such as Ti2C, V2C, Nb2C and Ti3C2 can be used as electrode materials in lithium-ion batteries (LIBs) and supercapacitors (SC’s) with performances that are quite impressive, given their very young age (≈ 2 yrs). Flexible additives-free electrodes of delaminated Ti3C2 showed reversible capacities of > 400 mAhg-1 at 1C and 110 mAhg-1 at 36 C, the latter for > 700 cycles.3 Supercapacitors with volumetric capacities of > 300 F/cm3 were also demonstrated.4 The potential of using MXenes in energy storage and other applications will be highlighted.

　　(1) Barsoum, M. W. MAX Phases: Properties of Machinable Carbides and Nitrides; Wiley-VCH: Weinheim, 2013.

　　(2) Naguib, M. et al. Advan. Mater. 2011, 23, 4248.

　　(3) Mashtalir, O.et al. Nature Comm. 2013, 4, Article Number: 1716.

　　(4) Lukatskaya, M.;et al, Y. Science 2013.