报告时间：2025年10月14日（星期二）10:00-11:30
报告地点：学术会议中心二楼报告厅
报 告 人：Rodney S. Ruoff
工作单位：Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS) (Republic of Korea); Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) (Republic of Korea)
举办单位：化学与化工学院，高值催化转化与反应工程安徽省重点实验室，安徽省柔性智能材料创制与应用工程研究中心
报告简介：
(i) On Earth circa 2025 significantly more natural graphite (G) than diamond (D) is mined/processed, and significantly more synthetic G than D is made. In metric tons: ~1,500,000 to ~24 (G to D, natural) and ~3,500,000 to ~3,100 (G to D, synthetic).D&G are almost isoenergetic at 273K and 1 atm and the same is true for hexagonal boron nitride (hBN) and cubic boron nitride (cBN).
A pure carbon sample containing only D&G at chemical equilibrium would have 22 mol% D at STP and 34.5 mol% D at 2000K (per HSC Chemistry). ΔHf of D at STP is about the same as ΔHvap of liquid neon at its boiling point of 27K, and about 1/10 the enthalpy of an H-bond in liquid water. (We recall that graphite is the standard state at STP.)
My perspective: Kinetic control and not thermodynamic control dictates why it has been simpler to synthesize G than D at 1 atm pressure. And: (I suggest) that it is also kinetic control and not thermodynamic control that favors synthesis of D vs G in high temperature-high pressure (HTHP) synthesis in metal flux (pressure in the range 5 – 10 GPa; typically but not always, a seed crystal is used). Almost invariably the explanation for each case (e.g., in textbooks, the published literature, etc.) has been based on thermodynamics and I suggest this is “simply wrong.”
I discuss possibilities to synthesize D (please see [1]) in new ways. The parameter space for the elemental compositions of metal fluxes that might dissolve the needed amount of C (or for cBN the needed amount(s) of B and/or N) at ~1 atm pressure is very large per combinatorics and the relevant elements in the Periodic Table. Fortunately (for opportunities for basic science as well as technology) there is a great deal that is “not studied at all” about dissolution of carbon, phase equilibria, and other interesting issues, in many possible choices of metal fluxes.
I will, furthermore, discuss new ideas about establishing/controlling the spatiotemporal distribution of solute elements in metal flux, from “time = 0” onwards (as the metal flux/solute(s) system evolves, so to speak). With retrosynthesis (terms such as inverse design and/or inverse optimization are also apt) and kinetic control in mind, I foresee a new—and very promising— horizon for synthesis of diamond and cubic boron nitride.
(ii) The macroscale tensile loading mechanics of monolayer single crystal graphene (SCG) is presented. We have measured the Young’s modulus, strain at failure, and tensile strength, as a function of crystallographic orientation. SCG is grown on either single crystal Cu(111) or on Ni(111) foils, and ‘dog bone’ samples with gauge length of 10 mm and width 2 mm have been found to have remarkably high tensile strength values, which we suggest bodes well for applications, particularly for ‘lightweighting’ in space and aerospace, among others. An earlier version of this study (in progress) has been archived, please see [2]. Supported by the Institute for Basic Science (IBS-R019D1)
报告人简介：
罗德尼·S·鲁夫（Rodney S. Ruoff），联合国教科文组织杰出教授（化学与材料科学系，以及能源科学与化学工程学院），同时也是位于韩国釜山国立科学技术院（UNIST）校园内的基础科学研究所（IBS）——“多维碳材料中心”（CMCM）的主任。在2014年加入UNIST之前，他自2007年9月起担任德克萨斯大学奥斯汀分校的考克雷尔家庭学者讲座教授。他于1988年获得伊利诺伊大学厄巴纳分校的化学物理学博士学位，并于1988年至1989年作为富布莱特学者在德国哥廷根的马克斯·普朗克流体力学研究所工作。他于2000年1月至2007年8月在西北大学工作，期间担任纳米工程领域的约翰·埃文斯教授，并兼任该校“生物启发材料研究所”的主任；此前，他曾在IBM TJ Watson研究中心担任博士后研究员，并在位于SRI国际公司的分子物理实验室工作了六年。
