報告時間：2025年10月14日（星期二）10:00-11:30
報告地點：學術會議中心二樓報告廳
報 告 人：Rodney S. Ruoff
工作單位：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)
舉辦單位：化學與化工學院，高值催化轉化與反應工程安徽省重點實驗室，安徽省柔性智能材料創制與應用工程研究中心
報告簡介：
(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)
報告人簡介：
羅德尼·S·魯夫（Rodney S. Ruoff），聯合國教科文組織杰出教授（化學與材料科學系，以及能源科學與化學工程學院），同時也是位于韓國釜山國立科學技術院（UNIST）校園內的基礎科學研究所（IBS）——“多維碳材料中心”（CMCM）的主任。在2014年加入UNIST之前，他自2007年9月起擔任德克薩斯大學奧斯汀分校的考克雷爾家庭學者講座教授。他于1988年獲得伊利諾伊大學厄巴納分校的化學物理學博士學位，并于1988年至1989年作為富布萊特學者在德國哥廷根的馬克斯·普朗克流體力學研究所工作。他于2000年1月至2007年8月在西北大學工作，期間擔任納米工程領域的約翰·埃文斯教授，并兼任該?！吧飭l材料研究所”的主任；此前，他曾在IBM TJ Watson研究中心擔任博士后研究員，并在位于SRI國際公司的分子物理實驗室工作了六年。
