Title: Ceramic processing science across scales

　　Abstract: Processing science of ceramics is critical to many applications. In this talk, I shall start with the design of promoting interfacial reactive sintering in protonic ceramic electrochemical cells operated at intermediate temperature [Nature 604, 479-485, 2022] and suppressing stress corrosion cracking in oxide cathodes of lithium-ion battery used at room temperature [Nat. Energy 6, 362, 2021; Nat. Energy 6, 495, 2021]. These efforts improve the device efficiency and stability and extend the cycle life. I will next talk about a generalized growth theory unifying the textbook knowledge of Ostwald ripening and normal grain growth [Adv. Funct. Mater. 31, 2007750, 2021]. A new concept of ultra-uniformity is proposed, defined as grain size distribution narrower than predicted by the classical theory of Hillert. For curvature driven grain growth, a steady-state size distribution is analytically solvable for growth exponent n > 1 and the distribution narrows with increasing n. Experimental validation of this prediction is found in porous alumina ceramics at various intermedium and final stage sintering, which sheds light on the hidden role of porosity to self-homogenize the microstructure. When coupled with two-step sintering that freezes grain coarsening in the final stage sintering, it creates dense alumina nanoceramics with 34 nm average grain size and an extremely uniform microstructure. The new fundamental insights and rationally optimized sintering practices would enable ultra-uniform nanocrystalline ceramics with unprecedented properties and reliability.

　　报告时间：2024年3月26日上午10:00~11:00

　　报告地点：辽宁材料实验室A楼303报告厅

　　报告人简介: 董岩皓，清华大学材料学院助理教授，博士生导师。2012年毕业于清华大学材料科学与工程系，获学士学位。2012至2017年，在美国宾夕法尼亚大学学习，获材料学硕士、应用力学硕士和材料学博士学位，从事陶瓷材料烧结、扩散、微结构演化等基础理论的研究。2017至2022年，在美国麻省理工学院从事博士后研究，从事交叉学科材料设计、制备、微结构、衰减机理的研究。曾获得美国陶瓷学会颁发的Early Discovery Award、Edward C. Henry Award、摩根奖章和优秀博士生论文奖、美国陶瓷学会终身会员，Acta Materialia期刊Acta Student Award，宾夕法尼亚大学Sidney J. Stein Prize等荣誉。近年来以第一作者和通讯作者（含共同）发表高水平学术论文50余篇，包括Nature、Nat. Energy（4篇）、Chem. Rev.、Acta Mater.（10篇）、J. Am. Ceram. Soc.（7篇）等。目前主要的研究方向是结构陶瓷和能源陶瓷材料。