应我校材料科学与工程学院欧阳家虎教授邀请，美国伊利诺伊大学香槟分校材料科学与工程系（Department of Materials Science and Engineering, UIUC）Shen J. Dillon教授将于5月28日至6月17日对我校进行访问交流、科研合作，并进行一系列学术报告，欢迎广大师生参加。具体学术讲座信息如下：
题目：Surface Interactions Affecting Li-ion Degradation Characterized by Model Experiments
Lithium ion battery cycle life varies significantly with cathode chemistry, structure, and properties. However, it is well known that deconstructing cycled and faded full cells and reassembling them as half cells can retrieve much of the lost capacity. Therefore, cathode chemistry must play a role in exacerbating other side reactions that induce capacity fade without significantly degrading themselves. A well-known example in the literature is the effect of Mn(II) dissolution from the cathode in degrading the anode. However, analogous fade mechanisms resulting from interactions between cathode and anode side reactions are not as well understood in other systems. Since such ‘cross-talk’ interactions can have multiple complex steps and inherently have surface reaction contributions, they can be difficult to characterize and identify. The complex nature of degradation reactions motivates the development of in situ and operando characterization techniques. Of particular value for understanding associated mechanisms are surface sensitive in situ characterization techniques such as x-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), etc. Such methods require specialized electrochemical cells that function in vacuum. Ideally, we seek to relate such information to associated changes occurring in the bulk of the electrode particles, in the physical properties of the underlying material, and in the commercially relevant battery environments.
题目：Interfacial Mechanical Properties from Small Scale Testing
Interfacial mechanics often dominate the bulk properties of polycrystals and composites. Understanding their properties can be critical to understanding the performance of the bulk material. Yet isolating the properties of the microstructural constituents can be challenging. This talk discusses the use of in-situ TEM based measurements to isolate interfacial and grain boundary properties in alumina polycrystals, ceramic eutectic composites, and alloy nanostructures oxides. In particular the work examines the effects of local interfacial structure and chemistry in affecting their mechanical properties, with an emphasis on understanding how these effects ultimately impact bulk properties. This talk will also discuss the effects of scale on deformation and the mechanisms for inverse Hall-Petch behavior in oxides.
题目：Self-Organization during Severe Plastic Deformation at High and Low Temperatures
Severe plastic deformation (SPD) provides a useful route to fabricating nanostructured alloys and is relevant in materials processes such as dry sliding wear. During SPD to high strains alloys often establish a steady-state microstructure in regard to the grain size, solute solubility levels, precipitate sizes, etc. at both high and low temperatures. Many fundamental questions remain regarding how different components mix under deformation, their dependence on strain, strain rate, temperature, and the thermodynamic properties of the alloy. This work explores how mixing occurs in mildly immiscible and highly immiscible systems at low and high temperatures in order to understand why and how the observed steady-state structures evolve.
题目：Characterizing Point Defect Fluxes to Sinks during Irradiation
Nanostructured alloys are envisioned as potential next-generation nuclear materials. Nanostructured materials are favored due to their high densities of point defect sinks. However, little is known about the efficiency of different interfaces as sinks for vacancies. This has previously been quite challenging to measure experimentally. Under stress such nanostructured materials may also be subject to irradiation induced creep (IIC) as a result of those point defect fluxes. However, little is known about IIC in nanostructured materials. While traditional mechanisms for IIC may be suppress in nanostructured alloys, new mechanisms for IIC could be activated and present unanticipated engineering challenges. Simulating neutron damage with ions in accelerated tests is challenging and ideally requires sub-micron scale samples. This talk reports on recent efforts to perform IIC using a combination of in-situ mechanical loading, ion irradiation, and laser heating in the transmission electron (I3TEM) at Sandia National Laboratories.
Shen J. Dillon教授简介：
Prof. Dillon现为美国伊利诺伊大学香槟分校工程学院材料科学与工程系副教授，分别于2002年和2007年在美国Lehigh University材料科学与工程系获得学士和博士学位。2007年赴卡耐基梅隆大学（Carnegie Mellon University）和麻省理工学院（Massachusetts Institute of Technology）从事材料微结构演变和储能材料的研究。2008年进入伊利诺伊大学香槟分校材料科学与工程系任教。Prof. Dillon致力于界面科学、陶瓷材料微结构与性能的关系、锂离子电池等方面研究，尤其是在原位电子显微学、晶界及界面科学、材料结构与性能关系等方面进行了开拓性的研究。他在Adv. Mater.，Acta Mater.，J. Amer. Ceram. Soc.，Appl. Phys. Lett.，Scripta Mater.，Langmuir等顶级期刊上发表研究和综述文章近百篇。他曾荣获美国能源部的Early Career Award（2011）、美国国家自然科学基金会的CAREER award（2013），Robert L. Coble 青年学者奖（2015），Lee Hsun青年科学家奖（2016）等多项奖励和荣誉。