间:2019年3月25日上午

       点:春晖楼四楼会议室

位:科技处  材料科学与工程学院

报告题目1MICATRONICS: A NEW PLATFORM FOR SOFT TRANSPARENT TECHNOLOGY

专家简介:朱英豪,台湾国立交通大学教授,于台湾清华大学获博士学位后前往美国加州大学柏克莱分校进行博士后研究。至今发表论文总计超过280篇,其中接近半数刊登于具有高影响因子的期刊(IF>10,Science & Nature 系列超过20篇),也有多篇邀请综述论文,文章引用次数也快速提升中(根据web of science统计,h-index为58,总引用数超过15000,由Google Scholar资料库的统计,h-index为67,总引用数超过20000)。研究的领域相当广泛,无论是在物理的PRL,或是化学的JACS,与材料的Adv. Mater.,都可以见到该团队的成果。曾三次获选全球材料领域高被引学者(2014、2016、2018年),2019年起担任ACS Applied Electronic Materials期刊副主编。

报告内容摘要:

A new world is being formed based on the technologies composed of artificial intelligence, Internet of Things (IoT), and robots. Especially, in the research fields of IoT and robotics systems, a device with mechanical flexibility can deliver more degrees of freedom as far as the design aspects are concerned. Therefore, the development of soft and flexible electronics becomes an important research direction for wearable and IoT devices. Due to the mechanical flexibility, polymer materials and thin metal foils are commonly used in the fabrication of flexible electronic systems. However, the reliability issue under practical operations hinders the applications of these flexible electronics, especially for those on polymer based substrates. This is attributed to a mismatch of thermal expansion coefficient between substrate and functional materials or low thermal and chemical endurance of polymers and organic materials. A lot of researchers are working hard and together to expand the applicability of current flexible devices. However, new pathway to flexible electronics can also be developed in parallel to provide more subtle solutions, thus in need of new platform to integrate functional materials with good thermal and chemical stabilities together with mechanical flexibility. In this research field, oxides can play an important role due to their intriguing functionalities and superior thermal and chemical stabilities. To deliver high-quality thin films or structures based on oxides, heteroepitaxy is essential. However, the lack of a suitable approach remains an obstacle for flexible oxide heteroepitaxy. van der Waals epitaxy (vdWE) involving two-dimensional layered materials can play a crucial role in the expansion of thin film epitaxy by overcoming the bottleneck of material combinations due to lattice/thermal matching conditions inherent to conventional epitaxy. In this study, we use a 2D material as the substrate. In this talk, we confine ourselves to the validity of vdWE of functional oxides on muscovite mica throughout this treatise. With such demonstrations, it is anticipated that MICAtronics, vdWE on mica, can reveal unusual properties and emergent phenomena in the realm of high-performance flexible device applications.

报告题目2先进材料中的多场耦合行为研究

专家简介:洪家旺,北京理工大学宇航学院教授,博士生导师,国家“青年千人”计划入选者。于2010年在清华大学获得博士学位,期间2007-2008年在英国剑桥大学进行交流访问,2010至2016年分别在美国Rutgers大学和橡树岭国家实验室从事博士后研究工作。主要从事先进功能材料和能源材料的多场耦合行为理论与实验研究,以及原子尺度模拟计算方法的发展。在Science, Nature,Nature Physics, Phys. Rev. Lett., Appl. Phys. Lett.等期刊发表学术论文40余篇,担任Science, Nature Materials, Phys. Rev. Lett., Phys. Rev. X等期刊审稿人。

报告内容摘要:

先进功能材料与能源材料体现出多场耦合效应,比如应变场、应变梯度场、电场、磁场以及热场等多物理量之间的耦合。这种耦合效应由于对材料组分,结构以及外部激励非常敏感而成为许多新型器件的核心材料元件。采用第一性原理方法,我们研究了压铁电材料与一般电介质材料中普遍存在的一种应变梯度与电极化强度之间的新的力电耦合效应——挠曲电效应。通过发展第一性原理挠曲电方法,揭示了挠曲电效应存在的内在微观机理并预测了具有强挠曲电效应的材料体系。同时,结合第一性原理计算和非弹性中子散射/同步辐射散射测量,我们研究了材料内部原子振动在材料磁电耦合效应、热电效应中的重要作用。

报告题目3六角锰氧化物中各向异性诱导的铁电拓扑畴的新奇性质

专家简介:王学云,博士,北京理工大学副研究员,博士生导师。2009年本科毕业于中国人民大学物理系,2015年博士毕业美国Rutgers, the State University of New Jersey物理系。2015年至2017年于北京科技大学数理学院任副教授,2017年加入北京理工大学宇航学院力学系。发表SCI论文41篇, 其中以一作/通讯作者在Nature Physics, Physical Review Letters, Physical Review B, ACS Applied Materials & Interfaces等国际顶级学术期刊发表文章9篇。担任Physical Review Letters, Physical Review X, Applied Physics Letters, Journal of Applied Physics, Journal of Physical Chemistry C等期刊的审稿人。主持国家自然科学基金青年项目1项。主要研究兴趣在先进功能材料的单晶生长,以及基于扫描探针技术的功能性畴与畴壁的研究。

报告内容摘要:

有通过高质量六角锰氧化物RMnO3单晶的生长与压电力扫描探针显微镜技术,我们研究了单晶中由于晶格畸变引起的铁电涡旋畴。该铁电畴由于对称性的破缺引起的锰氧多面体的倾斜以及锰离子层中的三角化(Trimerization) 从而导致了铁电拓扑涡旋畴的形成。六角锰氧化物本身层状结构性质所导致的各向异性,在畴结构的演化以及物理性质的调控中起到了至关重要的作用。在本报告中,我们将首先简单介绍六角锰氧化物中铁电畴的形成的机理,以及应力、电场等外物理场对畴结构与铁电拓扑缺陷调控的研究,进而着重探讨在该体系中最新发现的具有各向异性的电导率调控特性,该种沿不同晶向调控性质明显的差异是由间隙氧在不同晶向下迁移路径的能量差所导致的。