【报告时间】2016年6月27日
【报告地点】玉泉校区曹光彪科技大楼326会议室
【邀请人】朱铁军教授
【联系电话】0571-87952181
报告一（09:30-10:30）
Neutron Scattering Study on the Rock-salt Type Thermoelectric Materials
嘉宾介绍：
马杰，上海交通大学物理与天文系特别研究员，博士生导师。2003年本科毕业于中国科学技术大学材料科学与工程系；2010年于美国衣阿华州立大学物理与天文系获得博士学位；2010年至2015年在美国橡树岭国家实验室中子散射中心和田纳西大学物理与天文系担任博士后研究员。
主要运用中子散射及同步辐射X光技术对强关联体系功能材料的晶体结构、声子谱和磁子谱进行研究。在Science, Physical Review Letters, Nature Materials, Nature Nanotechnology, Journal of the American Chemical Society 等杂志上发表论文36篇。
报告摘要：
As an advanced energy material, the thermoelectric compound has attracted a lot attention in the past years. Understanding the phonon mechanism is important to characterize the phonon transport and design an efficient thermoelectric system. The neutron scattering technique is a very useful tool to map not only phonon dispersions, but also the lifetimes across the entire Brillouin zone. In our study, these measurements provided the key insights to establish a complete picture of phonons. In addition, the first-principles simulations of atomic dynamics were performed. We would discuss the results of the thermoelectric materials, PbTe, SnTe, and AgSbTe2: although they have the similar rock-salt lattice structure, the original driving forces are different. Those studies should be used to reach a new level of understanding the thermal conductivity.
报告二（10:30-11:30）
Large phonon anharmonicity in thermoelectrics and complex oxides from first-principles
嘉宾介绍：
洪家旺，北京理工大学教授，博士生导师。2004年本科毕业于湖南大学，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。他的主要研究方向为功能材料和能源材料的第一性原理研究，以及第一性原理方法的发展。已在Nature， Nature Physics, PRL等期刊发表学术论文20余篇，担任PRL, PRX, Nature Communications, Advanced Materials等期刊审稿人。
报告摘要：
Harmonic and quasi-harmonic models of lattice dynamics are widely successful in explaining thermodynamic properties of materials. However, in some cases, strong anharmonicity can critically affect physical properties, and a (quasi) harmonic model is not sufficient to capture these important features. In this talk, I will show that the strong anharmonicity play a critical role in two important systems: promising thermoelectric material SnSe and metal-insulator transition material VO2. By combining first-principles calculations and inelastic neutron scattering measurements, we have investigated the lattice dynamics (anharmonic phonons), and their important role in the ultralow thermal conductivity in thermoelectric SnSe and the thermodynamics of metal-insulator phase transition in VO2. The origin of the strong anharmonicity in these systems will be discussed.
报告三（14:00-15:00）
The Universal Conductive Network in Compounds with Chalcogenide Sublattices
嘉宾介绍：
杨炯，上海大学材料基因组工程研究院，教授。杨炯教授于2009年在中国科学院上海硅酸盐研究所获材料物理与化学博士学位。2009~ 2012年于上海硅酸盐研究所任助理研究员。2012-2015赴美国华盛顿大学材料科学与工程系进行博士后交流。2015年获得上海市“东方学者”资助回上海大学工作。杨炯教授长期从事热电材料理论理解、新材料设计以及电热输运方法的发展等方面的研究，在Energy. Environ. Sci., Adv. Funct. Mater., J. Am. Chem. Soc., Chem. Mater., Appl. Phys. Lett., Phys. Rev. B等SCI刊物上发表论文50余篇。总引用数1300余次，H因子17，并发表国际热电专著一章。
报告摘要：
The concept of ‘Phonon glass-electron crystal’ (PGEC), which allows us to tune the electrical and thermal transport separately, offers new directions to seek novel high performance thermoelectric (TE) materials. Recently, we recognized that the PGEC paradigm can be annotated in the compounds with conductive networks. The compounds with conductive networks have only part of the structures that contribute to the electrical transport, while the tuning of the carrier concentrations and lattice thermal conductivities can be achieved in the rest part. In this work, we systematically study the general conductive network in chalcogen-based compounds by first principles. Our results demonstrate that compounds with similar chalcogen sublattice almost follow the similar Seebeck coefficients. This implies that the electrical transport properties of these compounds are mainly dependent on the sublattice of chalcogen, which is the key feature of “electron crystal”. The variations on electrical transport properties of different chemical characteristic from S, Se, to Te are investigated.
