Phonon dispersion and scattering in thermoelectrics

主讲人：裴艳中 同济大学教授

时间：2019年6月17日13：00

地点：10号楼327

举办单位：数理学院

主讲人介绍：Dr. Yanzhong Pei became a professor in 2012 at the School of Materials Science  and Engineering, Tongji University, Shanghai, China. His research mainly focuses  on advanced thermoelectric semiconductors, from synthesis to understanding the  materials physics and chemistry. He holds a B.E. from Central South University  in China, a Ph.D from the Shanghai Institute of Ceramics, CAS, and postdoctoral  research experience for about 5 years from Michigan State University and the  California Institute of Technology. Dr. Pei has published ~100 papers on  thermoelectrics, which received a total citation of ~7700 with a H-index of 41.  Dr. Pei was also the recipient of 2017 Goldsmid and 2013 Young Investigator  Awards from the International Thermoelectric Society.

内容介绍：As an alternative strategy for advancing thermoelectrics by engineering the band  structure, a minimization of lattice thermal conductivity (KL) has been proven  to be successful as well. 0D vacancy (either intrinsic or extrinsic) and  interstitial defects are effective on scattering phonons. Moreover, the possible  clustering of vacancy or interstitial, which forms 1D dislocations, may lead to  additional phonon scattering, which opens new possibilities. It is recently  revealed that phonon scattering due to these defects essentially stems from a  broadening in phonon dispersion through changing the mass of lattice vibrators  (atoms) and the interaction force between and in-grain dislocations are  particularly effective for such dispersion broadening. In addition, the most  popular approximation on the phonon dispersion, the linear dispersion of Debye,  statistically leads to a significant deviation between predicted and measured KL  for solids. Thus, a development of a more accurate and physically meaningful  phonon dispersion for phonon transport would provide a more powerful guidance  for minimizing KL. Further than that, focusing on the phonon dispersion and  speed of phonon propagation, low sound velocity in complex crystal structures  with diffusive species is also desired for a low lattice thermal conductivity.  This talk involves our recent efforts on understanding/manipulating the phonon  dispersion and phonon scattering for a successful minimization of KL of  thermoelectrics.