Time: 15:45 pm, 20th September, 2020

Speaker: Dr. Jiawei Zhang, Aarhus University

Abstract:

Thermoelectric materials enable the interconversion between heat and electricity with no moving parts, showing potential applications in waste heat harvesting and solid-state refrigeration. Systematically optimizing the thermoelectric performance of a material remains a great challenge due to the transport parameters being correlated with each other. Focusing on Mg3Sb2 and related CaAl2Si2-type materials, in this talk I will first present design strategies for electronic transport optimization including a simple atomic orbital scheme for p-type and multi-valley conduction bands for n-type, followed by a systematic exploration of potential n-type dopants with defect calculations. Afterwards, I will focus on the origin of intrinsically low lattice thermal conductivity of Mg3Sb2 from insights of phonon-phonon scattering. Finally, I will discuss the quantitative chemical bonding analysis and reveal the breakdown of the Zintl concept in Mg3Sb2 with a nearly isotropic three-dimensional chemical bonding network. This unique chemical bonding feature can be used to understand the nearly isotropic structural and thermal properties.

Brief CV of Dr. Jiawei Zhang:

Dr. Jiawei Zhang received his PhD in 2018 from Aarhus University, after obtaining his Master’s degree in 2014 from Shanghai Institute of Ceramics, Chinese Academy of Sciences. Currently, he is a postdoctoral fellow at Aarhus University. His research focuses on understanding electrical and thermal transport properties for the design of new thermoelectric materials by combining comprehensive solid-state synthesis, structural and physical property characterizations, scattering techniques, chemical bonding analysis, and density functional theory calculations.