PhD. Candidate Mr. Amram Azulay
Thermoelectric (TE) materials serve for conversion of waste heat into electrical energy and are of prime technological importance. Among other physical properties, high electrical conductivity, low thermal conductivity, and large Seebeck coefficient are required to provide acceptable conversion efficiency. In this sense, oxides are attractive for their natural abundance, nontoxicity, and chemical stability at elevated temperatures. We study CaO(CaMnO3)m layered compounds, comprising m perovskite sub-cells separated by CaO rock-salt planes. These phases exhibit intriguing thermal and electronic transport properties which can be tuned by crystal periodicity and defect chemistry. We apply density functional theory for point defect engineering, then synthesize materials and measure their electronic and thermal transport properties. Employing the small polaron hopping model, we reveal that Y doping of Ca2MnO4 (m=1) compounds enhances the charge carrier mobility by up to 2.5 times compared to the case of La doping, shedding light on the correlation between electronic and elastic behaviors of these compounds. We also investigate CaMnO3 (m=∞) and Ca2MnO4 (m=1) composite materials, and correlate between their TE properties, microstructure evolution, and composition. Applying the general effective medium approach, we identify the significance of bulk vs. interfacial effects in the design of TE composites. Our research highlights the intricate relationship between the structure and the charge and heat transport of AB(ABO3)m-based materials, with implications for TE performance.
Supervisor: Prof. Yaron Amouyal
The lecture will take place in room 302, Meidan, for green pass holders, or via ZOOM.
Meeting ID: 995 9239 6977