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UID:1649923200@ist.ac.at
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DESCRIPTION:Speaker: Jeffrey Snyder\nhosted by Maria Ibáñez\nAbstract: En
 gineering Grain Boundaries in Thermoelectric MaterialsGrain boundaries hav
 e a remarkable effect on the thermal and electrical transport properties o
 f polycrystalline materials but are often ignored by prevailing physical t
 heories. Grain boundaries and interfaces can adversely alter the propertie
 s of Solar Cells\, Batteries and Thermoelectrics. To devise strategies for
  improving the thermoelectric performance of materials\, it is essential t
 o understand the coupled charge and thermal transport mechanisms including
  interfacial electrical and thermal resistance (Kapitza resistance) and ev
 en an interfacial Seebeck effect. The inhomogeneous nature of materials\, 
 such as that caused by grain boundaries\, must be taken into account to re
 think engineering strategies based on Mathiessen’s rule which interprets
  scattering homogeneously.Electrical grain boundary resistance can be so h
 igh in some thermoelectric materials it is the dominant property that limi
 ts zT. While small grains are usually considered beneficial for thermoelec
 tric performance due to reduced thermal conductivity\, MgSb based thermoel
 ectric materials\, so far at least\, contradict that trend. The effect of 
 grain boundary electrical resistance has been more striking and lead to th
 e development of new electronic transport models in granular materials to 
 explain and predict the electrical conductivity. Indeed\, atomic segregati
 on has been recently observed at the nanometer scale in grain boundaries i
 n many materials suggesting interfacial or complexion phases should be spe
 cifically considered when understanding nearly all thermoelectric material
 s. These phases can even be engineered not only with thermodynamic quantit
 ies such as temperature and composition but also by adding 2D interfacial 
 materials such as graphene. References J. J. Kuo\, G. J. Snyder “Grain
  boundary dominated charge transport in Mg3Sb2-based compounds” Energy &
  Env. Sci. 11\, 429 (2018)R. Hanus\, G. J. Snyder “Phonon diffraction an
 d dimensionality crossover in phonon interface scattering” Communication
 s Physics 1\, 78 (2018)Y. Lin et al.\, “Expression of interfacial Seebec
 k coefficient through grain boundary engineering with multi-layer graphene
  nanoplatelets”. Energy & Environmental Science 13\, 4114 (2020).
LOCATION:Big Seminar Room B - Sunstone Building\, ISTA
ORGANIZER:
SUMMARY:Jeffrey Snyder: Engineering Grain Boundaries in Thermoelectric Mate
 rials
URL:https://talks-calendar.ista.ac.at/events/3703
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