Influence of stress on transport properties of thermoelectric materials
||Influence of stress on transport properties of thermoelectric materials|
||SNIC Medium Compute|
||Denis Music <email@example.com>|
||2020-09-29 – 2021-10-01|
Thermoelectric devices directly convert heat into electricity without greenhouse gas emission enabling applications for off-grid energy generation waste heat extraction (see a selection of the publications from the applicant: Appl. Phys. Lett. 109, 223903 (2016) and J. Appl. Phys. 120, 045104 (2016)). Since their efficiency is defined by transport properties, mechanical strain can drastically affect the performance, which is a less investigated feature or even completely ignored in modern design efforts. Furthermore, these devices are subjected to abrupt thermal gradients giving rise to thermal shock and fatigue. Hence, this computational project is dedicated towards systematic studies of intermetallic and metallic-like thermoelectric systems in terms of their transport properties (the Seebeck coefficient, electrical conductivity, thermal conductivity) as a function of strain using density functional theory and non-equilibrium Green’s functions. First, material screening will be performed, ranging from common intermetallic systems (tellurides, half-Heusler alloys, skutterudites, and type-I-clathrates) to metallic-like systems (conductive ceramics such as Nb and Sn based oxides as well as NaCl structured nitrides and carbides) to identify the most interesting candidates. The Seebeck coefficient will we obtained from the Boltzmann transport equation at equilibrium and a large stress. Materials with large stress dependent properties will be selected and further studied in detail (variation in composition and structure as well as temperature dependence). The outcome of this computational study will be validated experimentally to provide a feedback for future calculations and refine theoretical models. It is expected that the results obtained herein will be used to increase the efficiency of thermoelectric devices by manipulating intrinsic stresses.