Influence of stress on transport properties of thermoelectric materials
||Influence of stress on transport properties of thermoelectric materials|
||NAISS Medium Compute|
||Denis Music <firstname.lastname@example.org>|
||2023-10-01 – 2024-10-01|
Green energy can be important for many aspects of our modern world. It can easily replace the negative effects of fossil fuels with more environmentally friendly alternatives and give rise to local energy production minimizing the existing global power relations. Thermoelectric devices directly convert heat into electricity without greenhouse gas emission enabling applications for off-grid energy generation and waste heat extraction (see a selection of the publications from the applicant: Appl. Phys. Lett. 120, 051901 (2022) and Appl. Phys. Lett. 109, 223903 (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 as well as oxidation. 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. In the first round of this computational project, material screening was performed, including Mg3Bi2, tellurides, half-Heusler alloys, and skutterudites. It seems that half-Heusler alloys, such as TiNiSn, and Mg3Bi2 are very promising systems for the mechano-transport response. Furthermore, these compounds in their amorphous states are increasingly interesting (results from the second round), which requires additional computational resources. More details will be carried out in the project, especially merging the theoretical efforts with experiments (important feedback loops). We have recently installed two experimental platforms to enable such comparisons. The Seebeck coefficient will we obtained from the Boltzmann transport equation at equilibrium and a stress of experimental interest. Variation in composition and structure as well as temperature dependence will also be tackled. It is expected that the results obtained herein will be used to increase the efficiency of thermoelectric devices by manipulating intrinsic and extrinsic stresses.