Final Report Summary - COMPTHERM (Computational Thermoelectrics)
Background:
One route to improve the sustainability of our electricity base is through the scavenging of waste heat with thermoelectric devices. Since waste heat is found everywhere, it can be used to generate electricity by using a thermoelectric generators. A thermoelectric generator is typically a solid-state device with no moving parts making them silent, reliable and scalable.
In order to enhance the efficiency of a thermoelectric materials, simultaneous tuning of its electronic properties, such as the Seebeck coefficient S, the electric conductivity, the electronic thermal conductivity and the lattice thermal conductivity is necessary. The efficiency for a given thermoelectric material is given by its figure-of-merit. In bulk materials, the only parameter tunable somewhat independently from the other parameters is the lattice thermal conductivity which ultimately should be very small. To maximise the efficiency is a very challenging materials design problem that requires good knowledge of the material properties on both a microscopical and macroscopic level. The objective of the project was to perform electronic structure calculations trying to gain some understanding of the phonon properties which is a crucial step for improving the efficiency. Since there is very little known about these properties in this materials from electronic structure calculations, it has been a very challenging task which unfortunately has resulted that the project has advanced slowly. However, some knowledge has certainly been gained and the present project has been acting as an excellent precursor to a larger European Union (EU)-funded project (FP7-NMP-2010, NEXTEC) on thermoelectrics in which the researcher is a participant and applying the knowledge from the COMPTHERM project.
Recently, we have started combining the spin dynamics with thermoelectrics, a field that sometimes is called spin-caloritronics. It is a rapid growing field with many novel interesting applications, many targeted for reducing energy consumption very relevant for the society.
Unforeseen event during the project:
A complicated factor happened around half-way into the project when the researcher got a job offer at another university (KTH, Stockholm) than the host (Uppsala University). The researcher changed affiliation starting from September 2010. Although, the researcher still holds many connections and collabourating with the host university, it hampered and slowed down the project progress.
Main scientific results in the project:
- Development of a general scheme for constructing interatomic force field that is parametrised from electronic structure calculations: This allows to perform elabourate studies of heat-transport in thermoelectric materials in various geometries such as multilayers, nanograins and nanostructured materials.
- Calculations of phonons and related properties in the thermoelectric class of materials of skutterudites and clathrates from electronic structure calculations: The results from these points are carried on to the NEXTEC project on thermoelectrics.
- Collection of previous results on diluted magnetic semiconductors that was published in the high-profile journal Review of Modern Physics with impact factor 52.
- Development of atomistic spin dynamics simulation method that was applied for calculations of magnon properties in low dimensional magnets.
- Novel material design predicted from electronic structure calculations using codoping to increase critical temperature in diluted magnetic semiconductors.
Impact and conclusion:
The review article about diluted magnetic semiconductors in Review of Modern Physics has attracted more than 75 citations since it was published two years ago and has stirred lots of interest in the field.
There has been both strong and weak points associated with the project. To start with the weak points, the most important is probably that the planned calculations turned out to be more difficult than first anticipated. That combining with the fact that the researcher changed affiliation half-way slowed down the progress resulting that the quantitative amount of output has not been so large. However, the project has resulted in some good qualitative output, in particular a deeper understanding of the phonon properties in skutterudites, which is now applied in the NEXTEC project on thermoelectrics.
During the course of the project, the researcher has widened his field of research towards atomistic spin dynamics. It has been quite successful and attracted several research grants on a national level. There is ongoing work combining these calculations with thermoelectric properties (thermal gradient to generate currents etc) where the knowledge obtained from COMPTHERM will be extremely useful.
Contact details and project websites:
Prof. Olle Eriksson
Department of Physics and Astronomy
Uppsala University
Box 516
SE-751 20 Uppsala, Sweden
Email: olle.eriksson@physics.uu.se
Tel: +46-184-713625
Dr Lars Bergqvist
Department of Materials Science and Engineering
KTH Royal Institute of Technology
Brinellv. 23
SE-100 44 Stockholm, Sweden
Email: lbergqv@kth.se
Tel: +46-879-06268
- http://www.e-science.se/project/thermoelectric-materials(opens in new window)
- http://www.e-science.se/project/atomistic-spin-dynamics(opens in new window)
- http://www.physics.uu.se/en/page/UppASD(opens in new window)
One route to improve the sustainability of our electricity base is through the scavenging of waste heat with thermoelectric devices. Since waste heat is found everywhere, it can be used to generate electricity by using a thermoelectric generators. A thermoelectric generator is typically a solid-state device with no moving parts making them silent, reliable and scalable.
In order to enhance the efficiency of a thermoelectric materials, simultaneous tuning of its electronic properties, such as the Seebeck coefficient S, the electric conductivity, the electronic thermal conductivity and the lattice thermal conductivity is necessary. The efficiency for a given thermoelectric material is given by its figure-of-merit. In bulk materials, the only parameter tunable somewhat independently from the other parameters is the lattice thermal conductivity which ultimately should be very small. To maximise the efficiency is a very challenging materials design problem that requires good knowledge of the material properties on both a microscopical and macroscopic level. The objective of the project was to perform electronic structure calculations trying to gain some understanding of the phonon properties which is a crucial step for improving the efficiency. Since there is very little known about these properties in this materials from electronic structure calculations, it has been a very challenging task which unfortunately has resulted that the project has advanced slowly. However, some knowledge has certainly been gained and the present project has been acting as an excellent precursor to a larger European Union (EU)-funded project (FP7-NMP-2010, NEXTEC) on thermoelectrics in which the researcher is a participant and applying the knowledge from the COMPTHERM project.
Recently, we have started combining the spin dynamics with thermoelectrics, a field that sometimes is called spin-caloritronics. It is a rapid growing field with many novel interesting applications, many targeted for reducing energy consumption very relevant for the society.
Unforeseen event during the project:
A complicated factor happened around half-way into the project when the researcher got a job offer at another university (KTH, Stockholm) than the host (Uppsala University). The researcher changed affiliation starting from September 2010. Although, the researcher still holds many connections and collabourating with the host university, it hampered and slowed down the project progress.
Main scientific results in the project:
- Development of a general scheme for constructing interatomic force field that is parametrised from electronic structure calculations: This allows to perform elabourate studies of heat-transport in thermoelectric materials in various geometries such as multilayers, nanograins and nanostructured materials.
- Calculations of phonons and related properties in the thermoelectric class of materials of skutterudites and clathrates from electronic structure calculations: The results from these points are carried on to the NEXTEC project on thermoelectrics.
- Collection of previous results on diluted magnetic semiconductors that was published in the high-profile journal Review of Modern Physics with impact factor 52.
- Development of atomistic spin dynamics simulation method that was applied for calculations of magnon properties in low dimensional magnets.
- Novel material design predicted from electronic structure calculations using codoping to increase critical temperature in diluted magnetic semiconductors.
Impact and conclusion:
The review article about diluted magnetic semiconductors in Review of Modern Physics has attracted more than 75 citations since it was published two years ago and has stirred lots of interest in the field.
There has been both strong and weak points associated with the project. To start with the weak points, the most important is probably that the planned calculations turned out to be more difficult than first anticipated. That combining with the fact that the researcher changed affiliation half-way slowed down the progress resulting that the quantitative amount of output has not been so large. However, the project has resulted in some good qualitative output, in particular a deeper understanding of the phonon properties in skutterudites, which is now applied in the NEXTEC project on thermoelectrics.
During the course of the project, the researcher has widened his field of research towards atomistic spin dynamics. It has been quite successful and attracted several research grants on a national level. There is ongoing work combining these calculations with thermoelectric properties (thermal gradient to generate currents etc) where the knowledge obtained from COMPTHERM will be extremely useful.
Contact details and project websites:
Prof. Olle Eriksson
Department of Physics and Astronomy
Uppsala University
Box 516
SE-751 20 Uppsala, Sweden
Email: olle.eriksson@physics.uu.se
Tel: +46-184-713625
Dr Lars Bergqvist
Department of Materials Science and Engineering
KTH Royal Institute of Technology
Brinellv. 23
SE-100 44 Stockholm, Sweden
Email: lbergqv@kth.se
Tel: +46-879-06268
- http://www.e-science.se/project/thermoelectric-materials(opens in new window)
- http://www.e-science.se/project/atomistic-spin-dynamics(opens in new window)
- http://www.physics.uu.se/en/page/UppASD(opens in new window)