Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - NOSTA (Nanostructured Oxide and Silicide Materials for Thermoelectric Device Applications)

Teaser

The impacts of energy and financial crisis along with climate change have generated the necessity of cheap sustainable green energy. Upgrading the otherwise lost waste heat, estimated to be over 60% of the globally released energy, to electrical energy is a promising strategy...

Summary

The impacts of energy and financial crisis along with climate change have generated the necessity of cheap sustainable green energy. Upgrading the otherwise lost waste heat, estimated to be over 60% of the globally released energy, to electrical energy is a promising strategy for sustainable energy. The use of thermoelectric,TE, devices which convert directly the waste heat to electrical energy, is a desirable technology for future power generation as there are no moving parts, high reliability, high adaptability uses, minimal environmental pollution and noiseless operation. Despite the big effort of the last years their conversion efficiency is quite low and the thermoelectric materials that are currently used are based on Tellurium, which is very rare on the earth surface.
The objectives of NOSTA Project are summarized as follows
1. Optimization of the synthesis and processing of highly-efficient, low-cost, non-toxic and environmentally friendly nanostructured bulk thermoelectric materials (TE) with the aim of further enhancing their efficiency.
2. Understanding of the underlying Physical mechanisms through computational modelling and analysis/modelling of the experimental data.
3. Construction and characterization of a prototype Thermoelectric device using the fabricated materials.
4. Improvement of existing experimental characterization technique to investigate thermoelectric properties in the nanoscale.

Work performed

A detailed study was performed on the optimization of the synthesis and processing of low-cost nanostructured bulk thermoelectric materials. More specifically, several experiments were performed for the optimization of the synthesis conditions of La and Nb doped SrTiO3 by Solid State Reaction (SSR) and Sol-Gel method. Different experimental techniques were employed for the structural and chemical characterisation of the synthesised materials. Based on the overall results, a methodology was developed for the synthesis of doped SrTiO3 with micro- and nano- grain sizes. Furthermore, following this methodology certain amounts of La and Nb doped SrTiO3 powders were synthesised with both techniques to investigate the effect of the doping and synthesis procedure on the TE properties of the materials.
An overview of NOSTA project results is given as follows:
• Doped SrTiO3 can be reproducibly synthesised by the optimized SSR and Sol-Gel procedures developed.
• Doped SrTiO3 of different grain sizes can be synthesized depending on the method. Therefore, by mixing the result powders, potentially high efficient TE materials can be synthesized for TE device fabrication.
• Outreach activities were planned according to Annex 1 of Grant Agreement to communicate the results with the society in a simple way, including proposal for participation in the Researchers night, active posts in the social media regarding the project. Although, due to the early termination of the project they didn\'t performed.

Potential exploitable results of the project, could lead to the fabrication of efficient n-type legs for TE devices. More specifically, the synthesis of powders combining SSR and Sol-Gel synthesis techniques can lead to an efficient TE material with grains varying from nano- to micron- sizes. Variable grain sizes ensures decrease of the thermal conductivity of the material which in turns will increase the efficiency. The methodology developed for the synthesis of doped SrTiO3 can be a useful tool and a basis for future research projects for the increase of efficiency of Oxide TE materials.

Final results

The progress beyond the ‘state-of-the-art’ is demonstrated by the following:
• The methodology developed for the synthesis of oxide thermoelectric materials with various grains sizes.
• Synthesis of Low cost non-toxic oxide thermoelectric materials.

The expected potential impact of the research results:
• The synthesis of low cost non-toxic oxide thermoelectric materials will attract the interest of the scientific community for further studies.
• The methodology developed for the synthesis of doped SrTiO3 can be a useful tool and a basis for future research projects as well as for the industrial sector.