Open Chem., 2015; 13: 629–635 Research Article Open Access Mohsen Yakshi Tafti, Mohsin Saleemi, Muhammet S. Toprak*, Mats Johnsson, Alexandre Jacquot, Martin Jägle, Mamoun Muhammed Fabrication and characterization of nanostructured thermoelectric Fe x Co 1-x Sb 3 Abstract: A novel synthesis route for the fabrication of p-type nanostructured skutterudite, FexCo1-xSb3 in large quantity is reported. This scalable synthesis route provides nano-engineered material with less impact on the environment compared to conventional synthesis procedures. Several Fe substituted compositions have been synthesized to confirm the feasibility of the process. The process consists of a nano-sized precursor fabrication of iron and cobalt oxalate, and antimony oxides by chemical co-precipitation. Further thermochemical processes result in the formation of iron substituted skutterudites. The nanopowders are compacted by Spark Plasma Sintering (SPS) technique in order to maintain nanostructure. Detailed physicochemical as well as thermoelectric transport properties are evaluated. Results reveal strongly reduced thermal conductivity values compared to conventionally prepared counterparts, due to nanostructuring. P-type characteristic was observed from the Seebeck measurements while electrical conductivity is high and shows metallic behavior. The highest TE figure of merit of 0.25 at 800 K has been achieved, which is strongly enhanced with respect to the mother compound CoSb 3 . This suggests the promise of the utilized method of fabrication and processing for TE applications with improved performance. Keywords: Skutterudite (CoSb 3 ), thermoelectric, iron substituted skutterudite, bottom-up synthesis, SPS DOI: 10.1515/chem-2015-0074 received April 7, 2014; accepted August 13, 2014. 1 Introduction Thermoelectric (TE) materials are one of the most promising candidates for sustainable energy generation, which are attracting research communities as well as industry [1-4]. Developing TE material in large scale for industrial applications has been one of the bottlenecks of this technology. Having a synthesis route with high yield, reproducibility and low energy consumption is one of the key issues that have to be tackled and overcome. Chemical synthesis routes usually take less energy, time and have less impact on environment [5,6]. CoSb 3 , known as skutterudites, exhibit high TE figure of merit. Skutterudites have an effective TE operational range from 650K to 950 K. Among the different types of skutterudites compounds, CoSb 3 based members have attracted by far the greatest interest because of constituents’ abundant availability and less cost [7]. Iron substituted CoSb 3 , FexCo 1-x Sb 3 , have been reported to display good performance as a p-type TE material, in terms of its TE figure of merit (ZT), and abundance of the constituent elements [8-14]. The ZT can be improved via introduction of dopants, nanoengineering and in case of skutterudites, introducing rare earth elements in the crystal cages to reduce the thermal conductivity [1,4-6] due to rattling of the fillers. Previous reports on synthesis of bulk powders of iron substituted skutterudites show synthesis routes, which consume high amount of energy, in terms of heat and electricity, as well as long synthesis/processing times. Most of these processes include melting the elemental powders of constituents, using high energy ball milling and finally having a high range of annealing step from 60 hours to almost 200 hours in some cases [8,9,11-16]. Recently, Biswas et al. and Ianniduo et al. have adopted microwave synthesis for skutterudites production. [17,18]. *Corresponding author: Muhammet S. Toprak: Department of Materials and Nano Physics, KTH Royal Institute of Technology, Isafjordsgatan 22, SE16440, Kista-Stockholm, Sweden, E-mail: toprak@kth.se Mohsen Yakshi Tafti, Mohsin Saleemi, Mamoun Muhammed: Department of Materials and Nano Physics, KTH Royal Institute of Technology, Isafjordsgatan 22, SE16440, Kista-Stockholm, Sweden Mats Johnsson: Department of Materials and Environmental Chemistry, Stockholm University, Arrhenius Laboratory, 106 91 Stockholm, Sweden Alexandre Jacquot, Martin Jägle: Fraunhofer-Institut für Physikalische Messtechnik IPM, 79110 Freiburg, Germany © 2015 Mohsen Yakshi Tafti et al., licensee De Gruyter Open. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License.