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Energy Materials

Per Eklund, Associate Professor (Link to CV) (Publication List on DiVA)

Group Leader, Energy Materials Group

ERC Starting Grant holder, SSF Future Research Leader

ResearchGate: www.researchgate.net/profile/P_Eklund

The Energy Materials group conducts fundamental and application-inspired studies in the general area of thin-film materials for energy applications. We investigate, among others, thermoelectrics, ionic conductors for fuel-cell applications, MAX phases, and hard coatings. Materials synthesis is performed by a wide range of sputter-deposition techniques. We are predominantly experimental materials scientists, but theoretical studies are an integral part of the work.

Group members

Senior scientists and postdocs

Dr. Biplab Paul, Asst. Prof. (PhD IIT Kharagpur, personal webpage)

Dr. Arnaud le Febvrier, Asst. Prof. (PhD Univ. Nantes)

Dr. Clio Azina, postdoc (PhD Univ. Bordeaux)


PhD students

Ludvig Landälv

Amin Gharavi

Erik Ekström

Binbin Xin


BSc/internship students

Fanny Bourgeios


Scientific highlights

Nanostructural tailoring to induce flexibility in thermoelectric Ca3Co4O9 thin films

Biplab Paul, Jun Lu, and Per Eklund

ACS Applied Materials & Interfaces 9 25308 (2017)

Due to their inherent rigidity and brittleness, inorganic materials have seen limited use in flexible thermoelectric applications. On the other hand, for high output power density and stability, the use of inorganic materials is required.  Here, we demonstrate a concept of fully-inorganic flexible thermoelectric thin films with Ca3Co4O9-on-mica. Ca3Co4O9 is promising not only due to its high Seebeck coefficient and good electrical conductivity but also important due to the abundance, low cost and nontoxicity of its constituent raw materials.  We show a promising nanostructural-tailoring approach to induce flexibility in inorganic thin film materials, achieving flexibility in nanostructured Ca3Co4O9 thin films. The films were grown by thermally induced phase transformation from CaO-CoO thin films deposited by rf-magnetron reactive cosputtering from metallic targets of Ca and Co, to final phase of Ca3Co4O9 on mica substrate. The pattern of nanostructural evolution during solid state phase transformation is determined by surface energy and strain energy contributions, while different distributions of CaO and CoO phases in the as-deposited films promote different nanostructuring during phase transformation. Another interesting fact is that the Ca3Co4O9 film is transferable onto arbitrary flexible platform from parent mica substrate by etch free dry transfer. The highest thermoelectric power factor obtained is above 1 ´ 10-4 Wm-1K-2 in a wide temperature range, and thus showing low temperature applicability of this class of materials  

Synthesis of Ti3AuC2, Ti3Au2C2 and Ti3IrC2 by noble-metal substitution reaction in Ti3SiC2 for high-temperature-stable ohmic contacts to SiC  

Hossein Fashandi, Martin Dahlqvist, Jun Lu, Justinas Palisaitis, Sergei I. Simak, Igor A. Abrikosov, Johanna Rosen, Lars Hultman, Mike Andersson, Anita Lloyd Spetz, and Per Eklund

Nature Materials 16, 814, 2017

The large class of layered ceramics encompasses both van der Waals (vdW) and non-vdW solids. While intercalation of noble metals in vdW solids is known, formation of compounds by incorporation of noble-metal layers in non-vdW layered solids is largely unexplored.  Here, we show formation of Ti3AuC2 and Ti3Au2C2 phases with up to 31% lattice swelling by a substitutional solid-state reaction of Au into Ti3SiC2 single-crystal thin films with simultaneous out-diffusion of Si.  Ti3IrC2 is subsequently produced by a substitution reaction of Ir for Au in Ti3Au2C2. These phases form ohmic electrical contacts to SiC and remain stable after 1000 h of aging at 600 °C in air. The present results, by combined analytical electron-microscopy and ab-initio calculations, open avenues for processing of noble-metal-containing layered ceramics that have not been synthesized from elemental sources, along with tunable properties such as stable electrical contacts for high-temperature power electronics or gas sensors.  

Mechanism of Formation of the Thermoelectric Layered Cobaltate Ca3Co4O9 by Annealing of CaO-CoO Thin Films

Biplab Paul, Jeremy L. Schroeder, Sit Kerdsongpanya, Ngo Van Nong, Norbert Schell, Daniel Ostach, Jun Lu, Jens Birch, Per Eklund

Advanced Electronic Materials, 1, 1400022 (2015) DOI: 10.1002/aelm.201400022

We show a novel two step sputtering/annealing method for thin film growth of highly textured Ca3Co4O9. CaO-CoO thin films were deposited by reactive rf-magnetron co-sputtering from Ca and Co targets. Synchrotron-based 2D x-ray diffraction as well as ex-situ annealing experiments and standard lab-based x-ray diffraction analyses reveal the underlying mechanism of thermally activated phase transformation from CaO-CoO into Ca3Co4O9.

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Last updated: 04/09/18