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Nuno M. Ferreira

Nuno M. Ferreira

University of Aveiro, Portugal

Title: Thermoelectric oxides processed by a laser floating zone technique


Biography: Nuno M. Ferreira


Oxide ceramics are very promising materials for new thermoelectric devices, as they exhibit high Seebeck coefficient and could present relatively low electrical resistivity, as well as high chemical stability at high temperatures. They show anisotropic thermoelectric properties linked to their layered structures. Therefore, texturing methods developing oriented grains, such as grain growth processes have already shown their applicability to this kind and similar compounds. Among these methods, the laser floating zone (LFZ) melting technique has been found to be very promising to tune up the performances of these compounds, especially in the Co-oxide based materials studied in the last years in our laboratories. In this work, some examples highlighting the versatility and usefulness of LFZ technique and the improvements on the thermoelectric performances of textured materials will be shown. This technique allows obtaining very dense, and well textured thermoelectric composite materials. In spite of the well known incongruent solidification of this family of materials, the as-grown samples possess high thermoelectric properties which can be further enhanced by an adequate annealing procedure, leading to nearly single phase materials. These microstructural modifications produce an important improvement of power factor when compared with materials prepared through conventional techniques. Moreover, this processing technique also shows good prospects to be applied in modules construction

Recent Publications :

  1. A.V Kovalevsky, A. Myriam, S. Populoh, S. Patrício, N.M. Ferreira, S. Mikhalev,D. Fagg, A. Weidenkaff, J.R. Frade, Designing strontium titanate-based thermoelectrics: an insight into defect chemistry mechanisms, Journal of Materials Chemistry A, manuscript ID is: TA-ART-11-2016-009860.R1, Dec 2016
  2. A. Sotelo, F.M. Costa, N.M. Ferreira, A. Kovalevsky, M.C. Ferro, V.S. Amaral, J.S. Amaral, S. Rasekh, M.A. Torres, M.A. Madre, J.C. Diez. 'Tailoring Ca3Co4O9 microstructure and performances using a transient liquid phase sintering additive', J. Eur. Ceram. Soc. 36 (2016) 1025.
  3. M. A. Madre, F. M. Costa, N. M. Ferreira, S. I. R. Costa, Sh. Rasekh, M. A. Torres, J. C. Diez, V. S. Amaral, J. S. Amaral, A. Sotelo, High thermoelectric performance in Bi2-xPbxBa2Co2Ox promoted by directional growth and annealing, Journal of the European Ceramic Society 36 (2016) 67-74, DOI: 10.1016/j.jeurceramsoc.2015.09.034;
  4. Sh. Rasekh, F.M. Costa, N.M. Ferreira, M.A. Torres, M.A. Madre, J.C. Diez, A. Sotelo, Use of laser technology to produce high thermoelectric performances in Bi2Sr2Co1.8Ox, Materials and Design 75 (2015) 143–148, doi: 10.1016/j.matdes.2015.03.005;
  5. F.M. Costa, N.M. Ferreira, S. Rasekh, A.J.S. Fernandes, M.A. Torres, M.A. Madre, J.C. Diez, A. Sotelo, Very Large Superconducting Currents Induced by Growth Tailoring, Cryst. Growth Des. 15 (2015) 2094–2101. DOI: 10.1021/cg5015972
  6. Sh. Rasekh, N.M. Ferreira, F.M. Costa, G. Constantinescu, M.A. Madre, M.A. Torres, J.C. Diez, A. Sotelo, Development of a new thermoelectric Bi2Ca2Co1.7Ox + Ca3Co4O9 composite, Scripta Materialia 80 (2014), 1–4
  7. M.A. Madre, F.M. Costa, N.M. Ferreira, A. Sotelo, M.A. Torres, G. Constantinescu,Sh. Rasekh, J.C. Diez, Preparation of high-performance Ca3Co4O9 thermoelectric ceramics produced by a new two-step method, Journal of the European Ceramic Society 33 (2013) 1747–1754,  DOI:10.1016/j.jeurceramsoc.2013.01.029
  8. N.M. Ferreira, Sh. Rasekh, F.M. Costa, M.A. Madre, A. Sotelo, J.C. Diez, M. A. Torres, New method to improve the grain alignment and performance of thermoelectric ceramics, Materials Letters (2012), 144-147, DOI: 10.1016/j.matlet.2012.05.131