liu.seSearch for publications in DiVA
Change search
Link to record
Permanent link

Direct link
BETA
Paul, Biplab
Publications (3 of 3) Show all publications
Paul, B., Björk, E. M., Kumar, A., Lu, J. & Eklund, P. (2018). Nanoporous Ca3Co4O9 Thin Films for Transferable Thermoelectrics. ACS applied energy materials, 1(5), 2261-2268
Open this publication in new window or tab >>Nanoporous Ca3Co4O9 Thin Films for Transferable Thermoelectrics
Show others...
2018 (English)In: ACS applied energy materials, ISSN 2574-0962, Vol. 1, no 5, p. 2261-2268Article in journal (Refereed) Published
Abstract [en]

The development of high-performance and transferable thin-film thermoelectric materials is important for low-power applications, e.g., to power wearable electronics, and for on-chip cooling. Nanoporous films offer an opportunity to improve thermoelectric performance by selectively scattering phonons without affecting electronic transport. Here, we report the growth of nanoporous Ca3Co4O9 thin films by a sequential sputtering-annealing method. Ca3Co4O9 is promising for its high Seebeck coefficient and good electrical conductivity and important for its nontoxicity, low cost, and abundance of its constituent raw materials. To grow nanoporous films, multilayered CaO/CoO films were deposited on sapphire and mica substrates by rf-magnetron reactive sputtering from elemental Ca and Co targets, followed by annealing at 700 C to form the final phase of Ca3Co4O9. This phase transformation is accompanied by a volume contraction causing formation of nanopores in the film. The thermoelectric propoperties of the nanoporous Ca3Co4O9 films can be altered by controlling the porosity. The lowest electrical resistivity is ~7 mO cm, yielding a power factor of 2.32 × 10-4 Wm-1K-2 near room temperature. Furthermore, the films are transferable from the primary mica substrates to other arbitrary polymer platforms by simple dry transfer, which opens an opportunity of low-temperature use these materials.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
Ca3Co4O9; nanoporous; thermoelectrics; thin film; transferable
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-155845 (URN)10.1021/acsaem.8b00333 (DOI)000458705500058 ()29905306 (PubMedID)
Available from: 2019-03-29 Created: 2019-03-29 Last updated: 2019-04-04Bibliographically approved
Rawat, P. K. & Paul, B. (2016). Simple design for Seebeck measurement of bulk sample by 2-probe method concurrently with electrical resistivity by 4-probe method in the temperature range 300-1000 K. Measurement, 91, 613-619
Open this publication in new window or tab >>Simple design for Seebeck measurement of bulk sample by 2-probe method concurrently with electrical resistivity by 4-probe method in the temperature range 300-1000 K
2016 (English)In: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 91, p. 613-619Article in journal (Refereed) Published
Abstract [en]

The 4-probe method has so far been the most popular method for concurrent measurement of Seebeck coefficient and electrical resistivity of bulk samples. However, for Seebeck measurement with higher accuracy, the 2-probe method is becoming preferred over 4-probe method. The problem with the previous apparatus designs is that they do not allow 2-probe arrangement for Seebeck measurement simultaneously with linear 4-probe arrangement for electrical resistivity measurement. So, the challenge is find a design where two different probe arrangements become possible at the same time in a single measurement run. Here, we report design and fabrication of an apparatus that allows Seebeck measurement by 2-probe method concurrently with electrical resistivity by 4-probe method of bar and disc samples in the temperature range from 300 to 1000 K. The uniqueness of the present design is that it does not require heating the entire sample chamber for temperature dependent measurements. This is because a small cylindrical furnace inside the sample chamber is used to control the sample background temperature. This internal furnace arrangement results in readily achievable set temperature with desired uniformity. Thus, it allows faster thermoelectric evaluation of samples. The design includes several preventive steps to negate the effect of off-axial heat flows on the measurement accuracy. The measurement error in Seebeck coefficient and electrical resistivity of PbTe sample is estimated to be smaller than 5%. (C) 2016 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2016
Keywords
Measurement; Seebeck coefficient; 2-probe method; Electrical resistivity; 4-probe method
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:liu:diva-130366 (URN)10.1016/j.measurement.2016.05.104 (DOI)000379507400068 ()
Note

Funding Agencies|University Grant Commission (UGC) of India through UGC (NET); Council of Scientific and Industrial Research (CSIR) India through CSIR (NET); Eurostars project [E!8892 T-to-Power]; European Research Council under the European Communitys Seventh Framework Programme/ERC - Belgium [335383]

Available from: 2016-08-15 Created: 2016-08-05 Last updated: 2017-11-28
Paul, B., Schroeder, J. L., Kerdsongpanya, S., van Nong, N., Schell, N., Ostach, D., . . . Eklund, P. (2015). Mechanism of Formation of the Thermoelectric Layered Cobaltate Ca3Co4O9 by Annealing of CaO-CoO Thin Films. Advanced Electronic Materials, 1(3), Article ID 1400022.
Open this publication in new window or tab >>Mechanism of Formation of the Thermoelectric Layered Cobaltate Ca3Co4O9 by Annealing of CaO-CoO Thin Films
Show others...
2015 (English)In: Advanced Electronic Materials, ISSN 2199-160X, Vol. 1, no 3, article id 1400022Article in journal (Refereed) Published
Abstract [en]

The layered cobaltate Ca3Co4O9 is of interest for energy-harvesting and heat-conversion applications because of its good thermoelectric properties and the fact that the raw materials Ca and Co are nontoxic, abundantly available, and inexpensive. While single-crystalline Ca3Co4O9 exhibits high Seebeck coefficient and low resistivity, its widespread use is hampered by the fact that single crystals are too small and expensive. A promising alternative approach is the growth of highly textured and/or epitaxial Ca3Co4O9 thin films with correspondingly anisotropic properties. Here, we present a two-step sputtering/annealing method for the formation of highly textured virtually phase-pure Ca3Co4O9 thin films by reactive cosputtering from Ca and Co targets followed by an annealing process at 730 °C under O2-gas flow. The thermally induced phase transformation mechanism is investigated by in situ time-resolved annealing experiments using synchrotron-based 2D X-ray diffraction (XRD) as well as ex situ annealing experiments and standard lab-based XRD. By tuning the proportion of initial CaO and CoO phases during film deposition, the method enables synthesis of Ca3Co4O9 thin films as well as CaxCoO2. With this method, we demonstrate production of epitaxial Ca3Co4O9 thin films with in-plane electrical resistivity of 6.44 mΩ cm and a Seebeck coefficient of 118 μV K−1 at 300 K.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2015
Keywords
Thermoelectrics, Ca3Co4O9, thin film, sputtering, phase transformation
National Category
Condensed Matter Physics Other Materials Engineering Nano Technology
Identifiers
urn:nbn:se:liu:diva-117610 (URN)10.1002/aelm.201400022 (DOI)000357653900004 ()
Funder
EU, European Research Council, 335383Swedish Research Council, 2012-4430Swedish Research Council, 2011-6505Swedish Foundation for Strategic Research , Future Research Leaders 5
Available from: 2015-05-06 Created: 2015-05-06 Last updated: 2016-02-16Bibliographically approved
Organisations

Search in DiVA

Show all publications