Prospects for Electrical Performance Tuning in Ca3Co4O9 Materials by Metallic Fe and Ni Particles Additions
authors Constantinescu, G; Mikhalev, SM; Lisenkov, AD; Lopes, DV; Sarabando, AR; Ferro, MC; da Silva, TF; Sergiienko, SA; Kovalevsky, AV
nationality International
journal MATERIALS
author keywords thermoelectric cobaltites; electrical performance; composite approach; transition metals additions; controlled interactions
abstract This work further explores the possibilities for designing the high-temperature electrical performance of the thermoelectric Ca3Co4O9 phase, by a composite approach involving separate metallic iron and nickel particles additions, and by employing two different sintering schemes, capable to promote the controlled interactions between the components, encouraged by our recent promising results obtained for similar cobalt additions. Iron and nickel were chosen because of their similarities with cobalt. The maximum power factor value of around 200 mu Wm(-1)K(-2) at 925 K was achieved for the composite with the nominal nickel content of 3% vol., processed via the two-step sintering cycle, which provides the highest densification from this work. The effectiveness of the proposed approach was shown to be strongly dependent on the processing conditions and added amounts of metallic particles. Although the conventional one-step approach results in Fe- and Ni-containing composites with the major content of the thermoelectric Ca3Co4O9 phase, their electrical performance was found to be significantly lower than for the Co-containing analogue, due to the presence of less-conducting phases and excessive porosity. In contrast, the relatively high performance of the composite with a nominal nickel content of 3% vol. processed via a two-step approach is related to the specific microstructural features from this sample, including minimal porosity and the presence of the Ca2Co2O5 phase, which partially compensate the complete decomposition of the Ca3Co4O9 matrix. The obtained results demonstrate different pathways to tailor the phase composition of Ca3Co4O9-based materials, with a corresponding impact on the thermoelectric performance, and highlight the necessity of more controllable approaches for the phase composition tuning, including lower amounts and different morphologies of the dispersed metallic phases.
publisher MDPI
isbn 1996-1944
year published 2021
volume 14
issue 4
digital object identifier (doi) 10.3390/ma14040980
web of science category 20
subject category Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Physics, Applied; Physics, Condensed Matter
unique article identifier WOS:000624113700001
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journal analysis (jcr 2019):
journal impact factor 3.057
5 year journal impact factor 3.424
category normalized journal impact factor percentile 58.121
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