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Research Article Open Access

Thermoelectric properties of hot-pressed pellets of Al and Ti co-doped calcium cobalt oxides (Ca(3-x)AlxCo(4-y)TiyO9+δ)

 

 

Raj K. Gupta, and Ajit K. Mahapatro*, Ram P. Tandon*

 

 

Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India

Adv. Mater. Proc., 2018, 3 (2), 103-107

DOI: 10.5185/amp.2018/848

Publication Date (Web):05 February 2018

Copyright © IAAM-VBRI Press

Abstract


Abstract  

This work demonstrates the achievement of high thermopower in the pellets of calcium cobalt oxide (Ca3Co4O9) co-doped with aluminium (Al) and titanium (Ti). The pellets of Ca(3-x)AlxCo(4-y)TiyO9+δ with x, y = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5, oxide ceramics are prepared using a hot-press machine by applying an uniaxial pressure of 70 MPa at a dwell temperature of
850 ºC. Microstructure imaging reveals compactness of good connectivity among grains with the estimated density using Archimedes principle suggests the formation of near perfect (99%) relative density for the new pelleted ceramics. All the
co-doped samples exhibit lower electrical resistivity (r) values compared to pure Ca3Co4O9. The maximum Seebeck coefficient (S) of 177 μV/K at 750 K is achieved for the pure Ca3Co4O9 sample. A significant improvement of 18% in the power factor (S2/r) is realized at 750 K in the co-doped samples containing 0.2 mol% of Al and Ti co-doping. The demonstration of significant thermoelectric properties of Ca(3-x)AlxCo(4-y)TiyO9+δ suggest that these materials could be utilized as promising active material in thermoelectrics. Copyright © 2018 VBRI Press.

Keywords


Electrical resistivity, thermoelectric materials, power factor, seebeck coefficient.