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Home  >  Journal list  >  Journal of the Ceramic Society of Japan  >  Vol.117  No.1364 (April) (2009)  >  pp.466-469

Journal of the Ceramic Society of Japan
<<Previous article Vol.117  No.1364 (April) (2009)   pp.466 - 469 Next article>>

Thermoelectricity of CaIrO3 ceramics prepared by spark plasma sintering

Nittaya KEAWPRAK1), Rong TU1) and Takashi GOTO1)
1) Institute for Materials Research, Tohoku University

  Polycrystalline bulk CaIrO3 as a main phase with minor phases of IrO2 and/or Ca2IrO4 was prepared by spark plasma sintering (SPS) at 1273 K. Metastable CaIrO3 with a perovskite-type structure (pv-CaIrO3) formed by heat-treatment at 1273 K for 43.2 ks and transformed into a post-perovskite structure (ppv-CaIrO3) by heat-treatment at 1273 K for 259.2 ks. The electrical conductivity (σ) of the pv-CaIrO3 specimen decreased from 1.74 × 104 to 1.45 × 104 Sm-1, while the σ of the ppv-CaIrO3 specimen increased from 5.0 × 101 to 9.8 × 102 Sm-1 with increasing temperature from 298 to 1023 K. The Seebeck coefficient (S) of the pv-CaIrO3 specimen was around -44 μVK-1 at room temperature and increase to the highest value of 40 μVK-1 at 1023 K. The S of the ppv-CaIrO3 specimen decreased with increasing temperature and had an almost constant value of about 60 μVK-1 above 600 K. The thermal conductivity (κ) of the ppv-CaIrO3 specimen decreased from 2.7 to 1.2 Wm-1K-1 and that of the pv-CaIrO3 specimen decreased from 1.5 to 1.2 Wm-1K-1 with increasing temperature from 298 to 1023 K. The highest dimensionless figure of merit values (ZT) of the pv-CaIrO3 and the ppv-CaIrO3 specimens were 0.02 and 0.003 at 1023 K, respectively.


Keyword:
Thermoelectric materials, Calcium Iridium oxide, Spark plasma sintering

Received: December 18, 2008
Accepted: February 19, 2009 , Published online: April 01, 2009
Copyright (c) 2009 The Ceramic Society of Japan

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