Fabrication and thermoelectric properties of heavily rare-earth metal-doped SrO(SrTiO3)n (n=1, 2) ceramics

초록

To clarify the effect of substitutional electron doping on the thermoelectric figure of merit (ZT= S-2 sigma T kappa(-1)) of Ruddlesden-Popper phase SrO(SrTiO3)(n) (or Srn+1TinO3n+1), measurements were conducted for several thermoelectric parameters, e.g. electrical conductivity (a), Seebeck coefficient (S) and thermal conductivity (kappa), of (Sr1-xREx)(n+1)TinO3n+1 (n = 1 or 2, RE (rare earth): La or Nd, x = 0.05 and 0.1) dense ceramics prepared by a conventional solid-state reaction and hot-pressing technique. Crystal structures of the resultant ceramics were represented as (Sr1-xREx)(n+1) TinO3n+1, evaluated by powder X-ray diffraction followed by the Rietveld analysis. All the ceramics exhibited electrical conductivity and the a values simply depended on the dopant concentration, indicating that both La3+ and Nd3+ ions act as electron donors. The vertical bar S vertical bar values increased with temperature due to decrease in the chemical potential. Significant reduction of the K values was observed as compared to cubic-perovskite SrTiO3. The ZT value increased with temperature and reached 0.15 at 1000 K for (Sr0.95La0.05)(3)Ti2O7. (C) 2007 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

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