Ruddlesden-Popper phases as thermoelectric oxides: Nb-doped SrO(SrTiO 3)n(n=1,2)

Kyu Hyoung Lee, Sung Wng Kim, Hiromichi Ohta, Kunihito Koumoto

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84 Citations (Scopus)

Abstract

A class of materials known as superlattices has shown substantial promise for potential thermoelectric (TE) applications because of its low thermal conductivity. We have investigated natural superlattice Ruddlesden-Popper (RP) phases [S. N. Ruddlesden and P. Popper, Acta Crystallogr. 10, 538 (1957)] to elucidate their potential as TE materials. The TE properties of Nb-doped SrO(SrTiO3)n (n =1,2) with a RP structure were measured, and the origin of the TE properties is discussed from the viewpoint of the structure of the TiO6 octahedron. Compared with the cubic perovskite-type Nb-doped SrTiO3, the lattice thermal conductivity decreased by more than 50% (4.4-5 W m-1 K-1) at room temperature and by 30% (1.9-2.2 W m-1 K-1) at 1000 K. There was a decrease in electrical conductivity owing to the randomly distributed insulating SrO layers in polycrystalline RP phases, and it was found that large TE power can be obtained in conjunction with high symmetry TiO 6 octahedra. The largest dimensionless figure of merit (ZT), 0.14 at 1000 K, was obtained in 5 at. % Nb-doped SrO(SrTiO3)2.

Original languageEnglish
Article number063717
JournalJournal of Applied Physics
Volume100
Issue number6
DOIs
Publication statusPublished - 2006

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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