TY - JOUR
T1 - Ruddlesden-Popper phases as thermoelectric oxides
T2 - Nb-doped SrO(SrTiO 3)n(n=1,2)
AU - Lee, Kyu Hyoung
AU - Kim, Sung Wng
AU - Ohta, Hiromichi
AU - Koumoto, Kunihito
PY - 2006
Y1 - 2006
N2 - 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.
AB - 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.
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U2 - 10.1063/1.2349559
DO - 10.1063/1.2349559
M3 - Article
AN - SCOPUS:33749335618
SN - 0021-8979
VL - 100
JO - Journal of Applied Physics
JF - Journal of Applied Physics
IS - 6
M1 - 063717
ER -