TY - JOUR
T1 - Enhancement of thermoelectric performance in rare earth-doped Sr 3Ti2O7 by symmetry restoration of TiO 6 octahedra
AU - Wang, Yifeng
AU - Lee, Kyu Hyoung
AU - Hyuga, Hideki
AU - Kita, Hideki
AU - Ohta, Hiromichi
AU - Koumoto, Kunihito
PY - 2010/4
Y1 - 2010/4
N2 - Aiming at the realization of the enhancement of thermoelectric performance through structural modification, the present work has clarified the significant effects of rare earth (RE=Gd, Sm, Nd, and La) doping at Sr-sites in Sr 3Ti 2O 7, both on the structural restoration of distorted TiO 6 octahedra and on the Seebeck coefficient, especially at high temperatures. The preferential substitution of RE 3+ at the nine-coordinate Sr-sites can facilitate the degeneration of the conduction band (Ti 3d-t 2g) orbital, owing to its special capability in restoring TiO 6 octahedra to a higher state of symmetry and thus enhance the density of states (DOS) effective mass of the carriers, which gives rise to a rather large increase in the Seebeck coefficient. The present findings have affirmed the effectiveness of structural restoration in enhancing the Seebeck coefficient by Sr-site-doping, which will help establish a useful solution for Ti-based thermoelectric oxides with inherently distorted TiO 6 octahedra to achieve high thermoelectric performance.
AB - Aiming at the realization of the enhancement of thermoelectric performance through structural modification, the present work has clarified the significant effects of rare earth (RE=Gd, Sm, Nd, and La) doping at Sr-sites in Sr 3Ti 2O 7, both on the structural restoration of distorted TiO 6 octahedra and on the Seebeck coefficient, especially at high temperatures. The preferential substitution of RE 3+ at the nine-coordinate Sr-sites can facilitate the degeneration of the conduction band (Ti 3d-t 2g) orbital, owing to its special capability in restoring TiO 6 octahedra to a higher state of symmetry and thus enhance the density of states (DOS) effective mass of the carriers, which gives rise to a rather large increase in the Seebeck coefficient. The present findings have affirmed the effectiveness of structural restoration in enhancing the Seebeck coefficient by Sr-site-doping, which will help establish a useful solution for Ti-based thermoelectric oxides with inherently distorted TiO 6 octahedra to achieve high thermoelectric performance.
KW - Local symmetry
KW - Ruddlesden-popper phase
KW - Thermoelectric properties
KW - TiOoctahedra
UR - http://www.scopus.com/inward/record.url?scp=77953293768&partnerID=8YFLogxK
U2 - 10.1007/s10832-008-9455-9
DO - 10.1007/s10832-008-9455-9
M3 - 文章
AN - SCOPUS:77953293768
SN - 1385-3449
VL - 24
SP - 76
EP - 82
JO - Journal of Electroceramics
JF - Journal of Electroceramics
IS - 2
ER -