Correlation between the structural distortions and thermoelectric characteristics in La(1-x)A(x)CoO(3) (A = Ca and Sr).
Detailed structures and thermoelectric (TE) properties are investigated for the perovskite La(1-x)Ca(x)CoO(3) and La(1-x)Sr(x)CoO(3) with 0 <or= x <or= 0.3. The monoclinic crystal structures for all samples are refined from powder X-ray diffraction, which reveals that the La(1-x)Sr(x)CoO(3) series has smaller global distortions but larger local distortions. The different structural distortions strongly influence the transport and TE properties in terms of resistivity, thermopower, thermal conductivity, bandwidth, and effective mass as well as electronic correlation. These results unambiguously demonstrate a close correlation between the structural distortions and TE characteristics in this family. Furthermore, a new approach is suggested to improve the TE performance by controlling the structure factors in such strongly correlated oxide systems. The effects of the spin-state transition of Co ions on the TE properties are also discussed.
Wang
Yang
Y
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore.
Sui
Yu
Y
Ren
Peng
P
Wang
Lan
L
Wang
Xianjie
X
Su
Wenhui
W
Fan
Hong Jin
HJ