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Strengthening of Thermoelectric Performance via Ir Doping in Layered Ca 3 Co 4 O 9 System
Author(s) -
Huang Yanan,
Zhao Bangchuan,
Lin Shuai,
Ang Ran,
Song Wenhai,
Sun Yuping
Publication year - 2014
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12676
Subject(s) - doping , seebeck coefficient , ferrimagnetism , x ray photoelectron spectroscopy , analytical chemistry (journal) , thermoelectric effect , valence (chemistry) , electrical resistivity and conductivity , materials science , ion , electron paramagnetic resonance , chemistry , magnetization , nuclear magnetic resonance , magnetic field , optoelectronics , physics , quantum mechanics , chromatography , thermodynamics , organic chemistry
The effects of Ir doping on thermoelectric (TE) as well as transport and magnetic properties of Ca 3 Co 4− x Ir x O 9 (0 ≤ x ≤ 0.4) series samples have been investigated systematically. Based on the analysis of X ‐ray photoelectron spectroscopy data, the valence state of the doped Ir ions is suggested to be +4. As Ir ions are doped into system, both the resistivity and the metal‐insulator transition temperature increase till to x = 0.3, indicating the more stable spin‐density‐wave state in these Ir‐doped samples. The thermopower increases monotonously with increasing x . For x = 0.4 sample, its room‐temperature thermopower S 300K reaches 166.2 μV/K, which is 36% larger than that of the undoped sample. The results show that a proper Ir doping may be an effective route to strengthen the TE performance of Ca 3 Co 4 O 9 system, which is suggested to originate from the variations of carrier concentration and lattice disharmony induced by Ir doping. At the same time, Ir doping suppresses the low‐temperature ferrimagnetic state and also introduces a spin‐glass behavior at low temperatures.