Enhancement of thermoelectric power in layered Bi2Sr2Co2−x Ir x O y single crystals
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We report on the structural, electrical, and thermal transport properties of the single crystals of Bi2Sr2Co2−x Ir x O y (0 ≤ x ≤ 0.2). Large-sized (centimeter-level) and good-quality single crystals were grown by a modified flux method. The substitution of Ir ions for Co ones makes the in-plane resistivity ρ ab increase monotonically, whereas, the in-plane thermopower S ab initially increases and then decreases as x is larger than 0.1. Therefore, among all samples, the in-plane power factor P ab (=S ab 2 /ρ ab) of Bi2Sr2Co1.9Ir0.1O y would reach a maximum value of 116.4 μWm−1K−2 at 300 K and shows a significant improvement of about 20 % compared to that of the parent sample. Our results indicate that an appropriate doping of Ir ions at Co-sites may provide an effective way to enhance the thermoelectric performance of Bi2Sr2Co2O y system.
KeywordsElectrical Transport Property Thermal Transport Property Spin State Transition CoO2 Layer Layered Cobaltite
This work is supported by the National Key Basic Research under Contract No. 2011CBA00111, and the National Nature Science Foundation of China under Contract No. 11174293, U1232140, 11174288, and 10904151, and the Scientific Research Foundation for the Returned Overseas Chinese Scholars.
- 8.Yin LH, Ang R, Huang YN, Jiang HB, Zhao BC, Zhu XB, Song WH, Sun YP (2012) The contribution of narrow band and modulation of thermoelectric performance in doped layered cobaltites Bi2Sr2Co2Oy. Appl Phys Lett 100:173503-1–173503-4Google Scholar
- 9.Yin LH, Ang R, Huang ZH, Liu Y, Tan SG, Huang YN, Zhao BC, Song WH, Sun YP (2013) Exotic reinforcement of thermoelectric power driven by Ca doping in layered Bi2Sr2−xCaxCo2Oy. Appl Phys Lett 102:141907-1–141907-5Google Scholar
- 11.Hsu HC, Lee WL, Wu KK, Kuo YK, Chen BH, Chou FC (2012) Enhanced thermoelectric figure-of-merit ZT for hole-doped Bi2Sr2Co2Oy through Pb substitution. J Appl Phys 111:103709-1–103709-5Google Scholar
- 16.Huang YN, Zhao BC, Lin S, Song WH, Sun YP (2013) Renormalized bands and low-temperature colossal thermopower induced by Ir doping in Ca3Co4O9 system. J Appl Phys 114:093709-1–093709-5Google Scholar
- 19.Zhao BC, Sun YP, Lu WJ, Zhu XB, Song WH (2006) Enhanced spin fluctuations in Ca3Co4−xTixO9 single crystals. Phys Rev B 74:144417-1–144417-8Google Scholar
- 21.Sugiyama J, Xia C, Tani T (2003) Anisotropic magnetic properties of Ca3Co4O9: evidence for a spin-density-wave transition at 27 K. Phys Rev B 67:104410-1–104410-5Google Scholar
- 26.Wu H (2012) Metal-insulator transition in Sr2−xLaxCoO4 driven by spin-state transition. Phys Rev B 86:075120-1–075120-4Google Scholar
- 29.Huang YN, Zhao BC, Fang J, Ang R, Sun YP (2011) Tunning of microstructure and thermoelectric properties of Ca3Co4O9 ceramics by high-magnetic-field sintering. J Appl Phys 110:123713-1–123713-12Google Scholar