Papers by Keyword: Thermoelectric Property

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Authors: Ming Liang Li, Hai Long Wang, Rui Zhang, Jing Li, Jun Hao Li
Abstract: SiC powders with nickel powders and sintering aids were prepared by pressureless sintering at 1500oC under a N2 atmosphere. XRD, TEM, SEM techniques were used to characterize the phases and microstructure of the specimens. The thermoelectric properties of SiC matrix composites were investigated by measuring the Seebeck coefficient and the electrical conductivity. The main phase of all samples was -SiC, the Ni2Si can be observed with adding nickel powders. The largest electric conductivity was close to 3.5 m-1-1 at about 973K. The highest Seeback coefficient was up to 1800 V/K at 1073K. The transition from n-type to p-type was occurred.
Authors: S. Yoneda, E. Ohta, Yoshikazu Shinohara, T. Kimura, Isao A. Nishida, H.T. Kaibe
Authors: Youhei Sakamaki, Kosuke Kuwabara, Gu Jiajun, Haruyuki Inui, Masaharu Yamaguchi, Atsushi Yamamoto, Haruhiko Obara
Authors: Čestmir Drašar, Antje Mrotzek, Christian Stiewe, Eckhard Müller, Wolfgang A. Kaysser
Authors: Wei Jun Luo, Mei Jun Yang, Qiang Shen, Hong Yi Jiang, Lian Meng Zhang
Abstract: The single phase of Bi-doped Mg2Si0.5Sn0.5 compounds have been successfully fabricated by solid state reaction-spark plasma sintering (SPS). The effect of Bi doping concentration on the thermoelectric properties of Mg2Si0.5Sn0.5 is mainly investigated. The doping of Bi atom introduces impurity energy to Mg2Si0.5Sn0.5 compounds, which results in the increase of carrier concentration ( ), meanwhile it causes the increase of crystal distortion, enhancing the scatter of phonon. The results show that with the increasing of Bi doping content, the electrical conductivity (σ) increase, the absolute Seebeck coefficient ( ) and thermal conductivity ( ) decrease slightly in the measuring temperature range between 300 K and 800K. When the doping concentration of Bi is up to 2.5at% (nominal molar percent), the sample shows a maximum value of the figure of merit, ZT, is 0.78 at 800K.
Authors: Yuzuru Miyazaki, Yoshitsugu Saito, Kei Hayashi, Kunio Yubuta, Tsuyoshi Kajitani
Abstract: A partially cobalt-substituted solid solution of Nowotny chimney-ladder phase, (Mn1-xCox)Si􀀂, has been prepared using a tetra-arc-type furnace and a subsequent annealing process. The compounds consist of two tetragonal subsystems of [Mn1-xCox] and [Si], with an irrational c-axis ratio 􀀂 = cMn/cSi ~ 1.7. The crystal structure and thermoelectric properties of (Mn1-xCox)Si􀀂 solid solution were compared with those of the Fe-substituted solid solution, (Mn1-xFex)Si􀀂. In the case of Co-series, extra valence electrons are introduced relative to Fe-series, since the valence electron count is 3d74s2 for Co but 3d64s2 for Fe, respectively. It was naturally expected that the Feand Co-substituted MnSi􀀁 becomes n-type conductor from the p-type one at x > 0.23(5) and x > 0.06(1), respectively. Experimentally, the Fe-substituted samples become n-type at x > 0.28 but it is not the case for the Co-substituted ones. It is thus evident that there is an unknown factor which controls the thermoelectric properties of Co-substituted samples.
Authors: Qing Sen Meng, Wen Hao Fan, L.Q. Wang, L.Z. Ding
Abstract: Iron disilicide (-FeSi2, and -FeSi2+Cu0.1wt%) were prepared by a field-activated pressure assisted synthesis(FAPAS) method from elemental powders and the thermoelectric properties were investigated. The average grain size of these products is about 0.3m. The thermal conductivity of these materials is 3-4wm-1K-1in the temperature range 300-725K. These products’ figure of merit is 28.50×10-4 in the temperature range 330-450K. The additions of Cu promote the phase transformation of -Fe2Si5 + -FeSi → β-FeSi2 and shorten the annealing time. It is proved that FAPAS is a benign and rapid process for sintering of -FeSi2 thermoelectric materials.
Authors: Jun Jiang, Li Dong Chen, Sheng Qiang Bai, Qin Yao, Qun Wang
Abstract: The n-type Bi2(Te,Se)3 thermoelectric materials doped with different contents of TeI4 were fabricated through the spark plasma sintering (SPS) technique at 693K under a pressure of 60MPa. The sintered materials were rather dense and showed preferred grain orientation. Electrical conductivity (s), Seebeck coefficient (a), and thermal conductivity (k) were measured in the temperature range of 300-500K. The optimal figure of merit ZT (ZT=a2sT/k) of the sintered material in the direction perpendicular to the pressing direction showed a value of 0.75 for the sample containing 0.14wt% TeI4.
Authors: Yan Lu, Ying Song, Jin Feng, Fu Ping Wang
Abstract: A series of (Ca0.9Gd0.1)3Co4O9/xAg(x=0, 0.1, 0.15, 0.2) ceramics were prepared by a polyacrylamide gel method and Spark Plasma Sintering. Scanning electron microscopy (SEM) revealed that small size Ag particles were dispersed into the (Ca0.9Gd0.1)3Co4O9(CGCO) matrix. The electrical conductivity of the composites was obviously higher than that of (Ca0.9Gd0.1)3Co4O9, and increased with increase of Ag content. However, the addition of Ag seemed to have a negative impact on the Seebeck coefficient (S) of the composites samples due to its poor S. Since the increase of electrical conductivity (σ) is more significant than the degradation of S, the power factor (P=σS2) was found to be improved by the addition of Ag. At 973 K, the P value of the sample with x =0.2 reached 3.17×10-4 W•m-1•K-2, which was 12.5% higher than that of Ca3Co4O9(CCO) bulk material.
Authors: Qiang Shen, Li Jun Zhang, Gang Wang, Leng Chen, Rong Tu, Toshio Hirai
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