Study on Pressure Sintering of beta-FeSi_2 with highly Efficient Thermoelectric Properties

高效热电性能β-FeSi_2的压力烧结研究

• 批准号: 06555266
• 负责人: SHIMADA Masahiko
• 金额: $ 8.64万
• 依托单位: TOHOKU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06555266/
• 关键词: Pressure sintering; Iron silicides; Oriented grain; Anisotropic thermoelectric power; Anisotropic electric conductivity; ゼ-ベック係数; 高温熱電特性

beta-Fe_<1-x>Ru_xSi_2 solid solution was synthesized by solid state reaction at 1100ﾟC for 48h and subsequect annealing at 850ﾟC for 168h in an evacuated silica tube. Single phase solid solution was obtained in the composition range 0*x*0.1. The thermal stability range of the beta-phase extended to higher temperature region by partial substitution of Ru atom. The thermoelectric properties of Cr or Co-doped B-Fe_<1x>Ru_xSi_2 strongly depend on the sinthering conditions. The samples with optimum thermoelectric properties are obtaind by high-pressure sintering at 3 GPa and 800ﾟC for 1h. Seebeck coefficient for X-axis perpendicular to applied pressure was superior to that for Z-axis parallel to applied pressure. The anisotropy of electrical conductivity was opposite tendency comparing with the results of Seebeck coefficient. The optimum compositions are found to be Fe_<0.92>Ru_<0.05>Cr_<0.03>Si_2 and Fe_<0.92>Ru_<0.05>Co_<0.03>Si_2 for p-type and n-type materials, respectively. The power factors (sigmaalpha_2) of these materials are higher than that of beta-FeSi_2 based materials. The mechanism for the anisotropy of thermoelectric properties was examined. As a result, it is considered that the model of oriented-grain microstructure is most possible factor to introduce the anisotropy of thermoelectric properties. In this model, a very few amounts of impurities (FeSi, amorphous Si etc.) were located at grain boundaries. Both oriented-grains and impurities in microstructure play an important role to introduce the anisotropy of thermoelectric properties.

在<1-x>真空石英管中，采用固相反应法在1100 ℃下反应48 h，然后在850 ℃下退火168 h，合成了β-Fe_ Ru_xSi_2固溶体。在0*x*0.1的组成范围内获得单相固溶体。Ru原子的部分取代使β相的热稳定范围向高温区扩展。Cr、Co掺杂B-Fe_ Ru_xSi_2的热电性能<1x>与烧结条件密切相关。在3GPa和800 ℃下高压烧结1h可获得热电性能最佳的样品。垂直于外加压力的X轴的Seebeck系数上级优于平行于外加压力的Z轴。电导率的各向异性与Seebeck系数的结果相反。对于p型和n型材料，最佳成分分别为Fe_<0.92>Ru_<0.05>Cr_<0.03>Si_2和Fe_<0.92>Ru_<0.05>Co_<0.03>Si_2。这些材料的功率因数（σ α_2）高于β-FeSi_2基材料。研究了热电性能各向异性的机理。结果表明，取向晶粒微结构模型是引起热电性能各向异性的最可能因素。在该模型中，非常少量的杂质（FeSi、非晶Si等）被引入到晶体中。位于晶界。微观结构中的取向晶粒和杂质对热电性能的各向异性起着重要的作用。

项目成果

H.Takizawa: "Preparation and thermoelectric properties of β-Fe_<1-x>Ru_xSi_2" Journal of Materials Science. 30. 4199-4203 (1995)

H. Takizawa：“β-Fe_<1-x>Ru_xSi_2 的制备和热电性能”材料科学杂志 30. 4199-4203 (1995)。

M.Shimada: "Synthesis and thermoelectric properties of β-Fe_<1-X>Ru_XSi_2" Proceedings of 12th International Conference on Thermoelectric. 299-302 (1994)

M. Shimada：“β-Fe_<1-X>Ru_XSi_2 的合成和热电性能”第 12 届国际热电会议论文集 299-302 (1994)。

H.Takizawa,P.F.Mo,T.Endo,M.Shimada: "Synthesis and thermoelectric properties of β-Fe_<1-x>Ru_xSi_2" Proc.12th Inter.Conf.on Thermoelectrics. 299-302 (1993)

H.Takizawa、P.F.Mo、T.Endo、M.Shimada：“β-Fe_<1-x>Ru_xSi_2 的合成和热电性能”Proc.12th Inter.Conf.on Thermoelectrics（1993 年）。

滝沢博胤、山本賢太、遠藤忠、島田昌彦: "超高圧焼結により作製したβ-FeSi_2系熱電材料の微細構造と熱電特性の異方性" 粉体粉末冶金雑誌. 44. 39-43 (1997)

Hirotane Takizawa、Kenta Yamamoto、Tadashi Endo、Masahiko Shimada：“超高压烧结制备的β-FeSi_2基热电材料的微观结构和热电性能”粉末冶金杂志44. 39-43（1997）。

H.Takizawa,P.F.Mo,T.Endo,M.Shimada: "Preparation and thermoelectric properties of β-Fe_<1-x>Ru_xSi_2" Journal of Materials Science. 30. 4199-4203 (1995)

H.Takizawa、P.F.Mo、T.Endo、M.Shimada：“β-Fe_<1-x>Ru_xSi_2 的制备和热电性能”材料科学杂志 30. 4199-4203 (1995)。