Effect of Si/C Ratio on Thermoelectric Properties of β-FeSi2 Mechanically Alloyed with (Si+C) Additions
Effect of Si/C Ratio on Thermoelectric Properties of β-FeSi2 Mechanically Alloyed with (Si+C) Additions
复制标题
Si/C比对(Si+C)添加β-FeSi2机械合金化热电性能的影响
DOI：
10.2320/matertrans1989.41.287
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
K. Majima
中科院分区：
文献类型：
--
作者：
H. Nagai;Takayuki Katsura;Mikio Ito;S. Katsuyama;K. Majima
为了提高β相的热电性能，研究了在不同Si/C摩尔比（Si/C = 0.5 × 10 2）下，机械合金化4mass%的n型Fe 0.98Co0.0 2Si 2和p型Fe 0.92Mn0.0 8 Si 2合金的热电性能。n型和p型机械合金化和热压样品均主要由β相组成，并分散有少量金属e相颗粒。在含有4质量%（Si+C）的样品中，s相的量随着Si/C比的增加而减少。在Si/C = 1.5和1.75时，n型和p型FeSi 2的e相消失。机械合金化20 h和1173 K热压1h的样品中形成了大量20 nm左右的细小a-SiC颗粒。热电功率随着Si/C比的增加而增加，这是由于金属s相与部分Si（其被添加以形成SiC）反应而增加半导体β相的量。在n型FeSi 2中，当Si/C = 1.5时，热电功率最大; p型FeSi 2中，当Si/C = 1.75时，热电功率最大。虽然电阻率的增加，通过添加（Si + C），Si/C比的电阻率的依赖性是不剧烈的n型和p型FeSi 2。（Si + C）的加入，由于α-SiC颗粒的弥散，使n型和p型FeSi 2的热导率均显著降低。最大优值出现在Si/C = 1.5的n型FeSi 2样品中含有4质量%（Si + C）和Si/C = 1.75的p型。
In order to improve the thermoelectric performance of β-phase, the thermoelectric properties of hot-pressed n-type Fe 0.98 Co 0.02 Si 2 and p-type Fe 0.92 Mn 0.08 Si 2 mechanically alloyed with 4mass% of (Si + C) powders at various Si/C molar ratios (Si/C = 0.5 ∼ 2) have been investigated. Both the n-type and p-type mechanically alloyed and hot-pressed samples are composed of mostly the β-phase with a dispersion of a small amount of metallic e-phase particles. The amount of the s-phase decreases with increasing Si/C ratio in samples containing 4 mass%(Si+C). The e-phase disappears at Si/C = 1.5 for the n-type and 1.75 for p-type FeSi 2 . Many fine a-SiC particles around 20 nm form in the samples mechanically alloyed for 20h and hot-pressed at 1173K for 1 h. The thermoelectric power increases with increasing Si/C ratio due to the increase in the amount of the semiconducting β-phase by the reaction of the metallic s-phase with some part of Si, which was added to form SiC. The thermoelectric power exhibits a maximum at Si/C = 1.5 in n-type FeSi 2 containing 4 mass%(Si + C) and Si/C = 1.75 for p-type. Although the electrical resistivity is increased by the addition of (Si + C), the Si/C ratio dependence of the electrical resistivity is not drastic for both n-type and p-type FeSi 2 . The addition of (Si + C) markedly decreases the thermal conductivity of both n-type and p-type FeSi 2 due to the dispersion of fine α-SiC particles. The maximum figure of merit values appear at Si/C = 1.5 in n-type FeSi 2 samples containing 4 mass%(Si + C) and Si/C = 1.75 for p-type.