Thermoelectric Properties of Sb-doped Mg2Si0.5Sn0.5
Thermoelectric Properties of Sb-doped Mg2Si0.5Sn0.5
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DOI：
10.1109/ict.2006.331283
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发表时间：
2006-08
期刊：
影响因子：
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通讯作者：
Y. Isoda;T. Nagai;H. Fujiu;Y. Imai;Y. Shinohara
中科院分区：
文献类型：
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作者：
Y. Isoda;T. Nagai;H. Fujiu;Y. Imai;Y. Shinohara
Mg_2Si_1-xSn_x系统是一种环境友好的半导体材料，是500 ~ 800 K温差发电器的理想材料。该体系在0.4 < x < 0.6的组成范围内的单相性至今未见报道。采用液-固反应法和热压法成功地制备了单相Mg2Si0.5Sn0.5合金。热导率的最小值在x=0.5左右确定。通过控制Mg2Si0.5Sn0.5的载流子浓度可以获得较高的热电性能。本文研究了Sb掺杂单相Mg 2Si 0. 5Sn 0. 5的热电性能。测量了从室温到850 K的塞贝克系数α、电阻率p和热导率k。所有样品的α符号均为阴性，为n型导电。对于未掺杂和5000 ppmSb掺杂的样品，α的温度依赖性分别在440 K和578 K处增加到-440muVK -1和-328muVK-1的最大值。7500 ppmSb样品的α随温度线性增加。对于非和5000 ppmSb-样品，p的温度依赖性显示半导体性质。另一方面，7500 ppmSb或更高的样品显示出金属行为。这种差异是由于载流子浓度的增加改变了导电机制的结果。随着载流子浓度的增加，热导率的载流子分量增加，而热导率的声子分量略有下降。在620 K时，Sb掺杂量为7500 ppm时，无量纲优值ZT=1.2，
Mg2Si1-xSnx systems, an ecologically friendly semiconductor, are the perspective material for thermoelectric generators at temperatures range from 500 to 800K. The single phase of this system at the compositions range of 0.4 < x < 0.6 has not been reported until now. The single phase of Mg2Si0.5Sn0.5 has been successfully obtained by a Liquid-Solid reaction method and Hot-pressing method. The minimum value of thermal conductivity was identified at around x=0.5. The high thermoelectric performance can be attained by the controlling of carrier concentration for Mg2Si0.5Sn0.5 . In this present work, the thermoelectric properties for the single-phase of Sb-doped Mg2Si0.5Sn0.5 were investigated. Seebeck coefficient alpha, electrical resistivity p and thermal conductivity k were measured from room temperature to 850K. The sign of alpha showed negative for all samples and has been n-type conduction. The temperature dependency of alpha for non-and 5000ppmSb-doped samples increased up to the maximum value of -440muVK -1 at 440K and -328muVK-1 at 578K, respectively. The alpha of 7500ppmSb sample were increased linearly with temperature. For non- and 5000ppmSb-sample, the temperature dependency of the p showed semiconducting properties. On the other hand, the sample of 7500ppmSb or more showed metallic behavior. The difference of this behavior is result of the conduction mechanism changed by the increase of carrier concentration. The carrier component of thermal conductivity was increased, while the phonon component of thermal conductivity was decreased slightly with carrier concentration. The dimensionless figure of merit was showed markedly enhanced the maximum value of ZT=1.2 for Sb doped 7500ppm at 620K