Effect of impurity oxygen concentration on the thermoelectric properties of hot-pressed Zn4Sb3
Effect of impurity oxygen concentration on the thermoelectric properties of hot-pressed Zn4Sb3
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DOI：
10.1016/j.jallcom.2005.09.014
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发表时间：
2006-06
影响因子：
6.2
通讯作者：
K. Ueno;A. Yamamoto;T. Noguchi;C. Li;T. Inoue;S. Sodeoka;H. Obara
中科院分区：
文献类型：
--
作者：
K. Ueno;A. Yamamoto;T. Noguchi;C. Li;T. Inoue;S. Sodeoka;H. Obara
采用真空热压法，在748 K、49 MPa下热压5 h制备了两种不同氧含量的p型ZnO-Zn 4Sb 3热电材料，并对其输运和热电性能进行了研究。由高纯度Zn和Sb粉末以及由市售粉末制备的Zn 4Sb 3的氧含量分别为0.209%和0.625%。在323 ~ 673 K温度范围内测定了电阻率和塞贝克系数。从室温到600 K，两种Zn 4Sb 3样品的电阻呈现相似的线性温度依赖关系，只是贫氧Zn 4Sb 3样品的电阻略高.然而，在600 K以上，富氧的Zn_4Sb_3显示出不规则的向下偏离线性，不同于高纯度样品。这种反常的温度依赖性的基础上的Zn 4Sb 3的热稳定性进行了检查，并可以解释通过Zn的释放和吸收的Zn 4Sb 3晶格在较高的温度下的机制。的塞贝克系数示出了类似的电阻的温度依赖性，但其绝对值较高的情况下，贫氧的Zn 4Sb 3。基于这些电性能，发现贫氧Zn_4Sb_3的功率因数高约20%。另一方面，贫氧的Zn 4Sb 3的热导率较高。因此，热电性能，即，当温度高于500 K时，贫氧Zn_4Sb_3的ZT值较低。贫氧和富氧化合物分别在622和660 K达到最大ZT值（分别为0.93和1.08）。
Two kinds of thermoelectric p-type semiconductive ɛ-Zn4Sb3with different oxygen content were prepared by hot-pressing at 748K under 49MPa for 5h in vacuum, and their transport and thermoelectric properties were evaluated to study the effect of oxygen concentration. The oxygen content of Zn4Sb3fabricated from high-purity Zn and Sb powders and from a commercially available powder was 0.209% and 0.625%, respectively. Electrical resistance and Seebeck coefficient were evaluated from 323 to 673K. The electrical resistance of the two Zn4Sb3samples exhibited a similar linear temperature dependence from room temperature up to about 600K, except that the resistance of the oxygen-poor Zn4Sb3was slightly higher. Above 600K, however, the oxygen-rich Zn4Sb3showed an irregular downward deviation from linearity, unlike the high-purity sample. This anomalous temperature dependence was examined on the basis of the thermal stability of Zn4Sb3, and could be explained through a mechanism of Zn release and absorption by the Zn4Sb3lattice at higher temperatures. The Seebeck coefficient showed a temperature dependence similar to that of the electrical resistance, but its absolute value was higher in the case of the oxygen-poor Zn4Sb3. Based on these electrical properties, it was found that the power factor of the oxygen-poor Zn4Sb3was about 20% higher. On the other hand, the thermal conductivity of the oxygen-poor Zn4Sb3was higher. Thus, the thermoelectric performance, i.e., the ZT value, of the oxygen-poor Zn4Sb3was lower at temperatures above 500K. The oxygen-poor and oxygen-rich compounds attained their maximum ZT maxima (0.93 and 1.08, respectively) at 622 and 660K, respectively.