Mg或Sm元素掺杂对Se替代PbTe、GeTe及其合金的热电性能优化研究

发布时间：2018-12-27 15:04

【摘要】：Pb Te、Ge Te是性能较好的中温热电材料,在发电领域有广泛的应用前景,在节能减排、低碳环保方面具有重要的意义。Se替代Pb Te-Ge Te合金中的Te后,能够增加Pb在Ge Te中的固溶度并提高材料的热电性能。本工作采用熔炼、热处理、淬火及放电等离子烧结(SPS)等工艺制备了Pb0.98-xMgxNa0.02Te0.5Se0.5、Ge1-xMgxTe0.7Se0.3及Ge0.75Pb0.2Sm0.03Te1-xSex三个系列合金样品,以进一步探究Mg及Sm元素掺杂对Se替代的Pb Te、Ge Te及Pb Te-Ge Te合金的物相、微观组织及热电性能的影响规律,优化它们的热电性能。。对Pb0.98-xMgxNa0.02Te0.5Se0.5(x=0,0.02,0.04,0.06,0.08,0.10)系列合金的研究表明:Se的替代增加了Mg的固溶度;合金的电阻率及Seebeck系数随Mg含量的增加先增大后减小,在x=0.06处达到最大值,而其热导率随Mg含量的增加先降低后升高,在x=0.04处达到最小值;最终,Mg掺杂量为x=0.04的合金样品在673 K时获得最高ZT值1.0,比未掺杂Mg合金在相同温度下的0.88高出13.6%。对Ge1-xMgxTe0.7Se0.3(x=0.04,0.07,0.10,0.12)系列合金的研究表明:Mg以析出Mg Se第二相形式存在,较少固溶进合金中;随着Mg含量的增加,合金电阻率增大,Seebeck系数变化不大,但热导率降低较多,最终,Mg掺杂量为0.12的合金样品在673K时获得最大热电优值0.60,比纯Ge Te在相同温度下的0.51高17%。对Ge0.75Pb0.2Sm0.03Te1-xSex(x=0,0.1,0.2,0.3,0.4,0.5,0.6)系列合金的研究表明:Se的替代增加了Pb在Ge Te固溶体中的固溶度;稀土元素Sm掺杂细化了调幅分解组织;随着Se含量的增加,合金电阻率上升,Seebeck系数也增加,并且热导率显著降低,最终,Se替代量x=0.5的合金具有最低的热导率0.78 W m-1 K-1(723 K)及最高热电优值ZT=1.5,比x=0的0.99高出51%。
[Abstract]:Pb Te,Ge Te is a medium temperature thermoelectric material with good performance. It has a wide application prospect in power generation field, and has important significance in energy saving and emission reduction, low carbon environmental protection. It can increase the solubility of Pb in Ge Te and improve the thermoelectric properties of the materials. In this work, three series of Pb0.98-xMgxNa0.02Te0.5Se0.5,Ge1-xMgxTe0.7Se0.3 and Ge0.75Pb0.2Sm0.03Te1-xSex alloy samples were prepared by melting, heat treatment, quenching and spark plasma sintering (SPS). In order to study the effect of Mg and Sm doping on the phase, microstructure and thermoelectric properties of Pb Te,Ge Te and Pb Te-Ge Te alloys replaced by Se, the thermoelectric properties of Pb Te,Ge Te and Pb Te-Ge Te alloys were optimized. A series of Pb0.98-xMgxNa0.02Te0.5Se0.5 alloys (0.02 / 0.02 / 0.04 / 0.06 / 0.08 / 0. 10) are studied. The results show that the substitution of Se increases the solution of Mg. The resistivity and Seebeck coefficient of the alloy first increased and then decreased with the increase of Mg content, and reached the maximum at x0. 06, while the thermal conductivity decreased first and then increased with the increase of Mg content, and reached the minimum value at x0. 04. In the end, the highest ZT value of the alloy with Mg doping amount of XG 0.04 is 1.0 at 673K, which is 13.6 higher than that of the undoped Mg alloy at the same temperature. The study on the Ge1-xMgxTe0.7Se0.3 (x _ (0.04) O _ (0.04) ~ (0.07) ~ (0.10) ~ (0.12) alloy shows that Mg exists in the form of precipitated second phase of Mg Se, and less solid solution is introduced into the alloy. With the increase of Mg content, the resistivity of the alloy increases, the Seebeck coefficient does not change much, but the thermal conductivity decreases more. Finally, the maximum thermoelectric excellent value of 0.60 is obtained at 673K when the content of Mg is 0.12. It is 17 times higher than that of pure Ge Te at the same temperature. A series of Ge0.75Pb0.2Sm0.03Te1-xSex alloys (xn00. 1 + 0. 2, 0. 3, 0. 4, 0. 50. 6) show that the substitution of Se increases the solution degree of Pb in Ge Te solid solution, and the Sm doping of rare earth element refines the structure of amplitude modulation decomposition. With the increase of Se content, the resistivity of the alloy increases, the Seebeck coefficient increases, and the thermal conductivity decreases significantly. The lowest thermal conductivity (0.78 W m ~ (-1) K ~ (-1) and the highest thermoelectric excellent value (ZT=1.5,) of the alloy with Se substitution x _ (0.5) are 51% higher than that of x _ (0) 0.99.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34

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