P型熱電材料AgSb1-xMxTe2 (M = Bi, In, Sn)其相組成、奈米結構和熱電特性之研究

Phase compositions, nanostructures and thermoelectric properties in the p-type materials AgSb1-xMxTe2 (M = Bi, In and Sn)

沐瑞曼(Mohanraman, Rajeshkumar)

指導教授 ： 陳洋元 ； 李志浩

國立清華大學/原子科學院/工程與系統科學系/博士(2015年)

摘要

One type of energy conversion technology that has gained renewed attention is thermoelectric energy conversion, where heat is converted directly into electricity using a class of materials known as thermoelectric materials. Thermoelectric (TE) materials are becoming increasingly important in the field of electricity generation and environmentally friendly refrigeration devices. AgSbTe2 has been firmly established as a potential TE material because of its relatively low thermal conductivity (0.6 – 0.7 Wm-1K-1). AgSbTe2 is widely identified as a disordered NaCl type (Fm-3m) where Ag and Sb randomly occupy the Na site. Doping is a potential approach to optimize the thermoelectric properties of p-type AgSbTe2 by reducing its thermal conductivity and adjusting its carrier concentration. In this study, Sb3+ was substituted with Bi3+, In3+ and Sn2+ in p-type Ag(Sb1-xMx)Te2 systems to optimize the charge-carrier concentration and simultaneously reduce lattice thermal conductivity by enhancing phonon scattering through the combined effects of lattice defects and the presence of nanoscale microstructures dispersed in the matrix. As a result the highest TE figure of merit ZT = 1.35, 1.1 and 1.04 were obtained for AgSb0.93In0.07Te2, AgSb0.97Sn0.03Te2 and AgSb0.957Bi0.05Te2 samples at 650 K, 600 K and 570 K respectively. These results indicate that doping with Bi, In and Sn is an effective method to enhance the TE performance of p-type AgSbTe2 with ZT = 0.9.

關鍵字

熱電 ； 參雜 ； 優質係數

並列摘要

熱電能量的轉換是一種利用熱電材料，熱可以直接轉變成電，而這種形式的能源轉換技術已經成為能源轉換上全新的焦點。 在發電和環保致冷設備的領域中熱電材料變得越來越重要。 由於銀銻鍗擁有相對低的熱導率(0.6 – 0.7 Wm-1K-1)使得這種材料被認為是有潛力的熱電材料。 銀銻鍗被認定屬於無序的氯化鈉型(Fm-3m)，銀和銻隨機分佈在鈉位置。 在P型銀銻鍗中的參雜效應是藉由減少熱導性和調整載子濃度以提升此材料熱電特性並使其最佳化的方法。 在這篇研究中，在P型Ag(Sb1-xMx)Te2 系統中Sb3+ 被Bi3+、 In3+ 和 Sn2+ 取代，藉由結合晶格缺陷的效應以及材料中的奈米結構，進而增加聲子散射，為了使電荷載子的濃度優化並同時使晶格熱導性減少。 結果我們分別從AgSb0.93In0.07Te2, AgSb0.97Sn0.03Te2 和AgSb0.957Bi0.05Te2 樣品中得到最高的熱電參數 ZT = 1.35, 1.1 和1.04. 這些結果指出參雜鉍，銦和錫是一個有效的方法使P型AgSbTe2熱電性能提升。

並列關鍵字

thermoelectric ； doping ； figure of merit

參考文獻

5. T. M. Tritt, ed., Recent Trends in Thermoelectric Materials Research, in Semiconductors and Semimetals, Academic Press, San Diego, 2001, vol. 69–71.

8. H. J. Goldsmid, Thermoelectric Refrigeration, Plenum Press, New York 1964.

10. R. Venkatasubramanian et al., Nature., 2001, 413, 597.

12. Matsubara, K. in International Conference on Thermoelectrics 2002, 418–423.

13. C. Wood, Rep. Prog. Phys., 1988, 51, 459.