熱電材料具有熱電轉換特性，主要應用於廢熱回收，在能源短缺及環保意識抬頭的現今備受關注。熱電元件之結構通常包含陣列熱電半導體，連接Cu導電基板以組成元件，因此熱電元件中存在許多接點。CoSb3是具代表性之中溫型熱電材料，於450-600oC有優異之熱電表現，Ag-Cu銲料合金是個適合的選擇，為了避免銲料擴散至熱電材料，需要在銲料與熱電材料之間加上一層阻障層。因此，熱電元件中接點為「熱電材料/障層/銲料合金」的型式。接點之界面反應與元件之可靠度與穩定性有極大的關係。本研究進行CoSb3於450oC及600oC之界面反應共有六組：Ag-Cu/CoSb3、Ag-Cu/Co、Co/CoSb3、Ag-Cu/Co/CoSb3、Ag-Cu/Ni/CoSb3以及Ti/CoSb3；相圖部分為Ag-Cu-Co之600oC等溫橫截面圖。Ag-Cu/CoSb3之反應劇烈，當兩者液固接合時，已有125m之反應層生成，將反應偶於600oC進行3天之熱處理，CoSb3熱電材料已完全被消耗而生成CoSb相，藉此結果可知，阻障層之引入是必須的。Ag-Cu/Co之界面反應進行於450oC以及600oC，可觀察到富Cu相之堆積，當於600oC之反應40天時，其反應層厚度約為5m。Co/CoSb3之反應偶以電鍍之方式製備，電鍍上之Co層厚度約為100m，當於450oC反應44天時，可在界面上觀察到CoSb及CoSb2相，厚度分別為18m及4m。將反應偶於600oC進行42天之界面反應，可觀察到CoSb及CoSb2相，其厚度分別為125及82m。Ag-Cu/Co/CoSb3之界面反應於600oC進行42天，Co層之厚度由原本之100m反應剩下30m，當反應持續進行，Co層終究被消耗殆盡。而Ag-Cu/Ni/CoSb3之界面反應於600oC進行12天，介金屬相之厚度約為175m，與Ag-Cu/Co/CoSb3之界面反應結果進行比較，Ni與CoSb3之反應性較強，不適合為CoSb3熱電元件之障層選擇。Ti/CoSb3之反應偶以濺鍍之方式製備，Ti層之厚度約為6m，當於450oC反應21天時，可以觀察到三層介金屬相之生成，分別是TiSb、TiSb2以及TiCoSb，而總厚度為3m。將Co/CoSb3、Ni/CoSb3以及Ti/CoSb3之反應性進行比較，可以發現Ti與CoSb3之反應性最低，對於CoSb3之熱電元件，Ti將是一個較理想的擴散阻障層。Ag-Cu-Co 600oC 等溫橫截面圖已經利用實驗及CALPHAD進行建構，此相圖中存在一個三相區:Ag+Cu+Co，並沒有發現三元相之存在。本研究成果對中溫熱電元件開發具重要參考價值，亦提供了相關材料系統之重要基礎瞭解。

Thermoelectric materials can directly convert heat and electricity, and are promising in the usage of waste heat recovery. Due to the energy crisis concerns and environmental issues, thermoelectric materials have been intensively investigated recently. Thermoelectric modules usually consist of areas of thermoelectric semiconductors connected together to Cu plate. Thus, there are many solder/braze joints in the thermoelectric modules. The CoSb3 compound is a skutterudite compound with good thermoelectric properties especially in the mid-temperature range, i.e. 450-600oC. The suitable Pb-free solder for application in mid-temperature range is Ag-Cu eutectic alloy. In order to prevent the solder/braze diffusion into the thermoelectric materials, diffusion barrier layers, Co, Ni and Ti, are introduced between solder/braze and substrates. Therefore, the solder joints in the thermoelectric modules are “thermoelectric material/barrier layer/solder alloy”. The interfacial reactions between various materials at the joints are crucial to the properties and the reliabilities of thermoelectric modules.This study plans to investigate the interfacial reactions at the joints in the mid-temperature thermoelectric modules and the phase diagram of their related materials system. The interfacial reactions studies include the following six systems: Ag-Cu/CoSb3, Ag-Cu/Co, Co/CoSb3, Ag-Cu/Co/CoSb3, Ag-Cu/Ni/CoSb3, and Ti/CoSb3. Phase diagrams studies focus on Ag-Cu-Co 600oC isothermal section.The thickness of reaction layer in quenched Ag-Cu/CoSb3 diffusion couple is about 125m. After the heat treatment at 600oC for 3 days, the CoSb3 substrates completely transform into CoSb phase. It is thus very clear that a barrier layer is needed to be introduced between CoSb3 substrates and Ag-Cu alloys. Cu-rich phase is present in the reaction layer of Ag-Cu/Co diffusion couples heat-treated at 450oC and 600oC, and the maximum thickness of the reaction layer is about 5m at 600oC for 40 days. The Co/CoSb3 diffusion couples are prepared with electroplating, and the thickness of Co layer is about 100m. Two IMCs(CoSb, CoSb2) are observed in the reacted couples at 450oC for 44 days. The thickness of CoSb is 18m and the CoSb2 is 4m. In the reacted couples at 600oC for 42 days, the thicknesses of these two layers are 125m and 82m, respectively. Thethickness of Co layer reduces from 100m to 30m in the Ag-Cu/Co/CoSb3 reacted couples at 600oC for 42 days. As the aging time increases, the CoSb3 keep reacting with Co. Eventually; Co will be consumed completely, exposing Ag-Cu/CoSb3. Co layer is not a suitable candidate for barrier layer. The thickness of IMCs is about 175m in the reacted Ag-Cu/Ni/CoSb3 couples at 600oC for 12 days. Compare the results of Ag-Cu/Co/CoSb3, Ni is not a suitrbla barrier layer candidate. Ti/CoSb3 diffusion couples are prepared with sputter, and the thickness of Ti layer is about 6m. Three IMCs(TiSb, TiSb2, TiCoSb) are observed at the reacted couples at 450oC for 21 days, the total thickness of IMCs are 3m. Compared to Co/CoSb3 and Ni/CoSb3, the consumption of diffusion barrier layer by CoSb3 in Ti/CoSb3 is the least. Ti can be a suitable layer for CoSb3-based thermoelectric modules. The 600oC isothermal section of Ag-Cu-Co ternary system has been determined by experiment and calculation. There is one tie-triangle, Ag+Cu+Co, in the Ag-Cu-Co system at 600oC, and no ternary compound is found.The results of this study are valuable for the development and reliability evaluations of thermoelectric modules. Furthermore, the phase diagrams and interfacial reaction results provide fundamentally important knowledge of the related materials systems.

目錄
誌謝 I
摘要 II
Abstract IV
目錄 VI
圖目錄 VIII
表目錄 XII
一、前言 1
1.1 熱電材料介紹 1
1.2 CoSb3 熱電材料 6
1.3 熱電元件接點 7
1.4 界面反應與材料系統 8
二、文獻回顧 9
2.1 材料系統平衡相圖 9
2.1-1二元系統平衡相圖 11
2.1-2三元系統相平衡圖 26
2.2 界面反應 33
2.2-1 CoSb3熱電材料製備 33
2.2-2 Ag-Cu/Co界面反應 34
2.2-3 Ag-Cu/Ni界面反應 35
2.2-4 Ag-Cu/Ti界面反應 36
2.2-5 Co/CoSb3界面反應 38
2.2-6 Ni/CoSb3界面反應 40
2.2-7 Ti/CoSb3界面反應 43
三、研究方法 49
3.1 Ag-Cu-Co 三元系統相平衡圖 49
3.2 CoSb3基材製備及熱電性質量測 50
3.3 Ag-Cu銲料對CoSb3之界面反應 50
3.4 Ag-Cu銲料/Co障層/CoSb3熱電材料之界面反應 51
3.5 Ag-Cu銲料/Ni障層/CoSb3熱電材料之界面反應 52
3.6 Ag-Cu銲料/Ti障層/CoSb3熱電材料之界面反應 52
四、結果與討論 53
4.1 Ag-Cu-Co 三元系統相平衡圖 53
4.2 CoSb3熱電材料製備及熱電性質 56
4.3 Ag-Cu銲料對CoSb3之界面反應 61
4.4 Ag-Cu銲料/Co障層/CoSb3熱電材料之界面反應 64
4.5 Ag-Cu銲料/Ni障層/CoSb3熱電材料之界面反應 92
4.6 Ag-Cu銲料/Ti障層/CoSb3熱電材料之界面反應 98
4.7 Ag-Cu銲料/(Co, Ni, Ti)障層界面反應之比較 104
4.8 (Co, Ni, Ti)障層/CoSb3熱電材料界面反應比較 106
五、結論 109
5.1 Ag-Cu-Co 三元系統相平衡圖 109
5.2 CoSb3熱電材料製備及熱電性質 109
5.3 Ag-Cu銲料對CoSb3之界面反應 109
5.4 Ag-Cu銲料/Co障層/CoSb3熱電材料之界面反應 109
5.5 Ag-Cu銲料/Ni障層/CoSb3熱電材料之界面反應 110
5.6 Ag-Cu銲料/Ti障層/CoSb3熱電材料之界面反應 111
5.7 Ag-Cu銲料/(Co, Ni, Ti)障層界面反應之比較 111
5.8 (Co, Ni, Ti)障層/CoSb3熱電材料界面反應比較 112
六、參考文獻 113

1. L. L. N. Laboratory. Estimated U. S. Energy Consumption in 2015. 2015.
2. J. T. Jarman, E. E. Khalil, and E. Khalaf, "Energy Analyses of Thermoelectric Renewable Energy Sources", Open Journal of Energy Efficiency, Vol. 2, pp. 143-153, (2013).
3. G. Chen, M. S. Dresselhaus, G. Dresselhaus, J. P. Fleurial, and T. Caillat, "Recent developments in thermoelectric materials", Int. Mater. Rev., Vol. 48, No. 1, pp. 45-66, (2003).
4. T. M. Tritt, H. Böttner, and L. Chen, "Thermoelectric: Direct Solar Thermal Energy Conversion ", MRS Bulletin, Vol. 33, pp. 366-368, (2008).
5. M. S. El-Genk, H. H. Saber, and T. Caillat, "Efficient segmented thermoelectric unicouples for space power applications", Energy Convers. Manage., Vol. 44, No. 11, pp. 1755-1772, (2003).
6. A. J. Minnich, M. S. Dresselhaus, Z. F. Ren, and G. Chen, "Bulk nanostructured thermoelectric materials: current research and future prospects", Energy Environ. Sci., Vol. 2, pp. 466-479, (2009).
7. C. Chubilleau, B. Lenoir, P. Masschelein, A. Dauscher, C. Candolfi, E. Guilmeau, and C. Godart, "High temperature thermoelectric properties of CoSb3 skutterudites with PbTe inclusions", J. Mater. Sci., Vol. 48, No. 7, pp. 2761-2766, (2013).
8. Y. Kawaharada, K. Kurosaki, M. Uno, and S. Yamanaka, "Thermoelectric properties of CoSb3", J. Alloys Compd., Vol. 315, No. 1-2, pp. 193-197, (2001).
9. P. X. Lu, F. Wu, H. L. Han, Q. Wang, Z. G. Shen, and X. Hu, "Thermoelectric properties of rare earths filled CoSb3 based nanostructure skutterudite", J. Alloys Compd., Vol. 505, No. 1, pp. 255-258, (2010).
10. G. J. Snyder and E. S. Toberer, "Complex thermoelectric materials", Nature Materials, Vol. 7, pp. 105-114, (2008).
11. H. N. Keller, "Solder Connections with a Ni Barrier", IEEE Trans. CHMT, Vol. 7, pp. 105-114, (1986).
12. T. Y. Lin, C. N. Liao, and A. T. Wu, "Evaluation of Diffusion Barrier Between Lead-Free Solder Systems and Thermoelectric Materials", J. Electron. Mater., Vol. 41, No. 1, pp. 153-158, (2012).
13. F. N. Rhines, Phase Diagrams in Metallurgy. 1956, New York: McGraw and Hall.
14. D. R. F. West, Ternary Equilibrium Diagrams 1982, New York: Chapman and Hall
15. P. R. Subramanian and J. H. Perepezko, "The Ag-Cu (Silver-Copper) system", J. Phase Equilib., Vol. 14, No. 1, pp. 62-75, (1983).
16. X. J. Liu, F. Gao, C. P. Wang, and K. Ishida, "Thermodynamic Assessments of the Ag-Ni Binary and Ag-Cu-Ni Ternary Systems", J. Electron. Mater., Vol. 37, No. 2, pp. 210-217, (2008).
17. J. Bernardini, A. Combe-Brun, and J. Cabane, "Diffusion et solubilite du cobalt dans l'argent", Scripta Metallurgica, Vol. 4, No. 12, pp. 985-989, (1970).
18. B. P. Burylev and V. D. Ivanova, "The Region of Immiscibility on Phase Diagrams for Germanium-Silver-Metal Systems (Metal= Manganese, Iron, Cobalt or Nickel)", Russ. J. Phys. Chem., Vol. 50, pp. 1286-1288, (1976).
19. G. Tammann and W. Oelsen, "Dependence of concentration of saturated mixed crystals on temperature", Z. Anorg. Allgem. Chem, Vol. 186, pp. 257-288, (1930).
20. W. J. Zhu, H. S. Liu, J. S. Wang, H. Q. Dong, and Z. P. Jin, "Thermodynamic assessment of the Sn-Ag-Co system and solidification simulation of the ternary alloy", J. Alloys Compd., Vol. 481, No. 1, pp. 503-508, (2009).
21. U. Hashimoto, "The equilibrium diagram of the Co-Cu system", J. Jap. Inst. Metals, Vol. 1, pp. 19-26, (1937).
22. M. Hasebe and T. Nishizawa, "Calculation of phase diagrams of the iron-copper and cobalt-copper systems", Calphad, Vol. 4, No. 2, pp. 83-100, (1980).
23. T. Nishizawa and K. Ishida, "The Co-Cu (Cobalt-Copper) system", J. Phase Equilib., Vol. 5, No. 2, pp. 161-165, (1984).
24. Y. Yu, X. Liu, Z. Jiang, C. Wang, R. Kainuma, and K. Ishida, "Thermodynamics and liquid phase separation in the Cu-Co-Nb ternary alloys", J. Mater. Res., Vol. 25, No. 9, pp. 1706-1717, (2010).
25. M. Singleton and P. Nash, "The Ag-Ni (Silver-Nickel) system", J. Phase Equilib., Vol. 8, No. 2, pp. 119-121, (1987).
26. E. Schurmann and E. Schultz, "Untersuchengen zum Verlauf der Liquidus und Solidus linien in den Systemen Kupfer-Mangan und Kupfer-Nickel", Z. Metallkd, Vol. 62, pp. 758-762, (1971).
27. B. D. Bastow and D. H. Kirkwood, "Solid/liquid equilibrium in the Copper-Nickel-Tin system determined by microprobe analysis", J. Inst. Met., Vol. 99, No. 9, pp. 277-283, (1971).
28. D. J. Chakrabarti, D. E. Laughlin, S. W. Chen, and Y. A. Chang, Binary Alloy Phase Diagrams, Second Edition, ed. T.B. Massalski. Vol. 2. 1990, Materials Park, Ohio: Materials Information Society.
29. H. K. Adenstedt and W. R. F. Jr, "The Tentative Titanium-silver Binary System", WADC Tech. Rept., Vol. 1, pp. 53-109, (1953).
30. H. W. Worner, "The structure of titanium-silver alloys in the range 0-30 at.-% silver", J. Inst. Metals, Vol. 82, pp. 222-226, (1954).
31. M. K. McQuillan, "A Study of the Titanium-Silver System", J. Inst. Met., Vol. 88, No. 5, pp. 235-239, (1960).
32. J. L. Murray and K. J. Bhansali, "The Ag-Ti (Silver-Titanium) system", J. Phase Equilib., Vol. 4, No. 2, pp. 178-183, (1983).
33. J. L. Murray, "The Cu-Ti (Copper-Titanium) system", Bull. Alloy Phase Diagr., Vol. 4, No. 1, pp. 81-95, (1983).
34. H. Okamoto, "Co-Sb (cobalt-antimony)", J. Phase Equilib., Vol. 12, No. 2, pp. 244-245, (1991).
35. U. Haschimoto, "コバルトの同素變態と附加元素との關係に就て", J. Japan. Inst. Met., Vol. 1, No. 5, pp. 177-190, (1937).
36. Y. Zhang, C. Li, Z. Du, and T. Geng, "The thermodynamic assessment of the Co-Sb system", Calphad, Vol. 32, No. 1, pp. 56-63, (2008).
37. T. Nishizawa and K. Ishida, "The Co-Ni (Cobalt-Nickel) system", Bull. Alloy Phase Diagr., Vol. 4, No. 4, pp. 390-395, (1983).
38. Y. Zhang, C. Li, Z. Du, C. Guo, and J. C. Tedenac, "The thermodynamic assessment of the ternary Co-Ni-Sb system", Calphad, Vol. 33, No. 2, pp. 405-414, (2009).
39. P. Feschotte and D. Lorin, "The Binary-Systems Fe-Sb, Co-Sb and Ni-Sb", Journal of the Less-Common Metals, Vol. 155, No. 2, pp. 255-269, (1989).
40. G. Cha, S. Lee, and P. Nash, The Sb-Ni system. Phase diagrams of binary nickel alloys. 1991, Materials Park, OH: ASM International.
41. Y. Zhang, C. Li, Z. Du, and C. Guo, "A thermodynamic assessment of Ni-Sb system", Calphad, Vol. 32, No. 2, pp. 378-388, (2008).
42. J. L. Murray, "The Co-Ti (Cobalt-Titanium) system", Bull. Alloy Phase Diagr., Vol. 3, No. 1, pp. 74-85, (1982).
43. G. Cacciamani, R. Ferro, I. Ansara, and N. Dupin, "Thermodynamic modelling of the Co-Ti system", Intermetallics, Vol. 8, No. 3, pp. 213-222, (2000).
44. J. L. Murray, Sb-Ti (Antimony-Titanium). Binary Alloy Phase Diagrams II Ed., ed. T.B. Massalski. Vol. 3. 1990.
45. H.-T. Luo and S.-W. Chen, "Phase equilibria of the ternary Ag-Cu-Ni system and the interfacial reactions in the Ag-Cu/Ni couples", J. Mater. Sci., Vol. 31, No. 19, pp. 5059-5067, (1996).
46. O. Dezellus, R. Arroyave, and S. G. Fries, "Thermodynamic modelling of the Ag-Cu-Ti ternary system", Int. J. Mater. Res., Vol. 102, No. 3, pp. 286-297, (2011).
47. Y. Stadnyk, L. Romaka, A. Horyn, A. Tkachuk, Y. Gorelenko, and P. Rogl, "Isothermal sections of the Ti-Co-Sn and Ti-Co-Sb systems", J. Alloys Compd., Vol. 387, No. 1, pp. 251-255, (2005).
48. J. W. Sharp, E. C. Jones, R. K. Williams, P. M. Martin, and B. C. Sales, "Thermoelectric properties of CoSb3 and related alloys", J. Appl. Phys., Vol. 78, No. 2, pp. 1013-1018, (1995).
49. T. Caillat, A. Borshchevsky, and J. P. Fleurial, "Properties of single crystalline semiconducting CoSb3", J. Appl. Phys., Vol. 80, No. 8, pp. 4442-4449, (1996).
50. J. X. Zhang, Q. M. Lu, K. G. Liu, L. Zhang, and M. L. Zhou, "Synthesis and thermoelectric properties of CoSb3 compounds by spark plasma sintering", Mater. Lett., Vol. 58, No. 14, pp. 1981-1984, (2004).
51. S. W. Chen, "Interfacial reactions in the liquid (Ag, Cu)Ni diffusion couples", Mater. Chem. Phys., Vol. 33, No. 3, pp. 271-276, (1993).
52. J. Andrieux, O. Dezellus, F. Bosselet, and J. C. Viala, "Low-Temperature Interface Reaction Between Titanium and the Eutectic Silver-Copper Brazing Alloy", Journal of Phase Equilibria and Diffusion, Vol. 30, No. 1, pp. 40-45, (2008).
53. T. Shimozaki, K.-s. Kim, T. Iwata, T. Okino, and C.-G. Lee, "Structure of Thermoelectric Material CoSb3 Formed by Reactive Diffusion", Mater. Trans., Vol. 43, No. 10, pp. 2609-2616, (2002).
54. S. G. Jeon, H. S. Shin, J. Yu, and J. Y. Song, "Diffusion-controlled solid-state formation of CoSb phase from Co/Sb-multilayered nanowires", J. Nanomater., Vol. 2012, pp. 4, (2012).
55. W. A. Chen, S. W. Chen, S. M. Tseng, H. W. Hsiao, Y. Y. Chen, G. J. Snyder, and Y. Tang, "Interfacial reactions in Ni/CoSb3 couples at 450°C", J. Alloys Compd., Vol. 632, pp. 500-504, (2015).
56. J. Fan, L. Chen, S. Bai, and X. Shi, "Joining of Mo to CoSb3 by spark plasma sintering by inserting a Ti interlayer", Mater. Lett., Vol. 58, No. 30, pp. 3876-3878, (2004).
57. X. Li, L. Chen, J. Fan, and S. Bai. Mo/Ti/CoSb3 joining technology for CoSb3 based materials. in Thermoelectrics, 2005. ICT 2005. 24th International Conference on. 2005. IEEE.
58. D. Zhao, X. Li, L. He, W. Jiang, and L. Chen, "Interfacial evolution behavior and reliability evaluation of CoSb3/Ti/Mo–Cu thermoelectric joints during accelerated thermal aging", J. Alloys Compd., Vol. 477, No. 1-2, pp. 425-431, (2009).
59. D. Zhao, H. Geng, and L. Chen, "Microstructure contact studies for skutterudite thermoelectric devices", Int. J. Appl. Ceram. Technol., Vol. 9, No. 4, pp. 733-741, (2012).
60. W. S. Liu, B. P. Zhang, J. F. Li, and L. D. Zhao, "Thermoelectric property of fine-grained CoSb3 skutterudite compound fabricated by mechanical alloying and spark plasma sintering", J. Phys. D Appl. Phys., Vol. 40, No. 2, pp. 566, (2007).