能源危機是全球所面臨的最大問題之一，開發高效率的綠色能源材料亦蔚為熱潮。熱電材料和熱電元件可直接將熱能轉化為電能，因此吸引大量研究投入，尤其是在廢熱回收(waste heat recovery)中的應用。從文獻上得知，在所有類型的熱電材料中，黃銅礦結構(chalcopyrite structure)的CuGaTe2為中高溫熱電材料中一極具發展潛力之候選人，其在650℃擁有極佳的熱電性質(zT≈1.4)。相圖(phase diagram)為材料的基礎知識，對相變化和微結構演變提供重要資訊。然而，文獻上對於相穩定性，金相(microstructure)演進、晶體結構和三元合金Cu-Ga-Te的熱電性質之間的相關性非常有限，留下較大的空間來進一步的探索。因此，這項研究計劃致力於建立Cu-Ga-Te的三元相圖，並以實驗方法確定三元相 CuGaTe2 於高溫下的同質性範圍(homogeneity region)。本研究的工作包括：(1)以實驗建構Cu-Ga-Te三元系統650℃之等溫橫截面圖、(2)以實驗建構Cu-Ga-Te三元系統之液相線投影圖、(3)選定非化學計量比組成之CuGaTe2之三元合金，進行熱電性質量測及討論、(4)在CuGaTe2中參雜第四元素Ge，並量測其熱電性質及討論。
由本研究結果可知，CuGaTe2三元合金可以穩定存在於650℃，且擁有一定之固溶度(25.0 at.%-30.0 at.%Cu及48.0 at.%-53.0 at.%Te)，在650℃等溫橫截面圖中包含一個單相區、十個三相區及十二個兩相區；各相組成分別於實驗中確立。液相線投影圖由實驗分析，總共存在十六個首要析出相，以及一個互融間隙，並由微熱差分析儀測量不變點溫度。在475℃時，多晶Bridgman長晶方法合金#C(Cu25Ga26Te49)表現最高之zT值(zT~0.6)，並從金相關係探討其熱電性質差異。

To cope with the globally increasing energy demands, researchers are eager to develop high-efficiency sustainable energy resources. Thermoelectric materials and devices, which can convert thermal energy into electricity directly, have attracted intensive interest in the application of waste heat recovery. Among all types of thermoelectric materials, the Chalcopyrite-structure CuGaTe2 has been viewed as a promising candidate for use of thermoelectric generator due to its high figure-of-merit (zT~1.4) at temperature higher than 900 K. Phase equilibrium is a fundamental knowledge and is useful for understanding of the phase transformation and microstructure evolution, which are believed to effectively alter the materials’ thermoelectric properties. Nevertheless, only limited information regarding the correlation between the phase stability and microstructure of ternary Cu-Ga-Te is available, leaving a large space open for furthering exploration.
Herein the 650 ℃ isothermal section and the liquidus projection of ternary Cu-Ga-Te system are determined; various ternary Cu-Ga-Te alloys are either thermally-equilibrated at 650 ℃ for 30 days to clarify the homogeneity range of ternary CuGaTe2 phase, which is determined to be 48.0 at%-53.0at%Te and 25.0at%-30.0at%Cu.There are 16 primary solidification phase and one misbility-gap in ternary Cu-Ga-Te liquidus projection.The temperature of invariant reaction was measured by DTA-7.Alloy#C show the highest zT value in CuGaTe2 system at 750K.

序 i
致謝 iii
摘要 iv
Abstract v
目錄 vi
圖目錄 ix
表目錄 xxii
一、前言 1
二、文獻回顧 9
2-1熱電元件 9
2-1-1 CuGaTe2熱電材料 11
2-2相圖 16
2-2-1 Cu-Te二元系統相圖 18
2-2-2 Cu-Ga二元系統相圖 20
2-2-3 Ga-Te二元系統相圖 22
2-2-4 三元Cu-Ga-Te系統等值剖面圖 24
三、實驗方法 26
3-1 三元Cu-Ga-Te系統之650℃等溫橫截面圖 26
3-1-1 合金配製 26
3-1-2 樣品熱處理 27
3-1-3 樣品金相及結構分析 27
3-2 三元Cu-Ga-Te系統之液相線投影圖 28
3-2-1 合金配製 28
3-2-2 樣品熱分析 28
3-2-3 樣品金相及結構分析 28
3-3 三元Cu-Ga-Te系統之熱電性質 29
3-3-1 合金配製 29
3-3-2 Bridgman長晶 29
3-3-3 熱電性質量測 30
四、結果與討論 31
4-1 三元Cu-Ga-Te系統650℃等溫橫截面圖 31
4-1-1 CuGaTe2-Liquid兩相區 34
4-1-2 CuGaTe2-Ga2Te3-Liquid三相區 42
4-1-3 CuGaTe2-Ga2Te3兩相區 44
4-1-4 CuGaTe2-GaTe兩相區 47
4-1-5 CuGaTe2-GaTe-Cu9Ga4三相區 49
4-1-6 GaTe-Cu9Ga4兩相區 54
4-1-7 GaTe+Cu9Ga4+Liquid三相區 55
4-1-8 GaTe-Liquid兩相區 58
4-1-9 CuGaTe2-Cu9Ga4兩相區 63
4-1-10 CuGaTe2-Cu9Ga4-Cu2Te三相區 65
4-1-11 CuGaTe2-Liquid- Cu1.6Te三相區 69
4-1-12 CuGaTe2-Cu1.6Te-Cu2Te三相區 71
4-1-13 Cu3Ga-Gu2Te兩相區 73
4-1-14 CuGaTe2單相區 74
4-1-15 三元Cu-Ga-Te系統650℃等溫橫截面圖總結 76
4-2 三元Cu-Ga-Te系統液相線投影圖 83
4-2-1 Ga2Te3首要析出相區 87
4-2-2 CuGaTe2首要析出相區 93
4-2-3 GaTe首要析出相區 108
4-2-4 Cu9Ga4首要析出相區 117
4-2-5 Cu3Ga首要析出相 138
4-2-6 三元Cu-Ga-Te系統液相投影圖之互溶間隙 143
4-2-7 三元Cu-Ga-Te系統熱分析 150
4-2-8 三元Cu-Ga-Te系統液相線投影圖總結 163
4-3 三元Cu-Ga-Te系統之熱電性質 168
4-3-1多晶CuGaTe2長晶方向之熱電性質探討 171
4-3-2 多晶Cu1+xGaTe2-x(X=0、0.04、0.08、0.12)合金之熱電性質探討 173
4-3-3 多晶CuGa1+xTe2-x(0.04、0.08)合金之熱電性質探討 181
4-3-4 多晶合金Cu29+XGa22Te49-X(X=0、1)之熱電性質探討 190
4-3-5 淬冷樣品之合金# L33熱電性質探討 196
4-3-6參雜GeTe之CuGaTe2熱電性質探討 202
五、結論 207
六、參考文獻 210

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