全球暖化為現今很重要的議題之一，所以提高能源轉換率及綠色能源之開發成為了能源發長的方向。然而，熱電材料本屬於綠色能源之一，同時又具有熱能以及電能互相轉換之性質，可將廢熱轉換為電能進而提升能源轉換率，是極具有潛能的材料。在熱電材料之中，Bi2Te3是最具代表性的常溫型熱電材料，其有著特殊的層狀結構，使導電性及導熱性具有方向性，主要應用於致冷效應，而在200℃以下具有0.8的zT值，並且不同摻雜或溫度具有n型及p型之轉換。主要透過摻雜微量的銅來調整Bi2Te3的電/熱的傳導性，而配置了一系列熱電合金。為了找尋性質更優異之材料及探討其特殊的熱電性質，須先完成相圖，從中了解其相區、反應溫度點、微結構、相穩定性…等相關資訊。
根據實驗方式建構Bi-Cu-Te三元系統之液相線投影圖以及250℃等溫橫截面圖，再透過Bridgman長晶法製備熱電合金進行熱電量測，探討不同摻雜對Bi2Te3合金之熱電性質的影響。發現摻雜Cu確實能有效降低電阻，其中(Bi2Te3)0.99(Cu2Te)0.01為最高p型而Bi2¬Cu0.01Te2.99為最高n型，zT值分別為1.2及1.7，Bi2¬Cu0.01Te2.99性質比文獻的Bi2Se0.3Te2.7高達200%，並發現具有再現能力及良好的熱穩定性。另外Bi2Cu0.1Te3有不受溫度影響得最高zT值，在應用上是更加有力的，其熱電優值平均為1.2。

Thermoelectric material (TE) could convert waste heat directly into electricity, and therefore it could pave the way toward the environmental sustainability. The layered-structure Bi2Te3, which crystallize in a rhombohedral symmetry, show anisotropic transport properties, and are the most well-established room-temperature TE materials. Herein we aim to tune the thermal/electrical transport properties of the Bi2Te3-based alloys, by incorporating minor amount of Cu, to form a series of Cu-doped Bi2Te3 alloys. The homogeneity regime, phase stability and microstructural evolution are elaborated by establishing the 523K isothermal section and liquidus projection of ternary Bi-Te-Cu system, using the thermally-equilibrated or solidified alloys. In addition, the TE properties of selective Cu-doped Bi2Te3 alloys that grown by the Bridgman method suggest that the small deviations in the starting compositions could lead to the huge the difference in the resultant TE performance. At 300 K, the highest peak zT for p-type ((Bi2Te3)0.99(Cu2Te)0.01) and n-type (Bi2¬Cu0.01Te2.99) Cu-containing Bi2Te3 are zT~1.2 and zT~1.7, respectively.

論文審定書 i
摘要 ii
Abstract iii
目錄 iv
圖目錄 vii
表目錄 xvi
第1章 前言 1
第2章 文獻回顧 7
2-1 熱電元件 7
2-1-1 Bi2Te3熱電材料 9
2-1-2 Bi2Te3摻雜元素之影響 11
2-2 相圖 13
2-2-1 Bi-Te二元系統相圖 14
2-2-2 Bi-Cu二元系統相圖 16
2-2-3 Cu-Te二元系統相圖 17
第3章 實驗方法 21
3-1 合金製備 22
3-2 相平衡熱處理 23
3-3 結構及組成分析 23
3-4 熱電性質 27
3-4-1 單軸式長晶 27
3-4-2 熱電性質分析 29
ZEM-3 29
LFA 30
Hall effect 30
第4章 結果與討論 31
4-1 Bi-Cu-Te三元系統之液相線投影圖 31
4-1-1 Te首要析出相區 36
4-1-2 Bi2Te3首要析出相區 39
4-1-3 Bi4Te5首要析出相區 48
4-1-4 BiTe首要析出相區 50
4-1-5 Eutectic相區 52
4-1-6 CuTe首要析出相區 53
4-1-7 Bi2Te3 /CuTe共析出相區 56
4-1-8 Cu1.38Te首要析出相區 57
4-1-9 Cu1.6Te首要析出相區 61
4-1-10 Cu2Te首要析出相 70
4-1-11 統整 86
4-2 Bi-Cu-Te三元系統之250℃等溫橫截面圖 88
4-2-1 Te + Bi2Te3 + CuTe三相區 93
4-2-2 Bi2Te3+ Cu1.4Te兩相區 98
4-2-3 Bi2Te3 + BiTe + Cu1.4Te三相區 100
4-2-4 BiTe + Cu2Te兩相區 103
4-2-5 BiTe + Bi4Te3 + Cu2Te三相區 106
4-2-6 Bi2Te + Cu2Te兩相區 110
4-2-7 Bi7Te3 + Cu2Te兩相區 113
4-2-8 Bi + Bi7Te3+ Cu2Te三相區 116
4-2-9 Bi + Cu + Cu2Te三相區 121
4-3 Bi-Cu-Te三元系統之熱電性質 127
4-3-1 Bi2Te3之熱電性質 133
4-3-2 常溫p型之熱電性質 137
4-3-3 常溫n型之熱電性質 153
第5章 總結 186
第6章 參考文獻 188
附錄 191
附錄（一）Bi2Se3摻雜元素之影響 191
附錄（二）二元相圖 192
Bi-Se二元系統相圖 192
Bi-Ge二元系統相圖 194
Ge-Se二元系統相圖 195
附錄（三）Bi-Ge-Se三元系統之液相線投影圖 199
Bi2Se3首要析出相區 204
玻璃態析出相區 208
A首要析出相區 213
B首要析出相區 215
C首要析出相區 218
GeSe首要析出相區 223
Bi6Se7首要析出相區 228
Ge首要析出相區 229
參考文獻 238

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