碲化鍺系列化合物由於在中高溫下的優異傳輸性能和其相轉變引發的能帶收斂效應而在熱電研究中受到廣泛關注。但碲化鍺本身過高的電洞濃度使其熱電轉換效率低落，藉由摻雜與合金化工程改善其晶體缺陷和能帶結構，可以有效增加碲化鍺系列化合物的熱電性能。本研究透過電流輔助燒結Ge0.87Pb0.13Te (GPT)與Ge0.87Pb0.13Te 添加 3 mol% Sb2Te3(GPST+3)試片研究微結構演變、析出物和傳導性質的影響。與熱壓的GPT試片相比，電流輔助燒結的GPT試片更加緻密(理論密度的96％)，且EDS元素分析顯示，電流輔助燒結的GPT試片中主相的鉛含量(6.5 at%)明顯比在熱壓GPT試片中的鉛含量(4.9 at%)高。此外本研究在GPT試片中摻入3 mol%的Sb2Te3，進一步調整GPT系統的缺陷濃度和傳輸性質。在室溫下，GPST+3 試片的功率因子可以達到11.82μW/ cm·K2，此功率因子的提升來自銻摻雜引起的電洞濃度改變。最後GPST+3試片在高溫量測下的峰值zT在600 K的溫度下達到1.3且平均zT 為 1.05。本研究提供一系統性的研究探討晶體缺陷和微觀結構如何影響GPT系列化合物的熱電性能與微結構。

GeTe-based compounds have received intensive attention in thermoelectric research society due to their phase transformation behavior and promising transport properties in the mid-temperature regime. Generally, the thermoelectric properties of GeTe-based compounds can be improved by engineering crystal defects and electronic band structure through doping and alloying. In this study, Ge0.87Pb0.13Te (GPT) compounds were fabricated by a combined thermal and electrical sintering approach. The effects of thermal history and electrical stressing on microstructure evolution, precipitation and transport properties of Ge0.87Pb0.13Te and Ge0.87Pb0.13Sb0.06Te1.09 (GPST+3) are investigated. Compared to typical hot-pressed samples, the electrical sintered sample is more compacted (96% of theoretical density). The elemental analysis suggests that the Pb content in the electrically sintered GPT matrix is increased (6.5 at.%) compared to the hot-pressed GPT (4.9 at.%). Moreover, 3 mol% Sb2Te3 was added into the GPT to further tailor defects and transport properties of the GPT system. The GPST+3 demonstrates a high power factor of 11.82 μW/cmK2 at room temperature. The high temperature thermoelectric measurements reveal that the GPST+3 sample can reach zT = 1.3 at 600 K with a zTaverage of 1.05. How the crystal defect concentration and microstructure evolution affect the thermoelectric properties of the GPT systems are systematically studied.

壹、緒論 1
1.1 研究背景 1
1.2 研究動機 5
貳、文獻回顧 7
2.1 碲化鍺系化合物 9
2.1.1 碲化鍺的晶體結構 9
2.1.2 碲化鍺的電子結構 10
2.1.3 碲化鍺之內部缺陷 13
2.2 碲化鍺鉛合金材料 15
2.2.1碲化鍺鉛合金之缺陷機制 16
2.2.2 GeTe-PbTe之相圖 17
2.3 銻摻雜碲化鍺鉛合金(Sb doped GPT) 19
2.3.1 銻摻雜碲化鍺鉛系列化合物缺陷機制 19
2.3.2 銻摻雜對於相轉變影響 20
2.4 火花電漿燒結製程材料對微結構影響 21
參、實驗流程及量測分析方法 24
3.1 試片製備 26
3.2 量測方法 27
3.2.1 Seebeck係數與四點式電阻量測 27
3.2.2 霍爾效應量測 29
3.2.3 熱傳導係數量測 31
3.2.4 表面形貌、析出物、成份分析 33
3.2.5 X光繞射分析 34
3.2.6 XRD Rietveld 分析 (XRD Rietveld Refinement Analysis) 34
3.2.7 熱重分析儀 35
肆、研究結果與討論 36
4.1電流輔助熱壓燒結GPT試片 36
4.1.1熱壓製程對GPT試片性能和組成的影響 36
4.1.2 GPT試片熱電傳輸特性 39
4.2 Sb元素摻雜對GPT系統的影響 47
4.2.1 GPST熔煉合金、塊材分析 48
4.2.2 GPST試片熱電傳輸特性 56
伍、結論 62
陸、參考文獻 63

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