研究了Bi摻雜對Cu_2SnSe3的熱電性能的影響。所有樣品的粉末X射線衍射（XRD）圖譜均顯示立方結構。系列樣品Cu_2Sn_(1-x)BixSe3（x = 0.00、0.02、0.04、0.06、0.08、0.10）中對電阻率（ρ），熱導率（κ）和塞貝克係數（S），進行測量溫度範圍為10 K – 350 K。電阻率隨摻雜量的增加而降低。根據X射線光電子能譜（XPS）結果。Seebeck係數結果表明，在低溫區域，線性趨勢有所偏離，懷疑受到聲子阻力的影響。由於摻雜後電阻率顯著下降，因此電子導熱率所佔比例增加，總導熱率隨摻雜量而增加。場發射掃描電子顯微鏡（FESEM）圖像顯示，晶粒尺寸隨摻雜量的增加而增加，這可能是摻雜後晶格導熱係數的聲子散射峰變得更尖銳的原因。對於樣品Cu_2Sn0.92Bi0.08Se3，ZT的在350 K時有最大值，約為0.0267，大約是原始樣品的兩倍。

The effect of Bi doping on the thermoelectric properties of Cu2SnSe3 was investigated. The powder X-ray diffraction (XRD) patterns for all samples showed a cubic structure. Electrical resistivity (ρ), thermal conductivity (κ), and Seebeck coefficient (S) measurements were performed on a series of samples Cu2Sn1-xBixSe3 (x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10) in the temperature range 10 K – 350 K. In general, the electrical resistivity decreases significantly with increasing Bi content. The Seebeck coefficient data show a deviation from linearity at low temperatures, presumably due to the phonon drag effect. The overall thermal conductivity is found to increase with the Bi substitution, most likely attributed to the reduction in the grain-boundary scattering. The field emission scanning electron microscope (FESEM) images confirm that the grain size increase with the Bi content, consistent with the thermal conductivity measurements. The highest figure of merit at 350 K is about 0.0267 for the Cu2Sn0.92Bi0.08Se3 sample, which is about two times larger than that of the pristine sample.

第一章 緒論 1
1.1 熱電材料 1
1.2 論文回顧 4
1.2.1 電性傳輸網絡 5
1.2.2 特殊的聲子散射機制 7
1.3 研究動機 7
第二章 實驗原理 9
2.1 電阻率(Resistivity) 9
2.1.1 電子的碰撞機制 11
2.2 熱電勢 (Thermoelectric Power) 14
2.2.1 Seebeck 效應 14
2.2.2 Seebeck 係數 16
2.3 熱傳導率 (Thermoconductivity) 21
2.3.1 電子熱傳導率 (κe) 22
2.3.2 聲子熱傳導率 (κph) 23
2.4 比熱 27
2.4.1 聲子比熱 27
第三章 實驗原理 29
3.1 量測系統 29
3.1.1 低溫冷卻系統 29
3.1.2 電阻率量測方法 31
3.1.3 熱傳導率量測方法 32
3.1.4 Seebeck 係數量測方法 33
3.2 實驗控制程式 35
第四章 實驗結果與分析 43
4.1 XRD 分析 ( X-ray diffraction ) 43
4.2 XPS 分析 45
4.3 FESEM 分析 51
4.4 電阻率(Electrical Resistivity) 55
4.5 熱電勢(Seebeck coefficient) 61
4.5.1 Mott’s VRH & 擴散熱電勢 Sd 62
4.5.2 低溫線性偏離行為 65
4.6 熱導率(Thermal conductivity) 71
4.6.1 電子熱導率 κe 71
4.6.2 聲子熱導率 κL 72
4.6.3 聲子熱導率 κL /總熱導率 κ 75
4.7 Figure of merit 79
第五章 結論 81
Reference 83

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