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.

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