熱電材料在溫差發電及熱電致冷方面都具有廣泛的應用，其有無運動部位，無噪音無污染等優點。PbTe 系合金是中溫區(400~700 K)熱電發電中最常用的熱電材料，其 ZT 值的研究主要集中在兩個方向：一、藉由增加材料內部的載子濃度(carrier concentration)來提高其功率因子(electrical power factor, S2σ)，二、增加材料內部的聲子(phonon)散射來降低其熱導係數，且不使電傳導係數下降太多。
本研究以二種無電鍍方式將奈米銀粒子披覆在PbTe 粉體表面，再以 SPS 在 300 ℃~400 ℃ 及壓力 100 MPa下進行燒結，所得之燒結塊材進行熱電性質之量測，並利用 XRD 、SEM、TEM、EDS 等儀器分析粉體及燒結體的微結構。本文檢討了Ag含量及燒結溫度對於 PbTe 燒結體的熱電性質及顯微結構的影響。
研究結果顯示，鍍析於 PbTe 粉體表面的 Ag 之含量是依無電鍍製程而異，其燒結緻密溫度亦異。Ag 含量為 1 at％ 及 3 at％ 之 PbTe 粉體，其燒結緻密(相對密度 ≧ 95 ％)溫度分別為 300 ℃ 及 400 ℃。
在熱電性質方面，隨著 Ag 含量及燒結溫度的增加，燒結體顯示出由 p 型向 n 型的載子類型轉變。以 400 ℃ 燒結、 Ag 含量為 3 at％ 之 n 型材料，與未經無電鍍處理之 PbTe 燒結體相比，其在 521 K 時之Seebeck 係數是由 -104.4 μV/K增加到 -312.3 μV/K，電傳導係數是由 13.8 S/cm 增加到 96.4 S/cm，最大功率因子值為 0.941 mw/cm-K2。

Thermoelectric materials and devices have received increasing attention because of their potential application in the fields of energy conversion, sensors, and thermoelectric cooling. The PbTe are the most commonly found thermoelectric materials which can be used in the 400-700 K temperature range. The research into PbTe’s figure-of-merit (ZT) has mainly focused on two main areas: (1) Improving the electrical power factor by increasing the material’s carrier concentration; (2) Lowering thermal conductivity by increasing the material’s ability to scatter phonons without causing a major decrease in electrical conductivity. This research continues this investigation.
Two different electroless plating methods are used to apply an Ag nanoparticle coating on PbTe, which are then sintered by SPS at 300-400 ℃ and 100 MPa. The crystal structure is analyzed by use of an X-ray diffraction method at room temperature using CuKα radiation, while the chemical composition is determined by an EDS analysis. The microstructures of the PbTe/Ag hybrid powders and the bulk materials are then observed by SEM and TEM. Finally, this research investigates how the Ag content and sintering temperature influences the PbTe/Ag bulk material’s microstructure and transport properties.
The findings show that the two electroless plating methods result in 1 at% and 3 at% Ag coating contents on PbTe powders, and which sintering densification (relative density ≧ 95%) temperatures are 300 ℃ and 400 ℃, respectively.
In terms of transport properties, the carrier transforms from p-type to n-type as the Ag coating content and sintering densification temperature increase. When comparing uncoated bulk material with 3 at% Ag coated bulk material sintered at 400 ℃, it is found that at 521 K the Seebeck coefficient increases from -104.4 μV/K to -312.3 μV/K and the electrical conductivity increases from 13.8 S/cm to 96.4 S/cm, providing a maximum power factor of 0.941 mw/cm-K2 for the bulk material containing 3 at% Ag.

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