為調變熱電塊材的載子濃度，進而增加塊材的電傳導率與 Seebeck 係數，以提升功率因子 (power factor)，本研究以無電鍍製程將 Ag 披覆於 PbTe 粉體上形成複合粉體，再以火花電漿燒結 (spark plasma sintering, SPS) 於 300 ~ 400 oC 、 50 MPa 壓力下製成 PbTe/Ag 複合塊材，檢討銀添加量及火花電漿燒結溫度對塊材的顯微結構及熱電性質的影響。
於製程上，披覆於 PbTe 粉體上的銀粒子的量是由適當添加還原劑量的控制而得。披覆的銀粒子其大小為 100 ~ 200 nm 。披覆的銀經 SPS 燒結後除形成微米尺度的團聚銀並存在於 PbTe 晶界上外，亦會於 PbTe 中產生兩種固溶形式，分別為主要的間隙型固溶與部分的取代型固溶 (Ag 取代 Pb位置)。
PbTe/Ag 塊材的電傳行為是隨銀添加量而異，≤ 2.18 wt% Ag 者為 p 型，> 6.81 wt% Ag 者轉變成 n 型摻雜半導體的電傳行為。此外，功率因子 (S2σ) 則隨銀添加量與量測溫度之增加而增加，而銀含量 6.81 wt% 之 PbTe/Ag 複合粉體以 SPS 於 400 oC 燒結所得之塊材，其熱電優值 (ZT) 於 610 K 時有最大值 0.27。
n 型傳導的 PbTe/Ag (含 8.96 wt% Ag) 塊材其室溫載子濃度是隨SPS燒結溫度之增加而減少；而塊材之相對密度、載子遷移率及 Seebeck 係數亦隨隨燒結溫度之增加而增加，其中銀含量 8.96 wt% 之 PbTe/Ag-400 oC 塊材的功率因子在 609 K 時有最大值 1.15 mW/m-K2，其功率為未添加銀的 PbTe-400 oC 塊材之功率因子 (0.04 mW/m-K2) 的 28.4 倍。

For changing carrier concentration and increasing electrical conductivity and Seebeck coefficient, and then enhancing the power factor of the PbTe/Ag bulk materials, in this study, PbTe/Ag hybrid powders were prepared using the electroless plating methods and sintered by spark plasma sintering (SPS) at 50 MPa from 300 oC to 400 oC. Effects of Ag comtents and SPS temperatures on the microstructures and thermoelectric properties of PbTe/Ag bulks were investigated.
The amounts of silver particles coating on the PbTe powders could be controled by adding the suitable amounts of the reducing agent, and the sizes of silver particles were 100 ~ 200 nm. After SPS sintering, the silver not only agglomerated in micro-scale on the grain boundaries of the PbTe but also formed solid solution in PbTe, including interstitial mainly and substitutional solid solutions.
The electric conductivity of PbTe/Ag bulks could be transformed from p-type to n-type with the increase of silver. The power factor of PbTe/Ag bulks increased with the silver contents and the sintering temperatures. The maximum ZT value, 0.27, was obtained from the PbTe/Ag bulk material prepared by SPS at 400 oC with 6.81 wt% silver measured at 610 K.
The carrier concentration of the n-type PbTe/Ag (with 8.96 wt% Ag) bulk materials at room temperature decreased with increasing SPS sintering temperatures. The relative densities, carrier mobilities and Seebeck coefficients of the bulk materials all increased with sintering temperatures. of The PbTe/Ag-400 oC bulk material with 8.96 wt% sliver had the maximum power factor,1.15 mW/m-K2 at 609 K, which was 28 times higher than PbTe-400 oC bulk without silver.

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