熱電材料能將熱能轉換成電能，可以將廢熱回收，進而提升能源使用效率。在能源短缺的議題受到重視的今日，熱電材料也備受矚目。Ag2Se是室溫型的熱電材料，在室溫的環境下具有良好的熱電性質表現。Ag2Se是Ag-Se二元系統相圖中唯一穩定的介金屬相，此介金屬相在溫度約132oC時存在一個相變化。在低於132oC的溫度下，Ag2Se的晶體結構是Primitive orthorhombic，高於相變溫度的晶體結構是Body center cubic。本研究工作包含二部分，第一部分是300oC的Ag-In-Se三元相圖，第二部分為在室溫的Ag2-xInxSe的熱電性質。本研究配置不同組成的三元合金，分析其生成相。依據三元合金的相平衡結果，文獻中Ag-In、Ag-Se與In-Se的二元相圖，文獻中Ag-In-Se的相關相平衡資料，及不含三元參數的二元系統熱力學參數的Ag-In-Se三元系統相圖計算結果，來建構Ag-In-Se的300oC等溫橫截面圖。在300oC的Ag-In-Se三元系統，有Liquid (In)、Liquid (Se)與(Ag)三個端頂相，Ag2Se、ζ-Ag3In、γ-Ag9In4、In4Se3、InSe、In6Se7與In2Se3等七個二元相，與AgInSe2和AgIn5Se8二個三元相。Ag2Se摻雜In的Ag2-xInxSe (x=0, 0.0005, 0.001, 0.002, 0.01, 0.02, 0.03)的熱電性質量測與分析，在300K至420K的溫度區間，席貝克係數和電阻率隨著摻雜In量的上升而遞減，能量係數則有先上升後下降的趨勢，熱傳導係數則是上升。結合熱電量測的結果計算Ag2-xInxSe (x=0, 0.0005, 0.001, 0.002, 0.01, 0.02, 0.03) 的熱電優值。除了熱電量測外，本研究也對摻雜In系列Ag2Se的樣本在室溫下進行霍爾量測，得到載子濃度、載子遷移率以及霍爾係數。

Thermoelectric materials can convert heat into electricity, and they can thus enhance energy usage efficiency by recovering waste heat. Energy is one of the most critical concerns of sustainability and thermoelectric materials have thus attracted a lot of research interests. Ag2Se is a room-temperature type thermoelectric material and has better thermoelectric properties at room temperature. Ag2Se is the only stable compound in the binary Ag-Se system. Ag2Se has two different crystal structures. One is a primitive orthorhombic and the other is a body center cubic. At room temperature, Ag2Se’s crystal structure is primitive orthorhombic. It will undergo a first order phase transition to body center cubic crystal structure at 132oC. This research has two parts. The first part is about the determination of the 300oC Ag-In-Se isothermal section, and the second part is about the determination of the thermoelectric properties of the In-doped Ag2Se, Ag2-xInxSe, (x=0, 0.0005, 0.001, 0.002, 0.01, 0.02, 0.03). Ternary Ag-In-Se alloys are prepared, equilibrated at 300oC, and the phases are determined. The 300oC Ag-In-Se isothermal section is determined based on the phase equilibria results of the ternary alloys at 300oC, the phase diagrams of the constituent binary systems, Ag-Se, Ag-In and In-Se, the available phase equilibria results of the Ag-In-Se ternary system in the literatures, and the preliminary calculated phase diagrams based on the binary thermodynamic parameters without ternary interaction parameters. The stable phases at the Ag-In-Se ternary system at 300oC are: three terminal phases, Liquid (In), Liquid (Se) and (Ag), seven binary compounds, Ag2Se,ζ-Ag3In,γ-Ag9In4, In4Se3, InSe, In6Se7, and In2Se3 and two ternary compounds, AgInSe2 and AgIn5Se8. The thermoelectric properties of the In-doped Ag2Se, Ag2-xInxSe (x=0, 0.0005, 0.001, 0.002, 0.01, 0.02, 0.03), have been measured. When the amount of indium increases, the seebeck coefficient and resistivity decrease gradually. Power factor can be obtained from seebeck coefficient and resistivity, and its values rise first then fall along with the increase of indium amount. Thermal conductivity is determined, and it increases gradually when the amount of indium increases. Finally, figure of merit can be calculated. Besides, Hall measurement has been carried out at the room temperature. Carrier concentration, mobility and hall coefficient are obtained.

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