固態電解質為高氧離子導電率的導體，利用晶粒本身性質，藉由晶粒中氧空缺來傳導氧離子，螢石結構(Fluorite Structure)為具有高氧離子導電率的結晶構造，純的CeO2從室溫至熔點皆為穩定的螢石結構，不需進行穩定化，摻雜異價陽離子，以增加氧空缺，提高氧離子導電率，具有比現行商業化的氧化釔安定化氧化鋯(YSZ)固態電解質還要高的離子導電率以及較低的活化能,極有希望成為固體氧化物燃料電池(Solid Oxide Fuel Cell,SOFC)的電解質材料。
　　本研究以微波加熱燃燒合成法製備GdxCe1-xO2-x/2粉末，經過加壓成型、燒結後作為固態電解質，利用XRD、SEM、BET，針對不同添加比例，分析粉末及燒結體的結晶相、顯微結構、緻密度，以及使用直流電法(DC-method)量測其導電率。
　　微波加熱燃燒合成法是以硝酸鈰、硝酸釓為氧化劑，尿素當還原劑，先配製成溶液的形式，再以微波加熱以引燃溶液，燃燒結束後反應便完成，可得到多孔性且蓬鬆的GdxCe1-xO2-x/2粉體，整個反應在極短時間內便可完成。經XRD的結果證實，在添加Gd3+比例範圍內(0＜x＜0.24)為單一相且完全固溶的螢石結構粉末，其粒徑大小約為10~20nm。
　　以Gd3+摻雜CeO2固態電解質，可有效提高氧離子導電率，900℃時導電率由7.37×10-4S/cm (CeO2) 提高到2.8×10-2S/cm(Ce0.8Gd0.2O1.9) 且隨著添加量的增加，氧空缺濃度增加，導電率也增加，但當添加比例超過x=0.2時，導電率並沒有跟著增加，其原因是因為氧離子空位的有序化，缺陷締合以及靜電相互作用所造成的。活化能隨著添加比例增加而降低，在x=0.2活化能為0.0869(eV)，繼續增加會使活化能升高，可與導電率結果作對照。

　　The Solid electrolyte is a conductor of the high oxygen ionic conductivity. It uses the nature from crystalline grain itself, as well as the oxygen vacancy inside to conduct oxygen ions. Fluorite Structure is a crystal conformation with high oxygen ionic conductivity. The pure CeO2 is stable Fluorite Structure both under the room temperature and melting point, so it is not necessary to stabilize and add unsual valence cation to increase the oxygen vacancy and increase oxygen ion electric conductivity. Besides, as compared to the current commercial YSZ (Yttria Stabilized Zirconia) solid electrolyte, it has higher ionic conductivity and lower active energy; therefore, it’s very possible that doped CeO2 could become the electrolyte material of solid oxide Fuel Cell (SOFC).
　　In this research, firstly, we adopted the method of “Microwave-induced Combustion Synthesis” to produce GdxCel-xO2-x/2 powder. Secondly, after pressurizing to form its shape, and sintering, it would become solid electrolyte. Then, we used XRD, SEM, BET, in accordance with different adding proportion, and analyzed powder, the crystal phase of sintered substances, microstructure, and fineness In addition, we also used DC-method to measure its ionic conductivity.
　　The method of “Microwave-induced Combustion Synthesis” is that we use Cerium Nitrate and Gadolinium Nitrate as the oxidizer and urea as reducing agent, to compound to the form of liquid, and then heat it up by microwave, in order to kindle the liquid. After finishing kindling, the reaction is completed. We therefore could get powder with porosity and fluffiness. The whole reaction can be finished in an extremely short time. The GdxCel-xO2-x/2 we get by using the above method shows a result of XRD: In the range of adding Gd3+ proportion(0<x<0.24), the powder belong to single phase and Fluorite Structure which is complete solid solution. The diameter of each powder is about 10 to 20nm.
　　By adding Gd3+ to CeO2 solid electrolytes could effectively increase the oxygen ion electric conductivity. When the temperature reaches 900℃, the electric conductivity can increase from 7.37×10-4S/cm (CeO2) to 2.8×10-2S/cm(Ce0.8Gd0.2O1.9). With the increase of adding amount, the concentration of oxygen vacancy would increase, as well as the ionic conductivity. However, if the adding proportion exceeds x=0.2, the ionic conductivity will not increase. The reason is because the vacancy of oxygen ion is formed by functioning between ordering, flaw　association, and static electricity. The activation energy would be reduced by the increase of adding proportion. When x=0.2, the active energy will be 0.0869(eV), and if keeping increasing, the active energy would also increase. The result can be a comparison of the result of electric conductivity.

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