固態電解質為高氧離子導電率導體，利用固溶取代之性質，藉由晶粒中氧空缺來傳導氧離子。螢石結構為具有高氧離子導電率的結晶構造，未摻雜氧化鈰從室溫至熔點皆為穩定的螢石結構，且不需進行穩定化，其穩定性非常利於燃料電池之固態電解質。氧化鈰可摻雜異價陽離子，以增加氧離子空缺，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，極可能取代YSZ而成為固體氧化物燃料電池(Solid Oxide Fuel Cell，SOFC)的電解質材料。
本研究以化學共沉法與共沸點蒸餾法製備Ce1-xSmxO2-x/2粉末，經過加壓成型、燒結後作為固態電解質，利用DTA、XRD、TEM、SEM、BET等分析設備，針對不同添加比例、燒結溫度與研磨時間，分析粉末及燒結體的結晶相、顯微結構、緻密度，以及使用交流阻抗分析法分析並模擬量測其離子導電率、活化能與晶界與晶粒的阻抗分析。
本研究以Sm3+摻雜CeO2固態電解質，可有效提高氧離子導電率，且隨著添加量的增加，氧空缺濃度增加，導電率也隨之增加，而活化能隨之降低。Ce1-xSmxO2-x/2燒結體在x=0.2且球磨時間9小時，燒結溫度為1450℃之燒結體可達到99.9%之相對密度。且850℃時導電率為3.13×10-2S/cm。近一步觀察到晶粒與晶界離子傳導率之差異，並且從低到高溫時，離子傳導率由晶界主導改變至晶粒主導，最後再度改變至晶界主導。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。

A fuel cell is an electrochemical energy conversion device. It includes anode, cathode and electrolyte.　The solid electrolyte is a conductor with the high oxygen ionic conductivity. A Solid Oxide Fuel Cell (SOFC) is regarded to be a highly efficient power-generation system for future applications. A typical high-temperature SOFC uses 8 mol% yttria-stabilized zirconia (YSZ) as an electrolyte, which is usually operated at a temperature as high as 800–1000℃, to obtain the required high ionic conductivity. However, such high temperatures will lead to a reaction between the components, thermal degradation, or thermal expansion mismatch. In order to reduce the operation temperature from 1000 to 800℃ or even lower, doped ceria has been considered as the solid electrolyte for moderate-temperature SOFCs. The conductivity maximum in zirconia has been correlated with the minimum dopant level necessary to stabilize the high-temperature face-centered cubic (F.C.C.) phase. Contrary to pure YSZ, CeO2 has a fluorite structure and oxygen vacancies as predominant ionic defects. Pure CeO2 ceramic is a poor oxide ion conductor. However, the ion conductivity of CeO2 can be significantly improved upon substitution dopant ion and oxygen vacancy.

In this research, first of all, we applied the method of “Chemical Coprecipitation” to produce SmxCe1-xO2-x/2 nano-scale powder. Secondly, after pressurizing and sintering, it would become solid electrolyte. Then, we applied DTA, XRD, TEM, SEM, and BET to observe sample with different adding proportion. We also analyzed nano-scale powder. It includes crystal phase analyzing of sintered substances, microstructure analyzing, and fineness measuring of powder. In addition, we applied AC-method to measure its impedance and ionic conductivity. For Sm0.8Ce0.2O1.9 ceramic sintered at 1500℃ for 5 hours, the bulk density was over 99.9% of the theoretical density. The maximum ionic conductivity, 3.13×10-2 Scm-1 at 850℃ with the minimum activation energy, Ea=0.74 eV, was found in Sm0.8Ce0.2O1.9 ceramic solid electrolyte.

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