二氧化鈰(CeO2)陶瓷材料在不同領域具有廣泛的應用性。本實驗將探討CeO2在固態氧化物燃料電池(Solid oxide fuel cell, SOFC)中電解質材料的應用。CeO2屬於螢石結構，具有良好的氧離子傳導能力，在SOFC中主要應用在電解質(Electrolyte)材料。而為了得到高密度的電解質材料，CeO2的形貌必須為實心球狀，在燒結過程中才能得到較高的密度。因此對於電解質材料的應用，CeO2形貌的操控是必須且重要的。
本實驗將由先驅物(Precursor)的特性探討不同形貌顆粒的成型機制，並藉此機制操控或製備具有新形貌的CeO2顆粒，所使用的製程為噴霧熱解法(Spray pyrolysis, SP)。先驅物的特性主要以熱重分析(Thermogravimetric analysis, TGA)及熱差分析(Differential thermal analysis, DTA)量測。而CeO2的顆粒形貌及表面結構分別以穿透式電子顯微鏡(Transmission electron microscopy, TEM)和掃描式電子顯微鏡(Scanning electron microscopy, SEM)鑑定。實驗結果顯示利用單無機鹽類先驅物醋酸鈰(CeA)、硝酸鈰(CeN)及硝酸鈰銨(CeAN)可分別得到中空(type II)或碗狀(type III)、多孔狀(type IV)及實心球狀(type I)結構的CeO2粉體。雙無機鹽類先驅物50CeA50CeN、50CeA50CeAN及50CeN50CeAN可得到實心球狀(type I)、隕石狀(type V)及鑲嵌狀結構(type VI)的CeO2粉體，其中利用先驅物硝酸鈰銨製備具有實心球狀的CeO2粉體可被應用在SOFC的電解質材料。
利用先驅物硝酸鈰銨與硝酸釤經由SP合成摻雜釤之CeO2粉體(Sm-doped ceria, SDC)，利用XRD鑑定粉體的結晶相，並透過晶格常數的計算判斷Sm在CeO2中的固溶量，實驗結果顯示當摻雜量到達
60at%時並無第二相產生。將不同比例的SDC粉體利用網印的技術印在具有白金線路之氧化鋁板上，透過500oC、2h將膠體去除並用1200oC、2h燒結緻密化後形成厚度約10-20μm的厚膜，在不同溫度900oC、800oC及700oC下測量導電率，導電率隨著溫度上升而上升，在摻雜量為20at%時會有最高的導電率。

Ceria (CeO2) materials are widely used in various applications. This study investigates the solid oxide fuel cell (SOFC) applications for CeO2 electrolytes. CeO2 has a fluorite crystallographic structure and it exhibits the excellent oxygen ion conductivity in SOFC electrolytes. In order to obtain the dense SOFC electrolytes with fewer pores, the morphology of solid spherical for CeO2 particles have benefits for sintering process. Manipulation of particle morphology is urgent and important for SOFC electrolytes.
This study synthesizes various morphological CeO2 particles from various precursors using spray pyrolysis (SP), and investigates the relativant formation mechanisms for various precursor characteristics. In order to examine the mechanisms, the decomposition behaviors of the precursors were examined by thermogravimetric analysis (TGA) and differential thermal analyzer (DTA). The geometries and surface morphologies of the ceria particles were examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. The experimental results show that the particle morphologies of hollow (type II) or bowl-like (type III), porous (type IV) and solid spherical (type I) structures were obtained using the single-salts of cerium acetate (CeA), cerium nitrate (CeN) and ammonium cerium nitrate (CeAN), respectively. The dual-salt system including 50CeA50CeN, 50CeA50CeAN and 50CeN50CeAN was applied to produce various morphological particles： solid spherical (type I), meteorite-like (type V) and embedded (type VI) structures. Furthermore, the solid spherical particles prepared from CeAN have been used in SOFC electrolytes.
The precursors of CeAN and samarium nitrate were used to produce Sm-doped ceria (SDC) particles using SP. The crystallographic phase and lattice parameters of SDC particles were examined by X-ray diffraction (XRD), and only the fluorite phase exists in SDC with the doping level from 0 to 60at%. SDC powders with various compositions were screen printed on the alumina substrates with platinum wires. The formation of thick films with 10-20μm thickness undergoes the gel decomposition at 500oC for 5h and sintering at 1200oC for 2h. The conductivities were measured at 900oC, 800oC and 700oC. The result shows that the conductivities increase with the increasing of temperature, and the highest conductivity value appears at 20at% SDC.

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