本研究將探討La0.6Sr0.4(Co1-x Znx)0.2Fe0.8O3-d (x=0.0、0.2、0.4、0.6、0.8、1.0)陰極材料，搭配在本實驗室所開發出具有優異導電率的電解質Ce0.78Gd0.2Sr0.02O1.9-x(GDC+Sr)來進行半電池測試。試片製作將控制陰極孔隙率約為31.25%，使用電化學交流阻抗圖譜術(EIS)來探討影響陰極氧還原反應之極化損失與陰極的電化學反應，並搭配X-ray繞射(XRD)分析晶體結構、掃描式顯微鏡(SEM)分析微結構、熱機械分析儀(TMA)分析熱膨脹係數與熱差/熱重分析儀(DTA/TGA)分析是否有相變化現象。
La0.6Sr0.4(Co1-x Znx)0.2Fe0.8O3-d成份變化由XRD分析為單一相的菱方晶(Rhombohedral)鈣鈦礦結構，a=b=c，因為鋅離子半徑大於鈷離子半徑約22%，所以當鋅逐漸取代鈷，其晶格常數與體積擴大。
根據同步熱差與熱重分析組成x = 0.0~1.0於量測溫度500~800℃間之實驗數據顯示出無明顯相變化現象，表示陰極/電解質界面能穩定搭配。在熱機械分析實驗數據得各組成之緻密塊材隨著溫度增加，而熱膨脹率近似線性增長，熱膨脹係數(Thermal expansion coefficient，TEC)隨著鋅元素摻雜取代鈷元素呈現下降的趨勢，由16.8下降至13.31 10-6k-1。直流四點探針的量測發現到在La0.6Sr0.4(Co1-x Znx)0.2Fe0.8O3-d，x = 0.0，純粹鈷元素沒摻雜鋅元素，其導電性最佳，在650℃達到229 S/cm，隨著鋅元素添加會導致導電性下降，而在x = 1.0，鋅元素全數取代鈷元素，其導電性(61 S/cm，600℃)為最差。
由電化學交流阻抗圖譜發現La0.6Sr0.4(Co1-x Znx)0.2Fe0.8O3-d系列B-site隨著鋅元素摻雜取代鈷元素，在x = 0.4、0.6與0.8呈現出低的極化阻抗(0.273、0.240 & 0.15 Ωcm2，800℃) 。分析其極化阻抗於高頻區域的阻值差異不大，但在中、低頻區域的阻值，因為B-site使用二價的鋅元素摻雜取代浮動價數的鈷元素造成電荷不平衡，會形成更多氧空缺，加速氧離子傳遞，而且鈷元素會二、三、四價數轉換來提供電子，說明B-site 鋅元素與鈷元素共存會有更低的氧化還原阻抗。此實驗結果與電化學分析(鐵弗曲線之交換電流密度、極化曲線與循環伏安曲線)之數據皆呈現出相同的趨勢。
在LSCZF材料組成中，以La0.6Sr0.4(Co0.2 Zn0.8)0.2Fe0.8O3-d擁有最佳特性：極低極化阻抗0.15 Ωcm2，800℃)、較LSCZF0.0(16.8 10-6k-1)低的熱膨脹係數(13.95 10-6k-1)與較佳的交換電流密度(331.41 mA/cm2，800℃)具有良好的催化特性，其特性皆優於La0.6Sr0.4Co0.2 Fe0.8O3-d與La0.6Sr0.4Zn0.2 Fe0.8O3-d母材，成為均衡性佳且催化特性優異的新型固態氧化物陰極材料。

This research was focused on the Cathode material, La0.6Sr0.4(Co1-x Znx)0.2Fe0.8O3-d(x=0.0、0.2、0.4、0.6、0.8、1.0), to go through the half-cell test with excellent electrical conductivity of the electrolyte Ce0.78Gd0.2Sr0.02O1.9-x(GDC+Sr) developed by our laboratory. The cathode porosity of test chip/fragment was controlled to be approximately 31.25±3% for evaluating the effect on polarization loss of cathode oxygen reduction reaction and electrical chemical reaction with electrochemical impedance spectroscopy (EIS). A combination of analytical techniques were applied X-ray diffraction for interpreting the crystal structure, scanning electron microscope (SEM) for examining micro-structures, thermo mechanical analyzer (TMA) for finding thermal expansion coefficient (TEC) and (DTA/TGA) thermal analyzers for analyzing the presence of Phase & Change.

The variation in component of La0.6Sr0.4(Co1-x Znx)0.2Fe0.8O3-d
analyzed by XRD was single-based Rhombohedral Perovskite, a=b=c. The lattice constant and volume were expanded when Zinc ionic substitutes for Cobalt ionic due to the radius of Zinc was 22% being wider than that of Cobalt.

According to the statistics from (DTA/TGA) thermal analysis, there was no Phase & Change when x was 0.0~1.0 at 500~800℃ which meant the interface between cathode and electrolyte was stable. In addition, based on the statistics from thermo mechanical analysis, the thermal expansion coefficient of the bulk grew as the temperature increases. Moreover, the thermal expansion coefficient decreased from 16.8 to 13.31 10-6k-1 if Zinc substituted for Cobalt.

On the basis of electrical chemical alternating electrical impedance atlas method (x = 0.4, 0.6, 0.8) when Cobalt was replaced by Zinc, the cathode electrical impedance of B-site in La0.6Sr0.4(Co1-x Znx)0.2Fe0.8O3-d
series was low (0.273、0.240 & 0.15 Ωcm2，800℃).

The difference of cathode electrical impedance (Co -> Zn) in the high frequency region was not obvious. However, among middle and low frequency regions, the imbalance of electric charge caused by adopting the valence two Zinc to B-site instead of Cobalt with floating valence created a lot of oxygen vacancies, accelerating the circulation. Electrons were provided by cobalt switching from valence two, three, to four as well, and therefore the electrical impedance of oxygen reduction reaction was low when coexistence of B-site Zinc and Cobalt. The trend of the testing result statistics was the same as that of electrochemical analysis; such as electric current-switched density of Tafel Curve, Polarization Curve, and Cyclic Voltammetry Curve.

Among the components of LSCZF, La0.6Sr0.4(Co0.2 Zn0.8)0.2Fe0.8O3-d
performed the best because the cathode electrical impedance was quite low (0.15 Ωcm2，800℃) and the thermal expansion coefficient (13.95 10-6k-1) is lower than LSCZF0.0(16.8 10-6k-1). Additionally the catalysis was significantly imporoved, due to the higher electric current-switched density. The overall performance of La0.6Sr0.4(Co0.2 Zn0.8)0.2Fe0.8O3-d was found to be better than that of the precursor of La0.6Sr0.4Co0.2 Fe0.8O3-and La0.6Sr0.4Zn0.2 Fe0.8O3-,and was proposed as an innovative solid oxide Cathode material with good compatibility and catalysis.

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