釔摻雜在SrCeO3之電導率及化學穩定性影響

Electrical Conductivity and Chemical Stability of Yttrium Doped SrCeO3

曾子豪(Zi-hao Zeng)

指導教授 ： 李 雄

國立中央大學/工學院/機械工程學系/碩士(2012年)

摘要

鍶鈰氧化物有利於當作固態氧化物氫傳輸膜(SOHTM)之材料，導因於其擁有高的電子及質子電導率。固態氧化物氫傳輸膜用來萃取天然氣或石化燃料中的氫氣，有幾點條件須滿足方能維持運作：對於氫氣需有高選擇性，具備足夠機械強度以抵抗膜兩端的壓力差，在高水氣、二氧化碳及硫化物分壓下須有良好的化學穩定性。本實驗所使用摻雜釔之鍶鈰氧化物(SrCe1-xYxO3-δ, x=0, 0.05, 0.1)是以檸檬酸-EDTA方法製備，材料之微結構以X光繞射儀(XRD)、場發掃描式電子顯微鏡(FE-SEM)及穿透式電子顯微鏡(TEM)來做觀察。材料之電導率使用兩點式電阻量測，化學穩定性則在CO2氣氛下處理後觀察實驗結果。由1000°C瑕燒所得之粉體經XRD鑑定顯示為不含其他相之純相。在導電率方面，鍶鈰氧化物電導率隨著釔摻雜含量增加而提升。此外在低於700°C下，質子傳導主導大部分的傳導。而在高於700°C溫度時，電子傳導為總電導率之主要貢獻。在CO2化學穩定性實驗中，穩定性隨釔摻雜含量增加而下降。

關鍵字

鈣鈦礦 ； 氫傳輸膜 ； 化學穩定性 ； 電導率

並列摘要

Strontium-cerium oxides are beneficial for solid oxide hydrogen transport membranes (SOHTMs) because of their relatively high electrical and protonic conductivities. SOHTMs for the purpose of extraction of hydrogen from supplied gas mixtures are required to be: high selectivity for hydrogen but not others; mechanically strong enough to resist differential pressures across them; chemically stable under high partial pressure of moisture, carbon dioxide and sulfides; In this study, yttrium substituted strontium cerate (SrCe1-xYxO3-δ, x=0, 0.05, 0.1) was prepared by Citrate-EDTA complexing method. The microstructures were identified using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). Electrical conductivity was measured by two-point probe and chemical stability was examined under CO2 atmosphere. Preliminary results from XRD showed no detectable impurity phases when powders were calcined at 1000℃. The electrical conductivity increased as concentration of doped Y increased. However, At lower temperature (<700°C), the protonic conductivity dominated the total conductivity. At high temperature (>700°C), the electronic conductivity dominated the total conductivity. The chemical stability under CO2 was significantly to lose as more Y was doped into strontium cerates.

並列關鍵字

HTM ； Perovskite ； Conductivity ； Chemical Stability

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