A-site與B-site摻雜對於SrCeO3鈣鈦礦材料特性影響;A-site and B-site Doped Effect on the SrCeO3 Perovskite Material Properties

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Title:	A-site與B-site摻雜對於SrCeO3鈣鈦礦材料特性影響;A-site and B-site Doped Effect on the SrCeO3 Perovskite Material Properties
Authors:	陳柏璋;Chen,Po-chang
Contributors:	機械工程學系
Keywords:	鈣鈦礦;質子傳輸膜;化學穩定性;導電率;Perovskite;Hydrogen transport membranes;Chemical Stability;Conductivity
Date:	2014-07-14
Issue Date:	2014-10-15 17:17:55 (UTC+8)
Publisher:	國立中央大學
Abstract:	鈣鈦礦結構鍶鈰氧化物(strontium-cerium oxides)具有高的質子與電子傳導率，故廣泛應用於質子傳輸膜(Hydrogen Transport Membrane, HTM)、氫氣感測器與質子傳輸型固態氧化物燃料電池電解質材料。許多研究都著重於摻雜異價元素(3+)於B-site對於材料導電性與化學穩定性之影響，但摻雜於A-site對材料特性影響卻鮮少討論。本論文主要探討不同位置摻雜對於SrCeO3材料晶格變化、質子與電子傳導率、化學穩定性的影響。本研究選擇鉀元素(K＋)摻雜於A-site、釔元素(Y3+)摻雜於B-site，其材料化學式可寫成SrCeO3、SrCe0.95Y0.05O3-δ、Sr0.95K0.05CeO3-δ與Sr0.95K0.05Ce0.95Y0.05O3-δ四種材料。材料合成利用固態反應法 (Solid State Reaction, SSR)來製備。以X光粉末繞射儀(XRD)分析材料相與結構的變化，場發掃描式電子顯微鏡(FE-SEM)觀察材料表面形貌；利用兩點式電阻量測法分別在RH 1%與RH 30%氫氣氣氛下進行電導率測試；化學穩定性則在600℃、1 atm CO2氣氛下，分別進行2、4、8與16小時穩定性測試。由XRD結果顯示，四種材料經1250℃煆燒12小時後可獲得單一鈣鈦礦結構，並無其他雜相生成；經過1550℃高溫燒結後，所有材料孔隙率皆低於4%。化學穩定性方面，四種材料經過16小時均以分解成SrCO3與CeO2氧化相，顯示不同位置摻雜無助於提升材料之化學穩定性。在導電性方面，Sr0.95K0.05CeO3-δ材料於900℃於濕氫氣氣氛下(RH 30%)具有較高的導電率，可達到0.1527 S∙cm-1。 ;Strontium-cerium oxides can be widely applied to hydrogen transport membranes (HTMs),hydrogen sensors and electrolyte materials of proton-conducting solid-oxide fuel cells because their relatively high electrical and protonic conductivities. Many investigations have focused on different valance of the dopants on B-site to the effect of material conductivity and chemical stability, but different valance of the dopants on A-site effect to material properties rarely be discussed. This essay focuses on different location of doping effect into lattice deformation in perovskite material protonic and electrical conductivities. In this study we choose potassium to dope A-site of strontium creates and yttrium to the dope B-site of strontium creates. The material of the formula could be written SrCeO3, SrCe0.95Y0.05O3-δ, Sr0.95K0.05CeO3-δ and Sr0.95K0.05Ce0.95Y0.05O3-δ. Material was prepared by solid state reaction. The crystal structure, phase and microstructures were identified using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM). Electrical conductivity were measured in RH1% and RH30% hydrogen atmosphere at 550℃ to 900℃ by two-point probe method. Chemical stability were examined under CO2 atmosphere at 600℃ for 2, 4, 8 and 16 hours, respectively. Hydrogen flux of material was examined by gas chromatography. Preliminary results from XRD showed the pure perovskite structure and no detectable impurity phases when powders were calcined at 1250℃ for 12 hours; porosities of all material were less than 4% when pellets were sintered at at 1550℃. The results from chemical stability showed a different location doped not to enhance the chemical stability of the material when perovskite could be decomposed into SrCO3 and CeO2 oxide phase. In terms of electrical conductivity, the conductivity of Sr0.95K0.05CeO3-δ could be achieved with 0.1527 S∙cm-1 in RH 30% hydrogen atmosphere at 900℃.
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