La1-xBaxGa1-yMgyO3-δ電解質電性及微觀結構分析

本實驗使用固態合成法製備中溫型固態氧化物電解質試片，摻雜鹼土金屬(Ba2+、Mg2+)於純LaGaO3中並燒結於1550oC持溫12小時，使其結構因電荷補償作用產生氧空缺，再探討電性及微觀結構分析。利用XRD做相結構初步判定，使用波長為0.15418 nm，隨後計算慢掃角度2θ為45o~48o其峰值偏移量，藉以觀察Ba2+、Mg2+於LaGaO3主相之固溶情況，並與同步輻射XRD，使用波長為0.10162623 nm，計算慢掃角度2θ為42.7o~ 44.5o之峰值偏移量做比對，同樣發現峰值皆往低角度位移，且Mg2+較Ba2+易固溶於主相中；後續以拉曼光譜判定因摻雜所產生之氧空缺波段位於677及739 cm-1，及確認因摻雜使相結構轉變為菱方晶，並計算菱方相晶格常數值ahR、chR值，再以菱方相與偽立方相之晶向關係，推算偽立方相晶格常數值，證實菱方相亦可表示為偽立方相；SEM觀察巨觀形貌，隨Ba2+摻雜其形貌呈現四方形，並利用EDS判定二次相成份；直流電性量測溫度範圍為500oC~800oC，以La0.95Ba0.05Ga0.75Mg0.25O3-δ在800oC導電率σ約0.1 S/cm最好。交流阻抗分析部份主要探討範圍在300oC~800oC其離子導體於固態陶瓷電解質中之導電機制。由低溫300oC~400oC離子藉由晶界傳遞，至高溫500oC~800oC晶格擴散機率增大。利用TEM觀察試片微結構特徵，藉由菱方相及偽立方相其面和方向對應之矩陣互轉公式，並由TEM繞射圖做驗證，證明鈣鈦礦結構菱方相亦可由偽立方相做表示，並證實隨摻雜量的添加，La1-xBaxGa1-yMgyO3-δ其結構已不同於LaGaO3的正交晶結構。

關鍵字

固態氧化物燃料電池；鎵酸鑭；鈣鈦礦結構

並列摘要

Ba2+ and Mg2+ ions doped LaGaO3 compositions were prepared by the solid-state reaction method, which were sintered at 1550 oC for 12 h, the oxygen vacancies generated to compensae the charge of substituting ions, then discussing electrical and microstructure. Calculate peak shift 2θ from 45o to 48o by X-ray(λ = 0.15418 nm) and 2θ from 42.7o to 44.5o in synchrotron radiation (λ = 0.10162623 nm), it shows the same result the peak of the BaO and MgO shift to low angle and the Mg+ were soluted in main phase more than Ba2+. Using Raman spectrometer determine the oxygen vacancies at 700 cm-1, and confirming the structure change to rhombohedral. Calculate the lattice constant of the rhombohedral which is surmised the pseudo cubic lattice constant. The tetragonal surface with Ba2+ doped by SEM observe, and using EDS to determine the secondary phase on the specimens. La0.95Ba0.05Ga0.75Mg0.25O3-δ behaved the higher conductivity 0.1 S/cm at 800oC by using DC measurement. Discussing AC impedance for the oxygen ion mechanism in the solid oxide electrolyte specimens and the measurement temperature range of 300oC ~800oC. Analysing microscopic structure of the specimens by TEM, then used matrix formula for the plane and direction of the rhombohedral and pseudo cubic corresponded, do the verification by the diffraction pattern. To verify the rhombohedral expressed as pseudo cubic of the perovskite structure, and La1-xBaxGa1-yMgyO3-δ structure different from the LaGaO3 orthorhombic by doping.

並列關鍵字

Solid Oxide Fuel Cell ； Lanthanum gallium oxide ； Perovskite structure

參考文獻

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[7] M. S. Khan, M. S. Islam, “Dopant Substitution and Ion Migration in the LaGaO3-Based Oxygen Ion Conductor,” Journal of Physics Chemistry, 102 3099-3104 (1998).

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La1-xBaxGa1-yMgyO3-δ電解質電性及微觀結構分析

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