Ba0.5Sr0.5Co0.8Fe0.2O3-δ ¬是目前備受矚目的混和離子/電子導體材料，由於其高離子導性與相對穩定的晶體結構，在中溫固態氧化物燃料電池與氧傳輸薄膜的應用上都開始有相關的研究。
本研究首先藉由X光繞射光譜分析BaxSr1-xCoyFe1-yO3-δ (x=0~1, y=0~1)的晶體結構隨著組成的變化，在x=0時，SrCo0.8Fe0.2O3-δ 從繞射光譜中可看出其晶體結構主要是正方晶相鈣鈦礦結構，但第二相SrCoO2.8的生成顯示其結構的不穩定性。¬¬¬¬¬而在x=0.2 to 0.8時其晶體結構皆為正方晶相鈣鈦礦結構而且其繞射峰角度隨著鋇摻雜量的增加而向低角度偏移，這顯示出了晶體隨著鋇的摻雜而膨脹。而當鋇的摻雜量超過60%時，BaxSr1-xCo0.8Fe0.2O3-δ 將無法維持單一正方晶相鈣鈦礦結構而相轉變成同為正方晶相的BaFeO3、斜方晶相的BaCoO2.7以及SrFe2O4，而當x=1時，由繞射光譜可知其主要結構為六方晶相的BaFeO2.9 以及Co3O4。而Ba0.5Sr0.5CoyFe1-yO3-δ 在y=0~0.8時皆顯示為正方晶相鈣鈦礦結構，但在y=1時則相轉變為氧空缺有序排列的2-H型六方晶相。
本次研究利用四線式電阻量測法測量BaxSr1-xCoyFe1-yO3-δ (x=0.2~0.8, y=0~0.8)於空氣中的導電性質，BaxSr1-xCo0.8Fe0.2O3-δ (x=0.2~0.8)的導電率隨著鋇的摻雜量增加而減少，這是由於因為被摻雜導致的晶體結構擴張阻礙了導電粒子的傳輸進而造成了導電率的下降。而Ba0.5Sr0.5CoyFe1-yO3-δ (y=0~0.8)的導電率在低於400℃時呈現p型半導體的導電特性，隨著溫度的升高而增加(活化能:0.248-0.346eV)，而在高於400℃後導電率開始隨著溫度升高而降低，而這主要是因為結構中四價的鐵離子的價數被還原並伴隨著氧空缺的生成，而導致帶電粒子濃度的下降。藉由這些量測可以更加的了解在不同的結構與溫度下BaxSr1-xCoyFe1-yO3-δ的導電機制。
Ba0.5Sr0.5Co0.8Fe0.2O3-δ的氧傳輸性質在600到900℃的區間量測，厚度800微米的Ba0.5Sr0.5Co0.8Fe0.2O3-δ氧傳輸薄膜在900℃氧分壓差分別為po2=0.21跟1時可以達到1.196和4.223ml/min-cm2。而為了要減少薄膜的厚度，本次研究利用刮刀成形法製備非對稱型結構的氧傳輸薄膜，包含了約40μm厚的氣密膜披覆在同材質的多孔性基材上，以漸少傳輸薄膜的厚度並維持其強度，非對稱薄膜於900℃時的氧傳輸量可達2.726 ml/min-cm2，而為了更進一步的提升非對稱薄膜的氧傳輸量，在非對稱薄膜的表面上再以刮刀成形製備一層Ba0.5Sr0.5Co0.8Fe0.2O3-δ催化層，以提升表面氧離子吸脫附的速率，而包含厚約9.11微米催化層的非對稱薄膜其氧傳輸量在900℃時可達5.43ml min-cm2，分別比單一結構厚膜與無催化層之非對稱膜提升99.19% 和354.01%.

Ba0.5Sr0.5Co0.8Fe0.2O3-δ, denoted as BSCF, is a well-known mixed ionic/electronic conductor (MIEC) due to the potential on the applications as a cathode material of the intermediate temperature solid oxide fuel cells (IT-SOFCs) and oxygen transport membranes (OTMs). The crystal structures of the BaxSr1-xCoyFe1-yO3-δ (x=0~1, y=0~1) had been investigated by the X-ray diffraction patterns. When x=0, the SrCo0.8Fe0.2O3-δ shows unstable crystal structure with additional peaks of tetragonal SrCoO2.8 and the primary phase is cubic perovskite. When x=0.2 to 0.6, there all showed the cubic perovskite structures and peaks shifted to lower diffraction angles with the increasing amount of Ba suggested the expansion of crystal. When the x exceeds 0.6, the structure cannot maintain the single cubic perovskite due to the larger ionic radius of Ba2+ (1.61Å) and transferred into the cubic perovskite BaFeO3, orthorhombic BaCoO2.7 and SrFe2O4 structure. The XRD pattern shows mainly hexagonal BaFeO2.9 and Co3O4 in the composition of x=1. The diffraction pattern of y=0~0.8 shows the cubic perovskite structure and the structure become oxygen vacancy-ordered 2-H type hexagonal phase with y=1.
The conductivity of BaxSr1-xCoyFe1-yO3-δ (x=0.2~0.8, y=0~0.8) had been measured by 4-point conductivity measurements in air with silver-paste as electrodes. The conductivity decreased with the increasing of Ba dopant which is because the expansion of the crystal structure impeded the transport of charge carriers. Below 400℃, the conductivity of Ba0.5Sr0.5CoyFe1-yO3-δ (y=0~0.8) was thermal activated (Ea= 0.248-0.346 eV) and the conductivity decreased with increasing temperature above 400℃, which was attributed to the decrease in p-type carriers resulted by the reduction of Fe4+ associated with the formation of oxygen vacancies. These measurements enable better understanding of the conduction mechanism of BSCF according to the changes of composition and temperatures.
The oxygen permeation flux of Ba0.5Sr0.5Co0.8Fe0.2O3-δ was 1.196 and 4.223 ml/min cm2 with pO2=0.21 and pO2=1 at 900℃ with membrane thickness of 800μm. The asymmetric structure, which is consistent with 40μm gas-tight layer on 300μm porous substrate with the same material Ba0.5Sr0.5Co0.8Fe0.2O3-δ, had been fabricated by tape casting method to minimize the thickness of oxygen transport membrane. The oxygen permeation of asymmetric membrane was 2.726 ml/min cm2 at 900℃. To further improve the property of oxygen permeation, a Ba0.5Sr0.5Co0.8Fe0.2O3-δ catalytic layer had been fabricated on the surface of asymmetric membrane and the membrane with 9.11μm catalytic layer achieved the best results to 5.43 ml/cm2min with pO2=0.21 at 900℃ which is 99.19% and 354.01% higher than the bare asymmetric membrane and symmetric membrane.

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