金屬離子與摻雜濃度對BaZrO3導電的影響
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2013
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利用實驗以溶膠-凝膠法(sol-gel)改良為較佳合成方式。首先，加入添加物金屬氧化物與利用NH4OH調控溶液pH值進行合成M-doped BaZrO3的粉末，之後再壓錠鍛燒高溫獲得樣品。在合成的各種變因中，如不同的添加物，pH值、鍛燒溫度的改變以及不同的鋪粉，有系統的測試，使得樣品有較高的密度、較大的晶粒尺寸、與更好的質子導電率。分別利用密度公式、XRD、SEM、EDS鑑定樣品密度、化學成分、顯微結構和摻雜比例，進行實驗的樣品分析。
M-doped BaZrO3 (M3+ = Al3+、Ga3+、In3+、Y3+、La3+ 、Nd3+、 Sm3+、Gd3+、 Dy3+、Ho3+ 、Er3+)為一種質子導體，藉由摻雜金屬產生氧空穴，在含有水氣的環境下，氧空穴與水氣結合得到質子。探討質子導電率，利用DC二電極和AC四電極的EIS在飽和水氣的氮氣下進行質子導電率的測試，測量溫度為100-700℃。在相同條件下，探討摻雜金屬對質子導電率的影響與趨勢，再以Arrhenius方程式得到各種摻雜金屬的活化能與A值。由實驗結果推斷質子傳導與摻雜半徑有關，最適當的摻雜金屬離子(Ho3+、Er3+、Dy3+)擁有較佳的質子導電率。
由於導電率與質子濃度有關，所以改變摻雜濃度。探討相同摻雜金屬，當濃度改變時對導電率影響。因此將較佳的三種金屬做摻雜濃度的改變BaZr1-xMxO3-α (0.10≦x≦0.25)。實驗結果顯示，摻雜濃度與導電率成反比，過多的質子濃度會互相trap住質子，使其較難傳導，降低導電率。因此最佳摻雜濃度為10 mol%。
The effects of cations (M3+ = Al3+、Ga3+、In3+、Y3+、La3+ 、Nd3+、 Sm3+、Gd3+、 Dy3+、Ho3+ 、Er3+) and their dopant ratios (0.05 ~ 0.30) on the proton conductivity have been systematically investgated on BaZrO3-based materials.The ceramic powders were initially synthesized by sol-gel method and with small amount of metal oxide additive and pH-controlled condition and subsequently compressed to pellet sintered at higher temperature 1400 ℃. The density, chemical composition, microstructure and dopant ratios of samples are characterized by density function, XRD, SEM, EDX. The protonic conductivity was measured by DC 2-electrode and AC 4 electrode methods from 700 – 100℃ in the wet-N2 condition.The results showed that proton conductivities is related to radii of doping catios, and the cations of Ho3+、Er3+、Dy3+ are the most proper dopant catios with the best proton conductivity. The analysis for Arrhenius equations on proton conductivity further clarified that the pre-exponential factors have larger variance while the activation barriers are rather intact by the doped cations. The doping concentration, another key factor, is inversely proportional to the proton conductivity, attributable to that the excess cation concentrations trap proton and the best doping ratio is 10 mol%. The Arrhenius analysis identified that, on the other hand, activation barrier is the important factor in the dopant-ratio effect while pre-exponential factors are in variant by ratios.
The effects of cations (M3+ = Al3+、Ga3+、In3+、Y3+、La3+ 、Nd3+、 Sm3+、Gd3+、 Dy3+、Ho3+ 、Er3+) and their dopant ratios (0.05 ~ 0.30) on the proton conductivity have been systematically investgated on BaZrO3-based materials.The ceramic powders were initially synthesized by sol-gel method and with small amount of metal oxide additive and pH-controlled condition and subsequently compressed to pellet sintered at higher temperature 1400 ℃. The density, chemical composition, microstructure and dopant ratios of samples are characterized by density function, XRD, SEM, EDX. The protonic conductivity was measured by DC 2-electrode and AC 4 electrode methods from 700 – 100℃ in the wet-N2 condition.The results showed that proton conductivities is related to radii of doping catios, and the cations of Ho3+、Er3+、Dy3+ are the most proper dopant catios with the best proton conductivity. The analysis for Arrhenius equations on proton conductivity further clarified that the pre-exponential factors have larger variance while the activation barriers are rather intact by the doped cations. The doping concentration, another key factor, is inversely proportional to the proton conductivity, attributable to that the excess cation concentrations trap proton and the best doping ratio is 10 mol%. The Arrhenius analysis identified that, on the other hand, activation barrier is the important factor in the dopant-ratio effect while pre-exponential factors are in variant by ratios.
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鈣鈦礦結構, 摻雜金屬, 固態電解質, 質子導體, BaZrO3, dopant cations, solid electrolyte, proton conductivity