Protonic conduction, crystal and electronic structures of LaBaGaMgO
LaBaGaMgOのプロトン伝導、結晶/電子構造の解析
浜尾 尚樹*; 北村 尚斗*; 伊藤 孝憲*; 井川 直樹 ; 井手本 康*; 大道 博行; 加来 正典*; 窪寺 昌一*
Hamao, Naoki*; Kitamura, Naoto*; Ito, Takanori*; Igawa, Naoki; Idemoto, Yasushi*; Daido, Hiroyuki; Kaku, Masanori*; Kubodera, Masakazu*
燃料電池用固体電解質材料、LaBaGaMgOを固相反応法で合成し、電気伝導度やRietveld/最大エントロピー法による結晶構造解析を行った。基本材料であるLaBaGaOの一部をBaやMgで置換することで、プロトン伝導度が向上した。Rietveld/最大エントロピー法解析の結果、1000Kまでの温度ではLaBaGaMgOはLaBaGaOと同じ結晶構造を有すること、プロトンはO3サイト近傍に配置し、この酸素と水素結合していることがわかった。
LaBaGaMgO which is one of the candidates for solid electrolyte of solid oxide fuel cell was synthesized by means of a conventional solid-state reaction, and investigated by conductivity measurements, the Rietveld and maximum entropy method analyses using neutron and synchrotron X-ray diffraction data. Conductivity measurements indicated that simultaneous Ba and Mg substitutions for LaBaGaO were effective way to improve the protonic conductivity. From the Rietveld and maximum entropy method analyses, it was confirmed that LaBaGaMgO kept the same crystal structure as LaBaGaO even at elevated temperature, i.e. 1000 K, and that protons existed around the O3 site and formed hydrogen bonds. It is also found that oxygens in LaBaGaO-based samples formed Ga-O tetrahedra, and the bonding strength was varied by the partial substitutions.