酸素固体電解質としてのシリカ-アルミナセラミックスの起電力の組成依存性

概要

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The electromotive force (EMF) of an oxygen concentration cell using Si0_2 Al_2O_3 ceramics (x= 1, 2, 3 and 4 in xAl_2O_3 2SiO_2) as a solid electrolyte was measured at 1073 1573 K in the oxygen pressure range of 1.0×10^<-1.0> to 1.0×10^<3.5> Pa at the anode side. The Si0_2 Al_2O_3 ceramics (96.2 98.5% of theoretical density) sintered at 1873 1903 K in air were annealed at 1673 K for 8h to produce equilibrium phases before EMF measurement. Air as a reference gas and Ar O_2 mixed gas were introduced to cathode and anode sides, respectively. The measured EMF indicates that ionic transport number (t_i) of oxygen is higher in the following order: mullite SiO_2 composite (x=1, 2) >mullite(x=3) >mullite-Al_2O_3 composite (x=4). At lower oxygen pressures, t_i decreased with decreasing oxygen pressure due to formation of electrons available for conduction. The critical oxygen pressure for t_i≈1 was 10^<1.8> to 10^<2.7> Pa for x=1, 2. The concentration of electrons formed in creased in proportional to Po_2^<-1/4> at 1473 1573 K, and Po_2^<-1/6> at 1073 K.
社団法人日本セラミックス協会の論文
1994-03-01