| The equilibrium partial pressure of oxygen obtained by mixing CO₂ and H₂ gas is determined with (ZrO₂)_(0.85)(CaO)_(0.15) solid state cell by means of measurement of E.M.F. and the compound of SrO-Fe₂O₃ system is studied. The results obtained in this study are as follows. i) The oxygen partial pressure is determinable above 1000°K. The oxygen partial pressure by E.M.F. measurement is almost consistent with that which is calculated from equilibrium data when the flow speed of mixed gas is about 180cc/min, and the initial ratio of mixing(P_(co2)/P_(H3)) is nearly 1. ii) Sr₃Fe₃O_(7-x) phase is terragonal and single phase in the range of oxygen pressure:0.21∼10^(-15) atmosphere. According to decreasing oxygen contents of this phase, lattice constant of a_0 is increased and a_0 is decreased. iii) The composition of SrFeO_(2.54-2.74) is rhombohedral, single phase, SrFeO_(2.54-2.74) contains cubic and rhombohedral two phases, and SrFeO_(2.74-) is single cubic phase. |
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