A two-step solar thermochemical cycle was considered for air separation to produce N₂ based on (Ba,La)_xSr_1-xFeO_3-δ perovskite reduction/oxidation (redox) reactions for A-site fractions of 0 ≤ x ≤ 0.2. The cycle steps encompassed (1) thermal reduction and O₂ release via concentrated solar input and (2) re-oxidation with air to uptake O₂ and produce high-purity N₂. Thermogravimetry at temperatures between 400 and 1100 °C in atmospheres of 0.005 to 90% O₂/Ar at 1 bar was performed to measure equilibrium nonstoichiometries. The compound energy formalism was applied to model redox thermodynamics for both Ba²⁺ and La³⁺ substitution. Non-linear regression was used to determine the empirical parameters based on the thermogravimetric measurements. The model was used to define partial molar reaction enthalpies and entropies and predicted equilibrium oxygen nonstoichiometry as functions of oxide stoichiometry, site fraction, temperature, and O₂ partial pressure. The thermodynamic analysis showed the materials are appealing for air separation at temperatures below 800 °C.

基于 (Ba,La) _x Sr _1-x FeO _3-δ钙钛矿还原/氧化（氧化还原）反应，对于 0 ≤ x ≤ 的 A 位分数，考虑使用两步太阳能热化学循环进行空气分离以产生 N ₂ 0.2. 循环步骤包括 (1)通过集中太阳能输入进行热还原和 O ₂释放，以及 (2) 用空气再氧化以吸收 O ₂并产生高纯度 N ₂。在 400 至 1100 °C 之间的温度下，在 0.005 至 90% O ₂ /Ar 和 1 bar 的气氛中进行热重分析以测量平衡非化学计量。应用复合能量形式来模拟 Ba ^{2+ 的}氧化还原热力学和 La ³⁺取代。非线性回归用于基于热重测量确定经验参数。该模型用于定义部分摩尔反应焓和熵，并预测平衡氧非化学计量作为氧化物化学计量、位点分数、温度和 O ₂分压的函数。热力学分析表明，这些材料在低于 800 °C 的温度下对空气分离很有吸引力。