Strontium titanate (SrTiO₃) based materials are promising for high‐temperature thermoelectric applications. In order to enhance their performance, annealing is usually required and carried out under various atmospheres. Annealing with graphite is quite effective, but the mechanism is not yet clear. In this work, we use IR spectroscopy and gas chromatography (GC) to monitor the chemical environment under the annealing conditions (1350 °C for 8 h under 16.9 mL/min N₂ with graphite) and quantify the various gases evolved in the process. It is shown that reducing agents, H₂ and CO (concentrations peaked at ca. 0.4–0.5 %), are generated from graphite in the annealing process. H₂ is produced in carbon gasification reaction, which also generates CO. Additional CO is produced from incomplete combustion of carbon. In the annealing of a La‐doped SrTiO₃‐based ceramic with graphite, higher levels of H₂O and CO₂ are detected, which is resulted from the reduction of the ceramic by H₂ and CO, respectively. About 67 % of the oxygen vacancies were created by CO reduction while about 33 % by H₂ reduction. The conclusions are well supported by direct weight loss measurements with a difference of less than 6 %.

中文翻译：

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石墨对钛酸锶基热电材料的退火：光谱和色谱技术的机理分析

钛酸锶（SrTiO ₃）基材料有望用于高温热电应用。为了提高它们的性能，通常需要退火并且在各种气氛下进行退火。用石墨进行退火是非常有效的，但机理尚不清楚。在这项工作中，我们使用红外光谱和气相色谱（GC）监测退火条件下的化学环境（在16.9 mL / min的N ₂和石墨条件下，在1350°C下持续8 h ），并对过程中产生的各种气体进行定量。结果表明，在退火过程中，石墨会生成还原剂H ₂和CO（浓度约为0.4-0.5％的峰值）。高₂碳气化反应中产生的二氧化碳也产生一氧化碳。碳的不完全燃烧会产生额外的二氧化碳。在用石墨对掺La的SrTiO ₃基陶瓷进行退火时，检测到较高的H ₂ O和CO ₂含量，这是由于陶瓷分别被H ₂和CO还原而导致的。约67％的氧空位是由CO还原产生的，而约33％是由H ₂还原产生的。直接重量损失小于6％的测量结果很好地支持了这些结论。