Correlated phase and microstructural evolution are systematically investigated by electron microscopies in Sr-deficient Sr(Ti, Nb)O₃ (STNO) thermoelectric ceramics incorporated with different fraction of reduced graphene oxide (RGO). It is found that while no impurity except for very few Ti₃O₅ precipitates are observed in monolithic STNO, the Nb-enriched rutile TiO₂ appears in RGO/STNO composites. With increasing RGO content, the amount of precipitates increase at first and then decrease when RGO content becomes high, which can be ascribed to the formation of local Magnéli phase. In addition, the energy-dispersive X-ray spectra combined with cathodoluminescence characterization indicates that the variation of Sr deficiency experiences the opposite trend with respect to the precipitates content. These findings clearly reveal the unique reducing effect of RGO on the microstructure of doped SrTiO₃ with Sr deficiency, which can greatly facilitate the design of perovskite based thermoelectric materials of hierarchical structure.

通过电子显微镜系统研究了掺有不同比例的氧化石墨烯（RGO）的Sr不足的Sr（Ti，Nb）O ₃（STNO）热电陶瓷中相关相和微结构的演变。发现在单块STNO中除了很少的Ti ₃ O ₅析出物外没有观察到杂质，而富Nb的金红石型TiO ₂出现在RGO / STNO复合材料中。随着RGO含量的增加，析出物的数量先增加，然后在RGO含量高时减少，这可以归因于局部Magnéli相的形成。此外，能量色散X射线光谱结合阴极发光特征表明，Sr缺乏的变化相对于沉淀物含量经历相反的趋势。这些发现清楚地揭示了RGO对具有Sr缺陷的掺杂SrTiO ₃的微观结构的独特还原作用，这可以极大地促进钙钛矿基热电材料的分层结构设计。