Fusheng Song , Hongbing Wei , Zongyang Shen , Zhumei Wang , Yueming Li
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引用次数: 0
Abstract
The sulfurization pathways of pure and Na-doped CeO2 with CS₂ were investigated to elucidate the mechanism by which Na+ doping lowers γ-Ce2S3 synthesis temperature. For undoped CeO2, the synthesis of γ-Ce2S3 typically encompasses three primary steps: (1) deoxidation, where oxygen in CeO2 is substituted by sulfur to form CeS2; (2) reduction of CeS2 to α-Ce2S3; (3) a phase transition sequence from α-Ce2S3 to β-Ce2S3, and subsequently to γ-Ce2S3. This process requires a high synthesis temperature of up to 1300 °C. Remarkably, Na+ introduction fundamentally altered this pathway, bypassing α and β intermediates to directly yield pure γ-Ce2S3 at 900 °C. This is attributed to Na+-promoted formation of NaCeS2 and Ce2O2S intermediates that facilitate direct γ-phase crystallization. The resultant γ-[Na]-Ce2S3 solid solution exhibits modified band structure and enhanced thermal stability compared to undoped γ-Ce2S3.
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