A Joint Theoretical and Experimental Study of Phase Equilibria and Evolution in Pt-Doped Calcium Titanate under Redox Conditions

详细信息    查看全文

• 作者：Baihai Li ; Michael B. Katz ; Yingwen Duan ; Xianfeng Du ; Kui Zhang ; Liang Chen ; Anton Van der Ven ; George W. Graham ; Xiaoqing Pan
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：January 13, 2015
• 年：2015
• 卷：27
• 期：1
• 页码：18-28
• 全文大小：664K
• ISSN：1520-5002

文摘

Pseudoternary phase diagrams of the PtO<sub>xsub>鈥揅aO鈥揟iO<sub>xsub> system were constructed using first-principles theoretical methods to interpret experimental observations of phase formation and evolution in Pt-doped CaTiO<sub>3sub> made by aberration-corrected scanning transmission electron microscopy. In this system, promoted as a self-regenerative automotive exhaust-gas catalyst, Pt precipitates as metallic particles from the doped perovskite under reducing conditions and tends to redissolve under oxidizing conditions. Due to the likely influence of kinetic limitations on experimental observations, we focus on a restricted (metastable) phase diagram in which single and other unobserved oxides of Pt are intentionally excluded. Various titanate phases appear, however, and their presence helps inform the calculation of the phase diagrams, which in turn confirm that the self-regenerative effect is a consequence of thermodynamic phase stability under the specific redox environments examined.