Catalytic Dynamics and Oxygen Diffusion in Doped PrBaCo2O5.5+未 Thin Films

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• 作者：Erik Enriquez ; Xing Xu ; Shanyong Bao ; Zach Harrell ; Chonglin Chen Sihyuk Choi ; Areum Jun ; Guntae Kim ; Myung-Hwan Whangbo
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：November 4, 2015
• 年：2015
• 卷：7
• 期：43
• 页码：24353-24359
• 全文大小：473K
• ISSN：1944-8252

文摘

The Sr and Fe codoped double perovskites PrBaCo₂O_5.5+未 (PrBCO) thin films of Pr(Ba_0.5Sr_0.5)(Co_1.5Fe_0.5)O_5.5+未 (PBSCFO) were epitaxially grown for chemical catalytic studies. The resistance behavior of PBSCFO epitaxial films was monitored under the switching flow of reducing and oxidizing gases as a function of the gas flow time, t, using an electrical conductivity relaxation (ECR) experimental setup. The R(t) vs t relationships determined at various temperatures show the occurrence of two oxidation processes, Co²⁺/Co³⁺ 鈫?Co³⁺ and Co³⁺ 鈫?Co³⁺/Co⁴⁺. Mathematical fitting of the observed R(t) vs t relationships was carried out using Fick鈥檚 second law for one-dimensional diffusion of charge carriers to derive the diffusivity D(T) and 蟿(T) for the two processes at various temperatures, T. The D(T) vs T relationships were analyzed in terms of the Arrhenius relationship to find the activation energies E_a for each process. Oscillations in the dR(t)/dt plots, observed under oxidation reactions, were discussed in terms of a layer-by-layer oxygen vacancy exchange diffusion mechanism. Our work suggests that thin films of LnBCO (Ln = lanthanide) with their A and B sites doped as in PBSCFO are excellent candidates for the development of low or intermediate temperature energy conversion devices and gas sensor applications.