Synthesis and Characterization of Nonsubstituted and Substituted Proton-Conducting La6鈥?i>xWO12鈥?i>y

详细信息    查看全文

• 作者：Janka Seeger ; Mariya E. Ivanova ; Wilhelm A. Meulenberg ; Doris Sebold ; Detlev St枚ver ; Tobias Scherb ; Gerhard Schumacher ; Sonia Escol谩stico ; Cecilia Sol铆s ; Jos茅 M. Serra
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：September 16, 2013
• 年：2013
• 卷：52
• 期：18
• 页码：10375-10386
• 全文大小：754K
• 年卷期：v.52,no.18(September 16, 2013)
• ISSN：1520-510X

文摘

Mixed proton鈥揺lectron conductors (MPEC) can be used as gas separation membranes to extract hydrogen from a gas stream, for example, in a power plant. From the different MPEC, the ceramic material lanthanum tungstate presents an important mixed protonic鈥揺lectronic conductivity. Lanthanum tungstate La_6鈥?i>xWO_12鈥?i>y (with y = 1.5x + 未 and x = 0.5鈥?.8) compounds were prepared with La/W ratios between 4.8 and 6.0 and sintered at temperatures between 1300 and 1500 掳C in order to study the dependence of the single-phase formation region on the La/W ratio and temperature. Furthermore, compounds substituted in the La or W position were prepared. Ce, Nd, Tb, and Y were used for partial substitution at the La site, while Ir, Re, and Mo were applied for W substitution. All substituents were applied in different concentrations. The electrical conductivity of nonsubstituted La_6鈥?i>xWO_12鈥?i>y and for all substituted La_6鈥?i>xWO_12鈥?i>y compounds was measured in the temperature range of 400鈥?00 掳C in wet (2.5% H₂O) and dry mixtures of 4% H₂ in Ar. The greatest improvement in the electrical characteristics was found in the case of 20 mol % substitution with both Re and Mo. After treatment in 100% H₂ at 800 掳C, the compounds remained unchanged as confirmed with XRD, Raman, and SEM.