The role of B-site cations on proton conductivity in double perovskite oxides La₂MgTiO₆ and La₂MgZrO₆

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• 作者：Camilla K. Vigen ; Tor Svendsen Bjø ; rheim ; Reidar Haugsrud ; ^{reidar.haugsrud@smn.uio.no}
• 关键词：Double perovskite ; La2MgTiO6 ; La2MgZrO6 ; Proton mobility ; Hydration thermodynamics
• 刊名：International Journal of Hydrogen Energy
• 出版年：2012
• 期刊代码：42_03603199
• 类别：ch
• 出版时间：May, 2012
• 卷：37
• 期：9
• 页码：7983-7994
• 文件大小：1177 K

摘要

Acceptor-doped La₂MgTiO₆ (LMTO) and La₂MgZrO₆ (LMZO) have been investigated to contribute to clarify the role of the B-site cations in A₂B鈥睟鈥砄₆ double perovskite oxides on formation and mobility of protons. Thermogravimetry and a.c. conductivity measurements in the temperature range 1000-300聽掳C, as well as DFT-calculations of LMTO, have been the basis for evaluating hydration thermodynamics and transport parameters of the materials. Both compounds show exothermic hydration of oxygen vacancies, but low concentrations of protons. The proton transport is limited by relatively high activation energies of mobility; 0.84聽eV and 0.78聽eV for LMTO and LMZO, respectively. This is suggested to reflect association to effectively negative charged defects formed by site exchange among the B-site cations. Consequently, the maximum proton conductivity of LMTO and LMZO is in the order of 10^鈭?聽S/cm.