Nonstoichiometry in Oxide Thin Films Operating under Anodic Conditions: A Chemical Capacitance Study of the Praseodymium鈥揅erium Oxide System
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- 作者：Di Chen ; Sean R. Bishop ; Harry L. Tuller
- 刊名：Chemistry of Materials
- 出版年：2014
- 出版时间：November 25, 2014
- 年：2014
- 卷：26
- 期：22
- 页码：6622-6627
- 全文大小：353K
- ISSN：1520-5002
文摘
PrxCe1鈥?i>xO2鈭捨?/sub> can potentially serve as both the cathode and anode in solid oxide fuel cells (SOFCs), given that it exhibits significant mixed ionic-electronic conductivity (MIEC) under both cathodic and anodic conditions. While MIEC is strongly dependent on oxygen nonstoichiometry (未), there have been few ways to extract this information reliably and in situ, particularly for thin films. In this work, this is achieved by analysis of chemical capacitance values extracted from impedance spectroscopy data obtained on electrochemical cells of the form Pr0.1Ce0.9O2鈭捨?/sub>/Y0.16Zr0.84O1.92/Pr0.1Ce0.9O2鈭捨?/sub> operating at temperatures in the range of 450鈥?00 掳C and over the oxygen pressure (pO2) range of 10鈥?3鈥?0鈥?4 atm. In combination with our prior investigation, the oxygen nonstoichiometry over a very wide range of pO2 values is derived. We found that 未 in thin films differs from that of the bulk (未film > 未bulk). This follows from a decreased enthalpy of reduction of 4.12 卤 0.25 eV for the film, compared to 4.52 卤 0.37 eV for the bulk.