Thermodynamic properties of nonstoichiometric oxygen in manganite Ca_0.9Pr_0.1MnO_3–δ

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• 作者：I. A. Leonidov ; E. I. Konstantinova…
• 关键词：perovskite ; like oxides ; calcium manganite CaMnO3 ; oxygen nonstoichiometry ; partial thermodynamic functions of oxygen
• 刊名：Russian Journal of Physical Chemistry A, Focus on Chemistry
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：90
• 期：11
• 页码：2123-2128
• 全文大小：398 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Physical Chemistry
  Russian Library of Science
  
• 出版者：MAIK Nauka/Interperiodica distributed exclusively by Springer Science+Business Media LLC.
• ISSN：1531-863X
• 卷排序：90

文摘

The chemical potential of oxygen Δμ_O relative to its standard state in the gas phase was calculated from the experimental dependences of the oxygen content in various polymorphic modifications of Ca_0.9Pr_0.1MnO_3–δ on the partial pressure and temperature. The partial molar enthalpy \(\Delta {\overline H _O}\) and entropy \(\Delta {\overline S _O}\) of oxygen were obtained from the linear temperature dependences of Δμ_O. Based on the ideal solution approximation, \(\Delta {\overline H _O}\) and \(\Delta {\overline S _O}\) were correlated with the enthalpies and entropies of the defect formation reactions, the concentrations of manganese cations, and the oxygen nonstoichiometry. The thermal excitation of Mn4+ cations was shown to substantially affect the thermodynamic functions of oxygen.