The processes of oxygen tracer diffusion and oxygen surface exchange in acceptor-doped oxides displaying high rates of oxygen transport are examined. Literature data are analysed with the standard atomistic expression, in order to obtain chemically reasonable limiting values for the oxygen diffusion coefficient, D*, in the solid state. The analysis suggests a limiting value of D* that is characterised by a pre-exponential of 8.8 × 10⁻² cm² s⁻¹ and an activation enthalpy of 0.5 eV. An (essentially temperature-independent) ultimate limit to the oxygen surface exchange coefficient, k*, of ca. 10⁰ cm s⁻¹ is obtained by assuming surface exchange to be limited by the incident flux of oxygen molecules from the gas phase. In addition, atomistic expressions are derived that quantitatively describe experimental k* data as a function of temperature and oxygen activity for surface exchange involving molecular oxygen at high temperatures. One expression is found for oxides with a bandgap, such as SrTiO₃, Ce_0.9Gd_0.1O_1.95, and La_0.6Sr_0.4Fe_0.8Co_0.2O_3−δ; and an analogous expression is found for oxides with a partially filled conduction band, such as La_1−aSr_aCoO_3−δ and (Ba_0.5Sr_0.5)(Co_0.8Fe_0.2)O_3−δ. Conduction-band electrons are considered for both types of oxides to play a central role in determining the rate of oxygen surface exchange.

中文翻译：

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限制混合导电氧化物中氧气的传输速率

研究了在氧掺杂速率高的受体掺杂氧化物中氧示踪剂扩散和氧表面交换的过程。用标准原子表达式分析文献数据，以便获得固态中氧扩散系数D *的化学上合理的极限值。该分析提出了D *的极限值，该极限值的特征在于前指数为8.8×10 ^-2 cm ² s ^-1，激活焓为0.5 eV。氧表面交换系数k *的（基本上与温度无关）极限。10 ⁰厘米s ^-1通过假定表面交换受到来自气相的氧分子的入射通量的限制而获得。另外，导出了原子表达式，该表达式定量地描述了实验性k *数据与温度和氧气活性的函数，用于高温下涉及分子氧的表面交换。一个表达被发现为与带隙的氧化物，例如的SrTiO ₃，Ce的_0.9的Gd _0.1 ø _1.95，和La _0.6锶_0.4铁_0.8钴_0.2 ö _{3- δ} ; 对于具有部分填充的导带的氧化物（例如La _1−），发现了一个类似的表达式_一个高级_一个的CoO _{3- δ}和（BA _0.5锶_0.5）（CO _0.8的Fe _0.2）O _{3- δ}。两种类型的氧化物都认为导带电子在确定氧表面交换速率中起着中心作用。