First-principles description of oxygen self-diffusion in rutile TiO 2 : assessment of uncertainties due to enthalpy and entropy contributions
First-principles description of oxygen self-diffusion in rutile TiO 2 : assessment of uncertainties due to enthalpy and entropy contributions
复制标题
金红石 TiO 2 中氧自扩散的第一性原理描述：评估因焓和熵贡献引起的不确定性
DOI：
10.1039/c8cp02741b
复制
发表时间：
2018
影响因子：
3.3
通讯作者：
Ertekin, Elif
中科院分区：
文献类型：
--
作者：
Jeong, Heonjae;Seebauer, Edmund G.;Ertekin, Elif
与传输相关的特性，如自扩散系数与燃料电池、电解电池和化学/气体传感器有关。从第一性原理预测自扩散系数涉及到对点缺陷形成和迁移的焓和熵贡献的精确测定。我们利用第一性原理密度泛函理论估计了中性O0i和双电离Oi2−间隙氧在金红石TiO2中的自扩散系数，并将结果与先前的同位素扩散实验结果进行了比较。除了形成和迁移能之外，还包括了包含振动和电离成分的形成和迁移熵的详细估计。基于间质机制，O0i和Oi2−被确定为不同的迁移途径。这导致自扩散系数相差几个数量级，足以在实验中分辨出扩散物质的电荷状态为Oi2−。将计算参数与实验参数进行比较时，考虑了误差的主要来源，表明由计算缺陷形成和迁移熵引起的不确定性与由计算缺陷形成和迁移能引起的不确定性在量级上相当。即便如此，复合不确定性似乎将第一性原理计算的精度限制在±103的范围内，这表明计算和实验之间的直接联系现在越来越有可能。
Properties related to transport such as self-diffusion coefficients are relevant to fuel cells, electrolysis cells, and chemical/gas sensors. Prediction of self-diffusion coefficients from first-principles involves precise determination of both enthalpy and entropy contributions for point defect formation and migration. We use first-principles density functional theory to estimate the self-diffusion coefficient for neutral O0i and doubly ionized Oi2− interstitial oxygen in rutile TiO2 and compare the results to prior isotope diffusion experiments. In addition to formation and migration energy, detailed estimates of formation and migration entropy incorporating both vibrational and ionization components are included. Distinct migration pathways, both based on an interstitialcy mechanism, are identified for O0i and Oi2−. These result in self-diffusion coefficients that differ by several orders of magnitude, sufficient to resolve the charge state of the diffusing species to be Oi2− in experiment. The main sources of error when comparing computed parameters to those obtained from experiment are considered, demonstrating that uncertainties due to computed defect formation and migration entropies are comparable in magnitude to those due to computed defect formation and migration energies. Even so, the composite uncertainty seems to limit the accuracy of first-principles calculations to within a factor of ±103, demonstrating that direct connections between computation and experiment are now increasingly possible.