Dopant arrangements in Y-doped BaZrO3 under processing conditions and their impact on proton conduction: a large-scale first-principles thermodynamics study
Dopant arrangements in Y-doped BaZrO3 under processing conditions and their impact on proton conduction: a large-scale first-principles thermodynamics study
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DOI：
10.1039/d0ta01741h
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发表时间：
2020-07-07
影响因子：
11.9
通讯作者：
Kuwabara, Akihide
中科院分区：
文献类型：
--
作者：
Kasamatsu, Shusuke;Sugino, Osamu;Kuwabara, Akihide
钇掺杂的BaZrO_3是一种离子导体，在中温固体氧化物燃料电池中的应用正处于激烈的研究之中。电导率在类似于20%掺杂时最大化，并且随着进一步掺杂的降低通常归因于缔合效应或掺杂剂对离子电荷载流子的捕获。这似乎是一个合理的推测，因为掺杂剂和载流子以相反的极性带电，并且应该相互吸引。然而，在如此高的掺杂浓度下，附近的掺杂剂和载流子之间的多体相互作用可能会修改这样一个简单的两体吸引图。因此，在这项工作中，我们采用了大规模的第一性原理热力学采样方案，直接检查的配置掺杂剂和电荷补偿缺陷在现实的掺杂浓度下的加工条件。我们发现，虽然有，确实，在所有的掺杂浓度检查一个clearassociation效应，效果的大小实际上随着掺杂剂浓度的增加而减少。我们还发现，相互作用不能简单地理解为两体库仑吸引力和排斥力，突出了多体效应在理解重掺杂氧化物中的缺陷化学的重要性。最后，我们研究了掺杂剂的配置，并成功地解释了电导率最大值的基础上，最近得到了关注的多体捕获的图片。
Y-doped BaZrO3 is an ion conductor under intense research for application in medium temperature solid oxide fuel cells. The conductivity is maximized at similar to 20% doping, and the decrease with further doping has often been attributed to the association effect, or the trapping of ionic charge carriers by the dopant. This seems like a reasonable conjecture since the dopant and carrier are charged in opposite polarities and should attract each other. However, at such high doping concentrations, many-body interactions between nearby dopants and carriers are likely to modify such a simple two-body attraction picture. Thus, in this work, we employ a large-scale first-principles thermodynamic sampling scheme to directly examine the configuration of dopants and charge-compensating defects at realistic doping concentrations under processing conditions. We find that although there is, indeed, a clearassociation effect at all doping concentrations examined, the magnitude of the effect actually decreases with increasing dopant concentration. We also find thatinteractions cannot simply be understood in terms of two-body Coulomb attraction and repulsion, highlighting the importance of many-body effects in understanding the defect chemistry in heavily doped oxides. Finally, we examine the dopant configurations and successfully explain the conductivity maximum based on a percolationvs.many-body trapping picture that has gained attention recently.