Abstract To design the material rationally, we predict the effect of oxygen vacancy on the material bandgap and electron state density based on the first principle density functional theory. Crystal structure, electronic properties, as well as the oxidation and reduction states of Gd0.8Ca0.2BaCo2O5+δ oxides were studied by GGA-PBE+U calculation. By changing one oxygen atom in the Gd-O0.5 plane of supercell, Gd0.8Ca0.2BaCo2O5.25 and Gd0.8Ca0.2BaCo2O5.75 were created. And they show half-metallic and metallic properties respectively, which is related to the strong electronic correlations for 3d orbitals of Co. Calculation results of partial density of states suggest that O-2p and Co-3d orbits have a great effect on the band gap of Gd0.8Ca0.2BaCo2O5.5, and the location of cobalt may be an active site. Besides, Gd0.8Ca0.2BaCo2O5+δ were prepared and annealed in atmosphere to regulate the oxygen vacancy content. Hence, a deep and systematic study on Gd0.8Ca0.2BaCo2O5+δ was conducted based on theoretical calculations and experiments, including crystal structure, electron distribution and oxygen vacancy. Differing from the conventional doping modification to adjust the electronic energy band structure, this work is dedicated to synthesizing the stable and efficient materials from the theoretical design, which providing a new feasible thought for the efficient and stable material design.

中文翻译：

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用于光催化应用的 Gd 0.8 Ca 0.2 BaCo 2 O 5+δ 双钙钛矿的带隙工程

摘要 为了合理设计材料，我们基于第一性原理密度泛函理论预测了氧空位对材料带隙和电子态密度的影响。通过GGA-PBE+U计算研究了Gd0.8Ca0.2BaCo2O5+δ氧化物的晶体结构、电子性质以及氧化还原态。通过改变超胞 Gd-O0.5 平面上的一个氧原子，产生了 Gd0.8Ca0.2BaCo2O5.25 和 Gd0.8Ca0.2BaCo2O5.75。它们分别表现出半金属和金属特性，这与 Co 3d 轨道的强电子相关性有关。 部分态密度的计算结果表明 O-2p 和 Co-3d 轨道对带隙有很大影响Gd0.8Ca0.2BaCo2O5.5 和钴的位置可能是一个活性位点。此外，Gd0.8Ca0. 制备 2BaCo2O5+δ 并在气氛中退火以调节氧空位含量。因此，基于理论计算和实验，包括晶体结构、电子分布和氧空位，对 Gd0.8Ca0.2BaCo2O5+δ 进行了深入和系统的研究。不同于传统的掺杂改性来调整电子能带结构，这项工作致力于从理论设计合成稳定高效的材料，为高效稳定的材料设计提供了新的可行思路。