The influence of oxygen vacancy on the electronic and optical properties of ABO3-δ (A = La, Sr, B = Fe, Co) perovskites.
The influence of oxygen vacancy on the electronic and optical properties of ABO3-δ (A = La, Sr, B = Fe, Co) perovskites.
复制标题
DOI：
10.1039/c9cp03883c
复制
发表时间：
2019-09
期刊：
影响因子：
--
通讯作者：
T. Jia;Z. Zeng;Xiaoli Zhang;P. Ohodnicki;B. Chorpening;Gregory A. Hackett;Jonathan W. Lekse;Y. Duan
中科院分区：
文献类型：
--
作者：
T. Jia;Z. Zeng;Xiaoli Zhang;P. Ohodnicki;B. Chorpening;Gregory A. Hackett;Jonathan W. Lekse;Y. Duan
ABO3-δ（A = La、Sr、B = Fe、Co）钙钛矿具有广泛的应用，包括最近在固体氧化物燃料电池等能量转换装置的高温光学氧传感中的应用探索。为了阐明功能特性和氧空位形成对缺陷化学和成分的依赖性，提出了第一原理计算。结果表明，氧空位（VO）形成能的顺序为LaFeO3 > LaCoO3 > SrFeO3 > SrCoO3。此外，还研究了高温稳定相（T = 1100 K）中 VO 对电子和光学性质的影响。对于 LaFeO3 绝缘体，VO 提供的电子都集中在最近的 Fe 离子的下自旋 d3z2-r2 轨道上。这些位于带隙中的缺陷态导致原始吸收能量开始下降→V2+O→V1+O→V0O，特别是，由于V0O和V1+O的形成，在0.5和1.5 eV之间出现了额外的吸收峰。在其余表现出金属特征的晶体中，VO 提供的电子部分局域于下自旋 d3z2-r2 轨道，部分通过晶格离域，从而增强了费米能级附近电子激发的吸收峰（LaCoO3 为 0.5-2.0 eV，SrFeO3 和 SrCoO3 为 0.0-0.5 eV）。 SrFeO3 和 SrCoO3 中氧双空位的高 VO 浓度可以增强下自旋 d3z2-r2 轨道上的电荷定位，从而导致 1.5-3.0 eV 处的光学吸收显着增加。
ABO3-δ (A = La, Sr, B = Fe, Co) perovskites are useful in a wide range of applications, including their recent exploration for application in high-temperature optical oxygen sensing for energy conversion devices such as solid oxide fuel cells. To elucidate the dependence of functional properties and oxygen vacancy formation on defect chemistry and composition, first principles calculations are presented. The obtained results show that oxygen vacancy (VO) formation energies are in the order of LaFeO3 > LaCoO3 > SrFeO3 > SrCoO3. Furthermore, the influence of VO on the electronic and optical properties is investigated for the high temperature stable phases (T = 1100 K). For the LaFeO3 insulator, the VO donated electrons are all localized on the down-spin d3z2-r2 orbitals of the nearest Fe ions. These defect states located in the band gap induce a drop in the energy onset of absorption as pristine bulk → V2+O → V1+O → V0O, and especially, an extra absorption peak appears between 0.5 and 1.5 eV due to V0O and V1+O formation. In the rest of the crystals that expressed a metallic feature, the VO donated electrons partially localize on the down-spin d3z2-r2 orbital and partially delocalize through the lattice, by which the absorption peaks (0.5-2.0 eV for LaCoO3, 0.0-0.5 eV for SrFeO3 and SrCoO3) from the electronic excitation near the Fermi level are enhanced. A high VO concentration of oxygen divacancy in SrFeO3 and SrCoO3 could enhance charge localization on down-spin d3z2-r2 orbitals, resulting in a remarkable increase of optical absorption at 1.5-3.0 eV.