(639d) Theoretical Investigation of the Electronic, Optical and Thermodynamic Properties of LaxSr1-XCoyFe1-YO3-? (x, y =0.0 ~ 1.0) Perovskites | AIChE

(639d) Theoretical Investigation of the Electronic, Optical and Thermodynamic Properties of LaxSr1-XCoyFe1-YO3-? (x, y =0.0 ~ 1.0) Perovskites

Authors 

Jia, T. - Presenter, National Energy Technology Laboratory
Hao, H., Institute of Solid State Physics
Ohodnicki, P. R., National Energy Technology Laboratory
Chorpening, B. T., National Energy Technology Laboratory
Hackett, G., National Energy Technology Laboratory
Zeng, Z., Institute of Solid State Physics, Chinese Academy of Sciences
Duan, Y., National Energy Technology Laboratory
The development of high temperature gas sensors for industrial applications is essential to improve energy efficiency and reduce toxic emissions. However, gas sensors operating at high temperatures encounter many challenging issues, such as thermal and long-term stability, sensitivity, reproducibility and selectivity. Sensing processes at such high temperatures are complicated and have not well understood. Hence, theoretical modeling could play a role to explore the sensing mechanisms and support experimental development of practical sensor devices. The perovskites in the form of ABO3 (A=alkaline-earth metal or La, B=3d transition metal) are good candidates as high temperature sensor materials. In this study, the electronic, optical and thermodynamic properties of LaxSr1-xCoyFe1-yO3-δ (x, y = 0.0 - 1.0) are investigated using density functional theory calculations. The obtained results showed that pure SrMO3 (M=Co, Fe) are metals, while LaMO3 are insulators and all of them exhibit strong hybridization of the Fe/Co-3d and O-2p orbitals. By correlating the energy band structures with the peaks of the imaginary part of the dielectric function, we obtained that the origin of each electron excitation provides information about the active bands for the corresponding optical transitions observed in the experiment. By exploring the influence of O vacancy on their optical properties, we found that there are extra optical absorption peaks from vacancy-level transition for LaMO3 insulators, however, the O vacancy has little influence on the optical properties of SrMO3 metals. The optical absorption coefficients of LaMO3 are very different for their high and low temperature phases. We also found that the optical absorption coefficients of SrMO3 are influenced by the electronic correlation. The calculated thermodynamic properties versus temperatures are in good agreement with the available experimental data. Our results showed that the properties of pure LaMO3 could be adjusted or enhanced for specific applications by chemical doping, hence, the doped LaxSr1-xFeyCo1-yO3 systems could possess improved performance and are under exploration.

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