Authors: Na Yuan Xiaojuan Liu Fanzhi Meng DeFeng Zhou Jian Meng
Publish Date: 2014/11/29
Volume: 21, Issue: 6, Pages: 1675-1681
Abstract
La2CoMnO6 has attracted intensive research interest because of its prospect for novel technological applications and rich fundamental physics And due to the similar radii size as well as small covalent difference as large as 2 between Co and Mn cation disorder should be intrinsic within this perovskite We performed comprehensive firstprinciples calculations on both La2CoMnO6 LCMO and LCMO with CoMnMnCo antisite defects ADLCMO focusing on the formation of bulk oxygen vacancies which plays a key role in oxygen ion diffusion process in solid oxide fuel cell SOFC electrodes First it is found that the covalent states are 2 and +4 for Co and Mn at their regular sites while they are both prone to be +3 in the antisites The formation energies for oxygen vacancies are predicted to follow the trend Co2+OMn4+ Co2+OCo3+ Mn3+OMn4+ and the underlying microscopic mechanism is attributed to the more electron delocalization between mixedcovalent transition metals Co2+OCo3+ and Mn3+OMn4+ which is beneficial to diminish the electronic repulsion and help to stabilize the vacancy Therefore we could conclude that oxygen ionic conductivity should be enhanced in the compounds with higher degree of cation disorder Our results indicate that ADLCMO should be a promising intermediatetemperature solid oxide fuel cell cathode materialBased on firstprinciples calculations we studied ordered LCMO as well as LCMO with CoMnMnCo antisite defects ADLCMO First it was found that the covalent states are +2 and +4 for Co and Mn at regular sites while they are both prone to be +3 in the antisites The formation energies for oxygen vacancies are predicted to follow the trend Co2+OMn4+ Co2+OCo3+ Mn3+OMn4+ and the underlying microscopic mechanism for this trend is attributed to the more delocalization of the electrons within ADLCMO due to the mixedcovalent transitionmetal pairsThis work was supported by the National Natural Science Foundation of China under grant Nos 51002148 20921002 and 21471002 and Natural Scientific Foundation of Jilin Province 20130101016JC and the Jilin Provincial Science Research Foundation of China No 20101549
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