First-principles study of point defect diffusion in CoMn2O4 crystal

The conductivity of spinel coating on metallic interconnects is of great significance for solid oxide fuel cells. Here, we develop a thorough theoretical study on the point defect diffusion based on first-principles calculations that reveals the conduction mechanism of a CoMn2O4 spinel crystal. Defect models that use three types of va-cancies and five types of interstitial atoms of Co, Mn, and O, are proposed and optimized. The energy barriers for diffusion of the vacancies, interstitial atoms and cascade reactions are calculated and analyzed. The diffusion pathways across the entire crystal are established. From the calculation of the corresponding diffusion co-efficients, it is found that the mobility of O atomic defect is higher than that of Co defect, and that of the Mn defect is the lowest. Our results reveal that the conductivity of a CoMn2O4 crystal may mainly depend on diffusion of interstitial O atoms and O vacancies. Therefore, our study suggests that the conductivity of CoMn2O4 spinel crystal may be improved by increasing the concentration of O atomic defects. The obtained activation energies and diffusion coefficients can provide theoretical support to the related experiments.

Automated summary

In this study, a thorough theoretical investigation on the diffusion of point defects in a CoMn2O4 spinel crystal was conducted based on first-principles calculations. The proposed defect models, including three types of vacancies and five types of interstitial atoms, were optimized and the energy barriers for diffusion were calculated and analyzed. It was found that the mobility of O atomic defect is higher than that of Co defect, and that of the Mn defect is the lowest. The results suggest that the conductivity of a CoMn2O4 crystal may depend on the diffusion of interstitial O atoms and O vacancies, and increasing the concentration of O atomic defects could improve the conductivity. The obtained activation energies and diffusion coefficients can provide theoretical support for related experiments.