First principles study on the structural, magnetic and electronic properties of Co-doped FeF3

To better understand the effects of Co-doping on the crystal and electronic structures of FeF3, the theoretical studies of three types of doped models (CoFe5F18, Co2Fe4F18, and Co3Fe3F18) have been carried out by means of first principles method based on density functional theory. It is found that the stability of Co-doped FeF3 decreases with the increase of Co-doping concentration. And Co doping does not impair the crystal structure of FeF3, but it can make G-type anti-magnetic structure of FeF3 convert into metamagnetism structure. Besides, the band gap of FeF3 decreases via Co doping, and the conductivity of the Co doping FeF3 compounds can be improved, thus indicating a high discharge specific capacity when the Co doping FeF3 compounds are used as cathode material of lithium ion batteries.