Density functional theory study of the structure and properties of C-doped pyrite

The structure and properties of C-doped pyrite are investigated by first-principles density functional theory. The results show that interstitial doping system is more stable than substitutional doping system. With the increase of carbon concentration, the hardness of interstitial C-doped pyrite decreases and the oxidizability increases, leading to the difficulty of coal-pyrite depression in coal flotation. After C doped in an interstitial lattice site the impurity states reduce the band gap and lead to the red-shift of absorption edge. C-doping improves the optical transition characteristics of pyrite electrons in visible light region.