Effects of (Mo/W, N) codoping on electronic structures of NaNbO3 based on hybrid density functional calculations

Abstract

The influences of a series of (N, Mo, W) monodoping and N–Mo(W) codoping on the electronic structures of sodium niobate have been systematically investigated by density functional theory (DFT) calculations with the hybrid B3LYP functional. The results indicated that some localized N 2p states were formed above the top of valence band (VB) after N-doping. In the case of Mo(W)-doping, the position of VB shifted up, meanwhile, the hybridization of Nb 4d and Mo 4d(W 5d) states moved the conduction band (CB) downward, leading to narrowing the band gap. As for N–Mo codoped NaNbO3, the localized Mo 4d states were formed near the bottom of CB while the localized N 2p states appeared above the top of VB. When N–W codoping, the W 5d p states mixed with Nb 4d states and then moved the top of CB downward as well as some localized N 2p states were formed above the valence band (O 2p), leading to the obvious reduction of the photon transition energy compared with that of NaNbO3.