Comparative study on spectral characteristics of Cr²⁺: ZnS and Fe²⁺: ZnS

Based on the density functional theory and projector augmented wave (PAW) method, a comparative study on the electronic structure and absorption spectra of Cr2+: ZnS and Fe2+: ZnS were carried out. Perdew, Burke, and Ernzerhof (PBE) function was employed for band structure calculation and geometry optimization of divalent ions in crystal. Absorption spectra of Cr2+: ZnS and Fe2+: ZnS show that the characteristic absorption is caused by local excitation from d to p-d hybrid orbitals and the central transition energy in Fe2+: ZnS is lower than in the Cr2+: ZnS, with a value of 0.34 eV. Cr2+: ZnS and Fe2+: ZnS were prepared and the absorption spectra were measured. It is proved that a red shift of 0.34 eV exists in characteristic absorption peaks of Fe2+: ZnS compared to Cr2+: ZnS.