The conduction band of the lanthanide doped chromium disulfides CuCr0.99Ln0.01S2 (Ln=La, Ce, Gd): XANES investigations

The comprehensive experimental and theoretical study of the cation-substituted disulfides CuCr0.99Ln0.01S2 (Ln=La, Ce, Gd) XANES spectra was carried out. The cationic substitution with lanthanide atoms affect to the conduction band structure was studied using the finite difference method, DFT calculations of conduction band structure and the experimental spectra interpretation. The conduction band bottom of CuCrS2 is formed mainly with the contribution of the mixed copper s-, p- and d-states, chromium d-states and sulfur p-states. After the cationic substitution the unoccupied lanthanide f-states localize near the conduction band bottom area replacing the chromium d-states. The unoccupied copper, chromium and sulfur states distribution character is preserved after cationic substitution. In the case of solid solutions CuCr1-xLaxS2 the lanthanum f−states main contribution is shifted into the high energy area from the conduction band bottom.