Luminescence Centers of MgS, CaS and CaSe Phosphors Activated with Eu²⁺ Ion

Emission and excitation spectra of Eu 2+ ions incorporated in MgS, CaS and CaSe were measured at temperatures 300, 80 and 6 K. Both spectra are interpreted as due to the allowed transition between the Eu 2+ ion's ground state ( 8 S 7/2 ) of 4f 7 configuration and the excited states of 4f 6 5d configuration, together with the forbidden transition arising from the configuration interaction between 4f 6 5d and4f 6 6s. From the observed excitation spectra for CaS: Eu 2+ and CaSe: Eu 2+ phosphors, \(⁸₄(t2g)\)-, \(⁸₃(eg)\)-bands were assigned for lower concentrations of Eu 2+ ion; besides these bands \(⁸₁(6s)\)- and \(⁶₄(t2g)\)-bands were assigned for higher concentrations of Eu 2+ ion. From the assigned \(⁸₄(t2g)\)- and \(⁸₃(eg)\)-bands, it has been found that 10 D q for MgS, CaS and CaSe are 19500 cm -1 , 18750 cm -1 and 17300 cm -1 , respectively.