Luminescence centers in CaS:Er3+

The diffuse reflectance, photoexcitation, and luminescence spectra and luminescence decay time of CaS:Er³⁺ have been measured at 77 and 300 K and different activator contents. The absorption and luminescence bands due to Er³⁺ centers and native defects have been revealed, and the radiative electronic transitions between excited and ground Er³⁺ states have been identified. The characteristic decay times of the Er^{3+ 2} H _11/2 and ⁴ F _9/2 states in CaS have been determined, and radiative energy transfer from excited states of native defects to erbium ions in CaS:Er³⁺ has been revealed.