When CaS:Sm3+, Eu2+ is excited at 476.5 nm (Ar+), the emission spectra take
n at room temperature and at 77 K are different, indicating that there are
two competitive energy transfer processes-Sm3+ --> Eu2+ and Eu2+ --> Sm3+ w
ith phonon participation. So, the luminescence intensity of Sm3+ increases
first, and then decreases as the concentration of Eu2+ is increasing. (C) 2
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