Dynamical processes of energy transfer in red emitting phosphor CaMoO_4:Sm~(3+), Eu~(3+)

摘要

Upon ~4K_(11/2) excitation of Sm~(3+) at 405 nm, the performance of energy transfer from Sm~(3+) to Eu~(3+) in the red emitting phosphor CaMoO_4:Eu~(3+), Sm~(3+) significantly extends its excitation region for better matching the near-UV LED. Photoluminescence spectra indicate that the energy transfer pathway concerns the relaxation from ~4K_(11/2) to ~4G_(5/2) of Sm~(3+)and subsequent transfer to ~5D_0 of Eu~(3+) rather than ~5D_1 ofEu~(3+). The fluorescent decay pattern of Sm~(3+) ~4G_(5/2) level in CaMoO_4:0.5% Sm~(3+), 2% Eu~(3+) is studied at 77 K based on the Inokuti-Hirayama formula, revealing an electronic dipole-dipole interaction between Sm~(3+) and Eu~(3+). The coefficient for the energy transfer is obtained to be 8.5 × 10~(-40)s~(-1) cm~6. The fluorescence rise and decay pattern of Eu~(3+) ~5D_0 level as Sm~(3+) is only excited at 77 K is well described by the dynamical processes of the energy transfer.