Luminescence properties of multicolor emitting La4GeO8:Tb3+,Eu3+ phosphors

Tb3+ and Eu3+ doped La4GeO8 multicolor emitting phosphors were synthesized. A systematic investigation was done into the photoluminescence properties of La4GeO8:Tb3+,Eu3+. Energy transfer from trivalent terbium to europium ions in La4GeO8 results from quadrupole-quadrupole interaction. The variable temperature emission spectra ranging from 303 to 513 K were used to demonstrate the thermal stability of La4GeO8:0.07Tb3+,0.01Eu3+ phosphor. The obtained activation energies for trivalent terbium and europium ions were 0.186 eV and 0.187 eV, separately. By altering the content ratio of Eu3+ to Tb3+, the La4GeO8:Tb3+,Eu3+ phosphors can achieve multicolor luminescence and tunable chromaticity from green (0.3416, 0.5423) to red (0.6479, 0.349) under 265 nm light excitation. The findings suggest that La4GeO8:Tb3+,Eu3+ are promising phosphors for solid-state lighting application.