Luminescent properties of trivalent praseodymium-doped lanthanum aluminum germanate LaAlGe2O7

The luminescent characteristics of Pr3+-activated LaAlGe2O7 were investigated. In response to excitement using 448 nm blue light, the emission spectra involved most of the 3P0→3HJ transitions. The dominant emission came from the 3P0→3H4 transition at 487 nm. 1D2 fluorescence quenching was observed in highly doped samples and is related to the cross-relaxation processes among neighboring Pr3+ ions. In contrast with conventional Pr3+-activated phosphors, the extraordinary excitation spectra showed only intense f–f transition of Pr3+ ions, while the 4f–5d transition was eliminated. This is ascribed to photoionization. By analyzing absorption and excitation spectra, it is recognized that no efficient energy transfer occurs between Pr3+ and the host lattice in LaAlGe2O7.