Energy Transfer between Tb(3+) and Eu(3+) in LaPO(4): Pulsed versus Switched‐off Continuous Wave Excitation

The energy transfer (ET) between Tb(3+) and Eu(3+) is investigated experimentally and with available theoretical models in the regime of high Tb(3+) concentrations in ≈30 nm LaPO(4) nanoparticles at room temperature. The ET efficiency approaches 100% even for lightly Eu(3+)‐doped materials. The major conclusion from the use of pulsed laser excitation and switched‐off continuous wave laser diode excitation is that the energy migration between Tb(3+) ions, situated on La(3+) sites with ≈4 Å separation, is not fast. The quenching of Tb(3+) emission in singly doped LaPO(4) only reduces the luminescence lifetime by ≈50% in heavily doped samples. Various theoretical models are applied to simulate the luminescence decays of Tb(3+) and Tb(3+), Eu(3+)‐doped LaPO(4) samples of various concentrations and the transfer mechanism is identified as forced electric dipole at each ion.