Investigation of energy transfer in Pr3+, Yb3+ co-doped phosphate phosphor: The role of 3P0 and 1D2

Abstract

The synthesis, crystal structure and photoluminescence and decay kinetics properties have been carried out for the Pr3+-Yb3+ co-doped YPO4 phosphors. Upon excitation with 447 nm, the intense emissions from 3P0, 1D2 and 1G4 excited states are all observed in the Pr3+ singly doped phosphors. The population of 1D2 state is attributed to cross-relaxation 3P0+3H4 → 1D2+3H6 and/or non-radiative multiphonon relaxation from 3P0 because of the larger maximum phonon energy of YPO4 host (1080 cm−1),which needs only 3–4 phonons to balance the energy gap between 3P0 and 1D2 excited states. For the Pr3+-Yb3+ codoped samples, the effect of Yb3+ concentration on the luminescence and decay kinetics of Pr3+ are investigated for the interpretation of observed experimental results. The observations and discussions manifest that the efficient energy transfer from Pr3+ to Yb3+ occurs, involving mainly 1D2 and 1G4 levels of Pr3+ ions instead of 3P0 level, which is not in accordance with many reported results. It is hoped that our results may give a new insights into the energy transfer mechanism in Pr3+-Yb3+ codoped system.