Synthesis and color-tunable luminescence properties of Eu2+ and Mn2+-activated Ca3Mg3(PO4)4 phosphor for solid state lighting

Abstract

Eu²⁺ and Mn²⁺ singly doped and Eu²⁺/Mn²⁺-co-doped Ca₃Mg₃(PO₄)₄ phosphors are prepared by the conventional solid-state method. The Ca₃Mg₃(PO₄)₄:Eu²⁺,Mn²⁺ phosphors are efficiently excited at wavelengths ranging from 200 to 430 nm, which can match well with near ultraviolet (UV) light emitting diode (LED) chips. As a result of fine-tuning of the emission composition of the Eu²⁺ and Mn²⁺ ions, white light emission can be realized by combining the emission of Eu²⁺ and Mn²⁺ in a single host lattice under UV light excitation. Resonant energy transfer with an efficiency value of over 90% from the Eu²⁺ to Mn²⁺ ions is demonstrated to be in the dipole-quadrupole mechanism in such system and the energy transfer efficiency increases with an increase of the Mn²⁺ doping content, which is confirmed by the luminescence spectra and fluorescence decay curves, respectively. The energy transfer critical distance has been calculated and evaluated by both the concentration quenching and spectral overlap methods. These results indicate that the Ca₃Mg₃(PO₄)₄:Eu²⁺,Mn²⁺ phosphors have potential applications as a near UV-convertible phosphor for light-emitting diodes because of its broad excitation in the near-ultraviolet range and the efficient emission light.