A study on luminescence properties and energy transfer mechanism for NaCaY(PO_4)_2:Eu^2+,Mn^2+ phosphors for LED applications

Abstract

A color-tunable NaCaY(PO₄)₂:Eu²⁺,Mn²⁺, was synthesized by a solid state reaction. NaCaY(PO₄)₂ crystallizes in the hexagonal structure system with space group of P6₂22 and Z = 1. The NaCaY(PO₄)₂:Eu²⁺ exhibits blue-greenish emission and broad excitation bands corresponding to the allowed f→d electronic transition of Eu²⁺. In addition, via the design of efficient energy transfer from Eu²⁺ to Mn²⁺, a high quality of white-emitting light could be generated in the optimized composition of NaCaY(PO₄)₂:1%Eu²⁺, 0.5%Mn²⁺ with CIE coordinates of (0.3389,0.3531) and CRI of 82, which is superior than that of blue chip and YAG phosphors. The results indicate that as-synthesized NaCaY(PO₄)₂:Eu²⁺,Mn²⁺ phosphors exhibits the potential to be an n-UV convertible phosphor.