A novel tunable Na2Ba6(Si2O7)(SiO4)2:Ce3+,Mn2+ phosphor with excellent thermal stability for white light emitting diodes

Abstract

In this paper, Ce³⁺ doped and Ce³⁺,Mn²⁺ co-doped Na₂Ba₆(Si₂O₇)(SiO₄)₂ phosphors were synthesized via a high temperature solid-state reaction. The Rietveld refinement analysis of the X-ray diffraction patterns confirmed the formation of the single phase of Na₂Ba₆(Si₂O₇)(SiO₄)₂. The PL spectrum of the Ce³⁺ single-doped phosphor shows a broad asymmetric band extending from 350 to 600 nm peaking at 420 nm under the excitation of UV light. Also, the low temperature (5 K) PL spectrum shows clearly three peaks at 375, 420, and 451 nm, which is in accordance with the Ce³⁺ ion site in the host. The Ce³⁺,Mn²⁺ co-doped phosphors show a blue emission band and an orange emission band, and the corresponding CIE coordinates intuitively indicate the tunable colors from the blue to green area. And the energy transfer mechanism from Ce³⁺ to Mn²⁺ in the host has been verified to be a dipole–quadrupole interaction. In addition, the emission intensity of Na₂Ba₆(Si₂O₇)(SiO₄)₂:0.01Ce³⁺ phosphor slightly changed with the temperature increase from 300 to 450 K, revealing that the obtained phosphor possesses an excellent thermal stability, which makes it an attractive candidate phosphor for white lighting emitting diodes.