Color tunable emission and energy transfer in Eu2+, Tb3+, or Mn2+-activated cordierite for near-UV white LEDs

Abstract

Emission-tunable Mg₂Al₄Si₅O₁₈:Eu²⁺, Mn²⁺ and Mg₂Al₄Si₅O₁₈:Eu²⁺, Tb³⁺ cordierite phosphors have been synthesized by a high-temperature solid-state reaction technique. Photoluminescence and energy transfer in Mg₂Al₄Si₅O₁₈:Eu²⁺, Mn²⁺ occur via a resonance-type dipole–quadrupole interaction mechanism, and the critical distance of the energy transfer is calculated to be 11.1 A. We found that the emission colors could be tuned from blue (0.19, 0.26) to white (0.41, 0.37) via the energy transfer of Eu²⁺ → Mn²⁺ and from blue to green (0.28, 0.45) via the energy transfer of Eu²⁺ → Tb³⁺. The green emission is realized in the Mg₂Al₄Si₅O₁₈:Eu²⁺, Tb³⁺ phosphors on the basis of the highly efficient energy transfer from the Eu²⁺ to Tb³⁺ ions. Finally, the color tunable emission with varied hues has been obtained in Eu²⁺, Tb³⁺, or Mn²⁺ activated Mg₂Al₄Si₅O₁₈ phosphors, making them potential emission-tunable phosphors for near-UV LEDs.