Color-tunable Eu2+,Eu3+ co-doped Ca20Al26Mg3Si3O68 phosphor for w-LEDs

Abstract

A series of promising color-tunable Ca₂₀Al₂₆Mg₃Si₃O₆₈ (CAMSO):Eu phosphors have been synthesized by a high-temperature solid-state method. Both Eu²⁺ and Eu³⁺ ions exist in this system despite the samples prepared in a reducing atmosphere. This phenomenon was discussed according to the thermal stability of the samples and the change of the local structure with Eu²⁺ ion doping. Furthermore, the multiple emissions of the Eu²⁺ ion in the CAMSO:Eu phosphors arise from Eu²⁺ ions at distinct crystallographic sites. The low-temperature emission spectra were investigated in detail by Gaussian peak parting to ascertain the site occupation of the Eu²⁺ ions. LEDs were fabricated using the CAMSO:xEu (x = 0.1, 0.2, 0.4, and 0.6) with 380 nm chips. The emission color could be tuned continuously from blue to yellow by increasing the concentration of Eu ions. A higher color rendering index (R_a > 80) and a broader color gamut could be achieved, indicating the promising application potential of the CAMSO:Eu phosphors for white LEDs.