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