Site occupancy and tunable luminescence of Eu²⁺ and Eu³⁺ coactivated KCaY (PO₄)₂:Eu phosphors

Utilizing the structure characteristic of KCaY (PO 4 ) 2 crystal, the site distribution of Eu 2+ in KCaY (PO 4 ) 2 :Eu phosphor coactivated with Eu 2+ and Eu 3+ ions is tuned. Upon 393‐nm excitation, the as‐prepared phosphor exhibits a broadband emission of Eu 2+ peaked at ~ 475 nm and a typical red emission of Eu 3+ with a strong 5 D 0 – 7 F 1 emission at ~ 591 nm. The luminescence color of the phosphor can be adjusted from blue to green, white, yellow, and red. The increasing concentration of Sr 2+ and Eu 2+ results in a blue shifting of Eu 2+ emission. The increasing concentration of Eu 3+ results in a red shifting of Eu 2+ emission and an enhanced red emission of Eu 3+ . The luminescence behaviors of the phosphors are analyzed in terms of the site distribution of Eu 2+ and Eu 3+ . A single‐phase white light emitting was achieved in KCaY (PO 4 ) 2 :Eu phosphor upon UV and NUV light excitation, indicating that the phosphor has potential application in white lighting.