White light emitting Sr₃YNa(PO₄)₃F: Dy3+, Eu3+ fluorapatite phosphor with tunable correlated color temperature

Abstract Dy 3+ and Eu 3+ doped Sr 3 YNa(PO 4 ) 3 F fluorapatite phosphors were synthesized using a solid-state reaction method. The structural, morphological and luminescence properties of the individually doped and codoped phosphors were studied. The photoluminescence (PL) spectra of Sr 3 YNa(PO 4 ) 3 F: Eu 3+ phosphor showed red emission lines due to the 4f-4f transitions, while that of Sr 3 YNa(PO 4 ) 3 F: Dy 3+ phosphor showed dual emissions in the blue and yellow regions. Although Dy 3+ -emissions are supposed to produce white light emission, the quality of the white light is compromised due to the poor color rendering index (CRI) occurring from the absence of the red component. This issue was addressed by codoping Eu 3+ and Dy 3+ ions in the Sr 3 YNa(PO 4 ) 3 F host and achieving emission lines in the blue, yellow and red regions of the visible light spectrum. By tuning the Dy 3+ /Eu 3+ concentration ratios, the correlated color temperature (CCT) of the white light was tuned from cool-white to warm-white. Moreover, the codoping of Dy 3+ and Eu 3+ resulted in improving the CRI of the phosphor. The results suggest that Sr 3 YNa(PO 4 ) 3 F: Dy 3+ , Eu 3+ phosphor is a potential candidate for solid-state lighting applications.