Improving the luminescence properties and powder morphologies of red-emitting Sr0.8Ca0.19AlSiN3:0.01Eu2+ phosphors for high CRIs white LEDs by adding fluxes

Red-emitting Sr 0.8 Ca 0.19 AlSiN 3 :0.01Eu 2+ phosphor with halide fluxes for use in the production of white light-emitting diodes (white LEDs) with high-colour rendering indices (CRIs) was prepared through the high-temperature solid-state method. Fluoride (NaF, SrF 2 , BaF 2 , CaF 2 , AlF 3 ·3H 2 O and CeF 3 ), chloride (NH 4 Cl, BaCl 2 , MgCl 2 , NaCl and LiCl) and composite fluxes (NaF + SrF 2 , SrF 2 +NH 4 Cl and NaF + NH 4 Cl) were applied in the phosphors. NaF, SrF 2 , NH 4 Cl and NaF + SrF 2 fluxes had prominent effects on the characteristics of Sr 0.8 Ca 0.19 AlSiN 3 :0.01Eu 2+ phosphors. Sr 0.8 Ca 0.19 AlSiN 3 :0.01Eu 2+ phosphors with various powder morphologies can be obtained through the addition of fluxes, which are conducive for phosphor formation. The powder morphologies of phosphors incorporated with NaF + SrF 2 were preferable to those of powders incorporated with other fluxes. This result indicated that the incorporation of NaF + SrF 2 into Sr 0.8 Ca 0.19 AlSiN 3 :0.01Eu 2+ yielded phosphors with high luminescent intensity and quantum efficiency , excellent thermal stability, narrow full widths at half-maximum (FWHM, 75.2 nm), uniform rod-like morphologies with large particle sizes (D 50  = 16.99 μm) and good particle dispersion . White LEDs with high CRIs were obtained by combining prepared phosphors (NaF + SrF 2 additive) with the commercial green-emitting phosphors Y 3 (Al,Ga) 5 O 12 :Ce 3+ and (Sr,Ba) 2 SiO 4 :Eu 2+ . White LEDs with Y 3 (Al,Ga) 5 O 12 :Ce 3+ and (Sr,Ba) 2 SiO 4 :Eu 2+ phosphors had correlated colour temperatures (CCTs) of 3064 and 3023 K, respectively, and CRIs of 81.8 and 92.4, respectively. Therefore, NaF + SrF 2 can be used as a favourable flux for the production of Sr 0.8 Ca 0.19 AlSiN 3 :0.01Eu 2+ .