Synthesis and photoluminescent properties of Ba2+ ions doped europium formate phosphors for white light-emitting diodes

The composition engineering of red‐emitting Eu3+‐doped Ca10.5(PO4)7‐type solid solution phosphors and application in LED

“…Concerning the theory of Judd‐Ofelt, when the R value is high, the ligand symmetry is low, and the bond covalency of Eu 3+ sites is high 46 . It can be observed from Figure 5E that the R value is always greater than 4, indicating that the transition of 5 D 0 ‐ 7 F 2 associated with Eu 3+ is dominant within the CNYP‐I (0 ≤ x ≤ 1/2) and CNYP‐II (0 ≤ y ≤ 1) complexes that might be inferred that Eu 3+ occupies the non‐inversion center of low‐symmetry 48,49 . In addition, with the increase in x (except for x = 1/2), the R value shows a slight downward trend, which implies the site symmetry Eu 3+ occupied increases; with the increase in y (except for y = 0), the R value presents an upward trend, which indicates the site symmetry Eu 3+ occupied decreases.…”

“…the transition of 5 D 0 -7 F 2 associated with Eu 3+ is dominant within the CNYP-I (0 ≤ x ≤ 1/2) and CNYP-II (0 ≤ y ≤ 1) complexes that might be inferred that Eu 3+ occupies the non-inversion center of low-symmetry. 48,49 In addition, with the increase in x (except for x = 1/2), the R value shows a slight downward trend, which implies the site symmetry Eu 3+ occupied increases; with the increase in y (except for y = 0), the R value presents an upward trend, which indicates the site symmetry Eu 3+ occupied decreases. For Ca 9 Na 3/2 Y 1/2 (PO 4 ) 7 (x = 1/2 or y = 0) sample, the substitution component locates at the critical point, and its R value does not conform to the above trends.…”