Effect of monovalent charge compensators on the photoluminescence properties of Ca3(PO4)2:Tb3+, A+ (A = Li, Na, K) phosphors

• Ca 3 (PO 4 ) 2 :Tb 3+ , Li + was explored as a green phosphor for WLED applications. • Adding 10 % excess Li + to Ca 2.3 (PO 4 ) 2 :Tb 3+ , Li + was necessary to enhance its PL properties. • Ca 2.3 (PO 4 ) 2 :0.35Tb 3+ , 0.385Li + showed 260 % larger emission intensity for Ca 2.65 (PO 4 ) 2 :0.35Tb 3+ . Ca 3- x (PO 4 ) 2 : x Tb 3+ (0.2 ≤ x ≤ 0.4), Ca 2.3 (PO 4 ) 2 :0.35Tb 3+ , 0.35A + (A = Li, Na, K), and Ca 2.3 (PO 4 ) 2 :0.35Tb 3+ , y Li + (0.35 ≤ y ≤ 0.455) phosphors were prepared by solid-state reaction. All the prepared phosphors formed a rhombohedral unit cell with the R 3 c space group. To improve the photoluminescence (PL) properties of the Ca 2.65 (PO 4 ) 2 :0.35Tb 3+ phosphor, monovalent charge compensators such as Li + , NA + , and K + were added to the Ca 2.65 (PO 4 ) 2 :0.35Tb 3+ phosphor. The charge compensators acted as fluxes, so they improved the crystallinity. The excitation and emission properties were significantly improved through the incorporation of charge compensators. In particular, among the charge compensators, Li + ion substantially enhanced the emission intensity and color purity. Furthermore, considering the evaporation of Li 2 CO 3 during the annealing process, we optimized the concentration of Li + charge compensator to enhance its PL performance. Impressively, the green emission intensity of the Ca 2.3 (PO 4 ) 2 :0.35Tb 3+ , 0.385Li + phosphor was 260 % higher than that of the Ca 2.65 (PO 4 ) 2 :0.35Tb 3+ phosphor. We believe that the effect of charge compensators on the PL properties and the optimum concentration of Li + charge compensator are useful for the design of phosphors in light-emitting diodes.