Effect of Partial Ca2+ Substitution with Ln3+ (Ln = Y, La) on Luminescence Enhancement of Ca18.62Zn2(PO4)14:0.38Dy3+ White-Emitting Phosphor for White Light-Emitting Diodes

A sequence of white-emitting Ca18.62–xLnxZn2(PO4)14:0.38Dy3+ (Ln = Y, La) phosphors were synthesized by a high-temperature solid-phase method. The luminescence enhancement of Ca18.62–xLnxZn2(PO4)14:0.38Dy3+ phosphors via Ln3+ partial substitution was investigated. Since Ln3+ and Ca2+ ions have similar ionic radii, XRD results showed that Ln3+ could enter into the lattice without changing the host structure and the luminescence performance was further enhanced by affecting the lattice environment around the luminescence center. When the substitution amounts of Y3+ and La3+ were respectively x = 0.57 and 0.76 in the Ca18.62–xLnxZn2(PO4)14:0.38Dy3+ phosphor, the optimal luminescence performance could be acquired, and the luminescence intensity could be increased to 1.43 and 1.55 times the original intensity, respectively. Meanwhile, the cation substitution can greatly improve the thermal stability and enhance the activation energy of phosphor. Finally, the w-LEDs with neutral white light emitting were obtained by coating the as-prepared phosphor on an n-UV chip, and the color rendering index and correlated color temperature were measured as 85.8 and 5071 K, respectively. All the results indicated that the Ca18.62–xLnxZn2(PO4)14:0.38Dy3+ phosphor is an excellent candidate as a single-component white-emitting phosphor.