Melilite-Structure CaYAl3O7:Eu3+ Phosphor: Structural and Optical Characteristics for Near-UV LED-Based White Light

A red-emitting phosphor, CaY 1- x Eu x Al 3 O 7 (CYA:Eu 3+ ), was prepared by conventional solid-state reaction, and its structural properties were investigated by means of Rietveld refinement method and maximum entropy method using an X-ray source. XRD patterns confirm the tetragonal phase of CYA:Eu 3+ phosphors. The photoluminescence properties of the samples were investigated for application to white light-emitting diodes (WLEDs). The emission spectrum is dominated by a red peak located at 616 nm due to the 5 D 0 → 7 F 2 electric dipole transition of Eu 3+ ions. Concentration quenching occurs when the Eu 3+ concentration is about 0.35 and the critical transfer distance of the phosphor is also calculated. A white LED fabricated with blue, green, and CYA:Eu 3+ red phosphor incorporated with an encapsulant in ultraviolet LEDs (λ max = 396 nm) is discussed.