Photoluminescence Properties of Sm ³⁺ ‐Activated Na ₃ Ba ₂ Ca(PO ₄ ) ₃ Orange‐Red Phosphor With High Color Purity for White LEDs

ABSTRACT A series of Na 3 Ba 2 Ca(PO 4 ) 3 : x Sm 3+ ( x = 0.01–0.13) orange‐red phosphors was synthesized via a high‐temperature solid‐state reaction. X‐ray diffraction (XRD) analysis confirmed that all samples were phase‐pure. Scanning electron microscopy (SEM) coupled with energy‐dispersive X‐ray spectroscopy (EDS) mapping revealed a homogeneous distribution of constituent elements throughout the particles. Under near‐ultraviolet excitation at 401 nm, the phosphors exhibited bright orange‐red emission with the strongest peak at 596 nm, corresponding to the characteristic 4 G 5/2 → 6 H 7/2 transition of Sm 3+ . The Commission Internationale de l’Éclairage (CIE) chromaticity coordinates of all samples fell in the orange‐red region. Moreover, the phosphor demonstrated favorable thermal stability, retaining 85.9% of its initial emission intensity at 423 K. A white light‐emitting diode was fabricated by combining the optimal phosphor with a near‐UV LED chip, yielding white light with CIE chromaticity coordinates of (0.3267, 0.3879) and a correlated color temperature of 5763 K. These results indicate that Na 3 Ba 2 Ca(PO 4 ) 3 : Sm 3+ is a promising candidate for near‐UV‐excited white light‐emitting diodes.