Orange-Red-Emitting Ba₂YAlO₅:Sm³⁺ Phosphors with High Thermal Stability for Preparation of w-LEDs

A series of orange-red-emitting phosphors, Ba₂Y_1−xSm_xAlO₅ (x = 1 mol.%, 2 mol.%, 5 mol.%, 10 mol.%, 15 mol.%, 20 mol.%, 25 mol.%, and 30 mol.%), were successfully synthesized using a high-temperature solid-state method at 1400°C, with Sm³⁺ serving as the activator. The crystallinity of the samples was confirmed in the space group P2₁/c (14). Efficient excitation was observed in the Ba₂YAlO₅:xSm³⁺ phosphors when exposed to 405 nm irradiation. Upon excitation at 405 nm, the synthesized Ba₂YAlO₅:xSm³⁺ phosphors displayed three distinctive peaks, which corresponded to the transitions of Sm³⁺ at ⁴G_5/2–⁶H_J (J = 5/2, 7/2, and 9/2). Optimal luminescence properties were achieved at a Sm³⁺ concentration of 2 mol.%. The phenomenon of concentration quenching was elucidated through the application of dipole–dipole interaction theory. The quenching temperature of Ba₂YAlO₅:0.10Sm³⁺ exceeded 480 K. The CIE chromaticity coordinates of Ba₂YAlO₅:xSm³⁺ closely align with the recognized standard red defined by the National Television System Committee (NTSC). This conformity underscores the potential of Ba₂YAlO₅:xSm³⁺ phosphors for applications demanding precise color reproduction, as required in advanced display technologies and lighting systems.