Synthesis and Photoluminescence Properties of Eu3+-Activated Ba2Cd(BO3)2 Red-Emitting Phosphors for Near-Ultraviolet Excited White Light-Emitting Diodes

Abstract

A new class of rare-earth doped borate phosphors, Ba₂Cd(BO₃)₂: xEu³⁺ (x = 2, 3, 4, 5, and 6 mol%), was synthesized using the high-temperature solid-state reaction technique in air. X-ray diffraction (XRD) confirmed the phase formation of Ba₂Cd(BO₃)₂, while Fourier transform infrared spectroscopy (FT-IR) revealed the presence of trigonal [BO₃] units. The surface morphology was studied using field emission scanning electron microscopy (FE-SEM), and energy dispersive spectroscopy (EDS) identified the elements. Photoluminescence (PL) analysis showed that the phosphors emitted at 592, 613, 652, and 701 nm, corresponding to the ⁵D₀ → ⁷F₁, ⁵D₀ → ⁷F₂, ⁵D₀ → ⁷F₃, and ⁵D₀ → ⁷F₄ transition of Eu³⁺ ions, respectively. The 613 nm red emission, from the ⁵D₀ → ⁷F₂ transition, was strongest for the 6 mol% Eu³⁺ sample. The emission intensity increased with Eu³⁺ concentration, peaking at 6 mol%. CIE chromaticity, correlated color temperature (CCT), and color purity calculations showed acceptable color coordinates (0.6426 and 0.3548), a low CCT value (2355 K), and high purity (91.34%), making the 6 mol% Eu³⁺-doped phosphor ideal for red light in white light-emitting diodes (WLEDs).

Keywords: CIE diagram; inorganic borate; photoluminescence; red phosphor; solid‐state reaction.