Structural, optical, and thermal traits of Sm³⁺-doped SrB₂O₄ phosphors for solid-state lighting applications

Abstract

We synthesized Sm³⁺-doped SrB₂O₄ phosphors through a solid-state reaction method, varying the Sm³⁺ doping concentrations. Structural and morphological characteristics of material were investigated using Fourier-transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD) and scanning electron microscopy (SEM). Optical transitions were analyzed by recording the diffuse reflectance spectroscopy, while photoluminescent (PL) spectra were used to evaluate luminescence properties. The PL spectra revealed a strong orange emission at 598 nm under 402 nm excitation. The optimal Sm³⁺ doping concentration was determined to be 0.02 mol, beyond which concentration quenching occurred. This quenching is attributed to exchange-type interactions, which facilitate non-radiative energy relaxation. The CIE color chromaticity coordinates of all the synthesized phosphors fell within the orange region of the chromaticity diagram. Temperature dependent photoluminescence revealed lower activation energy and phonon energy. Thermal quenching temperature was calculated which is inline with commercially available LEDs. All of these results indicate the candidature of SrB₂O₄ phosphor doped with Sm³⁺ ions for solid state lighting and optical thermal sensing applications.