Photoluminescence properties of novel Ca₃Al₁₀O₁₈:RE³⁺ (RE³⁺ = Dy³⁺, Sm³⁺) phosphor prepared via combustion synthesis for solid-state lightning devices

Abstract

The series of Dy³⁺ and Sm³⁺ activated Ca₃Al₁₀O₁₈ phosphors with various concentrations prepared through combustion method. The XRD analysis verified that the crystalline structure is orthorhombic, matching JCPDS no. 00-001-0572, with no impurities detected. FTIR spectroscopy revealed that the bending vibrations of H₂O, Ca–O, and Al–O atoms, indicating metal–oxygen stretching vibrations. The SEM image reveals micro-sized particles with irregular shapes and uneven morphology. The photoluminescence (PL) excitation spectra of Ca₃Al₁₀O₁₈:Dy³⁺ phosphor showed distinct lines at 327 nm, 346 nm, 374 nm, 391 nm, 423 nm, and 452 nm, attributed due to the transitions several excited states from ground state. The most intense transition was ⁶H_15/2 → ⁶P_7/2 (346 nm). Emission spectra exhibited strong blue (483 & 487 nm) and yellow (568 nm) luminescence peaks, with the ⁶F_9/2 → ⁶H_15/2 blue emission being magnetic dipole-allowed transition and the ⁶F_9/2 → ⁶H_13/2 yellow emission being induced dipole-allowed transition. The blue peaks split into two sharp peak centered at 483 nm and 487 nm. PL excitation spectra of Ca₃Al₁₀O₁₈:Sm³⁺ phosphor showed peaks at 345 nm, 362 nm, 375 nm, 403 nm, and 419 nm, with the highest intensity observed at 403 nm. The emission spectra displayed intense peaks at 567 nm, 604 nm, and 657 nm, corresponding to ⁴G_5/2 → ⁶H_5/2, ⁶H_7/2, and ⁶H_9/2 transition of Sm³⁺ ion within 4f–4f electronic configuration, with the most intense peak at 604 nm. The concentration quenching observed in Dy³⁺ and Sm³⁺ activated Ca₃Al₁₀O₁₈ phosphor at 0.7 mol%. The CIE color co-ordinates of Ca₃Al₁₀O₁₈:Dy³⁺ phosphor positioned at the edge of the green–yellow and indigo–blue regions of the CIE diagram. For Ca₃Al₁₀O₁₈:Sm³⁺ phosphor, the CIE co-ordinate located at the border of the yellow and red regions in the CIE diagram. These results suggest that Ca₃Al₁₀O₁₈:RE³⁺ (RE³⁺ = Dy³⁺, Sm³⁺) phosphor is promising for use in WLEDs and display application.