A near-UV-converted LiMgBO ₃ :Dy ³⁺ nanophosphor: Surface and spectral investigations

A near-ultra violet (UV) converted LiMgBO ₃ :Dy ³⁺ nanophosphors have been synthesized by the combustion method. The structural, spectral and optical properties were examined by powder X-ray diffraction, fluorescent spectrophotometry and UV-vis spectroscopy. The excitation spectra of the phosphors contain sharp peaks at 294, 323, 348 and 385 nm due to the 4f-4f transition of the Dy ³⁺ ion. The phosphor is efficiently excited by near-UV chips. Upon near-UV excitation the phosphor emits intense blue and yellow with a weak red band centered at 484, 573 and 669 nm respectively, ascribed to the transition of Dy ³⁺ ion from ⁴ F _9/2 → ⁶ H _15/2 , ⁶ H _13/2 , ⁶ H _11/2 . The diffuse reflectance spectra of the phosphors were consistent with the excitation spectra and were used to calculate the band gap of the material, approximated to be 5.4 eV. The calculated CIE coordinates (0.45, 0.46) under 348 nm excitation were found to be in the white spectrum region. For surface investigation, X-ray photoelectron spectroscopy was used which confirms the presence of all the elements on the surface of the material.