Optical properties of Y₄Al₂O₉:Eu³⁺ in the UV–Vis spectral range

The optical properties of Y 4 Al 2 O 9 :Eu 3+ were studied on the basis of diffuse reflectance spectra, photoluminescence and photoluminescence excitation spectra, temperature dependences of photoluminescence, and emission decay kinetics combined with calculations of the Judd–Ofelt parameters. Three excitation channels were identified for Eu 3+ luminescence, including intracenter excitation, energy transfer from intrinsic defects, and charge-transfer absorption. Temperature dependences of photoluminescence revealed the emission enhancement at excitation through the charge-transfer absorption band. Defects in the nearest environment of Eu 3+ ions lead to the shortening of the luminescence lifetime due to an increase in the probability of both radiative and nonradiative transitions. Additional excitation channels for Eu 3+ luminescence in the far and near UV ranges indicate the potential of Y 4 Al 2 O 9 :Eu 3+ for the development of red phosphors operating under UV excitation.