Peculiarities and the red shift of Eu2+ luminescence in Gd3+-admixed YAG phosphors

Set of Eu2+-doped (Gd; Y)3Al5O12 (GYAG) powder samples with different Gd/Y ratio was synthesized by inorganic reaction in the solid state from high purity Gd2O3, Y2O3, Al2O3 and EuS. Their structural, scintillation and optical properties were investigated thoroughly by means of X-ray powder diffraction, time-resolved luminescence spectroscopy, photothermal deflection spectroscopy and electron paramagnetic resonance in a broad temperature range to assess the influence of Gd admixture into the YAG host. A phenomenological model was fitted to the measured temperature dependences of the photoluminescence emission spectra and photoluminescence decay times to better understand the dynamics of the 5d excited state of the Eu2+ center. Thermoluminescence and delayed recombination measurements were performed to study the trap distribution and thermally induced ionization of the activator's excited state. Application potential of studied phosphors either in the field of scintillators or solid state white light emitting diode (LED) phosphors is discussed.