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We report results of the luminescence properties of the three garnet type phosphors Ce3+-doped Ca3Sc2Si3O12 (CSSO:Ce3+), Sr3Y2Ge3O12 (SYG:Ce3+) and Y3Al5O12 (YAG:Ce3+), investigated using optical spectroscopy techniques and vacuum referred binding energy (VRBE) diagram analysis.

The luminescence spectroscopy of Tb 3+ and Eu 3+ has been studied in the Ca 9 Tb(PO 4 ) 7 , Ca 9 Eu(PO 4 ) 7 , and Ca 9 Tb 0.9 Eu 0.1 (PO 4 ) 7 materials having a whitlockite structure, by using excitation in the near UV, vacuum UV and X-ray regions. The Eu 3+ ion in Ca 9 Eu(PO 4 ) 7 is located mainly in two cationic sites, as evidenced by the fine structure of the 5 D 0 → 7 F 0 transition at 5 K. In the case of Ca 9 Tb 0.9 Eu 0.1 (PO 4 ) 7 , weak Tb 3+ → Eu 3+ energy transfer is observed upon excitation in the UV bands of Tb 3+ . The low efficiency of the transfer appears to be due to slow energy migration in the 5 D 4 subset of the Tb 3+ ions. The overall behavior is strongly affected by the multisite and disordered nature of the Tb-based whitlockite host.

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The influence of the Ce3+ concentration on the excitation and emission characteristics, thermal stability, and charge-trapping–detrapping dynamics, of the green-emitting phosphor Ce3+ doped calcium scandium oxide (CaSc2O4) with very dilute Ce3+ substitutions (0.5, 1.0, and 1.5%), has been investigated using optical spectroscopy techniques. The diffuse reflectance and excitation spectra are found to exhibit a nonsystematic behavior with varying Ce3+ concentration, mainly linked to spectral band-overlap, whereas the emission spectra display only minor changes with varying Ce3+ concentration, suggesting that the local structural coordination of the Ce3+ dopants remains the same for different Ce3+ dopant levels. The major impact of Ce3+ concentration is seen on the thermal quenching temperature, which is found to be as high as T 50% ≈ 600 K for the most dilute Ce3+ doping (0.5%), followed by T 50% ≈ 530 K for 1.0% doping and T 50% ≈ 500 K for 1.5% doping, respectively. The materials are found to display a red-shift of the emitted light from 518 to 535 nm with increasing temperature from T = 80 K to T = 800 K, for all Ce3+ dopant levels. Thermoluminescence glow curves provide evidence for five charge-trapping defects, which are found to exhibit different charge-trapping dynamics for excitation into different 5d levels. It is argued that the three deeper traps can be filled by athermal tunneling of charges from the Ce3+ 5d 1 level, while the two shallower traps can only be filled when the charges move through the conduction band of the material.