Abstract:The growth of single crystalline films (SCFs) with excellent scintillation properties based on the Tb 1.5 Gd 1.5 Al 5−y Ga y O 12 :Ce mixed garnet at y = 2-3.85 by Liquid Phase Epitaxy (LPE) method onto Gd 3 Al 2.5 Ga 2.5 O 12 (GAGG) substrates from BaO based flux is reported in this work. We have found that the best scintillation properties are shown by Tb 1.5 Gd 1.5 Al 3 Ga 2 O 12 :Ce SCFs. These SCFs possess the highest light yield (LY) ever obtained in our group for LPE grown garnet SCF scintillators exceeding by at least 10% the LY of previously reported Lu 1.5 Gd 1.5 Al 2.75 Ga 2.25 O 12 :Ce and Gd 3 Al 2-2.75 Ga 3-2.25 O 12 :Ce SCF scintillators, grown from BaO based flux. Under α-particles excitation, the Tb 1.5 Gd 1.5 Al 3 Ga 2 O 12 :Ce SCF show LY comparable with that of high-quality Gd 3 Al 2.5 Ga 2.5 O 12 :Ce single crystal (SC) scintillator with the LY above 10,000 photons/MeV but faster (at least by 2 times) scintillation decay times t 1/e and t 1/20 of 230 and 730 ns, respectively. The LY of Tb 1.5 Gd 1.5 Al 2.5 Ga 2.5 O 12 :Ce SCFs, grown from PbO flux, is comparable with the LY of their counterparts grown from BaO flux, but these SCFs possess slightly slower scintillation response with decay times t 1/e and t 1/20 of 330 and 990 ns, respectively. Taking into account that the SCFs of the Tb 1.5 Gd 1.5 Al 3-2.25 Ga 2-2.75 O 12 :Ce garnet can also be grown onto Ce 3+ doped GAGG substrates, the LPE method can also be used for the creation of the hybrid film-substrate scintillators for simultaneous registration of the different components of ionization fluxes.
The work is dedicated to the investigation of Eu 2þ and Eu 3þ luminescence centers in the Ca 3 Ga 2 Ge 3 O 12 garnet using synchrotron radiation excitation. The luminescence of Eu 2þ and Eu 3þ states was observed in the emission spectra of Ca 3 Ga 2 Ge 3 O 12 :Eu ceramics under excitation with energies in the exciton range and the range above band gap of this garnet. The luminescence of Eu 2þ ions Ca 3 Ga 2 Ge 3 O 12 host is observed in the band peaked at 450-460 nm with decay time in the ten ns range and excited in the two wide bands peaked at 5.04 and 6.05 eV, related to the allowed 4f-5d transitions of Eu 2þ ions. The Eu 3þ luminescence can be excited via the Eu 2þ luminescence. We have also found the energies of formation of excitons bound with Eu 2þ and Eu 3þ ions in Ca 3 Ga 2 Ge 3 O 12 , being equal to 7.64 and 6.95 eV, respectively, and the onset of interband transitions in this garnet which is equal to 7.83 eV at 8 K. Strong increase of the luminescence intensity of Eu 2þ and Eu 3þ centers is observed under excitation above 21 eV due to multiplication of electronic excitation in Ca 3 Ga 2 Ge 3 O 12 host.
In this work we show the influence of material preparation technology on the thermoluminescent properties of single crystalline films (SCFs) of Ce 3+ -doped Lu 2 SiO 5 (LSO) and Y 2 SiO 5 (YSO) orthosilicates. LSO:Ce and YSO:Ce SCFs were grown by the liquid phase epitaxy method from two different melt-solutions based on PbO-B 2 O 3 and Bi 2 O 3 fluxes. Absorption, cathodoluminescence, and thermoluminescent properties of LSO:Ce and YSO:Ce SCFs grown from the two previously mentioned types of fluxes were compared, and results of spectrally resolved thermoluminescence measurements and thermoluminescent glow curves of SCFs recorded in different spectral ranges were presented. We have found that the observed differences in thermoluminescent properties of the SCFs under study can be caused by the
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