V. Gorbenko

Scintillating Screens Based on the Single Crystalline Films of Multicomponent Garnets: New Achievements and Possibilities

The paper is dedicated to development of the novel scintillating screens based on single crystalline films (SCF) of Ce doped Lu_{3 - x}Tb_xAl_{5 - y}GayO₁₂ multicomponent garnets at x = 2 - 3 and y = 0 - 2.5 onto Y₃Al₅O₁₂ (YAG) and Gd₃Al_2.5Ga_2.5O₁₂ (GAGG) substrates using the liquid phase epitaxy (LPE) method. We report the optimized content and high scintillation figure of merit of SCF of these garnets grown by the LPE method with using PbO based flux. Namely, the Tb₃Al_2.5Ga_2.5O₁₂:Ce SCFs possess the highest values of light yield (LY) compared to all earlier investigated SCF samples, with their LY exceeding by 2.35 and 1.15 times the LY values for YAG:Ce and LuAG:Ce SCF scintillators, respectively. The SCFs of the mentioned compounds show very lower thermoluminescence in the above room temperature range and relatively fast scintillation decay.

Epitaxial growth of single crystalline film scintillating screens based on Eu3+ doped RAlO3 (R = Y, Lu, Gd, Tb) perovskites

The study is dedicated to the development of scintillating screens for microimaging applications based on the single crystalline films (SCFs) of Eu3+-doped (Y,Lu,Gd,Tb)AlO3-mixed perovskites grown onto YAlO3 substrates using the liquid phase epitaxy (LPE) method with the objective to optimize their X-ray stopping power and light yield. We confirm that the Eu3+-doped YAlO3 and TbAlO3 SCFs and full set of Lu1−xGdxAlO3 SCFs with x values in the x = 0–1.0 range can be crystallized on YAlO3 substrates using the LPE technique. The structural quality of films was studied using X-ray diffraction. The optical properties of Lu1−xGdxAlO3:Eu (x = 0–1) SCFs and TbAlO3:Eu mixed perovskites were also studied in this work in comparison with YAlO3:Eu SCF counterpart using the absorption, cathodoluminescence, photoluminescence (PL) emission and excitation spectra and PL decay kinetics as well as light yield measurements under e-beam and α-particles excitation. The Gd3+ → Eu3+ and Tb3+ → Eu3+ energy transfer processes are observed in Lu1−xGdxAlO3 and TbAlO3:Eu SCFs, respectively, increasing the efficiency of the Eu3+ luminescence in the perovskite hosts. Meanwhile, the highest light yield of the cathodoluminescence (CL) and radioluminescence (RL) under excitation by α-particles is found only in YAlO3:Eu, Lu0.5Gd0.5AlO3:Eu and GdAlO3:Eu SCFs. The light yield of CL and RL of these SCFs is notably higher than that in TbAlO3:Eu and LuAlO3:Eu SCFs and they even slightly (9–11%) overcome the light yield of the conventional Gd3Ga5O12:Eu SCF screens that are used in the microimaging detectors.

Epitaxial growth of composite scintillators based on Tb3Al5O12 : Ce single crystalline films and Gd3Al2.5Ga2.5O12 : Ce crystal substrates

This work presents our latest achievements in the development of advanced composite scintillators for simultaneous registration of α-particles and γ-quanta in mixed ionizing fluxes based on single crystalline films (SCFs) of Tb3Al3O12u2006:u2006Ce (TbAGu2006:u2006Ce) garnet and Gd3Al2.5Ga2.5O12u2006:u2006Ce (GAGGu2006:u2006Ce) single crystal (SC) substrates using the liquid phase epitaxy (LPE) growth method from a melt-solution based on a PbO–B2O3 flux. The separation of the signals from the SCF and SC components of such composite scintillators can be realized by means of registration of the difference in the scintillation decay times of SCF and substrate scintillators and can be achieved at a large K = t(SCF)/t(SC) ratio, which is usually above 2. The TbAGu2006:u2006Ce SCFs exhibit relatively fast scintillation response under α-particle excitation with decay times of t1/e = 344–380 ns and t1/100 = 3130–3770 ns. Meanwhile, the scintillation response of TbAGu2006:u2006Ce SCFs under α-particle excitation is significantly slower in the 500–4000 ns range than that of the GAGGu2006:u2006Ce crystals with decay times of t1/e = 270–280 ns and t1/20 = 1280–1300 ns. We have found that for TbAGu2006:u2006Ce/GAGGu2006:u2006Ce composite scintillators, the optimal K ratio changes from 2.0 to 3.0 at the registration of scintillations with shaping times of 700–4000 ns. For this reason, TbAGu2006:u2006Ce/GAGGu2006:u2006Ce composite scintillators possess the best scintillation properties among all known LPE grown analogues for simultaneous registration of α-particles and γ-quanta in mixed fluxes.