Epitaxial growth of single-crystalline-film scintillators based on Tb³⁺-doped and Tb³⁺–Ce³⁺-codoped Gd_1–xLu_xAlO₃ (x = 0–1) mixed perovskites

The paper is dedicated to the development of scintillating screens for microimaging applications based on the single crystalline films (SCFs) of singly Tb³⁺ and doubly Tb³⁺–Ce³⁺ doped Gd_1–xLu_xAlO₃ (x = 0–1) mixed perovskites grown onto YAlO₃ (YAP) substrates using the liquid phase epitaxy (LPE) method. The cation engineering in Gd_1–xLu_xAlO₃ (x = 0–1) solid solution enabled an improvement of the K-edge of X-ray absorption of SCF scintillators in the 50–63 keV energy range. The structural quality of the grown films was studied using X-ray diffraction and scanning electron microscopy. The optical properties of the Tb³⁺-doped and Tb³⁺–Ce³⁺-codoped Gd_1–xLu_xAlO₃ (x = 0–1) SCFs were investigated by conventional spectroscopic methods, such as absorption, cathodoluminescence (CL), photoluminescence, the light yield of CL, and radioluminescence (RL) measurements under e-beam and α-particle excitation, respectively. Effective Gd³⁺ → Tb³⁺ and Gd³⁺ → Ce³⁺ → Tb³⁺ energy transfer processes were observed in Gd_1–xLu_xAlO₃:Tb and Gd_1–xLu_xAlO₃:Tb,Ce SCFs, respectively, explaining the increased efficiency of the Tb³⁺ luminescence in these perovskite hosts. We found that the highest efficiencies in terms of CL and RL were observed in the doubly Tb³⁺–Ce³⁺-doped Gd_0.5Lu_0.5AlO₃ SCFs.