The influence of air annealing on the microstructure and scintillation properties of Ce,Mg:LuAG ceramics

Abstract

The microstructures and optical properties of Ce,Mg:Lu3Al5O12 scintillator ceramics are investigated with particular focus on the effect of postannealing in air from 1000 to 1450°C. The formation of Al2O3 clusters after annealing above 1300°C is evidenced by scanning electron microscopy. The presence of this secondary phase is tentatively explained by the occurrence of Ce and Mg evaporation, proved by inductive coupled plasma optical emission spectrometry measurements, followed by defect diffusion and clustering during high temperature annealing. Meanwhile, optical investigations including absorption, X‐ray induced luminescence, light yield, scintillation decay, and thermoluminescence prove the positive role of post‐annealing that leads to a brighter and faster scintillation emission. This behavior is associated to the removal of oxygen vacancies occurring during such treatments. In parallel, the partial conversion of Ce3+ ions into Ce4+ is also observed as a consequence of annealings and the role of Ce4+ ions in the scintillation process is discussed.

On fast LuAG:Ce scintillation ceramics with Ca2+ co‐dopants

“…Figure 9 presents TSL curves in the 77‐350 K range for the LuAG:Ce ceramics with differing Ca 2+ ion concentrations. All the TSL curves show broad structureless TSL peaks, consistent with previous observations in the literature and occurring due to the higher structural disorder of the fabricated ceramic than its single crystal counterpart 34 . The TSL peak positions of these LuAG:Ce ceramics match well with the positions observed in the single crystal 27 .…”

“…In addition, Ce 4+ ions are powerful competitors for electrons, allowing electrons participate in the fast luminescence process more effectively. 24,27,34 Therefore, with the incorporation of Ca 2+ co-dopant, the LY value of the LuAG:Ce ceramics is notably improved, and the slow component is also reduced. Figure 7 presents the integrated RL intensity of the annealed ceramics as a function of temperature in the range of 80-340 K. Due to the presence of various traps, the intensity reduction on the low temperature side was reasonable.…”

“…With the photons emitted, the de‐excited Ce 3+ will obtain holes from the VB or other nearby hole sources, such as the O ‐ centers generated for the charge balance of the LuAG lattice, 33 to get back to the initial Ce 4+ state, which makes its luminescence process faster than that of the Ce 3+ centers. In addition, Ce 4+ ions are powerful competitors for electrons, allowing electrons participate in the fast luminescence process more effectively 24,27,34 . Therefore, with the incorporation of Ca 2+ co‐dopant, the LY value of the LuAG:Ce ceramics is notably improved, and the slow component is also reduced.…”

Tb3+‐doped transparent BaGdF5 glass‐ceramics scintillator for X‐ray detector

“…Rare earth (RE) ionsdoped scintillators, which emit light after absorbing high‐energy particles or rays (such as X‐ray or γ‐ray), have been extensively researched owing to their wide applications in many fields, such as industrial and medical imaging, high energy physics, homeland security, nuclear radiation detection and so on . Inorganic monocrystals and transparent ceramics, such as Gd 2 SiO 5 :Ce 3+ , Ce 3+ ‐doped Lu 2 SiO 5 , Bi 4 Ge 3 O 12 (BGO), and Ce,Mg:LuAG are often used as commercial productions due to their outstanding structural and optical properties. However, the manufacture techniques of single crystals and ceramic scintillators are extremely complex, costly, time‐consuming and difficult to get large‐size crystals, which limit their applications …”

Wide Concentration Range of Tb3+ Doping Influence on Scintillation Properties of (Ce, Tb, Gd)3Ga2Al3O12 Crystals Grown by the Optical Floating Zone Method

“…The GGAG:Ce, xTb crystals perform optimum LY when x = 7%, reaching to 18,841 pho/MeV, whereas in XEL the peak intensity is observed when x = 15%. This difference indicates that the GGAG:Ce, 7% Tb may probably have a lower defect concentration considering the 0.75 μs time gate [ 46 ] were used in scintillation LY measurement while XEL spectra give overall stead state radioluminescence intensity.…”