Defects Identification and Effects of Annealing on Lu2(1-x)Y2xSiO5 (LYSO) Single Crystals for Scintillation Application

Abstract

The nature, properties and relative concentrations of electronic defects were investigated by Thermoluminescence (TL) in Lu2(1-x)Y2xSiO5 (LYSO) single crystals. Ce and Tb-doped single crystals, grown by the Czochralski technique (CZ), revealed similar traps in TL. LYSO:Ce single crystals were grown by the Floating-Zone technique (FZ) with increasing oxygen concentration in the growth atmosphere. TL intensity is strongly dependent on the oxygen content of the material, and oxygen vacancies are proven to be the main electronic defects in LYSO. The effects of oxidizing and reducing annealing post-treatment on these defects were investigated. While oxidizing treatments efficiently reduce the amount of electronic defects, reducing treatments increase the amount of existing traps. In a thermally assisted tunneling mechanism, the localization of oxygen vacancies around the dopant is discussed. They are shown to be in the close vicinity of the dopant, though not in first neighbor positions.

Comparative Study of Co-Doped and Non Co-Doped LSO:Ce and LYSO:Ce Scintillators for TOF-PET

“…The LSO:Ce,0.2%Ca, LYSO:Ce (from Saint-Gobain Crystals), and LYSO:0.11%Ce,0.2%Mg materials were produced under stronger oxidizing conditions than usual. This is a method to suppress oxygen vacancies to increase the light output [13].…”

Long term in vivo imaging with Cr3+ doped spinel nanoparticles exhibiting persistent luminescence

“…In garnet for instance, lots of possible defects are reported such as vacancies, interstitials, antisites or other native defects [65,66] and such defects may play a fundamental role. Furthermore one should also notice that thermal annealing under reducing atmosphere is often used to create or enhance intrinsic traps such as oxygen vacancies [66]. Oxygen vacancies correspond to electron traps which can be responsible for the persistent luminescence.…”

Improving Ce3+doped scintillating materials for medical imaging applications

“…For this, various Ce 3+ :LYSO single crystals were grown by the Czochralski technique by Saint-Gobain Cristaux & Détecteurs as described in ref [4]. Samples with a size of 10×10×1 mm 3 with the two large faces polished were prepared.…”

“…Some materials like could have efficient emission 1, 2 but poor mechanical properties and mainly crystals and ceramics are suitable for high energy (X-rays or gamma rays) imaging. In order to improve the scintillation performances, the effect of oxidizing annealing treatments on Ce:LYSO, have been reported [3][4][5][6] . In particular these authors have pointed out the impact of point defects such as oxygen vacancies on the scintillation properties.…”