Abstract
Cerium-doped 1% Ce:Gd2Y1Ga2.7Al2.3O12(GYGAG) single crystal samples grown via Czochralski method were annealed under air, O2 and N2 atmospheres from 350 to 1400 °C. The X-ray excited luminescence spectra, energy spectra and UV as well as thermally stimulated luminescence (TSL) spectra were performed comparatively on “as-grown” and thermally annealed samples. It was found that the luminescence efficiency after annealing in air and O2 was significantly enhanced compared to the non-annealed samples and this phenomenon was suggested to be caused by the existence of some oxygen vacancies in the Ce:GYGAG crystals. And the oxygen vacancies in the as-grown GYGAG crystals can be effectively eliminated by means of annealing in O2 containing atmosphere without changing the luminescence mechanism. From the TSL curves before and after annealing, three traps within 77–650 K were found to be related to oxygen vacancies.
Highlights
Cerium and Praseodymium ion plays an important role in scintillation crystals as activators [1,2,3,4]
It was found that the luminescence efficiency after annealing in air and O2 was significantly enhanced compared to the non-annealed samples and this phenomenon was suggested to be caused by the existence of some oxygen vacancies in the Ce:GYGAG crystals
Systematical annealing experiments of Ce:Lu2Si2O7 crystals under different temperatures and different atmospheres were performed by Feng et al [20], they found a strong increase of luminescence intensity of Ce:LPS annealed in air above 1400 °C, which was due to vacancies’ filling by diffusing oxygen atoms
Summary
Cerium and Praseodymium ion plays an important role in scintillation crystals as activators [1,2,3,4]. Systematical annealing experiments of Ce:Lu2Si2O7 crystals under different temperatures and different atmospheres were performed by Feng et al [20], they found a strong increase of luminescence intensity of Ce:LPS annealed in air above 1400 °C, which was due to vacancies’ filling by diffusing oxygen atoms. Drozdowski et al [21,22,23] annealed Pr:LuAlO3 and Pr:Lu3Al5O12 crystals in hydrogen and air atmosphere, respectively, and a great yield enhancement was achieved in these crystals. The positive influence of annealing in air at high temperatures are explained by the creation of an alternative fast radiative pathway through stable Ce4? 384 Page 2 of 6 scintillators, which present great light yield improvement compared to the LuAG crystals. The thermal annealing effects on Ce:Gd2Y1Ga2.7Al2.3O12(GYGAG) crystals in different atmospheres were studied and the positive effects were explained. The results of correlated Absorption spectra, X-ray excited Radioluminescence, Thermoluminescence (TSL) and UV-excitation and emission spectra measurements, performed on the ‘‘asgrown’’ and annealed samples, have been analyzed
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