Vacancy-type defects in garnet crystals revealed by gamma-ray-induced positron annihilation spectroscopy

Kitaura, Mamoru*; Fujimori, Kosuke*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Hirade, Tetsuya ; Kamada, Kei*; Watanabe, Shinta*; Onishi, Akimasa*

Positron annihilation spectroscopy is the only way to investigate the properties of cation vacancies because they are negatively charged. We generated high-energy pulsed gamma rays by the vertical collision of an ultrashort pulse laser and electron beam. In this study, we investigated the vacancy-type defects present in the crystals of GAGG(Gd $_{3}$ Al $_{2}$ Ga $_{3}$ O $_{12}$ ), GAGG: Ce and GAGG: Ce, Mg by positron annihilation lifetime spectroscopy using the high-energy gamma rays. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg $^{2+}$ ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.

Language	:	Japanese
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Meeting title	:	MRM Forum 2020 (MRM 2020)
Held date	:	2020/12
Location (city)	:	online
Location (country)	:	Japan
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Keywords	:	シンチレータ; 陽電子消滅寿命測定
Research Facility	:	第4研究棟
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Registration No. : BB20200554
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