Investigation on the effects of Ce3+:Lu2SiO5 nanocrystalline phosphors in reducing environment

Abstract

Lutetium oxyorthosilicate doped with cerium (Ce3+:Lu2SiO5) is a high resolution and highly responsive detector used in medical imaging frequently in the form of single crystals. Fabrication of ceramic polycrystalline lutetium oxyorthosilicate (LSO) doped with cerium is an upcoming alternative that requires high temperatures and a non-oxidising atmosphere for sintering. However, the stability of the nano phosphor itself under the sintering conditions is inconsistent and has stumped many investigators. This paper presents a systematic study of the formation of lutetium oxyorthosilicate from its respective constituents (lutetia and silica) and of the behavior of LSO under sintering conditions. The study shows a breakdown of the compound in highly reducing atmospheres to form lutetium oxide, as confirmed by x-ray diffraction studies. The decomposition of hot pressed Ce:LSO in a reducing environment studied by scanning electron micrography, Raman spectroscopy, shows the correlation of its structure and defects with its radioluminescence.