Photoluminescence and scintillation properties in Tb3+/Eu3+co-doped phosphate glasses for X-ray imaging applications

Abstract

This study explores alkali oxide-modified phosphate glasses with the chemical composition 22K<inf>2</inf>O-9Al<inf>2</inf>O<inf>3</inf>-1SrO-(63-Z)P<inf>2</inf>O<inf>5</inf>-5Tb<inf>2</inf>O<inf>3</inf>-ZEu<inf>2</inf>O<inf>3,</inf> where (Z = 0.0, 0.1, 0.3, 0.5, 1.0, 2.0 mol%), synthesized by the conventional melt-quenching method. UV–Vis–NIR spectra exhibited six absorption bands. The absence of sharp diffraction peaks in the XRD patterns confirms the amorphous nature of the prepared glasses. FTIR spectra further indicate the presence of both bridging oxygen (BO) and non-bridging oxygen (NBO) structural units within the phosphate network. The red luminescence associated with the 5D<inf>0</inf>→7F<inf>2</inf> (613 nm) transition was observed at an excitation wavelength of (Formula presented), corresponding to Eu3+ ions. In contrast, excitation at (Formula presented) 377 nm revealed a green emission peak associated with the 5D<inf>4</inf>→7F<inf>5</inf> (544 nm) transition, corresponding to the Tb3+ ions. Photoluminescence and radioluminescence spectra, together with decay analysis, verified efficient Tb3+→Eu3+ energy transfer, with Tb3+ lifetimes decreasing and Eu3+ lifetimes remaining nearly constant. The CIE chromaticity coordinates lie in the orange-red region, with correlated color temperatures of 2000–3000 K, indicating suitability for warm red emission. Notably, the co-doped glass scintillator achieved a spatial resolution of 11.6 LP/mm, which is comparable to that of the commercial BGO scintillator (13.2 LP/mm). These results demonstrate that Tb3+/Eu3+ co-doped phosphate glasses are promising candidates for reddish-orange light-emitting devices and high-resolution X-ray imaging applications.