Crystal growth and scintillation properties of undoped and Ce3+-doped GdI3 crystals

Abstract The growth and scintillation properties of undoped and Ce 3+ -doped GdI 3 crystals were reported in this paper. These GdI 3 :χ%Ce (χ = 0, 1, 2) crystals were grown by the vertical Bridgman growth technique in evacuated quartz crucibles. X-ray excited optical luminescence spectra of GdI 3 :Ce exhibit a broad emission band (450 nm–650 nm) peaking at 520 nm corresponding to 5d 1 →4f 1 transition of Ce 3+ while the undoped GdI 3 crystal consists of a broad band (400 nm-600 nm) and several sharp lines peaking at 462 nm, 482 nm, 492 nm, 549 nm, 579 nm owing to the impurities ions and defects. The excitation spectra of Ce 3+ doped GdI 3 consist of two broad bands between 300 nm and 500 nm corresponding to 4f 1 →5d 1 absorption of Ce 3+ . The other absorption peaking at 262 nm in the spectrum of GdI 3 :2%Ce is assigned to band-to-band exciton transition. The excitation spectrum of undoped GdI 3 contains a flat absorption band from 330 to 370 nm and a broad band between 390 and 450 nm peaking at 414 nm corresponding to the absorption of the unintentionally doped Ce 3+ , Dy 3+ , Ho 3+ impurities and other defects. The emission spectrum of undoped GdI 3 under 332 nm excitation has the identical line peaks with the spectrum measured under X-ray excitation. The emission spectra of GdI 3 :2%Ce and GdI 3 :1%Ce show a broad band in the range of 450–750 nm with the maximum at 550 nm corresponding to 5d 1 →4f 1 transitions of Ce 3+ ion. The GdI 3 , GdI 3 :1%Ce and GdI 3 :2%Ce show fast principle decay time constant 73 ns, 69 ns and 58 ns respectively, besides, the undoped also shows a slow decay constant 325 ns which doesn't appear in Ce 3+ -doped GdI 3 crystal. The energy resolutions of GdI 3 :χ%Ce (χ = 1, 2) measured at 662 KeV are about 3%–5% and the undoped GdI 3 is 13.3%.