Effects of La, Gd, or Lu co-doping on crystal growth and scintillation properties of Eu:SrI2 single crystals

• We have grown rare-earth doped SrI2 single crystals by the μ-PD method.
• All diffraction peaks were ascribed to corresponding SrI2 plane indices.
• Luminescence originated from Eu2+ 5d-4f transition was observed near 435 nm.
• Eu7.5%:SrI2 crystals showed maximum light-yield and minimum energy resolution.

Eu:SrI2 and La, Gd or Lu co-doped Eu:SrI2 single crystals were grown by a modified micro-pulling-down method and the effects of rare-earth (RE) co-doping on the crystal growth and scintillation properties were investigated. RE-free Eu7.5 mol%:SrI2 and La, Gd or Lu 1 mol% co-doped Eu7.5 mol:SrI2 single crystals with high transparency were obtained. The powder X-ray diffraction measurements revealed that all the grown crystals had a single phase of SrI2 structure. In the X-ray radioluminescence spectra, emission peaks around 435 nm were observed for the Eu:SrI2 and La co-doped Eu:SrI2 specimens. The light yield of the La co-doped Eu7.5%:SrI2 specimens were lower than that of the RE-free Eu7.5%:SrI2 specimen due to the generation of some defects by La co-doping.