Crystal Growth and Scintillation Properties of Strontium Iodide Scintillators

Single crystals of SrI₂:Eu and SrI₂:Ce/Na were grown from anhydrous iodides by the vertical Bridgman technique in evacuated silica ampoules. Growth rates were of the order of 5-30 mm/day. Radioluminescence spectra of SrI₂:Eu and SrI₂:Ce/Na exhibit a broad band due to Eu²⁺ and Ce³⁺ emission, respectively. The maximum in the luminescence spectrum of SrI₂:Eu is found at 435 nm. The spectrum of SrI₂:Ce/Na exhibits a doublet peaking at 404 and 435 nm attributed to Ce³⁺ emission, while additional impurity-or defect-related emission is present at approximately 525 nm. The strontium iodide scintillators show very high light yields of up to 120 000 photons/MeV, have energy resolutions down to 3% at 662 keV (Full Width Half Maximum) and exhibit excellent light yield proportionality with a standard deviation of less than 5% between 6 and 460 keV.