Crystal growth and spectroscopic performance of large crystalline boules of CsCaI3:Eu scintillator

Abstract

a b s t r a c tThe crystal growth of CsCaI 3 :Eu with improved quality over prior efforts for use in X-ray and gamma-ray detection applications is reported. Boules were grown using the vertical Bridgman technique in quartz ampoules at 15, 22, and 35 mm diameters. CsCaI 3 :Eu crystals show evidence of a heavily twinned microstructure likely caused by a solid-solid phase transformation of the crystal during the cooling process. Energy resolution (FWHM) in large and small samples taken from crystalline boules varies between 13% and 4.5% for 662 keV gamma rays indicating volumetric non-uniformity. Scintillation decay time is shown to increase with volume. Proportionality of the light yield of CsCaI 3 :Eu is reported for the first time.

Improvement in the optical quality and energy resolution of CsSrBr3: Eu scintillator crystals

“…And while the twinning does not appear to affect the optical transparency of the crystals it may have some effect on the scintillation performance. Similar twinning can be observed in other metal halide scintillator crystals like europium doped cesium calcium iodide (CsCaI 3 : Eu) [15]. The twinning in CsSrBr 3 is thought to arise due 233 to a solid-solid phase transition.…”

“…This insures a flat or convex interface, both 105 of which are better suited for improved crystal growth. Previous crystal growth experiments 106 carried out in a transparent furnace have suggested that the use of a diaphragm also minimizes 107 the migration of the growth interface due to a heat sinking effect of the charge, which may cause 108 the growth rate to fluctuate over time [15]. The crystal was then grown by translating the 109 ampoule through the furnace at a pulling rate of 0.5 mm/hour.…”

Phase Diagrams and Stability of Lead-Free Halide Double Perovskites Cs2BB′X6: B = Sb and Bi, B′ = Cu, Ag, and Au, and X = Cl, Br, and I

“…In principle, the perovskite structure can be retained by using homovalent Pb replacements. In practice, however, the substitution of Pb by other divalent metals in the Periodic Table leads either to unstable perovskites or to stable semiconductors with band baps larger than 2.7 eV, , such as halide perovskites based on the alkali earth metals Ca, Sr, or Ba. − …”

Analysis of chemical stress and the propensity for cracking during the vertical Bridgman growth of BaBrCl:Eu

“…Instantaneous thermal stresses may promote cracking, as posited by the prior studies referred to above [9][10][11][12][13], and the important role of such thermal stresses on cracking has been documented in many prior experimental studies [14][15][16][17][18][19][20][21][22][23]. However, a solid can also experience residual stresses remaining in the material after the original cause has been removed [24] that can delay cracking to during unloading or processing.…”