Czochralski growth of 2 in. Ce-doped (La,Gd)2Si2O7 for scintillator application

Abstract

Growth of 2-inch diameter Ce-doped (La,Gd)2Si2O7 (La-GPS) scintillating crystals by Czochralski method using Ir crucible is reported. The composition of the host material was approximately equal to La0.5Gd1.5Si2O7 and the concentration of the Ce 3+-activator was either 0.5 or 1.5 at.% with respect to the total content of the rare-earths forming the host crystal matrix. Effects of the hot zone construction including inductive coil position, presence/absence of the after-heater, rotation rate and other growth parameters on the crystal quality are discussed in some details. The crystals produced in optimized conditions were colorless, transparent, uniform in their shape, crack-and inclusions-free, and demonstrated smooth glass-like surface. The length of the crystals' cylindrically-shaped body parts exceed 100 mm. The growth results were well reproducible. The main disadvantage of the growth process is associated with short lifetime of the Ir crucible and its deformation caused by thermal expansion of the pre-solidified melt at each heating stage.

Characterization of LaGPS:Ce scintillation crystals obtained under a reducing atmosphere

“…Such conditions imply the rapid oxidation, deformation, and destruction of iridium crucibles. 9 As the processing of iridium crucibles is a major component of the crystal cost and bearing in mind the record high Ir prices in the market, 10 there is no reliable method of mass production for bulk rare-earth pyrosilicates.…”

Performance evaluation for a radiation imaging detector using single-crystal GPS (Ce) plate

“…An alternative method was using a scintillator plate made of small grains of GPS (Ce) combined with a binder [5]. Other efforts were made to modify the composition of the scintillator by replacing a part of the gadolinium (Gd) with lanthanum (La) to grow single crystals more easily [5]- [10]. Nowadays, GPS (Ce) is commercially available [11], with sizes of up to 25 mm diameter × 25 mm height.…”