Czochralski Growth of ${\rm Ce}^{3+}$-Doped ${\rm Li}_{6}{\rm Gd}({\rm BO}_{3})_{3}$ Single Crystals

Abstract

The Ce 3+ doped Li 6 Gd(BO 3 ) 3 (LGBO) crystal is a promising scintillation crystal for thermal neutron detection. This crystal can be grown by Czochralski technique or modified Bridgman method for its melting point at about 848 C. With a lower radial temperature gradient, the LGBO crystal using CeO 2 as dopant host (CeO 2 : LGBO) can only be grown with the diameter less than 15 mm with a smaller shouldering angle. The viscosity of the melt will be decreased and the crystal diameter can be effectively enlarged by using CeF 3 as dopant host (CeF 3 : LGBO) when the crystals are grown with the same growth parameters. By increasing the radial temperature gradient, larger diameter single crystals of CeO 2 :LGBO with the diameter of 30 mm or 40 mm have been grown with a larger shouldering angle. The excitation and emission peaks will red shift and the X-ray excited luminescence emission intensity will be increased by using CeF 3 instead of CeO 2 as dopant host.

Growth and spectroscopic properties of 6Li- and 10B-enriched crystals for heat-scintillation cryogenic bolometers used in the rare events searches

“…The anharmonic contributions to interatomic potentials are expected to be important in the three crystallographic directions in this compound. Because of the propensity of borate liquids to supercool, 22,23 the initial stage of the growth, which consists of stabilizing the meniscus on the seed over a growth distance of y6 mm, requires large axial and radial thermal gradients, typically 50 uC cm 21 and more, to avoid solidification that is too fast and uncontrolled. In a purely resistive heating furnace and at moderately high temperatures, the design of high thermal gradients is more difficult than with induction heating systems.…”

“…The Eu-concentration of the 6 Li 6 Eu( 10 BO 3 ) 3 crystals was measured by scanning the (-102) and (010) facets at a depth down to 2.4 mm by means of EPMA (Cameca SX 100, 20 keV electron beam, already described in ref. 16), which gave 5.18 6 10 21 Eu cm 23 .…”

“…19 All the atomic positions were refined and then anisotropic displacement parameters (ADP) were considered for all the atoms. The occupancy of the Eu atom was refined to 0.965(2), leading to a concentration of 5 6 10 21 Eu cm 23 . This Eu concentration was used to calibrate the optical absorption spectra in cross section units.…”