Composition-Engineered GSAG Garnet: Single-Crystal Host for Fast Scintillators

Abstract

The growth process and the optical, luminescence, and scintillation characteristics of the composition-engineered Gd2.88Sc1.89Al3.23O12 (GSAG) single crystal doped with 0.1% Pr3+ and 0.1, 0.2, and 0.3% Ce3+ grown by the μ-PD method are investigated. The GSAG:Ce single-crystal scintillator grown in Mo crucible is evaluated for the first time. The comparison of the scintillation properties of GSAG:Ce using Mo and Ir technologies is presented. The effect of annealing in air and Mg2+ codoping is also discussed. In the case of the Ce dopant, the favorable combination of ultralow afterglow, fast scintillation response, and high-density host together with a cheaper preparation technology makes these materials competitive and promising for a wide range of applications.

Novel Phenomenon of Scintillation Performances with the Component Variation in the Mg Co-/Nondoped GAGG:Ce Crystal

“…The XRD patterns of non-co-doping and Mg 2+ codoping GAGG:Ce crystals were measured after grinding into uniformly distributed powders, as shown in Figure 3. All of the diffraction peaks of the samples match well with the 4a, there are sharp absorbance peaks at around 270 and 315 nm, which are due to the 8 S 7/2 − 6 I x and 8 S 7/2 − 6 P x transitions of Gd 3+ ions, 29,30 respectively. The 450 and 345 nm peaks correspond to 4f−5d 1 and 4f−5d 2 transitions of Ce 3+ , 12,16 respectively.…”

“…Figure compares the absorption spectra for two sets of GAGG crystals with various Ce concentrations. In Figure a, there are sharp absorbance peaks at around 270 and 315 nm, which are due to the 8 S 7/2 – 6 I x and 8 S 7/2 – 6 P x transitions of Gd 3+ ions, , respectively. The 450 and 345 nm peaks correspond to 4f–5d 1 and 4f–5d 2 transitions of Ce 3+ , , respectively.…”

Radiation Damage of GSAG:Ce Crystals with Codopants under Gamma‐Ray Irradiation

“…A wide absorption band with a weakly defined maximum at ≈620 nm and a long‐wavelength tail extending to 750 nm dominate in the initial spectrum, indicating a defect structure in the crystal. Transmittance of the original sample at 565 nm (emission maximum of Ce 3+ [ 12,14 ] is 79%, which decreases after irradiation to 77%. The same profile of the transmission spectra before and after irradiation indicates that the center responsible for the absorbing band at ≈620 nm is preserved.…”

“…Since then, a number of studies on GSAG:Ce were published, which concerned the energy transfer between Gd 3+ and Ce 3+ , [ 11 ] preparation of Ce‐doped layers for lighting applications, [ 12 ] and transparent ceramics for high‐power light‐emitting diodes. [ 13 ] In the latest study, [ 14 ] GSAG:Ce(Pr) crystals were successfully grown by the micropulling method from Gd 2.88 Sc 1.89 Al 3.23 O 12 melts prepared from 4 N pure starting oxides and using an Ir crucible in N 2 atmosphere and a Mo crucible in an Ar + 5%H 2 reducing atmosphere. The reported photoluminescence decay constant in the sample with Ce (0.1%) was 41 ns, but the scintillation decay under Cs‐137 excitation at 662 keV was much slower (70–239 ns depending on composition and growth technology).…”

“…The highest light yield value of 10 160 ph MeV −1 was measured in a GSAG:Ce(0.3%) sample grown in a Mo crucible and then annealed in air, which led to elimination of parasitic absorption due to scattering centers resulting from the incorporation of Mo from the crucible. [ 14 ] Due to the presently very high price of Ir, there is currently new interest in using Mo and W crucibles, instead of Ir crucibles, especially in Czochralski growth (see, e.g., [ 15 ] and studies therein).…”