Time-resolved luminescence and excitation spectroscopy of co-doped Gd3Ga3Al2O12 scintillating crystals

Abstract

Cerium doped Gd3Ga3Al2O12 (GGAG) single crystals as well as GGAG:Ce single crystals co-doped by divalent (Mg2+, Ca2+) and tetravalent (Zr4+, Ti4+) ions have been studied by means of time-resolved luminescence as well as the excitation luminescence spectroscopy in vacuum ultraviolet (VUV) and soft X-ray (XUV) spectral range. Tunable laser excitation was applied for time-resolved experiments in order to obtain luminescence decay curves under excitations in Ce3+, Gd3+ and excitonic absorption bands. The influence of the co-dopant ions on the Ce3+ luminescence decay kinetics is elucidated. The fastest luminescence decay was observed for the Mg2+ co-doped crystals under any excitation below bandgap energy indicating the perturbation of the 5d states of Ce3+ by Mg2+ ions. Synchrotron radiation was utilized for the luminescence excitation in the energy range from 4.5 to 800 eV. Special attention was paid to the analysis of Ce3+ excitation spectra in VUV and XUV spectral range where multiplication of electronic excitation (MEE) processes occur. Our results demonstrated that GGAG:Ce single crystals co-doped by Mg2+ ions as well as the GGAG:Ce crystal annealed in vacuum reveal the most efficient excitation of Ce3+ emission in VUV-XUV excitation range. The role of intrinsic defects in MEE processes in the co-doped as well as in the annealed GGAG:Ce single crystals is discussed.

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

“…A broad absorption shoulder near 235 nm can be ascribed to transitions toward higher excited states of Ce 3+ (5d 3,4,5 ). 17 The absorption edge of the host shows the onset at 220 nm, which is closely similar to that of GGAG:Ce. 2 3.1.2.…”

“…In the GSAG:Ce0.1% sample, there are additional two dominating peaks at 450 and 341 nm, corresponding to 4f-5d 1 and 4f-5d 2 transitions of Ce 3+ , respectively. A broad absorption shoulder near 235 nm can be ascribed to transitions toward higher excited states of Ce 3+ (5d 3,4,5 ) . The absorption edge of the host shows the onset at 220 nm, which is closely similar to that of GGAG:Ce …”

“…However, its scintillation decay still contained longer components (τ 2 ≥ 200 ns). Multicomponent garnets of general host composition (Lu,Y,Gd) 3 (Al,Ga) 5 O 12 doped by fast Ce 3+ and Pr 3+ luminescent centers have been studied and reported by a number of laboratories. − One of the two possible strategies to improve the scintillation performance of GAGG is the previously mentioned band gap engineering. , The second strategy consists of codoping with divalent ions (e.g., Ca 2+ or Mg 2+ ), which stabilize the Ce 4+ centers. ,− These centers compete with electron traps in the material for the capture of an electron from the conduction band. As a result, the intensity of slow radiative recombination processes is reduced.…”

Sapozhnikovite, Na8(Al6Si6O24)(HS)2, a new sodalite-group mineral from the Lovozero alkaline massif, Kola Peninsula

“…7) are attributed to the π u → π g * transitions in S 2 •– . The narrow bands with the maxima at ~ 30,200, ~35,000, and ~36,700 cm –1 are due to the transitions from the 6 S 7/2 level to 6 P J , 6 I J , and 6 D J in Gd 3+ , respectively (Pankratova et al , 2020). Gd 3+ and Nd 3+ ions may be located in sodalite cages.…”

Luminescence and Vacuum Ultraviolet Excitation Spectroscopy of Nanophosphors under Synchrotron Irradiation

“…The last facility provides an extremely wide excitation range for luminescence measurements (4.5-1500 eV) covering UV, VUV, and soft X-ray energy dispersion [37] and it demonstrates high potential in the luminescence studies for a wide class of inorganic materials. [10,[38][39][40][41][42][43] It is worth noting that since autumn 2021 new SUPERLUMI setup will be available for regular users at PETRA III storage ring of DESY synchrotron in Hamburg (Germany). [44]…”