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Zhuravleva, Mariya

Publications and source records attributed to Zhuravleva, Mariya.

23 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Crystal growth and scintillation properties of pure and Tl-doped Cs 3 Cu 2 I 5

Here, the Bridgman crystal growth and scintillation properties of both undoped and Tl-doped Cs 3 Cu 2 I 5 are presented. This material is very attractive for gamma and X-ray detection applications, with a density of 4.53 g/cm 3 and effective atomic number of 51.9. Undoped Cs 3 Cu 2 I 5 had a light yield of 41,500 photons/MeV, with an energy resolution of 4.4% at 662 keV. Thallium doping at 0.5 mol % resulted in a much-improved scintillation response, in which light yield increased to 98,200 photons/MeV and energy resolution reduced to 3.3% at 662 keV. The X-ray excited emission is centered at 442 nm for the undoped and 500 nm for the Tl-doped crystals. The undoped emission is broad, typical of excitonic emission, while thallium doping results in an even broader band with features of both the undoped and thallium defect-mediated emissions.

36 MATERIALS SCIENCE↗
DOE OSTI2020

TlSr 2 I 5 :Eu 2+ - A new high density scintillator for gamma-ray detection

In this paper we report on the scintillation properties of TlSr 2 I 5 doped with Eu 2+ , a novel thallium-containing high-resolution scintillator for gamma-ray spectroscopy. Here, small diameter, good quality crystals of TlSr 2 I 5 :Eu (TSI) with different Eu 2+ concentrations were grown by the vertical Bridgman method. X-ray diffraction measurements show that single crystals of TSI belong to the monoclinic system with space group P2 1 /c. TlSr 2 I 5 has a density of 5.32 g/cm 3 and effective Z of 60. The X-ray excited emission of Eu 2+ doped TlSr 2 I 5 features a broad emission band peaking between 460–470 nm. The light yield of TlSr 2 I 5 crystal doped with 1% Eu 2+ is measured to be ~72,000 ph/MeV with an energy resolution of 2.8% at 662 keV. The scintillation decay time which is characteristic of Eu 2+ shows two components, with 90% of the light in a ~500 ns component and the rest in a longer component of ~3 μs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Crystal growth and scintillation properties of new ytterbium-activated scintillators Cs 4 CaI 6 :Yb and Cs 4 SrI 6 :Yb

Yb 2+ was investigated as a potential alternative activator for Cs 4 SrI 6 and Cs 4 CaI 6 scintillators for the first time, as opposed to the previously studied Eu2+ activator. Single crystals with nominal Yb 2+ concentrations of 0.5 mol%, 1 mol%, and 3 mol% were grown in Ø7 mm ampoules using the vertical Bridgman method. Luminescence and scintillation properties were evaluated as a function of Yb 2+ concentration and host compound. Here, the 5d → 4f electronic transition of Yb 2+ was observed for both the Sr- and Ca-containing compositions. X-ray induced radioluminescence emission was centered between 449 nm and 463 nm depending on Yb 2+ concentration and host compound. Both the spin-allowed and spin-forbidden transitions were observed in photoluminescence emission spectra and were centered at 446 nm and 476 nm, respectively, for both compounds. The best scintillation performance was achieved with Cs 4 CaI 6 :Yb 1 mol%, which had a 3.5% energy resolution at 662 keV and 43,000 ph/MeV light yield. To our knowledge this is the best energy resolution ever reported for a Yb 2+ -doped scintillator. Additional Cs 4 CaI 6 :Yb 1% crystals were grown in Ø12 mm ampoules to investigate the size dependence of scintillation properties, as well as crystal homogeneity.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Crystal Growth and Elemental Homogeneity of the Multicomponent Rare-Earth Garnet (Lu 1/6 Y 1/6 Ho 1/6 Dy 1/6 Tb 1/6 Gd 1/6 ) 3 Al 5 O 12

We report high-entropy aluminum garnets were grown as bulk single crystals using the micro-pulling-down method, taking the synthesis of complex ceramics a step further from the conventional preparation of polycrystalline materials. We studied the effects of growth parameters on the elemental distribution in high optical quality crystals of (Lu 1/6 Y 1/6 Ho 1/6 Dy 1/6 Tb 1/6 Gd 1/6 ) 3 Al 5 O 12 containing six cations (yttrium and rare-earths) taken in equimolar amounts. A single garnet structure was confirmed by powder X-ray diffraction. Electron microprobe measurements were obtained to correlate the radial distribution of rare-earth elements with pulling rates and molten zone height. The nature of the elemental distribution in the radial direction was associated with ionic radius: smaller rare-earths concentrated in the center of the crystal, while larger rare-earths segregated toward the outer edge of the cylindrical crystal. Faster pulling rates led to a flattening of the concentration profiles toward the nominal concentration, promoting a more homogeneous radial elemental distribution, while varying the molten zone height did not have a significant effect. The demonstrated success with crystal growth enables the practical availability of single crystals of multicomponent aluminum garnets for further discovery of new phenomena and applications.

36 MATERIALS SCIENCE↗