This work focuses on the development of fast-timing inorganic scintillators for use in cutting-edge particle physics experiments at colliders and time-of-flight positron emission tomography (TOF-PET). Significant progress in enhancing the timing performance of Y3Al5O12 (YAG) scintillators is reported, achieved by optimizing the codoping conditions with Ca2+ and Mg2+. The optimized crystals exhibit fast rise and decay times of 30 ps and 26 ns, respectively, alongside with an impressive coincidence time resolution (CTR) of 131 ps, while maintaining a high light output of over 22,000 pH/MeV. The incorporation of dopants into the YAG lattice is explored, providing insights into the mechanisms driving scintillation response in YAG:Ce,Ca,Mg crystals. Furthermore, uniformity in scintillation properties was demonstrated along a large, 120 mm-long YAG:Ce,Ca,Mg ingot, which was grown using the Czochralski method in a tungsten crucible.

This work deals with the optimization of bismuth silicate, Bi4Si3O12 (BSO) scintillation crystals as candidates for future high energy physics experiments at colliders involving the registration of both scintillation and Cherenkov light. Crystals with a high transparency in UV-band and a high timing resolution are required for this application. Czochralski process was employed for BSO crystal growth in Pt crucibles in a dynamic growth atmosphere. After the growth of a series of crystals in air, as well as mixed Ar-air static and dynamic atmospheres, it was shown that the mixed atmosphere minimizes Bi2O3 evaporation and reduces the amount of Pt dissolved in the melt by several times. This caused the reduction in the number of foreign inclusions in the grown crystals, providing a transparency of over 70 % in the > 300 nm range, a light output of up to 2140 ph/MeV, an energy resolution of 21.5 % at 662 keV gamma-rays, while a coincidence time resolution was improved from 148 to 125 ps.

The work deals with timing characteristics of garnet scintillation materials, especially for applications like time-of-flight PET or future collider experiments. While cerium-activated oxide scintillation single crystals are known for their fast performance due to rapid d-f relaxation in Ce 3+ . Meanwhile, the extended scintillation decay time of Gd 3 (Al,Ga) 5 O 12 :Ce (GAGG:Ce), the brightest oxide scintillator, still does not meet the requirements for the upgrade 2 of the central part of the LHCb electromagnetic calorimeter in CERN. Additionally, GAGG:Ce and other Ga-containing scintillators are typically grown in large sizes exclusively in Ir crucibles. Attempts to substitute Ga with Sc in the gadolinium garnet Gd 3 (Al,Sc) 5 O 12 :Ce (GSAG:Sc,Ce) grown from Mo crucibles resulted in a significant decrease in light yield compared to GAGG:Ce, although without a notable improvement in timing.The results obtained in this work certify that tuning the doping concentrations of Ca2+ and Mg2+ ions provides the enhancement of timing performance of Ce-doped YAG and GAGG scintillators due to elimination of carrier traps and acceleration of carrier transport to luminescence centers, independently on the host composition. Apart of that, YAG is more promising as host, because it can be obtained in cheap W/Mo crucibles in contrast to GAGG and other Ga-containing crystals. Due to the synergy between Ca2+ and Mg2+ dopants in garnets hosts, we demonstrated that improved combination of light yield and decay time can be achieved in Ce-doped garnets, i.e. larger number of prompt photons can be generated for fast-timing applications. At the same time, Sc,Ca codoped YAG:Ce is another promising approach to get fast scintillation crystals with a high light yield that may be grown by a cheap technology from W crucibles.

For the first time to the best of our knowledge, CeAlO 3 nanocrystals with perovskite structure are synthesized by pulsed laser ablation technique. The morphological and optical properties of the obtained CeAlO 3 nanocrystals are investigated. This work opens new prospects for the application of laser ablation methods for the generation of perovskite nanocrystals and development of novel nanocomposite structures, which can be applied for the fabrication of perovskite solar cells, scintillation detectors, catalysts, etc.

Growth technologies of oxide crystals in W/Mo crucibles have been developed as a low-cost alternative to conventional processes involving Ir crucibles. Carbon-containing atmosphere needed to protect crucibles from oxidation leads to the introduction of carbon into the crystal lattice and creation of carbon-related defects, which affect the scintillation performance. Meanwhile, a search for fast scintillators for the new generation of positron-emission tomographs and high-energy physics experiments at colliders is under way. Codoping with divalent cations has become an efficient way to suppress long components of scintillation decay in Ce-doped scintillators. This work addresses Y 3 Al 5 O 12 (YAG) crystals codoped with carbon, cerium activator, and divalent cations. Optical and scintillation properties of YAG:Ce,C, $\text{A}^{2+}$ crystals (A = Ca $^{2+}$ , Mg $^{2+}$ , Ba $^{2+}$ , Sr $^{2+}$ ) are systematically studied. Among all the studied garnet compounds, YAG:Ce,C,Ca $^{2+}$ crystals demonstrated the fastest scintillation decay times, which are promising for the mentioned applications. Mechanisms of scintillation process in the studied materials are discussed. The Ce $^{3+}$ /Ca $^{2+}$ ratio in YAG:Ce,C,Ca $^{2+}$ was optimized to minimize slow components in scintillation decay.

Sesquioxides of lanthanides, yttrium, and scandium are promising hosts for laser and scintillation materials; however, the crystallization of such compounds is complicated by very high melting temperatures, as well as polymorph transitions. This work reports for the first time the growth of Y2O3 and Y2−xScxO3 crystals by the Vertical Gradient Freezing method from tungsten crucibles, proposing an alternative to extremely expensive rhenium and iridium crucibles. Translucent Y2O3 samples are obtained, and their luminescent and scintillation parameters are evaluated. The main issues of Y2O3 crystallization under the proposed conditions are discussed, as well as ways of enhancing the crystal quality. Finally, polymorph transitions are avoided by decreasing the average radius of the rare earth cation by Y3+/Sc3+ substitution, providing transparent Y2−xScxO3 crystals with a cubic structure.

The paper addresses cost-efficient methods of crystal growth from W crucibles in the reducing Ar + CO atmo-sphere. Lu3Al5O12 (LuAG:Ce) and (Lu1-xYx)3Al5O12 (LuYAG:Ce) scintillating crystals were grown by the Czo-chralski technique. The impact of Ce concentration on optical and scintillation properties of LuAG:Ce crystal was evaluated, as well as the optimal Lu/Y ratio in LuYAG:Ce was selected. The optical and scintillation properties of the grown crystals were investigated. The light yield in the mixed crystals reached 28,000 phot/MeV, while the energy resolution at 662 keV amounted to 10.3%. The effect of carbon co-doping due to the growth under the CO-containing atmosphere at the optical and scintillation performance of the crystals is discussed.

Ce-doped lanthanum gadolinium pyrosilicates are among the most efficient oxide scintillation crystals with a light yield of ca. 40 000 ph MeV −1 and a high energy resolution.

This paper addresses the carbon co-doping of Ce-doped garnets, an efficient scintillation material and white light phosphor. The composition and the optical and scintillation properties of carbon-co-doped Y3Al5O12 (YAG) are studied at different cerium and carbon concentrations. YAG:Ce,C crystals were grown in the Ar + CO atmosphere from W crucibles. The carbon concentration reaches 0.5 atom %, but it does not affect the Ce distribution coefficient. The appearance and elimination of color centers are discussed in comparison to Ce-free YAG:C crystals. The tuning of cerium and carbon concentrations provides a light yield enhancement of up to 29 600 phot/MeV. The achieved enhancement may extend the application range of garnet-type phosphors and scintillators.

The scintillation properties and radiation hardness of undoped and Ce doped YAG crystals, which were grown from tungsten crucibles in the Ar + CO atmosphere and annealed under different conditions, have been evaluated. The scintillation crystals obtained under such conditions have a high scintillation yield, demonstrate short scintillation kinetics with the major component of similar to 60 ns, and demonstrate high radiation resistance when irradiated with both gamma-quanta and high energy protons. The obtained results open up the opportunity to produce high-temperature garnet crystals using iridium-free technology, which forms the basis for a technology for mass production at an affordable price.

The feasibility to grow bulk La-GPS:Ce scintillation crystals by the Czochralski method using Mo crucibles has been reported.

This work is dedicated to the growth process and investigation of luminescent and scintillation properties of CeAlO3 single crystals and CeAlO3/CeAl11O18 metamaterials under e-beam and α-particles excitation. It has been shown that cathodoluminescence and radioluminescence spectra of CeAlO3 crystals contain two bands, peaking at 440 and 500 nm, and caused by the Ce3+ 5d–4f transitions into CeAl11O18 phase, which is present in these crystals as an admixture. Under 270 nm ultraviolet (UV) light excitation, a CeAlO3 crystal possesses complicated non-exponential luminescence decay, with the average decay time of 16 ns. The light yield of CeAlO3 crystals under α-particle excitation is about 16% and 12%, in respect to the standard Bi4Ge3O12 (BGO) crystal and Y3Al5O12:Ce (YAG:Ce) single crystalline film samples, respectively. The CeAlO3 scintillation decay is quite fast, with the decay time value t1/e in the 54–56 ns range.

Y3-xGdxAl5O12:Ce (x = 0.6, 1.2, 1.8 in the melt) single crystals were grown from the melt by the Czochralski technique. XRD results shown that crystalline samples contain main garnet Y(3-x)Gd(x)Al(5)O(12 )and additional Al2O3 and GdAlO3 phases. The maximal content of Gd3+ in the main garnet phase was determined at about of 40 at%. The presence of Al2O3 and GdAlO3 phases is explained by the thermal decomposition of Gd3Al5O12. The red-shift of Ce3+ emission with increasing of Gd3+ concentration in Y3-xGdxAl5O12:Ce was found. The latter is in a good agreement with data presented for Y3-xGdxAl5O12:Ce ceramics and powder phosphors. An additional 330-360 nm double-peaked emission observed in Y3-xGdxAl5O12:Ce crystals has been assigned to the 5d -> 4f radiative transitions of Ce3+ ions in GdAlO3 perovskite phase. In the view of potential application for white light-emitting diodes (WLEDs) light conversion characteristics tests of the Y3-xGdxAl5O12:Ce crystals were performed. The best parameters were obtained for Y3-xGdxAl5O12:Ce sample.

The work is motivated by the need for cheap garnet-based scintillators for new high energy physics experiments at colliders and medical equipment. During recent years, garnets became among the most studied scintillators due to a drastic enhancement of light yield achieved in (Lu,Y,Gd)3(Al,Ga)5O12:Ce multicomponent systems. Meanwhile, the production process of YAG- and LuAG-based crystals is easier and less expensive compared to the multicomponent garnets. This work addresses the preparation process and the optical and scintillation properties of YAG, YAG:Ce crystals grown in non-precious metal crucibles.

Scintillation performances of carbon‐doped YAG and YAG:Ce crystals obtained by the Czochralski method under novel conditions of Ar+CO reducing atmosphere is compared to their counterparts obtained by conventional technologies. While light yield and energy resolution in YAG crystals grown under different conditions is similar, a fast luminescence decay component of 4–6 ns is observed in YAG:C grown by the new procedure. Optimization of post‐growth thermal annealing procedure of YAG:Ce,C scintillator provides the very high light yield of 28 200 phot MeV−1, and the energy resolution of 7.8–8.5% at 662 KeV

Optical properties of YAG crystals grown and annealed under different atmosphere conditions have been compared. Simultaneously we have registered the surface composition of crystals and content of basic admixtures in the crystals grown under the reducing conditions. Unlike YAG grown under weakly oxidizing conditions in Ir crucibles and bleached under oxidizing annealing, YAG(Mo) crystals grown in Mo crucibles under reducing Ar + CO atmosphere can be bleached by both oxidizing and reducing thermal annealing. The bleaching of YAG(Mo) is not reversed by further annealing under any available conditions. Mechanisms of this phenomenon have been discussed, including a possible role of admixtures in elimination of color centers in YAG grown under the reducing conditions. (C) 2017 Elsevier B.V. All rights reserved.

A method of concentration of gas impurities contained in a melt into sealed cavities in a crystal has been proposed for the first time. This makes it possible to determine the amount of gases dissolved in the melt during crystallization by the Edge-defined Film-fed Growth (EGF) technique and the gas pressure in cavities inside the crystals. We also measure the composition of gas inclusions in crystallized melts of Al2O3, Y3Al5O12 and Bi4Ge3O12 and discuss it in connection with crystal growth procedure and quality of crystals.

The influence of the reducing Ar+CO atmosphere on the stages of starting raw material preparation, growth and post-growth annealing of yttrium aluminum garnet, Y3Al5O12 (YAG) crystals was studied. The chemical reactions involving CO atmosphere and its impact on the raw material, melt, and crystal composition are determined. Modification of YAG optical properties under the reducing annealing is discussed.