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A new one-dimensional hybrid [APCHA]Cu2I4 was designed and applied as an X-ray scintillator. It exhibits broad-band green emission with a high PLQY of 74.80% and excellent stability. It demonstrates radioluminescence property with a light yield of 28 336 photons MeV−1, detection limit of 41 nGyair s−1, and high spatial limit of 13.95 lp mm−1 in X-ray imaging. [ABSTRACT FROM AUTHOR]

X-ray detectors based on scintillators are widely used in the fields of medical imaging, high-energy physics, geological exploration, and industrial detection. The development of scintillation materials with different characteristics has become the focus of considerable research interest. Herein, we report a facile hydrothermal synthesis of Gd- and Eu-codoped LiLuF4 microcrystals (MCs), which exhibit strong luminescence of Eu3+ ion characteristic emission, characterized by distinct red fluorescence emission. The research shows that Gd3+ co-doping effectively improved the sensitivity and light yield of LiLuF4:Eu MCs by regulating the proportion of co-doping ions. In addition, the detection limit is 140.72 nGy s−1 for LiLuF4:Eu,Gd MCs, approximately 39 times lower than the dose requirement of medical diagnosis. Based on LiLuF4:Eu,Gd MCs with the superior scintillation properties, a MC-composited film with 250 μm thickness was prepared by a direct coating method. The uniform and high-loading scintillation film exhibits outstanding imaging performance with a high spatial resolution of 14.8 LP mm−1, which confirms the application potential of X-ray imaging. [ABSTRACT FROM AUTHOR]

In recent years, the development of new scintillation materials with red and near-infrared light emission has had significant advantages based on the development of an avalanche photodiode with high quantum yield. This study used a hydrothermal method to synthesize rare-earth-doped Cs2NaScCl6 crystals, in which a red emission of Cs2NaScCl6:Sm was investigated with high X-ray sensitivity and low detection limit. In addition, a tunable wavelength range of radioluminescence can be achieved, in which a near-white light emission can be generated by precisely controlling the proportion of Sm3+ and Tb3+ doping concentrations. Meanwhile, a Cs2NaScCl6:7%Sm scintillation film has been successfully prepared by direct coating with a thickness of 150 μm, which achieves a spatial resolution of 11.9 lp mm−1 based on X-ray imaging experiments. Therefore, this perovskite material has shown potential application as an eco-friendly multifunctional imaging material. [ABSTRACT FROM AUTHOR]

For a long time, single crystals of the organic compound TPB (1,3,5-triphenylbenzene) have been viewed as a scintillator material for indirect X-ray detection. We here attempt to explore their potential for direct detection. A TPB single crystal with a size of up to 20 × 6 × 4 mm3 and without obvious growth steps was obtained using a solvent volatilization method. It has an orthorhombic structure with a high-quality FWHM of as low as 0.059 and preferred grown orientations along (131) and (220). AFM images clarify the two-dimensional nucleation growth mechanism. The fitted bandgap of the as-grown crystal is about 3.65 eV. TPB detectors with vertical and coplanar electrodes with a resistivity of 2.56 × 1013 Ω cm and 6.68 × 1013 Ω cm, respectively, were prepared. The mobilities for electrons (μe) and holes (μh) for the coplanar device were calculated to be 1.12 cm2 V−1 s−1 and 1.02 cm2 V−1 s−1, respectively. Under a 50 kV X-ray beam, the detection limit is as low as 0.35 μGy s−1, and the sensitivity reaches 2.72 μC Gy−1 cm−2. The TPB devices have the ability to detect 241Am@5.49 MeV α particles, showing the full-energy peak collected from the holes with an energy resolution of 39.13% at 700 V. The mobility lifetime product of the TPB devices for electrons (μτ)e and holes (μτ)h were calculated to be up to 2.24 × 10−5 cm2 V−1 and 4.04 × 10−5 cm2 V−1, respectively. The TPB detector could present a spectral response to 241Am@59.5 keV γ-rays from the holes with an energy resolution of 44.25% at 1000 V, which shows the potential for both direct and indirect detection of high-energy radiation. [ABSTRACT FROM AUTHOR]

In recent years, hybrid manganese(II) halides (HMHs) have attracted wide attention due to their impressive optical properties, low toxicity, and facile synthetic processibility. Being effective reabsorption-free phosphors, these compounds demonstrate the potential to be used as low-cost solution-processable scintillators. However, most of the HMHs studied to date contain bulk organic cations and, as a result, are characterized by low density and low X-ray stopping power. For this reason, we studied manganese(II) bromides with compact organic cations such as formamidinium (FA+) and acetamidinium (AcA+). In particular, we synthesized four new phases, two of which are characterized by octahedral coordination of manganese ions ((FA)MnBr3 and (AcA)MnBr3) and red emission, whereas the other two have tetrahedrally coordinated Mn2+ ions ((FA)3MnBr5 and (AcA)2MnBr4) and green emission. Photoluminescence (PL) and radioluminescence measurements demonstrated high PL quantum yields and reasonable scintillation light yields of acetamidinium-based compounds. In addition, unlike most known HMH-based scintillators, the discovered materials have a relatively high density due to the small fraction of the volume occupied by organic cations, so their X-ray attenuation coefficients are comparable to the well-known oxide scintillators. [ABSTRACT FROM AUTHOR]

A single crystal of Zn2Te3O8 (ZTO) was grown using the conventional Czochralski technique. TGA analysis showed that the melting point of ZTO is 681 °C, while it exhibits a structural phase transition at 621 °C. The powder X-ray diffraction analysis of ZTO confirmed that it possesses a single crystalline monoclinic structure with the C2/c space group. An indirect band gap of 3.75 eV was estimated for the ZTO crystal based on its absorption spectrum. The X-ray-induced luminescence of the grown crystal comprised a broad band peaking at 565 nm, which can be tentatively assigned to the self-trapped exciton emission from the (Te3O8)4− molecular complexes. The photoluminescence measured under 280 nm excitation showed a broad band luminescence peaking at about 600 nm, and its intensity was significantly enhanced upon cooling the crystal from 300 K to 10 K. The photoluminescence decay time under 280 nm excitation was shown to have two exponential components in the range from 10 K to 175 K, which became a single exponential upon further heating the crystal. Low scintillation light was observed at room temperature both under α- and β-particle excitations from 241Am and 90Sr sources, respectively. The scintillation light yield measured under β-particle excitation from the 90Sr source was enhanced by about five orders of magnitude at 10 K in comparison to that at 300 K. The scintillation light yield measured at 10 K under the same experimental conditions for ZTO in comparison with the well-known cryogenic scintillator Li2MoO4 (LMO) was shown to have four times higher scintillation light. A single-crystal ingot of ZTO was obtained for the first time; however, it had several cracks due to its phase transition. Notably, scintillation at low temperatures for a Te-based crystal was observed for the first time. These preliminary findings are very promising and show that ZTO will be a good candidate for cryogenic phonon scintillation detectors for the 0νββ decay search of 130Te. [ABSTRACT FROM AUTHOR]

Compared with commercial bulk scintillators and halide perovskites, lanthanide-doped fluoride nanoscintillators (NSs) exhibit high photochemical stability, low bio-toxicity and tunable emissions. However, the widely employed hosts, such as NaGdF4, NaLuF4 and NaYF4, need many expensive rare earth salts and time-consuming reaction processes. In this work, lanthanide-doped NaBiF4 NSs were prepared by a facile rapid room-temperature reaction method. The obtained NSs present a hollow structure, strong scintillation intensity and ultra-weak afterglow. The scintillation intensity was enhanced by incorporating Gd3+ ions, but it was decreased after codoping with Ho3+ or Er3+ ions. By employing a NaBiF4:15Tb/10Gd NS integrated thin film as a nanoscintillator screen, a high spatial resolution of 12.5 lp mm−1 was achieved. Our results could promote the exploration of new kinds of NSs with low cost, high production and superior performances. [ABSTRACT FROM AUTHOR]

Colloidal semiconductor nanocrystals (NCs) have attracted a great deal of attention in recent decades. The quantum efficiency of many optoelectronic processes based on these nanomaterials, however, declines with increasing optical or electrical excitation intensity. This issue is caused by Auger recombination of multiple excitons, which converts the NC energy into excess heat, whereby reducing the efficiency and lifespan of NC-based devices, including lasers, photodetectors, X-ray scintillators, and high-brightness LEDs. Recently, semiconductor quantum shells (QSs) have emerged as a viable nanoscale architecture for the suppression of Auger decay. The spherical-shell geometry of these nanostructures leads to a significant reduction of Auger decay rates, while exhibiting a near unity photoluminescence quantum yield. Here, we compare the optoelectronic properties of quantum shells against other low-dimensional semiconductors and discuss their emerging opportunities in solid-state lighting and energy-harvesting applications. [ABSTRACT FROM AUTHOR]

For the first time, hafnia (HfO2) nanoparticles have been produced by photochemical synthesis. The photochemical route has been proven to be scalable, affordable, and straightforward to create monoclinic HfO2 nanoparticles with a size of tens of nanometers. The exploitation of this route offers a chance to create large amounts of dense nanoparticles with reduced costs and time of production for future creation of large area composite scintillators for fast timing techniques. Specific annealing treatments from 450 °C to 1000 °C have been targeted to tune the structural and morphological properties and optimize the luminescence of the nanoparticles. Hafnia nanoparticles annealed at low temperature display an amorphous structure. After thermal treatment at 1000 °C, HfO2 nanoparticles crystallize into a monoclinic phase, as evidenced by thermal analyses and X-ray diffraction. Radioluminescence and photoluminescence of HfO2 have been investigated at room temperature and 77 K. The emission band of hafnia covers a range from 300 to 600 nm and it can be attributed to defects within the matrix. In particular, the highest radioluminescence intensity appears in the crystalline sample annealed at 1000 °C, thanks to the higher crystallinity degree and the reduction of non-radiative channels and quenching defects. Photoluminescence and scintillation decay have evidenced the presence of the fast decay in the nanosecond time range. Thus, due to their size, density, and spectroscopic and timing features, monoclinic hafnia nanoparticles obtained by photochemical synthesis are attractive for potential creation of large area scintillating composites. [ABSTRACT FROM AUTHOR]

1 at% Ce3+-doped Gd3Ga2Al3O12 (GGAG) single crystals were grown by an optical floating zone (OFZ) method and a traveling solvent floating zone (TSFZ) method. To reveal their structure and chemical composition homogeneity, X-ray diffraction (XRD) and high-resolution inductively coupled plasma atomic emission spectrometry (ICP-AES) were conducted on the as-grown Ce:GGAG crystals at 4 different positions along the growth direction. Compared with the Ce:GGAG crystals grown by the OFZ method (Ce:GGAG-OFZ), the Ce:GGAG crystals grown by the TSFZ method (Ce:GGAG-TSFZ) presented better Ce3+ distribution homogeneity which varied from 0.21 to 0.29 at%. However, the segregation coefficient of Ce3+ in Ce:GGAG-OFZ was found to be higher than that in Ce:GGAG-TSFZ, revealing a different solidification rate between them. The comparison study shows that the photoluminescence (PL) intensity of Ce:GGAG-TSFZ is about twice higher than that of Ce:GGAG-OFZ and the maximum light yield (LY) of 35 340 photons per MeV also occurs in the former. Trap depths were measured to be 0.70 eV and 0.98 eV by TL glow curves. The LY value of Ce:GGAG-TSFZ along the growth direction fluctuated to a lesser extent with respect to that of Ce:GGAG-OFZ; the latter decreases gradually along the growth direction. It is concluded that the TSFZ method helps to improve the homogeneity of crystal composition when growing crystals with multiple compositions or incongruent compounds. [ABSTRACT FROM AUTHOR]

Due to the enlarged interlayer spacing of anion-inserted hydroxides and their increased surface area, the unique structure of double-layered hydroxides is often beneficial for electrochemical energy storage. This work demonstrates that Ce3+-regulated CoNi-layered double hydroxides (CoNi-LDHs) significantly enhance the kinetics of electron transfer and ion motion with increased layer positive charges and weakened O–H bonds. The Ce3+ addition enabled a high rate capacitance of 1000 F g−1 at an ultrahigh charge rate of 50 A g−1 compared with 1322 F g−1 at 1 A g−1. Served as Lewis acid sites, the substituting trivalent Ce3+ for Co2+ decreases the energy barrier of proton diffusion and promotes the fast charge storage kinetics by increasing the hole carrier concentration (6.74 × 1024 cm−3). The fabricated supercapacitor device achieves a high energy density of 30 W h kg−1 at a power density of 10 kW kg−1 (40 A g−1) based on the total mass of active materials. This work simultaneously enhanced intrinsic electronic conductivity and ion diffusion in an electrode by Ce3+ addition. [ABSTRACT FROM AUTHOR]

Halide perovskites are among the most attractive research hotspots in optoelectronic applications due to their excellent luminescence properties. In this paper, Li+ was successfully incorporated into a one-dimensional perovskite CsCu2I3 host and constructed as a novel neutron/gamma detection scintillator via the Bridgman method. XRD and ICP-MS were carried out, and the results were discussed. The Li-doped CsCu2I3 crystal exhibits a main emission peak at 575 nm originating from strongly localized 1D exciton emission and a high photoluminescence quantum efficiency of 18.7%. The CsCu2I3:Li crystal has a light yield of 10 900 photons per MeV and an energy resolution of 11.5% under 137Cs irradiation. The figure-of-merit (FoM) of the CsCu2I3:Li crystal has been estimated (about 0.8) under 252Cf radiation source. The crystal has a potential application for dual gamma–neutron detection. [ABSTRACT FROM AUTHOR]

Defect tuning in ceria to enhance its catalytic properties is a subject of great interest for the scientific community owing to the growing demand for catalytic materials in drug, automobile and chemical industries. Doping induced defect engineering was found to be one of the most sought out strategies particularly in oxides for achieving multifunctionality. Here, in this study, we have doped ceria with distinct sized trivalent rare-earth ions, namely, Y3+, Eu3+ and La3+, using combustion techniques. Positron annihilation lifetime spectroscopy (PALS) suggested enhanced defect density with doping in general and higher concentration of oxygen vacancies in La3+ doped ceria compared to Y3+ and Eu3+ counterparts. X-ray photoelectron spectroscopy (XPS) suggested the existence of both Ce3+ and Ce4+, with the former having higher fraction in CeO2:La3+ compared to CeO2:Y3+. The electron transfer resistance (Rct) reduced in all the doped samples when compared to undoped ceria and they demonstrated improved catalytic activity towards the oxygen reduction reaction (ORR). The highest reduction in Rct was seen in the 5% La doped sample owing to the very high concentration of oxygen vacancies and Ce3+/Ce4+ ratio and CeO2:5.0% La3+ showed the best performance towards ORR electrocatalysis. The studies are expected to help in further tuning the catalysts in terms of dopant concentrations, and in future work, the strategy will be to control the Ce3+/Ce4+ ratio and see its implication in both catalytic and magnetic applications. [ABSTRACT FROM AUTHOR]

Rb2CuBr3 nanocrystals with a high photoluminescence quantum yield (PLQY) of 75% were synthesized and then further mixed with polymethyl methacrylate to form flexible scintillators. The scintillators maintain a high PLQY, even after bending for 2000 cycles and storing in air for 28 days. X-Ray imaging of targeted objects was demonstrated based on the flexible scintillators, which exhibits a detection limit of 63 nGyair s−1 and a spatial resolution of 27.9 lp mm−1. [ABSTRACT FROM AUTHOR]

Crystals of metal hexachlorides Cs2MCl6 (M = Hf or Zr) have recently emerged as promising materials for scintillation applications due to their excellent energy resolution. In this work, we investigated the crystal structure and scintillation properties of Cs2HfCl6 and Cs2ZrCl6 crystals in the broad temperature range from 9 to 300 K. X-ray diffraction data confirmed the same cubic structure (space group Fm3m) for Cs2HfCl6 and Cs2ZrCl6 over the entire examined temperature range. The room temperature scintillation light yield of Cs2HfCl6 excited with a 137Cs γ-source is measured to be 24 800 photons per MeV, while Cs2ZrCl6 exhibits 33 900 photons per MeV resulting in energy resolutions of 5.3% and 4.5%, respectively. The alpha-to-beta ratio determined at room temperature for 5.5 MeV α-particles from an 241Am source is equal to 0.39 for Cs2HfCl6 and 0.35 for Cs2ZrCl6. The measurements of scintillation decay curves revealed complex kinetics due to delayed recombination processes. A tangible enhancement of the scintillation yield with heating is observed in the 125–150 K range. This effect is a manifestation of negative thermal quenching explained by thermal activation of trapped carriers. A model of the emission centre is proposed that consistently explains the observed changes of emission intensity with temperature in the crystals under study. [ABSTRACT FROM AUTHOR]

Crystals of metal hexachlorides Cs2MCl6 (M = Hf or Zr) have recently emerged as promising materials for scintillation applications due to their excellent energy resolution. In this work, we investigated the crystal structure and scintillation properties of Cs2HfCl6 and Cs2ZrCl6 crystals in the broad temperature range from 9 to 300 K. X-ray diffraction data confirmed the same cubic structure (space group Fm3m) for Cs2HfCl6 and Cs2ZrCl6 over the entire examined temperature range. The room temperature scintillation light yield of Cs2HfCl6 excited with a 137Cs γ-source is measured to be 24 800 photons per MeV, while Cs2ZrCl6 exhibits 33 900 photons per MeV resulting in energy resolutions of 5.3% and 4.5%, respectively. The alpha-to-beta ratio determined at room temperature for 5.5 MeV α-particles from an 241Am source is equal to 0.39 for Cs2HfCl6 and 0.35 for Cs2ZrCl6. The measurements of scintillation decay curves revealed complex kinetics due to delayed recombination processes. A tangible enhancement of the scintillation yield with heating is observed in the 125–150 K range. This effect is a manifestation of negative thermal quenching explained by thermal activation of trapped carriers. A model of the emission centre is proposed that consistently explains the observed changes of emission intensity with temperature in the crystals under study. [ABSTRACT FROM AUTHOR]

Scintillators can convert high-energy rays into ultraviolet or visible light and are widely used in medical diagnosis, safety inspection, and industrial flaw detection. Nowadays, conventional scintillation materials have certain limitations, including the extreme synthesis conditions and complex synthesis process of bulk scintillators, as well as toxicity and poor stability of perovskite quantum dots (QDs). Fluoride has high stability and simple synthesis, which can effectively solve these problems. LiYbF4 has the advantages of a larger atomic number and density, and the synthesis of LiYbF4:Tb nanocrystals (NCs) exhibited good stability to thermal injection. X-ray tests showed that Tb3+-doped LiYbF4 NCs were more sensitive to X-rays than the commercial scintillator BGO, and the detection limit was 360 nGy s−1, which was 1/15 of the medical X-ray detection dose rate. Our self-made scintillation film with a load of 40 wt% and a thickness of 150 μm had excellent X-ray imaging capabilities with a spatial resolution of up to 20 LP mm−1 (MTF = 0.35), which shows great application potential in the X-ray imaging of biological and non-biological structures. [ABSTRACT FROM AUTHOR]

Ce0.03Gd2.97Ga2Al3O12 (Ce:GGAG) single crystals were successfully grown by the traveling solvent floating zone method (TSFZ). A series of compositions, where the mole ratio is Gd2O3 : Al2O3 = 25 : 75, 27 : 73, 29 : 71, were investigated as solvents. The 25 mol% Gd2O3-75 mol% Al2O3 solvent component was found to be the most effective in stabilizing the molten zone to obtain a crystal rod with uniform diameter. The crystal cracks were relieved clearly due to the improved molten zone stabilization during the crystal growth process. XRD patterns of the obtained crystals prove the garnet structure without any evident second phase. The characteristic Ce3+ emission located at around 540 nm was presented in the photoluminescence and X-ray excited luminescence spectra. The scintillation light yield reaches up to 34 132 pho MeV−1 and scintillation decay time was optimized to 64 ns with a high fast decay component of about 85%. The TSFZ method demonstrated the growth feasibility of Ce:GGAG crystals that have an incongruent-melting trend with lower Ga/Al ratio in the compositions. [ABSTRACT FROM AUTHOR]

The current development status and future perspectives of Tl-based inorganic scintillators are highlighted in this study. The thallium (Tl) ion is known to exhibit highly efficient luminescence in the widely used NaI:Tl+, CsI:Tl+, and recently discovered Cs2Cu3I5:Tl+ scintillators. Besides being an efficient luminescence center, Tl possesses high density and atomic number, so that its presence in the host material increases the density and effective atomic number of the scintillators, which provides higher efficiencies for high-energy X- and γ-ray detection. Based on this idea, several novel efficient scintillators were reported by different research groups, which can be utilized in medical imaging, homeland security, space research, nuclear and high energy physics, rare event searches, and oil well logging. An overview of reported Tl-based scintillators and future directions for their improvements are discussed herein based on prior publications. [ABSTRACT FROM AUTHOR]

The quaternary tungstates Li3Ba2RE3(WO4)8 (RE = La–Nd, Sm–Ho) were obtained by a ceramic synthesis route and were characterized by powder and single crystal X-ray diffraction. The structures of Li3Ba2Pr3(WO4)8 and Li3Ba2Tb3(WO4)8 were refined from single crystal diffractometer data: RbLiBi2(MoO4)4 type, space group C2/c, a = 528.57(2), b = 1292.39(6), c = 1934.80(10) pm, β = 91.522(4)°, 2151 F2 values, 108 parameters for Li3Ba2Pr3(WO4)8 and a = 520.54(2), b = 1272.03(6), c = 1918.85(10) pm, β = 91.948(4)°, 2020 F2 values, 108 variables for Li3Ba2Tb3(WO4)8. Striking polyhedral building units in these tungstates are WO4 tetrahedra and LiO6 octahedra, while the mixed occupied site and the barium atoms have higher coordination numbers, i.e. RE/Li@O8 and Ba@O10. In addition to the powder quality assessment by means of reflection spectroscopy, the synthesized samples were studied for their suitability as a scintillator material. Therefore, X-ray excited luminescence measurements where performed. Apart from Li3Ba2Ce3(WO4)8 and Li3Ba2Nd3(WO4)8, all compounds show strong emission under X-ray irradiation. Li3Ba2La3(WO4)8 and Li3Ba2Gd3(WO4)8 show blue CT luminescence caused by tungstate units, while the other samples show typical and multiple lines due to well known [Xe]4fn → [Xe]4fn transitions. [ABSTRACT FROM AUTHOR]

Scintillators, which can emit visible photons under γ- or X-ray excitation, are widely used in radiation detection. Traditional inorganic scintillators usually have some drawbacks, such as hygroscopicity or a high synthesis temperature, and most of them are poisonous. Hence, we report the synthesis of metal iodate scintillators (Eu(IO3)3 and Tb(IO3)3) by a facile hydrothermal reaction that exhibit good radioluminescence (RL) intensity. To further increase the RL intensities, we prepared Eu(IO3)3:xSm and Tb(IO3)3:xGd with stronger RL intensities and higher sensitivities than BaF2 and PbWO4 powders when x = 3%. Furthermore, we obtained scintillating films consisting of Eu(IO3)3:3%Sm and Tb(IO3)3:3%Gd for X-ray imaging. Our Eu(IO3)3:3%Sm and Tb(IO3)3:3%Gd films revealed excellent luminescence under high-energy X-ray excitation and spatial resolutions down to 9 lp mm−1 and 8 lp mm−1, respectively. Thus, these films can be regarded as candidate materials for X-ray imaging. [ABSTRACT FROM AUTHOR]

We present X-ray-excitable organic ultralong room temperature phosphorescence (X-OURTP) for afterglow scintillators through implanting lone-pair electron involved n–π* transitions and efficient charge transfer characters into H-aggregations of organic crystals. The thus designed X-OURTP molecule exhibits ultralong lifetimes up to 790 ms, high phosphorescence quantum yields of ∼8%, and excellent scintillation stability. These findings will pave the way to the design of organic afterglow scintillators, simulating extensive investigations on the extraordinary X-OURTP. [ABSTRACT FROM AUTHOR]

A new self-activated X-ray scintillator, BaWO2F4, with an excellent photoluminescence quantum efficiency is reported. Hydrothermally grown single crystals, space group P2/n, exhibit a 3D framework structure containing isolated WO2F4 octahedra. BaWO2F4 exhibits green emission under UV light with a high quantum yield of 53% and scintillates when exposed to X-rays(Cu). [ABSTRACT FROM AUTHOR]

Characterization of copolymers requires the measurement of two distributions—molecular weight (MW) and chemical composition (CC). Molecular weight distributions (MWD) are traditionally determined using size exclusion chromatography (SEC) run under isocratic solvent conditions. Chemical composition distributions (CCD) are often determined using liquid adsorption chromatography (LC) with solvent gradients. The use of solvent gradients, however, often limits options of compatible detectors. A gradient compatible, universal linear mass concentration detector is a longstanding unmet need. Many industrially-relevant polymers lack chromophores or other discriminating moieties requiring detectors with a universal response. Differential refractive index (dRI) is incompatible with gradient elution due to its small dynamic range. Charged aerosol detectors (CAD) and evaporative light scattering detectors (ELSD) are probably the most promising options for gradient elution detection, but both suffer from a nonlinear mass concentration response. Silicon photonic microring resonators are optical sensors that are responsive to changes in the local refractive index (RI). The substantial dynamic range of this technology makes it attractive for refractive index-based detection during solvent gradient elution. Previously, the microring resonator platform was used as a SEC detector to characterize the MWD of broadly dispersed polystyrene (PS) standards. In this study, we demonstrate the gradient compatibility of the microring resonator platform for polymer detection by quantifying the CCD of polymer blend components. Control experiments were run with UV and ELSD detection, highlighting the uniqueness of the platform as a linear mass concentration detector with a universal detector response. [ABSTRACT FROM AUTHOR]

This work is devoted to the development of two novel types of advanced composite scintillators based on single crystalline films (SCFs) of Lu3Al5O12 garnet (LuAG), doped with Ce3+ and Pr3+ ions, and substrates from single crystals (SCs) of Sc3+ doped LuAG using the liquid phase epitaxy (LPE) method. We show the possibility for simultaneous registration of α-particles and γ-quanta using separation of the decay kinetics of the SCF and crystal parts of such composite scintillators. Namely, large differences in the respective scintillation decay kinetics and decay time values tα and tγ are observed for LuAG:Ce SCF/LuAG:Sc SC and LuAG:Pr SCF/LuAG:Sc SC composite scintillators under excitation by α-particles from an 241Am (5.5 MeV) source and γ-quanta from a 137Cs (662 keV) source. Thus, both developed types of composite scintillators can be applied for simultaneous registration of α-particles and γ-quanta in mixed radiation fluxes. The rate of discrimination of the scintillation signals, coming from the SCF and SC parts of the LuAG:Ce SCF/LuAG:Sc SC composite scintillator, expressed by the tγ/tα ratio, is equal to 1.34–1.96 in the 0–1100 ns time interval. For the LuAG:Pr SCF/LuAG:Sc SC composite scintillators, more significant differences in the scintillation decay kinetics are achieved. In this case, the tγ/tα ratio for these composite scintillators reaches the values 9.6–15.6 in the wide 0–2500 ns time interval. This is the best result among all the types of composite scintillators we developed based on epitaxial structures of garnet compounds. [ABSTRACT FROM AUTHOR]

Aiming to explore scintillator candidates for high-energy radiography, the environmentally friendly compound Mg4Ta2O9 was selected. Bulk crystals of good optical quality are needed to evaluate its scintillation performance against other commercial scintillators currently used such as CdWO4 and CsI:Tl. In this work, bulk single crystal rods of 3.5 mm in diameter with length up to 50 mm were obtained through optimization of the growth process. Particularly, the thermal gradients that impact the cooling of the crystal in the floating-zone furnace were modified. The scintillation properties of the produced Mg4Ta2O9 crystals, are reported. The scintillation decay and afterglow not reported previously have been measured. The afterglow results are compared to those of CdWO4, CsI:Tl and Y3Al5O12:Ce. We confirmed a luminosity similar to that of CdWO4. [ABSTRACT FROM AUTHOR]

Novel natLiCl–CeCl3 eutectic scintillators for thermal neutron detection were synthesized by using the vertical Bridgman method. The eutectic molar ratio of LiCl and CeCl3 is 0.75/0.25. The effects of solidification speed on the microstructure, optical properties, and scintillation properties under γ and neutron irradiation were studied. The grown natLiCl–CeCl3 eutectics have a lamellar structure. Excited by X-rays, the scintillation emission of the natLiCl–CeCl3 eutectics peaks at 365 nm, which is related to the Ce3+ 5d–4f emission, and a broad and weak emission appears at 526 nm. The scintillation decay time of the natLiCl–CeCl3 eutectics under γ irradiation is about 20 ns. The energy spectra under Pu/Be source irradiation indicate that the synthesized natLiCl–CeCl3 is capable of detecting thermal neutrons. [ABSTRACT FROM AUTHOR]

A single crystal scintillation material (Gd0.5–Y0.5)3Al2Ga3O12 (GYAGG) doped with Ce and codoped with Mg at a small concentration was grown by the Czochralski technique and studied for its scintillation properties for the first time. The Czochralski technique enabled this multi-ionic garnet to be produced from a melt in a single crystal form and allowed the problems of codoping peculiar to this material in a ceramic form to be solved. Due to codoping, the scintillation kinetics of a single crystal is shorter than that of GYAGG ceramics produced before. The scintillation properties of GYAGG were found to be superior to those of the solely Ce-doped or Mg-codoped Gd3Al2Ga3O12 crystal. The light yield of GYAGG:Ce,Mg was found to be 52 000 ph MeV−1, the coefficient of the light yield temperature dependence in the temperature range 20–100 °C was equal to 0.37%/°C, and the scintillation decay time constant was 50 ns. [ABSTRACT FROM AUTHOR]

For the first time, we report intense X-ray scintillation enabled by a series of isotypic lanthanide (Eu and Tb) based metal–organic frameworks, initially showing a very efficient X-ray to visible light luminescence conversion. By systematic adjusting of the molar ratio of Eu3+ and Tb3+ in the same MOF structure as a traditional strategy for color-tuning in lanthanide-based photoluminescent materials, linear multicolor visualization of X-ray radiation from red to green can be facilely achieved, providing a new class of scintillating materials with continuous color tunability that can be customized for desired purposes. Moreover, these lanthanide–organic framework based scintillators exhibit excellent radiation resistance and humidity stability, in comparison with the state of the art and commercially-available X-ray scintillator, CsI:Tl. [ABSTRACT FROM AUTHOR]

Single crystals of a new promising material Tl2HfCl6 were successfully grown by using a modified vertical Bridgman furnace. Various growth conditions were systematically optimized to achieve improved scintillation characteristics. For the first time, the crystalline phase and structure were analyzed using the Rietveld refinement method. The emission and scintillation properties were investigated in detail. The emission peak under X-ray excitation was centered at 398 nm, which was compatible with the quantum efficiency of the conventional photosensors. The scintillation decay time under γ-ray excitation exhibited a major component of 1 μs with the light yield of 32 000 photon per MeV. The improved energy resolution of the grown crystal was measured to be 4.0% at 662 keV. The significant improvement in decay time, light yield and energy resolution over previously reported results was mainly achieved by adopting a systematic approach of material purification. The applicability of this material in various fields was also investigated for the first time by recording the combined radiation of α-particles and γ-rays. These different types of radiations could be sufficiently separated by employing the charge comparison method with a promising figure-of-merit of 2.6. A simulation using Geant4 was also performed for comparing the detection efficiency of Tl2HfCl6 with those of the conventional halide crystal scintillators. Due to its good scintillation performance and pulse shape discrimination capability, this scintillator may be reasonably considered for various applications in the field of radiation detection. [ABSTRACT FROM AUTHOR]

This work reports the results of the optical and electron paramagnetic resonance (EPR) investigation of the Ce3+ incorporation in single crystalline film (SCF) scintillators of Ce-doped LuAlO3 perovskite, grown by the liquid phase epitaxy method onto YAlO3 substrates using a PbO–B2O3 flux. The absorption, luminescence and EPR spectra showed the presence of the main Ce3+ center type (CeLu) corresponding to the location of Ce3+ ions in the twelve-fold coordinated cuboctahedral positions of the LuAlO3 host. Also the dimer CeLu–CeLu centers were found in the EPR spectra of the LuAP:Ce SCFs. No EPR spectrum of the Ce3+ ions located in the octahedral positions of Al3+ cations has been detected indicating their negligibly small concentration (below 5 × 10−3 at%) in the SCFs. Pb3+ and Pt3+ impurity ions incorporated into the SCFs grown from the PbO–B2O3 flux and Pt crucible were also identified by resolving, in particular, the hyperfine structure from the 195Pt isotope in the EPR spectra. [ABSTRACT FROM AUTHOR]

The material presented herein focuses on the exploration of the production of gadolinium aluminum gallium garnet and lutetium oxyorthosilicate doped with cerium (GAGG:Ce and LSO:Ce, respectively) through mechanochemical means. Multiple parameters are explored including mass of starting material, ball size, rotational speed of the mill, number of balls employed, and material used for the milling container. Theoretical calculations were conducted using a pre-established equation and showed that, when all other parameters were held constant, in scenarios where (1) a smaller mass of sample, (2) faster revolutions per minute, (3) greater numbers of balls, or (4) a greater density of the material used for the vials and balls were employed, there should be higher energies imparted to the system. Actual results executed appeared to exhibit somewhat congruent results, but showed limitations due to experimental (non-idealized) conditions. [ABSTRACT FROM AUTHOR]

Using a combination of experimental methods, the substitution tendencies of Li+ and involved charge compensation mechanisms are determined and compared in two important similar scintillators, LuAG:Ce and YAG:Ce. The studies were performed on polycrystalline samples prepared by solid phase reactions as well as in single crystals grown by the vertical Bridgman method. The results show that Li+ in LuAG:Ce, Li is localized mainly at Lu3+ sites with charge compensation brought about by Ce3+→ Ce4+ conversion and creation of anion vacancies. Surprisingly, unlike LuAG:Ce, Li, no evidence for Li+ substitution at Y3+ sites and conversion of Ce3+ to Ce4+ has been obtained in YAG:Ce, Li. It suggests that Li+ goes mainly to interstitial positions and does not interact with Ce3+. From an application point of view, Li+ co-doping of YAG:Ce is not efficient to improve the scintillationdecay parameters, however, it is efficient to reduce the amount of anion vacancies in both YAG and YAG:Ce. [ABSTRACT FROM AUTHOR]

UV emitting scintillating screens based on single crystalline films (SCFs) of Lu3Al5−xGaxO12:Pr garnet have been developed by the liquid phase epitaxy (LPE) growth method onto Y3Al5O12 (YAG) substrates using a lead-free BaO based flux. The absorbance, luminescence and scintillation properties of these SCFs have been investigated depending on the Ga content in the x = 0–1.9 range. We have found that the absorption and luminescence spectra of Pr3+ ions as well as the scintillation light yield (LY) and decay kinetics of Lu3Al5−xGaxO12 SCFs are non-linearly affected by the gallium concentration x in the mentioned solid solution due to preference for the distribution of Ga3+ and Al3+ ions between the tetrahedral and octahedral positions of the garnet host, respectively. The best scintillation properties of Lu3Al5−xGaxO12:Pr SCFs are achieved at the Ga content in the x = 1.0–1.2 range. The LY of the Lu3Ga1.2Al3.8O12:Pr SCF is comparable with the LY of the best reference LuAG:Pr single crystal counterpart and significantly (up to 3 times) overcomes the LY of LuAG:Pr and Lu3Al4–3.5Ga1.0–1.5O12 SCFs, grown onto the YAG substrates from the conventional PbO–B2O3 flux. [ABSTRACT FROM AUTHOR]

YAG:Ce scintillating material was obtained using 3D printing for the first time. A green body was printed using a stereophotolithography approach from co-precipitated powders and then sintered at 1600 °C in air to afford translucent ceramics. The scintillation light yield using 5.5 MeV α-particle excitation was more than 60% higher than that of the reference YAG:Ce single crystal. [ABSTRACT FROM AUTHOR]

Composition-property correlations have been systematically studied in the full concentration range of Y3Al5−xGaxO12:Ce (YAGG:Ce) scintillator crystals. The most promising compositions for new high energy physics experiments at colliders have been determined with the light output ＞200% relative to BGO and fast luminescence decay. Codoping with Ca2+ provides the decrease of phosphorescence intensity to 0.2% after 0.6 μs and shortening of the luminescence decay constant to 21 ns. Factors affecting the scintillation decay time in YAGG:Ce have been discussed. The crystals show weak transmission loss under γ-irradiation. The feasibility to produce YAGG:Ce fibers using the μ-PD method has been shown. [ABSTRACT FROM AUTHOR]

A novel green afterglow phosphor NaBaScSi2O7:Eu2+ was prepared by a solid state reaction under a reductive atmosphere. The NaBaScSi2O7:Eu2+ phosphor shows two emission bands centered at about 424 (weak) and 502 nm (strong) due to the substitution of Eu2+ in both Ba+ and Na2+ sites, and energy transfer from EuBa (424 nm) to EuNa (502 nm) was found. Both EuBa and EuNa contribute to the afterglow process while EuNa dominates. Na0.99BaScSi2O7:0.01Eu2+ exhibits green long lasting phosphorescence, whose duration is more than 1 h. The thermoluminescence properties of NaBaScSi2O7:Eu2+ and the relationship between thermoluminescence and thermal quenching properties were discussed in detail. This work provides a new and efficient candidate for long lasting phosphorescence materials. [ABSTRACT FROM AUTHOR]

A novel green afterglow phosphor NaBaScSi2O7:Eu2+ was prepared by a solid state reaction under a reductive atmosphere. The NaBaScSi2O7:Eu2+ phosphor shows two emission bands centered at about 424 (weak) and 502 nm (strong) due to the substitution of Eu2+ in both Ba+ and Na2+ sites, and energy transfer from EuBa (424 nm) to EuNa (502 nm) was found. Both EuBa and EuNa contribute to the afterglow process while EuNa dominates. Na0.99BaScSi2O7:0.01Eu2+ exhibits green long lasting phosphorescence, whose duration is more than 1 h. The thermoluminescence properties of NaBaScSi2O7:Eu2+ and the relationship between thermoluminescence and thermal quenching properties were discussed in detail. This work provides a new and efficient candidate for long lasting phosphorescence materials. [ABSTRACT FROM AUTHOR]

Multifunctional LaF3:Tb scintillating nanoparticles (ScNPs) coated with homogenous layers of silica and subsequently tethered with RB covalently were elaborated. The nanoconjugates with a high colloidal stability and biocompatibility could generate a reasonable amount of 1O2 through efficient energy transfer upon external illumination, which enables them to be potentially applied in diagnosis and photodynamic therapy for deep seated tumour. [ABSTRACT FROM AUTHOR]

A strategy for Cd1−xZnxWO4 (x ＜ 0.5) solid solution growth was successfully achieved by the Czochralski method. Polycrystalline samples and crystals of the Cd1−xZnxWO4 system were studied using X-ray diffraction. Furthermore, the scintillation properties of Cd1−xZnxWO4 (x ＜ 0.5) crystals were investigated. It was found that the diffraction peaks of the polycrystalline Cd1−xZnxWO4 (x = 0–1.0) system shift toward higher 2ϑ angles with increasing degree of Zn substitution. A linear relation between the zinc composition x and the lattice parameters of Cd1−xZnxWO4 crystals existed. With increasing zinc content x, the lattice parameters a, b, and c decrease, and the volume of the unit cell decreases. The shift of the lattice parameter presents a trend from CdWO4 to ZnWO4. Energy dispersive X-ray (EDAX) analysis was carried out in order to confirm the composition of Cd1−xZnxWO4 single crystals (x ＜ 0.5). Optical measurements revealed that the solid solution crystals had a high optical transmittance of about 65% in the range of 350–600 nm, and the absorption edges of Cd1−xZnxWO4 crystals exhibit increasing peaks from 317.4 nm to 321.5 nm. The emission peaks showed a red shift from 465.4 nm to 501.2 nm with the increasing content of zinc. Furthermore, it was observed that the light output (L.O.) decreases and the energy resolution (E.R.) increases with the increase in zinc content. [ABSTRACT FROM AUTHOR]

The detection of nuclear radiation necessitates the availability of new generations of tunable blue emitting fluorophores with high emission quantum yields. Here we show that pyridyl-1,2,4-triazole based diphenyl boron complexes can provide highly tuneable emission through facile modification of the C5 position of the 1,2,4-triazolato ring. The series of complexes prepared show a wide range of emission from near-UV to green, enabling fine control over the spectral overlap with detectors used in scintillator technology. [ABSTRACT FROM AUTHOR]

A crack-free GdTaO4 single crystal as a promising high-density scintillator is grown successfully by the Czochralski method. High crystalline quality of the as-grown crystal has been demonstrated by its X-ray rocking curve. Its density is 8.94 g cm-3, which is the highest among current inorganic single-crystal scintillators. The absolute light yield of GTO is about three times as that of PbWO4 and the scintillation decay consists of a fast component of 72.6 ns and a slow component of 1236.2 ns. Additionally, the photoluminescence measurements of GTO indicate a complicated mechanism. Its fundamental physical properties including hardness, density, and thermal properties are determined for the first time, which are very important for crystal growth and its applications. [ABSTRACT FROM AUTHOR]

A study regarding the possibility to use compound refractive lenses (CRLs) for X-ray absorption spectroscopy (XAS) was conducted. For XAS measurements the energy of the monochromatic incident beam has to be tuned over an energy range which is broader than the energy bandwidth of a CRL. To prove that μ-XAS with compound refractive lenses is possible, it had to be investigated how changes in the energy influence the beam parameters. This was done by tuning the energy around the nominal energy of the lens and recording images with a high resolution X-ray imaging setup. To investigate the changes in the spot size the scintillator was placed at the nominal focal distance and scans along the beam axis were performed. The effect on the photon flux of the incident beam due to absorption in the lens was investigated by performing XANES measurement on different reference materials with and without CRL. The results of these measurements using a CRL designed for 9 keV are shown and discussed. [ABSTRACT FROM AUTHOR]

Fluorescent CdSe–CdS–Cd0.5Zn0.5S–ZnS core–shell colloidal quantum dots (cQDs) dispersed in aqueous and organic solvents have been prepared and used as scintillators for detecting ionizing radiation. Results demonstrate a linear relationship between emitted luminescence and dose–activity. These results suggest that cQDs alone could be used as liquid scintillators for specific environmental and medical applications. [ABSTRACT FROM AUTHOR]