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Gadolinium pyrosilicate (GPS, Gd2Si2O7) single crystals with different doping concentrations of Tb (0.1–2.0 mol%) are successfully fabricated using the floating-zone technique. In this work, the dependence of Tb-doping concentration on the photoluminescence (PL) and scintillation properties of Tb-doped GPS (Tb:GPS) has been investigated. The PL emission contour graph shows multiple emissions, with the strongest emissions at 378 nm for 0.1% and 0.5% Tb-doping and 544 nm for 1.0% and 2.0% Tb-doping, corresponding to Tb3+ 4f-4f transitions. The PL lifetimes of the specimens range from 4.89 to 5.22 ms. The scintillation spectra exhibit comparable wavelength and intensity trends to the PL emission. The scintillation lifetimes of the specimens range from 2.41 to 3.88 ms. The Tb:GPS specimens demonstrate a relatively excessive afterglow level, with Af20 values ranging from 1640 to 7250 ppm and Af40 values ranging from 136 to 362 ppm. Using recently developed pulse height measurement for millisecond decay scintillators, under excitation at 662 keV γ-rays, the 1.0% Tb:GPS specimen exhibits the highest scintillation light yield among all other specimens at 95,600 ph/MeV, making Tb:GPS one of the highest light yield oxide scintillators. [ABSTRACT FROM AUTHOR]

The large size (4 cm × 4 cm × 1 cm) Ce3+-doped high gadolinium oxyfluoride glass with density of 5.83 g/cm³ was prepared by the melt quench method at 1220 °C. The glass is colorless and transparent over the visible range. The prolonged decay time under 275 nm UV light demonstrates the energy transfer from Gd3+ ions to Ce3+ ions. The X-ray excited luminescence spectra (XEL) show the emission peak corresponds to the 5d→4f transitions of Ce3+ ion. The integral emission intensity of glass was compared with that of bismuth germanate oxide (BGO) crystals. The scintillation property of glass was studied under the γ -ray from 137Cs source and a clear energy peak was observed with light yield (LY) over 1100 ph/MeV. The scintillation decay time comprises fast and slow components. All results presented in this work indicate the appropriate potential to be high-energy rays detecting material for CEPC. [ABSTRACT FROM AUTHOR]

The phosphor-converted white light-emitting diodes (pc- w LEDs) are current research hotspot. To meet simultaneously the requirements of high chemical/thermal stability and color-rendering index (CRI), low correlated color temperature (CCT) for actual application is still not be perfectly achieved. Herein, we studied for the first time the incorporation of Ce3+ (blue-emitting) and Mn2+ (orange/red emission) into the dibarium magnesium phosphate ceramic (Ba 2 Mg(PO 4) 2 , BMP) for packaging of pc- w LEDs via remote 'capping' approach, which exhibits highly efficient color-tunable photoluminescence (PL) with splendid chemical/thermal stability, single-phase/full-color-PL, efficient energy transfer (ET). To reduce the impact of heterovalent substitution (Ba2+ ← Ce3+), the monovalent (Li+, Na+, K+) ion, respectively tridoped in BMP: Ce/Mn and played both roles as flux and charge compensator, were also studied/compared on the basis of PL efficiency, where Na+ is the most effective because of the lowest electronegativity mismatch between the Ba2+ and Na+. An alkaline-earth-metal-ion blending strategy via partial replacement of Ba2+ with Sr2+ was implemented to further regulate PL and obtain better parameters of CCT/CRI due to the variations of crystal field splitting. The site occupations of Ce/Na/Sr in Ba sites (CN = 8 and 7) and Mn in Mg site (CN = 6) were based on the comparisons of ion radius and confirmed by XRD/Rietveld analyses, where Ce/Na/Sr ions gave priority to occupy the Ba site with CN = 8 due to their much closer ion radius. Altogether, the stably composition-optimized BMP: Ce/Mn/Na/Sr has great potential application as a single-component color-tunable phosphor in n -UV pumped pc- w LEDs. The pc- w LED fabricated via remote 'capping' approach by combination of a n -UV chip with BMP: Ce/Mn/Na/Sr phosphor through Ce to Mn ET with the help of charge compensator of Na and the alkaline-earth-metal-ions blending by Ba/Sr replacement. [Display omitted] • Ce/Sr/Na occupied at Ba sites while Mn sited in Mg sites. • ET occurs efficiently from Ce to Mn. • Na + acts as charge balancer to improve PL efficiency. • Replacing partial Ba by Sr could regulate PL and improve ET efficiency. • pc- w LED via ' n -UV LED + white-emitting BMP: Ce/Mn/Na/Sr' is achieved. [ABSTRACT FROM AUTHOR]

Inorganic scintillation crystals have been widely used in applications of high-energy physics, nuclear medical imaging, industrial nondestructive inspection, etc. In this work, a single crystal Ba3Y(PO4)3 (BYP) with 1.0 at% Ce3+-doping concentration was first grown by the Czochralski method, and the electronic structure was calculated using first principles based on density functional theory. In addition, a series of Ce3+-doped BYP phosphors were synthesized, and the fluorescence emission under UV excitation was measured through low-temperature spectroscopy, containing double-peaked emission from 5d–4f transition and self-trapped exciton recombination. A comparison of the UV and X-ray-excited fluorescence spectra reveals the existence of oxygen vacancies as well as F+ centers in the crystal. The air annealing of the crystal effectively reduces the thermoluminescence defects but reduces the emission intensity under UV or X-ray excitation. The BYP:Ce crystal shows a fast decay lifetime of 15.5 ns, and the fast component is as short as 8 ns. The results show that the Ce3+-doped BYP crystal has potential as a kind of scintillator with fast decay properties. [ABSTRACT FROM AUTHOR]

Quasi-zero-dimensional quantum dots (QDs) have garnered significant attention owing to their distinct structural attributes, quantum confinement behaviors, optoelectronic characteristics, etc. Regrettably, their susceptibility to stability poses a challenge. In this context, leveraging rational component regulation and crystallization process optimization strategies, we presented the successful preparation of CdS QDs silicate glass through the amalgamation of melt-quenching and controlled crystallization. The optical and morphological analysis substantiated the accomplishment of in-situ precipitation of CdS QDs within the glass matrix, with grain sizes <20 nm. Integrating CdS QDs into an inorganic glass matrix remarkably augmented its fluorescence thermal stability, enabling the preservation of 85.1 % of the room-temperature luminescent intensity even at an elevated temperature of 150 °C. Moreover, the encapsulated W-LED device by near-UV LED chip, CdS QDs glass, and BaMgAl 10 O 17 :Eu2+ phosphor exhibited a warm white-light emission characterized by suitable chromaticity coordinates (0.3741, 0.3452) and a notably high color rendering index (CRI = 93). Ultimately, the radioluminescence behavior of CdS QDs glass was unveiled by utilizing it as the scintillator wafer in an X-ray imaging system, which clearly demonstrated the structure of spring encapsulated within an opaque capsule. In a nutshell, these demonstrations unequivocally emphasize the substantial potential merits of CdS QDs glass, particularly in the domains of long-term W-LED lighting and X-ray imaging applications. [ABSTRACT FROM AUTHOR]

Commercial white light-emitting diodes (WLEDs) usually face problems such as lack of red emission, color difference caused by different degradation rates of multiphase phosphors and the poor thermal stability of the organic encapsulants. The development of new single-phase phosphors and glass can solve these problems well. Sr 3 B 14 O 24 :RE3+ (RE = Ce, Tb, Sm, Eu) phosphors and glass were synthesized by solid-phase method. The obtained Sr 3 B 14 O 24 :RE3+ (RE = Ce, Tb, Sm, Eu) samples showed multicolor emission including blue, green, orange and red, respectively. The optimal excitation wavelength of these samples was located in the blue or ultraviolet (UV) light regions, which were well matched with the blue-violet light chips to manufacture WLEDs. More interestingly, UV absorption was found in Sr 3 B 14 O 24 :Ce3+/4+ glass samples. The doping of dual-valence cerium ions could enhance the shielding performance in the light of inferences drawn from the UV-Vis absorption and transmission spectra of glass samples. By co-doping different concentrations of Cs+ ions in Sr 3 B 14 O 24 :Ce3+/4+ glass samples, the function of near infrared (NIR) shielding was also realized. As a new optical multifunctional material, rare earth doped Sr 3 B 14 O 24 have great potential for application in WLEDs, UV and NIR shielding. [ABSTRACT FROM AUTHOR]

The photoluminescence and scintillation properties of KI:Eu synthesized by the vertical Bridgman-Stockbarger method were investigated. All the samples showed a broad peak at 430-450 nm under UV and X-ray irradiations, and the origin of emission was ascribed to the 4f65d1-4f7 transition of Eu2+. Furthermore, a tail emission at 500 nm under X-ray irradiation was observed, the origin of which could be ascribed to color centers associated with oxygen impurities. According to the pulse height spectra, the highest light yield (LY) under 241Am ?-ray (60 keV) irradiation was 3400 photons/MeV among the prepared samples. In terms of LY and afterglow, the optimal concentration of Eu was found to be 0.3%. [ABSTRACT FROM AUTHOR]

Eu:CaHfO3 single crystals with various Eu concentrations were synthesized by the floating zone method, and their photoluminescence (PL) and scintillation properties were investigated. All the samples showed PL peaks at 590, 620, and 650 nm, which were due to the 4f-4f transitions of Eu3+. The PL quantum yield of 1.0% Eu:CaHfO3 was the highest at 42.2% among the samples. The X-ray-induced scintillation spectra showed several emission peaks in the range of 400-690 nm, and the emissions were attributed to the 4f-4f transitions of Eu3+. Among the samples, 0.05% Eu:CaHfO3 showed the highest intensity. In the afterglow curves, the levels were within the range of 1,000-10,000 ppm and those of previous studies. [ABSTRACT FROM AUTHOR]

Ce-doped 20CsCl-20SrCl2-60ZnCl2 glasses were investigated for their optical and scintillation properties. Under X-ray irradiation, a broad emission peak at approximately 350 nm with a shoulder peak at 375 nm was observed, and its origin was attributed to Ce3+. In the pulse height spectrum under 241Am a-ray, the glass doped with 0.05% Ce exhibited the highest light yield (LY) of 25 ph/MeV (138 ph/5.5MeV-a) among zinc-halide-based glasses. The afterglow levels of the samples were superior to that of commercial CsI:Tl. [ABSTRACT FROM AUTHOR]

Tb-doped SrLu2O4 single crystals were grown by the floating zone method, and their optical and scintillation properties were evaluated. Regarding the scintillation properties, all the prepared crystals showed the sharp emission peaks assigned to Tb3+ 4f-4f transitions in the range of 350-650 nm. The obtained decay times of 1.0-1.6 ms were typical values for the Tb3+ 4f-4f transitions. From the results of the pulse area spectra, the 1.0% Tb-doped crystal showed the highest light yield of 19600 photons/MeV among the prepared crystals. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) and scintillation properties of Ce-doped BaHfO3 crystals were investigated. The Ce-doped BaHfO3 crystal is transparent and colorless after annealing treatment under a reduction condition. The broad luminescence band at ~370 nm was observed under ~280 nm excitation with the decay time of ~17 ns. The X-ray-induced scintillation spectra also showed the broad luminescence band at ~380 nm with a fast decay. The origin of the broad luminescence band at ~380 nm is attributed to the 5d-4f transition of Ce3+. The pulse height distribution under 137Cs gamma ray irradiation using Ce-doped BaHfO3 exhibited a distinguishable photoabsorption peak. The light yield of Ce-doped BaHfO3 is ~1600 photons/MeV. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL), scintillation, and thermally stimulated luminescence (TSL) properties of Eu-doped (0.01, 0.1, and 1%) Al2O3 single crystals grown by the floating zone method were investigated systematically. The PL of the samples showed several sharp emission peaks across 550-750 nm originating from the 4f-4f transitions of Eu3+ and the 3d-3d transitions of Cr3+ impurity ions. The scintillation spectrum of the samples showed a broad emission peak at 320 nm due to the F+ center and an emission peak at 700 nm due to the 3d-3d transitions of Cr3+ impurity ions. All the samples showed TSL glow peaks at around 200, 320, and 375 °C. The TSL intensity of the 1% Eu-doped sample was the highest among the present three samples, and the TSL response was proportional to the irradiated X-ray dose in the range from 10 to 1000 mGy. The Eu-doped Al2O3 single crystal could be a novel candidate for personal dose monitoring applications. [ABSTRACT FROM AUTHOR]

The relationship between the lifetimes and emission wavelengths of scintillation and photoluminescence, when the initial excited state was the same, was studied. When the rate equation is dominant, lifetime should be the same at different emission wavelengths. However, we have observed the dependence of lifetime on emission wavelength in common scintillators. [ABSTRACT FROM AUTHOR]

The paper presents the results of a comprehensive study of the structural-phase composition, morphology, optical, luminescent, and scintillation characteristics of thick ZnO films fabricated by magnetron sputtering. By using a hot ceramic target, extremely rapid growth (~50 µm/h) of ZnO microfilms more than 100 µm thick was performed, which is an advantage for the industrial production of scintillation detectors. The effects of post-growth treatment of the fabricated films in low-temperature plasma were studied and a significant improvement in their crystalline and optical quality was shown. As a result, the films exhibit intense near-band-edge luminescence in the near-UV region with a decay time of <1 ns. Plasma treatment also allowed to significantly weaken the visible defect luminescence excited in the near-surface regions of the films. A study of the luminescence mechanisms in the synthesized films revealed that their near-band-edge emission at room temperature is formed by phonon replicas of free exciton recombination emission. Particularly, the first phonon replica plays the main role in the case of optical excitation, while upon X-ray excitation, the second phonon replica dominates. It was also shown that the green band peaking at ~510 nm (2.43 eV) is due to surface emission centers, while longer wavelength (>550 nm) green-yellow emission originates mainly from bulk parts of the films. [ABSTRACT FROM AUTHOR]

ZnO nanoarrays were grown via a low-temperature hydrothermal method. Solutions, each with different additive combinations, were prepared and evaluated. The effects of the additives involved in the growth procedure, i.e., ammonium hydroxide and sodium citrate, were studied in terms of the morphological, optical and scintillation properties of the ZnO nanostructures. Measurement of the nanorod (NR) length, corresponding photoluminescence (PL) and scintillation spectra and their dependence on the additives present in the solution are discussed. ZnO NRs grown on a silica substrate, whose UV transmission was found to be better than glass, showed high-quality structural and optical properties. It was found that the addition of sodium citrate significantly reduced defects and correspondingly increased the intrinsic near-band-edge (NBE) UV emission intensity at ~380 nm. To obtain high-quality nanostructures, samples were annealed in a 10% H2 + 90% N2 atmosphere. The anneal in the forming gas atmosphere enhanced the emission of the UV peak by reducing defects in the nanostructure. NRs are highly tapered towards the end of the structure. The tapering process was monitored using time growth studies, and its effect on PL and reflectance spectra are discussed. A good alpha particle response was obtained for the grown ZnO NRs, confirming its potential to be used as an alpha particle scintillator. After optimizing the reaction parameters, it was concluded that when ammonium hydroxide and sodium citrate were used, vertically well-aligned and long ZnO nanoarrays with highly improved optical and scintillation properties were obtained. [ABSTRACT FROM AUTHOR]

Alkali metal halides have long been used as scintillators for applications as sensors and detectors. Usually, a small amount of impurities are added to these inorganic materials to improve their luminescence efficiencies. We investigate the structures and luminescent properties of un-doped sodium iodide (NaI) and cesium-doped NaI (NaI:Cs) films deposited by thermal vacuum evaporation. Instead of using the toxic element thallium (Tl), we introduced cesium dopant into NaI. This is the first study for the NaI:Cs film excited by UV LED's ultraviolet C (273 nm, 4.54 eV). The luminescence spectra show two main peaks at 3.05 and 4.32/3.955 eV (for fused silica/B270 substrate), originating from the intrinsic defects and/or activator excited states and the intrinsic self-trapped excitons (STEs), respectively. In general, both Cs-doping and post-annealing processes enhance the luminescence performance of NaI films. [ABSTRACT FROM AUTHOR]

Through a solid state process, YBO3:Ce3+,Tb3+ was created via rare earth oxides along with boric acid. The phosphor absorbs close-ultraviolet illumination through the transitions 4f-5d of Ce3+, then emits a wide spectrum of light through the transitions 5d-4f of Ce3+ and a sharp spectrum of light through the transitions 4f-4f of Tb3+. Nonradioactive power transmission between Ce3+ and Tb3+ has been seen in samples with varying amounts of Ce3+ and Tb3+ using spectroscopic analysis. The quantities of Ce3+ as well as Tb3+ decides the hue for the YBO3:Ce3+,Tb3+ emission, ranging between blue and green. The Y0.82Ce0.03Tb0.15BO3 phosphor, which emits green light when optimized, has an exterior quantum effectiveness of 76.7% and an emission color of (0.309, 0.547). This phosphor's luminescence strength maintains 87% of its strength at ambient temperature, demonstrating enough heat stability for white illumination emitting diode implementations. [ABSTRACT FROM AUTHOR]

CsI(Tl) scintillation screens have been widely applied in X-ray nondestructive testing (NDT) because of their low cost, high scintillation efficiency, and fluorescence guide columnar microstructures. The effect of humidity exposure on the microstructure and photoluminescence properties of polycrystalline CsI(Tl) screens was investigated in this work. The results indicate that the grain diameter of the columnar microstructure increased with increased exposure time in a humid environment. The degree of anisotropy of polycrystalline screens changed from (211) and (310) to (110) orientation with exposure time. FT-IR Spectra of the exposed screens peaked at 3734 cm−1, 3710 cm−1, 3676 cm−1, 3647 cm−1, 3627 cm−1, 3598 c−1, and 3566 cm−1 due to the symmetrical and asymmetrical stretching vibrations of water molecules. In addition, the photoluminescence properties of exposed screens decreased with increased humidity exposure time due to the deliquescence caused by water molecules. After hours of humidity exposure, the photoluminescence and imaging properties of the screens decrease obviously and tend to reduce slowly. The moisture absorption and deliquescence would directly affect the service reliability and the storage lifetime of polycrystalline CsI(Tl) screens. [ABSTRACT FROM AUTHOR]

This work reports morphologically alike, high-quality monolayer MoS2 flakes with a similar strain at various growth temperatures (750–900°C) achieved by adjusting sulfur temperature. The growth dynamics of MoS2 are correlated with changes in the photoluminescence (PL) and Raman peak positions. Monolayer MoS2 crystals are synthesized at different growth temperatures from 750°C to 900°C using chemical vapor deposition (CVD). We examined the structural quality and aimed to extract the recombination mechanisms in MoS2 using low-temperature, variable, and low-laser-intensity PL measurements. Our studies of the defect-associated bound exciton emission are well correlated with the blueshift in the A1g mode of Raman spectra, blueshift in PL spectra, and x-ray photoelectron spectroscopy results for crystal grown at 900°C. Our research findings not only shed light on a thorough, non-intrusive method for modifying growth parameters to enhance optical performance, but they also suggest a way to modify the optical characteristics of MoS2 while maintaining the morphology. [ABSTRACT FROM AUTHOR]

The green-emitting plastic scintillators with high transparence, short decay time and high quantum yield were fabricated by the modified thermal polymerization procedure. The effects of different concentrations of primary and secondary fluorescent dopants on photoluminescence performance, such as fluorescence intensity, decay time and absolute quantum yield, were investigated through orthogonal experiments. The optimal formula ratio for the plastic scintillator was that the primary dopant concentration was 0.25 wt.% and the secondary dopant concentration was 0.03 wt.%. The photoluminescence decay time of the optimal sample was 3.37 ns, which was faster than that of EJ-260 (6.57 ns) and its corresponding quantum yield was 91.57%, compared to that of EJ-260 (98.59%). [ABSTRACT FROM AUTHOR]

Mg4Ta2O9 single crystals doped with 0.01, 0.1, and 1% Er were grown using the floating zone method, and their photoluminescence and scintillation properties were studied. X-ray diffraction analysis confirmed that all samples had a hexagonal structure of Mg4Ta2O9. The samples showed that the emission peak at 1550 nm was due to 4f−4f transitions of Er3+ ions, with quantum yields of 32.9, 46.6, and 18.0% for 0.01, 0.1, and 1% doping concentrations, respectively. All samples showed scintillation with a broad emission band at 350 nm due to charge transfer from Ta5+ to O2− ions and emission peak at 1550 nm due to 4f−4f transition of Er3+ ions. The dose rate response functions showed that the detection limit for all samples was 0.06 Gy/h for scintillation detector applications. [ABSTRACT FROM AUTHOR]

Gallium nitride is a wide-direct-bandgap semiconductor suitable for the creation of modern optoelectronic devices and radiation tolerant detectors. However, formation of dislocations is inevitable in MOCVD GaN materials. Dislocations serve as accumulators of point defects within space charge regions covering cores of dislocations. Space charge regions also may act as local volumes of enhanced non-radiative recombination, deteriorating the photoluminescence efficiency. Surface etching has appeared to be an efficient means to increase the photoluminescence yield from MOCVD GaN materials. This work aimed to improve the scintillation characteristics of MOCVD GaN by a wet etching method. An additional blue photo-luminescence (B-PL) band peaking at 2.7–2.9 eV and related to dislocations was discovered. This B-PL band intensity appeared to be dependent on wet etching exposure. The intensity of the B-PL was considerably enhanced when recorded at rather low temperatures. This finding resembles PL thermal quenching of B-PL centers. The mechanisms of scintillation intensity and spectrum variations were examined by coordinating the complementary photo-ionization and PL spectroscopy techniques. Analysis of dislocation etch pits was additionally performed by scanning techniques, such as confocal and atomic force microscopy. It was proved that this blue luminescence band, which peaked at 2.7–2.9 eV, is related to point defects those decorate dislocation cores. It was shown that the intensity of this blue PL band was increased due to enhancement of light extraction efficiency, dependent on the surface area of either single etch-pit or total etched crystal surface. [ABSTRACT FROM AUTHOR]

Compared with single-crystal scintillator, the glass scintillators have the benefits of low cost, big size, straightforward manufacturing method, and adjustable component. In this work, a succession of diaphanous gallogermanate glass scintillators doped with Tb3+ or Eu3+ were manufactured using melt-quenching technique. The thermal, structural, photoluminescent, and scintillating properties were studied. For photoluminescent properties, 12 mol% Tb3+-doped glass sample has high internal quantum efficiency (87.8%) and no obvious concentration quenching phenomenon can be observed. For scintillating properties, the optimal doping concentration of Tb3+ and Eu3+ are 4 mol% and 8 mol%, respectively. The integral intensity of X-ray excited luminescence of Tb3+-doped sample is 73.1% of that of Bi 4 Ge 3 O 12 scintillator, while the ratio of Eu3+-doped sample is 26.5%. The radiation damage of 4 mol% Tb3+-doped sample resulted by high power X-ray could be repaired through heat-treatment, while 8 mol% Eu3+-doped sample exhibits fine stability that the transmittance keeps constant after exposed to high power X-ray. Our research indicates Tb3+ or Eu3+ doped gallogermanate glass might be candidate for X-ray detection of slow events. [ABSTRACT FROM AUTHOR]

Ce-doped 20CsBr-20BaBr2-60ZnBr2 glasses were synthesized by the conventional melt quenching method, and their photoluminescence (PL) and scintillation properties were investigated. In the PL and scintillation spectra, all the Ce-doped glasses showed broad emissions due to the 5d-4f transitions of Ce3+ ions. Under 241Am α-rays, the light yield of 0.05% Ce-doped glass was 40 photons/5.5 MeV-α. [ABSTRACT FROM AUTHOR]

We synthesized Ce-doped Gd3Al5-yGayO12 (GAGG) nanoparticle scintillators for obtaining efficient emission in living bodies upon X-ray irradiation from outside. To obtain a high photoluminescence quantum yield (QY), the chemical composition and synthesis conditions were optimized. The highest QY of 90%, which is higher than that of a commercially available Ce-doped GAGG single-crystal scintillator (87%), was achieved with the composition for Gd:Al:Ga = 3:3:2, a Ce concentration of 0.1 mol% relative to (Gd + Ce), aging at room temperature for 1 d, and a calcination temperature of 1300 °C. The size of the particles was 200-300 nm. A dominant emission band at around 550 nm was observed in the photoluminescence and X-ray-induced radioluminescence spectra and attributed to the 5d-4f transition of Ce3+. The high photoluminescence QY and appropriate size for applications in living bodies indicated that nanoparticle scintillators based on Ce-doped GAGG were successfully developed. [ABSTRACT FROM AUTHOR]

We synthesized 20Lu2O3-30Ga2O3-50SiO2 glasses doped with various concentrations of Sn using a floating zone furnace equipped with Xe arc lamps. The samples showed a luminescence band around 450 nm in both photoluminescence (PL) and scintillation spectra. The origin of the luminescence was ascribed to the T1-S0 transition of Sn2+ on the basis of the luminescence wavelength and PL decay time constant. The highest scintillation intensity and PL quantum yield were observed from the 1% Sn-doped sample. The afterglow level tended to decrease with increasing Sn doping, and the afterglow levels of the 1 and 3% Sn-doped samples were comparable to that of the conventional Tl-doped CsI scintillator. The optimal concentration of Sn for the glass was estimated to be 1%. [ABSTRACT FROM AUTHOR]

A comparative study on the radioluminescence properties of Ce-doped SrAl2O4 single crystal and translucent ceramic was performed. The transmittance of the synthesized ceramic is 20-30% in the visible region. Both samples exhibit photo- and radioluminescence with a broad emission peaking at 380 nm. The decay curves are fitted by a single exponential decay function with decay time constants of 30-50 ns, consistent with the typical value of the emission for the 5d-4f transitions of Ce3+. From the pulse height spectra measured under 241Am γ-ray (59.5 keV) irradiation, the scintillation light yields are 17000 ph/MeV for the single crystal and 6100 ph/MeV for the synthesized ceramic. The scintillation light yield and afterglow of the present samples show a negative correlation. [ABSTRACT FROM AUTHOR]

In this study, Mg1.995-xSiO4:xCe, 0.005Tb (x = 0 and 0.01) single crystals were synthesized by the floating zone method and their photoluminescence (PL) and dosimetric properties were evaluated. In the PL process, emission peaks due to the 4f-4f transitions of Tb3+ ions were observed in the x = 0 and 0.01 samples, and the emission peak due to the 5d-4f transitions of Ce3+ ions was detected in the x = 0.01 sample. In the thermally stimulated luminescence (TSL) process, only emission peaks due to the 4f-4f transitions of Tb3+ ions were observed in both samples, and the x = 0.01 sample had higher TSL intensity than the x = 0 sample. The x = 0.01 sample showed a lower detection limit of 0.01 mGy and a spatial resolution of 50.0 pm under X-ray irradiation. [ABSTRACT FROM AUTHOR]

Ce:(MgxCa1-x)HfO3 (x = 0.5, 2.5, 5, and 10%) single crystals were successfully grown by the floating zone method, and their photoluminescence (PL) and scintillation properties were investigated. A broad luminescence band with a maximum at 430 nm was observed in both the PL and scintillation spectra. The PL quantum yield (QY) improved with the substitution of Mg, and the PL QY of Ce:(MgxCa1-x)HfO3 reached 50%. Fast decay due to the 5d-4f transition of Ce3+ was observed for both the PL and scintillation. Ce:(MgxCa1-x)HfO3 (x = 5%) showed the highest light yield of ~9500 photons/MeV among the synthesized samples, and this value is higher than that of common X- and gamma-ray detection scintillators such as Bi4Ge3O12 and Ce:Gd2SiO5 single crystals. [ABSTRACT FROM AUTHOR]

Novel near-infrared (NIR) phosphors are in demand for light-emitting diode (LED) devices to extend their suitability for new applications and, in turn, support the sustainable and healthy development of the LED industry. The Cr3+ has been used as an activator in the development of new NIR phosphors. However, one main obstacle for the Cr3+-activated phosphors is the low luminescence efficiency due to the spin-forbidden d-d transition of Cr3+. The rare-earth (RE) huntite minerals that crystallize in the form of REM3(BO3)4 (M = Al, Sc, Cr, Fe, Ga) have a large family of members, including the rare-earth scandium borates of RESc3(BO3)4. Interestingly, in our research, we found that the luminescence efficiency of Cr3+ in the CeSc3(BO3)4 host, whose quantum yield was measured at 56%, is several times higher than that in GdSc3(BO3)4, TbSc3(BO3)4, and LuSc3(BO3)4 hosts. Hereby, the energy conversion and transfer in the luminescence of CeSc3(BO3)4:Cr3+ phosphor were examined. The Stokes shift of electron energy conversion within the Cr3+ 4T2g level for the emission at 818 nm and excitation at 625 nm in CeSc3(BO3)4 host was evaluated to be 3775.1 cm−1, and the super-large splitting energy of the 2F5/2 and 2F72 sub-states of the Ce3+ 4f1 state, about 3000 cm−1, was found in CeSc3(BO3)4 host. The typical electronic thermal vibration peaks were observed in the excitation spectra of CeSc3(BO3)4:Cr3+. On this basis, the smallest phonon energy, around 347.7 cm−1, of the CeSc3(BO3)4 host was estimated. Finally, the energy transfer that is responsible for the far higher photoluminescence of Cr3+ in CeSc3(BO3)4 than in other hosts was proven through the way of Ce3+ emission and Cr3+ reabsorption. [ABSTRACT FROM AUTHOR]

Ce3+‐doped 20Gd2O3–20Al2O3–60SiO2 (GAS:xCe3+) glasses (x = 0.3, 0.7, 1.1, 1.5, 1.9 mol%) with Si3N4 as a reducing agent were prepared. The density of the glasses is around 4.2 g/cm3. With the increase in the Ce3+ concentration, both the photoluminescence (PL) and PL excitation peaks of GAS:xCe3+ glasses show a redshift because the 4f–5d energy levels of Ce3+ ions are narrowed. PL quantum yield and PL decay time of GAS:xCe3+ glasses are 28.32–50.59% and 43–64 ns, respectively. In addition, they both first increases and then decreases with the Ce3+ concentration increasing, reached the maximum when x = 1.1 mol%. The integrated X‐ray excited luminescence (XEL) intensity of the GAS:1.1Ce3+ glass is 23.86% of that of Bi4Ge3O12 (BGO) crystal, and the light yield reaches 1200 ph/MeV with an energy resolution of 22.98% at 662 keV when exposed to γ‐rays. The PL and XEL thermal activation energies of GAS:xCe3+ glasses are independent of Ce3+ ions concentration. Scintillating decay time of the glasses exhibits two components consisting of nanosecond and microsecond levels, and the scintillating decay time gradually decreases with the Ce3+ concentration increasing. The difference between PL and scintillating decay time is discussed regarding the different luminescent mechanisms. [ABSTRACT FROM AUTHOR]

The Nd-doped LaMgAl11O19 single crystals were synthesized by the floating zone method, and the photoluminescence and scintillation properties were evaluated. Under X-ray irradiation, several sharp emission peaks due to the 4f–4f transitions of Nd3+ were observed at 900, 1060, and 1340 nm in the near-infrared range, and the decay curves show the typical decay time for Nd3+. The samples show good afterglow properties comparable with practical X-ray scintillators. The 1% and 3% Nd-doped LaMgAl11O19 samples show a good linearity in the dynamic range from 6–60,000 mGy/h. [ABSTRACT FROM AUTHOR]

Undoped, 0.5, 1.0, and 2.0% Nd-doped Bi4Si3O12 (BSO) crystals were synthesized by the floating zone method. Regarding photoluminescence (PL) properties, all samples had emission peaks due to the 6p–6s transitions of Bi3+ ions. In addition, the Nd-doped samples had emission peaks due to the 4f–4f transitions of Nd3+ ions as well. The PL quantum yield of the 0.5, 1.0, and 2.0% Nd-doped samples in the near-infrared range were 67.9, 73.0, and 56.6%, respectively. Regarding X-ray-induced scintillation properties, all samples showed emission properties similar to PL. Afterglow levels at 20 ms after X-ray irradiation of the undoped, 0.5, 1.0, and 2.0% Nd-doped samples were 192.3, 205.9, 228.2, and 315.4 ppm, respectively. Dose rate response functions had good linearity from 0.006 to 60 Gy/h for the 1.0% Nd-doped BSO sample and from 0.03 to 60 Gy/h for the other samples. [ABSTRACT FROM AUTHOR]

Nd-doped CaWO4 single crystals with dopant concentrations of 0.1, 0.5, and 1% were synthesized by the floating zone method. The transmission, photoluminescence, and scintillation properties were evaluated from ultraviolet to near-infrared (NIR) ranges. An emission peak due to transitions of the host was observed at 400 nm, and several sharp peaks originating from Nd3+ 4f–4f transitions were confirmed at 900, 1060, and 1300 nm. The quantum yields of 0.1, 0.5, and 1% Nd-doped samples were 70.7, 79.5, and 61.2%, respectively, when monitored, and excited wavelengths were 750–1500 nm and 590 nm. Decay times consistent with typical Nd3+ transitions were obtained when NIR ranges were monitored. Additionally, the energy transfer between the host and Nd3+ occurred according to the decay measurement. The relationship between X-ray irradiated dose rate and intensity in the range of NIR was investigated by combining the crystals with an InGaAs-photodiode. The lowest detectable dose rate retaining the linearity of the present crystals was 0.3–0.06 Gy/h. [ABSTRACT FROM AUTHOR]

In recent years, Cs2ZnCl4 crystal has become an ideal substrate for various functional doped ions due to its large bandgap, showing potential in photodetectors and scintillators. In practical application, the intrinsic defect luminescence of bulk crystals has an important effect on the photoelectrical properties. In this work, Ø12 mm × 90 mm Cs2ZnCl4 single crystal was grown by the vertical Bridgman method. The theoretical bandgap, state density distribution, and refractive index curve of the crystal were obtained by first-principles calculation of the structure data. The luminescence properties of the crystal were characterized, including photoluminescence spectrum and radioluminescence spectrum. The temperature-dependent photoluminescence spectrum of the crystal was studied, and the luminescence process of the defects in the crystal was analyzed by the experimental results. [ABSTRACT FROM AUTHOR]

[Display omitted] • B-site co-doped perovskite nanocrystals were synthesized. • Co-doped NCs has excellent photoluminescence efficiency and lifetime. • The mechanism of enhanced luminescence of co-doped NCs was elucidated. • The stable scintillator film was prepared by PVDF-HFP encapsulation of co-doped NCs. • The film has excellent performance as scintillator under X-ray. Perovskite scintillators with low cost, easy preparation, environmental stability, and high-resolution have become candidates for X-ray imaging applications. Here, based on the calculation results of surface formation energy (E f) and vacancy defect energy (E vac), a series of co-doped perovskite nanocrystals (NCs) with photoluminescence high quantum yield (PLQY) and fast luminescence decay time had been prepared by doping several bivalent metal ions into the B-site of methylammonium lead tribromide (MAPbBr 3). In addition, the scintillator with flexibility was prepared using poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) as the carrier, showing excellent stability and scintillation performance, with a light yield of 21,200 photons/MeV, imaging resolution reached 11.7 lp/mm, and low detection limits of 462 nGy air s−1. Finally, we demonstrated the scintillator characteristic with high-quality imaging results and excellent tolerance under high dose rate X-ray (25 mGy s−1). Therefore, the combination of co-doped nanocrystals with excellent optical properties and PVDF-HFP further paves the way for the development of a scintillator. [ABSTRACT FROM AUTHOR]

1Eu2O3–3BaO–20Nb2O5–76TeO2 glass and the corresponding glass-ceramics were synthesized with the aim to investigate the effect of glass crystallization on the photoluminescence and scintillation characteristics. Glass ceramics containing mainly the Nb2Te4O13 crystalline phase were obtained by heat treatment of the glass at 540 °C for 1, 2, or 4 h. For the glass and glass ceramics, emission peaks originating from the 4f → 4f transitions of Eu3+ appeared under irradiation with 530 nm light or X-rays. Among the samples, the highest emission intensity in the photoluminescence and X-ray-induced scintillation spectra was obtained for the glass. Furthermore, typical photoluminescence and scintillation decay time constants originating from the 4f → 4f transitions of Eu3+ were obtained for the glass and glass ceramics. The afterglow level of the glass was comparable to that of the glass ceramics. [ABSTRACT FROM AUTHOR]

Scintillators, which are widely used as radiation detectors, are phosphors that release absorbed ionizing radiation energy as ultraviolet or visible light. Inorganic glass scintillators have several advantages over inorganic crystal scintillators, such as ease of fabrication and low costs. However, unlike inorganic crystals, which can emit up to tens of thousands of photons/MeV, inorganic glasses exhibit less than several hundred photons/MeV in most cases. Here, we studied an inorganic glass scintillator that exhibits a light yield of 2700 photons/MeV, which exceeds those of previous inorganic glass scintillators with high light yields of approximately 2000 photons/MeV. The density of this material is 3.28 g/cm3, which is relatively high among glass scintillators. Moreover, a fast scintillation decay with a decay time constant of 30.0 ns was obtained and is attributed to the 5d–4f transition of Ce3+. Thus, this glass is suitable for gamma- and X-ray detection, thereby expanding the practical applicability of inorganic glass scintillators. [ABSTRACT FROM AUTHOR]

A novel and effective method to improve scintillation properties of glass-ceramics, such as intensity enhancement and decay-time shortening, is reported in this work. Compared with crystal scintillators, glass scintillators always have the problems of low efficiency and long decay; how to solve them has always been a scientific puzzle in the field of scintillation glass-ceramics. The plasma enhancement effect can be predicted to solve the above problems. Ag+ ions were diffused into glasses by ion exchange, and then Ag nanoparticles and CsPbBr3 quantum dots were formed by heat treatment. The structure of the CsPbBr3 perovskite consists of a series of shared corner PbBr6 octahedra with Cs ions occupying the cuboctahedral cavities. By using Ag and the plasma resonance effect, the photoluminescence intensity of CsPbBr3 quantum dot glasses was enhanced by 3 times, its radioluminescence intensity increased by 6.25 times, and its decay time was reduced by a factor of more than one. Moreover, the mechanism of photoluminescence and radioluminescence enhanced by Ag and plasma was discussed based on the experimental results and finite-difference time-domain method. We concluded that the increase in radioluminescence intensity was related to plasma enhancements and the energy exchange between Ag nanoclusters and CsPbBr3 quantum dots. Doping Ag is a valid means to improve the scintillation luminescence of CsPbBr3 quantum dot glasses, which can be applied in the field of scintillation. [ABSTRACT FROM AUTHOR]

Copper-based lead-free perovskite derivatives have recently drawn great attention for their excellent optoelectronic properties and potential applications in light-emitting diodes (LEDs) and photodetectors. Herein, facile synthesis methods of cooling crystallization and wet ball milling (WBM) are adopted to synthesize K2CuCl3, resulting in single crystals (SCs) and powder samples, respectively. The as-fabricated K2CuCl3 samples exhibit blue–violet emission, with the highest photoluminescence quantum yield (PL QY) of 70% (under 280 nm excitation), and the photoluminescence (PL) is attributed to the self-trap excitons (STEs) emission. We also test the scintillation properties of K2CuCl3 for X-ray detection and imaging applications. A down-conversion LED is finally made by using K2CuCl3 as phosphor. As-synthesized K2CuCl3 can be used for either photoluminescence under UV light or X-ray imaging under X-ray radiation. -- Present in ms [ABSTRACT FROM AUTHOR]

lthough single crystal scintillators have excellent performance, they have some drawbacks such as high cost, complicated elaboration method and difficulty of growth on large-scale. Glass scintillators are widely investigated to replace single crystal scintillators because of their simple fabrication method and low cost. In this paper, a series of transparent borosilicate aluminate glass scintillators doped with Tb3+ were successfully prepared by traditional melt-quenching method. The structural, luminescent, and X-ray excited scintillating properties were investigated. These glass samples show high stability and high transparency, and present good luminescent and scintillating properties. Sample with Tb3+ doping concentration of 10% has the best scintillating performance. The integrated intensity of X-ray excited luminescence is 66.6% of that of commercial Bi 4 Ge 3 O 12 single crystal scintillator, and the quantum efficiency (under 378 nm excitation) is 70.3%. Our findings suggest that Tb3+-doped borosilicate aluminate glasses with high light yield might be used as potential scintillators. [ABSTRACT FROM AUTHOR]

Sm-doped SrCl2 crystals were prepared, and the scintillation properties such as emission spectra, decay profiles, and pulse height were investigated. Under X-ray irradiation, a broad band can be observed at 680 nm, which indicates that the major origin is due to 5d-4f transitions of Sm2+. The decay curve is approximated by one exponential function with a decay time of 10 μs, and the decay time constant is typical for Sm2+. From the pulse height of 137Cs γ-rays, 0.1% Sm:SrCl2 shows a light yield of 33,000 photons/MeV. [ABSTRACT FROM AUTHOR]

Five samples of lanthanum pyrosilicate (La2Si2O7) single crystals with 0.5–10.0% Praseodymium (Pr)-doping concentrations were synthesized by the floating-zone method. Photoluminescence and scintillation properties of these crystals were investigated in this study for the first time. The multiple emissions from electron transitions of Pr3+ were observed on both a photoluminescence emission map and scintillation spectra, including the desired emission band of Pr3+ 5d–4f transition at 250–310 nm. The major photoluminescence and scintillation decay times were approximately 19 and 26 ns, respectively. When compared with commercial scintillators such as Tl-doped cesium iodide (CsI), the Pr-doped La2Si2O7 samples presented a respectively low afterglow level of 32 ppm after 20 ms of X-ray irradiation. Under 662 keV γ-ray irradiation from 137Cs, the 3.0% Pr-doped La2Si2O7 sample presented a scintillation light yield of 3200 ph/MeV, which was the best value among the tested samples. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) and scintillation properties of (C6H5C2H4NH3)2Pb1-xCuxBr4 (x = 0.05, 0.1, 0.25, and 0.5) single crystals prepared by the poor-solvent diffusion method were evaluated. In the PL profiles, free- and bound-exciton luminescence peaks at 410 and 440 nm were observed, respectively. The PL quantum yields (QYs) of the x = 0.05, 0.1, 0.25, and 0.5 samples were 20.0, 19.3, 18.4, and 16.7% with 2% errors, respectively. In the scintillation profiles, a bound-exciton luminescence peak was observed at 440 nm. Under γ-ray exposure with 137Cs, a photoabsorption peak was observed in all the samples, and the scintillation light yields of the x = 0.05, 0.1, 0.25, and 0.5 samples were estimated to be ~12000, ~11000, ~10000, and ~9700 ph/MeV with 10% errors, respectively. [ABSTRACT FROM AUTHOR]

In recent years, several coordination polymers of different dimensions and metal–organic frameworks were tested and expected to be good candidates for closing the gap between organic and plastic scintillators on the one hand side and inorganic scintillators on the other hand side. In the present work, we report the synthesis and characterization of a novel one-dimensional scintillating coordination polymer based on cadmium(II), N,N'-(1,4-phenylenedicarbonyl)di-glycinate, and 2,2'-bipyridine. Crystals could be obtained from water–methanol solutions and the structure was determined by single-crystal diffraction. The coordination polymer exhibits scintillation under X-ray excitation and laser as well as UV-light induced photoluminescence with fast decay times. Photoluminescence and X-ray excited optical luminescence (XEOL) properties and decay times were performed using a two-dimensional photon counting streak camera system with a time resolution up to 20 ps. The non-covalent interactions and supramolecular assemblies as a potential multiplier of the scintillating effect were investigated with the aid of a Hirshfeld surface analysis. The quality and phase purity of the used crystals and pellets was clarified by powder diffraction and Rietveld refinement. [ABSTRACT FROM AUTHOR]

We evaluated the photoluminescence (PL), scintillation, and dosimetric properties of Ce–doped Mg2SiO4 single crystals. As the PL and optically-stimulated luminescence (OSL) properties, the Ce–doped Mg2SiO4 showed the emission from 5d to 4f transitions of Ce3+. In the scintillation and thermally-stimulated luminescence (TSL) properties, two emission peaks due to Ce3+ and defect centers were observed. The Ce–doped Mg2SiO4 showed OSL by stimulating at 600 nm and TSL by heating at 50, 160, 195, and 370 °C. In OSL, linearly proportional responses were confirmed from 10 mGy for the 0.5 and 1% Ce–doped samples to 100 mGy for the 0.1% Ce–doped sample. In TSL, the undoped and Ce–doped samples had the linearity response from 100 to 0.01 mGy, respectively. [ABSTRACT FROM AUTHOR]

Transparent and yellowish Ce-doped SrHfO 3 (Ce:SHO) single crystals were grown by the xenon lamp equipped floating zone method. The synthesized crystals were in the single phase of SHO crystal structure, and no impurity phases such as HfO 2 were evident by the X-ray diffraction analysis. The Ce:SHO shows blue luminescence peaking at 410 nm in both the PL and scintillation spectra, and the decay time constant was approximately 14 ns. The PL QY increases with the Ce concentration, which was confirmed up to 5%. The afterglow level is the lowest when the Ce concentration is 3%. The full energy peak can be demonstrated with all the Ce:SHO single crystals prepared in this study under 241Am alpha-ray irradiation, and the estimated light yield is 396 photons/MeV for the 3% Ce:SHO, which is the highest among the samples studied. • Transparent and yellowish Ce-doped SrHfO 3 (Ce:SHO) single crystals were synthesized by the xenon lamp equipped floating zone method. • Ce:SHO showed blue luminescence with the maximum peak at 410 nm in both the photoluminescence and X-ray-induced scintillation spectra. • The full energy peak was observed in all the Ce:SHO single crystals under 241Am alpha-ray irradiation. [ABSTRACT FROM AUTHOR]

Inorganic phosphors based on rare earth elements are commonly used as scintillation materials due to their high chemical and radiation resistance. In this work, we study gadolinium oxyselenide as a new phosphor material. The work describes a facile synthesis method for Gd 2 O 2 Se. Single crystal structure of this compound was determined for the first time: sp.gr. P ¯3 m 1 with a ​= ​3.8911(4) Å and c ​= ​6.8829(8) Å. Gd 2 O 2 Se is stable in the inert atmosphere and melts at 2075 ​± ​20 ​°C. This material is also stable when heated in air up to 720 ​°C. with the following oxidation and weight increase. This mass increase can be explained by the oxidation of Se2− to Se4+. Further temperature increase above 952°С leads to a sharp mass loss and the final mass of sample corresponds to full oxidation of Gd 2 O 2 Se to gadolinium oxide. The band gap of the material was estimated to be 3.6 ​eV. Photoluminescence spectrum for Gd 2 O 2 Se:Tb3+ shows the characteristic transitions in Tb3+ ion with the most intense green emission that corresponds 5D 4 → 7F J transitions. [Display omitted] • A powder of Gd 2 O 2 Se was obtained and the single crystal structure was determined: sp.gr. P ¯3 m 1, a ​= ​3.89Å, c ​= ​6.88 Å. • The melting point was found to be 2075 ​± ​20 ​°C. High air stability for this compound was demonstrated up to 720 ​°C. • The estimated value of the band gap is 3.6 ​eV. The photoluminescence of the Tb3+ doped sample was investigated. [ABSTRACT FROM AUTHOR]