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The objective of this paper is to review the use of the thermoluminescence (TL) and optically stimulated luminescence (OSL) techniques as research tools in luminescence, particularly to detect the presence of trapping centers that can degrade the efficiency of scintillators, and shape the properties of persistent phosphors, storage phosphors and dosimeters. A brief review of the main analysis techniques is provided, followed by a discussion of their limitations. Examples of applications in which the TL or OSL analyses have provided useful information on the trapping and recombination of charges created by ionizing radiation is given. [ABSTRACT FROM AUTHOR]

To reduce the issue of tri-primary color reabsorption, a new approach for single-phase phosphors as light-emitting diodes (LEDs) has been recommended. The structures, morphology, photoluminescence, thermal stability, and luminescence mechanism of a variety of Ca3Bi (PO4)3 (CBPO): Ce3+/Dy3+ phosphors were investigated. XRD characterization showed that all CBPO samples were eulytite structures. Furthermore, the energy transfer process from Ce3+ to Dy3+ in CBPO is systematically investigated in this work, and the color of light can be adjusted by changing the ratio of doped ions. Under UV light, energy is transferred from Ce3+-Dy3+ mainly through quadrupole-quadrupole interactions in the CBPO host, and doping with different Dy3+ concentrations tunes the emission color from blue to white. The thermal stability of the CBPO: 0.04Ce3+, 0.08Dy3+ samples is outstanding, and the CIE coordinates of the samples after emission have little effect with temperature, while their emission intensity at 423 K is as strong as that at room temperature, reaching 90%. The above results indicate that this CBPO material has great potential as a white light phosphor under near-UV excitation at the optimized concentration of Ce3+ and Dy3+. [ABSTRACT FROM AUTHOR]

The study deals with the use of different amounts of MgO or tetraethyl orthosilicate (C 8 H 20 O 4 Si, TEOS), from 0.04 wt %, 0.06 wt %, 0.08 wt %, 0.4 wt %, 0.6 wt % to 0.8 wt %, respectively, as additional sintering aids during the vacuum sintering of transparent Ce3+ doped Y 3 Al 5 O 12 (Ce:YAG) ceramics to investigate their effect on microstructure and luminescence properties. A comparative study was carried out by using X - ray diffraction, scanning electron microscopy/energy dispersive X - ray spectroscopy, optical and photo-luminesce spectra, as well as electroluminescent spectra. The dominant garnet phase was obtained even when adding 0.8 wt % of MgO or TEOS, while adding MgO led to finer average grain size (∼ 5 - 10 μm) and more homogenous distribution compared to TEOS (∼ 20 - 25 μm) in Ce:YAG ceramics. Adding a large amount of MgO was found to result in the segregation of MgO in Ce:YAG ceramics, while an excess of TEOS led to the segregation of Al 2 O 3. A strong absorption peak at 308 nm was observed in Ce:YAG ceramics with MgO sintering aids, which was ascribed to the existence of Ce4+ induced by a charge compensation effect of Mg2+. The optimum transmittance reached 80% @ 800 nm in Ce:YAG ceramics when adding 0.6 wt % TEOS, which also exhibited a maximum luminous efficacy of 106 lm/W. Si4+ was experimentally proved to have a better optimization effect on luminous efficacy compared to Mg2+. • MgO or TEOS (C 8 H 20 O 4 Si) was added as additional sintering aids in a wide amount range. • MgO proves to have distinct inhibit effect on the grain growth. • Better luminous efficacy were observed in ceramics with TEOS additives. [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]

Rare-earth aluminate garnet-type double oxides have practical applications as scintillators with high luminescence yields; however, several garnet compounds are metastable phases, and those scintillation properties are yet unclear. We prepared Ce3+-doped Gd 3 Al 5 O 12 (Ce3+:GAG) as a thick-film phosphor, using laser-assisted metal–organic chemical vapor deposition, and investigated its luminescence and scintillation properties. With a deposition rate of 48 μm h−1, the Ce3+:GAG thick film was epitaxially grown on a Y 3 Al 5 O 12 single crystal substrate with in-plane orientation relationship. Under UV light and α-ray irradiations, the Ce3+:GAG film exhibited a broad emission centered at 560 nm corresponding to the 5d–4f transition of Ce3+ ions. The scintillation light yield of the Ce3+:GAG film was 14250 photons per 5.5 MeV with a fast decay constant of 82.8 ns for the α-ray irradiation from the 241Am source. • Ce3+:GAG thick film phosphor was epitaxially grown using CVD method. • Ce3+: GAG exhibited photoluminescence at 560 nm due to Ce3+ 5d-4f transition. • Scintillation light yield was 14250 photons per 5.5 MeV, comparable to Ce3+:YAG. [ABSTRACT FROM AUTHOR]

Gd3+ and Ce3+ doped and co-doped NaCaYF 6 were synthesized noting the lack of luminescence studies in this material by using hydrothermal method. Synthesized NaCaYF 6 is also known by the mineral name Gagarinite. X-ray diffraction studies of prepared sample performed to confirm the identification of the phase pure fluoride compound. Energy dispersive spectra (EDS) and elemental mapping also recorded to confirm the compositions. Photoluminescence (PL) studies performed for recording PL Excitation (PLE) and PL Emission (PL) Spectra. Characteristic luminescence of Gd3+ ions and Ce3+ ions were observed in NaCaYF 6. The PLE of Ce3+ doped NaCaYF 6 phosphor shows broad excitation band centered at 294 nm with other weak shoulder peak at 272 nm. A typical double humped broad band emission obtained for the 294 nm excitation. Emission peak of 322 nm appears due to Ce3+ (5d–4f) transition with an additional shoulder peak at 315 nm. The PL spectra of the Gd3+-doped NaCaYF 6 excited at 272 nm consists of a dominant UVB emissions at 311 nm due to the transitions 6P 7/2 → 8S 7/2 of Gd3+ ions. No concentration quenching for Ce3+ was observed while luminescence of Gd3+activator got quenched at 1 mol %. The peculiarity of Gd3+ emission was the long lifetime of the order of 10 ms. Luminescence characteristics are explained using the known energy level diagrams for the lanthanide activators. The results revealed that Gd3+ and Ce3+ doped NaCaYF 6 compound could find a promising application for the UV-emitting phototherapy lamps. [Display omitted] • Novel results on observation of UV emission in NaCaYF 6 :Ln3+ (Ln3+ = Ce, Gd) materials are reported for the first time. • The samples of pristine and Ln3+ doped NaCaYF 6 have been prepared by the Hydrothermal method. • Characteristic line emission for Ce and Gd doped NaCaYF 6 are observed. • This can be useful in various UV applications. [ABSTRACT FROM AUTHOR]

We have designed a novel strategy to develop efficient X-ray-induced long afterglow luminescent materials. Eu3+ ions as electron receptors were chosen as trap creators and emitting centers and scintillator Bi 4 Ge 3 O 12 was regarded as the host to efficiently absorb X-ray. The obtained results showed that Bi 4 Ge 3 O 12 : Eu3+ can produce excellent x-ray induced red long afterglow luminescence which appeared at 589, 612, 655 and 705 nm corresponding to the 5D 0 →7F j (j = 1,2,3,4) transitions, respectively. The best afterglow performance was shown when the Eu3+ doping concentration was 0.5% at this time, and Bi 4 Ge 3 O 12 :Eu3+ also showed a strong afterglow under short-time X-ray excitation. The thermoluminescence results indicated the X-ray irradiation can produce massive secondary electrons and the abundant free electrons can easily induce Eu3+ ions to formed Eu2+* traps, which resulted in the excellent x-ray induced long afterglow luminescence of Bi 4 Ge 3 O 12 : Eu3+. Furthermore, the X-ray induced long afterglow red luminescence from Bi 4 Ge 3 O 12 :Eu3+ can persist for more than 5400 s, which still can be clearly observed by naked eyes even after 5400 s. All these results our designed strategy can realize the development of good X-ray induced long afterglow luminescent materials from scintillator to phosphor. • X-ray excited long afterglow material Bi 4 Ge 3 O 12 :Eu3+ shows red afterglow. • The transformation from scintillator to long afterglow material. • The Eu3+ to Eu2+ transition is responsible for the afterglow of Bi 4 Ge 3 O 12 :Eu3+. • A model is presented to clarify the afterglow mechanisms of Bi 4 Ge 3 O 12 :Eu3+. [ABSTRACT FROM AUTHOR]

The development and characterization of the optical properties of a neodymium(III)‐doped 42.75AlF3–33.25CaF2–19BaF2–5YF3 (Nd3+‐doped BCA‐5Y) glass in the vacuum ultraviolet (VUV) region are reported. Photoluminescence peaks at 180 and 227 nm are observed upon excitation with the 157 nm emission of a F2 laser. The dominant 180 nm emission peak is assigned to the 4f25d–4f3 (4I9/2 level) transition in Nd3+. This emission peak exhibits a fast, single exponential luminescence with a 16 ns decay time. The strong luminescence intensity and the fast decay time allude to its prospects for scintillator applications. [ABSTRACT FROM AUTHOR]

Europium doped borosilicate glasses were prepared in CO reducing atmosphere. The glasses were systematically investigated through XPS, photoluminescence (PL), fluorescence decay curves and X-ray excited luminescence (XEL). XPS results show that the glasses contain Eu2+ and Eu3+ at the same time. Under the excitation of 360 nm light, only a broad blue emission with peak around 440 nm due to the 5d→4f transition of Eu2+ is observed, while the emissions from Eu3+ do not appear in the PL spectra. The fluorescence decay curves were monitored at 440 nm, and the measured lifetimes are in the range of 0.17–0.42 μs. The PL results indicate that the PL emission from Eu2+ is significantly intense than the PL emissions from Eu3+. Upon X-ray excitation, two main emissions with peaks at 445 nm and 616 nm corresponding to Eu2+ and Eu3+ are obtained. The XEL results reveal that the XEL emissions from Eu3+ are comparably intense as the XEL emission from Eu2+. The results indicate that europium doped borosilicate glass could be a potential scintillating material in X-ray detection filed. [ABSTRACT FROM AUTHOR]

The aluminate perovskites YAlO3 (YAP) and LuAlO3 (LuAP) have been identified as potential scintillator materials due to their high light output and short decay time. However, the performance of these materials is significantly reduced by point defects. In this paper, atomistic simulations provide insight into the types of point defects that are expected under various conditions in YAP and LuAP, as well as other REAlO3 compounds (where RE denotes a rare earth ion ranging from Lu to La or Y). For example, we predict that cation antisites are the dominate intrinsic defect for smaller REAlO3 compounds, with the concentration of Schottky-type defects increasing for compounds with larger RE ions. We also predict that cation vacancies will be present in association with the oxidation of the Ce activator. From these results, we show how defects affect different aspects of the scintillation process. Our aim is to provide information that can be used to aid in the intelligent optimization of this family of scintillator compounds. [ABSTRACT FROM AUTHOR]

X-ray luminescence from CdTe nanoparticles is observed when CdTe nanoparticles are encapsulated into BaFBr:Eu2+ phosphors. In contrast, negligible x-ray luminescence is observed from the unencapsulated nanoparticles, either in solution or in solid form. The origin of the x-ray luminescence is attributed to the effective energy transfer from Eu2+ ions to CdTe nanoparticles in the nanocomposite materials. The x-ray luminescence of these nanocomposites is dose dependent and the emission wavelength is size adjustable which may allow use as a type of dosimeter for both in vitro and in vivo applications. [ABSTRACT FROM AUTHOR]

YPO4 phosphors doped with trivalent ion Pr3+ were prepared by sol-gel method and treated with different doses of gamma radiation, from 0.25 MGy to 4 MGy. Effects of radiation on morphology, structure and luminescent properties were analyzed. Also, the influence of radiation on the change in the color of the samples was examined. The color efficiency of powders was evaluated by colorimetric analysis (CIE and L * a * b system). It has been observed that powders change color under the influence of radiation, i.e. they pass from white to pinkish red. Also, it has been determined that the radiation affects morphology change, as the particle size increases with increasing of the radiation dose. With the increase in the radiation dose, the emission intensity of samples decreases. The structure remains almost unchanged after irradiation, and the intensity constantly decreases with increasing of dose. [ABSTRACT FROM AUTHOR]

Molybdates have applications in various fields such as phosphors, optical fibers, scintillators, magnets, sensors and catalysts. Thulium ion is an excellent blue activator and plays an important role in the design of persistent luminescent materials. This paper reports the investigation of the structural and luminescent properties of Barium Thulium Molybdate (Ba 1− x Tm x )MoO 4 microcrystals (with x = 0, 0.01 or 0.03). The scheelite-type crystalline structure was identified from XRD and Raman studies. Under ultraviolet (359 nm) excitation, photoluminescence (PL) spectra present the characteristic emission bands at 453 nm and 545 nm which are due to the D 1 2 → F 3 4 and D 1 2 → H 3 4 , 5 transitions, respectively, from Tm 3+ ions. Thermoluminescence (TL) measurements were performed with powdered samples previously irradiated with beta radiation. The depth of traps, associated with trap levels located inside the band-gap, was determined from TL data using different methods of glow curve analysis. The kinetic parameters, determined from thermoluminescent glow curves, provide evidence about a possible persistent luminescence emission from the (Ba 0.97 Tm 0.03 )MoO 4 sample. This is a potential blue-light or ultraviolet long-lasting phosphor, with a trapping level lifetime, at room-temperature (300 K), of about 6 days. [ABSTRACT FROM AUTHOR]

A bilateral comparison of C activity measurements between ENEA-INMRI (Italy) and NCBJ RC POLATOM (Poland) was organized in the year 2015 and piloted by POLATOM, which provided the sources for the comparison. A set of six sources in Ultima Gold scintillator was measured at POLATOM using four different counters by two liquid scintillation counting methods: TDCR and CIEMAT/NIST. Three of sources were measured also at ENEA-INMRI by using two different TDCR counters. The results achieved in the comparison show an excellent agreement. [ABSTRACT FROM AUTHOR]

Ce3+/ Gd3+ co-doped NaBaBO 3 blue luminescent materials were synthesized by the solid-state reaction. Research shows that Ba2+ ions with larger ionic radius are replaced by Gd3+ ions and Ce3+ ions with smaller ionic radii. Gd3+ can act as a sensitizer to absorb energy and promote the luminescence of Ce3+.Under the excitation of 360 nm near ultraviolet light and X-ray, NaBaBO 3 :0.03Gd3+, 0.01Ce3+ can emit bright blue light, and its emission peak is located at 430 nm. [Display omitted] Ce3+ and Gd3+ co-doped NaBaBO 3 blue luminescent materials were synthesized by the solid-state reaction. X-ray diffraction, X-ray photoelectron spectrometer, and fluorescence spectrometer were used to analyze the crystal structure, the surface morphology, and the luminous properties. Ce3+/Gd3+ co-doped NaBaBO 3 phosphors can absorb near-ultraviolet light and emit bright blue light centered at 430 nm, which originates from the 5d-4f transition of Ce3+ ion. When the doping concentration of Ce3+ and Gd3+ was 1 % and 3 % respectively, Ce3+/Gd3+doped NaBaBO 3 had the strongest luminous intensity with a short decay time of about 23 ns. The addition of Gd3+ increases the luminescence intensity of Ce3+ doped NaBaBO 3. The CIE color coordinates are (0.1564, 0.0909). Ce3+/Gd3+ co-doped NaBaBO 3 powders are promising materials for WLEDs and scintillators. [ABSTRACT FROM AUTHOR]

The CeF 3 doped Gd 2-x MoB 2 O 9 phosphors (where x = 0.00, 0.25, 0.50 and 0.75 mol%) were synthesized by the conventional high-temperature solid-state reaction method at 900 °C for 12 h in air. DSC and TGA analysis executed to study the optimum temperature for sintering. The structural, photoluminescence and X-ray luminescence properties were investigated. The structure of the samples was analyzed by using X-ray diffractometer (XRD). The absorption spectra were analyzed and found that absorption edge increased with the increasing concentration of CeF 3. The photoluminescence of phosphors shows the overlapping of excitation and emission peaks in the range of 300 nm–450 nm. These emission peak correspond to the 5d – 4f transitions of Ce3+ ion. The optimum concentration of CeF 3 in these phosphors is 0.50 mol% corresponding to maximum emission intensity. The X-ray induced optical luminescence spectra showed a strong emission peak at 411 nm the concentration quenching at 0.75 mol%, which is as efficient as 54.4% compared with bismuth germanium oxide (BGO) crystal. The luminescence decay increased with the increment of CeF 3 concentration. From the optical properties investigated, it was found that the phosphors performed a strong and fast luminescence signal which is appropriate for the development of scintillators in X-ray detector devices. • Synthesis of phosphors doped Ce3+ ion for photonic and scintillation materials applications. • The strong emission spectra at 411 nm were observed. • The Decay time of the phosphors with the highest emission intensity (5d.→ 4f transition) was 12.35 ns • Highest X-ray-induced luminescence intensity is 411 nm of Ce3+ ion at the 5d.→ 4f transition. • The integral scintillation efficiency of phosphors was 54.44% of the BGO crystal. [ABSTRACT FROM AUTHOR]

This work investigates the physical, optical, luminescence, and scintillation properties of borosilicate glasses doped with different concentrations of Gd 2 O 3 and Dy 2 O 3. All glasses were prepared by the melt quenching technique. The density and molar volume value increase as the Gd 2 O 3 and Dy 2 O 3 content increases. Dy3+ in glasses absorb photons in visible light and near-infrared regions, confirmed by the absorption spectra. The emission spectra of glasses show two strong peaks at 575 nm (4F 9/2 →6H 13/2) and 481 nm (4F 9/2 →6H 15/2) under Gd3+, direct Dy3+ and X-ray excitation. The integral scintillation efficiency of 1.50Dy:12.5Gd is 7.22%, compared with BGO crystal. The luminescence of glass can be tuned for different shades of white emission by selecting the excitation source such as photon with 275 nm, 387 nm and X-ray, respectively. The developed glasses are the potential for tunable emitting and scintillation material applications. [ABSTRACT FROM AUTHOR]

Time-resolved luminescence properties of Ce3+ doped Y3Al5O12 (YAG) nanocrystals have been studied by means of vacuum-ultraviolet excitation spectroscopy. It was discovered that additionally to the regular Ce3+ yellow-green emission which is well-known luminescence in YAG, new emission covering a broad spectral range from 2.7 eV to 3.5 eV was revealed in the luminescence spectra for all YAG:Ce nanocrystals studied. This blue-UV emission has fast decay time about 7 ns as well as intensive well-resolved excitation band peaking at 5.9 eV and, in contrast to green Ce3+ emission, practically is not excited at higher energies. The origin of the blue-UV emission is tentatively suggested and discussed. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) [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]

Caesium iodide is one of the most extensively studied scintillators. Here, we present X-ray luminescence spectra, scintillation light output and decay curves as a function of temperature, from room temperature down to below 10 K. Features of the observed intrinsic luminescence are explained in terms of radiative recombination of on- and off-center STE. A model permitting interpretation of the dynamics of luminescence changes in CsI with temperature is suggested. This model includes adiabatic potential energy surfaces (APES) associated with singlet and triplet states of self-trapped excitons (STE) and explains the variation of the luminescence spectra with temperature as a result of re-distribution in the population between on- and off-center STE. The temperature dependence of the scintillation light yield is discussed in the framework of the Onsager mechanism. [ABSTRACT FROM AUTHOR]

Singulett ‐ Biradikaloide der Hauptgruppenelemente wurden in den letzten 20 Jahren gründlich untersucht, insbesondere Derivate des Cyclobutan ‐ 1,3 ‐ diyls. Jedoch sind in jedem der bekannten Beispiele die Radikalzentren äquivalent. Daher wollten wir ein gemischtes Dipniktadiazandiyl herstellen, in dem P und As den Radikalcharakter tragen. Um das Ziel zu erreichen, musste zunächst das Dichlorcycloarsaphosphadiazan [ClP(μ ‐ NTer)2AsCl] synthetisiert werden. Durch Chloridabstraktion von [ClP(μ ‐ NTer)2AsCl] wurde das cyclische Kation [P(μ ‐ NTer)2AsCl]+ erhalten, während die Reduktion mit Magnesium zum Arsaphosphadiazandiyl [P(μ ‐ NTer)2As] führte. Wenn man zu zweit ist, kann man nicht zu radikal sein: Das erste Biradikaloid mit unterschiedlichen Radikalzentren, das heteroatomare Biradikaloid [P(μ ‐ NR)2As], wurde durch Reduktion des entsprechenden Dichlorarsaphosphadiazans mit Magnesium erhalten. Die Molekülstruktur weist für den planaren viergliedrigen N2PAs ‐ Ring eine charakteristische Drachenform mit zwei gleichen P ‐ N ‐ und As ‐ N ‐ Abständen auf. CASSCF ‐ Rechnungen belegen einen Biradikalcharakter von 28 %. [ABSTRACT FROM AUTHOR]

Recent developments of plastic scintillators are reviewed, from 2000 to March 2014, distributed in two different chapters. First chapter deals with the chemical modifications of the polymer backbone, whereas modifications of the fluorescent probe are presented in the second chapter. All examples are provided with the scope of detection of various radiation particles. The main characteristics of these newly created scintillators and their detection properties are given. [ABSTRACT FROM AUTHOR]

Results of investigating an assembly of thin scintillators and silicon photomultipliers for registering relativistic particles with the minimum ionization are presented. A high efficiency of registering relativistic particles using an Ej-212 plastic scintillator, BSF-91A wavelength-shifting fiber (Saint-Gobain), and a silicon photomultiplier (Hamamtsu) is shown. The measurement results are used for creating a scintillation hodoscope of the magnetic spectrometer for registering γ quanta in the GlueX experiment. [ABSTRACT FROM AUTHOR]

Ce3+-doped lutetium aluminum garnet (LuAG) phosphors have been successfully synthesized by a facile carbon-free sol-gel method without using any organic gelling agent. Phase transitions from gel to LuAG were well investigated by X-ray diffraction and thermal analysis. The results confirmed that a pure LuAG phase can form at around 920 °C by directly crystallizing from amorphous material. Particle size of the LuAG phosphor can be controlled by adjusting the heat treatment process; therefore, both nano and micron-scale products can be obtained and they are suitable for the fabrication of laser scintillators and white light emitting diodes, respectively. Agglomeration can be observed in the nano-sized phosphor. For the micron-sized LuAG, a two-step process was used to avoid hard agglomeration. Particles of the obtained micron-sized phosphor are uniform and well-dispersed. Luminescence properties of the phosphors were characterized. Relative intensity of the micron-sized product is comparable with commercial phosphor. [ABSTRACT FROM AUTHOR]

Rare-earth (RE=Sm, Pr, Tb, Tm) doped ternary sulfides having the general formula KLn 0.995RE0.005 S 2 (Ln=La, Gd, Lu) and undoped KLnS 2 were synthesized in the form of crystalline hexagonal platelets by a chemical reaction in an electric resistance furnace under the flow of hydrogen sulfide. X-ray powder diffraction confirmed only a single phase of the rhombohedral lattice system (space group R-3 m). Time-resolved luminescence spectroscopy was employed to investigate radioluminescence, photoluminescence, decay kinetics and absorption spectra. The KLnS 2 band edge at 300–330 nm was found and characteristic Pr^3+, Sm^3+, Tb^3+ and Tm^3+~ 4 f -4 f emission lines in the visible spectral range were observed. The charge transfer transitions in the Pr^3+- and Sm^3+-related excitation spectra in the range 330–370 nm are described and the eficient energy transfer from the host to the emission centers is revealed. We discuss the potential for application of these materials in white LED solid-state lighting and X-ray phosphors. [ABSTRACT FROM PUBLISHER]

• Machine learning models for scintillator performance require self-consistent data. • High-throughput screening needs a universal preparation technique. • Multi-component aluminate garnets were synthesized by quenching of the melt. • Structural and luminescence properties of powder samples were evaluated. • A simplified model was developed for interpretation of radioluminescence intensity. Quenching from the melt using an Optical Floating Zone furnace was investigated as a possible high-throughput preparation method in order to screen novel scintillating materials. To validate this method, polycrystalline rare-earth aluminum garnets and yttrium gallium aluminum garnets were synthesized and characterized by X-ray diffraction, photoluminescence and radioluminescence emission spectra as well as radioluminescence imaging and compared to the previously reported properties of those materials. In order to achieve rapid, but quantitative comparison of the materials, pellets fabricated from the synthesized powders were sintered; two different sintering conditions were investigated and compared. A simplistic energy deposition and light absorption model for brightness of opaque samples under X-ray irradiation was developed to estimate the relative scintillation efficiency of the materials. Based on the results, Y 3 Al 5 O 12 , LuY 2 Al 5 O 12 and GdY 2 Al 5 O 12 seem to have the highest scintillation efficiency among the prepared samples. [ABSTRACT FROM AUTHOR]

Mechano-luminescence (ML) phenomenon is a non-destructive light generation mechanism with the effect of applied dynamic pressure on the materials. Here in present work, Mechano-luminescence response of Manganese (Mn) doped ZnS microcrystal is measured as a function of applied pressure and Mn concentration. First, ZnS is doped with three concentrations of Mn (0.5 M%, 1.0 M% and 1.5 M%) using solid state reaction mechanism at 1000 °C in an inert Argon atmosphere. The obtained material is characterized with Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Photo-luminescence (PL) techniques. The core mechano-luminescence (ML) signature of all samples is obtained using a custom designed dynamic vertical pressure impact setup. The pressure range for the experiments is kept from 10 to 400 bar with a gap of 50 bar for each measurement. It has been found that for ZnS:Mn with 1 M% doping concentration shows the highest ML emission intensity in comparison to 0.5 M% and 1.5 M%. It is also observed that ML intensity increases linearly with applied pressure for all three doping concentrations. Author has also discussed the decay time of signal with applied pressure. Results obtained show decrease in decay time for each drop height for all the samples. The current study clearly shows that ZnS:Mn has the ability to be used as an optical pressure sensor matrix material for impact sensor application. • Effect of impurity concentration on the mechano-luminescence response of manganese doped zinc sulphide a range of different vertical impact pressure. • Optical response of materials studied under customized calibrated dynamic pressure generator. • Effect of defects induced on the optical response and decay time of the material. [ABSTRACT FROM AUTHOR]

Ortho-phosphates according to the composition AB PO 4 (A = Li+, Na+, and K+; B = Mg2+, Ca2+, Sr2+, and Ba2+) are often investigated and used as hosts for Pr3+ activated phosphors or scintillators. In this work, the characterisation as well as the synthesis of microcrystalline Na 1+x Ca 1-2x PO 4 :Pr3+ x is discussed. In order to ensure that the investigated samples are single phase compounds, X-ray powder diffraction measurements were performed. The material was studied regarding its suitability as a UV-C emitting phosphor. Furthermore, the emission spectrum in the visible range was evaluated. Spectroscopic examinations included the temperature-dependent determination of the excitation and emission spectra as well as the measurement of the diffuse reflection characteristics. In order to evaluate its suitability as scintillator material, the emission of the samples was measured upon X-ray irradiation. • Temperature dependent UV luminescence of NaCaPO 4 :Pr between 100 and 500 K. • Temperature dependent characterisation of the red photoluminescence of NaCaPO 4 :Pr between 100 and 500 K. • X-ray excited luminescence of NaCaPO 4 :Pr at ambient temperature. [ABSTRACT FROM AUTHOR]

Abstract: The structural and luminescent properties of blue-emitting (Lu1−x−y Y x Ce y )2SiO5 (0.1≤x≤0.4, y=0.05, 0.005) phosphors prepared by combustion synthesis and post-annealed at 1200°C for different annealing times are reported. X-ray diffraction analysis revealed the formation of a (Lu,Y)2SiO5 solid solution as a majority phase with small traces of a residual phase that was identified as Lu2SiO7. Under long-UV excitation, the powders yield a very bright blue-emission consisting of two bands with maximum emissions located at λ=405nm and λ=440nm, both corresponding to the Ce3+ allowed transitions 2D3/2→2F5/2 and 2D5/2→2F7/2, respectively. Moreover, luminescence decay times of 38–45ns were measured, which depend on the composition, making these powders excellent candidates for application as scintillators in medical imaging. [Copyright &y& Elsevier]

Rare-earth doped solids have a number of useful scintillating and storage phosphor properties, and have received considerable attention because of their applications in sensors, optical and X-ray detectors, waveguides, lasers etc.. All samarium doped alkaline earth borophosphates were prepared by solid state reaction and melt quenched in air to form rare-earth doped glasses, glass ceramic and polycrystalline samples. Differential Scanning Calorimetry and Temperature Modulated Differential Scanning Calorimetry were carried out to extract the glass transformation properties for the glass and glass ceramic like samples. X-ray diffraction analysis was employed to investigate the phase composition and determine whether the synthesized samples were formed of glass or crystalline phases, or mixtures of both. Samples were irradiated by ultraviolet and blue light emitting sources to induce photoluminescence before and after exposure to synchrotron X-ray irradiation at the Canadian Light Source. X-ray induced luminescence spectra were also recorded. The experimental results are discussed in terms of the behavior of rare-earths in glasses and polycrystalline solids. The results indicate that while nearly all Sm3+ -doped polycrystalline borophosphates show the conversion of Sm3+ to Sm2+ upon exposure to X-rays, only certain glasses exhibit this conversion. Indeed, for a given composition, such as BaBPO5, the glass material shows no well defined Sm3+ to Sm2+ conversion, while the polycrystalline form exhibits a clear Sm3+ to Sm2+ conversion. Interestingly, all samples exhibit X-ray luminescence from Sm2+ ions during the X-ray irradiation; but there is no clear evidence of Sm2+ photoluminescence in non annealed samples after the cessation of X-ray synchrotron irradiation. [ABSTRACT FROM AUTHOR]

The ^3He shortage is forcing the neutron community to look for other detection methods. The inorganic scintillator may be an alternative. Thermal-neutron detection by means of inorganic scintillators has successfully been realized on a large scale at ISIS, UK, using ^6LiF/ZnS:Ag mixed with an organic binder. This material is now introduced in the security field. For several reasons other traditional neutron scintillators, ^6Li-glass:Ce and ^6LiI:Eu, and relatively new materials such as ^6Li6Gd(BO3)3:Ce and elpasolites like Cs2LiYCl6:Ce and Cs2LiLaBr6:Ce are hardly used or did not yet find their way to application. The same applies to more recently studied materials of the LICAF group. The pros and cons of these inorganic materials for thermal neutron detection will be discussed. [ABSTRACT FROM PUBLISHER]

Experiments to search for neutrinoless double beta decay are considered as an unique tool to study properties of neutrino and weak interactions. Scintillation detectors possess important properties required for high-sensitivity double beta decay experiments: presence of elements of interest, low level of intrinsic radioactivity, reasonable spectrometric characteristics, fast response, pulse-shape discrimination ability. Moreover, some crystal scintillators can be applied as cryogenic scintillating bolometers with high energy resolution and excellent particle discrimination. High concentration of isotope of interest and as low as possible radioactive contamination are important requirements to a scintillation material to be used in double beta decay experiments. Therefore development of radiopure crystal scintillators from isotopically enriched materials is required. Other important issues are maximal output of detectors and minimal loss of enriched materials. High quality, radiopure cadmium tungstate crystal scintillators were developed from enriched ^106Cd and ^116Cd, while calcium molybdate scintillators were grown form calcium depleted in ^48Ca and molybdenum enriched in ^100Mo. Prospects of several scintillation materials, promising for double beta experiments, are discussed. [ABSTRACT FROM PUBLISHER]

The influence of the geometry of the scintillators is presented in this paper. We focus on the effect of narrowing down the section of crystals that have a given length. The light output of a set of crystals with very similar scintillating properties but different geometries measured with several coupling/wrapping configurations is provided. We observe that crystals shaped in thin rods have a lower light output as compared to bulk or sliced crystals. The effect of unpolishing the crystal faces is also investigated, and it is shown that highest light outputs are not necessarily obtained with crystals having all faces polished. Simulation results based on a realistic model of the crystal that implements light scattering on the crystal edges are in agreement with the experimental data. Fine-tuning of this model would allow us to further explore the details of light propagation in scintillators and would be highly valuable to fast timing detection and highly granular detectors. [ABSTRACT FROM PUBLISHER]

Non-stoichiometric undoped zirconates of Ca, Sr and Ba were prepared and studied for their luminescence and scintillation characteristics in a broad range of compositions. Powder samples were prepared by solid state reaction method. Based on phase analysis the zirconate phases compositions in the sintered samples have been determined. Dominant emission band of these materials is situated in near UV-blue spectral range. The highest scintillation efficiency was found at the samples of the strontium zirconate containing surplus of ZrO2. [ABSTRACT FROM PUBLISHER]

Abstract: The heavily Ce-doped SrHfO3 (SHO) and the undoped non-stoichiometric SHO sample sets were prepared by solid state reaction in powder form and their luminescence spectra and decay kinetics were measured. Concentration quenching effects and thermally induced ionization of the Ce3+ excited states were followed and discussed in the former sample set. In the latter one new emission band at about 334nm was found in Sr-deficient samples and temperature dependences of its emission intensity and decay times were studied in the detail. Room temperature decay time of about 180ns and efficient and fast energy transfer from the host to the center of the 334nm emission make this material promising candidate for X-ray phosphors. [Copyright &y& Elsevier]

Abstract: We report the scintillation luminosities, decay times, and emission wavelengths for 19 Ce3+ activated scintillators, 18 Eu2+ activated scintillators, and 4 self-activated scintillators. Of these, 18 have not been previously reported either as phosphors or scintillators. Their luminosities range from 40,000 to under 1000photons/MeV. While these scintillators may not have properties that make them top candidates for widespread use, their data will contribute to a deeper understanding of factors that limit scintillator performance. [Copyright &y& Elsevier]

Abstract: In this paper we discuss two novel methods of measuring afterglow in scintillators. One method is designed for X-ray detection and the other for neutron detection applications. In the first method a commercial fan-beam scanner of basic design similar to those seen at airports is used to deliver a typically 12ms long X-ray pulse to a scintillator by passing the test equipment through the scanner on the conveyor belt. In the second method the thermal neutron beam from a research reactor is incident on the scintillator. The beam is cut-off in about 1ms using a 10B impregnated aluminum pneumatic shutter, and the afterglow is recorded on a dual range storage oscilloscope to capture both the steady state intensity and the weak decay. We describe these measurement methods and the results obtained for a range of developmental ceramic and glass scintillators, as well as some standard scintillators such as NaI(Tl), LiI(Eu) and the plastic scintillator NE102A. Preliminary modeling of the afterglow is presented. [Copyright &y& Elsevier]

A combinatorial chemistry method was employed to screen the yellow phosphors of (Lu1-xGdx)3Al5O12;Ce3y, as luminescenet materials. An array of 81 compositions was synthesized by inkjetting nitrate solutions into microreactor wells and sintering at high temperature. The candidate formulations were evaluated by luminescence pictures, and the optimal composition was determined to be Lu2.7Gd0.3 Al5O12:Ce0.045 after scale-up and detailed characterization. Lu2.7Gd0.3 Al5O12:Ce0.045 was also found to have a short decay time (⩽53.97 ns). These results demonstrate the great potential of the Lu2.7Gd0.3 Al5O12:Ce0.045 as a component of ceramic scintillators. [ABSTRACT FROM AUTHOR]

Excellent properties of optical ceramics initially developed as laser materials make them attractive for scintillator applications. The effects of the porosity of ceramics on their luminescence properties is analyzed using a simplified model to account for scattering. The results of the study of optical and luminescence properties of a concentration series of YAG:Yb ceramics fabricated by vacuum sintering and nanocrystalline technology (VSN method) in a wide UV and VUV and X-rays excitation energy range are presented. The results are compared to those obtained for Yb-doped single crystals and undoped YAG ceramics and single crystals. [ABSTRACT FROM AUTHOR]

Technology of producing single crystal scintillators is rather a hard and complex technological task connected with a very low output issue (15-50%) of the material and the restricted area of its application. Recent efforts of scientists are directed toward searching for alternative ways for producing these materials. It was established that high-performance ceramic scintillation materials for producing the scintillators could be prepared by using powder metallurgy techniques. However despite of certain achievements in this area, transparency of ceramic scintillators is still under the question. In our opinion a key to the solution of the problem lies in preparing scintillators in nanocrystalline structural state. A technology developed on the basis of the modified Sol-Gel method shows possibilities of manufacturing number of standard (as well as new hard to obtain as single crystals) scintillation materials. Present work is dedicated to the problems of manufacturing yttrium orthosilicate (Y2SiO5 )—as of one of the perspective scintillation materials. [ABSTRACT FROM AUTHOR]

Our experiments with nanocrystalline scintillating rare earth oxides and rare earth fluorides have shown that in some cases nanoscopic dimensions provide essential improvement of the most important scintillation parameters: light yield, kinetics of scintillations, radiation hardness, etc. We found that in the range from 20 to 100-nm of the oxide and fluoride particles there are 3 types of layered structures: with expanded exterior layer, with changed phase structure, and with changed chemical composition. These layered structures can strongly influence scintillation parameters: cause an increase or decrease in the light yield, vary scintillation kinetics, modify radiation hardness, etc. Control of dimensions and structures of nanoscintillators can be used for significant modifications of parameters of radiation detectors (radical acceleration of kinetics, enhancement of light yield, increase in radiation hardness, etc.). Radiation detectors based on nanoscintillators have promising prospects for applications in new generations of devices for medical diagnostics, security inspection, radiation monitoring of nuclear reactors. [ABSTRACT FROM AUTHOR]

Atomic-scale simulations have been employed to predict the site solution preference of Bi3+ activator cations in a series of RE2 O3 scintillators with the bixbyite crystal structure (Ia3), where RE denotes a 3+ cation ranging in size from Sc3+ to La3+. There are two crystallographically unique cation sites in the bixbyite structure, in Wyckoff notation referred to as the 24d and 8b site. It is expected that the spectroscopic properties of an activator cation residing on the 24d site will be different from the same activator cation residing on the 8b site, due to the distinct symmetries (C2 and S6 respectively) of these two sites. Previous studies have revealed two different Bi3+ emissions in Y2O3 corresponding to Bi3+ cations occupying both lattice 24d and 8b sites. By predicting the energy difference of the Bi3+ solution on the 24d and 8b sites, we are able to predict the distribution of Bi3+ in a range of bixbyite compounds. [ABSTRACT FROM AUTHOR]

CeBr3 crystals have been studied to assess their utility as potential gamma ray spectrometers for future ESA planetary missions. Pulse height spectra, scintillation time profiles, X-ray excited emission spectra, and photoluminescence spectra have been recorded as a function of temperature between 78 and 600 K. In addition, the influence of exposing CeBr3 to various doses of gamma rays from a strong 60Co source on its scintillation performance has been investigated. [ABSTRACT FROM AUTHOR]

Abstract: For a multi-layer depth-of-interaction (DOI) detector using different decay times, pulse shape analysis based on two different integration times is often used to distinguish scintillators in DOI direction. This method measures a partial integration and a full integration, and calculates the ratio of these two to obtain the pulse shape distribution. The full integration time is usually set to integrate full width of the scintillation pulse. However, the optimum partial integration time is not obvious for obtaining the best separation of the pulse shape distribution. To make it clear, a theoretical analysis and experiments were conducted for pulse shape analysis by changing the partial integration time using a scintillation detector of GSOs with different amount of Ce. A scintillation detector with 1-in. round photomultiplier tube (PMT) optically coupled GSO of 1.5mol% (decay time: 35ns) and that of 0.5mol% (decay time: 60ns) was used for the experiments. The signal from PMT was digitally integrated with partial (50–150ns) and full (160ns) integration times and ratio of these two was calculated to obtain the pulse shape distribution. In the theoretical analysis, partial integration time of 50ns showed largest distance between two peaks of the pulse shape distribution. In the experiments, it showed maximum at 70–80ns of partial integration time. The peak to valley ratio showed the maximum at 120–130ns. Because the separation of two peaks is determined by the peak to valley ratio, we conclude the optimum partial integration time for these combinations of GSOs is around 120–130ns, relatively longer than the expected value. [Copyright &y& Elsevier]

Abstract: An extended version of the scintillator response function prediction code SCINFUL has been developed by incorporating PHOTRACK, a Monte Carlo light transport code. Comparisons of calculated and experimental results for organic scintillators exposed to neutrons show that the extended code improves the predictive capability of SCINFUL. [Copyright &y& Elsevier]

Abstract: A new synthesis route to prepare well-crystallized hexagonal rare earth oxycarbonates, II-RE2O2CO3 (RE=La, Gd, and Y) in a single phase, has been established by a simple flux method. The precursor obtained by calcination of corresponding acetates was mixed with a 0.476Li2CO3–0.270Na2CO3–0.254K2CO3 eutectic mixture and heated in a pure CO2 (100%) atmosphere to obtain Eu3+- or Tb3+-doped II-RE2O2CO3 (RE=La, Gd, and Y) phosphors. Although the particle size of the oxycarbonate phosphors was in a submicron scale, they showed high emission intensities. The highest emission intensity was obtained successfully by changing the gas composition from 10%CO2–90%N2 to pure CO2 and by optimizing the flux treatment temperature, holding the particle size in a submicron scale. The maximum emission intensity was obtained at the composition of Gd2O2CO3:15at.%Tb3+, where it was 111% of that of a commercial LaPO4:Ce3+,Tb3+ phosphor. [Copyright &y& Elsevier]

Abstract: In the framework of an assessment of lanthanum halide scintillators, such as LaBr3:Ce and LaCl3:Ce on their suitability for space based gamma-ray spectroscopy, proton induced activation of the materials has been studied. One inch scintillators were subjected to proton irradiations in the range of 60–184MeV, where after the activation was measured. The activation was analyzed by identifying the decaying isotopes by means of gamma-ray spectroscopy and lifetime measurements using both a germanium detector and the activated scintillator itself. It was found that the dominant source of activation in the scintillators originates from the lighter elements in the materials: bromide and chloride, respectively. The activation of LaBr3:Ce manifest itself through gamma-decay, which partly leaves the volume. Activation of LaCl3:Ce originates mainly from beta decay, which is confined to the volume itself. [Copyright &y& Elsevier]

The focus of this paper is the evaluation of the new fast 51 mm-diameter, 8-stage Hamamatsu R9779 photomultipliers (PMTs) with an acceleration-ring at the front-end and the Photonis XP20D0 PMTs with a screening grid in front of the anode. The following performance characteristics are presented: Timing resolution, anode-scan-uniformity and transit-time spread. The unfolded timing resolution for two R9779 was 192 ps and 210 Ps using plastic scintillators. The individual timing resolutions for two XP20D0 using plastic scintillators are 181 ps and 154 ps, respectively. The variation in time resolution across the windows of the two R9779 ranged between 117 ps and 171 ps, and 79 ps and 73 ps for the two XP20D0 PMTs. [ABSTRACT FROM AUTHOR]

Abstract: SrAl2B2O7:Tb3+ phosphors were fabricated by the sol–gel method. The phosphor showed prominent luminescence in green due to the 5D4–7F5 transition of Tb3+ . Structural characterization of the luminescent material was carried out with X-ray powder diffraction (XRD) analysis. Luminescence properties were analyzed by measuring the excitation and photoluminescence spectra. Photoluminescence measurements indicated that the phosphor exhibited bright green emission at about 541 nm under UV excitation. It is shown that the 11% of doping concentration of Tb3+ ions in SrAl2B2O7:Tb3+ phosphors is optimum. [Copyright &y& Elsevier]