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• A serial of Eu2+-doped CLLB single crystals were successfully grown. • The Eu2+ activated CLLB matrix strategy increases the Stokes shift. • The light yields of CLLB: 2% Eu is 18700ph/MeV under 137Cs source at 662 keV. • CLLB: Eu crystal has the application potential of long afterglow X-ray imaging. In this work, a novel single crystal scintillator, Eu2+-doped Cs 2 LiLaBr 6 (CLLB: Eu) with Ф12 mm × 50 mm, was successfully grown by the Bridgman method. The effects of substitution amount of europium ions on the crystal structure, luminescent properties and scintillation properties were systematically studied by fluorescence spectroscopy, XEL, decay kinetics, and temperature-dependent emission spectra. The Cs 2 LiLaBr 6 :2%Eu sample presents the highest light yield under X-ray excitation, which is about 235 times that of commercial BGO single crystals. The nanosecond decay lifetime of Eu2+ was observed in Cs 2 LiLaBr 6 :Eu crystal. The afterglow result indicates that the Cs 2 LiLaBr 6 : Eu crystal has a long afterglow and the afterglow mechanism of Cs 2 LiLaBr 6 : Eu crystal was proposed and constructed. It has a potent application in nuclear radiation detection and imaging as a scintillation long afterglow material. [ABSTRACT FROM AUTHOR]

• K 2 LaBr 5 :Eu2+ single crystal was obtained successfully by vertical Bridgman method without flux for the first time. • The luminescence phenomenon of K 2 LaBr 5 :Eu2+ was studied. • The optical transmission of K 2 LaBr 5 :Eu2+ single crystal was presented and the bandgap was estimated according to Tauc and Menth's law. • For the first time, the decay time of the heterovalently doped K 2 LaBr 5 :Eu2+ single crystal under gamma rays is nanoseconds. Recent researches have shown that Eu2+ ion heterovalently doped rare earth halide scintillators attract the attention of researchers. In this paper, the transparent K 2 LaBr 5 scintillation crystals of centimeter size doped with heterovalent Eu2+ were successfully grow by the vertical Bridgman technique. X-ray powder diffraction analysis shows that the crystal has an orthonormal structure with space group Pnma(62). A small amount of Eu2+ doping does not change the internal structure of the crystal. The transmittance, the UV–visible excited spectrum and emission spectrum, X-ray excited luminescence spectrum, Photoluminescence decay time and scintillation pulse decay time have been measured at room temperature. The results show that the crystal has strong luminescence intensity, and the maximum emission peak is about 430 nm. The photoluminescence decay time of K 2 LaBr 5 :xmol.%Eu2+(x = 0.5, 1, 2) are 5.56 μs, 5.67 μs and 7.03 μs, respectively. The decay time of K 2 LaBr 5 :Eu2+ crystal under 137Cs 662 keV radiation is nanosecond, indicating that the K 2 LaBr 5 :Eu2+ crystal has fast decay characteristics and excellent time resolution performance. [ABSTRACT FROM AUTHOR]

• We grew phenanthrene crystals by the using the self-seeding vertical Bridgman technique. • The grown phenanthrene crystals were identified by powder XRD and FTIR. • We evaluated the optical and scintillation properties of grown phenanthrene crystals. Phenanthrene crystals were grown by the self-seeding vertical Bridgman technique as a neutron scintillation material and their luminescence properties were evaluated. As-grown crystals had no secondary phases from the results of the powder X-ray Diffraction and Fourier transform infrared spectrometer measurements. The radioluminescence emission spectrum had a peak at 408 nm and its profile was similar to that of the photoluminescence emission spectrum. The relative light yield under 5.5-MeV alpha-ray was 1.15 times higher than that of lithium glass GS-20. The light yield of phenanthrene under 662 keV gamma-ray is estimated to be 38 ± 2% of NaI:Tl. The scintillation decay time under neutron excitation was estimated to be 7.30 ± 0.14 ns. [ABSTRACT FROM AUTHOR]

Abstract: Luminescence and scintillation properties of Tm3+ 0.1–15% doped CaF2 crystals were systematically investigated. The crystals were grown by a simple solidification method which allowed us to obtain single crystals conveniently. In X-ray induced radio luminescence spectra, the luminosity of the self-trapped-exciton (STE) emission of CaF2 at 270nm decreased with increasing of Tm3+ concentration. The Tm3+ 5d-4f transition based emission lines appeared at 175nm (4f115d high spin state (HS)→ 3H6) and at 165nm (low spin state (LS) to 3H6). Pulse height spectra were measured under α-ray irradiation by using vacuum ultra-violet (VUV) sensitive photomultiplier tube (PMT) R8778 and Tm3+ 0.1% doped specimen exhibited the highest light yield. [Copyright &y& Elsevier]

Abstract: The work is dedicated to growth by the liquid phase epitaxy method and study of the luminescence and scintillation properties of Sc3+ doped single crystalline films (SCF) of Lu3Al5O12 (LuAG) garnet. The scintillation properties of SCF are compared with single crystal (SC) analogues grown by the Horizontal Direct Crystallization and Czochralski methods. We consider the dependence of intensity of the Sc3+ emission in LuAG host on the activator concentration and influence of flux contamination on the light yield (LY) of the Sc3+ luminescence in LuAG:Sc SCF with respect to their SC counterparts and the reference YAP:Ce scintillator. From the NMR investigations of LuAG:Sc SCF we confirm the substitution by Sc3+ ions both the octahedral and dodecahedral positions of LuAG host and formation of the ScAl and ScLu related emission centers, respectively. We also show that the luminescence spectrum in the UV range and decay kinetics of LuAG:Sc SCF can be effectively tuned by changing the scandium content. [Copyright &y& Elsevier]

Abstract: Ce and Eu doped LiSrAlF6 (LiSAF) single crystals for the neutron detection with different dopant concentrations were grown by the micro-pulling-down method (μ-PD). In Ce:LiSAF, intense emission peaks due to Ce3+ 5d–4f transitions were observed at approximately 315 and 335nm in photo- and α-ray induced radio-luminescence spectra. In case of Eu:LiSAFs, an intense emission peak at 375nm due to Eu2+ 5d–4f transition was observed in the radio-luminescence spectra. The pulse height spectra and decay time profiles were measured under 252Cf neutron irradiation to examine the neutron response. The Ce 3% and Eu 2% doped LiSAF showed the highest light yield of 2860ph/n with 19ns main decay time component and 24,000ph/n with 1610ns. [Copyright &y& Elsevier]

Abstract: Na x Ca1−2 x Lu x − y Nd y F2 single crystals were grown from the melt using the precise atmosphere control type Micro-Pulling-Down (μ-PD) method to investigate their potential as a vacuum-ultraviolet (VUV) scintillators. The grown crystals were single-phase materials with fluorite-type structure (Fm-3m, Z= 4) as confirmed by XRD. The crystals demonstrated 80–90% transmittance above 200nm wavelength and Nd3+ 5d–4f luminescence (when exited by X-ray) observed around 185nm. The radioluminescence measurements under 5.5MeV α-ray excitation (241Am) demonstrated the light yield of 48 [Ph/5.5MeV-α] and the decay time of 6.4–7.7ns. [Copyright &y& Elsevier]

Luminescence and scintillation properties of YAO:Ce single crystals grown from the melt by the Czochralski and horizontal directed crystallization methods in various gas media and YAO:Ce single-crystal films grown by liquid-phase epitaxy from a melt solution based on a PbO-BO flux have been comparatively analyzed. The strong dependence of scintillation properties of YAO:Ce single crystals on their growth conditions and concentrations of Y antisite defects and vacancy defects has been established. Vacancy defects are involved in Ce ion emission excitation as the centers of intrinsic UV luminescence and trapping centers. It has been shown that YAO:Ce single-crystal films are characterized by faster scintillation decay kinetics than single crystals and a lower content of slow components in Ce ion luminescence decay during high-energy excitation due to the absence of Y antisite defects in them and low concentration of vacancy defects. At the same time, the light yield of YAO:Ce single-crystal films is comparable to that of single crystals grown by directed crystallization due to the quenching effect of the Pb ion impurity as a flux component and is slightly lower (∼25%) than the light yield of single crystals grown by the Czochralski method. [ABSTRACT FROM AUTHOR]

Abstract: Transparent Lu0.8Sc0.2BO3:Ce single crystals doped with different Ce concentrations were grown by the Czochralski method. X-ray diffraction measurements showed that the as-grown crystals all possessed hexagonal structure with space group. The more initial Ce ion doping content in Lu0.8Sc0.2BO3:Ce, the smaller effective segregation coefficient of Ce in crystal will be, confirmed by the inductively coupled plasma atomic emission spectrometry (ICP-AES) tests. The Ce3+ 5d→4f emission band and five excitation states were both observed in the photoluminescence spectra (PL). The increase of luminescence center in crystal or the concentration quenching exerts effects in the change of PL decay time, depending on the cerium concentration. The radioluminescence spectra showed that the Lu0.8Sc0.2BO3:Ce crystals had one broad emission band corresponding to the 5d→4f transition of Ce3+ ions, similar to their PL spectra. Consequently, we found that Lu0.8Sc0.2BO3:2at.%Ce crystal achieved the maximum scintillation efficiency and for Lu0.8Sc0.2BO3:3at.%Ce crystal, there might be already affected by a concentration quenching effect. [Copyright &y& Elsevier]

Abstract: Nd3+ doped CaF2 single crystal scintillator has been investigated. We tried to grow 1%, 5%, 10%, 20%, 30% and 40% Nd3+ doped CaF2 single crystals by the simple melt-solidifying method. Powder X-ray diffraction (XRD) patterns were measured to identify the phase of all the samples. The XRD patterns of all the samples were similar to CaF2. Those samples are compared in terms of their X-ray-excited radioluminescence spectra, transmittance, α-ray-excited decay time and light yield. When the X-ray is used for excitation, luminescence is observed in the VUV region. Transmittance of the crystals is more than 70% at wavelengths longer than about 180nm. In the decay kinetics, the fast components of the samples are distributed in less than 25ns time range and the slow components of sample are distributed in more than 90ns. These decay times became shorter with increasing Nd3+ concentration. They are related to the Nd3+ 5d-4f VUV emission. The light yields of samples are distributed in 5–2500 photon/5.5MeV α-ray and decrease with increasing Nd3+ concentration. [ABSTRACT FROM AUTHOR]

Abstract: Pr3+ 0.2, 0.75, and 3mol% doped YAP single crystalline scintillators were grown by using the micro-pulling down (μ-PD) method. Pr3+ 0.05mol% doped YAP was also prepared by using the Czochralski method. In transmittance spectra, 4f–5d absorption line appeared at 230nm. The μ-PD grown crystals showed intense emission at 290nm while the Czochralski grown one showed an emission peak at 245nm in radio luminescence spectra under X-ray excitation. Among them, the Czochralski grown one exhibited the highest light yield under 137Cs 662keV excitation and the absolute light yield of this sample was estimated to be 20400±2000ph/MeV. The decay time constants of these scintillators were around 10ns due to Pr3+ 5d–4f transition. [ABSTRACT FROM AUTHOR]

Abstract: Pr1%:K(Y1−x Lu x )3F10 (x=0, 0.2, 0.4) single crystals were grown by the μ-PD method. All the grown crystals were greenish and perfectly transparent without any inclusions or cracks. Radioluminescence spectra and decay kinetics of the Pr1%:K(Y,Lu)3F10 crystals were measured. Emission from the Pr3+ 5d–4f transition, peaking around 260nm and of the decay time of around 22ns were observed. The 5d–4f emission intensities of the Pr1%:K(Y,Lu)3F10 crystals were higher than that of the standard BGO scintillator. [ABSTRACT FROM AUTHOR]

Abstract: Two-inch diameter Nd3+ doped LaF3 single crystals were successfully grown by the Czochralski technique. No remarkable absorption due to unfavorable impurities or color centers was observed from optical absorption measurements in the vacuum ultra-violet spectral region. The high crystallinity and homogeneous Nd3+ distribution were found from X-ray rocking curve and chemical composition analysis, respectively. X-ray excited luminescence spectrum was measured and the significant 4f25d–4f3 luminescence at 173nm was observed in the grown crystal. The pulse height spectrum and scintillation decay curves were taken upon γ-ray irradiation. As a result, the grown crystals demonstrated sufficient response to the γ-ray, the light yield of 140±30photons/MeV, and fast scintillation decay of 7.6ns. [Copyright &y& Elsevier]

Abstract: Chemically stable and transparent K2NaLuF6 single crystals doped with Tm3+ ions were grown by the micro-pulling down method (μ-PD). X-ray diffraction measurements showed that the as-grown crystals possess cubic structure with Fm3m space group. The radio- and photo-luminescence spectra of the grown crystals were measured in the vacuum ultraviolet (VUV) and ultraviolet (UV) regions. Tm:K2NaLuF6 showed high emission intensity at 188nm in the radio- and photo-luminescence spectra (λ exc =159nm). The decay time and light yield of Tm:K2NaLuF6 were also investigated by 241Am 5.5MeV α-ray irradiation. The main component of the decay time was a 4–8μs and this emission was considered as 5d–4f emission from 4f n −15d high-spin state (parity allowed and spin forbidden transition). In addition to this, the light yield of Tm-doped K2NaLuF6 single crystals systematically increased with increasing Tm concentration. [Copyright &y& Elsevier]

Single crystals of SrI2 :Eu and SrI2 :Ce/Na were grown from anhydrous iodides by the vertical Bridgman technique in evacuated silica ampoules. Growth rates were of the order of 5-30 mm/day. Radioluminescence spectra of SrI2:Eu and SrI2:Ce/Na exhibit a broad band due to Eu2+ and Ce3+ emission, respectively. The maximum in the luminescence spectrum of SrI2:Eu is found at 435 nm. The spectrum of SrI2:Ce/Na exhibits a doublet peaking at 404 and 435 nm attributed to Ce3+ emission, while additional impurity-or defect-related emission is present at approximately 525 nm. The strontium iodide scintillators show very high light yields of up to 120 000 photons/MeV, have energy resolutions down to 3% at 662 keV (Full Width Half Maximum) and exhibit excellent light yield proportionality with a standard deviation of less than 5% between 6 and 460 keV. [ABSTRACT FROM AUTHOR]

• γ-CuI single crystal was obtained successfully by vertical Bridgman method for the first time. • The optimum growth parameters of γ-CuI single crystal were studied in detail. • The optical transmission of γ-CuI single crystal was presented and the bandgap was estimated. • The photoluminescence spectra and X-ray excited luminescence of γ-CuI single crystal were investigated. The cuprous iodide (γ-CuI) exhibits an ultrafast scintillation property with decay time about 90 ps and shows a great potential application in ultrafast scintillators. In this paper, the γ-CuI crystal with dimensions of φ 10 mm × 24 mm was obtained by the vertical Bridgman method for the first time. The effects of raw material purification, furnace temperature, cooling and pulling rates crystal growth were presented in detail. The optimum growth conditions are as follows: pulling rate at 0.33 mm/h, cooling rate at 8.96 °C/h after growth, the furnace temperature at 675 °C. The optical transmittance, the photoluminescence and the X-ray excited luminescence of the as-grown crystals were characterized. [ABSTRACT FROM AUTHOR]

Elpasolite halides scintillation crystals have been proven to be very important materials for X-ray and γ-ray detector applications. The crystals of Cs2KLaCl6:4% Ce (CKLC) and Cs2KCeCl6 (CKCC) belong to novel scintillation of the Chloro-elpasolite crystal family. In this paper, the crystal growth of CKLC and CKCC crystals using the vertical Bridgman techniques were reported. The PXRD patterns showing both crystals have a cubic crystal structure. Both crystals have similar photoluminescence excitation and emission spectra, the fluorescence decay time of CKLC and CKCC crystals were about 49.7 and 33.8 ns. The energy resolution under the excitation of 662 keV γ-rays from a 137Cs source were found to be 6.6% and 5.2% (FWHM), respectively. The scintillation decay times of CKLC crystal were τ1 = 127 ns (33%) and τ2 = 1617 ns (67%), while that of CKCC crystal were τ1 = 2.86 ns (5%) and τ2 = 81 ns (95%). [ABSTRACT FROM AUTHOR]

Abstract: Transparent ceramic Ce 0.5% doped Lu3Al5O12 (LuAG) scintillator grown by the sintering method and single crystalline Ce doped LuAG grown by the Czochralski method are prepared. They are cut to the physical dimensions 4 × 4 × 2 mm3. Their transmittance and radio luminescence spectra are evaluated. They are both transmissive in wavelength longer than 500 nm and intense Ce3+ 5d–4f emission appears around 520 nm. When 137Cs γ-ray is irradiated, 662 keV photo-absorption peaks are clearly observed in each sample. The transparent ceramic one shows higher light yield than that of the single crystalline one. The absolute light yield of the ceramic sample is turned out to be 14800 ± 1500 ph/MeV. The decay time constants are evaluated under pulse X-ray excitation. The main component of the decay time of ceramic and single crystalline one are determined as 37 and 46 ns, respectively. [Copyright &y& Elsevier]