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Sample records for csitl phosphor coupled

  1. Signal and noise transfer properties of CMOS based active pixel flat panel imager coupled to structured CsI:Tl.

    Science.gov (United States)

    Arvanitis, C D; Bohndiek, S E; Blakesley, J; Olivo, A; Speller, R D

    2009-01-01

    Complementary metal-oxide-semiconductors (CMOS) active pixel sensors can be optically coupled to CsI:Tl phosphors forming a indirect active pixel flat panel imager (APFPI) for high performance medical imaging. The aim of this work is to determine the x-ray imaging capabilities of CMOS-based APFPI and study the signal and noise transfer properties of CsI:Tl phosphors. Three different CsI:Tl phosphors from two different vendors have been used to produce three system configurations. The performance of each system configuration has been studied in terms of the modulation transfer function (MTF), noise power spectra, and detective quantum efficiency (DQE) in the mammographic energy range. A simple method to determine quantum limited systems in this energy range is also presented. In addition, with aid of monochromatic synchrotron radiation, the effect of iodine characteristic x-rays of the CsI:Tl on the MTF has been determined. A Monte Carlo simulation of the signal transfer properties of the imager is also presented in order to study the stages that degrade the spatial resolution of our current system. The effect of using substrate patterning during the growth of CsI:Tl columnar structure was also studied, along with the effect of CsI:Tl fixed pattern noise due to local variations in the scintillation light. CsI:Tl fixed pattern noise appears to limit the performance of our current system configurations. All the system configurations are quantum limited at 0.23 microC/kg with two of them having DQE (0) equal to 0.57. Active pixel flat panel imagers are shown to be digital x-ray imagers with almost constant DQE throughout a significant part of their dynamic range and in particular at very low exposures.

  2. An analytical approach to the light transport in columnar phosphors. Detector Optical Gain, angular distribution and the CsI:Tl paradigm.

    Science.gov (United States)

    Psichis, Konstantinos; Kalyvas, Nektarios; Kandarakis, Ioannis; Panayiotakis, George

    2017-03-01

    An analytical model has been developed for the light propagation in columnar phosphors, based on the optical photon propagation physical and geometrical principles. This model accounts for the multiple reflections on the sides of the crystal column, as well as for the infinite forward and backward reflections of the propagated optical photon beams created in the crystal bulk. Additionally it considers the lateral propagated optical photon beams after multiple refractions from the neighbor columns and the optical photon attenuation inside the scintillator. The model was used to predict the Detector Optical Gain (DOG), and the angular distribution, of the columnar CsI:Tl scintillators, used in medical imaging. The model was validated against CsI:Tl optical photon transmission published results and good agreement was observed. It was, also, found that the DOG is affected by the length of the columns, as well as the incident X-ray energy spectrum. The results of the angular distribution are in accordance with the theory that the longer crystal columns have more directional light distribution. The results of DOG are in accordance with the use of short crystal columns for lower energies (mammography) and the use of long crystal columns for higher energies (general radiology). Angular distribution was found more directive for long crystal columns. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  3. Optimisation on the two-layer stack gamma detectors of CsI(Tl) coupled with a pin photodiode for non-destructive testing.

    Science.gov (United States)

    Bai, Jin Hyoung; Whang, Joo Ho

    2011-07-01

    This paper proposed the two-layer stack scintillator-coupled photodiode detector to improve the measurement accuracy of the gamma-ray scanning. Both MCNPX and DETECT97 code were used to design the detector. The two manufactured two-layer stack gamma detectors were used to measure the density profile of the distillation column of the radiographic non-intrusive process diagnostic area. To compare the measurement accuracy of the density profile through the non-destructive transmission test, the relative error of the four fluids used for the process diagnostics was analysed. To summarise the measurement results with regard to the relative error of the NaI(Tl) detector and the manufactured detector by material as well as the total relative error, the total relative error of the NaI(Tl) detector was about 15.7 %, whereas that of the two-layer stack CsI(Tl) with photodiode detectors were about 5 %. This paper confirmed that the measurement accuracy of the detector proposed was improved by about three times as compared with the NaI(Tl) detector mostly used for non-destructive testing.

  4. Characterization of prototype full-field breast tomosynthesis by using a CMOS array coupled with a columnar CsI(Tl) scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae-Gu; Choi, Young-Wook; Ham, Tae-Hee [Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Park, Hye-Suk; Kim, Ye-Seul; Kim, Hee-Joung [Yonsei University, Wonju (Korea, Republic of)

    2012-02-15

    We have developed a prototype full-field digital breast tomosynthesis (DBT) system by using a complementary-metal-oxide semiconductive (CMOS) array coupled with a columnar CsI(Tl) scintillator. The imaging system consists of a matrix with an active detector area of 3072 x 3888 pixels and a pixel pitch of 74.8 μm. For tomosynthesis imaging, the X-ray tube is automatically rotated in 3 .deg. increments in the shoot mode to acquire projection images at 15 different angles over a ±21 .deg. angular range in less than 10 s. The digital detector is stationary during image acquisition. In this research, we also carried out evaluation studies to characterize the performance of the system in different operational modes designed for the DBT system, e.g., binning mode and the range of view angles, in terms of the modulation transfer function (MTF), the normalized noise power spectra (NNPS), and the detective quantum efficiency (DQE): The MTF value measured at the Nyquist frequency was 18.49%, the NNPS value at zero frequency was about 1.93 x 10{sup -5} (mm{sup 2}), and the maximum value of DQE was about 47.09% for the full resolution. For the pixel binning mode, the MTF decreased more than it did for the full resolution mode due to the increased effective pixel size. However, the full resolution mode was more sensitive to noise than the pixel binning mode. For the scan angle of the DBT system, oblique incidence of X-rays on a detector caused blurring that reduced resolution. These results seem to be promising for the use of the DBT system in potential clinical applications and will provide important information when comparisons with other DBT systems are made.

  5. Phosphoric Acid-Mediated Synthesis of Vinyl Sulfones through Decarboxylative Coupling Reactions of Sodium Sulfinates with Phenylpropiolic Acids.

    Science.gov (United States)

    Rong, Guangwei; Mao, Jincheng; Yan, Hong; Zheng, Yang; Zhang, Guoqi

    2015-08-07

    A novel phosphoric acid -mediated synthesis of vinyl sulfones through decarboxylative coupling reactions of sodium sulfinates with phenylpropiolic acids is described. This transformation is efficient and environmentally friendly.

  6. Light collection enhancement of the digital x-ray detector using Gd 2O 2S:Tb and CsI:Tl phosphors in the aspect of nano-scale light dispersions

    Science.gov (United States)

    Woo, Taeho; Kim, Taewoo

    2012-01-01

    The nano-scopic light collection is investigated for the Active Matrix Flat-Panel Imagers (AMFPIs). The simulations using two kinds of screens are shown for light collection of x-rays. Enhancement of the light collection is accomplished by the microlens system incorporated with x-ray detector. For digital radiographic and mammographic applications, indirect detection imagers use Gd 2O 2S:Tb or CsI:Tl scintillation screens to convert the x-ray into visible photons. The light collection efficiencies for Gd 2O 2S and CsI are obtained. In Gd 2O 2S, the 27 kVp and 82 μm are the highest light collection cases in both Lambertian and Isotropic geometries. In CsI, 20 keV and 150 μm case have the highest light collection efficiency. So, x-ray energy and scintillator thicknesses are considered as the optimized light collection. The optimum thickness and x-ray energy combination are used for the detector of this study. In this paper, it is concluded that the screens between 17 kVp and 25 kVp have higher light collections, which could be considered as the clinical purposes if it is necessary. This energy range is compared with other energy cases, which are examined in the study.

  7. Structure and scintillation properties of CsI(Tl) films on Si single crystal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Lina [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Liu, Shuang, E-mail: shuangliu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Chen, Dejun; Zhang, Shangjian; Liu, Yong; Zhong, Zhiyong [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Falco, Charles M. [University of Arizona, College of Optical Sciences, AZ 85721 (United States)

    2016-10-30

    Highlights: • We obtained the desired micro-columnar structure of CsI(Tl) films on the orienting Si substrates. • We improved the micro-columnar structure of CsI(Tl) films under the relatively large deposition rate through using the substrate with a pre-deposited CsI nanolayer. • We modeled the interface structures between the CsI(Tl) films with (200) and (310) orientation and Si(111) substrates to explain the preferred orientation of film under the influence of the orienting substrate significantly. • We gained a new spectrum of the CsI(Tl) films peaked at 740 nm wavelength. - Abstract: CsI(Tl) scintillation films fabricated on glass substrates are widely applied for X-ray imaging because their ability to grow in micro-columnar structure and proper emission wavelength matching CCD cameras. But the coupling process between the CsI(Tl) films and Si-based photo detector would cause coupling loss. In this work, CsI(Tl) films were deposited on the orienting Si substrates and the Si substrates covered by the pre-deposited CsI nanolayers. Structure and scintillation properties of films were examined by using scanning electron microscopy, X-ray diffraction, photoluminescence and radioluminescent spectrum. The films deposited on the orienting Si substrates show the micro-columnar morphology with perfect single crystalline structure and the photoluminescence spectra with bimodal distribution. The performances of the films prepared on the pre-deposited CsI nanolayer, containing micro-columns structure and the light yield are improved.

  8. Impact of precursor purity on optical properties and radiation detection of CsI:Tl scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Saengkaew, Phannee; Cheewajaroen, Kulthawat; Yenchai, Chadet; Thong-aram, Decho [Chulalongkorn University, Department of Nuclear Engineering, Faculty of Engineering, Bangkok (Thailand); Sanorpim, Sakuntam [Chulalongkorn University, Department of Physics, Faculty of Science, Bangkok (Thailand); Jitpukdee, Manit [Kasetsart University, Department of Applied Radiation and Isotope, Faculty of Science, Bangkok (Thailand); Yordsri, Visittapong; Thanachayanont, Chanchana [Ministry of Science and Technology, National Metal and Materials Technology Center, National Science and Technology Development Agency, Pathumthani (Thailand); Nuntawong, Noppadon [Ministry of Science and Technology, National Electronic and Computer Technology Center, National Science and Technology Development Agency, Pathumthani (Thailand)

    2016-08-15

    orange scintillators. In summary, the unintended impurity as calcite in low-cost CsI:Tl scintillators was found to enhance PL emission but shift the PL wavelength. However, efficiency of radiation detection is slightly lower. By coupling with a suitable PMT, the radiation detection efficiency of low-cost CsI:Tl scintillators can be improved. From these valuable results, growing new ternary materials as CsCaI{sub 2} or CsI:Ca or Ca-codoped CsI:Tl scintillators could be one of the promising approaches to achieve highly efficient and low-cost radiation detectors with the optimization of the crystal growth conditions in the future. (orig.)

  9. A theoretical study of CsI:Tl columnar scintillator image quality parameters by analytical modeling

    Energy Technology Data Exchange (ETDEWEB)

    Kalyvas, N., E-mail: nkalyvas@teiath.gr; Valais, I.; Michail, C.; Fountos, G.; Kandarakis, I.; Cavouras, D.

    2015-04-11

    Medical X-ray digital imaging systems such as mammography, radiography and computed tomography (CT), are composed from efficient radiation detectors, which can transform the X-rays to electron signal. Scintillators are materials that emit light when excited by X-rays and incorporated in X-ray medical imaging detectors. Columnar scintillator, like CsI:T1 is very often used for X-ray detection due to its higher performance. The columnar form limits the lateral spread of the optical photons to the scintillator output, thus it demonstrates superior spatial resolution compared to granular scintillators. The aim of this work is to provide an analytical model for calculating the MTF, the DQE and the emission efficiency of a columnar scintillator. The model parameters were validated against published Monte Carlo data. The model was able to predict the overall performance of CsI:Tl scintillators and suggested an optimum thickness of 300 μm for radiography applications. - Highlights: • An analytical model for calculating MTF, DQE and Detector Optical Gain (DOG) of columnar phosphors was developed. • The model was fitted to published efficiency and MTF Monte Carlo data. • A good fit was observed for 300 µm columnar CsI:Tl thickness. • The performance of the 300 µm column thickness CsI:Tl was better in terms of MTF and DOG for radiographic applications.

  10. Enzymatic saccharification coupling with polyester recovery from cotton-based waste textiles by phosphoric acid pretreatment.

    Science.gov (United States)

    Shen, Fei; Xiao, Wenxiong; Lin, Lili; Yang, Gang; Zhang, Yanzong; Deng, Shihuai

    2013-02-01

    In order to recycle the cotton-based waste textiles, a novel process was designed for pretreating waste textiles with phosphoric acid to recover polyester and fermentable sugar. The effects of pretreatment conditions including, phosphoric acid concentration, pretreatment temperature, time, and ratio of textiles and phosphoric acid were thoroughly investigated. Results indicated the mentioned four factors had significant influences on sugar and polyester recovery. Almost complete polyester recovery was achieved by enhancing phosphoric acid concentration, temperature and pretreatment time or reducing the ratio of textiles and phosphoric acid. However, these behaviors decreased the sugar recovery seriously. 100% polyester recovery with a maximum sugar recovery of 79.2% was achieved at the optimized conditions (85% phosphoric acid, 50°C, 7h, and the ratio of 1:15). According to the technical and cost-benefit analysis, it was technically feasible and potentially profitable to recover polyester and sugar from waste textiles by phosphoric acid pretreatment.

  11. A CsI(Tl) detector array used in the experiment of the proton-rich nucleus 17Ne

    Institute of Scientific and Technical Information of China (English)

    MA Li-Ying; HUA Hui; LU Fei; CHEN Dong; JIANG Xi-Yao; YE Yan-Lin; JIANG Dong-Xing; Qureshi Faisal-Jamil

    2009-01-01

    To investigate the configurations of the valence protons in Borromean nucleus 17Ne, a CsI(Tl) detector array, which consists of 9 CsI crystals (26×26×20mm3) coupled with photodiodes, has been successfully used in the 17Ne experiment to measure the energy of protons. In order to find the optimal working conditions and get the best energy resolutions, several technologies (including various wrapping materials, wrapping and coupling methods) have been used. The testing results showed that the best energy resolution of the CsI(Tl) is about 3.3% using the 241 Am α-source. The primary testing results with the proton beam were also provided.

  12. Search for solar axions with CsI(Tl) crystal detectors

    CERN Document Server

    Yoon, Y S; Bhang, H; Choi, J H; Choi, S; Hahn, I S; Jeon, E J; Joo, H W; Kang, W G; Kim, B H; Kim, G B; Kim, H J; Kim, K W; Kim, S C; Kim, S K; Kim, Y D; Kim, Y H; Lee, H S; Lee, J H; Lee, J K; Lee, S J; Leonard, D S; Li, J; Myung, S S; Olsen, S L; So, J H

    2016-01-01

    The results of a search for solar axions from the Korea Invisible Mass Search (KIMS) experiment at the Yangyang Underground Laboratory are presented. Low-energy electron-recoil events would be produced by conversion of solar axions into electrons via the axio-electric effect in CsI(Tl) crystals. Using data from an exposure of 34,596 $\\rm kg \\cdot days$, we set a 90 \\% confidence level upper limit on the axion-electron coupling, $g_{ae}$, of $1.39 \\times 10^{-11}$ for an axion mass less than 1 keV/$\\rm c^2$. This limit is lower than the indirect solar neutrino bound, and fully excludes QCD axions heavier than 0.48 eV/$\\rm c^2$ and 140.9 eV/$\\rm c^2$ for the DFSZ and KSVZ models respectively.

  13. Search for solar axions with CsI(Tl) crystal detectors

    Science.gov (United States)

    Yoon, Y. S.; Park, H. K.; Bhang, H.; Choi, J. H.; Choi, S.; Hahn, I. S.; Jeon, E. J.; Joo, H. W.; Kang, W. G.; Kim, B. H.; Kim, G. B.; Kim, H. J.; Kim, K. W.; Kim, S. C.; Kim, S. K.; Kim, Y. D.; Kim, Y. H.; Lee, H. S.; Lee, J. H.; Lee, J. K.; Leonard, D. S.; Li, J.; Myung, S. S.; Olsen, S. L.; So, J. H.

    2016-06-01

    The results of a search for solar axions from the Korea Invisible Mass Search (KIMS) experiment at the Yangyang Underground Laboratory are presented. Low-energy electron-recoil events would be produced by conversion of solar axions into electrons via the axio-electric effect in CsI(Tl) crystals. Using data from an exposure of 34,596 kg · days, we set a 90 % confidence level upper limit on the axion-electron coupling, g ae , of 1 .39 × 10 -11 for an axion mass less than 1 keV/c2. This limit is lower than the indirect solar neutrino bound, and fully excludes QCD axions heavier than 0.48 eV/c2 and 140.9 eV/c2 for the DFSZ and KSVZ models respectively.

  14. CsI(Tl) infrared scintillation light yield and spectrum

    CERN Document Server

    Belogurov, S; Carugno, Giovanni; Conti, E; Iannuzzi, D; Meneguzzo, Anna Teresa

    2000-01-01

    Infrared emission from CsI(Tl) excited by approx 70 keV electrons was detected with an InGaAs PIN photodiode. Some parameters of infrared scintillation were studied. The emission spectrum is located between 1.55 and 1.70 mu m with a maximum at 1.60 mu m. The light yield of infrared scintillation is (4.9+-0.3)x10 sup 3 photons/MeV. Infrared scintillation caused by 3 MeV alpha-particles is detected as well.

  15. Electron-phonon coupling properties and energy transfer in NaY(WO{sub 4}){sub 2}:Eu{sup 3+} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ting; Meng, Qingyu, E-mail: qingyumeng163@163.com; Sun, Wenjun

    2015-10-25

    NaY(WO{sub 4}){sub 2} phosphors with various Eu{sup 3+} concentrations were prepared via a molten salt method. The crystal structure and morphology of the phosphors were characterized by means of XRD and field emission scanning electron microscope. The excitation spectra and emission spectra were measured. The energy transfer type between Eu{sup 3+} was proved. What's more, the critical energy transfer distance (Rc) and Huang-Rays factor were calculated. The self-generated quenching process of Eu{sup 3+} was explained based on Auzel's model, and the intrinsic radiative transition lifetime for {sup 5}D{sub 0} level was confirmed. The energy transfer rate between Eu{sup 3+} ions was derived on the basis of the fluorescence lifetime. Finally, the refractive index n was calculated. - Highlights: • We reported a method of low calcined temperature to synthesize tungstate phosphors. • The paper studied concentration dependence of electron-phonon coupling strength. • The energy transfer type among Eu{sup 3+} ions is exchange interaction on NaY(WO{sub 4}){sub 2} host. • We provided a method to obtain the refractive index of the non-transparent powder.

  16. CsI(Tl) for WIMP dark matter searches

    CERN Document Server

    Kudryavtsev, V A; Tovey, Daniel R; Roberts, J W; Lehner, M J; McMillan, J E; Lightfoot, P K; Lawson, T B; Peak, C D; Lüscher, R; Barton, J C

    2001-01-01

    We report a study of CsI(Tl) scintillator to assess its applicability in experiments to search for dark matter particles. Measurements of the mean scintillation pulse shapes due to nuclear and electron recoils have been performed. We find that, as with NaI(Tl), pulse shape analysis can be used to discriminate between electron and nuclear recoils down to 4 keV. However, the discrimination factor is typically (10-15)% better than in NaI(Tl) above 4 keV. The quenching factor for caesium and iodine recoils was measured and found to increase from 11% to ~17% with decreasing recoil energy from 60 to 12 keV. Based on these results, the potential sensitivity of CsI(Tl) to dark matter particles in the form of neutralinos was calculated. We find an improvement over NaI(Tl) for the spin independent WIMP-nucleon interactions up to a factor of 5 assuming comparable electron background levels in the two scintillators.

  17. Pulse shape discrimination properties of Gd3Ga3Al2O12:Ce,B single crystal in comparison with CsI:Tl

    Science.gov (United States)

    Rawat, S.; Tyagi, Mohit; Netrakanti, P. K.; Kashyap, V. K. S.; Mitra, A.; Singh, A. K.; Desai, D. G.; Kumar, G. Anil; Gadkari, S. C.

    2016-12-01

    Single crystals of Gd3Ga3Al2O12:Ce,B and CsI:Tl were grown by Czochralski and Bridgman techniques, respectively. While both the crystals exhibited similar emission at about 550 nm, their scintillation decay times showed significantly different characteristics. The average scintillation decay time of Gd3Ga3Al2O12:Ce,B crystal was found to be about 284 ns for alpha excitation compared to 108 ns measured for a gamma source. On the other hand in CsI:Tl crystals, the alpha excitation resulted in a lower average decay time of 600 ns compared to 1200 ns with gamma excitation. Their pulse shape discrimination (PSD) for gamma and alpha radiations were studied by coupling the scintillators with photomultiplier tube or SiPM and employing an advanced digitizer as well as a conventional zero-crossing setup. In spite of having a poor α/γ light yield ratio, the PSD figure of merit and the difference of zero-crossing time in Gd3Ga3Al2O12:Ce,B crystals were found to be superior in comparison to CsI:Tl crystals.

  18. CsI(Tl) scintillators as gamma-ray detectors for the identification of hidden explosives

    CERN Document Server

    Fioretto, E; Innocenti, F D; Viesti, G; Cinausero, M; Coco, I; Fabris, D; Filippini, V; Lunardon, M; Nebbia, G; Prete, G; Pesente, S; Sajo-Bohus, L; Chukhaev, E; Melnikov, A I

    2001-01-01

    We report on the performances of CsI(Tl) crystals as gamma-ray detectors, compared with standard NaI(Tl). Energy resolution from E subgamma=122 keV up to E subgamma=7.6 MeV and light output yield of different CsI(Tl) crystals and read-out configurations (photomultiplier tubes, photodiodes and avalanche photodiodes) have been measured.

  19. Validation of simulated point response of columnar phosphor screens

    Science.gov (United States)

    Badano, Aldo; Kyprianou, Iacovos S.; Tang, Katherine H.; Saha, Anindita

    2007-03-01

    Typical methods to measure the resolution properties of x-ray detectors use slit or edge devices. However, complete models of imaging systems for system optimization require knowledge of the point-response function of the detector. In this paper, we report on the experimental methods developed for the validation of the point-response function of an indirect columnar CsI:Tl detector predicted by Monte Carlo using mantis. We describe simulation results that replicate experimental resolution measurements using edge and pinhole devices. The experimental setup consists of a high-resolution CCD camera with a 1-to-1fiber optic faceplate that allows measurements for different scintillation screens. The results of these experiments and simulations constitute a resource for the development and validation of the columnar models of phosphor screens proposed as part of previous work with mantis. We compare experimental high-resolution pinhole responses of two different CsI(Tl) screens to predictions from mantis. The simulated response matches reasonably well the measurements at normal and off-normal x-ray incidence angle when a realistic pinhole is used in the simulation geometry. Our results will be combined with results on Swank factors determined from Monte Carlo pulse-height spectra to provide a comprehensive validation of the phosphor models, therefore allowing their use for in silico system optimization.

  20. Study on the effect of film formation process and deposition rate on the orientation of the CsI:Tl thin film

    Science.gov (United States)

    Tan, Xiaochuan; Liu, Shuang; Xie, Yijun; Guo, Lina; Ma, Shijun; Wang, Tianyu; Liu, Yong; Zhong, Zhiyong

    2017-10-01

    Although many new scintillation materials are developed, CsI:Tl is still prevailing because of its high scintillation efficiency. In this work, CsI:Tl thin films were fabricated by vacuum thermal evaporative deposition method and their morphology properties and growth orientation were observed by SEM and XRD. Photoluminescent spectra were used to measure the luminescent properties of the CsI:Tl thin film. The results show us the film formation process of CsI:Tl thin film and analyze the effect of film formation process and the deposition rate on the orientation of the CsI:Tl thin film.

  1. Diagnostic Accuracy of Charge-coupled Device Sensor and Photostimulable Phosphor Plate Receptor in the Detection of External Root Resorption In Vitro

    Directory of Open Access Journals (Sweden)

    Shirin Sakhdari

    2015-03-01

    Full Text Available Background and aims. Early diagnosis of external root resorption is important for accurate treatment. The purpose of this study was to compare the efficacy of a charge-coupled device (CCD sensor and a photostimulable phosphor (PSP plate receptor in the diagnosis of artificial external root resorption. Materials and methods. In this diagnostic in-vitro study, 40 maxillary incisors were mounted in a segment of dry bone and preliminary radiographs were obtained using CCD and PSP sensors. Artificial resorption cavities were produced on the middle-third in half of the samples and on the cervical-third in the other half on the buccal root surfaces. Radiographs were repeated and images were evaluated. Data were statistically analyzed using chi-square and diagnostic tests. Results. There were no significant differences between the two sensors in the sensitivity (p=0.08 and 0.06 and specificity (p=0.13 for the diagnosis of resorption in both root areas. The overall accuracy of CCD was higher than PSP sensor; how-ever, the difference was not statistically significance (p>0.05. Conclusion. CCD and PSP sensors chosen for the present study produced similar results in diagnosing simulated external root resorption.

  2. Fast preconcentration of trace rare earth elements from environmental samples by di(2-ethylhexyl)phosphoric acid grafted magnetic nanoparticles followed by inductively coupled plasma mass spectrometry detection

    Science.gov (United States)

    Yan, Ping; He, Man; Chen, Beibei; Hu, Bin

    2017-10-01

    In this work, di(2-ethylhexyl)phosphoric acid (P204) grafted magnetic nanoparticles were synthesized by fabricating P204 onto Fe3O4@TiO2 nanoparticles based on Lewis acid-base interaction between Ti and phosphate group under weakly acidic condition. The prepared Fe3O4@TiO2@P204 nanoparticles exhibited excellent selectivity for rare earth elements, and good anti-interference ability. Based on it, a method of magnetic solid phase extraction (MSPE) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for fast preconcentration and determination of trace rare earth elements in environmental samples. Under the optimal conditions, the detection limits of rare earth elements were in the range of 0.01 (Tm)-0.12 (Nd) ng L- 1 with an enrichment factor of 100-fold, and the relative standard deviations ranged from 4.9 (Pr) to 10.7% (Er). The proposed method was successfully applied to the determination of rare earth elements in environmental samples, including river water, lake water, seawater and sediment.

  3. Performance assessment of CsI(Tl) screens on various substrates for X-ray imaging

    Institute of Scientific and Technical Information of China (English)

    FENG Zhao-Dong; JIANG Peng; ZHANG Hong-Kai; ZHAO Bo-Zhen; QIN Xiu-Bo; WEI Cun-Feng; LIU Yu

    2015-01-01

    Thallium-doped cesium iodide (CsI(Tl)) screens are widely used in X-ray imaging devices because of the columnar structure of the CsI(Tl) layer,but few reports focus on the optical role of the substrate in the screen system.In this paper,four substrates including fused silica (SiO2),silver-film coated SiO2,graphite (C) and fiber optic plate (FOP) are used to fabricate CsI(Tl) screens by thermal evaporation.Their imaging performance is evaluated by relative light output (RLO),modulation transfer function (MTF),normalized noise power spectrum (NNPS) and noise equivalent quanta (NEQ).The results reveal that although CsI(Tl) film on graphite plate yields images with the lowest light output,it presents relatively higher spatial resolution and better signal-to-noise characteristics.However,films on SiO2 plate obtain low MTF but high NNPS curves,whether they are coated with silver film or not.Furthermore,scintillation screens on FOP have bright images with low NNPS and high NEQ,but have the lowest MTF.By controlling the substrate optical features,CsI(Tl) films can be tailored to suit a given application.

  4. Performance of CsI(Tl) calorimeter in an experiment with stopped K sup + 's

    CERN Document Server

    Kudenko, Yu G

    2002-01-01

    The performance of the photon detector constructed for the search of T-violation in the decay K sup +-> pi sup 0 mu sup +nu is presented. The specific features of this detector consisting of 768 CsI(Tl) crystals with PIN photodiode readout for high precision measurement of T-odd correlations in decays of positive kaons are considered.

  5. Comparative studies of YAG(Ce) and CsI(Tl) scintillators

    CERN Document Server

    Bhattacharjee, T; Dey, C C; Chatterjee, M B

    2002-01-01

    The performances of YAG(Ce) and CsI(Tl) scintillators have been compared using photomultiplier tube (PMT) readout for gamma rays and alpha particles. It is found that the energy resolution of YAG(Ce) is inferior to that of CsI(Tl). With Philips XP2971 PMT, we have obtained improved energy and time resolution for YAG(Ce), compared to the same, obtained by earlier workers using XP2020/Q. The best values of energy resolution (FWHM), obtained in the present work, for 662 keV gamma ray, are 6% and 7%, respectively, for CsI(Tl) and YAG(Ce), whereas for 5.48 MeV alpha particles, the observed values are 6% and 8.4%, respectively. The pulse height response of both the scintillators has been found to be reasonably linear up to 1.3 MeV gamma energy. A prompt time resolution of 1.3 ns (FWHM) has been obtained with a BaF sub 2 - YAG(Ce) combination against 511-511 keV photopeak selection, which compares well with that obtained for a BaF sub 2 -CsI(Tl) combination, used by us.

  6. Performance assessment of CsI(Tl) screens on various substrates for X-ray imaging

    CERN Document Server

    Feng, Zhaodong; Zhang, Hongkai; Zhao, Bozhen; Qin, Xiubo; Wei, Cunfeng; Liu, Yu; Wei, Long

    2015-01-01

    Thallium-doped cesium iodide (CsI(Tl)) screens are widely used in X-ray imaging devices because of the columnar structure of CsI(Tl) layer, but few reports focus on the optical role of the substrate in the screen system. In this paper, four substrates including fused silica (SiO2), silver-film coated SiO2, graphite (C) and fiber optic plate (FOP) are used to fabricate CsI(Tl) screens by thermal evaporation. Their imaging performance is evaluated by relative light output (RLO), modulation transfer function (MTF), normalized noise power spectrum (NNPS) and noise equivalent quanta (NEQ). The results reveal that although CsI(Tl) film on graphite plate yields images with the lowest light output, it presents relatively higher spatial resolution and better signal-to-noise characteristics. However, films on SiO2 plate obtain low MTF but high NNPS curves, whether or not coated with silver film. Furthermore, scintillation screens on FOP have bright images with low NNPS and high NEQ, but have the lowest MTF. By controll...

  7. Effect of Eu{sup 2+} concentration on afterglow suppression in CsI:Tl, Eu

    Energy Technology Data Exchange (ETDEWEB)

    Kappers, L.A. [Department of Physics, University of Connecticut, Storrs, CT 06269-3046 (United States)], E-mail: lawrence.kappers@uconn.edu; Bartram, R.H.; Hamilton, D.S. [Department of Physics, University of Connecticut, Storrs, CT 06269-3046 (United States); Brecher, C.; Lempicki, A. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States); Gaysinskiy, V.; Ovechkina, E.E.; Nagarkar, V.V. [Radiation Monitoring Devices, Inc., 44 Hunt str., Watertown, MA 02472 (United States)

    2007-04-15

    Combined radioluminescence and thermoluminescence experiments on the co-doped scintillator material CsI:Tl, Eu were extended in the present investigation to a sample with diminished europium concentration. Simulations based on postulated rate equations with empirically adjusted parameters are consistent with observed insensitivity of afterglow suppression to europium concentration for sufficiently short radiation times.

  8. Novel laser-processed CsI:Tl detector for SPECT.

    Science.gov (United States)

    Sabet, H; Bläckberg, L; Uzun-Ozsahin, D; El-Fakhri, G

    2016-05-01

    The aim of this work is to demonstrate the feasibility of a novel technique for fabrication of high spatial resolution CsI:Tl scintillation detectors for single photon emission computed tomography systems. The scintillators are fabricated using laser-induced optical barriers technique to create optical microstructures (or optical barriers) inside the CsI:Tl crystal bulk. The laser-processed CsI:Tl crystals are 3, 5, and 10 mm in thickness. In this work, the authors focus on the simplest pattern of optical barriers in that the barriers are created in the crystal bulk to form pixel-like patterns resembling mechanically pixelated scintillators. The monolithic CsI:Tl scintillator samples are fabricated with optical barrier patterns with 1.0 × 1.0 mm(2) and 0.625 × 0.625 mm(2) pixels. Experiments were conducted to characterize the fabricated arrays in terms of pixel separation and energy resolution. A 4 × 4 array of multipixel photon counter was used to collect the scintillation light in all the experiments. The process yield for fabricating the CsI:Tl arrays is 100% with processing time under 50 min. From the flood maps of the fabricated detectors exposed to 122 keV gammas, peak-to-valley (P/V) ratios of greater than 2.3 are calculated. The P/V values suggest that regardless of the crystal thickness, the pixels can be resolved. The results suggest that optical barriers can be considered as a robust alternative to mechanically pixelated arrays and can provide high spatial resolution while maintaining the sensitivity in a high-throughput and cost-effective manner.

  9. Practical applications of phosphors

    CERN Document Server

    Yen, William M; Yamamoto, Hajime

    2006-01-01

    Drawn from the second edition of the best-selling Phosphor Handbook, Practical Applications of Phosphors outlines methods for the production of various phosphors and discusses a broad spectrum of applications. Beginning with methods for synthesis and related technologies, the book sets the stage by classifying and then explaining practical phosphors according to usage. It describes the operating principle and structure of phosphor devices and the phosphor characteristics required for a given device, then covers the manufacturing processes and characteristics of phosphors. The book discusses research and development currently under way on phosphors with potential for practical usage and touches briefly on phosphors that have played a historical role, but are no longer of practical use. It provides a comprehensive treatment of applications including lamps and cathode-ray tubes, x-ray and ionizing radiation, and for vacuum fluorescent and field emission displays and covers inorganic and organic electroluminescen...

  10. Temperature dependence of CsI(Tl) gamma-ray excited scintillation characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Valentine, John David [Univ. of Michigan, Ann Arbor, MI (United States)

    1993-01-01

    Gamma-ray excited emission spectrum, absolute scintillation yield, rise and decay time constants, and thermoluminescence emissions of CsI(Tl) were measured at -100 to +50 C, for crystals from 4 different vendors. The thermoluminescence glow curves were the only property that varied significantly from crystal to crystal; room temperature operation in current mode could be susceptible to temperature fluctuations. The CsI(Tl) emission spectrum has emission bands peaking around 400 and 560 nm; the former band disappears between -50 and -75 C. The RT absolute scintillation yield was calculated to be 65,500{plus_minus}4,100 photons/MeV. The two primary decay time constants increases about exponentially with inverse temperature. An ultra-fast decay component was confirmed. Applications are discussed.

  11. Particle identification using CsI(Tl) crystal with three different methods

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Three pulse-shape-discrimination (PSD) methods are applied to study the particle identification (PID) by using CsI(Tl) crystal, especially for identifying light charged particles. The zero-cross time method, fast and total component method and signal rise time method are used. The experiment, data analysis and results are compared. Good PID for p, α and γ, can be achieved with a CsI(Tl)-photomultiplier assembly.

  12. A New Columnar CsI(Tl) Scintillator for iQID detectors.

    Science.gov (United States)

    Han, Ling; Miller, Brian W; Barber, H Bradford; Nagarkar, Vivek V; Furenlid, Lars R

    2014-09-12

    A 1650 μm thick columnar CsI(Tl) scintillator for upgrading iQID detectors, which is a high-resolution photon-counting gamma-ray and x-ray detector recently developed at the Center for Gamma-Ray Imaging (CGRI), has been studied in terms of sensitivity, spatial resolution and depth-of-interaction effects. To facilitate these studies, a new frame-parsing algorithm for processing raw event data is also proposed that has more degrees of freedom in data processing and can discriminate against a special kind of noise present in some low-cost intensifiers. The results show that in comparison with a 450 μm-thickness columnar CsI(Tl) scintillator, the 1650 μm thick CsI(Tl) scintillator provides more than twice the sensitivity at the expense of some spatial resolution degradation. The depth-of-interaction study also shows that event size and amplitude vary with scintillator thickness, which can assist in future detector simulations and 3D-interaction-position estimation.

  13. Results from an investigation of the physical origins of nonproportionality in CsI(Tl)

    Science.gov (United States)

    Asztalos, S.; Hennig, W.; Warburton, W. K.

    2011-10-01

    The relative scintillation response per energy deposited by Compton electrons, or nonproportionality, has traditionally been considered an intrinsic scintillator property. However, such an interpretation is inconsistent with recent results that show nonproportionality to depend on external factors such as shaping time, temperature and supplier. Apparently, at least some of the overall nonproportionality has an extrinsic origin. In this work we describe the results from a suite of measurements designed to test the hypothesis that nonproportionality in CsI(Tl) material has an extrinsic component that correlates with impurity levels. Our choice of material was motivated by the excellent energy resolution observed in one bulk crystal (6.4%)—a marked departure from that measured with conventional CsI(Tl) stock (8-8.5%). Six bulk CsI(Tl) crystals were procured and diced into 44 wafers. Using X-ray fluorescence techniques no conclusive evidence for impurities was found in any of the wafers at the 1-50 ppm level. One crystal exhibited a distinct correlation among energy resolution, decay lifetimes, nonproportionality and a very low level of Tl doping.

  14. Fundamentals of phosphors

    CERN Document Server

    Yen, William M; Yamamoto, Hajime

    2006-01-01

    Drawing from the second edition of the best-selling Handbook of Phosphors, Fundamentals of Phosphors covers the principles and mechanisms of luminescence in detail and surveys the primary phosphor materials as well as their optical properties. The book addresses cutting-edge developments in phosphor science and technology including oxynitride phosphors and the impact of lanthanide level location on phosphor performance.Beginning with an explanation of the physics underlying luminescence mechanisms in solids, the book goes on to interpret various luminescence phenomena in inorganic and organic materials. This includes the interpretation of the luminescence of recently developed low-dimensional systems, such as quantum wells and dots. The book also discusses the excitation mechanisms by cathode-ray and ionizing radiation and by electric fields to produce electroluminescence. The book classifies phosphor materials according to the type of luminescence centers employed or the class of host materials used and inte...

  15. Large-size CsI(Tl) crystal read-out by SiPM for low-energy charged-particles detection

    Science.gov (United States)

    Bondí, M.; Battaglieri, M.; Carpinelli, M.; Celentano, A.; De Napoli, M.; De Vita, R.; Marsicano, L.; Randazzo, N.; Sipala, V.; Smith, E. S.

    2017-09-01

    Silicon photomultipliers are a novel technology for the detection of photons in near ultraviolet, visible, and near-infrared spectral ranges. Their application is rapidly growing and extending to many fields in physics, replacing traditional PMTs and APDs. In this study a large-size CsI(Tl) crystal coupled to small-area SiPM (3 × 3mm2) was used to detect α-particles and low energy protons. In particular, the detector was irradiated with proton beams accelerated by the Tandem Van-der-Graff of the INFN-Laboratori Nazionali del Sud (LNS), at incident energies between 2.5 MeV and 24 MeV. The detector performance was studied in terms of light yield, linearity and energy resolution. In addition, we investigated the dependence of the detector response on the impact point of the particles.

  16. A comparison of CsI:Tl and GOS in a scintillator-CCD detector for nuclear medicine imaging

    Science.gov (United States)

    Bugby, S. L.; Jambi, L. K.; Lees, J. E.

    2016-09-01

    A number of portable gamma cameras for medical imaging use scintillator-CCD based detectors. This paper compares the performance of a scintillator-CCD based portable gamma camera with either a columnar CsI:Tl or a pixelated GOS scintillator installed. The CsI:Tl scintillator has a sensitivity of 40% at 140.5 keV compared to 54% with the GOS scintillator. The intrinsic spatial resolution of the pixelated GOS detector was 1.09 mm, over 4 times poorer than for CsI:Tl. Count rate capability was also found to be significantly lower when the GOS scintillator was used. The uniformity was comparable for both scintillators.

  17. Calibrating the CsI(Tl) detectors of the GARFIELD apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Abbondanno, U. E-mail: abbondanno@ts.infn.it; Bruno, M.; Casini, G.; Cavaletti, R.; Cavallaro, Sl.; Chiari, M.; D' Agostino, M.; Gramegna, F.; Lanchais, A.; Margagliotti, G.V.; Mastinu, P.F.; Milazzo, P.M.; Moroni, A.; Nannini, A.; Ordine, A.; Vannini, G.; Vannucci, L

    2002-08-11

    The energy and charge dependence of the light output of the CsI(Tl) detectors of the GARFIELD apparatus has been investigated for heavy ions with 5{<=}Z{<=}16 in the energy range from 2.2 to 8.3 A MeV. The results have been compared to an analytical expression successfully used in previous calibration procedures at higher energies, and a rather good agreement was obtained between measured and calculated quantities. The resulting parameter set was successfully applied to another set of experimental data. The overall result demonstrates the validity of the above mentioned calibration procedure in a wide range of incident ion energies and masses.

  18. Calibrating the CsI(Tl) detectors of the GARFIELD apparatus

    Science.gov (United States)

    Abbondanno, U.; Bruno, M.; Casini, G.; Cavaletti, R.; Cavallaro, Sl.; Chiari, M.; D'Agostino, M.; Gramegna, F.; Lanchais, A.; Margagliotti, G. V.; Mastinu, P. F.; Milazzo, P. M.; Moroni, A.; Nannini, A.; Ordine, A.; Vannini, G.; Vannucci, L.

    2002-08-01

    The energy and charge dependence of the light output of the CsI(Tl) detectors of the GARFIELD apparatus has been investigated for heavy ions with 5⩽ Z⩽16 in the energy range from 2.2 to 8.3 A MeV . The results have been compared to an analytical expression successfully used in previous calibration procedures at higher energies, and a rather good agreement was obtained between measured and calculated quantities. The resulting parameter set was successfully applied to another set of experimental data. The overall result demonstrates the validity of the above mentioned calibration procedure in a wide range of incident ion energies and masses.

  19. Calibrating the CsI(Tl) detectors of the GARFIELD apparatus

    CERN Document Server

    Abbondanno, U; Casini, G; Cavaletti, R; Cavallaro, S; Chiari, M; D'Agostino, M; Gramegna, F; Lanchais, A; Margagliotti, G V; Mastinu, P F; Milazzo, P M; Moroni, A; Nannini, A; Ordine, A; Vannini, G; Vannucci, L

    2002-01-01

    The energy and charge dependence of the light output of the CsI(Tl) detectors of the GARFIELD apparatus has been investigated for heavy ions with 5<=Z<=16 in the energy range from 2.2 to 8.3 A MeV. The results have been compared to an analytical expression successfully used in previous calibration procedures at higher energies, and a rather good agreement was obtained between measured and calculated quantities. The resulting parameter set was successfully applied to another set of experimental data. The overall result demonstrates the validity of the above mentioned calibration procedure in a wide range of incident ion energies and masses.

  20. Radiation Hardness of 30 cm Long CsI(Tl) Crystals

    CERN Document Server

    Longo, Savino

    2016-01-01

    Measurements of the degradation in performance of 30 cm long CsI(Tl) scintillation crystals exposed to 1 MeV photon doses of 2, 10, 35, 100 and 1000 Gy are presented. The light yield, light yield longitudinal non-uniformity, scintillation decay times, energy resolution and timing resolution of a set of spare crystals from the BABAR and Belle experiments are studied as a function of these doses. In addition, a model that describes the plateau observed in the light output loss as a function of dose in terms of increase in concentrations of absorption centres with irradiation is presented.

  1. Nondestructive method for quantifying thallium dopant concentrations in CsI:Tl crystals.

    Science.gov (United States)

    Miller, Stuart R; Ovechkina, Elena E; Bennett, Paul; Brecher, Charles

    2013-12-01

    We report a quantitative method for using X-ray fluorescence (XRF) to nondestructively measure the true content of Tl dopant in CsI:Tl scintillator crystals. The instrument is the handheld LeadTracer™, originally developed at RMD Instruments for measuring Pb concentration in electronic components. We describe both the measurement technique and specific findings on how changes in crystal size and growth parameters affect Tl concentration. This method is also applicable to numerous other activator ions important to scintillators, such as Ce(3+) and Eu(2+). © 2013 Elsevier Ltd. All rights reserved.

  2. Radiation hardness of 30 cm long CsI(Tl) crystals

    Science.gov (United States)

    Longo, S.; Roney, J. M.

    2016-08-01

    Measurements of the degradation in performance of 30 cm long CsI(Tl) scintillation crystals exposed to 1 MeV photon doses of 2, 10, 35, 100 and 1000 Gy are presented. The light yield, light yield longitudinal non-uniformity, scintillation decay times, energy resolution and timing resolution of a set of spare crystals from the BABAR and Belle experiments are studied as a function of these doses. In addition, a model that describes the plateau observed in the light output loss as a function of dose in terms of increase in concentrations of absorption centres with irradiation is presented.

  3. Particle identification method in the CsI(Tl) scintillator used for the CHIMERA 4{pi} detector

    Energy Technology Data Exchange (ETDEWEB)

    Alderighi, M.; Anzalone, A.; Basssini, R.; Berceanu, I.; Blicharska, J.; Boiano, C.; Borderie, B.; Bougault, R.; Bruno, M.; Cali, C.; Cardella, G. E-mail: cardella@ct.infn.it; Cavallaro, Sl.; D' Agostino, M.; D' Andrea, M.; Dayras, R.; De Filippo, E.; Fichera, F.; Geraci, E.; Giustolisi, F.; Grzeszczuk, A.; Guardone, N.; Guazzoni, P.; Guinet, D.; Iacono-Manno, C.M.; Kowalski, S.; La Guidara, E.; Lanchais, A.L.; Lanzalone, G.; Lanzano, G.; Le Neindre, N.; Li, S.; Maiolino, C.; Majka, Z.; Manfredi, G.; Nicotra, D.; Paduszynski, T.; Pagano, A.; Papa, M.; Petrovici, C.M.; Piasecki, E.; Pirrone, S.; Politi, G.; Pop, A.; Porto, F.; Rivet, M.F.; Rosato, E.; Sacca, G.; Sechi, G.; Simion, V.; Sperduto, M.L.; Steckmeyer, J.C.; Trifiro, A.; Trimarchi, M.; Urso, S.; Vannini, G.; Vigilante, M.; Wilczynski, J.; Wu, H.; Xiao, Z.; Zetta, L.; Zipper, W

    2002-08-21

    The charged particle identification obtained by the analysis of signals coming from the CsI(Tl) detectors of the CHIMERA 4{pi} heavy-ion detector is presented. A simple double-gate integration method, with the use of the cyclotron radiofrequency as reference time, results in low thresholds for isotopic particle identification. The dependence of the identification quality on the gate generation timing is discussed. Isotopic identification of light ions up to Beryllium is clearly seen. For the first time also the identification of Z=5 particles is observed. The identification of neutrons interacting with CsI(Tl) by (n,{alpha}) and (n,{gamma}) reactions is also discussed.

  4. Particle identification method in the CsI(Tl) scintillator used for the CHIMERA 4 pi detector

    CERN Document Server

    Alderighi, M; Basssini, R; Berceanu, I; Blicharska, J; Boiano, C; Borderie, B; Bougault, R; Bruno, M; Cali, C; Cardella, G; Cavallaro, S; D'Agostino, M; D'andrea, M; Dayras, R; De Filippo, E; Fichera, F; Geraci, E; Giustolisi, F; Grzeszczuk, A; Guardone, N; Guazzoni, P; Guinet, D; Iacono-Manno, M; Kowalski, S; La Guidara, E; Lanchais, A L; Lanzalone, G; Lanzanò, G; Le Neindre, N; Li, S; Maiolino, C; Majka, Z; Manfredi, G; Nicotra, D; Paduszynski, T; Pagano, A; Papa, M; Petrovici, C M; Piasecki, E; Pirrone, S; Politi, G; Pop, A; Porto, F; Rivet, M F; Rosato, E; Sacca, G; Sechi, G; Simion, V; Sperduto, M L; Steckmeyer, J C; Trifiró, A; Trimarchi, M; Urso, S; Vannini, G; Vigilante, M; Wilczynski, J; Wu, H; Xiao, Z; Zetta, L; Zipper, W

    2002-01-01

    The charged particle identification obtained by the analysis of signals coming from the CsI(Tl) detectors of the CHIMERA 4 pi heavy-ion detector is presented. A simple double-gate integration method, with the use of the cyclotron radiofrequency as reference time, results in low thresholds for isotopic particle identification. The dependence of the identification quality on the gate generation timing is discussed. Isotopic identification of light ions up to Beryllium is clearly seen. For the first time also the identification of Z=5 particles is observed. The identification of neutrons interacting with CsI(Tl) by (n,alpha) and (n,gamma) reactions is also discussed.

  5. CsI:Tl scintillator separated by Si grid partition wall

    Science.gov (United States)

    Tabata, Kento; Nishizawa, Junichi; Koike, Akihumi; Aoki, Toru

    2016-09-01

    The spatial resolution of scintillator type imaging detector is not so high because diffusion of luminescence in the scintillator. As a countermeasure, the silicon substrate was processed to make a small grid by MEMS technique for optical separation of scintillator. The silicon grid wall can completely obtain optical-separation for visible light as a result of X-ray scintillation. Moreover, we can get large-size silicon wafers up to diameter of 30cm with high precision semiconductor process. In this paper, the purpose is to fill a scintillator material such as CsI:Tl, inside of the grid substrate. Because the aspect ratio of the grid is large (90μm x 90μm with 800μm depth), it is not easy to fill scintillator inside the grid. Moreover, it is necessary to ensure uniformity, intention of light emission. In this study, the CsI:Tl was filled inside of the grid by resistive heated evaporation method. We evaluated by X-ray luminescence and test chart.

  6. A systematic study of radiation damage to large crystals of CsI(Tl) for the BaBar detector

    Energy Technology Data Exchange (ETDEWEB)

    Hryn' ova, T

    2003-10-28

    We describe a novel apparatus that allows simultaneous exposure of large CsI(Tl) crystals to radiation and precise measurement of the longitudinal changes in light yield of the crystals. We present herein the first results from this device for exposures up to 6 kRad.

  7. New PDP Phosphors

    Institute of Scientific and Technical Information of China (English)

    Zhao Baohua

    2002-01-01

    @@ A project on the development of phosphors for color plasma display panels (PDP), conducted by researchers from the Changchun Institute of Applied Chemistry (CIAC), CAS, has recently passed the evaluation in Changchun, capital of northeast China's Jilin Province. The evaluation panel concluded that the PDP was advanced in technique and especially the red phosphor is on a par with the similar products manufactured by Japan in 2001 and shows better secondary characteristics.

  8. Color stable manganese-doped phosphors

    Science.gov (United States)

    Lyons, Robert Joseph [Burnt Hills, NY; Setlur, Anant Achyut [Niskayuna, NY; Deshpande, Anirudha Rajendra [Twinsburg, OH; Grigorov, Ljudmil Slavchev [Sofia, BG

    2012-08-28

    A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

  9. Color stable manganese-doped phosphors

    Science.gov (United States)

    Lyons, Robert Joseph; Setlur, Anant Achyut; Deshpande, Anirundha Rajendra; Grigorov, Ljudmil Slavchev

    2014-04-29

    A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor material radiationally coupled to the light source. The phosphor material includes a color-stable Mn.sup.+4 doped phosphor prepared by a process including providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof.

  10. PIXE characterization of CsI(Tl) scintillators used for particle detection in nuclear reactions

    Science.gov (United States)

    Grassi, N.; Casini, G.; Frosini, M.; Tobia, G.; Marchi, T.

    2008-05-01

    Particle-Induced X-ray Emission has been used to measure Thallium concentration in several CsI(Tl) scintillators from different manufacturers, in order to check their nominal declared values and correlate their behaviour with actual Tl concentration. Indeed, both Tl doping level and its uniformity affect light emission of these detectors, which are largely employed in nuclear physics experiments. In some of the examined crystals Tl concentration values from PIXE measurements came out to be quite different from those declared. This allowed us to explain apparent anomalies in the trend of their α/γ-induced light yield ratio versus Tl content. In some cases, the presence of unexpected contaminants was also pointed out.

  11. PIXE characterization of CsI(Tl) scintillators used for particle detection in nuclear reactions

    Energy Technology Data Exchange (ETDEWEB)

    Grassi, N. [Istituto Nazionale di Fisica Nucleare-Sezione di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino (Firenze) (Italy); Dipartimento di Fisica dell' Universita di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino (Firenze) (Italy)], E-mail: grassi@fi.infn.it; Casini, G. [Istituto Nazionale di Fisica Nucleare-Sezione di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino (Firenze) (Italy); Frosini, M. [Dipartimento di Fisica dell' Universita di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino (Firenze) (Italy); Tobia, G. [Istituto Nazionale di Fisica Nucleare-Sezione di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino (Firenze) (Italy); Marchi, T. [Dipartimento di Fisica dell' Universita di Bologna, Via Irnerio 46, 40126 Bologna (Italy)

    2008-05-15

    Particle-Induced X-ray Emission has been used to measure Thallium concentration in several CsI(Tl) scintillators from different manufacturers, in order to check their nominal declared values and correlate their behaviour with actual Tl concentration. Indeed, both Tl doping level and its uniformity affect light emission of these detectors, which are largely employed in nuclear physics experiments. In some of the examined crystals Tl concentration values from PIXE measurements came out to be quite different from those declared. This allowed us to explain apparent anomalies in the trend of their {alpha}/{gamma}-induced light yield ratio versus Tl content. In some cases, the presence of unexpected contaminants was also pointed out.

  12. Investigation of the screen optics of thick CsI(Tl) detectors

    Science.gov (United States)

    Howansky, Adrian; Peng, Boyu; Suzuki, Katsuhiko; Yamashita, Masanori; Lubinsky, A. R.; Zhao, Wei

    2015-03-01

    Flat panel imagers (FPI) are becoming the dominant detector technology for digital x-ray imaging. In indirect FPI, the scintillator that provides the highest image quality is Thallium (Tl) doped Cesium Iodide (CsI) with columnar structure. The maximum CsI thickness used in existing FPI is ~600 microns, due to concerns of loss in spatial resolution and light output with further increase in thickness. The goal of the present work is to investigate the screen-optics for CsI with thicknesses much larger than that used in existing FPI, so that the knowledge can be used to improve imaging performance in dose sensitive and higher energy applications, such as cone-beam CT (CBCT). Columnar CsI(Tl) scintillators up to 1 mm in thickness with different screen-optical design were investigated experimentally. Pulse height spectra (PHS) were measured to determine the Swank factor at x-ray energies between 25 and 75 keV, and to derive depth-dependent light escape efficiency i.e. gain. Detector presampling MTF, NPS and DQE were measured using a high-resolution CMOS optical sensor. Optical Monte Carlo simulation was performed to estimate optical parameters for each screen design and derive depth-dependent gain and MTF, from which overall MTF and DQE were calculated and compared with measured results. The depth-dependent imaging performance parameters were then used in a cascaded linear system model (CLSM) to investigate detector performance under screen- and sensor-side irradiation conditions. The methodology developed for understanding the optics of thick CsI(Tl) will lead to detector optimization in CBCT.

  13. Modeling of reflection-type laser-driven white lighting considering phosphor particles and surface topography.

    Science.gov (United States)

    Lee, Dong-Ho; Joo, Jae-Young; Lee, Sun-Kyu

    2015-07-27

    This paper presents a model of blue laser diode (LD)-based white lighting coupled with a yellow YAG phosphor, for use in the proper design and fabrication of phosphor in automotive headlamps. First, the sample consisted of an LD, collecting lens, and phosphor was prepared that matches the model. The light distribution of the LD and the phosphor were modeled to investigate an effect of the surface topography and phosphor particle properties on the laser-driven white lighting systems by using the commercially available optical design software. Based on the proposed model, the integral spectrum distribution and the color coordinates were discussed.

  14. Timing characteristics of Ce doped Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12} single crystals in comparison with CsI(Tl) scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, M.; Singh, A.K.; Singh, S.G.; Sen, S.; Gadkari, S.C. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India); Desai, V.V.; Nayak, B.K. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India)

    2015-10-15

    Single crystals of Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:Ce with B codopants were successfully grown using the Czochralski technique. The timing characteristics of the crystal was measured by coupling the crystal to photomultiplier tubes (PMT) or silicon photodiodes [Si(PIN)]. The two prompt γ-rays emitted in a cascade from {sup 60}Co or {sup 22}Na source were detected in coincidence using Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:Ce,B crystal detectors and a BaF{sub 2} detector. The time resolution of these crystals are observed to be better than that measured for CsI:Tl crystal coupled to PMT or Si(PIN) in an identical measurement setup. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Measurement of intrinsic radioactive backgrounds from the 137Cs and U/Th chains in CsI(Tl) crystals

    Science.gov (United States)

    Liu, Shu-Kui; Yue, Qian; Lin, Shin-Ted; Li, Yuan-Jing; Tang, Chang-Jian; Wong Tsz-King, Henry; Xing, Hao-Yang; Yang, Chao-Wen; Zhao, Wei; Zhu, Jing-Jun

    2015-04-01

    The inorganic CsI(Tl) crystal scintillator is a candidate anti-compton detector for the China Dark matter Experiment. Studying the intrinsic radiopurity of the CsI(Tl) crystal is an issue of major importance. The timing, energy and spatial correlations, as well as the capability of pulse shape discrimination provide powerful methods for the measurement of intrinsic radiopurities. The experimental design, detector performance and event-selection algorithms are described. A total of 359×3 kg-days data from three prototypes of CsI(Tl) crystals were taken at China Jinping Underground Laboratory (CJPL), which offers a good shielding environment. The contamination levels of internal isotopes from 137Cs, 232Th and 238U series, as well as the upper bounds of 235U series are reported. Identification of the whole α peaks from U/Th decay chains and derivation of those corresponding quenching factors are achieved. Supported by National Natural Science Foundation of China (11275107, 11175099)

  16. Phosphors and PDP, LED Technology

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Phosphors for PDP has good prospect for the largepotential of PDP industry. LED technology brings new marketto be developed. Developing phosphors for white LED withhigh efficiency and low light attenuation is an urgent work todo. Application of phosphors in color LED is in initial stage.1. Good Prospect of Phosphors for PDPColor PDP is widely used today. Three-prime-colorphosphor excited by VUV is the key material for color PDP.This makes research on three-prime-color phosphor for colorPDP important. Follow...

  17. Radiation damage mechanisms in CsI(Tl) studied by ion beam induced luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Quaranta, Alberto [Dipartimento di Ingegneria dei Materiali e delle Tecnologie Industriali - DIMTI, Universita di Trento, Via Mesiano 77, I-38050 Povo, Trento (Italy); Laboratori Nazionali di Legnaro - INFN, Via dell' Universita 2, I-35020 Legnaro, Padova (Italy)], E-mail: quaranta@ing.unitn.it; Gramegna, Fabiana; Kravchuk, Vladimir [Laboratori Nazionali di Legnaro - INFN, Via dell' Universita 2, I-35020 Legnaro, Padova (Italy); Scian, Carlo [Dipartimento di Ingegneria dei Materiali e delle Tecnologie Industriali - DIMTI, Universita di Trento, Via Mesiano 77, I-38050 Povo, Trento (Italy); Laboratori Nazionali di Legnaro - INFN, Via dell' Universita 2, I-35020 Legnaro, Padova (Italy)

    2008-06-15

    Ion beam induced luminescence (IBIL) has been used to study the kinetics of defect production under ion beam irradiation in CsI(Tl) crystals with different Tl{sup +} concentrations (250, 560, 3250 and 6500 ppm). The crystals have been irradiated with H{sup +} and {sup 4}He{sup +} at 1.8 MeV. Both the scintillator spectra after irradiation and the intensity decrease at different wavelengths as a function of the fluence have been measured. The emission bands shift to higher wavelengths after irradiation, and the light decrease has been interpolated following a saturation model for the point defect concentration. Crystals with low Tl{sup +} concentrations present the UV emission peak of pure CsI at 300 nm whose intensity during H{sup +} irradiation and reaches a maximum under He{sup +} irradiation. At low Tl{sup +} concentrations the damage rate depends on the ion stopping power, while at higher concentrations it depends on the activator concentration. The results can be interpreted by assuming that the defects affecting the light emission are point defects nearby Tl{sup +} ions.

  18. Energy calibration of CsI(Tl) scintillator in pulse-shape identification technique

    CERN Document Server

    Avdeichikov, V; Golubev, P; Jakobsson, B; Colonna, N

    2003-01-01

    A batch of 16 CsI(Tl) scintillator crystals, supplied by the Bicron Company, has been studied with respect to precise energy calibration in pulse-shape identification technique. The light corresponding to pulse integration within the time interval 1.6-4.5 mu s (long gate) and 0.0-4.5 mu s (extra-long gate) exhibits a power law relation, L(E,Z,A)=a1(Z,A)E sup a sup 2 sup ( sup Z sup , sup A sup ) , for sup 1 sup , sup 2 sup , sup 3 H isotopes in the measured energy range 5-150 MeV. For the time interval 0.0-0.60 mu s (short gate), a significant deviation from the power law relation is observed, for energy greater than approx 30 MeV. The character of the a2(p)-a2(d) and a2(p)-a2(t) correlations for protons, deuterons and tritons, reveals 3 types of crystals in the batch. These subbatches differ in the value of the extracted parameter a2 for protons, and in the value of the spread of a2 for deuterons and tritons. This may be explained by the difference in the energy dependence of the fast decay time component an...

  19. Influence of processing parameters on long lasting hybrid phosphor for LED applications

    Science.gov (United States)

    Jain, Abhilasha; Kumar, Ashwini; Dhoble, S. J.; Peshwe, D. R.

    2016-05-01

    Rare earth activated hybrid phosphors have made significant progress in terms of better light output, color properties and potential for long life. All these features coupled with low cost production and reduced maintenance have offered phosphor converted LEDs for diverse optoelectronic applications including signal lighting in advanced aviation. The present paper explores the effect of various processing parameters on luminescent hybrid phosphors fabricated through combustion synthesis.

  20. High Extraction Phosphors for Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Summers, Chris [Phosphortech Corporation, Kennesaw, GA (United States); Menkara, Hisham [Phosphortech Corporation, Kennesaw, GA (United States); Wagner, Brent [Phosphortech Corporation, Kennesaw, GA (United States)

    2011-09-01

    systems, the encapsulation of ZnSeS particle phosphors and ZnSeS screens with Al2O3 and TiO2 using ALD was shown to improve the stability by >8X and also increased the luminescence efficiency due to improved surface passivation and optical coupling. A large-volume fluidized bed ALD system was designed that can be adapted to a commercial ALD or vapor deposition system. Throughout the program, optical simulations were developed to evaluate and optimize various phosphor mixtures and device configurations. For example, to define the scattering properties of nanophosphors in an LED device or in a stand-off screen geometry. Also this work significantly promoted and assisted in the implementation of realistic phosphor material models into commercial modeling programs.

  1. Automatic procedure for mass and charge identification of light isotopes detected in CsI(Tl) of the GARFIELD apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Morelli, L.; Bruno, M.; Baiocco, G. [Dipartimento di Fisica dell' Universita and INFN, Bologna (Italy); Bardelli, L.; Barlini, S.; Bini, M.; Casini, G. [Dipartimento di Fisica dell' Universita and INFN, Firenze (Italy); D' Agostino, M., E-mail: dagostino@bo.infn.i [Dipartimento di Fisica dell' Universita and INFN, Bologna (Italy); Degerlier, M.; Gramegna, F. [INFN, Laboratori Nazionali di Legnaro (Italy); Kravchuk, V.L. [Dipartimento di Fisica dell' Universita and INFN, Bologna (Italy); INFN, Laboratori Nazionali di Legnaro (Italy); Marchi, T. [Dipartimento di Fisica dell' Universita, Padova, ItalyNUCL-EX Collaboration (Italy); INFN, Laboratori Nazionali di Legnaro (Italy); Pasquali, G.; Poggi, G. [Dipartimento di Fisica dell' Universita and INFN, Firenze (Italy)

    2010-08-21

    Mass and charge identification of light charged particles detected with the 180 CsI(Tl) detectors of the GARFIELD apparatus is presented. A 'tracking' method to automatically sample the Z and A ridges of 'Fast-Slow' histograms is developed. An empirical analytic identification function is used to fit correlations between Fast and Slow, in order to determine, event by event, the atomic and mass numbers of the detected charged reaction products. A summary of the advantages of the proposed method with respect to 'hand-based' procedures is reported.

  2. Automatic procedure for mass and charge identification of light isotopes detected in CsI(Tl) of the GARFIELD apparatus

    Science.gov (United States)

    Morelli, L.; Bruno, M.; Baiocco, G.; Bardelli, L.; Barlini, S.; Bini, M.; Casini, G.; D'Agostino, M.; Degerlier, M.; Gramegna, F.; Kravchuk, V. L.; Marchi, T.; Pasquali, G.; Poggi, G.

    2010-08-01

    Mass and charge identification of light charged particles detected with the 180 CsI(Tl) detectors of the GARFIELD apparatus is presented. A "tracking" method to automatically sample the Z and A ridges of "Fast-Slow" histograms is developed. An empirical analytic identification function is used to fit correlations between Fast and Slow, in order to determine, event by event, the atomic and mass numbers of the detected charged reaction products. A summary of the advantages of the proposed method with respect to "hand-based" procedures is reported.

  3. Design and construction of a multi-layer CsI(Tl) telescope for high-energy reaction studies

    CERN Document Server

    Yan, D; Yue, K; Wang, S T; Zhang, X H; Yu, Y H; Chen, J L; Tang, S W; Fang, F; Zhou, Y; Sun, Y; Wang, Z M; Sun, Y Z

    2015-01-01

    A prototype of a new CsI(Tl) telescope, which will be used in the reaction studies of light isotopes with energy of several hundred AMeV, has been constructed and tested at the Institute of Modern Physics, Chinese Academy of Sciences. The telescope has a multi-layer structure and the range information will be obtained to improve the particle identification performance. This prototype has seven layers of different thickness. A 5.0% (FWHM) energy resolution has been extracted for one of the layers in a beam test experiment. Obvious improvement for the identification of $^{14}$O and $^{15}$O isotopes was achieved by using the range information.

  4. Design and construction of a multi-layer CsI(Tl) telescope for high-energy reaction studies

    Science.gov (United States)

    Yan, D.; Sun, Z. Y.; Yue, K.; Wang, S. T.; Zhang, X. H.; Yu, Y. H.; Chen, J. L.; Tang, S. W.; Fang, F.; Zhou, Y.; Sun, Y.; Wang, Z. M.; Sun, Y. Z.

    2017-01-01

    A prototype of a new CsI(Tl) telescope, which will be used in the reaction studies of light isotopes with energy of several hundred AMeV, was constructed and tested at the Institute of Modern Physics, Chinese Academy of Sciences. The telescope has a multi-layer structure, and the range information was obtained to improve the particle identification performance. This prototype has seven layers of different thickness. An energy resolution of 5.0% (FWHM) was obtained for one of the layers in a beam test experiment. Positive improvement for the identification of 14O and 15O isotopes was achieved using the range information.

  5. Manufacture and photoluminescent properties of molybdate phosphors

    Science.gov (United States)

    Lee, Kuan-Lin; Hsu, Ting-Chun; Chen, Lung-Chien

    2016-09-01

    In this experiment, the molybdate phosphors were manufactured by using the solid state amorphization with europium, yttrium and molybdenum. To investigate EuxYy(MoO4)3 phosphor characteristics, the europium and yttrium were blended to different of mole ratio. The europium composition can improve phosphors luminous intensity. Phosphors characteristics was measured by X-ray diffraction, SEM and photoluminescence. The X-ray diffraction and SEM displayed phosphors crystal structure. The photoluminescence of molybdate phosphors show that the best excitation spectra emitting position was at 614nm. The molybdate phosphors was excited by UV laser. Therefore, this molybdate phosphors was suitable for UV-LED.

  6. New Processing of LED Phosphors

    OpenAIRE

    Toda, Kenji

    2012-01-01

    In order to synthesize LED phosphor materials, we have applied three novel synthesis techniques, “melt synthesis”, “fluidized bed synthesis” and “vapor-solid hybrid synthesis”, in contrast with the conventional solid state reaction technique. These synthesis techniques are also a general and powerful tool for rapid screening and improvements of new phosphor materials.

  7. New Phosphors for White LEDs

    Institute of Scientific and Technical Information of China (English)

    LIU Ru-Shi

    2004-01-01

    White light-emitting diodes (WLEDs) have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or UV LEDs) and photoluminescence phosphors. GaN-based highly efficient blue InGaN LEDs combined with phosphors can produce white light. These solid-state LED lamps have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability, and long operating lifetime (about 100,000 hours). For the purpose of development of high energy-efficient white light sources, we need to produce highly efficient new phosphors, which can absorb excitation energy from blue or UV LEDs and generate emissions.In this paper, we investigate the development of blue or UV LEDs by the appropriate combination of new phosphors which can lead us to obtain high brightness white light. The criteria of choosing the best phosphors, for blue (380-450 nm) and UV (360-400 nm) LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance light between the light emission from blue LEDs and the yellow YAG:Ce,Gd phosphor is important to obtain white light with high color temperature. The phosphors with high efficiency which can be excited by UV LEDs are important to obtain the white light with high color rendering index.

  8. Contribution to the study of the {sup 31}P, {sup 1}H spin spin coupling constant N. M. R. in three co-ordinated phosphorus compounds. Influence of the bond orientation and of the nature of the substituent around the phosphorus atom; Contribution a l'etude des constantes de couplage {sup 31}P, {sup 1}H en R.M.N. dans les composes organo-phosphores tricoordines. Influence des facteurs geometriques et de la nature des substituants au niveau du phosphore

    Energy Technology Data Exchange (ETDEWEB)

    Robert, J.B. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    In order to investigate the influence of the configuration at the phosphorus atom and the influence of the substituents attached to the phosphorus atom on the J{sub PH} spin spin coupling constant, we have performed the NMR spectrum analysis of some three coordinated organo-phosphorus compounds. The studied coupling constants are {sup 3}J{sub PH} through P-O-C-H and P-C-C-H fragments and {sup 2}J{sub PH} through P-C-H fragment. The results clearly show that on the NMR time scale, in all the studied compounds (1,3,2-dioxaphospholanes, 1,3,2-dioxaphosphorinanes, 3-phospha-cyclopentene and 4-phosphorinanone) there is no inversion of the bonds around phosphorous. This conclusion held also for secondary phosphines. For a given geometry of the bonds joining the P and H atoms, and a given disposition of the bonds around the phosphorus atom, there is only a little influence of the nature of the substituents on the J{sub PH} spin coupling constants. The geometrical dependence of the {sup 3}J{sub PH} cannot be explained by a 'Karplus law'. There is an influence of the bond disposition around phosphorus. In the case of the {sup 2}J{sub P-C-H}, one can plot a curve {sup 2}J{sub P-C-H} = f({alpha}) (0{<=} {alpha} {<=} 180), {alpha} denote the dihedral angle of the two plane defined the first one by the P, C and H atoms, and the second one by the P-C bond together with the three-fold axis of the bond around phosphorus assuming a regular pyramidal arrangement. The function {sup 2}J{sub P-C-H} = f({alpha}) has two maxima, one for {alpha} = 0 degrees and the other for {alpha} = 180 degrees, and also a minimum for {alpha} = 110 degrees. (author) [French] Ce travail consiste en l'analyse par resonance magnetique nucleaire des constantes de couplage phosphore-proton dans des derives organo-phosphores tricoordines dans un double but: examen de la stabilite des liaisons au niveau du phosphore et etude de l'influence de la disposition des liaisons et de la nature de

  9. A Study of the Impact of Radiation Exposure on Uniformity of Large CsI(Tl) Crystals for the BaBar Detector

    Energy Technology Data Exchange (ETDEWEB)

    Hryn' ova, T

    2004-02-23

    We describe an apparatus that allows simultaneous exposure of large CsI(Tl) crystals to radiation and precise measurement of the longitudinal changes in light yield of the crystals. We present herein the results from this device for exposures up to 10 kRad.

  10. Spot phosphor concept applied to the remote phosphor configuration of a white phosphor-converted LED

    Science.gov (United States)

    Acuña, Paula; Correia, António; Ryckaert, Jana; Meuret, Youri; Deconinck, Geert; Hanselaer, Peter

    2016-04-01

    Although the remote phosphor technology outperforms the conformal phosphor technology for mid-power applications, one of the limiting factors is the amount of phosphor required and its impact on the total cost. Besides, an important loss mechanisms in remote phosphor LED technology is the re-absorption of converted light. An obvious solution to this issue is enabling a light path for the converted light, such that further interactions with the phosphor element are avoided. In order to explore such a configuration, a simulation model of a phosphor element is devised and validated based on experimental data and the application of the inverse adding-doubling method. The resulting configuration, denoted as spot concept, along with a long-pass filter is shown to be a potential solution to reduce the phosphor usage. Since the moderate change in the light extraction ratio when applying the spot concept is partly attributed to the losses in the secondary optics needed to narrow the LED beam, the application of the spot concept configuration with a directional light source such as a laser diode could be a powerful combination for the enhancement of the light extraction ratio.

  11. Surface Patterning of Ceramic Phosphor Plate for Light Extraction

    Science.gov (United States)

    Mao, An

    Light-Emitting Diodes (LEDs) are expected to replace traditional lighting sources in the near future due to their energy-efficiency, optical design flexibility and good reliability over traditional lighting sources. III-V nitride blue LEDs with powdered phosphors have been used commercially to get white emission. However, due to scattering losses, thermal issues as well as the surface reactivity with common encapsulants, LEDs fabricated with powdered phosphors have limitations in achieving high luminous efficacy, high chromatic stability and good color-rendering properties. Solid, non-scattering phosphors could avoid many of these limitations, but issues of light extraction and coupling of excitation radiation to the phosphor require development to insure efficient operation. Photonic crystal structures fabricated into or on non-scattering phosphors can be used to address these challenges. In this thesis, a lift-off process with bilayer resist system is developed to create nanopatterns. A photonic crystal structure is fabricated by low cost molecular transfer lithography (MxL) with bi-layer resist system on non-scattering phosphor plate used for white emission to increase the extraction efficiency. In Chapter 1, some basic background concepts which appear frequently in this thesis are introduced. These concepts include the Stokes shift and backscattering phenomenon for powder phosphors as well as non-scattering phosphors. In Chapter 2, a non-scattering single crystal phosphor with a patterned surface is proposed to replace the powdered phosphors used for color converted LEDs. A non-scattering phosphor YAG:Ce ceramic phosphor plate (CPP) patterned with TiO2 photonic crystal structure is selected for convenience to demonstrate the concept. The physical origin of light extraction of the proposed structure is discussed. The simulation principles and results are discussed in this chapter to find the optimized photonic crystal structure for light extraction. In Chapter 3

  12. Mechanisms affecting emission in rare-earth-activated phosphors

    Energy Technology Data Exchange (ETDEWEB)

    TALLANT,DAVID R.; SEAGER,CARLETON H.; SIMPSON,REGINA L.

    2000-05-23

    The relatively poor efficiency of phosphor materials in cathodoluminescence with low accelerating voltages is a major concern in the design of field emission flat panel displays operated below 5 kV. The authors research on rare-earth-activated phosphors indicates that mechanisms involving interactions of excited activators have a significant impact on phosphor efficiency. Persistence measurements in photoluminescence (PL) and cathodoluminescence (CL) show significant deviations from the sequential relaxation model. This model assumes that higher excited manifolds in an activator de-excite primarily by phonon-mediated sequential relaxation to lower energy manifolds in the same activator ion. In addition to sequential relaxation, there appears to be strong coupling between activators, which results in energy transfer interactions. Some of these interactions negatively impact phosphor efficiency by nonradiatively de-exciting activators. Increasing activator concentration enhances these interactions. The net effect is a significant degradation in phosphor efficiency at useful activator concentrations, which is exaggerated when low-energy electron beams are used to excite the emission.

  13. Neutron calibration facility with an Am-Be source for pulse shape discrimination measurement of CsI(Tl) crystals

    CERN Document Server

    Lee, H S; Choi, J H; Choi, S; Hahn, I S; Jeon, E J; Joo, H W; Kang, W G; Kim, G B; Kim, H J; Kim, K W; Kim, S C; Kim, S K; Kim, Y D; Kim, Y H; Lee, J H; Lee, J K; Leonard, D S; Li, J; Myung, S S; Olsen, S L; So, J H

    2014-01-01

    We constructed a neutron calibration facility based on a 300-mCi Am-Be source in conjunction with a search for weakly interacting massive particle candidates for dark matter. The facility is used to study the response of CsI(Tl) crystals to nuclear recoils induced by neutrons from the Am-Be source and comparing them with the response to electron recoils produced by Compton scattering of 662-keV $\\gamma$-rays from a $^{137}$Cs source. The measured results on pulse shape discrimination (PSD) between nuclear- and electron-recoil events are quantified in terms of quality factors. A comparison with similar result from a neutron reactor demonstrate the feasibility of performing calibrations of PSD measurements using neutrons from a Am-Be source.

  14. Laser-activated remote phosphor conversion with ceramic phosphors

    Science.gov (United States)

    Lenef, Alan; Kelso, John; Tchoul, Maxim; Mehl, Oliver; Sorg, Jörg; Zheng, Y.

    2014-09-01

    Direct laser activation of a remote phosphor, or LARP, is a highly effective approach for producing very high luminance solid-state light sources. Such sources have much smaller étendue than LEDs of similar power, thereby greatly increasing system luminous fluxes in projection and display applications. While several commercial products now employ LARP technology, most current configurations employ phosphor powders in a silicone matrix deposited on rotating wheels. These provide a low excitation duty cycle that helps limit quenching and thermal overload. These systems already operate close to maximum achievable pump powers and intensities. To further increase power scaling and eliminate mechanical parts to achieve smaller footprints, OSRAM has been developing static LARP systems based on high-thermal conductivity monolithic ceramic phosphors. OSRAM has recently introduced a static LARP product using ceramic phosphor for endoscopy and also demonstrated a LARP concept for automotive forward lighting1. We first discuss the basic LARP concept with ceramic phosphors, showing how their improved thermal conductivity can achieve both high luminous fluxes and luminance in a static configuration. Secondly, we show the importance of scattering and low optical losses to achieving high overall efficiency and light extraction. This is shown through experimental results and radiation transport calculations. Finally, we discuss some of the fundamental factors which limit the ultimate luminance achievable with ceramic converted LARP, including optical pumping effects and thermal quenching.

  15. Surface Modification of Long Afterglow Phosphors by Different Saturated Fatty Acid Based Al -Zr Coupling Agent%不同碳链长度饱和脂肪酸基铝锆偶联剂对夜光粉的表面修饰

    Institute of Scientific and Technical Information of China (English)

    郭斌; 徐杰; 唐皞; 曹绪芝; 李本刚; 郭福全; 高勇

    2011-01-01

    为扩展夜光粉的应用领域,以不同碳链长度的饱和脂肪酸(辛酸、月桂酸、硬脂酸)为有机功能配体制备了3种新型铝锆偶联剂(CA),并对夜光粉( SrMgAl4O8∶Eu2+、Dy3+)进行了表面修饰,用ATR -FTIR和接触角表征了样品表面性质,用水中pH和电导率的变化测定其耐水性,用TG表征了不同CA、原样及改性样的热失质量行为,并以此首次提出计算不同CA在夜光粉表面包覆量的方法及其结构模型.结果表明:随着CA中饱和脂肪酸碳链长度的增加(由辛酸到硬脂酸),夜光粉表面包覆量由13.41%降为6.53%,月桂酸基铝锆CA改性样具有最佳的耐水性和相容性.%To expand the application of the long afterglow phosphors, three saturated fatty acid ( capryl-ic, lauric and stearic acid) based Al -Zr coupling agent( CA) were synthesized, which were used to modify the phosphors SrMgAl4O8 ;Eu2+ , Dy3+. ATR - FTIR and contact angle were used to characterize their surface behavior. The pH value and electric conductivity in water were determined to evaluate their water resistance. TG Analysis was performed to characterize the thermal weight loss behaviors of CA, oringinal and modified samples. And with the TG data, the method to calculate the coated amount on phosphors and their structure model were proposed. Results showed that the coated amount on phosphors decreased from 13. 41% to 6. 53% with the increasing of carbon chain length of fatty acid. The better water resistant and compatibility with organic resin can be obtained by lauric based Al - Zr CA.

  16. Studies of scintillation light nonproportionality of ZnSe(Te), CsI(Tl) and YAP(Ce) crystals using heavy ions

    CERN Document Server

    Klamra, W; Kapusta, M; Kérek, A; Moszynski, M; Norlin, L O; Novák, D; Possnert, G

    2002-01-01

    The scintillation light yield for ZnSe(Te), CsI(Tl) and YAP(Ce) crystals have been studied with alpha particles, sup 1 sup 2 C and sup 8 sup 1 Br in the energy region 2.8-42.2 MeV. A nonproportional behavior was observed, mostly pronounced for alpha particles on YAP(Ce). The results are understood in terms of delta-rays effect.

  17. 21 CFR 582.1073 - Phosphoric acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Phosphoric acid. 582.1073 Section 582.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance...

  18. 21 CFR 182.1073 - Phosphoric acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Phosphoric acid. 182.1073 Section 182.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN....1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is...

  19. Phosphors for near UV-Emitting LED's for Efficacious Generation of White Light

    Energy Technology Data Exchange (ETDEWEB)

    McKittrick, Joanna

    2013-09-30

    1) We studied phosphors for near-UV (nUV) LED application as an alternative to blue LEDs currently being used in SSL systems. We have shown that nUV light sources could be very efficient at high current and will have significantly less binning at both the chip and phosphor levels. We identified phosphor blends that could yield 4100K lamps with a CRI of approximately 80 and LPWnUV,opt equal to 179 for the best performing phosphor blend. Considering the fact that the lamps were not optimized for light coupling, the results are quite impressive. The main bottleneck is an optimum blue phosphor with a peak near 440 nm with a full width half maximum of about 25 nm and a quantum efficiency of >95%. Unfortunately, that may be a very difficult task when we want to excite a phosphor at ~400 nm with a very small margin for Stokes shift. Another way is to have all the phosphors in the blend having the excitation peak at 400 nm or slightly shorter wavelength. This could lead to a white light source with no body color and optimum efficacy due to no self-absorption effects by phosphors in the blend. This is even harder than finding an ideal blue phosphor, but not necessarily impossible. 2) With the phosphor blends identified, light sources using nUV LEDs at high current could be designed with comparable efficacy to those using blue LEDs. It will allow us to design light sources with multiple wattages using the same chips and phosphor blends simply by varying the input current. In the case of blue LEDs, this is not currently possible because varying the current will lower the efficacy at high current and alter the color point. With improvement of phosphor blends, control over CRI could improve. Less binning at the chip level and also at the phosphor blend level could reduce the cost of SSL light sources. 3) This study provided a deeper understanding of phosphor characteristics needed for LEDs in general and nUV LEDs in particular. Two students received Ph.D. degrees and three

  20. N.M.R. study of organo-phosphorus compounds: non equivalence of methylenic protons in the {alpha} position of an asymmetric phosphorus atom. Application to study of coupling constants J{sub P,H} and J{sub H,H}; R.M.N. de composes organo-phosphores: non equivalence de protons methyleniques en {alpha} d'un phosphore asymetrique. Application a l'etude des constantes de couplage J{sub P,H} et J{sub H,H}

    Energy Technology Data Exchange (ETDEWEB)

    Albrand, J.P. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    Non-equivalent methylenic protons, with respect to an asymmetric center, have been observed in the n.m.r. spectra of some three- and tetra-coordinated phosphorus compounds. The analysis of these spectra yield the following results: in the studied secondary phosphines, the inversion rate at the phosphorus atom is slow on the n.m.r. time scale; the geminal coupling constant, for a free-rotating methylene group attached to a phosphorus atom, is negative; in phosphines the non equivalence of methylenic protons reveals two {sup 2}J{sub P-C-H} coupling constants which differ by about 5 Hz. This result is in agreement with previous studies on cyclic phosphines. In phosphine oxides, the {sup 2}J{sub P-C-H} values are negative. The {sup 3}J{sub H-P-C-H} coupling constant is positive in both phosphines and phosphine oxides. In phosphines, the non-equivalent methylenic protons exhibit two nearly equal values for this coupling constant. (author) [French] La non-equivalence de protons methyleniques observee dans quelques composes phosphores tricoordines et tetracoordines a apporte les resultats suivants, concernant la stereochimie et les constantes de couplage dans ces composes: dans les phosphines secondaires, la structure pyramidale des liaisons issues du phosphore est fixe a l'echelle de temps de mesure de la R.M.N.; la constante de couplage {sup 2}J{sub H-C-H}, pour un methylene en libre rotation en {alpha} d'un atome de phosphore, est negative; dans les phosphines etudiees, la non-equivalence. observee pour les protons methyleniques s'accompagne d'une difference importante (5 Hz) entre les deux constantes de couplage {sup 2}J{sub P-C-H} determinees par l'analyse; ce resultat est en accord avec la stereospecificite deja observee pour ce couplage dans les phosphines cycliques. Les valeurs observees pour {sup 2}J{sub P-C-H} dans les oxydes de phosphines sont negatives. Les valeurs de la constante de couplage {sup 3}J{sub H-P-C-H}, dans les phosphines

  1. A compact, discrete CsI(Tl) scintillator/Si photodiode gamma camera for breast cancer imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Gregory J. [Univ. of California, Berkeley, CA (United States)

    2000-01-01

    Recent clinical evaluations of scintimammography (radionuclide breast imaging) are promising and suggest that this modality may prove a valuable complement to X-ray mammography and traditional breast cancer detection and diagnosis techniques. Scintimammography, however, typically has difficulty revealing tumors that are less than 1 cm in diameter, are located in the medial part of the breast, or are located in the axillary nodes. These shortcomings may in part be due to the use of large, conventional Anger cameras not optimized for breast imaging. In this thesis I present compact single photon camera technology designed specifically for scintimammography which strives to alleviate some of these limitations by allowing better and closer access to sites of possible breast tumors. Specific applications are outlined. The design is modular, thus a camera of the desired size and geometry can be constructed from an array (or arrays) of individual modules and a parallel hole lead collimator for directional information. Each module consists of: (1) an array of 64 discrete, optically-isolated CsI(Tl) scintillator crystals 3 x 3 x 5 mm3 in size, (2) an array of 64 low-noise Si PIN photodiodes matched 1-to-1 to the scintillator crystals, (3) an application-specific integrated circuit (ASIC) that amplifies the 64 photodiode signals and selects the signal with the largest amplitude, and (4) connectors and hardware for interfacing the module with a motherboard, thereby allowing straightforward computer control of all individual modules within a camera.

  2. Suppression of afterglow in CsI:Tl by codoping with Eu{sup 2+}-I: Experimental

    Energy Technology Data Exchange (ETDEWEB)

    Brecher, C. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States)]. E-mail: cbrecher@rmdinc.com; Lempicki, A. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States); Miller, S.R. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States); Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Glodo, J. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States); Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Ovechkina, E.E. [Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Gaysinskiy, V. [Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Nagarkar, V.V. [Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Bartram, R.H. [Department of Physics, University of Connecticut, Storrs, CT 06269-3046 (United States)

    2006-03-15

    Although CsI:Tl is the brightest and most efficient scintillator material ever developed, its use in fast imaging applications has been hindered by its strong and persistent afterglow. Recent experiments, however, have demonstrated that much of this afterglow can be suppressed by the addition of Eu{sup 2+} to the CsI host lattice. The magnitude of the effect depends strongly on the duration of the pulse of ionizing radiation that excites the scintillation, but is virtually independent of the intensity of that excitation pulse. The codoping also brings about a measurable red shift in the Tl{sup +} emission, suggesting some degree of spatial correlation between the luminophor and the modifying additive. The observations indicate that the Eu{sup 2+} ion exerts its influence not by a quenching process, but rather by introducing a set of electron traps that fundamentally alter the decay kinetics. This is confirmed by the appearance of new glow peaks in the thermoluminescence traces of the codoped material. A consistent mathematical model has been developed to describe the phenomenon, to be discussed in detail in the accompanying paper.

  3. A compact, discrete CsI(Tl) scintillator/Si photodiode gamma camera for breast cancer imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Gregory J.

    2000-12-01

    Recent clinical evaluations of scintimammography (radionuclide breast imaging) are promising and suggest that this modality may prove a valuable complement to X-ray mammography and traditional breast cancer detection and diagnosis techniques. Scintimammography, however, typically has difficulty revealing tumors that are less than 1 cm in diameter, are located in the medial part of the breast, or are located in the axillary nodes. These shortcomings may in part be due to the use of large, conventional Anger cameras not optimized for breast imaging. In this thesis I present compact single photon camera technology designed specifically for scintimammography which strives to alleviate some of these limitations by allowing better and closer access to sites of possible breast tumors. Specific applications are outlined. The design is modular, thus a camera of the desired size and geometry can be constructed from an array (or arrays) of individual modules and a parallel hole lead collimator for directional information. Each module consists of: (1) an array of 64 discrete, optically-isolated CsI(Tl) scintillator crystals 3 x 3 x 5 mm{sup 3} in size, (2) an array of 64 low-noise Si PIN photodiodes matched 1-to-1 to the scintillator crystals, (3) an application-specific integrated circuit (ASIC) that amplifies the 64 photodiode signals and selects the signal with the largest amplitude, and (4) connectors and hardware for interfacing the module with a motherboard, thereby allowing straightforward computer control of all individual modules within a camera.

  4. Particle gamma correlations in {sup 12}C measured with the CsI(Tl) based detector array CHIMERA

    Energy Technology Data Exchange (ETDEWEB)

    Cardella, G., E-mail: cardella@ct.infn.it [INFN - Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Acosta, L. [INFN - Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Amorini, F. [INFN - Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Auditore, L. [INFN Gruppo collegato di Messina and Dip. di Fisica e Scienze della Terra, Università di Messina (Italy); Berceanu, I. [Institute for Physics and Nuclear Engineering, Bucharest (Romania); Castoldi, A. [INFN Sezione di Milano e Politecnico Milano (Italy); De Filippo, E. [INFN - Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Dell' Aquila, D. [Dipartimento di scienze Fisiche, Università Federico II and INFN Sezione di Napoli (Italy); Francalanza, L. [INFN - Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dip. di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); Gnoffo, B. [INFN - Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Guazzoni, C. [INFN Sezione di Milano e Politecnico Milano (Italy); Lanzalone, G. [INFN - Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Facoltà di Ingegneria e Architettura, Università Kore, Enna (Italy); Lombardo, I. [Dipartimento di scienze Fisiche, Università Federico II and INFN Sezione di Napoli (Italy); Minniti, T.; Morgana, E.; Norella, S. [INFN Gruppo collegato di Messina and Dip. di Fisica e Scienze della Terra, Università di Messina (Italy); Pagano, A. [INFN - Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Pagano, E.V. [INFN - Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dip. di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); Papa, M.; Pirrone, S. [INFN - Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); and others

    2015-11-01

    The gamma decay of the first excited 4.44 MeV 2+level of {sup 12}C, populated by inelastic scattering of proton and {sup 16}O beams at various energies was studied in order to test γ-ray detection efficiency and the quality of angular distribution information given by the CsI(Tl) detectors of the 4π CHIMERA array. The γ-decay was measured in coincidence with ejectile scattered particles in an approximately 4π geometry allowing to extract the angular distribution in the reference frame of recoiling {sup 12}C target. The typical sin{sup 2} (2θ) behavior of angular distribution was observed in the case of {sup 16}O beam. Besides that, for the proton beam, in order to explain the observed distribution, the addition of an incoherent flat contribution was required. This latter is the effect of proton spin flip events allowing the population of M=±1 magnetic substates, that is not possible in reactions induced by {sup 16}O beam. A comparison with previously collected data, obtained measuring only in and out of plane proton-γ-ray coincidences, confirms the good quality of the angular distribution information given by the apparatus. Possible applications with radioactive beams are outlined.

  5. Radioluminescent nuclear batteries with different phosphor layers

    Science.gov (United States)

    Hong, Liang; Tang, Xiao-Bin; Xu, Zhi-Heng; Liu, Yun-Peng; Chen, Da

    2014-11-01

    A radioluminescent nuclear battery based on the beta radioluminescence of phosphors is presented, and which consists of 147Pm radioisotope, phosphor layers, and GaAs photovoltaic cell. ZnS:Cu and Y2O2S:Eu phosphor layers for various thickness were fabricated. To investigate the effect of phosphor layer parameters on the battery, the electrical properties were measured. Results indicate that the optimal thickness ranges for the ZnS:Cu and Y2O2S:Eu phosphor layers are 12 mg cm-2 to 14 mg cm-2 and 17 mg cm-2 to 21 mg cm-2, respectively. ZnS:Cu phosphor layer exhibits higher fluorescence efficiency compared with the Y2O2S:Eu phosphor layer. Its spectrum properly matches the spectral response of GaAs photovoltaic cell. As a result, the battery with ZnS:Cu phosphor layer indicates higher energy conversion efficiency than that with Y2O2S:Eu phosphor layer. Additionally, the mechanism of the phosphor layer parameters that influence the output performance of the battery is discussed through the Monte Carlo method and transmissivity test.

  6. Luminescence properties of red-emission Mg4 Nb2 O9:Eu3+ phosphor.

    Science.gov (United States)

    Cao, Renping; Cao, Chunyan; Yu, Xiaoguang; Qiu, Jianrong

    2015-03-01

    Red-emitting Mg4 Nb2 O9 :Eu(3+) phosphor is synthesized via a solid-state reaction method in air, and its crystal structure and luminescence are investigated. The phosphor can be excited efficiently by ~ 395 nm light, coupled well with a ~ 395 nm near-ultraviolet chip and emits red light at ~ 613 nm with sharp spectra due to (5) D0  → (7)  F2 transition of the Eu(3+) ion. Mg4 Nb2 O9 :Eu(3+) phosphor sintered at 1350 ºC shows Commission international de I'Eclairage (CIE) chromaticity coordinates of x = 0.6354, y = 0.3592, and is a potential red-emitting phosphor candidate for white light-emitting diodes (W-LEDs) under ~ 395 nm near-ultraviolet LED chip excitation.

  7. LED lamp or bulb with remote phosphor and diffuser configuration with enhanced scattering properties

    Science.gov (United States)

    Tong, Tao; Le Toquin, Ronan; Keller, Bernd; Tarsa, Eric; Youmans, Mark; Lowes, Theodore; Medendorp, Jr., Nicholas W; Van De Ven, Antony; Negley, Gerald

    2014-11-11

    An LED lamp or bulb is disclosed that comprises a light source, a heat sink structure and an optical cavity. The optical cavity comprises a phosphor carrier having a conversions material and arranged over an opening to the cavity. The phosphor carrier comprises a thermally conductive transparent material and is thermally coupled to the heat sink structure. An LED based light source is mounted in the optical cavity remote to the phosphor carrier with light from the light source passing through the phosphor carrier. A diffuser dome is included that is mounted over the optical cavity, with light from the optical cavity passing through the diffuser dome. The properties of the diffuser, such as geometry, scattering properties of the scattering layer, surface roughness or smoothness, and spatial distribution of the scattering layer properties may be used to control various lamp properties such as color uniformity and light intensity distribution as a function of viewing angle.

  8. The Ring Counter (RCo): A high resolution IC Si CsI(Tl) device for heavy ion reaction studies at 10 30 MeV/A

    Science.gov (United States)

    Moroni, A.; Bruno, M.; Bardelli, L.; Barlini, S.; Brambilla, S.; Casini, G.; Cavaletti, R.; Chiari, M.; Cortesi, A.; D'Agostino, M.; De Sanctis, J.; Geraci, E.; Giordano, G.; Giussani, A.; Gramegna, F.; Guiot, B.; Kravchuk, V.; Lanchais, A.; Margagliotti, G. V.; Nannini, A.; Ordine, A.; Piantelli, S.; Vannini, G.; Vannucci, L.

    2006-01-01

    An annular detector (Ring Counter, RCo) is presented, which has been designed and built to detect and identify in mass and charge light charged particles and fragments with very low energy thresholds and high energy resolution. It complements the GARFIELD apparatus, operating at INFN Laboratori Nazionali di Legnaro, to detect the forward emitted products of nuclear heavy ion reactions. It consists of eight sectors of a three-stage telescope, each one formed by an ionization chamber followed by eight strips of a silicon detector and by two CsI(Tl) scintillators. Construction features and performances are described and discussed in details.

  9. Alpha-gamma pulse shape discrimination in CsI:Tl, CsI:Na and BaF sub 2 scintillators

    CERN Document Server

    Dinca, L E; Haas, J; Bom, V R; Eijk, C W E

    2002-01-01

    Some scintillating materials offer the possibility of measuring well separated alpha and gamma scintillation response using a single crystal. Eventually aiming at thermal neutron detection using sup 6 Li or sup 1 sup 0 B admixture, pulse shape discrimination measurements were made on three scintillators: CsI:Tl, CsI:Na and pure BaF sub 2 crystals. A very good alpha/gamma discrimination was obtained using sup 2 sup 2 Na, sup 2 sup 4 sup 1 Am (gamma) and sup 2 sup 4 sup 4 Cm (alpha) radioactive sources.

  10. Evaluation and Comparison of High-Resolution (HR) and High-Light (HL) Phosphors in the Micro-Angiographic Fluoroscope (MAF) using Generalized Linear Systems Analyses (GMTF, GDQE) that include the Effect of Scatter, Magnification and Detector Characteristics.

    Science.gov (United States)

    Gupta, Sandesh K; Jain, Amit; Bednarek, Daniel R; Rudin, Stephen

    2011-01-01

    In this study, we evaluated the imaging characteristics of the high-resolution, high-sensitivity micro-angiographic fluoroscope (MAF) with 35-micron pixel-pitch when used with different commercially-available 300 micron thick phosphors: the high resolution (HR) and high light (HL) from Hamamatsu. The purpose of this evaluation was to see if the HL phosphor with its higher screen efficiency could be replaced with the HR phosphor to achieve improved resolution without an increase in noise resulting from the HR's decreased light-photon yield. We designated the detectors MAF-HR and MAF-HL and compared them with a standard flat panel detector (FPD) (194 micron pixel pitch and 600 micron thick CsI(Tl)). For this comparison, we used the generalized linear-system metrics of GMTF, GNNPS and GDQE which are more realistic measures of total system performance since they include the effect of scattered radiation, focal spot distribution, and geometric un-sharpness. Magnifications (1.05-1.15) and scatter fractions (0.28 and 0.33) characteristic of a standard head phantom were used. The MAF-HR performed significantly better than the MAF-HL at high spatial frequencies. The ratio of GMTF and GDQE of the MAF-HR compared to the MAF-HL at 3(6) cycles/mm was 1.45(2.42) and 1.23(2.89), respectively. Despite significant degradation by inclusion of scatter and object magnification, both MAF-HR and MAF-HL provide superior performance over the FPD at higher spatial frequencies with similar performance up to the FPD's Nyquist frequency of 2.5 cycles/mm. Both substantially higher resolution and improved GDQE can be achieved with the MAF using the HR phosphor instead of the HL phosphor.

  11. Energy-Dependent Scintillation Pulse Shape and Proportionality of Decay Components for CsI:Tl: Modeling with Transport and Rate Equations

    Science.gov (United States)

    Lu, X.; Gridin, S.; Williams, R. T.; Mayhugh, M. R.; Gektin, A.; Syntfeld-Kazuch, A.; Swiderski, L.; Moszynski, M.

    2017-01-01

    Relatively recent experiments on the scintillation response of CsI:Tl have found that there are three main decay times of about 730 ns, 3 μ s , and 16 μ s , i.e., one more principal decay component than had been previously reported; that the pulse shape depends on gamma-ray energy; and that the proportionality curves of each decay component are different, with the energy-dependent light yield of the 16 -μ s component appearing to be anticorrelated with that of the 0.73 -μ s component at room temperature. These observations can be explained by the described model of carrier transport and recombination in a particle track. This model takes into account processes of hot and thermalized carrier diffusion, electric-field transport, trapping, nonlinear quenching, and radiative recombination. With one parameter set, the model reproduces multiple observables of CsI:Tl scintillation response, including the pulse shape with rise and three decay components, its energy dependence, the approximate proportionality, and the main trends in proportionality of different decay components. The model offers insights on the spatial and temporal distributions of carriers and their reactions in the track.

  12. LED lamp incorporating remote phosphor with heat dissipation features

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Tao; Letoquin, Ronan; Keller, Bernd; Tarsa, Eric

    2016-11-22

    An LED lamp or bulb is disclosed that comprises a light source, a heat sink structure and a remote planar phosphor carrier having at least one conversion material. The phosphor carrier can be remote to the light sources and mounted to the heat sink so that heat from the phosphor carrier spreads into the heat sink. The phosphor carrier can comprise a thermally conductive transparent material and a phosphor layer, with an LED based light source mounted to the heat sink such that light from the light source passes through the phosphor carrier. At least some of the LED light is converted by the phosphor carrier, with some lamp embodiments emitting a white light combination of LED and phosphor light. The phosphor arranged according to the present invention can operate at lower temperature to thereby operate at greater phosphor conversion efficiency and with reduced heat related damage to the phosphor.

  13. 46 CFR 151.50-23 - Phosphoric acid.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Phosphoric acid. 151.50-23 Section 151.50-23 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-23 Phosphoric acid. (a) The term phosphoric acid as used in this subpart shall include, in addition to phosphoric acid, aqueous solutions...

  14. 46 CFR 153.558 - Special requirements for phosphoric acid.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Special requirements for phosphoric acid. 153.558... Equipment Special Requirements § 153.558 Special requirements for phosphoric acid. A phosphoric acid... phosphoric acid tanks by the Commandant (CG-522); or (c) Made of a stainless steel that resists corrosion...

  15. Phosphors for solid-state lighting: New systems, deeper understanding

    Science.gov (United States)

    Denault, Kristin Ashley

    +; Li + is red-shifted from the near-UV to blue with compositional changes. The red-shifted photoluminescent quantum yield also increases when Sr is substituted for Ba in these compounds. The end member Ba9Y2Si 6O24:Ce 3+ was identified as an efficient blue-green phosphor with high thermal stability of the luminescence, viable for near-UV LED excitation. An efficient emission, with a quantum yield of ≈60%, covers a broad portion of the visible spectrum leading to the observed blue-green color. The emission of this compound can be red-shifted via the solid-solution Ba9(Y 1-ySc y) 2Si6O24:Ce3+. We then explore the structure-composition relationships and optical properties in newly developed cerium-substituted (Sr,Ba)3(Y,La)(BO3) 3 borate phosphors. Examination of the coordination environment of the Ce3+ active site polyhedra coupled with low-temperature photoluminescence reveals three distinct excitation bands corresponding to Ce3+ located on three distinct crystallographic sites. Comparing the position of these excitation bands with crystal field splitting effects due to changes in polyhedral volumes and distortions suggests an assignment of the three excitation bands. These compounds are efficiently excited by UV light with blue emission, the most efficient compound determined to be Sr3La(BO 3)3:Ce3+,Na + with a quantum yield of 50%. A data-driven discovery of energy materials then reveals the efficient BaM2Si3O10:Eu2+ (M = Sc, Lu) phosphors with UV-to-blue and UV-to-blue-green phosphors. Interestingly, substituting Eu2+ in the Lu3+ containing material produces two emission peaks, at low temperature, as allowed by two substitution sites. The photoluminescence of the Sc3+ compound is robust at high temperature, while the Lu-analogue has a large decrease of its room temperature intensity. The decrease in emission intensity is explained as stemming from charge transfer quenching due to the short distances separating the luminescent centers on the Lu3+ substitution site

  16. Spectrum-dose conversion operator of NaI(Tl) and CsI(Tl) scintillation detectors for air dose rate measurement in contaminated environments.

    Science.gov (United States)

    Tsuda, Shuichi; Saito, Kimiaki

    2017-01-01

    Spectrum-dose conversion operators, the G(E) functions, for common NaI(Tl) scintillation survey meters and CsI(Tl) detectors are obtained for measurements in a semi-infinite plane of contaminated ground field by photon-emitting radionuclides (ground source). The calculated doses at a height of 100 cm from the ground in (137)Cs-contaminated environments by the Monte Carlo simulation technique are compared with those obtained using the G(E) functions by assuming idealized irradiation geometries such as anterior-posterior or isotropic. The simulation reveals that one could overestimate air dose rates in the environment by a maximum of 20-30% for NaI(Tl) detectors and 40-50% for CsI(Tl) detectors depending on photon energy when using the G(E) functions assuming idealized irradiation geometries for ground source measurements. Measurements obtained after the nuclear accident in Fukushima reveal that the doses calculated using a G(E) function for a unidirectional irradiation geometry are 1.17 times higher than those calculated using a G(E) function for the ground source in the case of a CsI(Tl) scintillation detector, which has a rectangular parallelepiped crystal (13 × 13 × 20 mm(3)). However, if a G(E) function is used assuming irradiation to a surface of the detector, the doses agree with those of the ground source within 2%. These results indicate that in contaminated environments, the commonly used scintillation-based detectors overestimate doses within the acceptable limit. In addition, the degree of overestimation depends on the irradiation direction of each detector assumed for developing the G(E) function. With regard to directional dependence of the detectors, reliable air dose rates in the environment can be obtained using the G(E) function determined in unidirectional irradiation geometry, provided that the irradiation surface of the crystal is determined properly. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Phosphate Phosphors for Solid-State Lighting

    CERN Document Server

    Shinde, Kartik N; Swart, H C; Park, Kyeongsoon

    2012-01-01

    The idea for this book arose out of the realization that, although excellent surveys and a phosphor handbook are available, there is no single source covering the area of phosphate based phosphors especially for lamp industry. Moreover, as this field gets only limited attention in most general books on luminescence, there is a clear need for a book in which attention is specifically directed toward this rapidly growing field of solid state lighting and its many applications. This book is aimed at providing a sound introduction to the synthesis and optical characterization of phosphate phosphor for undergraduate and graduate students as well as teachers and researchers. The book provides guidance through the multidisciplinary field of solid state lighting specially phosphate phosphors for beginners, scientists and engineers from universities, research organizations, and especially industry. In order to make it useful for a wide audience, both fundamentals and applications are discussed, together.

  18. Phosphors for flat panel emissive displays

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, M.T.; Walko, R.J.; Phillips, M.L.F.

    1995-07-01

    An overview of emissive display technologies is presented. Display types briefly described include: cathode ray tubes (CRTs), field emission displays (FEDs), electroluminescent displays (ELDs), and plasma display panels (PDPs). The critical role of phosphors in further development of the latter three flat panel emissive display technologies is outlined. The need for stable, efficient red, green, and blue phosphors for RGB fall color displays is emphasized.

  19. Stabilizing platinum in phosphoric acid fuel cells

    Science.gov (United States)

    Remick, R. J.

    1982-01-01

    Platinum sintering on phosphoric acid fuel cell cathodes is discussed. The cathode of the phosphoric acid fuel cell uses a high surface area platinum catalyst dispersed on a conductive carbon support to minimize both cathode polarization and fabrication costs. During operation, however, the active surface area of these electrodes decreases, which in turn leads to decreased cell performance. This loss of active surface area is a major factor in the degradation of fuel cell performance over time.

  20. Comparison analysis on the properties of the phosphor film according to the various composition ratio of phosphor slurry

    Science.gov (United States)

    Park, Jeong Yeon; Lee, Jeong Won; Heo, Young Moo; Won, Si Tae; Yoon, Gil Sang

    2016-03-01

    The conventional method of making a phosphor layer on the LED package by using a dispensing method is difficult to implement the specific color coordinate, color temperature and optical efficiency because the thickness of the phosphor layer is non-uniform due to precipitation of the phosphor. Besides, the dispensing method consume a large amount of phosphor and silicone to fill the LED package. Thus, studies that manufacture phosphor layer with a uniform thickness such as spray coating, screen printing, electrophoresis are active recently. The purpose of this study is to perform the basic research about the change of the characteristics of phosphor film that is molded with uniform thickness using the phosphor slurry according to various silicone resin and phosphor composition ratio. It is expected to be used as useful information for the fabricating properties when production environment of phosphor layer is changed dispensing method into phosphor film fabrication. In the experiment, it was selected three kinds of methyl-phenyl silicone based resin as the phosphor slurry constituents, and mixed with phosphor various amount of 20 ˜ 60wt% content per one silicone resin. Using this mixed phosphor slurry, it was molded the phosphor film with 300 μm thickness and analyzed the mechanical properties and optical properties of the phosphor film. Finally, the results of this study are presented below: (a) As the phenyl group content is increased, the total heat of reaction need to cure the silicone resin is decrease, and also lower the durometer hardness of the phosphor sheet. On the other hand, it was confirmed that there is no relationship between the phenyl group content in the phosphor film and optical characteristics of the phosphor film. (b) If the amount of the phosphor within the film are increased, then the values of shore hardness and CIE color coordinates are increased gradually but the value of CIE color temperature is decreased gradually in case of being

  1. Fluorescent lighting with aluminum nitride phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Srivastava, Alok M.

    2016-05-10

    A fluorescent lamp includes a glass envelope; at least two electrodes connected to the glass envelope; mercury vapor and an inert gas within the glass envelope; and a phosphor within the glass envelope, wherein the phosphor blend includes aluminum nitride. The phosphor may be a wurtzite (hexagonal) crystalline structure Al.sub.(1-x)M.sub.xN phosphor, where M may be drawn from beryllium, magnesium, calcium, strontium, barium, zinc, scandium, yttrium, lanthanum, cerium, praseodymium, europium, gadolinium, terbium, ytterbium, bismuth, manganese, silicon, germanium, tin, boron, or gallium is synthesized to include dopants to control its luminescence under ultraviolet excitation. The disclosed Al.sub.(1-x)M.sub.xN:Mn phosphor provides bright orange-red emission, comparable in efficiency and spectrum to that of the standard orange-red phosphor used in fluorescent lighting, Y.sub.2O.sub.3:Eu. Furthermore, it offers excellent lumen maintenance in a fluorescent lamp, and does not utilize "critical rare earths," minimizing sensitivity to fluctuating market prices for the rare earth elements.

  2. [Progress in the research on silicon-nitrogen based phosphor for white LED].

    Science.gov (United States)

    Xu, Guo-Tang; Liang, Pei; Wang, Le; Dong, Qian-Min; Liu, Yang; Li, Xiao-Yan

    2013-11-01

    With the rapid development of white LED technology, the traditional YAG : Ce3+ phosphor is difficult to meet the requirement due to the low color rendering and high color temperature. Using ultraviolet chip to stimulate the tri-phosphor has become an effective way for white LED, and it is urgent to develop novel tri-phosphor with high-performance, especially for red light-emitting materials. Silicon-nitrogen based compounds contain the network structure composed of SiN4 tetrahedron, with higher chemical and thermal stability. Because of their diversity structures, these phosphors have a higher absorption efficiency in UV-blue region, and also, with the change of substrate and active ion, emission spectrum will cover the entire visible region, resulting in a higher light conversion efficiency and light color stability, coupled with the advantages of being not sensitive to the changes in temperature and drive current, etc. These studies will have a far-reaching impact on the development of white LED. In the present paper, we introduce the preparation and latest progress of silicon-nitrogen based phosphor, including the crystal structure, spectroscopic properties and application characteristics.

  3. Studies of the performance of different front-end systems for flat-panel multi-anode PMTs with CsI(Tl) scintillator arrays

    CERN Document Server

    Sekiya, H; Kubo, H; Miuchi, K; Nagayoshi, T; Nishimura, H; Okada, Y; Orito, R; Takada, A; Takeda, A; Tanimori, T; Ueno, K

    2006-01-01

    We have studied the performance of two different types of front-end systems for our gamma camera based on Hamamatsu H8500 (flat-panel 64 channels multi-anode PSPMT) with a CsI(Tl) scintillator array. The array consists of 64 pixels of $6\\times6\\times20{\\rm mm}^3$ which corresponds to the anode pixels of H8500. One of the system is based on commercial ASIC chips in order to readout every anode. The others are based on resistive charge divider network between anodes to reduce readout channels. In both systems, each pixel (6mm) was clearly resolved by flood field irradiation of $^{137}$Cs. We also investigated the energy resolution of these systems and showed the performance of the cascade connection of resistive network between some PMTs for large area detectors.

  4. Studies of the performance of different front-end systems for flat-panel multi-anode PMTs with CsI(Tl) scintillator arrays

    Science.gov (United States)

    Sekiya, H.; Hattori, K.; Kubo, H.; Miuchi, K.; Nagayoshi, T.; Nishimura, H.; Okada, Y.; Orito, R.; Takada, A.; Takeda, A.; Tanimori, T.; Ueno, K.

    2006-07-01

    We have studied the performance of two different types of front-end systems for our gamma camera based on Hamamatsu H8500 (flat-panel 64 channels multi-anode PSPMT) with a CsI(Tl) scintillator array. The array consists of 64 pixels of 6×6×20 mm3 which corresponds to the anode pixels of H8500. One of the system is based on commercial ASIC chips in order to read out every anode. The others are based on resistive charge divider network between anodes to reduce readout channels. In both systems, each pixel (6 mm) was clearly resolved by flood field irradiation of 137Cs. We also investigated the energy resolution of these systems and showed the performance of the cascade connection of resistive network between some PMTs for large area detectors.

  5. Multiple thermoluminescence glow peaks and afterglow suppression in CsI:Tl co-doped with Eu2+ or Yb2+

    Science.gov (United States)

    Bartram, R. H.; Kappers, L. A.; Hamilton, D. S.; Brecher, C.; Ovechkina, E. E.; Miller, S. R.; Nagarkar, V. V.

    2015-04-01

    CsI:Tl is a widely utilized scintillator material with many desirable properties but its applicability is limited by persistent afterglow. However, effective afterglow suppression has been achieved by co-doping with divalent lanthanides. The present report is concerned with observation of multiple thermoluminescence glow peaks in CsI:Tl,Eu and CsI:Tl,Yb, attributed to varying distributions of charge-compensating cation vacancies relative to divalent lanthanide co-dopants, and the subsequent modification of these distributions by repeated observations. It is observed that Yb2+ provides a slightly shallower electron trap than Eu2+, and that it can occupy a face-centered position by virtue of its relatively small ionic radius; the latter observation is confirmed by electrostatic calculations. It is also found that repeated observation of thermoluminescence in these materials has a modest adverse effect on afterglow suppression.

  6. Studies of the performance of different front-end systems for flat-panel multi-anode PMTs with CsI(Tl) scintillator arrays

    Energy Technology Data Exchange (ETDEWEB)

    Sekiya, H. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8502 (Japan)]. E-mail: sekiya@cr.scphys.kyoto-u.ac.jp; Hattori, K. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8502 (Japan); Kubo, H. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8502 (Japan); Miuchi, K. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8502 (Japan); Nagayoshi, T. [Advanced Research Institute for Science and Engineering, Waseda University, 17 Kikui-cho, Shinjuku, Tokyo 162-0044 (Japan); Nishimura, H. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8502 (Japan); Okada, Y. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8502 (Japan); Orito, R. [Department of Physics, Graduate School of Science and Technology, Kobe University, 1-1 Rokkoudai, Nada, Kobe 657-8501 (Japan); Takada, A. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8502 (Japan); Takeda, A. [Kamioka Observatory, ICRR, University of Tokyo, 456 Higasi-mozumi, Hida-shi, Gifu 506-1205 (Japan); Tanimori, T. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8502 (Japan); Ueno, K. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8502 (Japan)

    2006-07-01

    We have studied the performance of two different types of front-end systems for our gamma camera based on Hamamatsu H8500 (flat-panel 64 channels multi-anode PSPMT) with a CsI(Tl) scintillator array. The array consists of 64 pixels of 6x6x20mm{sup 3} which corresponds to the anode pixels of H8500. One of the system is based on commercial ASIC chips in order to read out every anode. The others are based on resistive charge divider network between anodes to reduce readout channels. In both systems, each pixel (6mm) was clearly resolved by flood field irradiation of {sup 137}Cs. We also investigated the energy resolution of these systems and showed the performance of the cascade connection of resistive network between some PMTs for large area detectors.

  7. MULTI-PHOTON PHOSPHOR FEASIBILITY RESEARCH

    Energy Technology Data Exchange (ETDEWEB)

    R. Graham; W. Chow

    2003-05-01

    Development of multi-photon phosphor materials for discharge lamps represents a goal that would achieve up to a doubling of discharge (fluorescent) lamp efficacy. This report reviews the existing literature on multi-photon phosphors, identifies obstacles in developing such phosphors, and recommends directions for future research to address these obstacles. To critically examine issues involved in developing a multi-photon phosphor, the project brought together a team of experts from universities, national laboratories, and an industrial lamp manufacturer. Results and findings are organized into three categories: (1) Multi-Photon Systems and Processes, (2) Chemistry and Materials Issues, and (3) Concepts and Models. Multi-Photon Systems and Processes: This category focuses on how to use our current understanding of multi-photon phosphor systems to design new phosphor systems for application in fluorescent lamps. The quickest way to develop multi-photon lamp phosphors lies in finding sensitizer ions for Gd{sup 3+} and identifying activator ions to red shift the blue emission from Pr{sup 3+} due to the {sup 1}S{sub 0} {yields} {sup 1}I{sub 6} transition associated with the first cascading step. Success in either of these developments would lead to more efficient fluorescent lamps. Chemistry and Materials Issues: The most promising multi-photon phosphors are found in fluoride hosts. However, stability of fluorides in environments typically found in fluorescent lamps needs to be greatly improved. Experimental investigation of fluorides in actual lamp environments needs to be undertaken while working on oxide and oxyfluoride alternative systems for backup. Concepts and Models: Successful design of a multi-photon phosphor system based on cascading transitions of Gd{sup 3+} and Pr{sup 3+} depends critically on how the former can be sensitized and the latter can sensitize an activator ion. Methods to predict energy level diagrams and Judd-Ofelt parameters of multi

  8. Radioactivity measurements using storage phosphor technology

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Y.T. [NeuTek, Darnestown, MD (United States); Hwang, J. [Advanced Technologies and Labs. International, Rockville, MD (United States); Hutchinson, M.R. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

    1995-10-01

    We propose to apply a recently developed charged particle radiation imaging concept in bio-medical research for fast, cost-effective characterization of radionuclides in contaminated sites and environmental samples. This concept utilizes sensors with storage photostimulable phosphor (SPP) technology as radiation detectors. They exhibit high sensitivity for all types of radiation and the response is linear over a wide dynamic range (>10{sup 5}), essential for quantitative analysis. These new sensors have an Active area of up to 35 cm x 43 cm in size and a spatial resolution as fine as 50 {mu}m. They offer considerable promise as large area detectors for fast characterization of radionuclides with an added ability to locate and identify hot spots. Tests with SPP sensors have found that a single alpha particle effect can be observed and an alpha field of 100 dpm/100 cm{sup 2} or a beta activity of 0.1 dpm/mm{sup 2} or gamma radiation of few {mu}R/hr can all be measured in minutes. Radioactive isotopes can further be identified by energy discrimination which is accomplished by placing different thicknesses of filter material in front of the sensor plate. For areas with possible neutron contamination, the sensors can be coupled to a neutron to charged particle converter screen, such as dysprosium foil to detect neutrons. Our study has shown that this approach can detect a neutron flux of 1 n/cm{sup 2}s or lower, again with only minutes of exposure time. The utilization of these new sensors can significantly reduce the time and cost required for many site characterization and environmental monitoring tasks. The {open_quotes}exposure{close_quotes} time for mapping radioactivity in an environmental sample may be in terms of minutes and offer a positional resolution not obtainable with presently used counting equipment. The resultant digital image will lend itself to ready analysis.

  9. Study On The Separation And Extraction Of Rare-Earth Elements From The Phosphor Recovered From End Of Life Fluorescent Lamps

    Directory of Open Access Journals (Sweden)

    Shin D.-W.

    2015-06-01

    Full Text Available In this study, recovered phosphor from end of life three-wavelength fluorescent lamp was selected for reuse rare earth elements in the phosphor. The effect of a type of acid, concentration, and time was investigated as solubility of rare earth elements. In addition, precipitate heat-treated was investigated as possibility of reusable phosphor. The results showed that the amount of the rare earth elements was different values depending on the type of acid, and it was investigated with concentration of acid and reaction time. After precipitation reaction, the precipitate was sintered in electric furnace in order to reuse rare earth elements as phosphor. It was confirmed that yttrium, europium, oxygen, and carbon through X-ray diffraction and inductively coupled plasma analysis. Following the results, it can assume that rare earth oxide reuse the phosphor as three-wavelength fluorescent lamp.

  10. Characterisation of phosphorous forms in wastewater treatment plants.

    Science.gov (United States)

    Fernández Dueñas, Joel; Ribas Alonso, Josep; Freixó Rey, Angel; Sánchez Ferrer, Antoni

    2003-02-28

    The removal of different forms of phosphorous (namely total phosphorous, soluble phosphorous, particulate phosphorous and total phosphate) has been studied in two municipal wastewater treatment plants (WWTP) with different characteristics, but without any specific implemented strategy for phosphorous removal. The results obtained for the different forms of phosphorus can be summarised as follows: (1) complete removal of particulate phosphorous is achieved in either primary or secondary clarifiers; (2) total phosphorous concentration in the effluent is mostly soluble phosphorous and this is mainly phosphate; (3) a small amount of soluble phosphorous is removed by biomass growth and/or biosorption; (4) both WWTPs presented a high-buffered behaviour in response to high inlet loading of phosphorous, showing a constant pattern at the outlet of the WWTP; (5) removal of total phosphorous was approximately 60-70% for both WWTPs; and (6) recirculation streams such as supernatant from centrifuge sludge dehydration operation can have a significant contribution to the inlet amount of phosphorous. The results presented in this paper provide a basis to develop prospects for phosphorous removal, which may be adapted to the particular configurations of the WWTP studied.

  11. Electrolyte Additives for Phosphoric Acid Fuel Cells

    DEFF Research Database (Denmark)

    Gang, Xiao; Hjuler, H.A.; Olsen, C.A.

    1993-01-01

    Electrochemical characteristics of a series of modified phosphoric acid electrolytes containing fluorinated car on compounds and silicone fluids as additives are presented. When used in phosphoric acid fuel cells, the modified electrolytes improve the performance due to the enhanced oxygen...... reduction rate. Among useful additives we found potassium perfluorohexanesulfonate (C6F13SO3K), potassium nonafluorobutanesulfonate (C4F9SO3K), perfluorotributylamine [(C4F9)3N], and polymethylsiloxanes [(-Si(CH3)2O-)n]. The wettability of the electrodes by the modified electrolytes also is discussed......, as a fuel-cell performance with the modified electrolytes. Specific conductivity measurements of some of the modified phosphoric acid electrolytes are reported. At a given temperature, the conductivity of the C4F9SO3K-modified electrolyte decreases with an increasing amount of the additive; the conductivity...

  12. Influence of different phosphoric acids in enamel adhesion

    National Research Council Canada - National Science Library

    Christopher Cadete de Figueiredo; Diego Alves Cunha; Igor Figueiredo Pereira; Julio Cesar Campos Ferreira Filho; Bianca Marques Santiago; Ana Maria Gondim Valença

    2012-01-01

    ...% with and without chlorhexidine. Thirty bovine incisors were divided into two groups (n = 15), according to the type of acid etching applied in enamel – G1 (phosphoric acid 37%) and G2 (phosphoric acid 37...

  13. Stabilizing platinum in phosphoric acid fuel cells

    Science.gov (United States)

    Remick, R. J.

    1981-10-01

    A carbon substrate for use in fabricating phosphoric acid fuel cell cathodes was modified by catalytic oxidation to stabilize the platinum catalyst by retarding the sintering of small platinum crystallites. Results of 100-hour operational tests confirmed that the rate of platinum surface area loss observed on catalytically oxidized supports was less than that observed with unmodified supports of the same starting material. Fuel cell electrodes fabricated from Vulcan XC-72R, which was modified by catalytic in a nitric oxide atmosphere, produced low platium sintering rates and high activity for the reduction of oxygen in the phosphoric acid environment.

  14. Feeling blue? Blue phosphors for OLEDs

    Directory of Open Access Journals (Sweden)

    Hungshin Fu

    2011-10-01

    Full Text Available Research on organic light emitting diodes (OLEDs has been revitalized, partly due to the debut of the OLED TV by SONY in 2008. While there is still plenty of room for improvement in efficiency, cost-effectiveness and longevity, it is timely to report on the advances of light emitting materials, the core of OLEDs, and their future perspectives. The focus of this account is primarily to chronicle the blue phosphors developed in our laboratory. Special attention is paid to the design strategy, synthetic novelty, and their OLED performance. The report also underscores the importance of the interplay between chemistry and photophysics en route to true-blue phosphors.

  15. Inorganic-organic hybrid white light phosphors.

    Science.gov (United States)

    Wang, Ming-Sheng; Guo, Guo-Cong

    2016-11-03

    Light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs) have brought about a revolution in lighting and display. A very hot field in recent years has been to develop white-light phosphors, aiming to achieve better colour stability, better reproducibility, and a simpler fabrication process for LEDs and OLEDs. This feature article reviews the development of inorganic-organic hybrid white-light phosphors, including coordination compounds of small organic molecules, organically templated inorganic compounds (phosphates, borates, sulfides, halides), metal-functionalized organic polymers, and organically coated nanoparticles.

  16. 40 CFR 721.3135 - Phosphorous modified epoxy resin (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphorous modified epoxy resin... Specific Chemical Substances § 721.3135 Phosphorous modified epoxy resin (generic). (a) Chemical substance... phosphorous modified epoxy resin (PMNs P-00-992 and P-01-471) is subject to reporting under this section...

  17. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid derivative (generic... Specific Chemical Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical substance... phosphoric acid derivative (PMN P-95-284) is subject to reporting under this section for the significant...

  18. Phosphate phosphors for solid-state lighting

    Energy Technology Data Exchange (ETDEWEB)

    Shinde, Kartik N. [N.S. Science and Arts College, Bhadrawati (India). Dept. of Physics; Swart, H.C. [University of the Orange Free State, Bloemfontein (South Africa). Dept. of Physics; Dhoble, S.J. [R.T.M. Nagpur Univ. (India). Dept. of Physics; Park, Kyeongsoon [Sejong Univ., Seoul (Korea, Republic of). Faculty of Nanotechnology and Advanced Materials Engineering

    2012-07-01

    Essential information for students in researchers working towards new and more efficient solid-state lighting. Comprehensive survey based on the authors' long experience. Useful both for teaching and reference. The idea for this book arose out of the realization that, although excellent surveys and a phosphor handbook are available, there is no single source covering the area of phosphate based phosphors especially for lamp industry. Moreover, as this field gets only limited attention in most general books on luminescence, there is a clear need for a book in which attention is specifically directed toward this rapidly growing field of solid state lighting and its many applications. This book is aimed at providing a sound introduction to the synthesis and optical characterization of phosphate phosphor for undergraduate and graduate students as well as teachers and researchers. The book provides guidance through the multidisciplinary field of solid state lighting specially phosphate phosphors for beginners, scientists and engineers from universities, research organizations, and especially industry. In order to make it useful for a wide audience, both fundamentals and applications are discussed, together.

  19. Corrosion free phosphoric acid fuel cell

    Science.gov (United States)

    Wright, Maynard K.

    1990-01-01

    A phosphoric acid fuel cell with an electrolyte fuel system which supplies electrolyte via a wick disposed adjacent a cathode to an absorbent matrix which transports the electrolyte to portions of the cathode and an anode which overlaps the cathode on all sides to prevent corrosion within the cell.

  20. Electrochemically promoted electroless nickel-phosphorous plating on titanium substrate

    Science.gov (United States)

    Gao, Ce; Dai, Lei; Meng, Wei; He, Zhangxing; Wang, Ling

    2017-01-01

    An electrochemically promoted electroless nickel-phosphorous plating process on titanium substrate is proposed. The influences of the temperature and current density on the phosphorous content, coating thickness and corrosion resistance are investigated. The results show that with the help of the electrochemical promotion, the uniform and amorphous nickel-phosphorous coatings with medium phosphorus content (6-8 wt%) are successfully prepared in the electroless bath at 40-60 °C. The phosphorous content of the coating increases with the temperature increasing, while decreases with current density increasing. Obvious passivation occurs for the nickel-phosphorous coatings during the anodic polarization in 3.5 wt% NaCl solution.

  1. Red-emitting manganese-doped aluminum nitride phosphor

    Science.gov (United States)

    Cherepy, Nerine J.; Payne, Stephen A.; Harvey, Nicholas M.; Åberg, Daniel; Seeley, Zachary M.; Holliday, Kiel S.; Tran, Ich C.; Zhou, Fei; Martinez, H. Paul; Demeyer, Jessica M.; Drobshoff, Alexander D.; Srivastava, Alok M.; Camardello, Samuel J.; Comanzo, Holly A.; Schlagel, Deborah L.; Lograsso, Thomas A.

    2016-04-01

    We report high efficiency luminescence with a manganese-doped aluminum nitride red-emitting phosphor under 254 nm excitation, as well as its excellent lumen maintenance in fluorescent lamp conditions, making it a candidate replacement for the widely deployed europium-doped yttria red phosphor. Solid-state reaction of aluminum nitride powders with manganese metal at 1900 °C, 10 atm N2 in a reducing environment results in nitrogen deficiency, as revealed diffuse reflectance spectra. When these powders are subsequently annealed in flowing nitrogen at 1650 °C, higher nitrogen content is recovered, resulting in white powders. Silicon was added to samples as an oxygen getter to improve emission efficiency. NEXAFS spectra and DFT calculations indicate that the Mn dopant is divalent. From DFT calculations, the UV absorption band is proposed to be due to an aluminum vacancy coupled with oxygen impurity dopants, and Mn2+ is assumed to be closely associated with this site. In contrast with some previous reports, we find that the highest quantum efficiency with 254 nm excitation (Q.E. = 0.86 ± 0.14) is obtained in aluminum nitride with a low manganese doping level of 0.06 mol.%. The principal Mn2+ decay of 1.25 ms is assigned to non-interacting Mn sites, while additional components in the microsecond range appear with higher Mn doping, consistent with Mn clustering and resultant exchange coupling. Slower components are present in samples with low Mn doping, as well as strong afterglow, assigned to trapping on shallow traps followed by detrapping and subsequent trapping on Mn.

  2. Direct and indirect signal detection of 122 keV photons with a novel detector combining a pnCCD and a CsI(Tl) scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Schlosser, D.M., E-mail: dieter.schlosser@pnsensor.de [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Huth, M.; Hartmann, R. [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Abboud, A.; Send, S. [Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany); Conka-Nurdan, T. [Türkisch-Deutsche Universität, Sakinkaya Cad. 86, Beykoz, 34820 Istanbul (Turkey); Shokr, M.; Pietsch, U. [Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany); Strüder, L. [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany)

    2016-01-01

    By combining a low noise fully depleted pnCCD detector with a CsI(Tl) scintillator, an energy-dispersive area detector can be realized with a high quantum efficiency (QE) in the range from below 1 keV to above 100 keV. In direct detection mode the pnCCD exhibits a relative energy resolution of 1% at 122 keV and spatial resolution of less than 75 µm, the pixel size of the pnCCD. In the indirect detection mode, i.e. conversion of the incoming X-rays in the scintillator, the measured energy resolution was about 9–13% at 122 keV, depending on the depth of interaction in the scintillator, while the position resolution, extracted with the help of simulations, was 30 µm only. We show simulated data for incident photons of 122 keV and compare the various interaction processes and relevant physical parameters to experimental results obtained with a radioactive {sup 57}Co source. - Highlights: • Position and energy resolving pnCCD+CsI(Tl) detector for energies from 1-150 keV • Detection in the pnCCD (122keV): 1% energy and <75µm spatial resolution • Detection in the scintillator (122keV): 9-12% energy and ~30µm spatial resolution.

  3. Scintillation response of CsI(Tl) and CsI(Na) crystals on X-ray and gamma-quanta low energy excitation

    CERN Document Server

    Kudin, A M; Vydaj, Y T; Gres, V Y

    2001-01-01

    The dependence on the response (L/E) from energy (E) in the range of 5.9...60 keV has been investigated for CsI(Na) during the aging and for CsI(Tl) crystals with different activator concentrations and light collection conditions. On the contrast to data on increasing of L/E in the range of approx 15 keV (so called the response non-proportionality up to + 245), we have shown that value and sign of non-proportionality are determined by light collection conditions, mainly and scintillation material (luminescence centers concentration) in the minor. The distinct correlation is observed between non-proportionality and energy resolution in the low energy range even where is supposed the non-proportionality contribution is insignificant. The main conclusion is the response non-proportionality is not fundamental property of the scintillator. It (and energy resolution) rise from light collection conditions for the quantum with different penetration depth and scintillation long.

  4. Radiation damage of CsI(Tl) scintillators: blocking of energy transfer process of V sub k centers to Tl sup + activators

    CERN Document Server

    Hamada, M M; Shimizu, S; Kubota, S

    2002-01-01

    This paper reports the emission spectra, light output, transmission and decay curves of CsI(Tl) crystals irradiated with gamma rays at different doses, ranging from 1x10 sup 5 to 5x10 sup 5 Gy. The crystals were coated with black or white tapes. Significant decreases in the emission spectra and light output values were observed for the crystals coated with white tape as the radiation dose increased. The decrease in the degree of the rising part of the decay curve in the irradiated crystals is attributed to the blocking of the energy transfer processes of V sub k lattice disorders, which were produced in irradiated crystals. The scintillation mechanism is affected in the crystal irradiated at 5x10 sup 5 Gy. However for crystals irradiated below 10 sup 5 Gy the mechanism process is not altered, and the decrease in the light output is due to internal transmission loss. It was also observed that the damage for irradiation is not permanent and it obeys a bi-exponential function.

  5. Direct and indirect signal detection of 122 keV photons with a novel detector combining a pnCCD and a CsI(Tl) scintillator

    Science.gov (United States)

    Schlosser, D. M.; Huth, M.; Hartmann, R.; Abboud, A.; Send, S.; Conka-Nurdan, T.; Shokr, M.; Pietsch, U.; Strüder, L.

    2016-01-01

    By combining a low noise fully depleted pnCCD detector with a CsI(Tl) scintillator, an energy-dispersive area detector can be realized with a high quantum efficiency (QE) in the range from below 1 keV to above 100 keV. In direct detection mode the pnCCD exhibits a relative energy resolution of 1% at 122 keV and spatial resolution of less than 75 μm, the pixel size of the pnCCD. In the indirect detection mode, i.e. conversion of the incoming X-rays in the scintillator, the measured energy resolution was about 9-13% at 122 keV, depending on the depth of interaction in the scintillator, while the position resolution, extracted with the help of simulations, was 30 μm only. We show simulated data for incident photons of 122 keV and compare the various interaction processes and relevant physical parameters to experimental results obtained with a radioactive 57Co source.

  6. Comparison between a silicon PIN diode and a CsI(Tl) coupled to a silicon PIN diode for dosimetric purpose in radiology

    Science.gov (United States)

    Andreani, Lucia; Bontempi, Marco; Rossi, Pier Luca; Rignanese, Luigi Pio; Zuffa, Mirco; Baldazzi, Giuseppe

    2014-10-01

    The use of amorphous Si-PIN diodes showed interesting applications in detector research. Due to their properties and cost effective value, these devices can be used as small dosimeters for fast and real time dose evaluation. The responses of two different detectors to the measurement of X-ray total air KERMA are compared and presented, with the goal to get a dosimetric parameter directly during the X-ray patients exposure. A bare Si-PIN diode and a Si-PIN diode+CsI(Tl) scintillator were tested and compared to radiologic dosimeters. Both detector outputs were calibrated using a secondary reference standard (CAPINTEC PM 30 dosimeter), in order to analyze and discuss the dose and the energy dependence of the detectors in the range of radiologic interest (tube voltage: 40-140 kVp and additional filtration: 0 mm Al to 4 mm Al). The bare Si-PIN diode shows a very coherent response independently from the X-ray beam quality and from the additional filtration. The Si-PIN+CsI(Tl) detector, on the other hand, shows a high spread of the calibration curves as a function of the tube high voltage and the additional filtration. The presented results could be used to calibrate an image detector in dose.

  7. Comparison between a silicon PIN diode and a CsI(Tl) coupled to a silicon PIN diode for dosimetric purpose in radiology

    Energy Technology Data Exchange (ETDEWEB)

    Andreani, Lucia, E-mail: lucia.andreani4@unibo.it [University of Bologna, Department of Physics and Astronomy, Viale Berti-Pichat 6/2, 40127 Bologna (Italy); INFN Bologna, Viale Berti Pichat 6/2, 40127 Bologna (Italy); Bontempi, Marco [Laboratorio NaBi, Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna (Italy); Rossi, Pier Luca [University of Bologna, Department of Physics and Astronomy, Viale Berti-Pichat 6/2, 40127 Bologna (Italy); INFN Bologna, Viale Berti Pichat 6/2, 40127 Bologna (Italy); Rignanese, Luigi Pio [University of Bologna, Department of Physics and Astronomy, Viale Berti-Pichat 6/2, 40127 Bologna (Italy); Zuffa, Mirco [INFN Bologna, Viale Berti Pichat 6/2, 40127 Bologna (Italy); Baldazzi, Giuseppe [University of Bologna, Department of Physics and Astronomy, Viale Berti-Pichat 6/2, 40127 Bologna (Italy); INFN Bologna, Viale Berti Pichat 6/2, 40127 Bologna (Italy)

    2014-10-21

    The use of amorphous Si-PIN diodes showed interesting applications in detector research. Due to their properties and cost effective value, these devices can be used as small dosimeters for fast and real time dose evaluation. The responses of two different detectors to the measurement of X-ray total air KERMA are compared and presented, with the goal to get a dosimetric parameter directly during the X-ray patients exposure. A bare Si-PIN diode and a Si-PIN diode+CsI(Tl) scintillator were tested and compared to radiologic dosimeters. Both detector outputs were calibrated using a secondary reference standard (CAPINTEC PM 30 dosimeter), in order to analyze and discuss the dose and the energy dependence of the detectors in the range of radiologic interest (tube voltage: 40–140 kVp and additional filtration: 0 mm Al to 4 mm Al). The bare Si-PIN diode shows a very coherent response independently from the X-ray beam quality and from the additional filtration. The Si-PIN+CsI(Tl) detector, on the other hand, shows a high spread of the calibration curves as a function of the tube high voltage and the additional filtration. The presented results could be used to calibrate an image detector in dose.

  8. Degradation of phosphor-in-glass encapsulants with various phosphor types for high power LEDs

    Science.gov (United States)

    Iqbal, Fauzia; Kim, Sunil; Kim, Hyungsun

    2017-10-01

    In order to replace conventional silicone-based phosphor light emitting diodes (LEDs), inorganic color converters with high thermal stabilities and transparencies, i.e., phosphors-in-glass (PiGs), have been investigated as encapsulants for high-power LEDs. In this paper, the effect of various types of phosphors, i.e., LuAG (green, Lu3Al5O12:Ce3+), silicate (yellow, Sr2SiO4:Eu2+), CASN (red, CaAlSiN3:Eu2+), and oxynitride (yellow, (Sr,Ba) Si2O2N2:Eu2+), on the reliability/degradation of the remote PiG encapsulants is explored for high power LEDs. For this purpose, a glass composition (SiO2-B2O3-ZnO-Na2O) was separately mixed with each type of phosphor and then sintered at appropriate temperatures to make the corresponding PiG. The reliabilities of the formed PiGs were evaluated by standard accelerated-aging tests (85 °C/85% RH) for 1000 h. Luminosity losses and shifts in the Commission Internationale de l'Eclairage (CIE) coordinates of the PiGs were measured before and after aging. Thermal, and moisture-induced quenching behavior was also analyzed. The surface of PiGs with different phosphors degraded differently, possibly because of structural incompatibilities between the glass matrix and phosphor type. Determining the compatibility of the glass composition with the type of phosphor used is therefore important in order to ensure the long-term stabilities of encapsulants for use in commercial LEDs.

  9. Phosphor-Free Solid State Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Nause, Jeff E; Ferguson, Ian; Doolittle, Alan

    2007-02-28

    The objective of this work was to demonstrate a light emitting diode that emitted white light without the aid of a phosphor. The device was based on the combination of a nitride LED and a fluorescing ZnO substrate. The early portion of the work focused on the growth of ZnO in undoped and doped form. The doped ZnO was successfully engineered to emit light at specific wavelengths by incorporating various dopants into the crystalline lattice. Thereafter, the focus of the work shifted to the epitaxial growth of nitride structures on ZnO. Initially, the epitaxy was accomplished with molecular beam epitaxy (MBE). Later in the program, metallorganic chemical vapor deposition (MOCVD) was successfully used to grow nitrides on ZnO. By combining the characteristics of the doped ZnO substrate with epitaxially grown nitride LED structures, a phosphor-free white light emitting diode was successfully demonstrated and characterized.

  10. [Change traits of phosphorous consumption structure in China and their effects on environmental phosphorous loads].

    Science.gov (United States)

    Ma, Dun-Chao; Hu, Shan-Ying; Chen, Ding-Jiang; Li, You-Run

    2012-04-01

    Substance flow analysis was used to construct a model to analyze change traits of China's phosphorous (P) consumption structure from 1980 to 2008 and their influences on environmental phosphorous loads, then the correlation between several socioeconomic factors and phosphorous consumption pollution was investigated. It is found that phosphorous nutrient inputs of urban life and rural life on a per capita level climbed to 1.20 kg x a(-1) and 0.99 kg x a(-1) from 0.83 kg x a(-1) and 0.75 kg x a(-1) respectively, but phosphorous recycling ratios of urban life fell to 15.6% from 62.6%. P inputs of animal husbandry and planting also kept increasing, but the recycling ratio of the former decreased from 67.5% to 40.5%, meanwhile much P input of the latter was left in agricultural soil. Correlation coefficients were all above 0.90, indicating that population, urbanization level, development levels of planting and animal husbandry were important incentives for P consumption pollution in China. Environmental Kuznets curve showed that China still stayed in the early development stage, promoting economic growth at an expense of environmental quality. This study demonstrates that China's P consumption system is being transformed into a linear and open structure, and that P nutrient loss and environmental P loads increase continually.

  11. Sorohalide scintillators, phosphors, and uses thereof

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Pin; Deng, Haoran; Doty, F. Patrick; Zhou, Xiaowang

    2016-05-10

    The present invention relates to sorohalide compounds having formula A.sub.3B.sub.2X.sub.9, where A is an alkali metal, B is a rare earth metal, and X is a halogen. Optionally, the sorohalide includes a dopant D. Such undoped and doped sorohalides are useful as scintillation materials or phosphors for any number of uses, including for radiation detectors, solid-state light sources, gamma-ray spectroscopy, medical imaging, and drilling applications.

  12. Phosphoric Acid Fuel Cell Technology Status

    Science.gov (United States)

    Simons, S. N.; King, R. B.; Prokopius, P. R.

    1981-01-01

    A review of the current phosphoric acid fuel cell system technology development efforts is presented both for multimegawatt systems for electric utility applications and for multikilowatt systems for on-site integrated energy system applications. Improving fuel cell performance, reducing cost, and increasing durability are the technology drivers at this time. Electrodes, matrices, intercell cooling, bipolar/separator plates, electrolyte management, and fuel selection are discussed.

  13. Synthesis of Chiral Amino Cyclic Phosphoric Acids

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Chirai amino cyclic phosphoric acids, 5-amino-2-hydroxy-4- (4-nitrophenyl)-l, 3,2-dioxaphospho- rinane 2-oxide and 2-hydroxy-4- (4-methylsulfonylphenyl)-5-phthalimido-1,3,2-dioxaphos phorinane 2-oxide are synthesized in good over yields (64. 2% and 72. 8% respectively) from 2-amino-l-aryl-l,3-propanediols. The different reaction conditions are necessary in hydrolysis reactions of amino cyclic phosphonyl chlorides.

  14. 40 CFR 422.50 - Applicability; description of the defluorinated phosphoric acid subcategory.

    Science.gov (United States)

    2010-07-01

    ... defluorinated phosphoric acid subcategory. 422.50 Section 422.50 Protection of Environment ENVIRONMENTAL... Defluorinated Phosphoric Acid Subcategory § 422.50 Applicability; description of the defluorinated phosphoric... defluorination of phosphoric acid. Wet process phosphoric acid is dehydrated by application of heat and...

  15. Fundamental study of phosphor separation by controlling magnetic force

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Kohei, E-mail: kohei@qb.see.eng.osaka-u.ac.jp; Mishima, Fumihito; Akiyama, Yoko, E-mail: yoko-ak@qb.see.eng.osaka-u.ac.jp; Nishijima, Shigehiro

    2013-11-15

    Highlights: •We tried to separate the phosphor using the magnetic Archimedes separation method. •In this method, vertical and radial components of the magnetic force were used. •We succeeded to separate HP and developed the continuous separation system. •The separation system enables successive separation and recovery of HP. -- Abstract: The phosphor wastes consist of phosphors with different emission colors, green (LAP), red (YOX), blue (BAM) and white (HP). It is required to recover and reuse the rare earth phosphors with high market value. In this study, we tried to separate the phosphor using the magnetic separation by HTS bulk magnet utilizing the differences of magnetic susceptibility by the type of phosphors. We succeeded in the successive separation of HP with low market value from YOX and BAM including the rare earth using the magnetic Archimedes method. In this method, vertical and radial components of the magnetic force were used.

  16. Preparation and evaluation of advanced catalysts for phosphoric acid fuel cells

    Science.gov (United States)

    Stonehart, P.; Baris, J.; Hockmuth, J.; Pagliaro, P.

    1984-01-01

    The platinum electrocatalysts were characterized for their crystallite sizes and the degree of dispersion on the carbon supports. One application of these electrocatalysts was for anodic oxidation of hydrogen in hot phosphoric acid fuel cells, coupled with the influence of low concentrations of carbon monoxide in the fuel gas stream. In a similar way, these platinum on carbon electrocatalysts were evaluated for oxygen reduction in hot phosphoric acid. Binary noble metal alloys were prepared for anodic oxidation of hydrogen and noble metal-refractory metal mixtures were prepared for oxygen reduction. An exemplar alloy of platinum and palladium (50/50 atom %) was discovered for anodic oxidation of hydrogen in the presence of carbon monoxide, and patent disclosures were submitted. For the cathode, platinum-vanadium alloys were prepared showing improved performance over pure platinum. Preliminary experiments on electrocatalyst utilization in electrode structures showed low utilization of the noble metal when the electrocatalyst loading exceeded one weight percent on the carbon.

  17. Luminescence kinetics of phosphors after excitation by electron beam

    OpenAIRE

    Ваганов, Виталий; Полисадова, Елена Фёдоровна; Мархабаева, А. А.

    2016-01-01

    The luminescence decay of industrial phosphors based on yttrium-aluminum garnet has beeninvestigated at the excitation by an electron beam. The ratio of slow and fast component amplitude in the kinetics of luminescence decay was estimated. It is shown that the luminescence decay time depends on the composition of the phosphor. The luminescence decay time can be used for analysis of the phosphors, to determine their quality.

  18. Phosphor Systems for Illumination Quality Solid State Lighting Products

    Energy Technology Data Exchange (ETDEWEB)

    Setlur, Anant; Briel, Linda; Cleaver, Robert; Clothier, Brent; Gao, Yan; Harlow, Richard; Henderson, Claire; Heward, William; Hill, M Christine; Lyons, Robert; Murphy, James; Siclovan, Oltea; Stoklosa, Stan; Happek, Uwe; Aanegola, Srinath; Aesram, Danny; Deshpande, Anirudha; Jacob, Cherian; Kolodin, Boris; Stoklosa, Emil; Beers, Williams

    2010-03-31

    The objective of this program is to develop phosphor systems that will enable LED lamps with 96 lm/W efficacy at correlated color temperatures, (CCTs) ~3000 K, and color rendering indices (CRIs) >80 and 71 lm/W efficacy at CCT<3100 K and CRI~95 using phosphor downconversion of LEDs. This primarily involves the invention and development of new phosphor materials that have improved efficiency and better match the eye sensitivity curves.

  19. Surface-treatment of Alkaline Earth Sulfides Based Phosphor

    Institute of Scientific and Technical Information of China (English)

    GUO Chong-feng; CHU Ben-li; XU Jian; SU Qiang

    2004-01-01

    A series of alkaline earth sulfides based phosphors Ca0.8Sr0.2S∶Eu2+, Tm3+ were covered with a layer of protective coating with alkaline earth fluorides by heating the mixture of phosphor and NH4HF2 at elevated temperatures. The coatings were characterized by means of XRD and SEM. The optical properties of the coated phosphors and the influences of the coating on their properties have been discussed extensively. The stabilities of the coated and uncoated phosphors have been compared.

  20. Progress in production and application of RE phosphors (continued)

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ 5. Rare earth trichromatic phosphors for lamps The energy efficient and environmental-friendly effects of rare earth fluorescent lamps have been recognized by globalcustomers in recent years. Many countries, especially developed countries, are replacing incandescent lamps with rare earthtrichromatic fluorescent lamps, which consequently promote the development of rare earth three prime color phosphors for lamps.China is one of the main producers of rare earth trichromatic phosphors and rare earth lamps in the world. Table 7 shows the outputof three prime color phosphors for lamps since 1999 and Table 8 shows the output of CFL (compact fluorescent lamp) from 2000 to2007 in China.

  1. Point defect engineering strategies to retard phosphorous diffusion in germanium

    KAUST Repository

    Tahini, H. A.

    2013-01-01

    The diffusion of phosphorous in germanium is very fast, requiring point defect engineering strategies to retard it in support of technological application. Density functional theory corroborated with hybrid density functional calculations are used to investigate the influence of the isovalent codopants tin and hafnium in the migration of phosphorous via the vacancy-mediated diffusion process. The migration energy barriers for phosphorous are increased significantly in the presence of oversized isovalent codopants. Therefore, it is proposed that tin and in particular hafnium codoping are efficient point defect engineering strategies to retard phosphorous migration. © the Owner Societies 2013.

  2. A ΔE-E semiconductor detector combined with CsI(Tl) crystal for monitoring the relative electrons flux generated in interaction of accelerated nuclei beam on thin targets

    Science.gov (United States)

    Cruceru, M.; Afanasiev, S.; Dryablov, D.; Dubinchik, B.; Igamkulov, Z.

    2015-07-01

    Experimental data are presented, obtained with a ΔE-E semiconductor detector combined with a CsI(Tl) inorganic scintillator crystal. The interaction between a beam of accelerated nuclei and thin targets is analyzed. We show that, as a result of this interaction, the secondary particles, including δ-electrons, are generated. In the case of δ-electrons it is possible to study the beam characteristics and the nature of interaction processes, which is of great interest in high-energy interaction.

  3. World wide IFC phosphoric acid fuel cell implementation

    Energy Technology Data Exchange (ETDEWEB)

    King, J.M. Jr

    1996-04-01

    International Fuel Cells, a subsidary of United technologies Corporation, is engaged in research and development of all types of fuel cell technologies and currently manufactures alkaline fuel cell power plants for the U.S. manned space flight program and natural gas fueled stationary power plants using phosphoric acid fuel cells. This paper describes the phosphoric acid fuel cell power plants.

  4. Luminescence spectroscopy of quantum cutting phosphors : materials, measurements and mechanisms

    NARCIS (Netherlands)

    Vergeer, Peter

    2005-01-01

    The industrial drive for this research is to find new phosphors for application in mercury-free fluorescent lamps and plasma display panels. The vacuum-ultraviolet (VUV) excitation light that is used in these devices allows for the use of phosphors that show emission of two photons for each photon

  5. Ln(III) complexes as potential phosphors for white LEDs

    NARCIS (Netherlands)

    Akerboom, Sebastiaan

    2013-01-01

    Generating white light with LED technology requires a trick; one of them is to use color-converting (phosphor) layer that covers the LED chip. Suitable phosphors that can be excited with LEDs are scarce, necessitating research in this area. Complexes of the trivalent lanthanoids are interesting cand

  6. Phosphor Scanner For Imaging X-Ray Diffraction

    Science.gov (United States)

    Carter, Daniel C.; Hecht, Diana L.; Witherow, William K.

    1992-01-01

    Improved optoelectronic scanning apparatus generates digitized image of x-ray image recorded in phosphor. Scanning fiber-optic probe supplies laser light stimulating luminescence in areas of phosphor exposed to x rays. Luminescence passes through probe and fiber to integrating sphere and photomultiplier. Sensitivity and resolution exceed previously available scanners. Intended for use in x-ray crystallography, medical radiography, and molecular biology.

  7. Color stable phosphors for LED lamps and methods for preparing them

    Science.gov (United States)

    Murphy, James Edward; Setlur, Anant Achyut; Camardello, Samuel Joseph

    2013-11-26

    An LED lamp includes a light source configured to emit radiation with a peak intensity at a wavelength between about 250 nm and about 550 nm; and a phosphor composition configured to be radiationally coupled to the light source. The phosphor composition includes particles of a phosphor of formula I, said particles having a coating composition disposed on surfaces thereof; ((Sr.sub.1-zM.sub.z).sub.1-(x+w)A.sub.wCe.sub.x).sub.3(Al.sub.1-ySi.sub.y-)O.sub.4+y+3(x-w)F.sub.1-y-3(x-w) I wherein the coating composition comprises a material selected from aluminum oxide, magnesium oxide, calcium oxide, barium oxide, strontium oxide, zinc oxide, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, strontium hydroxide, zinc hydroxide, aluminum phosphate, magnesium phosphate, calcium phosphate, barium phosphate, strontium phosphate, and combinations thereof; and A is Li, NA, K, or Rb, or a combination thereof; M is Ca, Ba, Mg, Zn, or a combination thereof; and 0

  8. Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

    Science.gov (United States)

    Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

    2009-01-01

    Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

  9. Self-activating and doped tantalate phosphors.

    Energy Technology Data Exchange (ETDEWEB)

    Nyman, May Devan; Rohwer, Lauren Elizabeth Shea

    2011-01-01

    An ideal red phosphor for blue LEDs is one of the biggest challenges for the solid-state lighting industry. The appropriate phosphor material should have good adsorption and emission properties, good thermal and chemical stability, minimal thermal quenching, high quantum yield, and is preferably inexpensive and easy to fabricate. Tantalates possess many of these criteria, and lithium lanthanum tantalate materials warrant thorough investigation. In this study, we investigated red luminescence of two lithium lanthanum tantalates via three mechanisms: (1) Eu-doping, (2) Mn-doping and (3) self-activation of the tantalum polyhedra. Of these three mechanisms, Mn-doping proved to be the most promising. These materials exhibit two very broad adsorption peaks; one in the UV and one in the blue region of the spectrum; both can be exploited in LED applications. Furthermore, Mn-doping can be accomplished in two ways; ion-exchange and direct solid-state synthesis. One of the two lithium lanthanum tantalate phases investigated proved to be a superior host for Mn-luminescence, suggesting the crystal chemistry of the host lattice is important.

  10. Tuning the diurnal natural daylight with phosphor converted white LED – Advent of new phosphor blend composition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yoon Hwa [School of Materials Science and Engineering, Chonnam National University, 300, Yongbong-dong, Buk-gu, Gwangju 500-757 (Korea, Republic of); Research Institute, Force4 Corp., Daechon-dong, Buk-gu, Gwangju 500-470 (Korea, Republic of); Arunkumar, Paulraj [School of Materials Science and Engineering, Chonnam National University, 300, Yongbong-dong, Buk-gu, Gwangju 500-757 (Korea, Republic of); Park, Seung Hyok; Yoon, Ho Shin [Research Institute, Force4 Corp., Daechon-dong, Buk-gu, Gwangju 500-470 (Korea, Republic of); Im, Won Bin, E-mail: imwonbin@jnu.ac.kr [School of Materials Science and Engineering, Chonnam National University, 300, Yongbong-dong, Buk-gu, Gwangju 500-757 (Korea, Republic of)

    2015-03-15

    Highlights: • Designed phosphor blend that mimics diurnal daylight for health benefits. • Developed new phosphor blend composition that mimics natural sunlight under near UV. • The phosphor blend also exhibits high CRI (≥90) under blue LED excitation. • Fabricated WLED exhibited ∼91% spectral resemblance with daylight at 4500 K. • While ∼39.2% spectral resemblance were observed for YAG:Ce{sup 3+} at 4500 K. - Abstract: We demonstrate the feasibility of developing phosphor converted white LED (pc-WLED) that mimics diurnal natural daylight with the newly designed phosphor blend in the color temperature (CCT) 2700–6000 K for health benefits. Natural daylight (sunlight) spectrum possesses broad emission in the visible region and closely approximates black body radiator, with color rendition index (CRI) of 100 under wide CCT (2500–6500 K). Current white light LEDs although are efficient and durable, they are not broad enough compared to daylight. We report new phosphor blend based on Sr{sub 3}MgSi{sub 2}O{sub 8}:Eu{sup 2+} blue phosphor with broad emission and high CRI ≥ 96 under both near UV and blue excitation. The fabricated WLED has exhibited ∼91% spectral resemblance with natural daylight compared to 39.2% for YAG:Ce{sup 3+} white LED at 4500 K. The developed phosphor blend tunes the spectrum in wider CCT and would be a prospective candidate for full spectrum daylight WLED.

  11. Bifunctional ferromagnetic Eu-Gd-Bi-codoped hybrid organo-silica red emitting phosphors synthesized by a modified Pechini sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Abo-Naf, S.M., E-mail: sm.abo-naf@nrc.sci.eg [Glass Research Department, National Research Centre (NRC), El-Buhouth Str., Dokki, 12622 Cairo (Egypt); Abdel-Hameed, S.A.M.; Marzouk, M.A. [Glass Research Department, National Research Centre (NRC), El-Buhouth Str., Dokki, 12622 Cairo (Egypt); Hamdy, Y.M. [Spectroscopy Department, National Research Centre (NRC), El-Buhouth Str., Dokki, 12622 Cairo (Egypt)

    2017-06-15

    Red phosphor, composed of Eu-Gd-Bi-codoped hybrid organo-silica glass, has been synthesized via a modified Pechini sol-gel process. The synthesized hybrid glass was analyzed with powder X-ray diffraction (XRD), differential thermal analysis coupled with thermogravimetry (DTA-TG) and Fourier transform infrared (FTIR) spectroscopy. XRD and DTA-TG confirmed its amorphous structure up to 1000 °C. Magnetic behavior of the produced phosphor was investigated using vibrating specimen magnetometer (VSM) and the obtained results revealed its unsaturated ferromagnetic behavior. Photoluminescence (PL) properties of the obtained phosphor have been investigated under near-UV excitation at 395 nm. The influence of calcination temperature on the PL intensity and its decay behavior as well as on the ferromagnetic characteristics has been studied to determine the optimal reaction temperature of the phosphor. The PL emission spectra show the characteristic emission bands of Eu{sup 3+} ions in the wavelength range from 580 to 700 nm. These emission spectra have been dominated by the electric dipole {sup 5}D{sub 0}→{sup 7}F{sub 2} transition of the Eu{sup 3+} peaked at 610–620 nm producing the red light emission of the phosphors. It was found that the phosphor performance, expressed by its PL intensity and life time, could be significantly improved by increasing of the heat treatment temperature up to 900 °C. Also, calcination at 900 °C for 6 h greatly increased both of the magnetization and retentivity, while decreased the coercivity value. The organic phenomenon of metal citrate-ethylene glycol chelation and its degradation by calcination were well followed by FTIR spectroscopy. The obtained results are promising and could afford a basis for designing of efficient red phosphors for displays, lighting and bifunctional biosensors for biomedical applications. - Highlights: • Eu-Gd-Bi-codoped hybrid organo-silica phosphor was synthesized by sol-gel method. • Inorganic Eu

  12. SU-E-T-610: Phosphor-Based Fiber Optic Probes for Proton Beam Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Darafsheh, A; Soldner, A; Liu, H; Kassaee, A; Zhu, T; Finlay, J [Univ Pennsylvania, Philadelphia, PA (United States)

    2015-06-15

    Purpose: To investigate feasibility of using fiber optics probes with rare-earth-based phosphor tips for proton beam radiation dosimetry. We designed and fabricated a fiber probe with submillimeter resolution (<0.5 mm3) based on TbF3 phosphors and evaluated its performance for measurement of proton beam including profiles and range. Methods: The fiber optic probe with TbF3 phosphor tip, embedded in tissue-mimicking phantoms was irradiated with double scattering proton beam with energy of 180 MeV. Luminescence spectroscopy was performed by a CCD-coupled spectrograph to analyze the emission spectra of the fiber tip. In order to measure the spatial beam profile and percentage depth dose, we used singular value decomposition method to spectrally separate the phosphors ionoluminescence signal from the background Cerenkov radiation signal. Results: The spectra of the TbF3 fiber probe showed characteristic ionoluminescence emission peaks at 489, 542, 586, and 620 nm. By using singular value decomposition we found the contribution of the ionoluminescence signal to measure the percentage depth dose in phantoms and compared that with measurements performed with ion chamber. We observed quenching effect at the spread out Bragg peak region, manifested as under-responding of the signal, due to the high LET of the beam. However, the beam profiles were not dramatically affected by the quenching effect. Conclusion: We have evaluated the performance of a fiber optic probe with submillimeter resolution for proton beam dosimetry. We demonstrated feasibility of spectral separation of the Cerenkov radiation from the collected signal. Such fiber probes can be used for measurements of proton beams profile and range. The experimental apparatus and spectroscopy method developed in this work provide a robust platform for characterization of proton-irradiated nanophosphor particles for ultralow fluence photodynamic therapy or molecular imaging applications.

  13. High Efficiency Colloidal Quantum Dot Phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Kahen, Keith

    2013-12-31

    The project showed that non-Cd containing, InP-based nanocrystals (semiconductor materials with dimensions of ~6 nm) have high potential for enabling next-generation, nanocrystal-based, on chip phosphors for solid state lighting. Typical nanocrystals fall short of the requirements for on chip phosphors due to their loss of quantum efficiency under the operating conditions of LEDs, such as, high temperature (up to 150 °C) and high optical flux (up to 200 W/cm2). The InP-based nanocrystals invented during this project maintain high quantum efficiency (>80%) in polymer-based films under these operating conditions for emission wavelengths ranging from ~530 to 620 nm. These nanocrystals also show other desirable attributes, such as, lack of blinking (a common problem with nanocrystals which limits their performance) and no increase in the emission spectral width from room to 150 °C (emitters with narrower spectral widths enable higher efficiency LEDs). Prior to these nanocrystals, no nanocrystal system (regardless of nanocrystal type) showed this collection of properties; in fact, other nanocrystal systems are typically limited to showing only one desirable trait (such as high temperature stability) but being deficient in other properties (such as high flux stability). The project showed that one can reproducibly obtain these properties by generating a novel compositional structure inside of the nanomaterials; in addition, the project formulated an initial theoretical framework linking the compositional structure to the list of high performance optical properties. Over the course of the project, the synthetic methodology for producing the novel composition was evolved to enable the synthesis of these nanomaterials at a cost approximately equal to that required for forming typical conventional nanocrystals. Given the above results, the last major remaining step prior to scale up of the nanomaterials is to limit the oxidation of these materials during the tens of

  14. Multilayer design of hybrid phosphor film for application in LEDs

    Science.gov (United States)

    Güner, Tuğrul; Köseoğlu, Devrim; Demir, Mustafa M.

    2016-10-01

    Crosslinked polydimethylsiloxane (PDMS) composite coatings containing luminescent micrometer-sized yellow Y3Al5O12:Ce3+ (YAG:Ce3+) particles were prepared by spraying for potential applications in solid-state lighting. Blue light was down converted by phosphor particles to produce white light, yet poor color properties of YAG:Ce3+ stemmed from a deficiency of red. When nitride-based red phosphor was simply blended into the system, the electrostatic interaction of negatively charged YAG:Ce3+ and positively charged red phosphor particles caused remarkable clustering and heterogeneity in particle dispersion. Consequently, the light is dominantly blue and shifted to cold white. In other case, phosphor particles were sprayed onto the diffused polycarbonate substrate in stacked layers. Coatings with >80% inorganic content by mass with a thickness of 60 μm were subjected to thermal crosslinking, which the presence of the phosphor particles obstructed, presumably due to the hindrance of large phosphor particles in the diffusion of PDMS precursors. The coating of YAG:Ce3+ first followed by red phosphor in stacked layers produced better light output and color properties than the coating obtained by spraying the mixture at once. Monte Carlo simulation validated the hypothesis.

  15. Alveolar bone measurement precision for phosphor-plate images

    Science.gov (United States)

    HILDEBOLT, CHARLES F.; COUTURE, REX; GARCIA, NATHALIA M.; DIXON, DEBRA; SHANNON, WILLIAM DOUGLAS; LANGENWALTER, ERIC; CIVITELLI, ROBERTO

    2009-01-01

    Objectives To demonstrate methods for determining measurement precision and to determine the precision of alveolar-bone measurements made with a vacuum-coupled, positioning device and phosphor-plate images. Study design Subjects were rigidly attached to the x-ray tube by means of a vacuum coupling device and custom, cross-arch, bite plates. Original and repeat radiographs (taken within minutes of each other) were obtained of the mandibular posterior teeth of 51 subjects, and cementoenamel-junction-alveolar-crest (CEJ-AC) distances were measured on both sets of images. In addition, x-ray-transmission (radiodensity) and alveolar-crest-height differences were determined by subtracting one image from the other. Image subtractions and measurements were performed twice. Based on duplicate measurements, the root-mean-square standard deviation (precision) and least-significant change (LSC) were calculated. LSC is the magnitude of change in a measurement needed to indicate that a true biological change has occurred. Results The LSCs were 4% for x-ray transmission, 0.49 mm for CEJ-AC distance, and 0.06 mm for crest-height 0.06 mm. Conclusion The LSCs for our CEJ-AC and x-ray transmission measurements are similar to what has been reported. The LSC for alveolar-crest height (determined with image subtraction) was less than 0.1 mm. Compared with findings from previous studies, this represents a highly precise measurement of alveolar crest height. The methods demonstrated for calculating LSC can be used by investigators to determine how large changes in radiographic measurements need to be before the changes can be considered (with 95% confidence) true biological changes and not noise (that is, equipment/observer error). PMID:19716499

  16. Characterization of lithium phosphorous oxynitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiaohua; Bates, J.B.; Jellison, G.E. Jr.

    1996-01-01

    Electrical and electrochemical properties of an amorphous thin-film lithium electrolyte, lithium phosphorous oxynitride (Lipon), have been studied with emphasis on the stability window vs Li metal and the behavior of the Li/Lipon interface. Ion conductivity of Lipon exhibits Arrhenius behavior at {minus}26 to +140 C, with a conductivity of 1.7 {times} 10{sup {minus}6}S/cm at 25 C and an activity energy of 0.50 {plus_minus} 0.01 eV. A stability window of 5.5 V was observed with respect to a Li{sup +}/Li reference, and no detectable reaction or degradation was evident at the Li/Lipon interface upon lithium cycling.

  17. Photoluminescence Characteristics of Yag:Ce, Gd Based Phosphors with Different Prehistories

    Science.gov (United States)

    Lisitsyn, V. M.; Soshchin, N. P.; Yang yang, Yu; Stepanov, S. A.; Lisitsyna, L. A.; Tulegenova, A. T.; Abdullin, Kh. A.

    2017-09-01

    Luminescence characteristics of yttrium-aluminum garnet based phosphor samples differed by their elemental composition and prehistory of synthesis are studied. The morphology, structure, and elemental composition of phosphor samples, their excitation and emission spectra, efficiency of phosphor conversion of chip emission, and kinetics of luminescence decay are measured. The emission characteristics of phosphors are compared with their structural properties and elemental composition.

  18. Efficient and Color-Tunable Oxyfluoride Solid Solution Phosphors for Solid-State White Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Im, Won Bin; George, Nathan; Kurzman, Joshua; Brinkley, Stuart; Mikhailovsky, Alexander; Hu, Jerry; Chmelka, Bradley F.; DenBaars, Steven P.; Seshadri, Ram (UCSB)

    2012-09-06

    A solid solution strategy helps increase the efficiency of Ce{sup 3+} oxyfluoride phosphors for solid-state white lighting. The use of a phosphor-capping architecture provides additional light extraction. The accompanying image displays electroluminescence spectra from a 434-nm InGaN LED phosphor that has been capped with the oxyfluoride phosphor.

  19. Optimized Phosphors for Warm White LED Light Engines

    Energy Technology Data Exchange (ETDEWEB)

    Setlur, Anant; Brewster, Megan; Garcia, Florencio; Hill, M. Christine; Lyons, Robert; Murphy, James; Stecher, Tom; Stoklosa, Stan; Weaver, Stan; Happek, Uwe; Aesram, Danny; Deshpande, Anirudha

    2012-07-30

    The objective of this program is to develop phosphor systems and LED light engines that have steady-state LED efficacies (using LEDs with a 60% wall-plug efficiency) of 105–120 lm/W with correlated color temperatures (CCT) ~3000 K, color rendering indices (CRI) >85, <0.003 distance from the blackbody curve (dbb), and <2% loss in phosphor efficiency under high temperature, high humidity conditions. In order to reach these goals, this involves the composition and processing optimization of phosphors previously developed by GE in combination with light engine package modification.

  20. Proton Conductivity in Phosphoric Acid: The Role of Quantum Effects

    Science.gov (United States)

    Heres, M.; Wang, Y.; Griffin, P. J.; Gainaru, C.; Sokolov, A. P.

    2016-10-01

    Phosphoric acid has one of the highest intrinsic proton conductivities of any known liquids, and the mechanism of this exceptional conductivity remains a puzzle. Our detailed experimental studies discovered a strong isotope effect in the conductivity of phosphoric acids caused by (i) a strong isotope shift of the glass transition temperature and (ii) a significant reduction of the energy barrier by zero-point quantum fluctuations. These results suggest that the high conductivity in phosphoric acids is caused by a very efficient proton transfer mechanism, which is strongly assisted by quantum effects.

  1. Reduced graphene oxide enwrapped phosphors for long-term thermally stable phosphor converted white light emitting diodes

    Science.gov (United States)

    Anoop, Gopinathan; Rani, Janardhanan R.; Lim, Juhwan; Jang, Myoung Soo; Suh, Dong Wook; Kang, Shinill; Jun, Seong Chan; Yoo, Jae Soo

    2016-09-01

    The long-term instability of the presently available best commercial phosphor-converted light-emitting diodes (pcLEDs) is the most serious obstacle for the realization of low-cost and energy-saving lighting applications. Emission from pcLEDs starts to degrade after approximately 200 h of operation because of thermal degradation of the phosphors. We propose a new strategy to overcome this thermal degradation problem of phosphors by wrapping the phosphor particles with reduced graphene oxide (rGO). Through the rGO wrapping, we have succeeded in controlling the thermal degradation of phosphors and improving the stability of fabricated pcLEDs. We have fabricated pcLEDs with long-term stability that maintain nearly 98% of their initial luminescence emission intensity even after 800 h of continuous operation at 85 °C and 85% relative humidity. The pcLEDs fabricated using SrBaSi2O2N2:Eu2+ phosphor particles wrapped with reduced graphene oxide are thermally stable because of enhanced heat dissipation that prevents the ionization of Eu2+ to Eu3+. We believe that this technique can be applied to other rare-earth doped phosphors for the realization of highly efficient and stable white LEDs.

  2. Reduced graphene oxide enwrapped phosphors for long-term thermally stable phosphor converted white light emitting diodes

    Science.gov (United States)

    Anoop, Gopinathan; Rani, Janardhanan R.; Lim, Juhwan; Jang, Myoung Soo; Suh, Dong Wook; Kang, Shinill; Jun, Seong Chan; Yoo, Jae Soo

    2016-01-01

    The long-term instability of the presently available best commercial phosphor-converted light-emitting diodes (pcLEDs) is the most serious obstacle for the realization of low-cost and energy-saving lighting applications. Emission from pcLEDs starts to degrade after approximately 200 h of operation because of thermal degradation of the phosphors. We propose a new strategy to overcome this thermal degradation problem of phosphors by wrapping the phosphor particles with reduced graphene oxide (rGO). Through the rGO wrapping, we have succeeded in controlling the thermal degradation of phosphors and improving the stability of fabricated pcLEDs. We have fabricated pcLEDs with long-term stability that maintain nearly 98% of their initial luminescence emission intensity even after 800 h of continuous operation at 85 °C and 85% relative humidity. The pcLEDs fabricated using SrBaSi2O2N2:Eu2+ phosphor particles wrapped with reduced graphene oxide are thermally stable because of enhanced heat dissipation that prevents the ionization of Eu2+ to Eu3+. We believe that this technique can be applied to other rare-earth doped phosphors for the realization of highly efficient and stable white LEDs. PMID:27671271

  3. Method to produce nanocrystalline powders of oxide-based phosphors for lighting applications

    Science.gov (United States)

    Loureiro, Sergio Paulo Martins; Setlur, Anant Achyut; Williams, Darryl Stephen; Manoharan, Mohan; Srivastava, Alok Mani

    2007-12-25

    Some embodiments of the present invention are directed toward nanocrystalline oxide-based phosphor materials, and methods for making same. Typically, such methods comprise a steric entrapment route for converting precursors into such phosphor material. In some embodiments, the nanocrystalline oxide-based phosphor materials are quantum splitting phosphors. In some or other embodiments, such nanocrystalline oxide based phosphor materials provide reduced scattering, leading to greater efficiency, when used in lighting applications.

  4. Impact of extinction coefficient of phosphor on thermal load of color conversion elements of phosphor converted LEDs

    Institute of Scientific and Technical Information of China (English)

    F.P. Wenzl; G. Langer; J. Nicolics; P. Fulmek; C. Sommer; S. Schweitzer; W. Nemitz; P. Hartmann; P. Pachler; H. Hoschopf; F. Schrank

    2014-01-01

    Besides their direct impact on the respective correlated color temperature, the extinction coefficient and the quantum effi-ciency of the phosphor also have tremendous impact on the thermal load of the color conversion elements of phosphor converted LEDs under operation. Because of the low thermal conductivity of the silicone matrix in which the phosphor particles are typically embedded, the by far highest temperatures within the LED assembly are reached within the color conversion element. Based on a combined optical and thermal simulation procedure we show that in particular a larger value for the extinction coefficient might have a beneficial impact on the resulting thermal load.

  5. Photostimulated luminescence properties of Eu2+ -doped barium aluminate phosphor.

    Science.gov (United States)

    He, Quanlong; Qiu, Guangyu; Xu, Xuhui; Qiu, Jianbei; Yu, Xue

    2015-03-01

    An intense green photostimulated luminescence in BaAl2 O4 :Eu(2+) phosphor was prepared. The thermoluminescence results indicate that there are at least three types of traps (T1 , T2 , T3 ) with different trap depths in BaAl2 O4 :Eu(2+) phosphor according to the bands located at 327, 361 and 555 K, respectively, which are closely associated with the phosphor's long persistent luminescence and photostimulated luminescence properties. In addition, as a novel optical read-out form, a photostimulated persistent luminescence signal can be repeatedly obtained in BaAl2 O4 :Eu(2+) phosphor. This shows that re-trapping of the electron released from a deep trap plays an important role in photostimulated persistent luminescence.

  6. Research on optical biosensor with up-converting phosphor marker

    Institute of Scientific and Technical Information of China (English)

    Yongkai Zhao; Xiangzhao Wang; Lei Zhou; Jing Wang; Lihua Huang; Zhongqiang Yan; Huijie Huang; Ruifu Yang; Lei Liu; Bingqiang Ren

    2006-01-01

    @@ An optical biosensor with up-converting phosphor (UCP) marker is developed for the sensitive rapid immunoassay to the specific biomolecule. UCP can emit visible light when excited by infrared light.

  7. Combustion synthesis of YAG:Ce and related phosphors

    Science.gov (United States)

    Gupta, K. V. K.; Muley, A.; Yadav, P.; Joshi, C. P.; Moharil, S. V.

    2011-11-01

    YAG:Ce is an important phosphor having applications in various fields ranging from solid state lighting to scintillation detectors. YAG phosphors doped with activators are mainly synthesized by solid state reaction techniques that require high sintering temperatures (above 1500°C) to eliminate YAM and YAP phases. Though several soft chemical routes have been explored for synthesis of YAG, most of these methods are complex and phase pure materials are not obtained in one step, but prolonged annealing at temperatures around 1000°C or above become necessary. One step combustion synthesis of YAG:Ce3+ and related phosphors carried out at 500°C furnace temperature is reported here. Activation with Ce3+ could be achieved during the synthesis without taking recourse to any post-combustion thermal treatment. LEDs prepared from the combustion synthesized YAG:Ce3+, exhibited properties comparable to those produced from the commercial phosphor.

  8. Inorganic phosphors in lead-silicate glass for white LEDs

    Science.gov (United States)

    Nikonorov, N. V.; Kolobkova, E. V.; Aseev, V. A.; Bibik, A. Yu.; Nekrasova, Ya. A.; Tuzova, Yu. V.; Novogran, A. I.

    2016-09-01

    Luminescent composites of the "phosphor-in-glass" type, based on a highly reflective lead-silicate matrix and fine-grained powders of YAG:Ce3+ and SiAlON:Eu2+ crystals, are developed and synthesized. Phosphor and glass powders are sintered at a temperature of 550°C to obtain phosphor samples for white LEDs. The composites are analyzed by X-ray diffraction and luminescence spectroscopy. The dependence of the light quantum yield on the SiAlON:Eu2+ content in the samples is investigated. A breadboard of a white LED is designed using a phosphor-in-glass composite based on lead-silicate glass with a low glasstransition temperature. The total emission spectra of a blue LED and glass-based composites are measured. The possibility of generating warm white light by choosing an appropriate composition is demonstrated.

  9. Progress in phosphors and filters for luminescent solar concentrators

    OpenAIRE

    De Boer, D.K.G.; Broer, D. J.; Debije, M.G.; Keur, W.; Meijerink, A.|info:eu-repo/dai/nl/075044986; Ronda, R.C.; Verbunt, P.P.C.

    2012-01-01

    Luminescent solar concentrators would allow for high concentration if losses by reabsorption and escape could be minimized. We introduce a phosphor with close-to-optimal luminescent properties and hardly any reabsorption. A problem for use in a luminescent concentrator is the large scattering of this material; we discuss possible solutions for this. Furthermore, the use of broad-band cholesteric filters to prevent escape of luminescent radiation from this phosphor is investigated both experim...

  10. Improved yellow phosphors for solid state white lighting

    Science.gov (United States)

    Yadav, P. J.; Meshram, N. D.; Joshi, C. P.; Moharil, S. V.

    2016-05-01

    Most of the commercial white LED lamps use blue chip coated with yellow emitting phosphor. YAG:Ce3+ phosphor is coated on blue chip to obtain white light. Though this is commercially successful, there are several drawbacks such as "halo effect", poor colour rendition, etc. In recent years several efforts have been made to improve LED lamp performance. These may be classified as 1> finding replacement for YAG:Ce and 2> improving performance of YAG:Ce.

  11. Development of Trichromatic Phosphor for Lamp in China(Continued)

    Institute of Scientific and Technical Information of China (English)

    WU Hong

    2008-01-01

    @@ Recent developments of fluorescent lamps in China and in the world 1.Energy saving fluorescent lamps with high luminous efficiency and high color rendering To further improve the color rendering and achieve a good combination of luminous efficiency,photochromism,color rendering property and lifespan of narrow-band rare earth trichromatic phosphor,the multi-composition phosphor is prepared by increasing compositions with emission wave length between 480-520nm and over 620nm.

  12. Materials characterization of phosphoric acid fuel cell system

    Science.gov (United States)

    Venkatesh, Srinivasan

    1986-01-01

    The component materials used in the fabrication of phosphoric acid fuel cells (PAFC) must have mechanical, chemical, and electrochemical stability to withstand the moderately high temperature (200 C) and pressure (500 kPa) and highly oxidizing nature of phosphoric acid. This study discusses the chemical and structural stability, performance and corrosion data on certain catalysts, catalyst supports, and electrode support materials used in PAFC applications.

  13. Ba2Mg(BO3)2:Ce3+,Eu2+,Na+: A potential single-phased two colour borate phosphor for white light-emitting diodes

    Institute of Scientific and Technical Information of China (English)

    PAN Zaifa; XU Juan; ZHU Chengjing; LIU Wenhan; WANG Lili

    2012-01-01

    A two colour phosphor Ba2Mg(BO3)2:Ce3+,Eu2+,Na+ was synthesized using solid-state reaction method.Luminescence of Ba2Mg(BO3)2:Ce3+,Eu2+,Na+ showed 416 and 618 nm emission bands attributed to Ce3+ and Eu2+ emission,respectively.Energy transfer occurred from Ce3+ to Eu2+ through a significant overlap of Eu2+ excitation spectrum with Ce3+ emission spectrum in Ba2Mg(BO3)2.They also showed that under the excitation of UV radiation,bluish or yellowish white light was generated by coupling a broad blue emission band and a red emission band.By combining with green phosphor,Ba2Mg(BO3):Ce3+,Eu2+,Na+ phosphor showed potential application for white light-emitting diodes (LEDs).

  14. Light Converting Inorganic Phosphors for White Light-Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Chiao-Wen Yeh

    2010-03-01

    Full Text Available White light-emitting diodes (WLEDs have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV LEDs and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED or polymer light-emitting diode (PLED, have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability and long operating lifetime. To meet with the further requirement of high color rendering index, warm light with low color temperature, high thermal stability and higher energy efficiency for WLEDs, new phosphors that can absorb excitation energy from blue or nUV LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450-480 nm and nUV (380-400 nm LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance of light between the emission from blue-nUV LEDs and the emissions from phosphors (such as yellow from Y3Al5O12:Ce3+ is important to obtain white light with proper color rendering index and color temperature. Here, we will review the status of phosphors for LEDs and prospect the future development.

  15. Microbial contamination in intraoral phosphor storage plates: the dilemma.

    Science.gov (United States)

    de Souza, Tricia Murielly Pereira Andrade; de Castro, Ricardo Dias; de Vasconcelos, Laís César; Pontual, Andréa Dos Anjos; de Moraes Ramos Perez, Flávia Maria; Pontual, Maria Luiza Dos Anjos

    2017-01-01

    The aims of this study were to evaluate microbial contamination in phosphor storage plates in dental radiology services and discuss the possible origin of this contamination. The sample comprised 50 phosphor plates: 14 plates from service A, 30 from service B, and 6 in the control group, consisting of plates never used. Damp sterile swabs were rubbed on the phosphor plates, and then transferred to tests tubes containing sterile saline solution. Serial dilutions were made, and then inoculated in triplicate on Mueller Hinton agar plates and incubated at 37 °C/48 h, before counting the colony-forming units (CFU). The samples were also seeded in brain-heart infusion medium to confirm contamination by turbidity of the culture medium. All solutions, turbid and clean, were seeded in selective and non-selective media. At service A and B, 50 and 73.3 % of the phosphor plates were contaminated, respectively. This contamination was mainly due to bacteria of the genus Staphylococcus. CFU counts ranged from 26.4 to 80.0 CFU/plate. Most of the phosphor plates evaluated shown to be contaminated, mainly by Staphylococcus ssp. Quantitatively, this contamination occurred at low levels, possibly arising from handling of the plates. The use of a second plastic barrier may have diminished contamination by microorganisms from the oral cavity. There is a risk of cross-contamination by phosphor storage plates used in dental radiology services.

  16. Thermoluminescence characteristics of LiF: Cu nanocrystalline phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Seth, Pooja, E-mail: pujaseth05@gmail.com; Aggarwal, Shruti [University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, New Delhi (India)

    2016-05-23

    Copper (Cu) activated LiF phosphor in nanocrystalline form has been prepared by the chemical co-precipitation method for radiation dosimetry application. The formation of nanocrystalline structure has been confirmed by X-ray diffraction and Scanning electron microscopy. Cubical shaped nanostructure with average particle size of 33nm has been formed. The sample was prepared at different concentration of Cu from 0.01mol% to 3 mol%. TL properties were investigated by studying the glow curve after irradiating the phosphor to gamma ray Co{sup 60} source with dose of 15 Gy. It has been found that nanocrystalline LiF: Cu show simple glow curve structure with a single glow peak at 404 K where as commercially available phosphors exhibits multi peak complex glow curve structure. The effect of different normality on the TL properties of phosphor has been studied. Maximum TL intensity for LiF: Cu (0.1mol %) phosphor is observed at the normality of 0.5N and annealing temperature of 200°C. The phosphor showed good linearity up to 10 KGy.

  17. Measurement of Quenching Factor for Nuclear Recoils in CsI(Tl) Crystal%CsI(Tl)晶体中反冲Cs和I核Quenching Factor的测量

    Institute of Scientific and Technical Information of China (English)

    岳骞; 李金; 刘延; 李浩斌; 王子敬; 王名儒

    2002-01-01

    Detection of dark matter using CsI(Tl) scintillating crystal as the detector has gathered more and more interests. In this paper, the quenching factor of nuclear recoils induced by incident neutron beam was measured based on Pulse Shape Discrimination (PSD) method to identify events of nuclear recoils from background. It is shown that the quenching factor increases with the decreased recoil energy in the range of 7 keV to 132 keV. This result shows the great advantage of CsI(Tl) crystal detector in detecting of dark matter.%许多实验对用CsI(Tl)闪烁晶体作为探测器来寻找和探测暗物质的可行性进行了研究. 本工作利用8MeV单能中子轰击CsI(Tl)晶体探测器来研究Cs核和I核的Quenching Factor. 在数据处理中,运用脉冲形状甄别(PSD)方法来分辨反冲核信号和本底信号. 实验结果表明,在7keV到132keV的能区中,Quenching Factor随着反冲核能量的减少而增加. 在探测暗物质的实验中,这一性质对于CsI(Tl)晶体探测器获得较低的能量阈值是很有利的.

  18. Development of surgical gamma probes with TlBr semiconductors and CsI(Tl) scintillators crystals; Desenvolvimento de sondas cirurgicas radioguiadas com semicondutores de TlBr e com cristais cintiladores de CsI (Tl)

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Fabio Eduardo da

    2006-07-01

    Radio guided surgery, using probes with radiation detectors, has been prominence in the medical area in the last decade. This technique consists in injecting a radioactive substance to concentrate in tumour and assist the localization during the surgical procedure. The radio guided surgeries allowing the identification of lymph node has revolutioned the behavior of tumour in initial stadium when are being spread by lymphatic way. The conditions imposed to the surgery due the proximity between some lymph nodes, demands of the probes, a small diameters and capacity of individual identification of these lymph nodes radiolabelled by a specific tracer. The international market supplies these probes with CdTe semiconductors and scintillators, but there is some time lack a promptly technical assistance in the Brazilian market. This work developed probes with national technology, using CsI(Tl) scintillators crystals and, in substitution to CdTe crystals semiconductors, the TlBr crystal, that is a new semiconductor detector in a world-wide development, with advantages in relation to the CdTe. Both crystals have been grown in IPEN. All the necessary electronics, specially, the preamplifier, that was also a restrictive factor for development of these types of probe in the country, have been developed with components found in the national market. Systematic measures of spatial resolution, spatial selectivity, maximum sensitivity and quality of the shielding have been carried the probes development. The results have shown that the probes, one with the CsI(Tl) crystal and another with TlBr semiconductor presented the requested performance in the international literature for radio guided probes. (author)

  19. The development of silicate matrix phosphors with broad excitation band for phosphor-convered white LED

    Institute of Scientific and Technical Information of China (English)

    LUO XiXian; CAO WangHe; SUN Fei

    2008-01-01

    This paper briefly reviews the recent progress in alkaline earth silicate host luminescent materials with broad excitation band for phosphor-convered white LED. Among them, the Sr-rich binary phases (Sr, Ba, Ca, Mg)2SiO4: Eu2+ and (Sr, Ba, Ca, Mg)3SiO5: Eu2+ are excellent phosphors for blue LED chip white LED. They have very broad excitation bands and exhibit strong absorption of blue radiation in the range of 450-480 nm. And they exhibit green and yellow-orange emission under the InGaN blue LED chip radiation, respectively. The luminous efficiency of InGaN-based (Sr, Ba, Ca, Mg)2SiO4: Eu2+ and (Sr, Ba, Ca, Mg)3SiO5: Eu2+ is about 70-80 lm/W, about 95%-105% that of the InGaN-based YAG:Ce, while the correlated color temperature is between 4600-11000 K. Trinary alkaline earth silicate host luminescent materials MO(M=Sr, Ca, Ba)-Mg(Zn)O-SiO2 show strong absorption of deep blue/near-ultraviolet radia-tion in the range of 370-440 nm. They can convert the deep blue/near-ultraviolet radiation into blue, green, and red emissions to generate white light. The realization of high-performance white-light LEDs by this approach presents excellent chromaticity and high color rendering index, and the application disadvantages caused by the mixture of various matrixes can be avoided. Moreover, the application prospects and the trends of research and development of alkaline earth silicate phosphors are also discussed.

  20. Technique of proton and phosphorous MR spectroscopy; Technik der Protonen- und Phosphor-MR-Spektroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Backens, M. [Universitaetsklinikum des Saarlandes, Klinik fuer Diagnostische und Interventionelle Neuroradiologie, Homburg/Saar (Germany)

    2017-06-15

    Magnetic resonance spectroscopy (MRS) is an important non-invasive method that can reveal the concentration and spatial distribution of particular biochemically relevant tissue metabolites. Proton MRS is routinely applicable in the clinical setting providing good quality results even with a moderate magnetic field strength of 1.5 T. Relative values of metabolite concentrations are mostly used for the assessment of metabolic disorders. Absolute quantification of metabolites can be achieved by means of internal or external reference scans. Phosphorous MRS extends the range of detectable molecules to energy and cell membrane metabolism. The lower detection limit of metabolite concentrations is in the range of some mmol/kg. Depending on the magnetic field strength, MRS enables a spatial resolution of a few milliliters. The use of phosphorous MRS is considerably limited because higher field strengths of at least 3.0 T and additional expensive hardware for signal processing are required. (orig.) [German] Die MR-Spektroskopie (MRS) ist eine wichtige nichtinvasive Untersuchungsmethode, die Konzentration und raeumliche Verteilung einiger biochemisch relevanter Metaboliten im Gewebe ermitteln kann. Die Protonenspektroskopie ist klinisch etabliert, in der Routine einfach durchfuehrbar und liefert bereits bei einer Magnetfeldstaerke von 1,5 T qualitativ gute Ergebnisse. Fuer die Beurteilung von Stoffwechselveraenderungen werden Metabolitenkonzentrationen meist als Relativwerte angegeben. Mithilfe interner oder externer Referenzmessungen sind auch absolute Metabolitenkonzentrationen berechenbar. Die Phosphorspektroskopie erweitert den Bereich der detektierbaren Molekuele auf den Energie- und Zellmembranstoffwechsel. Die minimale nachweisbare Metabolitenkonzentration liegt bei einigen mmol/kg. Abhaengig von der Magnetfeldstaerke ist eine raeumliche Aufloesung der MRS von wenigen Millilitern erreichbar. Der Einsatz der Phosphor-MRS wird dadurch erheblich eingeschraenkt, dass sie

  1. Discrete scintillator coupled mercuric iodide photodetector arrays for breast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tornai, M.P.; Levin, C.S.; Hoffman, E.J. [UCLA School of Medicine, Los Angeles, CA (United States)

    1996-12-31

    Multi-element (4x4) imaging arrays with high resolution collimators, size matched to discrete CsI(Tl) scintillator arrays and mercuric iodide photodetector arrays (HgI{sub 2} PDA) are under development as prototypes for larger 16 x 16 element arrays. The compact nature of the arrays allows detector positioning in proximity to the breast to eliminate activity not in the line-of-sight of the collimator, thus reducing image background. Short collimators, size matched to {le}1.5 x 1.5 mm{sup 2} scintillators show a factor of 2 and 3.4 improvement in spatial resolution and efficiency, respectively, compared to high resolution collimated gamma cameras for the anticipated compressed breast geometries. Monte Carlo simulations, confirmed by measurements, demonstrated that scintillator length played a greater role in efficiency and photofraction for 140 keV gammas than cross sectional area, which affects intrinsic spatial resolution. Simulations also demonstrated that an increase in the ratio of scintillator area to length corresponds to an improvement in light collection. Electronic noise was below 40 e{sup -} RMS indicating that detector resolution was not noise limited. The high quantum efficiency and spectral match of prototype unity gain HgI{sub 2} PDAs coupled to 1 x 1 x 2.5 mm{sup 3} and 2 x 2 x 4 mm{sup 3} CsI(Tl) scintillators demonstrated energy resolutions of 9.4% and 8.8% FWHM at 140 keV, respectively, without the spectral tailing observed in standard high-Z, compound semi-conductor detectors. Line spread function measurements matched the scintillator size and pitch, and small, complex phantoms were easily imaged.

  2. The effect of Tb+3 on α-Sr2P2O7 phosphor for green LED phosphor application

    Science.gov (United States)

    Patel, Nimesh P.; Srinivas, M.; Verma, Vishwnath; Modi, Dhaval

    2015-06-01

    A series of Tb+3 activated α-Sr2P2O7 (Strontium Pyrophosphate) phosphors were synthesized by high temperature combustion synthesis method. The structural analysis has been done by x-ray diffraction and FTIR (Fourier Transform Infrared Spectrum). The results obtained in structural characterization indicate that the doping concentration did not affect the crystal phase and structure of the phosphors. X-ray diffraction pattern reveals that the all samples were consistence with the JCPDS card No. 24-1011. The phosphor was excited at 232 nm wavelength, very intense PL green emission peak have been observed at 545 nm. This illustrates, that the phosphors could be efficiently excited because of the charge transfer band of the host as well as the energy transfer process occurred between host (Sr2P2O7) and activator (Tb+3). By increasing the doping concentration of Tb+3, the intensity of 545 nm emission peak has been increased predominantly and it suggest that the phosphor prepared has very good application in green LED phosphor.

  3. Storage phosphors for thermal neutron detection

    CERN Document Server

    Sidorenko, A V; Dorenbos, P; Le Masson, N J M; Rodnyi, P A; Eijk, C W E; Berezovskaya, I V; Dotsenko, V P

    2002-01-01

    The commercial BaFBr:Eu sup 2 sup +centre dot Gd sub 2 O sub 3 image plate (IP) is used nowadays for thermal neutron detection. However, it is rather sensitive to gamma-ray background, which can deteriorate the image quality. We focused our research on the development of new types of storage phosphors with the general formula M sub 2 B sub 5 O sub 9 Br:Ce sup 3 sup + (M=Sr, Ca). Neutron detection is based on the sup 1 sup 0 B(n,alpha) reaction. The advantages of this system are the low Z sub e sub f sub f , and the 40 times higher energy deposition resulting from the neutron capture reaction in comparison with that in the commercial IP. Here we present storage and spectroscopic properties of a series of newly synthesized haloborates. Comparative measurements with commercial IPs were done under neutron and beta irradiation. A satisfying light output of optically stimulated luminescence was achieved upon neutron irradiation.

  4. New applications for phosphoric acid fuel cells

    Science.gov (United States)

    Stickles, R. P.; Breuer, C. T.

    1983-01-01

    New applications for phosphoric acid fuel cells were identified and evaluated. Candidates considered included all possibilities except grid connected electric utility applications, on site total energy systems, industrial cogeneration, opportunistic use of waste hydrogen, space and military applications, and applications smaller than 10 kW. Applications identified were screened, with the most promising subjected to technical and economic evaluation using a fuel cell and conventional power system data base developed in the study. The most promising applications appear to be the underground mine locomotive and the railroad locomotive. Also interesting are power for robotic submersibles and Arctic villages. The mine locomotive is particularly attractive since it is expected that the fuel cell could command a very high price and still be competitive with the conventionally used battery system. The railroad locomotive's attractiveness results from the (smaller) premium price which the fuel cell could command over the conventional diesel electric system based on its superior fuel efficiency, and on the large size of this market and the accompanying opportunities for manufacturing economy.

  5. Phosphoric acid fuel cell platinum use study

    Science.gov (United States)

    Lundblad, H. L.

    1983-01-01

    The U.S. Department of Energy is promoting the private development of phosphoric acid fuel cell (PAFC) power plants for terrestrial applications. Current PAFC technology utilizes platinum as catalysts in the power electrodes. The possible repercussions that the platinum demand of PAFC power plant commercialization will have on the worldwide supply and price of platinum from the outset of commercialization to the year 2000 are investigated. The platinum demand of PAFC commercialization is estimated by developing forecasts of platinum use per unit of generating capacity and penetration of PAFC power plants into the electric generation market. The ability of the platinum supply market to meet future demands is gauged by assessing the size of platinum reserves and the capability of platinum producers to extract, refine and market sufficient quantities of these reserves. The size and timing of platinum price shifts induced by the added demand of PAFC commercialization are investigated by several analytical methods. Estimates of these price shifts are then used to calculate the subsequent effects on PAFC power plant capital costs.

  6. INORGANIC PHOSPHORS IN GLASS BASED ON LEAD SILICATE GLASSES

    Directory of Open Access Journals (Sweden)

    V. A. Aseev

    2014-09-01

    Full Text Available We created and synthesized luminescent composite of the "phosphor in glass" type, based on the lead-silicate matrix and fine-dispersed powder of cerium-activated yttrium-aluminum garnet crystal. Lead-silicate system (40SiO2- 20PbO-(40-x PbF2-xAlF3, x = 0-25 was chosen as the glassy matrix. Initial glass was reduced to powder (frit for "phosphor in glass" composite with a particle size about 50 µm. Glass frit and powder of commercial YAG:Ce3+ phosphor were mixed in a ratio of 30 to 70 (wt %. Then this composite was pressed in a tablet and sintered on a quartz substrate at 823 К for 30 minutes. Thus, the plane parallel sheet for composite of the "phosphor in glass" was obtained with a diameter equal to 10 mm. For the purpose to reduce the loss of light in the presence of dispersion at a glass-phosphor boundary, optimization of glass mixture was done by adjusting the refractive index. X-ray phase and spectral-luminescent analysis of the derived composite were done. The results of these studies showed that there was no degradation of YAG: Ce powder during sintering. Dependence of luminescence intensity from temperature in the range from room temperature to 473 К was studied. It was shown, that with the phosphor in glass usage thermal quenching of luminescence was reduced in comparison with the silicone. The model of white LED was created with the "phosphor in glass" composite based on lead-silicate glasses with low temperature of vitrifying. The derived LED emits white light with a color temperature of 4370 K, and the luminous efficiency is equal to 58 lm/W. The developed luminescent composite based on the lead-silicate matrix can be used for the production of high-power white light LED.

  7. Continuous depth-of-interaction encoding using phosphor-coated scintillators.

    Science.gov (United States)

    Du, Huini; Yang, Yongfeng; Glodo, Jarek; Wu, Yibao; Shah, Kanai; Cherry, Simon R

    2009-03-21

    We investigate a novel detector using a lutetium oxyorthosilicate (LSO) scintillator and YGG (yttrium-aluminum-gallium oxide:cerium, Y(3)(Al,Ga)(5)O(12):Ce) phosphor to construct a detector with continuous depth-of-interaction (DOI) information. The far end of the LSO scintillator is coated with a thin layer of YGG phosphor powder which absorbs some fraction of the LSO scintillation light and emits wavelength-shifted photons with a characteristic decay time of approximately 50 ns. The near end of the LSO scintillator is directly coupled to a photodetector. The photodetector detects a mixture of the LSO light and the light emitted by YGG. With appropriate placement of the coating, the ratio of the light converted from the YGG coating with respect to the unconverted LSO light can be made to depend on the interaction depth. DOI information can then be estimated by inspecting the overall light pulse decay time. Experiments were conducted to optimize the coating method. 19 ns decay time differences across the length of the detector were achieved experimentally when reading out a 1.5 x 1.5 x 20 mm(3) LSO crystal with unpolished surfaces and half-coated with YGG phosphor. The same coating scheme was applied to a 4 x 4 LSO array. Pulse shape discrimination (PSD) methods were studied to extract DOI information from the pulse shape changes. The DOI full-width-half-maximum (FWHM) resolution was found to be approximately 8 mm for this 2 cm thick array.

  8. Laser discrimination by stimulated emission of a phosphor

    Science.gov (United States)

    Mathur, V. K.; Chakrabarti, K.

    1991-01-01

    A method for discriminating sources of UV, near infrared, and far infrared laser radiation was discovered. This technology is based on the use of a single magnesium sulfide phosphor doubly doped with rare earth ions, which is thermally/optically stimulated to generate colors correlatable to the incident laser radiation. The phosphor, after initial charging by visible light, exhibits green stimulated luminescence when exposed to a near infrared source (Nd: YAG laser). On exposure to far infrared sources (CO2 laser) the phosphor emission changes to orange color. A UV laser produces both an orange red as well as green color. A device using this phosphor is useful for detecting the laser and for discriminating between the near infrared, far infrared, and UV lasers. The technology is also capable of infrared laser diode beam profiling since the radiation source leaves an imprint on the phosphor that can be photographed. Continued development of the technology offers potential for discrimination between even smaller bandwidths within the infrared spectrum, a possible aid to communication or wavemixing devices that need to rapidly identify and process optical signals.

  9. Detection of charged particles and X-rays by scintillator layers coupled to amorphous silicon photodiode arrays

    Energy Technology Data Exchange (ETDEWEB)

    Jing, T.; Drewery, J.; Hong, W.S.; Lee, H.; Kaplan, S.N.; Perez-Mendez, V. [Lawrence Berkeley Lab., CA (United States); Goodman, C.A.; Wildermuth, D. [Air Techniques, Inc. Hicksville, NY (United States)

    1995-04-01

    Hydrogenated amorphous silicon (a-Si:H) p-i-n diodes with transparent metallic contacts are shown to be suitable for detecting charged particles, electrons, and X-rays. When coupled to a suitable scintillator using CsI(Tl) as the scintillator we show a capability to detect minimum ionizing particles with S/N {approximately}20. We demonstrate such an arrangement by operating a p-i-n diode in photovoltaic mode (reverse bias). Moreover, we show that a p-i-n diode can also work as a photoconductor under forward bias and produces a gain yield of 3-8 higher light sensitivity for shaping times of 1 {mu}s. n-i-n devices have similar optical gain as the p-i-n photoconductor for short integrating times ( < 10{mu}s). However, n-i-n devices exhibit much higher gain for a long term integration (10ms) than the p-i-n ones. High sensitivity photosensors are very desirable for X-ray medical imaging because radiation exposure dose can be reduced significantly. The scintillator CsI layers we made have higher spatial resolution than the Kodak commercial scintillator screens due to their internal columnar structure which can collimate the scintillation light. Evaporated CsI layers are shown to be more resistant to radiation damage than the crystalline bulk CsI(Tl).

  10. Corrosion of titanium in phosphoric acid at 250 ℃

    Institute of Scientific and Technical Information of China (English)

    LU Jian-shu

    2009-01-01

    Corrosion studies of a commercially pure titanium in phosphoric acid solutions at 250 ℃ were carried out by immersion test in an autoclave. At lower phosphoric acid concentration (0.1 mol/L), the corrosion was mild. At higher phosphoric concentration (1.0 mol/L) corrosion, a 25 μm-thick white corrosion products layer was formed on the samples after 24 h immersion. XRD analysis shows that the white layer consists mainly of titanium oxide phosphate hydrate (π-Ti2O(PO4)2·2H2O). The corrosion product shows the morphology of fiber bundles. A thermodynamic analysis of the formation of the corrosion product is presented.

  11. Green chemistry-mediated synthesis of nanostructures of afterglow phosphor

    Science.gov (United States)

    Sharma, Pooja; Haranath, D.; Chander, Harish; Singh, Sukhvir

    2008-04-01

    Various nanostructures of SrAl 2O 4:Eu 2+, Dy 3+ (SAC) afterglow phosphor were prepared in a single-step reaction using a green chemistry-mediated modified combustion process. The evolution of hazardous NxOx gases during the customary combustion reaction was completely eliminated by employing an innovative complex formation route. Another fascinating feature of the process was that, a slight change in the processing conditions ensured the synthesis of either nanoparticles or nanowires. The photoluminescence spectrum of nanophosphor showed a slight blue shift in emission (˜511 nm) as compared to the bulk phosphor (˜520 nm). The afterglow (decay) profiles of SAC nanoparticles, nanowires and bulk phosphor were compared. The chemistry underlying the nanostructure synthesis and the probable afterglow mechanism were discussed.

  12. Hydrothermal preparation and persistence characteristics of nanosized phosphor SrS: Eu2+, Dy3+

    Institute of Scientific and Technical Information of China (English)

    DUAN Xiaoxia; HUANG Shihua; YOU Fangtian; KANG Kai

    2009-01-01

    Nanosized long-persistent phosphors SrS: Eu2+, Dy3+ were prepared by the hydrothermal method. The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and charge-coupled device spectrometry. The persistence characteristic was studied using the decay curves. The results showed that the emission intensity decreased sharply with temperature increasing, although the particle size increased. The S2- vacancies caused by oxidization served as shallow traps, and Dy3+ served as deep traps in SrS: Eu2+, Dy3+. The afterglow intensity of SrS: Eu2+, Dy3+ was higher than that of SrS: Eu2+ prepared at the same temperature. However, the minimization span of initial afterglow with temperature for the former sample was larger than that for the latter. Binary-doped phosphor decayed more slowly than the singly doped one. The afterglow of SrS: Eu2+, Dy3+ decayed more quickly with the increase of sintering temperature.

  13. Optical temperature sensing properties of Yb3+/Er3+ codoped LaF3 upconversion phosphor

    Science.gov (United States)

    Cheng, Xuerui; Ma, Xiaochun; Zhang, Huanjun; Ren, Yufen; Zhu, Kunkun

    2017-09-01

    The structural and optical properties of Er3+/Yb3+ codoped LaF3 phosphors are investigated using X-ray diffraction (XRD) and upconversion luminescence spectra. The result shows that the hexagonal phase of LaF3 keep stability at temperature lower than 800 °C in air condition and will be oxidized to be LaOF at higher temperature. Its upconversion emission intensity varies with the doping concentrations of Yb3+ ions and reaches a maximum at around 7 mol% Yb3+. The power-dependent luminescence reveals the possible emission mechanisms and the corresponding upconversion processes. Furthermore, the optical temperature sensing properties of LaF3: Er3+/Yb3+ are studied based on the fluorescence intensity ratio (FIR) technique for two thermally coupled levels (2H11/2 and 4S3/2) of Er3+. The maximum sensitivity is found to be about 0.00157 K-1 at 386 K, revealing this phosphor to be a promising prototype for applications in optical temperature sensing.

  14. Development of Up-Converting Phosphor Immunochromatography Test for Quantitative Detection of Sulfadiazin

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    An up-converting phosphor (UCP) immunochromatography test was developed for the detection of sulfadiazine (SD). The anti-SD monoclonal was conjugated to the up-converting phosphor particles while the SD-BSA immobilized on the

  15. Development of Up-Converting Phosphor Immunochromatography Test for Quantitative Detection of Enrofloxacin

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    An up-converting phosphor (UCP) immunochromatography test was developed for the detection of enrofloxacin (ENR). The anti-ENR monoclonal was conjugated to the up-converting phosphor particles while the ENR-BSA immobilized on the nitrocellulose membrane

  16. On the response of a europium doped phosphor-coated CMOS digital imaging detector

    Energy Technology Data Exchange (ETDEWEB)

    Seferis, I.E. [Department of Medical Physics, Faculty of Medicine, University of Patras, 26500 Patras (Greece); Michail, C.M.; Valais, I.G.; Fountos, G.P.; Kalyvas, N.I. [Department of Medical Instruments Technology, Technological Educational Institute (TEI) of Athens, Agios Spyridonos, 12210 Athens (Greece); Stromatia, F. [Department of Radiology and Nuclear Medicine, “IASO” General Hospital, Mesogion 264, 15562 Holargos (Greece); Oikonomou, G. [Department of Medical Radiological Technology, Faculty of Health and Caring Professions, Technological Educational Institute (TEI) of Athens, Agios Spyridonos, 12210 Athens (Greece); Kandarakis, I.S., E-mail: kandarakis@teiath.gr [Department of Medical Instruments Technology, Technological Educational Institute (TEI) of Athens, Agios Spyridonos, 12210 Athens (Greece); Panayiotakis, G.S. [Department of Medical Physics, Faculty of Medicine, University of Patras, 26500 Patras (Greece)

    2013-11-21

    Purpose: The purpose of the present study was to assess the information content of a high resolution active pixel CMOS imaging sensor coupled to Gd{sub 2}O{sub 2}S:Eu phosphor screens in terms of single index image quality metrics such as the information capacity (IC) and the noise equivalent passband (Ne). Methods: The CMOS sensor was coupled to two Gd{sub 2}O{sub 2}S:Eu scintillator screens with coating thicknesses of 33.3 and 65.1 mg/cm{sup 2}. IC and Ne were obtained by means of experimentally determined parameters such as the modulation transfer function (MTF), the detective quantum efficiency (DQE) and the noise equivalent quanta (NEQ). Measurements were performed using the standard IEC-RQA5 radiation beam quality (70 kVp) and a W/Rh beam quality (28 kVp). Results: It was found that the detector response function was linear for the exposure ranges under investigation. At 70 kVp, under the RQA 5 conditions IC values were found to range between 1730 and 1851 bits/mm{sup 2} and Ne values were found between 2.28 and 2.52 mm{sup −1}. At 28 kVp the corresponding IC values were found to range between 2535 and 2747 bits/mm{sup 2}, while the Ne values were found between 5.91 and 7.09 mm{sup −1}. Conclusion: IC and Ne of the red emitting phosphor/CMOS sensor combination were found with high values suggesting an acceptable imaging performance in terms of information content and sharpness, for X-ray digital imaging. -- Highlights: •Gd{sub 2}O{sub 2}S:Eu/CMOS combination has comparable image quality parameters to Gd{sub 2}O{sub 2}S:Tb/CMOS. •Information capacity was found with high values suggesting an acceptable imaging performance. •Red emitting phosphors coupled to silicon based optical sensors could be used in developing efficient imaging detectors.

  17. Progress in phosphors and filters for luminescent solar concentrators.

    Science.gov (United States)

    de Boer, Dick K G; Broer, Dirk J; Debije, Michael G; Keur, Wilco; Meijerink, Andries; Ronda, Cees R; Verbunt, Paul P C

    2012-05-07

    Luminescent solar concentrators would allow for high concentration if losses by reabsorption and escape could be minimized. We introduce a phosphor with close-to-optimal luminescent properties and hardly any reabsorption. A problem for use in a luminescent concentrator is the large scattering of this material; we discuss possible solutions for this. Furthermore, the use of broad-band cholesteric filters to prevent escape of luminescent radiation from this phosphor is investigated both experimentally and using simulations. Simulations are also used to predict the ultimate performance of luminescent concentrators.

  18. Technology development for phosphoric acid fuel cell powerplant (phase 2)

    Science.gov (United States)

    Christner, L.

    1979-01-01

    The status of technology for the manufacturing and testing of 1200 sq. cm cell materials, components, and stacks for on-site integrated energy systems is assessed. Topics covered include: (1) preparation of thin layers of silicon carbide; (2) definition and control schemes for volume changes in phosphoric acid fuel cells; (3) preparation of low resin content graphite phenolic resin composites; (4) chemical corrosion of graphite-phenolic resin composites in hot phosphoric acid; (5) analysis of electrical resistance of composite materials for fuel cells; and (6) fuel cell performance and testing.

  19. Beta and low-energy photon irradiation of several commercial phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Fix, J.J.; Holbrook, K.L.; Soldat, K.L.

    1983-02-01

    Several commercially available thermoluminescent phosphors were evaluated with respect to their observed response to selected beta sources and K-fluorescent x rays. Phosphor responses were determined for in-air and on-phantom irradiations. Similar irradiations were done using a /sup 137/Cs source. Phosphor glow curves were recorded using a Harshaw Model 2080 TL Picoprocessor.

  20. Beta and low-energy photon irradiation of several commercial phosphors

    Science.gov (United States)

    Fix, J. J.; Holbrook, K. L.; Soldat, K. L.

    1983-02-01

    Several commercially available thermoluminescent phosphors were evaluated with respect to their observed response to selected beta sources and K-fluorescent X rays. Phosphor responses were determined for in-air and on-phantom irradiations. Similar irradiations were done using a 137Cs source. Phosphor glow curves were recorded using a Harshaw Model 2080 TL Picoprocessor.

  1. 21 CFR 175.260 - Partial phosphoric acid esters of polyester resins.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Partial phosphoric acid esters of polyester resins... COMPONENTS OF COATINGS Substances for Use as Components of Coatings § 175.260 Partial phosphoric acid esters of polyester resins. Partial phosphoric acid esters of polyester resins identified in this section...

  2. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Science.gov (United States)

    2010-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this section...

  3. 40 CFR 721.10140 - Phosphoric acid, tin (2+) salt (2:3).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid, tin (2+) salt (2:3... Specific Chemical Substances § 721.10140 Phosphoric acid, tin (2+) salt (2:3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as phosphoric acid, tin...

  4. Improved properties of phosphor-filled luminescent down-shifting layers: reduced scattering, optical model, and optimization for PV application

    Science.gov (United States)

    Solodovnyk, Anastasiia; Lipovšek, Benjamin; Forberich, Karen; Stern, Edda; Krč, Janez; Batentschuk, Miroslaw; Topič, Marko; Brabec, Christoph J.

    2015-12-01

    We studied the optical properties of polymer layers filled with phosphor particles in two aspects. First, we used two different polymer binders with refractive indices n = 1.46 and n = 1.61 (λ = 600 nm) to decrease Δn with the phosphor particles (n = 1.81). Second, we prepared two particle size distributions D50 = 12 μm and D50 = 19 μm. The particles were dispersed in both polymer binders in several volume concentrations and coated onto glass with thicknesses of 150 - 600 μm. We present further a newly developed optical model for simulation and optimization of such luminescent down-shifting (LDS) layers. The model is developed within the ray tracing framework of the existing optical simulator CROWM (Combined Ray Optics / Wave Optics Model), which enables simulation of standalone LDS layers as well as complete solar cells (including thick and thin layers) enhanced by the LDS layers for an improved solar spectrum harvesting. Experimental results and numerical simulations show that the layers of the higher refractive index binder with larger particles result in the highest optical transmittance in the visible light spectrum. Finally we proved that scattering of the phosphor particles in the LDS layers may increase the overall light harvesting in the solar cell. We used numerical simulations to determine optimal layer composition for application in realistic thin-film photovoltaic devices. Surprisingly LDS layers with lower measured optical transmittance are more efficient when applied onto the solar cells due to graded refractive index and efficient light scattering. Therefore, our phosphor-filled LDS layers could possibly complement other light-coupling techniques in photovoltaics.

  5. Combustion synthesis, characterization and luminescence properties of barium aluminate phosphor

    Institute of Scientific and Technical Information of China (English)

    AH Wako; FB Dejene; HC Swart

    2014-01-01

    The blue-green emitting Eu2+and Nd3+ doped polycrystalline barium aluminate (BaAl2O4:Eu2+,Nd3+) phosphor, was pre-pared by a solution-combustion method at 500 ºC without a post-annealing process. The characteristic variation in the structural and luminescence properties of the as-prepared samples was evaluated with regards to a change in the Ba/Al molar ratio from 0.1:1 to 1.4:1. The morphologies and the phase structures of the products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), while the optical properties were investigated using ultra-violet (UV) and photoluminescence (PL) spectroscopy, respectively. The XRD and TEM results revealed that the average crystallite size of the BaAl2O4:Eu2+,Nd3+ phosphor was about 70 nm. The broad-band UV-excited luminescence of the phosphors was observed atλmax=500 nm due to transitions from the 4f65d1 to the 4f7 configuration of the Eu2+ ion. The PL results indi-cated that the main peaks in the emission and excitation spectrum of phosphor particles slightly shifted to the short wavelength due to the changes in the crystal field due to the structure changes caused by the variation in the quantity of the Ba ions in the host lattice.

  6. Luminescence and spectroscopic studies of halosulfate phosphors: a review.

    Science.gov (United States)

    Gedam, S C; Thakre, P S; Dhoble, S J

    2015-03-01

    This review discusses the photoluminescence (PL) characteristics of halosulfate phosphors developed by us. Halosulfate phosphors KCaSO4 Cl:X,Y (X = Eu or Ce; Y = Dy or Mn) and Na6 (SO4 )2 FCl (doped with Dy, Ce or Eu) were prepared using a solid-state diffusion method. The mechanism of energy transfer from Eu(2+) →Dy(3+) , Ce(3+) →Dy(3+) and Ce(3+) →Mn(2+) has also been studied. Dy(3+) emission in the host at 475 and 570 nm is observed due to (4) F9/2 →(6) H15/2 and (4) F9/2 →(6) H13/2 transition, whereas the PL emission spectra of Na6 (SO4 )2 FCl:Ce phosphor shows Ce(3+) emission at 322 nm due to 5d→4f transition of the Ce(3+) ion. The main property of KCaSO4 Cl is its very high sensitivity, particularly when doped by Dy, Mn or Pb activators. This review also discusses the PL characteristics of some new phosphors such as LiMgSO4 F, Na6 Pb4 (SO4 )6 Cl2 , Na21 Mg(SO4 )10 Cl3 and Na15 (SO4 )5 F4 Cl.

  7. Progress in phosphors and filters for luminescent solar concentrators

    NARCIS (Netherlands)

    de Boer, D.K.G.; Broer, D.J.; Debije, M.G.; Keur, W.; Meijerink, A.; Ronda, R.C.; Verbunt, P.P.C.

    2012-01-01

    Luminescent solar concentrators would allow for high concentration if losses by reabsorption and escape could be minimized. We introduce a phosphor with close-to-optimal luminescent properties and hardly any reabsorption. A problem for use in a luminescent concentrator is the large scattering of

  8. A Novel White Light Emitting Long-lasting Phosphor

    Institute of Scientific and Technical Information of China (English)

    Bing Fu LEI; Ying Liang LIU; Ze Ren YE; Chun Shan SHI

    2004-01-01

    A novel white light emitting long-lasting phosphor Cd1-xDyxSiO3 is reported in this letter. The Dy3+ doped CdSiO3 phosphor emits white light. The phosphorescence can be seen with the naked eye in the dark clearly even after the 254 nm UV irradiation have been removed for about 30 min. In the emission spectrum of 5% Dy3+ doped CdSiO3 phosphor, there are two emission peaks of Dy3+, 580 nm (4F9/2→6H13/2) and 486 nm (4F9/2→6H15/2), as well as a broad band emission located at about 410 nm. All the three emissions form a white light with CIE chromaticity coordinates x=0.3874, y=0.3760 and the color temperature is 4000 K under 254 nm excitation. It indicated that this phosphor is a promising new luminescent material for practice application.

  9. Progress in phosphors and filters for luminescent solar concentrators

    NARCIS (Netherlands)

    De Boer, D.K.G.; Broer, D.J.; Debije, M.G.; Keur, W.C.; Meijerink, A.; Ronda, C.R.; Verbunt, P.P.C.

    2012-01-01

    Luminescent solar concentrators would allow for high concentration if losses by reabsorption and escape could be minimized. We introducea phosphor with close-to-optimal luminescent properties and hardlyany reabsorption. A problem for use in a luminescent concentrator isthe large scattering of this

  10. Spectral modulation through controlling anions in nanocaged phosphors

    NARCIS (Netherlands)

    H. Bian; Y. Liu; D. Yan; H. Zhu; C. Liu; C.S. Xu; Y. Liu; H. Zhang; X. Wang

    2013-01-01

    A new approach has been proposed and validated to modulate the emission spectra of europium-doped 12CaO center dot 7Al(2)O(3) phosphors by tuning the nonradiative and radiative transition rates, realized by controlling the sort and amount of the encaged anions. A single wavelength at 255 nm can exci

  11. Progress in phosphors and filters for luminescent solar concentrators

    NARCIS (Netherlands)

    De Boer, D.K.G.; Broer, D.J.; Debije, M.G.; Keur, W.C.; Meijerink, A.; Ronda, C.R.; Verbunt, P.P.C.

    2012-01-01

    Luminescent solar concentrators would allow for high concentration if losses by reabsorption and escape could be minimized. We introducea phosphor with close-to-optimal luminescent properties and hardlyany reabsorption. A problem for use in a luminescent concentrator isthe large scattering of this m

  12. A Gravitational Shielding Based on ZnS:Ag Phosphor

    OpenAIRE

    De Aquino, Fran

    2001-01-01

    It was shown that there is a practical possibility of gravity control on electroluminescent (EL) materials (physics/0109060). We present here a type Gravitational Shielding based on an EL phosphor namely zinc sulfide doped with silver (ZnS:Ag) which can reduce the cost of the Gravitational Motor previously presented.

  13. Corrosion of graphite composites in phosphoric acid fuel cells

    Science.gov (United States)

    Christner, L. G.; Dhar, H. P.; Farooque, M.; Kush, A. K.

    1986-01-01

    Polymers, polymer-graphite composites and different carbon materials are being considered for many of the fuel cell stack components. Exposure to concentrated phosphoric acid in the fuel cell environment and to high anodic potential results in corrosion. Relative corrosion rates of these materials, failure modes, plausible mechanisms of corrosion and methods for improvement of these materials are investigated.

  14. Application of ceramic phosphors for near infrared biomedical imaging technologies

    Science.gov (United States)

    Soga, Kohei; Tokuzen, Kimikazu; Tsuji, Kosuke; Yamano, Tomoyoshi; Venkatachalam, Nallusamy; Hyodo, Hiroshi; Kishimoto, Hidehiro

    2010-02-01

    Near infrared wavelength region between 0.8 and 2 μm is an attractive region for biomedical imaging due to the low loss in biomedical objects in the region. Rare-earth doped ceramic phosphors are known to emit efficient fluorescence in the same wavelength region. The authors have developed micro fluorescence bioimaging system for cellular or tissue imaging and macro one for in vivo imaging. This paper will review the materials synthesis for the near infrared fluorescence probes as well as the system development and demonstrative works. Er-doped or Yb/Er-doped ceramic phosphors were synthesized with required particle size. The phosphors were partly modified with polyethylene glycol to give dispersion and controlled interaction with the biological objects. By using the micro imaging system, nematodes, mouse tissue and M1 cells were observed by detecting 1.5 μm emission from Er doped in the ceramic phosphor. in vivo imaging with the same fluorescence scheme was also performed for the digestive organs of live mouse.

  15. PMMA with Long-Persistent Phosphors and Its Behavior of Luminescence

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new kind of rare earth material with high efficient long-persistent phosphors, such as SrAl2O4:Eu, Dy, has been developed in recent years. The PMMA with long-persistent phosphors is typical one of applications for the phosphors. In this work, we try to probe into the affection of the manufacture process on the PMMA with long-persistent phosphors, to analyze its performance, and its luminescence behavior, especially to study the self-excitation of the PMMA with long-persistent phosphors.

  16. Rare earth activated yttrium aluminate phosphors with modulated luminescence.

    Science.gov (United States)

    Muresan, L E; Popovici, E J; Perhaita, I; Indrea, E; Oro, J; Casan Pastor, N

    2016-06-01

    Yttrium aluminate (Y3 A5 O12 ) was doped with different rare earth ions (i.e. Gd(3+) , Ce(3+) , Eu(3+) and/or Tb(3+) ) in order to obtain phosphors (YAG:RE) with general formula,Y3-x-a Gdx REa Al5 O12 (x = 0; 1.485; 2.97 and a = 0.03). The synthesis of the phosphor samples was done using the simultaneous addition of reagents technique. This study reveals new aspects regarding the influence of different activator ions on the morpho-structural and luminescent characteristics of garnet type phosphor. All YAG:RE phosphors are well crystallized powders containing a cubic-Y3 Al5 O12 phase as major component along with monoclinic-Y4 Al2 O9 and orthorhombic-YAlO3 phases as the impurity. The crystallites dimensions of YAG:RE phosphors vary between 38 nm and 88 nm, while the unit cell slowly increase as the ionic radius of the activator increases. Under UV excitation, YAG:Ce exhibits yellow emission due to electron transition in Ce(3+) from the 5d level to the ground state levels ((2) F5/2 , (2) F7/2 ). The emission intensity of Ce(3+) is enhanced in the presence of the Tb(3+) ions and is decreased in the presence of Eu(3+) ions due to some radiative or non-radiative processes that take place between activator ions. By varying the rare earth ions, the emission colour can be modulated from green to white and red. Copyright © 2015 John Wiley & Sons, Ltd.

  17. Laser-activated remote phosphor light engine for projection applications

    Science.gov (United States)

    Daniels, Martin; Mehl, Oliver; Hartwig, Ulrich

    2015-09-01

    Recent developments in blue emitting laser diodes enable attractive solutions in projection applications using phosphors for efficient light conversion with very high luminance levels. Various commercially available projectors incorporating this technology have entered the market in the past years. While luminous flux levels are still comparable to lamp-based systems, lifetime expectations of classical lamp systems are exceeded by far. OSRAM GmbH has been exploring this technology for several years and has introduced the PHASER® brand name (Phosphor + laser). State-of-the-art is a rotating phosphor wheel excited by blue laser diodes to deliver the necessary primary colors, either sequentially for single-imager projection engines, or simultaneously for 3-panel systems. The PHASER® technology enables flux and luminance scaling, which allows for smaller imagers and therefore cost-efficient projection solutions. The resulting overall efficiency and ANSI lumen specification at the projection screen of these systems is significantly determined by the target color gamut and the light transmission efficiency of the projection system. With increasing power and flux level demand, thermal issues, especially phosphor conversion related, dominate the opto-mechanical system design requirements. These flux levels are a great challenge for all components of an SSL-projection system (SSL:solid-state lighting). OSRAḾs PHASER® light engine platform is constantly expanded towards higher luminous flux levels as well as higher luminance levels for various applications. Recent experiments employ blue laser pump powers of multiple 100 Watts to excite various phosphors resulting in luminous flux levels of more than 40 klm.

  18. A mechanistic study of copper electropolishing in phosphoric acid solutions

    Science.gov (United States)

    Mansson, Andrew

    The microelectronics industry is using copper as the interconnect material for microchips. A study of copper electropolishing is important for the process development of a new, low downforce approach, which is being developed to replace chemical mechanical polishing (CMP) of the copper overburden. A promising technology is a combination of electropolishing with conventional CMP. Electropolishing of copper in phosphoric acid has been studied for, more than 70 years. Previous work has shown that the polishing rate, as measured by current density is directly related to the viscosity of the electrolyte. Also, the limiting species is water. In this study, a multidimensional design of experiments was performed to develop an in-depth model of copper electropolishing. Phosphoric acid was mixed with alcohols of different molecular weight and related viscosity to investigate how the solvents' properties affected polishing. The alcohols used were methanol, ethanol, isopropanol, butanol, ethylene glycol, and glycerol. The limiting current densities and electrochemical behavior of each solution was measured by potentiodynamic and potentiostatic experiments. Also, the kinematic viscosity and density were measured to determine the dynamic viscosity to investigate the relationship of current density and viscosity. Water, methanol, ethanol, and isopropanol solutions were also examined at 20°C to 60°C. Next, the relative percentage of dissociated phosphoric acid was measured by Raman spectroscopy for each polishing solution. Raman spectroscopy was also used to measure the relative dissociation of phosphoric acid inside the polishing film. Additionally, wafers were electropolished and electrochemical mechanically polished to investigate the effects of the different solvents, fluid flow, current, and potential. The results of these experiments have shown that the molecular mass and the ability of the solvent to dissociate phosphoric acid are the primary electrolyte properties that

  19. -2,4-Dichlorobenzoyl phosphoric triamides: Synthesis, spectroscopic and X-ray crystallography studies

    Indian Academy of Sciences (India)

    Khodayar Gholivand; Nasrin Oroujzadeh; Zahra Shariatinia

    2010-07-01

    New phosphoric triamides 1-9 were synthesized by the reaction of -2,4-dichlorobenzoyl phosphoramidic dichloride with various cyclic aliphatic amines and the products were characterized by 1H, 13C, 31P NMR, IR spectroscopy and elemental analysis. Surprisingly, the 1H NMR spectrum of 2 indicated long range 6 (P, H) coupling constant = 1.3, 1.4 Hz and those of molecules 3, 4, 6-8 display longrange 4 (H, H) coupling constants (1.8-1.9 Hz) for the coupling of aromatic protons in 2,4-dichlorophenyl rings. 1H NMR spectra indicated 3 (PNCH) for enantiotopic and diastereotopic benzylic CH2 protons in compounds 7 and 8. The spectroscopic data of newly synthesized compounds were compared with those related -benzoyl derivatives. The structures of compounds 5, 8 and 10 (2,4-Cl2-C6H3C(O)NHP(O)[NCH2CH(CH3)2]2) have been determined by X-ray crystallography. The structures form centrosymmetric dimers through intermolecular strong -P=O…H-N-hydrogen bonds. The dimers connect to each other via rather strong and weak C-H…O plus weak C-H…Cl H-bonds to produce a 1-D network for 5 while 3-D polymeric chains for 8 and 10.

  20. Effect of x-ray incident direction and scintillator layer design on image quality of indirect-conversion flat-panel detector with GOS phosphor

    Science.gov (United States)

    Sato, K.; Nariyuki, F.; Nomura, H.; Takasu, A.; Fukui, S.; Nakatsu, M.; Okada, Y.; Nabeta, T.; Hosoi, Y.

    2011-03-01

    In this study, we characterized the image quality of two types of indirect-conversion flat-panel detectors: an X-ray incident-side photo-detection system (IS) and an X-ray penetration-side photo-detection system (PS). These detectors consist of a Gd2O2S:Tb (GOS) scintillator coupled with a photodiode thin film transistor (PD-TFT) array on a glass substrate. The detectors have different X-ray incident directions, glass substrates, and scintillators. We also characterized the effects of layered scintillator structures on the image quality by using a single-layered scintillator containing large phosphor grains and a double-layered scintillator consisting of a layer of large phosphor grains and a layer of small phosphor grains. The IS system consistently demonstrated a higher MTF than the PS system for a scintillator of the same thickness. Moreover, the IS system showed a higher DQE than the PS system when a thick scintillator was used. While the double-layered scintillators were useful for improving the MTF in both systems, a thick single-layered scintillator was preferable for obtaining a high DQE when the IS system was applied. These results indicate that an IS system can efficiently utilize the light emitted from the phosphor at the far side of the PD without the occurrence of blurring. The use of IS systems makes it possible to increase the thickness of the scintillator layer for improving the sensitivity without reducing the MTF, which increases the DQE. The DQE of the IS system was 1.2 times that of the PS system, despite the absorption of X-rays at the glass substrate before entering the phosphor.

  1. Fiber optic temperature sensor using a Y{sub 2}O{sub 2}S:Eu thermographic phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Smith, T.V. [Bethel Coll., St. Paul, MN (United States). Dept. of Physics; Smith, D.B. [Oak Ridge National Lab., TN (United States)

    1993-09-01

    This report details the development and testing of a thermographic-phosphor-based fiber-optic temperature sensor. The sensor is constructed by removing a region of the fiber jacket and cladding, then coating the exposed core with yttrium oxysulfide doped with a europium activator (Y{sub 2}O{sub 2}S:Eu). When photoexcited, the europium in the host lattice emits a sharp-line fluorescence spectrum that is characteristic of the temperature of the host crystal lattice. By measuring fluorescence lifetimes, we can deduce the temperature of an optical fiber that is in thermal contact with the fiber. Two different distributions of Y{sub 2}O{sub 2}S:Eu in the cladding region were evaluated with regard to light coupling efficiency. Theoretical waveguide calculations indicate that a thin core/cladding boundary distribution of Y{sub 2}O{sub 2}S:Eu couples light more efficiently into the cores guided modes than does a bulk distribution of phosphor in the cladding. The sensor tests showed reproducible response from 20 to 180 degrees Celsius. This technique has several advantages over other fiber optic temperature sensing techniques: the temperature measurement is independent of the strain applied to the fiber; the measurements are potentially accurate to within half a degree centigrade; the sensor allows temperature to be measured at precise locations; and the method doesn`t preclude the use of the fiber for the simultaneous measurement of other parameters.

  2. Luminescent studies of impurity doped SrS phosphors

    Indian Academy of Sciences (India)

    Vijay Singh; Manoj Tiwari; T K Gundu Rao; S J Dhoble

    2005-02-01

    SrS phosphors activated with Ce and Dy ions were prepared by solid-state diffusion method. Photoluminescent study was carried out on SrS : Ce, SrS : Dy and SrS : Dy, Ce. Thermoluminescence and electron spin resonance studies were also carried out on SrS : Dy phosphor. The thermoluminescence glow curve shows a peak at around 142°C. Irradiated SrS : Dy exhibits an ESR line due to a defect centre. Thermal annealing behaviour indicates that this centre correlates with the TL peak at 142°C. The centre is characterized by an isotropic g-value of 2.0039 and is assigned to a + centre.

  3. Two-dimensional thermographic phosphor thermometry in a cryogenic environment

    Science.gov (United States)

    Cai, Tao; Kim, Dong; Kim, Mirae; Liu, Ying Zheng; Kim, Kyung Chun

    2017-01-01

    In this study, lifetime-based thermographic phosphor thermometry was developed for 2D temperature measurements in a cryogenic temperature environment. A chamber was set up to provide such an environment with temperatures of 300-110 K and accuracy of  ±3.5 K. Mg4FGeO6:Mn was used as a sensor material, which was excited by a pulsed UV LED. A high-speed camera with a frequency of 8000 Hz was used for the phosphor thermometry. Calibration was performed at temperatures ranging from 110 to 290 K. The calibration results clearly show variation in the lifetime at different temperatures, and the calibration error is within 1.7%. This measurement is demonstrated in a 2D temperature measurement of an aluminum plate with a heater for both steady and unsteady heat transfer conditions. The measurement results were compared with thermocouple measurements to validate the method.

  4. Synthesis and Properties of Eu3+ Activated Strontium Molybdate Phosphor

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to prepare fluorescent material for white Light Emitting Diodes (LEDs), a new Eu3+ activated molybdate phosphor SrMoO4 was fabricated with solid-state method.X-ray diffraction (XRD) showed that the doping of trivalent europium ion reduced the lattice parameters.The excitation and emission spectra indicated that this phosphor could be excited effectively by the visible light, and then emitted red light with the peaks located at 616 and 624 nm.The influence of Eu3+ concentration on the luminescent properties of Eu3+ doped SrMoO4 was investigated and the 25%(mole fraction) was the appropriate molar concentration.The reaction time and temperature had obvious effect on the luminescent properties.The luminescent intensity reached the strongest when it was sintered at 800 ℃ for 3 h.

  5. Preparation and luminescence characteristics of Eu2+ activated silicate phosphor

    Science.gov (United States)

    Li, Pan-Lai; Yang, Zhi-Ping; Wang, Zhi-Jun; Guo, Qing-Lin

    2008-03-01

    This paper synthesizes the Sr2SiO4 : Eu2+ phosphor by high temperature solid-state reaction. The emission spectrum of Sr2SiO4 : Eu2+ shows two bands centred at 480 and 547 nm, which agree well with the calculation values of emission spectrum, and the location of yellow emission of Sr2SiO4 : Eu2+ is influenced by the Eu2+ concentration. The excitation spectrum for 547nm emission has two bands at 363 and 402 nm. The emission spectrum of white light emitting diodes (w-LEDs) based on Sr2SiO4 :Eu2+ phosphor + InGaN LED was investigated.

  6. Preparation and luminescence characteristics of Eu2+ activated silicate phosphor

    Institute of Scientific and Technical Information of China (English)

    Li Pan-Lai; Yang Zhi-Ping; Wang Zhi-Jun; Guo Qing-Lin

    2008-01-01

    This paper synthesizes the Sr2SiO4:Eu2+ phosphor by high temperature solid-state reaction.The emission spectrum of Sr2SiO4 :Eu2+ shows two bands centred at 480 and 547 nm, which agree well with the calculation values of emission spectrum, and the location of yellow emission of Sr2SiO4 : Eu2+ is influenced by the Eu2+ concentration.The excitation spectrum for 547 nm emission has two bands at 363 and 402 nm. The emission spectrum of white light emitting diodes (w-LEDs) based on Sr2SiO4 : Eu2+ phosphor + InGaN LED was investigated.

  7. Recycle use of phosphorous mixer extractant to extract indium

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The stripping and regeneration of the loaded organic phase of phosphorous mixer extractant (PPD) were studied.The mixed solutions (3 mol/L HCl +2 mol/L ZnCl2) were used as the stripping agent and more than 99% of indium can bestripped after three-stage stripping when the volume ratio of organic phase to stripping agent is 1:1. The organic phase canbe recycled to use after regeneration with HCl. The parallel contrast experiments with D2EHPA (di-2-ethyl hexyl phospho-ric acid) were carried out under the same conditions. The results show that the mixer extractant has good reusability and thestripping and regeneration of PPD are superior to those of D2EHPA.

  8. Considerable photoluminescence enhancement of LiEu(MoO{sub 4}){sub 2} red phosphors via Bi and/or Si doping for white LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qing-Feng [Department of Materials Science and Engineering, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong 518055 (China); Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Liu, Ying [Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Wang, Yu [Department of Physics and Materials Science, City University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Wang, Wenxi; Wan, Yi [Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Wang, Gui-Gen [Department of Materials Science and Engineering, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong 518055 (China); Lu, Zhou-Guang [Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China)

    2015-03-15

    Graphical abstract: Doping of Bi and Si into the lattice leads to an considerable increase of the excitation efficiency and luminous intensity, and obvious movement of the CIE chromaticity coordinates to the NTSC standard values of the LiEu(MoO{sub 4}){sub 2}, a promising red phosphors suitable for near UV excited white-light emitting diodes. - Highlights: • High performance red phosphors for near UV light excited white LEDs. • Lithium lanthanide molybdate red phosphors. • Bi and Si substitution. • Considerable enhancement of luminescence intensity and excitation efficiency. • CIE chromaticity coordinates very close to the NTSC standard values. - Abstract: Novel Bi and/or Si substituted LiEu(MoO{sub 4}){sub 2} phosphors, where Bi was used as sensitizer to enhance the emission intensity and Si was used as substitution to improve the excitation efficiency, were prepared using the sol–gel method, and the photoluminescent properties of the resulting phosphors were intensively investigated. All samples can be excited efficiently by UV (395 nm) light and emit bright red light at 614 nm, which are coupled well with the characteristic emission from a UV-LED. In the Bi{sup 3+}-doped samples, the intensities of the main emission line ({sup 5}D{sub 0}–{sup 7}F{sub 2} transition at 614 nm) are strengthened because of the energy transition from Bi{sup 3+} to Eu{sup 3+}. With the substitution of Mo{sup 4+} by Si{sup 4+}, there are no significant changes in the emission peak positions, but the emission intensity was significantly enhanced under 395 nm excitation. Particularly, the LiEu{sub 0.9}Bi{sub 0.1}(Mo{sub 0.97}Si{sub 0.03}O{sub 4}){sub 2} phosphor doped with both Bi and Si demonstrates superior comprehensive photoluminescence properties with an excellent combination of easy excitation in the near UV range, bright emission intensity, high PL quantum efficiency as well as suitable decay time, which are very suitable for application as red phosphor for near UV

  9. Colour control in SrS:Cu,Cl powder phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Anila, E.I. [Department of Physics, Union Christian College, Aluva, Kerala 683102 (India); Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Kochi 682022 (India); Sanjaykumar, I.P. [Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Kochi 682022 (India); Jayaraj, M.K., E-mail: mkj@cusat.ac.in [Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Kochi 682022 (India)

    2011-12-15

    Graphical abstract: Photoluminescence spectrum of SrS:Cu,Cl phosphor for different Cu concentrations at 300 K, {lambda}{sub ex} = 310 nm. Emission colour varies from blue to red as the doping concentration is increased. Highlights: Black-Right-Pointing-Pointer We report the study of the effect of doping concentration on the lattice parameter, band gap and photoluminescence in SrS:Cu,Cl phosphor. Black-Right-Pointing-Pointer Analysis of the observations were made by comparison with previous reported results. Black-Right-Pointing-Pointer Emission colour in SrS:Cu,Cl phosphor can be tailored from blue to green on increasing the doping concentration. Black-Right-Pointing-Pointer Band gap is red shifted with doping concentration due to band tailing effects. Black-Right-Pointing-Pointer Analysis of lattice parameter, strain and grain size are carried out on the basis of X-ray diffraction (XRD) data. - Abstract: By controlling the concentration of defects and their type in strontium sulphide phosphor, a broad range of colours in the visible spectrum can be achieved. Photoluminescence (PL) spectrum in the blue to green range of SrS:Cu,Cl is presented and explained on the basis of charge compensation process and coordination about the Cu{sup +} ion. Analysis of lattice parameter, strain and grain size were carried out on the basis of X-ray diffraction (XRD) data. From the study of diffuse reflectance spectra (DRS), red-shift in band-gap was observed with increasing doping concentration, which is due to the presence of doping induced tail states.

  10. Modeling Phosphorous Losses from Seasonal Manure Application Schemes

    Science.gov (United States)

    Menzies, E.; Walter, M. T.

    2015-12-01

    Excess nutrient loading, especially nitrogen and phosphorus, to surface waters is a common and significant problem throughout the United States. While pollution remediation efforts are continuously improving, the most effective treatment remains to limit the source. Appropriate timing of fertilizer application to reduce nutrient losses is currently a hotly debated topic in the Northeastern United States; winter spreading of manure is under special scrutiny. We plan to evaluate the loss of phosphorous to surface waters from agricultural systems under varying seasonal fertilization schemes in an effort to determine the impacts of fertilizers applied throughout the year. The Cayuga Lake basin, located in the Finger Lakes region of New York State, is a watershed dominated by agriculture where a wide array of land management strategies can be found. The evaluation will be conducted on the Fall Creek Watershed, a large sub basin in the Cayuga Lake Watershed. The Fall Creek Watershed covers approximately 33,000 ha in central New York State with approximately 50% of this land being used for agriculture. We plan to use the Soil and Water Assessment Tool (SWAT) to model a number of seasonal fertilization regimes such as summer only spreading and year round spreading (including winter applications), as well as others. We will use the model to quantify the phosphorous load to surface waters from these different fertilization schemes and determine the impacts of manure applied at different times throughout the year. More detailed knowledge about how seasonal fertilization schemes impact phosphorous losses will provide more information to stakeholders concerning the impacts of agriculture on surface water quality. Our results will help farmers and extensionists make more informed decisions about appropriate timing of manure application for reduced phosphorous losses and surface water degradation as well as aid law makers in improving policy surrounding manure application.

  11. Methodology for detecting residual phosphoric acid in polybenzoxazole fibers.

    Science.gov (United States)

    Park, Eun Su; Sieber, John; Guttman, Charles; Rice, Kirk; Flynn, Kathleen; Watson, Stephanie; Holmes, Gale

    2009-12-01

    Because of the premature failure of in-service soft-body armor containing the ballistic fiber poly[(benzo-[1,2-d:5,4-d']-benzoxazole-2,6-diyl)-1,4-phenylene] (PBO), the Office of Law Enforcement Standards (OLES) at the National Institute of Standards and Technology (NIST) initiated a research program to investigate the reasons for this failure and to develop testing methodologies and protocols to ensure that these types of failures do not reoccur. In a report that focused on the stability of the benzoxazole ring that is characteristic of PBO fibers, Holmes, G. A.; Rice, K.; Snyder, C. R. J. Mater. Sci. 2006, 41, 4105-4116, showed that the benzoxazole ring was susceptible to hydrolytic degradation under acid conditions. Because of the processing conditions for the fibers, it is suspected by many researchers that residual phosphoric acid may cause degradation of the benzoxazole ring resulting in a reduction of ballistic performance. Prior to this work, no definitive data have indicated the presence of phosphoric acid since the residual phosphorus is not easily extracted and the processed fibers are known to incorporate phosphorus containing processing aids. Methods to efficiently extract phosphorus from PBO are described in this article. Further, characterization determined that the majority of the extractable phosphorus in PBO was attributed to the octyldecyl phosphate processing aid with some phosphoric acid being detected. Analysis by matrix assisted laser desorption ionization of model PBO oligomers indicates that the nonextractable phosphorus is attached to the PBO polymer chain as a monoaryl phosphate ester. The response of model aryl phosphates to NaOH exposure indicates that monoaryl phosphate ester is stable to NaOH washes used in the manufacturing process to neutralize the phosphoric acid reaction medium and to extract residual phosphorus impurities.

  12. Electrodialysis of Phosphates in Industrial-Grade Phosphoric Acid

    OpenAIRE

    Machorro, J. J.; Olvera, J. C.; Larios, A.; Hernández-Hernández, H. M.; Alcantara-Garduño, M. E.; Orozco, G.

    2013-01-01

    The objective of this research was to study the purification of industrial-grade phosphoric acid (P2O5) by conventional electrodialysis. The experiments were conducted using a three-compartment cell with anion and cation membranes, and industrial acid solution was introduced into the central compartment. The elemental analysis of the diluted solution indicated that the composition of magnesium, phosphates, and sodium was reduced in the central compartment. The ratios of the concentration of t...

  13. Status of commercial phosphoric acid fuel cell system development

    Science.gov (United States)

    Warshay, M.; Prokopius, P. R.; Simons, S. N.; King, R. B.

    1981-01-01

    A review of the current commercial phosphoric acid fuel cell system development efforts is presented. In both the electric utility and on-site integrated energy system applications, reducing cost and increasing reliability are important. The barrier to the attainment of these goals has been materials. The differences in approach among the three major participants are their technological features, including electrodes, matrices, intercell cooling, bipolar/separator plates, electrolyte management, fuel selection and system design philosophy.

  14. Integral edge seals for phosphoric acid fuel cells

    Science.gov (United States)

    Granata, Jr., Samuel J. (Inventor); Woodle, Boyd M. (Inventor); Dunyak, Thomas J. (Inventor)

    1992-01-01

    A phosphoric acid fuel cell having integral edge seals formed by an elastomer permeating an outer peripheral band contiguous with the outer peripheral edges of the cathode and anode assemblies and the matrix to form an integral edge seal which is reliable, easy to manufacture and has creep characteristics similar to the anode, cathode and matrix assemblies inboard of the seals to assure good electrical contact throughout the life of the fuel cell.

  15. 31p NMR and ESI-MS Studies on Some Intermediates of the Peptide Coupling Reagents Triphenyl-chlorophosphoranes

    Institute of Scientific and Technical Information of China (English)

    Guo TANG; Gui Ji ZHOU; Feng NI; Li Ming HU; Yu Fen ZHAO

    2005-01-01

    The intermediates of the Appel coupling reagents were studied in acetonitrile,dimethoxyethane and dioxane by 31P NMR, C NMR spectrum and ESI-MS. In dioxane a new high coordinated phosphorous compound with 31p NMR shift at -39 ppm was observed. The ESI-MS showed that it could be a penta-coordinated phosphorous compound containing dioxane. The carboxyl activated intermediates were also studied in three solvents.

  16. Status and prospects for phosphor-based white LED packaging

    Institute of Scientific and Technical Information of China (English)

    Zongyuan LIU; Sheng LIU; Kai WANG; Xiaobing LUO

    2009-01-01

    The status and prospects for high-power, phosphor-based white light-emitting diode (LED) pack-aging have been presented. A system view for packaging design is proposed to address packaging issues. Four aspects of packaging are reviewed: optical control, thermal management, reliability and cost. Phosphor materials play the most important role in light extraction and color control. The conformal coating method improves the spatial color distribution (SCD) of LEDs. High refractive index (RI) encapsulants with high transmittance and modified surface morphology can enhance light extraction. Multi-phosphor-based packaging can realize the control of correlated color temperature (CCT) with high color rendering index (CRI). Effective thermal management can dissipate heat rapidly and reduce thermal stress caused by the mismatch of the coefficient of thermal expansion (CTE). Chip-on-board (COB) technology with a multi-layer ceramic substrate is the most promising method for high-power LED packaging. Low junction temperature will improve the reliability and provide longer life. Advanced processes, precise fabrication and careful operation are essential for high reliability LEDs. Cost is one of the biggest obstacles for the penetration of white LEDs into the market for general illumination products. Mass production in terms of CoB, system in packaging (SIP), 3D packaging and wafer level packaging (WLP) can reduce the cost significantly, especially when chip cost is lowered by using a large wafer size.

  17. Synthesis and characterization of flexible thermographic phosphor temperature sensors

    Science.gov (United States)

    Mitchell, Katherine E.; Gardner, Victor; Allison, Stephen W.; Sabri, Firouzeh

    2016-10-01

    The temperature dependence of the emission characteristics of thermographic phosphors has been used extensively for surface temperature measurements of systems where thermal management is critical for the safe operation of the system. The instantaneous, remote, and highly accurate nature of this form of temperature measurement makes it a very attractive measurement technique. However, the destructive nature of depositing phosphors directly onto the surface of interest and the complications of working with fine powders has limited the use of this technique in all areas. This work focuses on the design and characterization of polymer-encapsulated thermographic phosphor flexible sensors for surface temperature assessment. La2O2S:Eu powder was embedded in an elastomeric sleeve at concentrations of 10%, 25%, and 50% wt. and fully characterized. The effect of spin-coating on emission characteristics of La2O2S:Eu was tested and the decay times were compared to results obtained from bulk-doped samples previously created by the authors.

  18. Fabrication of a Functionally Graded Copper-Zinc Sulfide Phosphor.

    Science.gov (United States)

    Park, Jehong; Park, Kwangwon; Kim, Jongsu; Jeong, Yongseok; Kawasaki, Akira; Kwon, Hansang

    2016-03-14

    Functionally graded materials (FGMs) are compositionally gradient materials. They can achieve the controlled distribution of the desired characteristics within the same bulk material. We describe a functionally graded (FG) metal-phosphor adapting the concept of the FGM; copper (Cu) is selected as a metal and Cu- and Cl-doped ZnS (ZnS:Cu,Cl) is selected as a phosphor and FG [Cu]-[ZnS:Cu,Cl] is fabricated by a very simple powder process. The FG [Cu]-[ZnS:Cu,Cl] reveals a dual-structured functional material composed of dense Cu and porous ZnS:Cu,Cl, which is completely combined through six graded mediating layers. The photoluminescence (PL) of FG [Cu]-[ZnS:Cu,Cl] is insensitive to temperature change. FG [Cu]-[ZnS:Cu,Cl] also exhibits diode characteristics and photo reactivity for 365 nm -UV light. Our FG metal-phosphor concept can pave the way to simplified manufacturing of low-cost and can be applied to various electronic devices.

  19. Combinatorial synthesis of phosphors using arc-imaging furnace

    Science.gov (United States)

    Ishigaki, Tadashi; Toda, Kenji; Yoshimura, Masahiro; Uematsu, Kazuyoshi; Sato, Mineo

    2011-10-01

    We have applied a novel 'melt synthesis technique' rather than a conventional solid-state reaction to rapidly synthesize phosphor materials. During a synthesis, the mixture of oxides or their precursors is melted by light pulses (10-60 s) in an arc-imaging furnace on a water-cooled copper hearth to form a globule of 1-5 mm diameter, which is then rapidly cooled by turning off the light. Using this method, we synthesized several phosphor compounds including Y3Al5O12:Ce(YAG) and SrAl2O4:Eu,Dy. Complex phosphor oxides are difficult to produce by conventional solid-state reaction techniques because of the slow reaction rates among solid oxides; as a result, the oxides form homogeneous compounds or solid solutions. On the other hand, melt reactions are very fast (10-60 s) and result in homogeneous compounds owing to rapid diffusion and mixing in the liquid phase. Therefore, melt synthesis techniques are suitable for preparing multi component homogeneous compounds and solid solutions.

  20. Combinatorial synthesis of phosphors using arc-imaging furnace

    Directory of Open Access Journals (Sweden)

    Tadashi Ishigaki, Kenji Toda, Masahiro Yoshimura, Kazuyoshi Uematsu and Mineo Sato

    2011-01-01

    Full Text Available We have applied a novel 'melt synthesis technique' rather than a conventional solid-state reaction to rapidly synthesize phosphor materials. During a synthesis, the mixture of oxides or their precursors is melted by light pulses (10–60 s in an arc-imaging furnace on a water-cooled copper hearth to form a globule of 1–5 mm diameter, which is then rapidly cooled by turning off the light. Using this method, we synthesized several phosphor compounds including Y3Al5O12:Ce(YAG and SrAl2O4:Eu,Dy. Complex phosphor oxides are difficult to produce by conventional solid-state reaction techniques because of the slow reaction rates among solid oxides; as a result, the oxides form homogeneous compounds or solid solutions. On the other hand, melt reactions are very fast (10–60 s and result in homogeneous compounds owing to rapid diffusion and mixing in the liquid phase. Therefore, melt synthesis techniques are suitable for preparing multi component homogeneous compounds and solid solutions.

  1. Cathodoluminescence Emission Studies for Selected Phosphor-Based Sensor Materials

    Energy Technology Data Exchange (ETDEWEB)

    Goedeke, Shawn [ORNL; Hollerman, William Andrew [ORNL; Allison, Stephen W [ORNL; Gray, P A [Integrated Concepts and Research Corporation - Huntsville, AL; Lewis, Linda A [ORNL; Smithwick III, Robert W [ORNL; Boatner, Lynn A [ORNL; Glasgow, David C [ORNL; Ivanov, Ilia N [ORNL; Wise, H. [Integrated Concepts and Research Corporation - Huntsville, AL

    2005-01-01

    The current interest in returning to the Moon and Mars by 2030 makes cost effective and low mass health monitoring sensors essential for spacecraft development. In space, there are many surface measurements that are required to monitor the condition of the spacecraft including: surface temperature, radiation dose, and impact. Through the use of phosphors, these conditions can be monitored. Practical space-based phosphor sensors will depend heavily upon research investigating the resistance of phosphors to ionizing radiation and the ability to anneal or self-heal from damage caused by ionizing radiation. The cathodoluminescence (CL) testing was performed using the low energy electron system located at the NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama. For the materials tested, several interesting results were observed. For most materials, increases in both beam energy and current density improved the CL fluorescence yield. It was also noted that YAG:Nd,Ce has the greatest near infrared intensity for any of the tested materials. The evaluation of dopant concentration in YPO{sub 4}:Nd showed minimal differences in spectral shape and intensity. While the total electron dose was small, the intention was to maximize the number of irradiated materials.

  2. Cathode catalysts for primary phosphoric acid fuel cells

    Science.gov (United States)

    1981-01-01

    Alkylation or carbon Vulcan XC-72, the support carbon, was shown to provide the most stable bond type for linking cobalt dehydrodibenzo tetraazannulene (CoTAA) to the surface of the carbon; this result is based on data obtained by cyclic voltammetry, pulse voltammetry and by release of 14C from bonded CoTAA. Half-cell tests at 100 C in 85% phosphoric acid showed that CoTAA bonded to the surface of carbon (Vulcan XC-72) via an alkylation procedure is a more active catalyst than is platinum based on a factor of two improvement in Tafel slope; dimeric CoTAA had catalytic activity equal to platinum. Half-cell tests also showed that bonded CoTAA catalysts do not suffer a loss in potential when air is used as a fuel rather than oxygen. Commercially available polytetrafluroethylene (PTFE) was shown to be unstable in the fuel cell environment with degradation occurring in 2000 hours or less. The PTFE was stressed at 200 C in concentrated phosphoric acid as well as electrochemically stressed in 150 C concentrated phosphoric acid; the surface chemistry of PTFE was observed to change significantly. Radiolabeled PTFE was prepared and used to verify that such chemical changes also occur in the primary fuel cell environment.

  3. Optimization of the performance of a CsI(Tl) scintillator + Si pin photodiode detector for medium energy light charged particle hybride array

    CERN Document Server

    Kalinka, G; Gál, J; Hegyesi, G; Molnár, J; Elekes, Z; Motobayashi, T; Yanagisawa, Y; Saito, A

    2003-01-01

    NaI(TI), BGO and CsI(TI) crystals in compact arrays will be used at RIKEN RI Beam Factory in the near future to detect gamma-rays from fast moving nuclei produced in nuclear reactions with radioactive beams, and among them CsI(TI) for light charged particle identification as well. The latter system will consist of 312 Cs(TI) crystals coupled to silicon photodiodes in a hemispherical arrangement, four detectors packed together with their own preamplifiers in each of the 78 parallelepipedic thin walled aluminum containers. (R.P.)

  4. Effects of phosphorous incorporation on the microstructure of Si nanoparticles as an anode material for lithium-ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Chun-young; Koo, Jeong-boon [Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 304-343 (Korea, Republic of); Graduate School of Energy Science and Technology, Chungnam National University, 99 Deahak-ro Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Jang, Bo-yun, E-mail: byjang@kier.re.kr [Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 304-343 (Korea, Republic of); Kim, Joon-soo; Lee, Jin-seok [Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 304-343 (Korea, Republic of); Kim, Sung-soo; Han, Moon-hee [Graduate School of Energy Science and Technology, Chungnam National University, 99 Deahak-ro Yuseong-gu, Daejeon 305-764 (Korea, Republic of)

    2015-07-31

    Si nanoparticles were synthesized by inductively coupled plasma and a specially designed double tube reactor. By injection of large amount of PH{sub 3} during the synthesis, the effects of phosphorous incorporation on their microstructures and chemical binding environments were investigated. Injection of PH{sub 3} gas during the synthesis resulted in a change from crystalline to amorphous phase, a reduction of particle size as well as a process yield. All of the above results were attributed to a lower plasma density when higher amount of PH{sub 3} was injected. From energy-dispersive X-ray spectroscopy, secondary ion mass spectrometry, and X-ray photoelectron spectroscopy analysis, it was revealed that P was doped in Si nanoparticles. However, secondary phases such as P{sub 4} and P{sub 2}O{sub 5} were formed as amorphous ones in nano-scale when a relatively large amount of PH{sub 3} was injected. In addition, those nanoparticles were applied as an active material in the lithium-ion battery's anode. Unexpectedly, amorphous Si nanoparticles with secondary phases showed improved electrochemical properties. P-doping in Si nanoparticles could not directly advance cycling performance by improvement of electrical conductivity of Si nanoparticles. It was rather assumed that a secondary phase influenced and enhanced electrochemical properties by additional capacity due to a formation of Li{sub 3}P and forming an effective buffer against large volumetric change of Si nanoparticles during the charge/discharge. The initial reversible capacity of amorphous Si nanoparticles synthesized with 100 sccm of PH{sub 3} flow rate was 2113 mAh g{sup −1}, and that at the 100th cycle was still about 1000 mAh g{sup −1}, which was twice as high as that of Si nanoparticles synthesized without PH{sub 3} injection. - Highlights: • Silicon nanoparticles with phosphorous were synthesized by inductively coupled plasma. • Effects of phosphorous incorporation on the microstructure

  5. Light yield of an undoped CsI crystal coupled directly to a photomultiplier tube at 77 Kelvin

    Science.gov (United States)

    Liu, Jing; Yamashita, Masaki; Soma, Arun Kumar

    2017-01-01

    A light yield of 20 . 4 +/- 0 . 8 photoelectrons/keV was achieved with an undoped CsI crystal coupled directly to a photomultiplier tube at 77 Kelvin. This is by far the largest in the world achieved with CsI crystals. An energy threshold that is several times lower than the current dark matter experiments utilizing CsI(Tl) crystals may be achievable using this technique. Together with novel CsI crystal purification methods, the technique may be used to improve the sensitivities of dark matter and coherent elastic neutrino-nucleus scattering experiments. Also measured were the scintillation light decay constants of the undoped CsI crystal at both room temperature and 77 Kelvin. The results are consistent with those in the literature. This work was supported by NSF PHY-1506036, USA and Grant-in-Aid (B) Project No. 26800122, MEXT, Japan.

  6. Light yield of an undoped CsI crystal coupled directly to a photomultiplier tube at 77 Kelvin

    CERN Document Server

    Liu, Jing; Soma, Arun Kumar

    2016-01-01

    A light yield of 20.4 $\\pm$ 0.8 photoelectrons/keV was achieved with an undoped CsI crystal coupled directly to a photomultiplier tube at 77 Kelvin. This is by far the largest yield in the world achieved with CsI crystals. An energy threshold that is several times lower than the current dark matter experiments utilizing CsI(Tl) crystals may be achievable using this technique. Together with novel CsI crystal purification methods, the technique may be used to improve the sensitivities of dark matter and coherent elastic neutrino-nucleus scattering experiments. Also measured were the scintillation light decay constants of the undoped CsI crystal at both room temperature and 77 Kelvin. The results are consistent with those in the literature.

  7. Design of Phosphor-Free Single-Chip White Light-Emitting Diodes Using InAlGaN Irregular Multiple Quantum Well Structures

    Institute of Scientific and Technical Information of China (English)

    LU Hui-Min; CHEN Gen-Xiang; JIAN Shui-Sheng

    2009-01-01

    A novel approach for the design of phosphor-free single-chip white light-emitting diodes (LEDs) is proposed by employing InAlGaN irregular multiple quantum well (IMQW) structures.The electronic and optical properties of the designed InAlGaN IMQWs are analyzed in detail by fully considering the effects of strain,well-coupling,For comparison,three different types of InAlGaN IMQW structures with ultra-wide band spontaneous emission spectra are analyzed,and the results show that phosphor-free single-chip white light LEDs with more than 200 nm emission band can be obtained using properly designed InAlGaN IMQW structures.

  8. Ytterbium Doped Gadolinium Oxide (Gd2O3:Yb3+) Phosphor: Topology, Morphology, and Luminescence Behaviour

    OpenAIRE

    Raunak Kumar Tamrakar; Durga Prasad Bisen; Chandra Shekher Robinson; Ishwar Prasad Sahu; Nameeta Brahme

    2014-01-01

    Gd2O3:Yb3+ phosphor has been synthesized by the solid state reaction method with boric acid used as a flux. The resulting Gd2O3:Yb3+ phosphor was characterized by X-ray diffraction (XRD) technique, Fourier transmission infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM), and photoluminescence and thermoluminescence. The results of the XRD show that obtained Gd2O3:Yb3+ phosphor has a cubic structure. The average crystallite sizes could...

  9. Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative

    Science.gov (United States)

    2014-11-01

    1 ASETSDefense 2014 Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative Ruben A. Prado, CEF...COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative...Mil-Spec development 3 ASETSDefense 2014 ■ Demonstrate/Validate pulsed electrodeposition of Nanocrystalline Cobalt -Phosphorous (nCoP) alloy

  10. Coupled transfers; Transferts couples

    Energy Technology Data Exchange (ETDEWEB)

    Nicolas, X.; Lauriat, G.; Jimenez-Rondan, J. [Universite de Marne-la-Vallee, Lab. d' Etudes des Transferts d' Energie et de Matiere (LETEM), 77 (France); Bouali, H.; Mezrhab, A. [Faculte des Sciences, Dept. de Physique, Lab. de Mecanique et Energetique, Oujda (Morocco); Abid, C. [Ecole Polytechnique Universitaire de Marseille, IUSTI UMR 6595, 13 Marseille (France); Stoian, M.; Rebay, M.; Lachi, M.; Padet, J. [Faculte des Sciences, Lab. de Thermomecanique, UTAP, 51 - Reims (France); Mladin, E.C. [Universitaire Polytechnique Bucarest, Faculte de Genie Mecanique, Bucarest (Romania); Mezrhab, A. [Faculte des Sciences, Lab. de Mecanique et Energetique, Dept. de Physique, Oujda (Morocco); Abid, C.; Papini, F. [Ecole Polytechnique, IUSTI, 13 - Marseille (France); Lorrette, C.; Goyheneche, J.M.; Boechat, C.; Pailler, R. [Laboratoire des Composites ThermoStructuraux, UMR 5801, 33 - Pessac (France); Ben Salah, M.; Askri, F.; Jemni, A.; Ben Nasrallah, S. [Ecole Nationale d' Ingenieurs de Monastir, Lab. d' Etudes des Systemes Thermiques et Energetiques (Tunisia); Grine, A.; Desmons, J.Y.; Harmand, S. [Laboratoire de Mecanique et d' Energetique, 59 - Valenciennes (France); Radenac, E.; Gressier, J.; Millan, P. [ONERA, 31 - Toulouse (France); Giovannini, A. [Institut de Mecanique des Fluides de Toulouse, 31 (France)

    2005-07-01

    This session about coupled transfers gathers 30 articles dealing with: numerical study of coupled heat transfers inside an alveolar wall; natural convection/radiant heat transfer coupling inside a plugged and ventilated chimney; finite-volume modeling of the convection-conduction coupling in non-stationary regime; numerical study of the natural convection/radiant heat transfer coupling inside a partitioned cavity; modeling of the thermal conductivity of textile reinforced composites: finite element homogenization on a full periodical pattern; application of the control volume method based on non-structured finite elements to the problems of axisymmetrical radiant heat transfers in any geometries; modeling of convective transfers in transient regime on a flat plate; a conservative method for the non-stationary coupling of aero-thermal engineering codes; measurement of coupled heat transfers (forced convection/radiant transfer) inside an horizontal duct; numerical simulation of the combustion of a water-oil emulsion droplet; numerical simulation study of heat and mass transfers inside a reactor for nano-powders synthesis; reduction of a combustion and heat transfer model of a direct injection diesel engine; modeling of heat transfers inside a knocking operated spark ignition engine; heat loss inside an internal combustion engine, thermodynamical and flamelet model, composition effects of CH{sub 4}H{sub 2} mixtures; experimental study and modeling of the evolution of a flame on a solid fuel; heat transfer for laminar subsonic jet of oxygen plasma impacting an obstacle; hydrogen transport through a A-Si:H layer submitted to an hydrogen plasma: temperature effects; thermal modeling of the CO{sub 2} laser welding of a magnesium alloy; radiant heat transfer inside a 3-D environment: application of the finite volume method in association with the CK model; optimization of the infrared baking of two types of powder paints; optimization of the emission power of an infrared

  11. Research on Y2O3:Eu Phosphor Coated with In2O3

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Y2O3:Eu red phosphor for FED application was prepared by high temperature solid-state reaction. The In2O3 coating by precipitation method to the phosphor was applied and the analyses of XRD, Zeta potential, SEM, EDS and low voltage cathodoluminescence (CL) were conducted for investigating the coating effect. The results showed that In2O3 coating promoted the low voltage CL of the phosphor efficiently. The promotion was possibly due to the enhancement of the surface conductivity of the phosphor grains.

  12. Modification of Luminescent Properties of Red Sulphide Phosphors for White LED Lighting

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A kind of sulphide, CaS:Eu2+, activated by europium ion for white LED lighting was synthesized via solid-state reaction route in reducing atmospheres. The phosphors were then encapsulated with silicone resin. Moreover, chemical structure of the phosphors was characterized by XRD. Microstructure of the powders was observed by SEM. Spectra of excitation and emission for the phosphors were also obtained by a spectrophotometer. Effect of processing parameters on the luminescent properties of the powders was systematically studied to result in the phosphors with good chemical stability and maximal relative luminescent intensity.

  13. Fact Sheet - Phosphate Fertilizer Production Plants and Phosphoric Acid Manufacturing Plants NESHAP

    Science.gov (United States)

    Fact sheet summarizing National Emission Standards for Hazardous Air Pollutants (NESHAP) for Phosphate Fertilizer Production Plants and Phosphoric Acid Manufacturing Plants (40 CFR 63 Subparts AA and BB).

  14. Red Emitting Phosphor (Y,Gd)BO3:Eu3+ for PDP Prepared by Complex Method

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Red phosphor (Y, Gd)BO3:Eu3+ with grain shape, small size, non-agglomerate, high crystallinity and good photoluminescence (PL) intensity was prepared by a complex method that the precursor of the phosphor was prepared by co-precipitation method and the phosphor was prepared by combustion method. The SEM photos and the photoluminescence spectrum excited under VUV show that the morphology and luminescent properties of this phosphor are satisfied when an appropriate amount of urea was adopted as the combustion agent in the preparation procedure.

  15. Defining phosphor luminescence property requirements for white AC LED flicker reduction

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Jianchuan; Narendran, Nadarajah, E-mail: narenn2@rpi.edu

    2015-11-15

    In this paper, we investigate the luminescence of slow-decay phosphors under flickering excitation from an alternating current light-emitting diode (AC LED). A mathematical model was developed to predict the behavior of slow-decay phosphors. The model predictions were validated by experiment. Results showed that it is possible to achieve good quality white light with low flicker index from an AC LED with a slow-decay phosphor. A human factors study confirmed the potential of slow-decay phosphors to improve acceptability of the light output from AC LEDs. Based on this study, we propose a set of recommendations for slow-decay phosphor luminescence properties to create a white AC LED with minimal flicker. - Highlights: • A mathematical model was proposed to simulate slow-decay phosphors. • The behavior of slow-decay phosphors under an AC LED excitation was simulated. • Slow-decay phosphor properties recommended to achieve low flicker, white AC LED. • A human factors study validated the flicker reduction by slow-decay phosphor.

  16. Enhancing the photoluminescence intensity of CaTiO3:Eu3+ red phosphors with magnesium

    Institute of Scientific and Technical Information of China (English)

    张杰强; 范艳伟; 陈朝阳; 王军华; 赵鹏君; 郝斌

    2015-01-01

    Red phosphors MgxCa1–xTiO3:Eu3+ (0phosphor bodies and size of the phosphor particles were uniformly distributed in the range of 600–800 nm when the Mg2+ concentration was about 40 mol.%. It could readily be seen that the strongest PL emission was located at 617 nm monitored at 398 nm, which well matched with the near ultraviolet (NUV, 395–400 nm) GaN-LEDs. More impor-tantly, PL emission intensity (617 nm) of phosphor Mg0.4Ca0.6TiO3:0.03Eu3+ was 4.26 times of that of phosphor CaTiO3:0.03Eu3+. Based on these results, it implied that the PL intensity of phosphorCaTiO3:0.03Eu3+ could be significantly enhanced by introducing Mg2+ into CaTiO3 host lattices and the phosphor Mg0.4Ca0.6TiO3:0.03Eu3+ might be the promising red-emitting phosphor in making tricolor phosphor converted white-LEDs.

  17. Spherical YAG:Ce3+ Phosphor Particles Prepared by Spray Pyrolysis

    Institute of Scientific and Technical Information of China (English)

    Qi Faxin; Wang Haibo; Zhu Xianzhong

    2005-01-01

    Spherical YAG:Ce3+ phosphor particles with narrow size distribution were prepared by spray pyrolysis. The effects of the concentration of solution, the flow rate of carrier gas and the annealing temperature on the phosphor morphology were studied. The productivity of precursor particles shows a trend of drop after rising with the increase of concentration. Raising the flow rate of nitrogen can improve the productivity of the precursor particles. Phosphor prepared by spray pyrolysis has obviously higher emission intensity than that synthesized by solid state reaction, spray pyrolysis makes Ce3+ ions well distributed in the crystal lattice as the luminescent centers, and phosphor particles have regular sphericity and narrow size distribution.

  18. Chemical Vapor Deposition of Phosphorous- and Boron-Doped Graphene Using Phenyl-Containing Molecules.

    Science.gov (United States)

    Mekan Ovezmyradov; Magedov, Igor V; Frolova, Liliya V; Chandler, Gary; Garcia, Jill; Bethke, Donald; Shaner, Eric A; Kalugin, Nikolai G

    2015-07-01

    Simultaneous chemical vapor deposition (CVD) of graphene and "in-situ" phosphorous or boron doping of graphene was accomplished using Triphenylphosphine (TPP) and 4-Methoxyphenylboronic acid (4-MPBA). The TPP and 4-MPBA molecules were sublimated and supplied along with CH4 molecules during graphene growth at atmospheric pressure. The grown graphene samples were characterized using Raman spectroscopy. Phosphorous and boron presence in phosphorous and boron doped graphene was confirmed with Auger electron spectroscopy. The possibility of obtaining phosphorous and boron doped graphene using solid-source molecule precursors via CVD can lead to an easy and rapid production of modified large area graphene.

  19. Kinetic characteristics of the luminescence decay for industrial yttrium-gadolinium-aluminium garnet based phosphors

    OpenAIRE

    Lisitsyn, Viktor Mikhailovich; Stepanov, Sergey Aleksandrovich; Valiev, Damir Talgatovich; Vishnyakova, E. A.; Abdullin, H. A.; Marhabaeva, A. A.; Tulegenova, A. T.

    2016-01-01

    The spectral and decay kinetic characteristics of pulse cathodoluminescence and photoluminescence of phosphors based on yttrium-gadolinium-aluminum garnet were investigated using pulsed optical time resolved spectroscopy.

  20. Preparation of balanced trichromatic white phosphors for solid-state white lighting.

    Science.gov (United States)

    Al-Waisawy, Sara; George, Anthony F; Jadwisienczak, Wojciech M; Rahman, Faiz

    2016-12-05

    High quality white light-emitting diodes (LEDs) employ multi-component phosphor mixtures to generate light of a high color rendering index (CRI). The number of distinct components in a typical phosphor mix usually ranges from two to four. Here we describe a systematic experimental technique for starting with phosphors of known chromatic properties and arriving at their respective proportions for creating a blended phosphor to produce light of the desired chromaticity. This method is applicable to both LED pumped and laser diode (LD) pumped white light sources. In this approach, the radiometric power in the down-converted luminescence of each phosphor is determined and that information is used to estimate the CIE chromaticity coordinate of light generated from the mixed phosphor. A suitable method for mixing multi-component phosphors is also described. This paper also examines the effect of light scattering particles in phosphors and their use for altering the spectral characteristics of LD- and LED-generated light. This is the only approach available for making high efficiency phosphor-converted single-color LEDs that emit light of wide spectral width.

  1. The rate equation based optical model for phosphor-converted white light-emitting diodes

    Science.gov (United States)

    Du, Kang; Li, Haokai; Guo, Keqin; Wang, Heng; Li, Dacheng; Zhang, Wending; Mei, Ting; Chua, Soo Jin

    2017-03-01

    An optical model based on the rate equation was developed to calculate the emission spectrum of a phosphor-converted white light-emitting diode (pc-WLED) taking into consideration the phosphor weight percentage, film thickness, and optical properties of phosphor, viz. absorption spectrum, quantum efficiency spectrum and fluorescent emission spectrum. Films containing a mixture of phosphor and silicone elastomer encapsulant were investigated using this model. A linear relationship was found between the peak absorption coefficient and the phosphor weight percentage with slopes of 66.76  ±  0.52 mm‑1 and 29.66  ±  2.05 mm‑1 for a red phosphor CaAlSiN3:Eu2+ and a yellow phosphor Y3Al5O12:Ce3+, respectively. With these parameters, the model predicted emission spectra which are in good agreement with measurement, thus verifying the validity of the model. The model correctly predicts redshift and spectral width reduction of the emission peak for increasing phosphor weight percentage or film thickness, as expected from the phenomenon of photon reabsorption by the phosphors. This model does not require the use of Monte Carlo simulation and Mie theory.

  2. Fabrication of phosphor micro-grids using proton beam lithography.

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, Paolo (University of Padova and INFN, Padova, Italy); Antolak, Arlyn J.; Provencio, Paula Polyak; Doyle, Barney Lee; Malmqvist, Klas (Lund Institute of Technology, Lund, Sweden); Hearne, Sean Joseph; Nilsson, Christer (Lund Institute of Technology, Lund, Sweden); Kristiansson, Per (Lund Institute of Technology, Lund, Sweden); Wegden, Marie (Lund Institute of Technology, Lund, Sweden); Elfman, Mikael (Lund Institute of Technology, Lund, Sweden); Pallon, Jan (Lund Institute of Technology, Lund, Sweden); Auzelyte, Vaida (Lund Institute of Technology, Lund, Sweden)

    2005-07-01

    A new nuclear microscopy technique called ion photon emission microscopy or IPEM was recently invented. IPEM allows analysis involving single ions, such as ion beam induced charge (IBIC) or single event upset (SEU) imaging using a slightly modified optical microscope. The spatial resolution of IPEM is currently limited to more than 10 {micro}m by the scattering and reflection of ion-induced photons, i.e. light blooming or spreading, in the ionoluminescent phosphor layer. We are developing a 'Microscopic Gridded Phosphor' (also called Black Matrix) where the phosphor nanocrystals are confined within the gaps of a micrometer scale opaque grid, which limits the amount of detrimental light blooming. MeV-energy proton beam lithography is ideally suited to lithographically form masks for the grid because of high aspect ratio, pattern density and sub-micron resolution of this technique. In brief, the fabrication of the grids was made in the following manner: (1) a MeV proton beam focused to 1.5-2 {micro}m directly fabricated a matrix of pillars in a 15 {micro}m thick SU-8 lithographic resist; (2) 7:1 aspect ratio pillars were then formed by developing the proton exposed area; (3) Ni (Au) was electrochemically deposited onto Cu-coated Si from a sulfamate bath (or buffered CN bath); (4) the SU-8 pillars were removed by chemical etching; finally (5) the metal micro-grid was freed from its substrate by etching the underlying Cu layer. Our proposed metal micro-grids promise an order-of-magnitude improvement in the resolution of IPEM.

  3. A Blended Cement Containing Blast Furnace Slag and Phosphorous Slag

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Blended cement containing blast furnace slag(BFS) and phosphorous slag(PS) is a new kind of cement.The total content of blended materials could increase if two additives were used. Using the same admixtures, the properties of the blended cement with 70% additives could reach the standard of 525-grade slag cement according to GB.The strength of cement with 80% additives could reach the standard of 425-grade slag cement.The tests of strength, pore structure,hydration products,inhibiting alkali-aggregate reaction, resistance to sulfate corrosion of BFS-PSC were performed.

  4. Phosphoric acid activation of phosphorites of Central Kyzylkum

    Directory of Open Access Journals (Sweden)

    Atanazar Seitnazarov

    2014-01-01

    Full Text Available The article presents a method of receiving the concentrated single phosphate fertilizers with the content of absorbable P2O5. The experiment made assumed processing of ordinary phosphate flour, washed concentrate, dust fraction, mineralized mass and thermoconcentrate of Central Kyzylkum’s phosphorites by incomplete norm of wet-process phosphoric acid. This process lasts 30 minutes at 75oC; the weight ratio of P2O5 in acid to P2O5 in raw material makes 1 : 0,3 and 1 : 0,5.

  5. Catalyst and electrode research for phosphoric acid fuel cells

    Science.gov (United States)

    Antoine, A. C.; King, R. B.

    1987-01-01

    An account is given of the development status of phosphoric acid fuel cells' high performance catalyst and electrode materials. Binary alloys have been identified which outperform the baseline platinum catalyst; it has also become apparent that pressurized operation is required to reach the desired efficiencies, calling in turn for the use of graphitized carbon blacks in the role of catalyst supports. Efforts to improve cell performance and reduce catalyst costs have led to the investigation of a class of organometallic cathode catalysts represented by the tetraazaannulenes, and a mixed catalyst which is a mixture of carbons catalyzed with an organometallic and a noble metal.

  6. Effect of the temperature and welding on the corrosion of austenitic stainless steel in polluted phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Bakour, S.; Guenbour, A.; Ben Bachir, A. [University Mohammed V-Agdal, Lab. Corrosion-Electrochimie, Faculty of Sciences, Rabat (Morocco); Garcia-Anton, J.; Blasco-Tamarit, E.; Garcia-Garcia, D.M. [Valencia Univ. Politecnica, Dept. de Ingenieria Quimica y Nuclear. ETSI Industriales, Valencia (Spain)

    2009-07-01

    This study enabled us to elucidate the effect of welding and the temperature, the impurities on the corrosion resistance of a super-alloy in phosphoric acid using electrochemical methods and microstructural analyses. The analysis of the electrochemical parameters, resulting from the potentio-kinetic curves realized on alloy 59 in the electrolytic medium showed that the process of welding weakens the behaviour with the materials of corrosion and that the increase in the temperature accentuates the aggressiveness of the medium. The tests carried out on the base metal, the zone affected thermically and the weld bead in polluted phosphoric medium showed that the base metal is the zone most corrosion resistant in a structure welded in the range of temperature 20-80 C, and that the rate of corrosion is very high on the level of the weld bead. The images of surfaces of the three electrodes obtained in real time simultaneously with the electrochemical data acquisition did not reveal the localised corrosion. The microstructural examination carried out by the MEB coupled by analysis EDS, showed that welding causes a variation in the microstructure of alloy 59 on the level of morphology and the composition. (authors)

  7. Controlled preparation of aluminum borate powders for the development of defect-related phosphors for warm white LED lighting

    Science.gov (United States)

    Guimarães, Vinicius F.; Salaün, Mathieu; Burner, Pauline; Maia, Lauro J. Q.; Ferrier, Alban; Viana, Bruno; Gautier-Luneau, Isabelle; Ibanez, Alain

    2017-03-01

    The optimization of the elaboration conditions of a new family of highly emissive white phosphors based on glassy yttrium aluminum borates (g-YAB) compositions is presented. Their preparation from solutions is based on the polymeric precursor method (modified Pechini process), involving non-toxic and low cost precursors. The resulting resins were first dried at moderate temperatures followed by two-step annealing treatments of the obtain powders under controlled atmospheres: a first pyrolysis under nitrogen followed by a calcination under oxygen. This favored the gradual oxidation of organic moieties coming from starting materials, avoiding uncontrolled self-combustion reactions, which generate localized hot spots. This prevented phase segregations and the formation of pyrolytic carbon or carbonates, which are strongly detrimental to the luminescence properties. Thus, coupled chemical analyses and luminescence characterizations showed the high chemical homogeneity of the resulting powders and their intense emissions in the whole visible range. These emissions can be tuned from blue to warm white by adjusting the calcination temperature that is an important advantage for the development of LED devices. We showed that impurities of monovalent and divalent cations act as quenching emission centers for these phosphors. Therefore, by increasing the purity grade, we significantly enhanced the PL emissions leading to high internal quantum yields (80-90%). Finally, cathodoluminescence emissions showed the homogeneous dispersion of emitting centers in the g-YAB matrix.

  8. Phosphorous fractionation in mangrove sediments of Kerala, south west coast of India: the relative importance of inorganic and organic phosphorous fractions

    Digital Repository Service at National Institute of Oceanography (India)

    Resmi, P.; Manju, M.N.; Gireeshkumar, T.R.; Ratheeshkumar, C.S.; Movitha, M.; Shameem, K.; Chandramohanakumar, N.

    act as an efficient trap of organic phosphorous by acting as P sink. The dissolved inorganic phosphate displayed higher concentration in monsoon that could be correlated with higher P leaching from mangrove litter as well as terrigenous input during...

  9. Nitrogen phosphoric fertilizer production technology on the base of Central Kyzylkum phosphorites and ammonium nitrate melt

    Directory of Open Access Journals (Sweden)

    Shavkat Namazov

    2012-11-01

    Full Text Available The process of obtaining nitrogen phosphoric fertilizer by introduction Central Kyzylkum phosphates and ammonium nitrate melt is studied. On the base of these results production technology diagram for nitrogen phosphoric fertilizer is offered. The given technology was approved and developed at the functioning devices of OJSC “NAVOIAZOT” ammonium nitrate shop.

  10. Three-Dimension Mathematical Model of Total Phosphor in the Reservoir and Application

    Institute of Scientific and Technical Information of China (English)

    NIE Jing; YANG Tian-xing; LIU Xiao-duan

    2004-01-01

    Taking the transport of total phosphor pollutants in the Beijing Miyun reservoir for example, we have obtained three dimensional distributing regularity of total phosphor pollutants by the calculation of the linear interpolation value of each point between horizontal layers. The credibility analysis in allusion to this method was carried out and the programming scheme for realizing this method was set forth.

  11. Alternative magnesium source for phosphorous recovery – a feasibility and economic analysis

    DEFF Research Database (Denmark)

    Quist-Jensen, Cejna Anna; Jørgensen, Mads Koustrup; Christensen, Morten Lykkegaard

    2016-01-01

    Conventional reservoirs of phosphorous are in high risk of depletion in near future, thus nontraditional and sustainable recovery-practices are essential to ensure its adequate supply in future. Today phosphorous is being recovered from wastewater at industrial scale by addition of MgCl2. However...

  12. Structural Changes of Oil Palm Empty Fruit Bunch (OPEFB after Fungal and Phosphoric Acid Pretreatment

    Directory of Open Access Journals (Sweden)

    Mohammad J. Taherzadeh

    2012-12-01

    Full Text Available Oil palm empty fruit bunch (OPEFB was pretreated using white-rot fungus Pleurotus floridanus, phosphoric acid or their combination, and the results were evaluated based on the biomass components, and its structural and morphological changes. The carbohydrate losses after fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 7.89%, 35.65%, and 33.77%, respectively. The pretreatments changed the hydrogen bonds of cellulose and linkages between lignin and carbohydrate, which is associated with crystallinity of cellulose of OPEFB. Lateral Order Index (LOI of OPEFB with no pretreatment, with fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 2.77, 1.42, 0.67, and 0.60, respectively. Phosphoric acid pretreatment showed morphological changes of OPEFB, indicated by the damage of fibre structure into smaller particle size. The fungal-, phosphoric acid-, and fungal followed by phosphoric acid pretreatments have improved the digestibility of OPEFB’s cellulose by 4, 6.3, and 7.4 folds, respectively.

  13. 40 CFR 721.10177 - Phosphoric acid, yttrium(3+) salt (1:1).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid, yttrium(3+) salt (1:1... Specific Chemical Substances § 721.10177 Phosphoric acid, yttrium(3+) salt (1:1). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as...

  14. Structural changes of oil palm empty fruit bunch (OPEFB) after fungal and phosphoric acid pretreatment.

    Science.gov (United States)

    Isroi; Ishola, Mofoluwake M; Millati, Ria; Syamsiah, Siti; Cahyanto, Muhammad N; Niklasson, Claes; Taherzadeh, Mohammad J

    2012-12-17

    Oil palm empty fruit bunch (OPEFB) was pretreated using white-rot fungus Pleurotus floridanus, phosphoric acid or their combination, and the results were evaluated based on the biomass components, and its structural and morphological changes. The carbohydrate losses after fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 7.89%, 35.65%, and 33.77%, respectively. The pretreatments changed the hydrogen bonds of cellulose and linkages between lignin and carbohydrate, which is associated with crystallinity of cellulose of OPEFB. Lateral Order Index (LOI) of OPEFB with no pretreatment, with fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 2.77, 1.42, 0.67, and 0.60, respectively. Phosphoric acid pretreatment showed morphological changes of OPEFB, indicated by the damage of fibre structure into smaller particle size. The fungal-, phosphoric acid-, and fungal followed by phosphoric acid pretreatments have improved the digestibility of OPEFB's cellulose by 4, 6.3, and 7.4 folds, respectively.

  15. Eu(2+) luminescence in SrCaP2 O7 pyrophosphate phosphor.

    Science.gov (United States)

    Kohale, R L; Dhoble, S J

    2013-01-01

    A series of Eu(2+) activated SrCaP2 O7 pyrophosphate phosphors were synthesized by the modified solid-state reaction method. The X-ray diffraction (XRD) and photoluminescence (PL) properties of these phosphors were investigated at room temperature. The excitation spectra indicate that these phosphors can be effectively excited by Hg-free excitation. The emission spectra exhibit strong blue performance, which is due to the 4f(6) 5d(1) →4f(7) transition of Eu(2+) . The Fourier transform infrared spectrum at room temperature was investigated and surface morphology has been studied by scanning electron microscope. The prepared phosphor exhibited intense blue emission at the 427 nm owing to Eu(2+) ion by Hg-free excitation at 330 nm, that is, solid-state lighting excitation. Hence, the availability of such a phosphor will significantly help in the growth of blue-emitting solid-state lighting applications.

  16. Luminescence properties of red phosphors Ca10Li (PO4)7:Eu3+

    Institute of Scientific and Technical Information of China (English)

    SONG Enhai; ZHAO Weiren; ZHOU Guoxiong; DOU Xihua; YI Chunyu; ZHOU Minkang

    2011-01-01

    A series of red phosphors Ca10Li (PO4)7:Eu3+ were synthesized by high temperature solid-state reaction method. Their luminescence properties were characterized by means of photoluminescence excitation and emission spectra, CIE chromaticity and quantum efficiency. Results indicated that the phosphors could be effectively excited by the near ultraviolet (NUV) light (393 nm). The main emission peaks of the phosphor were ascribed to the transition 5D0-7F2 (613 and 617 nm) of Eu3+ ion when samples were excited by 393 nm. The CIE chromaticity (x,y) of Ca9.9Li (PO4)7:0.10Eu3+ was x=0.638, y=0.361 and the quantum efficiency of this phosphor was 75% excited by 393 nm.Therefore, this phosphor could be a promising red component for the applications in white LEDs.

  17. Self-adaptive phosphor coating technology for wafer-level scale chip packaging

    Institute of Scientific and Technical Information of China (English)

    Zhou Linsong; Rao Haibo; Wang Wei; Wan Xianlong; Liao Junyuan; Wang Xuemei; Zhou Da

    2013-01-01

    A new self-adaptive phosphor coating technology has been successfully developed,which adopted a slurry method combined with a self-exposure process.A phosphor suspension in the water-soluble photoresist was applied and exposed to LED blue light itself and developed to form a conformal phosphor coating with selfadaptability to the angular distribution of intensity of blue light and better-performing spatial color uniformity.The self-adaptive phosphor coating technology had been successfully adopted in the wafer surface to realize a waferlevel scale phosphor conformal coating.The first-stage experiments show satisfying results and give an adequate demonstration of the flexibility of self-adaptive coating technology on application of WLSCP.

  18. Hermetic atomism: Christian Adolph Balduin (1632-1682), Aurum Aurae, and the 1674 phosphor.

    Science.gov (United States)

    Keller, Vera

    2014-11-01

    The synthesis of phosphors, or light-bearing matter, figured largely among the activities of early scientific societies and within the first scientific journals. They were prestige objects during the formative institutionalisation of experimental natural philosophy. Nevertheless, early phosphors have often appeared within the historiography of chemistry as a throwback to an earlier era. They have been represented as a fundamental epistemic and theoretical divide between a mystical alchemy (exemplified by Christian Adolph Balduin) and modern chemistry (prefigured by progressives such as Robert Boyle). The parallel phosphoric researches of Boyle and Balduin belie this divide. Recovering the theoretical context of Balduin's phosphor can both resituate it in relation to phosphoric research of the 1670s and 1680s, as well as further illuminate the intellectual sources and development of chymical atomism.

  19. Luminescent characteristics of LiCaBO3:Eu3+ phosphor for white light emitting diode

    Institute of Scientific and Technical Information of China (English)

    LI Panlai; YANG Zhiping; WANG Zhijun; GUO Qinglin

    2009-01-01

    LiCaBO3:Eu3+ phosphor was synthesized by high solid-state reaction method, and its luminescent characteristics were investigated. The emission and excitation spectra of LiCaBO3:Eu3+ phosphors exhibited that the phosphors could be effectively excited by near ultraviolet (400 nm) and blue (470 nm) light, and emitted red light. The effect of Eu3+ concentration on the emission spectrum of LiCaBO3:Eu3+ phos-phor was studied. The results showed that the emission intensity increased with increasing Eu3~ concentration, and then decreased because of concentration quenching. It reached the maximum at 3mol.% Eu3+, and the concentration self-quenching mechanism was the d-d interaction according to the Dexter theory. Under the conditions of charge compensator Li+, Na+ or K+ incorporated in LiCaBO3, the emission intensities of LiCaBO3:Eu3+ phosphor were enhanced.

  20. Luminescent Characteristics of LiSrBO3:Eu3+ Phosphor for White Light Emitting Diode

    Institute of Scientific and Technical Information of China (English)

    LI Pan-Lai; WANG Zhi-Jun; YANG Zhi-Ping; GUO Qing-Lin

    2009-01-01

    @@ LiSrBBO3:Eu>3+ phosphor is synthesized by a high solid-state reaction method, and its luminescent characteristics are investigated. The emission and excitation spectra of LiSrBO3:Eu>3+ phosphors exhibit that the phosphors can be effectively excited by near ultraviolet (401 nm) and blue (471 nm) light, and emit 615nm red light. The effect of Eu3+ concentration on the emission spectrum of LiSrBO3:Eu>3+ phosphor is studied; the results show that the emission intensity increases with increasing Eu3+ concentration, and then decreases because of concentration quenching. It reaches the maximum at 3mol%, and the concentration self-quenching mechanism is the dipole-dipole interaction according to the Dexter theory. Under the conditions of charge compensation Li+, Na+ or K+ incorporated in LiSrBO3, the luminescent intensities of LiSrBO3:Eu>3+ phosphor are enhanced.

  1. Colour-crafted phosphor-free white light emitters via in-situ nanostructure engineering

    Science.gov (United States)

    Min, Daehong; Park, Donghwy; Lee, Kyuseung; Nam, Okhyun

    2017-03-01

    Colour-temperature (Tc) is a crucial specification of white light-emitting diodes (WLEDs) used in a variety of smart-lighting applications. Commonly, Tc is controlled by distributing various phosphors on top of the blue or ultra violet LED chip in conventional phosphor-conversion WLEDs (PC-WLEDs). Unfortunately, the high cost of phosphors, additional packaging processes required, and phosphor degradation by internal thermal damage must be resolved to obtain higher-quality PC-WLEDs. Here, we suggest a practical in-situ nanostructure engineering strategy for fabricating Tc-controlled phosphor-free white light-emitting diodes (PF-WLEDs) using metal-organic chemical vapour deposition. The dimension controls of in-situ nanofacets on gallium nitride nanostructures, and the growth temperature of quantum wells on these materials, were key factors for Tc control. Warm, true, and cold white emissions were successfully demonstrated in this study without any external processing.

  2. Thermal stability and oil absorption of aluminum hydroxide treated by dry modification with phosphoric acid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The dry modification of aluminum hydroxide powders with phosphoric acid and the effects of modification of technological conditions on thermal stability, morphology and oil absorption of aluminum hydroxide powders were investigated. The results show that the increase of mass ratio of phosphoric acid to aluminum hydroxide, the decrease of mass concentration of phosphoric acid and prolongation of mixing time are favorable to the improvement of thermal stability of aluminum hydroxide; when the mass ratio of phosphoric acid to aluminum hydroxide is 5:100, the mass concentration of phosphoric acid is 200 g/L and the mixing time is 10 min, the initial temperature of loss of crystal water in aluminum hydroxide rises from about 192.10 to 208.66 ℃2,but the dry modification results in the appearance of agglomeration and macro-aggregate in the modified powders, and the oil absorption of modified powders becomes higher than that of original aluminum hydroxide.

  3. On the use of bastnasite ore as a phosphor material

    Energy Technology Data Exchange (ETDEWEB)

    Mohapatra, M., E-mail: manojm@barc.gov.in; Natarajan, V.; Rajeswari, B.; Dhobale, A.R.; Godbole, S.V.

    2014-01-15

    Bastnasite ore obtained from Indian Rare Earth (IRE) was investigated for its possible use as a phosphor material. The material was characterized by X-ray diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), photoacoustic spectroscopy (PAS), photoluminescence (PL) and electron paramagnetic resonance spectroscopy (EPR) techniques. XRD studies revealed the semi processed ore to be consisting of single phase CeO{sub 2} with no other impurities. EDXRF studies revealed the presence of ‘Th’ and traces of ‘Sm’ along with ‘Ce’ in the sample. PAS studies revealed the presence of strong charge transfer from oxygen to cerium in the system. PL studies confirmed the presence of at least four trivalent rare earths, viz. Sm, Eu, Dy and Tb in the system in trace quantities. The emission spectrum and decay time data were evaluated. It was observed that the rare earth ions are situated at distorted sites in the system surrounded by defect centers. EPR studies confirmed the presence of Ce{sup 3+}in the system along with electron trapped in oxygen ion vacancies. CIE indices for the ore sample were evaluated and it was seen that the overall emission from the system was in the ‘magenta’ region of the visible spectrum. The emission intensities were also compared with that of commercial samples. -- Highlights: • Characterization of bastnasite ore as a phosphor material. • Role of RE impurities in the luminescence • CIE index of the bastnasite ore.

  4. Pretreatment of moso bamboo with dilute phosphoric acid

    Directory of Open Access Journals (Sweden)

    Bo Hong

    2012-11-01

    Full Text Available Dilute phosphoric acid pretreatment of moso bamboo materials was studied for producing high quality dissolving pulp for textile applications. The dynamics of dilute acid pretreatment were considered. The Saeman model was found to describe well the acid hydrolysis of moso bamboo hemicelluloses to their monomers under different temperatures and different dilute phosphoric acid concentrations. The initial degradation rate of hemicelluloses was much higher than its subsequent degradation rate, and the xylose generation rate increased with increasing temperature. The change rule of the pentose extraction rate was considered along with the pretreatment factor (P factor. Optimum dilute acid pretreatment conditions were 170 °C and 45 minutes. Based on the optimum conditions and a mass balance of sugars, a weight loss of 26.5% of the solid and liquid fractions combined was observed after the pretreatment. SEM results revealed that the moso bamboo fibers surfaces and cell wall were damaged. With the surface area increasing, the accessible pore areas also increased. At the same time, the crystallinity of the cellulose was reduced, which created a favorable environment for chemical penetration in the subsequent treatment.

  5. Geopolymers Based on Phosphoric Acid and Illito-Kaolinitic Clay

    Directory of Open Access Journals (Sweden)

    S. Louati

    2016-01-01

    Full Text Available New three-dimensional geopolymer materials based on illito-kaolinitic clay and phosphoric acid were synthesized. The effect of Si/P molar ratio on the geopolymers properties was studied. Raw, calcined clay, and geopolymers structures were investigated using XRD, IR spectroscopy, and SEM. The phosphoric acid-based geopolymers mechanical properties were evaluated by measuring the compressive strength. The Si/P molar ratio was found to increase with the increase of the compressive strength of the obtained geopolymers, which attained a maximum value at Si/P equal to 2.75. Beyond this ratio, the mechanical strength decreases. The XRD patterns of these geopolymers samples have proven that when the Si/P molar ratio decreases, the amorphous phase content increases. Besides, the structural analyses have revealed the presence of aluminum phosphate and Si-O-Al-O-P polymeric structure, whatever the Si/P molar ratio is (between 2.25 and 3.5. The obtained results have confirmed that the presence of the associated minerals such as hematite and quartz in the clay does not prevent the geopolymerization reaction, but the presence of illite mineral seems to have a modest contribution in the geopolymerization.

  6. Effect of finite phosphor thickness on detective quantum efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Nishikawa, R.M.; Yaffe, M.J.; Holmes, R.B. (Univ. of Toronto (Canada))

    1989-09-01

    In this paper we describe theoretically the relationship between the finite thickness of a phosphor screen and its spatial-frequency-dependent detective quantum efficiency DQE(f-). The finite thickness of the screen causes a variation in both the total number of light quanta emitted from the screen in a burst from a given x-ray interaction and in the spatial distribution of the quanta within the light burst (i.e., shape or point spread function (PSF) of the light burst). The variation in magnitude of the burst gives rise to a spatial-frequency-independent reduction in DQE, characterized by the scintillation efficiency As. The variation in PSF causes a roll off in DQE with increasing spatial frequency which we have characterized by the function Rc(f). Both As and Rc(f) can be determined from the moments of the distribution of the spatial Fourier spectrum of light bursts emitted from the phosphor and thus they are related: As is a scaling factor for Rc(f). Our theory predicts that it is necessary for all light bursts which appear at the output to have the same magnitude to maximize As and the same shape to maximize Rc(f). These requirements can lead to the result that the fluorescent screen with the highest modulation transfer function will not necessarily have the highest DQE(f) even at high spatial frequencies.

  7. Flat Absorber Phosphorous Black Nickel Coatings for Space Applications

    Institute of Scientific and Technical Information of China (English)

    V. Maria Shalini; P. Arockiasamy; R. Urna Rani; A.K. Sharma

    2012-01-01

    A new process of flat absorber black nickel alloy coating tion from a bath containing nickel, zinc and ammonium was developed on stainless steel by electrodeposi- sulphates; thiocyanate and sodium hypophosphite for space applications. Coating process was optimized by investigating the effects of plating parameters, viz concentration of bath constituents, current density, temperature, pH and plating time on the optical properties of the black deposits. Energy dispersive X-ray spectroscopy showed the inclusion of about 6% phosphorous in the coating. The scanning electron microscopy studies revealed the amorphous nature of the coating. The corrosion resistance of the coatings was evaluated by the electrochemical impedance spectroscopy (EIS) and linear polarization (LP) techniques. The results revealed that, phosphorous addition confers better corro- sion resistance in comparison to conventional black nickel coatings. The black nickel coating obtained from hypophosphite bath provides high solar absorptance (αs) and infrared emittance (εIR) of the order of 0.93. Environmental stability to space applications was established by the humidity and thermal cycling tests.

  8. The effect of Tb{sup +3} on α-Sr{sub 2}P{sub 2}O{sub 7} phosphor for green LED phosphor application

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Nimesh P., E-mail: nimesh.0112@gmail.com, E-mail: mnsmsu@gmail.com; Srinivas, M.; Verma, Vishwnath; Modi, Dhaval [Department of Physics, Faculty of Science, The M. S. University of Baroda, Vadodara-390002 (India)

    2015-06-24

    A series of Tb{sup +3} activated α-Sr{sub 2}P{sub 2}O{sub 7} (Strontium Pyrophosphate) phosphors were synthesized by high temperature combustion synthesis method. The structural analysis has been done by x-ray diffraction and FTIR (Fourier Transform Infrared Spectrum). The results obtained in structural characterization indicate that the doping concentration did not affect the crystal phase and structure of the phosphors. X-ray diffraction pattern reveals that the all samples were consistence with the JCPDS card No. 24-1011. The phosphor was excited at 232 nm wavelength, very intense PL green emission peak have been observed at 545 nm. This illustrates, that the phosphors could be efficiently excited because of the charge transfer band of the host as well as the energy transfer process occurred between host (Sr{sub 2}P{sub 2}O{sub 7}) and activator (Tb{sup +3}). By increasing the doping concentration of Tb{sup +3}, the intensity of 545 nm emission peak has been increased predominantly and it suggest that the phosphor prepared has very good application in green LED phosphor.

  9. 40 CFR 721.6100 - Phosphoric acid, C6-12-alkyl esters, compounds with 2-(dibutylamino) ethanol.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid, C6-12-alkyl esters... Significant New Uses for Specific Chemical Substances § 721.6100 Phosphoric acid, C6-12-alkyl esters... reporting. (1) The chemical substances identified as phosphoric acid, C6-12-alkyl esters, compounds with 2...

  10. Response of Groundnut (�JL-24� Cultivar to Mycorrhiza Inoculation and Phosphorous Application

    Directory of Open Access Journals (Sweden)

    Khirood DOLEY

    2012-08-01

    Full Text Available A pot experiment was conducted on peanut Arachis hypogaea L. during 2007 growing season to determine their growth characteristics due to mycorrhizal inoculation and two different levels of soluble phosphorous application. Due to inoculation by AM fungi the growth parameters such as leaf number, shoot length, root length, fresh weight, dry weight, pod number and nodule number were significantly increased but two different level of phosphate also showed growth. However, growth parameters showed variable results when two different level of phosphate was applied along with AM fungi. Without phosphorous the mycorrhizal groundnut showed significant growth but when first low level of phosphorous was applied it showed more significant growth, however most significant result was observed with second high level of phosphorous application to the groundnut plant. Total chlorophyll content and acid and alkaline phosphatase activity was also significantly higher but most significant were observed when first level of phosphorous was applied followed by second level of phosphorous. The percent root colonization by mycorrhizal fungus Glomus fasciculatum was higher due to application of phosphorous but mycorrhizal dependency went on decreasing due to increase in the level of phosphorous. The different level of phosphorous had significant effect on growth and physiological parameters of mycorrhizal and non-mycorrhizal Arachis plants after 30, 60 and 90 days of growth period. However, the obtained results proved the improvement in plant growth with application of phosphorous. Thus, for increase in production of groundnut in the state of Maharashtra seems to be feasible option for increasing the overall production and yield.

  11. Depth-Penetrating Measurements Developed for Thermal Barrier Coatings Incorporating Thermographic Phosphors

    Science.gov (United States)

    Eldridge, Jeffrey I.; Bencic, Timothy J.

    2004-01-01

    The insulating properties of thermal barrier coatings (TBCs) provide highly beneficial thermal protection to turbine engine components by reducing the temperature sustained by those components. Therefore, measuring the temperature beneath the TBC is critical for determining whether the TBC is performing its insulating function. Currently, noncontact temperature measurements are performed by infrared pyrometry, which unfortunately measures the TBC surface temperature rather than the temperature of the underlying component. To remedy this problem, the NASA Glenn Research Center, under the Information Rich Test Instrumentation Project, developed a technique to measure the temperature beneath the TBC by incorporating a thin phosphor layer beneath the TBC. By performing fluorescence decay-time measurements on light emission from this phosphor layer, Glenn successfully measured temperatures from the phosphor layer up to 1100 C. This is the first successful demonstration of temperature measurements that penetrate beneath the TBC. Thermographic phosphors have a history of providing noncontact surface temperature measurements. Conventionally, a thermographic phosphor is applied to the material surface and temperature measurements are performed by exciting the phosphor with ultraviolet light and then measuring the temperature-dependent decay time of the phosphor emission at a longer wavelength. The innovative feature of the new approach is to take advantage of the relative transparency of the TBC (composed of yttria-stabilized zirconia) in order to excite and measure the phosphor emission beneath the TBC. The primary obstacle to achieving depth-penetrating temperature measurements is that the TBCs are completely opaque to the ultraviolet light usually employed to excite the phosphor. The strategy that Glenn pursued was to select a thermographic phosphor that could be excited and emit at wavelengths that could be transmitted through the TBC. The phosphor that was selected was

  12. Radioluminescence of red-emitting Eu-doped phosphors for fiberoptic dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Molina, P.; Santiago, M.; Marcazzo, J.; Caselli, E. [Universidad Nacional del Centro de la Provincia de Buenos Aires, Instituto de Fisica Arroyo Seco, Pinto 399, 7000 Tandil (Argentina); Spano, F. [Autoridad Regulatoria Nuclear, Av. del Libertador 8250, 1429 Buenos Aires (Argentina); Henniger, J. [Institut fur Kern-und Teilchenphysik, Zellescher Weg 19, 01069 Dresden (Germany); Cravero, W., E-mail: pmolina@exa.unicen.edu.ar [Universidad Nacional del Sur, Departamento de Fisica, Av. Colon 80, 8000FTN Bahia Blanca, Buenos Aires (Argentina)

    2011-10-15

    The fiberoptic dosimetry technique (FOD) has become an attractive method for in-vivo real-time dosimetry in radiotherapy. It is based on the use of a tiny piece of scintillator coupled to the end of an optical fiber, which collects the light emitted by the scintillator during irradiation (radioluminescence). Carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) is one of the most radioluminescence materials for FOD due to its high efficiency but it presents the drawback of emitting in the spectral region, where spurious luminescence is also important. Spurious luminescence from optical fiber, termed stem effect, is the main problem afflicting FOD. Several techniques have been applied to remove the stem effect. Optical filtering, which consists in using long-pass filters, is the simplest one. This technique is useful when red-emitting scintillators are employed. In this work, the feasibility of using red-emitting Eu-doped phosphors as FOD scintillators has been investigated. (Author)

  13. Variations of Phosphorous Accessibility Causing Changes in Microbiome Functions in the Gastrointestinal Tract of Chickens

    Science.gov (United States)

    Tilocca, Bruno; Witzig, Maren; Rodehutscord, Markus

    2016-01-01

    The chicken gastrointestinal tract (GIT) harbours a complex microbial community, involved in several physiological processes such as host immunomodulation and feed digestion. For the first time, the present study analysed dietary effects on the protein inventory of the microbiome in crop and ceca of broilers. We performed quantitative label-free metaproteomics by using 1-D-gel electrophoresis coupled with LC-MS/MS to identify the structural and functional changes triggered by diets supplied with varying amount of mineral phosphorous (P) and microbial phytase (MP). Phylogenetic assessment based on label-free quantification (LFQ) values of the proteins identified Lactobacillaceae as the major family in the crop section regardless of the diet, whereas proteins belonging to the family Veillonellaceae increased with the P supplementation. Within the ceca section, proteins of Bacteroidaceae were more abundant in the P-supplied diets, whereas proteins of Eubacteriaceae decreased with the P-addition. Proteins of the Ruminococcaceae increased with the amount of MP while proteins of Lactobacillaceae were more abundant in the MP-lacking diets. Classification of the identified proteins indicated a thriving microbial community in the case of P and MP supplementation, and stressed microbial community when no P and MP were supplied. Data are available via ProteomeXchange with identifier PXD003805. PMID:27760159

  14. Luminescence properties of Eu2+, Gd3+and Pr3+doped translucent Sialon phosphors

    Institute of Scientific and Technical Information of China (English)

    Bhupendra Joshi; Soo Wohn Lee

    2015-01-01

    Optical properties of hot pressed Sialon ceramics doped with different rare earth oxides (REOs) i.e. Eu2O3, Gd2O3, and Pr2O3 were investigated. Theα-Sialon phase was the main phase obtained after sintering as observed by X-ray diffraction (XRD). The transparency of different samples of varying thickness measured from UV to IR region revealed that the samples were translucent in the visible region while transparent in IR region. The thin samples of 150μm thickness had transmittance as high as 30%in the visible region. The luminescence was observed in transmittance mode to investigate the effect of sample thickness on luminescence intensity. We observed blue, yellow and red emissions in Sialon doped with Gd2O3, Eu2O3, and Pr2O3, respectively. The excitation wavelength for Gd2O3 and Pr2O3 doped samples were in UV region i.e. 280 and 270 nm, respectively, whereas, for Eu2O3 doped samples was in the blue region (460 nm). The Eu2O3 doped Sialon having 300μm thickness showed better white light extraction as coupled with blue LED. Moreover, the fabricated phosphor samples exhibited high hardness around 20 GPa and fracture toughness above 5 MPa·m1/2.

  15. High luminous flux from single crystal phosphor-converted laser-based white lighting system

    KAUST Repository

    Cantore, Michael

    2015-12-14

    The efficiency droop of light emitting diodes (LEDs) with increasing current density limits the amount of light emitted per wafer area. Since low current densities are required for high efficiency operation, many LED die are needed for high power white light illumination systems. In contrast, the carrier density of laser diodes (LDs) clamps at threshold, so the efficiency of LDs does not droop above threshold and high efficiencies can be achieved at very high current densities. The use of a high power blue GaN-based LD coupled with a single crystal Ce-doped yttrium aluminum garnet (YAG:Ce) sample was investigated for white light illumination applications. Under CW operation, a single phosphor-converted LD (pc-LD) die produced a peak luminous efficacy of 86.7 lm/W at 1.4 A and 4.24 V and a peak luminous flux of 1100 lm at 3.0 A and 4.85 V with a luminous efficacy of 75.6 lm/W. Simulations of a pc-LD confirm that the single crystal YAG:Ce sample did not experience thermal quenching at peak LD operating efficiency. These results show that a single pc-LD die is capable of emitting enough luminous flux for use in a high power white light illumination system.

  16. Study of electron-vibrational interaction and concentration quenching effect of Cu+ ions in lithium based sulphate phosphors

    Science.gov (United States)

    Bhoyar, Priyanka D.; Choithrani, Renu; Dhoble, S. J.

    2016-07-01

    The objective of this work is to study electron-vibrational interaction (EVI) and concentration quenching and their manifestation in experimental photoluminescence spectra of Cu+ ion in various lithium based phosphors namely, Li2SO4, LiNaSO4 and LiKSO4. The main parameters of EVI, such as the Stokes shift, Huang-Rhys factor and zero-phonon line positions, were estimated. The studied systems shows strong electron lattice coupling. The validity of results was established by modeling the shape of the emission spectra, which was found to be in good agreement with experimental photoluminescence spectra. The concentration quenching study is also carried out for these compounds. The studied systems correspond to the nearest neighbor energy transfer mechanism.

  17. Microwave synthesis of non-crystalline BCNO phosphors using thiourea as nitrogen source and their tunable luminescence

    Science.gov (United States)

    Chen, Jingjing; Zhao, Yang; Mao, Zhiyong; Wang, Dajian; Bie, Lijian

    2017-02-01

    Thiourea was employed as nitrogen source to synthesize BCNO phosphors by a simple microwave heating route. The phase structure, chemical composition, and the dependence of photoluminescent properties on the carbon content and incident excitation light for as-prepared BCNO phosphors were investigated in detail. Non-crystalline powder samples constituted by B, C, N, O elements with a slight of S dopant were identified for the prepared BCNO phosphors. Tunable luminescence induced by carbon content and incident excitation light implies the obtained non-crystalline BCNO phosphors could be used as an excellent candidate for LED conversion phosphor.

  18. Radionuclide concentrations in raw and purified phosphoric acids from Brazil and their processing wastes: implications for radiation exposures.

    Science.gov (United States)

    da Conceição, Fabiano Tomazini; Antunes, Maria Lúcia Pereira; Durrant, Steven F

    2012-02-01

    Radionuclides from the U and Th natural series are present in alkaline rocks, which are used as feedstock in Brazil for the production of raw phosphoric acid, which can be considered as a NORM (naturally occurring radioactive material). As a result of the purification of raw phosphoric acid to food-grade phosphoric acid, two by-products are generated, i.e., solid and liquid wastes. Taking this into account, the main aim of this study was to evaluate the fluxes of natural radionuclide in the production of food-grade phosphoric acids in Brazil, to determine the radiological impact caused by ingestion of food-grade phosphoric acid, and to evaluate the solid waste environmental hazards caused by its application in crop soils. Radiological characterization of raw phosphoric acid, food-grade phosphoric acid, solid waste, and liquid waste was performed by alpha and gamma spectrometry. The (238)U, (234)U, (226)Ra, and (232)Th activity concentrations varied depending on the source of raw phosphoric acid. Decreasing radionuclides activity concentrations in raw phosphoric acids used by the producer of the purified phosphoric acid were observed as follows: Tapira (raw phosphoric acid D) > Catalão (raw phosphoric acids B and C) > Cajati (raw phosphoric acid A). The industrial purification process produces a reduction in radionuclide activity concentrations in food-grade phosphoric acid in relation to raw phosphoric acid produced in plant D and single raw phosphoric acid used in recent years. The most common use of food-grade phosphoric acid is in cola soft drinks, with an average consumption in Brazil of 72 l per person per year. Each liter of cola soft drink contains 0.5 ml of food-grade phosphoric acid, which gives an annual average intake of 36 ml of food-grade phosphoric acid per person. Under these conditions, radionuclide intake through consumption of food-grade phosphoric acid per year per person via cola soft drinks is not hazardous to human health in Brazil

  19. Contrast and decay of cathodoluminescence from phosphor particles in a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Engelsen, Daniel den; Harris, Paul G.; Ireland, Terry G., E-mail: terry.ireland@brunel.ac.uk; Fern, George R.; Silver, Jack

    2015-10-15

    Cathodoluminescence (CL) studies are reported on phosphors in a field emission scanning electron microscope (FESEM). ZnO: Zn and other luminescent powders manifest a bright ring around the periphery of the particles: this ring enhances the contrast. Additionally, particles resting on top of others are substantially brighter than underlying ones. These phenomena are explained in terms of the combined effects of electrons backscattered out of the particles, together with light absorption by the substrate. The contrast is found to be a function of the particle size and the energy of the primary electrons. Some phosphor materials exhibit a pronounced comet-like structure at high scan rates in a CL-image, because the particle continues to emit light after the electron beam has moved to a position without phosphor material. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. The effect of phosphor saturation on the determination of decay times by CL-microscopy was also investigated. - Highlights: • Contrast enhancement are observed in secondary electron and cathodoluminescent images of phosphor particles sitting on top of others. • Backscattered electrons largely explain the observed contrast enhancement. • After glow effects in CL-micrographs of phosphors enable the determination of decay times. • Phosphor saturation can be used to determine the decay time of individual spectral transitions.

  20. Addition of Grape Seed Extract Renders Phosphoric Acid a Collagen-stabilizing Etchant.

    Science.gov (United States)

    Liu, Y; Dusevich, V; Wang, Y

    2014-08-01

    Previous studies found that grape seed extract (GSE), which is rich in proanthocyanidins, could protect demineralized dentin collagen from collagenolytic activities following clinically relevant treatment. Because of proanthocyanidin's adverse interference to resin polymerization, it was believed that GSE should be applied and then rinsed off in a separate step, which in effect increases the complexity of the bonding procedure. The present study aimed to investigate the feasibility of combining GSE treatment with phosphoric acid etching to address the issue. It is also the first attempt to formulate collagen-cross-linking dental etchants. Based on Fourier-transformed infrared spectroscopy and digestion assay, it was established that in the presence of 20% to 5% phosphoric acid, 30 sec of GSE treatment rendered demineralized dentin collagen inert to bacterial collagenase digestion. Based on this positive result, the simultaneous dentin etching and collagen protecting of GSE-containing phosphoric acid was evaluated on the premise of a 30-second etching time. According to micro-Raman spectroscopy, the formulation containing 20% phosphoric acid was found to lead to overetching. Based on scanning and transmission electronic microscopy, this same formulation exhibited unsynchronized phosphoric acid and GSE penetration. Therefore, addition of GSE did render phosphoric acid a collagen-stabilizing etchant, but the preferable phosphoric acid concentration should be <20%.

  1. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    2015-01-01

    We study motivations for and outcomes of couples starting up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010, while comparing them to a set of comparable firms and couples. The main motivation for joint entrepreneurship is to create...

  2. The enhancement of light efficiency using modified phosphor which is coated sub-micro size sulfonated polystyrene beads

    Science.gov (United States)

    Lee, Haisung; Park, Yoongon; Chang, Myungwhun; Kim, Gangpil; Hong, Sangsu; Won, Hyungsik; Lee, Jongmyeon; Oh, Yongsoo

    2006-08-01

    We have improved charge character on the surface of phosphor particles by dispersed sub micro miter size sulfonate polystryrene beads and polyelectrolyte dispersant. The surface of TAG phosphor was analyzed with SIMS-TOF. Many hydrocarbon molecules were existed on the TAG phosphor. We could exchange the hydrocarbon into polyelectrolyte and sulfonated polystyrene beads. Characterization of the chemical bonging of polystyrene beads adhered on the surface of the TAG phosphor was archieved with x-ray photoemission spectroscopy (XPS) and FT-Raman. We could measure light efficiency of the white LED with integrating sphere spectrophotometer. Adhering sub micro miter size sulfonated polystyrene beads on the surface of TAG phosphor has enhanced extraction efficiency of light from phosphor. The sulfonated ligand and reduced difference of refractive index between phosphor and encapsulant material are responsible for the enhancement of extraction efficiency light from phosphor. Additional increase of light extraction has been observed when the phosphor particles were coated only on and near the LED chip. Surface modified phosphor particle and phosphor layer have improved LED light efficiency about ten percents.

  3. Synthesis and characterisation of optically tuneable, magnetic phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnan, Sivakumar, E-mail: balasivam@gmail.com [CSIRO Molecular and Health Technologies, Bag 10, Clayton, Victoria 3169 (Australia); Launikonis, Anton [CSIRO Molecular and Health Technologies, Bag 10, Clayton, Victoria 3169 (Australia); Osvath, Peter, E-mail: Peter.Osvath@csiro.au [CSIRO Molecular and Health Technologies, Bag 10, Clayton, Victoria 3169 (Australia); Swiegers, Gerhard F. [CSIRO Molecular and Health Technologies, Bag 10, Clayton, Victoria 3169 (Australia); Douvalis, Alexios P. [Department of Physics, University of Ioannina, P.O. Box 1186, 45110 Ioannina (Greece); Wilson, Gerard J. [CSIRO Molecular and Health Technologies, Bag 10, Clayton, Victoria 3169 (Australia)

    2010-04-15

    YVO{sub 4}:Eu{sup 3+} phosphor particles have been encapsulated with silica using core-shell technology to produce particles of 400-600 nm in size. The surface of the outer silica shell was further functionalised by the introduction of iron oxide nanoparticles, thus producing a material possessing both magnetic and luminescent properties. The YVO{sub 4}:Eu{sup 3+}-SiO{sub 2}-magnetite composite material was characterised by X-ray diffraction (XRD), Raman and Fourier transform IR spectroscopy, scanning electron microscopy and emission spectroscopy. Characterisation of the outer iron oxide coating with {sup 57}Fe Moessbauer spectroscopy, magnetization measurements and scanning electron microscopy reveals the presence of non-stoichiometric maghemite and magnetite nanoparticles of sizes less than {approx}20 nm.

  4. Phosphorous gettering in acidic textured multicrystalline solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Montesdeoca-Santana, A. [Departamento de Fisica Basica, Universidad de La Laguna (ULL), Avenida Astrofisico Francisco Sanchez 2, 38206 La Laguna, S/C de Tenerife (Spain); Fraunhofer Institut fuer Solare Energiesysteme ISE, Laboratory and Servicecenter Gelsenkirchen, Auf der Reihe 2, 45884 Gelsenkirchen (Germany); Jimenez-Rodriguez, E.; Diaz-Herrera, B.; Hernandez-Rodriguez, C. [Departamento de Fisica Basica, Universidad de La Laguna (ULL), Avenida Astrofisico Francisco Sanchez 2, 38206 La Laguna, S/C de Tenerife (Spain); Gonzalez-Diaz, B. [Departamento de Fisica Basica, Universidad de La Laguna (ULL), Avenida Astrofisico Francisco Sanchez 2, 38206 La Laguna, S/C de Tenerife (Spain); Departamento de Energia Fotovoltaica, Instituto Tecnologico y de Energias Renovables. Poligono Industrial de Granadilla s/n, 38600 San Isidro-Granadilla de Abona, S/C de Tenerife (Spain); Rinio, M.; Borchert, D. [Fraunhofer Institut fuer Solare Energiesysteme ISE, Laboratory and Servicecenter Gelsenkirchen, Auf der Reihe 2, 45884 Gelsenkirchen (Germany); Guerrero-Lemus, R. [Departamento de Fisica Basica, Universidad de La Laguna (ULL), Avenida Astrofisico Francisco Sanchez 2, 38206 La Laguna, S/C de Tenerife (Spain); Fundacion de Estudios de Economia Aplicada, Catedra Focus-Abengoa, Jorge Juan 46, 28001 Madrid (Spain)

    2011-03-15

    The influence of phosphorus gettering is studied in this work applied to an acidic textured multicrystalline silicon substrate. The texturization was achieved with an HF/HNO{sub 3} solution leading to nanostructures on the silicon surface. It has been demonstrated in previous works that this textured surface decreases the reflectance on the solar cell and increases the surface area improving the photon collection and enhancing the short circuit current. The present study investigates the effect on the minority carrier lifetime of the phosphorous diffusion when it is carried out on this textured surface. The lifetime is measured by means microwave photoconductance decay and quasi steady state phototoconductance devices. The diffused textured wafers are used to fabricate solar cells and their electrical parameters are analyzed. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Synthesis and optical study of barium magnesium aluminate blue phosphors

    Science.gov (United States)

    Jeet, Suninder; Sharma, Manoj; Pandey, O. P.

    2015-05-01

    Europium doped barium magnesium aluminate (BaMgAl10O17:Eu2+) phosphor was prepared via solution combustion method at 550°C using urea as a fuel. Morphological and optical properties of the prepared sample was studied by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Photoluminescence spectroscopy (PL). XRD result showed the formation of pure phase BaMgAl10O17(JCPDS 26-0163) along with an additional phase BaAl2O4(JCPDS 01-082-1350). TEM image indicated the formation of faceted particles with average particle size 40 nm. From PL spectra, a broad emission band obtained at about 450 nm attributes to 4f6 5d → 4f7 transition of Eu2+ which lies in the blue region of the visible spectrum.

  6. Synthesis and optical study of barium magnesium aluminate blue phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Jeet, Suninder, E-mail: suninder.jeet@thapar.edu; Pandey, O. P., E-mail: oppandey@thapar.edu [School of Physics and Materials Science, Thapar University, Patiala (147003), Punjab (India); Sharma, Manoj, E-mail: manojnarad@sggswu.org [Department of Nanotechnology, Sri Guru Granth Sahib World University, Fatehgarh Sahib(146406), Punjab (India)

    2015-05-15

    Europium doped barium magnesium aluminate (BaMgAl{sub 10}O{sub 17}:Eu{sup 2+}) phosphor was prepared via solution combustion method at 550°C using urea as a fuel. Morphological and optical properties of the prepared sample was studied by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Photoluminescence spectroscopy (PL). XRD result showed the formation of pure phase BaMgAl{sub 10}O{sub 17}(JCPDS 26-0163) along with an additional phase BaAl{sub 2}O{sub 4}(JCPDS 01-082-1350). TEM image indicated the formation of faceted particles with average particle size 40 nm. From PL spectra, a broad emission band obtained at about 450 nm attributes to 4f{sup 6} 5d → 4f{sup 7} transition of Eu{sup 2+} which lies in the blue region of the visible spectrum.

  7. Nickel and nickel-phosphorous matrix composite electrocoatings

    Institute of Scientific and Technical Information of China (English)

    Nicolas SPYRELLIS; Evangelia A. PAVLATOU; Styliani SPANOU; Alexandros ZOIKIS-KARATHANASIS

    2009-01-01

    Nickel and nickel-phosphorous matrix composite coatings reinforced by TiO2, SiC and WC particles were produced under direct and pulse current conditions from an additive-free Watts' type bath. The influence of the variable electrolysis parameters (type of current, frequency of current pulses and current density) and the reinforcing particles properties (type, size and concentration in the bath) on the surface morphology and the structure of the deposits was examined. It is demonstrated that the embedding of ceramic particles modifies in various ways the nickel electrocrystallisation process. On the other hand, Ni-P amorphous matrix is not affected by the occlusion of the particles. Overall, the imposition of pulse current conditions leads to composite coatings with increased embedded percentage and more homogenous distribution of particles in the matrix than coatings produced under direct current regime.

  8. Full scale phosphoric acid fuel cell stack technology development

    Science.gov (United States)

    Christner, L.; Faroque, M.

    1984-01-01

    The technology development for phosphoric acid fuel cells is summarized. The preparation, heat treatment, and characterization of carbon composites used as bipolar separator plates are described. Characterization included resistivity, porosity, and electrochemical corrosion. High density glassy carbon/graphite composites performed well in long-term fuel cell endurance tests. Platinum alloy cathode catalysts and low-loaded platinum electrodes were evaluated in 25 sq cm cells. Although the alloys displayed an initial improvement, some of this improvement diminished after a few thousand hours of testing. Low platinum loading (0.12 mg/sq cm anodes and 0.3 mg/sq cm cathodes) performed nearly as well as twice this loading. A selectively wetproofed anode backing paper was tested in a 5 by 15 inch three-cell stack. This material may provide for acid volume expansion, acid storage, and acid lateral distribution.

  9. Transmission electron microscopic examination of phosphoric acid fuel cell components

    Science.gov (United States)

    Pebler, A.

    1986-01-01

    Transmission electron microscopy (TEM) was used to physically characterize tested and untested phosphoric acid fuel cell (PAFC) components. Those examined included carbon-supported platinum catalysts, carbon backing paper, and Teflon-bonded catalyst layers at various stages of fabrication and after testing in pressurized PAFC's. Applicability of electron diffraction and electron energy loss spectroscopy for identifying the various phases was explored. The discussion focuses on the morphology and size distribution of platinum, the morphology and structural aspects of Teflon in catalyst layers, and the structural evidence of carbon corrosion. Reference is made to other physical characterization techniques where appropriate. A qualitative model of the catalyst layer that emerged from the TEM studies is presented.

  10. Technology development for phosphoric acid fuel cell powerplant, phase 2

    Science.gov (United States)

    Christner, L.

    1981-01-01

    The development of materials, cell components, and reformers for on site integrated energy systems is described. Progress includes: (1) heat-treatment of 25 sq cm, 350 sq cm and 1200 sq cm cell test hardware was accomplished. Performance of fuel cells is improved by using this material; (2) electrochemical and chemical corrosion rates of heat-treated and as-molded graphite/phenolic resin composites in phosphoric acid were determined; (3) three cell, 5 in. x 15 in. stacks operated for up to 10,000 hours and 12 in. x 17 in. five cell stacks were tested for 5,000 hours; (4) a three cell 5 in. x 15 in. stack with 0.12 mg Pt/sq cm anodes and 0.25 mg Pt/sq cm cathodes was operated for 4,500 hours; and (5) an ERC proprietary high bubble pressure matrix, MAT-1, was tested for up to 10,000 hours.

  11. Dual preparation of hydrophobic and hydrophilic BaWO{sub 4}:Eu phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Young-Sik; Huh, Young-Duk, E-mail: ydhuh@dankook.ac.kr

    2016-06-15

    Highlights: • Red-emitting BaWO{sub 4}:Eu phosphors were prepared in hexane-water bilayer system. • The hydrophobic nanometer-sized BaWO{sub 4}:Eu phosphors were obtained in hexane. • The hydrophilic micrometer-sized BaWO{sub 4}:Eu dendrites were obtained in water. - Abstract: BaWO{sub 4}:Eu phosphors were prepared by performing a solvothermal reaction in a water–hexane bilayer system. A barium oleate (and europium oleate) complex was obtained in hexane via a phase transfer reaction involving Ba{sup 2+} (and Eu{sup 3+}) ions in an aqueous solution of sodium oleate. The outer surfaces of the nanometer-sized BaWO{sub 4}:Eu phosphors were capped by the long alkyl chain of oleate; therefore, the hydrophobic nanometer-sized BaWO{sub 4}:Eu phosphors preferentially dissolved in the hexane layer. The micrometer-sized BaWO{sub 4}:Eu phosphors were obtained in the water layer. The BaWO{sub 4}:Eu phosphors prepared in hexane and water yielded sharp strong absorption and emission peaks at 464 and 615 nm, respectively, due to the {sup 7}F{sub 0} → {sup 5}D{sub 2} and the {sup 5}D{sub 0} →{sup 7} F{sub 2} transitions of the Eu{sup 3+} ions. The BaWO{sub 4}:Eu phosphors are good candidate red-emitting phosphors for use in InGaN blue-emitting diodes, which have an emission wavelength of 465 nm.

  12. Polarized white light from LEDs using remote-phosphor layer sandwiched between reflective polarizer and light-recycling dichroic filter.

    Science.gov (United States)

    Oh, Ji Hye; Yang, Su Ji; Do, Young Rag

    2013-09-09

    This study introduces an efficient polarized, white phosphor-converted, light-emitting diode (pc-LED) using a remote phosphor film sandwiched between a reflective polarizer film (RPF) and a short-wavelength pass dichroic filter (SPDF). The on-axis brightness of polarized white light emission of a RPF/SPDF-sandwiched phosphor film over a blue LED, showed greater recovery than that of a conventional unpolarized remote phosphor film over blue LED, due to the recycling effect of yellow light from an SPDF. The relative luminous efficacy of an RPF/SPDF-sandwiched phosphor film was made 1.40 times better by adding an SPDF on the backside of an RPF-capped phosphor film. A polarization ratio of 0.84 was demonstrated for a white LED with an RPF/SPDF-sandwiched phosphor film, in good agreement with the measured results from the RPF-only sample.

  13. Preparation of a Phosphor/TiO2 nanoparticle composite layer for applications in dye-sensitized solar cells

    Science.gov (United States)

    Shin, Seong Gwan; Kim, Kyung Hwan; Bark, Chung Wung; Choi, Hyung Wook

    2014-08-01

    The conversion luminescence of a phosphor from the ultraviolet region to the visible region can enhance the light harvesting in dye-sensitized solar cells (DSSCs), because many dyes can only absorb visible light. To explore the influence of phosphor additives on the conversion efficiency of DSSC, we introduce the nanocrystalline YAG:Eu phosphors into TiO2 photoelectrodes. The photoluminescence measurement showed that a broad solar spectrum including the ultraviolet region could be reabsorbed by the dye N-719 via conversion luminescence due to the phosphor. With the introduction of the phosphor, both the photocurrent and the photovoltage of the DSSC could be improved due to the enhanced light harvesting and the elevated energy levels of the oxides. With the optimal concentration of phosphor doping in the electrode, the cells light-to-electricity conversion efficiency could be improved by a factor of 1.14 compared to that for a cell without phosphor doping.

  14. Preparation of a phosphor/TiO{sub 2} nanoparticle composite layer for applications in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Seong Gwan; Kim, Kyung Hwan; Bark, Chung Wung; Choi, Hyung Wook [Gachon University, Seongnam (Korea, Republic of)

    2014-08-15

    The conversion luminescence of a phosphor from the ultraviolet region to the visible region can enhance the light harvesting in dye-sensitized solar cells (DSSCs), because many dyes can only absorb visible light. To explore the influence of phosphor additives on the conversion efficiency of DSSC, we introduce the nanocrystalline YAG:Eu phosphors into TiO{sub 2} photoelectrodes. The photoluminescence measurement showed that a broad solar spectrum including the ultraviolet region could be reabsorbed by the dye N-719 via conversion luminescence due to the phosphor. With the introduction of the phosphor, both the photocurrent and the photovoltage of the DSSC could be improved due to the enhanced light harvesting and the elevated energy levels of the oxides. With the optimal concentration of phosphor doping in the electrode, the cells light-to-electricity conversion efficiency could be improved by a factor of 1.14 compared to that for a cell without phosphor doping.

  15. Organometallic catalysts for primary phosphoric acid fuel cells

    Science.gov (United States)

    Walsh, Fraser

    1987-01-01

    A continuing effort by the U.S. Department of Energy to improve the competitiveness of the phosphoric acid fuel cell by improving cell performance and/or reducing cell cost is discussed. Cathode improvement, both in performance and cost, available through the use of a class of organometallic cathode catalysts, the tetraazaannulenes (TAAs), was investigated. A new mixed catalyst was identified which provides improved cathode performance without the need for the use of a noble metal. This mixed catalyst was tested under load for 1000 hr. in full cell at 160 to 200 C in phosphoric acid H3PO4, and was shown to provide stable performance. The mixed catalyst contains an organometallic to catalyze electroreduction of oxygen to hydrogen peroxide and a metal to catalyze further electroreduction of the hydrogen peroxide to water. Cathodes containing an exemplar mixed catalyst (e.g., Co bisphenyl TAA/Mn) operate at approximately 650 mV vs DHE in 160 C, 85% H3PO4 with oxygen as reactant. In developing this mixed catalyst, a broad spectrum of TAAs were prepared, tested in half-cell and in a rotating ring-disk electrode system. TAAs found to facilitate the production of hydrogen peroxide in electroreduction were shown to be preferred TAAs for use in the mixed catalyst. Manganese (Mn) was identified as a preferred metal because it is capable of catalyzing hydrogen peroxide electroreduction, is lower in cost and is of less strategic importance than platinum, the cathode catalyst normally used in the fuel cell.

  16. Use of secondary phosphorescence for determination of the dose absorbed in dosimetric phosphors

    CERN Document Server

    Yaek, I V

    2002-01-01

    The measuring method of optically stimulated persistence (OSP) based on both the time division of the stimulating irradiation and luminescent response registration was applied for the radiation dosimetry. It was shown that the stimulation by the short-wave radiation crossing with spectrum of the dosimetric phosphor is possible. The spectrum of the stimulation of industry dosimetric phosphors was measured. The characteristics of the OSP registration for the phosphors which has manganese Mn sup 2 sup + as the activator is considered. Decay time of inner center luminescence is 40-50 ms. This method is used for the dosimetry of the natural quartzes to determine their age.

  17. Red emission phosphor for real-time skin dosimeter for fluoroscopy and interventional radiology

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Masaaki, E-mail: QYJ05476@nifty.com; Chida, Koichi; Zuguchi, Masayuki [Department of Radiological Technology, Faculty of Medicine, School of Health Sciences, Tohoku University, 2-1 Seiryou-machi, Aoba-ku, Sendai 980-8575 (Japan)

    2014-10-15

    Purpose: There are no effective real-time direct skin dosimeters for interventional radiology. Such a scintillation dosimeter would be available if there was a suitable red emission phosphor in the medical x-ray range, since the silicon photodiode is a highly efficient device for red light. However, it is unknown whether there is a suitable red emission phosphor. The purpose of this study is to find a suitable red emission phosphor that can be used in x-ray dosimeters. Methods: Five kinds of phosphors which emit red light when irradiated with electron beams or ultraviolet rays in practical devices were chosen. For the brightness measurement, phosphor was put into transparent plastic cells or coated onto plastic sheets. The phosphors were irradiated with medical range x-rays [60–120 kV(peak), maximum dose rate of 160 mGy min{sup −1}], and the emission was measured by a luminance meter. Several characteristics, such as brightness, dose rate dependence, tube voltage dependence, and brightness stability, were investigated. Results: The luminescence of Y V O{sub 4}:Eu, (Y,Gd,Eu) BO{sub 3}, and Y{sub 2}O{sub 3}:Eu significantly deteriorated by 5%–10% when irradiated with continuous 2 Gy x-rays. The 0.5MgF{sub 2}⋅3.5MgO⋅GeO{sub 2}:Mn phosphor did not emit enough. Only the Y{sub 2}O{sub 2}S:Eu,Sm phosphor had hardly any brightness deterioration, and it had a linear relationship so that the x-ray dose rate could be determined from the brightness with sufficient accuracy. For the tube voltage dependence of the Y{sub 2}O{sub 2}S:Eu,Sm phosphor, the brightness per unit dose rate with 120 kV(peak) x-rays was 30% higher than that with 60 kV(peak) x-rays. Conclusions: Five kinds of phosphors were chosen as an x-ray scintillator for a real-time direct skin dosimeter. The Y V O{sub 4}:Eu, (Y,Gd,Eu)BO{sub 3}, and Y{sub 2}O{sub 3}:Eu phosphors had brightness deterioration caused by the x-rays. Only the Y{sub 2}O{sub 2}S:Eu,Sm phosphor had hardly any brightness deterioration

  18. The chemistry of artificial lighting devices lamps, phosphors and cathode ray tubes

    CERN Document Server

    Ropp, Richard C

    1993-01-01

    Both the early use of artificial lighting and current manufacturing methods concerning incandescent and fluorescent lamps are covered in this book. The protocols for manufacture of fluorescent lamp phosphors and those used in cathode ray tubes are also treated in some detail. This text surveys the amazing, vast array of artificial lighting devices known to date in terms of how they arose and are, or have been used by mankind. A complete description of the formulations and methodology for manufacturing all known phosphors is given. The book will serve as a repository of such phosphor manufactur

  19. Effect of preparation conditions in sol-gel method on yellow phosphor with wide spectrum

    Science.gov (United States)

    Lin, Yenchen; Inoue, Shuhei; Matsumura, Yukihiko; Chen, Jyh-Chen

    2017-01-01

    Among several methods to obtain white light in light emitting diodes (LEDs), mixing blue light with yellow light excited by blue light is the most effective and economical method. However, the quality of white light achieved by this method is poor, making it essential to develop high-quality yellow phosphors. In this study, we synthesized yellow phosphors with broad spectral width by the sol-gel method and studied the effect of various synthetic conditions on their photoluminescence spectra. Consequently, we optimized synthesis conditions for a series of yellow phosphors and found that excess europium doping caused quenching and reduced the quantum yield.

  20. Dose Dependence of Mechanoluminescence Properties in MgAl2O4: Dy Phosphor

    Directory of Open Access Journals (Sweden)

    Kabita K. Satapathy

    2013-01-01

    Full Text Available A reliable dosimetry is fundamental for quality assurance of the processes and irradiation products. All dosimetric systems for high doses have some limitation with regard to their use. Dosimetric system should be easy to use, fast to measure, and of low cost. Good phosphor which shows high luminescence properties may fulfil the above criteria in some way. MgAl2O4: Dy phosphor has been prepared by solution combustion technique and confirmed with the help of XRD. ML has been excited impulsively by dropping a load of mass 0.7 kg onto the phosphors from various heights; two distinct ML peaks are observed for all the samples. It is observed that MgAl2O4: Dy phosphor shows linear response to gamma-ray dose and low fading which can be used for dosimetric purpose.

  1. YAG: Ce Phosphors for WLED via Nano-Pesudoboehmite Sol-Gel Route

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The sub-micron sized YAG: Ce phosphors were synthesized via a modified sol-gel method by peptizing nano-pesudoboehmite particulate. It is found that YAG phase from the dried gel powders appears at 1000 ℃ then the pure YAG phase exists at a relatively lower sintering temperature of 1400 ℃. The smaller sizes of phosphors in the ranges of 1 ~ 3 μm are obtained due to the contribution of seeding effects of nano-sized alumina particles to strengthen each step of the processes. Both the excitation and emission spectra of photoluminescence of the phosphor obtained at 1400 ℃ meet well with the spectroscopic requirements of the WLED phosphors.

  2. THERMOGRAPHIC APPLICATIONS OF TEMPERATURE SENSITIVE FLUORESCENCE OF SrS:Cu PHOSPHORS

    Directory of Open Access Journals (Sweden)

    R. PUROHIT

    2010-12-01

    Full Text Available The present work aims at investigating the temperature sensitive fluoro-optic behaviour of Cu-activated strontium sulphide (SrS phosphors and its possible application in thermography. Accordingly, SrS (Cu phosphors have been synthesized and painted with the help of adhesive on silica substrate. The excitation and emission spectra of such phosphor coatings have been recorded at room temperature (25C. The temperature dependence of fluorescence intensity and the lifetime of phosphorescence have also been studied. From the systematic variation of these two parameters with temperature, it appears that these phosphors are good candidates for thermographic application, at least, in the temperature range of investigation (25-150C.

  3. Studies on organic carbon, nitrogen and phosphorous in the sediments of Mandovi Estuary, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Nasnolkar, C.M.; Shirodkar, P.V.; Singbal, S.Y.S.

    Sediment organic carbon, total nitrogen, total phosphorous and hydrography of the overlying waters of the estuarine region in Mandovi Estuary, Goa, India have been studied. The relationship of carbon and nutrients with sediment characteristics...

  4. Ytterbium Doped Gadolinium Oxide (Gd2O3:Yb3+ Phosphor: Topology, Morphology, and Luminescence Behaviour

    Directory of Open Access Journals (Sweden)

    Raunak Kumar Tamrakar

    2014-01-01

    Full Text Available Gd2O3:Yb3+ phosphor has been synthesized by the solid state reaction method with boric acid used as a flux. The resulting Gd2O3:Yb3+ phosphor was characterized by X-ray diffraction (XRD technique, Fourier transmission infrared spectroscopy (FTIR, scanning electron microscope (SEM and transmission electron microscope (TEM, and photoluminescence and thermoluminescence. The results of the XRD show that obtained Gd2O3:Yb3+ phosphor has a cubic structure. The average crystallite sizes could be calculated as 42.9 nm, confirmed by the TEM results. The study suggested that Yb3+ doped phosphors are potential luminescence material for IR laser diode pumping.

  5. Photoluminescence of Bi(2+)-doped BaSO4 as a red phosphor for white LEDs.

    Science.gov (United States)

    Cao, Renping; Peng, Mingying; Qiu, Jianrong

    2012-11-05

    Bi(2+)-doped BaSO(4) phosphor was synthesized in air via solid state reaction method. Three excitation bands and one emission band were observed at 260 nm ((2)P(1/2) → (2)S(1/2)), 452 nm ((2)P(1/2) → (2)P(3/2)(2)), 592 nm ((2)P(1/2) → (2)P(3/2)(1)), and 627 nm ((2)P(3/2)(1) → (2)P(1/2)), respectively. W-LEDs were demonstrated by using a blend composition of BaSO(4):Bi(2+) and YAG:Ce(3+) phosphors pumped with a 455 nm blue LEDs chip. The results indicate that BaSO(4):Bi(2+) phosphor is suitable as potential red phosphor for application in W-LEDs excited with blue LEDs chip.

  6. Molten Carbonate and Phosphoric Acid Stationary Fuel Cells: Overview and Gap Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Remick, R.; Wheeler, D.

    2010-09-01

    This report describes the technical and cost gap analysis performed to identify pathways for reducing the costs of molten carbonate fuel cell (MCFC) and phosphoric acid fuel cell (PAFC) stationary fuel cell power plants.

  7. Development of Advanced LED Phosphors by Spray-based Processes for Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Cabot Corporation

    2007-09-30

    The overarching goal of the project was to develop luminescent materials using aerosol processes for making improved LED devices for solid state lighting. In essence this means improving white light emitting phosphor based LEDs by improvement of the phosphor and phosphor layer. The structure of these types of light sources, displayed in Figure 1, comprises of a blue or UV LED under a phosphor layer that converts the blue or UV light to a broad visible (white) light. Traditionally, this is done with a blue emitting diode combined with a blue absorbing, broadly yellow emitting phosphor such as Y{sub 3}Al{sub 5}O{sub 12}:Ce (YAG). A similar result may be achieved by combining a UV emitting diode and at least three different UV absorbing phosphors: red, green, and blue emitting. These emitted colors mix to make white light. The efficiency of these LEDs is based on the combined efficiency of the LED, phosphor, and the interaction between the two. The Cabot SSL project attempted to improve the over all efficiency of the LED light source be improving the efficiency of the phosphor and the interaction between the LED light and the phosphor. Cabot's spray based process for producing phosphor powders is able to improve the brightness of the powder itself by increasing the activator (the species that emits the light) concentration without adverse quenching effects compared to conventional synthesis. This will allow less phosphor powder to be used, and will decrease the cost of the light source; thus lowering the barrier of entry to the lighting market. Cabot's process also allows for chemical flexibility of the phosphor particles, which may result in tunable emission spectra and so light sources with improved color rendering. Another benefit of Cabot's process is the resulting spherical morphology of the particles. Less light scattering results when spherical particles are used in the phosphor layer (Figure 1) compared to when conventional, irregular shaped

  8. One Step Combustion Synthesis Of YAG:Ce Phosphor For Solid State Lighting

    Science.gov (United States)

    Yadav, Pooja; Gupta, K. Vijay Kumar; Muley, Aarti; Joshi, C. P.; Moharil, S. V.

    2011-10-01

    YAG:Ce is an important phosphor having applications in various fields ranging from solid state lighting to scintillation detectors. YAG phosphors doped with activators are mainly synthesized by solid state reaction techniques that require high sintering temperatures (above 1500°C) to eliminate YAM and YAP phases. Though several soft chemical routes have been explored for synthesis of YAG, most of these methods are complex and phase pure materials are not obtained in one step, but prolonged annealing at temperatures around 1000 C or above becomes necessary. One step combustion synthesis of YAG:Ce3+ and related phosphors carried out at 500 C furnace temperature is reported here. Activation with Ce3+ could be achieved during the synthesis without taking recourse to any post-combustion thermal treatment. LEDs prepared from the combustion synthesized YAG:Ce3+, exhibited properties comparable to those produced from the commercial phosphor.

  9. Optical properties of rare earth doped strontium aluminate (SAO) phosphors: A review

    Science.gov (United States)

    Kshatri, D. S.; Khare, A.

    2014-11-01

    After the first news on rare earth (RE) doped strontium aluminate (SAO) phosphors in late 1990s, researchers all over the world geared up to develop stable and efficient persistent phosphors. Scientists studied various features of long lasting phosphors (LLP) and tried to earmark appropriate mechanism. However, about two decades after the discovery of SrAl2O4: Eu2+, Dy3+, the number of persistent luminescent materials is not significant. In this review, we present an overview of the optical characteristics of RE doped SAO phosphors in terms of photoluminescence (PL), thermoluminescence (TL) and afterglow spectra. Also, we refresh the work undertaken to study diverse factors like dopant concentration, temperature, surface energy, role of activator, etc. Simultaneously, some of our important findings on SAO are reported and discussed in the end.

  10. Color deviation controlling of phosphor conformal coating by advanced spray painting technology for white LEDs.

    Science.gov (United States)

    Yang, Liang; Wang, Simin; Lv, Zhicheng; Liu, Sheng

    2013-04-01

    An advanced phosphor conformal coating technology is proposed, good correlated color temperature (CCT) and chromaticity uniformity samples are fabricated through phosphor spray painting technology. Spray painting technology is also suitable for phosphor conformal coating of whole LED wafers. The samples of different CCTs are obtained through controlling the phosphor film thickness in the range of 6-80 μm; CCT variation of samples can be controlled in the range of ±200 K. The experimental Δuv reveals that the spray painting method can obtain a much smaller CCT variation (Δuv of 1.36e(-3)) than the conventional dispensing method (Δuv of 11.86e(-3)) when the light is emitted at angles from -90° to +90°, and chromaticity area uniformity is also improved significantly.

  11. Preparation optimization and spectral properties of BCNO phosphors with high quantum efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Chunrong; Zhang, Xinghua, E-mail: xinghua146@126.com; Zhou, Liyu; Lu, Zunming; Lin, Jing; Xu, Xuewen; Li, Lanlan; Zhang, Xiao; Xue, Yanming; Meng, Fanbin; Zhao, Jianling; Tang, Chengchun, E-mail: tangcc@hebut.edu.cn

    2014-09-15

    BCNO phosphors with high quantum efficiency (QE) were synthesized using trimethyl borate, melamine and urotropine as raw materials. The effects of urotropine, starting materials ratio, sintering time and temperature on luminescence properties were systematically investigated and the preparation conditions were optimized. The BCNO phosphor has turbostratic boron nitride structure and its size in the range of several millimeters. The emission peak position was not influenced by the content of urotropine. However, the emission peak blue can be tuned from 475 nm to 535 nm with increasing B/N source ratios (R{sub B/N}=2–6), while the QE decreased from 65.2% to 15.8%. The emission peaks of BCNO phosphor with R{sub B/N}=4 were in the range of green light (495–540 nm) with high QE (20.8–51.4%) as sintering time increased (4–20 h). In addition, the emission peaks of BCNO phosphor with R{sub B/N}=4 blue-shifted from 525 nm to 460 nm and increased QE (16.1–56.7%) with increasing sintering temperature (650–750 °C). The formation mechanism of BCNO phosphors was investigated by means of ultraviolet visible absorption spectra and infrared spectra. The tunable emission spectra and high QE corresponded to the chemical composition, carbon concentration and crystallinity of BCNO phosphors. - Highlights: • We prepared BCNO phosphors with high quantum efficiency (65.2%). • The effects of raw materials, sintering condition on spectral properties were investigated. • The formation and luminescence mechanism of BCNO phosphors were investigated.

  12. Modeling of Spatial and Temporal Variations of Phosphorous Cycling in Tree Islands of the Everglades

    Science.gov (United States)

    Lago, M.; Miralles-Wilhelm, F. R.

    2008-05-01

    A model to study the temporal and spatial variations on the phosphorous cycle around tree islands in Shark River Slough in the Everglades has been developed. It is based in a conceptual model that considers the convective and diffusive transport of dissolved phosphorous, adsorption on to soil, input from rainfall and animal activity, and the phosphorous cycle in biomass that includes uptake, release as litter, transport as suspended litter and release from the decomposition of the deposited litter. The developed model solved governing equations for water, phosphorous and biomass balances. The parameterization of the model was conducted by using the data collected in three tree islands of Shark River Slough, the time series data downloaded mainly from SFWMD's DBHYDRO, among other parameters reported the literature. The model was calibrated in three stages. Initially, Manning coefficients were adjusted from surface water velocity data. Then, calibration of several groundwater flow parameters was performed from water table data collected at wells by. Finally, the phosphorous input rate from animal activity and the initial concentration of phosphorous were calibrated. This study concluded that an external input rate of Phosphorous (e.g. from animal activity) is necessary to maintain the phosphorous levels in the areas around the head of the tree islands, to counteract losses from rainfall driven transport and suspended litter transport. This result points to the importance of the preservation of the wading birds and other wild life forms in the Everglades. The model also suggests an explanation for the sawgrass die-off events observed in the Everglades as well as a cyclic succession between marsh and tall sawgrass.

  13. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    We study possible motivations for co-entrepenurial couples to start up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and postdissolution private and financial outcomes...... with a selected set of comparable firms and couples. We find evidence that couples often establish a business together because one spouse – most commonly the female – has limited outside opportunities in the labor market. However, the financial benefits for each of the spouses, and especially the female...

  14. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    2015-01-01

    We study possible motivations for co-entreprenurial couples to start up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and post-dissolution private and financial outcomes...... with a selected set of comparable firms and couples. We find evidence that couples often establish a business together because one spouse – most commonly the female – has limited outside opportunities in the labor market. However, the financial benefits for each of the spouses, and especially the female...

  15. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    We study possible motivations for co-entrepenurial couples to start up a joint firm, us-ing a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and post-dissolution private and financial outcomes...... with a selected set of comparable firms and couples. We find evidence that couples often establish a business together because one spouse - most commonly the female - has limited outside opportunities in the labor market. However, the financial benefits for each of the spouses, and especially the female...

  16. New NaSrPO$_4$:Sm$^{3+}$ phosphor as orange-red emitting material

    Indian Academy of Sciences (India)

    KUN-HSIEN CHEN; MIN-HANG WENG; RU-YUAN YANG; CHENG-TANG PAN

    2016-09-01

    Sm$^{3+}$-activated NaSrPO4 phosphors could be efficiently excited at 403 nm, and exhibited a bright red emission mainly including four wavelength peaks of 565, 600, 646 and 710 nm. The highest emission intensity was foundfor NaSr$_{1−x}$PO$_{4}$:$x$Sm$^{3+}$ with a composition of $x = 0.007$. Concentration quenching was observed as the composition of $x$ exceeds 0.007. The decay time values of NaSr1−xPO4:xSm3+ phosphors range from around 2.55 to 3.49 ms. NaSr$_{1−x}$PO$_{4}$:$x$Sm$^{3+}$ phosphor shows a higher thermally stable luminescence and its thermal quenching temperature$T_{50}$ was found to be 350$^{\\circ}$C, which is higher than that of commercial YAG:Ce$^{3+}$ phosphor and ZnS:(Al, Ag) phosphor. Because NaSr$_{1−x}$PO$_{4}$:$x$Sm$^{3+}$ phosphor features a high colour-rendering index and chemical stability, it is potentially useful as a new scintillation material for white light-emitting diodes.

  17. SrMoO4:Er3+-Yb3+ upconverting phosphor for photonic and forensic applications

    Science.gov (United States)

    Soni, Abhishek Kumar; Rai, Vineet Kumar

    2016-08-01

    The Er3+-Yb3+ codoped strontium molybdate (SrMoO4) phosphors have been synthesized via chemical co-precipitation method by adding ammonium hydroxide as a base reagent. The phase, crystal structure and formation of spindle-like particles present in the prepared phosphors have been recognized by using the X-ray powder diffraction (XRPD) and Field emission scanning electron microscopy (FE-SEM) techniques. The Fourier transform infrared (FTIR) spectroscopy of the developed phosphors has been analyzed to mark the different functional groups present in synthesized phosphors. The multicolour upconversion emissions observed upon excitation with 980 nm and 808 nm laser diode have been explained on the basis of dopants ions concentration, pump power dependence, energy level structure and decay curve analysis. The colour co-ordinate study confirmed that the codoped phosphor emits non-tunable green colour when excited with the 980 nm laser diode, whereas it shows the colour tunability from yellow to green region upon excitation with the 808 nm laser diode. The applicability of non-tunable green colour emission has been demonstrated in the security ink and latent finger print detection. This shows the utility of the developed phosphors in the photonic and forensic applications.

  18. Pd tetrabenzoporphyrin-dendrimers: near-infrared phosphors for oxygen measurements by phosphorescence quenching

    Science.gov (United States)

    Vinogradov, Sergei A.; Kim, Evelyn; Wilson, David F.

    2002-06-01

    Phosphorescence quenching is an optical method for measuring tissue oxygenation. The technique is based on the quenching of phosphorescence originated from the injected dye by molecule oxygen dissolved in the medium. The phosphor is the only 'invasive' component of the measurement procedure, and thus it is important to have precise control over the bio- distribution of the phosphor, i.e. to confine it to a single compartment within the sample. For tissue applications the phosphor must also be an effective light absorber in the near IR and to exhibit oxygen quenching constant of 200-400 Torr-1 sec-1, to permit reliable quantification of oxygen in arterioles as well as in veins. Overall, it is desirable to have synthetic, inert, hydrophilic, phosphors with quenching characteristics that are not affected by molecules other than oxygen. We discuss a new generation of phosphors based on dendrimer- tetrabenzoporphyrins, designed to satisfy the above criteria. In these phosphors, the core metallotetrabenzoporphyrins prove the required physical characteristics, while their immediate surrounding environments consist of covalently attached dendritic branches. The dendritic cages around porphyrins control their quenching properties and protect porphyrins from interactions with other substances in the blood.

  19. Phosphorous acid residues in apples after foliar fertilization: results of field trials.

    Science.gov (United States)

    Malusà, E; Tosi, L

    2005-06-01

    The levels of phosphorous acid residues in apples after foliar fertilization with P fertilizers and after treatment with a phosphonate fungicide (Fosetyl-Al) were determined and compared. Two field trials and a glasshouse experiment, using different genotypes and plants of different age, were carried out and monitored over a three-year period. Phosphorous acid residues were found in apples after application of foliar P fertilizers. Concentrations of the residues ranged between 0.02 and 14 mg kg(-1) depending on the phosphorous acid content in the fertilizer used and the plant size and yield. The treatments induced an accumulation of the residue in the course of the experiments, which in some cases reached a level exceeding the maximum limit set by EU legislation. Residues were also detected in other plant organs, i.e., roots and buds. Plants treated with Fosetyl-Al contained phosphorous acid residues in their fruits and buds two years after the suspension of the treatment, suggesting a long-term persistence of the substance in plant storage organs. A second experiment, involving treatment of trees with seven foliar fertilizers of different composition, also induced accumulation of phosphorous acid residues in fruits. It is concluded that a wide array of foliar products containing phosphorous acid, even as a minor component, could mimic the residue effect of phosphonate fungicide treatments.

  20. Effect of Eu3+ Concentration on Luminescence Studies of Y4Al2O9 Phosphor

    Directory of Open Access Journals (Sweden)

    Vikas Dubey

    2014-01-01

    Full Text Available The present paper reports the effect of europium concentration on photoluminescence (PL and thermoluminescence (TL studies of Eu3+ doped Y4Al2O9 phosphor using inorganic materials like yttrium oxide (Y2O3, aluminium oxide (Al2O3, boric acid (H3BO3 as a flux, and europium oxide (Eu2O3. The sample was prepared by the modified solid state reaction method, which is the most suitable for large-scale production. The prepared phosphor sample was characterized using X-ray diffraction (XRD, field emission gun scanning electron microscopy (FEGSEM, Fourier transform infrared spectroscopy (FTIR, photoluminescence (PL, thermoluminescence (TL, and CIE techniques. The PL emission was observed in the range of 467, 535, 591, 611, 625, and 629 nm for the Y4Al2O9 phosphor doped with Eu3+ (0.1 mol% to 2.5 mol%. Excitation spectrum was found at 237 and 268 nm. Sharp peaks were found around 591, 611, and 625 nm with high intensity. From the XRD data, using Scherer’s formula, the calculated average crystallite size of Eu3+ doped Y4Al2O9 the phosphor is around 55 nm. Thermoluminescence study was carried out for the phosphor with UV irradiation. The present phosphor can act as single host for red light emission in display devices.

  1. SrAl2O4:Eu, Dy Nanometer Phosphors Synthesized by Combustion Method

    Institute of Scientific and Technical Information of China (English)

    Qiu Guanming; Sun Yanbin; Zhang Shengqu; Zhang Ming; Yan Changhao; Dai Shaojun

    2004-01-01

    SrAl2 O4: Eu, Dy nanometer phosphors were synthesized by combustion method at 500 ~ 900℃, followed by heating the combustion sample at 1150℃ at a weak reductive atmosphere and nanometer phosphor with much better luminescent properties was obtained. The influences of the initiating combustion temperature, H3BO3 quantity, the mass ratio of urea and nitrate on the luminescent intensity of nanometer phosphors were studied. The optimum synthetic conditions were determined. The analysis results by transmission electron microscopy (TEM) indicate that the particle size of the synthetic product is less than 75 nm. The luminescent materials do not need to be ground. Their coating can be refined. It supplies a new approach to the rapid preparation of the luminescent materials at low temperature. The excitation and emission spectra indicate that the main peaks in the excitation and emission spectrum of nanometer phosphor synthesized by combustion method shifted to the short wavelength compared with the phosphor obtained by the solidstate reaction synthesis method. The reason of blue shift was explained. The afterglow decay results indicate that the decay speed of the afterglow for nanometer phosphor is faster than that obtained by the solid-state reaction method.

  2. Mechanoluminescence properties of SrAl2O4:Eu(2+) phosphor by combustion synthesis.

    Science.gov (United States)

    Bisen, D P; Sharma, R

    2016-03-01

    In this paper, europium-doped strontium aluminate (SrAl2O4:Eu(2+)) phosphors were synthesized using a combustion method with urea as a fuel at 600°C. The phase structure, particle size, surface morphology and elemental analysis were studied using X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FTIR) spectra. The EDX and FTIR spectra confirm the elements present in the SrAl2O4:Eu(2+) phosphor. The optical properties of SrAl2O4:Eu(2+) phosphors were investigated by photoluminescence (PL) and mechanoluminescence (ML). The excitation and emission spectra showed a broad band with peaks at 337 and 515 nm, respectively. The ML intensities of SrAl2O4:Eu(2+) phosphor increased proportionally with the increase in the height of the mechanical load, which suggests that this phosphor could be used in stress sensors. The CIE colour chromaticity diagram and ML spectra confirm that the SrAl2O4:Eu(2+) phosphor emitted green coloured light.

  3. Performance enhancement of phosphoric acid fuel cell using phosphosilicate gel based electrolyte

    Institute of Scientific and Technical Information of China (English)

    Kajari Kargupta; Swati Saha; Dipali Banerjee; Mrinal Seal; Saibal Ganguly

    2012-01-01

    Replacement of phosphoric acid electrolyte by phosphosilicate gel based electrolytes is proposed for performance enhancement of phosphoric acid fuel cell (PAFG).Phosphosilicate gel in paste form and in powder form is synthesized from tetraethoxysilane and orthophosphoric acid using sol-gel method for two different P/Si ratio of 5 and 1.5 respectively.Replacement of phosphoric acid electrolyte by phosphosilicate gel paste enhances the peak power generation of the fuel cell by 133% at 120 ℃ cell temperature; increases the voltage generation in the ohmic regime and extends the maximum possible load current.Polyinyl alcohol (PVA) is used to bind the phosphosilicate gel powder and to form the hybrid crosslinked gel polymer electrolyte membrane.Soaking the membrane with phosphoric acid solution,instead of that with water improves the proton conductivity of the membrane,enhances the voltage and power generation by the fuel cell and extends the maximum possible operating temperature.At lower operating temperature of 70 ℃,peak power produced by phosphosilicate gel polymer electrolyte membrane fuel cell ( PGMFC ) is increased by 40% compared to that generated by phosphoric acid fuel cell ( PAFC ).However,the performance of composite membrane diminishes as the cell temperature increases.Thus phosphosilicate gel in paste form is found to be a good alternative of phosphoric acid electrolyte at medium operating temperature range while phosphosilicate gel-PVA composite offers performance enhancement at low operating temperatures.

  4. Preparation of Y2O3: Eu3+ phosphor by molten salt assisted method

    Institute of Scientific and Technical Information of China (English)

    HUANG Yan; YE Hong-qi; ZHUANG Wei-dong; HU Yun-sheng; ZHAO Chun-lei; LI Cui; GUO Song-xia

    2007-01-01

    A kind of fine and quasi-spherical Y2O3:Eu3+ phosphor was prepared by firing a preparative precursor at 1 200 ℃ for 2 h with the molten salts of Na2CO3, S and NaCl. The precursor was obtained by homogeneous precipitation of yttrium and europium with oxalic acid when using EDTA, citric acid or starch as complexant. The structure and morphology of the phosphors were characterized by XRD and SEM, respectively. The influence of complexing environment, firing temperature and molten salts on formation of the phosphor Y2O3: Eu3+ was discussed. The result show that the prepared Y2O3:Eu3+ phosphor is of quasi-spherical structure with size of 2-3 μm. Its luminescent intensity is 30% higher than that of the same phosphor prepared by the same procedure but without molten salts, and is 5% higher than that of commercial Y2O3:Eu3+ red phosphor.

  5. Solid state synthesis, characterization and optical properties of Tb doped SrSnO{sub 3} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Kotan, Z. [Ege University, Institute of Nuclear Sciences, 35100 Bornova-İzmir (Turkey); Ayvacikli, M.; Karabulut, Y. [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, 45010 Muradiye-Manisa (Turkey); Garcia-Guinea, J.; Tormo, L. [Museo Nacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Canimoglu, A. [Niğde University, Faculty of Arts and Sciences, Department of Physics, Niğde (Turkey); Karali, T. [Ege University, Institute of Nuclear Sciences, 35100 Bornova-İzmir (Turkey); Can, N., E-mail: cannurdogan@yahoo.com [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, 45010 Muradiye-Manisa (Turkey)

    2013-12-25

    Highlights: •A new stannate phosphor, SrSnO{sub 3}:Tb{sup 3+} was synthesized by solid state reaction method. •The role of Tb{sup 3+} doped into SrSnO{sub 3} was discussed. •A structural phase transition in SrSnO{sub 3}:Tb{sup 3+} at ∼270 K was suggested. -- Abstract: In the present study, the structural and optical properties of SrSnO{sub 3} doped with Tb ions are reported. Novel SrSnO{sub 3}:Tb{sup 3+} phosphors were conventionally synthesized using a solid state reaction process under a mildly reduced atmosphere (5%H{sub 2} and 95%N{sub 2}). The crystal structures, morphologies and optical properties of the resultant materials have been characterised by experimental techniques such as X-ray Diffraction (XRD), Raman spectroscopy (RS), Photoluminescence (PL), Radioluminescence (RL) and Cathodoluminescence coupled to an ESEM (ESEM-CL). The new phosphor material has good crystallization without any impurity phases, which matches with the standard JCPDS files (No. 22-1442) from XRD analysis. The PL, RL and CL measurements taken at room temperature showed that the transitions of {sup 5}D{sub 4} to {sup 7}F{sub J} (j = 6, 5, 4, 3) corresponding to the typical 4f → 4f dipole forbidden intra-configurational transitions of Tb{sup 3+} are largely independent of the host material. The green emissions of the {sup 5}D{sub 4} → {sup 7}F{sub 5} magnetic dipole transition at ∼540 nm are predominant for three types of luminescence. PL emission spectra recorded in the temperature range from 10 K to 300 K were influenced by temperature. We report anomalies in the PL spectra of SrSnO{sub 3}:Tb{sup 3+} compatible with a structural phase transition at 260 K while simultaneously exciting and cooling the sample. This work clearly confirms the existence of a phase transition discovered by Singh et al. in SrSnO{sub 3} at 270 K.

  6. Experimental studies of magmatic differentiation of phosphor enriched

    Science.gov (United States)

    Gorbachev, Pavel; Bezmen, Nikolay

    2014-05-01

    At 800oC and under 200 MPa pressure of the H-O-C fluid system in the moderate reducing conditions (stability of magnetite) in the phosphor enriched Li-F granite melts contained closely connected with natural concentrations of F, P2O5 and H2O the superliquidus nano-cluster cryptic and contrasting layering of Qz-Fsp type is generated. The Sn and W in the experimental samples as well as in the phosphor enriched Li-F granite system of the Podlesi, Czech Republic are concentrated in the melts enriched by F and P2O5.The experiments were carried out in the internally heated gas high pressure vessel. The initial charges were homogeneous glasses obtained by melting of Podlesi Li-F granite system middle composition. The improved Shaw membrane technique is useful to control in experiments the hydrogen content of the fluid phase. The hydrogen fugacity was controlled by an argon-hydrogen mixture in the Re-reactor and was 0.12 MPa. At the interaction of phosphorus and fluorine with Podlesi Li-F granite melt in the presence of H-O-C system fluid in the absence of the thermal gradient and constancy of all other thermodynamic parameters, these develop cryptic layering, a gradual alteration of liquid composition along the sample height and appearance of layers ("lenses") enriched by silica. The origin of heterogeneities is connected to the formation of fluctuating more ordered structures-nano-clusters, which exchange particles and energy with matrix of melt. The depolymerization of melt affects the cluster formation. The degree of silicate melt depolymerization is stipulated by dissolution in the latter of volatiles, specially of hydrogen, phosphorus and fluorine: their presence increases water solubility and depolymerization. The behaviour of clusters cannot be predicted by "classical" chemical principles: various studies on such diverse properties as ionization potentials and nearest neighbour distance has shown that the values for clusters of an element is intermediate between

  7. Characteristics of anoxic phosphors removal in sequence batch reactor

    Institute of Scientific and Technical Information of China (English)

    WANG Ya-yi; PAN Mian-li; Yan Min; PENG Yong-zhen; WANG Shu-ying

    2007-01-01

    The characteristics of anaerobic phosphorus release and anoxic phosphorus uptake was investigated in sequencing batch reactors using denitrifying phosphorus removing bacteria (DPB) sludge. The lab-scale experiments were accomplished under conditions of various nitrite concentrations (5.5, 9.5, and 15 mg/L) and mixed liquor suspended solids (MLSS) (1844, 3231, and 6730 mg/L). The results obtained confirmed that nitrite, MLSS, and pH were key factors, which had a significant impact on anaerobic phosphorus release and anoxic phosphorus uptake in the biological phosphorous removal process. The nitrites were able to successfully act as electron acceptors for phosphorous uptake at a limited concentration between 5.5 and 9.5 mg/L. The denitrification and dephosphorous were inhibited when the nitrite concentration reached 15 mg/L. This observation indicated that the nitrite would not inhibit phosphorus uptake before it exceeded a threshold concentration. It was assumed that an increase of MLSS concentration from 1844 mg/L to 6730 mg/L led to the increase of denitrification and anoxic P-uptake rate. On the contrary, the average P uptake/N denitrifying reduced from 2.10 to 1.57 mg PO43--P/mg NO3--N. Therefore, it could be concluded that increasing MLSS of the DEPHANOX system might shorten the reaction time of phosphorus release and anoxic phosphorus uptake. However, excessive MLSS might reduce the specific denitrifying rate. Meanwhile, a rapid pH increase occurred at the beginning of the anoxic conditions as a result of denitrification and anoxic phosphate uptake. Anaerobic P release rate increased with an increase in pH. Moreover, when pH exceeded a relatively high value of 8.0, the dissolved P concentration decreased in the liquid phase, because of chemical precipitation. This observation suggested that pH should be strictly controlled below 8.0 to avoid chemical precipitation if the biological denitrifying phosphorus removal capability is to be studied accurately.

  8. Studying CaSO4:Eu as an OSL phosphor

    Science.gov (United States)

    Guckan, Veysi; Altunal, Volkan; Nur, Necmettin; Depci, Tolga; Ozdemir, Adnan; Kurt, Kasim; Yu, Yan; Yegingil, Ihami; Yegingil, Zehra

    2017-09-01

    This study was carried out to investigate the properties of the OSL signal from Eu-doped calcium sulfate (CaSO4:Eu) phosphor and study on its thermal behavior as a function of temperature under a series of luminescence experiments. The suitability of its usage as an optically stimulated luminescence (OSL) dosimeter was also checked. CaSO4:Eu was synthesized using the precipitation method and prepared in pellet form. The dopant concentration value was performed as 0.1 mol%. The synthesized CaSO4:Eu was analyzed by X-ray diffraction (XRD) method to confirm the product. To have an idea about the crystallography and microstructure morphology of the material, scanning electron microscope (SEM) analysis were carried out. It was found that the OSL signal is a resultant signal having three components and exhibits thermal quenching above 150 °C. The excitation spectrum of CaSO4:Eu showed different peaks in the region 220-360 nm with the highest one at 269 nm. Thermoluminescence (TL) signals of CaSO4:Eu pellets were obtained and compared with the TL signals obtained after OSL measurements of the same pellets by blue light stimulation. The low temperature peak near 180 °C did not show any significant change in TL after OSL measurement whereas the high temperature peak at 240 °C was bleached with the blue light illumination and might be responsible for the observed OSL signal. The dosimetric properties such as dose response, minimum detectable dose, energy response, reusability, fading properties, thermal stability and effect of reading temperatures on OSL signals were examined. OSL signals of CaSO4:Eu pellets were decreased by approximately 8% at the end of the 24 h and by about 7% at the end of 28 days when compared with the first readout. The thermal stability of the ∼240 °C TL peak and OSL signal using isothermal decay measurements were used to determine the trap parameters. The CaSO4:Eu OSL dosimeter in accordance with the presented study allows a high

  9. Fire severity effects on ash extractable Total Phosphorous

    Science.gov (United States)

    Pereira, Paulo; Úbeda, Xavier; Martin, Deborah

    2010-05-01

    Phosphorous (P) is a crucial element to plant nutrition and limits vegetal production. The amounts of P in soil are lower and great part of this nutrient is absorbed or precipitated. It is well known that fire has important implications on P cycle, that can be lost throughout volatilization, evacuated with the smoke, but also more available to transport after organic matter mineralization imposed by the fire. The release of P depends on ash pH and their chemical and physical characteristics. Fire temperatures impose different severities, according to the specie affected and contact time. Fire severity is often evaluated by ash colour and this is a low-cost and excellent methodology to assess the fire effects on ecosystems. The aim of this work is study the ash properties physical and chemical properties on ash extractable Total Phosphorous (TP), collected in three wildfires, occured in Portugal, (named, (1) Quinta do Conde, (2) Quinta da Areia and (3) Casal do Sapo) composed mainly by Quercus suber and Pinus pinaster trees. The ash colour was assessed using the Munsell color chart. From all three plots we analyzed a total of 102 ash samples and we identified 5 different ash colours, ordered in an increasing order of severity, Very Dark Brown, Black, Dark Grey, Very Dark Grey and Light Grey. In order to observe significant differences between extractable TP and ash colours, we applied an ANOVA One Way test, and considered the differences significant at a p<0.05. The results showed that significant differences in the extractable TP among the different ash colours. Hence, to identify specific differences between each ash colour, we applied a post-hoc Fisher LSD test, significant at a p<0.05. The results obtained showed significant differences between the extractable TP from Very dark Brown and Black ash, produced at lower severities, in relation to Dark Grey, Very Dark Grey and Light Grey ash, generated at higher severities. The means of the first group were higher

  10. Arsenic removal from contaminated soil using phosphoric acid and phosphate

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Laboratory batch experiments were conducted to study Arsenic (As) removal from a naturally contaminated soil using phosphoric acid (H3PO4) and potassium dihydrogen phosphate (KH2PO4). Both H3PO4 and KH2PO4 proved to clearly reduce toxicity of the soil in terms of soil As content, attaining more than 20% As removal at a concentration of 200 mmol/L, although soil As tolerance limit of 30 mg/kg, according to Chinese Environmental quality standard for soil (EQSS), was not satisfied by using these two extractants. At the same time, acidification of soil and dissolution of soil components (Ca, Mg, and Si) resulted from using these two extractants, especially H3PO4. The effectiveness of these two extractants could be attributed to the replacement of As by phosphate ions (PO43-). The function of H3PO4 as an acid to dissolve soil components had little effects on As removal. KH2PO4 almost removed as much As as H3PO4, but it did not result in serious damage to soils, indicating that it was a more promising extractant. The results of a kinetic study showed that As removal reached equilibrium after incubation for 360 min, but dissolution of soil components, especially Mg and Ca, was very rapid. Therefore dissolution of soil components would be inevitable if As was further removed. Elovich's model best described the kinetic data of As removal among the four models used in the kinetic study.

  11. Extracting phosphoric iron under laboratorial conditions smelting bog iron ores

    Science.gov (United States)

    Török, B.; Thiele, A.

    2013-12-01

    In recent years it has been indicated by archaeometric investigations that phosphoric-iron (P-iron, low carbon steel with 0,5-1,5wt% P), which is an unknown and unused kind of steel in the modern industry, was widely used in different parts of the world in medieval times. In this study we try to explore the role of phosphorus in the arhaeometallurgy of iron and answer some questions regarding the smelting bog iron ores with high P-content. XRF analyses were performed on bog iron ores collected in Somogy county. Smelting experiments were carried out on bog iron ores using a laboratory model built on the basis of previously conducted reconstructed smelting experiments in copies of excavated furnaces. The effect of technological parameters on P-content of the resulted iron bloom was studied. OM and SEM-EDS analyses were carried out on the extracted iron and slag samples. On the basis of the material analyses it can be stated that P-iron is usually extracted but the P-content is highly affected by technological parameters. Typical microstructures of P-iron and of slag could also be identified. It could also be established that arsenic usually solved in high content in iron as well.

  12. Bioturbation-induced phosphorous release from an insoluble phosphate source.

    Science.gov (United States)

    Chakrabarty, D; Das, S K

    2007-01-01

    The influence of bioturbation caused by common carp fry in 5 L jars (5 L each) in the laboratory and in 150 L outdoor vats in increasing the fertilizer value of phosphate rock was evaluated. Soluble reactive phosphate (SRP) was determined to quantify the effects of bioturbation, fish excrements and soil. The level of SRP was always lowest in the control series. Introduction of common carp fry resulted in a net increase of 0.09-0.10 mg L(-1) of SRP attributable to the effect of fish excrement. Bioturbation caused by common carp resulted in a 64.8-90% influx of phosphate from bottom soil in the presence of phosphate rock but only about 6.3-7.2% in the absence of phosphate rock. The bioturbation that occurred in these treatments resulted in a significant release of phosphorous into the overlying water from the apatite source. The results confirm the benefits of the application of environmentally friendly phosphate rock in fish farming ponds at low cost.

  13. New developments in X-ray storage phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Schweizer, S. E-mail: schweizer@physik.upb.de; Secu, M.; Spaeth, J.-M.; Hobbs, L.W.; Edgar, A.; Williams, G.V.M

    2004-12-01

    We found a significant PSL effect in Eu{sup 2+}-doped fluorozirconate glasses (ZBLAN) which were additionally doped with Br{sup -} or Cl{sup -} ions. The PSL is attributed to the characteristic emission of Eu{sup 2+} present in nano-crystallites of BaBr{sub 2} or BaCl{sub 2}, which form in the glass upon annealing. The metastable hexagonal form of BaX{sub 2} (X=Br,Cl) is always formed first before it is converted into the stable orthorhombic form. The particle size increases upon annealing and so does the PSL efficiency of the glass ceramic. However, there is a saturation of the PSL efficiency, which is for Br{sup -} doping about 9% and for Cl{sup -}-doping about 80% of the Eu-doped BaFBr standard. The particle size was determined by transmission electron microscopy (TEM). The TEM results show a clear tendency for bigger particles for longer annealing at the expense of its number. The particle size for the most efficient phosphor is about 100 nm.

  14. Phosphorous Nutritional Level, Carbohydrate Reserves and Flower Quality in Olives

    Science.gov (United States)

    Erel, Ran; Yermiyahu, Uri; Yasuor, Hagai; Cohen Chamus, Dan; Schwartz, Amnon; Ben-Gal, Alon; Dag, Arnon

    2016-01-01

    The olive tree is generally characterized by relatively low final fruit set consequential to a significant rate of undeveloped pistils, pistil abortion, and flower and fruitlet abscission. These processes are acknowledged to be governed by competition for resources between the developing vegetative and reproductive organs. To study the role of phosphorus (P) nutritional level on reproductive development, trees were grown under four levels of P for three years in large containers. Phosphorus nutritional level was positively related to rate of reproductive bud break, inflorescence weight, rate of hermaphrodite flowers, pistil weight, fruitlet persistence, fruit set and the consequential total number of fruits. The positive impact of P nutrition on the productivity parameters was not related to carbohydrate reserves or to carbohydrate transport to the developing inflorescence. Phosphorous deficient trees showed significant impairment of assimilation rate, and yet, carbohydrates were accumulated in inflorescences at levels comparable to or higher than trees receiving high P. In contrast to female reproductive organs, pollen viability was consistently higher in P deficient trees, possibly due to the enhanced carbohydrate availability. Overall, the positive effect of P on female reproductive development was found to be independent of the total carbohydrate availability. Hence, P is speculated to have a direct influence on reproductive processes. PMID:27907133

  15. Complex Leaching Process of Scheelite in Hydrochloric and Phosphoric Solutions

    Science.gov (United States)

    Liu, Liang; Xue, Jilai; Liu, Kang; Zhu, Jun; Wang, Zengjie

    2016-09-01

    The complex leaching process of synthetic scheelite and scheelite concentrate in hydrochloric and phosphoric solutions has been investigated for improving process efficiency. A higher leaching rate, compared with the classic acid leaching process, can be obtained through the synergy of HCl and H3PO4 with appropriate W/P mole ratio, temperature, and acid concentration. For synthetic scheelite, the optimum leaching conditions were W/P mole ratio 7:1, temperature 50°C, HCl 0.72 mol/L, and stirring speed 600 rpm; for scheelite concentrate, W/P mole ratio 7:1, temperature 80°C, HCl 2.16 mol/L, and stirring speed 1000 rpm. The leaching rates under the optimized conditions can reach up to 98% or even higher. FTIR spectra analysis confirmed that the leachate composition remained as H3[PW12O40] in the range of varying W/P mole ratios, so the PO4 3- in acidic solution and phosphorus content in the leaching product could be better controlled. The function 1 - (1 - X)1/3 against leaching time was applied to fit the experimental data, and the apparent activation energy, E a, was calculated as 60.65 kJ/mol. The results would be valuable for effectively using scheelite as a raw material resource for sustainable tungsten production.

  16. Dry compliant seal for phosphoric acid fuel cell

    Science.gov (United States)

    Granata, Jr., Samuel J. (Inventor); Woodle, Boyd M. (Inventor)

    1990-01-01

    A dry compliant overlapping seal for a phosphoric acid fuel cell preformed f non-compliant Teflon to make an anode seal frame that encircles an anode assembly, a cathode seal frame that encircles a cathode assembly and a compliant seal frame made of expanded Teflon, generally encircling a matrix assembly. Each frame has a thickness selected to accommodate various tolerances of the fuel cell elements and are either bonded to one of the other frames or to a bipolar or end plate. One of the non-compliant frames is wider than the other frames forming an overlap of the matrix over the wider seal frame, which cooperates with electrolyte permeating the matrix to form a wet seal within the fuel cell that prevents process gases from intermixing at the periphery of the fuel cell and a dry seal surrounding the cell to keep electrolyte from the periphery thereof. The frames may be made in one piece, in L-shaped portions or in strips and have an outer perimeter which registers with the outer perimeter of bipolar or end plates to form surfaces upon which flanges of pan shaped, gas manifolds can be sealed.

  17. Synthesis and luminescence properties of Ca5(PO43Cl:Eu2+ phosphor for solid state lighting

    Directory of Open Access Journals (Sweden)

    Deorao N. Game

    2016-03-01

    Full Text Available A novel method to prepare Eu2+ doped chlorapatite phosphor Ca5(PO43Cl useful for solid state lighting has been given in this paper. The phosphor was synthesized by the Pechini (citrate gel method which turned out to be more efficient than the conventional high temperature solid state reaction. The results of the photoluminescence (PL investigation revealed that it was possible to efficiently excite the phosphor by a UV–visible light from 220 to 430nm; the phosphor exhibited a bright blue emission at the wavelength λem=456nm for the excitation wavelength λex=350nm of near-ultraviolet light. The developed phosphor emits in blue and, hence, could provide one of the three (RGB primary color components in a phosphor-converted LED-producing white light.

  18. Monolithic translucent BaMgAl10O17:Eu2+ phosphors for laser-driven solid state lighting

    OpenAIRE

    Clayton Cozzan; Brady, Michael J.; Nicholas O’Dea; Emily E. Levin; Shuji Nakamura; Steven P. DenBaars; Ram Seshadri

    2016-01-01

    With high power light emitting diodes and laser diodes being explored for white light generation and visible light communication, thermally robust encapsulation schemes for color-converting inorganic phosphors are essential. In the current work, the canonical blue-emitting phosphor, high purity Eu-doped BaMgAl10O17, has been prepared using microwave-assisted heating (25 min) and densified into translucent ceramic phosphor monoliths using spark plasma sintering (30 min). The resulting transluc...

  19. Chiral Phosphoric Acid Catalyzed Enantioselective Allylation of Aldehydes with Allyltrichlorosilane%Chiral Phosphoric Acid Catalyzed Enantioselective Allylation of Aldehydes with Allyltrichlorosilane

    Institute of Scientific and Technical Information of China (English)

    程柯; 范甜甜; 孙健

    2011-01-01

    Easily accessible chiral phosphoric acid lb has been applied as efficient organocatalyst for the asymmetric al- lylation of aldehydes with allyltrichlorosilane. In the presence of 20 mol% of lb, the allylation of a broad range of aldehydes proceeded smoothly to give the corresponding homoallylic alcohol with up to 87% ee and 97% yield.

  20. Synthesis and luminescence properties of Tb$^{3+}-doped LiMgPO$_4$ phosphor

    Indian Academy of Sciences (India)

    C B PALAN; N S BAJAJ; A SONI; S K OMANWAR

    2016-09-01

    Polycrystalline sample LiMg$_{(1.x)}$PO$_4$:$x$Tb$^{3+}$ ($x = 0.001, 0.002, 0.005, 0.01, 0.02$) phosphor was synthesized via modified solid state method (MSSM). The prepared sample was characterized through XRD pattern (X-ray diffraction) and SEM (scanning electron microscope). Additionally, photoluminescence (PL), optically stimulated luminescence (OSL), thermoluminescence (TL) and other dosimetric properties including dose linearity, reusability and fading were studied. In OSL mode, sensitivity of prepared phosphor was found to be 2.7 times that of LiMgPO$_4$:Tb$^{3+}, B (BARC) phosphor and 4.3 times that of $\\alpha$-Al$_2$O$_3$:C (BARC) phosphor. The TL glow consists of overlapping peaks in temperature range of 50-400$^{\\circ}$C and first peak (P$_1$) was observed at 150$^{\\circ}$C, second peak (P$_2$) at 238$^{\\circ}$C, third peak (P$_3$) at 291$^{\\circ}$C and fourth peak (P$_4$) at 356$^{\\circ}$C. The TL sensitivity of second peak (P$_2$) of LiMgPO$_4$:Tb$^{3+}$ phosphor was compared with $\\alpha$-Al$_2$O$_3$:C (BARC) phosphor and found to be 100 times that of the $\\alpha$-Al$_2$O$_3$:C (BARC) phosphor. The minimum detectable dose (MDD) was found to be 5.6 $\\mu$Gy. Moreover, photoionization cross-sections, linearity, reusability, fading and kinetic parameters were calculated. Also, photoluminescence spectra of LiMgPO$_4$:Tb$^{3+}$ shows characteristic green.yellow emission exciting at 224nm UV source.

  1. Blue emitting KSCN:xCe phosphor for solid state lighting

    Energy Technology Data Exchange (ETDEWEB)

    Chikte, Devayani, E-mail: devi.awade@gmail.com [G.N. Khalsa College, Matunga, Mumbai 400019 (India); Omanwar, S.K. [Department of Physics, S.G.B. Amravati University, Amravati (India); Moharil, S.V. [Department of Physics, R.T.M. Nagpur University, Nagpur 440010 (India)

    2014-01-15

    The intense blue emitting phosphor KSCN:xCe (x=0.005, 0.01, 0.02, 0.04) is synthesized by a simple, time saving, economical method of re-crystallization through aqueous solution at 353 K. Photoluminescence measurements showed that the said phosphor exhibits emission with good intensity peaking at 450 nm corresponding to d→f transitions of Ce{sup 3+} ion. The excitation spectra monitored at 450 nm shows small peak at 282 nm and broad intense excitation band peaking at 350 nm. The latter lies in near ultraviolet (350–410 nm) emission of UV LED. The phosphor KSCN:0.02Ce{sup 3+} shows CIE 1931 color coordinates as (0.1484, 0.0602) whereas the commercial blue phosphor BAM:Eu{sup 2+} shows the color co-ordinates as (0.1417, 0.1072), respectively, indicating better color purity for KSCN: 0.02Ce{sup 3+} compared to the BAM:Eu{sup 2+} phosphor. The color coordinates of KSCN: 0.02Ce{sup 3+} phosphor (0.1484, 0.0602) are nearer to the color coordinate for blue color suggested by the color systems EBUPAL/SECAM, sRGB Blue as well as Adobe blue(0.15, 0.06). -- Highlights: • Novel phosphor KSCN:xCe prepared for the first time. • Method is simple, time saving, economical, easy to handle. • Intense, blue, Characteristic Ce{sup 3+} emission at 450 nm. • nUV excitation, suitable for solid state lighting.

  2. Analysis of wide color gamut of green/red bilayered freestanding phosphor film-capped white LEDs for LCD backlight.

    Science.gov (United States)

    Oh, Ji Hye; Kang, Heejoon; Ko, Minji; Do, Young Rag

    2015-07-27

    In this study, we propose green/red bilayered freestanding phosphor film-capped white light-emitting diodes (W-LEDs) using InGaN blue LEDs and narrowband red and green phosphors to realize a wide color gamut in a liquid crystal display (LCD) backlight system. The narrowband K2SiF6:Mn4+ (KSF) red and SrGa2S4:Eu2+ (SGS) green phosphors are synthesized using a facile etching synthetic process and flux-aided solid state reaction under a H2S atmosphere, respectively, and the freestanding phosphor films are fabricated using a delamination method with water-soluble polymer, polystyrene sulfonic acid, PEDOT/PSS, and interlayered phosphor film. Various phosphor concentrations of green/red bilayered freestanding phosphor film-capped W-LEDs exhibit a correlated color temperature (CCT) and luminous efficacy range of 11,390 K ~6,540 K and 99 lm/W ~124 lm/W, respectively, with an applied current of 60 mA. The W-LED with green (12.5 wt%)/red (40 wt%) bilayered phosphor film, which exhibited luminous efficacy of 105 lm/W at the CCT of 8,330 K, is selected and the color gamut of the bare LED and phosphor RG and the filtered RGB triangle is calculated to be more than ~95% and ~86.4%, respectively, relative to the NTSC in the 1931 CIE color coordinates space.

  3. Enhancement of Color Rendering Index for White Light LED Lamps by Red Y2O3:EU3+ Phosphor

    Directory of Open Access Journals (Sweden)

    Tran Hoang Quang Minh

    2016-01-01

    Full Text Available We present an application of the red Y2O3:Eu3+ dopant phosphor compound for reaching the color rendering index as high as 86. The Multi-Chip White LED lamps (MCW-LEDs with high Correlated Color Temperatures (CCTs including 7000 K and 8500 K are employed in this study. Besides, the impacts of the Y2O3:Eu3+ phosphor on the attenuation of light through phosphor layers of the various packages is also demonstrated based on the Beer-Lambert law. Simulation results provide important conclusion for selecting and developing the phosphor materials in MCW-LEDs manufacturing.

  4. Rare Earth Free Zn3V2O8 Phosphor with Controlled Microstructure and Its Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Hom Nath Luitel

    2013-01-01

    Full Text Available Microsphere of rare earth free phosphor, Zn3V2O8, with broadband yellowish white emission was synthesized by combustion route and compared with the hydrothermal, sol-gel, and solid state reaction methods. The phosphor samples were characterized by X-ray diffraction and scanning electron microscopy. UV-visible absorption and photoluminescence (PL emission and excitation spectra were investigated for these phosphors. Zn3V2O8 phosphor containing 10 mol% of H3BO3 flux exhibited enhanced PL emission showing broadband from 450 nm to 750 nm. Effect of stoichiometry of Zn and V on the host lattice and its effect on the PL emission spectra were studied. Series of Mg3V2O8, Ca3V2O8, and Sr3V2O8 phosphors were also synthesized and compared to the Zn3V2O8 phosphor in terms of PL emission and internal quantum yield, and it was found that Zn3V2O8 is the most efficient phosphor among the other phosphors studied with quantum yield of 60%. The visible light irradiated photocatalytic activity of these phosphors was investigated and it was found that the hydrothermal Zn3V2O8 exhibited enhanced activity.

  5. Comparison of Phosphorous Absorption, Quality and Yield Between High Oil Corn and Common Corn as Influenced by Phosphorous Application

    Institute of Scientific and Technical Information of China (English)

    HE Ping; JIN Ji-yun; LI Wen-juan; LIU Hai-long; HUANG Shao-wen; WANG Xiu-fang; WANG Li-chun; XIE Jia-gui

    2005-01-01

    A field trial was carried out to investigate phosphorous (P) absorption, grain quality and yield between high oil corn and common corn. The results indicated that high oil corn var. Tongyou 1 obtained lower highest P absorption rate (HAR) and later occurring date of HAR, in comparison with common corn var. Simi 25. The highest HAR and the earliest occurring date of HAR was obtained by the treatments of P45 and P75 in Tongyou 1 and Simi 25 separately; while the total amount of P accumulated by maize plant was achieved by P105 treatment in both varieties. P in grain relied mainly on root uptake at maturation that accounted for 85.7-96.8% and 79.3-84.3% for Tongyou 1 and Simi 25, respectively. Tongyou 1 contained more oil and protein contents, but less starch content with lower grain yield. P application at appropriate rate enhanced contents of protein and fatty acid, but the increment of starch content was neglectable.

  6. Nonadiabatic Coupling

    Science.gov (United States)

    Kryachko, Eugene S.

    The general features of the nonadiabatic coupling and its relation to molecular properties are surveyed. Some consequences of the [`]equation of motion', formally expressing a [`]smoothness' of a given molecular property within the diabatic basis, are demonstrated. A particular emphasis is made on the relation between a [`]smoothness' of the electronic dipole moment and the generalized Mulliken-Hush formula for the diabatic electronic coupling.

  7. External radiation assessment in a wet phosphoric acid production plant

    Energy Technology Data Exchange (ETDEWEB)

    Bolivar, J.P.; Perez-Moreno, J.P. [Dept. Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, 21012 Huelva (Spain); Mas, J.L. [Dept. Fisica Aplicada I, Escuela Universitaria Politecnica, Universidad de Sevilla, 41012 Sevilla (Spain)], E-mail: ppmasb@us.es; Martin, J.E.; San Miguel, E.G. [Dept. Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, 21012 Huelva (Spain); Garcia-Tenorio, R. [Dept. Fisica Aplicada II, Escuela Tecnica Superior de Arquitectura, Universidad de Sevilla, 41012 Sevilla (Spain)

    2009-10-15

    The factories dedicated to the production of phosphoric acid by the so-called wet acid method are usually considered typical NORM industries, because the phosphate rock used as raw material usually contains high concentrations of {sup 238}U-series radionuclides. The magnitude and behaviour of the radionuclides involved in the production process revealed the need to determine its dosimetric impact on workers. This work aims to partially compensate this lack of knowledge through the determination of external effective dose rates at different zones in the process at a typical plant located in the southwest of Spain. To this end, two dosimetric sampling campaigns have been carried out at this phosphoric acid production plant. The first sampling was carried out when phosphate rocks originating in Morocco were processed, and the second one when phosphate rock processed came from the Kola Peninsula (Russia Federation). This differentiation was necessary because the activity concentrations are almost one order of magnitude higher in Moroccan phosphate rock than in Kola phosphate rock. The results obtained have reflected external dose rate enhancements as high as 1.4 {mu}Sv h{sup -1} (i.e., up to thirty times the external exposition due to radionuclides in unperturbed soils) at several points in the facility, particularly where the digested rock (pulp) is filtered. However, the most problematic points are characterised by a small occupation factor. That means that the increment in the annual effective external gamma dose received by the most-exposed worker is clearly below 1 mSv (European Commission limit for the general population) under normal production. Nevertheless, special care in the design and schedule of cleaning and maintaining work in the areas with high doses should be taken in order to avoid any possibility of exceeding the previously mentioned general population limit. In addition, the results of the dosimetric campaign showed no clear correlation between {sup

  8. Understanding Phosphorous Chemistry in Comets in Light of Rosetta Results

    Science.gov (United States)

    Boice, Daniel C.; de Almeida, Amaury A.

    2016-10-01

    Introduction: Phosphorous is a key element in all known forms of life. P-bearing compounds have been observed in the ISM and other regions of space. They are ubiquitous in meteorites, have been detected in the dust component in comets 1P/Halley and 81P/Wild 2, and in the gas phase (atomic P) of 67P/Churyumov-Gerasimenko by the Rosetta Mission. We present results from the first quantitative study of P-bearing molecules in comets to aid in future searches for this important element in comets, shedding light on issues of comet formation and prebiotic to biotic evolution of life. Results and Discussion: Our gas dynamics model of cometary comae with chemical kinetics has been adapted to study this problem. We used phosphine (PH3) as a native molecule with a cosmic abundance mixing ratio. Over 100 photo and gas-phase reactions and 30 P-bearing species were added to the chemical network. The chemistry of PH3 in the inner coma shows the major destruction channels are photo-dissociation and protonation with water-group ions, leading to the recycling of PH3 in this region and the eventual production of atomic P. Conclusion: The model identifies the relevant phosphine chemistry in cometary coma. Protonation reactions of PH3 with water-group ions are important due to its high proton affinity. Abundances are found to be on the order of 10-4 relative to water, about the same as isotopic species. The scale length of PH3 in the coma is about 13,000-16,000 km. We also comment on other Rosetta findings (e.g., O2 and H-). Collaborations with observers using modern telescopic facilities (e.g., Keck 2 and Subaru) are underway to search for phosphorus in comets. Acknowledgments: This work was supported by FAPESP under Grant No. 2015/03176-8 and the National Science Foundation Planetary Astronomy Program Grant No. 0908529.

  9. Antimicrobial and cytotoxic effects of phosphoric acid solution compared to other root canal irrigants

    Directory of Open Access Journals (Sweden)

    Maíra PRADO

    2015-04-01

    Full Text Available Phosphoric acid has been suggested as an irrigant due to its effectiveness in removing the smear layer. Objectives : The purpose of this study was to compare the antimicrobial and cytotoxic effects of a 37% phosphoric acid solution to other irrigants commonly used in endodontics. Material and Methods : The substances 37% phosphoric acid, 17% EDTA, 10% citric acid, 2% chlorhexidine (solution and gel, and 5.25% NaOCl were evaluated. The antimicrobial activity was tested against Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Actinomyces meyeri, Parvimonas micra, Porphyromonas gingivalis, and Prevotella nigrescens according to the agar diffusion method. The cytotoxicity of the irrigants was determined by using the MTT assay. Results : Phosphoric acid presented higher antimicrobial activity compared to the other tested irrigants. With regard to the cell viability, this solution showed results similar to those with 5.25% NaOCl and 2% chlorhexidine (gel and solution, whereas 17% EDTA and 10% citric acid showed higher cell viability compared to other irrigants. Conclusion : Phosphoric acid demonstrated higher antimicrobial activity and cytotoxicity similar to that of 5.25% NaOCl and 2% chlorhexidine (gel and solution.

  10. Effect of phosphor addition on eutectic solidification and microstructure of an Al-13%Si alloy

    Directory of Open Access Journals (Sweden)

    Liao Hengcheng

    2011-11-01

    Full Text Available As the refiner or modifier, the master alloys containing high concentration phosphor are widely used in preparing eutectic or hypereutectic Al-Si alloys. To study the effect of phosphor addition on the eutectic solidification and microstructure of the Al-13%Si alloy, an investigation has been undertaken by means of thermal analysis and micro/macro-structure observation. Results indicate that addition of phosphor in near eutectic Al-Si alloy promotes the nucleation of eutectic but has little refinement impact on primary Si particles as expected. Conversely, both primary Si particles and eutectic Si flakes become slightly coarser in P-rich alloys. The coarsening of eutectic Si flakes ties closely to the increased eutectic growth temperature with phosphor addition. The eutectic solidification of the alloy proceeds from the near mold zone towards the center, and it is also found that a few independent nucleation regions emerge in liquid at the solidification front due to the addition of phosphor.

  11. Investigation of the effect of beta source and phosphors on photovoltaic cells

    Science.gov (United States)

    Yürük, Reyyan Kavak; Tütüncüler, Hayriye

    2017-02-01

    In this study, conversion of kinetic energy from the decay of a radioactive isotope to electricity is investigated by using the direct and the indirect conversion methods. In this context, simple nuclear battery models are designed. Analysis for the effect of low-activity radiation from Pm147 and Sr90 beta sources on photovoltaic Si solar cell is presented. Beta radioluminescence nuclear battery models consist of a beta source, a phosphor layer and a solar cell. Phosphor layers with different mass thicknesses are prepared from ZnS:CuCl and SrAl2O4:Eu2+,Dy3+ phosphors. Both the influence of beta sources and the phosphor layers on battery performance is analyzed separately. Effect of beta sources, phosphors are observed on solar cell by measuring the short circuit current and open circuit voltage. The efficiency of the battery models is determined with the obtained results. Furthermore, short circuit current values are analyzed at various times during the irradiation.

  12. Combustion synthesis and luminescence properties of blue NaBaPO4:Eu2+ phosphor

    Institute of Scientific and Technical Information of China (English)

    SUN Jiayue; ZHANG Xiangyan; DU Haiyan

    2012-01-01

    The blue-emitting phosphor NaBaPO4:Eu2+ was prepared by the combustion method.The phase structure and microstructure of the as-prepared samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM),respectively.Under the excitation wavelength of 360 nm,the emission spectrum exhibited only one blue band centering at 435 nm,which was ascribed to the 4f65d1→4f7transition on Eu2+ ions.Compared with the phosphor obtained by solid-state reaction method,the relative emission intensity of sample obtained by combustion method increased slightly.The decay times and the temperature dependence luminescence intensities (25-300 ℃) were discussed in order to further investigate the potential applications.Furthermore,Eu2+-doped NaBaPO4 phosphor showed higher thermally stable luminescence comparable to commercially available Y3Al5O12:Ce3+ (Y AG:Ce3+) phosphor.All the investigated suggestions that Na-BaPO4:Eu2+ is a good phosphor candidate applied in white light emitting diode.

  13. Antimicrobial and cytotoxic effects of phosphoric acid solution compared to other root canal irrigants.

    Science.gov (United States)

    Prado, Maíra; Silva, Emmanuel João Nogueira Leal da; Duque, Thais Mageste; Zaia, Alexandre Augusto; Ferraz, Caio Cezar Randi; Almeida, José Flávio Affonso de; Gomes, Brenda Paula Figueiredo de Almeida

    2015-01-01

    Phosphoric acid has been suggested as an irrigant due to its effectiveness in removing the smear layer. The purpose of this study was to compare the antimicrobial and cytotoxic effects of a 37% phosphoric acid solution to other irrigants commonly used in endodontics. The substances 37% phosphoric acid, 17% EDTA, 10% citric acid, 2% chlorhexidine (solution and gel), and 5.25% NaOCl were evaluated. The antimicrobial activity was tested against Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Actinomyces meyeri, Parvimonas micra, Porphyromonas gingivalis, and Prevotella nigrescens according to the agar diffusion method. The cytotoxicity of the irrigants was determined by using the MTT assay. Phosphoric acid presented higher antimicrobial activity compared to the other tested irrigants. With regard to the cell viability, this solution showed results similar to those with 5.25% NaOCl and 2% chlorhexidine (gel and solution), whereas 17% EDTA and 10% citric acid showed higher cell viability compared to other irrigants. Phosphoric acid demonstrated higher antimicrobial activity and cytotoxicity similar to that of 5.25% NaOCl and 2% chlorhexidine (gel and solution).

  14. Rare earth elements recycling from waste phosphor by dual hydrochloric acid dissolution.

    Science.gov (United States)

    Liu, Hu; Zhang, Shengen; Pan, Dean; Tian, Jianjun; Yang, Min; Wu, Maolin; Volinsky, Alex A

    2014-05-15

    This paper is a comparative study of recycling rare earth elements from waste phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red rare earth phosphor (Y0.95Eu0.05)2O3 in waste phosphor is dissolved during the first step of acid leaching, while the Green phosphor (Ce0.67Tb0.33MgAl11O19) and the Blue phosphor (Ba0.9Eu0.1MgAl10O17) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO2 are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the rare earth elements was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications.

  15. Visible upconversion in Er3+/Yb3+ co-doped LaAlO3 phosphors

    Science.gov (United States)

    Singh, Vijay; Rai, V. K.; Singh, N.; Pathak, M. S.; Rathaiah, M.; Venkatramu, V.; Patel, Rahul V.; Singh, Pramod K.; Dhoble, S. J.

    2017-01-01

    The Er3+ doped and Er3+/Yb3+ co-doped LaAlO3 phosphors have been synthesized by the combustion method and characterized their structural, morphological, elemental, vibrational and optical properties. The optical absorption and upconversion properties of the synthesized phosphors have been studied. Upon co-doping Yb3+ ions into Er3+:LaAlO3, the blue, green and red upconversion emissions of Er3+ ions have been enhanced about 20, 54 and 22 times, under 978 nm laser excitation. The observed upconversion emissions could be due to excited state absorption in Er3+:LaAlO3, whereas energy transfer is dominant mechanism in Er3+/Yb3+:LaAlO3 phosphors. The tuning in the color emitted from the synthesized phosphors towards the green region has been found due to incorporation of the Yb3+ ions. With increase in the pump power, the color emitted from the co-doped phosphor is not tuned significantly, showing its applicability in making the green display devices.

  16. Modification of ZnS∶Mn Phosphors by Sb-Doped SnO2 Coating

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The coating of ZnS∶Mn by Sb-doped SnO2 using an co-precipitation process was reported. ZnS∶Mn phosphor particles were prepared by solid reaction with ZnS and MnCl2·4H2O. Surface modification of the ZnS∶Mn powders was carried out by coating transparent conductive films of Sb-doped tin oxides which were formed by co-precipitation and heat treatment process. Tin tetrachloride and antimony trichloride were used as the precursor materials for the co-precipitation. The influences of coating molar ratio, Sb concentration in the coatings, annealing temperature and time on the resistivity of coated ZnS∶Mn phosphors were investigated. The optimum co-precipitation processing parameters and annealing conditions were determined. The phosphors were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence(PL) observation and conductance measurements. An improvement in phosphors conductivity was observed while the respective photoluminescence intensity is analogous to the as-prepared ZnS∶Mn phosphors.

  17. Near-Infrared Quantum Cutting in Yb3+ Doped SrMoO4 Phosphors.

    Science.gov (United States)

    Luo, Xiaobing; Shen, Jun; Huang, He; Xu, Lu; Wang, Zhixiang; Chen, Yang; Li, Li

    2016-04-01

    Efficient near-infrared (NIR) quantum cutting (QC) has been demonstrated in Yb3+ doped SrMoO4 phosphors synthesized by the high-temperature solid-state reaction method. The obtained SrMoO4:Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra and decay lifetime to understand the observed near-infrared quantum cutting phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of SrMoO4 and exhibit good crystallinity. The experimental results showed that the strong visible molybdate (MoO2-(4)) emission around 493 nm and near-infrared (NIR) emission around 1000 nm from Yb3+(2F(5/2)-->2F(7/2)) of SrMoO4:Yb3+ phosphors were observed under ultraviolet (290 nm) excitation. The Yb + concentration dependence of luminescent properties and lifetimes of both the visible and NIR emissions have also been investigated. The quenching concentration of Yb3+ ions approaches as high as 10 mol%. The cooperative energy transfer (CET) mechanism was also discussed in detail. The broadband NIR QC phosphors may possibly have potential application in enhancing the conversion efficiency of solar cells.

  18. Preliminary study on preparation of BCNO phosphor particles using citric acid as carbon source

    Energy Technology Data Exchange (ETDEWEB)

    Nuryadin, Bebeh W.; Pratiwi, Tripuspita; Faryuni, Irfana D.; Iskandar, Ferry, E-mail: ferry@fi.itb.ac.id; Abdullah, Mikrajuddin; Khairurrijal [Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Ganesha 10 Bandung, Indonesia 40132 (Indonesia); Ogi, Takashi; Okuyama, Kikuo [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, Japan 739-8527 (Japan)

    2015-04-16

    A citric acid was used as a carbon source in the preparation of boron carbon oxy-nitride (BCNO) phosphor particles by a facile process. The preparation process was conducted at relatively low temperature 750 °C and at ambient pressure. The prepared BCNO phosphors showed a high photoluminescence (PL) performance at peak emission wavelength of 470 nm under excitation by a UV light 365 nm. The effects of carbon/boron and nitrogen/boron molar ratios on the PL properties were also investigated. The result showed that the emission spectra with a wavelength peak ranging from 444 nm to 496 nm can be obtained by varying carbon/boron ratios from 0.1 to 0.9. In addition, the observations showed that the BCNO phosphor material has two excitation peaks located at the 365 nm (UV) and 420 nm (blue). Based on these observations, we believe that the citric acid derived BCNO phosphor particles can be a promising inexpensive material for phosphor conversion-based white LED.

  19. Production of monosaccharides from napier grass by hydrothermal process with phosphoric acid.

    Science.gov (United States)

    Takata, Eri; Tsutsumi, Ken; Tsutsumi, Yuji; Tabata, Kenji

    2013-09-01

    The production of monosaccharides from napier grass was investigated in the presence of acid catalysts using the hydrothermal process. When the napier grass was treated with 3 wt.% phosphoric acid at 160°C for 15min, the xylose yield reached 10.3 wt.%, corresponding to 72.0% of the xylan in it, whereas glucose was hardly obtained. A combined process was then conducted using an 85 wt.% phosphoric acid treatment at 60 °C for 1h followed by a hydrothermal treatment with 3 wt.% phosphoric acid. In the initial treatment with concentrated phosphoric acid the most of xylan was hydrolyzed to xylose, and the crystalline cellulose was converted to its amorphous form. The hydrolysis of cellulose to glucose was significantly enhanced during the following hydrothermal process with 3 wt.% phosphoric acid at 200 °C for 8 min. Consequently, 77.2% yield of xylose and 50.0% yield of glucose were obtained from the combined process.

  20. Citrate sol-gel combustion preparation and photoluminescence properties of YAG:Ce phosphors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Le; LU Zhou; ZHU Jinzhen; YANG Hao; HAN Pengde; CHEN Yan; ZHANG Qitu

    2012-01-01

    Yellow-emitting YAG:Ce3+ nanocrystalline phosphors were prepared by citrate sol-gel combustion method using citric acid as the fuel and chelating agent.The influence of mole ratio of citric acid to metallic ions (MRCM),pH value of the solution,calcination temperature and Ce-doped concentration on the structures and properties of as-prepared powders were investigated in detail.Higher crystallinity and better luminescence performance powders were obtained at MRCM=2,pH=3 and the calcination temperature of 1200 ℃.The phosphors exhibited the characteristic broadband visible luminescence of YAG:Ce.The optimum concentration of Ce3+ was 1.0 mol.%,and the concentration quenching was derived from the reciprocity between electric dipole and electric quadrupole (d-q).Especially,the pH value of the solution was a key factor to obtain a stable sol-gel system and then obtain pure and homogeneous rare earth ions doped YAG phosphors at a lower temperature.The Y3Al5O12:Ce0.03 phosphor with optimized synthesis-condition and composition had a similar luminescence intensity with the commercial phosphor YAG:Ce.

  1. Phosphorous Diffuser Diverged Blue Laser Diode for Indoor Lighting and Communication

    KAUST Repository

    Chi, Yu-Chieh

    2015-12-21

    An advanced light-fidelity (Li-Fi) system based on the blue Gallium nitride (GaN) laser diode (LD) with a compact white-light phosphorous diffuser is demonstrated for fusing the indoor white-lighting and visible light communication (VLC). The phosphorous diffuser adhered blue GaN LD broadens luminescent spectrum and diverges beam spot to provide ample functionality including the completeness of Li-Fi feature and the quality of white-lighting. The phosphorous diffuser diverged white-light spot covers a radiant angle up to 120o with CIE coordinates of (0.34, 0.37). On the other hand, the degradation on throughput frequency response of the blue LD is mainly attributed to the self-feedback caused by the reflection from the phosphor-air interface. It represents the current state-of-the-art performance on carrying 5.2-Gbit/s orthogonal frequency-division multiplexed 16-quadrature-amplitude modulation (16-QAM OFDM) data with a bit error rate (BER) of 3.1 × 10−3 over a 60-cm free-space link. This work aims to explore the plausibility of the phosphorous diffuser diverged blue GaN LD for future hybrid white-lighting and VLC systems.

  2. Preparation of CaS:Eu2+ Phosphor by Microwave Heating Method and its Luminescence

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This is the first report of using the microwave heating technique to synthesize calcium sulphide activated by europium whose structure is determined as the face-centered cubic by conventional X-ray powder diffraction method.The phosphor has maximum excitation peaks located at 280 nm and 560 nm and the maximum emission of the phosphor is 630 nm.When the concentration of Eu2+ in CaS increases from 1.0×10-5 to 1.0×10-2 mole per mole host,the body colour of the calcium sulphide activated with europium changes from white,through light-red to pink to deep-red.The phosphor obtains the longest afterglow at the concentration of 0.1% Eu2+-doped and is a kind of good material excited by sunlight.

  3. Key parameters of efficient phosphor-filled luminescent down-shifting layers for photovoltaics

    Science.gov (United States)

    Solodovnyk, Anastasiia; Lipovšek, Benjamin; Riedel, Daniel; Forberich, Karen; Stern, Edda; Batentschuk, Miroslaw; Krč, Janez; Topič, Marko; Brabec, Christoph J.

    2017-09-01

    Spectral management is one of the promising ways to increase the efficiency of modern photovoltaic devices. We study the performance of phosphor-filled luminescent down-shifting (LDS) layers. We focus on four powder phosphors with refractive indices in the range of 1.66-1.84 and similar particle size distributions. Using experimental characterization as well as 3D optical simulations, we identify key parameters of the phosphor particles and LDS layers that primarily affect the optical transmittance, absorptance, and photoluminescence quantum yield of the layers. We investigate the influence of the medium located beneath the LDS layer and reveal a strong increase in the performance when the layer is applied directly onto the solar cell. Finally, the optimal combination of the particle, binder and layer parameters that render the highest performance of the LDS layers are also indicated and discussed.

  4. Synthesis, structural and optical properties of SrZrO3:Eu3+phosphor

    Institute of Scientific and Technical Information of China (English)

    Sheetal; V.B.Taxak; Rajni Arora; Dayawati; S.P.Khatkar

    2014-01-01

    Eu3+activated Sr1-xEuxZrO3 (x=0.01-0.04) phosphor with perovskite structure was successfully synthesized by using com-bustion method. The structure, morphology and optical properties of the material were characterized by X-ray diffraction, scanning electron microscopy and fluorescence spectrometry. The XRD results indicated that crystals of SrZrO3:Eu3+belongs to tetragonal perovskite system. The phosphor could be effectively excited by UV light and the emission spectra results indicated that red-dish-orange luminescence of SrZrO3:Eu3+due to magnetic dipole transition 5D0→7F1 at 593 nm was dominant. Thus, the prepared phosphor showed remarkable luminescent properties which find applications in field emission display (FED) and plasma display panel (PDP) devices.

  5. Photoluminescence of Bi(2+)-doped BaSO4 as a red phosphor for white LEDs.

    Science.gov (United States)

    Cao, Renping; Peng, Mingying; Qiu, Jianrong

    2012-11-05

    Bi(2+)-doped BaSO(4) phosphor was synthesized in air via solid state reaction method. Three excitation bands and one emission band were observed at 260 nm ((2)P(1/2) → (2)S(1/2)), 452 nm ((2)P(1/2) → (2)P(3/2)(2)), 592 nm ((2)P(1/2) → (2)P(3/2)(1)), and 627 nm ((2)P(3/2)(1) → (2)P(1/2)), respectively. W-LEDs were demonstrated by using a blend composition of BaSO(4):Bi(2+) and YAG:Ce(3+) hosphors pumped with a 455 nm blue LEDs chip. The results indicate that BaSO(4):Bi(2+) phosphor is suitable as potential red phosphor for application in W-LEDs excited with blue LEDs chip.

  6. Developing Quantum Dot Phosphor-Based Light-Emitting Diodes for Aviation Lighting Applications

    Directory of Open Access Journals (Sweden)

    Fengbing Wu

    2012-01-01

    Full Text Available We have investigated the feasibility of employing quantum dot (QD phosphor-based light-emitting diodes (LEDs in aviation applications that request Night Vision Imaging Systems (NVIS compliance. Our studies suggest that the emerging QD phosphor-based LED technology could potentially be superior to conventional aviation lighting technology by virtue of the marriage of tight spectral control and broad wavelength tunability. This largely arises from the fact that the optical properties of semiconductor nanocrystal QDs can be tailored by varying the nanocrystal size without any compositional changes. It is envisioned that the QD phosphor-based LEDs hold great potentials in cockpit illumination, back light sources of monitor screens, as well as the LED indicator lights of aviation panels.

  7. Solid-state combinatorial chemistry of Eu(2+)-doped Sr-Al-Si-O-N phosphors.

    Science.gov (United States)

    Park, Ji Woong; Han, Bo Yong; Kim, Yang Soo; Sohn, Kee-Sun

    2013-06-01

    Sr-Al-Si-O-N composition space was screened by a solid state combinatorial chemistry. For this sake, powder mixtures of Sr3N2, alpha-Si3N4, AIN and Eu3N2 was fired at 1500 degrees C-1900 degrees C for 2 h under 1.0 Mpa N2 using a gas pressurized sintering (GPS) furnace. The resultant phosphors were phase-identified, and the photo luminescence was examined. The Sr-Al-Si-O-N phosphors are blue-Green and orange in color and emit in the region of 520-630 nm depending on synthesized temperature. Considering an intense excitation band in blue LED and emission band, these materials can be used as novel conversion phosphor for White-LEDs, if the luminance was improved.

  8. Thermographic Phosphors for High Temperature Measurements: Principles, Current State of the Art and Recent Applications

    Directory of Open Access Journals (Sweden)

    Konstantinos Kontis

    2008-09-01

    Full Text Available This paper reviews the state of phosphor thermometry, focusing on developments in the past 15 years. The fundamental principles and theory are presented, and the various spectral and temporal modes, including the lifetime decay, rise time and intensity ratio, are discussed. The entire phosphor measurement system, including relative advantages to conventional methods, choice of phosphors, bonding techniques, excitation sources and emission detection, is reviewed. Special attention is given to issues that may arise at high temperatures. A number of recent developments and applications are surveyed, with examples including: measurements in engines, hypersonic wind tunnel experiments, pyrolysis studies and droplet/spray/gas temperature determination. They show the technique is flexible and successful in measuring temperatures where conventional methods may prove to be unsuitable.

  9. Co-Precipitation Preparation and Luminescent Behavior of (Y,Gd)BO3∶ Eu Phosphor

    Institute of Scientific and Technical Information of China (English)

    鱼志坚; 黄小卫; 庄卫东; 崔向中; 何华强; 李红卫

    2004-01-01

    (Y,Gd)BO3∶ Eu phosphors were prepared by co-precipitation precursors, and luminescent properties were investigated. The precursors were synthesized by introducing hydroxyl ion to mixed solution of rare earth nitrates and boric acid, either through adding ammonia(precursor 1)or through controlled release of hydroxyl ion of urea(precursor 2). The precursors were fired in air at 1000 ℃ for 2 h. Resulted phosphor synthesized with precursor 1 has non-uniformed particle with mean diameter of about 3 μm, while that with precursor 2 exhibits uniformed near spherical-like morphology with mean diameter of about 300 nm. Phosphors with the two methods exhibit same crystal structure as that of commercial one. Emission spectra of the samples indicate that the sample prepared with precursor 2 shows relative higher intensity(exited by 172 nm VUV)than that prepared with the other precursor.

  10. Luminescence modification of Eu~(3+)-activated molybdate phosphor prepared via co-precipitation

    Institute of Scientific and Technical Information of China (English)

    ZHAO Chunlei; HU Yunsheng; ZHUANG Weidong; HUANG Xiaowei; HE Tao

    2009-01-01

    Eu-activated CaMoO_4 phosphors were co-precipitated in an aqueous solution, and NH_3·H_2O, NH_4HCO_3 and (NH_2)_2CO as pre-cipitating aid agents were compared based on the morphology and particle size distribution of the phosphor samples. Sm~(3+) as sensitizer ion was investigated on the luminescence of CaMoO_4:Eu, and it could strengthen the 406 nm absorption of this phosphor. At last, the scheelite CaMoO_4:Eu and wolframite ZnMoO_4:Eu were selected to compare their host absorption. The result showed that the scheelite molybdate host exhibited stronger UV absorption than wolframite one.

  11. Luminescence modification of Eu3+-activated molybdate phosphor prepared via co-precipitation

    Institute of Scientific and Technical Information of China (English)

    ZHAO; Chunlei

    2009-01-01

    Eu-activated CaMoO4 phosphors were co-precipitated in an aqueous solution, and NH3·H2O, NH4HCO3 and (NH2)2CO as pre-cipitating aid agents were compared based on the morphology and particle size distribution of the phosphor samples. Sm3+ as sensitizer ion was investigated on the luminescence of CaMoO4:Eu, and it could strengthen the 406 nm absorption of this phosphor. At last, the scheelite CaMoO4:Eu and wolframite ZnMoO4:Eu were selected to compare their host absorption. The result showed that the scheelite molybdate host exhibited stronger UV absorption than wolframite one.

  12. Effect of Sintering Time on Luminescent Properties of YAG:Ce3+ Phosphors

    Institute of Scientific and Technical Information of China (English)

    Xiong Zhaoxian; Song Chunxiao; Wu Wei; Qiu Hong

    2004-01-01

    Phosphors of yttrium aluminium garnet activated by cerium ion, a kind of yellow luminescent materials for white LED lighting, were synthesized via solid-state reaction route in air and then reducing atmospheres.Thermal analysis was conducted by DTA/TGA.Moreover, XRD patterns of phosphors show that pure cubic phase of Y3 Al5 O12 is formed.Microstructures of the powders were observed by SEM.Luminescent spectra of the phosphors were also characterized by a spectrophotometer.The effect of sintering time on excitation and emission properties of the YAG: Ce3+ powders were systematically studied, resulting a best range of sintering time, 300 ~ 400 min, for maximal relative luminescent intensity.

  13. Doping phosphoric acid in polybenzimidazole membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Jensen, Jens Oluf;

    2007-01-01

    Polybenzimidazole (PBI) membranes were doped in phosphoric acid solutions of different concentrations at room temperature. The doping chemistry was studied using the Scatchard method. The energy distribution of the acid complexation in polymer membranes is heterogeneous, that is, there are two...... different types of sites in PBI for the acid doping. The protonation constants of PBI by phosphoric acid are found to be 12.7 L mol(-1) (K-1) for acid complexing sites with higher affinity, and 0.19 L mol(-1) (K-2) for the sites with lower affinity. The dissociation constants for the complexing acid onto...... these two types of PBI sites are found to be 5.4 X 10(-4) and 3.6 X 10(-2), respectively, that is, about 10 times smaller than that of aqueous phosphoric acid in the first case but 5 times higher in the second. The proton conducting mechanism is also discussed....

  14. Thermoluminescence investigations in X-ray irradiated CaS phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Adhikary, S. [Department of Applied Physics, Indian School of Mines University, Dhanbad 826004 (India); Choubey, A., E-mail: anjani_physics@yahoo.co [Department of Applied Physics, Indian School of Mines University, Dhanbad 826004 (India); Das, S.; Sharma, S.K.; Manam, J. [Department of Applied Physics, Indian School of Mines University, Dhanbad 826004 (India)

    2010-01-07

    We report the thermoluminescence studies of X-ray irradiated CaS phosphor. The CaS phosphor was prepared by solid-state diffusion method and characterized by X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Thermally stimulated luminescence (TSL) glow curves of X-ray irradiated CaS sample have two glow peaks at temperatures 100 and 130 {sup o}C. A reliable dosimetric study of a thermoluminescence material is based on good knowledge of its trapping parameters. The trapping parameters namely activation energy, order of kinetics and frequency factor associated with the prominent glow peak (130 {sup o}C) of CaS phosphor were calculated by using isothermal decay and glow curve shape (Chen's) methods.

  15. Fast phosphor picosecond streak tube for ultrafast laser diagnostics in repetitive mode

    Science.gov (United States)

    Ageeva, N. V.; Gornostaev, P. B.; Ivanova, S. R.; Kulechenkova, T. P.; Levina, G. P.; Lozovoi, V. I.; Makushina, V. A.; Schelev, M. Ya; Shashkov, E. V.; Scaballanovich, T. A.; Smirnov, A. V.; Vereschagin, A. K.; Vereschagin, K. A.; Vorobiev, N. S.

    2015-08-01

    The well-established PIF-01/S1/P43 picosecond streak tube, designed 30 years ago and still manufactured at the A.M. Prokhorov General Physics Institute, was modified by replacing its traditional P43 phosphor screen with a P47 one having approximately three orders of magnitude shorter decay time. The experimental measurements of this decay time were provided by PIF-01/S1/P47 image tube photocathode irradiation either with a single or a train of 8 ps laser pulses separated by 8 ns from each other at a 1.08 μm wavelength. The results of our preliminary measurements of P47-BH phosphor (manufactured by Phosphor Technology Ltd) indicate the possibility of employing the PIF-01/S1/P47 streak tube for synchrotron diagnostics at a units megahertz repetition rate without the negative influence of ‘ghost images’ from the previous streak records.

  16. Photo and electroluminescence of ZnSe: Sn and ZnSe:(Sn, Pr) phosphors

    Science.gov (United States)

    Mishra, A. K.; Mishra, S. K.; Pandey, S. P.; Lakshmi Mishra, Kshama

    2016-09-01

    We have prepared ZnSe (luminescent grade) phosphor doped with Sn and (Sn,Pr) with varying concentration in an inert atmosphere in a silica tubular furnace at temperature of (780 ± 20) °C for 1 hr to obtain ZnSe:Sn and ZnSe: (Sn,Pr) phosphors. The photo luminescence (PL) and electroluminescence (EL) spectra of these phosphors have been studied at room temperature and results were discussed in the light of existing models. Dependence of EL emission on the voltage frequency has also been carried out. It is found that the plot between the integrated light intensity versus 1/√Vrms is a straight line suggesting the existence of Mott-Schottky type barrier on the metal semiconductor interface.

  17. Phosphorous transient enhanced diffusion suppression and activation enhancement with cluster carbon co-implantation

    Energy Technology Data Exchange (ETDEWEB)

    Nakashima, Yoshiki; Hamamoto, Nariaki; Nagayama, Tsutomu; Koga, Yuji; Umisedo, Sei; Kawamura, Yasunori; Hashimoto, Masahiro; Onoda, Hiroshi [Nissin Ion Equipment Co., Ltd., 575 Kuze Tonoshiro-cho, Minami-ku, Kyoto, 601-8205 (Japan)

    2012-11-06

    Carbon co-implantation is well known as an effective method for suppressing boron/phosphorous transient enhanced diffusion (TED). Germanium pre-amorphization implantation (PAI) is usually applied prior to carbon co-implantation for suppressing channeling tail of dopants. In this study, cluster carbon was applied instead of the combination of germanium PAI and monomer carbon co-implantation prior to phosphorous implantation. Dependence of phosphorous activation and TED on amorphous layer thickness, carbon dose, carbon distribution and substrate temperature have been investigated. Cluster carbon implantation enables thick amorphous layer formation and TED suppression at the same time and low temperature implantation enhances the ability of amorphous layer formation so that shallow junction and low Rs can be achieved without Ge implantation.

  18. Effect of spinel content on the properties of phosphoric acid bonded high alumina castables

    Institute of Scientific and Technical Information of China (English)

    Zichun Yang; Hongwei Duan; Lin Li; Shuqin Li; Wen Ni

    2003-01-01

    In order to study the effect of fused spinel on the properties of phosphoric acid bonded high alumina castables, samples with different contents of fused spinel were prepared. The results show that when the contents of the fused spinel are between 8% and 16% (mass fraction), the castables have good properties. The castables overcome the shortages of the phosphoric acid bonded high alumina castables with bauxite cement as a hardening promoter. The experiments demonstrate that most of the service properties of the castables with fused spinel are better than those of the normal phosphoric acid bonded castables which use bauxite cement as a hardening promoter. The examination of the materials indicates that free MgO inclusions in the spinel powder can promote the hardening of the castables.

  19. Laser-induced down-conversion parameters of singly and doubly doped ZnS phosphors

    Indian Academy of Sciences (India)

    H S Bhatti; Rajesh Sharma; N K Verma

    2005-09-01

    Singly and doubly doped ZnS phosphors have been synthesized using flux method. Laser-induced photoluminescence has been observed in ZnS-doped phosphors when these were excited by the pulsed UV N2 laser radiation. Due to down-conversion phenomenon, fast phosphorescence emission in the visible region is recorded in milliseconds time domain for ZnS:Mn while in the case of ZnS:Mn:killer (Fe, Co and Ni) the lifetime reduces to microseconds time domain. Experimentally observed luminescent emission parameters of excited states such as, lifetimes, trap-depth values and decay constants have been reported here at room temperature. The high efficiency and fast recombination times observed in doped ZnS phosphors make these materials very attractive for optoelectronic applications.

  20. Conformal phosphor coating using pulsed spray to reduce color deviation of white LEDs.

    Science.gov (United States)

    Huang, Hsin-Tao; Tsai, Chuang-Chuang; Huang, Yi-Pai

    2010-06-21

    This work presents a novel "pulsed spray (PS)" process for the coating of yellow YAG:Ce(3+) phosphor on blue InGaN-based light emitting diodes (LEDs). To coat a phosphor layer of high quality on an LED chip surface, the PS approach is used and studied because of the uniform color distribution, providing a wide range of color temperatures. This PS coating approach applies phosphor by exploiting mechanical principles without risk of chemical pollution. Additionally, it can be applied to wire-bonded LEDs and an array of LED chips on a substrate to fabricate a large-area, planar illumination system of high optical quality, which is easy to manufacture.

  1. Phosphoric acid as a matrix additive for MALDI MS analysis of phosphopeptides and phosphoproteins

    DEFF Research Database (Denmark)

    Kjellström, Sven; Jensen, Ole Nørregaard

    2004-01-01

    Phosphopeptides are often detected with low efficiency by MALDI MS analysis of peptide mixtures. In an effort to improve the phosphopeptide ion response in MALDI MS, we investigated the effects of adding low concentrations of organic and inorganic acids during peptide sample preparation in 2......,5-dihydroxybenzoic acid (2,5-DHB) matrix. Phosphoric acid in combination with 2,5-DHB matrix significantly enhanced phosphopeptide ion signals in MALDI mass spectra of crude peptide mixtures derived from the phosphorylated proteins alpha-casein and beta-casein. The beneficial effects of adding up to 1% phosphoric...... acid to 2,5-DHB were also observed in LC-MALDI-MS analysis of tryptic phosphopeptides of B. subtilis PrkC phosphoprotein. Finally, the mass resolution of MALDI mass spectra of intact proteins was significantly improved by using phosphoric acid in 2,5-DHB matrix....

  2. Optical Temperature Sensing Behavior Through Stark Sublevels Transitions of Green and Red Upconversion Emissions for Er3+-Yb3+-Li+ Codoped TiO2 Phosphors.

    Science.gov (United States)

    He, Y Y; Wu, J L; Wang, X H; Feng, Z Q; Dong, B

    2016-04-01

    The Er3+-Yb3+-Li+ codoped TiO2 phosphors have been prepared by sol-gel method. The green and red upconversion emissions were observed under a 976 nm laser diode excitation, which were ascribed to 2H11/2 --> 4I15/2, 4S3/2(I)/4S3/2(II) -->4I15/2, and 4F9/2(I)/4F9/2(II) -->4I15/2 transitions of Er3+ Stark sublevels. The fluorescence intensity ratios (FIR), which are corresponding to the transitions of 2H11/2/(4S3/2(I)+4S3/2(II))--> 4I5/2, 4S3/2(I)/4S3/2(II) -->4I15/2, and 4F9/2(II)/4F9/2(II) -->4I15/2, have been studied as a function of temperature in the range of 303 673 K. The temperature sensitivities have been calculated at the maximum value of 0.0020 K-1, 0.0015 K-1, and 0.0011 K-1 at the temperatures of 427 K, 350 K, and 273 K for the three coupled energy level transitions, respectively. The Er3+-Yb3+-Li+ codoped Ti02 phosphor with different temperature sensitivities by Stark sublevels indicated that it is a promising material for application in optical temperature sensing at a wide range of temperature.

  3. Minimum handling method for the analysis of phosphorous inhibitors of urolithiasis (pyrophosphate and phytic acid) in urine by SPE-ICP techniques.

    Science.gov (United States)

    Muñoz, Jose A; López-Mesas, Montserrat; Valiente, Manuel

    2010-01-25

    Pyrophosphate (PPi) and phytic acid (IP6) are natural phosphorous compounds with growing interest in the biomedical field due to their ability as potential inhibitors of urolithiasis among others. Existing methodologies for their evaluation show inconveniences mainly associated with sample treatment, matrix interferences and lack of resolution. The objective of the present work is the validation of a new method to determine both inhibitors in urine samples selectively and its application to the diagnosis of lithiasic patients. After urine purification by an off-line anion exchange solid phase extraction (SPE), based in an appropriate acidic elution gradient, the phosphorous compounds were analyzed by (31)P measurements by inductively coupled plasma mass spectrometry (ICP-MS) in the purified urine extracts. Linear range and limit of detection obtained were adequate for the analysis of the physiological amounts of the compounds in urine. The method was successfully applied to human urine samples, resulting in adequate accuracy and precision and allowing for the analysis of phosphorus inhibitors of urolithiasis in urine. The method simplicity and high sample throughput leads to a clear alternative to current determinations of the mentioned species in urine. Moreover, PPi and IP6 concentrations found in patients suffering from oxalocalcic urolithiasic were significantly lower than those for healthy controls, supporting the fact that the risk for oxalocalcic urolithiasis increases when urinary phosphorus inhibitors decrease. Thus, speciation of phosphorus inhibitors of urolithiasis in urine of stone formers can be performed, which is of unquestionable value in diagnostic, treatment and monitoring of urolithiasis.

  4. Effects of Ca Content on Formation and Photoluminescence Properties of CaAlSiN3:Eu2+ Phosphor by Combustion Synthesis

    Science.gov (United States)

    Chung, Shyan-Lung; Huang, Shu-Chi

    2016-01-01

    Effects of Ca content (in the reactant mixture) on the formation and the photoluminescence properties of CaAlSiN3:Eu2+ phosphor (CASIN) were investigated by a combustion synthesis method. Ca, Al, Si, Eu2O3, NaN3, NH4Cl and Si3N4 powders were used as the starting materials and they were mixed and pressed into a compact which was then wrapped up with an igniting agent (i.e., Mg + Fe3O4). The compact was ignited by electrical heating under a N2 pressure of ≤1.0 MPa. By keeping the molar ratios of Al and Si (including the Si powder and the Si in Si3N4 powder) both at 1.00 and that of Eu2O3 at 0.02, XRD (X-ray diffraction) coupled with TEM-EDS (transmission electron microscope equipped with an energy-dispersive X-ray spectroscope) and SAED (selected area electron diffraction) measurements show that AlN:Eu2+ and Ca-α-SiAlON:Eu2+ are formed as the major phosphor products when the Ca molar ratio (denoted by Y) is equal to 0.25 and AlN:Eu2+ and Ca-α-SiAlON:Eu2+ could not be detected at Y ≥ 0.75 and ≥1.00, respectively. CASIN (i.e., CaAlSiN3:Eu2+) becomes the only phosphor product as Y is increased to 1.00 and higher. The extent of formation of CASIN increases with increasing Y up to 1.50 and begins to decrease as Y is further increased to 1.68. While the excitation wavelength regions are similar at various Y, the emission wavelength regions vary significantly as Y is increased from 0.25 to 1.00 due to different combinations of phosphor phases formed at different Y. The emission intensity of CASIN was found to vary with Y in a similar trend to its extent of formation. The Ca and Eu contents (expressed as molar ratios) in the synthesized products were found to increase roughly with increasing Y but were both lower than the respective Ca and Eu contents in the reactant mixtures. PMID:28773303

  5. Effects of Ca Content on Formation and Photoluminescence Properties of CaAlSiN3:Eu2+ Phosphor by Combustion Synthesis

    Directory of Open Access Journals (Sweden)

    Shyan-Lung Chung

    2016-03-01

    Full Text Available Effects of Ca content (in the reactant mixture on the formation and the photoluminescence properties of CaAlSiN3:Eu2+ phosphor (CASIN were investigated by a combustion synthesis method. Ca, Al, Si, Eu2O3, NaN3, NH4Cl and Si3N4 powders were used as the starting materials and they were mixed and pressed into a compact which was then wrapped up with an igniting agent (i.e., Mg + Fe3O4. The compact was ignited by electrical heating under a N2 pressure of ≤1.0 MPa. By keeping the molar ratios of Al and Si (including the Si powder and the Si in Si3N4 powder both at 1.00 and that of Eu2O3 at 0.02, XRD (X-ray diffraction coupled with TEM-EDS (transmission electron microscope equipped with an energy-dispersive X-ray spectroscope and SAED (selected area electron diffraction measurements show that AlN:Eu2+ and Ca-α-SiAlON:Eu2+ are formed as the major phosphor products when the Ca molar ratio (denoted by Y is equal to 0.25 and AlN:Eu2+ and Ca-α-SiAlON:Eu2+ could not be detected at Y ≥ 0.75 and ≥1.00, respectively. CASIN (i.e., CaAlSiN3:Eu2+ becomes the only phosphor product as Y is increased to 1.00 and higher. The extent of formation of CASIN increases with increasing Y up to 1.50 and begins to decrease as Y is further increased to 1.68. While the excitation wavelength regions are similar at various Y, the emission wavelength regions vary significantly as Y is increased from 0.25 to 1.00 due to different combinations of phosphor phases formed at different Y. The emission intensity of CASIN was found to vary with Y in a similar trend to its extent of formation. The Ca and Eu contents (expressed as molar ratios in the synthesized products were found to increase roughly with increasing Y but were both lower than the respective Ca and Eu contents in the reactant mixtures.

  6. Thermoluminescence and defect centres in Tb doped lithium magnesium borate phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Menon, S.N., E-mail: sanju_n_m@yahoo.com [Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Kadam, Sonal [Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Watanabe, S.; Gundu Rao, T.K. [Institute of Physics, University of Sao Paulo, 05508-090 Sao Paulo, SP (Brazil); Kulkarni, M.S.; Babu, D.A.R. [Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India)

    2015-11-15

    Terbium doped lithium magnesium borate phosphor exhibits thermoluminescence (TL) peaks at about 140 °C, 200 °C, 225 °C and 370 °C. The phosphor was characterized by X-ray powder diffraction and photoluminescence studies. Electron Spin Resonance (ESR) studies were carried out to identify the defect centres responsible for the TL peaks. Room temperature ESR spectrum of irradiated phosphor appears to be a superposition of two distinct centres. One of the centres (centre I) with principal g-value 2.0108 is identified as an O{sup −} ion and the centre correlates with the TL peak at 200 °C. Centre II with an isotropic g-factor 2.0029 is assigned to an F{sup +}-type centre (singly ionized oxygen vacancy) and is the likely recombination centre for the TL peaks at 200 °C and 225 °C. An additional defect centre is observed during thermal annealing experiments and this centre (assigned to F{sup +} centre) seems to originate from an F centre (oxygen vacancy with two electrons). This F centre may be related to the observed high temperature 370 °C TL peak in LiMgBO{sub 3}:Tb phosphor. - Highlights: • Powder phosphor of LiMgBO{sub 3}:Tb{sup 3+} was prepared by solid state diffusion method. • The phosphor exhibits a dominant emission at 545 nm ({sup 5}D{sub 4}→{sup 7}F{sub 5}) of the Tb{sup 3+} ion. • Electron Spin Resonance studies have been carried out to identify the defect centres responsible for the observed thermoluminescence peaks.

  7. Methyl phosphate formation as a major degradation mode of direct methanol fuel cells with phosphoric acid based electrolytes

    DEFF Research Database (Denmark)

    Aili, David; Vassiliev, Anton; Jensen, Jens Oluf

    2015-01-01

    Phosphoric acid and phosphoric acid doped polymer membranes are widely used as electrolytes in hydrogen based fuel cells operating at elevated temperatures. Such electrolytes have been explored for direct oxidation of methanol to further increase the versatility of the systems, however, with demo...

  8. Reliability and Lifetime Prediction of Remote Phosphor Plates in Solid-State Lighting Applications Using Accelerated Degradation Testing

    NARCIS (Netherlands)

    Yazdan Mehr, M.; Van Driel, W.D.; Zhang, G.Q.

    2015-01-01

    A methodology, based on accelerated degradation testing, is developed to predict the lifetime of remote phosphor plates used in solid-state lighting (SSL) applications. Both thermal stress and light intensity are used to accelerate degradation reaction in remote phosphor plates. A reliability model,

  9. Phosphorous Application Improves Drought Tolerance of Phoebe zhennan

    Directory of Open Access Journals (Sweden)

    Akash Tariq

    2017-09-01

    Full Text Available Phoebe zhennan (Gold Phoebe is a threatened tree species in China and a valuable and important source of wood and bioactive compounds used in medicine. Apart from anthropogenic disturbances, several biotic constraints currently restrict its growth and development. However, little attention has been given to building adaptive strategies for its conservation by examining its morphological and physio-biochemical responses to drought stress, and the role of fertilizers on these responses. A randomized experimental design was used to investigate the effects of two levels of irrigation (well-watered and drought-stressed and phosphorous (P fertilization treatment (with and without P to assess the morphological and physio-biochemical responses of P. zhennan seedlings to drought stress. In addition, we evaluated whether P application could mitigate the negative impacts of drought on plant growth and metabolism. Drought stress had a significant negative effect on the growth and metabolic processes of P. zhennan. Despite this, reduced leaf area, limited stomatal conductance, reduced transpiration rate, increased water use efficiency, enhanced antioxidant enzymes activities, and osmolytes accumulation suggested that the species has good adaptive strategies for tolerating drought stress. Application of P had a significant positive effect on root biomass, signifying its improved water extracting capacity from the soil. Moreover, P fertilization significantly increased leaf relative water content, net photosynthetic rate, and maximal quantum efficiency of PSII under drought stress conditions. This may be attributable to several factors, such as enhanced root biomass, decreased malondialdehyde content, and the up-regulation of chloroplast pigments, osmolytes, and nitrogenous compounds. However, P application had only a slight or negligible effect on the growth and metabolism of well-watered plants. In conclusion, P. zhennan has a strong capability for drought

  10. Optical enhancement of phosphor-converted wLEDs using glass beads

    Science.gov (United States)

    Güner, Tuğrul; Şentürk, Ufuk; Demir, Mustafa M.

    2017-10-01

    YAG:Ce3+ is a yellow-source compound commonly used in phosphor conversion layers for direct coating or remote phosphor configurations in LED illumination. This material, however, suffers from a high correlated color temperature, and low color-rendering index due to its deficiency in the red spectrum. In this study, glass beads (GB) with an average particle diameter of 10 μm were introduced to the conversion layer of a YAG:Ce3+ particulate-filled polydimethylsiloxane matrix composite structure and found to improve the optical features of the resulting composite.

  11. High applicability of two-dimensional phosphorous in Kagome lattice predicted from first-principles calculations

    OpenAIRE

    Peng-Jen Chen; Horng-Tay Jeng

    2016-01-01

    A new semiconducting phase of two-dimensional phosphorous in the Kagome lattice is proposed from first-principles calculations. The band gaps of the monolayer (ML) and bulk Kagome phosphorous (Kagome-P) are 2.00 and 1.11 eV, respectively. The magnitude of the band gap is tunable by applying the in-plane strain and/or changing the number of stacking layers. High optical absorption coefficients at the visible light region are predicted for multilayer Kagome-P, indicating potential applications ...

  12. Co-doping with antimony to control phosphorous diffusion in germanium

    KAUST Repository

    Tahini, H. A.

    2013-02-15

    In germanium, phosphorous and antimony diffuse quickly and as such their transport must be controlled in order to design efficient n-typed doped regions. Here, density functional theory based calculations are used to predict the influence of double donor co-doping on the migration activation energies of vacancy-mediated diffusion processes. The migration energy barriers for phosphorous and antimony were found to be increased significantly when larger clusters involving two donor atoms and a vacancy were formed. These clusters are energetically stable and can lead to the formation of even larger clusters involving a number of donor atoms around a vacancy, thereby affecting the properties of devices.

  13. Evolution of the graphite surface in phosphoric acid: an AFM and Raman study

    Science.gov (United States)

    Brambilla, Luigi; Bussetti, Gianlorenzo; Tommasini, Matteo; Li Bassi, Andrea; Casari, Carlo Spartaco; Passoni, Matteo; Ciccacci, Franco; Duò, Lamberto; Castiglioni, Chiara

    2016-01-01

    Summary Phosphoric acid is an inorganic acid used for producing graphene sheets by delaminating graphite in (electro-)chemical baths. The observed phenomenology during the electrochemical treatment in phosphoric acid solution is partially different from other acidic solutions, such as sulfuric and perchloric acid solutions, where the graphite surface mainly forms blisters. In fact, the graphite surface is covered by a thin layer of modified (oxidized) material that can be observed when an electrochemical potential is swept in the anodic current regime. We characterize this particular surface evolution by means of a combined electrochemical, atomic force microscopy and Raman spectroscopy investigation.

  14. Relaxation kinetics of Sm: Ce-doped CaS phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Paulose, P.I. [Research Centre, Department of Physics, Maharajas College, Ernakulam 682011 (India); Joseph, James [St. Pauls College, Kalamassery, Ernakulam (India); Rudra Warrier, M.K. [Research Centre, Department of Physics, Maharajas College, Ernakulam 682011 (India); Jose, Gijo [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686560 (India); Unnikrishnan, N.V. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686560 (India)], E-mail: nvu50@yahoo.co.in

    2007-12-15

    Different samples of calcium sulphide (CaS):CaS(Sm) and CaS(Sm,Ce) phosphors have been prepared. To study the phosphorescence decay systematically, the samples were excited to a saturation using 259 nm line of xenon lamp and phosphorescence emission was monitored for a wavelength 569 nm of samarium. The trap depth has been evaluated by analyzing the decay curves. The observed decay could be explained satisfactorily by assuming a superposition scheme. The thermoluminescence properties of the doped CaS phosphors are also investigated in detail by computerized deconvolution technique of the glow curves obtained by UV irradiation.

  15. Are the effects of nicotinic acid on insulin resistance precipitated by abnormal phosphorous metabolism?

    Directory of Open Access Journals (Sweden)

    AbuSabha Hatem S

    2004-10-01

    Full Text Available Abstract Nicotinic acid is a unique cholesterol modifying agent that exerts favorable effects on all cholesterol parameters. It holds promise as one of the main pharmacological agents to treat mixed dyslipidemia in metabolic syndrome and diabetic patients. The use of nicotinic acid has always been haunted with concerns that it might worsen insulin resistance and complicate diabetes management. We will discuss the interaction between phosphorous metabolism and carbohydrate metabolism and the possibility that worsening of insulin resistance could be related to adrug induced alteration in phosphorous metabolism, and the implications of that in medical management of diabetes and metabolic syndrome patients with mixed dyslipidemia.

  16. Reaching 200-ps timing resolution in a time-of-flight and depth-of-interaction positron emission tomography detector using phosphor-coated crystals and high-density silicon photomultipliers.

    Science.gov (United States)

    Kwon, Sun Il; Ferri, Alessandro; Gola, Alberto; Berg, Eric; Piemonte, Claudio; Cherry, Simon R; Roncali, Emilie

    2016-10-01

    Current research in the field of positron emission tomography (PET) focuses on improving the sensitivity of the scanner with thicker detectors, extended axial field-of-view, and time-of-flight (TOF) capability. These create the need for depth-of-interaction (DOI) encoding to correct parallax errors. We have proposed a method to encode DOI using phosphor-coated crystals. Our initial work using photomultiplier tubes (PMTs) demonstrated the possibilities of the proposed method, however, a major limitation of PMTs for this application is poor quantum efficiency in yellow light, corresponding to the wavelengths of the converted light by the phosphor coating. In contrast, the red-green-blue-high-density (RGB-HD) silicon photomultipliers (SiPMs) have a high photon detection efficiency across the visible spectrum. Excellent coincidence resolving time (CRT; [Formula: see text]) was obtained by coupling RGB-HD SiPMs and [Formula: see text] lutetium fine silicate crystals coated on a third of one of their lateral sides. Events were classified in three DOI bins ([Formula: see text] width) with an average sensitivity of 83.1%. A CRT of [Formula: see text] combined with robust DOI encoding is a marked improvement in the phosphor-coated approach that we pioneered. For the first time, we read out these crystals with SiPMs and clearly demonstrated the potential of the RGB-HD SiPMs for this TOF-DOI PET detector.

  17. Effect of UV irradiation on different types of luminescence of SrAl2 O4 :Eu,Dy phosphors.

    Science.gov (United States)

    Jha, Piyush

    2016-11-01

    This paper reports the luminescence behavior of Sr0.097 Al2 O4 :Eu0.01 ,Dy0.02 phosphors under UV-irradiation. The effect of UV-irradiation on afterglow (AG), thermoluminescence (TL) and mechanoluminescence (ML) of Sr0.097 Al2 O4 :Eu0.01 ,Dy0.02 phosphors is investigated. The space group of Sr0.097 Al2 O4 :Eu0.01 ,Dy0.02 phosphors is monoclinic P21 . The prepared phosphors exhibit a long AG, intense TL and ML. It is found that the AG, ML intensity and TL increase with increasing duration of irradiation time. The ML intensity decreases with successive impact of the load onto the phosphors, whereby the diminished ML intensity can be recovered by UV-irradiation. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  18. Synergistic extraction of rare earth by mixtures of 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester and di-(2-ethylhexyl) phosphoric acid from sulfuric acid medium?

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiaowei; LI Jianning; LONG Zhiqi; ZHANG Yongqi; XUE Xiangxin; ZHU Zhaowu

    2008-01-01

    The extraction of Nd3+ and Sm3+, including the extraction and stripping capability as well as the separation effect of Nd3+ or Sm3+, from a sulfuric acid medium, by mixtures of di-(2-ethylhexyl) phosphoric acid (HDEHP, H2A2(0)) and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (HEH/EHP, H2L2(0)) were studied. The distribution ratios and synergistic coefficients of Nd3+ and Sm3+ in different acidities were also determined. A synergistic extractive effect was found when HDEHP and HEH/EHP were used as mixed extractants for Sm3+ or Nd3+. The chemical compositions of the extracted complex were determined as Nd·(HA2)2·HL2 and Sm·(HA2)2·HL2. The extraction equilibrium constants, enthalpy change, and entropy change of the extraction reaction were also determined.

  19. Geometric calibration and correction for a lens-coupled detector in x-ray phase-contrast imaging.

    Science.gov (United States)

    George, Alex; Chen, Peter Y; Morales-Martinez, Alejandro; Panna, Alireza; Gomella, Andrew A; Bennett, Eric E; Wen, Han

    2017-01-01

    A lens-coupled x-ray camera with a tilted phosphor collects light emission from the x-ray illuminated (front) side of phosphor. Experimentally, it has been shown to double x-ray photon capture efficiency and triple the spatial resolution along the phosphor tilt direction relative to the same detector at normal phosphor incidence. These characteristics benefit grating-based phase-contrast methods, where linear interference fringes need to be clearly resolved. However, both the shallow incident angle on the phosphor and lens aberrations of the camera cause geometric distortions. When tiling multiple images of limited vertical view into a full-field image, geometric distortion causes blurring due to image misregistration. Here, we report a procedure of geometric correction based on global polynomial transformation of image coordinates. The corrected image is equivalent to one obtained with a single full-field flat panel detector placed at the sample plane. In a separate evaluation scan, the position deviations in the horizontal and vertical directions were reduced from 0.76 and 0.028 mm, respectively, to 0.006 and 0.009 mm, respectively, by the correction procedure, which were below the 0.028-mm pixel size of the imaging system. In a demonstration of a phase-contrast imaging experiment, the correction reduced blurring of small structures.

  20. Enhancing the water-resistance stability of CaS:Eu2+,Sm2+phosphor with SiO2-PMMA composite coating

    Institute of Scientific and Technical Information of China (English)

    张杰强; 范艳伟; 陈朝阳; 闫世友; 王军华; 赵鹏君; 郝斌; 盖敏强

    2015-01-01

    This work was aimed at improving the water-resistance stability of CaS:Eu2+,Sm2+phosphor. An organic-inorganic com-posite coating method was adopted in order to obtain ideal phosphor. The phosphor was coated with SiO2 via sol-gel technique and it was also covered by polymethyl methacrylate (PMMA) via dissolution-cohesion technique. Powder X-ray diffraction (XRD) patterns, fluorescence spectroscopy and transmission electron microscopy (TEM) were employed to characterize the phase structures, emission spectrum and surface morphologies, respectively. In addition, the water-resistance stability of the phosphor was tested by soaking the phosphor into deionized water. The results showed that the phase structures remained the same as the uncoated phosphor and the po-sition of the fluorescence peak did not shift after surface treatment. Results showed that the water-resistance stability of the phosphor was improved to some degree. Moreover, the photoluminescence (PL) intensity of the coated phosphors reduced less than 10%of the original phosphors. Though being soaked into deionized water for 50 h, the phosphor coated with 10 wt.%SiO2-10 wt.%PMMA retained 85.9%PL intensity compared to that of the uncoated phosphor. Therefore, it could be concluded that the 10 wt.%SiO2-10 wt.%PMMA composite coating effectively improved the phosphor water resistance and retained its good optical properties.

  1. Why do proton conducting polybenzimidazole phosphoric acid membranes perform well in high-temperature PEM fuel cells?

    Science.gov (United States)

    Melchior, Jan-Patrick; Majer, Günter; Kreuer, Klaus-Dieter

    2016-12-21

    Transport properties and hydration behavior of phosphoric acid/(benz)imidazole mixtures are investigated by diverse NMR techniques, thermogravimetric analysis (TGA) and conductivity measurements. The monomeric systems can serve as models for phosphoric acid/poly-benzimidazole membranes which are known for their exceptional performance in high temperature PEM fuel cells. (1)H- and (31)P-NMR data show benzimidazole acting as a strong Brønsted base with respect to neat phosphoric acid. Since benzimidazole's nitrogens are fully protonated with a low rate for proton exchange with phosphate species, proton diffusion and conduction processes must take place within the hydrogen bond network of phosphoric acid only. The proton exchange dynamics between phosphate and benzimidazole species pass through the intermediate exchange regime (with respect to NMR line separations) with exchange times being close to typical diffusion times chosen in PFG-NMR diffusion measurements (ms regime). The resulting effects, as described by the Kärger equation, are included into the evaluation of PFG-NMR data for obtaining precise proton diffusion coefficients. The highly reduced proton diffusion coefficient within the phosphoric acid part of the model systems compared to neat phosphoric acid is suggested to be the immediate consequence of proton subtraction from phosphoric acid. This reduces hydrogen bond network frustration (imbalance of the number of proton donors and acceptors) and therefore also the rate of structural proton diffusion, phosphoric acid's acidity and hygroscopicity. Reduced water uptake, shown by TGA, goes along with reduced electroosmotic water drag which is suggested to be the reason for PBI-phosphoric acid membranes performing better in fuel cells than other phosphoric-acid-containing electrolytes with higher protonic conductivity.

  2. Pulsed beam dosimetry using fiber-coupled radioluminescence detectors

    DEFF Research Database (Denmark)

    Andersen, Claus Erik

    2012-01-01

    The objective of this work was to review and discuss the potential application of fiber-coupled radioluminescence detectors for dosimetry in pulsed MV photon beams. Two types of materials were used: carbon-doped aluminium oxide (Al2O3:C) and organic plastic scintillators. Special consideration...... was given to the discrimination between radioluminescence signals from the phosphors and unwanted light induced in the optical fiber cables during irradiation (Cerenkov and fluorescence). New instrumentation for dose-per-pulse measurements with organic plastic scintillators was developed....

  3. Preparation and Luminescence Characteristics of Ca3Y2(BO3)4:Eu3+ Phosphor

    Institute of Scientific and Technical Information of China (English)

    LI Pan-Lai; YANG Zhi-Ping; WANG Zhi-Jun; Guo Qing-Lin

    2007-01-01

    Ca3Y2(BO3)4:Eu3+ phosphor is synthesized by high temperature solid-state reaction method, and the luminescence characteristics are investigated. The emission spectrum exhibits two strong red emissions at 613 and 621 nm corresponding to the electric dipole 5 Do-7F2 transition of Eu3+ under 365 nm excitation, the reason is that Eu3+ substituting for y3+ occupies the non-centrosymmetric position in the crystal structure of Ca3Y2 (BO3 )4. The excitation spectrum for 613 nm indicates that the phosphor can be effectively excited by ultraviolet (UV) (254 nm,365nm and 400nm) and blue (470nm) light. The effect of Eu3+ concentration on the emission intensity of Ca3Y2 (BO3 )4:Eu3+ phosphor is measured, the result shows that the emission intensities increase with increasing Eu3+ concentration, then decrease. The CIE colour coordinates of Ca3Y2(BO3)4:Eu3+ phosphor is (0.639, 0.357) at 15mol% Eu3+.

  4. Experiences from Swedish demonstration projects with phosphoric acid fuel cells; Erfarenheter fraan svenska demonstrationsprojekt med fosforsyrabraensleceller

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Per [Sycon Energikonsult AB, Stockholm (Sweden); Sarkoezi, Laszlo [Vattenfall Utveckling AB, Stockholm (Sweden)

    1999-10-01

    In Sweden, there are today two phosphoric acid fuel cells installed, one PC25A which have been in operation in more than 4 years, and one PC25C which have been in operation for two years. The aim with this project has been two compare operation characteristics, performance, and operation experiences for these two models.

  5. Enhanced exciton emission from ZnO nano-phosphor induced by Yb3+ ions

    CSIR Research Space (South Africa)

    Kabongo, GL

    2014-01-01

    Full Text Available In this work, the sol–gel method was used to prepare Ytterbium (Yb(sup3+)) doped ZnO nano-phosphors with different concentrations of Yb(sup3+) ions. Their structural, morphological, photoluminescence, electronic states and the chemical composition...

  6. Optimizing ethanol and methane production from steam-pretreated, phosphoric acid-impregnated corn stover.

    Science.gov (United States)

    Bondesson, Pia-Maria; Dupuy, Aurélie; Galbe, Mats; Zacchi, Guido

    2015-02-01

    Pretreatment is of vital importance in the production of ethanol and methane from agricultural residues. In this study, the effects of steam pretreatment with phosphoric acid on enzymatic hydrolysis (EH), simultaneous saccharification and fermentation (SSF), anaerobic digestion (AD) and the total energy output at three different temperatures were investigated. The effect of separating the solids for SSF and the liquid for AD was also studied and compared with using the whole slurry first in SSF and then in AD. Furthermore, the phosphoric acid was compared to previous studies using sulphuric acid or no catalyst. Using phosphoric acid resulted in higher yields than when no catalyst was used. However, compared with sulphuric acid, an improved yield was only seen with phosphoric acid in the case of EH. The higher pretreatment temperatures (200 and 210 °C) resulted in the highest yields after EH and SSF, while the highest methane yield was obtained with the lower pretreatment temperature (190 °C). The highest yield in terms of total energy recovery (78 %) was obtained after pretreatment at 190 °C, but a pretreatment temperature of 200 °C is, however, the best alternative since fewer steps are required (whole slurry in SSF and then in AD) and high product yields were obtained (76 %).

  7. Evolving point-of-care diagnostics using up-converting phosphor bioanalytical systems.

    Science.gov (United States)

    Ouellette, Amy L; Li, Janice J; Cooper, David E; Ricco, Antonio J; Kovacs, Gregory T A

    2009-05-01

    Up-converting phosphors promise simpler readout systems with less background at a given signal level than many other popular approaches. (To listen to a podcast about this feature, please go to the Analytical Chemistry website at pubs.acs.org/journal/ancham.).

  8. 40 CFR 721.6200 - Fatty acid polyamine condensate, phosphoric acid ester salts.

    Science.gov (United States)

    2010-07-01

    ..., phosphoric acid ester salts. 721.6200 Section 721.6200 Protection of Environment ENVIRONMENTAL PROTECTION... ester salts. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substances identified as fatty acid polyamine condensate, phosphate ester salts (PMNs P-90-1984 and...

  9. Development of gamma spectrometric method for the determination of thorium in phosphoric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Mirashi, N.N.; Chaudhury, S.; Aggarwal, S.K. [Fuel Chemistry Div., Bhabha Atomic Research Centre, Mumbai (India)

    2010-07-01

    Gamma spectrometric determination of thorium in sintered thoria dissolved in strong phosphoric acid was studied using a high purity germanium (HPGe) detector. {sup 232}Th was determined using the highly abundant (27%) gamma ray (911.4 keV) emitted by its daughter {sup 228}Ac. The count rates in peak regions were plotted against the amount of thorium present in thorium nitrate working standard solution to obtain a calibration curve and the extent of thoria dissolved in 88% phosphoric acid was determined. Further studies on determination of thorium were carried out using thorium phosphate solutions, instead of using thorium nitrate working standard solutions. The solution of thorium phosphate obtained after quantitative dissolution of thoria in 88% phosphoric acid was also found to give a linear calibration curve at 911.4 keV. Using the calibration curves, expected count rates for thorium in sintered thoria dissolved in 88% phosphoric acid were calculated and were in good agreement ({+-}3%) with the observed count rates. (orig.)

  10. Proton conductivity of phosphoric acid doped polybenzimidazole and its composites with inorganic proton conductors

    DEFF Research Database (Denmark)

    He, Ronghuan; Qingfeng, Li; Gang, Xiao

    2003-01-01

    Phosphoric acid doped polybenzimidazole (PBI) and PBI composite membranes have been prepared in the present work. The PBI composites contain inorganic proton conductors including zirconium phosphate (ZrP), (Zr(HPO4)2·nH2O), phosphotungstic acid (PWA), (H3PW12O40·nH2O) and silicotungstic acid (Si...

  11. Atomic force microscopy observation of the enamel roughness and depth profile after phosphoric acid etching.

    Science.gov (United States)

    Loyola-Rodriguez, Juan Pablo; Zavala-Alonso, Veronica; Reyes-Vela, Enrique; Patiño-Marin, Nuria; Ruiz, Facundo; Anusavice, Kenneth J

    2010-01-01

    The aim was to compare the enamel surface roughness (ESR) and absolute depth profile (ADP) (mean peak-to-valley height) by atomic force microscopy (AFM) before and after using four different phosphoric acids. A total of 160 enamel samples from 40 upper premolars were prepared. The inclusion criterion was that the teeth have healthy enamel. Exclusion criteria included any of the following conditions: facial restorations, caries lesions, enamel hypoplasia and dental fluorosis. Evaluations of the ESR and ADP were carried out by AFM. The Mann-Whitney U-test was used to compare continuous variables and the Wilcoxon test was used to analyze the differences between before and after etching. There were statistically significant differences (P roughness and absolute depth before and after using four different phosphoric acids in healthy enamel; Etch-37 and Scotchbond Etching Gel showed higher profiles after etching (P roughness and ADP before and after using four different phosphoric acids in healthy enamel. However, consistently Etch-37 and Scotchbond Etching Gel showed the highest increase regarding the ESR and ADP after etching healthy enamel. AFM was a useful tool to study site-specific structural topography changes in enamel after phosphoric acid etching.

  12. Calculation of Spectral Parameters for Doped/Codoped MWO4 (M = Ba2+/Ca2+) Phosphors

    Science.gov (United States)

    Ambast, A. K.; Sharma, S. K.

    2017-08-01

    We report the spectral parameters of Dy3+-doped and Sr2+/K+-codoped MWO4 (M = Ba2+/Ca2+) tungstate phosphors synthesized by solid-state reaction route. The structural and optical properties were investigated by x-ray diffraction (XRD) analysis, photoluminescence (PL) measurements, and ultraviolet-visible-near infrared spectroscopy. The XRD results indicate tetragonal structure of the phosphors in space group I4 1 / a. The PL spectra show blue and yellow emission at 489 nm and 577 nm, respectively, on excitation at wavelength of 350 nm. The diffuse reflectance spectra reveal bandgap values for the phosphors in the range from 4.24 eV to 5.7 eV. Judd-Ofelt theory was used to calculate the oscillator strength from the excitation spectra of the phosphors. The intensity parameters ( Ω 2, Ω 4, and Ω 6) were used to calculate many radiative parameters such as the radiative transition probabilities ( A R), radiative lifetime ( τ R), branching ratio ( β R), stimulated emission cross-section [ σ( λ p)], and quantum efficiency ( η) for certain excited states of Dy3+ ion.

  13. Study on oxide resistance of long persistent phosphor SrAl2O4: Eu, Dy

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The heat-treated temperature and preservative time influence on oxide resistance of SrAl2O4 :Eu2+ ,Dy3+ in high temperature atmosphere were studied in this paper. The result showed that oxide resistance was improved obviously by phosphor particles coated SiO2. The reason for the coating to craze above 900℃ was also analyzed.

  14. Phosphoric acid doped imidazolium polysulfone membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Qingfeng; Jensen, Jens Oluf

    2012-01-01

    A novel acid–base polymer membrane is prepared by doping of imidazolium polysulfone with phosphoric acid for high temperature proton exchange membrane fuel cells. Polysulfone is first chloromethylated, followed by functionalization of the chloromethylated polysulfone with alkyl imidazoles i.e. me...

  15. A measurement of the fast luminescent decay time of P-15 phosphor.

    Science.gov (United States)

    Sutton, J. F.

    1972-01-01

    The fast decay time of a 3900-A spectral component of an electron-beam excited P-15 phosphor has been measured using a delayed coincidence technique. The result, 1.04 nsec plus or minus nearly 2%, is in good agreement with previous estimates.

  16. Cooperative catalysis by palladium and a chiral phosphoric acid: enantioselective amination of racemic allylic alcohols.

    Science.gov (United States)

    Banerjee, Debasis; Junge, Kathrin; Beller, Matthias

    2014-11-24

    Cooperative catalysis by [Pd(dba)2] and the chiral phosphoric acid BA1 in combination with the phosphoramidite ligand L8 enabled the efficient enantioselective amination of racemic allylic alcohols with a variety of functionalized amines. This catalytic protocol is highly regio- and stereoselective (up to e.r. 96:4) and furnishes valuable chiral amines in almost quantitative yield.

  17. Synthesis and study on the luminescence properties of cadmium borate phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Annalakshmi, O. [Radiological Safety Division, Indira Gandhi Center for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Jose, M.T., E-mail: mtjosein@yahoo.co.in [Radiological Safety Division, Indira Gandhi Center for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Venkatraman, B. [Radiological Safety Division, Indira Gandhi Center for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Amarendra, G. [Materials Physics Division, Indira Gandhi Center for Atomic Research, Kalpakkam 603102, Tamilnadu (India)

    2014-02-01

    Highlights: • Cadmium borate synthesized by solid state sintering technique. • Neutron sensitivity of the material ten times that of TLD-600. • Gamma sensitivity is found to be twice that of TLD-100. • Gamma response is linear from 0.1 to 10{sup 3} mGy. - Abstract: Cadmium borate compound prepared through wet chemical reaction from the starting chemicals followed by high temperature solid state synthesis below the melting point to get the final TL phosphor powder. Phase purity and bond details of cadmium borate crystals are characterized using X-ray diffraction technique and infrared spectroscopy. Feasibility of these materials for radiation dosimetry applications was studied after gamma and neutron irradiation. Gamma irradiation of undoped phosphors show a single peak around 185 °C whereas doping with gadolinium and silver, new more intense peak observed at 290 °C. Irradiation to thermal neutrons revealed single peak around 170 °C for all the phosphors. TL emission spectra and photoluminescence (PL) studies were also carried out on the phosphors. These borate materials are found to be highly sensitive to neutrons and hence can be used for neutron detection. Neutron sensitivity of the material is about ten times that of TLD-600.

  18. Metallurgical investigations of dry sliding surface layer in phosphorous iron/steel friction pairs

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Surface layer behaviors of composition concentration and micro-hardness were inves-tigated on phosphorous cast irons after dry sliding. The experimental results indicate that thehardness and chemical composition unevenly distribute in the surface layer. The sliding conditionand microstructure of the pin specimen have greatly effects on the distributions.

  19. Recovering Y and Eu from Waste Phosphors Using Chlorination Roasting—Water Leaching Process

    Directory of Open Access Journals (Sweden)

    Mingming Yu

    2016-10-01

    Full Text Available Recovering Y and Eu from waste phosphors using chlorination roasting followed by a water leaching process was investigated in this study. Firstly, by chlorination roasting and water leaching, Y and Eu elements present in waste phosphors were efficiently extracted into a leach solution. Secondly, the majority of the impurities in the solution can be removed by adjusting the pH to 4.5 using a Na2S and NH3·H2O solution. Thirdly, the rare earths can be precipitated afterwards by adding a H2C2O4 solution and adjusting the pH to 2.0. Then rare earth oxides (REOs can be obtained after calcining at 800 °C for 1 h. The characterization study of the waste phosphors and the rare earth oxide products was performed by XRD, XRF, and SEM-EDS analysis to determine the phase and morphological features. Influences of the factors, such as roasting temperatures and time, the addition of ammonium chloride on the roasting of waste phosphors, as well as the pH and the amount of oxalates on the precipitation of Y and Eu, were investigated. The maximum grade (99.84% of mixed rare earth oxides and recovery rate (87.35% of Y and Eu were obtained at the optimized conditions.

  20. Physicochemical properties of phosphoric acid doped polybenzimidazole membranes for fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Bach, Anders;

    2006-01-01

    Polybenzimidazole (PBI) membranes have been prepared with different molecular weights. The water and acid swelling, mechanical strength,gas permeability and proton conductivity were studied for the pristine and acid doped PBI membranes. When doped with 5 mol of phosphoric acid per mole repeat uni...

  1. Thermoluminescence characterization of Dy(3+) -activated Mg₅ (BO₃ )₃ F low Z(eff) phosphor.

    Science.gov (United States)

    Wani, Javaid A; Dhoble, N S; Dhoble, S J

    2013-01-01

    Thermoluminescence characteristics of Dy(3+) -activated Mg₅ (BO₃ )₃ F low Z(eff) phosphor are described. The Mg₅ (BO₃ )₃ F phosphor doped with Dy(3+) as activator was prepared by the modified solid-state reaction. Formation of the compound was confirmed by use of X-ray powder diffraction. The X-ray powder diffraction pattern of the as-prepared compound shows a good match with the available JCPDS data. The γ-irradiated Mg₅ (BO₃ )₃ F:Dy(3+) phosphor shows a simple glow curve peaking at about 148°C indicating that only one type of trap is being activated within a particular temperature range. The kinetic parameters, including activation energy and frequency factor were determined using Chen's method. The activation energy and frequency factors were 0.75 eV and 4.508 × 10(9) /s respectively. The Z(eff) ofMg₅ (BO₃ )₃ F:Dy(3+) phosphor was 9.84.

  2. Electrical-thermal-luminous-chromatic model of phosphor-converted white light-emitting diodes

    NARCIS (Netherlands)

    Ye, H.; Koh, S.W.; Yuan, C.; Zeijl, H. van; Gielen, A.W.J.; Lee, S.W.R.; Zhang, G.

    2014-01-01

    The drive of increased electrical currents to achieve high luminous output for phosphor-converted white light-emitting diodes (PW-LED) has led to a series of thermal problems. The light performance of PW-LED is affected by the heat generated by the two major sources in a package/module: chip(s) and

  3. A novel orange phosphor of Eu 2+-activated calcium chlorosilicate for white light-emitting diodes

    Science.gov (United States)

    Ding, Weijia; Wang, Jing; Zhang, Mei; Zhang, Qiuhong; Su, Qiang

    2006-11-01

    Novel orange phosphor of Eu 2+-activated calcium chlorosilicate was synthesized at 1273 K by conventional solid-state reactions under reductive atmosphere and investigated by means of photoluminescence excitation, diffuse reflectance and emission spectroscopies. These results show that this phosphor can be efficiently excited by the incident light of 300-450 nm, well matched with the emission band of 395 nm-emitting InGaN chip, and emits an intense orange light peaking at 585 nm. By combining this phosphor with a 395 nm-emitting InGaN chip, an intense orange light-emitting diode (LED) was fabricated. Under 20 mA forward-bias current, its CIE chromaticity coordinates are (0.486, 0.446). The dependence of as-fabricated orange LED on forward-bias current indicates that it shows excellent chromaticity stability and luminance saturation. These results show that this Eu 2+-activated calcium chlorosilicate is a promising orange-emitting phosphor for near-ultraviolet (UV) InGaN-based white LED.

  4. Upconversion emission study of Er3+ doped CaMoO4 phosphor

    Science.gov (United States)

    Sinha, Shriya; Mahata, Manoj Kumar; Rai, V. K.; Kumar, Kaushal

    2016-05-01

    The infrared to visible upconversion emission in Er3+ doped CaMoO4 phosphor has been investigated upon 980 nm diode laser excitation. The X-ray dffraction analysis reveals well crystalline nature and tetragonal phase structure of the prepared phosphor annealed at 800 °C. The Er3+ doped CaMoO4 phosphor has shown intense green upconversion emission upon 980 nm didode laser excitation. The green emission bands at 530 nm and 552 nm corresponds to the 2H11/2→4I15/2 and 4S3/2→4I15/2 electronic transitions, respectively of Er3+ ion. The very weak red emission band around 656 nm is assigned to the 4F9/2→4I15/2 transition of Er3+ ion. The CIE color coordinate exhibits the emission color in intense green region, indicating the use of present phosphor in display device applications.

  5. Phosphorous and proton spectroscopy in relation to near incarceration and incarceration of the human brain

    DEFF Research Database (Denmark)

    Garde, K; Mortensen, A C; Toft, P B

    1994-01-01

    incarceration, the energy supply to the brain was substantial. 1H-MRS of the 3rd patient showed massive lactate concentration, and 31P-MRS revealed the total absence of high-energy phosphorous compounds leaving only one single peak of inorganic phosphate, indicating irreversible brain death....

  6. Brewer’s Spent Grain Valorization Using Phosphoric Acid Pretreatment for Second Generation Bioethanol Production

    DEFF Research Database (Denmark)

    Romero, I.; Ruiz, E.; Cara, C.

    Brewer’s spent grain constitutes a byproduct of beer making process yearly generated in big amounts and lacking of economic feasible applications. This lignocellulosic residue was characterized and pretreated by dilute phosphoric acid according to a rotatable central composite design to evaluate ...

  7. Preparation and Photoluminescence of Sm (3+) Doped YAlO 3 Phosphor.

    Science.gov (United States)

    Baig, Huma Nazli; Saluja, Jagjeet Kaur; Harnath, D; Prasad, A S Sai; Murthy, K V R

    2016-05-01

    YAlO3: Sm(3+) phosphor has been synthesized by the solid state reaction method with calcium flouride used as a flux. The resulting YAlO3: Sm(3+) phosphor was characterized by X-ray diffraction (XRD) technique, Fourier transmission infrared spectroscopy (FTIR), photoluminescence . . PL excitation spectrum was found at 254,332,380,400,407, 603 and 713 nm. Under excitation of UV(713 nm) YAlO3: Sm(3+) (0-3 %) broad band emission were observed from 400 to 790 nm with a maximum around 713 nm of YAlO3 host lattice accompanied by weak emission of Sm(3+) ((4)G5/2 - (6)H5/2, (6)H7/2,(6)H9/2) transitions. The results of the XRD show that obtained YAlO3: Sm(3+) phosphor has a orthorhombic structure. The study suggested that Sm(3+) doped phosphors are potential luminescence material for laser diode pumping and inorganic scintillators.

  8. Luminescence and color center distributions in K3YB6O12:Ce3+ phosphor

    Science.gov (United States)

    Yang, Li; Wan, Yingpeng; Weng, Honggen; Huang, Yanlin; Chen, Cuili; Seo, Hyo Jin

    2016-08-01

    Polycrystalline Ce3+-doped K3YB6O12 (1-14 mol%) phosphors were prepared by facile chemical sol-gel synthesis. The phase formation of the phosphors was confirmed by x-ray powder diffraction (XRD) analysis. The photoluminescence excitation spectra (PLE), emission spectra (PL) and the luminescence decay curves were tested. Under the near-UV light, the phosphors present the emission from blue color to yellowish green due to the allowed 4f -5d transitions of Ce3+ ions. The absolute quantum efficiency (QE) of K3YB6O12:Ce3+ can reach 53% under the excitation of near-UV light. The luminescence thermal quenching of the phosphor was investigated by the temperature-dependent spectra. The crystallographic site of Ce3+ ions in the lattice was identified and discussed on the basis of luminescence characteristics and structural data. There is only one isolated Ce3+ center occupying the Y(II) sites in the lightly doped samples presenting a typical doublet emission profile. While the Ce3+ multi-centers could be created with the enhancement of the doping levels, which could induce the distinct red-shift of the spectra due to the dipole-dipole interactions. The result in this work could be useful for the further investigation of other rare earth ions in this host.

  9. Local structure of the Ce3+ ion the yellow emitting phosphor YAG:Ce

    NARCIS (Netherlands)

    Ghigna, P.; Pin, S.; Ronda, C.; Speghini, A.; Piccinelli, F.; Bettinelli, M.

    2011-01-01

    The local structure of the Ce3+ ion in the yellow emitting YAG:Ce phosphor has been studied by Extended X-ray Absorption Fine Structurespectroscopy in the 300−20 K temperature range. It has evidenced that the dopant Ce3+ replaces Y3+ in the garnet structure, giving rise to a significant expan

  10. Characteristics of up-conversion phosphor prepared by metal-organic decomposition method

    Science.gov (United States)

    Nonaka, Toshihiro; Kanamori, Tsubasa; Ohyama, Keito; Yamamoto, Shin-Ichi

    2015-03-01

    Oxides can be formed from many materials by air sintering after coating a substrate with a metal-organic decomposition (MOD) solution. This enables the preparation of thin films by simple processes such as spin coating. The up-conversion (UC) phosphor produced by the MOD method has a multifunctional potential for use in applications such as displays and solid-state lighting. In this study, a simple TiO2-ZnO mixed oxide system was examined for use as the base material and host crystal of rare-earth (RE) elements for UC phosphor. The maximum emission luminescence of the UC phosphor was obtained when the mixing ratios of the base materials TiO2 : ZnO and additive materials Yb2O3 : Er2O3 were 1:1 and 0.06:0.06, respectively. When the mixing ratio of the phosphor, Ti : Zn : Yb : Er, was 1:1:0.06:0.06, 550 nm green and 650 nm red emissions were produced. The UC emission intensity could be controlled by varying the mixing ratio of the rare-earth materials.

  11. Luminescence studies of rare earth doped yttrium gadolinium mixed oxide phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Som, S.; Choubey, A. [Department of Applied Physics, Indian School of Mines, Dhanbad, Jharkhand 826004 (India); Sharma, S.K., E-mail: sksharma_ism@yahoo.co.in [Department of Applied Physics, Indian School of Mines, Dhanbad, Jharkhand 826004 (India)

    2012-09-01

    This paper reports the photoluminescence and thermoluminescence properties of gamma ray induced rare earth doped yttrium gadolinium mixed oxide phosphor. The europium (Eu{sup 3+}) was used as rare earth dopant. The phosphor was prepared by chemical co-precipitation method according to the formula (Y{sub 2-x-y}Gd{sub x}) O{sub 3}: Eu{sub y}{sup 3+} (x=0.5; y=0.05). The photoluminescence emission spectrum of the prepared phosphor shows intense peaks in the red region at 615 nm for {sup 5}D{sub 0}{yields}{sup 7}F{sub 2} transitions and the photoluminescence excitation spectra show a broad band located around 220-270 nm for the emission wavelength fixed at 615 nm. The thermoluminescence studies were carried out after irradiating the phosphor by gamma rays in the dose range from 100 Gy to 1 KGy. In the thermoluminescence glow curves, one single peak was observed at about 300 Degree-Sign C of which the intensity increases linearly in the studied dose range of gamma rays. The glow peak was deconvoluted by GlowFit program and the kinetic parameters associated with the deconvoluted peaks were calculated. The kinetic parameters were also calculated by various glow curve shape and heating rate methods.

  12. Luminescence studies of rare earth doped yttrium gadolinium mixed oxide phosphor

    Science.gov (United States)

    Som, S.; Choubey, A.; Sharma, S. K.

    2012-09-01

    This paper reports the photoluminescence and thermoluminescence properties of gamma ray induced rare earth doped yttrium gadolinium mixed oxide phosphor. The europium (Eu3+) was used as rare earth dopant. The phosphor was prepared by chemical co-precipitation method according to the formula (Y2-x-yGdx) O3: Euy3+ (x=0.5; y=0.05). The photoluminescence emission spectrum of the prepared phosphor shows intense peaks in the red region at 615 nm for 5D0→7F2 transitions and the photoluminescence excitation spectra show a broad band located around 220-270 nm for the emission wavelength fixed at 615 nm. The thermoluminescence studies were carried out after irradiating the phosphor by gamma rays in the dose range from 100 Gy to 1 KGy. In the thermoluminescence glow curves, one single peak was observed at about 300 °C of which the intensity increases linearly in the studied dose range of gamma rays. The glow peak was deconvoluted by GlowFit program and the kinetic parameters associated with the deconvoluted peaks were calculated. The kinetic parameters were also calculated by various glow curve shape and heating rate methods.

  13. Synthesis and photoluminescence of BCNO/SiO{sub 2} nanocomposite phosphor materials

    Energy Technology Data Exchange (ETDEWEB)

    Faryuni, Irfana Diah; Nuryadin, Bebeh W. [Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10, Bandung 40132 (Indonesia); Iskandar, Ferry, E-mail: ferry@fi.itb.ac.id [Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10, Bandung 40132 (Indonesia); Abdullah, Mikrajuddin; Khairurrijal [Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10, Bandung 40132 (Indonesia); Ogi, Takashi; Okuyama, Kikuo [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima 739-8527 (Japan)

    2014-04-15

    A BCNO/SiO{sub 2} phosphor was successfully synthesized using a facile process at relatively low temperature (700–850 °C) and atmospheric pressure. The phosphors were prepared from precursors containing boric acid, urea, poly(ethylene glycol) (PEG) and SiO{sub 2} nanoparticles. The sample exhibited a single, distinct and broad photoluminescence (PL) emission band, the color of which varied from blue (480 nm) to green (522 nm). Adding SiO{sub 2} nanoparticles into the precursor homogenizes the spatial distribution of luminescent centers throughout the sample and increases the quantum yield up to 6-fold (for 3 wt% of SiO{sub 2} nanoparticles) compared with that of the sample without SiO{sub 2} nanoparticles. The BCNO/SiO{sub 2} nanocomposite has potential applications in white LEDs. -- Highlights: • A BCNO/SiO{sub 2} phosphor shown a single, distinct and broad photoluminescence (PL) emission band from blue (480 nm) to green (522 nm). • SiO{sub 2} nanoparticles increase the BCNO phosphor's quantum yield up to 6-fold. • Effect of the SiO{sub 2} mass fraction on the luminescence properties of BCNO/SiO{sub 2} was investigated.

  14. Evaluation of a new phosphor plate technology for neonatal portable chest radiographs.

    Science.gov (United States)

    Cohen, Mervyn; Corea, Donald; Wanner, Matthew; Karmazyn, Boaz; Gunderman, Richard; Applegate, Kimberly; Jennings, Samuel G

    2011-02-01

    The aim of this study was to evaluate a new thick-needle phosphor plate for computed radiography. Two studies were performed. Patients acted as their own controls. In the first study, old powder and new needle phosphor plate technologies were compared. Twenty infants were identified who had undergone chest x-rays with both systems within 3 days of each other. Exposure factors were constant. In the second study, standard and reduced exposure techniques (tube current-time product reduced by 20%) using the needle phosphor technology were compared. Twenty babies who had been imaged with both standard and reduced exposures within 3 days of each other were evaluated. There was a significant preference for images obtained with the new needle phosphor technology compared with the older powder technology (P exposure, images were better with the new technology. Using the new plate technology, dose can be decreased by ≥20%. Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.

  15. Elementary results on the dosimetric properties of SrSO4:Eu2+ phosphor

    Directory of Open Access Journals (Sweden)

    Chetan B. Palan

    2015-12-01

    Full Text Available A polycrystalline sample of SrSO4:Eu2+ phosphor has been successfully synthesized using the co-precipitation method and studied for its luminescence properties. The phosphor showed rather high optical stimulated luminescence (OSL sensitivity which was about 75% of that for the commercially available α-Al2O3:C phosphor (TLD-500. The continuous wave (CW-OSL curve exhibited three components having photoionization cross-sections of 1.78۰10–17, 7.70۰10–17 and 17.69۰10–17cm2, respectively. The thermal luminescence (TL sensitivity was about 100 times higher than that for TLD-500. The kinetic parameters for TL curve such as activation energy and frequency factor were calculated using peak shape treatment. OSL components were determined from CW and linear modulated (LM-OSL data. The minimum detectable dose was found to be 11.6mGy with 3σ of background. Also reusability studies showed that it was possible to reuse the phosphor for 10 cycles without change in the OSL output. In the TL mode the dose-response was nearly linear in the range of measurement (20–400mGy, and fading was 40% in 72h. Photoluminescence spectra of SrSO4:Eu2+ exhibited emission in the near-UV region at 254, 315, and 323nm when excited with an UV source.

  16. PREPARATION AND PROPERTIES OF ALKALI-ACTIVATED CEMENT CONTAINING PHOSPHOROUS SLAG AND FLY ASH

    Directory of Open Access Journals (Sweden)

    Duo You

    2016-03-01

    Full Text Available Phosphorous slag is an industrial waste which potentially pollutes environments. The aim of the present work is to use phosphorous slag as a raw material to produce alkali-activated cement. The influence of mix proportion of phosphorous slag and fly ash, alkali content and modulus of water glass on the properties of alkali-activated phosphorous slag and fly ash cement (AA-PS-FA-C was studied. The results show that AA-PS-FA-C with normal setting performance and desirable mechanical properties can be prepared using water glass as the activator. Changing the fly ash content in the range of 0-40 wt% has only a small influence on the setting time of AA-PS-FA-C. The strengths significantly decrease when the fly ash content exceeds 30 wt%. The carbonation resistance of AA-PS-FA-C is similar to that of ordinary Portland cement (OPC, while the frost resistance is much better. The hardened paste of AA-PS-FA-C is much more compact than OPC paste.

  17. Preparation and Characterization of UV Emitting Fluoride Phosphors for Phototherapy Lamps

    Science.gov (United States)

    Belsare, P. D.; Moharil, S. V.; Joshi, C. P.; Omanwar, S. K.

    2011-10-01

    The use of ultraviolet radiation for the treatment of various skin diseases is well known for long time. Phototherapy employs ultraviolet-blue radiation to cure skin diseases. The basis of phototherapy is believed to be the direct interaction of light of certain frequencies with tissue to cause a change in immune response. Currently dermatologists use UV lamps having specific emissions in UV region for treating various skin diseases. The treatment of skin diseases using artificial sources of UV radiation is now well established and more than 50 types of skin diseases are treated by phototherapy. This is an effective treatment for many skin disorders, such as psoriasis, vitiligo, ofujis disease, morphea , scleroderma, cutaneous T-cell lymphoma, lupus erythematosus, hyperbilirubinemia commonly known as infant jaundice, acne vulgaris, This paper reports photoluminescence properties of UV emitting fluoride phosphors prepared by wet chemical method. Emission characteristics of these phosphors are found similar to those of commercial UV lamp phosphors with comparable intensities. The usefulness of UV emitting fluoride phosphor is discussed in the paper.

  18. Tuning transport selectivity of ionic species by phosphoric acid gradient in positively charged nanochannel membranes.

    Science.gov (United States)

    Yang, Meng; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Fan, Xin; Liu, Wei; Liu, Xizhen; Liu, Jianbo; Huang, Jin

    2015-02-03

    The transport of ionic species through a nanochannel plays important roles in fundamental research and practical applications of the nanofluidic device. Here, we demonstrated that ionic transport selectivity of a positively charged nanochannel membrane can be tuned under a phosphoric acid gradient. When phosphoric acid solution and analyte solution were connected by the positively charged nanochannel membrane, the faster-moving analyte through the positively charged nanochannel membrane was the positively charged dye (methylviologen, MV(2+)) instead of the negatively charged dye (1,5-naphthalene disulfonate, NDS(2-)). In other words, a reversed ion selectivity of the nanochannel membranes can be found. It can be explained as a result of the combination of diffusion, induced electroosmosis, and induced electrophoresis. In addition, the influencing factors of transport selectivity, including concentration of phosphoric acid, penetration time, and volume of feed solution, were also investigated. The results showed that the transport selectivity can further be tuned by adjusting these factors. As a method of tuning ionic transport selectivity by establishing phosphoric acid gradient, it will be conducive to improving the separation of ionic species.

  19. Modification of vital wheat gluten with phosphoric acid to produce high free-solution capacity

    Science.gov (United States)

    Wheat gluten reacts with phosphoric acid to produce natural superabsorbent gels. The gel properties are defined by Fourier Transform Infra-red (FTIR) spectroscopy, 2-dimensional gel electrophoresis (2DE), and uptake of water, salt solutions, and aqueous ethanol. Temperatures above 120'C and dry cond...

  20. Phosphoric acid fuel cell power plant system performance model and computer program

    Science.gov (United States)

    Alkasab, K. A.; Lu, C. Y.

    1984-01-01

    A FORTRAN computer program was developed for analyzing the performance of phosphoric acid fuel cell power plant systems. Energy mass and electrochemical analysis in the reformer, the shaft converters, the heat exchangers, and the fuel cell stack were combined to develop a mathematical model for the power plant for both atmospheric and pressurized conditions, and for several commercial fuels.

  1. Program Trainer for Operator of Phosphoric Acid production by Wet-Process

    Directory of Open Access Journals (Sweden)

    Vladimir А. Krivonosov

    2013-01-01

    Full Text Available This article considers the major problems of operator of phosphoric acid production by wet-process during production control, develops program trainer, enabling to speed up the process of operators training, promote their professional qualifications and the production control

  2. Modification of vital wheat gluten with phosphoric acid to produce high free solution capacity

    Science.gov (United States)

    Wheat gluten reacts with phosphoric acid in the presence of urea to produce natural superabsorbent gels. Fourier Transform Infra-red (FT-IR) spectroscopy and two-dimensional gel electrophoresis (2DE) reveal chemical changes from the reaction. Temperatures above 120°C and dry conditions create the op...

  3. Manual of phosphoric acid fuel cell power plant cost model and computer program

    Science.gov (United States)

    Lu, C. Y.; Alkasab, K. A.

    1984-01-01

    Cost analysis of phosphoric acid fuel cell power plant includes two parts: a method for estimation of system capital costs, and an economic analysis which determines the levelized annual cost of operating the system used in the capital cost estimation. A FORTRAN computer has been developed for this cost analysis.

  4. Survey on aging on electrodes and electrocatalysts in phosphoric acid fuel cells

    Science.gov (United States)

    Stonehart, P.; Hochmuth, J.

    1981-01-01

    The processes which contribute to the decay in performance of electrodes used in phosphoric acid fuel cell systems are discussed. Loss of catalytic surface area, corrosion of the carbon support, electrode structure degradation, electrolyte degradation, and impurities in the reactant streams are identified as the major areas for concern.

  5. Current legal and institutional issues in the commercialization of phosphoric acid fuel cells

    Science.gov (United States)

    Nimmons, J. T.; Sheehy, K. D.; Singer, J. R.; Gardner, T. C.

    1982-01-01

    Legal and institutional factors affecting the development and commercial diffusion of phosphoric acid fuel cells are assessed. Issues for future research and action are suggested. Perceived barriers and potential opportunities for fuel cells in central and dispersed utility operations and on-site applications are reviewed, as well as the general concept of commercialization as applied to emerging energy technologies.

  6. Synthesis and characterization of nano-sized YAG∶Ce,Sm spherical phosphors

    Institute of Scientific and Technical Information of China (English)

    SUN Haiying; ZHANG Xiyan; BAI Zhaohui

    2013-01-01

    YAG:Ce,Sm spherical phosphors were synthesized by malic acid sol-gel method.The formation process of crystalline was characterized by X-ray diffraction (XRD) technique.The influence of Sm3+ doping on the luminescent intensity and the morphology of phosphors were studied by fluorescence spectrum and scanning electron microscopy (SEM) techniques,respectively.The results indicated that the size of spherical powders was about 100 nm calcined at 1200 ℃ for 3 h.The emission spectra of phosphors showed gradual red-shift from 525 to 540 nm with the increase of doping concentration of Sm3+ ion.A broadband emission spectrum of Ce3+ ion appeared at 540 nm,and a series of emission peaks corresponding to the 4G5/2→6HJ transition of Sm3+ ion also appeared at 617 nm with the doping of Sm3+.The red component of YAG:Ce phosphors increased with the doping of Sm3+.

  7. Theoretical study on the acidities of chiral phosphoric acids in dimethyl sulfoxide: hints for organocatalysis.

    Science.gov (United States)

    Yang, Chen; Xue, Xiao-Song; Jin, Jia-Lu; Li, Xin; Cheng, Jin-Pei

    2013-07-19

    The pKa values of 41 chiral phosphoric acid-family catalysts in DMSO were predicted using the SMD/M06-2x/6-311++G(2df,2p)//B3LYP/6-31+G(d) method for the first time. The study showed that the calculated pKa's range from -4.23 to 6.16 for absolute pKa values and from -4.21 to 6.38 for relative pKa values. Excellent agreement between the calculated and experimental pKa's was achieved for the few available cases (to a precision of around 0.4 pKa unit), indicating that this strategy may be suitable for calculating highly accurate pKa's. A good linear correlation between the pKa's for 3 and 3' disubstituted phenyl BINOL phosphoric acids and the Hammett constants was obtained. The relationship between the acidities of phosphoric acid catalysts and their reaction activity and selectivity was also discussed. Knowledge of the pKa values of phosphoric acids should be of great value for the understanding of chiral Brønsted acid-catalyzed reactions and may aid in future catalyst design.

  8. Enantioselective BINOL-phosphoric acid catalyzed Pictet-Spengler reactions of N-benzyltryptamine

    NARCIS (Netherlands)

    Sewgobind, N.V.; Wanner, M.J.; Ingemann, S.; de Gelder, R.; van Maarseveen, J.H.; Hiemstra, H.

    2008-01-01

    Optically active tetrahydro-beta-carbolines were synthesized via an (R)-BINOL-phosphoric acid-catalyzed asynunetric Pictet-Spengler reaction of N-benzyltryptamine with a series of aromatic and aliphatic aldehydes. The tetrahydro-beta-carbolines were obtained in yields ranging from 77% to 97% and wit

  9. Phosphoric acid doped polysulfone membranes with aminopyridine pendant groups and imidazole cross-links

    DEFF Research Database (Denmark)

    Hink, Steffen; Elsøe, Katrine; Cleemann, Lars Nilausen;

    2015-01-01

    Udel polysulfone based membranes with 4-aminopyridine pendant groups and cross-linking imidazole units are synthesized in a simple two step reaction. The ratio of 4-aminopyridine and imidazole is varied and the materials are extensively characterized. The average phosphoric acid uptake (in 85 wt...

  10. Dualistic temperature sensing in Er3 +/Yb3 + doped CaMoO4 upconversion phosphor

    Science.gov (United States)

    Sinha, Shriya; Mahata, Manoj Kumar; Kumar, Kaushal; Tiwari, S. P.; Rai, V. K.

    2017-02-01

    Temperature sensing performance of Er3 +/Yb3 + doped CaMoO4 phosphor prepared via polyol method is reported herein. The X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy are done to confirm the phase, structure and purity of the synthesized phosphor. The infrared to green upconversion emission is investigated using 980 nm diode laser excitation along with its dependence on input pump power and external temperature. The temperature dependent fluorescence intensity ratio of two upconversion emission bands assigned to 2H11/2 → 4I15/2 (530 nm) and 4S3/2 → 4I15/2 (552 nm) transitions has shown two distinct slopes in the studied temperature range - 300 to 760 K and therefore, dual nature of temperature sensitivity is observed in this phosphor. This phenomenon in rare earth doped materials is either scarcely reported or overlooked. The material has shown higher sensitivity in the high temperature region (535 K < T < 760 K) with a maximum of 7.21 × 10- 3 K- 1 at 535 K. The results indicate potential of CaMoO4: Er3 +/Yb3 + phosphor in high temperature thermometry.

  11. Wet chemical synthesis of Eu{sup 2+} activated fluoro-elpasolite phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Vartika S. [Department of Physics, R.T.M. Nagpur University, Nagpur 440010 (India); Joshi, C.P. [Physics Department, Shri Ramdeobaba K.N. Engineering College, Katol Road, Nagpur 440 013 (India); Muthal, P.L.; Dhopte, S.M. [National Environmental Engineering Research Institute, Nehru Marg, Nagpur (India); Moharil, S.V., E-mail: svmoharil@yahoo.com [Department of Physics, R.T.M. Nagpur University, Nagpur 440010 (India)

    2014-06-25

    Highlights: • First report on precipitation synthesis of elpasolite. • First report on Eu{sup 2+} emission in K{sub 2}NaAlF{sub 6} and K{sub 2}LiAlF{sub 6} elpasolites. • Strong Eu{sup 2+} emission in K{sub 2}NaAlF{sub 6} and K{sub 2}LiAlF{sub 6} observed. • UV emission comparable to that of commercial phosphor (Sylvania 2052). - Abstract: A simple precipitation synthesis of fluoro-elpasolites is reported for the first time. X-ray diffraction results show phase formation for K{sub 2}NaAlF{sub 6} and K{sub 2}LiAlF{sub 6} precipitated from aqueous solutions. Intense Eu{sup 2+} emission in both the hosts is also reported for the first time. K{sub 2}NaAlF{sub 6} exhibits both line and band emissions which are attributed to Eu{sup 2+} at K{sup +} and Na{sup +} sites, respectively. Only line emission is observed for K{sub 2}LiAlF{sub 6}. The emission is very strong, intensity being comparable to that of a commercial UV lamp phosphor. The photoluminescence spectra are explained on the basis of the known energy level scheme for Eu{sup 2+}. It is suggested that fluoro elpasolite phosphors obtained by the new route can be useful for making further studies on these phosphors.

  12. Lanthanide doped BaTiO{sub 3}−SrTiO{sub 3} solid-solution phosphors: Structure, optical spectroscopy and upconverted temperature sensing behavior

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Daqin, E-mail: dqchen@hdu.edu.cn; Xu, Wei; Zhou, Yang; Chen, Yan, E-mail: chenyan@hdu.edu.cn

    2016-08-15

    Lanthanide doped Ba{sub 1-x}Sr{sub x}TiO{sub 3} (x = 0–1) solid-solution phosphors were successfully prepared by a conventional solid-state reaction. Using Eu{sup 3+} dopants as the structural probe, the variation of {sup 5}D{sub 0} → {sup 7}F{sub 2}/{sup 5}D{sub 0} → {sup 7}F{sub 1} emission intensity ratio with increase of Eu{sup 3+} content and the excitation-wavelength-dependent luminescence in the Ba{sub 1-x}Sr{sub x}TiO{sub 3} sample were demonstrated to be originated from the different emission behaviors of Eu{sup 3+} in Ba{sup 2+}/Sr{sup 2+} site and Ti{sup 4+} site. Furthermore, upconversion luminescence for the Yb{sup 3+}/Er{sup 3+} co-doped Ba{sub 1-x}Sr{sub x}TiO{sub 3} samples were investigated, and it was found that the emission intensity of Yb{sup 3+}/Er{sup 3+}: Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} phosphor was about 5 and 2 times as high as those of Yb{sup 3+}/Er{sup 3+}: BaTiO{sub 3} and Yb{sup 3+}/Er{sup 3+}: SrTiO{sub 3} ones. Using the investigated Yb{sup 3+}/Er{sup 3+}: Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} solid-solution as the optical thermometric medium, the temperature sensitivity was determined to be 0.76% K{sup −1} at the temperature of 610 K based on the temperature-dependent fluorescence intensity ratio of the thermally coupled {sup 2}H{sub 11/2} and {sup 4}S{sub 3/2} emitting-states of Er{sup 3+}. - Highlights: • Lanthanide doped Ba{sub 1-x}Sr{sub x}TiO{sub 3} (x = 0–1) solid-solutions were fabricated. • Excitation-wavelength-dependent Eu{sup 3+} emissions were recorded. • Enhanced Er{sup 3+} luminescence was realized by partial substitution of Ba{sup 2+} by Sr{sup 2+}. • T-sensitive emissions of two Er{sup 3+} thermally coupled states were observed. • The upconversion phosphor exhibited a high sensitivity of 0.76% K{sup −1}.

  13. Combustion synthesis of blue-emitting submicron CaAl4O7:Eu2+, Dy3+ persistence phosphor.

    Science.gov (United States)

    Yerpude, A N; Dhoble, S J

    2012-01-01

    Long persistence phosphor CaAl4O7:Eu(2+), Dy(3+) were prepared by a combustion method. The phosphors were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), decay time measurement techniques and photoluminescence spectra (PL). The CaAl4O7:Eu(2+), Dy(3+) phosphor showed a broad blue emission, peaking at 445 nm when excited at 341 nm. Such a blue emission can be attributed to the intrinsic 4f → 5d transitions of Eu(2+) in the host lattices. The lifetime decay curve of the Dy(3+) co-doped CaAl4O7:Eu(2+) phosphor contains a fast decay component and another slow decay one. Surface morphology also has been studied by SEM. The calculated CIE colour chromaticity coordinates was (0.227, 043). We have also discussed a possible long-persistent mechanism of CaAl4O7:Eu(2+), Dy(3+) phosphor. All the results indicate that this phosphor has promising potential for practical applications in the field of long-lasting phosphors for the purposes of sign boards and defence. Copyright © 2011 John Wiley & Sons, Ltd.

  14. Effect of phosphoric acid as a catalyst on the hydrothermal pretreatment and acidogenic fermentation of food waste.

    Science.gov (United States)

    Shen, Dongsheng; Wang, Kun; Yin, Jun; Chen, Ting; Yu, Xiaoqin

    2016-05-01

    The hydrothermal method was applied to food waste (FW) pretreatment with phosphoric acid as a catalyst. The content of soluble substances such as protein and carbohydrate in the FW increased after the hydrothermal pretreatment with phosphoric acid addition (⩽5%). The SCOD approached approximately 29.0g/L in 5% phosphoric acid group, which is almost 65% more than the original FW. The hydrothermal condition was 160°C for 10min, which means that at least 40% of energy and 60% of reaction time were saved to achieve the expected pretreatment effect. Subsequent fermentation tests showed that the optimal dosage of phosphoric acid was 3% with a VFA yield of 0.763g/gVSremoval, but the increase in salinity caused by phosphoric acid could adversely affect the acidogenesis. With an increase in the quantity of phosphoric acid, among the VFAs, the percentage of propionic acid decreased and that of butyric acid increased. The PCR-DGGE analysis indicated that the microbial diversity could decrease with excessive phosphoric acid, which resulted in a low VFA yield.

  15. Luminescence studies and infrared emission of erbium-doped calcium zirconate phosphor.

    Science.gov (United States)

    Tiwari, Neha; Dubey, Vikas

    2016-05-01

    The near-infrared-to-visible upconversion luminescence behaviour of Er(3+)-doped CaZrO3 phosphor is discussed in this manuscript. The phosphor was prepared by a combustion synthesis technique that is suitable for less-time-taking techniques for nanophosphors. The starting materials used for sample preparation were Ca(NO3)2.4H2O, Zr(NO3)4 and Er(NO3)2, and urea was used as a fuel. The prepared sample was characterized by X-ray diffraction (XRD). The surface morphology of prepared phosphor was determined by field emission gun scanning electron microscopy (FEGSEM). The functional group analysis was determined by Fourier transform infrared (FTIR) spectroscopy. All prepared phosphors with variable Er(3+) concentrations (0.5-2.5 mol%) were studied by photoluminescence analysis. It was found that the excitation spectra of the prepared phosphor showed a sharp excitation peak centred at 980 nm. The emission spectra with variable Er(3+) concentrations showed strong peaks in the 555 nm and 567 nm range, with a dominant peak at 555 nm due to the ((2)H(11/2),(4)S(3/2)) transition and a weaker transition at 567 nm associated with 527 nm. Spectrophotometric determination of the peak was evaluated by the Commission Internationale de I'Eclairage (CIE) method These upconverted emissions were attributed to a two-photon process. The excitation wavelength dependence of the upconverted luminescence, together with its time evolution after infrared pulsed excitation, suggested that energy transfer upconversion processes were responsible for the upconversion luminescence. The upconversion mechanisms were studied in detail through laser power dependence. Excited state absorption and energy transfer processes were discussed as possible upconversion mechanisms. The cross-relaxation process in Er(3+) was also investigated.

  16. Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

    Energy Technology Data Exchange (ETDEWEB)

    Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M. [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine); Sapsay, V.I.; Klymchuk, D.O. [M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 2 Tereshchenkivska St., 01601 Kyiv (Ukraine); Puziy, A.M., E-mail: alexander.puziy@ispe.kiev.ua [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Phosphoric acid activation results in formation of carbons with acidic surface groups. Black-Right-Pointing-Pointer Maximum amount of surface groups is introduced at impregnation ratio 1.25. Black-Right-Pointing-Pointer Phosphoric acid activated carbons show high capacity to copper. Black-Right-Pointing-Pointer Phosphoric acid activated carbons are predominantly microporous. Black-Right-Pointing-Pointer Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 Degree-Sign C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S{sub BET} = 2081 m{sup 2}/g, V{sub tot} = 1.1 cm{sup 3}/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

  17. Energy transfer induced improvement of luminescent efficiency and thermal stability in phosphate phosphor.

    Science.gov (United States)

    Zhao, Yun; Lin, Chun Che; Wei, Yi; Chan, Ting-Shan; Li, Guogang

    2016-02-22

    Ce3+ and Eu2+/Tb3+/Mn2+ ions codoped Ca6BaP4O17 (CBPO) phosphors have been prepared via a high-temperature solid state reaction. The structural refinement indicates that the as-prepared phosphors crystallize in monoclinic phase (C2/m) and there are two Ca sites and one Ba site in host lattice. The doping ions are determined to occupy Ca sites and the emission of Ce3+ and Eu2+ ions at different Ca sites were identified and discussed. Since bright blue and yellow emissions were observed from Ce3+and Eu2+ ions monodoped CBPO under n-UV excitation, respectively. They were codoped into the CBPO for designing energy transfer from Ce3+ to Eu2+ to improve the luminescence efficiency of Eu2+. In addition, Tb3+ ions were added into the CBPO:Ce3+ system for realizing highly efficient green emission. The energy transfer mechanisms from Ce3+ to Eu2+/Tb3+ ions were discussed. Interestingly, the incorporation of Mn2+ ions into the CBPO:Ce3+ system enhanced the blue emission of Ce3+ ions due to the modification of crystal lattice. Finally, the thermal stability of CBPO:Ce3+, Eu2+/Tb3+/Mn2+ phosphors were investigated systematically and corresponding mechanisms were proposed. Based on these results, the as-prepared CBPO:Ce3+, Eu2+/Tb3+/Mn2+ phosphors can act as potential blue, yellow, green, and emission-tunable phosphors for n-UV based white LEDs.

  18. White emission using mixtures of CdSe quantum dots and PMMA as a phosphor

    Science.gov (United States)

    Chung, Wonkeun; Park, Kwanhwi; Yu, Hong Jeong; Kim, Jihyun; Chun, Byung-Hee; Kim, Sung Hyun

    2010-02-01

    White light emitting diodes (LEDs) were fabricated using an InGaN 460 nm blue emission LED chip as the excitation source and CdSe quantum dots dispersed in PMMA as the phosphor. CdSe quantum dots were synthesized by the wet chemical method using CdO and Selenium powder as precursors. The three different size, 2.9, 3.4 and 4.3 nm in diameter, of CdSe quantum dots obtained using this method exhibited emission peaks at 555, 580 and 625 nm, respectively with a quantum yield of 10-30%. Mixed phosphors containing different weight ratio of CdSe and PMMA (1:0.1, 1:1, 1:5 and 1:10 wt%) were deposited on the LED chip to investigate the effects of different weight ratios of CdSe and PMMA on the performance of the white LEDs. The fabricated white LEDs that contained CdSe and PMMA weight ratio at 1:10 showed the best performance and the CIE color coordinates varied less with different applied currents. The luminous efficiency of single phosphor (580 nm CdSe) white LEDs was 5.62 lm/W with a CRI of 15.7, whereas the luminous efficiency of dual phosphors (555, 625 nm CdSe) white LEDs was 3.79 lm/W with a CRI of 61.4 at 20 mA. The CIE coordinates of single and dual phosphors white LEDs varied from (0.33, 0.28) to (0.29, 0.26) and from (0.39, 0.33) to (0.39, 0.32), respectively, when the working current ranged from 5 to 80 mA.

  19. Synthesis of yellow emitting bis-pyrimidine based purely organic phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinod, E-mail: vinod.phy@gmail.com [Department of Physics, University of the Free State, Bloemfontein, PO Box 9300 (South Africa); Gohain, Mukut [Department of Chemistry, University of the Free State, Bloemfontein, PO Box 9300 (South Africa); Kumar, Vijay [Department of Physics, University of the Free State, Bloemfontein, PO Box 9300 (South Africa); Van Tonder, Johannes H.; Bezuidenhoudt, Barend C.B. [Department of Chemistry, University of the Free State, Bloemfontein, PO Box 9300 (South Africa); Ntwaeaborwa, O.M. [Department of Physics, University of the Free State, Bloemfontein, PO Box 9300 (South Africa); Swart, Hendrik C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, Bloemfontein, PO Box 9300 (South Africa)

    2014-05-01

    Two organic phosphors 5,5'-(4-pyridinylmethylene)bis[1,3-dimethyl-2,4,6-(1H,3H,5H) -pyrimidinetrione] (BP) and 5,5'-(4-nitrophenylmethylene)bis[1,3-dimethyl-2,4,6-(1H,3H,5H) -pyrimidinetrione] (BP-NO{sub 2}) have been synthesized through a one pot reaction of N,N-dimethylbarbituric acid and pyridine aldehyde in acetonitrile at 80 °C. The synthesized phosphors were characterized by single-crystal X-ray crystallography, Fourier transform infrared spectroscopy, UV–vis spectroscopy, thermogravimetry analysis and photoluminescence (PL) spectroscopy. A broadband PL emission spectrum ranging from 400 to 800 nm was recorded from both phosphors. The BP showed a luminescence peak at ca. 560 nm (2.21 eV), while the BP-NO{sub 2} exhibited a peak at 590 nm (2.1 eV), which reflect pure yellow emissions. The optimized geometry of the phosphors has been studied with a quantum chemical approach using the density functional theory. The highest occupied and lowest unoccupied molecular orbitals are predicted from the calculations. - Highlights: • Two stable organic phosphors to bridge the yellow gap were synthesized. • PL emission spectrum ranging from 400 to 800 nm was recorded for both. • Luminescence peaks were obtained at 560 nm (2.21 eV) and 590 nm (2.1 eV). • The optimized geometry was obtained with a quantum chemical approach using DFT. • The HOMO and LUMO orbitals were predicted from the calculations.

  20. Luminescent Properties of BaMgAl10O17: Eu2+ Phosphors Coated with Y2SiO5

    Institute of Scientific and Technical Information of China (English)

    Teng Xiaoming; Zhuang Weidong; Huang Xiaowei; Cui Xiangzhong; Zhang Shusheng

    2006-01-01

    BaMgAl10O17: Eu2+ phosphors was prepared by the solid-reaction method.Y2SiO5 was coated uniformly on the surface of phosphor by the surface-coated method, and the luminescent and deterioration properties were discussed.The XRD and SEM results show that Y2SiO5 film is produced on the surface of BAM phosphor.The emission spectrum analysis shows that the peak of the phosphor does not change after coating.The two phosphors were applied to lamps and the deterioration was tested at different ignited time.The keep ratio of luminous flux of the phosphor coated with Y2SiO5 is higher than that of the uncoated phosphor.

  1. [Influence of synthetic technology on the structure and luminescent properties of Sr3B2O6:Eu2+ yellow phosphor].

    Science.gov (United States)

    Liu, Quan-Sheng; Zhang, Xi-Yan; Cui, Tian; Wei, Chen-Chen

    2012-11-01

    The Sr3B2O6:Eu(2+) yellow phosphor for warm white LED was synthesized by high temperature solid phase method. The influences on the phosphor structure and luminous properties of sintering temperature and holding time were systematically studied. Results indicated that the optimum synthetic temperature and soaking is 1 150 degrees C and 2 hours respectively. The crystalline structure of phosphor is rhombohedral Sr3B2O6. Sintering temperature and holding time has a significant influence on grain development. The excitation spectrum of phosphor composes of a wide-band spectrum main peaking at 398 nm, and the phosphor can be excited by near ultraviolet and blue light. The luminescence spectrum of phosphor is a broad spectrum peaking at 574 nm. Sintering temperature and holding time have a main effect on luminous intensity of phosphor.

  2. Monolithic translucent BaMgAl10O17:Eu2+ phosphors for laser-driven solid state lighting

    Directory of Open Access Journals (Sweden)

    Clayton Cozzan

    2016-10-01

    Full Text Available With high power light emitting diodes and laser diodes being explored for white light generation and visible light communication, thermally robust encapsulation schemes for color-converting inorganic phosphors are essential. In the current work, the canonical blue-emitting phosphor, high purity Eu-doped BaMgAl10O17, has been prepared using microwave-assisted heating (25 min and densified into translucent ceramic phosphor monoliths using spark plasma sintering (30 min. The resulting translucent ceramic monoliths convert UV laser light to blue light with the same efficiency as the starting powder and provide superior thermal management in comparison with silicone encapsulation.

  3. Rapid Synthesis of Submicrometer-sized Red Phosphor CaS∶Cu+,Eu2+ in a Microwave Field

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The red phosphor materials CaS∶Cu+,Eu2+ were firstly synthesized in a microwave field, and characterized by XRD、SEM、fluorescent spectroscopy. The experimental results of XRD and SEM show that the phosphors of CaS∶Cu+,Eu2+ possess a spherical crystallite structure, in the submicrometer(250~500 nm) size range. Compared to the conventional high temperature solid state reaction this new synthetic technique exhibits interesting features, such as rapid reactions without other protective atmosphere,phosphors with high purity, smaller particles,and higher efficient luminescence.

  4. Monolithic translucent BaMgAl10O17:Eu2+ phosphors for laser-driven solid state lighting

    Science.gov (United States)

    Cozzan, Clayton; Brady, Michael J.; O'Dea, Nicholas; Levin, Emily E.; Nakamura, Shuji; DenBaars, Steven P.; Seshadri, Ram

    2016-10-01

    With high power light emitting diodes and laser diodes being explored for white light generation and visible light communication, thermally robust encapsulation schemes for color-converting inorganic phosphors are essential. In the current work, the canonical blue-emitting phosphor, high purity Eu-doped BaMgAl10O17, has been prepared using microwave-assisted heating (25 min) and densified into translucent ceramic phosphor monoliths using spark plasma sintering (30 min). The resulting translucent ceramic monoliths convert UV laser light to blue light with the same efficiency as the starting powder and provide superior thermal management in comparison with silicone encapsulation.

  5. Luminescence properties of Tb3+ doped Sr2SnO4 green phosphor in UV/VUV regions.

    Science.gov (United States)

    Srinivas, M; Rao, B Appa; Vithal, M; Rao, P Raghava

    2013-01-01

    Polycrystalline Sr2SnO4 phosphors doped with Tb(3+) were prepared by conventional solid-state reaction method. Materials were characterized by powder XRD and EDS techniques. The luminescence properties of these materials were investigated under UV and VUV excitation. Upon excitation at 272 nm, phosphors exhibited intense emissions at 492 and 543 nm due to (5)D4 → (7)F6 and (5)D4 → (7)F5 transitions of Tb(3+) ions, respectively. Materials also exhibited strong emissions from these transitions under VUV excitation at 147, 173 and 230 nm. Quantitative analysis of the spectra indicated probable applications of these phosphors for PDP and other display devices as green emitting phosphors.

  6. Temperature effects on photoluminescence of YAG:Ce3+ phosphor and performance in white light-emitting diodes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yanfang; LI Lan; ZHANG Xiaosong; XI Qun

    2008-01-01

    The well crystalline YAG:Ce3+ phosphor was synthesized by solid-state method, and the temperature dependence of excitation and emission spectra of YAG:Ce3+ phosphor were investigated in the temperature range from room temperature to 573 K. With temperature increasing, it was noted that the emission intensity of as-prepared phosphors decreased considerably more rapidly when pumped by 460 nm than by 340 nm. The temperature-intensity curves under different excitation wavelengths were obtained using an Arrhenius function, and the corresponding activation energies were also obtained respectively. Thus, the experimental phenomenon was discussed in terms of nonradiative decay rate. The effects of as-prepared phosphors on the performance of the white LED with changing temperature were also studied.

  7. A Potential Candidate for Lamp Phosphor: Eu3+ Activated K2Y2B2O7

    Directory of Open Access Journals (Sweden)

    K. A. Koparkar

    2014-01-01

    Full Text Available The novel phosphor K2Y2B2O7 doped with europium is studied for its photoluminescence properties. The studies show that the phosphor gives strong red emission (PL at 613 nm related to 5D0-7F2 transition of Eu3+ under the 260 nm excitation (PLE related to the charge transfer (CT from the 2p orbital of the O2− ions to the 4f orbital of Eu3+ ions with CIE coordinates (x=0.675; y=0.324. The results of PL and PLE spectra indicate the applicability of K2Y2B2O7:Eu as a red component in lamp phosphor. The phosphor is characterized through XRD pattern analysis, and morphology is explained on the basis of SEM image. Optimum concentration of Eu3+ required for the highest intensity of emission is also studied.

  8. Effect of fluxes on structure and luminescence properties of Y3Al5O12:Ce3+ phosphors

    Institute of Scientific and Technical Information of China (English)

    XU Shiqing; SUN Liuzheng; ZHANG Ying; JU Haidong; ZHAO Shilong; DENG Degang; WANG Huanping; WANG Baoling

    2009-01-01

    Ce3+-activated yttrium aluminum garnet (YAG) was prepared by the solid-state reaction, in which H3BO3, LiF, NaF, KF and BaF2 were used as the fluxes. The effect of fluxes on optical properties of phosphors was studied in detail, especially the fluxes of alkali fluorides, which could enhance the emission intensity and change the wavelength of emission peaks. Among these YAG:Ce phosphors, the phosphor sintered with H3BO3 and NaF exhibited the strongest emission. The emission peaks of phosphors prepared with fluxes from LiF to KF were shifted to long wavelength. The effect of NaF concentration on the emission intensity of YAG:Ce was also investigated. The value of emis-sion intensity reached the maximum when the concentration of NaF was 0.5%.

  9. Effect of strontium nitride on the properties of Sr2SisNs:Eu2+ red phosphor

    Institute of Scientific and Technical Information of China (English)

    Teng Xiaoming; Liang Chao; He Jinhua

    2011-01-01

    The nitride phosphor Sr2SisNs :Eu2+ was synthesized by the high temperature solid-state method. The properties of Sr2 Si5Ns:Eu2+ were discussed by X-ray diffraction (XRD) scanning electron microscope (SEM) and spectra analysis. The XRD pattern shows that the single phase produces when strontium nitride is a bit excessive.The SEM photo implies that the excessive strontium nitride works as a flux in the reaction system. The position of emission peak is also located at about 612 nm as strontium nitride is excessive. The luminescent intensity of the phosphor adding excessive strontium nitride is higher than that of the phosphor introducing stoichiometric strontium nitride. The optimized content of nitride strontium was 2.05 mol/mol for the obtained phosphor with excellent properties.

  10. Synthesis and thermoluminescence behavior of ZrO2:Eu3+ with variable concentration of Eu3+ doped phosphor

    Directory of Open Access Journals (Sweden)

    Raunak Kumar Tamrakar

    2014-10-01

    Full Text Available Cubical ZrO2 phosphor doped with the europium synthesized by conventional solid state synthesis method. The prepared phosphor was characterized by X-ray diffraction (XRD technique, field emission gun scanning electron microscopy (FEGSEM and transmission electron microscopy (TEM. In this paper, we focused on the thermoluminescence glow curves and kinetic parameters, activation energy, order of kinetics, and the frequency factor of ZrO2:Eu3+ phosphor under different doses of UV irradiations at a heating rate of 6.7 °C/s. The kinetic parameters activation energy E, the order of kinetics b, and the frequency factor s of synthesized phosphor of ZrO2:Eu3+ have been calculated by using a peak shape method.

  11. Extraction equilibrium of indium(III) from nitric acid solutions by di(2-ethylhexyl)phosphoric acid dissolved in kerosene

    National Research Council Canada - National Science Library

    Tsai, Hung-Sheng; Tsai, Teh-Hua

    2012-01-01

    The extraction equilibrium of indium(III) from a nitric acid solution using di(2-ethylhexyl) phosphoric acid (D2EHPA) as an acidic extractant of organophosphorus compounds dissolved in kerosene was studied...

  12. Synthesis and photoluminescence properties of LiSrPO4:Eu2+ phosphor for solid state lighting

    Science.gov (United States)

    Game, D. N.; Taide, S. T.; Khan, Z. S.; Ingale, N. B.; Omanwar, S. K.

    2016-05-01

    A novel method to prepare orthophosphate LiSrPO4: Eu2+ phosphor for white light-emitting diodes (w-LEDs) is given in this paper. Phosphor was successfully synthesized by Pechini (citrate gel) method which is efficient than conventional high temperature solid state reaction. X-ray powder diffraction (XRD) analysis confirmed the single phase formation of LiSrPO4:Eu2+ with monoclinic crystal structure. Luminescence results showed that the phosphor could be efficiently excited by near UV and exhibited bright blue emission at λem = 420 nm corresponding to 5d- 4f transition of Eu2+. The phosphor exhibits blue emission bands under 350 nm excitation. This mercury-free excitation is useful for solid state lighting and light-emitting diode (LED). Hence it could be useful for solid state lighting and light-emitting diode (LED) application.

  13. Efficiency enhancement in white phosphor-on-cup light-emitting diodes using short wave-pass filters

    Science.gov (United States)

    Cho, Sang-Hwan; Oh, Jeong Rok; Lee, Yong-Hee; Do, Young Rag

    2010-02-01

    We proposed and demonstrated a simple approach for designing and developing blue-excitation-light passing and phosphor-yellow-emission-light reflecting dielectric multilayer to enhance the forward efficiency of Y3Al5O12:Ce3+ (YAG:Ce) yellow phosphor on top of a blue InGaN LED cup. When inserting a modified quarter-wave films of alternate high- and low-refractive index dielectric films (TiO2/SiO2) into the interface between a YAG:Ce phosphor layer and a glass substrate, enhancements of the efficiency and luminous efficacy of the forward white emission become 1.64 and 1.95 times that of a conventional phosphor on top of a blue LED cup with a lower correlated color temperature (< 4000K).

  14. Potential of phosphoric acid-catalyzed pretreatment and subsequent enzymatic hydrolysis for biosugar production from Gracilaria verrucosa.

    Science.gov (United States)

    Kwon, Oh-Min; Kim, Sung-Koo; Jeong, Gwi-Taek

    2016-07-01

    This study combined phosphoric acid-catalyzed pretreatment and enzymatic hydrolysis to produce biosugars from Gracilaria verrucosa as a potential renewable resource for bioenergy applications. We optimized phosphoric acid-catalyzed pretreatment conditions to 1:10 solid-to-liquid ratio, 1.5 % phosphoric acid, 140 °C, and 60 min reaction time, producing a 32.52 ± 0.06 % total reducing sugar (TRS) yield. By subsequent enzymatic hydrolysis, a 68.61 ± 0.90 % TRS yield was achieved. These results demonstrate the potential of phosphoric acid to produce biosugars for biofuel and biochemical production applications.

  15. Degradation Physics of High Power LEDs in Outdoor Environment and the Role of Phosphor in the degradation process

    OpenAIRE

    Preetpal Singh; Cher Ming Tan

    2016-01-01

    A moisture- electrical ? temperature (MET) test is proposed to evaluate the outdoor reliability of high power blue LEDs, with and without phosphor, and to understand the degradation physics of LEDs under the environment of combined humidity, temperature and electrical stresses. The blue LEDs with phosphor will be the high power white LEDs. Scanning acoustic microscopy is used to examine the resulted delamination during this test for the LEDs. The degradation mechanisms of blue LEDs (LEDs with...

  16. Inorganic wastes in manufacturing of glass-ceramics. Slurry of phosphorous fertilizer production and oil shale ash

    Energy Technology Data Exchange (ETDEWEB)

    Gorokhovsky, A.V.; Mendez-Nonell, J.; Escalante-Garcia, J.I.; Pech-Canul, M.I.; Vargas-Gutierrez, G. [Department of Engineering Ceramics of CINVESTAV-IPN, Unidad Saltillo-Monterrey, km 13.5, Apartado Postal 663, CP 25000, Saltillo, Coahuila (Mexico); Gorokhovsky, V.A.; Mescheryakov, D.V. [Department of Building Materials of Saratov State Technical University, Saratov (Russian Federation)

    2001-11-01

    The use of bicomponent raw material mixtures of industrial wastes to produce pyroxene glass ceramics was investigated. It is shown that oil shale ash from heat power stations can promote the production of crystalline phases and the slurry from phosphorous fertilizer production can provide sufficient concentration of nucleating agents. Mechanical and chemical properties, as well as the structure and crystallization mechanism were characterized. An increase of phosphorous oxide and fluorine concentrations leads to a change of the crystallization mechanism.

  17. Quantitative Characterization of Phosphor Detector for Fusion Plasmas; Caracterizacion Cuantitativa de Detectores Luminiscentes para Plasmas de Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Baciero, A.; Zurro, B.; McCarthy, K. J.

    2004-07-01

    Experiments made to characterize phosphor screens with application as broadband radiation detectors, are described. Several radiation sources, covering the spectral range between the ultraviolet and X ray, were used. In addition, details are given of three original phosphor-screen-based detectors that were designed for use as broadband detectors in magnetically confined fusion devices. The first measurements obtained with these detectors in plasmas created in the TJ-II stellarator device are presented together with the analysis performed. (Author)

  18. In-Situ Wet Chemical Composition of Multicomponent Precursors to Blue Emitting Sr2CeO4 Phosphors

    Institute of Scientific and Technical Information of China (English)

    Yan Bing; Xiao Xiuzhen

    2004-01-01

    Hybrid precursors were assembled with cerium coordination polymers, polyethyl glycohol (PEG), SrCO3 and other functional components using a modified in-situ chemical polymeric gel technology. The hybrid precursors were calcinated to achieve the Sr2CeO4 phosphors, whose particle sizes were in the range of micrometer by XRD and SEM. The photoluminescence spectra indicate that the phosphors present a strong blue emission.

  19. Synthesis, energy transfer and tunable emission properties of SrSb2O6:Eu(3+), Bi(3+) phosphor.

    Science.gov (United States)

    Cao, Renping; Fu, Ting; Peng, Dedong; Cao, Chunyan; Ruan, Wen; Yu, Xiaoguang

    2016-12-05

    Host SrSb2O6, SrSb2O6:Bi(3+), SrSb2O6:Eu(3+), and SrSb2O6:Eu(3+), Bi(3+) phosphors are synthesized by solid state reaction method in air. Host SrSb2O6 with excitation 254nm shows weak green-yellow emission in the range of 320-780nm due to Sb(5+)→O(2-) transition. SrSb2O6:Bi(3+) phosphor with excitation 365nm emits green light within the range 400-650nm owing to the (3)P1→(1)S0 transition of Bi(3+) ion. SrSb2O6:Eu(3+) phosphor with excitation 254nm exhibits a systematically varied hue from green to orange-red light by increasing Eu(3+) concentration from 0 to 7mol%, and that with excitation 394nm only shows orange-red light. The optimal Eu(3+) concentration is ~4mol% in SrSb2O6:Eu(3+) phosphor. SrSb2O6:Eu(3+), Bi(3+) phosphor with excitation 254 and 394nm emits orange-red light. Emission intensity of SrSb2O6:Eu(3+) phosphor may be enhanced >2 times by co-doping Bi(3+) ion because of the fluxing agent and energy transfer roles of Bi(3+) ion in SrSb2O6:Eu(3+), Bi(3+) phosphor. The luminous mechanism of SrSb2O6:Eu(3+), Bi(3+) phosphor is analyzed and explained by the simplified energy level diagrams of Sb2O6(2-) group, Bi(3+) and Eu(3+) ions, and energy transfer processes between them.

  20. Europium doped di-calcium magnesium di-silicate orange–red emitting phosphor by solid state reaction method

    Directory of Open Access Journals (Sweden)

    Ishwar Prasad Sahu

    2015-07-01

    Full Text Available A new orange–red europium doped di-calcium magnesium di-silicate (Ca2MgSi2O7:Eu3+ phosphor was prepared by the traditional high temperature solid state reaction method. The prepared Ca2MgSi2O7:Eu3+ phosphor was characterized by X-ray diffractometer (XRD, transmission electron microscopy (TEM, field emission scanning electron microscopy (FESEM with energy dispersive x-ray spectroscopy (EDX, fourier transform infrared spectra (FTIR, photoluminescence (PL and decay characteristics. The phase structure of sintered phosphor was akermanite type structure which belongs to the tetragonal crystallography with space group P4¯21m, this structure is a member of the melilite group and forms a layered compound. The chemical composition of the sintered Ca2MgSi2O7:Eu3+ phosphor was confirmed by EDX spectra. The PL spectra indicate that Ca2MgSi2O7:Eu3+ can be excited effectively by near ultraviolet (NUV light and exhibit bright orange–red emission with excellent color stability. The fluorescence lifetime of Ca2MgSi2O7:Eu3+ phosphor was found to be 28.47 ms. CIE color coordinates of Ca2MgSi2O7:Eu3+ phosphor is suitable as orange-red light emitting phosphor with a CIE value of (X = 0.5554, Y = 0.4397. Therefore, it is considered to be a new promising orange–red emitting phosphor for white light emitting diode (LED application.