WorldWideScience

Sample records for earth doped wide

  1. Electrostatic tuning of Kondo effect in a rare-earth-doped wide-band-gap oxide

    KAUST Repository

    Li, Yongfeng

    2013-04-29

    As a long-lived theme in solid-state physics, the Kondo effect reflects the many-body physics involving the short-range Coulomb interactions between itinerant electrons and localized spins in metallic materials. Here we show that the Kondo effect is present in ZnO, a prototypical wide-band-gap oxide, doped with a rare-earth element (Gd). The localized 4f electrons of Gd ions do not produce remanent magnetism, but interact strongly with the host electrons, giving rise to a saturating resistance upturn and negative magnetoresistance at low temperatures. Furthermore, the Kondo temperature and resistance can be electrostatically modulated using electric-double-layer gating with liquid ionic electrolyte. Our experiments provide the experimental evidence of tunable Kondo effect in ZnO, underscoring the magnetic interactions between localized and itinerant electrons and the emergent transport behaviors in such doped wide-band-gap oxides.

  2. Crystal-field investigations of rare-earth-doped wide band gap semiconductors

    CERN Multimedia

    Muller, S; Wahl, U

    Crystal field investigations play a central role in the studies of rare earth doped semiconductors. Optical stark level spectroscopy and lattice location studies of radioactive rare earth isotopes implanted at ISOLDE have provided important insight into these systems during the last years. It has been shown that despite a major site preference of the probe atoms in the lattice, several defect configurations do exist. These sites are visible in the optical spectra but their origin and nature aren't deducible from these spectra alone. Hyperfine measurements on the other hand should reveal these defect configurations and yield the parameters necessary for a description of the optical properties at the atomic scale. In order to study the crystal field with this alternative approach, we propose a new concept for perturbed $\\gamma\\gamma$-angular correlation (PAC) experiments at ISOLDE based on digital signal processing in contrast to earlier analog setups. The general functionality of the spectrometer is explained ...

  3. Wide frequencies range of spin excitations in a rare-earth Bi-doped iron garnet with a giant Faraday rotation

    Science.gov (United States)

    Parchenko, Sergii; Stupakiewicz, Andrzej; Yoshimine, Isao; Satoh, Takuya; Maziewski, Andrzej

    2013-10-01

    Ultrafast magnetization dynamics of a rare-earth Bi-doped garnet were studied using an optical pump-probe technique via the inverse Faraday effect. We observed a wide range of frequency modes of the magnetization precession, covering two orders of magnitude. The excitation efficiency of low-frequency precessions in the GHz range, together with a significant beating effect, strongly depended on the amplitude of the external magnetic field. On the contrary, high-frequency precession was independent of the external magnetic field. The obtained results may be exploited in the development of wide class of microwave and magneto-optical devices.

  4. Review on dielectric properties of rare earth doped barium titanate

    Science.gov (United States)

    Ismail, Fatin Adila; Osman, Rozana Aina Maulat; Idris, Mohd Sobri

    2016-07-01

    Rare earth doped Barium Titanate (BaTiO3) were studied due to high permittivity, excellent electrical properties and have wide usage in various applications. This paper reviewed on the electrical properties of RE doped BaTiO3 (RE: Lanthanum (La), Erbium (Er), Samarium (Sm), Neodymium (Nd), Cerium (Ce)), processing method, phase transition occurred and solid solution range for complete study. Most of the RE doped BaTiO3 downshifted the Curie temperature (TC). Transition temperature also known as Curie temperature, TC where the ceramics had a transition from ferroelectric to a paraelectric phase. In this review, the dielectric constant of La-doped BaTiO3, Er-doped BaTiO3, Sm-doped BaTiO3, Nd-doped BaTiO3 and Ce-doped BaTiO3 had been proved to increase and the transition temperature or also known as TC also lowered down to room temperature as for all the RE doped BaTiO3 except for Er-doped BaTiO3.

  5. Reduction property of rare earth oxide doped molybdenum oxide

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Rare earth oxide doped molybdenum powders were prepared by the reduction of rare earth nitrites doped MoO3. The effect of rare earth oxide on the reduction behavior of molybdenum oxide had been studied by means of Temperature Programmed Reduction (TPR), thermal analysis, X-ray diffraction. Doping rare earth oxide in the powder could lower the reduction temperature of molybdenum oxide and decrease the particle size of molybdenum. The mechanism for the effects had been discussed in this paper.

  6. Monolithic Rare Earth Doped PTR Glass Laser Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The main goal of the project is to demonstrate the feasibility of a monolithic solid state laser on the basis of PTR glass co-doped with luminescent rare earth ions....

  7. Rare Earth Doped Optical Fibre From Oxide Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Minati Chatterjee; Aharon Gedanken; Renata Reisfeld; Ranjan Sen; Mrinmay Pal; Milan Naskar; Mukul Paul; Shyamal Bhadra; Kamal Dasgupta; Dibyendu Ganguli; Tarun Bandyopadhyay

    2003-01-01

    Rare earth (RE) doped optical fibres were fabricated by using RE oxides coated silica nanoparticles. The fibre properties are comparable to those prepared by conventional techniques. The process offers better control over RE incorporation and homogeneity in the preform.

  8. Rare-earth-ion-doped double-tungstate waveguides

    NARCIS (Netherlands)

    Pollnau, M.

    2007-01-01

    It has been recognized that the monoclinic double tungstates KY(WO4)2, KGd(WO4)2, and KLu(WO4)2 possess a high potential as rare-earth-ion-doped solid-state laser materials, partly due to the high absorption and emission cross-sections of rare-earth ions when doped into these materials. Besides, the

  9. Doped silicene: Evidence of a wide stability range

    KAUST Repository

    Cheng, Yingchun

    2011-06-17

    The effects of doping on the lattice structure, electronic structure, phonon spectrum, and electron-phonon coupling of low-buckling silicene are studied by first-principles calculations. Although the lattice is found to be very sensitive to the carrier concentration, it is stable in a wide doping range. The frequencies of the E2g-Γ and A′-K Raman modes can be used to probe the carrier concentration. In addition, the phonon dispersion displays Kohn anomalies at the Γ and K points which are reduced by doping. This implies that the electron-phonon coupling cannot be neglected in field-effect transistor applications. Copyright © 2011 EPLA.

  10. Recent Advances in New Band Rare-earth Doped Fiber Amplifiers

    Institute of Scientific and Technical Information of China (English)

    CHANG Jun; WANG Qing-pu; LIAN Jie; ZHANG Xing-yu; LI Ping; ZHANG Sha-sha

    2004-01-01

    Broadband,high bit rate,long hauls and system intelligence are current trends in developing fiber optic communication systems.The ever-increasing traffic demands have made it urgent to develop new band optical fiber amplifier.Laser characteristics of various rare-earth ion including Er3+,Tm3+,Pr3+,Dy3+,Ho3+,and Nd3+ doped fiber are reviewed.Recent advances of rare-earth doped fiber amplifiers with wide-band and flat gain are also introduced.

  11. Radar Images of the Earth and the World Wide Web

    Science.gov (United States)

    Chapman, B.; Freeman, A.

    1995-01-01

    A perspective of NASA's Jet Propulsion Laboratory as a center of planetary exploration, and its involvement in studying the earth from space is given. Remote sensing, radar maps, land topography, snow cover properties, vegetation type, biomass content, moisture levels, and ocean data are items discussed related to earth orbiting satellite imaging radar. World Wide Web viewing of this content is discussed.

  12. Photo-Induced conductivity of heterojunction GaAs/Rare-Earth doped SnO2

    Directory of Open Access Journals (Sweden)

    Cristina de Freitas Bueno

    2013-01-01

    Full Text Available Rare-earth doped (Eu3+ or Ce3+ thin layers of tin dioxide (SnO2 are deposited by the sol-gel-dip-coating technique, along with gallium arsenide (GaAs films, deposited by the resistive evaporation technique. The as-built heterojunction has potential application in optoelectronic devices, because it may combine the emission from the rare-earth-doped transparent oxide, with a high mobility semiconductor. Trivalent rare-earth-doped SnO2 presents very efficient emission in a wide wavelength range, including red (in the case of Eu3+ or blue (Ce3+. The advantage of this structure is the possibility of separation of the rare-earth emission centers, from the electron scattering, leading to an indicated combination for electroluminescence. Electrical characterization of the heterojunction SnO2:Eu/GaAs shows a significant conductivity increase when compared to the conductivity of the individual films. Monochromatic light excitation shows up the role of the most external layer, which may act as a shield (top GaAs, or an ultraviolet light absorber sink (top RE-doped SnO2. The observed improvement on the electrical transport properties is probably related to the formation of short conduction channels in the semiconductors junction with two-dimensional electron gas (2DEG behavior, which are evaluated by excitation with distinct monochromatic light sources, where the samples are deposited by varying the order of layer deposition.

  13. Magnetization dynamics in rare earth doped NiFe films

    Energy Technology Data Exchange (ETDEWEB)

    Kiessling, Matthias; Woltersdorf, Georg; Back, Christian [Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, D- 93040 Regensburg (Germany); Thiele, Jan-Ulrich; Schabes, Manfred [Hitachi Global Storage Technologies, 3403 Yerba Buena Road, San Jose, CA 95135 (United States)

    2007-07-01

    The influence of rare earth dopants on the damping parameter and the resulting possibility to control this parameter were investigated. In our experiments NiFe films were doped with Dysprosium, Holmium, Terbium, and Gadolinium. The magnetization dynamics of these rare earth doped films was mainly studied by means of ferromagnetic resonance (FMR) and network-analyzer ferromagnetic resonance. It is demonstrated that the doping of a NiFe film by a small amount of rare earth elements (Holmium, Terbium and Dysprosium) greatly effects its magnetic relaxation rate. This additional damping is proportional to the doping level. Compared to the pure NiFe film it is possible to increase the damping parameter of the magnetic film by two orders of magnitude. On the other hand Gadolinium as a dopant has no influence on the damping parameter. For small dopant concentrations the in and out-of-plane FMR measurements at various frequencies can be well described by the same damping parameter. This is expected for the Gilbert damping term in the equation of motion. Therefore the increased damping can be attributed to an increased rate of transfer of angular momentum from the spin system to the lattice.

  14. Thermoluminescence dosimetry of rare earth doped calcium aluminate phosphors

    Indian Academy of Sciences (India)

    K Madhukumar; K Rajendra Babu; K C Ajith Prasad; J James; T S Elias; V Padmanabhan; C M K Nair

    2006-04-01

    The thermoluminescence (TL) properties of calcium aluminate (CaAl2O4) doped with different rare earth ions have been studied and their suitability for radiation dosimetry applications is discussed. It is observed that monocalcium aluminate doped with cerium is a good dosimeter having linear response up to about 4 kGy of radiation doses. Dopant concentration of 0.25 mol% cerium gives maximum TL emission. The well-defined single peak observed at 295°C can be advantageously used for high temperature dosimetry applications.

  15. Promising wastewater treatment using rare earth-doped nanoferrites

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M.A., E-mail: moala47@hotmail.com [Materials Science Lab (1), Physics Department, Faculty of Science, Cairo University, Giza (Egypt); Bishay, Samiha T.; Khafagy, Rasha M. [Physics Department, Girls College for Arts, Science and Education, Ain Shams University, Cairo (Egypt); Saleh, N.M. [Physics Department, Faculty of Science, Western Mountain University (Libya)

    2014-01-15

    Single-phases of the spinel nanoferrites Zn{sub 0.5}Co{sub 0.5}Al{sub 0.5}R{sub 0.04}Fe{sub 1.46}O{sub 4}; R=Sm, Pr, Ce and La, were synthesized using the flash auto combustion method. X-ray diffraction (XRD) results indicated that doping nanoferrites with small concentrations of rare earth elements (RE) allowed their entrance to the spinel lattice. Transmission electron microscope (TEM) images revealed that doping with different RE elements resulted in the formation of different nanometric shapes such as nanospheres and nanowires. Doping with Sm{sup 3+} and Ce{sup 3+} resulted in the formation of nanospheres with average diameter of 14 and 30 nm respectively. In addition to the granular nanospheres, doping with Pr{sup 3+} and La{sup 3+} resulted in the formation of some nanowires with different aspect ratios (average length of ≈100 nm and diameter of ≈9 nm) and (average length of ≈150 nm and outer diameter of ≈22 nm) respectively. At fixed temperature, the Ac conductivity (σ) increased as the RE ionic radius increases except for Ce, due to the role of valance fluctuation from Ce{sup 3+} to Ce{sup 4+} ions. La- and Pr-doped nanoferrites showed the highest ac conductivity values, which is most probably due to the presence of large numbers of nanowires in these two types of ferrites. For all entire samples, the effective magnetic moment (μ{sub eff}) decreased, while the Curie temperature (T{sub C}) increased as the RE ionic radius increases. The synthesized rare earth nanoferrites showed promising results in purifying colored wastewater. La-doped ferrite was capable for up-taking 92% of the dye content, followed by Pr-doped ferrite, which adsorbed 85% of the dye, while Sm- and Ce-doped ferrites showed lower dye removal efficiency of 80% and 72% respectively. High dye uptake shown by La- and Pr-doped ferrites is most probably due to the presence of nanowires and their higher Ac conductivity values. These excellent results were not previously reported

  16. Rare Earth Doped High Temperature Ceramic Selective Emitters

    Science.gov (United States)

    Chubb, Donald L.; Pal, AnnaMarie; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study develops a spectral emittance model for films of rare earth containing materials. Although there are several possible rare earth doped high temperature materials, this study was confined to rare earth aluminum garnets. Good agreement between experimental and theoretical spectral emittances was found for erbium, thulium and erbium-holmium aluminum garnets. Spectral emittances of these films are sensitive to temperature differences across the film. Emitter efficiency is also a sensitive function of temperature. For thulium aluminum garnet the efficiency is 0.38 at 1700 K but only 0.19 at 1262 K.

  17. Rare-earth ions doped transparent oxyfluoride glass-ceramics

    OpenAIRE

    2010-01-01

    In recent years, rare-earth ions doped transparent oxyfluoride glass-ceramics have attracted great attentions for their low phonon energy environments of fluoride nanocrystals and high chemical and mechanical stabilities of oxide glassy matrix. In this chapter, firstly, the crystallization behaviors of the transparent glassceramics containing CaF2 nanocrystals are presented to demonstrate the controllable microstructure evolution of nano-composites. Secondly, the optical properties of the new...

  18. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    OpenAIRE

    Timothy A. DeVol; Basak Yazgan-Kukouz; Baris Kokuoz; DiMaio, Jeffrey R.; Kevin B. Sprinkle; Tiffany L. James; Courtney J. Kucera; JACOBSOHN, Luiz G.; John Ballato

    2010-01-01

    This paper reviews the synthesis, structure and applications of metal fluoride nanoparticles, with particular focus on rare earth (RE) doped fluoride nanoparticles obtained by our research group. Nanoparticles were produced by precipitation methods using the ligand ammonium di-n-octadecyldithiophosphate (ADDP) that allows the growth of shells around a core particle while simultaneously avoiding particle aggregation. Nanoparticles were characterized on their structure, morphology, and luminesc...

  19. Optical Properties of Rare Earth Doped SrS Phosphor: A Review

    Science.gov (United States)

    Khare, Ayush; Mishra, Shubhra; Kshatri, D. S.; Tiwari, Sanjay

    2016-10-01

    Rare earth (RE) doped SrS phosphor has attracted a lot of attention on a wide range of photo-, cathodo-, thermo-, and electroluminescent applications. Upon doping with different RE elements (e.g., Ce, Pr, Eu, Yb), the luminescence from SrS can be varied over the entire visible region by appropriately choosing the composition of the strontium sulfide host. The main applications include flat panel displays and SrS-based powder electroluminescence (EL) for back lights. Sulfide materials known for providing Eu2+ based red emission band and preferred as a color conversion material in white light emitting diodes are discussed. Especially, the applications of RE doped SrS are described in light of their utility as conversion and storage phosphors. The effect of energy level splitting, EL efficiency, post-annealing, milling time, and impurity on luminescence properties for SrS are also discussed.

  20. Optical Properties of Rare Earth Doped SrS Phosphor: A Review

    Science.gov (United States)

    Khare, Ayush; Mishra, Shubhra; Kshatri, D. S.; Tiwari, Sanjay

    2017-02-01

    Rare earth (RE) doped SrS phosphor has attracted a lot of attention on a wide range of photo-, cathodo-, thermo-, and electroluminescent applications. Upon doping with different RE elements (e.g., Ce, Pr, Eu, Yb), the luminescence from SrS can be varied over the entire visible region by appropriately choosing the composition of the strontium sulfide host. The main applications include flat panel displays and SrS-based powder electroluminescence (EL) for back lights. Sulfide materials known for providing Eu2+ based red emission band and preferred as a color conversion material in white light emitting diodes are discussed. Especially, the applications of RE doped SrS are described in light of their utility as conversion and storage phosphors. The effect of energy level splitting, EL efficiency, post-annealing, milling time, and impurity on luminescence properties for SrS are also discussed.

  1. Electrorheological behavior of rare earth-doped barium titanate suspensions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Doping Y, La, Ce into barium titanate is found to be able to improve its electrorheological (ER) effect in DC electrical field. The yield stress of a typical doped barium titanate/silicone oil suspension is approximately 3.2 -*7〗kPa at 3.5 -*7〗kV/mm, which is 10 times larger than that of pure barium titanate/silicone oil suspensions. The ER effect increases with the decrease of ionic radius of rare earth (RE) dopant when RE concentration remains constant, and the suspensions exhibit a relatively high shear stress when Y, La, Ce mole fractions are 15%, 10%~15%, and 5%, respectively. Dielectric measurements show that the suitable doping with RE element increases dielectric loss of barium titanate and causes very marked dielectric relaxation at low frequency. By measuring X-ray diffraction patterns of doped barium titanate, it is considered that the occurrence of lattice distortion or defects may be responsible for the change of dielectric properties which results in the improvement of ER effect of barium titanate in DC electrical field.

  2. Study on rare earth/alkaline earth oxide-doped CeO2 solid electrolyte

    Institute of Scientific and Technical Information of China (English)

    YAN Kai; ZHEN Qiang; Song Xiwen

    2007-01-01

    Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sintering at different temperatures. The results of X-ray diffraction and transmission electron microscopy showed that the grain size of the powders was approximately 20-30 nm, and rare earth/alkaline earth oxides were completely dissolved into ceria-based solid solution with fluorite structure. The electrical conductivities of the Sm2O3-CeO2 system were measured by the ac impedance technique in air at temperatures ranging from 513-900℃. The results indicated that the ionic conductivities of Sm0.20Ce0.8O1.875 solid electrolyte increase with increasing sintering temperature, and the relationship between the conductivities and measuring temperature obeys the Arrhenius equation. Then the Sm2O3-CeO2 material was further doped with other rare earth/alkaline earth oxide, and the conductivities improve with the effective index.

  3. Spectroscopic studies of Yb3+-doped rare earth orthosilicate crystals

    Science.gov (United States)

    Campos, S.; Denoyer, A.; Jandl, S.; Viana, B.; Vivien, D.; Loiseau, P.; Ferrand, B.

    2004-06-01

    Infrared transmission and Raman scattering have been used to study Raman active phonons and crystal-field excitations in Yb3+-doped yttrium, lutetium and scandium orthosilicate crystals (Y2SiO5 (YSO), Lu2SiO5 (LSO) and Sc2SiO5 (SSO)), which belong to the same C2h6 crystallographic space group. Energy levels of the Yb3+ ion 2F5/2 manifold are presented. In the three hosts, Yb3+ ions experience high crystal field strength, particularly in Yb:SSO. Satellites in the infrared transmission spectra have been detected for the first time in the Yb3+-doped rare earth orthosilicates. They could be attributed to perturbed Yb3+ sites of the lattices or to magnetically coupled Yb3+ pairs.

  4. Radioluminescence of rare-earth doped aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Santiago, M.; Molina, P. [Universidad Nacional del Centro de la Provincia de Buenos Aires, Instituto de Fisica Arroyo Seco, Pinto 399, 7000 Tandil (Argentina); Barros, V. S.; Khoury, H. J.; Elihimas, D. R., E-mail: msantiag@exa.unicen.edu.ar [Universidade Federal de Pernambuco, Departamento de Energia Nuclear, Av. Prof. Luiz Freire 1000, Recife, PE 50740-540 (Brazil)

    2011-10-15

    Carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) is one of the most used radioluminescence (Rl) materials for fiberoptic dosimetry due to its high efficiency and commercial availability. However, this compound presents the drawback of emitting in the spectral region, where the spurious radioluminescence of fibers is also important. In this work, the radioluminescence response of rare-earth doped Al{sub 2}O{sub 3} samples has been evaluated. The samples were prepared by mixing stoichiometric amounts of aluminum nitrate, urea and dopants with different amounts of terbium, samarium, cerium and thulium nitrates varying from 0 to 0.15 mo 1%. The influence of the different activators on the Rl spectra has been investigated in order to determine the feasibility of using these compounds for Rl fiberoptic dosimetry. (Author)

  5. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    Directory of Open Access Journals (Sweden)

    Timothy A. DeVol

    2010-03-01

    Full Text Available This paper reviews the synthesis, structure and applications of metal fluoride nanoparticles, with particular focus on rare earth (RE doped fluoride nanoparticles obtained by our research group. Nanoparticles were produced by precipitation methods using the ligand ammonium di-n-octadecyldithiophosphate (ADDP that allows the growth of shells around a core particle while simultaneously avoiding particle aggregation. Nanoparticles were characterized on their structure, morphology, and luminescent properties. We discuss the synthesis, properties, and application of heavy metal fluorides; specifically LaF3:RE and PbF2, and group IIA fluorides. Particular attention is given to the synthesis of core/shell nanoparticles, including selectively RE-doped LaF3/LaF3, and CaF2/CaF2 core/(multi-shell nanoparticles, and the CaF2-LaF3 system.

  6. Rare Earth Doped Fiber Amplifiers for the First Telecommunication Window

    Science.gov (United States)

    Sridhar, Balakrishnan

    A complete experimental and theoretical study of rare earth doped fiber-optic amplifiers for the first tele-communication window has been made. The thulium doped fluoride fiber amplifier is shown to provide amplification in the 800nm-820nm signal region. A complete steady state theoretical model has been presented and the model has been experimentally verified. The model predicts the gain, noise figure and the amplified spontaneous emission in the 800nm, 1470nm, 1900nm and 2300nm bands. The effect of population trapping at the ^3F_4 energy level of thulium ion is also shown with the help of the model. It has been shown that about 5 -15%o of the population is trapped at the ^3F _4 energy level. We have also shown theoretically, the expected gain and noise performance of Thulium doped fluoride fiber amplifiers pumped in the 680nm absorption band. The maximum gain at 806nm is slightly lower than with comparable 780 nm pumping. The gain bandwidth is however found to increase with 680nm pumping. The higher ASE at shorter wavelengths (flouride fiber amplifier in the 850nm signal band for the first time. The amplification is through an up-conversion process. The erbium doped flouride fiber amplifier was pumped with an estimated pump power of 35mW at 792nm. We have also considered a theoretical model for a single mode erbium doped fluoride fiber amplifier. Efficient amplification occurs because of the strong excited state absorption at the pump wavelength from the ^4I_{13/2} energy level.

  7. Multicomponent, Rare-Earth-Doped Thermal-Barrier Coatings

    Science.gov (United States)

    Miller, Robert A.; Zhu, Dongming

    2005-01-01

    Multicomponent, rare-earth-doped, perovskite-type thermal-barrier coating materials have been developed in an effort to obtain lower thermal conductivity, greater phase stability, and greater high-temperature capability, relative to those of the prior thermal-barrier coating material of choice, which is yttria-partially stabilized zirconia. As used here, "thermal-barrier coatings" (TBCs) denotes thin ceramic layers used to insulate air-cooled metallic components of heat engines (e.g., gas turbines) from hot gases. These layers are generally fabricated by plasma spraying or physical vapor deposition of the TBC materials onto the metal components. A TBC as deposited has some porosity, which is desirable in that it reduces the thermal conductivity below the intrinsic thermal conductivity of the fully dense form of the material. Undesirably, the thermal conductivity gradually increases because the porosity gradually decreases as a consequence of sintering during high-temperature service. Because of these and other considerations such as phase transformations, the maximum allowable service temperature for yttria-partially stabilized zirconia TBCs lies in the range of about 1,200 to 1,300 C. In contrast, the present multicomponent, rare-earth-doped, perovskite-type TBCs can withstand higher temperatures.

  8. Radiation effects on rare-earth doped optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Girard, S.; Marcandella, C. [CEA Bruyeres-le-Chatel, DIF 91 (France); Ouerdane, Y.; Tortech, B.; Boukenter, A.; Meunier, J.P.; Vivona, M. [Lab. Hubert Curien, CNRS, 42 - Saint-Etienne (France); Vivona, M.; Robin, Th.; Cadier, B. [iXFiber SAS, 22 - lannion (France)

    2010-07-01

    In this paper, we reviewed our previous work concerning the responses of rare-earth (RE) doped fibers (Yb, Er and Er/Yb) to various types of radiations like gamma-rays, X-rays and protons. For all these harsh environments, the main measured macroscopic radiation-induced effect is an increase of the linear attenuation of these waveguides due to the generation of point defects in the RE-doped core and silica-based cladding. To evaluate the vulnerability of this class of optical fibers for space missions, we characterize the growth and decay kinetics of their radiation-induced attenuation (RIA) during and after irradiation for various compositions. Laboratory testing reveals that this class of optical fibers is very sensitive to radiations compared to passive (RE-free) samples. As a consequence, despite the small length used for space applications, the understanding of the radiation-induced effects in this class of optical fibers becomes necessary before their integration as part of fiber-based systems like gyroscopes or communication systems. In this paper, we more particularly discussed about the relative influence of the rare-earth ions (Er{sup 3+} and/or Yb{sup 3+}) and of the glass matrix dopants (Al, P, ... ) on the optical degradation due to radiations. This has been done by using a set of five prototype optical fibers designed by the fiber manufacturer iXFiber SAS to enlighten the role of these parameters. Additional spectroscopic tools like con-focal microscopy of luminescence are also used to detect possible changes in the spectroscopy of the rare-earth ions and their consequences on the functionality of the active optical fibers. (authors)

  9. Guided mode cutoff in rare-earth doped rod-type PCFs

    DEFF Research Database (Denmark)

    Poli, F.; Cucinotta, A.; Passaro, D.

    2008-01-01

    Guided mode properties of rare-earth doped photonic crystal fibers are investigated as a function of the core refractive index, showing the possibility to obtain cutoff at low normalized wavelength.......Guided mode properties of rare-earth doped photonic crystal fibers are investigated as a function of the core refractive index, showing the possibility to obtain cutoff at low normalized wavelength....

  10. Rare earth-doped alumina thin films deposited by liquid source CVD processes

    Energy Technology Data Exchange (ETDEWEB)

    Deschanvres, J.L.; Meffre, W.; Joubert, J.C.; Senateur, J.P. [Ecole Nat. Superieure de Phys. de Grenoble, St. Martin d`Heres (France). Lab. des Materiaux et du Genie Phys.; Robaut, F. [Consortium des Moyens Technologiques Communs, Institut National Polytechnique de Grenoble, BP 75, 38402 St Martin d`Heres (France); Broquin, J.E.; Rimet, R. [Laboratoire d`Electromagnetisme, Microondes et Optoelectronique, CNRS-Ecole Nationale Superieure d`Electronique et Radioelectricite de Grenoble, BP 257, 38016 Grenoble, Cedex (France)

    1998-07-24

    Two types of liquid-source CVD processes are proposed for the growth of rare earth-doped alumina thin films suitable as amplifying media for integrated optic applications. Amorphous, transparent, pure and erbium- or neodymium-doped alumina films were deposited between 573 and 833 K by atmospheric pressure aerosol CVD. The rare earth doping concentration increases by decreasing the deposition temperature. The refractive index of the alumina films increases as a function of the deposition temperature from 1.53 at 573 K to 1.61 at 813 K. Neodymium-doped films were also obtained at low pressure by liquid source injection CVD. (orig.) 7 refs.

  11. Energy transfer and NIR emission in rare earth tri-doped barium lanthanum fluoro tellurite glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, J. Suresh; Pavani, K.; Graca, M.P.F.; Soares, M.J. [Department of Physics and I3N, University of Aveiro (Portugal); Venkataiah, G. [Department of Physics, Sri Venkateswara University, Tirupati (India); Jayasimhadri, M. [Department of Applied Physics, Delhi Technological University, Delhi (India)

    2014-09-15

    Barium lanthanum fluoro tellurite (BLFT) glasses doped with rare earth ions (ErF{sub 3}, PrF{sub 3} and YbF{sub 3}) both singly or in combinations were prepared by melt-quench technique and analysed spectroscopically. The prepared glasses were found to be mechanically strong and transparent. Optical absorption and NIR fluorescence were measured to the highly transparent and stable glass samples. Judd-Ofelt parameters and radiative properties were estimated for the single rare earth doped BLFT glasses using the optical absorption spectra. NIR fluorescence is measured using laser excitation. From the NIR emission spectra, energy transfer among the rare earth ions is analysed in the rare earth tri-doped BLFT glasses. These rare earth tri-doped BLFT glasses are found to be highly useful for the multi- wavelength emission in the NIR region for opto-electronic applications. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Electronic and Magnetic Properties of Rare-Earth Metals Doped ZnO Monolayer

    Directory of Open Access Journals (Sweden)

    Changlong Tan

    2015-01-01

    Full Text Available The structural, electronic, and magnetic properties of rare-earth metals doped ZnO monolayer have been investigated using the first-principles calculations. The induced spin polarization is confirmed for Ce, Eu, Gd, and Dy dopings while the induced spin polarization is negligible for Y doping. The localized f states of rare-earth atoms respond to the introduction of a magnetic moment. ZnO monolayer undergoes transition from semiconductor to metal in the presence of Y, Ce, Gd, and Dy doping. More interestingly, Eu doped ZnO monolayer exhibits half-metallic behavior. Our result demonstrates that the RE-doping is an efficient route to modify the magnetic and electronic properties in ZnO monolayer.

  13. Rare-earth-doped materials for applications in quantum information storage and signal processing

    Energy Technology Data Exchange (ETDEWEB)

    Thiel, C.W., E-mail: thiel@physics.montana.ed [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Boettger, Thomas, E-mail: tbottger@usfca.ed [Department of Physics and Astronomy, University of San Francisco, 2130 Fulton St., San Francisco, CA 94117 (United States); Cone, R.L., E-mail: cone@montana.ed [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

    2011-03-15

    Realization of practical quantum memory and optical signal processing systems critically depends on suitable materials that offer specific combinations of properties. Solid-state materials such as rare-earth ions doped into dielectric crystals are one of the most promising candidates for several quantum information storage protocols, including quantum storage of single photons. This article provides an overview of rare-earth-doped material properties and summarizes some of the most promising materials studied in our laboratory and by other groups for applications in quantum information storage and for ultra-wide bandwidth signal processing. Understanding and controlling spectral diffusion in these materials, which ultimately limits the achievable performance of any quantum memory system, is also briefly reviewed. Applications in quantum information impose stringent requirements on laser phase and frequency stability, and employing a narrow spectral hole in the inhomogeneous absorption profile in these materials as a frequency reference can dramatically improve laser stability. We review our work on laser frequency and phase stabilization and report our recent results on using a narrow spectral hole as a passive dynamic spectral filter for laser phase noise suppression, which can dramatically narrow the laser linewidth with or without the requirement of active feedback. - Research highlights: Rare-earth materials offer key properties for quantum memory and signal processing. Physics and properties of rare-earth optical transitions in solids are reviewed. Details of 47 promising optical transitions are tabulated and compared. A new narrow-band dynamic filtering method using spectral hole burning is discussed. Results of successful passive laser phase noise suppression are presented.

  14. Rare earth doped III-nitride semiconductors for spintronic and optoelectronic applications (Conference Presentation)

    Science.gov (United States)

    Palai, Ratnakar

    2016-10-01

    Since last four decades the information and communication technologies are relying on the semiconductor materials. Currently a great deal of attention is being focused on adding spin degree-of-freedom into semiconductor to create a new area of solid-state electronics, called spintronics. In spintronics not only the current but also its spin state is controlled. Such materials need to be good semiconductors for easy integration in typical integrated circuits with high sensitivity to the spin orientation, especially room temperature ferromagnetism being an important desirable property. GaN is considered to be the most important semiconductor after silicon. It is widely used for the production of green, blue, UV, and white LEDs in full color displays, traffic lights, automotive lightings, and general room lighting using white LEDs. GaN-based systems also show promise for microwave and high power electronics intended for radar, satellite, wireless base stations and spintronic applications. Rare earth (Yb, Eu, Er, and Tm) doped GaN shows many interesting optoelectronic and magnetoptic properties e. g. sharp emission from UV through visible to IR, radiation hardness, and ferromagnetism. The talk will be focused on fabrication, optoelectronic (photoluminescence, cathodeluminescence, magnetic, and x-ray photoelectron spectroscopy) properties of some rare earth doped GaN and InGaN semiconductor nanostructures grown by plasma assisted molecular beam epitaxy (MBE) and future applications.

  15. Doping of graphite by an alkaline-earth metal to reduce the work function

    NARCIS (Netherlands)

    Baturin, AS; Nikolski, KN; Knyazev, AI; Tchesov, RG; Sheshin, EP

    2004-01-01

    A technique for reducing the work function of a field-emission graphite cathode by doping it by an alkaline-earth metal (barium) is suggested. A model of formation of a barium monolayer on the cathode surface is proposed. Field-emission tests show that the operating voltage of the doped cathode is l

  16. Rare Earth Doped Silica Nanoparticles via Thermolysis of a Single Source Metallasilsesquioxane Precursor

    Science.gov (United States)

    Davies, Gemma-Louise; O'Brien, John; Gun'Ko, Yurii K.

    2017-04-01

    Rare earth metal doped silica nanoparticles have significant advantages over traditional organic dyes and quantum dots. Silsesquioxanes are promising precursors in the production of silica nanoparticles by thermolysis, due to their structural similarities with silica materials. This manuscript describes the production of a new Eu3+-based metallasilsesquioxane species and its use as a single source precursor in the thermolytic production of luminescent rare earth metal doped silica nanoparticles with characteristic emission in the visible region of the spectrum.

  17. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    OpenAIRE

    2011-01-01

    International audience; Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium ...

  18. Multilayer Thermal Barrier Coating (TBC) Architectures Utilizing Rare Earth Doped YSZ and Rare Earth Pyrochlores

    Science.gov (United States)

    Schmitt, Michael P.; Rai, Amarendra K.; Bhattacharya, Rabi; Zhu, Dongming; Wolfe, Douglas E.

    2014-01-01

    To allow for increased gas turbine efficiencies, new insulating thermal barrier coatings (TBCs) must be developed to protect the underlying metallic components from higher operating temperatures. This work focused on using rare earth doped (Yb and Gd) yttria stabilized zirconia (t' Low-k) and Gd2Zr2O7 pyrochlores (GZO) combined with novel nanolayered and thick layered microstructures to enable operation beyond the 1200 C stability limit of current 7 wt% yttria stabilized zirconia (7YSZ) coatings. It was observed that the layered system can reduce the thermal conductivity by approximately 45 percent with respect to YSZ after 20 hr of testing at 1316 C. The erosion rate of GZO is shown to be an order to magnitude higher than YSZ and t' Low-k, but this can be reduced by almost 57 percent when utilizing a nanolayered structure. Lastly, the thermal instability of the layered system is investigated and thought is given to optimization of layer thickness.

  19. Influence of Rare Earth Doping on the Structural and Catalytic Properties of Nanostructured Tin Oxide

    Directory of Open Access Journals (Sweden)

    Maciel Adeilton

    2008-01-01

    Full Text Available AbstractNanoparticles of tin oxide, doped with Ce and Y, were prepared using the polymeric precursor method. The structural variations of the tin oxide nanoparticles were characterized by means of nitrogen physisorption, carbon dioxide chemisorption, X-ray diffraction, and X-ray photoelectron spectroscopy. The synthesized samples, undoped and doped with the rare earths, were used to promote the ethanol steam reforming reaction. The SnO2-based nanoparticles were shown to be active catalysts for the ethanol steam reforming. The surface properties, such as surface area, basicity/base strength distribution, and catalytic activity/selectivity, were influenced by the rare earth doping of SnO2and also by the annealing temperatures. Doping led to chemical and micro-structural variations at the surface of the SnO2particles. Changes in the catalytic properties of the samples, such as selectivity toward ethylene, may be ascribed to different dopings and annealing temperatures.

  20. Research on photodarkening in rare earth doped fibers

    Institute of Scientific and Technical Information of China (English)

    CHENG Yu

    2012-01-01

    Samarium doped aluminosilicate fiber was fabricated by modified chemical vapor deposition (MCVD) process.The optical properties of this fiber were characterized by white light source and OSA.The photodarkening property of the fiber was measured by an Ar+ laser.The experiment results proved that the samarium doped aluminosilicate fiber had better photodarkening resistance than that of the samarium doped germanosilicate fiber.A brief explanation showed that the photodarkening loss could be reduced by changing the fiber core's material from germanosilicate to aluminosilicate.Samarium doped aluminosilicate fiber was very promising for the red fiber laser application.

  1. Dynamics of dipolar defects in rare earth-doped alkaline-earth fluoride crystals

    Science.gov (United States)

    Charnock, Forrest Taylor

    Alkaline-earth fluoride crystals such as SrF2 provide an excellent sample material for investigating the physics of point defects in crystal lattices. High quality crystals are easily grown, and they readily accept many dopant ions into the lattice, particularly rare earth ions. Rare earth dopant ions (typically trivalent) occupy substitutional sites in the lattice by replacing a Sr2+ ion. Due to the extra charge of the rare earth ion, charge compensation is often provided by an extra fluoride ion (F--) located in a nearby interstitial position. If located in the nearest-neighbor (nn) interstitial position, it forms a defect with C4n symmetry; if located in the next-nearest-neighbor (nnn) intersitial position, it forms a defect with C3n symmetry. Given sufficient thermal energy, this interstitial F ion can move to adjacent interstitial sites and hence reorient the defect. The rate w at which the ion moves from one interstitial site to another is well described by a simple Arrhenius expression: w=n0e-E/kT , where n0 is the attack frequency of the F-- and E is the activation energy. This motion can profoundly affect both the electronic polarizability of the material and the polarization of light emitted or absorbed by the rare earth ion. This thesis describes the normal mode motion of interstitial ions which may occupy either nn or nnn interstitial sites. Using electron paramagnetic resonance (EPR), I observed the relative populations of nn and nnn defects in SrF2 doped with Gd3+ as a function of temperature. These measurements show that dipolar reorientation of the nnn F occurs through the nn interstitial position. Not all interstitial F-- motion is thermally driven. Fluorescence depolarization measurements of SrF2:Pr3+ indicate that optically stimulating a Pr3+ may induce interstitial motion of a nn F--. Such motion was confirmed by showing that nn defects in SrF2:Pr3+ may be polarized at very low temperatures when the sample is illuminated with resonant light. I

  2. Spectroscopy and dynamics of rare earth doped fluorides

    NARCIS (Netherlands)

    Ebens, Willem Omco

    1995-01-01

    The defect structure of RE doped Fluorides has been studied along with the conductivity properties, using a variety of techniques, both experimental and theoretical. Two systems have been studied in detail, which represent two kinds of defect states for RE doped SrFr. The system SrFr:CeF, has been t

  3. Electrical, optical, and electronic properties of Al:ZnO films in a wide doping range

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, Ilaria; Valeri, Sergio [CNR, Istituto Nanoscienze, S3, Via G. Campi 213/a, 41125 Modena (Italy); Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia, Via G. Campi 213/a, 41125 Modena (Italy); Benedetti, Stefania, E-mail: stefania.benedetti@unimore.it; Bona, Alessandro di [CNR, Istituto Nanoscienze, S3, Via G. Campi 213/a, 41125 Modena (Italy); Lollobrigida, Valerio [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome, Italy and Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Perucchi, Andrea; Di Pietro, Paola [INSTM Udr Trieste-ST and Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, I-34012 Trieste (Italy); Lupi, Stefano [CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza, P.le Aldo Moro 2, I-00185 Roma (Italy); Torelli, Piero [Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, I-34149 Trieste (Italy)

    2015-10-28

    The combination of photoemission spectroscopies, infrared and UV-VIS absorption, and electric measurements has allowed to clarify the mechanisms governing the conductivity and the electronic properties of Al-doped ZnO (AZO) films in a wide doping range. The contribution of defect-related in-gap states to conduction has been excluded in optimally doped films (around 4 at. %). The appearance of gap states at high doping, the disappearance of occupied DOS at Fermi level, and the bands evolution complete the picture of electronic structure in AZO when doped above 4 at. %. In this situation, compensating defects deplete the conduction band and increase the electronic bandgap of the material. Electrical measurements and figure of merit determination confirm the high quality of the films obtained by magnetron sputtering, and thus allow to extend their properties to AZO films in general.

  4. The Progress of TiO Nanocrystals Doped with Rare Earth Ions

    Directory of Open Access Journals (Sweden)

    Hai Liu

    2012-01-01

    Full Text Available In the past decades, TiO2 nanocrystals (NCs have been widely studied in the fields of photoelectric devices, optical communication, and environment for their stability in aqueous solution, being nontoxic, cheapness, and so on. Among the three crystalline phases of TiO2, anatase TiO2 NCs are the best crystallized phase of solar energy conversion. However, the disadvantages of high band gap energy (3.2 ev and the long lifetime of photogenerated electrons and holes limit its photocatalytic activity severely. Therefore, TiO2 NCs doped with metal ions is available way to inhibit the transformation from anatase to rutile. Besides, these metal ions will concentrate on the surface of TiO2 NCs. All above can enhance the photoactivity of TiO2 NCs. In this paper, we mainly outlined the different characterization brought about in the aspect of nanooptics and photocatalytics due to metal ions added in. Also, the paper mainly concentrated on the progress of TiO2 NCs doped with rare earth (RE ions.

  5. Spectroscopic analyses of trivalent rare-earth ions doped in different host materials

    Science.gov (United States)

    Chandrasekharan, Sreerenjini

    2011-12-01

    Trivalent rare-earth (RE3+) ions of 4f n electronic configurations are found to possess potential applications in the field of optoelectronic and biophotonic technologies owing to their unique optical properties. They have been used as optical activators in a large number of solid-state laser host materials due to their rich energy level structure. This work focuses on the spectroscopic study of two RE 3+ ions, namely, trivalent erbium and neodymium (Er3+ and Nd3+, respectively), embedded in some important single crystal and nanocrystalline host materials including yttrium orthoaluminate (YAlO3), erbium oxide (Er2O3), yttrium oxide (Y2O3) and a combined host system of Y2O 3 and a vinyl polymer named Polymethyl Methacrylate (PMMA). Each one of these host materials are known to be unique for their characteristic properties such as chemical durability, thermal stability, optical clarity, wide band gaps, biocompatibility, and success as phosphors in various optoelectronic devices. The complete material characterization has been performed through morphology analyses using advanced microscopy techniques and spectroscopic analyses of the characteristic absorption and emission spectra by applying phenomenological crystal-field splitting and Judd-Ofelt techniques. The important spectroscopic parameters such as line strengths, radiative decay rates, and branching ratios have been obtained for the intermanifold transitions from the upper multiplets to the corresponding lower-lying multiplet manifolds 2S+1LJ of RE3+ ions doped in various host systems. Using the radiative decay rates, radiative life times are obtained and the experimental analyses of the fluorescent spectra yield the measured lifetimes of emitting metastable states. Finally, the results are compared with the previously published set of values for the same ions doped in similar type of host systems. Detailed analyses of the spectroscopic properties show that the studied systems RE3+ doped single crystals and

  6. Raman and Rietveld structural characterization of sintered alkaline earth doped ceria

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira Junior, Jose Marcio; Brum Malta, Luiz Fernando; Garrido, Francisco M.S. [Departamento de Quimica Inorganica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 149, Centro de Tecnologia, Bloco A, room 632, CEP 68563, 21941-909 Rio de Janeiro, RJ (Brazil); Ogasawara, Tsuneharu [Programa de Engenharia Metalurgica e de Materiais, Coordenacao dos Programas de Pos - Graduacao de Engenharia, Centro de Tecnologia, Universidade Federal do Rio de Janeiro, Ilha do Fundao, CEP 68505, 21941-972 Rio de Janeiro, RJ (Brazil); Medeiros, Marta Eloisa, E-mail: chico@iq.ufrj.br [Departamento de Quimica Inorganica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 149, Centro de Tecnologia, Bloco A, room 632, CEP 68563, 21941-909 Rio de Janeiro, RJ (Brazil)

    2012-08-15

    Nanocrystalline calcium and strontium singly doped ceria and co-doped ceria materials for solid electrolytes were prepared via a hydrothermal route. The effect of the hydrothermal treatment time on the solid solution composition was evaluated. Sr doped ceria was the most difficult to form, due to the Sr{sup 2+} large ionic radius. The small crystal size (12-16 nm) of powders allowed sintering into dense ceramic pellets at 1350 Degree-Sign C for 5 h. Raman spectroscopy evidenced a great lattice distortion for Sr doped and co-doped ceria materials, explaining the deterioration of the electrical properties for these ceramics. Besides that, a second phase was detected for Sr doped ceria pellet by using X-ray powder diffraction and Rietveld refinement of XRD data. Impedance measurements showed that Ca-doped ceria behaves as the best ionic conductor ({sigma}{sub g} 390 Degree-Sign C = 1.0 Multiplication-Sign 10{sup -3} S cm{sup -1}) since the nominal composition was achieved; on the other hand, Sr doped ceria performed as resistive materials since Sr incorporation into ceria lattice was critical. These results enhance the close interlace between electrical performance and chemical composition of alkaline earth doped ceria. -- Highlights: Black-Right-Pointing-Pointer Hydrothermally synthesized calcium doped ceria nanoparticles. Black-Right-Pointing-Pointer Incorporation of alkaline earth dopant into ceria lattice. Black-Right-Pointing-Pointer Raman and Rietveld structural characterization. Black-Right-Pointing-Pointer Calcium doped ceria ceramic pellets with high ionic conductivity. Black-Right-Pointing-Pointer Problems associated with the Sr{sup 2+} incorporation into ceria lattice.

  7. NIR persistent luminescence of lanthanide ion-doped rare-earth oxycarbonates: the effect of dopants.

    Science.gov (United States)

    Caratto, Valentina; Locardi, Federico; Costa, Giorgio Andrea; Masini, Roberto; Fasoli, Mauro; Panzeri, Laura; Martini, Marco; Bottinelli, Emanuela; Gianotti, Enrica; Miletto, Ivana

    2014-10-22

    A series of luminescent rare-earth ion-doped hexagonal II-type Gd oxycarbonate phosphors Gd2-xRExO2CO3 (RE = Eu(3+), Yb(3+), Dy(3+)) have been successfully synthesized by thermal decomposition of the corresponding mixed oxalates. The Yb(3+) doped Gd-oxycarbonate has evidenced a high persistent luminescence in the NIR region, that is independent from the temperature and makes this materials particular attractive as optical probes for bioimaging.

  8. Influence of rare earth doping on thermoelectric properties of SrTiO3 ceramics

    Science.gov (United States)

    Liu, J.; Wang, C. L.; Li, Y.; Su, W. B.; Zhu, Y. H.; Li, J. C.; Mei, L. M.

    2013-12-01

    Thermoelectric properties of SrTiO3 ceramics, doped with different rare earth elements, were investigated in this work. It's found that the ionic radius of doping elements plays an important role on thermoelectric properties: SrTiO3 ceramics doped with large rare earth ions (such as La, Nd, and Sm) exhibit large power factors, and those doped with small ions (such as Gd, Dy, Er, and Y) exhibit low thermal conductivities. Therefore, a simple approach for enhancing the thermoelectric performance of SrTiO3 ceramics is proposed: mainly doped with large ions to obtain a large power factor and, simultaneously, slightly co-doped with small ions to obtain a low thermal conductivity. Based on this rule, Sr0.8La0.18Yb0.02TiO3 ceramics were prepared, whose ZT value at 1 023 K reaches 0.31, increasing by a factor of 19% compared with the single-doped counterpart Sr0.8La0.2TiO3 (ZT = 0.26).

  9. Metal enhanced fluorescence in rare earth doped plasmonic core-shell nanoparticles.

    Science.gov (United States)

    Derom, S; Berthelot, A; Pillonnet, A; Benamara, O; Jurdyc, A M; Girard, C; Colas des Francs, G

    2013-12-13

    We theoretically and numerically investigate metal enhanced fluorescence of plasmonic core-shell nanoparticles doped with rare earth (RE) ions. Particle shape and size are engineered to maximize the average enhancement factor (AEF) of the overall doped shell. We show that the highest enhancement (11 in the visible and 7 in the near-infrared) is achieved by tuning either the dipolar or the quadrupolar particle resonance to the rare earth ion's excitation wavelength. Additionally, the calculated AEFs are compared to experimental data reported in the literature, obtained in similar conditions (plasmon mediated enhancement) or when a metal-RE energy transfer mechanism is involved.

  10. Rare-earth doped polymer waveguides and light emitting diodes

    NARCIS (Netherlands)

    Slooff, L.H.

    2001-01-01

    Polymer-based optical waveguide amplifiers offer a low-cost alternative for inorganic waveguide amplifiers. Due to the fact that their refractive index is almost similar to that of standard optical fibers, they can be easily coupled with existing fibers at low coupling losses. Doping the polym

  11. INFLUENCE OF RARE-EARTH DOPING ON THE ELECTRICAL PROPERTIES OF HIGH VOLTAGE GRADIENT ZnO VARISTORS

    Directory of Open Access Journals (Sweden)

    LEI KE

    2013-03-01

    Full Text Available The influence of rare-earth doping on the electrical properties of ZnO varistors was investigated. In a lower doping region, the electrical properties were greatly improved with the increase of rare-earth contents. The highest voltage gradient value of 1968.0 V/mm was obtained with a rare-earth concentration of 0.06 mol. %. The microstructure of samples with different amounts of rare-earth oxides was examined and the notable decrease of grain size was identified as the origin for the increased voltage gradient. The doped rare-earth oxides dissolved at the grain boundaries and the excessive doping reduced the voltage across the single grain/grain boundary from 2.72 V to 0.91 V. The poor electrical properties in a higher doping region resulted from the degeneration of grain boundaries and the decrease of block density.

  12. Influence of inherent strain on the curie temperature of rare earth ion-doped bismuth vanadate

    OpenAIRE

    Sooryanarayana, K; Row, TNG; R. Somashekar; Varma, KBR

    1998-01-01

    X-ray line broadening is found to be an effective parameter to estimate the strain associated with rare earth ion (Gd3+)-doped polycrystalline bismuth vanadate(Bi2VO5.5). The strain increases with increasing Gd3+ concentration. It is anisotropic and found to be maximum in (111) plane. The Curie temperature which is known to decrease with increase in the rare earth ion concentration in these compounds is correlated with increase in strain.

  13. Magneto-optical investigations of rare earth doped sol-gel derived silicate xerogels

    Energy Technology Data Exchange (ETDEWEB)

    Secu, C.E.; Polosan, S. [National Institute of Materials Physics, Optical Processes in Nanostructured Materials Department, P.O. Box MG-7, Bucharest-Magurele, 077125 (Romania); Secu, M., E-mail: msecu@infim.ro [National Institute of Materials Physics, Optical Processes in Nanostructured Materials Department, P.O. Box MG-7, Bucharest-Magurele, 077125 (Romania)

    2011-08-15

    Rare-earth doped xerogels (Eu{sup 3+}, Sm{sup 3+}, Ho{sup 3+}, Pr{sup 3+}) were prepared by using the sol-gel method and their magneto-optical and optical properties have been studied. The Magnetic Circular Dichroism (MCD) spectra are quite similar to those recorded in the RE-doped fluorozirconate glasses; the fine structures shown by the MCD spectra are better resolved compared to the optical absorption spectra. The MCD technique has been correlated with optical measurements in order to investigate the site symmetry in the particular case of Eu{sup 3+}-doped xerogel and oxyfluoride glasses. In the xerogel, coordination symmetry around the Eu{sup 3+} ions is close to D{sub 3h} and is lower in the oxyfluoride glass. - Highlights: > Rare-earth doped xerogels (Eu{sup 3+}, Sm{sup 3+}, Ho{sup 3+}, Pr{sup 3+}) were prepared by the sol-gel method. > MCD and luminescence methods were applied to probe the site symmetry in europium doped xerogel and oxyfluoride glasses. > Rare-earth site symmetry is close to D{sub 3h} in xerogel and is lower in oxyfluoride glass.

  14. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    CERN Document Server

    Blanc, Wilfried; Nguyen, Luan; Bhaktha, S N B; Sebbah, Patrick; Pal, Bishnu P; Dussardier, Bernard

    2011-01-01

    Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporati...

  15. Breaking the low phonon energy barrier for laser cooling in rare-earth doped hosts

    Science.gov (United States)

    Nemova, Galina; Kashyap, Raman

    2011-03-01

    A new approach to cool rare earth doped solids with optical super-radiance (SR) is presented. SR is the coherent, sharply directed spontaneous emission of photons by a system excited with a pulsed laser. We consider an Yb3+ doped ZBLAN sample pumped at the wavelength 1015nm with a rectangular pulsed source with a power of ~700W and duration of 20ns. The intensity of the SR is proportional to the square of the number of excited ions. This unique feature of SR permits an increase in the rate of the cooling process in comparison with the traditional laser cooling of the rare earth doped solids with anti-Stokes spontaneous incoherent radiation (fluorescence). This scheme overcomes the limitation of using only low phonon energy glasses for laser cooling.

  16. Infrared spectroscopy of rare-earth-doped CaFe2As2

    Science.gov (United States)

    Xing, Zhen; Huffman, T. J.; Xu, Peng; Qazilbash, M. M.; Saha, S. R.; Drye, Tyler; Paglione, J.

    2014-03-01

    Recently, rare-earth doping in CaFe2As2 has been used to tune its electronic, magnetic, and structural properties. The substitution of rare-earth ions at the alkaline-earth sites leads to the suppression of the spin-density wave (SDW) phase transition in CaFe2As2. For example, Pr substitution results in a paramagnetic metal in the tetragonal phase that is susceptible to a low temperature structural transition to a collapsed tetragonal phase. However, La-doped CaFe2As2 remains in the uncollapsed tetragonal structure down to the lowest measured temperatures. Both the uncollapsed and collapsed tetragonal structures exhibit superconductivity with maximum Tc reaching 47 K, the highest observed in inter-metallics albeit with a small superconducting volume fraction. In this work, we perform ab-plane infrared spectroscopy of rare-earth-doped CaFe2As2 at different cryogenic temperatures. Our aim is to ascertain the contributions of electron doping and chemical pressure to the charge and lattice dynamics of this iron-arsenide system.

  17. Surface ζ potential and photocatalytic activity of rare earths doped TiO2

    Institute of Scientific and Technical Information of China (English)

    SONG Mianxin; BIAN Liang; ZHOU Tianliang; ZHAO Xiaoyong

    2008-01-01

    The iso-electric point of different rare earths (La, Ce, Y) doped anatase TiO2 was set out, and three organisms with different sur-face electrical properties (methylene blue trihydrate-positive electricity, methyl orange-negative electricity, methyl red-neutral electricity) were selected as photodegradable models. The result showed that the photocatalytic activity of 0.5wt.%Y ions doped anatase TiO2 was better than those of the others. The relationship between Zeta (ζ) potential and the photocatalytic activity of different RE doped anatase TiO2 were also investigated. The Y-doped anatase TiO2 was found with the special two iso-electric points and three ζ potential values.

  18. Structure and distortion of lead fluoride nanocrystals in rare earth doped oxyfluoride glass ceramics.

    Science.gov (United States)

    Ge, Jin; Zhao, Lijuan; Guo, Hui; Lan, Zijian; Chang, Lifen; Li, Yiming; Yu, Hua

    2013-10-28

    A series of rare earth (RE) doped oxyfluoride glasses with the composition of (45-x) SiO2-5Al2O3-40PbF2-10CdF2-xRe2O3 (x = 1, 5, 10, 15) (mol%) were prepared by a traditional melt-quenching method. Glass ceramics (GCs) were obtained after thermal treatment and characterized by X-ray diffraction (XRD) to investigate the nanocrystal structure and distortion. Both the dopant type and the doping level play an important role in the distortion of the PbF2-RE lattice. It is found that a cubic Pb3REF9 phase forms in low doping GCs, a tetragonal PbREF5 phase forms in middle doping GCs and cubic PbRE3F11 forms in high doping GCs. Accordingly, the site symmetry of RE(3+) dopants in β-PbF2 nanocrystal undergoes a transition of Oh···D4h···Oh with the increase of doping level. The change in the ligands coordinating the RE(3+) ions was further illustrated by the optical changes in Yb-doped GCs. This paper provides insights on the nanocrystal structure of RE at the atomic level and tries to make a complete description of the nanocrystal structure and distortion in these glass-ceramic materials, which will benefit the optimization of optical properties.

  19. Widely tunable erbium-doped fiber laser based on multimode interference effect.

    Science.gov (United States)

    Castillo-Guzman, A; Antonio-Lopez, J E; Selvas-Aguilar, R; May-Arrioja, D A; Estudillo-Ayala, J; LiKamWa, P

    2010-01-18

    A widely tunable erbium-doped all-fiber laser has been demonstrated. The tunable mechanism is based on a novel tunable filter using multimode interference effects (MMI). The tunable MMI filter was applied to fabricate a tunable erbium-doped fiber laser via a standard ring cavity. A tuning range of 60 nm was obtained, ranging from 1549 nm to 1609 nm, with a signal to noise ratio of 40 dB. The tunable MMI filter mechanism is very simple and inexpensive, but also quite efficient as a wavelength tunable filter.

  20. Synthesis and Characterization of Titania and Rare Earth Doped Titania Nanoparticles by Sol-gel Process

    Institute of Scientific and Technical Information of China (English)

    LIN Ping; XIAN Chun-ying; MAO Zhi-ping; ZHENG Li-min

    2006-01-01

    Titania sol has been prepared by the sol-gel process with Ti(OC4H9)4 as precursor. TiO2 gel was obtained through hydrolysis and condensation process. Rare earth such as La2O3, CeO2 and Gd2O3 were introduced into the nanostructure TiO2. After TiO2 and rare earth doped TiO2powders were calcined at 400℃, 500℃, 600℃, 700℃ and 800℃ respectively, the characteristic analyses of the TiO2samples were studied by UV-VIS, XRD and TEM etc. It was found that there are some stronger absorption peaks at 200- 325 nm. The rare earth doping can increase the phase transition temperature converting anatase phase into ruttle phase, can decrease the grain size of TiO2particles and can improve the ant1-UV capacity of the coating fabrics.

  1. Creation of trapped electrons and holes in alkaline-earth fluoride crystals doped by rare-earth ions

    Science.gov (United States)

    Radzhabov, E.

    2002-06-01

    Defects in Ce 3+- and Eu 2+-doped alkaline-earth fluorides, created by vacuum ultraviolet (VUV) photons with energy lower than that of the band gap, were investigated by various methods: thermostimulated luminescence, photostimulated luminescence and optical absorption. The CaF 2:Eu 2+ thermoluminescence curves in the range of 60-330 K due to various types of trapped holes were the same after VUV illumination as after X-ray irradiation. Thermoluminescence curves of Ce 3+-doped alkaline-earth fluorides created by VUV illumination or X-ray irradiation were generally similar. However, Vk thermoluminescence peaks were absent in VUV-illuminated CaF 2:Ce 3+ and SrF 2:Ce 3+ crystals. Creation of Ce 2+ characteristic bands was observed in photostimulated luminescence spectra as well as in optical absorption spectra of vacuum ultraviolet-illuminated or X-ray-irradiated Ce 3+-doped crystals. The proposed mechanism of creation of trapped hole and trapped electron defects by vacuum ultraviolet illumination involves charge transfer-type transitions, in which the electron transfers from valence band to an impurity level, lying in the band gap. Comparison of all involved energies of transitions in the crystals investigated shows that the sum of all transition energies is less than that of the band gap by 1-3 eV. This energy difference can be considered as the energy of lattice relaxation around created Ce 2+ or Eu + ions.

  2. Widely tunable short-infrared thulium and holmium doped fluorozirconate waveguide chip lasers.

    Science.gov (United States)

    Lancaster, D G; Gross, S; Withford, M J; Monro, T M

    2014-10-20

    We report widely tunable (≈ 260 nm) Tm(3+) and Ho(3+) doped fluorozirconate (ZBLAN) glass waveguide extended cavity lasers with close to diffraction limited beam quality (M(2) ≈ 1.3). The waveguides are based on ultrafast laser inscribed depressed claddings. A Ti:sapphire laser pumped Tm(3+)-doped chip laser continuously tunes from 1725 nm to 1975 nm, and a Tm(3+)-sensitized Tm(3+):Ho(3+) chip laser displays tuning across both ions evidenced by a red enhanced tuning range of 1810 to 2053 nm. We also demonstrate a compact 790 nm diode laser pumped Tm(3+)-doped chip laser which tunes from 1750 nm to 1998 nm at a 14% incident slope efficiency, and a beam quality of M(2) ≈ 1.2 for a large mode-area waveguide with 70 µm core diameter.

  3. Processing of Transparent Rare Earth Doped Zirconia for High Temperature Light Emission Applications

    Science.gov (United States)

    Hardin, Corey Lee

    The high fracture toughness of stabilized zirconia makes it one of the most widely applicable high temperature structural materials. However, it is not typicality considered for optical applications since the microstructure achieved by traditional processing makes it opaque. The aim of this dissertation is to develop processing methods for the introducing new functionalities of light transparency and light emission (photoluminescence) and to understand the nanostructure-property relationships that make these functionalities possible. A processing study of rare-earth (RE) doped Zirconium Oxide (ZrO2, zirconia) via Current Activated Pressure Assisted Densification (CAPAD) is presented. The role of processing temperature and dopant concentration on the crystal structure, microstructure and properties of the RE: ZrO2 is studied. Microstructural shows sub-100 nm grain size and homogeneous dopant distribution. X-ray diffraction and Raman analysis show that with increased dopant concentration the material changes from monoclinic to tetragonal. Structural analysis shows the material shows high hardness and toughness values 30% greater than similarly processed yttria-stabilized zirconia. Despite birefringence in the tetragonal phase, optical characterization is presented showing the samples are both highly transparent and photo-luminescent. Special attention is paid to analyzing structural and photoluminescence development during densification, as well as the role of oxygen vacancies on the optical properties of the densified material. This material is shown to be a promising candidate for a number of applications including luminescence thermometry and high temperature light emission.

  4. Alkaline earth metal doped tin oxide as a novel oxygen storage material

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Qiang, E-mail: dong@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan); Yin, Shu; Yoshida, Mizuki; Wu, Xiaoyong; Liu, Bin [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan); Miura, Akira; Takei, Takahiro; Kumada, Nobuhiro [Department of Research Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Miyamae cho-7, Kofu 400-8511 (Japan); Sato, Tsugio [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan)

    2015-09-15

    Alkaline earth metal doped tin oxide (SnO{sub 2}) hollow nanospheres with a diameter of 50 nm have been synthesized successfully via a facial solvothermal route in a very simple system composed of only ethanol, acetic acid, SnCl{sub 4}·5H{sub 2}O and A(NO{sub 3}){sub 2}·xH{sub 2}O (A = Mg, Ca, Sr, Ba). The synthesized undoped SnO{sub 2} and A-doped SnO{sub 2} hollow nanospheres were characterized by the oxygen storage capacity (OSC), X-ray diffraction, transmission electron microscopy and the Brunauer–Emmet–Teller (BET) technique. The OSC values of all samples were measured using thermogravimetric-differential thermal analysis. The incorporation of alkaline earth metal ion into tin oxide greatly enhanced the thermal stability and OSC. Especially, Ba-doped SnO{sub 2} hollow nanospheres calcined at 1000 °C for 20 h with a BET surface area of 61 m{sup 2} g{sup −1} exhibited the considerably high OSC of 457 μmol-O g{sup −1} and good thermal stability. Alkaline earth metal doped tin oxide has the potential to be a novel oxygen storage material.

  5. Luminescence properties or rare earth doped III-V and II- VI semiconductors

    Science.gov (United States)

    Alshawa, Amer Kamal

    Two novel step impact optical devices have been proposed by H. J. Lozykowski, the step impact electroluminescence device (SIED) and the step photon amplifier converter (SPAC). The realization of the proposed devices requires systematic study of the optical properties of rare earth doped semiconductors. The experimental data is explained using a kinetics model of energy transfer from the host lattice to the localized core excited states of rare earth isoclectronic structured traps (REI-trap). The numerically simulated lun-finescence rise and decay times show a good general quantitative agreement with experimental data, over a wide range of generation rates. A new quenching mechanism of ytterbium luminescence involving Yb and Fe ions is proposed. Detailed experimental and theoretical studies of the electrolurninescence excitation mechanism of Yb3+ in InP are presented. The electroluminescence (EL) spectra and the kinetics of Yb implanted InP are investigated under pulsed and dc excitations at different temperatures. The plot of natural logarithm (In) of I versus V-1/2 indicates that the direct impact excitation mechanism is a dominant process. A systematic study of the effect of oxygen on ytterbium 4f-4f emission by coimplanting Yb and O into InP is performed. The PL spectra and kinetic processes of InP: Yb and InP: (Yb+O) are recorded as a function of temperature, excitation intensity and annealing temperature and duration. No luminescence was observed after oxygen co-implantation and that is because the exciton bound to a YbIn-OP complex center will not have sufficient energy to excite the core Yb 4f electrons. The photoluminescence spectra and kinetics of Nd- and Yb-implanted CdS were investigated as a function of excitation intensity and temperature. The ac electroluminescence of thulium doped ZnS embedded in boric acid matrix was investigated as a function of voltage, frequency and temperature. The plot of In(I) versus V-1/2 shows a straight line characteristic

  6. Ultraviolet to visible frequency-conversion properties of rare earths doped glass ceramics

    Institute of Scientific and Technical Information of China (English)

    Y. Hatefi; N. Shahtahmasebi; A. Moghimi; E. Attaran

    2011-01-01

    Nd3+, Eu3+ and Tb3+ ions doped transparent chlorophosphate glass ceramics were prepared and their fiequency-conversion properties were studied. X-ray diffraction (XRD) patterns evidenced the formation of expected halide nanocrystals. The absorption, excitation and emission spectra investigation indicated that some of rare earth (RE) ions were trapped in low phonon energy halide nanocrystals, and therefore an efficient down frequency-conversion was observed. The comparative spectroscopic studies of RE doped samples suggested that the glass ceramics systems are potentially applicable as efficient ultraviolet to visible frequency-conversion photonics materials.

  7. Luminescent dye-doped or rare-earth-doped monodisperse silica nanospheres as efficient labels in DNA microarrays

    Science.gov (United States)

    Enrichi, F.; Riccò, R.; Meneghello, A.; Pierobon, R.; Marinello, F.; Schiavuta, P.

    2009-08-01

    Luminescent nanoparticles are gaining more and more interest in bio-labeling and bio-imaging applications, like for example DNA microarray. This is a high-throughput technology used for detection and quantification of nucleic acid molecules and other ones of biological interest. The analysis is resulting by specific hybridization between probe sequences deposited in array and a target ss-DNA usually expressed by PCR and functionalized by a fluorescent dye. These organic labels have well known disadvantages like photobleaching and limited sensitivity. Quantum dots may be used as alternatives, but they present troubles like blinking, toxicity and excitation wavelengths out of the usual range of commercial instruments, lowering their efficiency. Therefore in this work we investigate a different strategy, based on the use of inorganic silica nanospheres incorporating standard luminescent dyes or rare earth doped nanocrystals. In the first case it is possible to obtain a high luminescence emission signal, due to the high number of dye molecules that can be accommodated into each nanoparticle, reduced photobleaching and environmental protection of the dye molecules thanks to the encapsulation in the silica matrix. In the second case, rare earths exhibit narrow emission bands (easy identification), large Stokes shifts (efficient discrimination of excitation and emission) and long luminescence lifetimes (possibility to perform time-delayed analysis) which can be efficiently used for the improvement of signal to noise ratio. The synthesis and characterization of good luminescent silica spheres either by organic dye-doping or by rare-earth-doping are investigated and reported. Moreover, their application in the DNA microarray technology in comparison to the use of standard molecular fluorophores or commercial quantum dots is discussed. The cheap and easy synthesis of these luminescent particles, the stability in water, the surface functionalization and bio

  8. Tunable Solid-State Quantum Memory Using Rare-Earth-Ion-Doped Crystal, Nd3(+):GaN

    Science.gov (United States)

    2017-04-26

    Research Initiative was to work on developing solid-state quantum memory using cryogenically cooled rare- earth -ion-doped crystal, Nd3+:GaN. The samples...Initiative (DRI) was to work on developing solid-state quantum memory using cryogenically cooled rare- earth -ion- doped crystal, Nd3+:GaN. The samples were...Caltech group has been working in the area of quantum information of rare- earth doped solids for a number of years and is well equipped to perform

  9. Benefit of Rare-Earth "Smart Doping" and Material Nanostructuring for the Next Generation of Er-Doped Fibers

    Science.gov (United States)

    Savelii, Inna; Bigot, Laurent; Capoen, Bruno; Gonnet, Cedric; Chanéac, Corinne; Burova, Ekaterina; Pastouret, Alain; El-Hamzaoui, Hicham; Bouazaoui, Mohamed

    2017-03-01

    Erbium-doped fiber amplifiers (EDFAs) for harsh environments require to develop specific fabrication methods of Er 3+-doped fibers (EDFs) so as to limit the impact of radiation-induced absorption. In this context, a compromise has to be found between the concentration of Erbium and the glass composition. On the one hand, high concentration of Er 3+ ions helps to reduce the length of the EDF and hence the cumulated attenuation but generally leads to luminescence quenching mechanisms that limit the performances. On the other hand, so as to avoid such quenching effect, glass modifiers like Al 3+ or P 5+ ions are used in the fabrication of commercial EDFs but are not suitable for applications in harsh environment because these glass modifiers are precursors of radiation-induced structural defects and consequently of optical losses. In this work, we investigate the concept of smart doping via material nanostructuring as a way to fabricate more efficient optical devices. This approach aims at optimizing the glass composition of the fiber core in order to use the minimal content of glass modifiers needed to reach the suited level of performances for EDFA. Er 3+-doped alumina nanoparticles (NPs), as precursor of Er 3+ ions in the preform fabrication process, were used to control the environment of rare-earth ions and their optical properties. Structural and optical characterizations of NP-doped preforms and optical fibers drawn from such preforms demonstrate the interest of this approach for small concentrations of aluminum in comparison to similar glass compositions obtained by a conventional technique.

  10. Benefit of Rare-Earth "Smart Doping" and Material Nanostructuring for the Next Generation of Er-Doped Fibers.

    Science.gov (United States)

    Savelii, Inna; Bigot, Laurent; Capoen, Bruno; Gonnet, Cedric; Chanéac, Corinne; Burova, Ekaterina; Pastouret, Alain; El-Hamzaoui, Hicham; Bouazaoui, Mohamed

    2017-12-01

    Erbium-doped fiber amplifiers (EDFAs) for harsh environments require to develop specific fabrication methods of Er (3+)-doped fibers (EDFs) so as to limit the impact of radiation-induced absorption. In this context, a compromise has to be found between the concentration of Erbium and the glass composition. On the one hand, high concentration of Er (3+) ions helps to reduce the length of the EDF and hence the cumulated attenuation but generally leads to luminescence quenching mechanisms that limit the performances. On the other hand, so as to avoid such quenching effect, glass modifiers like Al (3+) or P (5+) ions are used in the fabrication of commercial EDFs but are not suitable for applications in harsh environment because these glass modifiers are precursors of radiation-induced structural defects and consequently of optical losses. In this work, we investigate the concept of smart doping via material nanostructuring as a way to fabricate more efficient optical devices. This approach aims at optimizing the glass composition of the fiber core in order to use the minimal content of glass modifiers needed to reach the suited level of performances for EDFA. Er (3+)-doped alumina nanoparticles (NPs), as precursor of Er (3+) ions in the preform fabrication process, were used to control the environment of rare-earth ions and their optical properties. Structural and optical characterizations of NP-doped preforms and optical fibers drawn from such preforms demonstrate the interest of this approach for small concentrations of aluminum in comparison to similar glass compositions obtained by a conventional technique.

  11. Effect of cobalt on the magnetoresistance characteristics of rare-earth doped manganites

    Institute of Scientific and Technical Information of China (English)

    Jiang Kuo; Gong Sheng-Kai

    2009-01-01

    The effect of cobalt-doping on the magnetic, transport and magnetoresistance characteristics of La1-xSrxMnO3 was investigated. The results show that the magnetoelectric property of rare-earth doped manganites is greatly affected by substitution of Co for Mn sites. The Curie temperature as well as the magnetic moment decreases with the increase of doping concentration, and the samples exhibit obvious characteristics of the spin glass state. Moreover,the magnetoresistance is evidently modulated by doping concentration, and the relevant temperature dependence is also suppressed. In addition, low-temperature magnetorcsistance is significantly promoted as doping concentration increases, which renders a value of approximately 50% in the temperature range of 5-200 K and varies within 12.5%. It can be attributed to the effect of spin scattering, induced by cobalt doping, on the itinerant electrons of Mn ions, thus introducing a spin-disorder region into the ferromagnetic region of double-exchange interaction between neighbouring Mn3+ and Mn 4+ ions.

  12. Ionoluminescence of trivalent rare-earth-doped strontium barium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Calvo del Castillo, H. [Departamento de Geologia y Geoquimica, Universidad Autonoma de Madrid, Modulo C-VI, Campus de Cantoblanco, 28049 Cantoblanco, Madrid (Spain); Universidad Nacional Automoma de Mexico, Instituto de Fisica, 04510 Ciudad Universitaria, Mexico D.F. (Mexico); Ruvalcaba, J.L. [Universidad Nacional Automoma de Mexico, Instituto de Fisica, 04510 Ciudad Universitaria, Mexico D.F. (Mexico); Bettinelli, M.; Speghini, A. [Dipartimento Scientifico e Tecnologico, Universita di Verona and INSTM, UdR Verona, Ca Vignal, Strada Le Grazie 15, I-37134 Verona (Italy); Barboza Flores, M. [Centro de Investigacion en Fisica, Universidad de Sonora, Hermosillo, Sonora (Mexico); Calderon, T. [Departamento de Geologia y Geoquimica, Universidad Autonoma de Madrid, Modulo C-VI, Campus de Cantoblanco, 28049 Cantoblanco, Madrid (Spain)], E-mail: tomas.calderon@uam.es; Jaque, D.; Garcia Sole, J. [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, 28049 Cantoblanco, Madrid (Spain)

    2008-05-15

    Ionoluminescence spectra for different rare-earth ion (Pr{sup 3+} and Eu{sup 3+})-activated Sr{sub x}Ba{sub 1-x}Nb{sub 2}O{sub 6} strontium barium niobate crystals (x=0.33 and 0.60) have been induced with a 3 MeV proton beam for a variety of beam current intensities (45, 40 and 20 nA). The proton-beam induced luminescent spectra have shown features associated with the presence of the rare-earth ion and some spectral features mostly related to the host crystal, which appear only for high beam current intensities. We have compared the ionoluminescence results to those obtained under UV light excitation (photoluminescence technique) where a direct excitation of the band gap would occur.

  13. Structure and spectroscopy of rare earthDoped lead phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, Wojciech A., E-mail: wojciech.pisarski@us.edu.pl [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Żur, Lidia [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Goryczka, Tomasz [University of Silesia, Institute of Materials Science, Bankowa 12, 40-007 Katowice (Poland); Sołtys, Marta; Pisarska, Joanna [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland)

    2014-02-25

    Highlights: • Lead phosphate glasses doped with rare earth ions were prepared. • The local structure was examined using X-ray diffraction and spectroscopic methods. • Different structural phosphate groups are present in lead phosphate glasses. • The electron–phonon coupling strength and phonon energy of the glass host was determined. • Several observed emission bands are due to 4f–4f electronic transitions of rare earth ions. -- Abstract: Lead–gallium phosphate glasses doped with rare the earth ions (Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}, Er{sup 3+}) were synthesized. The structure of obtained glasses was examined by means of use: X-ray diffraction (XRD), nuclear magnetic resonance ({sup 207}Pb and {sup 31}P NMR), fourier transform infrared (FT-IR) and Raman spectroscopy. In contrast to fully amorphous Ln-doped samples (Ln = Eu, Dy, Tb), in Er-doped sample the GaPO{sub 4} crystalline phase was identified. It was found from the NMR, FT-IR and Raman spectroscopic techniques that, different structural phosphate groups were present in lead phosphate glasses. Based on absorption measurements, the UV–VIS cut-off wavelength for lead phosphate glass was determined and its value is close to 305 nm. Excitation and emission spectra of rare earths were also detected. From excitation spectra of Eu{sup 3+} the electron–phonon coupling strength and phonon energy of the glass host were determined. Due to 4f{sup 6}–4f{sup 6} (Eu{sup 3+}), 4f{sup 8}–4f{sup 8} (Tb{sup 3+}), 4f{sup 9}–4f{sup 9} (Dy{sup 3+}) and 4f{sup 11}–4f{sup 11} (Er{sup 3+}) electronic transitions of trivalent rare earth ions several luminescence bands were stated.

  14. Effects of defects and doping on wide band gap ferromagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Pearton, S.J.; Abernathy, C.R.; Thaler, G.T.; Frazier, R.; Ren, F.; Hebard, A.F.; Park, Y.D.; Norton, D.P.; Tang, W.; Stavola, M.; Zavada, J.M.; Wilson, R.G

    2003-12-31

    Both ion implantation and epitaxial crystal growth provide convenient methods of introducing transition metals such as Mn,Cr,Fe,Ni and Co into GaN, GaP, SiC and ZnO for creating dilute magnetic semiconductors exhibiting room temperature ferromagnetism. In this paper we review progress in wide band gap ferromagnetic semiconductors and the role of defects and doping on the resulting magnetic properties.

  15. Raman spectral analysis of TiO2 thin films doped with rare-earth samarium.

    Science.gov (United States)

    Yang, Chang-Hu; Ma, Zhong-Quan

    2012-08-01

    TiO(2) thin films doped with rare-earth samarium were prepared on a quartz plate by the sol-gel/spin-coating technique. The samples were annealed at 700 °C to 1100 °C, and the Raman spectra of the samples were obtained. Analyses of Raman spectra show that samarium doping can inhibit the anatase-rutile phase transition. Samarium doping can refine grains of TiO(2) thin films and increase the internal stress, thereby preventing lattice vibration. Nanocrystalline TiO(2) thin films obviously show the phonon confinement effect, i.e., the blueshift of characteristic Raman peak and full width at half-height increase, and the peak shapes asymmetrically broaden with a decrease in the grain sizes of the samples.

  16. Nanocrystalline rare earth fluorides doped with Pr3+ions

    Institute of Scientific and Technical Information of China (English)

    Marcin Runowski; Stefan Lis

    2016-01-01

    Praseodymium(III) doped CeF3, CeF3:Gd, LaF3, GdF3 and YF3 inorganic fluorides were precipitated in an aqueous, sur-factant-free solution, using NH4F as a source of fluoride ions. The as-prepared products were subjected to a hydrothermal treatment, which led to the formation of crystalline nanoluminophores, composed of spherical (≈30 nm) and elongated (≈40–200 nm) nanos-tructures. Due to the presence of Pr3+ions, the synthesized nanomaterials showed yellow luminescence under a blue light irradiation. The nanoluminophore based on the YF3 host revealed the most promising spectroscopic properties, i.e., bright and intensive emission, hence it was investigated in detail. The photophysical properties of the nanomaterials obtained were studied by powder X-ray diffrac-tion (XRD), transmission electron microscopy (TEM) and spectrofluorometry, i.e., measurements of excitation/emission spectra and luminescence decay curves.

  17. Rare-earth doped (alpha'/beta')-sialon ceramics

    CERN Document Server

    Gajum, N R

    2001-01-01

    combination of light and heavy rare-earth (Yb-Nd and Gd-Nd), and then pressureless sintered and compared with the single cation materials. Materials in the as sintered state were composed of a high alpha' sialon content with a minor amount of beta' sialon and 12H A1N polytype indicating that the heavy rare-earth (which is the principal alpha' stabilizer) has a dominant effect although EDAX analysis confirmed the presence of both cations (light and heavy) within the alpha' structure. The research also compared, and developed an understanding of, the thermal stability of alpha'-sialon using single Yb or mixed cations. The Yb single cation alpha'/beta' materials exhibited excellent stability over a range of temperature (1200 - 1600 deg C) and for different periods of time up to 168 hrs. The heat treatments result in the crystallisation of the residual phase as a Yb garnet phase which formed at approx 1300 deg C. The mixed cation alpha'/beta' materials showed some alpha'-beta' transformation. The transformation w...

  18. Capillary-force-induced formation of luminescent polystyrene/(rare-earth-doped nanoparticle) hybrid hollow spheres.

    Science.gov (United States)

    Chen, Min; Xie, Lin; Li, Fuyou; Zhou, Shuxue; Wu, Limin

    2010-10-01

    This paper presents a "one-pot" procedure to synthesize polystyrene/(rare-earth-doped nanoparticles) (PS/REDNPs) hybrid hollow spheres via the in situ diffusion of organic core into inorganic shell under strong capillary force. In this approach, when carboxyl-capped PS colloids were deposited by different REDNPs in aqueous medium, such as LaF3:Eu3+, LaF3:Ce3+-Tb3+, and YVO4:Dy3+, PS/REDNPs inorganic-organic hybrid hollow spheres could be directly obtained via the in situ diffusion of core PS chains into the voids between rare-earth-doped nanoparticles through the strong capillary force. Not only is the synthetic procedure versatile and very simple, but also the obtained hybrid hollow spheres are hydrophilic and luminescent and could be directly used in chemical and biological fields.

  19. Enhanced Laser Cooling of Rare-Earth-Ion-Doped Glass Containing Nanometer-Sized Metallic Particles

    Institute of Scientific and Technical Information of China (English)

    JIA You-Hun; ZHONG Biao; YIN Jian-Ping

    2009-01-01

    The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb3+-doped ZBLAN as example, the cooling power and heat-light converting efficiency are calculated. It is finally concluded that the absorption and the fluorescence are greatly enhanced in these composite materials, the cooling power is increased compared to the bulk material.

  20. Preparation and up-conversion luminescence of 8 nm rare-earth doped fluoride nanoparticles.

    Science.gov (United States)

    Tikhomirov, V K; Mortier, M; Gredin, P; Patriarche, G; Görller-Walrand, C; Moshchalkov, V V

    2008-09-15

    Free-standing, 8 nm diameter, rare-earth doped nanoparticles Re(10)Pb(25)F(65) have been prepared, where Re stands for either single rare-earth ion, such as Er(3+), Yb(3+), Eu(3+), Dy(3+), Ho(3+), Tm(3+) or combinations of those ions. The nanoparticles have been extracted by chemical etching from the oxyfluoride nano-glass-ceramics template and analyzed by transmission electron microscope with energy dispersion spectroscopy. The nanoparticles show durable up-conversion photoluminescence, which is neither concentration nor impurity quenched after 6 months ageing in ambient atmosphere. High doping levels in these nanoparticles ensure high, up to 15%, quantum yield of up-conversion luminescence.

  1. Preparation of Rare Earth Doped Alumina-Siloxane Gel and Its ER Effect

    Institute of Scientific and Technical Information of China (English)

    李幼荣; 张明; 周兰香; 邱关明; 井上真一; 冈本宏

    2002-01-01

    Poly(methyl methacrylate) (PMMA) was used to wrap alumina-siloxane sol through emulsion polymerization. A kind of suspensions with notable ER effect was produced by fully mixing the prepared microcapsule with silicon oil. Meanwhile a series of PMMA wrapped alumina-siloxane gel doped with rare earths was obtained and its ER effect was tested, like viscosity of different rare earth ion doped samples in different powder concentrations and at different temperatures, at the same time, leak current density and dielectric constant were measured. Results show that the ER effect of this suspension is remarkable, and its stability is much better. The condition of emulsion polymerization and the mechanism of effect are discussed.

  2. Luminescence quenching in rare-earth-ion-doped $Al_2O_3$ lasers and its influence on relaxation oscillation frequency

    NARCIS (Netherlands)

    Agazzi, L.; Bernhardi, E.H.; Wörhoff, K.; Pollnau, M.

    2012-01-01

    The impact of luminescence quenching on rare-earth-ion doped lasers is investigated, and we show that the expression for the relaxation oscillation frequency needs to be modified to take the quenching properly into account.

  3. Luminescence quenching in rare-earth-ion-doped Al2O3 lasers and its influence on relaxation oscillation frequency

    NARCIS (Netherlands)

    Agazzi, L.; Bernhardi, Edward; Worhoff, Kerstin; Pollnau, Markus

    The impact of luminescence quenching on rare-earth-ion doped lasers is investigated, and we show that the expression for the relaxation oscillation frequency needs to be modified to take the quenching properly into account.

  4. Investigation of luminescent dye-doped or rare-earth-doped monodisperse silica nanospheres for DNA microarray labelling

    Science.gov (United States)

    Enrichi, F.; Riccò, R.; Meneghello, A.; Pierobon, R.; Cretaio, E.; Marinello, F.; Schiavuta, P.; Parma, A.; Riello, P.; Benedetti, A.

    2010-10-01

    DNA microarray is a high-throughput technology used for detection and quantification of nucleic acid molecules and others of biological interest. The analysis is resulting by specific hybridization between probe sequences deposited in array and a target ss-DNA usually functionalized by a luminescent dye. These organic labels have well known disadvantages like photobleaching and limited sensitivity. Therefore in this work we investigate a different strategy, based on the use of inorganic silica nanospheres incorporating standard luminescent dyes or rare earth ions. The synthesis and characterization of these biomarkers is reported and their application to the DNA microarray technology in comparison to the use of standard molecular fluorophores or commercial quantum dots is discussed. We show that dye doped silica spheres provides a significant increase of the optical emission signal with respect to the use of free dyes, while rare earth doped silica spheres allow reducing or completely avoiding the background noise. These aspects, together with their cheap and easy synthesis, stability in water, easy surface functionalization and bio-compatibility makes them very promising for present and future applications in bio-labelling and bio-imaging.

  5. Dosimetric and kinetic parameters of lithium cadmium borate glasses doped with rare earth ions

    Directory of Open Access Journals (Sweden)

    J. Anjaiah

    2014-10-01

    Full Text Available Thermoluminescence (TL characteristics of X-ray irradiated pure and doped with four different rare earth ions (viz., Pr3+, Nd3+, Sm3+ and Eu3+ Li2O–Cdo–B2O3 glasses have been studied in the temperature range 303–573 K; the pure glass has exhibited single TL peak at 466 K. When this glass is doped with different rare earth ions no additional peaks are observed but the glow peak temperature of the existing glow peak shifted gradually towards higher temperatures with gain in intensity of TL light output. The area under the glow curve is found to be maximum for Eu3+ doped glasses. The trap depth parameters associated with the observed TL peaks have been evaluated using Chen's formulae. The possible use of these glasses in radiation dosimetry has been described. The result clearly showed that europium doped cadmium borate glass has a potential to be considered as the thermoluminescence dosimeter.

  6. Enhanced Laser Cooling of Rare-Earth-Ion-Doped Composite Material

    Institute of Scientific and Technical Information of China (English)

    JIA You-Hua; ZHONG Biao; JI Xian-Ming; YIN Jian-Ping

    2008-01-01

    We predict enhanced laser cooling performance of rare-earth-ions-doped glasses containing nanometre-sized ultrafine particles, which can be achieved by the enhancement of local field around rare earth ions, owing to the surface plasma resonance of small metallic particles. The influence of energy transfer between ions and the particle is theoretically discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption is predicted. It is concluded that the absorption are greatly enhanced in these composite materials, the cooling power is increased as compared to the bulk material.

  7. Investigations on luminescence of rare earths doped CaTiO_3:Pr~(3+) phosphor

    Institute of Scientific and Technical Information of China (English)

    N.; Suriyamurthy; B.S.; Panigrahi

    2010-01-01

    Calcium titanate doped with praseodymium was prepared through solid state reaction and it exhibited intense red emission at 612 nm. Phosphors were characterized for photoluminescence, thermo-luminescence and afterglow emissions. Study of effects of rare earths on photoluminescence as well as afterglow intensity was reported. Presence of gadolinium enhanced luminescence. Presence of some monovalent ions enhanced both afterglow and photoluminescence emission. Thermo-luminescence glow curves were analyzed and ...

  8. INFLUENCE OF RARE-EARTH DOPING ON THE ELECTRICAL PROPERTIES OF HIGH VOLTAGE GRADIENT ZnO VARISTORS

    OpenAIRE

    2013-01-01

    The influence of rare-earth doping on the electrical properties of ZnO varistors was investigated. In a lower doping region, the electrical properties were greatly improved with the increase of rare-earth contents. The highest voltage gradient value of 1968.0 V/mm was obtained with a rare-earth concentration of 0.06 mol. %. The microstructure of samples with different amounts of rare-earth oxides was examined and the notable decrease of grain size was identified as the origin for the increase...

  9. Widely tunable Tm-doped mode-locked all-fiber laser

    Science.gov (United States)

    Yan, Zhiyu; Sun, Biao; Li, Xiaohui; Luo, Jiaqi; Shum, Perry Ping; Yu, Xia; Zhang, Ying; Wang, Qi Jie

    2016-06-01

    We demonstrated a widely tunable Tm-doped mode-locked all-fiber laser, with the widest tunable range of 136 nm, from 1842 to 1978 nm. Nonlinear polarization evolution (NPE) technique is employed to enable mode-locking and the wavelength-tunable operation. The widely tunable range attributes to the NPE-induced transmission modulation and bidirectional pumping mechanism. Such kind of tunable mode-locked laser can find various applications in optical communications, spectroscopy, time-resolved measurement, and among others.

  10. Cross Relaxation in rare-earth-doped oxyfluoride glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lakshminarayana, G.; Weis, Eric M. [Materials Science and Technology Division (MST-7), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lira, A.C. [Unidad Académica Profesional Nezahualcóyotl, Universidad Autónoma del Estado de México, Av. Bordo de Xochiaca s/n, Nezahualcóyotl, Estado de Mexico 57000, México (Mexico); Caldiño, Ulises [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, P.O. Box 55-534, México D.F. 09340 (Mexico); Williams, Darrick J. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hehlen, Markus P., E-mail: hehlen@lanl.gov [Materials Science and Technology Division (MST-7), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2013-07-15

    The excited-state relaxation dynamics of Tb{sup 3+}, Sm{sup 3+}, and Eu{sup 3+} doped into a 50SiO{sub 2}–20Al{sub 2}O{sub 3}–10Na{sub 2}O–20LaF{sub 3} (mol%) oxyfluoride glass are studied. Multiphonon relaxation of the primary emitting states in Tb{sup 3+} ({sup 5}D{sub 3} and {sup 5}D{sub 4}), Sm{sup 3+} ({sup 4}G{sub 5/2}), and Eu{sup 3+} ({sup 5}D{sub 0}) was found to be negligible in the present host. The relaxation of Tb{sup 3+} ({sup 5}D{sub 4}) and Eu{sup 3+} ({sup 5}D{sub 0}) is dominated by radiative decay. For Tb{sup 3+} ({sup 5}D{sub 3}) and Sm{sup 3+} ({sup 4}G{sub 5/2}) in contrast, radiative relaxation is in competition with several non-radiative cross-relaxation processes. This competition was found to be particularly pronounced for the {sup 5}D{sub 3} excited state in Tb{sup 3+}, where a 124-fold decrease of the ({sup 5}D{sub 3}→{sup 7}F{sub 5})/({sup 5}D{sub 4}→{sup 7}F{sub 5}) emission intensity ratio and a ∼10-fold shortening of the {sup 5}D{sub 3} lifetime was observed upon increasing the Tb{sup 3+} concentration from 0.01% to 1%. The Tb{sup 3+} concentration dependence of {sup 5}D{sub 3} also points to some degree of ion aggregation in the “as quenched” glasses. A Judd–Ofelt intensity analysis was performed for Sm{sup 3+} and used to estimate the relative magnitude of {sup 4}G{sub 5/2} cross-relaxation processes. Four cross-relaxation processes in particular were identified to account for 92% of the total {sup 4}G{sub 5/2} non-radiative decay, and a 11% quantum efficiency was estimated for the {sup 4}G{sub 5/2} excited state. Non-exponentiality in the {sup 5}D{sub 0} decay of Eu{sup 3+} is evidence for several Eu{sup 3+} coordination environments in the glass host that manifest in different {sup 5}D{sub 0} decay constants because of the hypersensitivity of the {sup 5}D{sub 0}→{sup 7}F{sub 2} transition. -- Highlights: ► Tb{sup 3+}, Sm{sup 3+}, and Eu{sup 3+} were doped into a LaF{sub 3}-rich oxyfluoride glass. ► The

  11. Rare Earth Doped Silica Optical Fibre Sensors for Dosimetry in Medical and Technical Applications

    Directory of Open Access Journals (Sweden)

    N. Chiodini

    2014-01-01

    Full Text Available Radioluminescence optical fibre sensors are gaining importance since these devices are promising in several applications like high energy physics, particle tracking, real-time monitoring of radiation beams, and radioactive waste. Silica optical fibres play an important role thanks to their high radiation hardness. Moreover, rare earths may be incorporated to optimise the scintillation properties (emission spectrum, decay time according to the particular application. This makes doped silica optical fibres a very versatile tool for the detection of ionizing radiation in many contexts. Among the fields of application of optical fibre sensors, radiation therapy represents a driving force for the research and development of new devices. In this review the recent progresses in the development of rare earth doped silica fibres for dosimetry in the medical field are described. After a general description of advantages and challenges for the use of optical fibre based dosimeter during radiation therapy treatment and diagnostic irradiations, the features of the incorporation of rare earths in the silica matrix in order to prepare radioluminescent optical fibre sensors are presented and discussed. In the last part of this paper, recent results obtained by using cerium, europium, and ytterbium doped silica optical fibres in radiation therapy applications are reviewed.

  12. Photoluminescence of some chalcogenide glasses doped with rare-earth ions

    Science.gov (United States)

    Iovu, Mihail; Lupan, Elana; Zavadil, Jurii; Kostka, Peter; Ivanova, Zoya; Seddon, Angela; Furniss, David

    2015-02-01

    The absorption and emission spectra of Ga-La-S:O doped with Pr3+, and Ga-Ge-As-S chalcogenide glasses doped with Pr3+, Dy3+, Nd3+, Sm3+ and Ho3+ were experimentally investigated at room temperature and at T=4 K. Photoluminescence spectra were measured at low temperature (T=4 K) at excitation by He-Ne (λ=632.8 nm line) and Ar ion (INNOVA 306, λ=514.5 nm line) lasers working in CW regime, in order to observe simultaneously the narrow 4f-4f emission from rare-earth ions and the broad band luminescence of the host glass. In the transmission spectra of rare-earth doped glasses differs from that of the base glass. The major feature in low-temperature of photoluminescence spectra (PL) is the presence of the broad band luminescence of the host glass and relatively sharp 4f-4f radiative transitions due to the presence of rare-earth (RE3+) ions, that gives the direct evidence of the energy transfer between the host glass and respective RE3+ dopants.

  13. Structural properties of lithium borate glasses doped with rare earth ions

    Directory of Open Access Journals (Sweden)

    Thomazini D.

    2001-01-01

    Full Text Available This paper presents the study on lithium triborate glass (LBO in the system (1-x|3B2O3.Li2O| (xNb2O5 yPr3+ zYb3+ wNd3+ with 0 <= x <= 20 mol% (y, z and w in mol%. The samples were studied by Raman spectroscopy, infrared absorption and differential thermal analysis. Pr3+-doped LBO and Pr3+/Yb3+-doped LBO samples show an increase of the glass transition and crystallization temperatures and a decrease of the fusion temperature associated with the increase of the praseodymium concentration in the LBO matrix. For the Nd3+-doped LBO and Pr3+/Yb3+-doped (LBO+Nb2O5 samples, a decrease of the glass transition temperature of the samples was observed. The increase of the rare earth doping leads to an increase of the difference between the glass transition and the crystallization temperatures. From infrared analysis it was possible to identify all the modes associated to the B-O structure. The NbO6 octahedra was also identified by IR spectroscopy for samples with x=5, 10, 15 and 20 mol% and y=0.05, z=1.1 mol%. Raman spectroscopy shows the presence of boroxol rings, tetrahedral and triangular coordination for boron. For samples containing niobium, the Raman spectra show the vibrational mode associated with the Nb-O bond in the niobium octahedra (NbO6.

  14. Mechanoluminescence and thermoluminesence in γ-irradiated rare earth doped CaF2 crystals

    Science.gov (United States)

    Brahme, Nameeta; Bisen, D. P.; Kher, R. S.; Khokhar, M. S. K.

    2009-08-01

    Mechanoluminescence (ML) and Thermoluminescence (TL) in γ-irradiated Dy, Ce, Er and Gd doped CaF2 crystals were studied. The crystals of doped CaF2 were grown by the Bridgman technique. The cleaved crystals were annealed at 450 ∘C for about two hours and cooled very slowly and then irradiated for different time from 60Co source having an exposure rate of 2.8×103 Gy/hr. ML was excited by applying uniaxial pressure on to the samples. Both the ML and TL intensities of CaF2 crystals increase with doping of rare earth impurities. Both the ML and TL intensity of γ-irradiated Dy, Ce, Er and Gd doped CaF2 crystals initially increase with increasing concentration of dopants obtaining an optimum value at 0.1 mole% level then further decreases with increasing dopant concentration. ML and TL intensity of γ-irradiated Dy, Ce, Er and Gd doped CaF2 crystals initially increases with the irradiation dose and then saturates at higher values of γ-doses. The order of ML and TL intensity for dopants were found similar and their order for decreasing intensity is CaF2:Dy>CaF2:Ce>CaF2:Er>CaF2:Gd. The ML spectra are almost similar to the TL spectra, this suggest that the centres emitting TL and ML may be the same although different processes cause their excitations.

  15. Band gap calculation and photo catalytic activity of rare earths doped rutile TiO2

    Institute of Scientific and Technical Information of China (English)

    BIAN Liang; SONG Mianxin; ZHOU Tianliang; ZHAO Xiaoyong; DAI Qingqing

    2009-01-01

    The density of states (DOS) of 17 kinds of rare earths (RE) doped futile TiO2 was by using fast-principles density functional the-ory (DFF) calculation. The band gap widths of RE doped rutile TiO2 were important factors for altering their absorbing wavelengths. The results show that RE ions could obviously reduce the band gap widths and form of energy of rutile TiO2 except Lu, Y, Yb and Sc, and the order of absorbing wavelengths of RE doped rutile TiO2 were the same as that of the results of calculation. The ratio of RE dopant was an-other important factor for the photo catalytic activity of RE doped rutile TiO2, and there was an optimal ratio of dopant. There was a constant for predigesting the calculation difficulty, respectively, which were 0.5mol.% and 100 mol-1 under supposition. The band gap widths of RE doped rutile TiO2 by DFT calculation were much larger than that by experiment. Finally, by transferring the calculation values to experiment values, it could be found and predicted that RE enlarged obviously the absorbing wavelengh of futile TiO2. In addition, the degree of RE ions edging out the Ti atom using the parameters of RE elements was computed.

  16. Electronic structures and magnetic properties of rare-earth-atom-doped BNNTs

    Science.gov (United States)

    Ren, Juan; Zhang, Ning-Chao; Wang, Peng; Ning, Chao; Zhang, Hong; Peng, Xiao-Juan

    2016-04-01

    Stable geometries, electronic structures, and magnetic properties of (8,0) and (4,4) single-walled BN nanotubes (BNNTs) doped with rare-earth (RE) atoms are investigated using the first-principles pseudopotential plane wave method with density functional theory (DFT). The results show that these RE atoms can be effectively doped in BNNTs with favorable energies. Because of the curvature effect, the values of binding energy for RE-atom-doped (4,4) BNNTs are larger than those of the same atoms on (8,0) BNNTs. Electron transfer between RE-5 d, 6 s, and B-2 p, N-2 p orbitals was also observed. Furthermore, electronic structures and magnetic properties of BNNTs can be modified by such doping. The results show that the adsorption of Ce, Pm, Sm, and Eu atoms can induce magnetization, while no magnetism is observed when BNNTs are doped with La. These results are useful for spintronics applications and for developing magnetic nanostructures.

  17. Sputter deposition of rare earth doped zinc sulfide for near infrared electroluminescence

    Science.gov (United States)

    Glass, William Robert, III

    2003-10-01

    Near infrared emitting alternating current thin film electroluminescent (ACTFEL) phosphors were fabricated by simultaneous R.F. magnetron sputtering from both a target of doped ZnS and an undoped ZnS target. The intensities of both near infrared (NIR) and visible emission from ZnS doped with thulium (Tm), neodymium (Nd), or erbium (Er) fluorides were dependent on deposition parameters such as target duty cycle (varied from 25 to 100% independently for the two targets) and substrate temperature (140--180°C), with lower temperatures giving 400% better NIR brightness. By optimizing the rare earth concentration between 0.8 and 1.1 at%, the near infrared irradiance was improved by 400% for each dopant. The increase in brightness and optimal concentrations are attributed to decreased crystallinity and increased dopant interaction at higher rare earth concentrations. The brightness increase with decreasing deposition temperature was attributed to a reduction of thermal desorption of the ZnS during deposition, and consequently thicker films and optimized rare earth concentration. Luminescent decay lifetimes were short (20--40 musec) because of a high concentration of non-radiative pathways due to defects from the strain of the large rare earth ions on the ZnS lattice. The threshold voltage for visible and near infrared emission was identical despite emission of NIR and visible light resulting from electrons relaxing from low and high energy excited levels, respectively. The optical threshold voltages were identical to the electrical threshold voltages, and it was concluded that at the voltages necessary for electrical breakdown, the accelerated electrons had enough energy to excite either the visible or NIR emitting levels. Phosphors doped with Nd exhibited increased internal charge at higher dopant concentrations despite a reduction in phosphor field (i.e. reduced applied voltage) In contrast; the charge did not change appreciably for Er and decreased for Tm doped films

  18. VUV spectroscopy of nominally pure and rare-earth ions doped LiCaAIF6 single crystals as promising materials for 157 nm photolithography

    Science.gov (United States)

    Cefalas, Alkiviadis C.; Sarantopoulou, Evangelia; Kollia, Z.; Abdulsabirov, R. Y.; Korableva, S. L.; Naumov, A. K.; Semashko, V. V.; Kobe, S.; McGuiness, P. J.

    2002-07-01

    Recently it was found that birefringence is induced in CaF2 crystals when they are illuminated with laser light at 157 nm. Taking into consideration that CaF2 is the only optical material used in 157 nm photolithography today, the possibility to use new wide band gap fluoride crystals as optical elements for 157 nm photolithography, even those of non-cubic symmetry, should be considered. Additionally fluoride dielectric crystals with wide band gaps doped with trivalent rare-earth (RE) ions can be used as passive or active optical elements int eh VUV. For doped crystals, applications depend on the structure of the energy level pattern of the 4fn-15d electronic configuration and RE ion concentration. In this work we are exploiting the use of wide band gap fluoride dielectric crystals doped with RE ions. The laser induced fluorescence spectrum at 157 nm, and the absorption spectra of the LiCaAlF6 crystals, pure and doped with RE ions, were investigated in the VUV region of the spectrum. A new m4tehod for monitoring RE concentration in wide band gap fluoride crystals, that is based on vibrating sample magnetometer measurement is presented as well.

  19. The tetragonal structure of nanocrystals in rare-earth doped oxyfluoride glass ceramics.

    Science.gov (United States)

    Hu, Nan; Yu, Hua; Zhang, Ming; Zhang, Pan; Wang, Yazhou; Zhao, Lijuan

    2011-01-28

    Rare-earth doped oxyfluoride glasses and nanocrystalline glass ceramics have been prepared and studied by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) aiming at investigating the structure and the symmetry of the nanocrystal as well as the site of the rare-earth ion. To solve the problem encountered by previous researchers due to glass host interference, we etched off glass matrix and released the fluoride nanocrystal, which is more convenient for EDS measurement. A tetragonal phase model with the chemical formula as PbREF(5) proved by quantitative EDS and XRD analyses has been proposed in this paper for the first time. Two specific crystalline phases with the same space group have been observed at 460 °C-500 °C and 520 °C-560 °C, respectively. Moreover, a super "pseudo-cubic" cell based on our tetragonal model may give a good explanation to the probable previous cubic-symmetry misunderstanding by researchers. Additionally, the thermodynamic mechanism of phase transition and the thermal stability related to the structure of nanocrystals in glass ceramics have been studied and supported by ab initio calculations and experimental methods. The structure and thermal stability of the nanocrystal and clear environment of the rare-earth ion reported here have far-reaching significance with respect to the optical investigations and further applications of rare-earth doped oxyfluoride glass ceramics.

  20. Magnetocaloric effect in heavy rare-earth elements doped Fe-based bulk metallic glasses with tunable Curie temperature

    Science.gov (United States)

    Li, Jiawei; Huo, Juntao; Law, Jiayan; Chang, Chuntao; Du, Juan; Man, Qikui; Wang, Xinmin; Li, Run-Wei

    2014-08-01

    The effects of heavy rare earth (RE) additions on the Curie temperature (TC) and magnetocaloric effect of the Fe-RE-B-Nb (RE = Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE element and its concentration can easily tune TC in a large temperature range of 120 K without significantly decreasing the magnetic entropy change (ΔSM) and refrigerant capacity (RC) of the alloys. The observed values of ΔSM and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd5Ge1.9Si2Fe0.1. The tunable TC and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.

  1. Synthesis and Photocatalytic Activity of TiO2/V2O5 Composite Catalyst Doped with Rare Earth Ions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    TiO2/V2O5 catalyst doped with rare earth ions was prepared by sol-gel method. Titanium tetrapropoxide and vanadium pentoxide were used as precursor of the composite catalyst and rare earth ions were used as dopant. The crystal phases, crystalline sizes, microstructure, absorption spectra of doped composite catalyst were studied by XRD, EDS, FT-IR and UV-Vis. Photoactivity of the prepared catalyst under ultraviolet irradiation were evaluated by degradation of methyl orange (MO) in aqueous solution. It is shown that the prepared catalyst is composed of anatase and rutile. The rare earth ions are highly dispersed in composite catalyst. All the doped catalysts appear higher photocatalytic activity than TiO2/V2O5 catalyst and catalyst doped with Ce4+ present the best activity to MO.

  2. Low-temperature photoluminescence in chalcogenide glasses doped with rare-earth ions

    Energy Technology Data Exchange (ETDEWEB)

    Kostka, Petr, E-mail: petr.kostka@irsm.cas.cz [Institute of Rock Structure and Mechanics AS CR, V Holešovičkách 41, 182 09 Praha 8 (Czech Republic); Zavadil, Jiří [Institute of Photonics and Electronics AS CR, Chaberská 57, 182 51 Praha 8, Kobylisy (Czech Republic); Iovu, Mihail S. [Institute of Applied Physics, Academy of Sciences of Moldova, Str. Academiei 5, MD-28 Chisinau, Republic of Moldova (Moldova, Republic of); Ivanova, Zoya G. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 1784 Sofia (Bulgaria); Furniss, David; Seddon, Angela B. [Mid-Infrared Photonics Group, George Green Institute for Electromagnetics Research, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

    2015-11-05

    Sulfide and oxysulfide bulk glasses Ga-La-S-O, Ge-Ga-S and Ge-Ga-As-S doped, or co-doped, with various rare-earth (RE{sup 3+}) ions are investigated for their room temperature transmission and low-temperature photoluminescence. Photoluminescence spectra are collected by using external excitation into the Urbach tail of the fundamental absorption edge of the host-glass. The low-temperature photoluminescence spectra are dominated by the broad-band luminescence of the host glass, with superimposed relatively sharp emission bands due to radiative transitions within 4f shells of RE{sup 3+} ions. In addition, the dips in the host-glass luminescence due to 4f-4f up-transitions of RE{sup 3+} ions are observed in the Ge-Ga-S and Ge-Ga-As-S systems. These superimposed narrow effects provide a direct experimental evidence of energy transfer between the host glass and respective RE{sup 3+} dopants. - Highlights: • An evidence of energy transfer from host-glass to doped-in RE ions is presented. • Energy transfer is manifested by dips in host-glass broad-band luminescence. • This channel of energy transfer is documented on selected RE doped sulfide glasses. • Photoluminescence spectra are dominated by broad band host-glass luminescence. • Presence of RE ions is manifested by superimposed narrow 4f-4f transitions.

  3. Anti-UV Capability of Rare Earth Doping TiO2

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The sol-gel process is used in the preparation of nanostructure materials with Ti(OC4H9)4 as precursor in the start materials. TiO2 gelatin is obtained through hydrolysis and condensation process. Rare earth such as La2O3, CeO2, Eu2O3 and Gd2O3 are introduced into the nanostructure TiO2 to improve the anti-UV capacity. The phase structure of pure TiO2 and doped TiO2 and their antiUV capacity are studied by means of XRD and UPF. The optimum doping and heat treatment temperature are chosen.

  4. Green Synthesis of Nanoparticles Molybdate Doped with Rare Earth Ion and Its Luminescence Property

    Directory of Open Access Journals (Sweden)

    Wang Jun

    2015-09-01

    Full Text Available The aim of this study is to prepare nanoparticles molybdates doped with rare earth ion Eu3+ synthesized by sol-gel method to study the luminescence property of these crystal powders. The influence of pH and doping amount of Eu3+ on these nanoparticles was also investigated. The results showed that CaMoO4: Eu3+ (6%, mass ratio prepared in pH value 7-9 and calcined at 700°C became uniformly cubic crystal and exhibited red photoluminescence with strongest emission peak at 612×258 nm excitation, which was caused by 5D0→7F2 transition of Eu3+. It can be predicted this CaMoO4: Eu3+ phosphor could be a potential phosphor material for white-light LED application in the future.

  5. The Progress of Photoluminescent Properties of Rare-Earth-Ions-Doped Phosphate One-Dimensional Nanocrystals

    Directory of Open Access Journals (Sweden)

    Lixin Yu

    2010-01-01

    Full Text Available One-dimensional (1D nanostructures, such as tubes, wires, rods, and belts, have aroused remarkable attentions over the past decade due to a great deal of potential applications, such as data storage, advanced catalyst, and photoelectronic devices . On the other hand, in comparison with zero-dimensional (0D nanostructures, the space anisotropy of 1D structures provided a better model system to study the dependence of electronic transport, optical and mechanical properties on size confinement and dimensionality. Rare earth (RE compounds, were intensively applied in luminescent and display devices. It is expected that in nanosized RE compounds the luminescent quantum efficiency (QE and display resolution could be improved. In this paper, we systematically reported the research progress of luminescent properties of RE-doped 1D orthophosphate nanocrystal, including the synthesis of 1D nanostructures doped with RE ions, local symmetry of host, electronic transition processes, energy transfer (ET, and so forth.

  6. Crystallization studies on rare-earth co-doped fluorozirconate-based glasses.

    Science.gov (United States)

    Paßlick, C; Johnson, J A; Schweizer, S

    2013-07-01

    This work focuses on the structural changes of barium chloride (BaCl2) nanoparticles in fluorochlorozirconate-based glass ceramics when doped with two different luminescent activators, in this case rare-earth (RE) ions, and thermally processed using a differential scanning calorimeter. In a first step, only europium in its divalent and trivalent oxidation states, Eu(2+) and Eu(3+), is investigated, which shows no significant influence on the crystallization of hexagonal phase BaCl2. However, higher amounts of Eu(2+) increase the activation energy of the phase transition to an orthorhombic crystal structure. In a second step, nucleation and nanocrystal growth are influenced by changing the structural environment of the glasses by co-doping with Eu(2+) and trivalent Gd(3+), Nd(3+), Yb(3+), or Tb(3+), due to the different atomic radii and electro-negativity of the co-dopants.

  7. 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.

  8. On-chip quantum storage in a rare-earth-doped photonic nanocavity

    Science.gov (United States)

    Zhong, Tian; Kindem, Jonathan M.; Rochman, Jake; Miyazono, Evan; Faraon, Andrei; Ferrier, Alban; Goldner, Philippe

    2016-03-01

    Rare-earth-ion doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical and microwave photons. Here we describe our progress towards a nanophotonic quantum memory based on a rare-earth (Neodymium) doped yttrium orthosilicate (YSO) photonic crystal resonator. The Purcell-enhanced coupling of the 883 nm transitions of Neodymium (Nd3+) ions to the nano-resonator results in increased optical depth, which could in principle facilitate highly efficient photon storage via cavity impedance matching. The atomic frequency comb (AFC) memory protocol can be implemented in the Nd:YSO nano-resonator by efficient optical pumping into the long-lived Zeeman state. Coherent optical signals can be stored and retrieved from the AFC memory. We currently measure a storage efficiency on par with a bulk crystal Nd:YSO memory that is millimeters long. Our results will enable multiplexed on-chip quantum storage and thus quantum repeater devices using rare-earth-ions.

  9. Rare-earth-doped optical-fiber core deposition using full vapor-phase SPCVD process

    Science.gov (United States)

    Barnini, A.; Robin, T.; Cadier, B.; Aka, G.; Caurant, D.; Gotter, T.; Guyon, C.; Pinsard, E.; Guitton, P.; Laurent, A.; Montron, R.

    2017-02-01

    One key parameter in the race toward ever-higher power fiber lasers remains the rare earth doped optical core quality. Modern Large Mode Area (LMA) fibers require a fine radial control of the core refractive index (RI) close to the silica level. These low RI are achieved with multi-component materials that cannot be readily obtained using conventional solution doping based Modified Chemical Vapor Deposition (MCVD) technology. This paper presents a study of such optical material obtained through a full-vapor phase Surface Plasma Chemical Vapor Deposition (SPCVD). The SPCVD process generates straight glassy films on the inner surface of a thermally regulated synthetic silica tube under vacuum. The first part of the presented results points out the feasibility of ytterbium-doped aluminosilicate fibers by this process. In the second part we describe the challenge controlling the refractive index throughout the core diameter when using volatile fluorine to create efficient LMA fiber profiles. It has been demonstrated that it is possible to counter-act the loss of fluorine at the center of the core by adjusting the core composition locally. Our materials yielded, when used in optical fibers with numerical apertures ranging from 0.07 to 0.09, power conversion efficiency up to 76% and low background losses below 20 dB/km at 1100nm. Photodarkening has been measured to be similar to equivalent MCVD based fibers. The use of cerium as a co-dopant allowed for a complete mitigation of this laser lifetime detrimental effect. The SPCVD process enables high capacity preforms and is particularly versatile when it comes to radial tailoring of both rare earth doping level and RI. Large core diameter preforms - up to 4mm - were successfully produced.

  10. Spectroscopic characterization of manganese-doped alkaline earth lead zinc phosphate glasses

    Indian Academy of Sciences (India)

    S Sreehari Sastry; B Rupa Venkateswara Rao

    2015-04-01

    Alkaline earth lead zinc phosphate glasses doped with Mn(II) are characterized by spectroscopic techniques like X-ray diffraction (XRD), UV–visible, differential scanning calorimetry (DSC), electron paramagnetic resonance (EPR), Fourier transform infrared (FTIR) and Raman. Optical absorption spectrum exhibits four bands which are characteristic of Mn(II) in distorted octahedral site symmetry. The crystal field parameter Dq and Racah interelectronic-repulsion parameters and have been evaluated. All investigated samples exhibit EPR signals which are characteristic to the Mn2+ ions. The shapes of spectra are also changed with varying alkaline earth ions content. FTIR spectra show specific vibrations of phosphate units. The characteristic Raman bands of these glasses due to stretching and bending vibrations were identified and analysed by varying alkaline earth content. The intensity and frequency variations for the characteristic phosphate group vibrations have been correlated with the changes of the structural units present in these glasses. Depolymerization of the phosphate chains in all the glasses is observed with replacement of alkaline earth content by spectroscopic studies. This leads to a strong decrease of the average chain length and a small decrease of the average P–O–P bridging angle with replacement of alkaline earth content.

  11. Luminescence and structural properties of RbGdS2 compounds doped by rare earth elements

    Science.gov (United States)

    Jarý, V.; Havlák, L.; Bárta, J.; Mihóková, E.; Nikl, M.

    2013-04-01

    Rare earth elements (Pr, Ce) doped ternary sulfides of formula RbGd1-xRExS2 were synthesized in the form of crystalline hexagonal platelets by chemical reaction under the flow of hydrogen sulfide. The X-ray powder diffraction detected only a single crystalline phase of rhombohedral lattice system. Optical properties of studied systems are investigated by methods of time-resolved luminescence spectroscopy. Thermal stability of the Pr3+ emission is demonstrated. Application potential in the white light-emitting diode solid state lighting or X-ray phosphors is discussed.

  12. Crystal field and magnetism with Wannier functions:rare-earth doped aluminum garnets

    Institute of Scientific and Technical Information of China (English)

    Eva Mihóková; Pavel Novák; Valentin V. Laguta

    2015-01-01

    Using the recently developed method we calculated the crystal field parameters in yttrium and lutetium aluminum garnets doped with seven trivalent Kramers rare-earth ions. We then inserted calculated parameters into the atomic-like Hamiltonian taking into account the electron-electron, spin-orbit and Zeeman interactions and determined the multiplet splitting by the crystal field as well as magneticĝ tensors. We compared calculated results with available experimental data. Very good agreement with the spectro-scopic data and qualitative agreement with experimentalĝ tensors was found.

  13. Fibre Tip Sensors for Localised Temperature Sensing Based on Rare Earth-Doped Glass Coatings

    Directory of Open Access Journals (Sweden)

    Erik P. Schartner

    2014-11-01

    Full Text Available We report the development of a point temperature sensor, based on monitoring upconversion emission from erbium:ytterbium-doped tellurite coatings on the tips of optical fibres. The dip coating technique allows multiple sensors to be fabricated simultaneously, while confining the temperature-sensitive region to a localised region on the end-face of the fibre. The strong response of the rare earth ions to changing temperature allows a resolution of 0.1–0.3 °C to be recorded over the biologically relevant range of temperatures from 23–39 °C.

  14. Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction.

    Science.gov (United States)

    Cramer, Alisha J; Cole, Jacqueline M; FitzGerald, Vicky; Honkimaki, Veijo; Roberts, Mark A; Brennan, Tessa; Martin, Richard A; Saunders, George A; Newport, Robert J

    2013-06-14

    Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3)x(R'2O3)y(P2O5)(1-(x+y)), where (R, R') denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP5O14. Thereupon, the effects of rare-earth co-doping on the local structure are assessed at the atomic level. Pair-distribution function analysis of high-energy X-ray diffraction data (Q(max) = 28 Å(-1)) is employed to make this assessment. Results reveal a stark structural invariance to rare-earth co-doping which bears testament to the open-framework and rigid nature of these glasses. A range of desirable attributes of these glasses unfold from this finding; in particular, a structural simplicity that will enable facile molecular engineering of rare-earth phosphate glasses with 'dial-up' lasing properties. When considered together with other factors, this finding also demonstrates additional prospects for these co-doped rare-earth phosphate glasses in nuclear waste storage applications. This study also reveals, for the first time, the ability to distinguish between P-O and P[double bond, length as m-dash]O bonding in these rare-earth phosphate glasses from X-ray diffraction data in a fully quantitative manner. Complementary analysis of high-energy X-ray diffraction data on single rare-earth phosphate glasses of similar rare-earth composition to the co-doped materials is also presented in this context. In a technical sense, all high-energy X-ray diffraction data on these glasses are compared with analogous low-energy diffraction data; their salient differences reveal distinct advantages of high-energy X-ray diffraction data for the study of amorphous materials.

  15. Rare Earth Doped GaN Laser Structures Using Metal Modulated Epitaxy

    Science.gov (United States)

    2015-03-30

    Doped Gallium Nitride by Plasma Assisted MBE, Ph. D. Thesis in Electrical and Computer Engineering, 2007, Georgia Institute of Technology, Atlanta...PERCENT_SUPPORTEDNAME FTE Equivalent: Total Number: ...... ...... Inventions (DD882) Scientific Progress Gallium nitride is a well-known wide bandgap III/V...Rui Wang for generously sharing his knowledge and experience in MBE, SIMS and nitride semiconductors. The discussions I was fortunate enough to have

  16. High quality factor nanophotonic resonators in bulk rare-earth doped crystals

    CERN Document Server

    Zhong, Tian; Kindem, Jonathan M; Miyazono, Evan; Faraon, Andrei

    2015-01-01

    Numerous bulk crystalline materials exhibit attractive nonlinear and luminescent properties for classical and quantum optical applications. A chip-scale platform for high quality factor optical nanocavities in these materials will enable new optoelectronic devices and quantum light-matter interfaces. In this article, photonic crystal nanobeam resonators fabricated using focused ion beam milling in bulk insulators, such as rare-earth doped yttrium orthosilicate and yttrium vanadate, are demonstrated. Operation in the visible, near infrared, and telecom wavelengths with quality factors up to 27,000 and optical mode volumes close to one cubic wavelength is measured. These devices enable new nanolasers, on-chip quantum optical memories, single photon sources, and non-linear devices at low photon numbers based on rare-earth ions. The techniques are also applicable to other luminescent centers and crystals.

  17. Mechanical behaviors of alumina ceramics doped with rare-earth oxides

    Institute of Scientific and Technical Information of China (English)

    YAO Yijun; LI Chuncheng; WANG Ling; JIANG Xiaolong; QIU Tai

    2010-01-01

    The effects of three types of additives Y2O3, La2O3, and Sm2O3 on the sintering and mechanical behaviors of alumina ceramics were investigated. The bending strengths of alumina ceramics with Sm2O3 and Y2O3 additions were 455 and 439 MPa, respectively, higher than that with La2O3 addition. The fracture toughness of the ceramics with Sm2O3 and Y2O3 were also higher than that with La2O3 addition. The fracture mode of rare earth oxides doped alumina ceramics exhibited obvious transgranular fractures as well as intergranular fracture. The results of research show that the improvement of bending strength and fracture toughness of alumina ceramics with rare earth oxides was achieved by refining the grain size and strengthening the grain boundary.

  18. Quantitative Analysis of Life Index of Electrothermal-Film Coated Ceramic Heating Elements with Rare-Earth Element Doped

    Institute of Scientific and Technical Information of China (English)

    He Ping

    2004-01-01

    For electrothermal-film heating elements for ceramics, the quantitative expression of the relation between the contents of multicomponent semiconductor dope and rare-earth element additive through the multivariate statistical regression analysis was presented, and the optimum control index of the multicomponent semiconductor dope and the rareearth element for the maximum life was also determined. The research shows that the life value ranging from 15 to 20 thousand hours can be ensured only if the evaluation grade of metal oxide dope in the compounding formula is controlled between grades 0.5 to 1.2. The relation of the content of multicomponent rare-earth element dope and the life index of electrothermal-film heating material for ceramics was determined theoretically.

  19. The NOAA-9 Earth Radiation Budget Experiment Wide Field-of-View Data Set

    Science.gov (United States)

    Bush, Kathryn A.; Smith, G. Louis; Young, David F.

    1999-01-01

    The Earth Radiation Budget Experiment (ERBE) consisted of wide field-of-view (WFOV) radiometers and scanning radiometers for measuring outgoing longwave radiation and solar radiation reflected from the Earth. These instruments were carried by the dedicated Earth Radiation Budget Satellite (ERBS) and by the NOAA-9 and -10 operational spacecraft. The WFOV radiometers provided data from which instantaneous fluxes at the top of the atmosphere (TOA) are computed by use of a numerical filter algorithm. Monthly mean fluxes over a 5-degree equal angle grid are computed from the instantaneous TOA fluxes. The WFOV radiometers aboard the NOAA-9 spacecraft operated from February 1985 through December 1992, at which time a failure of the shortwave radiometer ended the usable data after nearly 8 years. This paper examines the monthly mean products from that data set.

  20. Design and achieving of multicolor upconversion emission based on rare-earth doped tellurite glasses

    Institute of Scientific and Technical Information of China (English)

    邢明铭; 马运北; 罗昔贤; 付姚; 姜涛; 汪红; 段小龙

    2014-01-01

    Yb3+/Tm3+ co-doped and Yb3+/Ho3+/Tm3+ tri-doped tellurite glasses were synthesized by fusing the mixture of TeO2, PbF2, AlF3, BaF2, Yb2O3, Tm2O3 and Ho2O3 in a corundum crucible at 850 ºC for 20 min. The synthesized glasses were characterized by upconversion emission spectra under the excitation of 980 nm laser, and the emission colors were investigated according to the CIE-1931 standards. The results indicated that Yb3+/Tm3+ co-doped tellurite glass exhibited blue upconversion emission with favor-able color coordinates of (0.20, 0.07). Yb3+, Ho3+ and Tm3+ tri-doped tellurite glasses presented white upconversion luminescence under a single 980 nm laser excitation. Moreover, a very wide range of emission colors could be tuned by altering Ho3+ concentration. Combining the contribution of adjusting Ho3+ concentration and pump power, near equal energy white light was obtained.

  1. Rare Earth Doped Optical Fibers for Temperature Sensing Utilizing Ratio-Based Technology

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new and practical fluorescence temperature detecting system based on fluorescence intensity ratio was proposed. The background theory of fluorescence intensity-ratio method was presented simply. And the characters of rare earth doped samples were detailed. The erbium-doped fiber was chosen as the sensing element. The energy levels of 2H11/2 and 4S3/2 are responsible for the emission of radiation at approximately 530 and 555 nm. The erbium-doped (960 ppm) fiber of length 20 cm and core diameter 3.2 μm was used as the sensing part. A silica photodiode transfers the fluorescence signal to electric signal, then the ratio of the average of the two different signals was calculated by the computer and the temperature was obtained. The ratio R of the intensity resulting from the transition between the two levels varies proportionly with temperature interval from 293 K to 373 K. The sensitivity of the sensor is approximately 0.05 K-1.

  2. Study on BSTO/MgO Ferroelectric Materials for Phase Shift Doped with Rare Earth Oxides

    Institute of Scientific and Technical Information of China (English)

    Yang Chunxia; Zhou Hongqing; Liu Min; Wu Hongzhong

    2005-01-01

    Barium strontium titanate/magnesia (BSTO/MgO) ferroelectric materials for phase shift were prepared by traditional ceramic process-solid phase synthesis. The effects of various rare earth oxides of 0.5% on dielectric behaviors of BSTO/MgO composites were studied in terms of permittivity, loss tangent and tunability both at low and high frequencies. The dielectric constant of Y2O3 and Er2O3 doped samples decreases from 160 to 120, and the microwave loss of La2O3 and Er2O3 doped samples decreases from 8.2×10-3 to 6.8×10-3. Only La2O3 increases the tunability of BSTO/MgO system, from 13.6% to 14.8%. For the La2O3 doped sample, the value of tunability is more than 14% with the external DC field 4000 V*mm-1 and the microwave loss at 2.47 GHz is 6.77×10-3 and, hence, it can basically meet the requirements of phase shifters working at microwave frequencies. The influence mechanism was discussed preliminarily.

  3. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation.

    Science.gov (United States)

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-10-28

    A two-step process is developed to synthesize rare earth doped titania nanorods (RE-TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE-TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10(-3) s(-1). The La(3+), Sm(3+), Eu(3+) and Er(3+) doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. We further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products.

  4. Nanophotonic coherent light-matter interfaces based on rare-earth-doped crystals

    Science.gov (United States)

    Zhong, Tian; Kindem, Jonathan M.; Miyazono, Evan; Faraon, Andrei

    2015-09-01

    Quantum light-matter interfaces connecting stationary qubits to photons will enable optical networks for quantum communications, precise global time keeping, photon switching and studies of fundamental physics. Rare-earth-ion-doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical photons, microwave photons and spin waves. Here we demonstrate coupling of an ensemble of neodymium rare-earth-ions to photonic nanocavities fabricated in the yttrium orthosilicate host crystal. Cavity quantum electrodynamics effects including Purcell enhancement (F=42) and dipole-induced transparency are observed on the highly coherent 4I9/2-4F3/2 optical transition. Fluctuations in the cavity transmission due to statistical fine structure of the atomic density are measured, indicating operation at the quantum level. Coherent optical control of cavity-coupled rare-earth ions is performed via photon echoes. Long optical coherence times (T2~100 μs) and small inhomogeneous broadening are measured for the cavity-coupled rare-earth ions, thus demonstrating their potential for on-chip scalable quantum light-matter interfaces.

  5. Power scaling estimate of crystalline fiber waveguides with rare earth doped YAG cores

    Science.gov (United States)

    Li, Da; Hong, Pengda; Meissner, Stephanie K.; Meissner, Helmuth E.

    2016-03-01

    Power scaling analysis based on the model by Dawson et al. [1,2] for circular core fibers has been applied to estimating power scaling of crystalline fiber waveguides (CFWs) with RE3+ doped single crystalline or ceramic YAG (RE=rare earth: Yb, Er, Tm and Ho). Power scaling limits include stimulated Brillouin scattering, thermal lensing effect, and limits to coupling of pump light into CFWs. The CFW designs we have considered consist, in general, of a square doped RE3+:YAG core, an inner cladding of either undoped or laser-inactive-ion-doped YAG and an outer cladding of sapphire. The presented data have been developed for the structures fabricated using the Adhesive-Free Bonding (AFB®) technique, but the results should be essentially independent of fabrication technique, assuming perfect core/inner cladding/outer cladding interfaces. Hard power scaling limits exist for a specific CFW design and are strongly based on the physical constants of the material and its spectroscopic specifics. For example, power scaling limit was determined as ~16 kW for 2.5% ceramic Yb:YAG/YAG (core material/inner cladding material) at fiber length of 1.7 m and core diameter of 69 μm. Considering the present manufacturing limit for CFW length to be, e.g., 0.5 m, the actual maximum output power will be limited to ~4.4 kW for a Yb:YAG/YAG CFW. Power limit estimates have also been computed for Er3+, Tm3+ and Ho3+doped core based CFWs.

  6. Performance Evaluation of ZnO based Rare Earth Element Doped Thin Films

    Directory of Open Access Journals (Sweden)

    Manish Sharma

    2013-10-01

    Full Text Available In DMS materials, a small fraction of a host semiconductor cation is substituted by magnetic ions. We chose as semiconducting host the transparent ZnO, with a bandgap of 3.3 eV at room temperature. Studies on ZnO doped with 3d transition metals indicated only small magnetic moments. The more recent results for Gd in GaN, indicating high magnetic moments, motivated us to investigate ZnO thin films doped with rare earth (RE metal ions. For the 3d transition metals, the 3d electrons are exterior and delocalized; leading to strong direct exchange interactions and high Curie temperatures, but often the orbital momentum is zero, leading to small total magnetic moments per atom. In RE metals, the 4f electrons are localized, exchange interactions are indirect, via 5d or 6s conduction electrons, but the high orbital momentum is leading to high total magnetic moments per atom, like 3.27μB for Nd. The Curie point for Nd is 19 K. In this paper we present the results of our study on ZnO films doped with Nd. Hall measurements are performed to investigate the electrical properties of films. Here we prepared and investigated ZnO films doped with different concentration of Nd. The films are grown on a-plane Al2O3 or SiO2 substrates. Hall investigations of electrical properties revealed the presence of a degenerate, highly conducting, film–substrate interface layer for the films grown on Al2O3; such an effect can be avoided, for example, by using SiO2 substrates. Magnetotransport measurements indicated no anomalous Hall effect, but a pronounced negative magneto resistance ratio that can be interpreted as a paramagnetic response of the system to the applied magnetic field. We would like to proceed with the surface sensitive techniques for investigating magnetic properties of ZnO:RE thin films.

  7. Rare earth doped CaCu_3Ti_4O_(12) electronic ceramics for high frequency applications

    Institute of Scientific and Technical Information of China (English)

    慕春红; 张怀武; 刘颖力; 宋远强; 刘鹏

    2010-01-01

    Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully investigated.XRD results showed that the secondary phases with the general formula R2Ti2O7 existed at grain boundaries of rare earth doped ceramics,which inhibited abnormal grain growth.The dielectric constant decreased from 4×105 in pure CaCu3Ti4O12(CCTO) ceramics to 2×103 with rare earth doping....

  8. Wide-range controllable n-doping of molybdenum disulfide (MoS2) through thermal and optical activation.

    Science.gov (United States)

    Park, Hyung-Youl; Lim, Myung-Hoon; Jeon, Jeaho; Yoo, Gwangwe; Kang, Dong-Ho; Jang, Sung Kyu; Jeon, Min Hwan; Lee, Youngbin; Cho, Jeong Ho; Yeom, Geun Young; Jung, Woo-Shik; Lee, Jaeho; Park, Seongjun; Lee, Sungjoo; Park, Jin-Hong

    2015-03-24

    Despite growing interest in doping two-dimensional (2D) transition metal dichalcogenides (TMDs) for future layered semiconductor devices, controllability is currently limited to only heavy doping (degenerate regime). This causes 2D materials to act as metallic layers, and an ion implantation technique with precise doping controllability is not available for these materials (e.g., MoS2, MoSe2, WS2, WSe2, graphene). Since adjustment of the electrical and optical properties of 2D materials is possible within a light (nondegenerate) doping regime, a wide-range doping capability including nondegenerate and degenerate regimes is a critical aspect of the design and fabrication of 2D TMD-based electronic and optoelectronic devices. Here, we demonstrate a wide-range controllable n-doping method on a 2D TMD material (exfoliated trilayer and bulk MoS2) with the assistance of a phosphorus silicate glass (PSG) insulating layer, which has the broadest doping range among the results reported to date (between 3.6 × 10(10) and 8.3 × 10(12) cm(-2)) and is also applicable to other 2D semiconductors. This is achieved through (1) a three-step process consisting of, first, dopant out-diffusion between 700 and 900 °C, second, thermal activation at 500 °C, and, third, optical activation above 5 μW steps and (2) weight percentage adjustment of P atoms in PSG (2 and 5 wt %). We anticipate our widely controllable n-doping method to be a starting point for the successful integration of future layered semiconductor devices.

  9. Wide colour gamut generated in triply lanthanide doped sol-gel nano-glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, J. del, E-mail: fjvargas@ull.e [Universidad de La Laguna, Dpto. Fisica Basica (Spain); Mendez-Ramos, J. [Universidad de La Laguna, Dpto. Fisica Fundamental y Experimental, Electronica y Sistemas (Spain); Yanes, A. C. [Universidad de La Laguna, Dpto. Fisica Basica (Spain); Rodriguez, V. D. [Universidad de La Laguna, Dpto. Fisica Fundamental y Experimental, Electronica y Sistemas (Spain)

    2009-05-15

    The generation of a wide colour gamut, based on up-conversion of cheap near-infrared photons into the visible range, is of great importance for general lighting appliances and integrated optical devices. Here, we report for the first time on up-conversion luminescence under infrared excitation at 980 nm in Yb{sup 3+}-Er{sup 3+}-Tm{sup 3+} triply doped sol-gel derived SiO{sub 2}-LaF{sub 3} based nano-glass-ceramics (SOL-YET), containing LaF{sub 3} nanocrystals with a size about 13 nm. Efficient simultaneous up-conversion emission of the three primary colours (blue, green and red) gives rise to a balanced white overall emission. The ratio between up-conversion emission bands can be varied by changing pump power intensity resulting in colour tuneable up-conversion phosphor.

  10. Estimation of cut-off wavelength of rare earth doped single-mode fibers

    Science.gov (United States)

    Kaur, Jagneet; Thyagarajan, K.; Pal, B. P.

    1999-11-01

    A new empirical relation is proposed describing spectral variation of mode-field radius (MFR) as inferred from measurements in the far-field of the fiber. It is shown that using this relation, it is possible to estimate the cut-off wavelength ( λc) of the fiber. The proposed technique is successfully tested through measurements made on two standard step index single-mode fibers, as well as on an erbium doped fiber (EDF) having λc falling within its strong absorption band around 980 nm. This empirical formula is more accurate than the widely used Marcuse's formula to describe spectral dependence of MFR determined through measurements made in the fiber's far-field. The proposed technique is especially suited for estimation of λc of doped fibers in which λc falls within an absorption band.

  11. Rare-earth-ion-doped waveguide lasers on a silicon chip

    Science.gov (United States)

    Pollnau, Markus

    2015-03-01

    Rare-earth-ion-doped materials are of high interest as amplifiers and lasers in integrated optics. Their longer excited-state lifetimes and the weaker refractive-index change accompanied with rare-earth-ion excitation compared to electron-hole pairs in III-V semiconductors provide spatially and temporally stable optical gain, allowing for high-speed amplification and narrow-linewidth lasers. Amorphous Al2O3 deposited onto thermally oxidized silicon wafers offers the advantage of integration with silicon photonics and electronics. Layer deposition by RF reactive co-sputtering and micro-structuring by chlorine-based reactive-ion etching provide low-loss channel waveguides. With erbium doping, we improved the gain to 2 dB/cm at 1533 nm and a gain bandwidth of 80 nm. The gain is limited by migration-accelerated energy-transfer upconversion and a fast quenching process. Since stimulated emission is even faster than this quenching process, lasers are only affected in terms of their threshold, allowing us to demonstrate diode-pumped micro-ring, distributed-feedback (DFB), and distributed-Bragg-reflector (DBR) lasers in Al2O3:Er3+ and Al2O3:Yb3+ on a silicon chip. Surface-relief Bragg gratings were patterned by laser-interference lithography. Monolithic DFB and DBR cavities with Q-factors of 1.35×106 were realized. In an Er-doped DFB laser, single-longitudinal-mode operation at 1545 nm was achieved with a linewidth of 1.7 kHz, corresponding to a laser Q-factor of 1.14×1011. Yb-doped DFB and DBR lasers were demonstrated at 1020 nm with output powers of 55 mW and a slope efficiency of 67% versus launched pump power. A dual-phaseshift, dual-wavelength laser was achieved and a stable microwave signal at ~15 GHz was created via the heterodyne photo-detection of the two laser wavelengths.

  12. Spectroscopic studies of copper doped alkaline earth lead zinc phosphate glasses

    Science.gov (United States)

    Sastry, S. Sreehari; Rao, B. Rupa Venkateswara

    2014-02-01

    In this paper spectroscopic investigation of Cu2+ doped alkaline earth lead zinc phosphate glasses was done through the spectroscopic techniques like X-ray diffraction, Ultra Violet (UV) absorption Spectroscopy, Electron Paramagnetic Resonance (EPR - X band), Fourier Transform Infra Red (FTIR) and Raman Spectroscopy. Alkaline earth lead zinc phosphate glasses containing 0.1% copper oxide (CuO) were prepared by the melt quenching technique. Spectroscopic studies indicated that there is a greater possibility for the copper ions to exist in Cu2+ state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu2+ is a function of composition. The maxima absorption peak was reported at 862 nm for strontium lead zinc phosphate glass. Bonding parameters were calculated for the optical and EPR data. All these spectral results indicated clearly that there are certain structural changes in the present glass system with different alkaline earth contents. The IR and Raman spectra noticed the breaking of the P-O-P bonds and creating more number of new P-O-Cu bonds.

  13. Spectroscopic studies of copper doped alkaline earth lead zinc phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, S. Sreehari, E-mail: sreeharisastry@yahoo.com [Department of Physics, Acharya Nagarjuna University, Nagarjunanagar 522510 (India); Rao, B. Rupa Venkateswara [Department of Physics, Acharya Nagarjuna University, Nagarjunanagar 522510 (India); Department of Physics, V.R. Siddhartha Engineering College, Vijayawada 52007 (India)

    2014-02-01

    In this paper spectroscopic investigation of Cu{sup 2+} doped alkaline earth lead zinc phosphate glasses was done through the spectroscopic techniques like X-ray diffraction, Ultra Violet (UV) absorption Spectroscopy, Electron Paramagnetic Resonance (EPR – X band), Fourier Transform Infra Red (FTIR) and Raman Spectroscopy. Alkaline earth lead zinc phosphate glasses containing 0.1% copper oxide (CuO) were prepared by the melt quenching technique. Spectroscopic studies indicated that there is a greater possibility for the copper ions to exist in Cu{sup 2+} state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu{sup 2+} is a function of composition. The maxima absorption peak was reported at 862 nm for strontium lead zinc phosphate glass. Bonding parameters were calculated for the optical and EPR data. All these spectral results indicated clearly that there are certain structural changes in the present glass system with different alkaline earth contents. The IR and Raman spectra noticed the breaking of the P–O–P bonds and creating more number of new P–O–Cu bonds.

  14. Enhanced near-infrared photoacoustic imaging of silica-coated rare-earth doped nanoparticles.

    Science.gov (United States)

    Sheng, Yang; Liao, Lun-De; Bandla, Aishwarya; Liu, Yu-Hang; Yuan, Jun; Thakor, Nitish; Tan, Mei Chee

    2017-01-01

    Near-infrared photoacoustic (PA) imaging is an emerging diagnostic technology that utilizes the tissue transparent window to achieve improved contrast and spatial resolution for deep tissue imaging. In this study, we investigated the enhancement effect of the SiO2 shell on the PA property of our core/shell rare-earth nanoparticles (REs) consisting of an active rare-earth doped core of NaYF4:Yb,Er (REDNPs) and an undoped NaYF4 shell. We observed that the PA signal amplitude increased with SiO2 shell thickness. Although the SiO2 shell caused an observed decrease in the integrated fluorescence intensity due to the dilution effect, fluorescence quenching of the rare earth emitting ions within the REDNPs cores was successfully prevented by the undoped NaYF4 shell. Therefore, our multilayer structure consisting of an active core with successive functional layers was demonstrated to be an effective design for dual-modal fluorescence and PA imaging probes with improved PA property. The result from this work addresses a critical need for the development of dual-modal contrast agent that advances deep tissue imaging with high resolution and signal-to-noise ratio. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Hydrothermal Synthesis, Microstructure and Photoluminescence of Eu3+-Doped Mixed Rare Earth Nano-Orthophosphates

    Directory of Open Access Journals (Sweden)

    Yan Bing

    2010-01-01

    Full Text Available Abstract Eu3+-doped mixed rare earth orthophosphates (rare earth = La, Y, Gd have been prepared by hydrothermal technology, whose crystal phase and microstructure both vary with the molar ratio of the mixed rare earth ions. For LaxY1–xPO4: Eu3+, the ion radius distinction between the La3+ and Y3+ is so large that only La0.9Y0.1PO4: Eu3+ shows the pure monoclinic phase. For LaxGd1–xPO4: Eu3+ system, with the increase in the La content, the crystal phase structure of the product changes from the hexagonal phase to the monoclinic phase and the microstructure of them changes from the nanorods to nanowires. Similarly, YxGd1–xPO4: Eu3+, Y0.1Gd0.9PO4: Eu3+ and Y0.5Gd0.5PO4: Eu3+ samples present the pure hexagonal phase and nanorods microstructure, while Y0.9Gd0.1PO4: Eu3+ exhibits the tetragonal phase and nanocubic micromorphology. The photoluminescence behaviors of Eu3+ in these hosts are strongly related to the nature of the host (composition, crystal phase and microstructure.

  16. Effect of doping rare earth oxide on performance of copper-manganese catalysts for water-gas shift reaction

    Institute of Scientific and Technical Information of China (English)

    何润霞; 姜浩强; 武芳; 智科端; 王娜; 周晨亮; 刘全生

    2014-01-01

    Rare earth-doped copper-manganese mixed oxide catalysts were prepared by coprecipitation and mechanical mixing using copper sulfate, manganese sulfate, and rare-earth oxides REO (REO indicates La2O3, CeO2, Y2O3, or Pr6O11) as raw materials. The samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), temperature-programmed reduc-tion of oxidized surfaces (s-TPR), and temperature-programmed desorption (TPD). Catalytic activities were tested for a water-gas shift reaction. Doping rare earth oxides did not alter the crystal structure of the original copper-manganese mixed oxides but changed the interplanar spacing, adsorption performance and reaction performance. Doping with La2O3 enhanced the activity and stability of Cu-Mn mixed oxides because of high copper distribution and fine reduction. Doping with CeO2 and Y2O3 also decreased the reduc-tion temperatures of the samples to different degrees while improving the dispersion of Cu on the surface, thus, catalytic activity was better than that of undoped Cu-Mn sample. The Pr6O11-doped sample was difficult to reduce, the dispersion of surface coppers was lowered, resulting in poor activity.

  17. Rare-earth-ion doped KY(WO4)2 optical waveguides grown by liquid-phase epitaxy

    NARCIS (Netherlands)

    Romanyuk, Y.E.; Apostolopoulos, V.; Utke, U.; Pollnau, Markus

    2004-01-01

    High-quality KY(WO4)2 thin layers doped with rare-earth-ions were grown using liquid-phase epitaxy. A low-temperature mixture of chlorides was used as the flux and undoped KY(WO4)2 crystals as substrates. The crystalline layers possessed thicknesses up to 10 µm. Passive and active planar waveguiding

  18. Low-temperature liquid phase epitaxy of rare-earth-ion doped KY(WO4)2 thin layers

    NARCIS (Netherlands)

    Romanyuk, Y.E.; Utke, I.; Ehrentraut, D.; Pollnau, Markus; Garcia-Revilla, S.; Valiente, R.; Kuleshov, N.V.

    2004-01-01

    Rare-earth-ion doped KY(WO4)2 (hereafter KYW) is a promising material for novel solid-state lasers. Low laser threshold, high efficiency, high output powers, and third-order nonlinear effects have stimulated research towards miniaturized thin-film waveguide lasers and amplifiers for future photonic

  19. Single-mode regime in large-mode-area rare-earth-doped rod-type PCFs

    DEFF Research Database (Denmark)

    Poli, F.; Cucinotta, A.; Passaro, D.

    2009-01-01

    In this paper, large-mode-area, double-cladding, rare-earth-doped photonic crystal fibers are investigated in order to understand how the refractive index distribution and the mode competition given by the amplification can assure single-mode propagation. Fibers with different core diameters, i...

  20. Birefringence and polarization rotator induced by electromagnetically induced transparency in rare earth ion-doped crystals

    Science.gov (United States)

    Li, Zhixiang; Liu, Jianji; Yu, Ping; Zhang, Guoquan

    2016-05-01

    The birefringence induced by the electromagnetically induced transparency effect in a {Pr}^{3+}:{Y}_2 {SiO}_5 crystal was studied by using a balanced polarimeter technique. The results show that it is possible to control the polarization state of the output probe beam by adjusting the experimental conditions. Particularly, the coherently prepared {Pr}^{3+}:{Y}_2 {SiO}_5 crystal can serve as a polarization rotator for a linearly polarized input probe beam at the two-photon resonant condition. Such coherent control on the polarization of light should be useful for polarization-based classical and quantum information processing such as all-optical switching, polarization preserving light pulse memory and polarization qubits based on rare earth ion-doped solids.

  1. Luminescence of color centers formed in alkali-earth-doped yttrium orthoaluminate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kawabe, Y. [Chitose Institute of Science and Technology, 758-65 Bibi, Chitose, Hokkaido 066-8655 (Japan) and CREST, Japan Science and Technology Agency, 758-65 Bibi, Chitose, Hokkaido 066-8655 (Japan)]. E-mail: y-kawabe@photon.chitose.ac.jp; Yamanaka, A. [Chitose Institute of Science and Technology, 758-65 Bibi, Chitose, Hokkaido 066-8655 (Japan); CREST, Japan Science and Technology Agency, 758-65 Bibi, Chitose, Hokkaido 066-8655 (Japan); Horiuchi, H. [Chitose Institute of Science and Technology, 758-65 Bibi, Chitose, Hokkaido 066-8655 (Japan); CREST, Japan Science and Technology Agency, 758-65 Bibi, Chitose, Hokkaido 066-8655 (Japan); Takashima, H. [Chitose Institute of Science and Technology, 758-65 Bibi, Chitose, Hokkaido 066-8655 (Japan); Hanamura, E. [Chitose Institute of Science and Technology, 758-65 Bibi, Chitose, Hokkaido 066-8655 (Japan); CREST, Japan Science and Technology Agency, 758-65 Bibi, Chitose, Hokkaido 066-8655 (Japan)

    2006-12-15

    Alkali-earth-doped yttrium orthoaluminate crystals grown in a reducing atmosphere are found to show bright photoluminescence (PL) in visible wavelength regions under the excitation by UV light source. From the results of transmission, PL, PL excitation and time-resolved PL spectra for the samples with different types and concentrations of dopants and the comparison to the results for the samples grown under different conditions, the origin of principal emission is determined to be color centers stabilized by heterovalent ions. The observed fast lifetime and high quantum yield of the luminescence can be explained by dipole-allowed transition between the levels localized in a vacancy. Comparing the effects on the optical properties from several types of dopant ions and taking influence from the UV irradiation into account, a model for the structure of emission centers is proposed.

  2. Nanophotonic coherent light-matter interfaces based on rare-earth-doped crystals

    CERN Document Server

    Zhong, Tian; Miyazono, Evan; Faraon, Andrei

    2015-01-01

    Quantum light-matter interfaces (QLMIs) connecting stationary qubits to photons will enable optical networks for quantum communications, precise global time keeping, photon switching, and studies of fundamental physics. Rare-earth-ion (REI) doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical photons, microwave photons and spin waves. Here we demonstrate coupling of an ensemble of neodymium REIs to photonic nano-cavities fabricated in the yttrium orthosilicate host crystal. Cavity quantum electrodynamics effects including Purcell enhancement (F=42) and dipole-induced transparency are observed on the highly coherent 4I9/2-4F3/2 optical transition. Fluctuations in the cavity transmission due to statistical fine structure of the atomic density are measured, indicating operation at the quantum level. Coherent optical control of cavity-coupled REIs is performed via photon echoes. Long optical coherence times (T2~100 microseconds) and small inhomogeneous...

  3. Interfacing Superconducting Qubits and Telecom Photons via a Rare-Earth Doped Crystal

    Science.gov (United States)

    Lauk, Nikolai; O'Brien, Christopher; Blum, Susanne; Morigi, Giovanna; Fleischhauer, Michael

    2014-05-01

    Superconducting qubits (SCQ) are promising candidates for scalable quantum computation. However, they are essentially stationary, which makes them less suitable for quantum information transport. Interfacing short telecom photons with SCQ's would enable the combination of SCQ with low loss optical fiber networks and a fast, reliable quantum network could be realized. To this end, we propose and theoretically analyze a scheme for coupling optical photons to a SCQ, using a rare earth doped crystal (REDC) coupled to the microwave cavity as an interface. The idea is first to store an optical photon by mapping it to a spin excitation in a REDC and then transfer this excitation to a SCQ via a microwave cavity. Due to intrinsic and engineered inhomogeneous broadening of the optical and spin transitions employed in REDC for the storage of short optical photon pulses, we suggest and optimize a special transfer protocol using staggered π-pulses.

  4. Improving the intensity and efficiency of compressed echo in rare-earth-ion-doped crystal

    Science.gov (United States)

    Xiu-Rong, Ma; Yu-Qing, Liang; Song, Wang; Shuang-Gen, Zhang; Yun-Long, Shan

    2016-07-01

    We investigate the intensity and efficiency of a compressed echo, which is important in arbitrary waveform generation (AWG). A new model of compressed echo is proposed based on the optical Bloch equations, which exposes much more detailed parameters than the conventional model, such as the time delay of the chirp lasers, the nature of the rare-earth-ion-doped crystal, etc. According to the novel model of compressed echo, we find that reducing the time delay of the chirp lasers and scanning the lasers around the center frequency of the inhomogeneously broadened spectrum, while utilizing a crystal with larger coherence time and excitation lifetime can improve the compressed echo’s intensity and efficiency. The theoretical analysis is validated by numerical simulations. Project supported by Special Funds for Scientific and Technological Innovation Projects in Tianjin, China (Grant No. 10FDZDGX00400) and the Tianjin Research Program of Application Foundation and Advanced Technology, China (Grant No. 15JCQNJC01100).

  5. Sol-gel-derived hybrid materials multi-doped with rare-earth metal ions

    Science.gov (United States)

    Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.

    2012-06-01

    Four different hybrid organic-inorganic materials based on TiO2-SiO2 matrices with organic additives and doped with rare-earth metal ions (III) from the group of europium, cerium, terbium, neodymium, dysprosium and samarium, were synthesized by sol-gel method. Tetraethyl orthosilicate, titanium (IV) isopropoxide and organic compounds, such as butyl acrylate, butyl methacrylate, ethyl acetoacetate, ethylene glycol dimethacrylate, ethyl acetate, propylene carbonate, organic solvents and certain inorganic salts were used in the synthesis. The inorganic part of the sols, which were used in the synthesis of all the hybrid materials, was prepared separately and then the organic parts were added. The materials obtained were aged for three weeks at room temperature and then heated in an electric oven for three hours at temperatures of 80 °C-150 °C. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX); X-ray diffraction (XRD); Fourier transform infrared spectroscopy (KBr technique); 29Si magic-angle spinning nuclear magnetic resonance; and fluorescence spectroscopy were used for the examination of morphology, microstructure and luminescence properties, respectively. Photoluminescence properties with relatively intense narrow emission lines of Tb, Eu, Dy, Nd, Sm respectively to the RE-ions doping, were observed for all the hybrid materials.

  6. Cancer-targeted near infrared imaging using rare earth ion-doped ceramic nanoparticles.

    Science.gov (United States)

    Zako, Tamotsu; Yoshimoto, Miya; Hyodo, Hiroshi; Kishimoto, Hidehiro; Ito, Masaaki; Kaneko, Kazuhiro; Soga, Kohei; Maeda, Mizuo

    2015-01-01

    The use of near-infrared (NIR) light over 1000 nm (OTN-NIR or second NIR) is advantageous for bioimaging because it enables deep tissue penetration due to low scattering and autofluorescence. In this report, we describe the application of rare earth ion-doped ceramic nanoparticles to cancer-targeted NIR imaging using erbium and ytterbium ion-doped yttrium oxide nanoparticles (YNP) functionalized with streptavidin via bi-functional PEG (SA-YNP). YNP has NIR emission at 1550 nm, with NIR excitation at 980 nm (NIR-NIR imaging). Cancer-specific NIR-NIR imaging was demonstrated using SA-YNP and biotinylated antibodies on cancer cells and human colon cancer tissues. NIR-NIR imaging through porcine meat of 1 cm thickness was also demonstrated, supporting the possible application of deep tissue NIR-NIR bioimaging using YNP as a probe. Our results suggest that non-invasive imaging using YNP has great potential for general application in cancer imaging in living subjects.

  7. Visible-Light Excitated Photocatalytic Activity of Rare Earth Metal-Ion-Doped Titania

    Institute of Scientific and Technical Information of China (English)

    谢一兵; 李萍; 袁春伟

    2002-01-01

    The rare earth ion Ce4+ doped TiO2 was prepared by sol-gel method. The average particle sizes are about 10 nm for sol phase and 55 nm for polycrystalline phase. The photocatalytic activities to degrade Reactive Brilliant Red Dye X-3B were investigated. The result reveals that the spectrum response of Ce4+-TiO2 has extended to visible region from the UV region(λ<387 nm) of pure TiO2. Amorphous phase Ce4+-TiO2 sol with an electron scavenger (1.0% atom fraction Ce4+ ion doping amount) shows the capability of the photocatalytic degradation of the dye X-3B as well as the nanocrystallite Ce4+-TiO2 with an interband trap site. Despite of the difference in the morphology of Ce4+-TiO2 photocatalyst, there is no apparent difference in respect of the decoloring effects. Whereas, polycrystalline phase Ce4+-TiO2 exhibits strong photomineralization power in comparison with the amorphous phase. The photocatalytic oxidation mechanisms of the dye molecule mainly involved in the self-photo-sensitization photolysis process by the first excited singlet oxygen (1O2) and photocatalysis process by hydroxyl radicals(*OH) under visible light irradiation.

  8. Luminescence spectroscopy of rare earth-doped oxychloride lead borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, Wojciech A., E-mail: Wojciech.Pisarski@us.edu.p [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Pisarska, Joanna [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Lisiecki, RadosLaw [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okolna 2, 50-422 WrocLaw (Poland); Grobelny, Lukasz [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Dominiak-Dzik, Grazyna; Ryba-Romanowski, Witold [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okolna 2, 50-422 WrocLaw (Poland)

    2011-04-15

    Ln-doped oxychloride lead borate glasses were studied using luminescence spectroscopy. Rare earth ions were limited to trivalent Pr{sup 3+}, Tm{sup 3+}, Eu{sup 3+} and Er{sup 3+}. Luminescence spectra were registered, which correspond to {sup 3}P{sub 0}-{sup 3}H{sub 4} and {sup 1}D{sub 2}-{sup 3}H{sub 4} transitions of Pr{sup 3+}, {sup 1}G{sub 4}-{sup 3}H{sub 5} and {sup 1}G{sub 4}-{sup 3}F{sub 4} transitions of Tm{sup 3+}, {sup 5}D{sub 0}-{sup 7}F{sub J} (J=0, 1, 2, 3, 4) transitions of Eu{sup 3+} and {sup 4}S{sub 3/2},{sup 2}H{sub 11/2}-{sup 4}I{sub 15/2} and {sup 4}I{sub 13/2}-{sup 4}I{sub 15/2} transitions of Er{sup 3+}. Luminescence decays from the excited states of Ln{sup 3+} ions were analyzed in detail. The experimental results indicate that relatively high phonon energy of the host gives important contribution to the excited state relaxation of rare earth ions. - Research Highlights: {yields}Lead borate glasses modified by PbCl{sub 2} were synthesized. {yields}Luminescence of Pr{sup 3+}, Tm{sup 3+}, Eu{sup 3+} and Er{sup 3+} ions in multicomponent oxychloride glasses was registered. {yields}From decay curves luminescence lifetimes for the excited states of rare earth ions were determined. {yields}The relatively high phonon energy of the host gives important contribution to the excited state relaxation of rare earth ions.

  9. Glass-forming Ability and Chemical Stability of Mag-neto-optical Glass Heavily Doped with Rare Earth Oxide

    Institute of Scientific and Technical Information of China (English)

    YIN Hairong; ZHANG Chunxiang; LIU Liying; CHEN Guoping; TANG Baojun

    2009-01-01

    The glass-forming region of B_2O_3-Al_2O_3-SiO_2(BAS)glass heavily doped with rare earth oxides was investigated by an effective method,and the chemical stability was investigated by powder method.Influences of rare earth oxides on the glass-forming ability and the chemical stability of the BAS glass were also discussed.The experimental results show that the BAS glass-forming re-gion expands firstly with the increase of the Tb_2O_3 content up to 30mol%and then shrinks.The acid-resistant capacity of the BAS glass doped with rare earth oxides is the lowest,the water-resistant capacity is secondary,and the alkali-resistant capacity is the best.Besides,the glass chemical stability can be improved by doping appropriate amount of rare earth oxides.Moreover,the stronger the ionic polarization ability of the rare earth ions is,the better the chemical stability of the BAS glass will be.

  10. 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.

  11. 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.

  12. Fabrication and Characterization of Glass-Ceramics Doped with Rare Earth Oxide and Heavy Metal Oxide

    Institute of Scientific and Technical Information of China (English)

    陈国华; 刘心宇; 成钧

    2004-01-01

    Cordierite-based glass-ceramics with non-stoichiometric composition doped with rare earth oxide (REO2) and heavy metal oxide (M2O3) respectively were fabricated from glass powders. After sintering and crystallization heat treatment, various physical properties, including compact density and apparent porosity, were examined to evaluate the sintering behavior of cordierite-based glass-ceramics. Results show that the additives both heavy metal oxide and rare earth oxide promote the sintering and lower the phase temperature from μ- to α-cordierite as well as affect the dielectric properties of sintered glass-ceramics. The complete-densification temperature for samples is as low as 900 ℃. The materials have a low dielectric constant (≈5), a low thermal expansion coefficient ((2.80~3.52)×10-6 ℃-1) and a low dissipation factor (≤0.2%) and can be co-fired with high conductivity metals such as Au, Cu, Ag/Pd paste at low temperature (below 950 ℃), which makes it to be a promising material for low-temperature co-fired ceramic substrates.

  13. Dephasing mechanisms of optical transitions in rare-earth-doped transparent ceramics

    Science.gov (United States)

    Kunkel, Nathalie; Bartholomew, John; Welinski, Sacha; Ferrier, Alban; Ikesue, Akio; Goldner, Philippe

    2016-11-01

    We identify and analyze dephasing mechanisms that broaden the optical transitions of rare-earth ions in randomly oriented transparent ceramics. The study examines the narrow F70↔D50 transition of Eu3 + dopants in a series of Y2O3 ceramic samples prepared under varying conditions. We characterize the temperature and magnetic field dependence of the homogeneous linewidth, as well as long-term spectral diffusion on time scales up to 1 s. The results highlight significant differences between samples with differing thermal treatments and Zr4 + additive concentrations. In particular, several distinct magnetic interactions from defect centers are observed, which are clearly distinguished from the broadening due to interactions with two-level systems and phonons. By minimizing the broadening due to the different defect centers, linewidths of the order of 4 kHz are achieved for all samples. The linewidths are limited by temperature-dependent interactions and by an interaction that is yet to be identified. Although the homogeneous linewidth can be narrowed further in these ceramic samples, the broadening is now comparable to the linewidths achieved in rare-earth-ion-doped single crystals. Thus, this work emphasizes the usefulness of studying ceramics to gain insights into dephasing mechanisms relevant to single crystals and suggests that ceramics may be an interesting alternative for applications in classical and quantum information processing.

  14. Magnetocaloric effect in heavy rare-earth elements doped Fe-based bulk metallic glasses with tunable Curie temperature

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiawei; Huo, Juntao; Chang, Chuntao, E-mail: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn; Du, Juan, E-mail: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn; Man, Qikui; Wang, Xinmin; Li, Run-Wei [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Law, Jiayan [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden)

    2014-08-14

    The effects of heavy rare earth (RE) additions on the Curie temperature (T{sub C}) and magnetocaloric effect of the Fe-RE-B-Nb (RE = Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE element and its concentration can easily tune T{sub C} in a large temperature range of 120 K without significantly decreasing the magnetic entropy change (ΔS{sub M}) and refrigerant capacity (RC) of the alloys. The observed values of ΔS{sub M} and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd{sub 5}Ge{sub 1.9}Si{sub 2}Fe{sub 0.1}. The tunable T{sub C} and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.

  15. Progress in rare-earth-doped nanocrystalline glass-ceramics for laser cooling

    Science.gov (United States)

    Venkata Krishnaiah, Kummara; Ledemi, Yannick; Soares de Lima Filho, Elton; Loranger, Sebastien; Nemova, Galina; Messaddeq, Younes; Kashyap, Raman

    2016-03-01

    Laser cooling with anti-Stokes fluorescencewas predicted by Pringsheim in 1929, but for solids was only demonstrated in 1995. There are many difficulties which have hindered laser assisted cooling, principally the chemical purity of a sample and the availability of suitable hosts. Recent progress has seen the cooled temperature plummet to 93K in Yb:YLF. One of the challenges for laser cooling to become ubiquitous, is incorporating the rare-earthcooling ion in a more easily engineered material, rather than a pure crystalline host. Rare-earth-doped nanocrystalline glass-ceramics were first developed by Wang and Ohwaki for enhanced luminescence and mechanical properties compared to their parent glasses. Our work has focused on creating a nanocrystalline environment for the cooling ion, in an easy to engineer glass. The glasses with composition 30SiO2-15Al2O3-27CdF2-22PbF2-4YF3-2YbF3 (mol%), have been prepared by the conventional melt-quenching technique. By a simple post fabrication thermal treatment, the rare-earth ions are embedded in the crystalline phase within the glass matrix. Nanocrystals with various sizes and rare-earth concentrations have been fabricated and their photoluminescence properties assessed in detail. These materials show close to unity photoluminescence quantum yield (PLQY) when pumped above the band. However, they exhibit strong up-conversion into the blue, characteristic of Tm trace impurity whose presence was confirmed. The purification of the starting materials is underway to reduce the background loss to demonstrate laser cooling. Progress in the development of these nano-glass-ceramics and their experimental characterization will be discussed.

  16. A Wide Field Auroral Imager (WFAI for low Earth orbit missions

    Directory of Open Access Journals (Sweden)

    N. P. Bannister

    2007-03-01

    Full Text Available A comprehensive understanding of the solar wind interaction with Earth's coupled magnetosphere-ionosphere system requires an ability to observe the charged particle environment and auroral activity from the same platform, generating particle and photon image data which are matched in time and location. While unambiguous identification of the particles giving rise to the aurora requires a Low Earth Orbit satellite, obtaining adequate spatial coverage of aurorae with the relatively limited field of view of current space bourne auroral imaging systems requires much higher orbits. A goal for future satellite missions, therefore, is the development of compact, wide field-of-view optics permitting high spatial and temporal resolution ultraviolet imaging of the aurora from small spacecraft in low polar orbit. Microchannel plate optics offer a method of achieving the required performance. We describe a new, compact instrument design which can observe a wide field-of-view with the required spatial resolution. We report the focusing of 121.6 nm radiation using a spherically-slumped, square-pore microchannel plate with a focal length of 32 mm and an F number of 0.7. Measurements are compared with detailed ray-trace simulations of imaging performance. The angular resolution is 2.7±0.2° for the prototype, corresponding to a footprint ~33 km in diameter for an aurora altitude of 110 km and a spacecraft altitude of 800 km. In preliminary analysis, a more recent optic has demonstrated a full width at half maximum of 5.0±0.3 arcminutes, corresponding to a footprint of ~1 km from the same spacecraft altitude. We further report the imaging properties of a convex microchannel plate detector with planar resistive anode readout; this detector, whose active surface has a radius of curvature of only 100 mm, is shown to meet the spatial resolution and sensitivity requirements of the new wide field auroral imager (WFAI.

  17. Preparation, crystal structure, spectra and energy levels of the trivalent ytterbium ion doped into rare earth stannates

    Science.gov (United States)

    Ning, Kaijie; Zhang, Qingli; Sun, Dunlu; Yin, Shaotang; Jiang, Haihe

    2012-01-01

    Yb3+-doped Rare Earth Stannates Ln2Sn2O7(Ln=Y, Gd) with space group Fd3m were synthesized by co-precipitation technique. Their structures were determined by Rietveld refinement to their X-ray diffraction, and their atom coordinates, lattice parameters and temperature factors were given. From emission, absorption and excitation spectra, the energy levels of Yb3+ in Ln2Sn2O7(Ln=Y, Gd) were assigned and the crystal field parameters were fitted to energy splitting of Yb3+-doped Ln2Sn2O7 (Ln=Y, Gd).

  18. Structure and photoluminescence of TiO{sub 2} nanocrystals doped and co-doped with N and rare earths (Y{sup 3+}, Pr{sup 3+})

    Energy Technology Data Exchange (ETDEWEB)

    Ricci, P.C., E-mail: carlo.ricci@dsf.unica.it [Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. Monserrato-Sestu Km 0,700, 09042 Monserrato (Italy); Carbonaro, C.M.; Geddo Lehmann, A.; Congiu, F.; Puxeddu, B. [Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. Monserrato-Sestu Km 0,700, 09042 Monserrato (Italy); Cappelletti, G.; Spadavecchia, F. [Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano (Italy)

    2013-06-05

    Highlights: ► We studied singly and co-doped N, Y and Pr:TiO{sub 2} nanoparticles. ► A mixed anatase-brookite phase with average dimension lower than 10 nm was revealed. ► The nature of defects in the TiO{sub 2} structures depends on the doping elements. ► Bulk and surface defects are related to nitrogen in the TiO{sub 2} matrix. ► Y{sup 3+} ion acts as a surface stabilizer, Pr{sup 3+} generates surface recombination centers. -- Abstract: The structural and optical properties of sol–gel synthesized TiO{sub 2} nanoparticles doped and co-doped with N and rare earth ions (Y{sup 3+} and Pr{sup 3+}) are presented. Crystal structures, phase composition, and crystallite sizes are analyzed by powder X-ray diffraction and Raman spectroscopy. The analysis of intragap excited photoluminescence indicates the formation of radiative recombinations related to different defect centers in the TiO{sub 2} structure, generated by the presence of doping elements. In particular we assign the formation of bulk and surface defects to the presence of nitrogen in the TiO{sub 2} matrix, whereas we observe different effects on the defective TiO{sub 2} structure related to the two rare earths: the presence of Y{sup 3+} ion acts as a stabilizer of the TiO{sub 2} surface whereas the presence of Pr{sup 3+} generates surface recombination centers.

  19. Effect of hydroxyl groups on hydrophilic and photocatalytic activities of rare earth doped titanium dioxide thin films

    Institute of Scientific and Technical Information of China (English)

    杜军; 吴其; 钟汕; 顾馨; 刘娇; 郭海志; 张文龙; 彭海龙; 邹建国

    2015-01-01

    Rare earth (Y, La and Nd) doped TiO2 thin films were prepared on glass slides by sol-gel method. The photocatalytic de-composition of methylene blue in aqueous solution was used as a probe reaction to evaluate their photocatalytic activities. The effects of hydroxyl groups on hydrophilic and photocatalytic activities were investigated by means of techniques such as X-ray diffrac-tion (XRD), atomic force microscopy (AFM), Fourier transform infrared (FTIR), optical contact angle, UV-Visible spectroscopy and VIS spectroscopy. The results showed that an appropriate doping of rare earth could cause the TiO2 lattice distortion, inhib-ited phase transition from anatase to rutile, accelerated surface hydroxylation and produced more hydroxyl groups, which resulted in a denser surface and smaller grains (40–60 nm), and a significant improvement in the hydrophilicity and photoreactivity of TiO2 thin films. The optimal content of rare earth was between 0.1 wt.%and 0.3 wt.%. Moreover, the modification mechanism of rare earth doping was also discussed.

  20. Low Temperature Preparation of Ceria Solid Solutions Doubly Doped with Rare-Earth and Alkali-Earth and Their Properties as Solid Oxide Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    任引哲; 蒋凯; 王海霞; 孟健; 苏锵

    2003-01-01

    A series of solid electrolytes, (Ce0.8Ln0.2)1-xMxO2-δ (Ln= La, Nd, Sm, Gd, M:Alkali-earth), were prepared by amorphous citrate gel method. XRD patterns indicate that a pure fluorite phase is formed at 800 ℃. The electrical conductivity and the AC impedance spectra were measured. XPS spectra show that the oxygen vacancies increase owing to the MO doping, which results in the increase of the oxygen ionic transport number and conductivity. The performance of ceria-based solid electrolyte is improved. The effects of rare-earth and alkali-earth ions on the electricity were discussed. The open-circuit voltages and maximum power density of planar solid oxide fuel cell using (Ce0.8Sm0.2)1-0.05Ca0.05O2-δ as electrolyte are 0.86 V and 33 mW*cm-2, respectively.

  1. PHYSICAL AND ELECTRICAL PROPERTIES ENHANCEMENT OF RARE-EARTH DOPED-POTASSIUM SODIUM NIOBATE (KNN: A REVIEW

    Directory of Open Access Journals (Sweden)

    Akmal Mat Harttat Maziati

    2015-06-01

    Full Text Available Alkaline niobate mainly potassium sodium niobate, (KxNa1-x NbO3 (abreviated as KNN has long attracted attention as piezoelectric materials as its high Curie temperature (Tc and piezoelectric properties. The volatility of alkaline element (K, Na is, however detrimental to the stoichiometry of KNN, contributing to the failure to achieve high-density structure and lead to the formation of intrinsic defects. By partially doping of several rare-earth elements, the inherent defects could be improved significantly. Therefore, considerable attempts have been made to develop doped-KNN based ceramic materials with high electrical properties. In this paper, these research activities are reviewed, including dopants type and doping role in KNN perovskite structure.

  2. The unusually high Tc in rare-earth-doped single crystalline CaFe2As2

    Science.gov (United States)

    Wei, Fengyan; Lv, Bing; Deng, Liangzi; Meen, James K.; Xue, Yu-Yi; Chu, Ching-Wu

    2014-08-01

    In rare-earth-doped single crystalline CaFe2As2, the mysterious small volume fraction which superconducts up to 49 K, much higher than the bulk Tc ~ 30 s K, has prompted a long search for a hidden variable that could enhance the Tc by more than 30% in iron-based superconductors of the same structure. Here we report a chemical, structural and magnetic study of CaFe2As2 systematically doped with La, Ce, Pr and Nd. Coincident with the high Tc phase, we find extreme magnetic anisotropy, accompanied by an unexpected doping-independent Tc and equally unexpected superparamagnetic clusters associated with As vacancies. These observations lead us to conjecture that the tantalizing Tc enhancement may be associated with naturally occurring chemical interfaces and may thus provide a new paradigm in the search for superconductors with higher Tc.

  3. SWOT: The Surface Water and Ocean Topography Mission. Wide- Swath Altimetric Elevation on Earth

    Science.gov (United States)

    Fu, Lee-Lueng (Editor); Alsdorf, Douglas (Editor); Morrow, Rosemary; Rodriguez, Ernesto; Mognard, Nelly

    2012-01-01

    The elevation of the surface of the ocean and freshwater bodies on land holds key information on many important processes of the Earth System. The elevation of the ocean surface, called ocean surface topography, has been measured by conventional nadirlooking radar altimeter for the past two decades. The data collected have been used for the study of large-scale circulation and sea level change. However, the spatial resolution of the observations has limited the study to scales larger than about 200 km, leaving the smaller scales containing substantial kinetic energy of ocean circulation that is responsible for the flux of heat, dissolved gas and nutrients between the upper and the deep ocean. This flux is important to the understanding of the ocean's role in regulatingfuture climate change.The elevation of the water bodies on land is a key parameter required for the computation of storage and discharge of freshwater in rivers, lakes, and wetlands. Globally, the spatial and temporal variability of water storage and discharge is poorly known due to the lack of well-sampled observations. In situ networks measuring river flows are declining worldwide due to economic and political reasons. Conventional altimeter observations suffers from the complexity of multiple peaks caused by the reflections from water, vegetation canopy and rough topography, resulting in much less valid data over land than over the ocean. Another major limitation is the large inter track distance preventing good coverage of rivers and other water bodies.This document provides descriptions of a new measurement technique using radar interferometry to obtain wide-swath measurement of water elevation at high resolution over both the ocean and land. Making this type of measurement, which addresses the shortcomings of conventional altimetry in both oceanographic and hydrologic applications, is the objective of a mission concept called Surface Water and Ocean Topography (SWOT), which was recommended by

  4. Effect of rare earth ions doping on properties of LiFePO4/C cathode material

    Institute of Scientific and Technical Information of China (English)

    王丽; 焦昌梅; 梁广川; 赵南南; 王亚勉; 李琳慈

    2014-01-01

    LiFe0.99RE0.01PO4/C cathode material was synthesized by solid-state reaction method using FeC2O4·2H2O, Li2CO3, NH4H2PO4, RE(NO3)3·nH2O as raw materials and glucose as a carbon source. The doping effects of rare earth ions, such as La3+, Ce3+, Nd3+, on the structure and electrochemical properties of LiFePO4/C cathode material were systematically investigated. The as-prepared samples were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and particle size analysis. The electrochemical properties were investigated in terms of constant-current charge/discharge cycling tests.The XRD results showed that the rare earth ions doping did not change the olivine structure of LiFePO4, and all the doped samples were of single-phase with high crystallinity. SEM and particle size analysis results showed that the doping of La3+, Ce3+ and Nd3+ led to the decrease of particle size. The electrochemical results exhibited that the doping of La3+ and Ce3+ could improve the high-rate capability of LiFePO4/C cathode material, among which, the material doped with 1% Ce3+ exhibited the optimal elec-trochemical properties, whose specific discharge capacities could reach 128.9, 119.5 and 104.4 mAh/g at 1C, 2C and 5C rates, re-spectively.

  5. Recent progress on upconversion luminescence enhancement in rare-earth doped transparent glass-ceramics

    Institute of Scientific and Technical Information of China (English)

    邱建备; 焦清; 周大成; 杨正文

    2016-01-01

    The upconversion (UC) of the rare earth doped glass-ceramics has been extensively investigated due to their potential ap-plications in many fields, such as color display, high density memories, optical data storage, sensor and energy solar cell, etc. Many series of them, especially the oxyfluorides glasses containing Ba2LaF7 nanocrystals were studied in this review work, due to the ther-mal and mechanical toughness, high optical transmittance from the ultraviolet to the infrared regions, and a low nonlinear refractive index compared to the other commercial laser glasses. Moreover, the energy transfer (ET) between the rare earth ions and transition metals plays an important role in the upconversion process. The cooperative ET has been researched very activly in UC glasses due to applications in the fields of solar cells, such as in the Er/Yb, Tm/Yb, Tb/Yb, Tb/Er/Yb and Tm/Er/Yb couples. The present article re-views on the recent progress made on: (i) upconversion materials with fluoride microcrystals in glasses and the mechanisms involved, including the UC in double and tri-dopant RE ions activated fluoride microcrystal, energy transfer process; and (ii) the effect of the metal Mn and nanoparticles of Au, Ag, Cu on the enhancement of UC emissions. Discussions have also been made on materials, ma-terial synthesis, the structural and emission properties of glass-ceramics. Additionally, the conversion efficiency is still a challenge for the spectra conversion materials and application; challenge and future advances have also been demonstrated.

  6. Influence of Doping Rare Earth on Performance of Lithium Manganese Oxide Spinels as Cathode Materials for Lithium-Ion Batteries

    Institute of Scientific and Technical Information of China (English)

    Tang Zhiyuan; Zhang Na; Lu Xinghe; Huang Qinghua

    2005-01-01

    Some rare earth doping spinel LiMn2-xRExO4 (RE=La, Ce, Nd) cathode materials for lithium ion batteries were synthesized by the solid-state reaction method. The structure characteristics of these produced samples were investigated by XRD, SEM, and particle size distribution analysis. According to the microstructure and charge-discharge testing, the effect of doping rare earth on stabilizing the spinel structure was analyzed. Through a series of doping experiments, it is shown that when the doping content x within the range of 0.01~0.02 the cycle performance of the materials is greatly improved. The discharge capacity of the sample LiMn1.98La0.02O4, LiMn1.98Ce0.02O4 and LiMn1.98Nd0.02O4 remain 119.1, 114.2 and 117.5 mAh*g-1 after 50 cycles.

  7. The Effect of Ormosil Matrix Composition and Alkaline Earth Metal Doping on the Photochromic Response of Ormosil-Phosphotungstate Films

    OpenAIRE

    Ferreira Neto,Elias P.; Simões,Mateus B.; Noveletto,Julia C.; Yabarrena,Jean M. S. C.; Ullah,Sajjad; Ubirajara P. Rodrigues Filho

    2015-01-01

    In this study, polyoxometallate based hybrid photochromic materials were prepared by incorporating phosphotungstate anion, PW12O403−, (PW) in hybrid tetraethyl orthosilicate and (3-glycidyloxypropyl)trimethoxysilane TEOS-GPTMS derived organomodified silicates (Ormosil) matrices by sol-gel method and the resulting materials were used to prepare multilayer films by dip-coating method. The effect of alkaline earth metal cations doping and matrix composition (%GPTMS) on the photochromic res...

  8. Synthesis and characterization of rare earth doped novel optical materials and their potential applications

    Science.gov (United States)

    Pokhrel, Madhab

    There are many application of photonic materials but selection of photonic materials are always constrained by number of factors such as cost, availability of materials, thermal and chemical stability, toxicity, size and more importantly ease of synthesis and processing along with the efficient emission. For example, quantum dots are efficient emitter but they are significantly toxic, whereas dyes are also efficient emitters but they are chemically unstable. On the other hand, display and LED requires the micron size particles but bio application requires the nano-sized particles. On the other hand, laser gain media requires the ceramics glass or single crystal not the nanoparticles. So, realization of practical optical systems critically depends on suitable materials that offer specific combinations of properties. Solid-state powders such as rare-earth ions doped nano and micron size phosphors are one of the most promising candidates for several photonic applications discussed above. In this dissertation, we investigate the upconversion (UC) fluorescence characteristics of rare earth (RE) doped M2O2S (M = Y, Gd, La) oxysulphide phosphors, for near-infrared to visible UC. Both nano and micron size phosphors were investigated depending on their applications of interest. This oxysulphide phosphor possesses several excellent properties such as chemical stability, low toxicity and can be easily mass produced at low cost. Mainly, Yb3+, Er3+, and Ho3+ were doped in the host lattice, resulting in bright red, green, blue and NIR emissions under 980 nm and 1550 nm excitation at various excitation power densities. Maximum UC quantum yields (QY) up to 6.2 %, 5.8%, and 4.6% were respectively achieved in Yb3+/Er3+ :La2O2S, Y2O2S, and Gd2O 2S. Comparisons have been made with respect to reported most efficient upconverting phosphors beta-NaYF4:20 % Yb/ 2% Er. We believe that present phosphors are the most efficient and lower excitation threshold upconverting phosphors at 980 and

  9. Synthesis and structure of some nano-sized rare-earth metal ions doped potassium hexacyanoferrates

    Science.gov (United States)

    Narayan, Himanshu; Alemu, Hailemichael; Nketsa, Pusetso F.; Manatha, Toka J.; Madhavi Thakurdesai, And

    2015-05-01

    Rare-earth ions doped potassium hexacyanoferrates (KR-HCF); with the general formula KRFe(CN)6 · 3H2 O [with, R≡Y, Gd and Yb] nanoparticles were synthesized through precipitation. Characterization was done through particle-size analyzer, scanning electron microscopy (SEM), Fourier Transform infra-red (FTIR) and Raman spectroscopy, and powder X-ray diffraction (XRD). The XRD data was analyzed on FullProf Software Suite program and the unit-cell structure and lattice parameters of KR-HCF samples were determined from scratch and refined further. All the three KR-HCF nanoparticles seem to crystallize in the orthorhombic primitive PMMM space-group. Reasonably good agreement was found with the previously reported lattice constants of KGd-HCF and KYb-HCF orthorhombic single-crystals, except that they assume different space-groups. The observed dissimilarity of space-groups may be attributed to the different time scales involved in the synthesis process. Moreover, the crystal structure of KYFe(CN)6 · 3H2 O nanoparticles is being reported for the very first time.

  10. Photo-bleaching effect in divalent samarium-doped alkaline-earth fluorohalides

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Weiping [Chinese Academy of Sciences, Changchun (China); Jang, Kiwan; Cho, Hyungab; Chung, Yonghwa; Park, Seongtae; Lee, Yongill [Changwon National University, Changwon (Korea, Republic of); Kim, Changdae [Mokpo National University, Mokpo (Korea, Republic of)

    2004-08-15

    When a CW laser was focused on a sample of divalent samarium-doped alkaline-earth fluorohalides (Mg{sub 0.5}Sr{sub 0.5}FCl{sub 0.5}Br{sub 0.5} : Sm{sup 2+} or BaFCl{sub 0.5}Br{sub 0.5} : Sm{sup 2+}), the fluorescence intensity of Sm{sup +2} ions decreased rapidly. Under irradiation from a 488-nm laser with a power density of 10 W/cm{sup 2}, the intensity of the {sup 5}D{sub 0} -> {sup 7}F{sub 0} (Sm{sup 2+}) emission decreased as much as 96 % of its initial intensity in 30 minutes (for an X-ray-reduced sample). The so-called photo-bleaching effect can be influenced by the processes used for sample synthesis, such as the reduction method, the grinding process or X-ray irradiation. The decreasing curves obtained in the photo-bleaching experiments were fitted, a biexponential decreasing mode was found, which included a fast decrease (time constant {approx}tens of seconds) and a slow decrease (time constant {approx}hundreds of seconds). There was no evidence to support the divalent samarium ions being photo-ionized into trivalent samarium ions in the photobleaching process. The most probable mechanism for the photo-bleaching effect involves structural defects and color centers in the samples.

  11. Development of novel rare earth doped fluoride and oxide scintillators for two-dimensional imaging

    Institute of Scientific and Technical Information of China (English)

    A. Yoshikawa; T. Iguchi; G. Boulon; M. Nikd; T. Yanagida; Y. Yokota; K. Kamada; N. Kawaguchi; K. Fukuda; A. Yamazaki; K. Watanabe; A. Uritani

    2011-01-01

    Two topics were focused.The first one was about the gamma-ray scintillator,pr3+:Lu3Al5O12 (LuAG).The second one was about neutron scintillator,Ce3+:6LiCaAlF6 and Eu2+:6LiCaAlF6 (6LiCAF).Those scintillators have been developed very recently for modem imaging applications in the medical and homeland security fields.In both cases,the rare earth ions are playing the crucial role as emission centers.Pr3+ in LuAG provided fast 5d→4f transition providing noticeably shorter decay time than that of Ce3+.Among several candidate hosts,LuAG showed the best performance.Bulk crystal growth,basic scintillation properties,two-dimensional gamma-ray imaging and positron emission mammography (PEM) application were demonstrated.Due to the international situation,the homeland security was compromized by illicit traffic of explosives,drugs,nuclear materials,etc.and the ways to its improvement became an important R&D topic.For this purpose the Ce and Eu doped LiCAF appeared competitive candidates.Especially,when substitution of 3He neutron detectors was considered,the discrimination ability of gamma-ray from alpha-ray was important.Bulk crystal growth,basic scintillation properties and two-dimensional neutron imaging were demonstrated.

  12. Ceramics and amorphous thin films based on gallium sulphide doped by rare-earth sulphides

    Science.gov (United States)

    Popescu, M.; Sava, F.; Lőrinczi, A.; Velea, A.; Simandan, I. D.; Badica, P.; Burdusel, M.; Galca, A. C.; Matei, E.; Preda, N.; Secu, M.; Socol, G.; Jipa, F.; Zamfirescu, M.; Balan, A.

    2015-04-01

    Bulk ceramics of Ga2S3 and rare-earth sulfides (EuS, Gd2S3, Er2S3) as well as combinations thereof have been prepared by spark plasma sintering (SPS). The disk-shaped ceramics were used as targets for pulsed laser deposition (PLD) experiments to obtain amorphous thin films. The properties of these new bulks and amorphous thin films have been investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), optical transmission spectroscopy, and atomic force microscopy (AFM). In order to test the photoexpansion effect in Ga2S3 and the possibility to create planar arrays of microlenses, the film was irradiated with femtosecond laser pulses at different powers. For low laser power pulses (up to 100 mW power per pulse) a photoexpansion effect was observed, which leads to formation of hillocks with a height of 40-50 nm. EuS doped Ga2S3 thin film shows luminescence properties, which recommend them for optoelectronic applications.

  13. Rare Earth Doped III-Nitrides for Optoelectronic and Spintronic Applications

    CERN Document Server

    O’Donnell, Kevin

    2010-01-01

    This book provides a snapshot of recent progress in the field of rare-earth-doped group III-nitride semiconductors, especially GaN, but extending to AlN and the alloys AlGaN, AlInN and InGaN. This material class is currently enjoying an upsurge in interest due to its ideal suitability for both optoelectronic and spintronic applications. The text first introduces the reader to the historical background and the major theoretical challenges presented when 4f electron systems are embedded in a semiconductor matrix. It details the preparation of samples for experimental study, either by in-situ growth or ion implantation/annealing, and describes their microscopic structural characterisation. Optical spectroscopy is a dominant theme, complicated by site multiplicity, whether in homogeneous hosts or in heterostructures such as quantum dots, and enlivened by the abiding fascination of the energy transfer mechanism between the host material and the lumophore. Finally, the rapid progress towards prospective optoelectro...

  14. Rare-earth doped colour tuneable up-conversion ZBLAN phosphor for enhancing photocatalysis

    Science.gov (United States)

    Méndez-Ramos, J.; Acosta-Mora, P.; Ruiz-Morales, J. C.; Sierra, M.; Redondas, A.; Ruggiero, E.; Salassa, L.; Borges, M. E.; Esparza, P.

    2015-03-01

    Rare-earth doped ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fluoride glasses have been successfully synthesized showing outstanding UV-VIS up-conversion luminescence of Er3+ and Tm3+, sensitized by Yb3+ ions, under near-infrared excitation at 980 nm. The ratio between blue, green and red up-conversion emission bands can be adjusted by varying the pump power density of the incident infrared radiation, resulting in a controlled tuneability of the overall emitting colour from greenish to yellowish. Additionally, the observed high energy UV intense up-conversion emissions are suitable to enhance photocatalytic activity of main water-splitting semiconductor electrodes (such as TiO2) used in sustainable production of hydrogen. Photocatalysis and photolysis degradation of methylene blue in water under sun-like irradiation using benchmark photocatalyst (TiO2 Degussa P25) have been boosted by 20% and by a factor of 2.5 respectively, due to the enhancement of UV radiation that reaches the TiO2 particles by the addition of ZBLAN powder into a slurry-type photo-reactor. Hence, up-conversion ZBLAN phosphors contribute to demonstrate the possibility of transforming the incoming infrared radiation into the UV region needed to bridge the gap of photocatalytic semiconductors.

  15. Structure-property-composition relationships in doped zinc oxides: enhanced photocatalytic activity with rare earth dopants.

    Science.gov (United States)

    Goodall, Josephine B M; Illsley, Derek; Lines, Robert; Makwana, Neel M; Darr, Jawwad A

    2015-02-09

    In this paper, we demonstrate the use of continuous hydrothermal flow synthesis (CHFS) technology to rapidly produce a library of 56 crystalline (doped) zinc oxide nanopowders and two undoped samples, each with different particle properties. Each sample was produced in series from the mixing of an aqueous stream of basic zinc nitrate (and dopant ion or modifier) solution with a flow of superheated water (at 450 °C and 24.1 MPa), whereupon a crystalline nanoparticle slurry was rapidly formed. Each composition was collected in series, cleaned, freeze-dried, and then characterized using analytical methods, including powder X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area measurement, X-ray photoelectron spectroscopy, and UV-vis spectrophotometry. Photocatalytic activity of the samples toward the decolorization of methylene blue dye was assessed, and the results revealed that transition metal dopants tended to reduce the photoactivity while rare earth ions, in general, increased the photocatalytic activity. In general, low dopant concentrations were more beneficial to having greater photodecolorization in all cases.

  16. Direct quantification of rare earth doped titania nanoparticles in individual human cells

    Science.gov (United States)

    Jeynes, J. C. G.; Jeynes, C.; Palitsin, V.; Townley, H. E.

    2016-07-01

    There are many possible biomedical applications for titania nanoparticles (NPs) doped with rare earth elements (REEs), from dose enhancement and diagnostic imaging in radiotherapy, to biosensing. However, there are concerns that the NPs could disintegrate in the body thus releasing toxic REE ions to undesired locations. As a first step, we investigate how accurately the Ti/REE ratio from the NPs can be measured inside human cells. A quantitative analysis of whole, unsectioned, individual human cells was performed using proton microprobe elemental microscopy. This method is unique in being able to quantitatively analyse all the elements in an unsectioned individual cell with micron resolution, while also scanning large fields of view. We compared the Ti/REE signal inside cells to NPs that were outside the cells, non-specifically absorbed onto the polypropylene substrate. We show that the REE signal in individual cells co-localises with the titanium signal, indicating that the NPs have remained intact. Within the uncertainty of the measurement, there is no difference between the Ti/REE ratio inside and outside the cells. Interestingly, we also show that there is considerable variation in the uptake of the NPs from cell-to-cell, by a factor of more than 10. We conclude that the NPs enter the cells and remain intact. The large heterogeneity in NP concentrations from cell-to-cell should be considered if they are to be used therapeutically.

  17. First-principles prediction of Si-doped Fe carbide as one of the possible constituents of Earth's inner core

    Science.gov (United States)

    Das, Tilak; Chatterjee, Swastika; Ghosh, Sujoy; Saha-Dasgupta, Tanusri

    2017-09-01

    We perform a computational study based on first-principles calculations to investigate the relative stability and elastic properties of the doped and undoped Fe carbide compounds at 200-364 GPa. We find that upon doping a few weight percent of Si impurities at the carbon sites in Fe7C3 carbide phases, the values of Poisson's ratio and density increase while VP, and VS decrease compared to their undoped counterparts. This leads to marked improvement in the agreement of seismic parameters such as P wave and S wave velocity, Poisson's ratio, and density with the Preliminary Reference Earth Model (PREM) data. The agreement with PREM data is found to be better for the orthorhombic phase of iron carbide (o-Fe7C3) compared to hexagonal phase (h-Fe7C3). Our theoretical analysis indicates that Fe carbide containing Si impurities can be a possible constituent of the Earth's inner core. Since the density of undoped Fe7C3 is low compared to that of inner core, as discussed in a recent theoretical study, our proposal of Si-doped Fe7C3 can provide an alternative solution as an important component of the Earth's inner core.

  18. Improving the Photoelectric Characteristics of MoS2 Thin Films by Doping Rare Earth Element Erbium

    Science.gov (United States)

    Meng, Miaofei; Ma, Xiying

    2016-11-01

    We investigated the surface morphologies, crystal structures, and optical characteristics of rare earth element erbium (Er)-doped MoS2 (Er: MoS2) thin films fabricated on Si substrates via chemical vapor deposition (CVD). The surface mopography, crystalline structure, light absorption property, and the photoelectronic characteristics of the Er: MoS2 films were studied. The results indicate that doping makes the crystallinity of MoS2 films better than that of the undoped film. Meanwhile, the electron mobility and conductivity of the Er-doped MoS2 films increase about one order of magnitude, and the current-voltage ( I- V) and the photoelectric response characteristics of the Er:MoS2/Si heterojunction increase significantly. Moreover, Er-doped MoS2 films exhibit strong light absorption and photoluminescence in the visible light range at room temperature; the intensity is enhanced by about twice that of the undoped film. The results indicate that the doping of MoS2 with Er can significantly improve the photoelectric characteristics and can be used to fabricate highly efficient luminescence and optoelectronic devices.

  19. Scintillation properties of rare-earth doped NaPO3-Al(PO3)3 glasses

    Science.gov (United States)

    Kuro, Tomoaki; Okada, Go; Kawaguchi, Noriaki; Fujimoto, Yutaka; Masai, Hirokazu; Yanagida, Takayuki

    2016-12-01

    We systematically investigated photoluminescence (PL), scintillation and dosimeter properties of rare-earth (RE) doped NaPO3-Al(PO3)3 (NAP) glasses. The NAP glasses doped with a series of RE ions (La-Yb, except Pm) with a consistent concentration (0.3 wt%) were prepared by the conventional melt-quenching method. The PL and scintillation decay time profiles showed fast (ns) and slow (μs or ms) components: the fast components from 15 to 100 ns were due to the host or 5d-4f transition emission, and the slow components from 15 μs to 5 ms were due to the 4f-4f transitions of RE. The thermally stimulated luminescence (TSL) was evaluated as a dosimeter property, and glow peaks appeared around 400 °C in all the samples. The TSL dose response function was examined in the dose range from 10 mGy to 10 Gy. Among the samples tested, Nd and Tb doped glasses showed higher signal by at least one order of magnitude than those of non-doped and other RE-doped samples. Over the dose range tested, the TSL signals are linearly related with the incident X-ray dose, showing a potential for practical applications.

  20. Slow and fast light via two-wave mixing in the rare-earth doped optical fibers (Conference Presentation)

    Science.gov (United States)

    Stepanov, Serguei I.; Plata Sánchez, Marcos; Hernández, Eliseo

    2017-02-01

    Dynamic population Bragg gratings can be recorded in the rare-earth-doped (e.g. doped with erbium or ytterbium) optical fibers with mWatt-scale cw laser power. Two-wave mixing (TWM) via such gratings is utilized in single-frequency fiber lasers and in adaptive interferometric fiber sensors with automatic stabilization of the operation point. Slow and fast light propagation can also be observed in the vicinity of narrow ( 20-200Hz) spectral profile of stationary no-degenerate TWM. In particular, slow light propagation is observed for the purely amplitude grating, recorded in the erbium-doped fiber in spectral range 1510-1550nm. In its turn, in ytterbium-doped fibers at 1064nm (or in erbium-doped fiber at the wavelength below 1500nm) the dynamic grating has significant contribution of the phase component, the TWM profile has essentially asymmetric form, and both slow and fast (superluminal) light propagation is possible at different frequency off-sets between the counter-propagating interacting waves.

  1. Rare earth oxides doped NiO/γ-Al2O3 catalyst for oxidative dehydrogenation of cyclohexane

    Institute of Scientific and Technical Information of China (English)

    Hany M AbdelDayem; M Faiz; Hesham S Abdel-Samad; Salah A Hassan

    2015-01-01

    The effect of rare earth oxides (RE=Ce, La, Gd, and Dy) doping of alumina support in NiO/γ-Al2O3 system was investi-gated on its catalytic performance in oxidative dehydrogenation (ODH) of cyclohexane. The physicochemical properties of various samples were followed up through N2 physisorption, temperature programmed reduction (H2-TPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and potentiometric acid-base titration techniques. In the parent NiO/γ-Al2O3 catalyst, Ni species were found to be strongly interacted with alumina surface. Addition of rare earth dopants toγ-Al2O3 in the catalyst system affected the nickel-alumina interaction and resulted in significant modifications in the catalytic performances in the ODH reaction. The results re-vealed the beneficial role of both La2O3 and Gd2O3 doping in enhancing the ODH catalytic activity and selectivity to cyclohexene. H2-TPR and XPS results indicated that majority of Ni species in NiO/La2O3 modifiedγ-Al2O3 were more weakly interacted with La2O3 and alumina whereas both NiO like species and nickel aluminate were present on the surface. Doping with cerium or dyspro-sium increased the nickel-support interaction and led to a decrease in surface nickel concentration. In case of doping with Ce, surface concentration of cerium oxide was higher than those of the other RE oxides; the doped catalyst reached its steady state activity faster than the other catalysts. The acid-base results suggested that RE metals were interacted most likely with acidic surface hydroxyl groups. The degree of nickel-alumina interaction decreased in the following order: LaAl>GdAl>CeAl>DyAl.

  2. Potency of (doped) rare earth oxide particles and their constituent metals to inhibit algal growth and induce direct toxic effects.

    Science.gov (United States)

    Joonas, Elise; Aruoja, Villem; Olli, Kalle; Syvertsen-Wiig, Guttorm; Vija, Heiki; Kahru, Anne

    2017-03-27

    Use of rare earth elements (REEs) has increased rapidly in recent decades due to technological advances. It has been accompanied by recurring rare earth element anomalies in water bodies. In this work we (i) studied the effects of eight novel doped and one non-doped rare earth oxide (REO) particles (aimed to be used in solid oxide fuel cells and gas separation membranes) on algae, (ii) quantified the individual adverse effects of the elements that constitute the (doped) REO particles and (iii) attempted to find a discernible pattern to relate REO particle physicochemical characteristics to algal growth inhibitory properties. Green algae Raphidocelis subcapitata (formerly Pseudokirchneriella subcapitata) were used as a test species in two different formats: a standard OECD201 algal growth inhibition assay and the algal viability assay (a 'spot test') that avoids nutrient removal effects. In the 24h 'spot' test that demonstrated direct toxicity, algae were not viable at REE concentrations above 1mgmetal/L. 72-hour algal growth inhibition EC50 values for four REE salts (Ce, Gd, La, Pr) were between 1.2 and 1.4mg/L, whereas the EC50 for REO particles ranged from 1 to 98mg/L. The growth inhibition of REEs was presumably the result of nutrient sequestration from the algal growth medium. The adverse effects of REO particles were at least in part due to the entrapment of algae within particle agglomerates. Adverse effects due to the dissolution of constituent elements from (doped) REO particles and the size or specific surface area of particles were excluded, except for La2NiO4. However, the structure of the particles and/or the varying effects of oxide composition might have played a role in the observed effects. As the production rates of these REO particles are negligible compared to other forms of REEs, there is presumably no acute risk for aquatic unicellular algae.

  3. Doping Effects of Rare Earth on Dielectric Properties of Fine-Grained BaTiO3-Based Ceramics

    Institute of Scientific and Technical Information of China (English)

    李玲霞; 郭炜; 吴霞宛; 王洪儒; 张志萍

    2003-01-01

    The doping effects of rare earth oxides Ho2O3 and Er2O3 on dielectric properties of BaTiO3-based ceramics were studied. After adding rare earth elements, grain growth in this system was inhibited and the grain size was reduce devidently which realized the fine-grained effect. In this system, the trivalent oxides Ho2O3 and Er2O3 were added to BaTiO3 ceramics. The rare earth oxides do not enter into inner lattice totally to replace A or B sites. Some of additives can improve dielectric strength by forming nonferroelectric phases, and the rest maintained at grain boundaries controls overgrowth of grains. The dielectric constant at room temperature is increased up to 3000 and the curve of TCC becomes flat. Meanwhile, the dielectric strength Eb becomes higher.

  4. Preparation and adsorption mechanism of rare earth-doped adsorbent for arsenic(V) removal from groundwater

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Yu; (张; 昱); YANG; Min; (杨; 敏); GAO; Yingxin; (高迎新); WANG; Feng; (王; 峰); HUANG; Xia; (黄; 霞)

    2003-01-01

    Several types of rare earth metal-doped iron oxide adsorbents were prepared and their arsenic(As(V)) removal performance was evaluated. The cerium(Ce(IV))-doped adsorbent (CFA4) has the highest adsorption capacity. The crystalline properties (XRD), surface charge, FTIR and X-ray photoelectron spectroscopy (XPS) were determined for CFA. Based on the results of XRD, introduction of Ce(IV) ions into Fe(II)/Fe(III) systems results in the co-existence of Ce and Fe with the formation of minicrystals. The pHzpc (the pH value at which surface charge is zero) of CFA is 5.8 by the measurement of the acid-base titration method. By FTIR measurements, it is shown that the substitution of M-OH groups at CFA surface by As(V) ions plays an important role in the adsorption mechanisms of CFA. XPS spectra of CFA before and after adsorption of As demonstrate that Fe atom might be activated for As removal as a result of rare earth metal (Ce) doping.

  5. Effect of rare earth doping on thermo-physical properties of lanthanum zirconate ceramic for thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hongming; YI Danqing

    2008-01-01

    The effect of rare earth doping on thermo-physical properties of lanthanum zirconate was investigated. Oxide powders of various compositions La2Zr2O7 were synthesized by coprecipitation-calcination method. High-temperature dilatometer, DSC, and laser thermal dif-fusivity methods were used to analyze thermal expansion coefficient (TEC), specific heat, and thermal diffusivity. The results showed that CeO2 doped pyrochlores La2(Zr1.8Ce0.2)2O7 and La1.7(DyNd)0.15(Zr0.8Ce0.2)2O7 had higher TEC than La2Zr2O7 and Lal.7Dyo.3Zr207. La2(Zr1.8Ce0.2)2O7, La1.7Oy0.3Zr2O7, and La1.7(DyNd)0.15(Zr0.8Ce0.2)2O7 had lower thermal conductivity than undoped La2Zr2O7. The Dy203, Nd2O3, and CeO2 codoped composition showed the lowest thermal conductivity and the highest TEC. Thermo-physical results also indicated that TEC of rare earth oxide doped La2Zr2O7 ceramic was slightly higher than that of conventional ZrO2-8wt.% Y2O3 (8YSZ), and its thermal conductivity was lower than that of 8YSZ.

  6. Down Converter Device Combining Rare-Earth Doped Thin Layer and Photonic Crystal for c-Si Based Solar Cell

    CERN Document Server

    Deschamps, Thierry; Peretti, Romain; Lalouat, Loïc; Fourmond, Erwann; Fave, Alain; Guille, Antoine; Pereira, António; Moine, Bernard; Seassal, Christian

    2013-01-01

    The aim of the study is to develop ultra-compact structures enabling an efficient conversion of single high energy photon (UV) to two lower energy photons (IR). The proposed structure combines rare-earths doped thin layer allowing the down-conversion process with a photonic crystal (PhC), in order to control and enhance the down-conversion using optical resonances. On the top of the rare-earths doped layer, a silicon nitride (SiN) 2D planar PhC is synthesized. For that, SiN is first deposited by PECVD. After holographic lithography and reactive ion etching, a periodic square lattice of holes is generated on the SiN layer. The PhC topographical parameters as well as the layers thickness are optimized using Finite-Difference-Time-Domain simulations. The design and realization of such PhC-assisted down-converter structures is presented. Optical simulations demonstrate that the PhC leads to the establishment of resonant modes located in the underneath doped layer, allowing a drastic enhancement of the absorption ...

  7. Evidence for interface superconductivity in rare-earth doped CaFe2As2 single crystals

    Science.gov (United States)

    Lv, Bing; Deng, L. Z.; Wei, F. Y.; Xue, Y. Y.; Chu, C. W.

    2014-03-01

    To unravel to the mysterious non-bulk superconductivity up to 49K observed in rare-earth (R =La, Ce, Pr and Nd) doped CaFe2As2 single-crystals whose Tc is higher than that of any known compounds consisting of one or more of its constituent elements of R, Ca, Fe, and As at ambient or under pressures, systematic magnetic, compositional and structural have carried out on different rare-earth-doped (Ca1-xRx) Fe2As2 samples. We have detected extremely large magnetic anisotropy, doping-level independent Tc, unexpected superparamagnetic clusters associated with As vacancies and their close correlation with the superconducting volume fraction, the existence of mesoscopic-2D structures and Josephson-junction arrays in this system. These observations lead us to conjecture that the Tc enhancement may be associated with naturally occurring chemical interfaces and thus provided evidence for the possible interface-enhanced Tc in naturally-grown single crystals of Fe-based superconductors.

  8. Laser refrigeration of rare-earth doped sodium-yttrium-fluoride nanowires

    Science.gov (United States)

    Zhou, Xuezhe; Roder, Paden B.; Smith, Bennett E.; Pauzauskie, Peter J.

    2017-02-01

    Hexagonal sodium yttrium fluoride (β-NaYF4) crystals are currently being studied for a wide range of applications including color displays, solar cells, photocatalysis, and bio-imagβing. β-NaYF4 has also been predicted to be a promising host material for laser refrigeration of solids. However, due to challenges with growing Czochralski β- NaYF4 single-crystals, laser refrigeration of bulk β-NaYF4 has not yet been achieved6. Recently hydrothermal processing has been reported to produce Yb-doped β-NaYF4 nanowires (NWs) that undergo laser refrigeration during single-beam optical trapping experiments in heavy water. The local refrigeration of the individual nanowire is quantified through the analysis of its Brownian motion through the analysis of forward scattered light that is focused onto a quadrant photodiode. The individual β-NaYF4 nanowires show maximum local cooling of 9°C below ambient conditions. Here we present the emission lifetime for the 4S3/2 - 4I15/2 transition for Er(III) ions in Yb/Er-codoped -NaYF4 NW ensembles was measured to be (220 +/- 6) μs using a an electron multiplying charge coupled device (EMCCD) as a detector with high spatial resolution. This lifetime is consistent with values reported in the literature.

  9. A density functional theory study of electronic and magnetic properties of rare earth doped monolayered molybdenum disulphide

    Science.gov (United States)

    Majid, Abdul; Imtiaz, Anum; Yoshiya, Masato

    2016-10-01

    The effects of Rare Earth (RE) atoms Sm, Eu, Gd, Tb, and Dy doping on structural, electronic, and magnetic properties of single layer MoS2 were investigated using first principles calculations. The analysis of electronic properties pointed out the appearance of host-impurity hybrid states on the edges of principal bands of the material, which appeared to cause narrowing of its bandgap. The values of total magnetic moment were calculated as 3.3 μB, 8.1 μB, 8.5 μB, 6.8 μB, and 6.4 μB for Sm-, Eu-, Gd-, Tb-, and Dy-doped MoS2, respectively. The underestimation of magnetic moment in the case of Sm doping is found which is assigned to shielding of 4f moments and quenching of angular momentum caused by Sm 4f-S 3p hybridization. On the other hand, the observed overestimation of magnetic moments for Eu and Gd cases is likely to be due to increase in angular momentum due to indirect exchange interaction of highly localized 4f states via 5d or 6s conduction electrons. The findings of this work point out the possibilities of tuning the band gap and magnetic properties of monolayer MoS2 upon RE doping for realization of p-type ferromagnetic semiconductors.

  10. Microstructure and properties of in-flight rare-earth doped thermal barrier coatings prepared by suspension plasma spray

    Science.gov (United States)

    Gong, Stephanie

    Thermal barrier coatings with lower thermal conductivity improve the efficiency of gas turbine engines by allowing higher operating temperatures. Recent studies were shown that coatings containing a pair of rare-earth oxides with equal molar ratio have lower thermal conductivity and improved sintering resistance compared to the undoped 4-4.5 mol.% yttria-stabilized zirconia (YSZ). In the present work, rare-earth doped coatings were fabricated via suspension plasma spray by spraying YSZ powder-ethanol suspensions that contained dissolved rare-earth nitrates. The compositions of the coatings determined by inductively coupled plasma mass spectroscopy verified that 68 +/- 8% of the rare-earth nitrates added into the suspension was incorporated into the coatings. Two coatings containing different concentrations of the same dopant pair (Nd2O3/Yb2O3), and three coatings having similar concentrations of different dopant pairs (Nd 2O3/Yb2O3, Nd2O3/Gd 2O3, and Gd2O3/Yb2O 3) were produced and compared. The effect of dopant concentration and dopant pair type on the microstructure and properties of the coatings in the as-sprayed and heat treated conditions were investigated using XRD, SEM, TEM, STEM-EDX, and the laser flash method. The cross-sectional morphology of all coatings displayed columnar structure. The porosity content of the coating was found to increase with increasing dopant concentration, but did not significantly change with dopant pairs. Similarly, increasing the Nd2O3/Yb2O 3 concentration lowered the thermal conductivity of the as-sprayed coatings. Although the effect of changing dopant pair type is not as significant as increasing the dopant concentration, the coating that contained Gd2O 3/Yb2O3 exhibited the lowest conductivity compared to coatings that had other dopant pairs. Thermal conductivity measurement performed on the heat treated coatings indicated a larger conductivity increase for the rare-earth doped coatings. A detailed study on the

  11. Highly Active Rare-Earth-Metal La-Doped Photocatalysts: Fabrication, Characterization, and Their Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    S. Anandan

    2012-01-01

    Full Text Available Efficient La-doped TiO2 photocatalysts were prepared by sol-gel method and extensively characterized by various sophisticated techniques. The photocatalytic activity of La-doped TiO2 was evaluated for the degradation of monocrotophos (MCPs in aqueous solution. It showed higher rate of degradation than pure TiO2 for the light of wavelength of 254 nm and 365 nm. The rate constant of TiO2 increases with increasing La loading and exhibits maximum rate for 1% La loading. The photocatalytic activities of La-doped TiO2 are compared with La-doped ZnO; the reaction rate of the former is ~1.8 and 1.1 orders higher than the latter for the lights of wavelength 254 nm and 365 nm, respectively. The relative photonic efficiency of La-doped TiO2 is relatively higher than La-doped ZnO and commercial photocatalysts. Overall, La-doped TiO2 is the most active photocatalyst and shows high relative photonic efficiencies and high photocatalytic activity for the degradation of MCP. The enhanced photocatalytic activity of La-doped TiO2 is mainly due to the electron trapping by lanthanum metal ions, small particle size, large surface area, and high surface roughness of the photocatalysts.

  12. Rare-earth doped nanocomposites enable multiscale targeted short-wave infrared imaging of metastatic breast cancer

    Science.gov (United States)

    Pierce, Mark C.; Higgins, Laura M.; Ganapathy, Vidya; Kantamneni, Harini; Riman, Richard E.; Roth, Charles M.; Moghe, Prabhas V.

    2017-02-01

    We are investigating the ability of targeted rare earth (RE) doped nanocomposites to detect and track micrometastatic breast cancer lesions to distant sites in pre-clinical in vivo models. Functionalizing RE nanocomposites with AMD3100 promotes targeting to CXCR4, a recognized marker for highly metastatic disease. Mice were inoculated with SCP-28 (CXCR4 positive) and 4175 (CXCR4 negative) cell lines. Whole animal in vivo SWIR fluorescence imaging was performed after bioluminescence imaging confirmed tumor burden in the lungs. Line-scanning confocal fluorescence microscopy provided high-resolution imaging of RE nanocomposite uptake and native tissue autofluorescence in ex vivo lung specimens. Co-registered optical coherence tomography imaging allowed assessment of tissue microarchitecture. In conclusion, multiscale optical molecular imaging can be performed in pre-clinical models of metastatic breast cancer, using targeted RE-doped nanocomposites.

  13. Preparation of Ultrahigh Potential Gradient of ZnO Varistors by Rare-Earth Doping and Low-Temperature Sintering

    Directory of Open Access Journals (Sweden)

    Lei Ke

    2013-01-01

    Full Text Available The effects of rare-earth doping and low-temperature sintering on electrical properties of ZnO varistors were investigated. The potential gradient (E1mA of the ZnO varistors increased significantly to 2247.2 V/mm after doping 0.08 mol% of Y2O3 and sintering at 800°C for 2 h. The notable decrease of the grain size with the given experimental conditions was the origin for the increase in E1mA. During the process of high-temperature sintering, both the oxygen at the grain boundary interface and the neutralisation of the ions on the depletion layer were directly reduced, which caused the weight loss and the internal derangement of double Schottky barriers.

  14. Measurement of a wide-range of X-ray doses using specialty doped silica fibres

    Science.gov (United States)

    Abdul Sani, S. F.; Hammond, R.; Jafari, S. M.; Wahab, Norfadira; Amouzad Mahdiraji, G.; Siti Shafiqah, A. S.; Abdul Rashid, H. A.; Maah, M. J.; Aldousari, H.; Alkhorayef, M.; Alzimami, M.; Bradley, D. A.

    2017-08-01

    Using six types of tailor-made doped optical fibres, we carry out thermoluminescent (TL) studies of X-rays, investigating the TL yield for doses from 20 mGy through to 50 Gy. Dosimetric parameters were investigated for nominal 8 wt% Ge doped fibres that in two cases were co-doped, using B in one case and Br in the other. A comparative measurement of surface analysis has also been made for non-annealed and annealed capillary fibres, use being made of X-ray Photoelectron Spectroscopy (XPS) analysis. Comparison was made with the conventional TL phosphor LiF in the form of the proprietary product TLD-100, including dose response and glow curves investigated for X-rays generated at 60 kVp over a dose range from 2 cGy to 50 Gy. The energy response of the fibres was also performed for X-rays generated at peak accelerating potentials of 80 kVp, 140 kVp, 250 kVp and 6 MV photons for an absorbed dose of 2 Gy. Present results show the samples to be suitable for use as TL dosimeters, with good linearity of response and a simple glow curve (simple trap) distribution. It has been established that the TL performance of an irradiated fibre is not only influenced by radiation parameters such as energy, dose-rate and total dose but also the type of fibre.

  15. Magnetic properties of rare-earth-doped La0.7Sr0.3MnO3

    Science.gov (United States)

    Veverka, Pavel; Kaman, Ondřej; Knížek, Karel; Novák, Pavel; Maryško, Miroslav; Jirák, Zdeněk

    2017-01-01

    Rare-earth-doped ferromagnetic manganites La0.63RE0.07Sr0.30MnO3 (RE  =  Gd, Tb, Dy, and Ho) are synthesized in the form of sintered ceramics and nanocrystalline phases with the mean size of crystallites  ≈30 nm. The electronic states of the dopants are investigated by SQUID magnetometry and theoretically interpreted based on the calculations of the crystal field splitting of rare-earth energy levels. The samples show the orthorhombic perovskite structure of Ibmm symmetry, with a complete FM order of Mn spins in bulk and reduced order in nanoparticles. Non-zero moments are also detected at the perovskite A sites, which can be attributed to magnetic polarization of the rare-earth dopants. The measurements in external field up to 70 kOe show a standard Curie-type contribution of the spin-only moments of Gd3+ ions, whereas Kramers ions Dy3+ and non-Kramers ions Ho3+ contribute by Ising moments due to their doublet ground states. The behaviour of non-Kramers ions Tb3+ is anomalous, pointing to singlet ground state with giant Van Vleck paramagnetism. The Tb3+ doping leads also to a notably increased coercivity compared to other La0.63RE0.07Sr0.30MnO3 systems.

  16. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO{sub 2} fiber

    Energy Technology Data Exchange (ETDEWEB)

    Katsumata, Toru, E-mail: katsumat@toyo.jp; Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki [Faculty of Science and Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585 (Japan)

    2014-08-15

    Visible light thermal radiation from SiO{sub 2} glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO{sub 2} fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO{sub 2} fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO{sub 2} fibers are smaller than those from SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO{sub 2} are potentially applicable for the fiber-optic thermometry above 900 K.

  17. White upconversion of rare-earth doped ZnO nanocrystals and its dependence on size of crystal particles and content of Yb3+ and Tm3+

    Science.gov (United States)

    Liu, Yunxin; Xu, Changfu; Yang, Qibin

    2009-04-01

    Rare earth (RE) doped ZnO nanocrystals were synthesized by chemical combustion method. Bright white upconversion (UC) luminescence with the CIE coordinates close to (0.33, 0.33) was obtained in Er+Tm+Yb tridoped ZnO nanocrystals under the excitation of a cost-effective 980 nm single-wavelength laser diode. The overall and relative UC luminescence intensities of RE doped ZnO nanocrystals were found to be depended highly on the diameter of crystal particles and the concentration of Yb3+ and Tm3+, for which the involved mechanisms were demonstrated. The investigation based on UC spectra, simplified energy level diagram, and excitation power dependence indicated that the remarkable enhancement of the green emission of the RE tridoped sample was due to a dual sensitization of Er3+ by Yb3+ and Tm3+ ions. The RE tridoped ZnO nanocrystals with the CIE coordinates close to (0.33, 0.33) are potentially suitable for the widely realistic application as the multicolor fluorescent labels, due to a fact that they could be cheaply and easily obtained and excited cost effectively.

  18. Magnetic, dielectric and microwave absorption properties of rare earth doped Ni-Co and Ni-Co-Zn spinel ferrites

    Science.gov (United States)

    Stergiou, Charalampos

    2017-03-01

    In this article we analyze the electromagnetic properties of rare earth substituted Ni-Co and Ni-Co-Zn cubic ferrites in the microwave band, along with their performance as microwave absorbing materials. Ceramic samples with compositions Ni0.5Co0.5Fe2-xRxO4 and Ni0.25Co0.5Zn0.25Fe2-xRxO4 (R=Y and La, x=0, 0.02), fabricated with the solid state reaction method, were characterized with regard to the complex permeability μ*(f) and permittivity ε*(f) up to 20 GHz. The rare earth substitutions basically affect the microwave μ*(f) spectra and the dynamic magnetization mechanisms of domain wall motion and magnetization rotation. Key parameters for this effect are the reduced magnetocrystalline anisotropy and the created crystal inhomogeneities. Moreover, permittivity is increased with the Y and La content, due to the enhancement of the dielectric orientation polarization. Regarding the electromagnetic wave attenuation, the prepared ferrites exhibit narrowband return losses (RL) by virtue of the cancellation of multiple reflections, when their thickness equals an odd multiple of quarter-wavelength. Interestingly, the zero-reflection conditions are satisfied in the vicinity of the ferromagnetic resonance. As the rare earth doping shifts this mechanism to lower frequencies, loss peaks with RL>46 dB occur at 4.1 GHz and 5 GHz for Y and La-doped Ni-Co-Zn spinels, whereas peaks with RL>40 dB appear at 18 GHz and 19 GHz for Y and La-doped Ni-Co spinels, respectively. The presented experimental findings underline the potential of cubic ferrites with high Co concentration in the suppression of electromagnetic reflections well above the 1 GHz region.

  19. Comparison of various organic compounds destruction on rare earths doped Ti/Sb-SnO{sub 2} electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Yu-Hong [School of Environmental Science and Engineering, Huazhong University of Science and Technology, No. 1037 Luoyu Road, Hongshan District, Wuhan 430074 (China); State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Feng, Yu-Jie, E-mail: yujief@hit.edu.cn [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Liu, Junfeng; Ren, Nanqi [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Different REs doping has distinct effect on the Ti/Sb-SnO{sub 2} electrode performance. Black-Right-Pointing-Pointer Gd or Eu improves the performance of Ti/Sb-SnO{sub 2} on aromatic ring cleavage. Black-Right-Pointing-Pointer Catechol is more refractory to be degraded than benzoquinone and hydroquinone. Black-Right-Pointing-Pointer The molecular structure of organic compound influences its degradation rate. - Abstract: Ti/Sb-SnO{sub 2} and three kinds of rare earths (REs), namely Ce, Gd, and Eu doped Ti/Sb-SnO{sub 2} electrodes were prepared and tested for their capacity on electrocatalytic degradation of three kinds of basal aromatic compounds (benzoquinone, hydroquinone and catechol) and six kinds of aliphatic acids (maleic acid, fumaric acid, succinic acid, malonic acid, oxalic acid and acetic acid). The elimination of selected organics as well as their TOC removal with different doped Ti/Sb-SnO{sub 2} electrodes was described by first-order kinetics. Compared with Ti/Sb-SnO{sub 2}, the Gd and Eu doped electrodes show better performance on the degradation of most of the selected organics, while Ce doped electrode shows either closely or lower efficiency on the degradation of these selected organics. Besides electrode material, the molecular structure of organic compound has obvious effect on its degradation in the electrocatalytic process. Catechol is more resistant to the electrophilic attack by hydroxyl radicals than benzoquinone and hydroquinone. The compound with more complicate molecular structure or longer carbon chain is more difficult to be mineralized. The aliphatic acid with higher oxygen content or more double bonds is more readily to be oxidized in the electrocatalytic process.

  20. Synthesis and characterization of rare earth and transition metal doped BaMgF{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Janssens, S. [Industrial Research Limited, PO Box 31310, Lower Hutt 5040 (New Zealand); MacDiarmid Institute, SCPS, Victoria University of Wellington, PO Box 600, Wellington 6012 (New Zealand); Williams, G.V.M., E-mail: grant.williams@vuw.ac.nz [MacDiarmid Institute, SCPS, Victoria University of Wellington, PO Box 600, Wellington 6012 (New Zealand); Clarke, D. [Industrial Research Limited, PO Box 31310, Lower Hutt 5040 (New Zealand)

    2013-02-15

    BaMgF{sub 4} nanoparticles doped with Ce{sup 3+}, Eu{sup 3+}, Mn{sup 2+}, and Nd{sup 3+} have been successfully synthesized using a reverse microemulsion method. They form nanorods that aggregate into 'moustache' shaped clusters. All doped samples show photoluminescence where the Ce{sup 3+} and Eu{sup 3+} photoluminescence spectra are consistent with substitution onto different crystal sites, while only a single site was found for the Mn{sup 2+} doped sample. Mn{sup 2+} was successfully sensitized by Ce{sup 3+} in BaMgF{sub 4}:Mn{sup 2+}:Ce{sup 3+} nanoparticles. The Ce{sup 3+} PL lifetimes are strongly wavelength dependent, which could be due to different Ce{sup 3+} sites with different PL lifetimes as well as energy transfer between Ce{sup 3+} sites. Transparent thick polymer films containing nanoparticles have been made. The appearance of photoluminescence in rare earth and transition metal doped BaMgF{sub 4} nanoparticles and the ability to make transparent thick films means that the BaMgF{sub 4} nanoparticles have a range of potential applications that include optical amplification. - Highlights: Black-Right-Pointing-Pointer BaMgF{sub 4} nanorods synthesized using a reverse microemulsion method. Black-Right-Pointing-Pointer BaMgF{sub 4} nanorods successfully doped with luminescent ions. Black-Right-Pointing-Pointer Ce{sup 3+} and Eu{sup 3+} ions occupy two distinct crystal sites. Black-Right-Pointing-Pointer Efficient energy transfer from Ce{sup 3+} to Mn{sup 2+} is observed. Black-Right-Pointing-Pointer Transparent nanoparticle/PMMA polymer films were made.

  1. Effects of varying base glass composition on the optical properties of lead borate glasses doped with rare earth ions

    Science.gov (United States)

    Heidorn, William D.

    Rare Earth (RE) doped lead borate glasses are expected to exhibit a compositional dependence in their optical properties due to the changes induced by variations in the structure of the base glass with increasing lead oxide content. A series of lead borate glasses with the composition xPbO:(99.5 - x)B2O 3 (x = 29.5 to 69.5 in steps of 10 mol%) doped with 0.5 mol% Sm2O3, Er2O3, and Ho2O3 were prepared using the melt quench technique followed by 3 hours of annealing near the glass transition temperature. Optical absorption and fluorescence spectra of these RE doped lead borate glasses were analyzed using Judd-Ofelt theory. The compositional dependence of Judd-Ofelt intensity parameters, O t (t = 2, 4, 6), were determined and were then used to calculate the radiative transition probability of the excited states, the total radiative transition probability, branching ratios, and radiative lifetime of the glasses. From the fluorescence spectra the stimulated emission cross section, and Stark splitting of the excited states were calculated as a function of glass composition. A fourth set of samples with composition xPbO:(99 - x)B2O 3(x = 29 to 69 in steps of 10 mol%) co-doped with 0.5 mol% Er2 O3 and Ho2O3 were also prepared and the effects of co-doping on the absorption and fluorescence were analyzed. In all the glass systems studied, it was found that the optical properties are strongly influenced by structural changes arising from compositional variation. Er3+ transitions exhibit large stimulated cross section suggesting the possible utilization of these materials in laser applications. Keywords: Lead and bismuth borate glasses, fluorescence, optical absorption, Sm3+, Ho3+, Er3+ ions, Judd-Ofelt intensity parameters, stimulated emission cross section.

  2. New Mid-IR Lasers Based on Rare-Earth-Doped Sulfide and Chloride Materials

    Energy Technology Data Exchange (ETDEWEB)

    Nostrand, M

    2000-09-01

    Applications in remote-sensing and military countermeasures have driven a need for compact, solid-state mid-IR lasers. Due to multi-phonon quenching, non-traditional hosts are needed to extend current solid-state, room-temperature lasing capabilities beyond {approx} 4 {micro}m. Traditional oxide and fluoride hosts have effective phonon energies in the neighborhood of 1000 cm{sup -1} and 500 cm{sup -1}, respectively. These phonons can effectively quench radiation above 2 and 4 {micro}m, respectively. Materials with lower effective phonon energies such as sulfides and chlorides are the logical candidates for mid-IR (4-10 {micro}m) operation. In this report, laser action is demonstrated in two such hosts, CaGa{sub 2}S{sub 4} and KPb{sub 2}Cl{sub 5}. The CaGa{sub 2}S{sub 4}:Dy{sup 3+} laser operating at 4.3 {micro}m represents the first sulfide laser operating beyond 2 {micro}m. The KPb{sub 2}Cl{sub 5}:Dy{sup 3+} laser operating at 2.4 {micro}m represents the first operation of a chloride-host laser in ambient conditions. Laser action is also reported for CaGa{sub 2}S{sub 4}:Dy{sup 3+} at 2.4 {micro}m, CaGa{sub 2}S{sub 4}:Dy{sup 3+} at 1.4 {micro}m, and KPb{sub 2}Cl{sub 5}:Nd{sup 3+} at 1.06 {micro}m. Both host materials have been fully characterized, including lifetimes, absorption and emission cross sections, radiative branching ratios, and radiative quantum efficiencies. Radiative branching ratios and radiative quantum efficiencies have been determined both by the Judd-Ofelt method (which is based on absorption measurements), and by a novel method described herein which is based on emission measurements. Modeling has been performed to predict laser performance, and a new method to determine emission cross section from slope efficiency and threshold data is developed. With the introduction and laser demonstration of rare-earth-doped CaGa{sub 2}S{sub 4} and KPb{sub 2}Cl{sub 5}, direct generation of mid-IR laser radiation in a solid-state host has been demonstrated. In

  3. Earth's crust model of the South-Okhotsk Basin by wide-angle OBS data

    Science.gov (United States)

    Kashubin, Sergey N.; Petrov, Oleg V.; Rybalka, Alexander V.; Milshtein, Evgenia D.; Shokalsky, Sergey P.; Verba, Mark L.; Petrov, Evgeniy O.

    2017-07-01

    Deep seismic studies of the Sea of Okhotsk region started in late 1950s. Since that time, wide-angle reflection and refraction data on more than two dozen profiles were acquired. Only five of those profiles either crossed or entered the deep-water area of the South-Okhotsk Basin (also known as the Kuril Basin or the South-Okhotsk Deep-Water Trough). Only P-waves were used to develop velocity-interface models in all the early research. Thus, all seismic and geodynamic models of the Okhotsk region were based only on the information on compressional waves. Nevertheless, the use of Vp/Vs ratio in addition to P-wave velocity allows discriminating felsic and mafic crustal layers with similar Vp values. In 2007 the Russian seismic service company Sevmorgeo acquired multi-component data with ocean bottom seismometers (OBS) along the 1700-km-long north-south 2-DV-M Profile. Only P-wave information was used previously to develop models for the entire profile. In this study, a multi-wave processing, analysis, and interpretation of the OBS data are presented for the 550-km-long southern segment of this Profile that crosses the deep-water South-Okhotsk Basin. Within this segment 50 seismometers were deployed with nominal OBS station spacing of 10-12 km. Shot point spacing was 250 m. Not only primary P-waves and S-waves but also multiples and P-S, S-P converted waves were analyzed in this study to constrain velocity-interface models by means of travel time forward modeling. In offshore deep seismic studies, thick water layer hinders an estimation of velocities in the sedimentary cover and in the upper consolidated crust. Primarily, this is due to the fact that refracted waves propagating in low-velocity solid upper layers interfere with high-amplitude direct water wave. However, in multi-component measurements with ocean bottom seismometers, it is possible to use converted and multiple waves for velocity estimations in these layers. Consequently, one can obtain P- and S

  4. Study of structure and magnetic properties of rare earth doped BiFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, Pittala; Srinath, S., E-mail: srinath@uohyd.ac.in

    2014-09-01

    RE{sub x}Bi{sub 1−x}FeO{sub 3} (RE=La, Gd and Ho) samples were synthesized by a solid state reaction method and investigated for structure and magnetic properties. XRD shows that La and Ho dopings at A-site effectively reduce the secondary phase formation. A structural phase transition is observed to orthorhombic phase with all RE elements above certain concentration limit. La doping results in the observation of huge coercivity of 10 kOe and Ho doping results in high magnetic moment among all the RE elements. Gd and Ho doped samples show a pinching in the M–H loops with minimum H{sub C}.

  5. Spectroscopic and Neutron Detection Properties of Rare Earth and Titanium Doped LiAlO2 Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dickens, Peter T.; Marcial, Jose; McCloy, John S.; McDonald, Benjamin S.; Lynn, Kelvin G.

    2017-10-02

    In this study, LiAlO2 crystals doped with rare-earth elements and Ti were produced by the CZ method and spectroscopic and neutron detection properties were investigated. Photoluminescence revealed no clear luminescent activation of LiAlO2 by the rare-earth dopants though some interesting luminescence was observed from secondary phases within the crystal. Gamma-ray pulse height spectra collected using a 137Cs source exhibited only a Compton edge for the crystals. Neutron modeling using Monte Carlo N-Particle Transport Code revealed most neutrons used in the detection setup are thermalized, and while using natural lithium in the crystal growth, which contains 7.6 % 6Li, a 10 mm Ø by 10 mm sample of LiAlO2 has a 70.7 % intrinsic thermal neutron capture efficiency. Furthermore, the pulse height spectra collected using a 241Am-Be neutron source demonstrated a distinct neutron peak.

  6. The MCVD synthesis and characterization of water tolerant fiber optic waveguides based on alkaline earth-doped silicas

    Science.gov (United States)

    Farley, Kevin F.

    Optical fibers that transmit throughout the entire telecommunications spectrum (1.2--1.7 mum) are presently manufactured by the removal of hydrogen or OH from the host preform glass. Hydrogen-oxygen torches are utilized in the conventional preform manufacturing process, but result in the formation of hydroxyls in germanium-doped silica fiber. The hydroxyl species generate unacceptably high losses for long haul telecommunications systems. This thesis has explored an alternative strategy for reducing OH-related absorption in silica-based glasses. Alkaline earth modifiers have been introduced via the modified chemical vapor deposition (MCVD) process to successfully damp out and dramatically reduce the extrinsic attenuation associated with both water and hydrogen. Specifically, alkaline earth ions were introduced into alumino-silicate glasses to form MgO-Al2O3-SiO2, CaO-Al 2O3-SiO2, and SrO-Al2O3-SiO 2 compositions. The utilization of halide precursors based on the vapor delivery of rare earths was incorporated into the existing MCVD set-up to fabricate these optical preforms. Both the bulk preforms and fibers drawn from them were characterized to determine relevant optical properties, including the attenuation, index profiles and extinction coefficients arising from OH in each host. The data indicate that modification of the silica glass structure through the additions of modifying ions can significantly reduce OH related absorption. For example, the doping of alkaline earth ions decreased the extinction coefficient measured at the 1.39 mum) OH overtone, to values reinforced by a series of experiments documenting their resistance to hydrogen induced losses.

  7. Thermoelectric properties of rare earth-doped -type Bi2Se0.3Te2.7 nanocomposites

    Indian Academy of Sciences (India)

    Fang Wu; Hongzhang Song; Jianfeng Jia; Xing Hu

    2014-08-01

    -Type R0.2Bi1.8Se0.3Te2.7 (R = Ce, Y and Sm) nanopowders were synthesized by hydrothermal method and the thermoelectric properties of the bulk samples made by hot-pressing these nanopowders were investigated. The Ce, Y and Sm doping have significant effects on the morphologies of the synthesized nanopowders. The thermoelectric property results show that Ce, Y and Sm doping not only help to decrease the electrical resistivity, but also help to reduce the thermal conductivity. Among rare earth elements–doped samples, it seems that the Y0.2Bi1.8Se0.3Te2.7 bulk has a suitable microstructure, which scatters phonons effectively but does not scatter electronic carriers as much. As a result, the ZT values of Y0.2Bi1.8Se0.3Te2.7 can reach 1.21 at 413 K, which is higher than those of Bi2Se0.3Te2.7 ingots made by zone-melting method.

  8. Electrodeposition and characterization of CaF{sub 2} and rare earth doped CaF{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hui; Liu Run, E-mail: runliu@zju.edu.cn; Chen Keli; Shi Xiaofang; Xu Zhude

    2011-07-29

    Calcium fluoride (CaF{sub 2}) and the rare earth doped CaF{sub 2} films have been electrodeposited on indium tin oxide (ITO) electrode through electrochemical generation of acid in aqueous solutions near room temperature. For CaF{sub 2} film electrodeposition, the local pH at ITO surface is lowered by the electrochemical oxidation of ascorbate anion, and then the Ca-ethylene diamine tetraacetic acid disodium complexes which are close to the ITO electrode are decomposed to release free Ca{sup 2+} to react with F{sup -}to form CaF{sub 2} deposit onto ITO. In the same way, RE-doped CaF{sub 2} films have been electrodeposited onto ITO electrode. The morphology of films studied by scanning electron microscopy revealed that they are agglomerated and dense. The films showed a little [111] preferred orientation by X-ray diffraction. It was also proved that doped RE ions were distributed homogeneously in the film by energy dispersive spectroscopy mapping. The optical properties of the electrodeposited CaF{sub 2}, CaF{sub 2}:Eu and CaF{sub 2}:Tb films were studied by photoluminescence, and all films exhibit intense emission peaks.

  9. Luminescence properties of barium--gadolinium-titanate ceramics doped with rare-earth ions (Eu3+ and Tb3+).

    Science.gov (United States)

    Hemasundara Raju, S; Muni Sudhakar, B; Sudhakar Reddy, B; Dhoble, S J; Thyagarajan, K; Nageswara Raju, C

    2014-11-01

    Barium-gadolinium-titanate (BaGd2 Ti4 O12) powder ceramics doped with rare-earth ions (Eu(3+) and Tb(3+)) were synthesized by a solid-state reaction method. From the X-ray diffraction spectrum, it was observed that Eu(3+) and Tb(3+):BaGd2 Ti4 O12 powder ceramics are crystallized in the form of an orthorhombic structure. Scanning electron microscopy image shows that the particles are agglomerated and the particle size is about 200 nm. Eu(3+) - and Tb(3+) -doped BaGd2 Ti4 O12 powder ceramics were examined by energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, photoluminescence and thermoluminescence (TL) spectra. Emission spectra of Eu(3+)-doped BaGd2 Ti4 O12 powder ceramics showed bright red emission at 613 nm ((5)D0 →(7)F2) with an excitation wavelength λ(exci)  = 408 nm ((7)F0 → (5)D3) and Tb(3+):BaGd2 Ti4 O12 ceramic powder has shown green emission at 534 nm ((5)D4 → (7)F5) with an excitation wavelength λ(exci)  = 331 nm (((7)F6 → (5)D1). TL spectra show that Eu(3+) and Tb(3+) ions affect TL sensitivity.

  10. Optimization of rare-earth-doped amplifiers for space mission through a hardening-by-system strategy

    Science.gov (United States)

    Ladaci, Ayoub; Girard, Sylvain; Mescia, Luciano; Robin, Thierry; Laurent, Arnaud; Cadier, Benoit; Boutillier, Mathieu; Ouerdane, Youcef; Boukenter, Aziz

    2017-02-01

    Rare-earth doped optical fibers (REDF, Er or Er/Yb-doped) are a key component in optical laser sources (REDFS) and amplifiers (REDFA). The high performances of these fiber-based systems made them as promising solution part of gyroscopes, telecommunication systems… However, REDFs are very sensitive to space radiations, so their degradation limits their integration in long term space missions. To overcome this issue, several studies were carried out and some innovations at the component level were proposed by our group such as the Cerium co-doping or the hydrogen loading of the REDF. More recently we initiated an original coupled simulation/experiment approach to improve the REDFA performances under irradiation by acting at the system level and not only at the component itself. This procedure optimizes the amplifier properties (gain, noise figure) under irradiation through simulation. The optimization of the system is ensured using a PSO (Particle Swarm optimization) algorithm. Using some experimental inputs, such as the Radiation Induced Attenuation (RIA) measurements and the spectroscopic features of the fiber, we demonstrate its efficiency to reproduce the amplifier degradation when exposed to radiations in various experimental configurations. This was done by comparing the obtained simulation results to those of dedicated experiments performed on various REDFA architectures. Our results reveal a good agreement between simulations and experimental data (with design in order to get the best performances during the space mission and not on-ground only.

  11. Influence of rare-earth metal doping on the catalytic performance of CuO-CeO2 for the preferential oxidation of CO in excess hydrogen

    Institute of Scientific and Technical Information of China (English)

    Zhigang Liu; Renxian Zhou; Xiaoming Zheng

    2008-01-01

    Doping of different rare-earth metals(Pr,Nd,Y and La)had an evident influence on the catalytic performance of CuO-CeO2 for the preferential oxidation(PROX)Of CO in excess hydrogen.As for Pr,the doping enhanced the catalytic activity of CuO-CeO2 for PROX.For example,the CO conversion over the above catalyst for PROX was higher than 99%at 120℃.Especially.the doping of Pr widened the temperature window by 20℃ over CuO-CeO2 with 99%CO conversion.For Nd,Y and La,the doping depressed the catalytic activity of CuO-CeO2 for PROX.However,the doping of transition metals markedly improved the selectivity of CuO-CeO2 for PROX.

  12. Composition-driven structural phase transitions in rare-earth-doped BiFeO3 ceramics: a review.

    Science.gov (United States)

    Arnold, Donna C

    2015-01-01

    Bismuth ferrite suffers from high leakage currents and the presence of a complex incommensurate spin cycloidal magnetic ordering, which has limited its commercial viability and has led researchers to investigate the functionality of doped BiFeO3 ceramics. In particular, the substitution of rare earths onto the Bi(3+) site of the perovskite lattice have been shown to lead to improved functional properties, including lower leakage currents and the suppression of the magnetic spin cycloid. There is particular interest in materials with compositions close to structural morphotropic phase boundaries, because these may lead to materials with enhanced electronic and magnetic properties analogous to the highly relevant PbZrO3- PbTiO3 solid solution. However, many contradictory crystal structures and physical behaviors are reported within the literature. To understand the structure-property relationships in these materials, it is vital that we first unravel the complex structural phase diagrams. We report here a comprehensive review of structural phase transitions in rare-earth-doped bismuth ferrite ceramics across the entire lanthanide series. We attempt to rationalize the literature in terms of the perovskite tool kit and propose an updated phase diagram based on an interpretation of the literature.

  13. GeS2-In2S3-CsI Chalcogenide Glasses Doped with Rare Earth Ions for Near- and Mid-IR Luminescence.

    Science.gov (United States)

    Li, Legang; Bian, Junyi; Jiao, Qing; Liu, Zijun; Dai, Shixun; Lin, Changgui

    2016-11-21

    Chalcogenide glass has been considered as a promising host for the potential laser gain and amplifier media operating in near- and mid-IR spectral region. In this work, the IR luminescence spectra of rare earth ions (Tm(3+), Er(3+), and Dy(3+)) doped 65GeS2-25In2S3-10CsI chalcogenide glasses were measured under the excitation of an 808 nm laser diode. To the best of our knowledge, it firstly provides the luminescence spectra of a full near- and mid-IR spectral range from 1 to 4 μm in rare earth ions doped chalcogenide glasses. The results of absorption spectra, luminescence spectra, and fluorescence decay curves were obtained in these samples with singly-, co- and triply-doping behaviors of Tm(3+), Er(3+), and Dy(3+) ions. In order to search possible efficient IR emissions, the luminescence behavior was investigated specifically with the variation of doping behaviors and dopant ions, especially in the samples co- and triply-doped active ions. The results suggest that favorable near- and mid-IR luminescence of rare earth ions can be further modified in chalcogenide glasses through an elaborated design of doping behavior and optically active ions.

  14. GeS2–In2S3–CsI Chalcogenide Glasses Doped with Rare Earth Ions for Near- and Mid-IR Luminescence

    Science.gov (United States)

    Li, Legang; Bian, Junyi; Jiao, Qing; Liu, Zijun; Dai, Shixun; Lin, Changgui

    2016-11-01

    Chalcogenide glass has been considered as a promising host for the potential laser gain and amplifier media operating in near- and mid-IR spectral region. In this work, the IR luminescence spectra of rare earth ions (Tm3+, Er3+, and Dy3+) doped 65GeS2–25In2S3–10CsI chalcogenide glasses were measured under the excitation of an 808 nm laser diode. To the best of our knowledge, it firstly provides the luminescence spectra of a full near- and mid-IR spectral range from 1 to 4 μm in rare earth ions doped chalcogenide glasses. The results of absorption spectra, luminescence spectra, and fluorescence decay curves were obtained in these samples with singly-, co- and triply-doping behaviors of Tm3+, Er3+, and Dy3+ ions. In order to search possible efficient IR emissions, the luminescence behavior was investigated specifically with the variation of doping behaviors and dopant ions, especially in the samples co- and triply-doped active ions. The results suggest that favorable near- and mid-IR luminescence of rare earth ions can be further modified in chalcogenide glasses through an elaborated design of doping behavior and optically active ions.

  15. The influence of different alkaline earth oxides on the structural and optical properties of undoped, Ce-doped, Sm-doped, and Sm/Ce co-doped lithium alumino-phosphate glasses

    Science.gov (United States)

    Othman, H. A.; Arzumanyan, G. M.; Möncke, D.

    2016-12-01

    Undoped, singly Sm doped, Ce doped, and Sm/Ce co-doped lithium alumino-phosphate glasses with different alkaline earth modifiers were prepared by melt quenching. The structure of the prepared glasses was investigated by FT-IR and Raman, as well as by optical spectroscopy. The effect of the optical basicity of the host glass matrix on the added active dopants was studied, as was the effect doping had on the phosphate structural units. The optical edge shifts toward higher wavelengths with an increase in the optical basicity due to the increased polarizability of the glass matrix, but also with increasing CeO2 concentration as a result of Ce3+/Ce4+ inter valence charge transfer (IV-CT) absorption. The optical band gap for direct and indirect allowed transitions was calculated for the undoped glasses. The glass sample containing Mg2+ modifier ions is found to have the highest value (4.16 eV) for the optical band gap while Ba2+ has the lowest value (3.61 eV). The change in the optical band gap arises from the structural changes and the overall polarizability (optical basicity). Refractive index, molar refractivity Rm and molar polarizability αm values increase with increasing optical basicity of the glasses. The characteristic absorption peaks of Sm3+ were also investigated. For Sm/Ce co-doped glasses, especially at high concentration of CeO2, the absorption of Ce3+ hinders the high energy absorption of Sm3+ and this effect becomes more obvious with increasing optical basicity.

  16. Optical spectroscopy of rare earth-doped oxyfluoro-tellurite glasses to probe local environment

    Indian Academy of Sciences (India)

    GAJANAN V HONNAVAR; K P RAMESH

    2017-09-01

    TeO$_2$-based glasses with a general formula 65TeO$_2$−5BaF$_2$−30ZnF$_2$ (TBZ) (in mol%) were prepared by usual melt quenching technique. Three mol% of europium (Eu) or erbium (Er) were added to the prepared glass at the expense of TeO$_2$. Raman, photoluminescence (PL), UV–visible absorption studies were carried out on the glass samples. Raman spectra of the undoped and doped glasses were analysed using the peak shift and the intensity variation along with fullwidth at half-maximum (FWHM). It was found that Eu-doped TBZ glass has a greater tendency towards depolymerizing theglass matrix by influencing the conversion of TeO$_4$ to TeO$_3$ units compared to Er-doped and undoped glasses. PL spectraof the glass samples show emission due to different possible transitions. Position of the peak of the de-convoluted spectrashows the position of the particular Stark component and the FWHM is a measure of the inhomogeneous broadening. TheUV–visible absorption spectra are used to calculate the optical density and to determine the band edge of the glass samplesby fitting to the Mott equation. It is seen that Eu-doped TBZ glass has a lesser bandgap than that of Er-doped glass.

  17. In-volume waveguides by fs-laser direct writing in rare-earth-doped fluoride glass and phosphate glass

    Science.gov (United States)

    Esser, D.; Wortmann, D.; Gottmann, J.

    2009-02-01

    Refractive index modifications are fabricated in the volume of rare-earth-doped glass materials namely Er- and Pr-doped ZBLAN (a fluoride glass consisting of ZrF4, BaF2, LaF3, AlF3, NaF), an Er-doped nano-crystalline glass-ceramic and Yb- and Er-doped phosphate glass IOG. Femtosecond laser radiation (τ=500fs, λ=1045nm, f=0.1-5MHz) from an Ybfiber laser is focused with a microscope objective in the volume of the glass materials and scanned below the surface with different scan velocities and pulse energies. Non-linear absorption processes like multiphoton- and avalanche absorption lead to localized density changes and the formation of color centers. The refractive index change is localized to the focal volume of the laser radiation and therefore, a precise control of the modified volume is possible. The width of the written structures is analyzed by transmission light microscopy and additionally with the quantitative phase microscopy (QPm) software to determine the refractive index distribution perpendicular to a waveguide. Structures larger than 50μm in width are generated at high repetition rates due to heat accumulation effects. In addition, the fabricated waveguides are investigated by far-field measurements of the guided light to determine their numerical apertures. Using interference microscopy the refractive index distribution of waveguide cross-sections in phosphate glass IOG is determined. Several regions with an alternating refractive index change are observed whose size depend on the applied pulse energies and scan velocities.

  18. Personal, Informal and Relatable: Engaging Wide Audiences in Climate Science with Nasa's Earth Right Now Blog

    Science.gov (United States)

    Tenenbaum, L. F.; Shaftel, H.; Jackson, R.

    2014-12-01

    There is no such thing as a non-scientist, but there are some who have yet to acknowledge their inner science spark. Aiming to ignite and fan the flame of curiosity, promote dialogue and attempt to make climate science personal and relevant to everyday life, NASA's Global Climate Change website http://climate.nasa.gov/ and Earth Right Now campaign http://www.nasa.gov/content/earth-right-now/ partnered together this year to launch the Earth Right Now blog http://climate.nasa.gov/blog. It quickly became one of the most popular blogs in all of NASA social media, receiving thousands of likes per week, and frequent comments as well as thoughtful and respectful discussions about climate change. Social media platforms such as blogs have become popular vehicles for engaging large swaths of the public in new exciting ways. NASA's Earth Right Now blog has become a powerful platform for engaging both scientists and the science-curious in constructive, fruitful conversations about the complex topic of climate science. We continue to interact and have ongoing dialogue with our readers by making the scientific content both accessible and engaging for diverse populations.

  19. Nanocrystalline semiconductor doped rare earth oxide for the photocatalytic degradation studies on Acid Blue 113: A di-azo compound under UV slurry photoreactor.

    Science.gov (United States)

    Suganya Josephine, G A; Mary Nisha, U; Meenakshi, G; Sivasamy, A

    2015-11-01

    Preventive measures for the control of environmental pollution and its remediation has received much interest in recent years due to the world-wide increase in the contamination of water bodies. Contributions of these harmful effluents are caused by the leather processing, pharmaceutical, cosmetic, textile, agricultural and other chemical industries. Nowadays, advanced oxidation processes considered to be better option for the complete destruction of organic contaminants in water and wastewater. Acid Blue 113 is a most widely used di-azo compound in leather, textile, dying and food industry as a color rending compound. In the present study, we have reported the photo catalytic degradation of Acid Blue 113 using a nanocrystalline semiconductor doped rare earth oxide as a photo catalyst under UV light irradiation. The photocatalyst was prepared by a simple precipitation technique and were characterized by XRD, FT-IR, UV-DRS and FE-SEM analysis. The experimental results proved that the prepared photo catalyst was nanocrystalline and highly active in the UV region. The UV-DRS results showed the band gap energy was 3.15eV for the prepared photo catalyst. The photodegradation efficiency was analyzed by various experimental parameters such as pH, catalyst dosage, variation of substrate concentration and effect of electrolyte addition. The photo degradation process followed a pseudo first order kinetics and was continuously monitored by UV-visible spectrophotometer. The experimental results proved the efficacy of the nanocrystalline zinc oxide doped dysprosium oxide which are highly active under UV light irradiations. It is also suggested that the prepared material would find wider applications in environmental remediation technologies to remove the carcinogenic and toxic moieties present in the industrial effluents.

  20. Rare-earth doped transparent ceramics for spectral filtering and quantum information processing

    OpenAIRE

    2015-01-01

    International audience; Homogeneous linewidths below 10 kHz are reported for the first time in high-quality Eu3+ doped Y 2O3 transparent ceramics. This result is obtained on the 7F0→5D0 transition in Eu3+ doped Y 2O3 ceramics and corresponds to an improvement of nearly one order of magnitude compared to previously reported values in transparent ceramics. Furthermore, we observed spectral hole lifetimes of ∼15 min that are long enough to enable efficient optical pumping of the nuclear hyperfin...

  1. Strong broad green UV-excited photoluminescence in rare earth (RE = Ce, Eu, Dy, Er, Yb) doped barium zirconate

    Energy Technology Data Exchange (ETDEWEB)

    Borja-Urby, R. [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A. C., Leon, Gto. 37150 (Mexico); Diaz-Torres, L.A., E-mail: ditlacio@cio.mx [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A. C., Leon, Gto. 37150 (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro, Qro. 76000 (Mexico); Angeles-Chavez, C. [Instituto Mexicano del Petroleo, Ciudad de Mexico, D. F. 07730 (Mexico); Meza, O. [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A. C., Leon, Gto. 37150 (Mexico)

    2011-10-25

    Highlights: > Trivalent rare earth (RE) substitution on Zr{sup 4+} sites in BaZrO{sub 3} lead to band gap narrowing. > RE substitution lead to enhanced blue-green intrinsic emission of nanocrystalline BaZrO{sub 3} > Blue-green hue of BaZrO3:RE depends on RE dopant and excitation UV wavelength > BaZrO3: Dy{sup 3+} PL chromatic coordinates correspond to pure white color coordinates of CIE 1931 model - Abstract: The wet synthesis hydrothermal method at 100 deg. C was used to elaborate barium zirconate (BaZrO{sub 3}) unpurified with 0.5 mol% of different rare earth ions (RE = Yb, Er, Dy, Eu, Ce). Morphological, structural and UV-photoluminescence properties depend on the substituted rare earth ionic radii. While the crystalline structure of RE doped BaZrO{sub 3} remains as a cubic perovskite for all substituted RE ions, its band gap changes between 4.65 and 4.93 eV. Under 267 nm excitation the intrinsic green photoluminescence of the as synthesized BaZrO{sub 3}: RE samples is considerably improved by the substitution on RE ions. For 1000 deg. C annealed samples, under 267 nm, the photoluminescence is dominated by the intrinsic BZO emission. It is interesting to notice that Dy{sup 3+}, Er{sup 3+} and Yb{sup 3+} doped samples present whitish emissions that might be useful for white light generation under 267 nm excitation. CIE color coordinates are reported for all samples.

  2. All-fiber widely tunable mode-locked thulium-doped laser using a curvature multimode interference filter

    Science.gov (United States)

    Li, N.; Liu, M. Y.; Gao, X. J.; Zhang, L.; Jia, Z. X.; Feng, Y.; Ohishi, Y.; Qin, G. S.; Qin, W. P.

    2016-07-01

    We demonstrated a widely tunable mode-locked thulium doped fiber laser (TDFL) by using a homemade multimode interference filter (MMIF). The MMIF had a structure of single mode fiber (SMF)—multimode fiber (MMF)—SMF and three main transmission peaks at 1901.2, 1957.2 and 2043.2 nm. By mechanically bending the MMIF, the three main transmission peaks were tuned in the range of 1860-2024 nm due to multimode interference effect. By inserting the MMIF into a passively mode-locked TDFL cavity pumped by a 1570 nm fiber laser, a tunable mode-locked TDFL with a tuning range of 1919.6-2014.9 nm was achieved by adjusting the MMIF. To the best of our knowledge, such a tunable range is the largest among all-fiber tunable mode-locked TDFLs.

  3. Wide-field polarimetric analysis of photoinduced birefringence in azo-dye-doped thin films: irradiance and time dependence

    Science.gov (United States)

    Marino, I.-G.; Razzetti, C.; Lottici, P. P.

    2007-03-01

    We have investigated by wide field polariscopy the behaviour of photoinduced birefringence (PIB) in sol-gel hybrid disperse red 1 (DR1) doped films. This technique allows the mapping of the local values of a bell-shaped pump beam irradiance and those of the corresponding photoinduced birefringence. By means of a point-to-point correlation of these maps, we have tracked the dependence of PIB, simultaneously and continuously, on exposure times and pump irradiances. We have then applied some of the available theoretical models, representing birefringence as an analytical function of irradiance and time, to interpolate the experimental PIB data. As compared to the usual PIB measurements, which neglect the spatial distribution of the pump irradiance, our results provide a more detailed and reliable empirical basis on which models of the orientational mechanisms of the photoisomerizable molecules can be developed.

  4. Optical spectroscopy of rare-earth ions doped KY(WO4)2 thin films

    NARCIS (Netherlands)

    García-Revilla, S.; Valiente, R.; Romanyuk, Y.E.; Utke, I.; Pollnau, Markus

    2004-01-01

    KY(WO4)2 thin films doped with Dy3+, Tb3+, Yb3+, were grown onto KY(WO4)2 substrates using liquid-phase epitaxy. Spectroscopic investigations of the grown layers were performed. Obtained results were compared with spectra given for bulk crystals. Upconversion experiments after direct Yb3+ excitation

  5. Rare earth doped nanoparticles in organic and inorganic host materials for application in integrated optics

    NARCIS (Netherlands)

    Dekker, R.; Hilderink, L.T.H.; Diemeer, Mart; Stouwdam, J.W.; Sudarsan, V; van Veggel, F.C.J.M.; Driessen, A.; Worhoff, Kerstin; Misra, D; Masscher, P.; Sundaram, K.; Yen, W.M.; Capobianco, J.

    2006-01-01

    The preparation and the optical properties of lanthanum fluoride (LaF3) nanoparticles doped with erbium and neodymium will be discussed. Organic and inorganic materials in the form of polymers and sol-gels were used to serve as the hosts for the inorganic nanoparticles, respectively. The organic

  6. Temperature dependent coercivity and magnetization of light rare-earth Nd doped permalloy thin films

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Chen [Physics Department, Southeast University, Nanjing 211189 (China); Fu, Yu [Physics Department, Southeast University, Nanjing 211189 (China); Institut Nanosciences et Cryogénie, CEA, 38054 Grenoble (France); Zhang, Dong [Physics Department, Southeast University, Nanjing 211189 (China); School of Physics Science and Information Engineering, Liaocheng University, Liaocheng 252059 (China); Yuan, Shijun [Physics Department, Southeast University, Nanjing 211189 (China); Zhai, Ya, E-mail: yazhai@seu.edu.cn [Physics Department, Southeast University, Nanjing 211189 (China); Dong, Shuai [Physics Department, Southeast University, Nanjing 211189 (China); Zhai, Hongru [National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-01-15

    The temperature dependence of the magnetic properties of Ni{sub 80}Fe{sub 20} thin films with dilute Nd dopants has been studied. The effect of Nd dopants on the hysteresis loops of Nd-doped Ni{sub 80}Fe{sub 20} thin films is small at room temperature but large at low temperature. The measurements show an interesting temperature dependence of the coercivity with different concentrations of Nd impurities, which might be related to the film structure. The temperature dependence of the saturation magnetization for Nd-doped Ni{sub 80}Fe{sub 20} thin films is fitted by a theoretical expression of spin-wave excitation plus Stoner-type-like contribution, in which the spin-wave excitation plays a main role at low temperature. The spin-wave stiffness constant D evaluated from the fitting shows a strong doping concentration dependence. - Highlights: • The abnormal coercivity behavior of Nd-doped Permalloy thin films is studied. • The mechanism of temperature dependence of coercivity is discussed. • The effect of Nd dopants on temperature dependence of Ms is studied. • Spin-wave excitations and Stoner-type excitations are discussed quantitatively.

  7. Optical spectroscopy of rare-earth ions doped KY(WO4)2 thin films

    NARCIS (Netherlands)

    García-Revilla, S.; Valiente, R.; Romanyuk, Y.E.; Utke, I.; Pollnau, M.

    2004-01-01

    KY(WO4)2 thin films doped with Dy3+, Tb3+, Yb3+, were grown onto KY(WO4)2 substrates using liquid-phase epitaxy. Spectroscopic investigations of the grown layers were performed. Obtained results were compared with spectra given for bulk crystals. Upconversion experiments after direct Yb3+ excitation

  8. ZnO varistors with high voltage gradient and low leakage current by doping rare-earth oxide

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The surge arrester of 1000 kV gas-insulated substation (GIS) needs ZnO varistor with high voltage gradient to effectively improve the potential distribution along ZnO varistor column inside the metal-oxide surge arresters. In this paper, the elec-trical and structural parameters of ZnO varistors are changed by doping with some rare-earth oxides, and the mechanism which leads these changes is discussed. When rare-earth oxide additives are added into ZnO varistors, the growing speed is slowed down due to the stabilization of the new spinel phases formed in the grain-boundary by rare-earth oxide additives, then the size of ZnO grains is smaller, and the voltage gradient of varistor increases obviously. By adding suitable amount of oxides of metal Co and Mn, the leakage current can be effectively decreased and the nonlinearity coefficient increased. The novel ZnO varistor samples sintered with the optimal additives have a voltage gradient of 492 V/mm, and the nonlinearity coefficient of 76, but their leakage currents are only 1 μA.

  9. Small Airborne Hyperspectral Wide Area Imager for Disaster Response and Earth Science Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed hyperspectral plus LWIR system will deliver high signal to noise performance, a wide spectral range, nominally 365 nm to 1.7 um, a single long wave IR...

  10. Rare earth doped silicate-oxyfluoride glass ceramics incorporating LaF3 nano-crystals for UV-LED color conversion

    Science.gov (United States)

    Bae, Suk-Rok; Choi, Yong Gyu; Im, Won Bin; Lee, Ki Seok; Chung, Woon Jin

    2013-09-01

    Rare earth doped oxyfluoride glass ceramics with LaF3 nano-crystals formed inside were fabricated for color converter of UV-LED. Among various rare earth ions, Dy3+ and Eu3+ showed practically utilizable visible emissions under UV-LED excitation of 365 nm. The visible emission has been improved by the formation of LaF3 brought by heat treatment. X-ray diffraction and transmission electron microscopy along with its energy dispersive spectra confirmed the formation of LaF3 nano-crystals. Compositional dependence and the effects of heat treatment conditions on the visible emissions have been investigated. The CIE chromaticity coordinates of the glasses were also examined for Dy3+ singly doped and co-doped samples. The effect of LaF3 nano-crystals and co-dopants on the visible emission properties of Dy3+ was discussed.

  11. The effect of surface OH-population on the photocatalytic activity of rare earth-doped P25-TiO2 in methylene blue degradation

    NARCIS (Netherlands)

    Du, P.; Bueno-López, A.; Verbaas, M.; Almeida, A.R.; Makkee, M.; Moulijn, J.A.; Mul, Guido

    2008-01-01

    Commercial TiO2 (P25, from Degussa) was modified with variable amounts of La, Ce, Y, Pr, Sm (generally rare earth (RE)), by thermal treatment of physical mixtures of TiO2 and the nitrates of the various RE. Doping of P25 with RE, combined with calcination at 600 or 800 °C, yields materials with

  12. Rare-earth doped transparent ceramics for spectral filtering and quantum information processing

    Directory of Open Access Journals (Sweden)

    Nathalie Kunkel

    2015-09-01

    Full Text Available Homogeneous linewidths below 10 kHz are reported for the first time in high-quality Eu3+ doped Y 2O3 transparent ceramics. This result is obtained on the 7F0→5D0 transition in Eu3+ doped Y 2O3 ceramics and corresponds to an improvement of nearly one order of magnitude compared to previously reported values in transparent ceramics. Furthermore, we observed spectral hole lifetimes of ∼15 min that are long enough to enable efficient optical pumping of the nuclear hyperfine levels. Additionally, different Eu3+ concentrations (up to 1.0% were studied, resulting in an increase of up to a factor of three in the peak absorption coefficient. These results suggest that transparent ceramics can be useful in applications where narrow and deep spectral holes can be burned into highly absorbing lines, such as quantum information processing and spectral filtering.

  13. Up-conversion in rare earth-doped silica hollow spheres

    Science.gov (United States)

    Fortes, Luís M.; Li, Yigang; Réfega, Ricardo; Clara Gonçalves, M.

    2012-06-01

    In the present work, Er/Yb co-doped silica hollow spheres are prepared in a two-step process. In a first step, polystyrene-core is silica coated in situ by a modified Stöber sol-gel method and in the second one, the sacrificial polystyrene core is thermally removed. The core-shell and the hollow spheres are characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectroscopy (PL). PL measurements show up-conversion phenomena upon excitation at 975 nm, through the emission of blue (˜490 nm), green (˜523 nm and ˜536 nm) and red (˜655 nm) light. The up-conversion phenomena are discussed and modelled. The developed model explains the up-conversion phenomena of Er/Yb co-doped silica hollow spheres, with special agreement for high Yb/Er ratio.

  14. Rare-earth doped transparent ceramics for spectral filtering and quantum information processing

    Science.gov (United States)

    Kunkel, Nathalie; Ferrier, Alban; Thiel, Charles W.; Ramírez, Mariola O.; Bausá, Luisa E.; Cone, Rufus L.; Ikesue, Akio; Goldner, Philippe

    2015-09-01

    Homogeneous linewidths below 10 kHz are reported for the first time in high-quality Eu3+ doped Y 2O3 transparent ceramics. This result is obtained on the 7F0→5D0 transition in Eu3+ doped Y 2O3 ceramics and corresponds to an improvement of nearly one order of magnitude compared to previously reported values in transparent ceramics. Furthermore, we observed spectral hole lifetimes of ˜15 min that are long enough to enable efficient optical pumping of the nuclear hyperfine levels. Additionally, different Eu3+ concentrations (up to 1.0%) were studied, resulting in an increase of up to a factor of three in the peak absorption coefficient. These results suggest that transparent ceramics can be useful in applications where narrow and deep spectral holes can be burned into highly absorbing lines, such as quantum information processing and spectral filtering.

  15. Study on the preparation and electrochemical performance of rare earth doped nano-Ni(OH)2

    Institute of Scientific and Technical Information of China (English)

    YE Xiancong; ZHU Yanjuan; WU Shanggai; ZHANG Zhongju; ZHOU Zhuojun; ZHENG Hanzhong; LIN Xiaoran

    2011-01-01

    Multiphase nano-Ni(OH)2 doped with Y or La was prepared by supersonic co-precipitation method.The crystal morphology,structure and particle size were characterized by transmission electron microscopy (TEM),X-ray diffraction (XRD) and particle size distribution (PSD).The electrochemical performance of samples was investigated by electrochemical workstation and battery tested system.The results indicated that micro-morphology and grain size were changed with the changing of supersonic power,pH values and doping elements.The morphology of Y doped sample was from the flake-like to the needle-like with the increase of supersonic power; Particles were from quasispherical particles into needle-like with the increase of pH values; As the supersonic power increased,the proportion of α-Ni(OH)2 increased initially and then decreased.pH value was very important to the formation of crystalline phase.Lower pH value was beneficial to the formation of α-Ni(OH)2.However,the pH values had a slight effect on the reaction reversibility.Complex electrodes were prepared by mixing 8 wt.% nickel hydroxides with commercial micro-size spherical nickel.The discharge capacity of electrodes increased initially and then decreased with the increase of supersonic power.When the supersonic power was 60 W and the pH value was 9,the sample had the largest discharge capacity (358 mAh/g) at 0.5 C rate,which was 122.7 and 76 mAh/g higher than the spherical nickel electrode and La doped sample electrode,respectively.

  16. Enhanced thermoelectric properties of earth-abundant Cu{sub 2}SnS{sub 3} via In doping effect

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Qing; Sun, Wei; Li, Zhiliang; Li, Jing-Feng, E-mail: jingfeng@mail.tsinghua.edu.cn

    2016-07-05

    Ternary copper tin sulfide (Cu–Sn–S) compounds have been investigated for decades as promising candidates of earth-abundant thin film solar cell absorbers. Cu{sub 2}SnS{sub 3} is a representative member of this material system, and is highly expected to be a potential thermoelectric material by the first-principles calculations. In this work, Cu{sub 2}SnS{sub 3} bulk materials were synthesized by the mechanical alloying (MA) combined with spark plasma sintering (SPS), and their crystal structures, electronic transport properties and enhanced thermoelectric performance were systematically investigated. We found that pristine Cu{sub 2}SnS{sub 3} is a p-type thermoelectric material with a relatively high thermopower up to 300 μV/K and low thermal conductivity below 1.0 W/m K above 700 K. It revealed that In doping is an effective means to improve the electrical transport properties, which leads to a figure of merit (ZT) of Cu{sub 2}Sn{sub 0.9}In{sub 0.1}S{sub 3} close to 0.6 at the relatively low temperature (773 K). - Highlights: • Ternary compounds Cu{sub 2}SnS{sub 3} is a promising candidate for thermoelectric materials. • Pristine and In-doped Cu{sub 2}SnS{sub 3} were synthesized by the MA process combining with SPS. • Relatively high thermopower and low thermal conductivity were obtained in Cu{sub 2}SnS{sub 3}. • In-doping further improved electrical conductivity and reduced thermal conductivity. • ZT value of Cu{sub 2}Sn0{sub 0}.{sub 9}In{sub 0.1}S{sub 3} reached 0.56 at 773 K, over twice higher than Cu{sub 2}SnS{sub 3}.

  17. Physical and optical absorption studies of Fe{sup 3+} - ions doped lithium borate glasses containing certain alkaline earths

    Energy Technology Data Exchange (ETDEWEB)

    Bhogi, Ashok [VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad, Telangana (India); Kumar, R. Vijaya [School of Physics, University of Hyderabad, Hyderabad, Telangana (India); Kistaiah, P., E-mail: pkistaiah@yahoo.com [Department of Physics, Osmania University, Hyderabad, Telangana (India)

    2016-05-23

    Iron ion doped lithium borate glasses with the composition 15RO-25Li{sub 2}O-59B{sub 2}O{sub 3}-1Fe{sub 2}O{sub 3} (where R= Ca, Sr and Ba) have been prepared by the conventional melt quenching technique and characterized to investigate the physical and optical properties using XRD, density, molar volume and UV-Visible spectroscopy. The optical absorption spectra exhibit a band at around 460 nm which is assigned to {sup 6}A{sub 1g}(S) → 4E{sub g} (G) of Fe{sup 3+} ions with distorted octahedral symmetry. From ultraviolet absorption edges, the optical band gap and Urbach energies have been evaluated. The effect of alkaline earths on these properties is discussed.

  18. Physical and optical absorption studies of Fe3+ - ions doped lithium borate glasses containing certain alkaline earths

    Science.gov (United States)

    Bhogi, Ashok; Kumar, R. Vijaya; Kistaiah, P.

    2016-05-01

    Iron ion doped lithium borate glasses with the composition 15RO-25Li2O-59B2O3-1Fe2O3 (where R= Ca, Sr and Ba) have been prepared by the conventional melt quenching technique and characterized to investigate the physical and optical properties using XRD, density, molar volume and UV-Visible spectroscopy. The optical absorption spectra exhibit a band at around 460 nm which is assigned to 6A1g(S) → 4Eg (G) of Fe3+ ions with distorted octahedral symmetry. From ultraviolet absorption edges, the optical band gap and Urbach energies have been evaluated. The effect of alkaline earths on these properties is discussed.

  19. Direct laser writing of near-IR step-index buried channel waveguides in rare earth doped YAG.

    Science.gov (United States)

    Rodenas, A; Benayas, A; Macdonald, J R; Zhang, J; Tang, D Y; Jaque, D; Kar, A K

    2011-09-01

    A new (to our knowledge) ultrashort laser pulse irradiation regime that allows us to directly modify and increase the refractive index of rare earth doped YAG polycrystalline ceramics has been identified. Single-mode buried channel waveguides in both Ho:YAG and Er:YAG ceramics at the near-IR wavelengths of 1.55 μm and 1.95 μm are demonstrated by fabricating positive square step-index cores. Minimum propagation losses of 1.5 dB cm(-1) at a 1.51 μm wavelength have been preliminarily obtained. Confocal microluminescence mapping reveals that the increased refractive index regions retain the near-IR spectral properties of Er3+ ions in the YAG crystalline matrix.

  20. Role of vacancies, light elements and rare-earth metals doping in CeO2.

    Science.gov (United States)

    Shi, H; Hussain, T; Ahuja, R; Kang, T W; Luo, W

    2016-08-24

    The magnetic properties and electronic structures of pure, doped and defective cerium oxide (CeO2) have been studied theoretically by means of ab initio calculations based on the density function theory (DFT) with the hybrid HF/DFT technique named PBE0. Carbon (C), nitrogen (N), phosphorus (P), sulphur (S), lanthanum (La) and praseodymium (Pr) doped in CeO2 and CeO2 containing oxygen vacancies (Ov) were considered. Our spin-polarized calculations show that C, N, Pr dopants and Ov defects magnetize the non-magnetic CeO2 in different degree. The optical band gap related to photocatalysis for pure CeO2, corresponding to the ultraviolet region, is reduced obviously by C, N, S, Pr impurities and oxygen vacancies, shifting to the visible region and even further to the infrared range. Especially, N-, S- and Pr-doped CeO2 could be used to photocatalytic water splitting for hydrogen production. As the concentration of Ov increasing up to 5%, the CeO2 exhibits a half-metallic properties.

  1. Role of vacancies, light elements and rare-earth metals doping in CeO2

    Science.gov (United States)

    Shi, H.; Hussain, T.; Ahuja, R.; Kang, T. W.; Luo, W.

    2016-01-01

    The magnetic properties and electronic structures of pure, doped and defective cerium oxide (CeO2) have been studied theoretically by means of ab initio calculations based on the density function theory (DFT) with the hybrid HF/DFT technique named PBE0. Carbon (C), nitrogen (N), phosphorus (P), sulphur (S), lanthanum (La) and praseodymium (Pr) doped in CeO2 and CeO2 containing oxygen vacancies (Ov) were considered. Our spin-polarized calculations show that C, N, Pr dopants and Ov defects magnetize the non-magnetic CeO2 in different degree. The optical band gap related to photocatalysis for pure CeO2, corresponding to the ultraviolet region, is reduced obviously by C, N, S, Pr impurities and oxygen vacancies, shifting to the visible region and even further to the infrared range. Especially, N-, S- and Pr-doped CeO2 could be used to photocatalytic water splitting for hydrogen production. As the concentration of Ov increasing up to 5%, the CeO2 exhibits a half-metallic properties. PMID:27554285

  2. Effects of rare earth ionic doping on microstructures and electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Renzhong [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an 710048 (China); Department of Technology and Physics, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Chen, Zhenping, E-mail: xrzbotao@163.com [Department of Technology and Physics, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Dai, Haiyang; Liu, Dewei; Li, Tao [Department of Technology and Physics, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Zhao, Gaoyang, E-mail: zhaogy@xaut.edu.cn [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an 710048 (China)

    2015-06-15

    Graphical abstract: The dielectric constant decreases monotonically with reduced RE doping ion radius and is more frequency independent compared with that of pure CCTO sample. - Highlights: • The mean grain sizes decrease monotonically with reduced RE doping ionic radius. • Doping gives rise to the monotonic decrease of ϵ{sub r} with reduced RE ionic radius. • The nonlinear coefficient and breakdown field increase with RE ionic doping. • α of all the samples is associated with the potential barrier width rather than Φ{sub b}. - Abstract: Ca{sub 1–x}R{sub x}Cu{sub 3}Ti{sub 4}O{sub 12}(R = La, Nd, Eu, Gd, Er; x = 0 and 0.005) ceramics were prepared by the conventional solid-state method. The influences of rare earth (RE) ion doping on the microstructure, dielectric and electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) ceramics were investigated systematically. Single-phase formation is confirmed by XRD analyses. The mean grain size decreases monotonically with reduced RE ion radius. The EDS results reveal that RE ionic doping reduces Cu-rich phase segregation at the grain boundaries (GBs). Doping gives rise to the monotonic decrease of dielectric constant with reduced RE ionic radius but significantly improves stability with frequency. The lower dielectric loss of doped samples is obtained due to the increase of GB resistance. In addition, the nonlinear coefficient and breakdown field increase with RE ionic doping. Both the fine grains and the enhancement of potential barrier at GBs are responsible for the improvement of the nonlinear current–voltage properties in doped CCTO samples.

  3. Room temperature ferromagnetism with large magnetic moment at low field in rare-earth-doped BiFeO₃ thin films.

    Science.gov (United States)

    Kim, Tae-Young; Hong, Nguyen Hoa; Sugawara, T; Raghavender, A T; Kurisu, M

    2013-05-22

    Thin films of rare earth (RE)-doped BiFeO3 (where RE=Sm, Ho, Pr and Nd) were grown on LaAlO3 substrates by using the pulsed laser deposition technique. All the films show a single phase of rhombohedral structure with space group R3c. The saturated magnetization in the Ho- and Sm-doped films is much larger than the values reported in the literature, and is observed at quite a low field of 0.2 T. For Ho and Sm doping, the magnetization increases as the film becomes thinner, suggesting that the observed magnetism is mostly due to a surface effect. In the case of Nd doping, even though the thin film has a large magnetic moment, the mechanism seems to be different.

  4. Optical properties and size distribution of the nanocolloids made of rare-earth ion-doped NaYF4

    Science.gov (United States)

    Patel, Darayas N.; Lewis, Ashley; Wright, Donald M.; Lewis, Danielle; Valentine, Rueben; Valentine, Maucus; Wessley, Dennis; Sarkisov, Sergey; Darwish, Abdalla M.

    2015-03-01

    In this paper we investigate optical properties and size distribution of the nano-colloids made of trivalent rare-earth ion doped fluorides: holmium and ytterbium, thulium and ytterbium, and erbium and ytterbium co-doped NaYF4. These materials were synthesized by using simple co-precipitation synthetic method. The initially prepared micro-crystals had very weak or no visible upconversion fluorescence signals when being pumped with a 980-nm laser. The fluorescence intensity significantly increased after the crystals were annealed at a temperature of 400°C - 600°C undergoing the transition from cubic alpha to hexagonal beta phase of the fluoride host. Nano-colloids of the crystals were made in polar solvents using the laser ablation and ball milling methods. Size analyses of the prepared nano-colloids were conducted using a dynamic light scatterometer and atomic force microscope. The nano-colloids were filled in holey PCFs and their fluorescent properties were studied and the feasibility of new a type of fiber amplifier/laser was evaluated.

  5. First-principles prediction of the magnetism of 4f rare-earth-metal-doped wurtzite zinc oxide

    Institute of Scientific and Technical Information of China (English)

    AG El Hachimi; H Zaari; A Benyoussef; M El Yadari; A El Kenz

    2014-01-01

    Electronic structure and magnetic properties of wurtzite ZnO semiconductor doped with rare earth (RE=La, Ce, Pr, Pm, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb) atoms were studied using spin-polarized density functional theory based on the full-potential linear augmented plane wave (FP-LAPW) method as implemented in the Wien2k code. In this approach the generalized gradient ap-proximation (GGA) was used for the exchange-correlation (XC) potential. Our results showed that the substitution of RE ions in ZnO induced spins polarized localized states in the band gap. Moreover, the studied DMSs compounds retained half metallicity at dopant concentration x=0.625%for most of the studied elements, with 100%spin polarization at the Fermi level (EF). The total magnetic moments of these compounds existed due to RE 4f states present at EF, while small induced magnetic moments existed on other non-magnetic atoms as well. Finally, the energy difference between far and near configurations was investigated. It was found that the room temperature ferromagnetism was possible for RE-doped ZnO at near configuration. Since the RE-RE separation was long enough (far configuration) for magnetic coupling, the system became paramagnetic or antiferromagnetic ground state.

  6. Luminescence investigations of rare earth doped lead-free borate glasses modified by MO (M = Ca, Sr, Ba)

    Energy Technology Data Exchange (ETDEWEB)

    Janek, Joanna, E-mail: janek.joanna@gmail.com; Sołtys, Marta; Żur, Lidia; Pietrasik, Ewa; Pisarska, Joanna; Pisarski, Wojciech A.

    2016-09-01

    Series of lead-free borate glasses with different oxide modifiers and lanthanide ions were prepared. The effect of oxide modifiers MO (M = Ca, Sr, Ba) on spectroscopic properties of trivalent Ln{sup 3+} (Ln = Eu, Er, Pr) were systematically investigated. Especially, the luminescence spectra of Ln{sup 3+}-doped lead-free borate glasses are presented and discussed in relation to the impact of selective components (CaO, SrO and BaO). Several spectroscopic parameters, such as the fluorescence intensity ratio R/O (Eu{sup 3+}) and measured luminescence lifetimes for the {sup 5}D{sub 0} (Eu{sup 3+}), {sup 4}I{sub 13/2} (Er{sup 3+}) and {sup 1}D{sub 2} (Pr{sup 3+}) excited states of lanthanide ions were analyzed in details. The research proved that spectroscopic properties of trivalent Ln{sup 3+} depend significantly on kind of presence oxide modifiers MO (M = Ca, Sr, Ba) in glass host matrices. - Highlights: • Luminescence of Ln{sup 3+}-doped borate glasses was presented and discussed. • Effect of glass modifiers on spectroscopic properties of rare earths was studied. • Measured luminescence lifetimes of Ln{sup 3+} (Ln = Eu, Er, Pr) were analyzed. • Luminescence intensity ratios R/O (Eu{sup 3+}) were determined.

  7. Abnormal Dielectric Response in an Optical Range Based on Electronic Transition in Rare-Earth-Ion-Doped Crystals

    Institute of Scientific and Technical Information of China (English)

    FU Xiao-Jian; XU Yuan-Da; ZHOU Ji

    2012-01-01

    A new scheme to realize an abnormal dielectric response at optical wavelength is developed on the basis of twolevel electronic transition of rare-earth ion doped crystals.Based on the semi-classical theory and the Judd-Ofelt theory,the electric dipole transition under a weak field is analyzed,and a general expression for the frequencydependent dielectric constant is obtained.As an example,the permittivity of (Erx Y1-x)3Al5O12 is calculated numerically in consideration of the transition between 4I15/2and 4F9/2.An optimized dielectric property with a negative real part and low absorption is achieved.This proposes a new mechanism for building extraordinary electromagnetic media at optical frequencies by using a quantum process.%A new scheme to realize an abnormal dielectric response at optical wavelength is developed on the basis of two-level electronic transition of rare-earth ion doped crystals. Based on the semi-classical theory and the Judd-Ofelt theory, the electric dipole transition under a weak Reid is analyzed, and a general expression for the frequency-dependent dielectric constant is obtained. As an example, the permittivity of (ErxY1-x)3A15O12 is calculated numerically in consideration of the transition between 4I15/2 and 4F9/2. An optimized dielectric property with a negative real part and low absorption is achieved. This proposes a new mechanism for building extraordinary electromagnetic media at optical frequencies by using a quantum process.

  8. Analysis of multilayered, nitrogen-doped aluminum oxide and hafnium oxide dielectric films for wide-temperature capacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    DeCerbo, J.N., E-mail: jennifer.decerbo@us.af.mil [United States Air Force Research Laboratory, Aerospace Systems Directorate, 2130 Eighth St., WPAFB, OH 45433 (United States); Bray, K.R. [UES, Inc., 4401 Dayton Xenia Rd., Beavercreek, OH 45432 (United States); Merrett, J.N. [United States Air Force Research Laboratory, Aerospace Systems Directorate, 2130 Eighth St., WPAFB, OH 45433 (United States)

    2015-09-01

    Capacitors with stable dielectric properties across a wide temperature range are a vital component in many power conditioning applications. High breakdown strength and low loss are also important for many applications. In this study, the dielectric properties of multilayer nitrogen-doped aluminum oxide and hafnium oxide films were characterized, comparing their properties to single layer films. The films were found to be stable from − 50 to 200 °C and from 20 Hz to 1 MHz. An order of magnitude decrease in leakage current was observed for the bilayer films. Breakdown strength for the multilayer films increased up to 75%. This concurs with the hypothesis that the addition of dielectric interfaces provides area to trap and dissipate runaway charge moving through the dielectric, thus lowering leakage current and increasing the breakdown strength. - Highlights: • Multilayer dielectric had stable dielectric properties for a wide temperature range. • Leakage current decreased an order of magnitude with layered dielectrics. • Breakdown strength increase of up to 75% was observed with layered dielectrics.

  9. The role of deep acceptor centers in the oxidation of acceptor-doped wide-band-gap perovskites ABO3

    Science.gov (United States)

    Putilov, L. P.; Tsidilkovski, V. I.

    2017-03-01

    The impact of deep acceptor centers on defect thermodynamics and oxidation of wide-band-gap acceptor-doped perovskites without mixed-valence cations is studied. These deep centers are formed by the acceptor-bound small hole polarons whose stabilization energy can be high enough (significantly higher than the hole-acceptor Coulomb interaction energy). It is shown that the oxidation enthalpy ΔHox of oxide is determined by the energy εA of acceptor-bound states along with the formation energy EV of oxygen vacancies. The oxidation reaction is demonstrated to be either endothermic or exothermic, and the regions of εA and EV values corresponding to the positive or negative ΔHox are determined. The contribution of acceptor-bound holes to the defect thermodynamics strongly depends on the acceptor states depth εA: it becomes negligible at εA less than a certain value (at which the acceptor levels are still deep). With increasing εA, the concentration of acceptor-bound small hole polarons can reach the values comparable to the dopant content. The results are illustrated with the acceptor-doped BaZrO3 as an example. It is shown that the experimental data on the bulk hole conductivity of barium zirconate can be described both in the band transport model and in the model of hopping small polarons localized on oxygen ions away from the acceptor centers. Depending on the εA magnitude, the oxidation reaction can be either endothermic or exothermic for both mobility mechanisms.

  10. Phase transition characteristics and dielectric properties of rare-earth (La, Pr, Nd, Gd) doped Ba(Zr0.09Ti0.91)O-3 ceramics

    OpenAIRE

    2010-01-01

    A-site deficient rare-earth doped barium zirconate titanate (BZT) ceramics (Ba1−yLn2y/3)Zr0.09Ti0.91O3 (Ln = La, Pr, Nd, Gd) are obtained by a modified solid-state reaction method. Perovskite-like single-phase compounds were confirmed from X-ray diffraction data. Morphological analysis on sintered samples shows that the addition of rare-earth ions inhibits the growth of the grain and remarkably changes the grain morphology. The effect of rare-earth addition to BZT on phase transition and diel...

  11. High Power Widely Tunable Narrow Linewidth All-Solid-State Pulsed Titanium-Doped Sapphire Laser

    Institute of Scientific and Technical Information of China (English)

    DING Xin; LI Xue; SHENG Quan; SHI Chun-Peng; YIN Su-Jia; LI Bin; YU Xuan-Yi; WEN Wu-Qi; YAO Jian-Quan

    2011-01-01

    We report a widely tunable, narrow linewidth, pulsed Ti:sapphire laser pumped by an all-solid-state Q-switched intra-cavity frequency-doubled Nd:YAG laser. By using four dense Bint glass prisms as intra-cavity dispersive elements, the output wavelength can be continuously tuned over 675-970 nm and the spectral linewidth is shortened to 0.5nm. The maximum output power of 6.65 W at 780 nm is obtained under 23.4 Wpump power with repetition rate of 5.5 kHz; corresponding to an conversion efficiency of 28.4%. Due to the gain-switching characteristics of the Ti:sapphire laser, the output pulse duration is as short as 17.6ns.%@@ We report a widely tunable,narrow linewidth,pulsed Th:sapphire laser pumped by an all-solid-state Q-switched intra-cavity frequency-doubled Nd:YAG laser.By using four dense flint glass prisms as intra-cavity dispersive elements,the output wavelength can be continuously tuned over 675-970nm and the spectral linewidth is shortened to 0.5 nm.The maximum output power of 6.65 W at 780 run is obtained under 23.4 W pump power with repetition rate of 5.5 kHz,corresponding to an conversion efficiency of 28.4%.Due to the gain-switching characteristics of the Ti:sapphire laser,the output pulse duration is as short as 17.6ns.

  12. Wide wavelength-tuning of a double-clad Yb3+-doped fiber laser based on a fiber Bragg grating array

    NARCIS (Netherlands)

    Alvarez-Chavez, J.A.; Martinez-Rios, A.; Torres-Gomez, I.; Offerhaus, H.L.

    2007-01-01

    We report wide wavelength tuning in a double-clad ytterbium-doped fiber laser. The laser cavity consists of an array of broadband high-reflection fiber Bragg gratings and a bulk grating as output coupler and wavelength selection element. The proposed fiber laser configuration combines low intra-cavi

  13. Superposition-model analysis of rare-earth doped BaY2F8

    Science.gov (United States)

    Magnani, N.; Amoretti, G.; Baraldi, A.; Capelletti, R.

    The energy level schemes of four rare-earth dopants (Ce3+ , Nd3+ , Dy3+ , and Er3+) in BaY2 F-8 , as determined by optical absorption spectra, were fitted with a single-ion Hamiltonian and analysed within Newman's Superposition Model for the crystal field. A unified picture for the four dopants was obtained, by assuming a distortion of the F- ligand cage around the RE site; within the framework of the Superposition Model, this distortion is found to have a marked anisotropic behaviour for heavy rare earths, while it turns into an isotropic expansion of the nearest-neighbours polyhedron for light rare earths. It is also inferred that the substituting ion may occupy an off-center position with respect to the original Y3+ site in the crystal.

  14. Rare earth-doped materials with enhanced thermoelectric figure of merit

    Science.gov (United States)

    Venkatasubramanian, Rama; Cook, Bruce Allen; Levin, Evgenii M.; Harringa, Joel Lee

    2016-09-06

    A thermoelectric material and a thermoelectric converter using this material. The thermoelectric material has a first component including a semiconductor material and a second component including a rare earth material included in the first component to thereby increase a figure of merit of a composite of the semiconductor material and the rare earth material relative to a figure of merit of the semiconductor material. The thermoelectric converter has a p-type thermoelectric material and a n-type thermoelectric material. At least one of the p-type thermoelectric material and the n-type thermoelectric material includes a rare earth material in at least one of the p-type thermoelectric material or the n-type thermoelectric material.

  15. Advancing radiation balanced lasers (RBLs) in rare-earth (RE)-doped solids

    Energy Technology Data Exchange (ETDEWEB)

    Hehlen, Markus Peter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-21

    These slides cover the following topics: Mid-IR lasers in crystals using two-tone RBL (Single-dopant two-tone RBLs: Tm3+, Er3+, and Co-doped two-tone RBLs: (Yb3+, Nd3+) and (Ho3+, Tm3+); Advanced approaches to RBL crystals (Precursor purification, Micro-pulling-down crystal growth, and Bridgman crystal growth); Advanced approaches to RBL fibers (Materials for RBL glass fibers, Micro-structured fibers for RBL, and Fiber preform synthesis); and finally objectives.

  16. Spectroscopy and Device Performance of Rare Earth Doped III-Nitrides

    Science.gov (United States)

    2002-11-12

    Journal of Alloys and Compounds , 341, 62-66 (2002). D. S. Lee, J. Heikenfeld, M. Garter, A. J. Steckl, U. Hömmerich, J. T. Seo, A. Braud... Journal of Alloys and Compounds , 303- 304, 331-335 (2000). J. T. Seo, U. Hömmerich, J. D. MacKenzie, C. R. Abernathy, J.M. Zavada, “Near-Infrared...S. J. Pearton, R. G. Wilson, “Luminescence characteristics of Er-doped GaN semiconductor thin films”, Journal of Alloys and Compounds

  17. Rare Earth Elements-Doped LiCoO2 Cathode Material for Lithium-Ion Batteries

    Institute of Scientific and Technical Information of China (English)

    魏进平; 曹晓燕; 潘桂玲; 叶茂; 阎杰

    2003-01-01

    Some compounds of LiCo1-xRExO2 (RE=rare earth elements and x=0.01~0.03) were prepared by doping rare earth elements to LiCoO2 via solid state synthesis. The microstructure characteristics of the LiCo1-xRExO2 were investigated by XRD. It was found that the lattice parameters c are increased and the lattice volumes are enlarged compared to that of LiCoO2. Moreover, the performance of LiCo1-xRExO2 as the cathode material in lithium ion battery is improved, especially LiCo1-xYxO2 and LiCo1-xLaxO2. The initial charge/discharge capacities of LiCo0.99Y0.01O2 and LiCo0.99La0.01O2 are 174/154 (mAh*g-1) and 159/149 (mAh*g-1) respectively, while those for LiCoO2 working in the same way are only 139/131 (mAh*g-1).

  18. Rare-earth doped transparent ceramics for spectral filtering and quantum information processing

    Energy Technology Data Exchange (ETDEWEB)

    Kunkel, Nathalie, E-mail: nathalie.kunkel@chimie-paristech.fr; Goldner, Philippe, E-mail: philippe.goldner@chimie-paristech.fr [PSL Research University, Chimie ParisTech–CNRS, Institut de Recherche de Chimie Paris, 11 rue Pierre et Marie Curie, 75005 Paris (France); Ferrier, Alban [PSL Research University, Chimie ParisTech–CNRS, Institut de Recherche de Chimie Paris, 11 rue Pierre et Marie Curie, 75005 Paris (France); Sorbonnes Universités, UPMC Univ Paris 06, 75005 Paris (France); Thiel, Charles W.; Cone, Rufus L. [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States); Ramírez, Mariola O.; Bausá, Luisa E. [Departamento Física de Materiales and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Ikesue, Akio [World Laboratory, Mutsuno, Atsuta-ku, Nagoya 456-0023 (Japan)

    2015-09-01

    Homogeneous linewidths below 10 kHz are reported for the first time in high-quality Eu{sup 3+} doped Y {sub 2}O{sub 3} transparent ceramics. This result is obtained on the {sup 7}F{sub 0}→{sup 5}D{sub 0} transition in Eu{sup 3+} doped Y {sub 2}O{sub 3} ceramics and corresponds to an improvement of nearly one order of magnitude compared to previously reported values in transparent ceramics. Furthermore, we observed spectral hole lifetimes of ∼15 min that are long enough to enable efficient optical pumping of the nuclear hyperfine levels. Additionally, different Eu{sup 3+} concentrations (up to 1.0%) were studied, resulting in an increase of up to a factor of three in the peak absorption coefficient. These results suggest that transparent ceramics can be useful in applications where narrow and deep spectral holes can be burned into highly absorbing lines, such as quantum information processing and spectral filtering.

  19. Characterization of rare-earth doped Si 3 N4 /SiC micro/nanocomposites

    Directory of Open Access Journals (Sweden)

    Peter Tatarko

    2010-03-01

    Full Text Available Influence of various rare-earth oxide additives (La2O3, Nd2O3, Sm2O3, Y2O3, Yb2O3 and Lu2O3 on the mechanical properties of hot-pressed silicon nitride and silicon nitride/silicon carbide micro/nano-composites has been investigated. The bimodal character of microstructures was observed in all studied materials where elongated β-Si3N4 grains were embedded in the matrix of much finer Si3N4 grains. The fracture toughness values increased with decreasing ionic radius of rare-earth elements. The fracture toughness of composites was always lower than that of monoliths due to their finer Si3N4/SiC microstructures. Similarly, the hardness and bending strength values increased with decreasing ionic radius of rare-earth elements either in monoliths or composites. On the other hand, the positive influence of finer microstructure of the composites on strength was not observed due to the present defects in the form of SiC clusters and non-reacted carbon zones. Wear resistance at room temperature also increased with decreasing ionic radius of rare-earth element. Significantly improved creep resistance was observed in case either of composite materials or materials with smaller radius of RE3+.

  20. Effect of Al2O3 on the Structure and Photoluminescence Properties of Sol-gel Glass Doped with Rare Earth Organic Complex

    Institute of Scientific and Technical Information of China (English)

    肖静; 付桂军; 刘韩星; 欧阳世Xi

    2005-01-01

    Both silica glass materials singly doped with rare earth organic complex and co-doped with Al3+ were prepared by in situ sol-gel method respectively. XRD and SEM measurements were performed to verify the non-crystalline structure of the glass. The excitation spectra, emission spectra and IR spectra were measured to analyze the influence of the glass contents on the structure of the glass and the energy level of the doped Eu(IH) ions. The effect of Al3+ on the photoluminescence properties of rare earth organic complex in silica glass was investigated. The IR spectra indicated that the in situ synthesized europium complex molecule was confined to the micropores of the host and the vibration of the ligands was frozen. When Al2O3 was doped into the silica host gel, the rare earth ions in the silica network were wrapped up and dispersed by Al2O3, so the distribution of Eu(Ⅲ) complex in the host was morehomogeneous, and the luminescence intensity of 5D0-7F2 transition emission of the Eu3+ ions was improved. The results showed that an appropriate amount of Al3+ added to the gel glass improved the emission intensity of the complex in the silica glass, and when the content of Al2O3 reached 4 mol%, the maximum emission intensity could be obtained compared with that of other samples containing different Al2O3 contents.

  1. Efficient dual-wavelength excitation of Tb3+ emission in rare-earth doped KYF4 cubic nanocrystals dispersed in silica sol-gel matrix

    Science.gov (United States)

    del-Castillo, J.; Yanes, A. C.; Santana-Alonso, A.; Méndez-Ramos, J.

    2014-11-01

    Energy transfer from Ce3+ to Tb3+ ions under UV excitation, giving rise to visible emissions, is investigated in sol-gel derived transparent nano-glass-ceramics containing cubic KYF4 nanocrystals, for different doping concentrations of rare-earth ions. Moreover, visible emissions of Tb3+ are also obtained under near-infrared excitation through energy transfer from Yb3+ ions by means of cooperative up-conversion processes. Thus, Ce3+-Tb3+-Yb3+ doped nano-glass-ceramics can be activated in a dual-wavelength mode yielding efficient blue-green emissions of particular interest in photovoltaic silicon solar cells and white-light emitting diodes.

  2. Photoluminescence of rare-earth ion (Eu3+, Tm3+, and Er3+)-doped and co-doped ZnNb2O6 for solar cells

    Science.gov (United States)

    Gao, Sen-Pei; Qian, Yan-Nan; Wang, Biao

    2015-08-01

    Visible converted emissions produced at an excitation of 286 nm in ZnNb2O6 ceramics doped with rare-earth ions (RE = Eu3+, Tm3+, Er3+ or a combination of these ions) were investigated with the aim of increasing the photovoltaic efficiency of solar cells. The structure of RE:ZnNb2O6 ceramics was confirmed by x-ray diffraction patterns. The undoped ZnNb2O6 could emit a blue emission under 286-nm excitation, which is attributed to the self-trapped excitons’ recombination of the efficient luminescence centers of edge-shared NbO6 groups. Upon 286-nm excitation, Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 ceramics showed blue, green, and red emissions, which correspond to the transitions of 5D0 → 7FJ (J = 1-4) (Eu3+), 1G4 → 3H6 (Tm3+), and 2H11/2/4S3/2 → 4I15/2 (Er3+), respectively. The calculated CIE chromaticity coordinates of Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 are (0.50, 0.31), (0.14, 0.19), and (0.29, 0.56), respectively. RE ion-co-doped ZnNb2O6 showed a combination of characteristic emissions. The chromaticity coordinates of Eu/Tm:ZnNb2O6, Eu/Er:ZnNb2O6, and Tm/Er:ZnNb2O6 were calculated to be (0.29, 0.24), (0.45, 0.37), and (0.17, 0.25). Project supported by the National Natural Science Foundation of China (Grant Nos. 10572155 and 10732100) and the Research Fund for the Doctoral Program of Ministry of Education, China (Grant No. 20130171130003).

  3. The fabrication of porous N-doped carbon from widely available urea formaldehyde resin for carbon dioxide adsorption.

    Science.gov (United States)

    Liu, Zhen; Du, Zhenyu; Song, Hao; Wang, Chuangye; Subhan, Fazle; Xing, Wei; Yan, Zifeng

    2014-02-15

    N-doped carbon material constitutes abundant of micropores and basic nitrogen species that have potential implementation for CO2 capture. In this paper, porous carbon material with high nitrogen content was simply fabricated by carbonizing low cost and widely available urea formaldehyde resin, and then followed by KOH activation. CO2 capture experiment showed high adsorption capacity of 3.21 mmol g(-1) at 25 °C under 1 atm for UFCA-2-600. XRD, SEM, XPS and FT-IR analysis confirmed that a graphitic-like structure was retained even after high temperature carbonization and strong base activation. Textural property analysis revealed that narrow micropores, especially below 0.8 nm, were effective for CO2 adsorption by physical adsorption mechanism. Chemical evolved investigation revealed that graphitic-like embedded basic nitrogen groups are generated from bridged and terminal amines of urea formaldehyde resin from thermal carbonization and KOH activation treatment, which is responsible for the enrichment of CO2 capacity by chemical adsorption mechanism. The relationship between CO2 adsorption capacity and pore size or basic N species was also studied, which turned out that both of them played crucial role by physical and chemical adsorption mechanism, respectively.

  4. Rare earth-doped lead borate glasses and transparent glass-ceramics: structure-property relationship.

    Science.gov (United States)

    Pisarski, W A; Pisarska, J; Mączka, M; Lisiecki, R; Grobelny, Ł; Goryczka, T; Dominiak-Dzik, G; Ryba-Romanowski, W

    2011-08-15

    Correlation between structure and optical properties of rare earth ions in lead borate glasses and glass-ceramics was evidenced by X-ray-diffraction, Raman, FT-IR and luminescence spectroscopy. The rare earths were limited to Eu(3+) and Er(3+) ions. The observed BO(3)↔BO(4) conversion strongly depends on the relative PbO/B(2)O(3) ratios in glass composition, giving important contribution to the luminescence intensities associated to (5)D(0)-(7)F(2) and (5)D(0)-(7)F(1) transitions of Eu(3+). The near-infrared luminescence and up-conversion spectra for Er(3+) ions in lead borate glasses before and after heat treatment were measured. The more intense and narrowing luminescence lines suggest partial incorporation of Er(3+) ions into the orthorhombic PbF(2) crystalline phase, which was identified using X-ray diffraction analysis.

  5. Structure and properties of rare earth-doped lead borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, W.A. [University of Silesia, Institute of Materials Science, Bankowa 12, 40-007 Katowice (Poland)]. E-mail: wpisarsk@us.edu.pl; Goryczka, T. [University of Silesia, Institute of Materials Science, Bankowa 12, 40-007 Katowice (Poland); Wodecka-Dus, B. [University of Silesia, Department of Materials Science, Sniezna 2, 41-200 Sosnowiec (Poland); PIonska, M. [University of Silesia, Department of Materials Science, Sniezna 2, 41-200 Sosnowiec (Poland); Pisarska, J. [Silesian University of Technology, Department of Materials Science, Krasinskiego 8, 40-019 Katowice (Poland)

    2005-09-15

    Influence of rare earth oxide (Nd{sub 2}O{sub 3}, Er{sub 2}O{sub 3}) addition on structure and glass properties has been investigated in PbO-B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-WO{sub 3} system. With an increasing of rare earth concentration, intensity of OH band drastically decreases and IR transparency is slightly shifted to the longer wavelengths. The ErBO{sub 3} crystalline phase has been identified basing on X-ray diffraction analysis. In opposite to the neodymium oxide, the erbium oxide plays the role as glass-modifier and influences on BO{sub 3} {r_reversible} BO{sub 4} conversion, what was stated by infrared spectroscopy.

  6. Rare earth-doped lead borate glasses and transparent glass-ceramics: Structure-property relationship

    Science.gov (United States)

    Pisarski, W. A.; Pisarska, J.; Mączka, M.; Lisiecki, R.; Grobelny, Ł.; Goryczka, T.; Dominiak-Dzik, G.; Ryba-Romanowski, W.

    2011-08-01

    Correlation between structure and optical properties of rare earth ions in lead borate glasses and glass-ceramics was evidenced by X-ray-diffraction, Raman, FT-IR and luminescence spectroscopy. The rare earths were limited to Eu 3+ and Er 3+ ions. The observed BO 3 ↔ BO 4 conversion strongly depends on the relative PbO/B 2O 3 ratios in glass composition, giving important contribution to the luminescence intensities associated to 5D 0- 7F 2 and 5D 0- 7F 1 transitions of Eu 3+. The near-infrared luminescence and up-conversion spectra for Er 3+ ions in lead borate glasses before and after heat treatment were measured. The more intense and narrowing luminescence lines suggest partial incorporation of Er 3+ ions into the orthorhombic PbF 2 crystalline phase, which was identified using X-ray diffraction analysis.

  7. Earth

    CERN Document Server

    Carter, Jason

    2017-01-01

    This curriculum-based, easy-to-follow book teaches young readers about Earth as one of the eight planets in our solar system in astronomical terms. With accessible text, it provides the fundamental information any student needs to begin their studies in astronomy, such as how Earth spins and revolves around the Sun, why it's uniquely suitable for life, its physical features, atmosphere, biosphere, moon, its past, future, and more. To enhance the learning experience, many of the images come directly from NASA. This straightforward title offers the fundamental information any student needs to sp

  8. Defect-induced magnetism in undoped and Mn-doped wide band gapzinc oxide grown by aerosol spray pyrolysis

    CSIR Research Space (South Africa)

    Motaung, DE

    2014-08-01

    Full Text Available We present a systemic study on the structural, optical and magnetic properties of the un-doped and Mn doped ZnO thin films grown by aerosol spray pyrolysis at different deposition times. XRD profilinghas shown that the structures of the prepared...

  9. A mini-review on rare earth metal-doped TiO2 for photocatalytic remediation of wastewater.

    Science.gov (United States)

    Saqib, Najm Us; Adnan, Rohana; Shah, Irfan

    2016-08-01

    Titanium dioxide (TiO2) has been considered a useful material for the treatment of wastewater due to its non-toxic character, chemical stability and excellent electrical and optical properties which contribute in its wide range of applications, particularly in environmental remediation technology. However, the wide band gap of TiO2 photocatalyst (anatase phase, 3.20 eV) limits its photocatalytic activity to the ultraviolet region of light. Besides that, the electron-hole pair recombination has been found to reduce the efficiency of the photocatalyst. To overcome these problems, tailoring of TiO2 surface with rare earth metals to improve its surface, optical and photocatalytic properties has been investigated by many researchers. The surface modifications with rare earth metals proved to enhance the efficiency of TiO2 photocatalyts by way of reducing the band gap by shifting the working wavelength to the visible region and inhibiting the anatase-to-rutile phase transformations. This review paper summarises the attempts on modification of TiO2 using rare earth metals describing their effect on the photocatalytic activities of the modified TiO2 photocatalyst.

  10. Dispersive coupling between light and a rare-earth-ion-doped mechanical resonator

    Science.gov (United States)

    Mølmer, Klaus; Le Coq, Yann; Seidelin, Signe

    2016-11-01

    By spectrally hole burning an inhomogeneously broadened ensemble of ions while applying a controlled perturbation, one can obtain spectral holes that are functionalized for maximum sensitivity to different perturbations. We propose to use such hole-burned structures for the dispersive optical interaction with rare-earth-ion dopants whose frequencies are sensitive to crystal strain due to the bending motion of a crystal cantilever. A quantitative analysis shows that good optical sensitivity to the bending motion is obtained if a magnetic-field gradient is applied across the crystal during hole burning and that the resulting optomechanical coupling strength is sufficient for observing quantum features such as zero-point vibrations.

  11. Luminescence properties of solid solutions of borates doped with rare-earth ions

    Science.gov (United States)

    Levushkina, V. S.; Mikhailin, V. V.; Spassky, D. A.; Zadneprovski, B. I.; Tret'yakova, M. S.

    2014-11-01

    The structural and luminescence properties of LuxY1 - xBO3 solid solutions doped with Ce3+ or Eu+3 have been investigated. It has been found that the solid solutions crystallize in the vaterite phase with a lutetium concentration x spectra are characterized by intensive impurity emission under excitation with the synchrotron radiation in the X-ray and ultraviolet spectral ranges. It has been shown that, as the lutetium concentration x in the LuxY1 - xBO3: Ce3+ solid solutions increases, the emission intensity smoothly decreases, which is associated with a gradual shift of the Ce3+ 5 d(1) level toward the bottom of the conduction band, as well as with a decrease in the band gap. It has been established that, in the LuxY1 - xBO3: Eu3+ solid solutions with intermediate concentrations x, the efficiency of energy transfer to luminescence centers increases. This effect is explained by the limited spatial separation of electrons and holes in the solid solutions. It has been demonstrated that the calcite phase adversely affects the luminescence properties of the solid solutions.

  12. Thermoluminescence of double fluorides doped with rare earths; Termoluminiscencia de fluoruros dobles dopados con tierras raras

    Energy Technology Data Exchange (ETDEWEB)

    Azorin N, J.; Sanchez R, A. [UAM-I, 09340 Mexico D.F. (Mexico); Khaidukov, N.M. [Kurnakov Institute of General and Inorganic Chemistry, 119991 Moscow (Russian Federation)

    2004-07-01

    In this work the thermoluminescent characteristics of double fluorides K{sub 2}YF{sub 5}, K{sub 2}GdF{sub 5} and K{sub 2}LuF{sub 5} doped are presented with Tb{sup 3+}, studied in the interval of temperature from 30 to 400 C. The materials that presented better answer to the irradiation with particles beta and with ultraviolet light they were the K{sub 2}YF{sub 5}: Tb (1% at. Tb{sup 3+}) and the K{sub 2}LuF{sub 5}: Tb (1% at. Tb{sup 3+}); while the K{sub 2}YF{sub 5}: Tb to high concentrations (10% and 20% at. Tb{sup 3+}) and the K{sub 2}LuF{sub 5}: Tb (1% at. Tb{sup 3+}) and the K{sub 2}LuF{sub 5}: Tb (1% at. Tb{sup 3+}) they presented an acceptable answer in front of the gamma radiation. The intensity of the Tl answer induced in these materials is a decisive factor to continue studying its dosimetric characteristics, what allows to consider them as the base for the development of potential materials to use them in the dosimetry of beta particles, of the UV light of the gamma radiation using the thermoluminescence method. (Author)

  13. Blue and white upconversion emissions of rare-earth ions-doped oxyfluoride phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Pang Tao [Optoelectronic Technology Institute, Dalian Maritime University, Liaoning Dalian 116026 (China); Cao Wanghe, E-mail: whcao@online.ln.c [Optoelectronic Technology Institute, Dalian Maritime University, Liaoning Dalian 116026 (China); Xing Mingming; Feng Wei; Xu Shujing [Optoelectronic Technology Institute, Dalian Maritime University, Liaoning Dalian 116026 (China)

    2010-05-01

    A blue emitting upconversion phosphor based on Yb{sup 3+} and Tm{sup 3+} codoped oxyfluoride is reported. Under the excitation of a single 980 nm diode laser with the power density of 5.56 W/cm{sup 2}, the upconversion luminescence brightness can reaches to 13053 mcd/m{sup 2}, which is much stronger than that of commercial Y{sub 2}O{sub 2}S:Yb, Tm phosphors (8194 mcd/m{sup 2}). The research of upconversion mechanism indicates that cooperating sensitization dominates the emissions at 479 and 645 nm, while the emission at 454 nm results from the combination of cooperating sensitization and phonon-assisted energy transfer from Yb{sup 3+} to Tm{sup 3+}. Also, bright upconversion white light is obtained by tri-doping of Er{sup 3+}, Tm{sup 3+} and Yb{sup 3+}. Because the blue (main emission at 479 nm), green and red emissions are two-photon process, the white light is not sensitive to the pumping power.

  14. Raman and Luminescence Investigation of Rare Earth Doped Laser-Induced Crystals-in-Glass

    Science.gov (United States)

    Knorr, Brian; Stone, Adam; Jain, Himanshu; Dierolf, Volkmar

    2015-03-01

    Laser induced crystallization of glasses is a highly spatially selective process which has the potential to produce compact, integrated optics within a glass matrix. In LaBGeO5 low temperature Combined Excitation Emission Spectroscopy (CEES) revealed that erbium incorporates into both glass-ceramics and laser-induced crystals-in-glass in predominantly one type of environment (site). The energy levels of this site were quantified. The fluorescence characteristics of the erbium ions in any site in the laser-induced crystals were found to be only weakly influenced by the irradiation conditions during growth. On the other hand, a hidden parameter, potentially boron deficiency-related defects, resulted in a significant change in the incorporation behavior of the erbium ions. Scanning confocal Raman and fluorescence spectroscopy showed that the energies of the Raman modes are shifted and the erbium fluorescence intensity is inhomgeneously distributed, despite the host glass being homogeneously doped, across the cross-sections of laser-induced crystals in glass. These fluctuations within the Raman and fluorescence are spatially correlated, implying that different erbium sites form preferentially at different locations in the crystal cross-section.

  15. METALLIC PHASE AND INSULATING CHARACTER OF ALKALI-EARTH METAL DOPED C60

    Institute of Scientific and Technical Information of China (English)

    曹阳; 陈良进; 陈波; 冯建文; 陈文建

    1995-01-01

    The three dimensional EHMO crystal orbital calculations for crystalline Ba6 C60,Ca3 C60 and Ca5 C60 are reported.The ground state of partially doped Ca3 C60 is found to be insulating with an indrect energy gap of 0.5eV.In contrast,the Ca5 C60 forms a metallic conducting phase with a set of three half-filled bands crossing the Fermi level which is Found to locate close to a peak of the density of state. The character of crystal orbitals near the Fermilevel for both Ca3 C60 and Ca5 C60 is completely carbon-like.In both cases the Ca3 atoms are almost fully ionized and C60 molecules form a stable negative charge state with six to ten additional electrons.The conductivity of Ba6 C60 is resuted from the incomplete charge tranfer.The valance charge of every Ba ion is about 0.33.The total charge tranfer of six Ba atoms is almost the same as that of five Ca atoms.

  16. Synthesis, structural and optical properties of pure and rare-earth ion doped TiO{sub 2} nanowire arrays by a facile hydrothermal technique

    Energy Technology Data Exchange (ETDEWEB)

    Bandi, Vengala Rao; Raghavan, Chinnambedu Murugesan; Grandhe, Bhaskar kumar; Kim, Sang Su [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Jang, Kiwan, E-mail: kwjang@changwon.ac.kr [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Shin, Dong-Soo [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of); Yi, Soung-Soo [Department of Photonics, Silla University, Busan 617-736 (Korea, Republic of); Jeong, Jung-Hyun [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2013-11-29

    Single crystalline pure and rare-earth metal ions (Eu{sup 3+} and Ce{sup 3+}) doped TiO{sub 2} nanowire arrays were prepared on conductive fluorine doped indium tin oxide substrates by a facile hydrothermal method. Initially the conditions and parameters were optimized to prepare the high quality TiO{sub 2} nanowire arrays in the absence of organic additives. The average diameter and length of the TiO{sub 2} nanowire were found to be ∼ 30–50 nm and ∼ 0.5–1.5 μm, respectively. The formations of rutile phase structure in all the samples were confirmed by x-ray diffractometric analysis while the transmission electron microscopy confirms the single crystallinity and the maximum orientation of growth direction along [001] for the as-grown TiO{sub 2} nanowire. The optical properties of all the samples were analyzed using photoluminescence spectroscopy. The photocatalytic properties of the pure and doped TiO{sub 2} were investigated for the decomposition of organic toludine blue-O dye under ultraviolet irradiation. The result demonstrates that the Ce{sup 3+}: TiO{sub 2} decomposed almost 90% of the organic dye within 80 min. - Highlights: • Rare-earth (RE) doped TiO{sub 2} nanowire arrays were prepared by hydrothermal method • RE doping enhanced the growth rate of TiO{sub 2} nanowire arrays • The catalysts used to check their photocatalytic activity by toludine blue-O dye • RE doped TiO2 act as unprecedented photocatalyst for organic dye decomposition.

  17. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Enhanced Laser Cooling of Rare-Earth-Ion-Doped Glass Containing Nanometer-Sized Metallic Particles

    Science.gov (United States)

    Jia, You-Hua; Zhong, Biao; Yin, Jian-Ping

    2009-03-01

    The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb3+ -doped ZBLAN as example, the cooling power and heat-light converting efficiency are calculated. It is finally concluded that the absorption and the fluorescence are greatly enhanced in these composite materials, the cooling power is increased compared to the bulk material.

  18. Luminescent rare earth vanadate nanoparticles doped with Eu3+ and Bi3 for sensing and imaging applications

    Science.gov (United States)

    Escudero, Alberto; Carrillo-Carrión, Carolina; Zyuzin, Mikhail; Hartmann, Raimo; Ashraf, Sumaira; Parak, Wolfgang J.

    2016-03-01

    Nanoparticles (NPs) are attracting interest in nanomedicine due to their potential medical applications, ranging from optical biolabels and contrast agents for magnetic resonance imaging to carriers for drug and gene delivery for disease therapy.[1] Rare earth (RE) based nanophosphors exhibit important advantages compared with other available luminescent materials, such as quantum dots and nanostructures functionalized with organic dyes, due to their lower toxicities, photostabilities, high thermal and chemical stabilities, high luminescence quantum yields, and sharp emission bands.[2] Yttrium orthovanadate NPs doped with Eu3+ and Bi3+, functionalized with poly acryl acid (PAA), and excitable by near-ultraviolet light have been synthesized by homogeneous precipitation at 120 °C from solutions of rare earth precursors (yttrium acetylacetonate and europium nitrate), bismuth nitrate, sodium orthovanadate, and PAA, in an ethylene glycol/water mixture. Quasispheres with sizes from 93 to 51 nm were obtained. The as synthesized NPs were already functionalized with PAA. The NPs showed the typical red luminescence of Eu3+, which can be excited with near-UV light through an energy transfer from the vanadate anion. The presence of Bi3+ shifts the maximum of the broad excitation band from 280 nm to 342 nm. This excitation path is much more efficient than the direct excitation of the Eu3+ electronic levels, and results in a much higher luminescence. The NPs can be uptaken by HeLa cells, and are eventually located in the lysosomes after being internalized. Finally, the functionalization with PAA provides -COOH anchors for adding functional ligands of biomedical interest that can be used for sensing applications.

  19. Structural, electrical and magnetic properties of rare-earth and transition element co-doped bismuth ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Vivek, E-mail: vermavivek.neel@gmail.com

    2015-08-25

    Highlights: • Sm-doping increases the symmetry and decreases the second phase formation. • Ferromagnetic, ferroelectric and dielectric properties enhanced with doping. • M–H loops represents weak ferromagnetic (FM) behavior. • A modification in dielectric constant is observed due to doping of Mn, Co and Cr. • Saturation polarization (P{sub s}), remnant polarization (P{sub r}) and coercive field (E{sub c}) increased with doping. - Abstract: Pure and doped multiferroic samples of bismuth ferrites (BFO) were successfully synthesized by the sol–gel technique. Detailed investigations were made on the influence of (Sm and Mn, Co, Cr) co-doping on structural, electrical, ferroelectric and magnetic properties of the BFO. A structural phase transformation from rhombohedral to orthorhombic with co-doping is confirmed through XRD. It is also observed that Sm-doping increases the symmetry and decreases the second phases noticeably. Microstructure investigation using the scanning electron microscope showed a reduction of grain size with doping in BFO. Magnetic hysteresis loops showed that retentivity (Mr), coercivity (Hc) and saturation magnetization (Ms) of the doped samples were improved. Furthermore, the co-doping enhances the dielectric properties as a result of the reduction in the Fe{sup 2+} ions and oxygen vacancies. The room temperature P–E loop study shows that ferroelectric properties are strongly depend on doping.

  20. Low-temperature liquid-phase epitaxy and optical waveguiding of rare-earth-ion-doped KY(WO4)2 thin layers

    NARCIS (Netherlands)

    Romanyuk, Y.E.; Utke, I.; Ehrentraut, D.; Apostolopoulos, V.; Pollnau, Markus; Garcia-Revilla, S.; Valiente, B.

    2004-01-01

    Crystalline $KY(WO_{4})_{2}$ thin layers doped with different rare-earth ions were grown on b-oriented, undoped $KY(WO_{4})_{2}$ substrates by liquid-phase epitaxy employing a low-temperature flux. The ternary chloride mixture of NaCl, KCl, and CsCl with a melting point of 480°C was used as a solven

  1. Low-temperature liquid-phase epitaxy and optical waveguiding of rare-earth-ion-doped $KY(WO_{4})_{2}$ thin layers

    NARCIS (Netherlands)

    Romanyuk, Y.E.; Utke, I.; Ehrentraut, D.; Apostolopoulos, V.; Pollnau, M.; Garcia-Revilla, S.; Valiente, B.

    2004-01-01

    Crystalline $KY(WO_{4})_{2}$ thin layers doped with different rare-earth ions were grown on b-oriented, undoped $KY(WO_{4})_{2}$ substrates by liquid-phase epitaxy employing a low-temperature flux. The ternary chloride mixture of NaCl, KCl, and CsCl with a melting point of 480°C was used as a solven

  2. Synthesis, characterization and properties of undoped und doped rare earth cuprates; Synthese, Charakterisierung und Eigenschaften undotierter und dotierter Seltenerdcuprate

    Energy Technology Data Exchange (ETDEWEB)

    Hord, Roland

    2014-06-01

    Undoped La{sub 2}CuO{sub 4} was prepared as bulk sample in the Nd{sub 2}CuO{sub 4} structure type by low-temperature synthesis using CsOH flux. The obtained product was characterized by X-ray powder diffractometry, high-temperature X-ray powder diffractometry, scanning electron microscopy, differential thermal analysis and high-temperature solution calorimetry, in order to examine the structural variations and stability regions of this compound. Furthermore, Pr{sub 2}CuO{sub 4}, which crystallizes also in the Nd{sub 2}CuO{sub 4} structure type, was prepared by high-temperature synthesis known from literature. Neutron diffraction studies on both La{sub 2}CuO{sub 4} and Pr{sub 2}CuO{sub 4} were performed to determine the exact occupancies of all oxygen atom positions. In addition, the dopability, that means the substitution of lanthanum by rare earth elements (Nd-Lu) was studied applying low-temperature synthesis. The properties of the doped compounds of the general formula La{sub 2-x}SE{sub x}CuO{sub 4}, SE = Gd-Nd were characterized by X-ray powder diffractometry, high-temperature X-ray powder diffractometry and scanning electron microscopy.

  3. Adjustable up-conversion luminescence color in rare earth co-doped transparent oxyfluoride nano-glass-ceramics.

    Science.gov (United States)

    Song, Zhiguo; Zhou, Dacheng; Qiu, Jianbei

    2010-03-01

    Transparent oxyfluoride nano-glass-ceramics with highly efficient up-conversion and adjustable color luminescence were developed in the 28SiO2 x 17Al2O3 28PbF2 x 22CdF2 x 0.1NdF3 x xYbF3 x yHoF3 zTmF3 x (4.9 - x - y - z)GdF3 composition, in mol%. X-ray diffraction and transmission electron microscopy measurements revealed that heat treatments of the oxyfluoride glasses cause the homogeneous precipitation of rare-earth ions co-doped fluorite-type Pb(x)Cd1-xF2 nanocrystals of about 10 nm in diameter in the glass matrix. Under single 808 nm laser excitation, intense red, green and blue up-conversion luminescences were simultaneously observed in these transparent nano-glass-ceramics owing to the successive energy transfer from Nd3+ ions to Ho3+ and Tm3+ via Yb3+ ions. Various colors of luminescence, including bright perfect white light, can be tuned by adjusting the concentrations of the Tm3+ ions in the material. A possible energy transfer process and up-conversion luminescence mechanism in the nano-glass-ceramics are proposed and discussed.

  4. Path integral Monte Carlo study of 4He clusters doped with alkali and alkali-earth ions.

    Science.gov (United States)

    Galli, D E; Ceperley, D M; Reatto, L

    2011-06-30

    Path integral Monte Carlo calculations of (4)He nanodroplets doped with alkali (Na(+), K(+) and Cs(+)) and alkali-earth (Be(+) and Mg(+)) ions are presented. We study the system at T = 1 K and between 14 and 128 (4)He atoms. For all studied systems, we find that the ion is well localized at the center of the droplet with the formation of a "snowball" of well-defined shells of localized (4)He atoms forming solid-like order in at least the first surrounding shell. The number of surrounding helium shells (two or three) and the number of atoms per shell and the degree of localization of the helium atoms are sensitive to the type of ion. The number of (4)He atoms in the first shell varies from 12 for Na(+) to 18 for Mg(+) and depends weakly on the size of the droplet. The study of the density profile and of the angular correlations shows that the local solid-like order is more pronounced for the alkali ions with Na(+) giving a very stable icosahedral order extending up to three shells.

  5. High pressure effects on the superconductivity in rare-earth-doped CaFe2As2

    Science.gov (United States)

    Uhoya, Walter; Cargill, Daniel; Gofryk, Krzysztof; Tsoi, Georgiy M.; Vohra, Yogesh K.; Sefat, Athena S.; Weir, S. T.

    2014-01-01

    High pressure superconductivity in a rare-earth-doped Ca0.86Pr0.14Fe2As2 single-crystalline sample has been studied up to 12 GPa and temperatures down to 11 K using the designer diamond anvil cell under a quasi-hydrostatic pressure medium. The electrical resistance measurements were complemented by high pressure and low-temperature X-ray diffraction studies at a synchrotron source. The electrical resistance measurements show an intriguing observation of superconductivity under pressure, with Tc as high as ∼51 K at 1.9 GPa, presenting the highest Tc reported in the intermetallic class of 122 iron-based superconductors. The resistive transition observed suggests a possible existence of two superconducting phases at low pressures of 0.5 GPa: one phase starting at Tc1 ∼ 48 K and the other starts at Tc2 ∼ 16 K. The two superconducting transitions show distinct variations with increasing pressure. High pressure and low-temperature structural studies indicate that the superconducting phase is a collapsed tetragonal ThCr2Si2-type (122) crystal structure.

  6. Composition dependence of the magnetic properties of strontium hexaferrite doped with rare earth ions

    Science.gov (United States)

    Singh, Taminder; Batra, M. S.; Singh, Iqbal; Katoch, Arun

    2014-09-01

    Rare earth substituted ferrite Sr1-xRExFe12O19 (where RE = La, Gd and Dy, x = 0.0, 0.10, 0.20 and 0.30), have been prepared by employing the ceramic technique and subsequent heat treatment. The magnetic properties of the calcined samples were characterized with a Vibrating Sample Magnetometer (VSM). The samples were sintered at 1150°C for 8 hours. The samples were characterized for magnetic properties such as specific saturation magnetization MS, specific remanence magnetization Mr, and coercivity Hc as well as microstructure. It has been observed that all these parameters depend on the composition and heat treatment of the prepared samples. The coercively Hc exhibits an increase as the RE content increases in Sr1-xRExFe12O19 ferrite. With increasing RE content the MS and Mr decrease due to dissolution of RE ion into hexaferrite lattice.

  7. Piezoelectric/photoluminescence effects in rare-earth doped lead-free ceramics

    Science.gov (United States)

    Yao, Qirong; Wang, Feifei; Jin, Chengchao; Tang, Yanxue; Wang, Tao; Shi, Wangzhou

    2013-10-01

    In the present work, we report the environmentally-friendly multifunctional effects—piezoelectric/photoluminescence effects, which originated from the combination of the electromechanical properties and the photoluminescence effect through introducing the rare-earth elements (Pr and Eu) into the (Bi0.5Na0.5)TiO3-BaTiO3 ceramics with the composition around the morphotropic phase boundary. Compared to the pure piezoelectric ceramic, the proposed system simultaneously exhibited enhanced ferroelectric, piezoelectric, dielectric properties along with strong photoluminescence effects, which exhibited potential applications in sensor, and electro-mechano-optical integration. In addition, the present work also provides a promising path for us to fabricate multifunctional composites.

  8. Evidence of dilute ferromagnetism in rare-earth doped yttrium aluminium garnet

    Energy Technology Data Exchange (ETDEWEB)

    Farr, Warrick G.; Goryachev, Maxim; Le Floch, Jean-Michel; Tobar, Michael E. [ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009 (Australia); Bushev, Pavel [Experimentalphysik, Universität des Saarlandes, D-66123 Saarbrücken (Germany)

    2015-09-21

    This work demonstrates strong coupling regime between an erbium ion spin ensemble and microwave hybrid cavity-whispering gallery modes in a yttrium aluminium garnet dielectric crystal. Coupling strengths of 220 MHz and mode quality factors in excess of 10{sup 6} are demonstrated. Moreover, the magnetic response of high-Q modes demonstrates behaviour which is unusual for paramagnetic systems. This behaviour includes hysteresis and memory effects. Such qualitative change of the system's magnetic field response is interpreted as a phase transition of rare earth ion impurities. This phenomenon is similar to the phenomenon of dilute ferromagnetism in semiconductors. The clear temperature dependence of the phenomenon is demonstrated.

  9. Structural elucidation and magnetic behavior evaluation of rare earth (La, Nd, Gd, Tb, Dy) doped BaCoNi-X hexagonal nano-sized ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, Abdul, E-mail: abdulmajeed2276@gmail.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Raheem, Faseeh ur; Hussain, Altaf; Iqbal, F. [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Akhtar, Majid Niaz [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Shakir, Imran [Deanship of Scientific Research, College of Engineering, King Saud University, PO Box 800, Riyadh 11421 (Saudi Arabia); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2016-06-15

    Rare-earth (RE=La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) doped Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route, which is a fast chemistry route for obtaining nano-sized ferrite powders. These nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as vibrating sample magnetometer (VSM). The XRD analysis exhibited that all the samples crystallized into single X-type hexagonal phase. The crystalline size calculated by Scherrer's formula was found in the range 7–19 nm. The variations in lattice parameters elucidated the incorporation of rare-earth cations in these nanomaterials. FTIR absorption spectra of these X-type ferrites were investigated in the wave number range 500–2400 cm{sup −1.} Each spectrum exhibited absorption bands in the low wave number range, thereby confirming the X-type hexagonal structure. The enhancement in the coercivity was observed with the doping of rare-earth cations. The saturation magnetization was lowered owing to the redistribution of rare-earth cations on the octahedral site (3b{sub VI}). The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Graphical abstract: Nano-sized rare-earth (RE=La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) doped Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route and the crystallite size was found in the range 7–19 nm. The enhancement in the coercivity was observed with the doping of rare-earth cations. The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Highlights: • Micro-emulsion route was used to synthesize Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} ferrites. • The crystallite size was found

  10. Morphological, Raman, electrical and dielectric properties of rare earth doped X-type hexagonal ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, Abdul, E-mail: abdulmajeed2276@gmail.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Center for Computational Materials Science, Department of Physics, University of Malakand, Chakdara, Dir (Lower) 18800 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Raheem, Faseeh ur [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Ahmad, Iftikhar [Center for Computational Materials Science, Department of Physics, University of Malakand, Chakdara, Dir (Lower) 18800 (Pakistan); Department of Physics, Abbottabad University of Science & Technology, Abbottabad (Pakistan); Akhtar, Majid Niaz [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2016-12-15

    The influence of rare-earth metals (La, Nd, Gd, Tb, Dy) on morphology, Raman, electrical and dielectric properties of Ba{sub 2}NiCoRE{sub x}Fe{sub 28−}xO{sub 46} ferrites were studied. The scanning electron microscopy (SEM) exhibited the platelet like structure of these hexagonal ferrites. The surface morphology indicated the formation of ferrite grains in the nano-regime scale. The bands obtained at lower wave number may be attributed to the metal-oxygen vibration at octahedral site which confirm the development of hexagonal phase of these ferrites. The resonance peaks were observed in dielectric constant, dielectric loss factor and quality factor versus frequency graphs. These dielectric parameters indicate that these ferrites nano-materials are potential candidates in the high frequency applications. The enhancement in DC electric resistivity from 2.48×10{sup 8} to 1.20×10{sup 9} Ω cm indicates that the prepared materials are beneficial for decreasing the eddy current losses at high frequencies and for the fabrication of multilayer chip inductor (MLCI) devices.

  11. Morphological, Raman, electrical and dielectric properties of rare earth doped X-type hexagonal ferrites

    Science.gov (United States)

    Majeed, Abdul; Khan, Muhammad Azhar; ur Raheem, Faseeh; Ahmad, Iftikhar; Akhtar, Majid Niaz; Warsi, Muhammad Farooq

    2016-12-01

    The influence of rare-earth metals (La, Nd, Gd, Tb, Dy) on morphology, Raman, electrical and dielectric properties of Ba2NiCoRExFe28-xO46 ferrites were studied. The scanning electron microscopy (SEM) exhibited the platelet like structure of these hexagonal ferrites. The surface morphology indicated the formation of ferrite grains in the nano-regime scale. The bands obtained at lower wave number may be attributed to the metal-oxygen vibration at octahedral site which confirm the development of hexagonal phase of these ferrites. The resonance peaks were observed in dielectric constant, dielectric loss factor and quality factor versus frequency graphs. These dielectric parameters indicate that these ferrites nano-materials are potential candidates in the high frequency applications. The enhancement in DC electric resistivity from 2.48×108 to 1.20×109 Ω cm indicates that the prepared materials are beneficial for decreasing the eddy current losses at high frequencies and for the fabrication of multilayer chip inductor (MLCI) devices.

  12. Heavy rare-earth-doped ZBLAN glasses for UV–blue up-conversion and white light generation

    Energy Technology Data Exchange (ETDEWEB)

    Méndez-Ramos, J., E-mail: jmendezr@ull.es [Departamento de Física Fundamental y Experimental, Electrónica y Sistemas, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain); Acosta-Mora, P. [Departamento de Física Fundamental y Experimental, Electrónica y Sistemas, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain); Ruiz-Morales, J.C., E-mail: jcruiz@ull.es [Departamento de Química Inorgánica, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain); Hernández, T.; Borges, M.E. [Departamento de Ingeniería Química, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain); Esparza, P., E-mail: pesparza@ull.es [Departamento de Química Inorgánica, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain)

    2013-11-15

    Noticeable UV–vis up-conversion luminescence of Er{sup 3+} and Tm{sup 3+} ions sensitised by Yb{sup 3+} ions in ZrF{sub 4}–BaF{sub 2}–LaF{sub 3}–AlF{sub 3}–NaF (ZBLAN) fluoride glasses have been obtained under near-infrared excitation at 980 nm. Red, green and blue simultaneous emissions were observed yielding to a white-balanced overall colour. Moreover significant UV up-conversion emissions observed can contribute to enhance spectral response of semiconductor electrode, such as TiO{sub 2} and Fe{sub 2}O{sub 3}, for sustainable production of hydrogen via water photolysis by harvesting of long wavelength solar irradiation, emerging as an interesting solely luminescent approach for improving water-splitting. Total infrared to UV–vis up-conversion efficiency has been calculated to be at around 46%. Laboratory tests prove the improvement in the photocatalytic action of a commercial benchmark photocatalyst (TiO{sub 2} Degussa P25) in the decomposition of methylene blue in water under sun-like irradiation, by a factor of 16% driven by up-conversion effects due to the inclusion of RE-doped ZBLAN powders into a slurry-type photo-reactor. -- Highlights: • Successful development of heavy rare-earth doped (Yb{sup 3+}–Tm{sup 3+}–Er{sup 3+}) ZBLAN glasses. • Very efficient red, green and blue simultaneous up-conversion emissions yielding to a white-balanced overall colour. • High intense UV up-conversion emissions to enhance spectral response of semiconductor electrode, such as TiO{sub 2} and Fe{sub 2}O{sub 3} to boost their photo-catalytic action in water-splitting. • Total infrared to UV–vis up-conversion efficiency calculated to be at around 46%. • Enhancement of about 16% of the photocatalytic activity of commercial TiO{sub 2} catalyst.

  13. Widely tunable, narrow line width and low optical noise continuous-wave all fiber Er:Yb co-doped double-clad ring laser

    Science.gov (United States)

    Guesmi, Khmaies; Bahloul, Faouzi; Semaan, Georges; Meng, Yichang; Salhi, Mohamed; Sanchez, François

    2017-01-01

    In this paper, we report a widely tunable, narrow linewidth, low noise continuous-wave double-clad Er:Yb doped fiber ring laser. Tunability is demonstrated in wide range spanning from 1520 to almost 1620 nm covering the C and L spectral bands. The cavity design is optimized in order to achieve the largest tuning range with very high optical signal-to-noise ratio (SNR). The output coupling ratio greatly influences the tuning range of the laser while the position of the spectral filter determines the SNR. The obtained laser exhibits a tuning range over 98 nm with a nearly constant SNR of about 58.5 dB.

  14. Quantum efficiency of silica-coated rare-earth doped yttrium silicate

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes-Vásquez, D., E-mail: dcervant@cnyn.unam.mx [Centro de Investigación Científica y de Educación Superior de Ensenada, Carretera Ensenada-Tijuana No. 3918, Zona Playitas, C.P. 22860 Ensenada, B.C., México (Mexico); Contreras, O.E.; Hirata, G.A. [Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Km. 107 Carretera Tijuana-Ensenada, C.P. 22800 Ensenada, B.C., México (Mexico)

    2013-11-15

    The photoluminescent properties of rare earth-activated white-emitting Y{sub 2}SiO{sub 5}:Ce,Tb nanocrystalline phosphor prepared by two different methods, pressure-assisted combustion synthesis and sol–gel, were studied. The synthesized phosphor samples were post-annealed at 1373 K and 1623 K in order to obtain the X1-Y{sub 2}SiO{sub 5} and X2-Y{sub 2}SiO{sub 5} phases, respectively, which were confirmed by X-ray diffraction measurements. Photoluminescence analysis showed the contribution of two blue-emission bands within the 380–450 nm region originating from 5d–4f transitions in Ce{sup 3+} ions and a well-defined green emission of Tb{sup 3+} ions located at 545 nm corresponding to {sup 5}D{sub 4}→{sup 7}F{sub 5} electronic transitions. Thereafter, Y{sub 2}SiO{sub 5}:Ce,Tb powders were coated with colloidal silica in order to investigate the effect of silica coatings on their luminescent properties. Absolute fluorescence quantum efficiency measurements were carefully performed, which revealed an increase of 12% of efficiency in coated compared with bare-Y{sub 2}SiO{sub 5}:Ce,Tb phosphor. -- Highlights: • Y{sub 2}SiO{sub 5}:Ce,Tb phosphor powders were successfully coated with colloidal silica. • Post-annealing treatments improved the quantum efficiency of silica-coated Y{sub 2}SiO{sub 5}:Ce,Tb phosphors. • Absolute fluorescence quantum efficiency measurements showed an increase of 12%.

  15. Influences of rare earth element Ce-doping and melt-spinning on microstructure and magnetostriction of Fe{sub 83}Ga{sub 17} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Zhanquan, E-mail: ndyzq@126.com [School of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot 010018 (China); Tian, Xiao, E-mail: nsdtx@126.com [Key Laboratory for Physics and Chemistry of Functional Materials, School of Physics and Electronic Information, Inner Mongolia Normal University, Hohhot 010022 (China); Jiang, Liping; Hao, Hongbo; Zhang, Guangrui; Wu, Shuangxia; Zhao, Zengqi [Baotou Research Institute of Rare Earths, Baotou 014030 (China); Gerile, Naren [Key Laboratory for Physics and Chemistry of Functional Materials, School of Physics and Electronic Information, Inner Mongolia Normal University, Hohhot 010022 (China)

    2015-07-15

    Highlights: • The CeGa{sub 2} phase existing in the Fe{sub 83}Ga{sub 17}Ce{sub 0.8} alloy is found for the first time. • The (100) orientation of alloy become stronger after Ce doping into the Fe-Ga alloy. • The melt-spinning leads to the formation of asymmetrical DO{sub 3} phase. • The enhanced magnetostriction is credited with new phase and preferred orientation. • The Ce-doping and melt-spinning are beneficial to the improvement of magnetostriction. - Abstract: In order to improve magnetostriction of the polycrystalline Fe-Ga alloy, the rare earth element Ce was firstly doped into Fe{sub 83}Ga{sub 17} and the melt-spinning method was subsequently applied. The as-cast Fe{sub 83}Ga{sub 17} and Ce-doped Fe{sub 83}Ga{sub 17} alloys were prepared by arc melting. Then the as-cast Ce-doped Fe{sub 83}Ga{sub 17} alloy was melt-spun by the melt-spinning technique. The microstructures and magnetostrictions of all these three alloys were investigated by X-ray diffractometer (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), differential scanning calorimeter (DSC) and magnetostriction measurements. The results indicated that the CeGa{sub 2} phase and asymmetrical DO{sub 3} phase are formed caused by Ce-doping and melt-spinning, respectively. The magnetostrictions of three alloys are ranked in sequence the melt-spun Fe{sub 83}Ga{sub 17}Ce{sub 0.8} alloy > as-cast Fe{sub 83}Ga{sub 17}Ce{sub 0.8} alloy > as-cast Fe{sub 83}Ga{sub 17} alloy. The enhanced magnetostriction is attributed to the fact that the formation of new phases and the preferred orientation along (100) direction.

  16. Enhanced Electroresponse of Alkaline Earth Metal-Doped Silica/Titania Spheres by Synergetic Effect of Dispersion Stability and Dielectric Property.

    Science.gov (United States)

    Yoon, Chang-Min; Lee, Seungae; Cheong, Oug Jae; Jang, Jyongsik

    2015-09-01

    A series of alkaline earth metal-doped hollow SiO2/TiO2 spheres (EM-HST) are prepared as electrorheological (ER) materials via sonication-mediated etching method with various alkaline earth metal hydroxides as the etchant. The EM-HST spheres are assessed to determine how their hollow interior and metal-doping affects the ER activity. Both the dispersion stability and the dielectric properties of these materials are greatly enhanced by the proposed one-step etching method, which results in significant enhancement of ER activity. These improvements are attributed to increased particle mobility and interfacial polarization originating from the hollow nature of the EM-HST spheres and the effects of EM metal-doping. In particular, Ca-HST-based ER fluid exhibits ER performance which is 7.1-fold and 3.1-fold higher than those of nonhollow core/shell silica/titania (CS/ST) and undoped hollow silica/titania (HST)-based ER fluids, respectively. This study develops a versatile and simple approach to enhancing ER activity through synergetic effects arising from the combination of dispersion stability and the unique dielectric properties of hollow EM-HST spheres. In addition, the multigram scale production described in this experiment can be an excellent advantage for practical and commercial ER application.

  17. Systematic Structural Change in Selected Rare Earth Oxide Pyrochlores as Determined by Wide-Angle CBED and a Comparison with the Results of Atomistic Computer Simulation

    Science.gov (United States)

    Tabira, Yasunori; Withers, Ray L.; Minervini, Licia; Grimes, Robin W.

    2000-08-01

    An unknown oxygen atom fractional co-ordinate characteristic of the pyrochlore structure type has been determined for selected rare earth zirconate and titanate pyrochlores via a systematic row wide-angle CBED technique and shown to vary systematically with rare earth ion size. In the case of the titanate pyrochlore Gd2Ti2O7, the obtained results contrast with previously published X-ray results. Atomistic computer simulation is used to predict the value of the same parameter for a wide range of oxide pyrochlores. Comparison of calculated values with experimentally determined values shows that the general trends are correctly predicted although there appears to be systematic underestimation of both the observed values (by approximately 0.007) as well as their rate of change with rare earth ion size. Cation anti-site disorder is proposed as the origin of these discrepancies.

  18. Synthesis and luminescent properties of rare earth (Sm3+ and Eu3+) Doped Gd2Ti2O7 pyrochlore nanopowders

    Science.gov (United States)

    Ćulubrk, Sanja; Antić, Željka; Marinović-Cincović, Milena; Ahrenkiel, Phillip S.; Dramićanin, Miroslav D.

    2014-11-01

    This work describes the synthesis and photoluminescent properties of rare earth (Sm3+ and Eu3+) doped Gd2Ti2O7 pyrochlore nanopowders. Pure-phase rare earth-doped Gd2Ti2O7 nanoparticles of approximately 20-50 nm in diameter, as evidenced from X-ray diffraction and electron microscopy analysis, are produced via the mixed metal-citric acid complex method. A temperature of 880 °C is identified for the formation of the crystalline pyrochlore phase, based on a differential thermal analysis of Gd2Ti2O7 precursor gels. From photoluminescence excitation and emission spectra, measured at 10 K and room temperature, the energy levels of Sm3+ and Eu3+ ions in Gd2Ti2O7 nanoparticles are obtained. The dependence of luminescence emission intensity and emission decays on rare earth concentration are measured and discussed. The strongest Sm3+ orange-reddish emission is observed for samples containing 2.5 at.% of Sm3+ ions, while in the case of Eu3+, the most intense emission is found for 15 at.% Eu3+ doping. The 4G5/2 level lifetime decreases with an increase in Sm3+ concentration, from about 5 ms (for 0.1-0.2 at.% of Sm3+) to 2.4 ms (for 2.5 at.% of Sm3+). With an increase in Eu3+ concentration in the Gd2Ti2O7 nanoparticles, the Eu3+5D0 level lifetime decreases from ∼5.9 ms (for 0.5 at.% of Sm3+) to 3.1 ms (for 15 at.% of Sm3+).

  19. Rare earth metal doped CeO2-based catalytic materials for diesel soot oxidation at lower temperatures

    Institute of Scientific and Technical Information of China (English)

    A Rangaswamy; Putla Sudarsanam; Benjaram M Reddy

    2015-01-01

    In this work, the influence of trivalent rare-earth dopants (Sm and La) on the structure-activity properties of CeO2 was thor-oughly studied for diesel soot oxidation. For this, an optimized 40%of Sm and La was incorporated into the CeO2 using a facile co-precipitation method from ultra-high dilute aqueous solutions. A systematic physicochemical characterization was carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), Brumauer-Emmett-teller method (BET) surface area, X-ray pho-toelectron spectroscopy (XPS), Raman, and H2-temperature programmed reduction (TPR) techniques. The soot oxidation efficiency of the catalysts was investigated using a thermogravimetric method. The XRD results suggested the formation of nanocrystalline sin-gle phase CeO2-Sm2O3 and CeO2-La2O3 solid solutions. The Sm-and La-doped CeO2 materials exhibited smaller crystallite size and higher BET surface area compared with the pure CeO2. Owing to the difference in the oxidation states of the dopants (Sm3+and La3+) and the Ce4+, a number of oxygen vacancies were generated in CeO2-Sm2O3 and CeO2-La2O3 samples. The H2-TPR studies evidenced the improved reducible nature of the CeO2-Sm2O3 and CeO2-La2O3 samples compared with the CeO2. It was found that the addition of Sm and La to the CeO2 outstandingly enhanced its catalytic efficiency for the oxidation of diesel soot. The observed 50%soot con-version temperatures for the CeO2-Sm2O3, CeO2-La2O3 and CeO2 were~790, 843 and 864 K (loose contact), respectively, and similar activity order was also found under the tight contact condition. The high soot oxidation efficacy of the CeO2-Sm2O3 sample was at-tributed to numerous catalytically favourable properties, like smaller crystallite size, larger surface area, abundant oxygen vacancies, and superior reducible nature.

  20. Facile fabrication and photoluminescence properties of rare-earth-doped Gd₂O₃ hollow spheres via a sacrificial template method.

    Science.gov (United States)

    Gao, Yu; Zhao, Qian; Fang, Qinghong; Xu, Zhenhe

    2013-08-21

    Rare-earth-doped gadolinium oxide (Gd₂O₃) hollow spheres were successfully fabricated on a large scale by using PS spheres as sacrificed templates and urea as a precipitating agent, which involved the deposition of an inorganic coating Gd(OH)CO3 on the surface of PS spheres and subsequent calcination in the air. Various approaches including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), as well as photoluminescence spectroscopies were used to characterize the samples. The results indicate that the sample is composed of uniform hollow Gd₂O₃ spheres with a mean particle size of about 2.3 μm and these hollow spheres have the mesoporous shell that are composed of a large amount of nanoparticles. The possible mechanism of evolution from PS spheres to the amorphous precursor and to the final hollow Gd₂O₃ spheres have been proposed. The as-obtained samples show strong light emission with different colors corresponding to different Ln³⁺ ions under ultraviolet-visible light and electron-beam excitation. Under 980 nm NIR irradiation, Gd₂O₃:Ln³⁺ (Ln³⁺ = Yb³⁺/Er³⁺, Yb³⁺/Tm³⁺ and Yb³⁺/Ho³⁺) exhibit characteristic up-conversion (UC) emissions of red (Er³⁺, ²H11/2, ⁴S3/2, ⁴F9/2 → ⁴I15/2), blue (Tm³⁺, ¹G₄ → ³H₆) and green (Ho³⁺, ⁵F₄, ⁵S₂ → ⁵I₈), respectively. These merits of multicolor emissions in the visible region endow these kinds of materials with potential applications in the field of light display systems, lasers, optoelectronic devices, and MRI contrast agents.

  1. Acoustic investigations on PbO–Al2O3–B2O3 glasses doped with certain rare earth ions

    Indian Academy of Sciences (India)

    M Rami Reddy; S Bangaru Raju; N Veeraiah

    2001-02-01

    Elastic moduli (, ), Poisson’s ratio (), microhardness () and some thermodynamical parameters such as Debye temperature (), diffusion constant (), latent heat of melting ( ) etc of PbO–Al2O3–B2O3 glasses doped with rare earth ions viz. Pr3+, Nd3+, Sm3+, Eu3+, Tb3+, Dy3+, Ho3+, Er3+ and Yb3+, are studied as functions of temperatures (in the temperature range 30–200°C) by ultrasonic techniques. All these parameters are found to increase with increasing atomic number of the rare earth ions and found to decrease with increasing temperature of measurement. From these results (together with IR spectra of these glasses), an attempt is made to throw some light on the mechanical strength of these glasses.

  2. X-Ray Absorption Spectroscopy Studies of the Atomic Structure of Zirconium-Doped Lithium Silicate Glasses and Glass-Ceramics, Zirconium-Doped Lithium Borate Glasses, and Vitreous Rare-Earth Phosphates

    Science.gov (United States)

    Yoo, Changhyeon

    In the first part of this work, the atomic-scale structure around rare-earth (RE = Pr, Nd, Eu, Dy, and Er) cations (RE3+) in rare-earth sodium ultraphosphate (REUP) glasses were investigated using RE LIII -edge (RE = Nd, Er, Dy, and Eu) and K-edge (RE = Pr and Dy) Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. (RE2O 3)x(Na2O)y(P2O5) 1-x-y glasses in the compositional range 0 ≤ x ≤ 0.14 and 0.3 ≤ x + y ≤ 0.4 were studied. For the nearest oxygen shell, the RE-oxygen (RE-O) coordination number decreases from 10.8 to 6.5 with increasing RE content for Pr-, Nd-, Dy-, and Er-doped sodium ultraphosphate glasses. For Eu-doped samples, the Eu-O coordination number was between 7.5 and 8.8. Also, the RE-O mean distance ranges were between 2.43-2.45 A, 2.40-2.43 A, 2.36-2.38 A, 2.30-2.35 A, and 2.28-2.30 A for Pr-, Nd-, Eu-, Dy-, and Er-doped samples, respectively. In the second part, a series of Zr-doped (3-10 mol%) lithium silicate (ZRLS) glass-ceramics and their parent glasses and a series of Zr-doped (2-6 mol% ZrO2) lithium borate (ZRLB) glasses were investigated using Zr K-edge EXAFS and X-ray Absorption Near Edge Structure (XANES) spectroscopy. Immediate coordination environments of all ZRLS glasses are remarkably similar for different compositions. For the nearest oxygen shell, the Zr-O coordination number ranges were between 6.1 and 6.3 for nucleated and crystallized samples, respectively. Also, the Zr-O mean distance remains similar around 2.10 A. For these glasses, the composition dependence of structural parameters was small. Small changes in the coordination environment were observed for ZRLS glass-ceramics after thermal treatments. In contrast, Zr coordination environment in ZRLB glasses appear to depend appreciably on the Zr concentration. For the nearest oxygen shell, the Zr-O coordination number increased from 6.1 to 6.8 and the Zr-O distance decreased from 2.18 A to 2.14 A with decreasing ZrO2 content.

  3. Eu3+-Doped Wide Band Gap Zn2SnO4 Semiconductor Nanoparticles: Structure and Luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrievska, Mirjana; Ivetic, Tamara B.; Litvinchuk, Alexander P.; Fairbrother, Andrew; Miljevic, Bojan B.; Strbac, Goran R.; Rodriguez, Alejandro Perez; Lukic-Petrovic, Svetlana R.

    2016-08-25

    Nanocrystalline Zn2SnO4 powders doped with Eu3+ ions were synthesized via a mechanochemical solid-state reaction method followed by postannealing in air at 1200 degrees C. X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and Raman and photoluminescence (PL) spectroscopies provide convincing evidence for the incorporation of Eu3+ ions into the host matrix on noncentrosymmetric sites of the cubic inverse spinel lattice. Microstructural analysis shows that the crystalline grain size decreases with the addition of Eu3+. Formation of a nanocrystalline Eu2Sn2O7 secondary phase is also observed. Luminescence spectra of Eu3+-doped samples show several emissions, including narrow-band magnetic dipole emission at 595 nm and electric dipole emission at 615 nm of the Eu3+ ions. Excitation spectra and lifetime measurements suggest that Eu3+ ions are incorporated at only one symmetry site. According to the crystal field theory, it is assumed that Eu3+ ions participate at octahedral sites of Zn2+ or Sn4+ under a weak crystal field, rather than at the tetrahedral sites of Zn2+, because of the high octahedral stabilization energy for Eu3+. Activation of symmetry forbidden (IR-active and silent) modes is observed in the Raman scattering spectra of both pure and doped samples, indicating a disorder of the cation sublattice of Zn2SnO4 nanocrystallites. These results were further supported by the first principle lattice dynamics calculations. The spinel-type Zn2SnO4 shows effectiveness in hosting Eu3+ ions, which could be used as a prospective green/red emitter. This work also illustrates how sustainable and simple preparation methods could be used for effective engineering of material properties.

  4. PERFORMANCE ANALYSIS OF DIFFERENT ERBIUM DOPED FIBER BASED CODIRECTIONALLY PUMPED WDMSYSTEMS OPERATING IN OPTICAL WIDE-BAND

    Directory of Open Access Journals (Sweden)

    RICKY ANTHONY

    2012-02-01

    Full Text Available In this paper, simulation studies for different types of erbium doped fiber amplifier (EDFA based codirectionally pumped systems, operating in C and L band have been analyzed for wave division multiplexing (WDM, which is in accordance with ITU standards. The natural gain and noise figure (NF for variable pump powers at 0.03W, 0.06W, 0.12W, 0.18W and 0.24W were obtained. A comparative study of these fiberamplifiers using a figure of merit (FOM, in terms of gain uniformity in the given optical band was discussed.

  5. Widely-tunable, passively Q-switched erbium-doped fiber laser with few-layer MoS2 saturable absorber.

    Science.gov (United States)

    Huang, Yizhong; Luo, Zhengqian; Li, Yingyue; Zhong, Min; Xu, Bin; Che, Kaijun; Xu, Huiying; Cai, Zhiping; Peng, Jian; Weng, Jian

    2014-10-20

    We propose and demonstrate a MoS2-based passively Q-switched Er-doped fiber laser with a wide tuning range of 1519.6-1567.7 nm. The few-layer MoS2 nano-platelets are prepared by the liquid-phase exfoliation method, and are then made into polymer-composite film to construct the fiber-compatible MoS2 saturable absorber (SA). It is measured at 1560 nm wavelength, that such MoS2 SA has the modulation depth of ∼ 2% and the saturable optical intensity of ∼ 10 MW/cm(2). By further inserting the filmy MoS2-SA into an Er-doped fiber laser, stable Q-switching operation with a 48.1 nm continuous tuning from S- to C-waveband is successfully achieved. The shortest pulse duration and the maximum pulse energy are 3.3 μs and 160 nJ, respectively. The repetition rate and the pulse duration under different operation conditions have been also characterized. To the best of our knowledge, it is the first demonstration of MoS2 Q-switched, widely-tunable fiber laser.

  6. Luminescent features of sol-gel derived rare-earth multi-doped oxyfluoride nano-structured phosphors for white LED application

    Energy Technology Data Exchange (ETDEWEB)

    Gouveia-Neto, A.S., E-mail: artur@df.ufrpe.br [Departamento de Fisica, Universidade Federal Rural de Pernambuco, Recife, PE (Brazil); Silva, A.F. da; Bueno, L.A.; Costa, E.B. da [Departamento de Fisica, Universidade Federal Rural de Pernambuco, Recife, PE (Brazil)

    2012-02-15

    Rare-earth doped oxyfluoride 75SiO{sub 2}:25PbF{sub 2} nano-structured phosphors for white-light-emitting diodes were synthesized by thermal treatment of precursor sol-gel derived glasses. Room temperature luminescence features of Eu{sup 3+}, Sm{sup 3+}, Tb{sup 3+}, Eu{sup 3+}/Tb{sup 3+}, and Sm{sup 3+}/Tb{sup 3+} ions incorporated into low-phonon-energy PbF{sub 2} nanocrystals dispersed in the aluminosilicate glass matrix and excited with UV light emitting diode were investigated. The luminescence spectra exhibited strong emission signals in the red (600, 610, 625, and 646 nm), green (548 and 560 nm), and blue (485 nm) wavelength regions. White-light emission was observed in Sm/Tb and Eu/Tb double-doped activated phosphors employing UV-LED excitation at 395 nm. The dependence of the luminescence emission intensities upon annealing temperature and rare-earth concentration was also examined. The results indicated that there exist optimum annealing temperature and activator ion concentration in order to obtain intense visible emission light with high color rendering index. The study suggests that the nanocomposite phosphor based upon 75SiO{sub 2}:25PbF{sub 2} host herein reported is a promising contender for white-light LED applications. - Highlights: Black-Right-Pointing-Pointer White-light emission in double-doped activated phosphors employing UV-LED excitation. Black-Right-Pointing-Pointer Luminescent features of europium, samarium, and terbium in nanocrystals dispersed in aluminosilicate glass. Black-Right-Pointing-Pointer New nanocomposite phosphor host for white-light LED applications.

  7. Preparation and Characterization of Yb - doped YAG Ceramics

    OpenAIRE

    2011-01-01

    Rare-earth doped yttrium aluminum garnet (YAG) ceramics are among the most widely produced transparent ceramics for laser applications. Yb:YAG ceramics are an interesting IR laser material [1], which allows significantly higher doping compared to the generally more used Nd:YAG [2,3]. This work presents the preparation of polycrystalline Yb:YAG ceramics with dopant concentration from 0 up to 20 at.% via solid state reactive sintering. Samples were prepared via cold isostatic pressing of spray ...

  8. Luminescence quenching versus enhancement in WO3-NaPO3 glasses doped with trivalent rare earth ions and containing silver nanoparticles

    Science.gov (United States)

    Dousti, M. Reza; Poirier, Gael Y.; Amjad, Raja J.; de Camargo, Andrea S. S.

    2016-10-01

    We report on the influence of silver nanoparticles (NPs) on the luminescence behavior of trivalent rare earth (RE) ion doped tungsten-phosphate glasses. In order to induce the growth of NPs, the as-prepared glass samples containing silver atoms, are exposed to heat-treatment above the glass transition temperature. The surface plasmon resonance band of the Ag NPs is observed in the visible range around 420 and 537 nm in the glasses with low and high tungsten content, respectively. Such difference in spectral shift of the plasmon band is attributed to the difference in the refractive index of the two studied glass compositions. Heat-treatment results in the general increase in number of NPs, while in the case of glasses with low tungsten content, it also imposes a shift to the Ag plasmon band. The NPs size distribution (4-10 nm) was determined in good agreement with the values obtained by using Mie theory and by transmission electron microscopy. The observed quenching in the visible luminescence of glasses doped with Eu3+, Tb3+ or Er3+is attributed to energy transfer from the RE ions to Ag species, while an enhanced near-infrared emission in Er3+ doped glasses is discussed in terms of the chemical contribution of silver, rather than the most commonly claimed enhancement of localized field or energy transfer from silver species to Er3+. The results are supported by the lifetime measurements. We believe that this study gives further insight and in-depth exploration of the somewhat controversial discussions on the influence of metallic NPs plasmonic effects in RE-doped glasses.

  9. Mechanism of Phase Transformation and Formation of Barium Hexaferrite Doped with Rare-Earths in Sol-Gel Process

    Institute of Scientific and Technical Information of China (English)

    甘树才; 洪广言; 张军; 车平; 唐娟

    2003-01-01

    The phase-transformation in sol-gel preparation of barium hexaferrite and the formation of barium hexaferrite doped with La3+ were studied by chemical phase analysis, X-ray diffraction and infrared spectrometry analysis. The experimental results show that phase transformation reactions of FeCO3, Fe2O3 and BaFe2O4, barium hexaferrite and γ-Fe2O3 take place in the heat treatment of gel. While the doping lanthanide ion replace barium ion, an equivalent quantity of Fe3+ are reduced to Fe2+ to maintain the charge equilibrium.

  10. Widely and continuously tunable optical parametric generator based on MgO-doped periodically poled LiNbO3 crystal

    Science.gov (United States)

    Diao, Shuyan; Yao, Jianquan; Zheng, Yi; Geng, Youfu; Tan, Xiaoling; Liu, Qiang; Xu, Longhao

    2006-09-01

    A widely and continuously tunable optical parametric generator (OPG) pumped by a 1064-nm acousto-optically Q-switched diode-end-pumped Nd:YAG laser based on MgO-doped periodically poled LiNbO3 crystal with a multigrating structure (29.2-30.4 micron) is reported. A broad continuous signal spectrum of 1513-1700 nm is obtained by changing the crystal grating periods from 29.2 to 30.4 micron and by tuning the crystal temperature from 30 to 180 Celsius degrees simultaneously. When the average pump power is 1.82 W with pulse duration of about 70 ns operating at a repetition rate of 10 kHz, the maximum signal output power of the periodically poled MgO-doped lithium niobate (PPMgLN) OPG is about 210 mW corresponding to the idler and total powers of 118.4 and 328.4 mW respectively.

  11. Widely and continuously tunable optical parametric generator based on MgO-doped periodically poled LiNbO3 crystal

    Institute of Scientific and Technical Information of China (English)

    Shuyan Diao; Jianquan Yao; Yi Zheng; Youfu Geng; Xiaoling Tan; Qiang Liu; Longhao Xu

    2006-01-01

    @@ A widely and continuously tunable optical parametric generator (OPG) pumped by a 1064-nm acoustooptically Q-switched diode-end-pumped Nd:YAG laser based on MgO-doped periodically poled LiNbO3 crystal with a multigrating structure (29.2-30.4 μm) is reported.A broad continuous signal spectrum of 1513-1700 nm is obtained by changing the crystal grating periods from 29.2 to 30.4μm and by tuning the crystal temperature from 30 to 180 ℃ simultaneously.When the average pump power is 1.82 W with pulse duration of about 70 ns operating at a repetition rate of 10 kHz,the maximum signal output power of the periodically poled MgO-doped lithium niobate (PPMgLN) OPG is about 210 mW corresponding to the idler and total powers of 118.4 and 328.4 mW respectively.

  12. Synthesis of three-dimensional rare-earth ions doped CNTs-GO-Fe{sub 3}O{sub 4} hybrid structures using one-pot hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Guo, E-mail: guogao@sjtu.edu.cn [Institute of Nano Biomedicine and Engineering, Department of Instrument Science and Technology, Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhang, Qiang; Cheng, Xin-Bing [Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China); Sun, Rongjin [Institute of Nano Biomedicine and Engineering, Department of Instrument Science and Technology, Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Shapter, Joseph G., E-mail: joe.shapter@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, Bedford Park, Adelaide 5042 (Australia); Yin, Ting [Institute of Nano Biomedicine and Engineering, Department of Instrument Science and Technology, Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Cui, Daxiang, E-mail: dxcui@sjtu.edu.cn [Institute of Nano Biomedicine and Engineering, Department of Instrument Science and Technology, Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-11-15

    Rechargeable lithium ion batteries (LIBs) are currently the dominant power source for all sorts of electronic devices due to their low cost and high energy density. The cycling stability of LIBs is significantly compromised due to the broad satellite peak for many anode materials. Herein, we develop a facile hydrothermal process for preparing rare-earth (Er, Tm) ions doped three-dimensional (3D) transition metal oxides/carbon hybrid nanocomposites, namely CNTs-GO-Fe{sub 3}O{sub 4}, CNTs-GO-Fe{sub 3}O{sub 4}-Er and CNTs-GO-Fe{sub 3}O{sub 4}-Tm. The GO sheets and CNTs are interlinked by ultrafine Fe{sub 3}O{sub 4} nanoparticles forming three-dimensional (3D) architectures. When evaluated as anode materials for LIBs, the CNTs-GO-Fe{sub 3}O{sub 4} hybrid composites have a bigger broad satellite peak. As for the CNTs-GO-Fe{sub 3}O{sub 4}-Er and CNTs-GO-Fe{sub 3}O{sub 4}-Tm hybrid composites, the broad satellite peak can be completely eliminated. When the current density changes from 5 C back to 0.1 C, the capacity of CNTs-GO-Fe{sub 3}O{sub 4}-Tm hybrid composites can recover to 1023.9 mAhg{sup −1}, indicating an acceptable rate capability. EIS tests show that the charge transfer resistance does not change significantly after 500 cycles, demonstrating that the cycling stability of CNTs-GO-Fe{sub 3}O{sub 4}-Tm hybrid composites are superior to CNTs-GO-Fe{sub 3}O{sub 4} and CNTs-GO-Fe{sub 3}O{sub 4}-Er hybrid structures. - Graphical abstract: One-pot hydrothermal method for synthesis of rare-earth ions doped CNTs-GO-Fe{sub 3}O{sub 4} hybrid structures as anode materials of LIBs have been reported. - Highlights: • We report the synthesis of rare-earth ions doped CNTs-GO-Fe{sub 3}O{sub 4} hybrid structures. • The hybrid structures can improve the cycling stability of lithium storage. • As for anode materials, the broad satellite peak can be completely eliminated. • When the rate return back to 0.1 C, the capacity can recover to 1023.9 mAhg{sup −1}. • After 500

  13. Silver doping of silica-hafnia waveguides containing Tb3+/Yb3+ rare earths for downconversion in PV solar cells

    Science.gov (United States)

    Enrichi, F.; Armellini, C.; Battaglin, G.; Belluomo, F.; Belmokhtar, S.; Bouajaj, A.; Cattaruzza, E.; Ferrari, M.; Gonella, F.; Lukowiak, A.; Mardegan, M.; Polizzi, S.; Pontoglio, E.; Righini, G. C.; Sada, C.; Trave, E.; Zur, L.

    2016-10-01

    The aim of this paper is to study the possibility to obtain an efficient downconverting waveguide which combines the quantum cutting properties of Tb3+/Yb3+ codoped materials with the optical sensitizing effects provided by silver doping. The preparation of 70SiO2-30HfO2 glass and glass-ceramic waveguides by sol-gel route, followed by Ag doping by immersion in molten salt bath is reported. The films were subsequently annealed in air to induce the migration and/or aggregation of the metal ions. Results of compositional and optical characterization are given, providing evidence for the successful introduction of Ag in the films, while the photoluminescence emission is strongly dependent on the annealing conditions. These films could find potential applications as downshifting layers to increase the efficiency of PV solar cells.

  14. Microemulsion synthesis of nanosized TiO(2) particles doping with rare-earth and their photocatalytic activity.

    Science.gov (United States)

    Jian, Zicong; Pu, Yuying; Fang, Jianzhang; Ye, Zhiping

    2010-01-01

    Microemulsion is the easiest and cleanest of the popular methods of synthesizing nanomaterial. This work synthesized the nanosized La-TiO(2) and Ce-TiO(2) particles through the hydrolyzation of tetrabutyl titanate in a Triton X-100/n-hexanol/cyclohexane/water reverse microemulsion. The particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetry (TG). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) under ultraviolet light and visible light irradiation. The results showed that reverse microemulsion produced the nanosized and well-separated particles, which are obviously in degrading MO. Comparing the pure TiO(2) with doping TiO(2) , the doping ones are smaller and have better photocatalytic activity, which was best at the molar content of 0.1% for La, whereas for Ce it was 0.5%.

  15. Optical Properties of Li2B4O7 Glasses Doped with Rare-Earths and Transition Metal Ions

    Science.gov (United States)

    2001-01-01

    K.P. O’Donnell, B. Henderson and D. Hollis, " Disorder and the optical spectroscopy of Cr 3+- doped glasses: II. Glasses with high and low ligand...ions in oxide compounds", Fiz. Tw. Tela, 31(1), pp. 243-249, 1989. 11. W. Chen, J.O. Maim, V. Zwiller, Y. Huang, S. Liu, R. Wallenberg , J.O. Bovin and L

  16. Evaluation of rare earth oxides doping SnO2.(Co1/4,Mn3/4O-based varistor system

    Directory of Open Access Journals (Sweden)

    Alessandro Dibb

    2006-09-01

    Full Text Available The present paper aims to verify the inuence of rare earth oxide such as lanthanum (La2O3 and neodymium (Nd2O3 doping SnO2 + 0.25%CoO + 0.75%MnO2 + 0.05%Ta2O5 system. The analysis focus on microstructural inuence on electrical properties. Microstructural analysis were made by using Transmission Electron Microscopy (TEM at different regions of the samples. From such analysis it was found that La2O3 and Nd2O3 oxides cause heterogeneous segregation and precipitation at grain boundary concerning cobalt and manganese, decreasing the nonohmic electrical properties, as discussed, likely due to the increasing of grain boundary non-active potential barriers.

  17. Application of doped rare-earth oxide TiO2:(Tm3+, Yb3+) in dye-sensitized solar cells

    Science.gov (United States)

    Xie, Guixiang; Wei, Yuelin; Fan, Leqing; Wu, Jihuai

    2012-01-01

    Tm3+ and Yb3+ are codoped into TiO2 film in a dye-sensitized solar cell (DSSC). The emission and excitation spectra of TiO2:(Tm3+, Yb3+) power shows that the rare-earth ions possess up-conversion luminescence function, which results in harvesting more incident light and increasing photocurrent for the DSSC. On the other hand, owing to the p-type doping effect by Tm3+ and Yb3+, the photovoltage of the DSSC is enhanced. Under a simulated solar light irradiation of 100 mW·cm-2, a DSSC containing Tm3+/Yb3+ achieves a conversion efficiency of 7.05 %, which is increased by 10.0% compared with a DSSC lacking Tm3+/Yb3+.

  18. Chemical environment of rare earth ions in Ge28.125Ga6.25S65.625 glass-ceramics doped with Dy3+

    Science.gov (United States)

    Wang, Rongping; Yan, Kunlun; Zhang, Mingjie; Shen, Xiang; Dai, Shixun; Yang, Xinyu; Yang, Zhiyong; Yang, Anping; Zhang, Bin; Luther-Davies, Barry

    2015-10-01

    We have annealed Ge28.125Ga6.25S65.625 glasses doped with 0.5% Dy to create glass-ceramics in order to examine the local chemical environment of the rare earth ions (REI). More than 12 times enhancement of the emission at 2.9 and 3.5 μm was achieved in glass-ceramics produced using prolonged annealing time. Elemental mapping showed clear evidence that Ga2S3 crystalline grains with a size of 50 nm were dispersed in a Ge-S glass matrix in the glass-ceramics, and the REI could only be found near the Ga2S3 crystalline grains. From the unchanged lineshape of the emissions at 2.9 and 3.5 μm and lack of splitting of the absorption peaks, we concluded that the REI were bonded to Ga on the surface of the Ga2S3 crystals.

  19. Depolarization effect in rare-earth doped Y{sub 2}O{sub 3} films in blue and UV spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Gasimov, Naghi; Mammadov, Eldar; Babayev, Sardar; Mamedova, Irada; Mamedov, Nazim [Department of Ellipsometry, Institute of Physics, Azerbaijan National Academy of Sciences, H. Javid ave. 33, Baku-1143 (Azerbaijan); Joudrier, Anne L.; Andriamiadamanana, Christian; Naghavi, Negar; Guillemoles, Jean F. [Institute for Research and Development of Photovoltaic Energy, 6 Quai Watier, 78401 Chatou, Paris (France)

    2015-06-15

    The 200 to 300 nm thick, Er and Er,Yb doped Y{sub 2}O{sub 3} films deposited onto silicon substrate by spin coating have been studied by spectroscopic ellipsometry over the 192-1680 nm spectral range at room temperature. All samples have been found to be strongly depolarizing in the blue and UV part of the spectrum. Complimentary examination of the sample surfaces, using confocal photoluminescence microscopy has disclosed the non-uniform distribution of the rare-earth dopants. The depolarization effects have then been modeled and found to be best reproduced by taking the thickness non-uniformity as the main source of depolarization. The optical constants of the studied films have been determined after four-step modeling with sequential decrease of the mean square error. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. The Electronic Structures and Optical Properties of Alkaline-Earth Metals Doped Anatase TiO2: A Comparative Study of Screened Hybrid Functional and Generalized Gradient Approximation

    Directory of Open Access Journals (Sweden)

    Jin-Gang Ma

    2015-08-01

    Full Text Available Alkaline-earth metallic dopant can improve the performance of anatase TiO2 in photocatalysis and solar cells. Aiming to understand doping mechanisms, the dopant formation energies, electronic structures, and optical properties for Be, Mg, Ca, Sr, and Ba doped anatase TiO2 are investigated by using density functional theory calculations with the HSE06 and PBE functionals. By combining our results with those of previous studies, the HSE06 functional provides a better description of electronic structures. The calculated formation energies indicate that the substitution of a lattice Ti with an AEM atom is energetically favorable under O-rich growth conditions. The electronic structures suggest that, AEM dopants shift the valence bands (VBs to higher energy, and the dopant-state energies for the cases of Ca, Sr, and Ba are quite higher than Fermi levels, while the Be and Mg dopants result into the spin polarized gap states near the top of VBs. The components of VBs and dopant-states support that the AEM dopants are active in inter-band transitions with lower energy excitations. As to optical properties, Ca/Sr/Ba are more effective than Be/Mg to enhance absorbance in visible region, but the Be/Mg are superior to Ca/Sr/Ba for the absorbance improvement in near-IR region.

  1. Efficient Dual-Modal NIR-to-NIR Emission of Rare Earth Ions Co-doped Nanocrystals for Biological Fluorescence Imaging.

    Science.gov (United States)

    Zhou, Jiajia; Shirahata, Naoto; Sun, Hong-Tao; Ghosh, Batu; Ogawara, Makoto; Teng, Yu; Zhou, Shifeng; Sa Chu, Rong Gui; Fujii, Minoru; Qiu, Jianrong

    2013-02-07

    A novel approach has been developed for the realization of efficient near-infrared to near-infrared (NIR-to-NIR) upconversion and down-shifting emission in nanophosphors. The efficient dual-modal NIR-to-NIR emission is realized in a β-NaGdF4/Nd(3+)@NaGdF4/Tm(3+)-Yb(3+) core-shell nanocrystal by careful control of the identity and concentration of the doped rare earth (RE) ion species and by manipulation of the spatial distributions of these RE ions. The photoluminescence results reveal that the emission efficiency increases at least 2-fold when comparing the materials synthesized in this study with those synthesized through traditional approaches. Hence, these core-shell structured nanocrystals with novel excitation and emission behaviors enable us to obtain tissue fluorescence imaging by detecting the upconverted and down-shifted photoluminescence from Tm(3+) and Nd(3+) ions, respectively. The reported approach thus provides a new route for the realization of high-yield emission from RE ion doped nanocrystals, which could prove to be useful for the design of optical materials containing other optically active centers.

  2. Rare-earth doped YF{sub 3} nanocrystals embedded in sol-gel silica glass matrix for white light generation

    Energy Technology Data Exchange (ETDEWEB)

    Mendez-Ramos, J. [Departamento Fisica Fundamental y Experimental, Electronica y Sistemas, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain); Santana-Alonso, A. [Departamento Fisica Basica, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain); Yanes, A.C., E-mail: ayanesh@ull.e [Departamento Fisica Basica, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain); Castillo, J. del [Departamento Fisica Basica, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain); Rodriguez, V.D. [Departamento Fisica Fundamental y Experimental, Electronica y Sistemas, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain)

    2010-12-15

    YF{sub 3} nanocrystals triply-doped with Yb{sup 3+}, Ho{sup 3+} and Tm{sup 3+} ions embedded in amorphous silica matrix have been successfully obtained by heat treatment of precursor sol-gel glasses for the first time to our knowledge and confirmed by X-ray diffraction and luminescence measurements. Simultaneous UV and visible efficient up-conversion emissions, with well-resolved Stark structure, under 980 nm infrared pump are observed, indicating the effective partition of rare-earth ions into a crystalline-like environment of the YF{sub 3} nanocrystals. Corresponding energy transfer mechanisms have been analyzed and overall colour emission has been quantified in terms of standard chromaticity diagram. By an adequate doping level and heat treatment temperature of precursor sol-gel glasses, a bright white colour has been accomplished, close to the standard equal energy white light illumination point, with potential applications in photo-electronic devices and information processing.

  3. Analysis of doping concentration and composition in wide bandgap AlGaN:Si by wavelength dispersive x-ray spectroscopy

    Science.gov (United States)

    Kusch, Gunnar; Mehnke, Frank; Enslin, Johannes; Edwards, Paul R.; Wernicke, Tim; Kneissl, Michael; Martin, Robert W.

    2017-03-01

    Detailed knowledge of the dopant concentration and composition of wide band gap Al x Ga{}1-x{{N}} layers is of crucial importance for the fabrication of ultra violet light emitting diodes. This paper demonstrates the capabilities of wavelength dispersive x-ray (WDX) spectroscopy in accurately determining these parameters and compares the results with those from high resolution x-ray diffraction (HR-XRD) and secondary ion mass spectrometry (SIMS). WDX spectroscopy has been carried out on different silicon-doped wide bandgap Al x Ga{}1-x{{N}} samples (x between 0.80 and 1). This study found a linear increase in the Si concentration with the SiH4/group-III ratio, measuring Si concentrations between 3× {10}18 cm‑3 and 2.8× {10}19 cm‑3, while no direct correlation between the AlN composition and the Si incorporation ratio was found. Comparison between the composition obtained by WDX and by HR-XRD showed very good agreement in the range investigated, while comparison of the donor concentration between WDX and SIMS found only partial agreement, which we attribute to a number of effects.

  4. Thermoluminescence investigations of sol–gel derived and γ-irradiated rare earth (Eu and Nd) doped YAG nanophosphors

    Energy Technology Data Exchange (ETDEWEB)

    Kurrey, M.S. [Department of Applied Physics, Government Engineering College, Bilaspur 495006 (India); Tiwari, Ashish, E-mail: ashisht048@gmail.com [Department of Chemistry, Government Lahiri College, Chirimiri 497449 (India); Khokhar, M.S.K. [Department of Rural Technology, Guru Ghasidas Vishwavidyalaya, Bilaspur 495006 (India); Kher, R.S. [Department of Physics, Government E.R.R. PG Science College, Bilaspur 495006 (India); Dhoble, S.J. [Department of Physics, RTM Nagpur University, Nagpur 440033 (India)

    2015-08-15

    Nanocrystalline YAG doped with Eu{sup 3+} and Nd{sup 3+} has been synthesized by a sol–gel technique. The prepared nanophosphors were calcined and characterized by XRD, SEM. The XRD analysis revealed well-defined cubic phase. Electron microscopy showed spherical morphologies with an average size of 15–20 nm. The thermoluminescence (TL) properties of as prepared nanophosphors were investigated after γ-irradiation using {sup 60}Co source at room temperature. It has been found that there is a prominent TL glow peak at 290–295 °C for the as prepared doped samples. The TL glow curve showed variation in TL peak intensity as the concentration of dopant is changed. Kinetic data and trap depth for the synthesized samples were calculated by a peak shape method. It has been found that TL response is nonlinear in the range 0.29–1.16 kGy. This paper discusses about the optimal doping concentration of Eu and Nd in YAG nanophosphors. - Highlights: • TL properties of YAG:Eu{sup 3+}/Nd{sup 3+} nanoparticles were investigated after γ-irradiation. • TL peak intensity and glow curve structure varies with concentration of dopant. • Optimal TL intensity was obtained for YAG:Eu{sub 3.0}. and YAG:Nd{sub 3.0}. • Blue-shift in the TL peaks was observed as the gamma dose is increased for YAG:Eu{sub 5.0}. • TL response was found to be nonlinear in the range 0.29–1.16 kGy.

  5. Temperature and frequency dependence of transport phenomena in co-doped rare earth oxides nanoparticles for ITSOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, A. [Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Park Road, Islamabad 44000 (Pakistan); School of Science and Technology, University of Management and Technology, Sialkot Campus, Shahabpura Road, Sialkot 51310 (Pakistan); Saleemi, A.S. [Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Park Road, Islamabad 44000 (Pakistan); Anis-ur-Rehman, M., E-mail: marehman@comsats.edu.pk [Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Park Road, Islamabad 44000 (Pakistan)

    2015-05-25

    Highlights: • Phase pure ceria (Gd–La and Gd–Nd co-doped) as electrolytes for fuel cells. • Facile synthesis is done with composite mediated hydrothermal method. • Significant variation in transport properties with doping concentration is observed. • The Raman spectra confirmed the targeted doping and increase of vacancy sites. • Maximum conductivity achieved was 1.78 S cm{sup −1} for Ce{sub 0.5}Gd{sub 0.25}Nd{sub 0.25}O{sub δ} at 600 °C. - Abstract: The present study is focused on the conductivity enhancement of the doped ceria. Composite mediated hydrothermal method (CMHM) was employed to produce the material. X-ray diffraction was used to determine phase of nanocrystalline Ce{sub 1−2x}Gd{sub x}La{sub x}O{sub δ} and Ce{sub 1−2x}Gd{sub x}Nd{sub x}O{sub δ} (x = 0.1, 0.25). Conduction mechanism (dc conductivity and ac conductivity) in prepared samples was observed as a function of temperature and frequency. DC conductivity was measured in temperature range 300–700 °C. AC conductivity was measured in frequency range 1 kHz to 3 MHz at temperatures 300, 400, 500, 600, and 700 °C. The enhancement in conductivity was observed due to availability of oxygen vacancy sites which was dependent on composition. The Raman measurements supported the electrical conductivity results and more vacancy sites were observed in Raman spectrum in samples which showed maximum conductivities. The maximum conductivity achieved was 1.78 S cm{sup −1} (at 600 °C) for Ce{sub 0.5}Gd{sub 0.25}Nd{sub 0.25}O{sub δ}, which is quite a higher value in these compounds. This made this material a potential candidate for its use as an electrolyte material for Intermediate Temperature Solid Oxide Fuel Cells (ITSOFCs)

  6. Photon management properties of rare-earth (Nd,Yb,Sm)-doped CeO2 films prepared by pulsed laser deposition.

    Science.gov (United States)

    Balestrieri, Matteo; Colis, Silviu; Gallart, Mathieu; Schmerber, Guy; Bazylewski, Paul; Chang, Gap Soo; Ziegler, Marc; Gilliot, Pierre; Slaoui, Abdelilah; Dinia, Aziz

    2016-01-28

    CeO2 is a promising material for applications in optoelectronics and photovoltaics due to its large band gap and values of the refractive index and lattice parameters, which are suitable for silicon-based devices. In this study, we show that trivalent Sm, Nd and Yb ions can be successfully inserted and optically activated in CeO2 films grown at a relatively low deposition temperature (400 °C), which is compatible with inorganic photovoltaics. CeO2 thin films can therefore be efficiently functionalized with photon-management properties by doping with trivalent rare earth (RE) ions. Structural and optical analyses provide details of the electronic level structure of the films and of their energy transfer mechanisms. In particular, we give evidence of the existence of an absorption band centered at 350 nm from which energy transfer to rare earth ions occurs. The transfer mechanisms can be completely explained only by considering the spontaneous migration of Ce(3+) ions in CeO2 at a short distance from the RE(3+) ions. The strong absorption cross section of the f-d transitions in Ce(3+) ions efficiently intercepts the UV photons of the solar spectrum and therefore strongly increases the potential of these layers as downshifters and downconverters.

  7. Effect of rare-earth (La and Eu) doping on ferroelectric and magnetic properties of magnetoelectric Pb(Fe{sub 0.5}Nb{sub 0.5})O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Venkata Ramana, E.; Graca, M.P.F.; Valente, M.A. [I3N-Aveiro, Department of Physics, University of Aveiro, Aveiro, 3810-193 (Portugal)

    2014-09-15

    Polycrystalline Pb(Fe{sub 0.5}Nb{sub 0.5})O{sub 3} (PFN) samples have been synthesized to study the effect of rare-earth ions, La and Eu, on multiferroic physical properties. The synthesis of materials in controlled PbO atmosphere accounted for the pyrochlore free ceramics with tetragonal structure. Small amount (1 at.%) of rare-earth doping resulted in a shrinkage of unit cell volume. The dielectric studies indicated a decrease in phase transition temperature from 375 K to 356 K for La doped ceramics. A well-saturated ferroelectric polarization with a remanent polarization of 8.9 μC/cm{sup 2} was observed for undoped PFN while the doping affected in the large leakage current and higher coercivity. We observed no significant effect of doping on magnetic transition temperatures at low temperatures. Doping with La resulted in reduced magnetoelectric coefficient compared to the undoped value of 9.2 mV/cmOe, due to the poor poling ability. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. New in-flight calibration adjustment of the Nimbus 6 and 7 earth radiation budget wide field of view radiometers

    Science.gov (United States)

    Kyle, H. L.; House, F. B.; Ardanuy, P. E.; Jacobowitz, H.; Maschhoff, R. H.; Hickey, J. R.

    1984-01-01

    In-flight calibration adjustments are developed to process data obtained from the wide-field-of-view channels of Nimbus-6 and Nimbus-7 after the failure of the Nimbus-7 longwave scanner on June 22, 1980. The sensor characteristics are investigated; the satellite environment is examined in detail; and algorithms are constructed to correct for long-term sensor-response changes, on/off-cycle thermal transients, and filter-dome absorption of longwave radiation. Data and results are presented in graphs and tables, including comparisons of the old and new algorithms.

  9. E ective Doping of Rare-earth Ionsin Silica Gel:A Novel Approach to Design Active Electronic Devices

    Institute of Scientific and Technical Information of China (English)

    D. Haranath∗; Savvi Mishra; Amish G. Joshi; Sonal Sahai; Virendra Shanker

    2011-01-01

    Eu3+luminescence spectroscopy has been used to investigate the effective doping of alkoxide-based silica (SiO2) gels using a novel pressure-assisted sol-gel method. Our results pertaining to intense photolumi-nescence (PL) from gel nanospheres can be directly attributed to the high specific surface area and remarkable decrease in unsaturated dangling bonds of the gel nanospheres under pressure. An increased dehydroxylation in an autoclave resulted in enhanced red (∼611 nm) PL emission from europium and is almost ten times brighter than the SiO2 gel made at atmospheric pressure and∼50℃ using conventional St¨ober-Fink-Bohn process. The presented results are entirely different from those reported earlier for SiO2:Eu3+ gel nanospheres and the origin of the enhanced PL have been discussed thoroughly.

  10. Promotion of redox and stability features of doped Ce-W-Ti for NH3-SCR reaction over a wide temperature range

    Science.gov (United States)

    Zhao, Kun; Han, Weiliang; Lu, Gongxuan; Lu, Jiangyin; Tang, Zhicheng; Zhen, Xinping

    2016-08-01

    In this study, transition metals Co, Mn, and Cu were introduced into a Ce-W-Ti catalyst to promote low-temperature catalytic activity. Among these metal-modified M/Ce-W-Ti catalysts (M represents Co, Mn, or Cu), the Cu/Ce-W-Ti catalyst with an optimized Cu content of 5 wt.% exhibited more than 90% conversion of nitrogen oxide (NOx) in the selective catalytic reduction by NH3 over a wide temperature range (260-400 °C). This catalyst likewise exhibited higher resistance to SO2 gas and water vapor under severe test conditions. On the basis of the characterization results by powder X-ray diffraction and X-ray photoelectron spectroscopy, we concluded that the superior catalytic properties of the Cu/Ce-W-Ti catalyst could be attributed to the highly dispersed Cu species, which increased the contents of Ce3+ species and adsorbed oxygen species in the catalysts. In addition, the NH3 temperature-programmed desorption results demonstrated that the Cu species doped into the Ce-W-Ti catalysts optimized surface acid content.

  11. Antenna Effect on the Organic Spacer-Modified Eu-Doped Layered Gadolinium Hydroxide for the Detection of Vanadate Ions over a Wide pH Range.

    Science.gov (United States)

    Jeong, Heejin; Lee, Byung-Il; Byeon, Song-Ho

    2016-05-04

    The excitation of the adsorbed vanadate group led to the red emission arising from the efficient energy transfer to Eu-doped layered gadolinium hydroxide (LGdH:Eu). This light-harvesting antenna effect allowed LGdH:Eu to detect selectively a vanadate in aqueous solution at different pHs. Because vanadate exists in various forms by extensive oligomerization and protonation reactions in aqueous solution depending on pH, it is important to detect a vanadate regardless of its form over a wide pH range. In particular, spacer molecules with long alkyl chains greatly facilitated access of a vanadate antenna into the interlayer surface of LGdH:Eu. The concomitant increase in adsorption capacity of LGdH:Eu achieved a strong antenna effect of vanadate on the red emission from Eu(3+). When a suspension containing LGdH:Eu nanosheets (1.0 g/L) was used, the vanadate concentration down to 1 × 10(-5) M could even be visually monitored, and the detection limit based on the (5)D0 → (7)F2 emission intensity could reach 4.5 × 10(-8) M.

  12. 添加稀土Gd的氧化锆的物相分析%Phase analysis of rare earth Gd doping ZrO2

    Institute of Scientific and Technical Information of China (English)

    刘树信; 王海滨

    2011-01-01

    以硝酸锆、硝酸钆和柠檬酸为原料,按n(Gd):n(Zr)分别为1:99、3:97、5:95、8:92和10:90的配比在1 200℃煅烧6h制备了稀土Gd掺杂ZrO2试样,以研究Gd与ZrO2的化学相容性;进而按n(Gd2Zr2O7):n(ZrO2)分别为1:10、1:8、1:4、1:2、1:1、4:1和8:1的配比于1 200℃煅烧6h原位合成了Gd2 Zr2O7-ZrO2复合材料.采用XRD和拉曼光谱研究了稀土Gd掺杂ZrO2和Gd2 Zr2O7-ZrO2复合材料的物相组成和结构.结果表明:稀土Gd容易进入ZrO2晶格形成固溶体,当稀土Gd掺杂量较少时,随着稀土Gd掺杂量的增加,m-ZrO2逐渐转变为t-ZrO2;当稀土Gd添加量较多时,随着Gd量的增加,逐渐原位生成了萤石结构的稀土锆酸盐Gd2Zr2O7,从而合成了由Gd2 Zr2O7和t-ZrO2构成的Gd2 Zr2 O7 - ZrO2复合材料.%Rare earth Gd doping ZrO2 specimens were prepared using Zr(NO3)4 · 3H2O,Gd(NO3)3 · 6H2O and C6H8O7 · H2O as starting materials according to the molar ratio of Gd and Zr (1:99,3:97,5:95,8=92,10:90) and firing at 1 200 °C for 6 h for studying chemical compatibility of Gd and ZrO2,and then Gd2Zr207-Zr02 composites were in-situ fired at 1 200 °C for 6 h according to the molar ratio of Gd2Zr207 and ZrO2(1= 10, 1:8,1 : 4,1:2,1 : 1,4:1,8:1). The phase composition and structure of the composites were studied by XRD and Raman. The results indicate that it is easy for Gd to enter crystal lattice of ZrO2 forming solid solution; when the doping amount of Gd is less, the m-ZrO2 transforms into t-ZrO2 with the increase of doping amount of Gd;when the doping amount of Gd is more,the fluorite-structured Gd2Zr2O7 forms gradually with the increase of doping amount of Gd,so the Gd2Zr207-ZrO2 composite composed of fluorite-structured Gd2Zr2O7 and t-ZrO2 is synthesized.

  13. Promotion of redox and stability features of doped Ce–W–Ti for NH{sub 3}-SCR reaction over a wide temperature range

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Kun [State Key Laboratory for Oxo Synthesis and Selective Oxidation, National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key laboratory of Oil & Gas Fine Chemical, Ministry of Education, College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Han, Weiliang; Lu, Gongxuan [State Key Laboratory for Oxo Synthesis and Selective Oxidation, National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Lu, Jiangyin, E-mail: jiangyinlu6410@163.com [Key laboratory of Oil & Gas Fine Chemical, Ministry of Education, College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Tang, Zhicheng, E-mail: tangzhicheng@licp.cas.cn [State Key Laboratory for Oxo Synthesis and Selective Oxidation, National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhen, Xinping [Key laboratory of Oil & Gas Fine Chemical, Ministry of Education, College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China)

    2016-08-30

    Graphical abstract: In this study, different transition metals were introduced into Ce–W–Ti catalyst in order to promote the low temperature activity. The Cu/Ce–W–Ti catalyst prepared via a co-precipitation method displayed more excellent performance in the wide temperature range (260–400 °C). - Highlights: • Redox ability of Ce–W–Ti was enhanced by introduction of CuO. • The optimum catalyst provided high activity and broad operation window. • Cu/Ce–W–Ti presents an adequate tolerance to SO{sub 2} and hydrothermal aging. - Abstract: In this study, transition metals Co, Mn, and Cu were introduced into a Ce–W–Ti catalyst to promote low-temperature catalytic activity. Among these metal-modified M/Ce–W–Ti catalysts (M represents Co, Mn, or Cu), the Cu/Ce–W–Ti catalyst with an optimized Cu content of 5 wt.% exhibited more than 90% conversion of nitrogen oxide (NO{sub x}) in the selective catalytic reduction by NH{sub 3} over a wide temperature range (260–400 °C). This catalyst likewise exhibited higher resistance to SO{sub 2} gas and water vapor under severe test conditions. On the basis of the characterization results by powder X-ray diffraction and X-ray photoelectron spectroscopy, we concluded that the superior catalytic properties of the Cu/Ce–W–Ti catalyst could be attributed to the highly dispersed Cu species, which increased the contents of Ce{sup 3+} species and adsorbed oxygen species in the catalysts. In addition, the NH{sub 3} temperature-programmed desorption results demonstrated that the Cu species doped into the Ce–W–Ti catalysts optimized surface acid content.

  14. Superconductivity by rare earth doping in the 1038-type compounds (Ca1-xREx) 10(FeAs)10(Pt3As8) with RE=Y, La-Nd, Sm-Lu

    Science.gov (United States)

    Stürzer, Tobias; Derondeau, Gerald; Bertschler, Eva-Maria; Johrendt, Dirk

    2015-01-01

    We report superconductivity in polycrystalline samples of the 1038-type compounds (Ca1-xREx) 10(FeAs)10(Pt3As8) up to Tc=35 K with RE=Y, La-Nd, Sm, Gd-Lu. The critical temperatures are nearly independent of the trivalent rare earth element used, yielding a common Tc(xRE) phase diagram for electron doping in all these systems. The absence of superconductivity in Eu2+ doped samples, as well as the close resemblance of (Ca1-xREx) 10(FeAs)10(Pt3As8) to the 1048 compound substantiate that the electron doping scenario in the RE-1038 and 1048 phases is analogous to other iron-based superconductors with simpler crystal structures.

  15. Fast synthesis of rare-earth (Pr{sup 3+}, Sm{sup 3+}, Eu{sup 3+} and Gd{sup 3+}) doped bismuth ferrite powders with enhanced magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Iorgu, A.I. [Department of Chemical Thermodynamics, “Ilie Murgulescu” Institute of Physical Chemistry, 060021 Bucharest (Romania); Department of Inorganic Chemistry, Physical Chemistry and Electrochemistry, University “Politehnica” of Bucharest, 011061 Bucharest (Romania); Maxim, F., E-mail: fmaxim@icf.ro [Department of Chemical Thermodynamics, “Ilie Murgulescu” Institute of Physical Chemistry, 060021 Bucharest (Romania); Matei, C. [Department of Inorganic Chemistry, Physical Chemistry and Electrochemistry, University “Politehnica” of Bucharest, 011061 Bucharest (Romania); Ferreira, Liliana Pires [Centro de Física da Matéria Condensada, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Department of Physics, University of Coimbra, 3004-516 Coimbra (Portugal); Ferreira, P. [Department of Materials and Ceramics Engineering, CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Cruz, M.M. [Centro de Física da Matéria Condensada, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Berger, D., E-mail: danaberger01@yahoo.com [Department of Inorganic Chemistry, Physical Chemistry and Electrochemistry, University “Politehnica” of Bucharest, 011061 Bucharest (Romania)

    2015-04-25

    Highlights: • Synthesis of rare earth doped bismuth ferrite powders by combustion method. • SEM and TEM were used to investigate the morphology and size of particles. • Effect of Bi substitution with Pr, Sm, Eu and Gd on magnetic properties of powders. - Abstract: Rare-earth (Pr{sup 3+}, Sm{sup 3+}, Eu{sup 3+} and Gd{sup 3+}) doped bismuth ferrite powders were synthesized for the first time by solution combustion method, which is a fast soft chemistry route for obtaining oxide powders. The materials were investigated by X-ray diffraction, Raman spectroscopy, as well as scanning and transmission electron microscopy. A distortion from rhombohedral R3c symmetry, specific to pure bismuth ferrite, to orthorhombic symmetry was observed for all doped samples. The SEM analysis of pure and doped bismuth ferrite powders showed the formation of sintered grains, with faceted cuboids-shaped particles with different size and lower average dimension in the case of doped samples. Magnetic properties were analyzed using SQUID magnetometry, M–H hysteresis loops being measured at 10 K and 300 K. All studied pure and doped bismuth ferrite samples presented high susceptibility values for high magnetic fields indicating strong antiferromagnetic interactions, whereas the behavior at low magnetic field demonstrates the existence of ferromagnetic coupling. Compared to BiFeO{sub 3}, Bi{sub 0.9}RE{sub 0.1}FeO{sub 3} (RE = Pr, Sm, Eu and Gd) powders exhibit higher susceptibility, remanence and coercivity values, Bi{sub 0.9}Eu{sub 0.1}FeO{sub 3} sample displaying the highest remanence and coercivity at room temperature.

  16. Rare-Earth doped particles as dual-modality contrast agent for minimally-invasive luminescence and dual-wavelength photoacoustic imaging.

    Science.gov (United States)

    Sheng, Yang; Liao, Lun-De; Thakor, Nitish; Tan, Mei Chee

    2014-10-09

    Multi-modal imaging is an emerging area that integrates multiple imaging modalities to simultaneously capture visual information over many spatial scales. Complementary contrast agents need to be co-developed in order to achieve high resolution and contrast. In this work, we demonstrated that rare-earth doped particles (REDPs) can be employed as dual-modal imaging agents for both luminescence and photoacoustic (PA) imaging to achieve intrinsic high contrast, temporal and spatial resolution, reaching deeper depth. REDPs synthesized with different surfactants (citric acid, polyacrylic acid, ethylenediaminetetraacetic acid and sodium citrate) exhibit tunable emission properties and PA signal amplitudes. Amongst these samples, sodium citrate-modified REDPs showed the strongest PA signals. Furthermore, since REDPs have multiple absorption peaks, they offer a unique opportunity for multi-wavelength PA imaging (e.g. PA signals were measured using 520 and 975 nm excitations). The in vivo PA images around the cortical superior sagittal sinus (SSS) blood vessel captured with enhanced signal arising from REDPs demonstrated that in addition to be excellent luminescent probes, REDPs can also be used as successful PA contrast agents. Anisotropic polyacrylic acid-modified REDPs were found to be the best candidates for dual-modal luminescence and PA imaging due to their strong luminescence and PA signal intensities.

  17. Optical and electronic study on InAs quantum dots doped with rare earths; Optische und elektronische Untersuchung an mit Seltenen Erden dotierten InAs-Quantenpunkten

    Energy Technology Data Exchange (ETDEWEB)

    Greff, Markus Karlheinz

    2015-07-01

    In the framework of this thesis it was studied, how the optical and electronic properties of InAs quantum dots change by the implantation of ions form the group of the rare earths. For this photoluminescence measurements as well as C(V) measurements were performed on InAs quantum dots, which were doped with europium as well as erbium. The optical studies showed a new emission peak in the photoluminescence spectrum after the thermal annealing. By the ions brought in by means of ion implantation it came locally to lattice stresses and an accumulation of lattice defects on the interfaces of the quantum dots, which led to a diffusion strengthening, whereby it came during the thermal annealing both to a broadening of the quantum dots by the indium diffusion and to an increasement of the band gap by gallium diffusion into the quantum dot. Thereby a shift of the ground-state energy of up to 150 meV could be measured.

  18. Sintering effect on ageing behavior of rare earths (Pr6O11-Er2O3-Y2O3)-doped ZnO varistor ceramics

    Institute of Scientific and Technical Information of China (English)

    Choon-Woo Nahm

    2012-01-01

    The electrical properties and ageing behavior of the rare earths (Pr6O11-Er2O3-Y2O3)-doped ZnO varistor ceramics were systematically investigated at sintering temperature range of 1335-1350 ℃.With an increase in the sintering temperature,the sintered density increased from 5.41 to 5.64 g/cm3 and the average grain size increased from 5.8 to 7.9 μm.The varistor properties and ageing behavior were significantly affected by small sintering temperature range of 1335-1350 ℃.The breakdown field noticeably decreased from 5767 to 3628 V/cm with an increase in the sintering temperature.The varistor ceramics exhibited the highest nonlinear coefficient (43.2) at the sintering temperature of 1340 ℃.The varistor ceramics sintered at 1350 ℃ exhibited a surprisingly excellent stability by exhibiting 0.3% in the variation rate of the breakdown field and 0.3% in the variation rate of the nonlinear coefficient for ageing stress of 0.95 E1 mA/150 ℃/24 h.

  19. Furnace Cyclic Behavior of Plasma-Sprayed Zirconia-Yttria and Multi-Component Rare Earth Oxide Doped Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Nesbitt, James A.; McCue, Terry R.; Barrett, Charles A.; Miller, Robert A.

    2002-01-01

    Ceramic thermal barrier coatings will play an increasingly important role in advanced gas turbine engines because of their ability to enable further increases in engine temperatures. However, the coating performance and durability become a major concern under the increasingly harsh thermal cycling conditions. Advanced zirconia- and hafnia-based cluster oxide thermal barrier coatings with lower thermal conductivity and improved thermal stability are being developed using a high-heat-flux laser-rig based test approach. Although the new composition coatings were not yet optimized for cyclic durability, an initial durability screening of numerous candidate coating materials was carried out using conventional furnace cyclic tests. In this paper, furnace thermal cyclic behavior of the advanced plasma-sprayed zirconia-yttria-based thermal barrier coatings that were co-doped with multi-component rare earth oxides was investigated at 1163 C using 45 min hot cycles. The ceramic coating failure mechanisms were studied by using scanning electron microscopy combined with X-ray diffraction phase analysis after the furnace tests. The coating cyclic lifetime will be discussed in relation to coating phase structures, total dopant concentrations, and other properties.

  20. Dielectric and varistor properties of rare-earth-doped ZnO and CaCu3Ti4O12 composite ceramics

    Science.gov (United States)

    Lu, Huafei; Lin, Yuanhua; Yuan, Jiancong; Nan, Cewen; Chen, Kexin

    2013-02-01

    To investigate the multi-functional ceramics with both high permittivity and large nonlinear coefficient, we have prepared rare-earth Tb-and-Co doped ZnO and TiO2-rich CaCu3Ti4O12 (TCCTO) powders by chemical co-precipitation and sol-gel methods respectively, and then obtained the TCCTO/ZnO composite ceramics, sintered at 1100°C for 3 h in air. Analyzing the composite ceramics of the microstructure and phase composition indicated that the composite ceramics were composed of the main phases of ZnO and CaCu3Ti4O12 (CCTO). Our results revealed that the TCCTO/ZnO composite ceramics showed both high dielectric and good nonlinear electrical behaviors. The composite ceramic of TCCTO: ZnO = 0.3 exhibited a high dielectric constant of 210(1 kHz) with a nonlinear coefficient of 11. The dielectric behavior of TCCTO/ZnO composite could be explained by the mixture rule. With the high dielectric permittivity and tunable varistor behaviors, the composite ceramics has a potential application for the higher voltage transportation devices.

  1. Enhancement of Cerenkov luminescence imaging by dual excitation of Er(3+,Yb(3+-doped rare-earth microparticles.

    Directory of Open Access Journals (Sweden)

    Xiaowei Ma

    Full Text Available Cerenkov luminescence imaging (CLI has been successfully utilized in various fields of preclinical studies; however, CLI is challenging due to its weak luminescent intensity and insufficient penetration capability. Here, we report the design and synthesis of a type of rare-earth microparticles (REMPs, which can be dually excited by Cerenkov luminescence (CL resulting from the decay of radionuclides to enhance CLI in terms of intensity and penetration.Yb(3+- and Er(3+- codoped hexagonal NaYF4 hollow microtubes were synthesized via a hydrothermal route. The phase, morphology, and emission spectrum were confirmed for these REMPs by power X-ray diffraction (XRD, scanning electron microscopy (SEM, and spectrophotometry, respectively. A commercial CCD camera equipped with a series of optical filters was employed to quantify the intensity and spectrum of CLI from radionuclides. The enhancement of penetration was investigated by imaging studies of nylon phantoms and nude mouse pseudotumor models.the REMPs could be dually excited by CL at the wavelengths of 520 and 980 nm, and the emission peaks overlaid at 660 nm. This strategy approximately doubled the overall detectable intensity of CLI and extended its maximum penetration in nylon phantoms from 5 to 15 mm. The penetration study in living animals yielded similar results.this study demonstrated that CL can dually excite REMPs and that the overlaid emissions in the range of 660 nm could significantly enhance the penetration and intensity of CL. The proposed enhanced CLI strategy may have promising applications in the future.

  2. 稀土元素掺杂TiO2光催化性能的研究%Study on rare earth oxide doping on the phoyocatalytic activities of TiO2

    Institute of Scientific and Technical Information of China (English)

    计海峰; 张乃军; 王迪; 李忠玉; 王卫东

    2014-01-01

    Rare earth oxide (La3+、Ce3+) doping on the photocatalytic activities of TiO2 were compared by sol-gel method, and were characterized by XRD, SEM, EDS and IR. Photocatalytic degradation of methylene blue was studied by doping rare earth elements on the photocatalytic properties of TiO2. Result shows that photocatalytic activties of La3+ and Ce3+ - doping TiO2 is improved. Photocatalytic activties of La3+ and Ce3+-doping TiO2 are optimum at 400℃, and the best doped contents are 1.0% and 1.5%, respectively. After 0.5h light, both the degradation rate reached over 90%.%采用溶胶-凝胶法制备稀土元素(La3+、Ce3+)掺杂TiO2光催化剂,利用XRD、SEM、EDS、IR 进行表征,并以亚甲基蓝为光降解反应对象,进行光催化降解实验,考察了掺杂稀土元素对TiO2光催化性能的影响。结果表明:La3+和Ce3+掺杂TiO2使得光催化剂的活性提高;煅烧温度为400℃时,掺杂La3+和Ce3+的TiO2光催化活性分别最佳,最佳掺杂量分别为1.0%和1.5%;0.5h光照后,二者降解率均达到90%以上。

  3. Alkaline Earth Metal Zirconate Perovskites MZrO3 (M=Ba(2+), Sr(2+), Ca(2+)) Derived from Molecular Precursors and Doped with Eu(3+) Ions.

    Science.gov (United States)

    Drąg-Jarząbek, Anna; John, Łukasz; Petrus, Rafał; Kosińska-Klähn, Magdalena; Sobota, Piotr

    2016-03-24

    The effect of alkaline earth metal alkoxides on the protonation of zirconocene dichloride was investigated. This approach enabled the design of compounds with preset molecular structures for generating high-purity binary metal oxide perovskites MZrO3 (M=Ba(2+), Sr(2+), Ca(2+)). Single-source molecular precursors [Ba4 Zr2 (μ6 -O)(μ3 ,η(2)-OR)8 (OR)2(η(2) -HOR)2 (HOR)2 Cl4], [Sr4 Zr2 (μ6 -O)(μ3 ,η(2)-OR)8 (OR)2 (HOR)4 Cl4], [Ca4 Zr2 (μ6-O)(μ3 ,η(2)-OR)8 (OR)2 Cl4], and [Ca6 Zr2 (μ2 ,η(2)-OR)12 (μ-Cl)2 (η(2) -HOR)4 Cl6 ]⋅8 CH2 Cl2 were prepared via elimination of the cyclopentadienyl ring from Cp2 ZrCl2 as CpH in the presence of M(OR)2 and alcohol ROH (ROH=CH3OCH2 CH2OH) as a source of protons. The resulting complexes were characterized by elemental analysis, IR and NMR spectroscopy, and single-crystal X-ray diffraction. The compounds were then thermally decomposed to MCl2 /MZrO3 mixtures. Leaching of MCl2 from the raw powder with deionized water produced highly pure perovskite-like oxide particles of 40-80 nm in size. Luminescence studies on Eu(3+)-doped MZrO3 revealed that the perovskites are attractive host lattices for potential applications in display technology.

  4. NEW ERBIUM DOPED ANTIMONY GLASSES FOR LASER AND GLASS AMPLIFICATION

    Directory of Open Access Journals (Sweden)

    B. Tioua

    2015-07-01

    Full Text Available Because of the special spectroscopic properties of the rare earth ions, rare earth doped glasses are widely used in bulk and fiber lasers or amplifiers. The modelling of lasers and searching for new laser transitions require a precise knowledge of the spectroscopic properties of rare earth ions in different host glasses. In this poster will offer new doped erbium glasses synthesized in silicate crucibles were obtained in the combination Sb2O3-WO3-Na2O. Several properties are measured and correlated with glass compositions. The absorption spectral studies have been performed for erbium doped glasses. The intensities of various absorption bands of the doped glasses are measured and the Judd-Ofelt parameters have been computed. From the theory of Judd-Ofelt, various radiative properties, such as transition probability, branching ratio and radiative life time for various emission levels of these doped glasses have been determined and reported. These results confirm the ability of antimony glasses for glass amplification.

  5. NEW ERBIUM DOPED ANTIMONY GLASSES FOR LASER AND GLASS AMPLIFICATIONmplification

    Directory of Open Access Journals (Sweden)

    B. Tioua

    2012-06-01

    Full Text Available Because of the special spectroscopic properties of the rare earth ions, rare earth doped glasses are widely used in bulk and fiber lasers or amplifiers. The modelling of lasers and searching for new laser transitions require a precise knowledge of the spectroscopic properties of rare earth ions in different host glasses. in this poster will offer new doped erbium glasses synthesized in silicate crucibles were obtained in the combination Sb2O3-WO3-Na2O. Several properties are measured and correlated with glass compositions. The absorption spectral studies have been performed for erbium doped glasses. The intensities of various absorption bands of the doped glasses are measured and the Judd-Ofelt parameters have been computed. From the theory of Judd-Ofelt, various radiative properties, such as transition probability, branching ratio and radiative life time for various emission levels of these doped glasses have been determined and reported. These results confirm the ability of antimony glasses for glass amplification.

  6. THE FLAT TRANSMISSION SPECTRUM OF THE SUPER-EARTH GJ1214b FROM WIDE FIELD CAMERA 3 ON THE HUBBLE SPACE TELESCOPE

    Energy Technology Data Exchange (ETDEWEB)

    Berta, Zachory K.; Charbonneau, David; Desert, Jean-Michel; Irwin, Jonathan [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Miller-Ricci Kempton, Eliza; Fortney, Jonathan J.; Nutzman, Philip [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); McCullough, Peter R. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Burke, Christopher J. [SETI Institute/NASA Ames Research Center, M/S 244-30, Moffett Field, CA 94035 (United States); Homeier, Derek, E-mail: zberta@cfa.harvard.edu [Centre de Recherche Astrophysique de Lyon, UMR 5574, CNRS, Universite de Lyon, Ecole Normale Superieure de Lyon, F-69364 Lyon Cedex 07 (France)

    2012-03-01

    Capitalizing on the observational advantage offered by its tiny M dwarf host, we present Hubble Space Telescope/Wide Field Camera 3 (WFC3) grism measurements of the transmission spectrum of the super-Earth exoplanet GJ1214b. These are the first published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, finding the transmission spectrum of GJ1214b to be flat between 1.1 and 1.7 {mu}m. Inconsistent with a cloud-free solar composition atmosphere at 8.2{sigma}, the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b's outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the flat transmission spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching 1 {mu}m in diameter.

  7. Rare-earth-ion-doped ultra-narrow-linewidth lasers on a silicon chip and applications to intra-laser-cavity optical sensing

    NARCIS (Netherlands)

    Bernhardi, Edward; de Ridder, R.M.; Worhoff, Kerstin; Pollnau, Markus

    We report on diode-pumped distributed-feedback (DFB) and distributed-Bragg-reflector (DBR) channel waveguide lasers in Er-doped and Yb-doped Al2O3 on standard thermally oxidized silicon substrates. Uniform surface-relief Bragg gratings were patterned by laser-interference lithography and etched into

  8. Rare-earth-ion-doped ultra-narrow-linewidth lasers on a silicon chip and applications to intra-laser-cavity optical sensing

    NARCIS (Netherlands)

    Bernhardi, E.H.; Ridder, de R.M.; Wörhoff, K.; Pollnau, M.

    2013-01-01

    We report on diode-pumped distributed-feedback (DFB) and distributed-Bragg-reflector (DBR) channel waveguide lasers in Er-doped and Yb-doped Al2O3 on standard thermally oxidized silicon substrates. Uniform surface-relief Bragg gratings were patterned by laser-interference lithography and etched into

  9. Calibration on wide-ranging aluminum doping concentrations by photoluminescence in high-quality uncompensated p-type 4H-SiC

    Science.gov (United States)

    Asada, Satoshi; Kimoto, Tsunenobu; Ivanov, Ivan G.

    2017-08-01

    Previous work has shown that the concentration of shallow dopants in a semiconductor can be estimated from the photoluminescence (PL) spectrum by comparing the intensity of the bound-to-the-dopant exciton emission to that of the free exciton. In this work, we study the low-temperature PL of high-quality uncompensated Al-doped p-type 4H-SiC and propose algorithms for determining the Al-doping concentration using the ratio of the Al-bound to free-exciton emission. We use three different cryogenic temperatures (2, 41, and 79 K) in order to cover the Al-doping range from mid 1014 cm-3 up to 1018 cm-3. The Al-bound exciton no-phonon lines and the strongest free-exciton replica are used as a measure of the bound- and free-exciton emissions at a given temperature, and clear linear relationships are obtained between their ratio and the Al-concentration at 2, 41, and 79 K. Since nitrogen is a common unintentional donor dopant in SiC, we also discuss the criteria allowing one to determine from the PL spectra whether a sample can be considered as uncompensated or not. Thus, the low-temperature PL provides a convenient non-destructive tool for the evaluation of the Al concentration in 4H-SiC, which probes the concentration locally and, therefore, can also be used for mapping the doping homogeneity.

  10. Thermally deposited Ag-doped CdS thin film transistors with high-k rare-earth oxide Nd{sub 2}O{sub 3} as gate dielectric

    Energy Technology Data Exchange (ETDEWEB)

    Gogoi, P., E-mail: paragjyoti_g@rediffmail.com [Sibsagar College, Material Science Laboratory, Department of Physics (India)

    2013-03-15

    The performance of thermally deposited CdS thin film transistors doped with Ag has been reported. Ag-doped CdS thin films have been prepared using chemical method. High dielectric constant rare earth oxide Nd{sub 2}O{sub 3} has been used as gate insulator. The thin film trasistors are fabricated in coplanar electrode structure on ultrasonically cleaned glass substrates with a channel length of 50 {mu}m. The thin film transistors exhibit a high mobility of 4.3 cm{sup 2} V{sup -1} s{sup -1} and low threshold voltage of 1 V. The ON-OFF ratio of the thin film transistors is found as 10{sup 5}. The TFTs also exhibit good transconductance and gain band-width product of 1.15 Multiplication-Sign 10{sup -3} mho and 71 kHz respectively.

  11. Enhancing photovoltaic performance of dye-sensitized solar cell by rare-earth doped oxide of Lu{sub 2}O{sub 3}:(Tm{sup 3+}, Yb{sup 3+})

    Energy Technology Data Exchange (ETDEWEB)

    Li Qingbei; Lin Jianming [Engineering Research Center of Environment-Friendly Functional Materials, Ministry of Education, Institute of Material Physical Chemistry, Huaqiao University, Quanzhou 362021 (China); Wu Jihuai, E-mail: jhwu@hqu.edu.cn [Engineering Research Center of Environment-Friendly Functional Materials, Ministry of Education, Institute of Material Physical Chemistry, Huaqiao University, Quanzhou 362021 (China); Lan Zhang; Wang Yue; Peng Fuguo; Huang Miaoliang [Engineering Research Center of Environment-Friendly Functional Materials, Ministry of Education, Institute of Material Physical Chemistry, Huaqiao University, Quanzhou 362021 (China)

    2011-05-30

    Highlights: > Tm{sup 3+}/Yb{sup 3+} codoped oxide is introduced into the TiO{sub 2} film in dye-sensitized solar cell. > The RE improves light harvest via conversion luminescence and increases photocurrent. > The RE elevates the oxide film energy level and increases the cell photovoltage. > The cell efficiency is increased by 11.1% compared to the cell lacking of RE doping. - Abstract: In order to increase of the photocurrent, photovoltage and energy conversion efficiency of dye-sensitized solar cell (DSSC), rare-earth doped oxide of Lu{sub 2}O{sub 3}:(Tm{sup 3+}, Yb{sup 3+}) is prepared and introduced into the TiO{sub 2} film in the DSSC. As a luminescence medium, Lu{sub 2}O{sub 3}:(Tm{sup 3+}, Yb{sup 3+}) improves incident light harvest via a conversion luminescence process and increases photocurrent; as a p-type dopant, the rare-earth ions elevate the energy level of the oxide film and increase the photovoltage. Under a simulated solar light irradiation of 100 mW cm{sup -2}, the light-to-electric energy conversion efficiency of the DSSC with Lu{sub 2}O{sub 3}:(Tm{sup 3+}, Yb{sup 3+}) doping reaches 6.63%, which is increased by 11.1% compared to the DSSC without Lu{sub 2}O{sub 3}:(Tm{sup 3+}, Yb{sup 3+}) doping.

  12. Techniques for computing regional radiant emittances of the earth-atmosphere system from observations by wide-angle satellite radiometers, phase 3

    Science.gov (United States)

    Pina, J. F.; House, F. B.

    1975-01-01

    Radiometers on earth orbiting satellites measure the exchange of radiant energy between the earth-atmosphere (E-A) system and space at observation points in space external to the E-A system. Observations by wideangle, spherical and flat radiometers are analyzed and interpreted with regard to the general problem of the earth energy budget (EEB) and to the problem of determining the energy budget of regions smaller than the field of view (FOV) of these radiometers.

  13. Luminescence and photo-thermally stimulated defects creation processes in PbWO{sub 4} crystals doped with trivalent rare-earth ions

    Energy Technology Data Exchange (ETDEWEB)

    Fabeni, P. [Institute of Applied Physics “N.Carrara” (IFAC) of CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Firenze) (Italy); Krasnikov, A.; Kärner, T. [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Laguta, V.V.; Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Pazzi, G.P. [Institute of Applied Physics “N.Carrara” (IFAC) of CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Firenze) (Italy); Zazubovich, S., E-mail: svet@fi.tartu.ee [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia)

    2013-04-15

    In PbWO{sub 4} crystals, doped with various trivalent rare-earth A{sup 3+} ions (A{sup 3+}: La{sup 3+}, Lu{sup 3+}, Y{sup 3+}, Ce{sup 3+}, Gd{sup 3+}), electron (WO{sub 4}){sup 3−} and {(WO_4)"3"−–A"3"+} centers can be created under UV irradiation not only in the host absorption region but also in the energy range around 3.85 eV (Böhm et al., 1999; Krasnikov et al., 2010). Under excitation in the same energy range, the UV emission peak at 3.05–3.20 eV is observed. In the present work, the origin of this emission is investigated in detail by low-temperature time-resolved luminescence methods. Photo-thermally stimulated creation of (WO{sub 4}){sup 3−} and {(WO_4)"3"−–A"3"+} centers is studied also in PbWO{sub 4}:Mo,A{sup 3+} crystals. Various processes, which could explain both the appearance of the UV emission and the creation of the {(WO_4)"3"−–A"3"+}-type centers under irradiation of PbWO{sub 4}: A{sup 3+} crystals in the 3.85±0.35 eV energy range, are discussed. The radiative and non-radiative decay of the excitons localized near A{sup 3+} ions is considered as the most probable mechanism to explain the observed features. -- Highlights: ► UV emission of PbWO{sub 4}: A{sup 3+} (A{sup 3+}: La{sup 3+}, Lu{sup 3+}, Y{sup 3+}, Ce{sup 3+}, and Gd{sup 3+}) crystals is studied. ► The emission is ascribed to the radiative decay of excitons localized near A{sup 3+} ions. ► The excitons are created at 3.85 eV excitation by a two-step process. ► Non-radiative decay of the excitons leads to the creation of (WO{sub 4}){sup 3−}–A{sup 3+} centers.

  14. Mechanism of luminescent emission in BaY{sub 2}F{sub 8} scintillators doped with rare earths; Mecanismos de emissao luminescente nos cintiladores de BaY{sub 2}F{sub 8} dopado com terras raras

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Ana Carolina de Mello

    2013-07-01

    weak. The combined results obtained with these techniques together with an analysis of X-ray absorption spectroscopy (XAS) and X-rays Excited Optical Luminescence (XEOL) allowed the development of a model for the scintillation mechanism for the rare earth doped BaYF systems. (author)

  15. Microwave-assisted one-pot synthesis of water-soluble rare-earth doped fluoride luminescent nanoparticles with tunable colors.

    Science.gov (United States)

    Mi, Cong-Cong; Tian, Zhen-Huang; Han, Bao-Fu; Mao, Chuan-Bin; Xu, Shu-Kun

    2012-06-05

    Polyethyleneimine (PEI) functionalized multicolor luminescent LaF(3) nanoparticles were synthesized via a novel microwave-assisted method, which can achieve fast and uniform heating under eco-friendly and energy efficient conditions. The as-prepared nanoparticles possess a pure hexagonal structure with an average size of about 12 nm. When doped with different ions (Tb(3+) and Eu(3+)), the morphology and structure of the nanoparticles were not changed, whereas the optical properties varied with doped ions and their molar ratio, and as a result emission of four different colors (green, yellow, orange and red) were achieved by simply switching the types of doping ions (Eu(3+) versus Tb(3) +) and the molar ratio of the two doping ions.

  16. 2D Layered Materials of Rare-Earth Er-Doped MoS2 with NIR-to-NIR Down- and Up-Conversion Photoluminescence.

    Science.gov (United States)

    Bai, Gongxun; Yuan, Shuoguo; Zhao, Yuda; Yang, Zhibin; Choi, Sin Yuk; Chai, Yang; Yu, Siu Fung; Lau, Shu Ping; Hao, Jianhua

    2016-09-01

    A 2D system of Er-doped MoS2 layered nanosheets is developed. Structural studies indicate that the Er atoms can be substitutionally introduced into MoS2 to form stable doping. Density functional theory calculation implies that the system remains stable. Both NIR-to-NIR up-conversion and down-conversion light-emissions are observed in 2D transition metal dichalcogenides, ascribed to the energy transition from Er(3+) dopants.

  17. An insight to the low temperature conduction mechanism of c-axis grown Al-doped ZnO, a widely used transparent conducting oxide

    Science.gov (United States)

    Murali, Banavoth; Parui, Jayanta; Madhuri, M.; Krupanidhi, S. B.

    2015-01-01

    Al-doped ZnO thin films were synthesized from oxygen reactive co-sputtering of Al and Zn targets. Explicit doping of Al in the highly c-axis oriented crystalline films of ZnO was manifested in terms of structural optical and electrical properties. Electrical conduction with different extent of Al doping into the crystal lattice of ZnO (AZnO) were characterized by frequency dependent (40 Hz-50 MHz) resistance. From the frequency dependent resistance, the ac conduction of them, and correlations of localized charge particles in the crystalline films were studied. The dc conduction at the low frequency region was found to increase from 8.623 µA to 1.14 mA for the samples AZnO1 (1 wt% Al) and AZnO2 (2 wt% Al), respectively. For the sample AZnO10 (10 wt% Al) low frequency dc conduction was not found due to the electrode polarization effect. The measure of the correlation length by inverse of threshold frequency (ω0) showed that on application of a dc electric field such length decreases and the decrease in correlation parameter(s) indicates that the correlation between potentials wells of charge particles decreases for the unidirectional nature of dc bias. The comparison between the correlation length and the extent of correlation in the doped ZnO could not be made due to the observation of several threshold frequencies at the extent of higher doping. Such threshold frequencies were explained by the population possibility of correlated charge carriers that responded at different frequencies. For AZnO2 (2% Al), the temperature dependent (from 4.5 to 288 K) resistance study showed that the variable range hopping mechanism was the most dominating conduction mechanism at higher temperature whereas at low temperature region it was influenced by the small polaronic hopping conduction mechanism. There was no significant influence found in these mechanisms on applications of 1, 2 and 3 V as biases.

  18. 稀土氢氧化物纳米线掺杂二氧化钛光催化性能%Photocatalytic properties of rare earth hydroxide nanowires doped TiO2

    Institute of Scientific and Technical Information of China (English)

    苗慧; 丁建; 高丹; 朱良俊; 崔玉民

    2015-01-01

    Using hydrothermal synthesis of rare earth Y( OH) 3 and the Eu( OH) 3 nanowires,taking a cer-tain rare earth nanowires adding tetrabutyl titanate as the main raw material of sol-gel system,the prepara-tion of the quantity of different calcination temperature of rare earth doped TiO2 composite material,deter-mination of the UV-Vis absorption spectrum and fluorescence spectrum. Aiming at the methyl orange deg-radation,studied the photocatalytic performance of the material. The results show that the mixed rare earth quantity has distinct effect on the light catalytic properties,decolorization rate of methyl orange with the increase of amount of rare earth doped;Different calcination temperature of the composite materials also affect the photocatalytic performance,raise the temperature under the condition of laboratory decolorization by rate of methyl orange, when the calcination temperature is 600 ℃, the Y ( OH ) 3 or Eu ( OH ) 3 nanowires doping amount was 1%,photocatalytic effect is best,when light after 1 h of reaction of methyl orange degradation rate can reach more than 99%.%利用水热法合成稀土Y( OH)3和Eu( OH)3纳米线,取一定稀土纳米线掺入以钛酸四丁酯为主要原料的溶胶-凝胶体系中,制备出不同煅烧温度不同稀土掺杂量的TiO2材料。以甲基橙为目标降解物,研究了该材料的光催化性能。结果表明,稀土的掺入量对材料的光催化性能有明显的影响,甲基橙的脱色率随着稀土掺入量的增加降低;不同煅烧温度也影响材料的光催化性能,实验条件下,煅烧温度较高的材料催化甲基橙的脱色率更高,当煅烧温度为600℃,Y( OH)3或Eu( OH)3纳米线掺入量为1%时,光催化效果最佳,光反应1 h后甲基橙的降解率可达99%以上。

  19. Doping of Semi Conductors

    Directory of Open Access Journals (Sweden)

    V. V. Agashe

    1960-07-01

    Full Text Available Most of the semi-conductors are formed by addition of foreign substances in an insulator. This is called 'Doping'. These doped semi-conductors today are widely used in many electrical devices. Some of them are rectifiers, transistors, thermistors, oxides cathodes and photo-sensitive elements. This paper reviews the fundamental concept of impurity in semi-conductors and recent work on doping of the latter. Purification methods are described in the case of group IV elements and semi-conducting intermetallic compounds. Results of different physical measurements have been discussed in order to understand the role of 'doping'.

  20. Effects of Rare Earths on Properties and Microstructure of Automotive Friction Materials

    Institute of Scientific and Technical Information of China (English)

    Xu Yue; Lu Liguo; Bai Jing

    2007-01-01

    Rare earth compounds as modifiers used widely in modern friction materials can enhance the interracial binding of constituents of materials and improve the comprehensive properties of materials evidently. However, there are still few reports on application of rare earth in automotive friction materials. In order to study the effect mechanism of rare earths in friction materials, a rare earth compound was selected as additive and the effects of materials doped with or without rare earth on friction and wear properties of materials were studied. The microstructure and worn surface morphology were observed by scanning electron microscopy and the macro performance was discussed. Worn surface element constitution of materials was analyzed by energy dispersive spectroscopy. Effect mechanism of rare earths on friction and wear behaviors of friction materials were discussed. The results show that doping rare earths in friction materials can stabilize friction Coefficient, lower the wear rate of materials and increase the impact strength of materials. The flexibility and fracture resistance of materials is greatly improved. Worn surface of materials doped with rare earth is compact and the surface adhesion is greatly enhanced.

  1. VUV spectroscopic properties of rare-earth (RE=Eu, Tb and Dy)-doped A2Zr(PO4)2 (A=Li, Na and K) phosphates

    Institute of Scientific and Technical Information of China (English)

    林啸; 冯昂; 张志军; 赵景泰

    2014-01-01

    This study fully investigated the vacuum ultraviolet excitation spectra of pure and rare-earth (RE=Eu, Tb and Dy)-doped A2Zr(PO4)2 (A=Li, Na and K) phosphors. The synthesized Na and Li compounds were characterized by XRD showing two new types of phases after indexation. Although these three pure compounds had different crystal structures, they exhibited similar luminescence properties. For Eu3+-activated samples, the broad excitation band centered at 217 nm could be attributed to the CT transition between O2- (2p6) and Eu3+ ions. For Tb3+-doped samples, two groups of f-d transitions were observed, where a strong broad band at 221 nm was due to the spin-allowed f-d transition. Energy transfer from O2-to Dy3+was not observed in Dy3+-doped phosphors, probably because it overlapped considerably with the CT transition from O2- to Zr4+at 187 nm.

  2. Physicochemical properties of rare earth doped ceria Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) as an electrolyte material for IT-SOFC/SOEC

    Science.gov (United States)

    Chaubey, Nityanand; Wani, B. N.; Bharadwaj, S. R.; Chattopadhyaya, M. C.

    2013-06-01

    Nanosized crystallites of rare earth doped ceria Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) a promising electrolyte material for Intermediate Temperature - Solid Oxide Fuel Cells/electrolysis cells have been synthesized by standard ceramic route. Detection of impurities in the samples was done by FTIR spectroscopy. X-ray diffraction studies were used for the determination of phase purity, crystal structure and average crystallite size of the samples. Kinetics involved in phase formation has been discussed. Raman study showed a major band around 465 cm-1 in all the samples, which is attributed to the cubic fluorite structure of ceria. It was also found that for samples Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) the frequency of F2g shifts to lower value. Electrochemical impedance spectroscopy has been used to measure the ionic conductivity of the samples at elevated temperatures. The Gd doped sample showed the highest grain boundary and total conductivity in comparison to Sm and Nd doped sample. Bulk thermal expansion behavior, sintered densities and micro structural features of the samples have also been studied.

  3. Development of Doped Lanthanum Gallate Solid Electrolytes

    Institute of Scientific and Technical Information of China (English)

    蒋凯; 王海霞; 郑立庆; 杨林; 孟健; 苏锵

    2003-01-01

    Development of the doped lanthanum gallate solid electrolytes in the recent years was reviewed. The structure and oxygen ion transference mechanism were discussed. Effects of alkali earths, transition metals, and impurities on electrical conductivity of the doped lanthanum gallates were also discussed. The applications of doped lanthanum gallate were described. The current problems and corresponding strategies were explored.

  4. Synthesis and thermoelectric properties of rare earth Yb-doped Ba{sub 8−x}Yb{sub x}Si{sub 30}Ga{sub 16} clathrates

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lihua, E-mail: lhliu@ustb.edu.cn [University of Science and Technology Beijing, School of Mathematics and Physics, Department of Physics, Beijing 100083 (China); Li, Feng [University of Science and Technology Beijing, School of Mathematics and Physics, Department of Physics, Beijing 100083 (China); Wei, Yuping; Chen, Ning; Bi, Shanli [University of Science and Technology Beijing, School of Materials Science and Engineering, Beijing 100083 (China); Qiu, Hongmei [University of Science and Technology Beijing, School of Mathematics and Physics, Department of Physics, Beijing 100083 (China); Cao, Guohui [University of Science and Technology Beijing, School of Materials Science and Engineering, Beijing 100083 (China); Li, Yang [University of Science and Technology Beijing, School of Mathematics and Physics, Department of Physics, Beijing 100083 (China); University of Puerto Rico at Mayaguez, Department of Engineering Science and Materials, Mayaguez, PR 00681-9044 (United States)

    2014-03-05

    Highlights: • Samples with the chemical formula Ba8−{sub x}Yb{sub x}Si{sub 30}Ga{sub 16} (x = 0, 0.5, 0.7, 1 and 1.5) were prepared. • Some Yb atoms enter the clathrate lattice to replace Ba, while other Yb atoms are oxidized as Yb{sub 2}O{sub 3}. • The thermal conductivity decreases with Yb-doping. • Thermoelectric figure of merit ZT significantly increased. -- Abstract: The potential thermoelectric and magnetic application of clathrate materials with rare-earth doping is the focus of much of the recent research activity in the synthetic material physics and chemistry. A series of clathrate samples with the chemical formula Ba{sub 8−x}Yb{sub x}Si{sub 30}Ga{sub 16} (x = 0, 0.5, 0.7, 1 and 1.5) were prepared by combining arc melting, ball milling and spark plasma sintering (SPS) techniques. X-ray diffraction and scanning electronic microscopy combined with energy-dispersive X-ray spectroscopy (EDS) analysis showed the dominant phase to be the type-I clathrate. Whereas, X-ray structural refinement and EDS analysis indicated that some Yb atoms enter the clathrate lattice to replace Ba at 2a sites, while other Yb atoms are oxidized as Yb{sub 2}O{sub 3} precipitated around grain boundaries. The solid solubility of Yb into clathrate lattice yielded x ∼ 0.3. Comparative analysis between Yb-doped and Yb-free clathrates showed that the thermal conductivity decreases with Yb-doping. Consequently, thermoelectric figure of merit ZT significantly increased.

  5. Técnica de bombeio e prova para medidas de absorção de estado excitado e de emissão estimulada, em materiais sólidos dopados com íons terras raras Pump-probe technique for excited state absorption and stimulated emission measurements in rare earth ion doped solid materials

    Directory of Open Access Journals (Sweden)

    Andrea Simone Stucchi de Camargo

    2008-01-01

    Full Text Available Rare earth ion doped solid state materials are the most important active media of near-infrared and visible lasers and other photonic devices. In these ions, the occurrence of Excited State Absorptions (ESA, from long lived electronic levels, is commonplace. Since ESA can deeply affect the efficiencies of the rare earth emissions, evaluation of these transitions cross sections is of greatest importance in predicting the potential applications of a given material. In this paper a detailed description of the pump-probe technique for ESA measurements is presented, with a review of several examples of applications in Nd3+, Tm3+ and Er3+ doped materials.

  6. The effect of Ce3+ ions on the spectral and decay characteristics of luminescence phosphate-borate glasses doped with rare-earth ions

    Science.gov (United States)

    Valiev, D. T.; Polisadova, E. F.; Belikov, K. N.; Egorova, N. L.

    2014-05-01

    The luminescent characteristics of Li2O-B2O3-P2O5-CaF2 (LBPC) glasses doped with Gd3+ and Tb3+ ions and codoped with Ce3+ are studied by pulsed optical spectrometry under electron beam excitation. It is found that in glass with Ce3+ and Gd3+ ions a decrease in the decay time of gadolinium luminescence in the 312-nm band (6 P J → 8 S 7/2) was observed. It is shown that in the glass LBPC: Tb, Ce, an increase in the emission intensity in the main radiative transitions in terbium ion was observed. In the kinetics of luminescence band 545 nm of LBPC: Tb, Ce glasses, is present stage of buildup, the character of which changes with the doped of Ce3+ ions. The mechanism of energy transfer in LBP glasses doped with rare elements is discussed.

  7. Contributed Review: A review of the investigation of rare-earth dopant profiles in optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Sidiroglou, F.; Baxter, G. [Optical Technology Research Laboratory, College of Engineering and Science, Victoria University, P.O. Box 14428, Melbourne, VIC 8001 (Australia); Roberts, A. [School of Physics, The University of Melbourne, Melbourne, VIC 3010 (Australia)

    2016-04-15

    Rare-earth doped optical fibers have captivated the interest of many researchers around the world across the past three decades. The growth of this research field has been stimulated primarily through their application in optical communications as fiber lasers and amplifiers, although rare-earth doped optical fiber based devices are now finding important uses in many other scientific and industrial areas (for example, medicine, sensing, the military, and material processing). Such wide commercial interest has provided a strong incentive for innovative fiber designs, alternative glass compositions, and novel fabrication processes. A prerequisite for the ongoing progress of this research field is developing the capacity to provide high resolution information about the rare-earth dopant distribution profiles within the optical fibers. This paper constitutes a comprehensive review of the imaging techniques that have been utilized in the analysis of the distribution of the rare-earth ion erbium within the core of optical fibers.

  8. Contributed Review: A review of the investigation of rare-earth dopant profiles in optical fibers

    Science.gov (United States)

    Sidiroglou, F.; Roberts, A.; Baxter, G.

    2016-04-01

    Rare-earth doped optical fibers have captivated the interest of many researchers around the world across the past three decades. The growth of this research field has been stimulated primarily through their application in optical communications as fiber lasers and amplifiers, although rare-earth doped optical fiber based devices are now finding important uses in many other scientific and industrial areas (for example, medicine, sensing, the military, and material processing). Such wide commercial interest has provided a strong incentive for innovative fiber designs, alternative glass compositions, and novel fabrication processes. A prerequisite for the ongoing progress of this research field is developing the capacity to provide high resolution information about the rare-earth dopant distribution profiles within the optical fibers. This paper constitutes a comprehensive review of the imaging techniques that have been utilized in the analysis of the distribution of the rare-earth ion erbium within the core of optical fibers.

  9. Calculations of Neutron and y Transport through Rare-earth Doped Polymer%中子、γ射线在稀土-高分子材料中的输运

    Institute of Scientific and Technical Information of China (English)

    呼延雪莹; 胡碧涛

    2011-01-01

    A series of shielding analyses have been performed to estimate the material composition and optimum thickness required for a new radiation shield with various rare-earth doped polymer and heavy metal mixtures.The neutron and y photon fluxes have been calculated by Monte Carlo N-Particle(MCNP) transport code.The results indicate that the relative fluxes of y photon and neutron in both traditional and new composite materials follow an exponential decay rule with the distance of penetration.It can be seen that the composite material consisting of rare-earth doped polymer and heavy metal has stronger neutron shielding performance than lead-boron polyethylene,but weaker y shielding effectiveness than W-Ni alloy.It isalso found that materials with more components of rare earth elements don't always provide better neutron shielding performance.%为研究新型复合屏蔽材料的最佳厚度与各种成分最佳配比,用MCNP计算了中子、γ射线在稀土-高分子与重金属复合材料中的通量.对中子、γ射线在屏蔽体中变化规律进行了深入探索,同传统复合屏蔽材料的屏蔽性能进行了对比.结果表明,中子和γ射线通过屏蔽体时,其强度遵循指数衰减规律.新型屏蔽材料对中子的屏蔽效果均优于铅硼聚乙烯,对γ射线的屏蔽效果均劣于W-Ni合金,且并非稀土含量越高,材料对中子辐射屏蔽能力越强.

  10. Ultraviolet photoluminescence in Gd-doped silica and phosphosilicate fibers

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2017-04-01

    Full Text Available Optical fiber lasers operating in the near infrared and visible spectral regions have relied on the spectroscopic properties of rare earth ions such as Yb3+, Er3+, Tm3+, Nd3+, and Sm3+. Here, we investigate Gd3+ doping in phosphosilicate and pure silica fibers using solution doping and sol-gel techniques, respectively, for potential applications in the ultraviolet. Photoluminescence spectra for optical fiber bundles and fiber preforms were recorded and compared. Emissions at 312 nm (phosphosilicate and 314 nm (pure silica were observed when pumping to the Gd3+ 6DJ, 6IJ, and 6PJ = 5/2, 3/2 energy levels. Oxygen deficient center was observed in solution doping sample with a wide absorption band centered at around 248 nm not affecting pumping to 6IJ states.

  11. Influence of rare-earth additives (La, Sm and Dy on the microstructure and dielectric properties of doped BaTiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Paunović Vesna

    2010-01-01

    Full Text Available A series of La/Mn, Sm/Mn and Dy/Mn codoped BaTiO3 samples were prepared by the conventional solid state procedure with dopant concentrations ranging from 0.1 up to 2.0 at%. The specimens were sintered at 1320°C and 1350°C in an air atmosphere for two hours. The low doped samples demonstrated a mainly uniform and homogeneous microstructure with average grain sizes ranging from 0.3 μm to 5.0 μm. The appearance of secondary abnormal grains in the fine grain matrix and core-shell structure were observed in highly doped La/BaTiO3 and Dy/BaTiO3 sintered at 1350°C. The low doped samples, sintered at 1350°C, display a high value of dielectric permittivity at room temperature, 6800 for Sm/BaTiO3, 5900 for Dy/BaTiO3 and 3100 for La/BaTiO3. A nearly flat permittivity-response was obtained in specimens with 2.0 at% additive content. Using a modified Curie-Weiss law the Curie-like constant C⁄ and a critical exponent γ were calculated. The obtained values of γ pointed out the diffuse phase transformation in heavily doped BaTiO3 samples.

  12. Preparation of Rare Earth Doped TiO2 Grafting Poly-Silicone Electrorheological Fluid and Its Electrorheological Response%稀土掺杂纳米二氧化钛接枝聚硅氧烷电流变液的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    吴茂艳; 王富星; 丁克鸿; 王志峰; 刘俊亮; 张明

    2012-01-01

    采用水热合成法制备稀土掺杂金红石型纳米二氧化钛,并通过XRD,TEM等对其进行了表征.结果表明,稀土离子的掺杂使得二氧化钛(110)晶面衍射峰位置发生了漂移,并且出现了不同程度的宽化,但并没有改变纳米TiO2的晶型,也没有出现稀土氧化物的特征衍射峰.稀土掺杂后的二氧化钛形貌为棒状,长径比约为110 nm:20 nm.利用硅烷偶联剂KH-570对稀土掺杂纳米TiO2表面修饰,与乙烯硅油发生接枝反应制备新型电流变液,并通过旋转流变仪测试了该电流变液的稳态电流变性能.通过红外吸收光谱发现,乙烯基硅油与KH-570-TiO2发生了一定程度的接枝共聚反应.由于无机纳米粒子与聚硅氧烷连续相形成化学键体系,电流变液的抗沉降稳定性得到了很大的提高;稀土离子的掺杂增大了体系的极性,随着电场强度的增大,电流变液的线性平台区也随之变长,表现出典型的类固态响应行为,其中以Sm3+的掺杂效果最为显著.%Rare earth doped rutile titanium dioxide nanoparticles were prepared by hydrothermal synthesis method. And the RE-TiO2 particles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) . The results showed that the incorporation of RE3+ did preserve the rutile crystal form of TiO2, and there was no other crystal type. But titanium dioxide crystal diffraction peak locations (110) drifted, and appeared different degrees of the wide. The feature of the RE-TiO2 nanoparticles was clubbed and the size was about 110 nm: 20 run. KH-570 silane coupling agent was used for modifying rare earth doped nanometer TiO2 and reacted with vinyl silicone oil to prepare new electrorheological fluid. And the steady electrorheological fluid performance was tested by rotary rheometer. Through the infrared absorption spectrum, it was found that vinyl silicone oil was reacted with KH-570-TiO2. Because the inorganic nanometer particles and

  13. Photoluminescence properties of rare-earth-doped (Er³⁺,Yb³⁺) Y₂O₃ nanophosphors by a combustion synthesis method.

    Science.gov (United States)

    Kaur, Manmeet; Bisen, D P; Brahme, N; Singh, Prabhjot; Sahu, I P

    2016-05-01

    In this work, we report the synthesis of Y2O3:Er(3+), Y2O3:Yb(3+) and Y2O3:Er(3+),Yb(3+) nanophosphors by the combustion synthesis method using urea as fuel. The doping agents were incorporated in the form of erbium nitrate and ytterbium nitrate. X-Ray diffraction (XRD) patterns revealed that the synthesized particles have a body-centered cubic structure with space group Ia-3. The photoluminescence (PL) properties were investigated after UV and infrared irradiation at room temperature. A strong characteristic emission of Er(3+) and Yb(3+) ions was identified, and the influence of doping concentration on the PL properties was systematically studied. Energy transfer from Yb(3+) to Er(3+) ions was observed in Y2O3 nanophosphors. The obtained result may be useful in potential applications such as bioimaging.

  14. Rare-earth-ion-doped ultra-narrow-linewidth lasers on a silicon chip and applications to intra-laser-cavity optical sensing

    Science.gov (United States)

    Bernhardi, E. H.; de Ridder, R. M.; Wörhoff, K.; Pollnau, M.

    2013-03-01

    We report on diode-pumped distributed-feedback (DFB) and distributed-Bragg-reflector (DBR) channel waveguide lasers in Er-doped and Yb-doped Al2O3 on standard thermally oxidized silicon substrates. Uniform surface-relief Bragg gratings were patterned by laser-interference lithography and etched into the SiO2 top cladding. The maximum grating reflectivity exceeded 99%. Monolithic DFB and DBR cavities with Q-factors of up to 1.35×106 were realized. The Erdoped DFB laser delivered 3 mW of output power with a slope efficiency of 41% versus absorbed pump power. Singlelongitudinal- mode operation at a wavelength of 1545.2 nm was achieved with an emission line width of 1.70 0.58 kHz, corresponding to a laser Q-factor of 1.14×1011. Yb-doped DFB and DBR lasers were demonstrated at wavelengths near 1020 nm with output powers of 55 mW and a slope efficiency of 67% versus launched pump power. An Yb-doped dualwavelength laser was achieved based on the optical resonances induced by two local phase shifts in the DFB structure. A stable microwave signal at ~15 GHz with a -3-dB width of 9 kHz and a long-term frequency stability of +/- 2.5 MHz was created via the heterodyne photo-detection of the two laser wavelengths. By measuring changes in the microwave beat signal as the intra-cavity evanescent laser field interacts with micro-particles on the waveguide surface, we achieved real-time detection and accurate size measurement of single micro-particles with diameters ranging between 1 μm and 20 μm, which represents the typical size of many fungal and bacterial pathogens. A limit of detection of ~500 nm was deduced.

  15. Rare Earth Doped Semiconductors, Symposium Held in San Francisco, California on April 13-15, 1993. Materials Research Society Symposium Proceedings, Volume 301

    Science.gov (United States)

    1994-02-04

    Si FILMS BY ELECTRON CYCLOTRON RESONANCE PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION 49 Jim L. Rogers , Walter J. Varhue. and Edward Adams ERBIUM-DOPED...VAPOR DEPOSITION JIM L. ROGERS *, WALTER J. VARHUE* and EDWARD ADAMS** *Dept. of Electrical Engineering, University of Vermont, Burlington, VT 05405 **IBM...McFarlane and D. Yap, Electron. Lett. 29, 172 (1993). 14. 1. Chartier , B. Ferrand, D. Pelenc, S.J. Field, D.C, Hanna, A.C. Large, D.P. Shepherd, A.C

  16. Propriedades dielétricas de cerâmicas (Sr,BaNb2O6 dopadas com terras raras Dielectric properties of (Sr,BaNb2O6 ceramics doped with rare earths

    Directory of Open Access Journals (Sweden)

    I. A. Santos

    1999-12-01

    Full Text Available Cerâmicas de Sr1-xBaxNb2O6, "puras" e dopadas com óxidos de terras raras, foram preparadas com o objetivo de estudar o seu comportamento dielétrico em função da adição desses dopantes. As amostras foram caracterizadas através de medidas dielétricas efetuadas em função da temperatura (30 K a 500 K e da freqüência (1 kHz a 1 MHz. Em todas as amostras estudadas verifica-se a presença de dois processos distintos de relaxação dielétrica. O primeiro processo é observado a temperaturas inferiores a 100 K. O segundo processo é observado próximo a temperatura ambiente, onde a constante dielétrica apresenta seu maior valor. Observou-se que a adição de dopantes causa efeitos distintos nas temperaturas de máximo das constantes dielétricas nas duas regiões de relaxação dielétrica.Ceramics of SBN, undoped and doped with rare earth oxides, were prepared to the study of the influence of the doping on the dielectric properties. The samples were characterised through dielectric measurements as a function of temperature (30 K to 500 K and frequency (1 kHz to 1 MHz. In all samples two distinct dielectric relaxation processes were observed. The first one at temperatures below 100 K; the second one is near room temperature, where the dielectric constant is maximum. The doping causes distinct effects in the maximum temperatures of the dielectric constants in the two dielectric relaxation regions.

  17. 稀土元素Gd掺杂BiFeO3的第一性原理研究%First-principles study of rare-earth-element Gd doped BiFeO3

    Institute of Scientific and Technical Information of China (English)

    张静; 徐凯宇; 刘廷禹; 陈腾

    2011-01-01

    采用基于密度泛函理论的局域自旋密度近似加U法(LSDA+U:Hubbard参数)计算了多铁材料BiFeO3铁电相以及稀土元素Gd掺杂BiFeO3材料的能带结构、态密度(DOS)、原子轨道占据数和净电荷分布等,对稀土元素Gd掺杂BiFeO3可能引起的电子结构、介电常数和铁磁性的改变进行了第一性原理研究.计算结果表明:Gd掺杂对材料钙铁矿结构影响不大,BiFeO3铁电性主要来源于Fe原子3d轨道和O原子2p轨道杂化;掺杂Gd后材料中的Fe原子和O原子的共价性减弱,Bi原子和O原子的离子性增强,禁带宽度变窄,绝缘性减弱,铁磁性明显增强;计算得到的光学性质表明材料的静态介电常数有所增加.%The band structure, density of states (DOS) , Mulliken charge population etc. Of ferroelectric (FE) BiFeO3 and rare-earth-element Gd doped BiFeO3 have been studied by first-principles calculations within the local spin density approximation plus Hubbard U (LSDA+U) approach. Our result turns out that the perovskite structure of BiFeO3 is not significantly affected by Gd doped. The ferroelectric stability of BiFeO3 is found to be attributed to the hybridization between 3d orbit of Fe and 2p orbit of O atom. And the strength of covalent bonds between Fe atom and O atom becomes weaker while the strength of ionic bonds between Bi and O becomes stronger. Meanwhile the insulativity becomes weaker since the band gap of Gd doped BiFeO3 is narrower than that of ferroelectric BiFeO3. However, the fer-romagnetism improved significantly. Furthermore, the absorption coefficient and dielectric function were calculated and the corresponding numerical results show that the static dielectric constant of Gd doped BiFeO3 is higher than that of pure BiFeO3.

  18. Rare earths (Ce, Eu, Tb) doped Y{sub 2}Si{sub 2}O{sub 7} phosphors for white LED

    Energy Technology Data Exchange (ETDEWEB)

    Sokolnicki, Jerzy, E-mail: jerzy.sokolnicki@chem.uni.wroc.pl [Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie Street, 50-383 Wroclaw (Poland)

    2013-02-15

    Nanocrystalline yttrium pyrosilicate Y{sub 2}Si{sub 2}O{sub 7} (YPS) singly, doubly or triply doped with Ce{sup 3+}, Eu{sup 3+}, Tb{sup 3+} was obtained by the reaction of nanostructured Y{sub 2}O{sub 3}:Ln{sup 3+} and colloidal SiO{sub 2} at high temperatures. X-ray diffraction analysis confirmed the formation of a single phase of {alpha}-YPS at 1200 Degree-Sign C. Two series of YPS samples doped with Eu{sup 3+} or Eu{sup 3+}/Tb{sup 3+} were obtained by applying the reducing atmosphere (75%N{sub 2}+25%H{sub 2}) at different temperatures. The luminescence and excitation spectra are reported. The singly Eu{sup 3+} doped YPS emit from both Eu{sup 3+} and Eu{sup 2+} ions, with the spectral position and width of the Eu{sup 2+} emission different in both series. The presence of Eu{sup 2+} in the samples was confirmed by electron paramagnetic resonance (EPR) spectra. A broadband emission of Eu{sup 2+} (380-650 nm), combined with the red emission of Eu{sup 3+} is perceived by the naked eye as white light. Co-doping of YPS:Eu{sup 3+} with Tb{sup 3+} results in enhancement of the green component of the emission, and well-balanced white luminescence. The colour of this emission is tunable, and it is possible to get Commission International de I'Eclairage (CIE) chromaticity coordinates of (0.327, 0.327), colour-rendering index (CRI) of 85, and quantum efficiency (QE) of 71%. These phosphors are efficiently excited in the wavelength range of 300-420 nm, which perfectly matches a near UV-emitting InGaN chip. It was shown that for triply (Ce{sup 3+}, Eu{sup 3+} and Tb{sup 3+}) doped samples the three emissions from the particular activators can be generated using one excitation wavelength. The white light resulting from the superposition of the blue (Ce{sup 3+}), green (Tb{sup 3+}) and red (Eu{sup 3+}) emissions can be obtained by varying the concentration of the active ions and the treating atmosphere, i.e. reducing or oxidising. Eu{sup 2+} was not detected in the triply

  19. Hybrid Neodymium-doped passively Q-switched waveguide laser

    Energy Technology Data Exchange (ETDEWEB)

    Salas-Montiel, Rafael [IMEP-LAHC, 3 Parvis Louis Neel BP 257, 38016 Grenoble Cedex 1 (France); Bastard, Lionel [IMEP-LAHC, 3 Parvis Louis Neel BP 257, 38016 Grenoble Cedex 1 (France)], E-mail: lionel.bastard@minatec.inpg.fr; Grosa, Gregory; Broquin, Jean-Emmanuel [IMEP-LAHC, 3 Parvis Louis Neel BP 257, 38016 Grenoble Cedex 1 (France)

    2008-03-25

    In the mid 80s, the doping of optical fibers' core with rare earth atoms has been a major breakthrough in the field of optical telecommunications since it allowed the realization of in line optical amplifiers. However, erbium-doped fiber amplifiers are a few meters long and a huge effort has been made in order to realize compact and efficient active devices based on rare-earth-doped waveguides. For this purpose the use of phosphate glasses instead of silicate ones has been investigated because they allow a better solubility of the inserted rare earths. In this paper we present the realization of a hybrid Neodymium-doped passively Q-switched waveguide laser made by an ion-exchange on a Schott IOG-1 phosphate laser glass combined with the deposition of a bis(4-dimethylaminodithiobenzil)nickel (BDN) saturable absorber diluted in a cellulose acetate polymer cladding. In a first step, we present the continuous wave (CW) operation of the laser with an undoped cladding. We show that for a 3.5 {mu}m wide, 1.5 cm long waveguide realized by a silver-sodium ion-exchange, a 6 mW output has been achieved by creating a Fabry-Perot cavity with dielectric multilayers mirrors sticked to the chip facets. Then, the characterizations performed on the BDN-doped layers are presented. It is shown that a proper selection of the hybrid guiding condition and saturable absorber concentration entail a non-saturated excess absorption of 3.4 dB/cm. Finally, we present the results we obtained on the Q-switched behaviour of the laser. Indeed a repetition rate of 330 kHz is achieved for a pulse energy of 10 nJ and a peak power of 1 W.

  20. Rare-earth Doped GaN - An Innovative Path Toward Area-scalable Solid-state High Energy Lasers Without Thermal Distortion (2nd year)

    Science.gov (United States)

    2010-06-01

    temperature for two Ga fluxes: Ga = 1.5×10–7 torr BEP (blue) and Ga= 3.5×10–7 torr BEP (red). ...........................................4  Figure 4...850–1025 °C, and the Ga flux, measured as beam equivalent pressure ( BEP ), was varied from 9.8×10–6 to 5.6×10–7 torr. The secondary ion mass...temperature for two Ga fluxes: Ga = 1.5×10–7 torr beam equivalent pressure (blue) and Ga= 3.5×10–7 torr BEP (red). 3.2 Optical Studies of Nd Doped

  1. Preparation and Performance of Al2TiO5-TiO2-SiO2 Honeycomb Ceramics by Doping Rare Earth

    Institute of Scientific and Technical Information of China (English)

    Zhu Shemin; Shen Yuesong; Wang Jialei; Zhang Yandong; Liu Yayun

    2007-01-01

    A preferable honeycomb ceramics of Al2TiO5-TiO2-SiO2 doped by CeO2 and Er2O3 with high performance was prepared by means of extrusion molding and the effects of CeO2 and Er2O3 on the mechanical strength, thermal stability, and sintering temperature of ATS ceramics were mainly investigated. The exp erimental results and the microscopic analysis by scanning electron microscope, X-ray powder diffraction, and TG-DSC showed that adding CeO2 and Er2O3 into ATS could prohibit the growth of their crystal grains and make their size uniform, which finally decrease its sintering temperature, and also enhance its mechanical performance as well as thermal stability. After the reforming, ATS doped by 0.5%CeO2+0.5%Er2O3 was sintered at 1250 ℃, its bending strength reached to 177.4 MPa and thermal expansion coefficient was 3.8×10-6/℃ at 25~1000 ℃, which provided a promising basis of making monolithic honeycomb catalyst of deNOx.

  2. Wide-Range Enhancement of Spectral Response by Highly Conductive and Transparent μc-SiOx:H Doped Layers in μc-Si:H and a-Si:H/μc-Si:H Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Pei-Ling Chen

    2016-01-01

    Full Text Available The enhancement of optical absorption of silicon thin-film solar cells by the p- and n-type μc-SiOx:H as doped and functional layers was presented. The effects of deposition conditions and oxygen content on optical, electrical, and structural properties of μc-SiOx:H films were also discussed. Regarding the doped μc-SiOx:H films, the wide optical band gap (E04 of 2.33 eV while maintaining a high conductivity of 0.2 S/cm could be obtained with oxygen incorporation of 20 at.%. Compared to the conventional μc-Si:H(p as window layer in μc-Si:H single-junction solar cells, the application of μc-SiOx:H(p increased the VOC and led to a significant enhancement in the short-wavelength spectral response. Meanwhile, the employment of μc-SiOx:H(n instead of conventional ITO as back reflecting layer (BRL enhanced the external quantum efficiency (EQE of μc-Si:H single-junction cell in the long-wavelength region, leading to a relative efficiency gain of 10%. Compared to the reference cell, the optimized a-Si:H/μc-Si:H tandem cell by applying p- and n-type μc-SiOx:H films achieved a VOC of 1.37 V, JSC of 10.55 mA/cm2, FF of 73.67%, and efficiency of 10.51%, which was a relative enhancement of 16%.

  3. Rare earth ions doped polyaniline/cobalt ferrite nanocomposites via a novel coordination-oxidative polymerization-hydrothermal route: Preparation and microwave-absorbing properties

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chunming; Jiang, Junjun; Liu, Xiaohua; Yin, Chengjie; Deng, Cuifen

    2016-04-15

    Polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} (RE=La, Ce, Y, x=0.05–0.25) nanocomposites were successfully synthesized by a novel coordination-oxidative polymerization-hydrothermal method, and doped by sulfosalicylic acid. The resultant nanocomposites were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and electromagnetic measurements. The composites mainly showed nanofibers with a diameter of ca. 70 nm and a length longer than 2 μm. The surface of composites was uniformly covered with numerous nanoparticles with an average size of ca. 10–20 nm. Microwave absorption properties of polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} nanocomposites doped with La ion were found to be better than those doped with Ce and Y ions. For the polyaniline/CoLa{sub x}Fe{sub 2−x}O{sub 4} nanocomposite, the optimal microwave absorption performance is at x=0.15, that is, the mass ratio of La in CoLa{sub x}Fe{sub 2−x}O{sub 4} is 7.5%, with the conductivity of the composite about 0.833 S/cm. Furthermore, when the layer thickness is 2 mm, the maximum reflection loss achieves the maximum number of −42.65 dB at 15.91 GHz with a bandwidth of 6.14 GHz above −10 dB loss, suggesting that these nanocomposites are excellent in microwave absorbing capacity. - Graphical abstract: Scheme PAn/CoRE{sub x}Fe{sub 2−x}O{sub 4} nanocomposites prepared via a novel coordination-oxidative polymerization-hydrothermal route. - Highlights: • An organic–inorganic hybrid―polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} (RE=La, Ce, Y, x=0.05–0.25) nanocomposites was prepared via a novel coordination-oxidative polymerization-hydrothermal route. • The as-prepared polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} nanocomposites exhibit excellent microwave absorbing performance compared with the composites prepared by using conventional method. • The novel method reported in this work could

  4. The Flat Transmission Spectrum of the Super-Earth GJ1214b from Wide Field Camera 3 on the Hubble Space Telescope

    CERN Document Server

    Berta, Zachory K; Désert, Jean-Michel; Kempton, Eliza Miller-Ricci; McCullough, Peter R; Burke, Christopher J; Fortney, Jonathan J; Irwin, Jonathan; Nutzman, Philip; Homeier, Derek

    2011-01-01

    Capitalizing on the observational advantage offered by its tiny M dwarf host, we present HST/WFC3 grism measurements of the transmission spectrum of the super-Earth exoplanet GJ1214b. These are the first published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, finding the transmission spectrum of GJ1214b to be flat between 1.1 and 1.7 microns. Inconsistent with a cloud-free solar composition atmosphere at 8.2 sigma, the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b's outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the flat transmission spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching...

  5. Supramolecular recognition control of polyethylene glycol modified N-doped graphene quantum dots: tunable selectivity for alkali and alkaline-earth metal ions.

    Science.gov (United States)

    Yang, Siwei; Sun, Jing; Zhu, Chong; He, Peng; Peng, Zheng; Ding, Guqiao

    2016-02-07

    The graphene quantum dot based fluorescent probe community needs unambiguous evidence about the control on the ion selectivity. In this paper, polyethylene glycol modified N-doped graphene quantum dots (PN-GQDs) were synthesized by alkylation reaction between graphene quantum dots and organic halides. We demonstrate the tunable selectivity and sensitivity by controlling the supramolecular recognition through the length and the end group size of the polyether chain on PN-GQDs. The relationship formulae between the selectivity/detection limit and polyether chains are experimentally deduced. The polyether chain length determines the interaction between the PN-GQDs and ions with different ratios of charge to radius, which in turn leads to a good selectivity control. Meanwhile the detection limit shows an exponential growth with the size of end groups of the polyether chain. The PN-GQDs can be used as ultrasensitive and selective fluorescent probes for Li(+), Na(+), K(+), Mg(2+), Ca(2+) and Sr(2+), respectively.

  6. Energies of 4f^N and 4f^N-15d States Relative to Host Bands in Rare-earth-doped Fluorides

    Science.gov (United States)

    Thiel, C. W.; Joubert, M.-F.; Tkachuk, A.

    2005-03-01

    Energies of 4f^N states relative to crystal band states were measured for rare-earth ions in the optical host materials LiYF4, Na0.4Y0.6F2.2, and LaF3 using x-ray photoemission spectroscopy. Spectra were modeled to determine the valence band maximum and 4f^ electron binding energies in each material. These results were combined with 4f^N to 4f^N-15d transition energies to determine 5d binding energies for the lowest levels of excited 4f^N-15d configurations. While 4f^N ground-state energies vary within several eV of the valence band maximum for different rare-earth ions in each host, the lowest 4f^N-15d states have similar energies and are several eV below the bottom of the conduction band. A simple model accurately described 4f^N and 4f^N-15d binding energies across the entire series of rare-earth ions. These results improve the understanding of optical materials for lasers, phosphors, and spectral hole burning applications for optical signal processing and data storage.

  7. Versatile Chromium-Doped Zinc Selenide Infrared Laser Sources

    Science.gov (United States)

    2010-05-01

    Erbium Doped Fiber Amplifiers ( EDFAs ). An EDFA is essentially a normal optical fiber waveguide that has been lightly doped with a rare-earth...element, namely erbium (possibly co-doped with ytterbium to increase the pumping efficiency and gain). In a typical EDFA , 980 nm photons are used to

  8. Stabilisation of Fe2O3-rich Perovskite Nanophase in Epitaxial Rare-earth Doped BiFeO3 Films.

    Science.gov (United States)

    Zhang, Huairuo; Reaney, Ian M; Marincel, Daniel M; Trolier-McKinstry, Susan; Ramasse, Quentin M; MacLaren, Ian; Findlay, Scott D; Fraleigh, Robert D; Ross, Ian M; Hu, Shunbo; Ren, Wei; Rainforth, W Mark

    2015-08-14

    Researchers have demonstrated that BiFeO3 exhibits ferroelectric hysteresis but none have shown a strong ferromagnetic response in either bulk or thin film without significant structural or compositional modification. When remanent magnetisations are observed in BiFeO3 based thin films, iron oxide second phases are often detected. Using aberration-corrected scanning transmission electron microscopy, atomic resolution electron energy loss spectrum-mapping and quantitative energy dispersive X-ray spectroscopy analysis, we reveal the existence of a new Fe2O3-rich perovskite nanophase, with an approximate formula (Fe0.6Bi0.25Nd0.15)(3+) Fe(3+)O3, formed within epitaxial Ti and Nd doped BiFeO3 perovskite films grown by pulsed laser deposition. The incorporation of Nd and Bi ions on the A-site and coherent growth with the matrix stabilise the Fe2O3-rich perovskite phase and preliminary density functional theory calculations suggest that it should have a ferrimagnetic response. Perovskite-structured Fe2O3 has been reported previously but never conclusively proven when fabricated at high-pressure high-temperature. This work suggests the incorporation of large A-site species may help stabilise perovskite-structured Fe2O3. This finding is therefore significant not only to the thin film but also to the high-pressure community.

  9. Preparation and Characterization of Yttrium Hydroxide and Oxide Doped with Rare Earth Ions (Eu3+, Tb3+) Nano One-dimensional

    Science.gov (United States)

    Giang, Lam Thi Kieu; Anh, Tran Kim; Marciniak, Lukasz; Hreniak, Dariusz; Strek, Wieslaw; Lojkowski, Witold; Minh, Le Quoc

    The one-dimensional (1D) crystalline nanostructures of Y(OH)3:Eu/Tb have been synthesized using softemplate method at temperature range of 180 - 200 °C for 24 h. The studies by Field Emission Scanning Electron Microscopy (FESEM) have been determined that the outer and interior hollow diameter of Y(OH)3:Eu/Tb nanotubes was obtained range from 150 to 500 nm and 100 to 300 nm, respectively and of the length up to several micrometers, respectively. The Y2O3:Eu/Tb nanorod/tubes have been obtained from Y(OH)3:Eu/Tb counterparts by crucial annealing. The Xray diffraction (XRD) patterns indicated that the Y(OH)3:Eu/Tb and Y2O3:Eu/Tb nanorods and nanotubes obtained has hexagonal and cubic phase with high crystaline. The luminescence and excitation properties of Y(OH)3:Eu/Tb and Y2O3:Eu/Tb nanorods and nanotubes were investigated in details. It found that crystal form and nanomorphology of Y(OH)3 and Y2O3 have played a great role on the emission properties of the doped Eu3+ ions.

  10. High-Tc Superconductivity and Raman Scattering Study of the phonon properties of electron doped (transition metal, rare-earth) - Oxygen-Free CaFeAsF and compared with RFeAsO system

    Science.gov (United States)

    Sasmal, Kalyan; Hadjiev, Viktor; Chu, C. W.(Paul)

    Quaternary CaFeAsF has ZrCuSiAs-type structure,(RO)δ+ layer in RFeAsO replaced by (CaF)δ+ layer,with tetragonal (P4/nmm)-orthorhombic (Cmma) phase transition at 134K,while magnetic order,SDW sets in at 114K. Partial replacement of Fe with Co/Ni is direct electron doping to (FeAs)δ+ layer.Tc ~15K in CaFe0.9Ni0.1AsF.Substitution of rare earth metal for alkaline earth metal suppresses anomaly in resistivity & induces superconductivity.Tc ~52K in Ca0.5Pr0.5FeAsF.Characterized by resistivity, susceptibility,XRD & EDX-SEM.Upper critical field estimated from magneto resistance.Bulk superconductivity proved by DC magnetization. Hall coefficient RH revealed hole-like charge carriers in parent compound CaFeAsF, while electron-type (RH in normal state is -Ve) for Ca0.5Pr0.5FeAsF.Evolution of Raman active phonons of Ca1-xPrxFeAsF measured with polarized Raman spectroscopy at room temperature from absurfaces of impurity-free microcrystals.Spectra exhibit sharp phonon lines on very weak electronic scattering background.Frequency and symmetry of Raman phonons involving out-of-plane atomic vibrations are found at 162.5 cm-1 (A1 g, Pr), 201 cm-1 (A1 g, As), 215.5 cm-1 (B1 g, Fe), 265 cm-1 (Eg, Fe) and 334 cm-1 (B1 g, F) for Ca0.5Pr0.5FeAsF.Observations are compared with RFeAsO unconventional superconductors also possibly related to magnetic fluctuations

  11. Growth of doped and pure monocrystalline fibers and gradient crystals of REMO{sub 4} compounds (RE = rare earths and M = Nb and Ta); Crescimento de fibras monocristalinas puras e dopadas, e cristais gradientes de compostos REMO{sub 4} (RE= terras raras e M = Nb e Ta)

    Energy Technology Data Exchange (ETDEWEB)

    Octaviano, E.S.; Levada, C.L.; Missiato, O., E-mail: esoctaviano@if.sc.usp.br [Academia da Forca Aerea, Campo Fontenelle, Pirassununga , SP (Brazil). Div. de Ensino; Semenzato, M.J.; Silva, R.A.; Andreeta, J.P. [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Fisica

    2009-07-01

    A desirable alternative for a faster development, characterization and application of material of technological interest has been the growth of single crystal fibers by LHPG - Laser Heated Pedestal Growth. In this work it was reported the growth of pure, doped and gradient single crystal fibers of the chemical formulation REMO{sub 4} (M = Nb e Ta, e RE= Rare Earth), characterized through primary techniques such as X-Ray and optical spectroscopy. (author)

  12. Modeling of optical amplifier waveguide based on silicon nanostructures and rare earth ions doped silica matrix gain media by a finite-difference time-domain method: comparison of achievable gain with Er3+ or Nd3+ ions dopants

    CERN Document Server

    Cardin, Julien; Dufour, Christian; Gourbilleau, Fabrice

    2015-01-01

    A comparative study of the gain achievement is performed in a waveguide optical amplifier whose active layer is constituted by a silica matrix containing silicon nanograins acting as sensitizer of either neodymium ions (Nd 3+) or erbium ions (Er 3+). Due to the large difference between population levels characteristic times (ms) and finite-difference time step (10 --17 s), the conventional auxiliary differential equation and finite-difference time-domain (ADE-FDTD) method is not appropriate to treat such systems. Consequently, a new two loops algorithm based on ADE-FDTD method is presented in order to model this waveguide optical amplifier. We investigate the steady states regime of both rare earth ions and silicon nanograins levels populations as well as the electromagnetic field for different pumping powers ranging from 1 to 10 4 mW.mm-2. Furthermore, the three dimensional distribution of achievable gain per unit length has been estimated in this pumping range. The Nd 3+ doped waveguide shows a higher gross...

  13. Research status of rare earth doped Mn-Zn ferrites synthesized by hydrothermal method%水热法制备稀土掺杂Mn-Zn铁氧体的研究现状

    Institute of Scientific and Technical Information of China (English)

    陈明洁; 庄琳; 沈辉

    2012-01-01

    The research status of Mn-Zn ferrites synthesized by hydrothermal method was summarized. The key factors of maintaining the initial stoichiometry and getting nanosized particles with narrow size distribution and perfect crystallization without impurity phase were discussed. Finally, according to the current research situation of rare earth doped Mn-Zn ferrite, the further research directions were proposed.%综述了水热法制备Mn-Zn铁氧体的研究现状,对制备出与初始化学计量一致、颗粒细小、尺寸分布窄且结晶程度好、没有杂相的纳米颗粒的关键合成条件进行了讨论.并针对目前的稀土掺杂Mn-Zn铁氧体微粉的研究现状,提出需要深入研究的几个方向.

  14. Analysis of electrical and microstructural characteristics of a ZnO-based varistor doped with rare earth oxide; Analise das caracteristicas microestruturais e eletricas de um varistor a base de ZnO dopado com oxidos de terras raras

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, J.M. de; Dias, R.; Furtado, J.G. de M. [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil); Assuncao, F.C.R. [Pontificia Univ. Catolica do Rio de Janeiro (PUC/Rio), RJ (Brazil)

    2010-07-01

    Varistor is a semiconductor device, used in the protection of electrical systems, characterized to have a high no-linear electric resistance. Its properties are directly dependents of its chemical composition and microstructural characteristics. In this work were analyzed microstructural and electrical characteristics of a ZnO-based varistor doped with rare earth oxide, with chemical composition (mol%) 98,5.ZnO - 0,3.Pr{sub 6}O{sub 11} - 0,2.Dy{sub 2}O{sub 3} - 0,9.Co{sub 2}O{sub 3} - 0,1.Cr{sub 2}O{sub 3}. X-ray diffraction for phase characterization, scanning electron microscopy and energy dispersive X-ray spectroscopy were used for microstructural analysis. Measurement of average grain size and electrical and dielectric characteristics complete the characterization. The results show the formation of biphasic microstructure and with high densification, presenting relevant varistors characteristics but that would need improvements.(author)

  15. Chemical environment of rare earth ions in Ge{sub 28.125}Ga{sub 6.25}S{sub 65.625} glass-ceramics doped with Dy{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Rongping, E-mail: rongping.wang@anu.edu.au; Yan, Kunlun; Luther-Davies, Barry [Centre for Ultrahigh bandwidth Devices for Optical Systems, Laser Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra ACT 2600 (Australia); Zhang, Mingjie; Yang, Anping; Zhang, Bin [Jiangsu Key Laboratory of Advanced Laser Materials and Devices, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou, Jiangsu 221116 (China); Shen, Xiang; Dai, Shixun [Laboratory of Infrared Material and Devices, The Advanced Technology Research Institute, Ningbo University, Ningbo 315211 (China); Yang, Xinyu [Faculty of Chemistry and Material Engineering, Wenzhou University, Wenzhou 325027 (China); Yang, Zhiyong [Centre for Ultrahigh bandwidth Devices for Optical Systems, Laser Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra ACT 2600 (Australia); Jiangsu Key Laboratory of Advanced Laser Materials and Devices, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou, Jiangsu 221116 (China)

    2015-10-19

    We have annealed Ge{sub 28.125}Ga{sub 6.25}S{sub 65.625} glasses doped with 0.5% Dy to create glass-ceramics in order to examine the local chemical environment of the rare earth ions (REI). More than 12 times enhancement of the emission at 2.9 and 3.5 μm was achieved in glass-ceramics produced using prolonged annealing time. Elemental mapping showed clear evidence that Ga{sub 2}S{sub 3} crystalline grains with a size of 50 nm were dispersed in a Ge-S glass matrix in the glass-ceramics, and the REI could only be found near the Ga{sub 2}S{sub 3} crystalline grains. From the unchanged lineshape of the emissions at 2.9 and 3.5 μm and lack of splitting of the absorption peaks, we concluded that the REI were bonded to Ga on the surface of the Ga{sub 2}S{sub 3} crystals.

  16. Magnetic and microwave absorption properties of rare earth ions (Sm3+, Er3+) doped strontium ferrite and its nanocomposites with polypyrrole

    Science.gov (United States)

    Luo, Juhua; Xu, Yang; Mao, Hongkai

    2015-05-01

    M-type strontium ferrite substituted by RE (RE=Sm3+, Er3+) were prepared via a sol-gel method. Polypyrrole (PPy)/ferrite nanocomposites (with 20 wt% ferrite) were prepared by in situ polymerization method in the presence of ammonium persulfate. Effect of the substituted RE ions on structure, magnetic properties and microwave absorption properties were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and vector network analyzer. All XRD patterns show the single phase of strontium hexaferrite without other intermediate phases. The crystallite size of synthesized particle is within the range of 22.2-38.1 nm. The structural in character of the composites were investigated with FT-IR analysis. It shows that the ferrite successfully packed by PPy. TEM photographs show that the particle size had grown up to 50-100 nm after coating with PPy. In the magnetization for the PPy/SrSm0.3Fe11.7O19 (SrEr0.3Fe11.7O19) composites, the coercivity (Hc) of the composites both increased compared with the undoped composite while the saturation magnetization (Ms) appeared opposite change with different RE ions. Considering the electromagnetic loss and impedance matching comprehensively, the Er-doped ferrite/PPy composite got the better microwave absorption performance with the maximum RL value of -24.01 dB in 13.8 GHz at 3.0 mm. And its width (<-10 dB) has reached 7.2 GHz which has covered the whole Ku band.

  17. Study of amorphous semiconductors doped with rare earths (Gd and Er) and conducting polymers by EPR techniques and magnetic susceptibility; Estudo de semicondutores amorfos dopados com terras raras (Gd e Er) e de polimeros condutores atraves das tecnicas de RPE e susceptibilidade magnetica

    Energy Technology Data Exchange (ETDEWEB)

    Sercheli, Mauricio da Silva

    1999-07-01

    This thesis involves the study of amorphous semiconductors and conducting polymers, which have been characterized by EPR and magnetic susceptibility measurements, and to a lesser extent by Raman spectroscopy and RBS. The semiconductors were studied using thin films of silicon doped with rare earth metals, e.g. erbium and gadolinium, which had their magnetic properties studied. Using these studies we could determine the state of valence of the rare earths as well as their concentrations in the silicon matrix. According to our results, the valence of the rare earth metal ions is 3+, and we were able to conclude that 4f electronic shells could not be used for the calculation of the conducting band in this system. Furthermore, the analysis of the data on the magnetic susceptibility of the Er{sup 3+} ion with cubic crystalline acting field, gave us the opportunity to estimate the overall splitting of their electronic states for the first time. The conducting polymers were studied using samples of poly(3-methylthiophene) doped with ClO{sub 4}{sup -}, which show a phase transition in the range of 230 K to 130 K. The electron paramagnetic resonance also gives important information on the crystallization, doping level and the presence of polarons or bipolarons in conducting polymers. (author)

  18. Study the structural and magnetic properties of rare-earth ions (La and Gd) doped Ba0.9575Ca0.0025Ti0.80685Mn0.002475Nb0.002475Zr0.1782O3 (BCTMNZ) ceramics

    Science.gov (United States)

    Rai, Radheshyam; Kumari, Poonam; Valente, M. A.

    2015-12-01

    In this paper, we investigated the influence of rare earth (RE=La and Gd) doped Ba0.9575RE0.04Ca0.0025Ti0.80685 Mn0.002475Nb0.002475Zr0.1782O3 (BCTMNZ) ceramics were fabricated by using a conventional solid-state reaction method. The doping effects of La and Gd on the structural and magnetic properties were studied. The structural pattern of the ceramic samples were investigated by X-ray diffraction and the results indicated that both samples shows an orthorhombic structure with pure phase. Strain and crystalline size values for Gd and La doped were 0.31-0.33% and 0.154-0.181μm, respectively. The room temperature hysteresis loops were obtained by using a vibrating sample magnetometer. La doped ceramic showed the higher value of magnetization i.e., 0.369μB/f.u. as compared to Gd doped BLTMNZ ceramics.

  19. Study on the Rare Earth Element and Lead Titanate Doping in Lead Magnesium Niobate Ceramics%铌镁酸铅陶瓷的稀土元素及钛酸铅互掺改性研究

    Institute of Scientific and Technical Information of China (English)

    李惠琴; 刘敬松

    2012-01-01

    本文采用了铌铁矿法,研究了稀土元素及钛酸铅(PT)的掺入对铌镁酸铅(PMN)铁电陶瓷的介电性能及拉曼行为的影响.分别掺入Y2O3 、Sin2O3、La2O3稀土氧化物后,PMN的介电常数峰值(εm)有所下降,而掺人PT后εm有所上升.稀土元素的掺人使相转变温度(Tm)朝远离居里点的低温方向移动,室温下的介电损耗值减小,介电常数频率稳定性得到增强.PT的掺入使Tm朝接近居里点的高温方向移动.拉曼光谱研究表明稀土元素、PT的掺人影响了PMN陶瓷的B位有序度,导致其介电性变化.%The columbite route was used in this work, and the influences of the addition of rare earth elements and PbTiO3 (PT) on the dielectric properties and Raman behavior of Pb( Mg1/3Nb2/3)O3 (PMN) ceramics were investigated. When Y2O3, Sm2O3 and La2O3 were added into PMN, the maximum of dielectric constant (εm) decreased. While PT was added, εm increased. The doping of rare earth elements resulted that the temperature of phase transition ( Tm) moves to lower temperature far away the Curie point and dissipation factor at room temperature decreased, and the frequency dependence of dielectric constant get stabilized. The addition of PT moved Tm to higher temperature near the Curie point. The Raman investigation on the influence of rare earth elements and PT addition revealed that the change of chemical degree of B-site resulted in the dielectric property change.

  20. Magnetic and microwave absorption properties of rare earth ions (Sm{sup 3+}, Er{sup 3+}) doped strontium ferrite and its nanocomposites with polypyrrole

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Juhua, E-mail: luojuhua@163.com [School of Materials Engineering, Yancheng Institute of Technology, Yancheng 224051 (China); Xu, Yang; Mao, Hongkai [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-05-01

    M-type strontium ferrite substituted by RE (RE=Sm{sup 3+}, Er{sup 3+}) were prepared via a sol–gel method. Polypyrrole (PPy)/ferrite nanocomposites (with 20 wt% ferrite) were prepared by in situ polymerization method in the presence of ammonium persulfate. Effect of the substituted RE ions on structure, magnetic properties and microwave absorption properties were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and vector network analyzer. All XRD patterns show the single phase of strontium hexaferrite without other intermediate phases. The crystallite size of synthesized particle is within the range of 22.2–38.1 nm. The structural in character of the composites were investigated with FT-IR analysis. It shows that the ferrite successfully packed by PPy. TEM photographs show that the particle size had grown up to 50–100 nm after coating with PPy. In the magnetization for the PPy/SrSm{sub 0.3}Fe{sub 11.7}O{sub 19} (SrEr{sub 0.3}Fe{sub 11.7}O{sub 19}) composites, the coercivity (H{sub c}) of the composites both increased compared with the undoped composite while the saturation magnetization (M{sub s}) appeared opposite change with different RE ions. Considering the electromagnetic loss and impedance matching comprehensively, the Er-doped ferrite/PPy composite got the better microwave absorption performance with the maximum RL value of −24.01 dB in 13.8 GHz at 3.0 mm. And its width (<−10 dB) has reached 7.2 GHz which has covered the whole Ku band. - Highlights: • The influence of RE ions on the structure of PPy/SrRE{sub 0.3}Fe{sub 11.7}O{sub 19} is discussed. • The influence of RE ions on the magnetic properties of PPy/SrRE{sub 0.3}Fe{sub 11.7}O{sub 19} is discussed. • The influence of RE ions on electromagnetic losses of PPy/SrRE{sub 0.3}Fe{sub 11.7}O{sub 19} is discussed. • PPy/SrEr{sub 0.3}Fe{sub 11.7}O{sub 19} possessed the excellent absorption property.

  1. Fullerene-C60 and crown ether doped on C60 sensors for high sensitive detection of alkali and alkaline earth cations

    Science.gov (United States)

    Zaghmarzi, Fatemeh Alipour; Zahedi, Mansour; Mola, Adeleh; Abedini, Saboora; Arshadi, Sattar; Ahmadzadeh, Saeed; Etminan, Nazanin; Younesi, Omran; Rahmanifar, Elham; Yoosefian, Mehdi

    2017-03-01

    Fullerenes are effective acceptor components with high electron affinity for charge transfer. The significant influences of chemical adsorption of the cations on the electrical sensitivity of pristine C60 and 15-(C2H4O)5/C60 nanocages could be the basis of new generation of electronic sensor design. The density functional theory calculation for alkali and alkaline earth cations detection by pristine C60 and 15-(C2H4O)5/C60 nanocages are considered at B3LYP level of theory with 6-31 G(d) basis set. The quantum theory of atoms in molecules analysis have been performed to understand the nature of intermolecular interactions between the cations and nanocages. Also, the natural bond orbital analysis have been performed to assess the intermolecular interactions in detail. Furthermore, the frontier molecular orbital, energy gap, work function, electronegativity, number of transferred electron (∆N), dipole moment as well as the related chemical hardness and softness are investigated and calculated in this study. The results show that the adsorption of cations (M=Na+, K+, Mg2+ and Ca2+) are exothermic and the binding energy in pristine C60 nanocage and 15-(C2H4O)5/C60 increases with respect to the cations charge. The results also denote a decrease in the energy gap and an increase in the electrical conductivity upon the adsorption process. In order to validate the obtained results, the density of state calculations are employed and presented in the end as well.

  2. 858nm激光激发下掺Nd3+氟化物陶瓷体上的转换发光研究%The influence of preparing process to up-conversion characteristics of rare earth doped ceramics

    Institute of Scientific and Technical Information of China (English)

    肖思国; 刘政威; 阳效良

    2001-01-01

    本文报道了三种方法制备的掺Nd3+氟化物烧结陶瓷体的上转换发光特性。不同的制备方法可以造成基质中稀土离子分布的不同。在一定条件下基质中可聚合形成合适的稀土离子的团簇,而稀土离子团簇的形成可以造成稀土离子间强烈的相互作用并导致了新颖的上转换通道的出现。%In this paper,the influence of different processes to up-conversion characteristics of Nd3+ doped materials has been reported.The difference of processes could cause the difference of the distribution of rare-earth ions in the host.Under certain circumstance,rare-earth clusters appear in thd host.The formation of rare-earth clusters brings about the interaction among rare-earth ions in the cluster,which results in the appearance of new up-conversion mechanism.The experiment results indicate that Nd3+ doped in suitable host could possess excellent up-conversion performance.

  3. First principles investigation of structural, electronic, elastic and thermal properties of rare-earth-doped titanate Ln2TiO5

    Directory of Open Access Journals (Sweden)

    Hui Niu

    2012-09-01

    Full Text Available Systematic first-principles calculations based on density functional theory were performed on a wide range of Ln2TiO5 compositions (Ln = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy and Y in order to investigate their structural, elastic, electronic, and thermal properties. At low temperature, these compounds crystallize in orthorhombic structures with a Pnma symmetry, and the calculated equilibrium structural parameters agree well with experimental results. A complete set of elastic parameters including elastic constants, Hill's bulk moduli, Young's moduli, shear moduli and Poisson's ratio were calculated. All Ln2TiO5 are ductile in nature. Analysis of densities of states and charge densities and electron localization functions suggests that the oxide bonds are highly ionic with some degree of covalency in the Ti-O bonds. Thermal properties including the mean sound velocity, Debye temperature, and minimum thermal conductivity were obtained from the elastic constants.

  4. Non-Linear Fibres for Widely Tunable Femtosecond Fibre Lasers

    DEFF Research Database (Denmark)

    Pedersen, Martin Erland Vestergaard

    This Ph.D. thesis investigates how intramodal and intermodal nonlinear processes in few-moded fibres can be used to generate light sources at wavelengths outside the spectral gain-bands of rare-earth-doped opticalfibres. The design of two specialty few-moded fibres for use in a widely tunable...... femtosecond fibre laser is presented. The two fibres are used to facilitate the shifting of a soliton in a cascade configuration from the ytterbium gain-band and to a wavelength of 1280 nm. The temporal pulse duration is on a femtosecond scale with a pulse energy of 5 nJ. The experimentally observed soliton...... self-frequency shift and thereby the outcome of the experimental demonstration of the widely tunable femtosecond fibre laser is shown to depend highly on the chirped of the input pulse into the first few-moded fibre in the cascade setup. Furthermore, an alternative splicing process, with a combination...

  5. Bioactivity of Gradient Rare Earths Bioceramic Coating Produced by Wide-Band Laser Cladding%宽带激光熔覆梯度稀土生物陶瓷涂层的生物活性

    Institute of Scientific and Technical Information of China (English)

    李明; 汪震

    2012-01-01

    To decrease thermal crack and to raise bonding strength between substrate and bioceramic coating during laser cladding, a kind of gradient rare earths bioceramics coating is designed. And the rare earth active gradient bioceramic coating with HA and β-TCP on Ti allloy was prepared by using wide-band laser cladding technique. The surface morphologies and microstructure were analyzed by OM, SEM and XRD; the bioceramic coating was immersed in SBF to examine its bioactivity ; and the corrosion resistance of bioceramic was examed by the Electrochemical Analyzer. Results show that the rare earth active bioceramic gradient coatings which have excellent chemical metallurgy bonding at the interface consists of substrate, alloying layer and bioceramic coating. When content of Nd2O3 is up to 0.6wt.%, the amount of HA+β — TCP catalyzed during wide-band laser cladding becomes largest. Bioactivity and corrosion resistance of bioceramic coating is dependent on the amount of HA + β—TCP catalyzed. The largest amount of apatite formed on the surface of gradient bioceramic coating is complied with 0.6wt.% Nd2O3. At the same time, the corrosion resistence is best.%为了减少激光熔覆过程中基材与生物陶瓷涂层之间的热裂纹,提高涂层与基材的结合强度,设计了一种梯度稀土生物陶瓷涂层,采用宽带激光熔覆技术,在TC4钛合金表面制备了含HA+β-TCP活性相的稀土活性梯度生物陶瓷复合涂层.利用SEM、XRD分析手段对涂层形貌、相组成进行了研究;通过模拟体液(SBF)浸泡实验(浸泡7、14 d)考察了生物陶瓷涂层的生物活性;利用电化学分析仪测试了生物活性陶瓷涂层的耐腐蚀性.结果表明,当稀土氧化物Nd2O3添加量为w(Nd2O3) =0.6%时,宽带激光熔覆过程中催化合成HA +3-TCP活性相的数量最多,具有优异的表面形貌;当稀土氧化物Nd2O3添加量为w(Nd2O3)=0.6%时,梯度稀土生物陶瓷涂层在SBF中浸泡不同时间点后表面沉

  6. Influence of Rare Earth Elements on Luminescent Properties of Y2SiO5:Tb

    Institute of Scientific and Technical Information of China (English)

    Jiao Huan; Liao Fuhui; Zhou Jingjing; Jing Xiping

    2005-01-01

    Photoluminescent(PL) and cathodoluminescent(CL) properties of rare earths (Sc3+, La3+, Gd3+ and Lu3+) doped (Y0.97Tb0.03)2SiO5 were studied. Rare earth doping clearly influences PL and CL properties of Y2SiO5:Tb. For La3+ doped system, PL intensity increases nearly 10% at x=0.05 whereas for Lu3+ doped system, the intensity increases about 20% at x=0.20. Gd3+ doping and Sc3+ doping reduce the intensity; at x=0.3, it is reduced about 30% for Gd3+ doped system and about 15% for Sc3+ doped system, respectively. Quenching concentration of activator became higher in rare earth doped samples, which may be understood by that the rare earth dopants might dilute the concentration of the activator. Additionally, doping also influences the color saturation of Y2SiO5:Tb. Sc3+, La3+, and Gd3+ doping improve the color saturation, whereas Lu3+ doping decreases the color saturation. CL measurements show that CL intensity increases for all rare earths doped systems. The energy transfer from Gd3+ to Tb3+ was discussed.

  7. Novel method for fabrication of metal- or oxide-nanoparticle doped silica-based specialty optical fibers

    Science.gov (United States)

    Lenardič, Borut; Kveder, Miha; Lisjak, Darja; Guillon, Herve; Bonnafous, Samuel

    2011-03-01

    Nanoparticle-doped optical fibers are causing significant scientific interest in different application fields. Nanoparticle-doping of silica glass layers during optical fiber preform fabrication was so far reported by sol-gel and solution doping processes, by flame hydrolysis spraying and by pulling hollow cylinders from nanoparticle suspensions. A new method for fabrication of high quality nanoparticle-doped fibers is suggested. Proposed method is based on "flash vaporization" deposition process, previously reported as method to fabricate rare earth- and metal ion-doped specialty optical fibers. Experiments were made where SiO2 layers were deposited using "flash vaporization"-equipped MCVD system, adding vapors carrying metal or oxide nanoparticles into deposition zone. Analysis of produced preforms confirms presence of nanoparticles in deposited layers, albeit with low deposition rate due to weak thermophoretic forces acting on very small particles or agglomerations. Based on results, a number of improvements were suggested and implemented in fabrication process, device design and choice of precursor materials. "Flash vaporization" method was demonstrated as suitable method for deposition of nanoparticles in silica layers, permitting in-situ fabrication of complete preforms, providing easy upgrade path for existing MCVD and OVD deposition systems and allowing simultaneous co-doping by a wide range of other co-dopants.

  8. Photo darkening of rare earth doped silica

    DEFF Research Database (Denmark)

    Mattsson, Kent Erik

    2011-01-01

    ). The displacive transition is initiated by a charge disproportionation process which leads to NBO transfer in forming dioxasilirane (2-fold coordinated silicon with two NBO attached) next to silylene (2-fold coordinated silicon with a lone electron pair). In collaboration with a valence electron of Yb 3+ a new 1...... transfer from type II oxygen deficiency centers ODC(II) to Tm3+ trace impurities. The ODC(II) is proposed to be the result of a displacive transition of a 4-fold silica ring hosting two 3-fold silicon units that presents two non-bridging oxygen to Yb3+ (as part of its 6-fold coordination by oxygen...

  9. A 23-dB bismuth-doped optical fiber amplifier for a 1700-nm band

    Science.gov (United States)

    Firstov, Sergei V.; Alyshev, Sergey V.; Riumkin, Konstantin E.; Khopin, Vladimir F.; Guryanov, Alexey N.; Melkumov, Mikhail A.; Dianov, Evgeny M.

    2016-06-01

    It is now almost twenty-five years since the first Erbium-Doped Fiber Amplifier (EDFA) was demonstrated. Currently, the EDFA is one of the most important elements widely used in different kinds of fiber-optic communication systems. However, driven by a constantly increasing demand, the network traffic, growing exponentially over decades, will lead to the overload of these systems (“capacity crunch”) because the operation of the EDFA is limited to a spectral region of 1530–1610 nm. It will require a search for new technologies and, in this respect, the development of optical amplifiers for new spectral regions can be a promising approach. Most of fiber-optic amplifiers are created using rare-earth-doped materials. As a result, wide bands in shorter (1150–1530 nm) and longer wavelength (1600–1750 nm) regions with respect to the gain band of Er-doped fibers are still uncovered. Here we report on the development of a novel fiber amplifier operating in a spectral region of 1640–1770 nm pumped by commercially available laser diodes at 1550 nm. This amplifier was realized using bismuth-doped high-germania silicate fibers fabricated by MCVD technique.

  10. Optical and structural characterization of the pure and doped BaY{sub 2}F{sub 8} with rare earths for application in radiation detectors and scintillators; Caracterizacao optica e estrutural do BaY{sub 2}F{sub 8} puro e dopado com terras raras visando aplicacao em detectores de radiacao e cintiladores

    Energy Technology Data Exchange (ETDEWEB)

    Mello, Ana Carolina Santana de

    2008-07-01

    In this work Barium Yttrium Fluoride (BaY{sub 2}F{sub 8} -BaYF) doped with different concentrations of ions Tb{sup 3+}, Er{sup 3+}, Tm{sup 3+} e Nd{sup 3+} were characterized, aiming the application in radiation detection devices that use the scintillating properties. Two types of samples were produced in the CLA-IPEN-SP, polycrystalline samples, obtained via solid state reaction of BaF{sub 2} and YF{sub 3} under HF atmosphere, and single crystals, obtained via the zone melting method also in a HF atmosphere. The samples were characterized using the following experimental techniques: X-ray powder diffraction, Radioluminescence (RL), Optical Absorption and Dispersive X-ray Absorption Spectroscopy (DXAS). The X-ray diffraction pattern showed the presence of the phase BaY{sub 2}F{sub 8} and a small amount of the phase Ba{sub 4}Y{sub 3}F{sub 17} in the polycrystalline pure and Tb{sup 3+}doped samples. The other samples showed only the desired BaY{sub 2}F{sub 8} phase. The radioluminescence measurements of the doped BaYF, when irradiated with X-rays, showed emission peaks in energies that are characteristics of the 4f-4f transitions of rare earths. The RL of the samples with 2 mol por cent and 3 mold of Tb{sup 3+}showed quite intense peaks with a maximum emission peak at 545 nm. The Tm{sup 3+}doped BYF showed that the scintillation efficiency is not directly proportional to the doping level, and the highest RL emission were obtained for the polycrystalline samples doped with 1 mol por cent, showing a maximum peak intensity at 456 nm (the blue region of the visible spectrum). All samples showed a phosphorescent decay time of the order of seconds. Single crystals of BaYF doped with 2 mol por cent of Er{sup 3+}, in addition to one of the highest phosphorescence time, presents a quite strong Rl in the green region of the spectra. The radiation damage was evaluated by the optical absorption techniques and the results showed that the formation of the absorption bands can be

  11. Expanding earth

    Energy Technology Data Exchange (ETDEWEB)

    Carey, S.W.

    1976-01-01

    Arguments in favor of an expanding earth are presented. The author believes that the theory of plate tectonics is a classic error in the history of geology. The case for the expanding earth is organized in the following way: introductory review - face of the earth, development of expanding earth concept, necessity for expansion, the subduction myth, and definitions; some principles - scale of tectonic phenomena, non-uniformitarianism, tectonic profile, paleomagnetism, asymmetry of the earth, rotation of the earth, and modes of crustal extension; regional studies - western North America, Central America, South-East Asia, and the rift oceans; tests and cause of expansion. 824 references, 197 figures, 11 tables. (RWR)

  12. Wide Area Thermal Processing of Light Emitting Materials

    Energy Technology Data Exchange (ETDEWEB)

    Duty, Chad E [ORNL; Joshi, Pooran C [ORNL; Jellison Jr, Gerald Earle [ORNL; Angelini, Joseph Attilio [ORNL; Sabau, Adrian S [ORNL

    2011-10-01

    Laboratory laser materials synthesis of wide bandgap materials has been successfully used to create white light emitting materials (LEMs). This technology development has progressed to the exploration on design and construction of apparatus for wide area doping and phase transformation of wide bandgap material substrates. The objective of this proposal is to develop concepts for wide area doping and phase transformation based on AppliCote Associates, LLC laser technology and ORNL high density pulsed plasma arc technology.

  13. 稀土对金属纳米粒子-介质复合薄膜(Ag-BaO)光电发射性能的增强%ENHANCED PHOTOEMISSION FROM METAL NANOPARTICLE COMPOSITE THIN FILMS (Ag-BaO) DOPED WITH RARE-EARTH ELEMENTS

    Institute of Scientific and Technical Information of China (English)

    许北雪; 吴锦雷; 刘惟敏; 杨海; 邵庆益; 刘盛; 薛增泉; 吴全德

    2001-01-01

    用真空蒸发沉积的方法制备了掺杂稀土的金属纳米粒子-介质复 合薄膜(Ag-BaO薄膜). 与不掺杂稀土的Ag-BaO薄膜相比,其光电发射能力提高了近40%. 透射电镜分析表明,掺杂稀土后,Ag-BaO薄膜中的Ag纳米粒子明显细化、球化、密度增大 . 这表明Ag纳米粒子的细化,使得其在光作用下,光电子更容易通过隧道效应穿过界面位垒 逸出,导致光电发射能力增强.%A metal nanoparticles-composite thin film (Ag-BaO), doped by rare-earth eleme nts, was g rown by vacuum deposition. Compared with the normal Ag-BaO thin film, the photo emission current of the doped Ag-BaO thin film increases by about 40%. The tran smi ssion electron micrograph indicated that Ag nanoparticles become smaller when do ped with rare-earth. With the smaller size of Ag nanoparticles, photoelect rons are eas ier to transgress from Ag nanoparticles via tunnel effect. Thus the photomission current increases.

  14. Lanthanide-doped CaS and SrS luminescent nanocrystals : A single-source precursor approach for doping

    NARCIS (Netherlands)

    Zhao, Yiming; Rabouw, Freddy T.; Puffelen, Tim Van; van Walree, Kees; Gamelin, Daniel R.; De Mello Donegá, Celso; Meijerink, A

    2014-01-01

    The incorporation of dopants with optical or magnetic functionalities into colloidal nanocrystals (NCs) has been a longstanding challenge for nanomaterial research. A deeper understanding of the doping kinetics will aid a better control of the doping process. In particular, alkaline-earth sulfides a

  15. 稀土掺杂对Li2O-Al2O3-SiO2微晶玻璃组织和光学性能的影响%Effect of rare earth doping on microstructure and optical properties of Li2O-Al2O3-SiO2 glass-ceramics

    Institute of Scientific and Technical Information of China (English)

    董伟; 卢金山

    2011-01-01

    通过熔融法制备了掺杂CeO2和Nd2O3的Li2O-Al2O3-SiO2(LAS)透明微晶玻璃,利用差热分析仪、X射线衍射仪、扫描电镜、紫外可见分光光度计等检测技术,研究稀土掺杂对Li2O-Al2O3-SiO2(LAS)玻璃析晶行为以及微晶玻璃的微观结构和光学性能的影响。稀土掺杂明显提高玻璃的析晶活化能和晶化温度,抑制了微晶玻璃由石英固溶体向锂辉石固溶体的转变,使LAS微晶玻璃的热稳定性增强。微晶玻璃晶化后紫外吸收边出现"红移",掺杂稀土的微晶玻璃晶粒出现细化。稀土离子的能级跃迁,导致微晶玻璃的颜色发生变%Transparent Li2O-Al2O3-SiO2(LAS) glass-ceramics doped with CeO2 and Nd2O3 were prepared by the melting method.The effects of rare earth ions on the crystallization behavior,microstructure and optical properties of Li2O-Al2O3-SiO2 glass-ceramics were studied by differential thermal analysis,X-ray diffraction,scanning electron microscopy and ultraviolet-visible spectroscopy.The results show that the activation energy of crystallization process and the crystallization temperature increases with rare earth doping,and the phase transition from β-quartz to β-spodumene is suppressed,and the thermal stability of glass-ceramics is enhanced.The UV absorption edge of LAS glass-ceramics is red-shifted compared to their parent glass.The grain refinement is observed with rare earth doping.The color of glass-ceramics is changed due to the energy-level transition of rare earth ions.The transmittance of LAS glass-ceramics is smaller than their parent glass,owing to light scattering by the grain boundary as well as the lattice absorption.

  16. Raman and Photoluminescence Spectroscopy of Er(3+) Doped Heavy Metal Oxide Glasses

    Science.gov (United States)

    Dyer, Keith; Pan, Zheng-Da; Morgan, Steve

    1997-01-01

    The potential applications of rare-earth ion doped materials include fiber lasers which can be pumped conveniently by infrared semiconductor laser diodes. The host material systems most widely studied are fluoride crystals and glasses because fluorides have low nonradiative relaxation rates due to their lower phonon energies. However, the mechanical strength, chemical durability and temperature stability of the oxide glasses are generally much better than fluoride glasses. The objective of this research was to investigate the optical and spectroscopic properties of Er(3+)-doped lead-germanate and lead-tellurium-germanate glasses. The maximum vibrational energy of lead-tellurium-germanate glasses are in the range of 740-820/cm, intermediate between those of silicate (1150/cm) and fluoride (530/cm) glasses.

  17. The psychology of doping.

    Science.gov (United States)

    Elbe, Anne-Marie; Barkoukis, Vassilis

    2017-08-01

    Doping is increasingly becoming a problem in both elite and recreational sports. It is therefore important to understand the psychological factors which can explain doping behavior in order to prevent it. The present paper briefly presents evidence on the prevalence of doping use in competitive sports and the measurement approaches to assess doping behavior and doping-related variables. Furthermore, the integrative theoretical approaches used to describe the psychological processes underlying doping use are discussed. Finally, the paper provides suggestions for appropriate measurement of doping behavior and doping-related variables, key preventive efforts against doping as well as avenues for future research. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Optical spectroscopy of erbium and thulium doped SnO glass ceramics

    OpenAIRE

    2003-01-01

    The advantages of multifunctional integrated optical components in planar devices are well known. For these devices to be small, a planar amplifier with high rare-earth solubility and photosensitivity would be highly desirable. Tin-doped silica has been found to have high negative photosensitivity, with excellent thermal stability. Optical spectroscopy has been carried out on a range of erbium- and thulium-doped tin-silicates, with rare earth doping levels from 200-10,000ppm and tin concentra...

  19. Luminescence efficiency growth in wide band gap semiconducting Bi2O3 doped Cd0.4Pb0.1B0.5 glasses and effect of γ-irradiation

    Science.gov (United States)

    Marzouk, M. A.; Ibrahim, S.; Hamdy, Y. M.

    2014-11-01

    Cadmium lead borate glasses together with other glasses containing different Bi2O3-doping concentrations (2.5, 5, 7.5, 10 mol%) were prepared by conventional melt annealing method. The density and molar volume values were calculated to obtain some insight on the packing density and arrangement in the network. Also their optical and structural properties have been characterized by means of X-ray diffraction, UV-visible spectroscopy, luminescence spectroscopy and FTIR spectroscopy. Optical measurements have been used to determine the optical band gap (Eg), Urbach energy (ΔE) and the refractive index (n). The results demonstrate the effective rule of Bi2O3 on the studied glasses. The undoped and Bi2O3 doped - glass show strong extended UV-near visible absorption bands which are attributed to the collective presence of both trace iron impurities from raw materials and also the sharing of bismuth Bi+3 ions. Furthermore, the luminescence intensity strongly increases with increasing Bi2O3 content which may be attributed to transfer of energy from transitions in its energy levels. It has been revealed that the decreasing values of optical band gap and band tail can be understood and related in terms of the structural changes that are taking place in the glass samples. The infrared absorption spectra of the prepared glasses show characteristic absorption bands related to the borate network (BO3, BO4 groups) together with vibrational modes due to Bi-O groups upon the introduction of Bi2O3. The prepared samples reveal a very limited response towards of gamma irradiation which reflects its shielding behavior towards the effect of such type of irradiation.

  20. Earth\\'s Mass Variability

    CERN Document Server

    Mawad, Ramy

    2014-01-01

    The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.

  1. [Doping, sport and addiction--any links?].

    Science.gov (United States)

    Foucart, J; Verbanck, P; Lebrun, P

    2015-01-01

    Sport is widely encouraged as it is beneficial for health. However, high-performance sport is more and more associated to rather suspicious practices; doping is one of the best example. From a physician point of view, the use of doping agents is obviously a major concern because taking such products often induce serious adverse effects on health. The present manuscript aims to inform physicians about the most frequent doping practices. It also points out that intensive sport can generate an "addictive" behavior sharing with "common"addictions a loss of practice control, a lack of interest in other activities and even a sport's practice detrimental to athlete's health. Analysis of the doping issue needs to take this reality into account as some doping products display an established " addictive" effect.

  2. Earth materials and earth dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, K; Shankland, T. [and others

    2000-11-01

    In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  3. Recent progress on the spectroscopy of rare earth ions in core-shells, nanowires, nanotubes, and other novel nanostructures.

    Science.gov (United States)

    Chen, Xueyuan; Liu, Liqin; Liu, Guokui

    2008-03-01

    Research and development of nanoscale luminescent and laser materials are part of the rapidly advancing nanoscience and nanotechnology. Because of unique spectroscopic properties and luminescent dynamics of f-electron states, doping luminescent rare earth ions into nano-hosts has been demonstrated as an optimistic approach to developing highly efficient and stable nanophosphors for various applications. In this article, we review the most recent progress in spectroscopic measurements of rare earth ion-activated low-dimensional nanostructures including nanolayers, core-shells, nanowires, nanotubes, and nanodisks. Among a large volume of work reported in the literature on many members of the rare earth series including Ce3+, Pr3+, Nd3+, Eu3+, and Er3+, we focus on recent findings in the spectroscopic and luminescence properties of Eu3+ doped nanolayers, core-shells, and nanotubes, because Eu3+ ions have been extensively studied and widely used as an ideal probe for fundamental understanding of nano-phenomena. Specifically, the dependence of the optical properties of rare earth ions on nanostructures is discussed in detail.

  4. Common Earth Science Misconceptions in Science Teaching

    Science.gov (United States)

    King, Chris

    2012-01-01

    A survey of the Earth science content of science textbooks found a wide range of misconceptions. These are discussed in this article with reference to the published literature on Earth science misconceptions. Most misconceptions occurred in the "sedimentary rocks and processes" and "Earth's structure and plate tectonics" categories; the most…

  5. Space-Based Erbium-Doped Fiber Amplifier Transmitters for Coherent, Ranging, 3D-Imaging, Altimetry, Topology, and Carbon Dioxide Lidar and Earth and Planetary Optical Laser Communications

    Science.gov (United States)

    Storm, Mark; Engin, Doruk; Mathason, Brian; Utano, Rich; Gupta, Shantanu

    2016-06-01

    This paper describes Fibertek, Inc.'s progress in developing space-qualified Erbium-doped fiber amplifier (EDFA) transmitters for laser communications and ranging/topology, and CO2 integrated path differential absorption (IPDA) lidar. High peak power (1 kW) and 6 W of average power supporting multiple communications formats has been demonstrated with 17% efficiency in a compact 3 kg package. The unit has been tested to Technology Readiness Level (TRL) 6 standards. A 20 W EDFA suitable for CO2 lidar has been demonstrated with ~14% efficiency (electrical to optical [e-o]) and its performance optimized for 1571 nm operation.

  6. Space-Based Erbium-Doped Fiber Amplifier Transmitters for Coherent, Ranging, 3D-Imaging, Altimetry, Topology, and Carbon Dioxide Lidar and Earth and Planetary Optical Laser Communications

    Directory of Open Access Journals (Sweden)

    Storm Mark

    2016-01-01

    Full Text Available This paper describes Fibertek, Inc.’s progress in developing space-qualified Erbium-doped fiber amplifier (EDFA transmitters for laser communications and ranging/topology, and CO2 integrated path differential absorption (IPDA lidar. High peak power (1 kW and 6 W of average power supporting multiple communications formats has been demonstrated with 17% efficiency in a compact 3 kg package. The unit has been tested to Technology Readiness Level (TRL 6 standards. A 20 W EDFA suitable for CO2 lidar has been demonstrated with ~14% efficiency (electrical to optical [e-o] and its performance optimized for 1571 nm operation.

  7. The Sun and Earth

    Science.gov (United States)

    Gopalswamy, Natchimuthuk

    2012-01-01

    Thus the Sun forms the basis for life on Earth via the black body radiation it emits. The Sun also emits mass in the form of the solar wind and the coronal mass ejections (CMEs). Mass emission also occurs in the form of solar energetic particles (SEPs), which happens during CMEs and solar flares. Both the mass and electromagnetic energy output of the Sun vary over a wide range of time scales, thus introducing disturbances on the space environment that extends from the Sun through the entire heliosphere including the magnetospheres and ionospheres of planets and moons of the solar system. Although our habitat is located in the neutral atmosphere of Earth, we are intimately connected to the non-neutral space environment starting from the ionosphere to the magnetosphere and to the vast interplanetary space. The variability of the solar mass emissions results in the interaction between the solar wind plasma and the magnetospheric plasma leading to huge disturbances in the geospace. The Sun ionizes our atmosphere and creates the ionosphere. The ionosphere can be severely disturbed by the transient energy input from solar flares and the solar wind during geomagnetic storms. The complex interplay between Earth's magnetic field and the solar magnetic field carried by the solar wind presents varying conditions that are both beneficial and hazardous to life on earth. This seminar presents some of the key aspects of this Sun-Earth connection that we have learned since the birth of space science as a scientific discipline some half a century ago.

  8. Thermal diffusion boron doping of single-crystal natural diamond

    Science.gov (United States)

    Seo, Jung-Hun; Wu, Henry; Mikael, Solomon; Mi, Hongyi; Blanchard, James P.; Venkataramanan, Giri; Zhou, Weidong; Gong, Shaoqin; Morgan, Dane; Ma, Zhenqiang

    2016-05-01

    With the best overall electronic and thermal properties, single crystal diamond (SCD) is the extreme wide bandgap material that is expected to revolutionize power electronics and radio-frequency electronics in the future. However, turning SCD into useful semiconductors requires overcoming doping challenges, as conventional substitutional doping techniques, such as thermal diffusion and ion implantation, are not easily applicable to SCD. Here we report a simple and easily accessible doping strategy demonstrating that electrically activated, substitutional doping in SCD without inducing graphitization transition or lattice damage can be readily realized with thermal diffusion at relatively low temperatures by using heavily doped Si nanomembranes as a unique dopant carrying medium. Atomistic simulations elucidate a vacancy exchange boron doping mechanism that occurs at the bonded interface between Si and diamond. We further demonstrate selectively doped high voltage diodes and half-wave rectifier circuits using such doped SCD. Our new doping strategy has established a reachable path toward using SCDs for future high voltage power conversion systems and for other novel diamond based electronic devices. The novel doping mechanism may find its critical use in other wide bandgap semiconductors.

  9. Snowball Earth

    OpenAIRE

    2016-01-01

    In the ongoing quest to better understand where life may exist elsewhere in the Universe, important lessons may be gained from our own planet. In particular, much can be learned from planetary glaciation events that Earth suffered ∼600 million years ago, so-called `Snowball Earth' episodes. I begin with an overview of how the climate works. This helps to explain how the ice-albedo feedback effect can destabilise a planet's climate. The process relies on lower temperatures causing more ice to ...

  10. Preparation and properties on rare-earth element cerium doped nano-titanium dioxide photocatalyst%Ce-TiO2光催化剂的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    燕宁宁; 张莹; 龚昌杰; 朱忠其; 柳清菊

    2012-01-01

    采用溶胶-凝胶法制备了稀土Ce离子掺杂的纳米TiO2光催化剂(Ce-TiO2),通过XRD、FT-IR、UV-Vis、PL、Nano-sizer纳米粒度分析仪等对Ce-TiO2样品进行了表征和分析,并以亚甲基蓝(MB)作为目标降解物,考察了不同掺杂浓度及经不同温度热处理后的Ce-TiO2样品对MB的光催化降解效果,结果表明所制备样品的晶型均为锐钛矿相和金红石相的混晶相,Ce离子的掺杂拓展了TiO2在可见光区的光谱响应范围,提高了TiO2光催化活性。当pH值为1.5,Ce的掺杂量为n(Ce)∶n(TiO2)=1∶300,热处理温度为600℃条件下制备的样品其催化活性显著高于Degussa P25。%The nano-TiO2 doped with Ce was prepared by sol-gel method.The samples were analyzed by X-ray diffraction(XRD),FT-IR,UV-Vis,PL,Nano-sizer nano particle size analyzer,etc.The photocatalytic activity of Ce-TiO2 was investigated at different doping dosage and different calcinated temperatures by measuring the degradation rate of methyl blue(MB) under the irradiation of fluorescent lamp,the results show that crystal phase of Ce-TiO2 samples are all mixed phase of anatase and rutile.The existence of the doped element Ce expands TiO2's spectrum absorption under the visible light,and increases the photocatalytic activity of TiO2.Meanwhile,the photocatalytic activity of the sample at pH=1.5,n(Ce)∶n(TiO2)=1∶300 and the calcinated temperature of 600℃ is the best,and it is obvious higher than that of P25.

  11. Digital Earth - A sustainable Earth

    Science.gov (United States)

    Mahavir

    2014-02-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

  12. Upconversion luminescence in Yb 3+-doped yttrium aluminum garnets

    Science.gov (United States)

    Xu, Xiaodong; Zhao, Zhiwei; Song, Pingxin; Jiang, Benxue; Zhou, Guoqing; Xu, Jun; Deng, Peizhen; Bourdet, Gilbert; Christophe Chanteloup, Jean; Zou, Ji-Ping; Fulop, Annabelle

    2005-03-01

    In this paper, we present results on upconversion luminescence performed on Yb 3+-doped yttrium aluminum garnets under 940 nm excitation. The upconversion luminescence was ascribed to Yb 3+ cooperative luminescence and the presence of rare earth impurity ions. The cooperative luminescence spectra as a function of Yb concentration were measured and the emission intensity variation with Yb concentration was discussed. Yb 3+ energy migration quenched the cooperative luminescence of Yb:YAG crystals with doping level over 15 at%.

  13. Preparation, Characterization, and Biotoxicity of Nanosized Doped ZnO Photocatalyst

    OpenAIRE

    Lingling Liu; XiangRui Wang; Xiuping Yang; Wenhong Fan; Xiaolong Wang; Ning Wang; Xiaomin Li; Feng Xue

    2014-01-01

    Metal-doped nanosized ZnO (nZnO) photocatalyst has been widely used for its typical properties and has thus gained considerable attention. In this study, five types of nZnO (nondoped nZnO, iron- (Fe-) doped nZnO, cobalt- (Co-) doped nZnO, nickel- (Ni-) doped nZnO, and manganese- (Mn-) doped nZnO) materials were prepared through a wet chemical method and then exposed to Daphnia magna (D. magna) at low and high concentrations (50 and 250 μg L−1). Results showed that the different metal-doped nZ...

  14. The interaction of a magnetic cloud with the Earth - Ionospheric convection in the Northern and Southern Hemispheres for a wide range of quasi-steady interplanetary magnetic field conditions

    Science.gov (United States)

    Freeman, M. P.; Farrugia, C. J.; Burlaga, L. F.; Hairston, M. R.; Greenspan, M. E.; Ruohoniemi, J. M.; Lepping, R. P.

    1993-01-01

    Observations are presented of the ionospheric convection in cross sections of the polar cap and auroral zone as part of the study of the interaction of the Earth's magnetosphere with the magnetic cloud of January 13-15, 1988. For strongly northward IMF, the convection in the Southern Hemisphere is characterized by a two-cell convection pattern comfined to high latitudes with sunward flow over the pole. The strength of the flows is comparable to that later seen under southward IMF. Superimposed on this convection pattern there are clear dawn-dusk asymmetries associated with a one-cell convection component whose sense depends on the polarity of the magnetic cloud's large east-west magnetic field component. When the cloud's magnetic field turns southward, the convection is characterized by a two-cell pattern extending to lower latitude with antisunward flow over the pole. There is no evident interhemispheric difference in the structure and strength of the convection. Superimposed dawn-dusk asymmetries in the flow patterns are observed which are only in part attributable to the east-west component of the magnetic field.

  15. Doped Colloidal ZnO Nanocrystals

    Directory of Open Access Journals (Sweden)

    Yizheng Jin

    2012-01-01

    Full Text Available Colloidal ZnO nanocrystals are promising for a wide range of applications due to the combination of unique multifunctional nature and remarkable solution processability. Doping is an effective approach of enhancing the properties of colloidal ZnO nanocrystals in well-controlled manners. In this paper, we analyzed two synthetic strategies for the doped colloidal ZnO nanocrystals, emphasizing our understanding on the critical factors associated with the high temperature and nonaqueous approach. Latest advances of three topics, bandgap engineering, n-type doping, and dilute magnetic semiconductors related to doped ZnO nanocrystals were discussed to reveal the effects of dopants on the properties of the nanocrystalline materials.

  16. [High-performance society and doping].

    Science.gov (United States)

    Gallien, C L

    2002-09-01

    Doping is not limited to high-level athletes. Likewise it is not limited to the field of sports activities. The doping phenomenon observed in sports actually reveals an underlying question concerning the notion of sports itself, and more widely, the society's conception of sports. In a high-performance society, which is also a high-risk society, doping behavior is observed in a large number of persons who may or may not participate in sports activities. The motivation is the search for individual success or profit. The fight against doping must therefore focus on individual responsibility and prevention in order to preserve athlete's health and maintain the ethical and educational value of sports activities.

  17. Erbium-doped nanoparticles in silica-based optical fibres

    CERN Document Server

    Blanc, Wilfried; Dussardier, Bernard; 10.1504/IJNT.2012.045350

    2012-01-01

    Developing of new rare-earth (RE)-doped optical fibres for power amplifiers and lasers requires continuous improvements in the fibre spectroscopic properties (like shape and width of the gain curve, optical quantum efficiency, resistance to spectral hole burning and photodarkening...). Silica glass as a host material for fibres has proved to be very attractive. However, some potential applications of RE-doped fibres suffer from limitations in terms of spectroscopic properties resulting from clustering or inappropriate local environment when doped into silica. To this aim, we present a new route to modify some spectroscopic properties of RE ions in silica-based fibres based on the incorporation of erbium ions in amorphous dielectric nanoparticles, grown in-situ in fibre preforms. By adding alkaline earth elements, in low concentration into silica, one can obtain a glass with an immiscibility gap. Then, phase separation occurs under an appropriate heat treatment. We investigated the role of three alkaline-earth...

  18. Influence of high magnetic field on the luminescence of Eu{sup 3+}-doped glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Wei; Chen, Weibo; Chen, Ping; Xu, Beibei; Zheng, Shuhong; Guo, Qiangbing; Liu, Xiaofeng, E-mail: xfliu@zju.edu.cn, E-mail: qjr@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang, Junpei; Han, Junbo [Wuhan National High Magnetic field Center, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Qiu, Jianrong, E-mail: xfliu@zju.edu.cn, E-mail: qjr@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, Guangdong 510640 (China)

    2014-09-28

    Rare earth (RE) doped materials have been widely exploited as the intriguing electronic configuration of RE ions offers diverse functionalities from optics to magnetism. However, the coupling of magnetism with photoluminescence (PL) in such materials has been rarely reported in spite of its fundamental significance. In the present paper, the effect of high pulsed magnetic field on the photoluminescence intensity of Eu{sup 3+}-doped nano-glass-ceramics has been investigated. In our experiment, Eu-doped oxyfluoride glass and glass ceramic were prepared by the conventional melt-quenching process and controlled heat treatment. The results demonstrate that the integrated PL intensity of Eu{sup 3+} decreases with the enhancement of magnetic field, which can be interpreted in terms of cooperation effect of Zeeman splitting and magnetic field induced change in site symmetry. Furthermore, as a result of Zeeman splitting, both blue and red shift in the emission peaks of Eu{sup 3+} can be observed, and this effect becomes more prominent with the increase of magnetic field. Possible mechanisms associated with the observed magneto-optical behaviors are suggested. The results of the present paper may open a new gate for modulation of luminescence by magnetic field and remote optical detection of magnetic field.

  19. Influence of high magnetic field on the luminescence of Eu3+-doped glass ceramics

    Science.gov (United States)

    Jiang, Wei; Zhang, Junpei; Chen, Weibo; Chen, Ping; Han, Junbo; Xu, Beibei; Zheng, Shuhong; Guo, Qiangbing; Liu, Xiaofeng; Qiu, Jianrong

    2014-09-01

    Rare earth (RE) doped materials have been widely exploited as the intriguing electronic configuration of RE ions offers diverse functionalities from optics to magnetism. However, the coupling of magnetism with photoluminescence (PL) in such materials has been rarely reported in spite of its fundamental significance. In the present paper, the effect of high pulsed magnetic field on the photoluminescence intensity of Eu3+-doped nano-glass-ceramics has been investigated. In our experiment, Eu-doped oxyfluoride glass and glass ceramic were prepared by the conventional melt-quenching process and controlled heat treatment. The results demonstrate that the integrated PL intensity of Eu3+ decreases with the enhancement of magnetic field, which can be interpreted in terms of cooperation effect of Zeeman splitting and magnetic field induced change in site symmetry. Furthermore, as a result of Zeeman splitting, both blue and red shift in the emission peaks of Eu3+ can be observed, and this effect becomes more prominent with the increase of magnetic field. Possible mechanisms associated with the observed magneto-optical behaviors are suggested. The results of the present paper may open a new gate for modulation of luminescence by magnetic field and remote optical detection of magnetic field.

  20. Erbium doped tellurite photonic crystal optical fiber

    Science.gov (United States)

    Osorio, Sergio P.; Fernandez, Enver; Rodriguez, Eugenio; Cesar, Carlos L.; Barbosa, Luiz C.

    2005-04-01

    In this work we present the fabrication of tellurite glass photonic crystal fiber doped with a very large erbium concentration. Tellurite glasses are important hosts for rare earth ions due to its very high solubility, which allows up to 10,000 ppm Er3+ concentrations. The photonic crystal optical fibers and tellurite glasses can be, therefore, combined in an efficient way to produce doped fibers for large bandwidth optical amplifiers. The preform was made of a 10 mm external diameter tellurite tube filled with an array of non-periodic tellurite capillaries and an erbium-doped telluride rod that constitute the fiber core. The preform was drawn in a Heathway Drawing Tower, producing fibers with diameters between 120 - 140 μm. We show optical microscope photography of the fiber"s transverse section. The ASE spectra obtained with a spectra analyzer show a red shift as the length of the optical fiber increases.

  1. 稀土金属 Dy 掺杂 TiO2光催化剂的制备及其对孔雀石绿降解性能的研究%Study on preparation of rare earth element dysprosium doped with TiO2 photocatalyst and its degradation property to malachite green

    Institute of Scientific and Technical Information of China (English)

    高航; 高梅; 李松田; 马威; 吴晓兵

    2015-01-01

    To improve the oxidation efficiency of heterogeneous photocatalysis,TiO2 doped by rare-earth elements was adopted. The results indicate that:there was red-shift adsorption spectra of synthetic product which could enhance malachite green oxidative decolorization effectively under the action of normal visible light. Due to Dy3 + -TiO2 doped photocatalyst,activation energy of photooxidation was decreased so that the efficiency of photolysis could be improved significantly. What’s more,the treatment of malachite green model wastewater with Dy3 + -TiO2 was studied and optimal conditions has been determined as follows:the concentration of malachite green is 20 mg / L,molar ratio of Dy-doping is 1. 5% . Under that reaction con-dition,after 150 min,the decolorization rates of malachite green will be over 60% .%采用稀土元素掺杂法制备改性的二氧化钛,以改善非均相光催化的氧化效率。研究结果表明,在掺杂镝元素之后,产物的吸收光谱发生了红移,在可见光作用下,可以有效地促进孔雀石绿的氧化脱色。引入掺杂型光催化剂 Dy3+-TiO2后,可降低光氧化体系所需的能量,提高光解效率。以孔雀石绿溶液作为模拟废水,考察了 Dy3+离子掺杂量、底物浓度等因素的影响,确定了优化的实验条件:在孔雀石绿的浓度为20 mg/ L,稀土元素 Dy 掺杂量为1.5%(摩尔比)时,反应150 min 后孔雀石绿脱色率达到60%以上。

  2. Electron-hole doping asymmetry of Fermi surface reconstructed in a simple Mott insulator.

    Science.gov (United States)

    Kawasugi, Yoshitaka; Seki, Kazuhiro; Edagawa, Yusuke; Sato, Yoshiaki; Pu, Jiang; Takenobu, Taishi; Yunoki, Seiji; Yamamoto, Hiroshi M; Kato, Reizo

    2016-08-05

    It is widely recognized that the effect of doping into a Mott insulator is complicated and unpredictable, as can be seen by examining the Hall coefficient in high Tc cuprates. The doping effect, including the electron-hole doping asymmetry, may be more straightforward in doped organic Mott insulators owing to their simple electronic structures. Here we investigate the doping asymmetry of an organic Mott insulator by carrying out electric-double-layer transistor measurements and using cluster perturbation theory. The calculations predict that strongly anisotropic suppression of the spectral weight results in the Fermi arc state under hole doping, while a relatively uniform spectral weight results in the emergence of a non-interacting-like Fermi surface (FS) in the electron-doped state. In accordance with the calculations, the experimentally observed Hall coefficients and resistivity anisotropy correspond to the pocket formed by the Fermi arcs under hole doping and to the non-interacting FS under electron doping.

  3. Earth Science Multimedia Theater

    Science.gov (United States)

    Hasler, A. F.

    1998-01-01

    The presentation will begin with the latest 1998 NASA Earth Science Vision for the next 25 years. A compilation of the 10 days of animations of Hurricane Georges which were supplied daily on NASA to Network television will be shown. NASA's visualizations of Hurricane Bonnie which appeared in the Sept 7 1998 issue of TIME magazine. Highlights will be shown from the NASA hurricane visualization resource video tape that has been used repeatedly this season on network TV. Results will be presented from a new paper on automatic wind measurements in Hurricane Luis from 1 -min GOES images that will appear in the October BAMS. The visualizations are produced by the Goddard Visualization & Analysis Laboratory, and Scientific Visualization Studio, as well as other Goddard and NASA groups using NASA, NOAA, ESA, and NASDA Earth science datasets. Visualizations will be shown from the "Digital-HyperRes-Panorama" Earth Science ETheater'98 recently presented in Tokyo, Paris and Phoenix. The presentation in Paris used a SGI/CRAY Onyx Infinite Reality Super Graphics Workstation at 2560 X 1024 resolution with dual synchronized video Epson 71 00 projectors on a 20ft wide screen. Earth Science Electronic Theater '999 is being prepared for a December 1 st showing at NASA HQ in Washington and January presentation at the AMS meetings in Dallas. The 1999 version of the Etheater will be triple wide with at resolution of 3840 X 1024 on a 60 ft wide screen. Visualizations will also be featured from the new Earth Today Exhibit which was opened by Vice President Gore on July 2, 1998 at the Smithsonian Air & Space Museum in Washington, as well as those presented for possible use at the American Museum of Natural History (NYC), Disney EPCOT, and other venues. New methods are demonstrated for visualizing, interpreting, comparing, organizing and analyzing immense Hyperimage remote sensing datasets and three dimensional numerical model results. We call the data from many new Earth sensing satellites

  4. Surface characterization and luminescence properties of AlN doped with RE elements (Sm, Ho, Gd, Tm)

    OpenAIRE

    Balogun, Ismail Ayodele

    2015-01-01

    Rare‐ earth (RE)‐doped III‐nitride broad band‐gap semiconductors have attracted enormous interest as a foundation for optoelectronics devices, which combine the unique luminescence feature of Rare‐earth ions with the electronic properties of the semiconductors. Recent progress toward nitride‐based light emitting diode and light emitting due to electric current devices have been made using crystalline and amorphous AlN and GaN doped with a different lanthanide elements. The Rare‐earth...

  5. Nanocrystalline Mg-doped Zinc Oxide Scintillator for UV detectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA uses detectors for a broad range of wavelengths from UV to gamma for applications in astrophysics, earth science, heliophysics, and planetary science. Mg-doped...

  6. Effect of molecular electrical doping on polyfuran based photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shuwen; Opitz, Andreas; Salzmann, Ingo, E-mail: ingo.salzmann@physik.hu-berlin.de [Humboldt-Universität zu Berlin, Institut für Physik and IRIS Adlershof, Brook-Taylor Straße 6, 12489 Berlin (Germany); Frisch, Johannes [Helmholtz-Zentrum für Materialien und Energie GmbH, Bereich Solarenergieforschung, Albert-Einstein-Straße 15, 12489 Berlin (Germany); Cohen, Erez; Bendikov, Michael [Department of Organic Chemistry, Weizmann Institute of Science, 76100 Rehovot (Israel); Koch, Norbert [Humboldt-Universität zu Berlin, Institut für Physik and IRIS Adlershof, Brook-Taylor Straße 6, 12489 Berlin (Germany); Helmholtz-Zentrum für Materialien und Energie GmbH, Bereich Solarenergieforschung, Albert-Einstein-Straße 15, 12489 Berlin (Germany)

    2015-05-18

    The electronic, optical, and morphological properties of molecularly p-doped polyfuran (PF) films were investigated over a wide range of doping ratio in order to explore the impact of doping in photovoltaic applications. We find evidence for integer-charge transfer between PF and the prototypical molecular p-dopant tetrafluoro-tetracyanoquinodimethane (F4TCNQ) and employed the doped polymer in bilayer organic solar cells using fullerene as acceptor. The conductivity increase in the PF films at dopant loadings ≤2% significantly enhances the short-circuit current of photovoltaic devices. For higher doping ratios, however, F4TCNQ is found to precipitate at the heterojunction between the doped donor polymer and the fullerene acceptor. Ultraviolet photoelectron spectroscopy reveals that its presence acts beneficial to the energy-level alignment by doubling the open-circuit voltage of solar cells from 0.2 V to ca. 0.4 V, as compared to pristine PF.

  7. Luminescent Thin Film of Doped Terbium Complex Obtained by Sol-Gel Method

    Institute of Scientific and Technical Information of China (English)

    刘丰祎; 符连社; 王俊; 李焕荣; 张洪杰

    2003-01-01

    The transparent luminescent thin films of doped terbium complex were obtained by sol-gel method. The result indicates that rare earth carboxylates with poor solubility can be homogeneously doped into sol matrix in situ. The fluorescence spectra show that the thin film material emits the characteristic narrow band emission of Tb3+ under the UV excitation.

  8. Er-doped concentric-cores optical fiber for simultaneous amplification and compensation of positive dispersion

    Institute of Scientific and Technical Information of China (English)

    Pramod R. Watekar; M. L. N. Goswami; H. N. Acharya; J. C. Biswas; B. P. Pal

    2004-01-01

    The Er-doped concentric-cores dispersion compensating fiber (EDDCF) has been demonstrated. The rare earth has been doped as a ring around the inner core. We have obtained 14-dB gain at 1550 nm (using the optical fiber network where amplification as well as negative dispersion are necessary.

  9. China's rare-earth industry

    Science.gov (United States)

    Tse, Pui-Kwan

    2011-01-01

    Introduction China's dominant position as the producer of over 95 percent of the world output of rare-earth minerals and rapid increases in the consumption of rare earths owing to the emergence of new clean-energy and defense-related technologies, combined with China's decisions to restrict exports of rare earths, have resulted in heightened concerns about the future availability of rare earths. As a result, industrial countries such as Japan, the United States, and countries of the European Union face tighter supplies and higher prices for rare earths. This paper briefly reviews China's rare-earth production, consumption, and reserves and the important policies and regulations regarding the production and trade of rare earths, including recently announced export quotas. The 15 lanthanide elements-lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium (atomic numbers 57-71)-were originally known as the rare earths from their occurrence in oxides mixtures. Recently, some researchers have included two other elements-scandium and yttrium-in their discussion of rare earths. Yttrium (atomic number 39), which lies above lanthanum in transition group III of the periodic table and has a similar 3+ ion with a noble gas core, has both atomic and ionic radii similar in size to those of terbium and dysprosium and is generally found in nature with lanthanides. Scandium (atomic number 21) has a smaller ionic radius than yttrium and the lanthanides, and its chemical behavior is intermediate between that of aluminum and the lanthanides. It is found in nature with the lanthanides and yttrium. Rare earths are used widely in high-technology and clean-energy products because they impart special properties of magnetism, luminescence, and strength. Rare earths are also used in weapon systems to obtain the same properties.

  10. Doping control in sport

    DEFF Research Database (Denmark)

    Overbye, Marie Birch

    2016-01-01

    Doping testing is a key component enforced by anti-doping authorities to detect and deter doping in sport. Policy is developed to protect athletes' right to participate in doping-free sport; and testing is a key tool to secure this right. Accordingly, athletes' responses to anti-doping efforts...... a web-based questionnaire (N = 645; response rate 43%) and uses qualitative findings to elaborate on and explain quantitative results. Results showed that two-thirds of the athletes reported the national testing programme in their sport to be appropriate. A majority of the athletes who had an opinion...

  11. The Earth's Biosphere

    Science.gov (United States)

    2002-01-01

    In the last five years, scientists have been able to monitor our changing planet in ways never before possible. The Sea-viewing Wide Field-of-View Sensor (SeaWiFS), aboard the OrbView-2 satellite, has given researchers an unprecedented view of the biological engine that drives life on Earth-the countless forms of plants that cover the land and fill the oceans. 'There is no question the Earth is changing. SeaWiFS has enabled us, for the first time, to monitor the biological consequences of that change-to see how the things we do, as well as natural variability, affect the Earth's ability to support life,' said Gene Carl Feldman, SeaWiFS project manager at NASA's Goddard Space Flight Center, Greenbelt, Md. SeaWiFS data, based on continuous daily global observations, have helped scientists make a more accurate assessment of the oceans' role in the global carbon cycle. The data provide a key parameter in a number of ecological and environmental studies as well as global climate-change modeling. The images of the Earth's changing land, ocean and atmosphere from SeaWiFS have documented many previously unrecognized phenomena. The image above shows the global biosphere from June 2002 measured by SeaWiFS. Data in the oceans is chlorophyll concentration, a measure of the amount of phytoplankton (microscopic plants) living in the ocean. On land SeaWiFS measures Normalized Difference Vegetation Index, an indication of the density of plant growth. For more information and images, read: SeaWiFS Sensor Marks Five Years Documenting Earth'S Dynamic Biosphere Image courtesy SeaWiFS project and copyright Orbimage.

  12. Effect of alkaline earth oxides on the physical and spectroscopic properties of Dy3+- doped Li2O-B2O3 glasses for white emitting material application

    Science.gov (United States)

    Shamshad, L.; Rooh, G.; Kirdsiri, K.; Srisittipokakun, N.; Damdee, B.; Kim, H. J.; Kaewkhao, J.

    2017-02-01

    Li2O-MO-B2O3:0.5Dy2O3 glasses mixed with four different alkaline earth modifier oxides MgO, CaO, SrO and BaO were synthesized by melt quench technique. Their physical properties like density, molar volume and refractive index were measured at room temperature and the effect of alkaline earth modifier oxides were studied. Also, optical absorption and photoluminescence spectra of these glasses have been acquired at room temperature. The Judd-Ofelt theory was effectively used to characterize these spectra and spectral intensities (ƒcal), Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6) and certain radiative properties have been determined. Radiative life-times (τR), branching ratios (βcal), and emission cross-sections (σp) and optical gain parameters (σp × τR) were calculated from the Judd-Ofelt intensity parameters and the variation in these parameters with the variation of glass matrix are discussed. Yellow/Blue (Y/B) ratio and chromacity color coordinates (x,y) are calculated from the emission spectra which indicates the white light generation from all the investigated samples. The correlated color temperature (CCT) for the studied glasses is found to be 4418 K. The fluorescence decay time (τexp) of the 4F9/2 level of Dy3+ has been measured from the decay profiles and compared with calculated lifetimes (τcal). Among all the studied glass matrices, the glass containing BaO exhibits high value of branching ratio, large emission cross-section and high optical gain parameter for 6F9/2 → 6H13 at 575 nm. The results indicates the suitability of all the studied glasses for laser action and white light generation.

  13. The Progress in Improving the Solar Cell Performance of Anti-reflection Film Doped with Rare-earth Eu Complexes%稀土铕配合物减反射层对提高太阳能电池效率的研究进展

    Institute of Scientific and Technical Information of China (English)

    赵峰; 梁妍; 赵旭

    2015-01-01

    The main limited factors of solar photoelectric conversion efficiency is its spectral sensitive area is narrow, most of the sunlight irradiation on the battery has failed to effectively converted into electricity. Rare-earth complexes doped into the anti-reflection film of solar cells,in order to improve the efficiency,is a research hotspot in the field of solar energy in recent years.Rare earth Eu3+ complexes not only make part of the ultraviolet and visible light to convert to a wavelength which is more suitable for solar cell absorption and utilization of 612 nm red band, also can effectively shield against ultraviolet light on solar cell.This paper mainly introduces the turn light mechanism of rare earth Eu3+and its complexes, and its research progress in solar cells decreased reflector.%限制太阳能电池光电转换效率的主要因素是其光谱敏感区域比较狭窄,照射在电池上的大部分太阳光没能有效地转换成电能.将稀土铕配合物掺杂入太阳能电池减反射层中以此来提高太阳能电池效率是近年来太阳能领域的研究热点.稀土铕配合物不仅使部分紫外及可见光转换为波长更适合太阳能电池吸收利用的612nm红光波段,还能有效屏蔽对太阳能电池不利的紫外光,如能将其合理有效地在太阳能电池中加以利用,势必会对太阳能电池的光电转换效率产生重要影响.本文主要介绍稀土铕元素及其配合物的转光机理和其在太阳能电池减反射层中的研究进展.

  14. High accuracy magnetic field sensors with wide operation temperature range

    Science.gov (United States)

    Vasil'evskii, I. S.; Vinichenko, A. N.; Rubakin, D. I.; Bolshakova, I. A.; Kargin, N. I.

    2016-10-01

    n+InAs(Si) epitaxial thin films heavily doped by silicon and Hall effect magnetic field sensors based on this structures have been fabricated and studied. We have demonstrated the successful formation of highly doped InAs thin films (∼100 nm) with the different intermediate layer arrangement and appropriate electron mobility values. Hall sensors performance parameters have been measured in wide temperature range. Obtained sensitivity varied from 1 to 40 Ω/T, while the best linearity and lower temperature coefficient have been found in the higher doped samples with lower electron mobility. We attribute this to the electron system degeneracy and decreased phonon contribution to electron mobility and resistance.

  15. Graphene doping methods and device applications.

    Science.gov (United States)

    Oh, Jong Sik; Kim, Kyong Nam; Yeom, Geun Young

    2014-02-01

    Graphene has recently been studied as a promising material to replace and enhance conventional electronic materials in various fields such as electronics, photovoltaics, sensors, etc. However, for the electronic applications of graphene prepared by various techniques such as chemical vapor deposition, chemical exfoliation, mechanical exfoliation, etc., critical limitations are found due to the defects in the graphene in addition to the absence of a semiconducting band gap. For that, many researchers have investigated the doped graphene which is effective to tailor its electronic property and chemical reactivity. This work presents a review of the various graphene doping methods and their device applications. As doping methods, direct synthesis method and post treatment method could be categorized. Because the latter case has been widely investigated and used in various electronic applications, we will focus on the post treatment method. Post treatment method could be further classified into wet and dry doping methods. In the case of wet doping, acid treatment, metal chloride, and organic material coating are the methods used to functionalize graphene by using dip-coating, spin coating, etc. Electron charge transfer achieved from graphene to dopants or from dopants to graphene makes p-type or n-type graphenes, respectively, with sheet resistance reduction effect. In the case of dry doping, it can be further categorized into electrostatic field method, evaporation method, thermal treatment method, plasma treatment method, etc. These doping techniques modify Fermi energy level of graphene and functionalize the property of graphene. Finally, some perspectives and device applications of doped graphene are also briefly discussed.

  16. Highly textured and transparent RF sputtered Eu2O3 doped ZnO films.

    Science.gov (United States)

    Sreedharan, Remadevi Sreeja; Ganesan, Vedachalaiyer; Sudarsanakumar, Chellappan Pillai; Bhavsar, Kaushalkumar; Prabhu, Radhakrishna; Mahadevan Pillai, Vellara Pappukutty Pillai

    2015-01-01

    Background : Zinc oxide (ZnO) is a wide, direct band gap II-VI oxide semiconductor. ZnO has large exciton binding energy at room temperature, and it is a good host material for obtaining visible and infrared emission of various rare-earth ions. Methods : Europium oxide (Eu2O3) doped ZnO films are prepared on quartz substrate using radio frequency (RF) magnetron sputtering with doping concentrations 0, 0.5, 1, 3 and 5 wt%. The films are annealed in air at a temperature of 773 K for 2 hours. The annealed films are characterized using X-ray diffraction (XRD), micro-Raman spectroscopy, atomic force microscopy, ultraviolet (UV)-visible spectroscopy and photoluminescence (PL) spectroscopy. Results : XRD patterns show that the films are highly c-axis oriented exhibiting hexagonalwurtzite structure of ZnO. Particle size calculations using Debye-Scherrer formula show that average crystalline size is in the range 15-22 nm showing the nanostructured nature of the films. The observation of low- and high-frequency E2 modes in the Raman spectra supports the hexagonal wurtzite structure of ZnO in the films. The surface morphology of the Eu2O3 doped films presents dense distribution of grains. The films show good transparency in the visible region. The band gaps of the films are evaluated using Tauc plot model. Optical constants such as refractive index, dielectric constant, loss factor, and so on are calculated using the transmittance data. The PL spectra show both UV and visible emissions. Conclusion : Highly textured, transparent, luminescent Eu2O3 doped ZnO films have been synthesized using RF magnetron sputtering. The good optical and structural properties and intense luminescence in the ultraviolet and visible regions from the films suggest their suitability for optoelectronic applications.

  17. Highly textured and transparent RF sputtered Eu2O3 doped ZnO films

    Directory of Open Access Journals (Sweden)

    Remadevi Sreeja Sreedharan

    2015-03-01

    Full Text Available Background: Zinc oxide (ZnO is a wide, direct band gap II-VI oxide semiconductor. ZnO has large exciton binding energy at room temperature, and it is a good host material for obtaining visible and infrared emission of various rare-earth ions. Methods: Europium oxide (Eu2O3 doped ZnO films are prepared on quartz substrate using radio frequency (RF magnetron sputtering with doping concentrations 0, 0.5, 1, 3 and 5 wt%. The films are annealed in air at a temperature of 773 K for 2 hours. The annealed films are characterized using X-ray diffraction (XRD, micro-Raman spectroscopy, atomic force microscopy, ultraviolet (UV-visible spectroscopy and photoluminescence (PL spectroscopy. Results: XRD patterns show that the films are highly c-axis oriented exhibiting hexagonalwurtzite structure of ZnO. Particle size calculations using Debye-Scherrer formula show that average crystalline size is in the range 15–22 nm showing the nanostructured nature of the films. The observation of low- and high-frequency E2 modes in the Raman spectra supports the hexagonal wurtzite structure of ZnO in the films. The surface morphology of the Eu2O3 doped films presents dense distribution of grains. The films show good transparency in the visible region. The band gaps of the films are evaluated using Tauc plot model. Optical constants such as refractive index, dielectric constant, loss factor, and so on are calculated using the transmittance data. The PL spectra show both UV and visible emissions. Conclusion: Highly textured, transparent, luminescent Eu2O3 doped ZnO films have been synthesized using RF magnetron sputtering. The good optical and structural properties and intense luminescence in the ultraviolet and visible regions from the films suggest their suitability for optoelectronic applications.

  18. Sulfur Earth

    Science.gov (United States)

    de Jong, B. H.

    2007-12-01

    Variations in surface tension affect the buoyancy of objects floating in a liquid. Thus an object floating in water will sink deeper in the presence of dishwater fluid. This is a very minor but measurable effect. It causes for instance ducks to drown in aqueous solutions with added surfactant. The surface tension of liquid iron is very strongly affected by the presence of sulfur which acts as a surfactant in this system varying between 1.9 and 0.4 N/m at 10 mass percent Sulfur (Lee & Morita (2002), This last value is inferred to be the maximum value for Sulfur inferred to be present in the liquid outer core. Venting of Sulfur from the liquid core manifests itself on the Earth surface by the 105 to 106 ton of sulfur vented into the atmosphere annually (Wedepohl, 1984). Inspection of surface Sulfur emission indicates that venting is non-homogeneously distributed over the Earth's surface. The implication of such large variation in surface tension in the liquid outer core are that at locally low Sulfur concentration, the liquid outer core does not wet the predominantly MgSiO3 matrix with which it is in contact. However at a local high in Sulfur, the liquid outer core wets this matrix which in the fluid state has a surface tension of 0.4 N/m (Bansal & Doremus, 1986), couples with it, and causes it to sink. This differential and diapiric movement is transmitted through the essentially brittle mantle (1024 Pa.s, Lambeck & Johnson, 1998; the maximum value for ice being about 1030 Pa.s at 0 K, in all likely hood representing an upper bound of viscosity for all materials) and manifests itself on the surface by the roughly 20 km differentiation, about 0.1 % of the total mantle thickness, between topographical heights and lows with concomitant lateral movement in the crust and upper mantle resulting in thin skin tectonics. The brittle nature of the medium though which this movement is transmitted suggests that the extremes in topography of the D" layer are similar in range to

  19. The Greatest Shadow on Earth

    Science.gov (United States)

    Hughes, Stephen; Wimmer, Jason; Towsey, Michael; Fahmi, Marco; Winslett, Greg; Dubler, Gabriel; Le Prou, Angela; Loose, David

    2014-01-01

    In a total solar eclipse, the Moon completely covers the Sun, casting a shadow several hundred km wide across the face of the Earth. This paper describes observations of the 14 November 2012 total eclipse of the Sun visible from north Queensland, Australia. The edge of the umbra was captured on video during totality, and this video is provided for…

  20. The Anti-Doping Movement.

    Science.gov (United States)

    Willick, Stuart E; Miller, Geoffrey D; Eichner, Daniel

    2016-03-01

    Historical reports of doping in sports date as far back as the ancient Greek Olympic Games. The anti-doping community considers doping in sports to be cheating and a violation of the spirit of sport. During the past century, there has been an increasing awareness of the extent of doping in sports and the health risks of doping. In response, the anti-doping movement has endeavored to educate athletes and others about the health risks of doping and promote a level playing field. Doping control is now undertaken in most countries around the world and at most elite sports competitions. As athletes have found new ways to dope, however, the anti-doping community has endeavored to strengthen its educational and deterrence efforts. It is incumbent upon sports medicine professionals to understand the health risks of doping and all doping control processes.

  1. Polarization induced doped transistor

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Huili (Grace); Jena, Debdeep; Nomoto, Kazuki; Song, Bo; Zhu, Mingda; Hu, Zongyang

    2016-06-07

    A nitride-based field effect transistor (FET) comprises a compositionally graded and polarization induced doped p-layer underlying at least one gate contact and a compositionally graded and doped n-channel underlying a source contact. The n-channel is converted from the p-layer to the n-channel by ion implantation, a buffer underlies the doped p-layer and the n-channel, and a drain underlies the buffer.

  2. Earth current monitoring circuit for inductive loads

    CERN Document Server

    Montabonnet, V; Thurel, Y; Cussac, P

    2010-01-01

    The search for higher magnetic fields in particle accelerators increasingly demands the use of superconducting magnets. This magnet technology has a large amount of magnetic energy storage during operation at relatively high currents. As such, many monitoring and protection systems are required to safely operate the magnet, including the monitoring of any leakage of current to earth in the superconducting magnet that indicates a failure of the insulation to earth. At low amplitude, the earth leakage current affects the magnetic field precision. At a higher level, the earth leakage current can additionally generate local losses which may definitively damage the magnet or its instrumentation. This paper presents an active earth fault current monitoring circuit, widely deployed in the converters for the CERN Large Hadron Collider (LHC) superconducting magnets. The circuit allows the detection of earth faults before energising the circuit as well as limiting any eventual earth fault current. The electrical stress...

  3. The Dope Stops Here

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Beijing has been making preparations to present a dope-free Olympics next yearThe China Anti-Doping Agency,set up to replace the 17-year-old China Doping Control Center,was offi- cially unveiled in Beijing on November 12.Between July 27 next year,when the Olympic Village is opened to athletes,and August 24,the last day of the Olympic Games,a total of 4,500 doping tests will be conducted in the build- ing.This number is 25 percent higher than that of the Athens Olympic Games in 2004 and 63 percent higher than at the Sydney Olympics in 2000.

  4. Er doped oxide nanoparticles in silica based optical fibres

    CERN Document Server

    Blanc, Wilfried; Paul, M C

    2009-01-01

    Erbium doped materials are of great interest in optical telecommunications due to the Er3+ intra-4f emission at 1.54 ?m. Erbium doped fibre amplifiers (EDFA) were developed in silica glass because of the low losses at this wavelength and the reliability of this glass. Developments of new rare earth doped fibre amplifiers aim to control their spectroscopic properties including shape and width of the gain curve and optical quantum efficiency. Standard silica glass modifiers, such as aluminium, result in very good properties in current EDFA. However, for more drastic spectroscopic changes, more important modifications of the rare earth ions local environment are required. To address this aim, we present a fibre fabrication route creating rare earth doped calcia?silica or calcia?phosphosilica nanoparticles embedded in silica glass. By adding alkaline earth elements such as calcium, in low concentration, one can obtain a glass with an immisci- bility gap so that phase separation occurs with an appropriate heat tre...

  5. 碱土、稀土元素掺杂对Y(VP)O4:Eu3+荧光粉发光性能的影响%Luminescence Propertyes of Y(VP)O4:Eu3+ Luminescence Properties of Y(VP)O4:Eu3+ Phosphor Doped with Alkali Earths and Rare Earths

    Institute of Scientific and Technical Information of China (English)

    谢晔; 王涛; 王海波

    2011-01-01

    High brightness red phosphor Yax ( VP)O4 : Eu3+ and Y0.94Lny ( VP) O4 :Ey0.063+ (A = Mg, Ca,Sr,Ba;Ln = La,Ga) particles were prepared by coprecipitation process. The sample was investigated by X-ray diffraction (XRD) , scanning electron microscope (SEM) , excitation spectra and emission spectra. The particles were spherical shape. Aggregation between particles was not observed. The phosphor particles had very high emission intensity. The main excitation peak of the particles was 300 nm. The main peak for the emission spectra was 620 nm. Emission intensity of Yax (VP)O4: Eu3+ phosphor doped with little Sr and Ba could be improved. Emission intensity of Yax (VP) O4: Eu3+ phosphor showed a decreasing trend with Ca and Mg. Emission intensity of Y0.94-yLny (VP)O4: Eu0.063+ (Ln = La,Ga) could be improved evidently when doped with La3+ and Ga3+. The phosphor showed red emission with good color purity under 300 nm light excitation. This phosphor is a good substitution for (Y, Gd) BO3 : Eu3+ in PDP.%采用共沉淀法制备了高亮度红色荧光粉YAx(VP)O4:Eu3+、Y0.94-Lny(VP)O4:Eu0.06(3+)(A=Mg,Ca,Sr,Ba;Ln=La,Ga),通过X射线衍射(XRD)、扫描电镜(SEM)、荧光光谱分析仪等测试方法对样品进行了研究.结果表明:选择合适的实验条件,可以制得颗粒分布均匀、表面光滑的Y(VP)O4:Eu3+荧光粉,其发射峰位于620 nm,是现有PDP商品(Y,Gd)BO3:Eu3+荧光粉的良好替代品.

  6. Characterisation and behaviour under irradiation of rare-earth doped powellite phases - Application to the long term behaviour of nuclear waste matrices; Caracterisation et comportement sous irradiation de phases powellites dopees terres rares - Application au comportement a long terme des matrices de confinement des dechets nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, C.

    2010-09-15

    This work deals with the behaviour under irradiation of a glass-ceramic made after heat treatment of a molybdenum rich R7/T7 type glass. Rare earth elements (Eu{sup 3+} and Nd{sup 3+}) are used as surrogates of minor actinides and fission products as well as structural luminescent probes. We will focus on the behaviour of the crystalline phase which is a powellite type calcium molybdate that incorporated other elements including rare earth elements. In order to determine the crystalline-chemical properties of the powellite structure, Raman spectroscopy and photoluminescence analyses are led on natural powellite samples and synthetic ceramics with compositions from pure CaMoO{sub 4} to Ca{sub 0.76}Sr{sub 0.1}Na{sub 0.07}Eu{sub 0.01}La{sub 0.02}Nd{sub 0.02}Pr{sub 0.02}MoO{sub 4}, a model composition of the crystalline phase of the glass-ceramic. The analyses of synthetic samples irradiated with He, Ar and Pb ions compared to the behaviour of a natural powellite sample that contains uranium indicate that powellite resist strongly to irradiation and never reach the amorphous state. (author)

  7. Nanoscale imaging of freestanding nitrogen doped single layer graphene.

    Science.gov (United States)

    Iyer, Ganjigunte R S; Wang, Jian; Wells, Garth; Bradley, Michael P; Borondics, Ferenc

    2015-02-14

    Graphene can be p-type or n-type doped by introduction of specific species. Doping can modulate the electronic properties of graphene, but opening a sizable-well-tuned bandgap is essential for graphene-based tunable electronic devices. N-doped graphene is widely used for device applications and is mostly achieved by introducing ammonia into the synthesis gas during the chemical vapor deposition (CVD) process. Post synthesis treatment studies to fine-tune the electron hole doping in graphene are limited. In this work realization of N-doping in large area freestanding single layer graphene (LFG) is achieved by post treatment in nitrogen plasma. The changes in the chemical and electronic properties of graphene are followed with Raman microscopy and mapped via synchrotron based scanning transmission X-ray microscopy (STXM) at the nanoscale.

  8. To dope or not to dope

    DEFF Research Database (Denmark)

    Overbye, Marie Birch; Knudsen, Mette Lykke; Pfister, Gertrud Ursula

    2013-01-01

    tAim: This study aims to examine the circumstances which athletes say affect their (hypothetical) consid-erations of whether to dope or not and explore the differences between athletes of different gender, ageand sport type.Methods: 645 elite athletes (mean age: 22.12; response rate: 43%) represe......tAim: This study aims to examine the circumstances which athletes say affect their (hypothetical) consid-erations of whether to dope or not and explore the differences between athletes of different gender, ageand sport type.Methods: 645 elite athletes (mean age: 22.12; response rate: 43......%) representing 40 sports completed aweb-based questionnaire. Participants were asked to imagine themselves in a situation in which theyhad to decide whether to dope or not to dope and then evaluate how different circumstances would affecttheir decisions.Results: Multiple circumstances had an effect on athletes......’ hypothetical decisions. The most effective deter-rents were related to legal and social sanctions, side-effects and moral considerations. Female athletesand younger athletes evaluated more reasons as deterrents than older, male athletes. When confrontedwith incentives to dope, the type of sport was often...

  9. 二价碱土金属氟化物对Er3+/Tm3+/Yb3+共掺氟氧锗酸盐玻璃热稳定性和光谱特性影响的研究%Effect of Bivalent Alkaline Earth Fluorides Introduction on Thermal Stability and Spectroscopic Properties of Er3+/Tm3+/Yb3+ Co-Doped Oxyfluorogermanate Glasses

    Institute of Scientific and Technical Information of China (English)

    胡曰博; 张新娜; 周大利; 焦清; 王荣飞; 黄劲峰; 龙晓波; 邱建备

    2012-01-01

    制备了分别含有MgF2,CaF2,SrF2或BaF2的Er3+/Tm3+/Yb3+共掺氟氧锗酸盐玻璃试样和包含BaF2纳米晶的玻璃陶瓷试样,所制备试样均具有良好的透光性.对试样的热稳定性和上转换发光特性进行了研究.通过分析试样的吸收光谱发现,随着所含二价阳离子原子量的增大,试样的紫外吸收截止波长明显向短波方向移动.结果显示:通过改变所含二价碱土金属离子的种类能够对激发光的颜色进行调节,特别值得关注的是Mg2+的影响;结果证实:通过对包含二价碱土金属的玻璃进行微晶化处理或者增加二价碱土金属的含量均能提高上转换发光的强度.%Transparent Er3+ /Tm3+ /Yb3+ co-doped oxyfluorogermanate glasses alone containing MgF2, CaF2, SrF2 or BaF2 and nano-glass-ceramics only containing BaF2 were prepared. The thermal stabilities and the up-conversion emission properties of the samples were investigated. Analyses of absorbance spectra reveal that the UV cutoff band moves slightly to shortwave band with the doping bivalent cation mass increasing. The results show that the emission color can be adjusted by changing the alkaline earth cation species in the glass matrixes, especially as Mg2+ is concerned, and the emission intensity can increase notably by heating the glass containing alkaline-earth fluoride into glass ceramic containing alkaline-earth fluoride nanocrystals or increasing the content of bivalent alkaline earth fluorides.

  10. Estudo da sinterização da zircônia dopada com óxidos de terras raras a 5 GPa de pressão Sintering of rare earth-doped zirconia under 5 GPa pressure

    Directory of Open Access Journals (Sweden)

    C. Kuranaga

    2005-06-01

    Full Text Available A zircônia (ZrO2 tem mostrado grande destaque entre as cerâmicas avançadas, atraindo muito o interesse de pesquisadores em seus vários campos de atuação. A zircônia apresenta elevada resistência quando na fase tetragonal, mas a fase estável a temperatura ambiente é a monoclínica, sendo necessário o uso de estabilizantes para a fase tetragonal. Neste trabalho propomos a sinterização rápida da zircônia parcialmente estabilizada com óxidos de terras raras (ZrO2-OTR, mediante o emprego da alta pressão de 5 GPa. As condições de sinterização realizadas neste trabalho são inovadoras, haja visto que utilizou-se de tecnologia alternativa para processar a ZrO2-OTR, chamada de altas temperaturas e altas pressões (HPHT. Foi utilizada uma pressão de 5 GPa, temperaturas de 1100, 1200 e 1300 ºC nos tempos de 2 e 5 min. O melhor resultado foi obtido nas amostras sinterizadas a 5 GPa/1300 ºC/5 min, onde apresentaram microdureza média de 488,73 kgf/mm², para uma tenacidade à fratura de 5,33 MPa.m½, as quais apresentaram densidade da ordem de 97,88% da teórica, e 88% em volume de fase tetragonal retida à temperatura ambiente.Zirconia (ZrO2 has shown great projection among the advanced ceramics, attracting the interest of researchers in its various fields of application. Tetragonal zirconia presents high mechanical strength, but the room temperature stable phase is the monoclinic, being necessary the use of stabilizers for obtaining the tetragonal phase. In this work the rapid sintering of zirconia partially stabilized with rare earth oxides (ZrO2-OTR, via 5 GPa high pressure is proposed. The sintering conditions employed in this work are innovative, due to the use of an alternative technology to process ZrO2-OTR, so called high temperature - high pressure (HPHT. A pressure of 5 GPa and temperatures of 1100, 1200 and 1300 ºC for times of 2 and 5 min were used. The best results were obtained for samples sintered at 5 GPa at 1300 º

  11. Systematic hardness measurements on some rare earth garnet crystals

    Indian Academy of Sciences (India)

    D B Sirdeshmukh; L Sirdeshmukh; K G Subhadra; K Kishan Rao; S Bal Laxman

    2001-10-01

    Microhardness measurements were undertaken on twelve rare earth garnet crystals. In yttrium aluminium garnet and gadolinium gallium garnet, there was no measurable difference in the hardness values of pure and nominally Nd-doped crystals. The hardness values were correlated with the lattice and elastic constants. An analysis of hardness data in terms of the interatomic binding indicated a high degree of covalency.

  12. Nanoscale imaging of freestanding nitrogen doped single layer graphene

    Science.gov (United States)

    Iyer, Ganjigunte R. S.; Wang, Jian; Wells, Garth; Bradley, Michael P.; Borondics, Ferenc

    2015-01-01

    Graphene can be p-type or n-type doped by introduction of specific species. Doping can modulate the electronic properties of graphene, but opening a sizable-well-tuned bandgap is essential for graphene-based tunable electronic devices. N-doped graphene is widely used for device applications and is mostly achieved by introducing ammonia into the synthesis gas during the chemical vapor deposition (CVD) process. Post synthesis treatment studies to fine-tune the electron hole doping in graphene are limited. In this work realization of N-doping in large area freestanding single layer graphene (LFG) is achieved by post treatment in nitrogen plasma. The changes in the chemical and electronic properties of graphene are followed with Raman microscopy and mapped via synchrotron based scanning transmission X-ray microscopy (STXM) at the nanoscale.Graphene can be p-type or n-type doped by introduction of specific species. Doping can modulate the electronic properties of graphene, but opening a sizable-well-tuned bandgap is essential for graphene-based tunable electronic devices. N-doped graphene is widely used for device applications and is mostly achieved by introducing ammonia into the synthesis gas during the chemical vapor deposition (CVD) process. Post synthesis treatment studies to fine-tune the electron hole doping in graphene are limited. In this work realization of N-doping in large area freestanding single layer graphene (LFG) is achieved by post treatment in nitrogen plasma. The changes in the chemical and electronic properties of graphene are followed with Raman microscopy and mapped via synchrotron based scanning transmission X-ray microscopy (STXM) at the nanoscale. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05385k

  13. Structural and AC loss study for pure and doped MgB{sub 2} superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Hansdah, J. S.; Sarun, P. M., E-mail: sarun.res@gmail.com [Functional Ceramics Lab, Department of Applied Physics, Indian School of Mines (ISM), Dhanbad – 826004 (India)

    2015-06-24

    Superconducting polycrystalline bulk MgB{sub 2} samples doped with n-C, n-Y{sub 2}O{sub 3} and n-Ho{sub 2}O{sub 3} were prepared by powder-in-sealed (PIST) method. XRD measurement shows the influence of dopants on phase and lattice parameters of samples. The ac susceptibility measurement reveals ac loss and activation energy of the samples. Nano-C doped sample shows less ac loss in all frequency (208 Hz – 999 Hz) among the doped samples; whereas n-Ho{sub 2}O{sub 3} doped sample shows highest ac loss. The activation energy is high for rare earth (n-Y{sub 2}O{sub 3} and n-Ho{sub 2}O{sub 3}) doped samples as compare to n-C doped samples which reveals the enhancement in flux-pinning properties of these materials.

  14. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Oversupply of rare earths led to the significant price drop of rare earth mineral products and separated products in Chinese domestic market. To stabilize the price, prevent waste of resources, further improve regulation capability on domestic rare earth market and rare earth price and maintain sustaining and healthy development of rare earth industry, partial rare earth producers in Baotou and Jiangxi province projected to cease the production for one month.

  15. Effect of Different Nd2O3 Contents on Performances of Rare Earth Active Bioceramic Gradient Coating Produced by Wide-Band Laser Cladding%Nd2O3含量对宽带激光熔覆生物活性稀土梯度涂层性能的影响

    Institute of Scientific and Technical Information of China (English)

    汪震; 刘其斌; 肖明; 杨邦成

    2011-01-01

    为了减少激光熔覆过程中基材与生物陶瓷涂层之间的热应力,提高涂层与基材的结合强度,设计了一种稀土活性生物梯度陶瓷涂层,采用宽带激光熔覆技术,在TC4合金上制备了含HA+β-TCP稀土活性梯度生物陶瓷复合涂层.利用扫描电镜(SEM)、X射线衍射(XRD)、模拟体液(SBF)以及电化学分析仪等手段对涂层组织结构、生物活性及耐腐蚀性进行了研究.结果表明,生物活性稀土梯度涂层分为基材、合金化层以及生物陶瓷层3个层次,且各梯度层之间均为良好的化学冶金结合;稀土氧化物Nd2 O3在宽带激光熔覆生物陶瓷的过程中具有催化合成HA+β-TCP的作用,且当Nd2 O3质量分数为0.6% 时,催化合成HA+β-TCP的量最多;当Nd2 O3质量分数为0.4% ~0.6% 时,涂层的耐腐蚀性最好且涂层表面沉积的磷灰石相的量最多,具有最佳的生物活性.%To decrease the thermal stress and raise the bonding strength between substrate and bioceramic coating during laser cladding, a rare earth active bioceramic gradient coating is designed. The rare earth active gradient bioceramic coating with HA and β-TCP on TC4 allloy is prepared by using wide-band laser cladding technique. The microstructure, bioactivity and corrosion resistance of bioceramic coating are analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD), simulated body fluid (SBF), and electrochemical analyzer. The experimental results show that the bioactive rare earth gradient coating which has excellent chemical metallurgy bonding at the interface consists of substrate, alloying layer and bioceramic coating. Nd2O3 plays an important role in synthesizing HA and β-TCP during wide-band laser cladding. When the mass fraction of Nd2O3 is up to 0.6%, the amount of HA+β-TCP catalyzed during wide-band laser cladding becomes the largest. When the mass fraction of Nd2O3 is 0.4 % ~ 0.6 %, the corrosion resistance of bioceramic coating is

  16. Health-enhancing doping controls

    DEFF Research Database (Denmark)

    Christiansen, Ask Vest

    2010-01-01

    Editorial published at International Network of Humanistic Doping Research (INHDR) website: http://www.doping.au.dk/en/online-resources/editorials/......Editorial published at International Network of Humanistic Doping Research (INHDR) website: http://www.doping.au.dk/en/online-resources/editorials/...

  17. Negative terahertz conductivity in remotely doped graphene bilayer heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ryzhii, V. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Institute of Ultra High Frequency Semiconductor Electronics of RAS, and Center for Photonics and Infrared Engineering, Bauman Moscow State Technical University, Moscow 111005 (Russian Federation); Ryzhii, M. [Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu 965-8580 (Japan); Mitin, V. [Department of Electrical Engineering, University at Buffalo, SUNY, Buffalo, New York 1460-1920 (United States); Shur, M. S. [Departments of Electrical, Electronics, and Systems Engineering and Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Otsuji, T. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan)

    2015-11-14

    Injection or optical generation of electrons and holes in graphene bilayers (GBLs) can result in the interband population inversion enabling the terahertz (THz) radiation lasing. The intraband radiative processes compete with the interband transitions. We demonstrate that remote doping enhances the indirect interband generation of photons in the proposed GBL heterostructures. Therefore, such remote doping helps to surpass the intraband (Drude) absorption, and results in large absolute values of the negative dynamic THz conductivity in a wide range of frequencies at elevated (including room) temperatures. The remotely doped GBL heterostructure THz lasers are expected to achieve higher THz gain compared with previously proposed GBL-based THz lasers.

  18. Wide-angle energy-momentum spectroscopy

    CERN Document Server

    Dodson, Christopher M; Li, Dongfang; Zia, Rashid

    2014-01-01

    Light emission is defined by its distribution in energy, momentum, and polarization. Here, we demonstrate a method that resolves these distributions by means of wide-angle energy-momentum spectroscopy. Specifically, we image the back focal plane of a microscope objective through a Wollaston prism to obtain polarized Fourier-space momentum distributions, and disperse these two-dimensional radiation patterns through an imaging spectrograph without an entrance slit. The resulting measurements represent a convolution of individual radiation patterns at adjacent wavelengths, which can be readily deconvolved using any well-defined basis for light emission. As an illustrative example, we use this technique with the multipole basis to quantify the intrinsic emission rates for electric and magnetic dipole transitions in europium-doped yttrium oxide (Eu$^{3+}$:Y$_{2}$O$_{3}$) and chromium-doped magnesium oxide (Cr$^{3+}$:MgO). Once extracted, these rates allow us to reconstruct the full, polarized, two-dimensional radi...

  19. Preparation and luminescence of new Nd 3+ doped chloro-sulphide glass-ceramics

    Science.gov (United States)

    Seznec, Vincent; Ma, Hong Li; Zhang, Xiang Hua; Nazabal, Virginie; Adam, Jean-Luc; Qiao, X. S.; Fan, X. P.

    2006-12-01

    Chalcogenide glass-ceramics containing rare earth have been studied. A reproducible process has been established for making transparent glass-ceramics. The presence of micro-crystals inside the chalco-halide glass-ceramics induces scattering at the short wavelengths. Photoluminescence of rare earth has been greatly increased in glass-ceramics. To our best knowledge, this is the first paper on rare-earth-doped glass-ceramics based on chalcogenide.

  20. Effect of Rare Earth Phosphate Composite Materials on Cleanout Oil-Dirty Property of Ceramics

    Institute of Scientific and Technical Information of China (English)

    Liang Jinsheng; Zhang Jin; Liang Guangchuan; Wang Lijuan; Li Guosheng; Meng Junping; Pan Yanfen

    2004-01-01

    The ceramics with cleaning easily up oil-dirty property were prepared by doping enamel slurry with rare earth elements phosphate composite materials, and then the influence mechanisms of rare earth elements phosphate composite materials on the cleaning easily up oil-dirty property of ceramic were studied by testing the surface tension and contact angle of water, latex stability inside of ceramic product. Results that the ceramic doped enamel slurry with rare earth phosphate composite materials can reduce obviously the surface tension and contact angle of water, and make latex more stable, and so the ceramics possess excellent cleanout oil-dirty property.

  1. An Earth Penetrating Modeling Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Stokes, E; Yarrington, P; Glenn, L

    2005-06-21

    Documentation of a study to assess the capability of computer codes to predict lateral loads on earth penetrating projectiles under conditions of non-normal impact. Calculations simulated a set of small scale penetration tests into concrete targets with oblique faces at angles of 15 and 30 degrees to the line-of-flight. Predictive codes used by the various calculational teams cover a wide range of modeling approaches from approximate techniques, such as cavity expansion, to numerical methods, such as finite element codes. The modeling assessment was performed under the auspices of the Phenomenology Integrated Product Team (PIPT) for the Robust Nuclear Earth Penetrator Program (RNEP). Funding for the penetration experiments and modeling was provided by multiple earth penetrator programs.

  2. Gene doping in sports.

    Science.gov (United States)

    Unal, Mehmet; Ozer Unal, Durisehvar

    2004-01-01

    Gene or cell doping is defined by the World Anti-Doping Agency (WADA) as "the non-therapeutic use of genes, genetic elements and/or cells that have the capacity to enhance athletic performance". New research in genetics and genomics will be used not only to diagnose and treat disease, but also to attempt to enhance human performance. In recent years, gene therapy has shown progress and positive results that have highlighted the potential misuse of this technology and the debate of 'gene doping'. Gene therapies developed for the treatment of diseases such as anaemia (the gene for erythropoietin), muscular dystrophy (the gene for insulin-like growth factor-1) and peripheral vascular diseases (the gene for vascular endothelial growth factor) are potential doping methods. With progress in gene technology, many other genes with this potential will be discovered. For this reason, it is important to develop timely legal regulations and to research the field of gene doping in order to develop methods of detection. To protect the health of athletes and to ensure equal competitive conditions, the International Olympic Committee, WADA and International Sports Federations have accepted performance-enhancing substances and methods as being doping, and have forbidden them. Nevertheless, the desire to win causes athletes to misuse these drugs and methods. This paper reviews the current status of gene doping and candidate performance enhancement genes, and also the use of gene therapy in sports medicine and ethics of genetic enhancement.

  3. Doping of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Luessem, B.; Riede, M.; Leo, K. [Institut fuer Angewandte Photophysik, TU Dresden (Germany)

    2013-01-15

    The understanding and applications of organic semiconductors have shown remarkable progress in recent years. This material class has been developed from being a lab curiosity to the basis of first successful products as small organic LED (OLED) displays; other areas of application such as OLED lighting and organic photovoltaics are on the verge of broad commercialization. Organic semiconductors are superior to inorganic ones for low-cost and large-area optoelectronics due to their flexibility, easy deposition, and broad variety, making tailor-made materials possible. However, electrical doping of organic semiconductors, i.e. the controlled adjustment of Fermi level that has been extremely important to the success of inorganic semiconductors, is still in its infancy. This review will discuss recent work on both fundamental principles and applications of doping, focused primarily to doping of evaporated organic layers with molecular dopants. Recently, both p- and n-type molecular dopants have been developed that lead to efficient and stable doping of organic thin films. Due to doping, the conductivity of the doped layers increases several orders of magnitude and allows for quasi-Ohmic contacts between organic layers and metal electrodes. Besides reducing voltage losses, doping thus also gives design freedom in terms of transport layer thickness and electrode choice. The use of doping in applications like OLEDs and organic solar cells is highlighted in this review. Overall, controlled molecular doping can be considered as key enabling technology for many different organic device types that can lead to significant improvements in efficiencies and lifetimes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Copernicus Earth observation programme

    Science.gov (United States)

    Žlebir, Silvo

    European Earth observation program Copernicus is an EU-wide programme that integrates satellite data, in-situ data and modeling to provide user-focused information services to support policymakers, researchers, businesses and citizens. Land monitoring service and Emergency service are fully operational already, Atmosphere monitoring service and Marine environment monitoring service are preoperational and will become fully operational in the following year, while Climate change service and Security service are in an earlier development phase. New series of a number of dedicated satellite missions will be launched in the following years, operated by the European Space Agency and EUMETSAT, starting with Sentinel 1A satellite early this year. Ground based, air-borne and sea-borne in-situ data are provided by different international networks and organizations, EU member states networks etc. European Union is devoting a particular attention to secure a sustainable long-term operational provision of the services. Copernicus is also stated as a European Union’s most important contribution to Global Earth Observation System of Systems (GEOSS). The status and the recent development of the Copernicus programme will be presented, together with its future perspective. As Copernicus services have already demonstrated their usability and effectiveness, some interesting cases of their deployment will be presented. Copernicus free and open data policy, supported by a recently adopted EU legislative act, will also be presented.

  5. Doping and Fair Play

    OpenAIRE

    Nicolas Eber

    2009-01-01

    The conventional approach to the economic analysis of doping in sport is that athletes are typically involved in a Prisoner’s Dilemma-type interaction (Breivik 1987, Bird and Wagner 1997, Eber and Thépot 1999, Haugen 2004).1 The idea is straightforward: doping being a dominant strategy (i.e., yielding a preferred outcome regardless of the strategy used by the competitor), each athlete finds it optimal to take drugs; this results in a situation of generalized doping although each athlete would...

  6. Isoelectronic co-doping

    Science.gov (United States)

    Mascarenhas, Angelo

    2004-11-09

    Isoelectronic co-doping of semiconductor compounds and alloys with deep acceptors and deep donors is used to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, N and Bi, to customize solar cells, thermal voltaic cells, light emitting diodes, photodetectors, and lasers on GaP, InP, GaAs, Ge, and Si substrates. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

  7. Earth from Above

    Science.gov (United States)

    Stahley, Tom

    2006-01-01

    Google Earth is a free online software that provides a virtual view of Earth. Using Google Earth, students can view Earth by hovering over features and locations they preselect or by serendipitously exploring locations that catch their fascination. Going beyond hovering, they can swoop forward and even tilt images to make more detailed…

  8. Effect of rare-earth dopants on the growth and structural, optical, electrical and mechanical properties of L-arginine phosphate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Arjunan, S., E-mail: arjunan_hce@yahoo.co.i [Department of Physics, Sri Ramachandra University, Porur, Chennai (India); Bhaskaran, A. [Department of Physics, Dr. Ambedkar Government College, Chennai (India); Kumar, R. Mohan; Mohan, R. [Department of Physics, Presidency College, Chennai (India); Jayavel, R. [Crystal Growth Centre, Anna University, Chennai (India)

    2010-09-17

    Research highlights: {yields} Thorium, Lanthanum and Cerium rare-earth ions were doped with L-arginine phosphate material and the crystals were grown by slow evaporation technique. {yields} The transparency of the rare-earth doped LAP crystals has enhanced compared to pure LAP. {yields} The powder SHG measurements revealed that the SHG output of rare-earth doped LAP crystals increases considerably compared to that of LAP. {yields} Vicker's hardness number of as-grown crystal of LAP is higher than that of rare-earth doped LAP crystals. - Abstract: Effect of Thorium, Lanthanum and Cerium rare-earth ions on the growth and properties of L-arginine phosphate single crystals has been reported. The incorporation of rare-earth dopants into the L-arginine phosphate crystals is confirmed by Inductively Coupled Plasma-Mass Spectroscopy analysis. The unit cell parameters for pure and rare-earth doped L-arginine phosphate crystals have been estimated by powder X-ray diffraction studies. UV-visible studies revealed the transmittance percentage and cut-off wavelengths of the grown crystals. Powder second harmonic generation measurement has been carried out for pure and doped L-arginine phosphate crystals. The dielectric behavior of the grown crystals was analyzed for different frequencies at room temperature. The mechanical properties have been determined for pure and the doped L-arginine phosphate crystals.

  9. Rare Earth Resolution

    Institute of Scientific and Technical Information of China (English)

    Mei Xinyu

    2012-01-01

    BEFORE the early 1970s, China had no rare earth exports, and the world rare earth market was dominated by the United States, Europe and Japan. In the 1970s, China began to enter the world rare earth market and its share has picked up sharply in the following decades. Today, having the monopoly over global rare earth production, China must improve the benefits from rare earth production, not only from producing individual rare earth products, but also from mastering the intensive processing of rare earth products.

  10. Room temperature enhanced red emission from novel Eu{sup 3+} doped ZnO nanocrystals uniformly dispersed in nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yongzhe; Wang Qijie [School of Electrical and Electronic Engineering and School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Liu Yanxia; Li Xiaodong; Xie Erqing, E-mail: QJWANG@ntu.edu.sg [School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000 (China)

    2011-10-14

    Achieving red emission from ZnO-based materials has long been a goal for researchers in order to realize, for instance, full-color display panels and solid-state light-emitting devices. However, the current technique using Eu{sup 3+} doped ZnO for red emission generation has a significant drawback in that the energy transfer from ZnO to Eu{sup 3+} is inefficient, resulting in a low intensity red emission. In this paper, we report an efficient energy transfer scheme for enhanced red emission from Eu{sup 3+} doped ZnO nanocrystals by fabricating polymer nanofibers embedded with Eu{sup 3+} doped ZnO nanocrystals to facilitate the energy transfer. In the fabrication, ZnO nanocrystals are uniformly dispersed in polymer nanofibers prepared by the high electrical field electrospinning technique. Enhanced red emission without defect radiation from the ZnO matrix is observed. Three physical mechanisms for this observation are provided and explained, namely a small ZnO crystal size, uniformity distribution of ZnO nanocrystals in polymers (PVA in this case), and strong bonding between ZnO and polymer through the -OH group bonding. These explanations are supported by high resolution transmission emission microscopy measurements, resonant Raman scattering characterizations, photoluminescence spectra and photoluminescence excitation spectra measurements. In addition, two models exploring the 'accumulation layer' and 'depletion layer' are developed to explain the reasons for the more efficient energy transfer in our ZnO nanocrystal system compared to that in the previous reports. This study provides an important approach to achieve enhanced energy transfer from nanocrystals to ions which could be widely adopted in rare earth ion doped materials. These discoveries also provide more insights into other energy transfer problems in, for example, dye-sensitized solar cells and quantum dot solar cells.

  11. Room temperature enhanced red emission from novel Eu3 + doped ZnO nanocrystals uniformly dispersed in nanofibers

    Science.gov (United States)

    Zhang, Yongzhe; Liu, Yanxia; Li, Xiaodong; Jie Wang, Qi; Xie, Erqing

    2011-10-01

    Achieving red emission from ZnO-based materials has long been a goal for researchers in order to realize, for instance, full-color display panels and solid-state light-emitting devices. However, the current technique using Eu3 + doped ZnO for red emission generation has a significant drawback in that the energy transfer from ZnO to Eu3 + is inefficient, resulting in a low intensity red emission. In this paper, we report an efficient energy transfer scheme for enhanced red emission from Eu3 + doped ZnO nanocrystals by fabricating polymer nanofibers embedded with Eu3 + doped ZnO nanocrystals to facilitate the energy transfer. In the fabrication, ZnO nanocrystals are uniformly dispersed in polymer nanofibers prepared by the high electrical field electrospinning technique. Enhanced red emission without defect radiation from the ZnO matrix is observed. Three physical mechanisms for this observation are provided and explained, namely a small ZnO crystal size, uniformity distribution of ZnO nanocrystals in polymers (PVA in this case), and strong bonding between ZnO and polymer through the -OH group bonding. These explanations are supported by high resolution transmission emission microscopy measurements, resonant Raman scattering characterizations, photoluminescence spectra and photoluminescence excitation spectra measurements. In addition, two models exploring the 'accumulation layer' and 'depletion layer' are developed to explain the reasons for the more efficient energy transfer in our ZnO nanocrystal system compared to that in the previous reports. This study provides an important approach to achieve enhanced energy transfer from nanocrystals to ions which could be widely adopted in rare earth ion doped materials. These discoveries also provide more insights into other energy transfer problems in, for example, dye-sensitized solar cells and quantum dot solar cells.

  12. Inverted opal luminescent Ce-doped silica glasses

    Directory of Open Access Journals (Sweden)

    R. Scotti

    2006-01-01

    Full Text Available Inverted opal Ce-doped silica glasses (Ce : Si molar ratio 1 ⋅ 10−3 were prepared by a sol-gel method using opals of latex microspheres as templates. The rare earth is homogeneously dispersed in silica host matrix, as evidenced by the absence of segregated CeO2, instead present in monolithic Ce-doped SG with the same cerium content. This suggests that the nanometric dimensions of bridges and junctions of the host matrix in the inverted opal structures favor the RE distribution avoiding the possible segregation of CeO2.

  13. Advances in Laser Cooling of Thulium-Doped Glass

    Science.gov (United States)

    2003-05-01

    conversion,’’ Appl. Phys. Lett. 75, 1258–1260 (1999). 21. L. Wetenkamp, G. F. West, and H. Tobben, ‘‘Optical proper- ties of rare earth-doped ZBLAN glasses ...properties of Tm31 in ZBLAN fluoride glass . Part 2. Judd-Ofelt parameters,’’ Phys. Chem. Glasses 36, 139–140 (1995). 38. M. J. Weber, ‘‘Laser excited...Advances in laser cooling of thulium-doped glass C. W. Hoyt, M. P. Hasselbeck, and M. Sheik-Bahae Department of Physics and Astronomy, University of

  14. MATLAB Recipes for Earth Sciences

    Science.gov (United States)

    Trauth, M. H.

    MATLAB is used in a wide range of applications in geosciences, such as image processing in remote sensing, generation and processing of digital elevation models and the analysis of time series. This book introduces basic methods of data analysis in geosciences using MATLAB. The text includes a brief description of each method and numerous examples demonstrating how MATLAB can be used on data sets from earth sciences. All MATLAB recipes can be easily modified in order to analyse the reader's own data sets.

  15. Optical properties of Pr3+-, Ce3+-, and Eu3+-doped ternary lead halides

    Science.gov (United States)

    Brown, Ei E.; Bluiett, Althea; Hömmerich, Uwe; Trivedi, Sudhir B.

    2015-03-01

    The luminescent properties of rare-earth doped solids have been under intense exploration for a wide range of applications ranging from displays and lasers to scintillators. In this work, the material purification, crystal growth, and spectroscopic properties of Ce3+-, and Eu3+- doped KPb2Cl5 as well as Pr3+ doped KPb2Cl5 and KPb2Br5 were investigated for possible applications in infrared lasers and radiation detectors. The studied materials were synthesized through careful purification of starting materials including multi-pass zone-refinement and halogination. The growth of the purified materials was then carried out through vertical or horizontal Bridgman technique. The trivalent praseodymium ion (Pr3+) offers a large number of laser transitions in the visible and infrared (IR) spectral regions. Using ~1.45 μm and 1.9 μm pumping, IR emissions at ~1.6, ~2.4, and ~4.6 μm were observed from Pr: KPb2Cl5 and Pr: KPb2Br5 corresponding to the 4f-4f transitions of 3F4/3F3-->3H4, 3F2/3H6-->3H4, and 3H5-->3H4, respectively. Large emission cross-sections in the range of (4.8-6.1) x 10-20 cm2 (near-IR, ~1.6 μm) and (5.5-6.0) x 10-20 cm2 (mid-IR, ~4.6 μm) were observed for both crystals. Emission characteristics of the ~1.6 μm Pr3+ transition including IR to visible upconversion emission studies were also discussed. Under Xenon lamp excitation, preliminary spectroscopic results showed allowed 5d-4f Ce3+ emission centered at ~375 nm in Ce3+ doped KPb2Cl5. In addition, commercial Ce:YAG and Ce:YAP crystals are included in this study for comparison. Pr3+ and Eu2+ 5d-4f emissions were not observed from Pr3+/Eu2+ doped KPb2Cl5 crystals.

  16. Borazino-Doped Polyphenylenes.

    Science.gov (United States)

    Marinelli, Davide; Fasano, Francesco; Najjari, Btissam; Demitri, Nicola; Bonifazi, Davide

    2017-04-19

    The divergent synthesis of two series of borazino-doped polyphenylenes, in which one or more aryl units are replaced by borazine rings, is reported for the first time, taking advantage of the decarbonylative [4 + 2] Diels-Alder cycloaddition reaction between ethynyl and tetraphenylcyclopentadienone derivatives. Because of the possibility of functionalizing the borazine core with different groups on the aryl substituents at the N and B atoms of the borazino core, we have prepared borazino-doped polyphenylenes featuring different doping dosages and orientations. To achieve this, two molecular modules were prepared: a core and a branching unit. Depending on the chemical natures of the central aromatic module and the reactive group, each covalent combination of the modules yields one exclusive doping pattern. By means of this approach, three- and hexa-branched hybrid polyphenylenes featuring controlled orientations and dosages of the doping B3N3 rings have been prepared. Detailed photophysical investigations showed that as the doping dosage is increased, the strong luminescent signal is progressively reduced. This suggests that the presence of the B3N3 rings engages additional deactivation pathways, possibly involving excited states with an increasing charge-separated character that are restricted in the full-carbon analogues. Notably, a strong effect of the orientational doping on the fluorescence quantum yield was observed for those hybrid polyphenylene structures featuring low doping dosages. Finally, we showed that Cu-catalyzed 1,3-dipolar cycloaddition is also chemically compatible with the BN core, further endorsing the inorganic benzene as a versatile aromatic scaffold for engineering of molecular materials with tailored and exploitable optoelectronic properties.

  17. [Doping: effectiveness, consequences, prevention].

    Science.gov (United States)

    Guezennec, C Y

    2001-02-01

    The use of doping is linked with the history of sports. Doping abuse escalated until the mid sixties when government and sports authorities responded with antidoping laws and drug testing. Today, the details of substances detected in controls give a good indication on the importance of doping use. Three classes of pharmaceuticals account for most of the positive controls. They are anabolic steroids, stimulants and narcotics. Their use can be related with the goal of the athletes. Anabolic steroids are mainly used in sports such as bodybuilding or weight lifting in order to develop strength. Stimulants are used in sports were speed favors performance. All the products that enhance blood oxygen transportation are used in endurance sports, their efficacy is not scientifically demonstrated, but their use does result in real risks. Several studies have evidenced the medical problems resulting from prolonged doping. Doping control is impaired by the fact that many products now used, e.g. EPO or rhGH, are not detectable. Regular medical examination of athletes could help prevent use of doping.

  18. Gain equalization of FM-EDFA by optimizing ring doping and mode content of the pump with a genetic algorithm

    Science.gov (United States)

    Qiu, Changren; Yang, Tianxin; Jia, Dong fang; Wang, Zhaoying; Ge, Chunfeng

    2015-03-01

    We investigate gain equalization of a four-mode-group and six-mode-group erbium-doped fiber amplifiers with a genetic algorithm for mode division multiplexing transmission systems by optimizing rare earth dopant profile and pump modes powers, respectively. The optimizing gains are calculated to be > 28 dB between 1520 nm - 1565 nm with a maximum differential modal gain of ~ 2 dB among the mode groups only by optimizing the rare earth ring doping profile in the few-mode erbium-doped fiber.

  19. A versatile new method for synthesis and deposition of doped, visible light-activated TiO2 thin films

    DEFF Research Database (Denmark)

    In, Su-il; Kean, A.H.; Orlov, A.

    2009-01-01

    A flexible and widely applicable method allows the deposition of carbon-doped visible light-activated photocatalytic TiO2 thin films on a variety of substrates.......A flexible and widely applicable method allows the deposition of carbon-doped visible light-activated photocatalytic TiO2 thin films on a variety of substrates....

  20. Monolithic Rare Earth Doped PTR Glass Laser Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of airborne and spaceborne laser systems dictates a number of extremely challenging requirements for such fine optical devices. These requirements...