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Sample records for ag-clad bi-based superconducting

  1. Near-net-shape fabrication of continuous Ag-Clad Bi-Based superconductors

    International Nuclear Information System (INIS)

    Lanagan, M. T. et al.

    1998-01-01

    We have developed a near-net-shape process for Ag-clad Bi-2212 superconductors as an alternative to the powder-in-tube process. This new process offers the advantages of nearly continuous processing, minimization of processing steps, reasonable ability to control the Bi-2212/Ag ratio, and early development of favorable texture of the Bi-2212 grains. Superconducting properties are discussed

  2. Method and etchant to join Ag-clad BSSCO superconducting tape

    Science.gov (United States)

    Balachandran, U.; Iyer, A.N.; Huang, J.Y.

    1999-03-16

    A method of removing a silver cladding from high temperature superconducting material clad in silver (HTS) is disclosed. The silver clad HTS is contacted with an aqueous solution of HNO{sub 3} followed by an aqueous solution of NH{sub 4}OH and H{sub 2}O{sub 2} for a time sufficient to remove the silver cladding from the superconducting material without adversely affecting the superconducting properties of the superconducting material. A portion of the silver cladding may be masked with a material chemically impervious to HNO{sub 3} and to a combination of NH{sub 4}OH and H{sub 2}O{sub 2} to preserve the Ag coating. A silver clad superconductor is disclosed, made in accordance with the method discussed. 3 figs.

  3. Superconducting joint of Bi-2223/Ag superconducting tapes by diffusion bonding

    International Nuclear Information System (INIS)

    Guo Wei; Zou Guisheng; Wu Aiping; Wang Yanjun; Bai Hailin; Ren Jialie

    2009-01-01

    61-Filaments Bi-2223/Ag superconducting tapes have been joined by diffusion bonding. The critical currents (I C s) of the joints are obtained by using standard four probe method under no magnetic field in the liquid nitrogen. The microstructures of the joints are evaluated by the electron microscope in electron backscatter diffraction mode and the phase compositions of the superconducting cores of the joint and the original tape are determined by X-ray diffraction (XRD). The results show diffusion bonding is effective bonding technique for HTS tapes, and the bonding time is reduced greatly from hundreds of hours to a few hours, and the bonding pressure also changes from 140-4000 MPa to 3 MPa. Furthermore, the diffusion bonding joints sustain superconducting properties, and the critical current ratios (CCR O ) of the joints are in the range of 35%-80%. Microstructures of the typical joint display a good bonding and some defects existed in traditional method are avoided. XRD results show that the phase compositions of the superconducting cores have no obvious changes before and after diffusion bonding, which offers physical and material bases for high superconducting property of the joints.

  4. Development of microstructure and superconductivity of silver-clad Bi(2223) composite tapes in the process of heat treatment

    International Nuclear Information System (INIS)

    Guo, Y.C.; Liu, H.K.; Dou, S.X.

    1994-01-01

    A systematic study on the development of phase composition, microstructure and superconducting properties (critical temperature Tc and critical current density J c ) in silver-clad (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10 composite tapes during the process of heat treatment has been conducted using X-ray diffraction, scanning electron microscopy and electrical measurements. The correlation between the tape's high Tc phase purity, microstructure and superconducting properties at different heat treatment stages has been carefully analysed and explained. The results indicate that pure high Tc phase, high degree of grain alignment, high mass density and good connection between grains are all essential for superconducting tapes to carry a large current. With the optimized process parameters, a critical current density J c up to 32665 A cm -2 (corresponding critical current, 42.3 A) at 77 K and self-magnetic field for silver-clad (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10 superconducting composite tapes has been achieved. (orig.)

  5. Critical current of high Tc superconducting Bi223/Ag tapes

    NARCIS (Netherlands)

    Huang, Y.; ten Haken, Bernard; ten Kate, Herman H.J.

    1998-01-01

    The magnetic field dependence of the critical current of various high Tc superconducting Bi2223/Ag tapes indicates that the transport current is carried through two paths: one is through weakly-linked grain boundaries (Josephson junctions); another is through well-connected grains. The critical

  6. Fabrication, properties, and microstructures of high Tc tapes and coils made from Ag-clad Bi-2223 superconductors

    International Nuclear Information System (INIS)

    Balachandran, U.; Iyer, A.N.; Youngdahl, C.A.; Motowidlo, L.R.; Hoehn, J.G.; Haldar, P.

    1993-07-01

    Bi-2223 precursor powders were prepared via a solid-state reaction using carbonates and oxides of Bi, Pb, Sr, Ca, and Cu. Results indicate that an in-situ reaction between constituent phases with tho formation of a transient liquid that is consumed during final heat treatment, is essential to obtain increased density with greater connectivity between the 2223 grains. Relative amounts of the constituent phases were adjusted in the powder by varying the calcination conditions, and the powder was then used to fabricate Ag-clad tapes by a powder-in-tube technique. By improving process conditions, transport critical current density (J c ) values greater than 4 x 10 4 A/cm 2 at 77 K and 2 x 10 5 A/cm 2 at 4.2 and 27 K have been obtained in short tape samples. Long tapes were cut into lengths upto 10 m long and used in parallel to fabricate small superconducting pancake coils. The coils were characterized at 77, 27 and 4.2 K and results are discussed

  7. The Effect of Temperature Dependence of AC Losses in a Bi-2223/Ag Insert of an 8-T Superconducting Magnet

    DEFF Research Database (Denmark)

    Wang, Lei; Wang, Qiuliang; Wang, Hui

    2016-01-01

    A conduction-cooled split-gap superconducting magnet system with a center field of 8 T has been designed and fabricated in the Institute of Electrical Engineering, Chinese Academy of Sciences. The system consists of two Bi-2223/Ag coils and six NbTi coils. Due to a large aspect ratio of the high-...... in the second case. Hence, it is a good way to reduce the ac losses by changing the charging sequences of the Bi-2223/Ag and NbTi cols. Afterward, the calculated results are compared with the experimental data, and they show a good agreement.......A conduction-cooled split-gap superconducting magnet system with a center field of 8 T has been designed and fabricated in the Institute of Electrical Engineering, Chinese Academy of Sciences. The system consists of two Bi-2223/Ag coils and six NbTi coils. Due to a large aspect ratio of the high......-temperature superconducting tape, there will be large ac losses when the magnet is ramped up and down. An accurate estimation of the total ac losses in the high-temperature superconducting coils is essential for the cryogenic system design. In the Bi-2223/Ag coils, the total ac losses mainly originate from two parts: One...

  8. Structural properties of superconducting Bi-2223/Ag tapes

    Energy Technology Data Exchange (ETDEWEB)

    Gottschalck Andersen, L.

    2001-05-01

    The structural properties of silver clad high-T{sub c} superconducting ceramic tapes of (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Bi-2223) have been investigated by means of synchrotron X-ray diffraction (including the 3DXRD microscope setup), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDS). By synchrotron X-ray diffraction in situ studies of the phase development during the transformation of (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 1}Cu{sub 2}O{sub x} (Bi-2212) into Bi-2223, the stoichiometry changes and the texture have been performed during annealing in 8% O{sub 2} and in air. Furthermore, an annealing with two high temperature cycles has been performed to study the equilibrium phenomena. During heating (Ca,Sr){sub 2}PbO{sub 4} decomposes at temperatures between 700 deg. C and 840 deg.C. Simultaneously, the Bi-2212 lattice contracts, indicating an incorporation of Pb. Moreover, the grain mis-alignment decreases significantly. In air we have observed that Bi-2212 partly dissociates into (Ca,Sr){sub 2}CuO{sub 3} and a liquid at temperatures above 812 deg. C. At the annealing temperature Bi-2212 and (Ca,Sr){sub 2}CuO{sub 3} react with the liquid to form Bi-2223. The transformation mechanism is discussed. During cooling below {approx}750 deg.C (Ca,Sr){sub 2}CuO{sub 3} and the liquid mainly transform into Bi-2201. Below {approx}780 deg. C Bi-2223 decomposes to 3221. In addition, a two-step cooling experiment and a decomposition study have been performed in 8% O{sub 2}. By TEM the grain and colony size in the c-axis direction, the angles of c-axis tilt grain boundaries and the intergrowth content are investigated. A fully processed tape has on average 50% thicker grains than a tape after the 1st annealing. The angles of c-axis tilt grain boundaries are on average 14 deg. and 26 deg. for the fully processed tape and the tape after the 1st annealing, respectively. The intergrowth content (15%) and

  9. Investigation on the phase transformation of Bi-2223/Ag superconducting tapes during heating

    International Nuclear Information System (INIS)

    Huang, K.-T.; Qu, T.-M.; Xie, P.; Han, Z.

    2013-01-01

    Highlights: • In situ resistance measurement was carried out on Bi-2223/Ag superconducting tapes. • The oxygen partial pressure of the outlet gas in the heating process was monitored continuously. • The samples quenched in the heating process were studied by XRD and T c measurements. • The heating process contains three procedures: oxygen diffusion, Pb-rich phase evolution and liquid phase formation. -- Abstract: The phase transformation of Bi-2223/Ag superconducting tapes during heating was investigated. The resistance of the ceramic core as a function of the heating temperature was measured in situ. The pO 2 of the outlet gas in the heating process was also monitored continuously. By comparing the heating process with the X-ray diffraction and T c measurements taken from samples quenched at different temperatures, we have identified that the heating process could be divided into the following regions: (1) the oxygen diffusion (OD) region, which is mainly influenced by OD; (2) the Pb-rich phase evolution (PbE) region, in which the formation and decomposition of the Pb-rich phases occur; (3) the liquid phase formation (LF) region, in which resistance increased rapidly with increasing temperature

  10. A high Tc superconducting liquid nitrogen level sensor

    International Nuclear Information System (INIS)

    Jin, J. X.; Liu, H. K.; Dou, S. X.; Grantham, C.; Beer, J.

    1996-01-01

    Full text: The dramatic resistance change in the superconducting-normal transition temperature range enables a high T c superconductor to be considered for designing a liquid nitrogen level sensor. A (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+x Ag clad superconducting wire is selected and tested as a continuous liquid nitrogen level sensor to investigate the possibility for this application. The (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+x Ag clad superconducting wire has approximately 110 K critical temperature, with more flexible and stable properties compared with bulk shape ceramic high T c superconductors. The voltage drops across the sensor are tested with different immersion lengths in liquid nitrogen. The accuracy of the HTS sensor is analysed with its dR/dT in the superconducting-normal transition range. The voltage signal is sensitive to liquid nitrogen level change, and this signal can be optimized by controlling the transport current. The problems of the Ag clad superconductor are that the Ag sheath thermal conductivity is very high, and the sensor normal resistance is low. These are the main disadvantages for using such a wire as a continuous level sensor. However, a satisfactory accuracy can be achieved by control of the transport current. A different configuration of the wire sensor is also designed to avoid this thermal influence

  11. Effect of Pb and Ag additions on electrical properties Bi2Sr2Ca2Cu3Ox superconductive ceramics

    International Nuclear Information System (INIS)

    Reddi, B.V.; Uskov, E.M.

    1990-01-01

    The influence of Pb and Ag additions on the electrical properties of Bi 2 Sr 2 Ca 2 Cu 3 O x superconducting ceramics has been studied by Hall method. It was found that the Pb additions has more influence on the sample characteristics than Ag. It was found, that Hall EMF at 77 K equal to zero in the samples having some residue resistance

  12. Effect of Ag in structural, electrical and magnetic properties of Ag-sheated Bi-2223 wires

    Directory of Open Access Journals (Sweden)

    D Sohrabi

    2009-08-01

    Full Text Available  In this study, the superconducting properties of Bi-2223/Ag wires, made by the PIT method have been studied. Powder samples were prepared using conventional solid state reaction method. After calcination, samples with different Ag percent (0, 5, 10, 15, 20, and 25 prepared and sintered at 830 °C. It was shown that Ag addition has not only affected the formation of the desired Bi-2223 phase and the microstructure of these wires, but also influenced on the critical current density (JC and critical temperature.

  13. Investigation on synthesis of Bi-based thin films on flat sputter-deposited Ag film by melting process

    International Nuclear Information System (INIS)

    Su Yanjing; Satoh, Yoshimasa; Arisawa, Shunichi; Awane, Toru; Fukuyo, Akihiro; Takano, Yoshihiko; Ishii, Akira; Hatano, Takeshi; Togano, Kazumasa

    2003-01-01

    We report on the fabrication of ribbon-like thin films on flat sputter-deposited Ag films whose surface smoothness remained within the order of tens of nm. It was found that the addition of Pb to the starting material improves the wettability of molten phase and facilitates the growth of Bi-2212 ribbon-like thin films on a flat Ag substrate, and that the increase of Ca and Cu in starting material suppresses the intergrowth of the Bi-2201 phase in ribbon-like thin films. By using (Bi,Pb)-2246 powders, with nominal composition of Bi 1.6 Pb 0.4 Sr 1.6 Ca 3.2 Cu 4.8 O y , as the starting material, the superconducting Bi-2212 ribbon-like thin films with an onset T c at 74 K on a very flat Ag substrate were successfully synthesized. Additionally, the growth mechanism of ribbon-like thin films on flat Ag substrate was investigated by in situ high temperature microscope observation

  14. Analysis of the residual strain change of Bi2212, Ag alloy and Ag during the heating and cooling process in Bi2212/Ag/Ag alloy composite wire

    International Nuclear Information System (INIS)

    Shin, J K; Ochiai, S; Okuda, H; Mukai, Y; Sugano, M; Sato, M; Oh, S S; Ha, D W; Kim, S C

    2008-01-01

    The residual strain change of Bi2212 and Ag during the cooling and heating process in the Bi2212/Ag/Ag alloy composite superconductor was studied. First, the residual strain of Bi2212 filaments at room temperature was measured by the x-ray diffraction method. Then, the Young's moduli of the constituents (Bi2212 filaments, Ag and Ag alloy) and yield strains of Ag and Ag alloy were estimated from the analysis of the measured stress-strain curve, based on the rule of mixtures. Also, the coefficient of thermal expansion of the Bi2212 filaments was estimated from the analysis of the measured thermal expansion curve of the composite wire. From the modeling analysis using the estimated property values and the residual strain of Bi2212 filaments, the changes of residual strain of Bi2212, Ag alloy and Ag with temperature during the cooling and heating process were revealed

  15. Effect of Sintering Time on Superconducting Wire Bi-Pb-Sr-Ca-Cu-O With Dopant MgO Sheated Ag Using Powder in Tube Method

    Directory of Open Access Journals (Sweden)

    Hariyati Lubis

    2018-01-01

      DAFTAR PUSTAKA Abbas M.M., Abass L.K and Salman U., (2012, Influences of Sintering Time on the Tc of Bi2-xCuxPb0.3Sr2Ca2Cu3010+ High Temperature Superconductors, Energy Procedia 18, 215-224  Abbas, M.M., Abbas, L.K., Bahedh, H.S. 2015. Superconducting Properties of Bi2-SbxPb0,3Sr1,9Ba0,1Ca2Cu3O10+δ Compounds. Journal of Applied Science Research. 11. 22: 164-172 Darsono, N., Imaduddin, A., Raju, K., Yoon, D.H., (2015, Synthesis and Characterization of Bi1.6Pb0.4Sr2Ca2Cu3O7 Superconducting Oxide by High-Energy Milling, J Supercond Nov Magn. E. Chew,. (2010, Superconducting Transformer Design And Construction, University of Canterbury, Christchurch, New Zealand. March Hamadneh, I., Halim, S. A., dan Lee, C. K., (2006,  Characterization of Bi1.6Pb0.4Sr2Ca2Cu3Oy Ceramic Superconductor Prepared Via Coprecipitation Method at Different Sintering Time, J. Mater. Sci, 41: 5526-5530. Hermiz G.Y., Aljurani B.A., Beayaty M.A., (2014, Effect of Mn Substitution on the Superconducting Properties of Bi1.7Pb0,3Sr2Ca2-xMnxCu3O10+, International Journal Of Engineering and Advanced Technology (IJEAT. 3. 4: 213-217 John R Hull, (2003, Applications of high-temperature superconductors in power technology, Reports on Progress in Physics, Volume 66, Number 11 Lu, X.Y., Yi, D., Chen, H., Nagata, A. 2016. Effect of Sn, MgO and Ag2O mix-doping on the formation and superconducting properties of Bi-2223 Ag/tapes. Physics Procedia. 81: 129-132 Meretliev Sh., Sadykov K.B., Berkeliev A., (2000, Doping of High Temperature Superconductors, Turk J Phy.24: 39-48 Mohammed, N. H., Ramadhan A., Ali I. A., Ibrahim, I. H., dan Hassan, M. S, (2012, Optimizing the Preparation Conditions of Bi-2223 Superconducting Phase Using PbO and PbO2, Materials Sciences and Applications, 3: 224-233. Roumie, M., Marhaba, S., Awad R., Kork M., Hassan I., Mawassi R., (2014, Effect of Fe2O3 Nano-Oxide Addition on the Superconducting Properties of the (Bi,Pb-2223 Phase, Journal of Supercond Nov Magn, 27: 143-153 Serkan

  16. RRR and thermal conductivity of Ag and Ag0.2wt%Mg alloy in Ag/Bi-2212 wires

    Energy Technology Data Exchange (ETDEWEB)

    Li, Pei [Fermilab; Ye, L. [North Carolina State U.; Jiang. J., Jiang. J. [Natl. High Mag. Field Lab.; Shen, T. [Fermilab

    2015-08-19

    The residual resistivity ratio (RRR) and thermal conductivity of metal matrix in metal/superconductor composite wires are important parameters for designing superconducting magnets. However, the resistivity of silver in reacted Ag/Bi-2212 wires has yet to be determined over temperature range from 4.2 K to 80 K because Bi-2212 filaments have a critical transition temperature Tc of ~ 80 K, and because it is unknown whether the RRR of Ag/Bi-2212 degrades with Cu diffusing from Bi-2212 filaments into silver sheathes at elevated temperatures and to what degree it varies with heat treatment. We measured the resistivity of stand-alone Ag and AgMg (Ag-0.2wt%Mg) wires as well as the resistivity of Ag and Ag- 0.2wt%Mg in the state-of-the-art Ag/Bi-2212 round wires reacted in 1 bar oxygen at 890 °C for 1, 8, 24 and 48 hours and quickly cooled to room temperature. The heat treatment was designed to reduce the critical current Ic of Bi-2212 wires to nearly zero while allowing Cu loss to fully manifest itself. We determined that pure silver exhibits a RRR of ~ 220 while the oxide-dispersion strengthened AgMg exhibits a RRR of ~ 5 in stand-alone samples. A surprising result is that the RRR of silver in the composite round wires doesn’t degrade with extended time at 890 °C for up to 48 hours. This surprising result may be explained by our observation that the Cu that diffuses into the silver tends to form Cu2O precipitates in oxidizing atmosphere, instead of forming Ag-Cu solution alloy. We also measured the thermal conductivity and the magneto-resistivity of pure Ag and Ag-0.2 wt%Mg from 4.2 K to 300 K in magnetic fields up to 14.8 T and summarized them using a Kohler plot.

  17. Superconducting Bi-Sr-Ca-Cu-O thin films from metallo-organic complexes

    International Nuclear Information System (INIS)

    Gruber, H.; Krautz, E.; Fritzer, H.P.; Popitsch, A.

    1991-01-01

    Thin films in the Bi-Sr-Ca-Cu-O system are produced by decomposition of organic precursor compounds containing different metallo-organic complexes. The superconducting phase identified is Bi 2 Sr 2 CaCu 2 O 8+x on (100)-MgO single crystal substrates, polycrystalline Au- and Ag-ribbons and Bi 2 Sr 2 Ca 2 Cu 3 O 10+x on Ag-ribbons. For the 2212-phase a zero resistance temperature of 79 K is found. The 2223-samples on Ag-ribbons show a broad transition at 110 K with a zero resistance at 85 K. SEM and EDX are used for the detection of the microstructure and composition of the prepared films. (orig.)

  18. Radio frequency response of Ag-sheathed (Bi, Pb)2Sr2Ca2Cu3O10+x superconducting tapes

    International Nuclear Information System (INIS)

    Grasso, G.

    2000-01-01

    The response of long (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10 conductors fabricated by the oxide-powder-in-tube method to a radio frequency excitation was investigated while employed as the inductive part of large L-C resonating circuits. After removal of the outer silver sheath, superconducting devices cooled down to 77 K showed superior properties compared to equivalent non-superconducting circuits: Bi-based resonators, conceived for a working frequency in the range between 5 and 17 MHz, presented an improvement of the quality factor by a factor of 20. This result opens new perspectives for the application of Bi-based superconducting materials in the detection of a weak radio frequency signal, as in magnetic resonance imaging. (author)

  19. Process for producing clad superconductive materials

    International Nuclear Information System (INIS)

    Cass, R.B.; Ott, K.C.; Peterson, D.E.

    1992-01-01

    This patent describes a process for fabricating superconducting composite wire. It comprises placing a superconductive precursor admixture capable of undergoing self propagating combustion in stoichiometric amounts sufficient to form a superconductive product within an oxygen-porous metal tube; sealing one end of the tube; igniting the superconductive precursor admixture whereby the superconductive precursor admixture endburns along the length of the admixture; and cross-section reducing the tube at a rate substantially equal to the rate of burning of the superconductive precursor admixture and at a point substantially planar with the burnfront of the superconductive precursor mixture, whereby a clad superconductive product is formed in situ

  20. An in situ study of the annealing behaviour of BiSCCO Ag tapes

    DEFF Research Database (Denmark)

    Frello, T.; Poulsen, H.F.; Andersen, L.G.

    1999-01-01

    The phase transformations and structural changes occurring during initial heating and annealing of an Ag-clad high-T-c superconducting tape of the (Bi, Pb)(2)Sr2Ca2Cu3Ox type are investigated. The annealing takes place in air at an operating temperature of 835 degrees C. Using x-ray diffraction...... continuously. We interpret these results as being related to a temperature-dependent solubility limit of Pb in 2212, leading to a substantial grain growth of the phase. Above 812 degrees C 2212 partly decomposes to form (Ca, Sr)(2)CuO3 and a liquid. At the operating temperature 2212 and (Ca, Sr)(2)CuO3 react...... the annealing the 2212 linewidth is constant, implying that there is neither strain nor finite-size broadening of the 2212 peaks during the transformation. This points to a transformation mechanism where only a few 2212 grains transform at a given time. Implications of these findings are discussed in relation...

  1. Critical current density and flux pinning in superconducting wires and coils of silver-clad Bi-Pb-Sr-Ca-Cu-O

    International Nuclear Information System (INIS)

    Dou, S.X.; Liu, H.K.; Apperley, M.H.; Song, K.H.; Sorrell, C.C.; Guo, S.J.; Loberg, B.; Easterling, K.E.

    1991-01-01

    The critical current density (J c ) of Ag-clad of Bi-Pb-Sr-Ca-Cu-O has been measured to be about 12,000 A/cm 2 at 77 K in zero field. This wire was rolled into a tape of thickness 0.1 mm and width of 2 to 3 mm, and a coil of 35 mm diameter was formed. The J c of this coil was measured to be about 2,000 A/cm 2 at 77 K over the full length (1.00 meter) of the coil. In this paper compositions, heat treatment parameters, and cold-deformation for enhancement of J c are presented. The microstructure is characterized and pinning interactions as well as possible weak links are emphasised. (orig.)

  2. Electronic, phonon and superconducting properties of LaPtBi half-Heusler compound

    Science.gov (United States)

    Shrivastava, Deepika; Sanyal, Sankar P.

    2018-05-01

    In the framework of density functional theory based on plane wave pseudopotential method and linear response technique, we have studied the electronic, phonon and superconducting properties of LaPtBi half-Heusler compound. The electronic band structure and density of states show that it is gapless semiconductor which is consistent with previous results. The positive phonon frequencies confirm the stability of this compound in cubic MgAgAs phase. Superconductivity is studied in terms of Eliashberg spectral function (α2F(ω)), electron-phonon coupling constants (λ). The value of electron-phonon coupling parameter is found to be 0.41 and the superconducting transition temperature is calculated to be 0.76 K, in excellent agreement with the experimentally reported values.

  3. The superconductivity of Bi1.7Pb0.3Sr2-xAgxCa2Cu3Oy

    International Nuclear Information System (INIS)

    Yu, Y.

    1995-01-01

    It was discovered that the critical current density of BiSrCaCuO can be increased by cladding wires of this material with silver. Part of the cladding process is thermal annealing to 920 C. Although the empirical effects of this processing are well established, the effect of silver doping on T c and the structure of the lattice is not very clear. We studied this problem by substitution of Ag for Sr in BiSrCaCuO. The result reveals that T c0 of the sample increased to 99 K. (orig.)

  4. Microstructure and superconducting properties of Bi-2223/Ag tapes fabricated in the two-step sintering process

    International Nuclear Information System (INIS)

    Lu, X.Y.; Nagata, A.; Sugawara, K.

    2008-01-01

    The microstructure and superconducting properties of Bi-2223/Ag tapes fabricated in the two-step sintering process were investigated. The tapes were then subjected to two heat treatments with an intermediate rolling. All the tapes were sintered at 835 deg. C for 24 h at initial sintering stage. A two-step sintering procedure was then used in the final sintering stage. In the first step, the tapes are sintered at 840-865 deg. C for 1 h. In the second step, they were sintered at 835 deg. C for 120 h. The results show that the first step sintering temperature has significant influence on the microstructure and the critical current density J c . The observed microstructures are consistent well with the different J c performances of the tapes first-step-sintered at different temperatures. The tape first-step-sintered at 850 deg. C, which has small secondary phases, stronger c-axis grain alignment, higher proportion of Bi-2223 phase, and no cracks, exhibits the highest J c value

  5. Effect of Sintering Time and Diameter on Bi-Pb-Sr-Ca-Cu-O Superconducting Wire Formation with TiO2 Dopant by Silver (Ag Tube

    Directory of Open Access Journals (Sweden)

    Cindy Al Kindi

    2018-01-01

    Full Text Available Pengaruh waktu sintering dan diameter terhadap pembentukan kawat superkonduktor Bi-Pb-Sr-Ca-Cu-O dengan dopan TiO2 menggunakan tabung perak (Ag menjadi penting untuk dibahas karena hal ini berpengaruh terhadap adanya suhu kritis yang merupakan syarat penting superkonduktor. Pada penelitian ini ada beberapa tahap yang dilakukan yaitu preparasi bahan, proses permesinan, penarikan kawat dan proses perlakuan panas. Serbuk BPSCCO dengan dopan TiO2 dimasukkan ke dalam tabung perak (Ag dan dikalsinasi pada temperatur 820oC selama 20 jam, lalu proses penarikan (Rolling sampai diameter 6 mm dan 2,6 mm serta sintering dilakukan pada temperatur 850oC selama 9 jam dan 30 jam untuk masing-masing ukuran diameter dengan dua kali proses sintering. Hasil penelitian menunjukkan bahwa kawat superkonduktor memiliki suhu kritis yaitu Tc onset = 99 K dan Tc zero = 70 K. Waktu yang sangat berpengaruh pada pembentukan fasa superkonduktor yaitu sintering selama 9 jam sedangkan untuk ukuran diameter kawat yang memiliki suhu kritis yaitu 6 mm, sedangkan waktu sintering selama 30 jam dapat merubah fasa BPSCCO sehingga tidak terbentuk superkonduktor melainkan konduktor dan semikonduktor. Pada diameter 2,6 mm belum menjadi ukuran yang tepat pada pembentukan kawat superkonduktor.   The influence of sintering time and diameter on the formation of Bi-Pb-Sr-Ca-Cu-O superconducting wire with doped TiO2 by silver (Ag tube becomes important to be discussed because of the presence of critical temperature which is an essential condition in superconductors. In this research there are several steps must be done that is: material preparation, machine process, wire drawing and heat process. BPSCCO powder with dopant TiO2 filled into silver (Ag tube with calcination temperature at 820oC for 20 h, then rolling process to diameter 6 mm and 2,6 mm with sintering temperature at 850oC for 9 h and 30 h for each size of diameter by twice sintering process. The results showed that

  6. Design, processing, and properties of Bi 2212\\/Ag Rutherford cables

    CERN Document Server

    Collings, E W; Scanlan, R M; Dietderich, D R; Motowidlo, L R; Sokolowski, R S; Aoki, Y; Hasegawa, T

    1999-01-01

    In a program intended to explore the use of high temperature superconducting (HTSC) cables in high field synchrotron dipole magnets model Bi:2212/Ag Rutherford cables were designed bearing in mind the needs for mechanical integrity, relatively high tensile strength, and low coupling losses. To satisfy these needs a core-type cable design was selected and a readily available heat-resistant core material acquired. Cables were wound for critical current- and AC loss measurement. Both winding-induced (mechanical) and core-induced (chemical) critical current degradation was examined. Interstrand coupling loss was measured calorimetrically on model cable samples with bare- and oxide-coated cores. From the results it was predicted that the losses of full-scale Bi:2212/Ag-wound LHC-type Rutherford cables would fall close to the acceptability range for the windings of high-field accelerator dipoles. (10 refs).

  7. Electrical and mechanical properties of Bi-2223/Ag/barrier/Ag composite tapes

    International Nuclear Information System (INIS)

    Kovac, P.; Husek, I.; Goemoery, F.; Oduleye, O.O.; Alford, N.McN.; Pachla, W.; Diduszko, R.

    2000-01-01

    Bi-2223/Ag/barrier/Ag single-core tapes with various oxide barrier materials (BaZrO 3 , SrCO 3 , ZrO 2 and Al 2 O 3 ) have been prepared by PIT. The I-V curves and ac susceptibility measurements have been performed for tapes with identical heat treatment history. Young's moduli of these tape samples have been evaluated by three-point bending and the structure of barrier powders and BSCCO cores was analysed by SEM and XRD, respectively. It was found that the shape of I-V curves, the current transfer lengths and the mechanical properties of tapes are all affected by the oxide barrier type and the barrier thickness, as well as by its porosity and uniformity. This is because the oxide barrier controls the oxygen diffusion during the tape heat treatment and simultaneously the HTS phase formation kinetics, its purity and content within the superconducting core. On the base of the results obtained for single-core tapes, two kinds of multifilamentary composite were made and tested. (author)

  8. Distribution of local critical current along sample length and its relation to overall current in a long Bi2223/Ag superconducting composite tape

    International Nuclear Information System (INIS)

    Ochiai, S; Doko, D; Okuda, H; Oh, S S; Ha, D W

    2006-01-01

    The distribution of the local critical current and the n-value along the sample length and its relation to the overall critical current were studied experimentally and analytically for the bent multifilamentary Bi2223/Ag/Ag-Mg alloy superconducting composite tape. Then, based on the results, it was attempted to simulate on a computer the dependence of the critical current on the sample length. The main results are summarized as follows. The experimentally observed relation of the distributed local critical current and n-value to the overall critical current was described comprehensively with a simple voltage summation model, in which the sample was regarded as a one-dimensional series circuit. The sample length dependence of the critical current was reproduced on the computer by a Monte Carlo simulation incorporating the voltage summation model and the regression analysis results for the local critical current distribution and the relation of the n-value to the critical current

  9. Novel Bi/BiOBr/AgBr composite microspheres: Ion exchange synthesis and photocatalytic performance

    Science.gov (United States)

    Lyu, Jianchang; Li, Zhenlu; Ge, Ming

    2018-06-01

    Novel Bi/BiOBr/AgBr composite microspheres were prepared by a rational in situ ion exchange reaction between Bi/BiOBr microspheres and AgNO3. The characteristic of the as-obtained ternary microspheres was tested by X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL). Under visible light irradiation, Bi/BiOBr/AgBr microspheres exhibited an excellent photocatalytic efficiency for rhodamine B (RhB) degradation, which was about 1.4 and 4.9 times as high as that of Bi/BiOBr and BiOBr/AgBr, demonstrating that the highest separation efficiency of charge carriers in the heterostructured Bi/BiOBr/AgBr. The photocatalytic activity of Bi/BiOBr/AgBr microspheres just exhibited a slight decrease after three consecutive cycles. The photocatalytic mechanism investigation confirmed that the superoxide radicals (O2•-) were the dominant reactive oxygen species for RhB degradation in Bi/BiOBr/AgBr suspension.

  10. Bi-based superconducting fibers with high critical parameters

    International Nuclear Information System (INIS)

    Huo Yujing; He Yusheng; Liu Menglin; Mao Sining; Cai Liying; Wang Ying; Zhang Jincang; He Aisheng; Wang Jinsong

    1991-01-01

    Superconducting fibers of Bi(Pb)-Sr-Ca-Cu-O high Tc superconducting materials have been prepared by means of the laser-heated pedestal growth (LHPG) method. The highest zero resistance temperature T c0 reaches is 114K, and the highest critical current density J c (77K, O T) is greater than 5000 A/cm 2 . As-grown superconducting fibers were successfully fabricated without post growth heat treatment. Amorphous materials were used for the first time to make high quality fibers. The influence of growth conditions, thermal treatment and the composition of the fibers were discussed. (author). 5 refs., 7 figs., 3 tabs

  11. Development of heat resistant Pb-free joints by TLPS process of Ag and Sn-Bi-Ag alloy powders

    Directory of Open Access Journals (Sweden)

    Ohnuma I.

    2012-01-01

    Full Text Available TLPS (Transient Liquid Phase Sintering process is a candidate method of heat-resistant bonding, which makes use of the reaction between low-melting temperature powder of Sn-Bi base alloys and reactive powder of Ag. During heat treatment above the melting temperature of a Sn-Bi base alloy, the molten Sn-Bi reacts rapidly with solid Ag particles, which results in the formation of heat-resistant intermetallic compound (IMC. In this study, the TLPS properties between Sn-17Bi-1Ag (at.% powder with its liquidus temperature of 200°C and pure Ag powder were investigated. During differential scanning calorimetry (DSC measurement, an exothermic reaction and an endothermic reaction occurred, which correspond to the formation of the e-Ag3Sn IMC phase and the melting of the Sn-17Bi-1Ag alloy, respectively. After the overall measurement, the obtained reactant consists of the Ag3Sn-IMC and Bi-rich phases, both of which start melting above 250°C, with a small amount of the residual Sn-Bi eutectic phase. These results suggest that the TLPS process can be applied for Pb-free heatresistant bonding.

  12. Preparing superconducting nanopowder based YBCO/Ag tapes

    DEFF Research Database (Denmark)

    Paturi, P.; Raittila, J.; Grivel, J.C.

    2002-01-01

    YBCO nanopowder consisting of 1-3 nm thick and 40 nm wide particles has been used to make silver clad superconducting tapes. After annealing in nitrogen at 945 degreesC for 10 h a critical current of 5.02 A (3300 A/cm(2)) was attained, Annealing in mixed atmosphere of oxygen and nitrogen was also...... carried out and this procedure produced tapes with a critical current of 2.83 A (2200 A/cm(2)). These tapes show very good characteristics in magnetic fields. (C) 2002 Elsevier Science B.V. All rights reserved....

  13. Effect of Ag on the peritectic decomposition of Bi2Sr2CaCu2Ox

    International Nuclear Information System (INIS)

    Margulies, L.; Dennis, K.W.; Kramer, M.J.; McCallum, R.W.

    1995-01-01

    During the melt processing of superconducting wires and tapes a number of partial liquid phase regions are entered, and the type and amount of second phases that exist in the melt before cooling are critical in determining the microstructure of the final material. Decomposition pathway of Bi 2 Sr 2 CaCu 2 O x (Bi2212) with 0, 2, and 10 wt% Ag added was examined at 1 bar PO 2 by performing SAME/EDS analysis on oil quenched samples. A variety of quaternary phase diagrams were constructed to describe the evolution of the phase assemblage with temperature. At all Ag contents, Bi2212 first undergoes a peritectic reaction producing (Sr 1-x Ca x ) 14 Cu 24 O 41 (14,24), Bi 2 (Sr 1-x Ca x ) 4 O x (24x), and liquid

  14. The stability of high-Tc BSCCO/Ag superconducting microcomposites in water, some inorganic solutions and organic solvents

    International Nuclear Information System (INIS)

    Gao, W.; Chen, J.; Yang, C.O.; McNabb, D.; Sande, J. vander

    1992-01-01

    Bi(Pb)-Sr-Ca-Cu-O/Ag (BSCCO/Ag) superconducting microcomposites with zero-resistance temperatures from 102 to 108 K and critical current densities of ∝600 A/cm 2 at 77 K were produced by oxidation and annealling of metallic precursor alloys. The stabilities and degradation behavior of BSCCO/Ag specimens in various environments were studied by a combination of mass loss measurement, electrical transport measurement and microstructural observation. The environmental conditions used in the present work were moist air, distilled water, aqueous solutions of NaCl, NaOH and acetic acid, and organic solvents methanol and acetone. Although there is a general tendency toward a decrease in critical current density after a long exposure to most of the testing conditions, the specimens containing a high percent of Ag (≥70 wt.%) showed very little decrease in Tc and J c up to 200 days of exposure in moist air and distilled water, and up to 20 days in NaCl solution, methanol and acetone. It was found that the superconducting ''2223'' phase is stable in water, neutral solutions and the organic solvents, reacts very slowly with basic solutions, and dissolves rapidly in acidic solutions. Some non-superconducting Ca-rich oxides dissolve in water and neutral and basic solutions and therefore damage the connection of the superconducting grains in low-Ag containing specimens. The excellent stability of the BSCCO/Ag superconducting microcomposites containing high Ag provides an important advantage for their potential industrial application. (orig.)

  15. Thermal expansion properties of Bi-2212 in Ag or an Ag-alloy matrix

    International Nuclear Information System (INIS)

    Tenbrink, J.; Krauth, H.

    1994-01-01

    The thermal expansion properties of polycrystalline Bi 2 Sr 2 Ca 1 Cu 2 O 8+x melt-processed bulk specimens, and Bi 2 Sr 2 Ca 1 Cu 2 O 8+x monocore as well as multifilamentary round wires in Ag or Ag-alloy matrix have been investigated over the temperature range from -150 to 800 degrees C. Although the thermal expansion of Bi 2 Sr 2 Ca 1 Cu 2 O 8+x is distinctly lower compared with Ag, the thermal expansion properties of the Bi 2 Sr 2 Ca 1 Cu 2 O 8+x -Ag or AgNiMg-alloy composite conductors are essentially governed by the matrix material. The thermal expansion of the encountered oxide-dispersion-strengthened AgNiMg alloys is only slightly lower compared with that of pure Ag. Therefore the thermal expansion of all investigated Bi 2 Sr 2 Ca 1 Cu 2 O 8+x -Ag or Ag-alloy composite wires was found to be close to that of pure Ag. The reason for this striking behaviour is shown to be related to a surprisingly low elastic modulus of the polycrystalline Bi-2212 wire cores of the order of 10 to a maximum 40 GPa. (author)

  16. Design and fabrication of a 30 T superconducting solenoid using overpressure processed Bi2212 round wire

    Energy Technology Data Exchange (ETDEWEB)

    Flanagan, Gene [Muons, Inc., Batavia, IL (United States); Johnson, Rolland [Muons, Inc., Batavia, IL (United States)

    2016-02-18

    High field superconducting magnets are used in particle colliders, fusion energy devices, and spectrometers for medical imaging and advanced materials research. Magnets capable of generating fields of 20-30 T are needed by future accelerator facilities. A 20-30 T magnet will require the use of high-temperature superconductors (HTS) and therefore the challenges of high field HTS magnet development need to be addressed. Superconducting Bi2Sr2CaCu2Ox (Bi2212) conductors fabricated by the oxide-powder-in-tube (OPIT) technique have demonstrated the capability to carry large critical current density of 105 A/cm2 at 4.2 K and in magnetic fields up to 45 T. Available in round wire multi-filamentary form, Bi2212 may allow fabrication of 20-50 T superconducting magnets. Until recently the performance of Bi2212 has been limited by challenges in realizing high current densities (Jc ) in long lengths. This problem now is solved by the National High Magnetic Field Lab using an overpressure (OP) processing technique, which uses external pressure to process the conductor. OP processing also helps remove the ceramic leakage that results when Bi-2212 liquid leaks out from the sheath material and reacts with insulation, coil forms, and flanges. Significant advances have also been achieved in developing novel insulation materials (TiO2 coating) and Ag-Al sheath materials that have higher mechanical strengths than Ag-0.2wt.% Mg, developing heat treatment approaches to broadening the maximum process temperature window, and developing high-strength, mechanical reinforced Bi-2212 cables. In the Phase I work, we leveraged these new opportunities to prototype overpressure processed solenoids and test them in background fields of up to 14 T. Additionally a design of a fully superconducting 30 T solenoid was produced. This work in conjunction with the future path outlined in the Phase II proposal would

  17. Synthesis and chemistry of the new Y-Based and Bi-Based high temperature superconducting perovskites

    International Nuclear Information System (INIS)

    Tarascon, J.M.; Barboux, P.; Miceli, P.F.; Bagley, B.G.; Greene, L.H.; Hull, G.W.; Giroud, M.

    1988-01-01

    Chemical synstesis of the new high T c oxides using solid state reactions or solution techniques is shown. A solution process which allows the preparation of both homogeneous and dense ceramics and of superconducting thick films has been developed for the YBa 2 Cu 3 O 7 system. Physical measurements performed on homogeneous YBa 2 Cu 3-x Co x O y samples have shown that the Co substitution, associated with an uptake of oxygen, takes place on the Cu-O chains and that T c is depressed, leading ultimately to antiferromagnetic insulators whose magnetic structures are shown. Three phases of general formula Bi 2 Sr 2 Ca n-1 Cu n O y with n = 1,2 and 3 have been isolated in the Bi system and characterized for their structural and physical properties. These phases crystallize in the same pseudotetragonal unit cell differing one from the next by the stacking sequence along the c-axis, with the main feature being the presence of a sheared Bi-O double layer. The T c s of the n = 1,2 and 3 phases are 10 K, 85 K and 110 K respectively, but because of phase intergrowth, these values depend upon sample processing, making chemical substitutions within the Bi system quite complex as is discussed. Finally, we succeeded in making superconducting thick films (having zero resistance around 100 K) of the Bi-based and T1-based matrials via the decomposition of aqueous-glycerol solutions containing the salts of the elements

  18. Crystal Structure of AgBi2I7 Thin Films.

    Science.gov (United States)

    Xiao, Zewen; Meng, Weiwei; Mitzi, David B; Yan, Yanfa

    2016-10-06

    Synthesis of cubic-phase AgBi 2 I 7 iodobismuthate thin films and fabrication of air-stable Pb-free solar cells using the AgBi 2 I 7 absorber have recently been reported. On the basis of X-ray diffraction (XRD) analysis and nominal composition, it was suggested that the synthesized films have a cubic ThZr 2 H 7 crystal structure with AgBi 2 I 7 stoichiometry. Through careful examination of the proposed structure and computational evaluation of the phase stability and bandgap, we find that the reported "AgBi 2 I 7 " films cannot be forming with the ThZr 2 H 7 -type structure, but rather more likely adopt an Ag-deficient AgBiI 4 type. Both the experimental X-ray diffraction pattern and bandgap can be better explained by the AgBiI 4 structure. Additionally, the proposed AgBiI 4 structure, with octahedral bismuth coordination, removes unphysically short Bi-I bonding within the [BiI 8 ] hexahedra of the ThZr 2 I 7 model. Our results provide critical insights for assessing the photovoltaic properties of AgBi 2 I 7 iodobismuthate materials.

  19. Efecto de la adición de Ag en Bi-2212 texturado mediante laser

    Directory of Open Access Journals (Sweden)

    Mora, M.

    2005-08-01

    Full Text Available The addition of Ag into Bi-2212 compounds has demonstrated to be a suitable method to improve both, the thermal and mechanical properties as well as the electrical ones. The final properties have been found to be in strong dependence of Ag content and the processing technique. In the present work the influence of Ag addition on Bi-2212 bulk materials grown from the melt, using a laser floating zone melting technique, has been studied. Samples with different Ag contents (0 to 40 wt.% were prepared for this work. The Bi-2212 + x wt.% Ag powders have been prepared by a sol-gel method via nitrates to assure total cation solution, small particle size and good homogeneity in the mixture. Cylindrical precursors, fabricated from these powders, were used as feed in a LFZ melting installation to obtain textured Bi-2212/Ag composites. The effect of the Ag addition on the microstructure is analysed as a function of Ag content. The changes on the microstructure are also correlated with the mechanical and superconducting properties.

    La incorporación de Ag en los compuestos de Bi-2212 ha demostrado ser un método adecuado para mejorar tanto las propiedades mecánicas, térmicas como eléctricas de estos materiales. Las propiedades finales dependen fuertemente de la cantidad de Ag añadida al sistema pero también del tipo de procesado que sufre. En el presente trabajo se realiza un estudio del efecto de la adición de Ag en materiales masivos Bi-2212 texturados mediante fusión zonal inducida por láser, con el objetivo de comprender el efecto de la adición de Ag en sistemas Bi-2212 que pasan totalmente por un fundido. Para ello se preparon muestras con diferentes contenidos en Ag (hasta el 40% en peso. Debido a la inmiscibilidad en estado sólido de la Ag y del Bi-2212, se ha utilizado un método de síntesis de estos materiales por medio de técnicas sol-gel para asegurar una buena homogeneidad y un tamaño de partícula reducido en la cerámica de

  20. Ag doped (Bi1.6Pb0.4Sr2CaCu2O8+δ textured rods

    Directory of Open Access Journals (Sweden)

    Díez, J. C.

    2008-06-01

    Full Text Available In this work, superconducting samples of (Bi1.6Pb0.4Sr2CaCu2O8+δ with Ag additions have been studied. (Bi1.6Pb0.4Sr2CaCu2O8+δ + x wt.% Ag (with x = 0, 1 and 3 powders were synthesized using a sol-gel method. The obtained powders were used as precursors to fabricate long textured cylindrical bars through a floating zone melting method. A drastic change on the microstructure has been found when comparing with undoped Bi2Sr2CaCu2O8+δ samples. The results showed that electrical resistivity at room temperature, critical current as well as flexural strength are improved when Ag is added to these Pb doped samples, while critical temperature does not change. On the other hand, it has been found that samples with composition (Bi1.6Pb0.4Sr2CaCu2O8+δ + Ag shown E-I curves with very high sharpness values on the zone of the superconducting to normal transition, reaching n-values (E∼In as high as 45 at 65K.Se han preparado polvos cerámicos de composición (Bi1.6Pb0.4Sr2CaCu2O8+δ + x % Ag en peso (con x = 0, 1 y 3 mediante un proceso sol-gel. Estos polvos se han utilizado para fabricar precursores que se texturaron por medio del método de fusión zonal flotante. Se ha encontrado un gran cambio en la microestructura cuando se compara con muestras de composición pura Bi2Sr2CaCu2O8+δ. Tanto la resistividad eléctrica a temperatura ambiente, como la corriente crítica, así como la resistencia a flexión se mejoran cuando la Ag se adiciona a estas muestras dopadas con Pb, mientras que no se observa cambio en la temperatura crítica. Por otra parte, se ha encontrado que las muestras de composición (Bi1.6Pb0.4Sr2CaCu2O8+δ + Ag presentan una gran pendiente de la curva E-I en la zona de transición entre el estado superconductor y el estado normal. Con estas composiciones, se han encontrado valores de n (E∼In de hasta 45 a 65K.

  1. Nano Ag@AgBr surface-sensitized Bi{sub 2}WO{sub 6} photocatalyst: oil-in-water synthesis and enhanced photocatalytic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shuanglong; Liu, Li; Hu, Jinshan; Liang, Yinghua, E-mail: liangyh@heuu.edu.cn; Cui, Wenquan, E-mail: wkcui@163.com

    2015-01-01

    }WO{sub 6}. Additionally, studies performed using radical scavengers indicated that O{sub 2}{sup −•} , • OH and Br{sup 0} acted as the main reactive species. Based on above, a photocatalytic mechanism for organics degradation over Ag@AgBr/Bi{sub 2}WO{sub 6} was proposed.

  2. Influence of microscopic inhomogeneity on macroscopic transport current of Ag/Bi2223 tapes

    International Nuclear Information System (INIS)

    Ogawa, Kazuhiro; Osamura, Kozo

    2004-01-01

    In Ag/Bi2223 tapes, inhomogeneities such as spatially distributed weak links or non-superconducting oxides are inevitably introduced because of the complicated manufacturing process and thermodynamic instability. In order to clarify the effect of the difference in such microscopic inhomogeneites on the macroscopic current transport properties, we carried out a numerical analysis. By changing volume fraction (V f ) of the Bi2223 phase and the shape of local distribution of critical current at each weak link, it is revealed that I-V characteristics are largely affected by the breadth of local distributions with different dependence on V f of Bi2223 and calculated results can be analyzed by Weibull distribution function with some parameters including the information of two-dimensional distribution

  3. Synthesis of Bi{sub 1.8}Pb{sub 0.4}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} superconductor

    Science.gov (United States)

    Smith, M.G.

    1996-10-29

    Two-powder processes for the synthesis of superconducting (Bi, Pb)-2223/Ag-clad wires by the oxide-powder-in-the-robe are provided. The first precursor powder, of nominal stoichiometry CaCuO{sub x}, is a solution-synthesized mixture of Ca{sub 0.45}Cu{sub 0.55}O{sub 2} and CaO. Using these oxide precursor mixtures, superconducting tapes with well-aligned grains and reproducible critical current densities J{sub c} in the range of 20,000 to 26,000 A/cm{sup 2} at 75 K in self-field after annealing less than 200 hours were obtained. 2 figs.

  4. Bi3+–Pr3+ energy transfer processes and luminescent properties of LuAG:Bi,Pr and YAG:Bi,Pr single crystalline films

    International Nuclear Information System (INIS)

    Zorenko, Y.; Gorbenko, V.; Savchyn, V.; Zorenko, T.; Nikl, M.; Mares, J.A.; Beitlerova, A.; Jary, V.

    2013-01-01

    Absorption, cathodoluminescence, excitation spectra of photoluminescence (PL) and PL decay kinetics were studied at 300 K for the double doped with Bi 3+ –Pr 3+ and separately doped with Bi 3+ and Pr 3+ Lu 3 Al 5 O 12 (LuAG) and Y 3 Al 5 O 12 (YAG) single crystalline film (SCF) phosphors grown by the liquid phase epitaxy method. The emission bands in the UV range arising from the intrinsic radiative transitions of Bi 3+ based centers, and emission bands in the visible range, related to the luminescence of excitons localized around Bi 3+ based centers, were identified both in Bi–Pr and Bi-doped LuAG and YAG SCFs. The energy transfer processes from the host lattice simultaneously to Bi 3+ and Pr 3+ ions and from Bi 3+ to Pr 3+ ions were investigated. Competition between Pr 3+ and Bi 3+ ions in the energy transfer processes from the LuAG and YAG hosts was evidenced. The strong decrease of the intensity of Pr 3+ luminescence both in LuAG:Pr and YAG:Pr SCFs phosphors, grown from Bi 2 O 3 flux, is observed due to the quenching influence of Bi 3+ flux related impurity. Due to overlap of the UV emission band of Bi 3+ centers with the f–d absorption bands of Pr 3+ ions in the UV range and the luminescence of excitons localized around Bi ions with the f–f absorption bands of Pr 3+ ions in the visible range, an effective energy transfer from Bi 3+ ions to Pr 3+ ions takes place in LuAG:Bi,Pr and YAG:Bi,Pr SCFs, resulting in the appearance of slower component in the decay kinetics of the Pr 3+ d–f luminescence. -- Highlights: • Bi and Pr doped film phosphor grown by liquid phase epitaxy method. • Energy transfer from Bi 3+ to Pr 3+ ions. • Strong quenching of the Pr 3+ luminescence by Bi 3+ co-dopant

  5. Synthesis and chemistry of the new Y-Based and Bi-Based high temperature superconducting perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Tarascon, J.M.; Barboux, P.; Miceli, P.F.; Bagley, B.G.; Greene, L.H.; Hull, G.W.; Giroud, M.

    1988-12-01

    Chemical synstesis of the new high T{sub c} oxides using solid state reactions or solution techniques is shown. A solution process which allows the preparation of both homogeneous and dense ceramics and of superconducting thick films has been developed for the YBa{sub 2}Cu{sub 3}O{sub 7} system. Physical measurements performed on homogeneous YBa{sub 2}Cu{sub 3-x}Co{sub x}O{sub y} samples have shown that the Co substitution, associated with an uptake of oxygen, takes place on the Cu-O chains and that T{sub c} is depressed, leading ultimately to antiferromagnetic insulators whose magnetic structures are shown. Three phases of general formula Bi{sub 2}Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub y} with n = 1,2 and 3 have been isolated in the Bi system and characterized for their structural and physical properties. These phases crystallize in the same pseudotetragonal unit cell differing one from the next by the stacking sequence along the c-axis, with the main feature being the presence of a sheared Bi-O double layer. The T{sub c}s of the n = 1,2 and 3 phases are 10 K, 85 K and 110 K respectively, but because of phase intergrowth, these values depend upon sample processing, making chemical substitutions within the Bi system quite complex as is discussed. Finally, we succeeded in making superconducting thick films (having zero resistance around 100 K) of the Bi-based and T1-based matrials via the decomposition of aqueous-glycerol solutions containing the salts of the elements.

  6. The effect of the ceramic core initial phase composition on the Ag-sheathed Bi-2223 tapes critical properties

    International Nuclear Information System (INIS)

    Nikulin, A.D.; Shikov, A.K.; Khlebova, N.E.; Antipova, E.V.; Dontsova, E.V.; Kazakov, E.G.; Medvedev, M.I.; Kozlenkova, N.I.; Shishov, V.N.; Akimov, I.I.

    1993-01-01

    Ag - sheathed superconducting tapes were fabricated using ''powder-in-tube'' method with powders of Bi 1.6 Pb 0.4 Sr 2 Ca 2 Cu 3.2 O x chemical composition prepared by the ''freeze-drying'' tecnique and taken as a core materials. The effect of ceramic core initial phase composition: the mixture of oxide non-superconducting phases - OP (typeI) and 50% OP + 50% OP ''2212''- phase (type II) on the critical current density was investigated as well as the ''annealing - cold pressing'' parameters. Multifilamentary superconducting tapes and the pancake coils were fabricated. (orig.)

  7. Co-doping induced coexistence of superconductivity and ferromagnetism in Bi{sub 3.9}Co{sub 0.1}O{sub 4}S{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Chuan [Department of Physics, Shanghai University, Shanghai 200444 (China); Feng, Zhenjie, E-mail: fengzhenjie@t.shu.edu.cn [Department of Physics, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai 200444 (China); Yin, Xunqing; Li, Qing; Kang, Baojuan [Department of Physics, Shanghai University, Shanghai 200444 (China); Lu, Bo [Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Jing, Chao; Cao, Shixun [Department of Physics, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai 200444 (China); Zhang, Jincang [Department of Physics, Shanghai University, Shanghai 200444 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China)

    2016-09-15

    Highlights: • Bi{sub 4}O{sub 4}S{sub 3} is a new discovered layered superconductor. Some doping effects, such as Ag, Cu, and Pb, are studied, the superconductivity is suppressed in these doping samples. We doped the Ni magnetic ions to the system, it is interesting that the superconductivity is not suppressed in x = 0.1 sample. Meanwhile, the coexistence of the superconductivity and magnetism is observed in the samples from the M-vs. –H loops. - Abstract: The effects of Co doping on the physical properties of the Bi{sub 4}O{sub 4}S{sub 3} system was studied. We discovered that stable Bi{sub 3.9}Co{sub 0.1}O{sub 4}S{sub 3} compound exhibits both long-range ferromagnetism and enhanced superconductivity with thermodynamic evidences for Tc ∼ 5.5 K. We found that there is an anomalous feature which represents superconducting transition in the hysteretic M-vs.-H loops for Bi{sub 3.9}Co{sub 0.1}O{sub 4}S{sub 3} at T = 3 K.

  8. The inhomogeneities of (Pb,Bi)2223 superconducting tapes and their detection

    International Nuclear Information System (INIS)

    Leeuwen, S. van

    1999-05-01

    This thesis consists of two parts: first, the inhomogeneities that were observed in high temperature superconducting (Pb,Bi)2223 tapes were studied followed by the design of two rigs which were built to detect them. These investigations concentrated on (Pb,Bi)2223 phase high temperature superconducting tapes. Superconductors and their applications were briefly evaluated. It was found that high temperature superconductors have unique properties which cannot be duplicated by their counterparts. However, it was noted that there are significant improvements to be made before they can be commercially viable. An investigation was carried out into the variation of core density within cross sections and along lengths of (Pb,Bi)2223 tapes during fabrication. It was observed that rolling and thermal treatment brought about a non-uniform core density in both these aspects of tile tape. This was followed by an investigation into the effect of core density on the formation of the (Pb,Bi)2223 phase. It was shown that a high core density formed the (Pb,Bi)2223 phase at a slower rate than a lower core density under the thermal treatment. A high core density and a slow heating rate produced smaller 2212 grains at the end of the incubation period. Smaller 2212 grains were thought to be linked to the faster formation of the (Pb,B1)2223 phase. The highest Jc was from a high core density tape which had the smaller 2212 grains at the end of incubation period. Smaller 2212 grains were thought to aid a more homogeneous conversion to the (Pb,Bi)2223 phase. Alloy-sheathed (Pb,Bi)2223 superconducting tapes were produced in order to fabricate a more homogeneous core density. It was found that the alloy sheath (with an addition of 15% wt Ag in the precursor powder) changed the characteristics of the core in several ways: the formation of the (Pb,Bi)2223 phase was homogeneous across the thickness of the core, a smaller 2212 grain size was formed at the end of the incubation period and a higher

  9. Kinetics and thermodynamics of ceramic/metal interface reactions related to high T(sub c) superconducting applications

    Science.gov (United States)

    Notis, Michael R.; Oh, Min-Seok

    1990-01-01

    Superconducting ceramic materials, no matter what their form, size or shape, must eventually make contact with non-superconducting materials in order to accomplish current transfer to other parts of a real operating system, or for testing and measurement of properties. Thus, whether the configuration is a clad wire, a bulk superconducting disc, tape, or a thick or thin superconducting film on a substrate, the physical and mechanical behavior of interface (interconnections, joints, etc.) between superconductors and normal conductor materials of all kinds is of extreme importance to the technological development of these systems. Fabrication heat treatments associated with the particular joining process allow possible reactions between the superconducting ceramic and the contact to occur, and consequently influence properties at the interface region. The nature of these reactions is therefore of great broad interest, as these may be a primary determinant for the real capability of these materials. Research related both to fabrication of composite sheathed wire products, and the joining contacts for physical property measurements, as well as, a review of other related literature in the field are described. Comparison are made between 1-2-3, Bi-, and Tl-based ceramic superconductors joined to a variety of metals including Cu, Ni, Fe, Cr, Ag, Ag-Pd, Au, In, and Ga. The morphology of reaction products and the nature of interface degradation as a function of time will be highlighted.

  10. Microwave-assisted solvothermal synthesis of flower-like Ag/AgBr/BiOBr microspheres and their high efficient photocatalytic degradation for p-nitrophenol

    International Nuclear Information System (INIS)

    Li, Tingting; Luo, Shenglian; Yang, Lixia

    2013-01-01

    Flower-like Ag/AgBr/BiOBr microspheres were successfully fabricated by the approach of microwave-assisted solvothermal and in situ photo-assisted reduction. A reactive ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C 16 mim]Br) was employed as Br source in the presence of surfactant polyvinylpyrrolidone (PVP). The photocatalytic activity of Ag/AgBr/BiOBr towards the decomposition of p-nitrophenol under visible light irradiation was evaluated. The results indicated that Ag/AgBr/BiOBr showed enhanced photocatalytic activity towards p-nitrophenol, comparing with P25, BiOBr and Ag/AgBr. More than 96% of p-nitrophenol was decomposed in 3.5 h under visible-light irradation. The excellent photocatalytic activity of flower-like Ag/AgBr/BiOBr microspheres can be attributed to the large specific surface area, strong visible-light absorption, suitable energy band structure and surface plasmon resonance effect of Ag nanoparticles. The possible photocatalytic mechanism was proposed based on the active species test and band gap structure analysis. - Graphical abstract: The photocatalytic reaction mechanisms of the as-prepared Ag/AgBr/BiOBr. Display Omitted - Highlights: • Successful synthesis of flower-like Ag/AgBr/BiOBr microspheres. • The Ag/AgBr/BiOBr showed much higher photocatalytic activity towards p-nitrophenol as compared to BiOBr and Ag/AgBr. • The reasons for the excellent photocatalytic activity are the large specific surface area, strong visible-light absorption and surface plasmon resonance effect of Ag nanoparticles. • The O 2 · − , Br 0 and photogenerated h + play key roles in the photocatalytic degradation process

  11. Magneto-optical investigations of Ag-sheathed Bi-2223 tapes with ferromagnetic shielding

    International Nuclear Information System (INIS)

    Yurchenko, V.V.; Shantsev, D.V.; Galperin, Y.M.; Alamgir, A.K.M.; Han, Z.; Johansen, T.H.

    2007-01-01

    An increase in the critical current and suppression of AC losses in superconducting wires and tapes with soft magnetic sheath have been predicted theoretically and confirmed experimentally. In this work we present the results of magneto-optical investigations on a series of Ag-sheathed Bi-2223 tapes with Ni coating. We visualize distributions of magnetic field at increasing external field and different temperatures, demonstrating a difference between the flux propagation in the superconductor with Ni rims and a reference sample without Ni coating

  12. Magneto-optical investigations of Ag-sheathed Bi-2223 tapes with ferromagnetic shielding

    Energy Technology Data Exchange (ETDEWEB)

    Yurchenko, V.V.; Shantsev, D.V.; Galperin, Y.M. [University of Oslo, Department of Physics, P.O. Box 1048, Blindern, 0316 Oslo (Norway); Alamgir, A.K.M.; Han, Z. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Johansen, T.H. [University of Oslo, Department of Physics, P.O. Box 1048, Blindern, 0316 Oslo (Norway)], E-mail: tomhj@fys.uio.no

    2007-09-01

    An increase in the critical current and suppression of AC losses in superconducting wires and tapes with soft magnetic sheath have been predicted theoretically and confirmed experimentally. In this work we present the results of magneto-optical investigations on a series of Ag-sheathed Bi-2223 tapes with Ni coating. We visualize distributions of magnetic field at increasing external field and different temperatures, demonstrating a difference between the flux propagation in the superconductor with Ni rims and a reference sample without Ni coating.

  13. Production of BiPbSrCaCuO thin films on MgO and Ag/MgO substrates by electron beam deposition techniques

    CERN Document Server

    Varilci, A; Gorur, O; Celebi, S; Karaca, I

    2002-01-01

    Superconducting BiPbSrCaCuO thin films were prepared on MgO(001) and Ag/MgO substrates using an electron beam (e-beam) evaporation technique. The effects of annealing temperature and Ag diffusion on the crystalline structure and some superconducting properties, respectively, were investigated by X-ray diffraction, atomic force microscopy, and by measurements of the critical temperature and the critical current density. It was shown that an annealing of both types of films at 845 or 860 C resulted in the formation of mixed Bi-2223 and Bi-2212 phases with a high degree of preferential orientation with the c-axis perpendicular to the substrates. The slight increase of the critical temperature from 103 K to 105 K, the enhancement of the critical current density from 2 x 10 sup 3 to 6 x 10 sup 4 A/cm sup 2 , and the improved surface smoothness are due to a possible silver doping from the substrate. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  14. Effect of composition on the fabrication and properties of Ag-Cu alloy sheathed (Bi,Pb)2223 tapes

    International Nuclear Information System (INIS)

    Nakamura, Yuichi; Nakashima, Sohei; Inada, Ryoji; Oota, Akio

    2004-01-01

    To achieve high J c values as well as high mechanical strength, the effects of Ag-Cu alloy sheath and initial composition of precursor on the microstructure and J c properties of Ag-Cu alloy sheathed tapes were investigated. The alkaline-earth cuprate particles were found to form preferentially near the interface between superconducting core and sheath. Although the worse (Bi,Pb)2223 purity and microstructure of alloy sheathed tapes, the reduction of J c values of the tapes was small especially in 7-filaments tapes. This might be explained by the well grain alignment of (Bi,Pb)2223 into the middle region of the filament due to the high strength of alloy sheath. The usage of the Cu deficient composition was effective to reduce the total amount of 14:24 particle while the filament thickness should be thin to maintain J c values for Ag-Cu alloy sheathed tapes due to the lack of Cu diffusion from the sheath to convert 2212 into (Bi,Pb) in the middle region of the filament

  15. The mechanical deformation of superconducting BiSrCaCuO/Ag composites

    International Nuclear Information System (INIS)

    Han, Z.; Skov-Hansen, P.; Freltoft, T.

    1997-01-01

    The mechanical deformation of BiSrCaCuO/Ag composites made by the powder-in-tube method is a multi-step process. The main difficulty is that the mechanical properties of the ceramic powder are very different from those of the Ag sheath. A key parameter is the core density, which changes during mechanical deformation. In this review, basic concepts of the classical mechanical deformation theory are briefly discussed. Simple descriptions of deformation processes like pressing, rolling, drawing and extrusion are also presented. The term 'freedom parameter', Δ f , is introduced to illustrate the influence of various constraint factors on the mass-flow behaviour. Simple pictures including mass redistribution and the powder-flow model are presented for interpreting the plastic deformation process of the composites. Experimental results are reviewed and our proposed pictures and models are applied for discussion. (author)

  16. Processing and characterization of superconducting solenoids made of Bi-2212/Ag-alloy multifilament round wire for high field magnet applications

    Science.gov (United States)

    Chen, Peng

    -off and full coil reaction. The coil was successfully tested at the NHMFL generating 33.8 T combined magnetic field in a 31.2 T background field. Multiple quenches occurred safely, which also illustrates that the insulation provided sufficient dielectric standoff. For Bi-2212 RW with a typical as-drawn diameter of 1.0-1.5 mm, this 15 microm thick insulation allows a very high coil packing factor of ~0.74, whereas earlier alumino-silicate braid insulation only allows packing factors of 0.38-0.48. In addition to the commercial TiO2/polymer insulation, we have also investigated sol-gel based ceramic coatings through collaboration with Harran University and another TiO2 based insulation coating at the NHMFL. Since Bi-2212 superconducting coils employ the Wind-and-React (W&R) technology, there are some potential issues in processing Bi-2212 coils, in particular for coils with a large thermal mass and dense oxide insulation coating. For this study, several Bi-2212 test solenoids with an outer diameter (OD) of about 90 mm were built and heat treated in 1 bar flowing oxygen with deadweights applied so as to simulate large coil packs. After the heat treatment (HT), coils were epoxy impregnated and cut. Winding pack was checked using SEM in terms of conductor geometry and insulation. Some samples were extracted to measure transport critical current Ic and critical temperature Tc. The results are very promising: test coils presented low creep behavior after standard partial melt HT under mechanical load, and no Ic degradation was found due to the application of mechanical load, and no inadequate oxygenation issue was seen for thick coils with ceramic coating on the wire. However, coils were partially electrically shorted after 1 bar HT under mechanical load, and we believe that increasing insulation coating thickness is necessary. In addition, several small solenoids were manufactured to study OP processing of Bi-2212 coils. The preliminary results indicate that there are some gaps

  17. Enhancement of superconductivity near the pressure-induced semiconductor-metal transition in the BiS₂-based superconductors LnO₀.₅F₀.₅BiS₂ (Ln = La, Ce, Pr, Nd).

    Science.gov (United States)

    Wolowiec, C T; White, B D; Jeon, I; Yazici, D; Huang, K; Maple, M B

    2013-10-23

    Measurements of electrical resistivity were performed between 3 and 300 K at various pressures up to 2.8 GPa on the BiS2-based superconductors LnO0.5F0.5BiS2 (Ln=Pr, Nd). At lower pressures, PrO0.5F0.5BiS2 and NdO0.5F0.5BiS2 exhibit superconductivity with critical temperatures Tc of 3.5 and 3.9 K, respectively. As pressure is increased, both compounds undergo a transition at a pressure Pt from a low Tc superconducting phase to a high Tc superconducting phase in which Tc reaches maximum values of 7.6 and 6.4 K for PrO0.5F0.5BiS2 and NdO0.5F0.5BiS2, respectively. The pressure-induced transition is characterized by a rapid increase in Tc within a small range in pressure of ∼0.3 GPa for both compounds. In the normal state of PrO0.5F0.5BiS2, the transition pressure Pt correlates with the pressure where the suppression of semiconducting behaviour saturates. In the normal state of NdO0.5F0.5BiS2, Pt is coincident with a semiconductor-metal transition. This behaviour is similar to the results recently reported for the LnO0.5F0.5BiS2 (Ln=La, Ce) compounds. We observe that Pt and the size of the jump in Tc between the two superconducting phases both scale with the lanthanide element in LnO0.5F0.5BiS2 (Ln=La, Ce, Pr, Nd).

  18. Composite metallic sheathes: the key to low-cost, high strength (Bi,Pb)2Sr2Ca2Cu3O10-based tapes?

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude

    2007-01-01

    (Bi, Pb)(2)Sr2Ca2Cu3O10-based superconducting tapes were prepared by the powder- in- tube process, using a bimetallic sheath consisting of Ag and Ni. Ag was in contact with the superconducting ceramic core and acted as a protective layer against reaction between the external Ni sheath and the cor...

  19. Comparative study on the critical current performance of Bi-2223/Ag and YBCO wires in low magnetic fields at liquid nitrogen temperature

    International Nuclear Information System (INIS)

    Feng, F.; Qu, T.-M.; Gu, C.; Xin, Y.; Gong, W.-Z.; Wu, W.; Han, Z.

    2011-01-01

    Highlights: → The I c values of Bi-2223/Ag and YBCO wires in low fields at 77 K were compared. → The performance of Bi-2223/Ag in low parallel fields was better than that of YBCO. → The phenomenon mentioned above can be verified by the published literature datum. → A new aspect was brought to understand the transport properties of HTS wires. - Abstract: A comparative study on the critical current performance of Bi-2223/Ag and YBCO coated conductor wires in low magnetic fields at liquid nitrogen temperature was carried out in this work. Five commercial high temperature superconductor wires from different manufacturers were collected. Their critical currents were measured in magnetic fields, ranging from 0 to 0.4 T. On contrary to the common conception, the Bi-2223/Ag samples had better performance than YBCO coated conductor samples in the magnetic fields parallel to the wide surface of superconducting wires within the experimental scope. We also found similar results by collecting the concerned datum from the published literatures to confirm our measurement results. At the present stage, this fact made that the Bi-2223/Ag wires might be the preferred choice for the applications with mainly low parallel fields involved, unless other considerations were prioritized.

  20. Progress in Jc and magnetic field performance of Bi-2223/Ag composite tapes

    International Nuclear Information System (INIS)

    Savvides, N.; Katsaros, A.; Reilly, D.; Thorley, A.; Herrmann, J.

    1998-01-01

    Full text: The application of high-temperature superconductors to electric power systems is actively pursued by several commercial teams around the world. A promising candidate is the Bi-2223/Ag composite superconductor. For large scale commercial applications the conductor must meet certain engineering specifications including high current capacity in the presence of a self-generated magnetic field ranging from a few hundred mT in transmission cables to 1-2 T in transformers and current limiters, and to much higher fields in the case of superconducting coils for energy storage and magnets. In the last two years, a commercial consortium consisting of Metal Manufactures Ltd, University of Wollongong and CSIRO has focused on the development of Bi-2223/Ag composite tape suitable for use in electric power applications. The powder-in-tube process is used to produce conventional single filament and multifilament tapes and twisted conductors. An appropriate measure of 'process capability' is routine running of the process and evaluation of tape performance. In this paper we report on the electrical properties of Bi-2223/Ag composite tapes produced as part of the long-length product development. The transport critical current density of tapes is measured in magnetic fields up to 9 T (H parallel and H perpendicular tape-plane) and as a function of temperature (4 - 80 K). Transport ac losses are determined at 77 K and 60 Hz, and the bend strain performance is determined at 77 K for strains up to 1.5 %

  1. Effects of Bi Addition on the Microstructure and Mechanical Properties of Nanocrystalline Ag Coatings

    Directory of Open Access Journals (Sweden)

    Yuxin Wang

    2017-08-01

    Full Text Available In this study we investigated the effects of Bi addition on the microstructure and mechanical properties of an electrodeposited nanocrystalline Ag coating. Microstructural features were investigated with transmission electron microscopy (TEM. The results indicate that the addition of Bi introduced nanometer-scale Ag-Bi solid solution particles and more internal defects to the initial Ag microstructures. The anisotropic elastic-plastic properties of the Ag nanocrystalline coating with and without Bi addition were examined with nanoindentation experiments in conjunction with the recently-developed inverse method. The results indicate that the as-deposited nanocrystalline Ag coating contained high mechanical anisotropy. With the addition of 1 atomic percent (at% Bi, the anisotropy within Ag-Bi coating was very small, and yield strength of the nanocrystalline Ag-Bi alloy in both longitudinal and transverse directions were improved by over 100% compared to that of Ag. On the other hand, the strain-hardening exponent of Ag-Bi was reduced to 0.055 from the original 0.16 of the Ag coating. Furthermore, the addition of Bi only slightly increased the electrical resistivity of the Ag-Bi coating in comparison to Ag. Results of our study indicate that Bi addition is a promising method for improving the mechanical and physical performances of Ag coating for electrical contacts.

  2. Proposal of 99.99%-aluminum/7N01-Aluminum clad beam tube for high energy booster of Superconducting Super Collider

    International Nuclear Information System (INIS)

    Ishimaru, Hajime

    1994-01-01

    Proposal of 99.99% pure aluminum/7N01 aluminum alloy clad beam tube for high energy booster in Superconducting Super Collider is described. This aluminum clad beam tube has many good performances, but a eddy current effect is large in superconducting magnet quench collapse. The quench test result for aluminum clad beam tube is basically no problem against magnet quench collapse. (author)

  3. Ag/AgCl Loaded Bi2WO6 Composite: A Plasmonic Z-Scheme Visible Light-Responsive Photocatalyst

    Directory of Open Access Journals (Sweden)

    Xiangchao Meng

    2016-01-01

    Full Text Available Hierarchical flower-like Bi2WO6 was successfully synthesized by facile hydrothermal method at low pH. And Ag/AgCl was loaded by photoreduction on its surface. As-prepared photocatalysts were characterized by various techniques. Bi2WO6 was successfully synthesized at a size of 2-3 μm. Depositing Ag/AgCl did not destroy the crystal structure, and both Ag+ and metallic Ag0 were found. The band gap of the composite was 2.57 eV, which indicates that visible light could be the activating irradiation. In the photocatalytic activity test, the composite with 10 wt% Ag/AgCl boasted the highest removal efficiency (almost 100% in 45 min. The significant enhancement can be attributed to the surface plasmon resonance (SPR effect and the establishment of heterostructures between Ag/AgCl and Bi2WO6. A possible mechanism of photocatalytic oxidation in the presence of Ag/AgCl-Bi2WO6 was proposed. This work sheds light on the potential applications of plasmonic metals in photocatalysis to enhance their activities.

  4. Superconducting properties of Pb82Bi18 films controlled by ferromagnetic nanowire arrays

    International Nuclear Information System (INIS)

    Ye Zuxin; Lyuksyutov, Igor F; Wu Wenhao; Naugle, Donald G

    2011-01-01

    The superconducting properties of Pb 82 Bi 18 alloy films deposited on ferromagnetic nanowire arrays have been investigated. Ferromagnetic Co or Ni nanowires are first electroplated into the columnar pores of anodic aluminum oxide (AAO) membranes. Superconducting Pb 82 Bi 18 films are then quench condensed onto the polished surface of the AAO membranes filled with magnetic nanowires. A strong dependence of the Pb 82 Bi 18 superconducting properties on the ratio of the superconducting film thickness to the magnetic nanowire diameter and material variety was observed.

  5. Superconducting properties of Pb82Bi18 films controlled by ferromagnetic nanowire arrays

    Science.gov (United States)

    Ye, Zuxin; Lyuksyutov, Igor F.; Wu, Wenhao; Naugle, Donald G.

    2011-02-01

    The superconducting properties of Pb82Bi18 alloy films deposited on ferromagnetic nanowire arrays have been investigated. Ferromagnetic Co or Ni nanowires are first electroplated into the columnar pores of anodic aluminum oxide (AAO) membranes. Superconducting Pb82Bi18 films are then quench condensed onto the polished surface of the AAO membranes filled with magnetic nanowires. A strong dependence of the Pb82Bi18 superconducting properties on the ratio of the superconducting film thickness to the magnetic nanowire diameter and material variety was observed.

  6. Design of medium band gap Ag-Bi-Nb-O and Ag-Bi-Ta-O semiconductors for driving direct water splitting with visible light.

    Science.gov (United States)

    Wang, Limin; Cao, Bingfei; Kang, Wei; Hybertsen, Mark; Maeda, Kazuhiko; Domen, Kazunari; Khalifah, Peter G

    2013-08-19

    Two new metal oxide semiconductors belonging to the Ag-Bi-M-O (M = Nb, Ta) chemical systems have been synthesized as candidate compounds for driving overall water splitting with visible light on the basis of cosubstitution of Ag and Bi on the A-site position of known Ca2M2O7 pyrochlores. The low-valence band edge energies of typical oxide semiconductors prevents direct water splitting in compounds with band gaps below 3.0 eV, a limitation which these compounds are designed to overcome through the incorporation of low-lying Ag 4d(10) and Bi 6s(2) states into compounds of nominal composition "AgBiM2O7". It was found that the "AgBiTa2O7" pyrochlores are in fact a solid solution with an approximate range of Ag(x)Bi(5/6)Ta2O(6.25+x/2) with 0.5 semiconductors with the onset of strong direct absorption at 2.72 and 2.96 eV, respectively. Electronic structure calculations for an ordered AgBiNb2O7 structure show that the band gap reduction and the elevation of the valence band primarily result from hybridized Ag d(10)-O 2p orbitals that lie at higher energy than the normal O 2p states in typical pyrochlore oxides. While the minimum energy gap is direct in the band structure, the lowest energy dipole allowed optical transitions start about 0.2 eV higher in energy than the minimum energy transition and involve different bands. This suggests that the minimum electronic band gap in these materials is slightly smaller than the onset energy for strong absorption in the optical measurements. The elevated valence band energies of the niobate and tantalate compounds are experimentally confirmed by the ability of these compounds to reduce 2 H(+) to H2 gas when illuminated after functionalization with a Pt cocatalyst.

  7. Superconducting transition in TlBiTe/sub 2/ and TlTe compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kantser, V G; Popovich, N S; Sidorenko, A S

    1985-10-01

    On the basis of zone structure calculation for TlBiTe/sub 2/ and TlTe it is found that TlBiTe/sub 2/ is a narrow-gap semiconductor and TlTe is a p-metal. At Tsub(c)=0.19 K TlTe is found to experience the superconducting transition. In TlBiTe/sub 2/ superconductivity is not observed to occur up to 0.05 K, since there is a possibility of occupying the high density of states zones because they are remote from actual ones. The earlier discovered superconducting transition in TlBiTe/sub 2/ is inherent in the alien phase of TlTe.

  8. Fabrication of laminated Bi-2212/Ag multifilamentary tape

    Science.gov (United States)

    Yuan, D.-W.; Majer, W. J.; Francavilla, T. L.

    2000-03-01

    The powder-in-tube (PIT) process has been successfully used to make long lengths of Ag-sheathed oxide superconductors. A modified PIT approach is proposed to fabricate conductors with laminated Bi-2212 configurations. Ag/Bi-2212 tapes consisting of seven laminae were produced with various thicknesses ranging from 0.38 to 0.25 mm. The use of a turkshead was found to be beneficial, yielding tapes with good dimensional integrity and consistency. Critical current density (Jc ) values greater than 105 A cm-2 (0.01 T and Bicons/Journals/Common/perp" ALT="perp" ALIGN="TOP"/> tape surface) have been attained for tapes of different thicknesses. Nonetheless, Jc was found to be related to the average thickness of individual Bi-2212 lamina. It is believed that excessive cold working accounts for the decrease in Jc with decreasing size below a threshold value. The enhancement of Jc is attributed to the high Bi-2212 grain alignment along the Ag-oxide interfaces and uniform dimensions within the laminate conductors.

  9. Superconductivity with twofold symmetry in Bi2Te3/FeTe0.55Se0.45 heterostructures

    Science.gov (United States)

    Du, Zengyi

    2018-01-01

    Topological superconductors are an interesting and frontier topic in condensed matter physics. In the superconducting state, an order parameter will be established with the basic or subsidiary symmetry of the crystalline lattice. In doped Bi2Se3 or Bi2Te3 with a basic threefold symmetry, it was predicted, however, that bulk superconductivity with order parameters of twofold symmetry may exist because of the presence of odd parity. We report the proximity effect–induced superconductivity in the Bi2Te3 thin film on top of the iron-based superconductor FeTe0.55Se0.45. By using the quasiparticle interference technique, we demonstrate clear evidence of twofold symmetry of the superconducting gap. The gap minimum is along one of the main crystalline axes following the so-called Δ4y notation. This is also accompanied by the elongated vortex shape mapped out by the density of states within the superconducting gap. Our results provide an easily accessible platform for investigating possible topological superconductivity in Bi2Te3/FeTe0.55Se0.45 heterostructures. PMID:29888330

  10. Effect of Bi-content on hardness and micro-creep behavior of Sn-3.5Ag rapidly solidified alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kamal, M. [Metal Physics Laboratory, Faculty of Science, Mansoura University (Egypt); Gouda, El Said [Metal Physics Laboratory, Department of Solid State Physics, Physics Division, National Research Center, Dokki, Giza (Egypt); Marei, L.K. [Faculty of Petroleum and Mining Engineering, Suez Canal University, Suez (Egypt)

    2009-12-15

    In the present paper, the influence of 1, 3, 5 and 10 % Bi (weight %) as ternary additions on structure, melting and mechanical properties of rapidly solidified Sn-3.5Ag alloy has been investigated. The effect of Bi was discussed based on the experimental results. The experimental results showed that the alloys of Sn-3.5Ag, Sn-3.5Ag-1Bi and Sn-3.5Ag-3Bi are composed of two phases; Ag{sub 3}Sn IMC embedded in Sn matrix phase, which indicated that the solubility of Bi phase in Sn-matrix was extended to 3 % as a result of rapid solidification. Bi precipitation in Sn matrix was only observed in Sn-3.5Ag-5Bi and Sn-3.5Ag-10Bi alloys. Also, addition of Bi decreased continuously the melting point of the eutectic Sn-3.5Ag alloy to 202.6 C at 10 % Bi. Vickers hardness of Sn-3.5Ag rapidly solidified alloy increased with increasing Bi content up to 3 % due to supersaturated solid solution strengthening hardening mechanism of Bi phase in Sn matrix, while the alloys contain 5 and 10 % Bi exhibited lower values of Vickers hardness. The lower values can be attributed to the precipitation of Bi as a secondary phase which may form strained regions due to the embrittlement of Bi atom. In addition, the effect of Bi addition on the micro-creep behavior of Sn-3.5Ag alloy as well as the creep rate have been described and has been calculated at room temperature. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Enhanced Visible Light Photocatalytic Degradation of Organic Pollutants over Flower-Like Bi2O2CO3 Dotted with Ag@AgBr

    Directory of Open Access Journals (Sweden)

    Shuanglong Lin

    2016-10-01

    Full Text Available A facile and feasible oil-in-water self-assembly approach was developed to synthesize flower-like Ag@AgBr/Bi2O2CO3 micro-composites. The photocatalytic activities of the samples were evaluated through methylene blue degradation under visible light irradiation. Compared to Bi2O2CO3, flower-like Ag@AgBr/Bi2O2CO3 micro-composites show enhanced photocatalytic activities. In addition, results indicate that both the physicochemical properties and associated photocatalytic activities of Ag@AgBr/Bi2O2CO3 composites are shown to be dependent on the loading quantity of Ag@AgBr. The highest photocatalytic performance was achieved at 7 wt % Ag@AgBr, degrading 95.18% methylene blue (MB after 20 min of irradiation, which is over 1.52 and 3.56 times more efficient than that of pure Ag@AgBr and pure Bi2O2CO3, respectively. Bisphenol A (BPA was also degraded to further demonstrate the degradation ability of Ag@AgBr/Bi2O2CO3. A photocatalytic mechanism for the degradation of organic compounds over Ag@AgBr/Bi2O2CO3 was proposed. Results from this study illustrate an entirely new approach to fabricate semiconductor composites containing Ag@AgX/bismuth (X = a halogen.

  12. Experimental formation of a fractional vortex in a superconducting bi-layer

    Science.gov (United States)

    Tanaka, Y.; Yamamori, H.; Yanagisawa, T.; Nishio, T.; Arisawa, S.

    2018-05-01

    We report the experimental formation of a fractional vortex generated by using a thin superconducting bi-layer in the form of a niobium bi-layer, observed as a magnetic flux distribution image taken by a scanning superconducting quantum interference device (SQUID) microscope. Thus, we demonstrated that multi-component superconductivity can be realized by an s-wave conventional superconductor, because, in these superconductors, the magnetic flux is no longer quantized as it is destroyed by the existence of an inter-component phase soliton (i-soliton).

  13. Pb induces superconductivity in Bi2Se3 analyzed by point contact spectroscopy

    OpenAIRE

    Arevalo-López, P.; López-Romero, R. E.; Escudero, R.

    2015-01-01

    Some topological insulators become superconducting when doped with Cu and Pd. Superconductivity in a non-superconductor may be induced by proximity effect: i.e. Contacting a non-superconductor with a superconductor. The superconducting macroscopic wave function will induce electronic pairing into the normal compound. In the simplest topological insulator, Bi$_2$Se$_3$, superconductivity may be induced with Pb. We studied with point contact junctions formed by contacting Bi$_2$Se$_3$ crystals ...

  14. Fabrication, characterization and photocatalytic properties of Ag/AgI/BiOI heteronanostructures supported on rectorite via a cation-exchange method

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yunfang [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Fang, Jianzhang, E-mail: fangjzh@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China); Lu, Shaoyou [Shenzhen Center for Disease Control and Prevention, Shenzhen 518055 (China); Wu, Yan; Chen, Dazhi; Huang, Liyan [Institute of Engineering Technology of Guangdong Province, Key Laboratory of Water Environmental Pollution Control of Guangdong Province, Guangzhou 510440 (China); Xu, Weicheng; Zhu, Ximiao [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Fang, Zhanqiang [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China)

    2015-04-15

    Highlights: • Ag/AgI/BiOI-rectorite was prepared by twice cation-exchange process. • Ag/AgI/BiOI-rectorite photocatalyst possessed SPR and adsorption capacity. • Ag/AgI/BiOI-rectorite exhibited highly photocatalytic activity. • Trapped holes and ·O{sub 2}{sup −} were formed active species in the photocatalytic system. - Abstract: In this work, a new plasmonic photocatalyst Ag/AgI/BiOI-rectorite was prepared via a cation exchange process. The photocatalyst had been characterized by X-ray powder diffraction (XRD), Raman spectra, nitrogen sorption (BET), field-emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity, which was evaluated by degradation of rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation, was enhanced significantly by loading Ag/AgI/BiOI nanoparticles onto rectorite. The photogenerated holes and superoxide radical (·O{sub 2}{sup −}) were both formed as active species for the photocatalytic reactions under visible light irradiation. The existence of metallic Ag particles, which possess the surface plasmon resonance effect, acted as an indispensable role in the photocatalytic reaction.

  15. Chemical casting of high-Tc superconducting BiSCCO

    International Nuclear Information System (INIS)

    Toth, L.E.; Das, B.N.; Rayne, R.J.; Bender, B.A.; Lechter, W.L.; Hoff, H.A.; Osofsky, M.S.; Soulen, R.J. Jr.

    1989-01-01

    BiSCCO has been successfully cast into a number of useful shapes. This casting process differs significantly from traditional casting in that the process includes a change in the oxygen content of the melt. A heat treatment is required to restore the original chemistry, properly form the BiSCCO crystal structure and develop the superconducting properties. This paper emphasizes the microstructures of as-cast and heat treated BiSCCO. Casting causes considerable grain alignment of the BiSCCO platelets. The platelets align preferentially along the thermal gradients which exist during the solidification process

  16. Magnetotransport and induced superconductivity in Bi based three-dimensional topological insulators

    International Nuclear Information System (INIS)

    Veldhorst, M.; Snelder, M.; Hoek, M.; Molenaar, C.G.; Leusink, D.P.; Golubov, A.A.; Hilgenkamp, H.; Brinkman, A.

    2013-01-01

    The surface of a three-dimensional (3D) topological insulator is conducting and the topologically nontrivial nature of the surface states is observed in experiments. It is the aim of this paper to review and analyze experimental observations with respect to the magnetotransport in Bi-based 3D topological insulators, as well as the superconducting transport properties of hybrid structures consisting of superconductors and these topological insulators. The helical spin-momentum coupling of the surface state electrons becomes visible in quantum corrections to the conductivity and magnetoresistance oscillations. An analysis will be provided of the reported magnetoresistance, also in the presence of bulk conductivity shunts. Special attention is given to the large and linear magnetoresistance. Superconductivity can be induced in topological superconductors by means of the proximity effect. The induced supercurrents, Josephson effects and current-phase relations will be reviewed. These materials hold great potential in the field of spintronics and the route towards Majorana devices. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Magnetotransport and induced superconductivity in Bi based three-dimensional topological insulators

    Energy Technology Data Exchange (ETDEWEB)

    Veldhorst, M.; Snelder, M.; Hoek, M.; Molenaar, C.G.; Leusink, D.P.; Golubov, A.A.; Hilgenkamp, H.; Brinkman, A. [MESA + Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2013-02-15

    The surface of a three-dimensional (3D) topological insulator is conducting and the topologically nontrivial nature of the surface states is observed in experiments. It is the aim of this paper to review and analyze experimental observations with respect to the magnetotransport in Bi-based 3D topological insulators, as well as the superconducting transport properties of hybrid structures consisting of superconductors and these topological insulators. The helical spin-momentum coupling of the surface state electrons becomes visible in quantum corrections to the conductivity and magnetoresistance oscillations. An analysis will be provided of the reported magnetoresistance, also in the presence of bulk conductivity shunts. Special attention is given to the large and linear magnetoresistance. Superconductivity can be induced in topological superconductors by means of the proximity effect. The induced supercurrents, Josephson effects and current-phase relations will be reviewed. These materials hold great potential in the field of spintronics and the route towards Majorana devices. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Growth, characterization, and physical properties of Bi-Sr-Ca-Cu-O superconducting whiskers

    International Nuclear Information System (INIS)

    Kraak, W.; Thiele, P.

    1996-01-01

    Single crystal whiskers of the Bi-based high-T c superconductors have been grown directly from the stoichiometric melt. Conditions for the preferable growth of the (2212) phase and annealing conditions for the conversion from the (2212) phase to the (2223) and (2234) Bi-based superconducting phases are achieved. The orientation and chemical composition of the crystals were characterized by X-ray diffractometry and energy dispersive X-ray analysis. Characteristic structural properties of the whiskers (incommensurable modulation in b-direction, peculiarities of dislocation networks) have been revealed by transmission electron microscopy and electron diffraction. Some special features of the broad superconducting transition in multiphase whiskers have been examined by spatially resolved measurements using low-temperature scanning electron microscopy. (orig.)

  19. The effect of Ag doping on superconducting properties of the Bi-Pb-Sr-Ca-Cu-O tape fabricated by an Ag sheath

    International Nuclear Information System (INIS)

    Oota, A.; Horio, T.; Ohba, K.; Iwasaki, K.

    1992-01-01

    The powder-in-tube method using an Ag sheath is applied to achieve high current capacity in the tapes of Bi-Pb-Sr-Ca-Cu-O (BPSCCO) with the high-T c phase (T c =110 K), by a combination process of cold working and sintering. Two kinds of the BPSCCO powder with and without Ag doping are used as the materials for tape fabrication. The morphology, structure, and critical current density J c are investigated on the tapes by x-ray diffraction, differential thermal analysis, scanning electron microscope, magnetic susceptibility, and I-V curves. The optimum sintering conditions to obtain a maximum in the value of J c at 77 K and 0 T are presented in the Ag-doped tapes and the nondoped ones. An improvement in the J c vs B properties up to 1 T at 77 K is presented in the BPSCCO tape by Ag doping. The Ag doping causes neither change in the value of T c (=110 K) nor decomposition of the high-T c phase

  20. Composite ceramic superconducting wires for electric motor applications

    Science.gov (United States)

    Halloran, John W.

    1990-07-01

    Several types of HTSC wire have been produced and two types of HTSC motors are being built. Hundreds of meters of Ag- clad wire were fabricated from YBa2Cu3O(7-x) (Y-123) and Bi2Ca2Sr2Cu3O10 (BiSCCO). The dc homopolar motor coils are not yet completed, but multiple turns of wire have been wound on the coil bobbins to characterize the superconducting properties of coiled wire. Multifilamentary conductors were fabricated as cables and coils. The sintered polycrystalline wire has self-field critical current densities (Jc) as high as 2800 A/sq cm, but the Jc falls rapidly with magnetic field. To improve Jc, sintered YBCO wire is melt textured with a continuous process which has produced textures wire up to 0.5 meters long with 77K transport Jc above 11, 770 A/sq cm2 in self field and 2100 A/sq cm2 at 1 telsa. The Emerson Electric dc homopolar HTSC motor has been fabricated and run with conventional copper coils. A novel class of potential very powerful superconducting motors have been designed to use trapped flux in melt textures Y-123 as magnet replicas in an new type of permanent magnet motor. The stator element and part of the rotor of the first prototype machine exist, and the HTSC magnet replica segments are being fabricated.

  1. Effect of axial strain on the critical current of Ag-sheathed Bi-based superconductors in magnetic fields up to 25 T

    International Nuclear Information System (INIS)

    Ekin, J.W.; Finnemore, D.K.; Li, Q.; Tenbrink, J.; Carter, W.

    1992-01-01

    The irreversible strain limit ε irrev for the onset of permanent axial strain damage to Ag-sheathed Bi 2 Sr 2 Ca 1 Cu 2 O 8+x and Bi 2 Sr 2 Ca 2 Cu 3 O 10+x superconductors has been measured to be in the range of 0.2%--0.35%. This strain damage onset is about an order of magnitude higher than for bulk sintered Y-, Bi-, or Tl-based superconductors and is approaching practical values for magnet design. The measurements show that the value of ε irrev is not dependent on magnetic field, nor does the critical current depend on strain below ε irrev at least up to 25 T at 4.2 K. Both of these factors indicate that the observed strain effect in Ag-sheathed Bi-based superconductors is not intrinsic to the superconductor material. Rather, the effect is extrinsic and arises from superconductor fracture. Thus, the damage onset is amenable to further enhancement. Indeed, the data suggest that subdividing the superconductor into fine filaments or adding Ag to the superconductor powder prior to processing significantly enhances the damage threshold ε irrev to above 0.6%

  2. Synthesis and photocatalytic properties of MgBi2O6 with Ag additions

    Science.gov (United States)

    Zhong, Liansheng; Hu, Chaohao; Zhu, Binqing; Zhong, Yan; Zhou, Huaiying

    2018-02-01

    Ag-doped MgBi2O6 photocatalysts were synthesized by the low temperature hydrothermal method in combination with heat treatment reaction using NaBiO3·2H2O, MgCl2·6H2O, and AgNO3 as raw materials. The products were characterized by using power X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Energy dispersive X-ray detector (EDS), and UV-Vis diffusion reflectance spectra. The photocatalytic activity of MgBi2O6 with Ag additions was evaluated by degrading MB (10 mg/L) under visible light irradiation (λ > 420 nm). The results showed that in comparison with pure MgBi2O6, the photocatalytic activity of MgBi2O6 with about 5% Ag concentration is increased by about 24% after 120 min reaction. The enhancement of catalytic activity of Ag-doped MgBi2O6 photocatalysts should be related to the band structure, morphology and larger specific surface area.

  3. Facile synthesis of AgI/BiOI-Bi{sub 2}O{sub 3} multi-heterojunctions with high visible light activity for Cr(VI) reduction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qi [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); The Brook Byer Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta 30332 (United States); Shi, Xiaodong; Liu, Enqin [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); Crittenden, John C. [The Brook Byer Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta 30332 (United States); Ma, Xiangjuan; Zhang, Yi [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); Cong, Yanqing, E-mail: yqcong@hotmail.com [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China)

    2016-11-05

    Graphical abstract: Highly visible-light-active AgI/BiOI-Bi{sub 2}O{sub 3} with multi-heterojunctions was developed. - Highlights: • Visible-light-active AgI/BiOI-Bi{sub 2}O{sub 3} with multi-heterojunctions was prepared. • Highly enhanced photocatalytic reduction of Cr(VI) was observed. • k{sub Cr(VI)} on AgI/BiOI-Bi{sub 2}O{sub 3} increased by ca.16 times relative to Bi{sub 2}O{sub 3}. • Decreased E{sub g}, shifted E{sub fb} and reduced charge transfer resistance were observed. • Simultaneous reduction of Cr(VI) and degradation of organics were achieved. - Abstract: AgI sensitized BiOI-Bi{sub 2}O{sub 3} composite (AgI/BiOI-Bi{sub 2}O{sub 3}) with multi-heterojunctions was prepared using simple etching-deposition process. Different characterization techniques were performed to investigate the structural, optical and electrical properties of the as-prepared photocatalysts. It was found that the ternary AgI/BiOI-Bi{sub 2}O{sub 3} composite exhibited: (1) improved photocurrent response, (2) smaller band gap, (3) greatly reduced charge transfer resistance and (4) negative shift of flat band potential, which finally led to easier generation and more efficient separation of photo-generated electron-hole pairs at the hetero-interfaces. Thus, for the reduction of Cr(VI), AgI/BiOI-Bi{sub 2}O{sub 3} exhibited excellent photocatalytic activity under visible light irradiation at near neutral pH. AgI/BiOI-Bi{sub 2}O{sub 3} was optimized when the initial molar ratio of KI to Bi{sub 2}O{sub 3} and AgNO{sub 3} to Bi{sub 2}O{sub 3} was 1:1 and 10%, respectively. The estimated k{sub Cr(VI)} on optimized AgI/BiOI-Bi{sub 2}O{sub 3} was about 16 times that on pure Bi{sub 2}O{sub 3}. Good stability was also observed in cyclic runs, indicating that the current multi-heterostructured photocatalyst is highly desirable for the remediation of Cr(VI)-containing wastewater.

  4. High-pressure studies of superconductivity in BiO0. 75F0. 25BiS2

    Indian Academy of Sciences (India)

    ). We have investigated the effect of pressure on magnetization measurements. Our studies suggest improved superconducting properties in polycrystalline samples of BiO 0.75 F 0.25 BiS 2 . The Tc in our sample is 5.3 K, at ambient pressure, ...

  5. Superconductivity in the Bi-Sr-Ca-Cu-O compounds some characteristics

    International Nuclear Information System (INIS)

    Escudero, R.

    1989-01-01

    The authors have prepared 90% single phase bulk samples of the 110K superconducting phase of the Bi-Sr- Ca-Cu-O compounds with different Pb amounts. This paper presents critical superconducting temperatures (zero resistance) of up to 109K were measured in the bulk samples. X-ray powder diffraction patterns of the almost isolated 110K phase. Computer simulated diffractograms were obtained, which are in general agreement with the measured ones. A discussion of the role of Pb in the stability of the 110K phase in this compounds is presented. Tunnelling measurements were made using Bi-based material. The authors studied break junctions and point contact junctions. The energy gap was determined to be about 25.5 meV and the ratio 2Δ/KBTc = 7.5. The data also show structure at energies of 67 and 120 meV

  6. Pressure induced superconductivity in the antiferromagnetic Dirac material BaMnBi2.

    Science.gov (United States)

    Chen, Huimin; Li, Lin; Zhu, Qinqing; Yang, Jinhu; Chen, Bin; Mao, Qianhui; Du, Jianhua; Wang, Hangdong; Fang, Minghu

    2017-05-09

    The so-called Dirac materials such as graphene and topological insulators are a new class of matter different from conventional metals and (doped) semiconductors. Superconductivity induced by doing or applying pressure in these systems may be unconventional, or host mysterious Majorana fermions. Here, we report a successfully observation of pressure-induced superconductivity in an antiferromagnetic Dirac material BaMnBi 2 with T c of ~4 K at 2.6 GPa. Both the higher upper critical field, μ 0 H c2 (0) ~ 7 Tesla, and the measured current independent of T c precludes that superconductivity is ascribed to the Bi impurity. The similarity in ρ ab (B) linear behavior at high magnetic fields measured at 2 K both at ambient pressure (non-superconductivity) and 2.6 GPa (superconductivity, but at the normal state), as well as the smooth and similar change of resistivity with pressure measured at 7 K and 300 K in zero field, suggests that there may be no structure transition occurred below 2.6 GPa, and superconductivity observed here may emerge in the same phase with Dirac fermions. Our findings imply that BaMnBi 2 may provide another platform for studying SC mechanism in the system with Dirac fermions.

  7. Microscopic fracture of filaments and its relation to the critical current under bending deformation in (Bi,Pb)2Sr2Ca2Cu3O10 composite superconducting tapes

    International Nuclear Information System (INIS)

    Hojo, Masaki; Nakamura, Mitsuhiro; Matsuoka, Tomoe; Tanaka, Mototsugu; Ochiai, Shojiro; Sugano, Michinaka; Osamura, Kozo

    2003-01-01

    The strain dependence of the critical current, I c , of (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10 (Bi2223)/Ag/Ag-Mg composite superconducting tapes has been studied both experimentally and analytically under bending deformation. Tests have been carried out for one type of tape used in the VAMAS bending round-robin programme. The complex stress-strain behaviour of each component was first analysed in tension. This was done by comparing the stress-strain curves of composite tapes with those of Ag and Ag-Mg alloy tapes. Here, the plastic deformation (work hardening) of Ag and Ag-Mg alloy, and the thermal residual strain due to the manufacturing process were taken into account. The fracture strain of Bi2223 filaments was inversely determined as 0.08% to meet the global tensile stress-strain curve of the composite tape. The calculated stress-strain curves finally agreed well with the experimental results when the as-supplied bending strain was taken into account. Then, the analysis was modified to fit the bending deformation. Here, the movement of the neutral axis due to the non-symmetric and elastic-plastic stress-strain curves of the components and their Bauschinger effect were taken into account. The relative decrease of I c with the increase in the Bi2223 tape curvature was calculated from the volume fraction of the broken filaments. The calculated I c agreed well with the experimental results when the movement of the neutral axis and the Bauschinger effect were taken into account. Microscopic observation of the spatial distribution of the filament fracture indicated that the damage occurred at the outermost layer on the tensile side when the curvature was small, and then the damage front shifted to the inside layers. The observed fracture behaviour of the Bi2223 filament agreed well with the estimated location based on the above analysis

  8. Tensile damage and its influence on the critical current of Bi2223/Ag superconducting composite tape

    International Nuclear Information System (INIS)

    Ochiai, S; Nagai, T; Okuda, H; Oh, S S; Hojo, M; Tanaka, M; Sugano, M; Osamura, K

    2003-01-01

    We have studied the tensile behaviour of Bi2223 superconducting composite tapes at room temperature, and the influence of the tensile damages introduced at room temperature on the critical current I c and the n values at 77 K. In the measurement of the I c and n values, the overall composite with a gauge length 60 mm was divided into six elements with a gauge length of 10 mm in order to find the correlation of the I c and n values of the overall composite to those of the local elements which constitute the composite. From the measured stress-strain curve of the composite and the calculated residual strain of the Bi2223 filaments, the intrinsic fracture strain of Bi2223 filaments was estimated to be 0.09-0.12%. When the applied strain was lower than the onset strain of the filament damage, the original I c and n values were retained both in the overall composite and the elements. In this situation, while the overall voltage at the transition from superconductivity to normal conductivity of the composite was the sum of the voltages of the constituent elements, among all elements the overall voltage was affected more by the element with the lower I c (higher voltage). The damage of the filaments arose first locally, resulting in a reduction of the I c and n values in the corresponding local element, even though the other elements retained the original I c and n values. In this situation, the voltage of the overall composite stemmed dominantly from that of the firstly damaged weakest element, and the overall I c and n values were almost determined by the values of such an element. After the local element was fully damaged, the damage arose also in other elements, resulting in segmentation of the filaments. Thus, the I c and n values were reduced in all elements. The correlation of I c between the overall composite and the elements could be described comprehensively for non-damaged and damaged states from the voltage-current relation

  9. Enhanced photocatalytic performance of BiVO_4 in aqueous AgNO_3 solution under visible light irradiation

    International Nuclear Information System (INIS)

    Huang, Chien-Kai; Wu, Tsunghsueh; Huang, Chang-Wei; Lai, Chi-Yung; Wu, Mei-Yao; Lin, Yang-Wei

    2017-01-01

    Graphical abstract: Ag"+ ions enhanced photocatalytic activity of BiVO_4 under visible light irradiation. - Highlights: • The presence of Ag"+ ions enhanced the photodegradation activity of BiVO_4. • Photoreduction of Ag deposited on the BiVO_4 surface was obtained. • Luminescence and electrochemical results elucidated the photocatalytic mechanism. • Holes and oxygen radicals were the main reactive species generated by BiVO_4/Ag"+. • Used BiVO_4/Ag"+ exhibited photocatalytic antibacterial activity toward E. coli. - Abstract: Monoclinic-phase bismuth vanadate (BiVO_4) with a 2.468 eV band gap exhibited enhanced synergic photodegradation activity toward methylene blue (MB) when combined with silver ions (Ag"+) in an aqueous solution under visible light irradiation. The mass ratio of AgNO_3 to BiVO_4 and the calcination temperature were discovered to considerably affect the degradation activity of BiVO_4/Ag"+. Superior photocatalytic performance was obtained when BiVO_4 was mixed with 0.01%(w/v) AgNO_3 solution, and complete degradation of MB was achieved after 25 min visible light irradiation, outperforming BiVO_4 or AgNO_3 solution alone. The enhanced photodegradation was investigated using systematic luminescence measurements, electrochemical impedance spectroscopy, and scavenger addition, after which a photocatalytic mechanism for MB degradation under visible light irradiation was identified that involved oxygen radicals and holes. This study also discovered the two dominating processes involved in enhancing the electron–hole separation efficiency and reducing their recombination rate, namely photoreduction of Ag"+ and the formation of a BiVO_4/Ag heterojunction. The synergic effect between BiVO_4 and Ag"+ was discovered to be unique. BiVO_4/Ag"+ was successfully used to degrade two other dyes and disinfect Escherichia Coli. A unique fluorescent technique using BiVO_4 and a R6G solution to detect Ag"+ ions in water was discovered.

  10. Control of texture in Ag and Ag-alloy substrates for superconducting tapes

    International Nuclear Information System (INIS)

    Gladstone, T.A.

    2000-01-01

    The use of a biaxially textured silver tape as a substrate for high temperature superconductor (HTS) phases is one possible route towards the fabrication of high-J c superconducting tape. Using a cold-rolling and annealing process we have reproducibly fabricated {110} textured silver which is stable up to 900 deg. C. We have found that there are two critical process requirements for the formation of this texture; a low oxygen content in the material prior to deformation, and a cold-rolling thickness reduction of less than 97%. To overcome the problems associated with the poor mechanical strength of pure silver, texture development in Ag-Mg and Ag-Hf alloys with improved mechanical properties has been studied. Heat treatments in a reducing atmosphere allow the {110} annealing texture to be obtained in Ag-0.1 wt%Mg. The recrystallization behaviour of a Ag-Pd alloy with an increased stacking fault energy was also investigated and a partial cube texture was obtained in this material. Using orientation distribution function (ODF) analysis we have shown that minor variations in the deformation texture of both pure silver and Ag-based alloys can lead to significant differences in the recrystallization textures obtained. (author)

  11. Tuning the giant Rashba effect on a BiAg2 surface alloy: Two different approaches

    International Nuclear Information System (INIS)

    Frantzeskakis, E.; Crepaldi, A.; Pons, S.; Kern, K.; Grioni, M.

    2010-01-01

    We discuss two different approaches for tuning the giant spin-orbit splitting of a BiAg 2 surface alloy. The first approach consists of electron doping by alkaline metal deposition in order to shift the energy position of the spin-split surface states, while the second is based on the novel Si(1 1 1)-Ag-BiAg 2 trilayer system. In both cases the spin-polarized structure near the Fermi level can be controlled by an external parameter, while the second approach permits coupling the concept of giant spin-splitting with a semiconducting substrate.

  12. Role of valence changes and nanoscale atomic displacements in BiS2-based superconductors.

    Science.gov (United States)

    Cheng, Jie; Zhai, Huifei; Wang, Yu; Xu, Wei; Liu, Shengli; Cao, Guanghan

    2016-11-22

    Superconductivity within layered crystal structures has attracted sustained interest among condensed matter community, primarily due to their exotic superconducting properties. EuBiS 2 F is a newly discovered member in the BiS 2 -based superconducting family, which shows superconductivity at 0.3 K without extrinsic doping. With 50 at.% Ce substitution for Eu, superconductivity is enhanced with Tc increased up to 2.2 K. However, the mechanisms for the T c enhancement have not yet been elucidated. In this study, the Ce-doping effect on the self-electron-doped superconductor EuBiS 2 F was investigated by X-ray absorption spectroscopy (XAS). We have established a relationship between Ce-doping and the T c enhancement in terms of Eu valence changes and nanoscale atomic displacements. The new finding sheds light on the interplay among superconductivity, charge and local structure in BiS 2 -based superconductors.

  13. Development of Bi-based high critical current density superconducting tapes

    International Nuclear Information System (INIS)

    Swaminathan, G.

    1995-01-01

    In order to achieve the aim of developing suitable superconducting materials the main emphasis has to be made in the following areas viz., synthesizing powders, detailed study of sintering and phase conversion process in relation to the critical current density (J c ) on pellets and optimising of tape processing parameters. The bismuth system has been found to be more favourable for making wires and tapes because of its high transition temperature, good stability, does not require oxygen on cooling and is non-toxic. These have been the most convenient properties which made the BiSCO material the most popular one

  14. High-pressure studies of superconductivity in BiO0. 75F0. 25BiS2

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 40; Issue 6. High-pressure studies of superconductivity in BiO 0.75 F 0.25 BiS 2. ZEBA HAQUE GOHIL S THAKUR GANESAN KALAI SELVAN SONACHALAM ARUMUGAM L C GUPTA A K GANGULI. Volume 40 Issue 6 October 2017 pp 1121-1125 ...

  15. Superconductivity induced by oxygen doping in Y{sub 2}O{sub 2}Bi

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Xiyue; Deng, Shuiquan [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences (CAS), Fuzhou (China); Gordon, Elijah E. [Department of Chemistry, North Carolina State University, Raleigh, NC (United States); Whangbo, Myung-Hwan [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences (CAS), Fuzhou (China); Department of Chemistry, North Carolina State University, Raleigh, NC (United States)

    2017-08-14

    When doped with oxygen, the layered Y{sub 2}O{sub 2}Bi phase becomes a superconductor. This finding raises questions about the sites for doped oxygen, the mechanism of superconductivity, and practical guidelines for discovering new superconductors. We probed these questions in terms of first-principles calculations for undoped and O-doped Y{sub 2}O{sub 2}Bi. The preferred sites for doped O atoms are the centers of Bi{sub 4} squares in the Bi square net. Several Bi 6p x/y bands of Y{sub 2}O{sub 2}Bi are raised in energy by oxygen doping because the 2p x/y orbitals of the doped oxygen make antibonding possible with the 6p x/y orbitals of surrounding Bi atoms. Consequently, the condition necessary for the ''flat/steep'' band model for superconductivity is satisfied in O-doped Y{sub 2}O{sub 2}Bi. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Enhancement of critical currents in bulk and Ag-sheathed Bi(Pb)-2223 superconductors

    International Nuclear Information System (INIS)

    Brauer, D.J.; Eujen, R.; Hudepohl, J.

    1991-01-01

    This paper reports on the superconducting properties of the Bi(Pb)-2223 phase that have been optimized. Prolonged annealing of coarse powder raised j c in bulk samples to as high as 1100 Acm -2 at 77 K. the temperature dependence was studied between 96 and 4.2 K whereby j c rose gradually from 120 to 2100 Acm -2 . T c dropped from 107 K to 64 K in magnetic fields up to 4 T but decreased by only 1 K/T in higher fields. A tape prepared by rolling and subsequent annealing of Ag tubes containing Bi(Pb)-2223 powder exhibited a j c of 1700 Acm -2 at 77 K and 11000 Acm -2 at 4.2 K. The latter j c dropped to 3000 Acm -2 in a magnetic field of 0.25 t, but it was still 1200 Acm -2 in a 10 T field. A tape fabricated by pressing a drawn and annealed wire proved to be less sensitive to low magnetic fields

  17. Visible-light photocatalytic activity of Ag2O coated Bi2WO6 hierarchical microspheres assembled by nanosheets

    International Nuclear Information System (INIS)

    Chen, Lin; Hua, Hao; Yang, Qi; Hu, Chenguo

    2015-01-01

    Graphical abstract: - Highlights: • Bi 2 WO 6 hierarchical microspheres assembled by nanosheets and dispersed nanosheets are synthesized. • Ag 2 O/Bi 2 WO 6 heterostuctures exhibites an enhanced photocatalytic activity compared with the Bi 2 WO 6 nanostructures. • Photocatalytic activity of the Ag 2 O/Bi 2 WO 6 microspheres is higher than that of the nanosheets. • Bi 2 WO 6 hierarchical structure is an excellent architecture for loading of Ag 2 O nanoparticles. - Abstract: Bi 2 WO 6 hierarchical microspheres assembled by nanosheets and dispersed nanosheets were synthesized by hydrothermal reaction in different conditions. Ag 2 O nanoparticles were deposited on the surface of Bi 2 WO 6 microspheres and nanosheets by the chemical precipitation method. The photocatalytic performance of pure Bi 2 WO 6 nanostructures and Ag 2 O/Bi 2 WO 6 heterostructures were evaluated by the photocatalytic decolorization of RhB solution under visible-light irradiation. Compared with the pure Bi 2 WO 6 nanostructures, the Ag 2 O/Bi 2 WO 6 heterostructures exhibited an obviously enhanced photocatalytic activity. And photocatalytic activity of the Ag 2 O/Bi 2 WO 6 microspheres is higher than that of the Ag 2 O/Bi 2 WO 6 nanosheets. This work demonstrates that the Bi 2 WO 6 hierarchical three-dimensional structure is an excellent architecture for the loading of Ag 2 O nanoparticles to build a highly efficient photocatalyst

  18. Phase chemistry and microstructure evolution in silver-clad (Bi2-xPbx)Sr2Ca2Cu3Oy filaments

    International Nuclear Information System (INIS)

    Luo, J.S.; Merchant, N.; Maroni, V.A.; Escorcia-Aparicio, E.; Gruen, D.M.; Tani, B.S.; Riley, G.N. Jr.; Carter, W.L.

    1992-08-01

    The reaction kinetics and mechanism that control the conversion of (Bi,Pb) 2 Sr 2 CaCu 2 O z (Bi-2212) + alkaline earth cuporates to (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O y (Bi-2223) in silver-clad wires were investigated as a function of equilibration temperature and time at a fixed oxygen partial pressure (7.5% O 2 ). Measured values for the fractional conversion of Bi-2223 versus time have been evaluated based on the Avrami equation. SEM and TEM studies of partially and fully converted wires have revealed that (1) the growth of Bi-2223 is two-dimensional and controlled by a diffusion process, (2) liquid phases are present during part of the Bi-2212 -> Bi-2212 conversion, and (3) segregation of the second phases occurs in early time domains of the reaction

  19. Enhanced photocatalytic performance of BiVO{sub 4} in aqueous AgNO{sub 3} solution under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chien-Kai [Department of Chemistry, National Changhua University of Education, Changhua City, Taiwan (China); Wu, Tsunghsueh [Department of Chemistry, University of Wisconsin-Platteville, Platteville (United States); Huang, Chang-Wei [Department of Chemistry, National Changhua University of Education, Changhua City, Taiwan (China); Lai, Chi-Yung [Department of Biology, National Changhua University of Education, Changhua, Taiwan (China); Wu, Mei-Yao, E-mail: meiyaowu0919@gmail.com [Research Centre for Traditional Chinese Medicine, Department of Medical Research, China Medical University Hospital, Taichung City, Taiwan (China); Lin, Yang-Wei, E-mail: linywjerry@cc.ncue.edu.tw [Department of Chemistry, National Changhua University of Education, Changhua City, Taiwan (China)

    2017-03-31

    Graphical abstract: Ag{sup +} ions enhanced photocatalytic activity of BiVO{sub 4} under visible light irradiation. - Highlights: • The presence of Ag{sup +} ions enhanced the photodegradation activity of BiVO{sub 4}. • Photoreduction of Ag deposited on the BiVO{sub 4} surface was obtained. • Luminescence and electrochemical results elucidated the photocatalytic mechanism. • Holes and oxygen radicals were the main reactive species generated by BiVO{sub 4}/Ag{sup +}. • Used BiVO{sub 4}/Ag{sup +} exhibited photocatalytic antibacterial activity toward E. coli. - Abstract: Monoclinic-phase bismuth vanadate (BiVO{sub 4}) with a 2.468 eV band gap exhibited enhanced synergic photodegradation activity toward methylene blue (MB) when combined with silver ions (Ag{sup +}) in an aqueous solution under visible light irradiation. The mass ratio of AgNO{sub 3} to BiVO{sub 4} and the calcination temperature were discovered to considerably affect the degradation activity of BiVO{sub 4}/Ag{sup +}. Superior photocatalytic performance was obtained when BiVO{sub 4} was mixed with 0.01%(w/v) AgNO{sub 3} solution, and complete degradation of MB was achieved after 25 min visible light irradiation, outperforming BiVO{sub 4} or AgNO{sub 3} solution alone. The enhanced photodegradation was investigated using systematic luminescence measurements, electrochemical impedance spectroscopy, and scavenger addition, after which a photocatalytic mechanism for MB degradation under visible light irradiation was identified that involved oxygen radicals and holes. This study also discovered the two dominating processes involved in enhancing the electron–hole separation efficiency and reducing their recombination rate, namely photoreduction of Ag{sup +} and the formation of a BiVO{sub 4}/Ag heterojunction. The synergic effect between BiVO{sub 4} and Ag{sup +} was discovered to be unique. BiVO{sub 4}/Ag{sup +} was successfully used to degrade two other dyes and disinfect Escherichia Coli. A

  20. Suppression of superconductivity in a single Pb layer on Ag/Si(111)

    Energy Technology Data Exchange (ETDEWEB)

    Leon-Vanegas, Augusto; Kirschner, Juergen [Max Plank Instituet fuer Mikrostukturphysik (Germany); Martin Luther Univeristaet, Halle-Wittenberg (Germany); Caminale, Michael; Stepniak, Agnieszka; Oka, Hirofumi; Sanna, Antonio; Linscheid, Andreas; Sander, Dirk [Max Plank Instituet fuer Mikrostukturphysik (Germany)

    2015-07-01

    Recently, superconductivity was reported in a single layer of Pb on Si(111) with a critical temperature of 1.83 K. It has been proposed that the interaction of Pb with the Si substrate provides the electron phonon coupling to support superconductivity in this system. We have used a {sup 3}He-cooled STM with a vector magnetic field to study the effect of insertion of a Ag interlayer on the superconducting properties of a single Pb layer on Si(111). In contrast to the experiments on Pb/Si(111), the differential conductance of Pb/Ag/Si(111) does not show a gap indicative of superconductivity even at the lowest experimental temperature of 0.38 K. We ascribe this to the suppression of superconductivity. This result is explained by means of ab-initio calculations, showing that the effect of a chemical hybridization between Pb and Ag/Si occurring at the Fermi level dramatically reduces the strength of the electron phonon coupling. This contrasts with the case of Pb/Si(111), where no overlap between Pb and Si electronic states at the Fermi level is found in the calculations.

  1. Doping dependence of low-energy quasiparticle excitations in superconducting Bi2212.

    Science.gov (United States)

    Ino, Akihiro; Anzai, Hiroaki; Arita, Masashi; Namatame, Hirofumi; Taniguchi, Masaki; Ishikado, Motoyuki; Fujita, Kazuhiro; Ishida, Shigeyuki; Uchida, Shinichi

    2013-12-05

    : The doping-dependent evolution of the d-wave superconducting state is studied from the perspective of the angle-resolved photoemission spectra of a high-Tc cuprate, Bi2Sr2CaCu2 O8+δ (Bi2212). The anisotropic evolution of the energy gap for Bogoliubov quasiparticles is parametrized by critical temperature and superfluid density. The renormalization of nodal quasiparticles is evaluated in terms of mass enhancement spectra. These quantities shed light on the strong coupling nature of electron pairing and the impact of forward elastic or inelastic scatterings. We suggest that the quasiparticle excitations in the superconducting cuprates are profoundly affected by doping-dependent screening.

  2. AC loss in superconducting wires operating in a wind turbine like generator

    DEFF Research Database (Denmark)

    Seiler, Eugen; Zirngibl, Thomas; Mijatovic, Nenad

    2010-01-01

    We have manufactured a small circular superconducting coil impregnated with epoxy fibreglass. The coil was wound from a Bi-2223/Ag superconducting wire and it was tested in liquid nitrogen at 77 K. Current-voltage characteristic and the AC losses of the coil were measured and compared...

  3. AGS superconducting bending magnets

    International Nuclear Information System (INIS)

    Robins, K.E.; Sampson, W.B.; McInturff, A.D.; Dahl, P.F.; Abbatiello, F.; Aggus, J.; Bamberger, J.; Brown, D.; Damm, R.; Kassner, D.; Lasky, C.; Schlafke, A.

    1976-01-01

    Four large aperture superconducting bending magnets are being built for use in the experimental beams at the AGS. Each of these magnets is 2.5 m long and has a room temperature aperture of 20 cm. The magnets are similar in design to the dipoles being developed for ISABELLE and employ a low temperature iron core. Results are presented on the ''training'' behavior of the magnets and a comparison will be made with the smaller aperture versions of this design. The magnet field measurements include end fields and leakage fields as well as the harmonic components of the straight section of the magnet

  4. Effect of epoxy impregnation on strain distribution of materials in Bi2223 superconducting coils by using synchrotron X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Xinzhe, E-mail: xinzhe.jin@riken.jp [Center for Life Science Technologies, RIKEN, Yokohama-shi, Kanagawa 230-0045 (Japan); Osamura, Kozo [Research Institute for Applied Sciences, Sakyo-ku, Kyoto 606-8202 (Japan); Machiya, Shutaro [Daido University, Minami-ku, Nagoya 457-8530 (Japan); Kajiwara, Kentaro [Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198 (Japan); Shobu, Takahisa [Japan Atomic Energy Agency, Sayo, Hyogo 679-5148 (Japan); Maeda, Hideaki [Center for Life Science Technologies, RIKEN, Yokohama-shi, Kanagawa 230-0045 (Japan)

    2015-11-25

    Synchrotron X-rays have been used to observe strain distributions in composite materials such as superconducting wires with a thickness of less than about 2 mm. In applications that employ wound coils of superconducting wire, it is necessary to understand the strain distribution within the coiled wire. Superconducting wires such as Bi2223 and REBCO wires approximately 4–5 mm wide are commercially available. Coiled wires of this width are too thick to easily measure using conventional X-ray techniques, especially the inner strain, because the penetration depth tends to be around 2 mm. Therefore, the beam penetration must be improved, and it is known that the penetration depth of an X-ray beam depends upon the beam energy, beam intensity, measurement material, and measurement method. In this study, we used a white X-ray diffractometer at SPring-8 to develop a method of observing the strain distribution in Bi2223 superconducting coils winded by a 4.5 mm wide Bi2223 wire. We successfully observed a clear (400) peak of the Bi2223 phase by an appropriate measurement condition, and then observed the strains of each material in the Bi2223 coils with and without epoxy impregnation. This is the first time that we have obtained the strain of a Bi2223 phase in coiled wire using synchrotron X-ray diffraction. Further synchrotron-based study of superconducting coils will be useful in the development of advanced high-field magnets. The appropriate measurement method and the obtained measurement results are presented in this paper. - Highlights: • We successfully obtained clear peaks of Bi2223 phase in 4.5 mm thick coils. • The strain behaviors of materials in the coil correspond to a three turn cycle model. • A uniform strain distribution of the Bi2223 phase was obtained by epoxy impregnation.

  5. Topotactic synthesis of a new BiS2-based superconductor Bi2(O,F)S2

    OpenAIRE

    Okada, Tomoyuki; Ogino, Hiraku; Shimoyama, Jun-ichi; Kishio, Kohji

    2015-01-01

    A new BiS2-based superconductor Bi2(O,F)S2 was discovered. This is a layered compound consisting of alternate stacking structure of rock-salt-type BiS2 superconducting layer and fluorite-type Bi(O,F) blocking layer. Bi2(O,F)S2 was obtained as the main phase by topotactic fluorination of undoped Bi2OS2 using XeF2, which is the first topotactic synthesis of an electron-doped superconductor via reductive fluorination. With increasing F-content, a- and c-axis length increased and decreased, respe...

  6. Processing Y- and Bi-based superconductors

    International Nuclear Information System (INIS)

    Balachandran, U.; Dos Santos, D.I.; von Stumberg, A.W.; Graham, S.W.; Singh, J.P.; Youngdahl, C.A.; Goretta, K.C.; Shi, D.; Poeppel, R.B.

    1989-01-01

    This paper reports on bulk specimens of YBa 2 Cu 3 O x and Bi 2 Sr 2 CaCu 2 O y formed and then processed by sintering in the solid state, in the presence of a liquid phase, or by sinter forging. Both Y- and Bi-based superconductors are difficult to densify by solid-state sintering but easy to densify in the presence of a liquid phase. Effects of sintering conditions on superconducting properties are, however, different between the two materials. These differences will be discussed. Attempts to texture microstructures and increase J c by sinter-forging techniques have been successful for Y-based superconductors, but unsuccessful for Bi-based superconductors

  7. Method of producing superconducting fibers of bismuth strontium calcium copper oxide (Bi(2212) and Bi(2223))

    Science.gov (United States)

    Schwartzkopf, Louis A.

    1991-10-01

    Fibers of Bi(2212) have been produce by pendant drop melt extraction. This technique involves the end of a rod of Bi(2212) melted with a hydrogen-oxygen torch, followed by lowering onto the edge of a spinning wheel. The fibers are up to 15 cm in length with the usual lateral dimensions, ranging from 20 um to 30 um. The fibers require a heat treatment to make them superconducting.

  8. Tuning the electronic and the crystalline structure of LaBi by pressure: From extreme magnetoresistance to superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Tafti, F. F.; Torikachvili, M. S.; Stillwell, R. L.; Baer, B.; Stavrou, E.; Weir, S. T.; Vohra, Y. K.; Yang, H. -Y.; McDonnell, E. F.; Kushwaha, S. K.; Gibson, Q. D.; Cava, R. J.; Jeffries, J. R.

    2017-01-01

    Extreme magnetoresistance (XMR) in topological semimetals is a recent discovery which attracts attention due to its robust appearance in a growing number of materials. To search for a relation between XMR and superconductivity, we study the effect of pressure on LaBi. By increasing pressure, we observe the disappearance of XMR followed by the appearance of superconductivity at P ≈ 3.5 GPa. We find a region of coexistence between superconductivity and XMR in LaBi in contrast to other superconducting XMR materials. The suppression of XMR is correlated with increasing zero-field resistance instead of decreasing in-field resistance. At higher pressures, P ≈ 11 GPa, we find a structural transition from the face-centered cubic lattice to a primitive tetragonal lattice, in agreement with theoretical predictions. The relationship between extreme magnetoresistance, superconductivity, and structural transition in LaBi is discussed.

  9. Macroscopic Quantum Tunneling in Superconducting Junctions of β-Ag2Se Topological Insulator Nanowire.

    Science.gov (United States)

    Kim, Jihwan; Kim, Bum-Kyu; Kim, Hong-Seok; Hwang, Ahreum; Kim, Bongsoo; Doh, Yong-Joo

    2017-11-08

    We report on the fabrication and electrical transport properties of superconducting junctions made of β-Ag 2 Se topological insulator (TI) nanowires in contact with Al superconducting electrodes. The temperature dependence of the critical current indicates that the superconducting junction belongs to a short and diffusive junction regime. As a characteristic feature of the narrow junction, the critical current decreases monotonously with increasing magnetic field. The stochastic distribution of the switching current exhibits the macroscopic quantum tunneling behavior, which is robust up to T = 0.8 K. Our observations indicate that the TI nanowire-based Josephson junctions can be a promising building block for the development of nanohybrid superconducting quantum bits.

  10. Low coupling loss core-strengthened Bi 2212\\/Ag Rutherford cables

    CERN Document Server

    Collings, E W; Scanlan, R M; Dietderich, D R; Motowidlo, L R

    1999-01-01

    In a comprehensive "vertically integrated" program multifilamentary (MF) high temperature superconducting (HTSC) Bi:2212/Ag strand was fabricated using the powder-in-tube process and heat treated in oxygen by a modified standard $9 procedure. The reaction-heat-treatment (HT) was adjusted to maximize critical current (density), I/sub c/ (J /sub c/), as measured in various magnetic fields, B. A series of Rutherford cables was designed, each of which included a $9 metallic (Nichrome-80) core for strengthening and reduction of coupling loss. Prior to cable winding a series of tests examined the possibility of strand "poisoning" by the core during HT. Small model Rutherford cables were wound, $9 and after HT were prepared for I/sub c/(B) measurement and calorimetric measurement of AC loss and hence interstrand contact resistance I/sub c/(B). It was deduced that, if in direct contact with the strand during HT, the core $9 material can degrade the I/sub c/ of the cable; but steps can be taken to eliminate this probl...

  11. Engineering Critical Current Density Improvement in Ag- Bi-2223 Tapes

    DEFF Research Database (Denmark)

    Wang, W. G.; Seifi, Behrouz; Eriksen, Morten

    2000-01-01

    Ag alloy sheathed Bi-2223 multifilament tapes were produced by the powder-in-tube method. Engineering critical current density improvement has been achieved through both enhancement of critical current density by control of the thermal behavior of oxide powder and by an increase of the filling...... factor of the tapes. Phase evolution at initial sintering stage has been studied by a quench experiment in Ag-Bi-2223 tapes. The content, texture, and microstructure of various phases were determined by XRD and SEM. A novel process approach has been invented in which square wire was chosen rather than...

  12. Visible-light-induced Ag/BiVO4 semiconductor with enhanced photocatalytic and antibacterial performance

    Science.gov (United States)

    Regmi, Chhabilal; Dhakal, Dipesh; Wohn Lee, Soo

    2018-02-01

    An Ag-loaded BiVO4 visible-light-driven photocatalyst was synthesized by the microwave hydrothermal method followed by photodeposition. The photocatalytic performance of the synthesized samples was evaluated on a mixed dye (methylene blue and rhodamine B), as well as bisphenol A in aqueous solution. Similarly, the disinfection activities of synthesized samples towards the Gram-negative Escherichia coli (E. coli) in a model cell were investigated under irradiation with visible light (λ ≥ 420 nm). The synthesized samples have monoclinic scheelite structure. Photocatalytic results showed that all Ag-loaded BiVO4 samples exhibited greater degradation and a higher mineralization rate than the pure BiVO4, probably due to the presence of surface plasmon absorption that arises due to the loading of Ag on the BiVO4 surface. The optimum Ag loading of 5 wt% has the highest photocatalytic performance and greatest stability with pseudo-first-order rate constants of 0.031 min-1 and 0.023 min-1 for the degradation of methylene blue and rhodamine B respectively in a mixture with an equal volume and concentration of each dye. The photocatalytic degradation of bisphenol A reaches 76.2% with 5 wt% Ag-doped BiVO4 within 180 min irradiation time. Similarly, the Ag-loaded BiVO4 could completely inactivate E. coli cells within 30 min under visible light irradiation. The disruption of the cell membrane as well as degradation of protein and DNA exhibited constituted evidence for antibacterial activity towards E. coli. Moreover, the bactericidal mechanisms involved in the photocatalytic disinfection process were systematically investigated.

  13. AgBr/MgBi2O6 heterostructured composites with highly efficient visible-light-driven photocatalytic activity

    Science.gov (United States)

    Zhong, Liansheng; Hu, Chaohao; Zhuang, Jing; Zhong, Yan; Wang, Dianhui; Zhou, Huaiying

    2018-06-01

    AgBr/MgBi2O6 heterostructured photocatalysts were synthesized by the deposition-precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS) were employed to examine the phase structure, morphology and optical properties of the as-prepared samples. The photocatalytic activity was investigated by decomposing methylene blue (MB) solution under visible light irradiation (λ > 420 nm). AgBr/MgBi2O6 composites exhibited significantly enhanced visible-light-driven photocatalytic properties in comparison with pure MgBi2O6 and AgBr. When the molar ratio of AgBr to MgBi2O6 was 3:1, the composite catalyst showed the optimal photocatalytic activity and excellent stability. The enhanced photocatalytic activity of AgBr/MgBi2O6 composites was attributed to the formation of p-n heterojunction between AgBr and MgBi2O6, thereby resulting in the effective separation and transfer of photogenerated electrons-hole pairs.

  14. Synthesis of flower-like Ag{sub 2}O/BiOCOOH p-n heterojunction with enhanced visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shijie [Innovation & Application Institute, Zhejiang Ocean University, Zhoushan, Zhejiang Province 316022 (China); Zhejiang Provincial Key Laboratory of Health Risk Factors for Seafood, Zhoushan Municipal Center for Disease Control and Prevention, Zhoushan 316021 (China); State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Xu, Kaibing [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Research Center for Analysis and Measurement, Donghua University, Shanghai 201620 (China); Hu, Shiwei, E-mail: hushiweihai@163.com [Innovation & Application Institute, Zhejiang Ocean University, Zhoushan, Zhejiang Province 316022 (China); Jiang, Wei [Innovation & Application Institute, Zhejiang Ocean University, Zhoushan, Zhejiang Province 316022 (China); Zhejiang Provincial Key Laboratory of Health Risk Factors for Seafood, Zhoushan Municipal Center for Disease Control and Prevention, Zhoushan 316021 (China); Zhang, Junlei [Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433 (China); Liu, Jianshe [State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Zhang, Lisha, E-mail: lszhang@dhu.edu.cn [State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China)

    2017-03-01

    Highlights: • Ag{sub 2}O/BiOCOOH p-n heterojunctions are prepared by a solvothermal deposition-precipitation method. • They consist of flower-like BiOCOOH microspheres decorated with Ag{sub 2}O nanoparticles. • Heterojunction with the Ag/Bi molar ratio of 0.2/1 showed the highest photocatalytic activity. • The photogenerated holes (h{sup +}) and superoxide radical anions (·O{sub 2}{sup −}) have been found to be the main reactive species. - Abstract: The development of efficient semiconductor heterojunction photocatalysts has drawn much attention. Herein, we have reported a kind of flower-like Ag{sub 2}O/BiOCOOH p-n heterojunction as a novel and efficient visible-light-driven photocatalyst. The Ag{sub 2}O/BiOCOOH heterojunctions have been successfully prepared via a solvothermal precipitation-deposition method. They consist of flower-like BiOCOOH microspheres (diameters: 1–2.5 μm) decorated with Ag{sub 2}O nanoparticles (size: ∼14 nm). In addition, optical characterization reveals that they have broad visible-light photo-absorption. Importantly, under visible-light irradiation (λ > 400 nm), all Ag{sub 2}O/BiOCOOH heterojunctions exhibit enhanced photocatalytic activity than pure BiOCOOH or Ag{sub 2}O for the degradation of rhodamine B (RhB) dye and para-chlorophenol (4-CP). Especially, the Ag{sub 2}O/BiOCOOH heterojunction with the Ag/Bi molar ratio of 0.2/1 shows the highest photocatalytic activity, which is even higher than the activity from the mechanical mixture (8 wt% Ag{sub 2}O + 92 wt% BiOCOOH). This enhanced photocatalytic performance could be predominantly attributed to the efficient separation of photogenerated electron-hole pairs. The photogenerated holes (h{sup +}) and superoxide radical anions (·O{sub 2}{sup −}) have been found to be the main reactive species responsible for the photodegradation of RhB dye in aqueous solution. Therefore, the Ag{sub 2}O/BiOCOOH p-n heterojunction has great potential to be used as a kind of efficient

  15. Topotactic synthesis of a new BiS2-based superconductor Bi2(O,F)S2

    Science.gov (United States)

    Okada, Tomoyuki; Ogino, Hiraku; Shimoyama, Jun-ichi; Kishio, Kohji

    2015-02-01

    A new BiS2-based superconductor, Bi2(O,F)S2, was discovered. It is a layered compound consisting of alternately stacked structure of rock-salt-type BiS2 superconducting layers and fluorite-type Bi(O,F) blocking layers. Bi2(O,F)S2 was obtained as the main phase by topotactic fluorination of undoped Bi2OS2 using XeF2. This is the first topotactic synthesis of an electron-doped superconductor via reductive fluorination. With increasing F-content, a- and c-axis lengths increased and decreased, respectively, and Tc increased to 5.1 K.

  16. Electrodeposited Ag-Stabilization Layer for High Temperature Superconducting Coated Conductors: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, R. N.; Mann, J.; Qiao, Y.; Zhang, Y.; Selvamanickam, V.

    2010-11-01

    We developed a non-aqueous based electrodepostion process of Ag-stabilization layer on YBCO superconductor tapes. The non-aqueous electroplating solution is non-reactive to the HTS layer thus does not detoriate the critical current capability of the superconductor layer when plated directly on the HTS tape. The superconducting current capabilities of these tapes were measured by non-contact magnetic measurements.

  17. Photocatalytic Degradation of Methyl Orange on Bi2O3 and Ag2O-Bi2O3 Nano Photocatalysts

    Directory of Open Access Journals (Sweden)

    Seyed Ali Hosseini

    2017-04-01

    Full Text Available The photocatalytic activity of Bi2O3 and Ag2O-Bi2O3 was evaluated by degradation of aqueous methyl orange as a model dye effluent. Bi2O3 was synthesized using chemical precipitation method. Structural analysis revealed that Bi2O3 contain a unique well-crystallized phase and the average crystallite size of 22.4 nm. The SEM analysis showed that the size of Bi2O3 particles was mainly in the range of 16-22 nm. The most important variables affecting the photocatalytic degradation of dyes, namely reaction time, initial pH and catalyst dosage were studied, and their optimal amounts were found at 60 min, 5.58 and 0.025 g, respectively. A good correlation was found between experimental and predicted responses, confirming the reliability of the model. Incorporation of Ag2O in the structure of composite caused decreasing band gap and its response to visible light. Because a high percentage of sunlight is visible light, hence Ag2O-Bi2O3 nano-composite could be used as an efficient visible light driven photocatalyst for degradation of dye effluents by sunlight. Copyright © 2017 BCREC GROUP. All rights reserved Received: 15th August 2016; Revised: 20th December 2016; Accepted: 21st December 2016 How to Cite: Hosseini, S.A., Saeedi, R. (2017. Photocatalytic Degradation of Methyl Orange on Bi2O3 and Ag2O-Bi2O3 Nano Photocatalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (1: 96-105 (doi:10.9767/bcrec.12.1.623.96-105 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.1.623.96-105

  18. Enhanced photoelectrochemical and photocatalytic activity in visible-light-driven Ag/BiVO_4 inverse opals

    International Nuclear Information System (INIS)

    Fang, Liang; Nan, Feng; Yang, Ying; Cao, Dawei

    2016-01-01

    BiVO_4 photonic crystal inverse opals (io-BiVO_4) with highly dispersed Ag nanoparticles (NPs) were prepared by the nanosphere lithography method combining the pulsed current deposition method. The incorporation of the Ag NPs can significantly improve the photoelectrochemical and photocatalytic activity of BiVO_4 inverse opals in the visible light region. The photocurrent density of the Ag/io-BiVO_4 sample is 4.7 times higher than that of the disordered sample without the Ag NPs, while the enhancement factor of the corresponding kinetic constant in photocatalytic experiment is approximately 3. The improved photoelectrochemical and photocatalytic activity is benefited from two reasons: one is the enhanced light harvesting owing to the coupling between the slow light and localized surface plasmon resonance effect; the other is the efficient separation of charge carriers due to the Schottky barriers.

  19. Effect of lead addition on the formation of superconducting phases in Bi-Sr-Ca-Cu-O ceramics

    International Nuclear Information System (INIS)

    Martinelli, A.E.

    1991-01-01

    Superconducting ceramics with starting composition Bi 2 - x Pb x Sr 2 Ca 2 Cu 3 O y (0,0 ≤ X ≤ 0,6) were prepared in order to investigate the effects of partial substitution of Pb for Bi and sintering time and atmosphere in the formation of superconducting phases. For all samples X-ray diffraction analyses were performed to estimate the amount of superconducting phases; superconductivity was analysed by dc electrical resistance and ac magnetic susceptibility measurements. The main results show that: a) the longer the sintering time (up to 168 h), the larger the volume fraction of superconducting phases with critical temperature (T c ) greater than the temperature of nitrogen liquefaction; b) by partially substituting Pb for Bi it is possible to restrain the formation of 2212 phase (T c = 80 K) and to enhance the amount of 2223 phase (T c = 105 K); C) a heat treatment under oxygen atmosphere before sintering enhances the formation of 2223 phase. (author)

  20. In situ controllable synthesis of novel surface plasmon resonance-enhanced Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} composite for enhanced and stable visible light photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Jiali [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Dai, Kai, E-mail: daikai940@chnu.edu.cn [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Zhang, Jinfeng [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Lu, Luhua, E-mail: lhlu@cug.edu.cn [Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Liang, Changhao, E-mail: chliang@issp.ac.cn [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 23003 (China); Geng, Lei; Wang, Zhongliao; Yuan, Guangyu; Zhu, Guangping [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China)

    2017-01-01

    Highlights: • Novel Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} ternary photocatalyst was prepared. • Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} showed enhanced catalytic activity. • Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} showed long reusable life. - Abstract: A novel hierarchical Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} ternary visible-light-driven photocatalyst was successfully synthesized by in situ doping Ag{sub 2}WO{sub 4} with Bi{sub 2}MoO{sub 6} nanosheets through a facile hydrothermal and photochemical process. The morphology, structure, optical performance and crystallinity of the products were measured by field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS), UV–vis diffuse reflectance spectroscopy (DRS) and X-ray diffraction (XRD). The results showed that Ag{sub 2}WO{sub 4}/Ag was uniformly dispersed on the surface of Bi{sub 2}MoO{sub 6} nanosheets. The photocatalytic performance of Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} heterostructures was evaluated by the degradation of methylene blue (MB) under 410 nm LED arrays. The ternary Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} nanocomposite exhibits higher photocatalytic activity than Bi{sub 2}MoO{sub 6} and Ag{sub 2}WO{sub 4}. The synergistic effect of Ag{sub 2}WO{sub 4} and Bi{sub 2}MoO{sub 6} could generated more heterojunctions which promoted photoelectrons transfer from Ag{sub 2}WO{sub 4} to Bi{sub 2}MoO{sub 6}, leading to the improvement of photocatalytic performance by photoelectrons-holes recombination suppression. At the same time, the surface plasmon resonance of Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} is another crucial reason for the high photocatalytic performance of organic pollutants degradation. And the 20 wt% Ag{sub 2}WO{sub 4}-loaded Bi{sub 2}MoO{sub 6} shows the optimal photocatalytic performance in the degradation of MB. In addition, the ternary composites can be easily reclaimed by precipitation and exhibits high stability of photocatalytic

  1. Weak antilocalization effect and noncentrosymmetric superconductivity in a topologically nontrivial semimetal LuPdBi

    KAUST Repository

    Xu, Guizhou; Wang, Wenhong; Zhang, Xiaoming; Du, Yin; Liu, Enke; Wang, Shouguo; Wu, Guangheng; Liu, Zhongyuan; Zhang, Xixiang

    2014-01-01

    A large number of half-Heusler compounds have been recently proposed as three-dimensional (3D) topological insulators (TIs) with tunable physical properties. However, no transport measurements associated with the topological surface states have been observed in these half-Heusler candidates due to the dominating contribution from bulk electrical conductance. Here we show that, by reducing the mobility of bulk carriers, a two-dimensional (2D) weak antilocalization (WAL) effect, one of the hallmarks of topological surface states, was experimentally revealed from the tilted magnetic field dependence of magnetoconductance in a topologically nontrivial semimetal LuPdBi. Besides the observation of a 2D WAL effect, a superconducting transition was revealed at T c ∼ 1.7â.K in the same bulk LuPdBi. Quantitative analysis within the framework of a generalized BCS theory leads to the conclusion that the noncentrosymmetric superconductivity of LuPdBi is fully gapped with a possibly unconventional pairing character. The co-existence of superconductivity and the transport signature of topological surface states in the same bulk alloy suggests that LuPdBi represents a very promising candidate as a topological superconductor.

  2. Weak antilocalization effect and noncentrosymmetric superconductivity in a topologically nontrivial semimetal LuPdBi

    KAUST Repository

    Xu, Guizhou

    2014-07-21

    A large number of half-Heusler compounds have been recently proposed as three-dimensional (3D) topological insulators (TIs) with tunable physical properties. However, no transport measurements associated with the topological surface states have been observed in these half-Heusler candidates due to the dominating contribution from bulk electrical conductance. Here we show that, by reducing the mobility of bulk carriers, a two-dimensional (2D) weak antilocalization (WAL) effect, one of the hallmarks of topological surface states, was experimentally revealed from the tilted magnetic field dependence of magnetoconductance in a topologically nontrivial semimetal LuPdBi. Besides the observation of a 2D WAL effect, a superconducting transition was revealed at T c ∼ 1.7â.K in the same bulk LuPdBi. Quantitative analysis within the framework of a generalized BCS theory leads to the conclusion that the noncentrosymmetric superconductivity of LuPdBi is fully gapped with a possibly unconventional pairing character. The co-existence of superconductivity and the transport signature of topological surface states in the same bulk alloy suggests that LuPdBi represents a very promising candidate as a topological superconductor.

  3. Preparation of Bi-Pb-Sr-Ca-Cu-O high Tc thick films on Ag or MgO substrate with superconductor paste; Bi kei ko Tc chodendo paste ni yoru Ag, MgO kibanjo eno atsumaku sakusei

    Energy Technology Data Exchange (ETDEWEB)

    Takabatake, N. [Ishikawa Technical High School, Ishikawa (Japan); Tsubota, T.; Ishikawa, T.; Ohashi, K. [Kanazawa Institute of Technology, Ishikawa (Japan)

    1995-07-15

    The following were reported on making Bi series superconducting thick films by a wet method. A paste was made by adding PSO (or ethanol solution of ethylenegrycol) of Yushiro Chemical Industry Co., Ltd. as a binder to a Bi series 2223 single-phase powder sample (blending composition Bi:Pb:Sr:Ca:Cu=1.8:0.4:2:2:3.2); the sample was then coated on an Ag (or MgO) substrate with a brush; after being dried at 105{degree}C for one hour, it was thermally decomposed at 700{degree}C for one hour; then, the process of prissurized forming (at pressure 2 to 5 ton f/cm{sup 2}) and of sintering at 845{degree}C for 20 hours or more were performed on the sample to form a thick film sample. A critical temperature Tc, critical current density Jc, etc., were measured on such thick film sample. As a result, nearly same values were obtained as Tc (93K) and Jc (84A/cm{sup 2}) which were those of a bulk sample made by using the same powder sample, pressurizing at 2 ton f/cm{sup 2} for pelletizing, and sintering at 845{degree}C for 20 hours. 6 refs., 7 figs., 1 tab.

  4. Growth and superconducting properties of Bi2Sr2Ca2Cu3O10 single crystals

    International Nuclear Information System (INIS)

    Clayton, N; Musolino, N; Giannini, E; Garnier, V; Fluekiger, R

    2004-01-01

    Single crystals of Bi 2 Sr 2 Ca 2 Cu 3 O 10 (Bi-2223) have been grown using the travelling solvent floating zone technique in an image furnace. Annealing the crystals under high pressures of O 2 increased their critical temperature to 109 K, and resulted in sharp superconducting transitions of ΔT c = 1 K. The superconducting anisotropy of Bi-2223 was found to be ∼ 50, from measurements of the lower critical field with the magnetic field applied parallel and perpendicular to the c-axis. The anisotropy of Bi-2223 is significantly reduced compared to that of Bi 2 Sr 2 CaCu 2 O 8 (Bi-2212), and this accounts for the enhanced irreversibility fields in Bi-2223. Furthermore, Bi-2223 has a higher critical current density, and a reduced magnetic relaxation rate compared to Bi-2212, which are both signatures of more effective pinning in Bi-2223 due to its reduced anisotropy

  5. Measuring the homogeneity of Bi(2223)/Ag tapes by four-probe method and a Hall probe array

    International Nuclear Information System (INIS)

    Kovac, P.

    1999-01-01

    The nature of the BSCCO compound and application of the powder-in-tube technique usually lead to non-uniform quality across and/or along the ceramic fibres and finally to variations in the critical current and its irregular distribution in the Bi(2223)/Ag tape. Therefore, the gliding four-probe method and contactless field monitoring measurements have been used for homogeneity studies. The gliding potential contacts moved along the tape surface and a sensitive system based on an integrated Hall probe array containing 16 or 19 in-line probes supported by PC-compatible electronics with software allowed us to make a comparison of contact and contactless measurements at any elements of Bi(2223)/Ag sample. The results of both methods show very good correlation and the possibility of using a sensitive Hall probe array for monitoring the final quality of Bi(2223)/Ag tapes. (author)

  6. Mechanical properties of high-temperature superconducting wires. Ph.D. Thesis - Illinois Inst. of Tech.

    Science.gov (United States)

    Goretta, K. C.; Cluff, J. A.; Joo, J.; Lanagan, M. T.; Singh, J. P.; Vasanthamohan, N.; Xin, Y.; Wong, K. W.

    1995-01-01

    Bending strength, fracture toughness, and elastic modulus data were acquired for YBa2Cu3O(x), Bi2Sr2CaCu2O(x) (Bi,Pb)2Sr2Ca2Cu3O(x), and Tl2Ba2Ca2Cu3O(x) bars. These data and thermal expansion coefficients strongly suggest that the maximum possible tensile strain without fracture of bulk tapes or wires is approximately equals 0.2%. In Ag-clad conductors, residual stresses will be of limited benefit, but fractures produced by larger strains can be accommodated by shunting current through the Ag.

  7. Trapping control of phase development in zone melting of Bi-Sr-Ca-Cu-O superconducting fibres

    International Nuclear Information System (INIS)

    Costa, F M; Carrasco, M F; Silva, R F; Vieira, J M

    2003-01-01

    Highly-texturized polycrystalline fibres of the Bi-Sr-Ca-Cu-O system have been grown by the laser floating zone technique at seven different pulling rates: (1.1, 2.2, 4.17, 8.3, 16.7, 33.3, 60.5) x 10 -6 m s -1 . The assessment of the cation segregation at the solid/liquid interface allowed us to calculate their equilibrium and effective distribution coefficients. The equilibrium distribution coefficients (k 0,Bi = 0.55, k 0,Sr = 0.97, k 0,Ca = 1.67, k 0,Cu = 1.10) were estimated using the Burton, Primm and Slichter (BPS) theory by taking into account the determined effective values. The effective distribution coefficients tend to unity as long as the pulling rate increases. The composition profiles along the initial transient region of the solidified fibres show a fast approach to the nominal composition as the pulling rate increases. The outstanding effect of the growth speed on superconducting phase type development is explained based on the solute trapping phenomena. The sequence of crystallization for superconducting phases ('2212' → '4413' → '2201') with pulling rate is a spontaneous effect of the system thermodynamics in order to balance the Bi trapping. This phase sequence corresponds to the smallest change of Bi chemical potential from the liquid phase to the solid phase. A diagram of free energy curves of the interdendritic superconducting phases illustrates the partitionless solidification phenomena at the highest growth speed

  8. AC power losses in Bi-2223/Ag HTS tapes

    International Nuclear Information System (INIS)

    Savvides, N.; Reilly, D.; Mueller, K.-H.; Herrmann, J.

    1998-01-01

    Full text: We report measurements at 77 K of the transport ac losses of Bi-2223/Ag composite tapes. The investigated tapes vary from single filament to multifilament construction and include both conventional tapes and other conductor shapes with twisted filaments. The self-field ac losses were determined at 77 K and 60 Hz as a function of ac current amplitude (0 - 100 A). We observe different behaviour among tapes depending on their quality and strain history. For 'good' virgin tapes the experimental data are well described by the Norris equations for the dependence of power loss P on the amplitude I m of the transport current. The data of good monofilament tapes are fitted to the Norris equation P ∼ I m n for an elliptical cross section (ie. n = 3) and the data of good multifilament tapes are fitted to the Norris equation for a rectangular strip (ie. n = 4). Many specimens, however, show a range of behaviour with lower values of n. Based on our work on the effect of strain on the dc transport properties of tapes, we carried out detailed investigations of the effect of controlled applied bend strain on the ac loss. Our results show that irreversible damage to superconducting filaments (ie. cracks) cause the ac loss to rise and n to decrease with increasing strain. In addition, applied strains much greater than the irreversible strain limit cause the ac loss to increase by several orders of magnitude and become ohmic in character with n = 2. Theoretical work is in progress to model the observed behaviour

  9. Beginning point of metal to insulator transition for Bi-2223 superconducting matrix doped with Eu nanoparticles

    International Nuclear Information System (INIS)

    Yildirim, G.

    2013-01-01

    Highlights: •Standard measurements such as bulk density, ρ-T, J ct , XRD, SEM and EDX examinations for characterization of the samples. •Role of Eu inclusions on the microstructural, electrical and superconducting properties of Bi-2223 phase. •Determination of metal to insulator transition due to Eu impurities in the Bi-2223 superconducting matrix. •From the Eu content level of x = 0.5 onwards, destruction of the superconducting phases. •Constant retrogression of the microstructural and superconducting properties with the Eu individuals. -- Abstract: This comprehensive study examines the change of the microstructural, electrical and superconducting properties of the Eu doped Bi 1.8 Pb 0.4 Eu x Sr 2 Ca 2.2 Cu 3.0 O y ceramic cuprates (with x ⩽ 0.7) produced by the conventional solid state reaction method at the constant annealing temperature of 840 °C for 24 h with the aid of the standard characterization measurements such as bulk density, dc resistivity (ρ-T), transport critical current density (J c ), X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) examinations. For the full characterization of the pure and Eu doped Bi-2223 samples, the degree of granularity (from the bulk density and porosity measurements); the room temperature resistivity, onset–offset critical transition temperature, variation of transition temperature, hole carrier concentration, spin-gap opening temperature and thermodynamic fluctuations (from the dc resistivity experiments); the texturing, crystal structure, crystallite size, phase purity and cell parameters (from the XRD investigations); the variation of the flux pinning centers and the boundary weak-links between the superconducting grains (from the critical current density values); the crystallinity, specimen surface morphology, grain connectivity between the superconducting grains and grain size distribution (from the SEM examinations), the elemental compositions and

  10. Electronic structure of clean and Ag-covered single-crystalline Bi2Sr2CuO6

    International Nuclear Information System (INIS)

    Lindberg, P.A.P.; Shen, Z.; Wells, B.O.; Mitzi, D.B.; Lindau, I.; Spicer, W.E.; Kapitulnik, A.

    1989-01-01

    Photoemission studies of single-crystalline samples of Bi 2 Sr 2 CuO 6 show clear resemblance to the corresponding data for single crystals of Bi 2 Sr 2 CaCu 2 O 8 . In particular, a sharp Fermi-level cutoff, giving evidence of metallic conductivity at room temperature, as well as single-component O 1s emission and Cu 2p satellites with a strength amounting to about 50% of that of the main Cu 2p line, are observed. An analysis of the relative core-level photoemission intensities shows that the preferential cleavage plane of single-crystalline Bi 2 Sr 2 CuO 6 is between adjacent Bi-O layers. Deposition of Ag adatoms causes only weak reaction with the Bi and O ions of the Bi 2 Sr 2 CuO 6 substrate, while the Cu states rapidly react with the Ag adatoms, as monitored by a continuous reduction of the Cu 2p satellite intensity as the Ag overlayer becomes thicker

  11. Synthesis of AgI/Bi2MoO6 nano-heterostructure with enhanced visible-light photocatalytic property

    Directory of Open Access Journals (Sweden)

    Li Zhang

    2018-04-01

    Full Text Available A novel nano-heterostructure of AgI/Bi2MoO6 photocatalyst was successfully synthesized via a facile deposition-precipitation method. The samples were systematically characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoemission spectroscopy, UV–Vis absorption spectroscopy, and photoluminescence spectra. While sole Bi2MoO6 or AgI showed poor activity toward photocatalytic rhodamine B degradation, the nano-heterostructure was found with superior performance. The AgI/Bi2MoO6 composite with an optimal content of 20 wt% AgI exhibited the highest photocatalytic degradation rate. Rhodamine B was totally degraded within 75 min visible-light irradiation. Moreover, the hybrid photocatalyst also showed a fairly good stability for several-cycle reuse. This study indicates that the AgI/Bi2MoO6 nano-heterostructure can be used as an effective candidate for photocatalytic degradation of organic pollutants. Keywords: Heterostructure, Photocatalyst, RhB-degradation

  12. Raman scattering spectra of superconducting Bi2Sr2CaCu2O8 single crystals

    International Nuclear Information System (INIS)

    Kirillov, D.; Bozovic, I.; Geballe, T.H.; Kapitulnik, A.; Mitzi, D.B.

    1988-01-01

    Raman spectra of Bi 2 Sr 2 CaCu 2 O 8 single crystals with superconducting phase-transition temperature of 90 K have been studied. The spectra contained phonon lines and electronic continuum. Phonon energies and polarization selection rules were measured. A gap in the electronic continuum spectrum was observed in a superconducting state. Noticeable similarity between Raman spectra of Bi 2 Sr 2 CaCu 2 O 8 and YBa 2 Cu 3 O 7 was found

  13. Raman scattering spectra of superconducting Bi2Sr2CaCu2O8 single crystals

    Science.gov (United States)

    Kirillov, D.; Bozovic, I.; Geballe, T. H.; Kapitulnik, A.; Mitzi, D. B.

    1988-12-01

    Raman spectra of Bi2Sr2CaCu2O8 single crystals with superconducting phase-transition temperature of 90 K have been studied. The spectra contained phonon lines and electronic continuum. Phonon energies and polarization selection rules were measured. A gap in the electronic continuum spectrum was observed in a superconducting state. Noticeable similarity between Raman spectra of Bi2Sr2CaCu2O8 and YBa2Cu3O7 was found.

  14. Bi4Sr3Ca3Cu4O16 galss and superconducting glass ceramics

    International Nuclear Information System (INIS)

    Zheng, H.; Mackenzie, J.D.

    1988-01-01

    Bi 4 Sr 3 Ca 3 Cu 4 O 16 glass has been successfully fabricated by the melting process. Glass transition temperature, crystallization temperature, and liquid temperature of the glass are 434, 478, and 833 0 C, respectively. After the glass is heat treated at 800 0 C, a glass ceramic is formed. A comparison of the x-ray-diffraction pattern of the superconducting Bi 4 Sr 3 Ca 3 Cu 4 O/sub 16+//sub x/ ceramic to the Bi 4 Sr 3 Ca 3 Cu 4 O 16 glass ceramic revealed preferred orientation in the glass ceramic crystals. The superconducting transition temperatures T/sub c//sub (onset)/ and T/sub c//sub (zero)/ of the glass ceramics are 100 and 45 K, respectively

  15. Superconductivity in REO0.5F0.5BiS2 with high-entropy-alloy-type blocking layers

    Science.gov (United States)

    Sogabe, Ryota; Goto, Yosuke; Mizuguchi, Yoshikazu

    2018-05-01

    We synthesized new REO0.5F0.5BiS2 (RE: rare earth) superconductors with high-entropy-alloy-type (HEA-type) REO blocking layers. The lattice constant a systematically changed in the HEA-type samples with the RE concentration and the RE ionic radius. A sharp superconducting transition was observed in the resistivity measurements for all the HEA-type samples, and the transition temperature of the HEA-type samples was higher than that of typical REO0.5F0.5BiS2. The sharp superconducting transition and the enhanced superconducting properties of the HEA-type samples may indicate the effectiveness of the HEA states of the REO blocking layers in the REO0.5F0.5BiS2 system.

  16. Hydrazine reduction of metal ions to porous submicro-structures of Ag, Pd, Cu, Ni, and Bi

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yue; Shi Yongfang; Chen Yubiao [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Wu Liming, E-mail: liming_wu@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

    2012-07-15

    Porous submicro-structures of Ag, Pd, Cu, Ni, and Bi with high surface area have been prepared by the reduction of hydrazine in glycerol-ethanol solution at room temperature or 120-180 Degree-Sign C. Phase purity, morphology, and specific surface area have been characterized. The reactions probably undergo three different mechanisms: simple reduction for Ag and Pd, coordination-then-reduction for Cu and Ni, and hydrolysis-then-reduction for Bi. The reductant hydrazine also plays an important role to the formation of the porous submicro-structure. The reaction temperature influences the size of the constituent particles and the overall architecture of the submicro-structure so as to influence the surface area value. The as-prepared porous metals have shown the second largest surface area ever reported, which are smaller than those made by the reduction of NaBH{sub 4}, but larger than those made by hard or soft template methods. - Graphical abstract: Porous submicro-structures of Ag, Pd, Cu, Ni, and Bi with high surface area have been prepared by the reduction of hydrazine in the glycerol-ethanol solution at room temperature or 120-180 Degree-Sign C. The reactions undergo different mechanisms: simple reduction for Ag and Pd, coordination-then-reduction for Cu and Ni, and hydrolysis-then-reduction for Bi. Highlights: Black-Right-Pointing-Pointer Syntheses of porous Ag, Pd, Cu, Ni, and Bi with high surface area. Black-Right-Pointing-Pointer Ag and Pd undergo simple reduction. Black-Right-Pointing-Pointer Cu and Ni undergo coordination-then-reduction. Black-Right-Pointing-Pointer Bi undergoes hydrolysis-then-reduction. Black-Right-Pointing-Pointer The as-prepared metals have shown the second largest surface area ever reported.

  17. Recent Advances in Layered Metal Chalcogenides as Superconductors and Thermoelectric Materials: Fe-Based and Bi-Based Chalcogenides.

    Science.gov (United States)

    Mizuguchi, Yoshikazu

    2016-04-01

    Recent advances in layered (Fe-based and Bi-based) chalcogenides as superconductors or functional materials are reviewed. The Fe-chalcogenide (FeCh) family are the simplest Fe-based high-Tc superconductors. The superconductivity in the FeCh family is sensitive to external or chemical pressure, and high Tc is attained when the local structure (anion height) is optimized. The Bi-chalcogenide (BiCh2) family are a new group of layered superconductors with a wide variety of stacking structures. Their physical properties are also sensitive to external or chemical pressure. Recently, we revealed that the emergence of superconductivity and the Tc in this family correlate with the in-plane chemical pressure. Since the flexibility of crystal structure and electronic states are an advantage of the BiCh2 family for designing functionalities, I briefly review recent developments in this family as not only superconductors but also other functional materials. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Feasible voltage-tap based quench detection in a Ag/Bi-2212 coil enabled by fast 3D normal zone propagation

    International Nuclear Information System (INIS)

    Shen, Tengming; Ye, Liyang; Li, Pei

    2016-01-01

    For this study, small insert solenoids have been built using a commercial Ag/Bi-2212 multifilamentary round wire, insulated with a new thin TiO 2 – polymer coating insulation (thickness in ~20 μm versus ~100 μm for a commonly used mullite braided sleeve insulation), and characterized in background magnetic field up to 14 T at 4.2 K to explore the high-field performance and quench detection of Bi-2212 magnets. The coil has no visible leakage and no electrical shorts after reaction, and it carries 280 A/mm -2 in a background field 14 T and generates an additional 1.7 T. A notable result is that, despite normal zones propagate slowly along the conductor, the hot spot temperature upon detection increases only from 40 K to 60 K when the resistive quench detection voltage threshold increases from 0.1 V to 1 V for all operating current density investigated, showing that quench detection using voltage taps is feasible for this coil. This is in a strong contrast to a coil we previously built to the same specifications but from wires insulated with the mullite braided sleeve insulation, for which the hot spot temperature upon detection increases from ~80 K to ~140 K while increasing from the detection voltage threshold from 0.1 V to 1 V, and thus for which quench detection using voltage taps presents significant risks, consistent with the common belief that the effectiveness of quench detection using voltage taps for superconducting magnets built using high temperature superconductors is seriously compromised by their slow normal zone propagation. This striking difference is ascribed to the fast transverse quench propagation enabled by thin insulation and improved thermal coupling between conductor turns. Finally, this work demonstrates that quench detection for high-temperature superconducting magnets highly depends on the design and construction of the coils such as insulation materials used and this dependence should be factored into the overall magnet design

  19. Soldering of copper-clad niobium--titanium superconductor composite

    International Nuclear Information System (INIS)

    Moorhead, A.J.; Woodhouse, J.J.; Easton, D.S.

    1977-04-01

    When superconductivity is applied to various electrical devices, the joining of the superconducting material and the performance of the joints are generally crucial to the successful operation of the system. Although many techniques are being considered for joining composite superconductors, soldering is the most common. We determined the wetting and flow behavior of various solder and flux combinations on a copper-clad Nb-Ti composite, developed equipment and techniques for soldering and inspection of lap joints, and determined the shear strength of joints at temperatures down to -269 0 C (4 0 K). We studied 15 solders and 17 commercial and experimental fluxes in the wettability and flow tests. A resistance unit was built for soldering test specimens. A series of samples soldered with 80 Pb-20 Sn, 83 Pb-15 Sn-2 Sb, 97.5 Pb-1.5 Ag-1 Sn, 80 In-15 Pb-5 Ag, or 25 In-37.5 Pb-37.5 Sn (wt percent) was inspected by three nondestructive techniques. Through-transmission ultrasound gave the best correlation with nonbond areas revealed in peel tests. Single-lap shear specimens soldered with 97.5 Pb-1.5 Ag-1 Sn had the highest strength (10.44 ksi, 72 MPa) and total elongation (0.074 in., 1.88 mm) at -269 0 C (4 0 K) of four solders tested

  20. Experimental and numerical study of influence of ferromagnetic cover on critical current of BiSCCO-2223/Ag tape superconductor

    International Nuclear Information System (INIS)

    Vojenciak, M; Souc, J; Goemoery, F

    2009-01-01

    Samples of commercially available BiSCCO-2223/Ag tape have been partially covered by the ferromagnetic material. Improvement of the self-field critical current up to 15 % has been achieved by this procedure. A critical current of such tape strongly depends on geometric and magnetic properties of both, the superconducting tape as well as the ferromagnetic cover. Numerical simulations, based on the critical state model using commercial finite element method (FEM) code, have been performed. Properties of superconductor are characterized by anisotropic dependence of the critical current density on magnetic field as well as detail geometry of filaments. The ferromagnetic material is characterized by nonlinear magnetization curve. Nonlinear dependences of the critical current on selected parameters are shown in this work. Optimization of the cover parameters using these curves has been made. Samples with various parameters have been manufactured for the confirmation of numerical simulations results. Experimental results are in good qualitative agreement with results obtained by numerical simulations.

  1. Pressure induced superconductivity in the antiferromagnetic Dirac material BaMnBi2

    OpenAIRE

    Huimin Chen; Lin Li; Qinqing Zhu; Jinhu Yang; Bin Chen; Qianhui Mao; Jianhua Du; Hangdong Wang; Minghu Fang

    2017-01-01

    The so-called Dirac materials such as graphene and topological insulators are a new class of matter different from conventional metals and (doped) semiconductors. Superconductivity induced by doing or applying pressure in these systems may be unconventional, or host mysterious Majorana fermions. Here, we report a successfully observation of pressure-induced superconductivity in an antiferromagnetic Dirac material BaMnBi2 with T c of ~4?K at 2.6?GPa. Both the higher upper critical field, ? 0 H...

  2. Experiment of enhancing critical current in Bi-2223/Ag tape by means of ferromagnetic shielding

    Energy Technology Data Exchange (ETDEWEB)

    Alamgir, A.K.M. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China)]. E-mail: alam643@hotmail.com; Gu, C. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Han, Z. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China)

    2005-11-15

    Critical current in multifilamentary Ag-sheath Bi-2223 tape is enhanced to some extent by means of thin and narrow coating of pure nickel. The concept of enhancing critical current is based on the magnetic shielding effect resulting in redirection of self-field flux lines. The Ni coating was introduced at the edge regime of the tape in order to redirect the perpendicular component of self-field lines which is severe at the edges. Critical current in a typical Ag-sheath Bi-2223 tape was enhanced up to {approx}11% by 50 {mu}m thick and 0.4 mm long Ni coating without any change of self-field loss. This fact reveals that additional ferromagnetic loss could be compensated by the shielding effect and increased critical current of the tape. The degree of enhancement in critical current as well as ferromagnetic impact on ac losses depend on the length and thickness of ferromagnetic coating introduced. Therefore, it is very important to control the geometry of ferromagnetic coating in order to balance the critical current and ac loss for optimum superconductor performance. Introduction of ferromagnetic coating and its effect on electromagnetic properties in multifilamentary Bi-2223/Ag tape will be reported in this article.

  3. Experiment of enhancing critical current in Bi-2223/Ag tape by means of ferromagnetic shielding

    International Nuclear Information System (INIS)

    Alamgir, A.K.M.; Gu, C.; Han, Z.

    2005-01-01

    Critical current in multifilamentary Ag-sheath Bi-2223 tape is enhanced to some extent by means of thin and narrow coating of pure nickel. The concept of enhancing critical current is based on the magnetic shielding effect resulting in redirection of self-field flux lines. The Ni coating was introduced at the edge regime of the tape in order to redirect the perpendicular component of self-field lines which is severe at the edges. Critical current in a typical Ag-sheath Bi-2223 tape was enhanced up to ∼11% by 50 μm thick and 0.4 mm long Ni coating without any change of self-field loss. This fact reveals that additional ferromagnetic loss could be compensated by the shielding effect and increased critical current of the tape. The degree of enhancement in critical current as well as ferromagnetic impact on ac losses depend on the length and thickness of ferromagnetic coating introduced. Therefore, it is very important to control the geometry of ferromagnetic coating in order to balance the critical current and ac loss for optimum superconductor performance. Introduction of ferromagnetic coating and its effect on electromagnetic properties in multifilamentary Bi-2223/Ag tape will be reported in this article

  4. Emergence of superconductivity in topological insulator Bi{sub 2}Se{sub 3} by Sr intercalation

    Energy Technology Data Exchange (ETDEWEB)

    Shruti,; Maurya, V. K.; Srivastava, P.; Patnaik, S., E-mail: spatnaik@mail.jnu.ac.in [School of Physical Sciences, Jawaharlal Nehru University, New Delhi-110067 (India)

    2016-05-23

    Recently superconductivity wasreported by Sr intercalation in topological insulator Bi{sub 2}Se{sub 3}. In this report we extensively study anisotropic superconducting properties of Sr{sub 0.1}Bi{sub 2}Se{sub 3} with transition at ~2.9 through resistivity and DC magnetization measurement. We also discuss synthesis methodology for growth of single crystal Sr-Bi{sub 2}Se{sub 3}. The anisotropic properties of Sr{sub 0.1}Bi{sub 2}Se{sub 3} single crystals were studied using transport measurements. Using Ginzburg Landau formulas the upper critical field H{sub c2}(0) comes out to be 2.1 T and 1.4 T for magnetic field applied along the ab-plane and c-axis of the single crystalsand corresponding Ginzburg - Landau coherence lengths are ξ{sub ab} = 15.3 nm and ξ{sub c} = 10.2 nm. The sample shows weak electronic anisotropy Γ = 1.5. Hall resistivity is linear with field at 10 K.

  5. Bi--Sr--Ca--Cu--O superconducting films fabricated using metal alkoxides

    International Nuclear Information System (INIS)

    Katayama, S.; Sekine, M.

    1991-01-01

    Superconducting films in the Bi--Sr--Ca--Cu--O systems were made using metal alkoxides. To prepare a dip-coating solution using a mixed alkoxide solution, insoluble Cu and Bi alkoxides were dissolved by modification with 2-dimethylaminoethanol and formation of a double alkoxide, respectively. Formation of the double alkoxides of Bi with Ca or Sr was confirmed using FT-IR and 1 H-NMR. Bi--Sr--Ca--Cu--O films on yttria-stabilized ZrO 2 and single crystal MgO(100) substrates were made using this solution. The films were closely oriented along the c-axis perpendicular to the substrate. The film on MgO(100) fired at 850 degree C for 48 h showed two resistance drops around 115 and 85 K, corresponding to the high-T c and low-T c phases, respectively, and zero resistance at 72 K

  6. Electronic energy loss of low velocity H+ beams in Al, Ag, Sb, Au and Bi

    International Nuclear Information System (INIS)

    Valdes, J.E.; Martinez Tamayo, G.; Lantschner, G.H.; Eckardt, J.C.; Arista, N.R.

    1993-01-01

    The energy loss of H + ions in thin polycrystalline Al, Sb, Ag, Au and Bi films has been determined in the energy range below 10 keV. This low-energy range is of special interest to fill a lack of low-energy experimental data and test various theoretical predictions and semiempirical formulas. We find that the general theoretical prediction of a velocity-proportional dependence of energy loss does not hold for all targets studied in this work. The velocity-proportionality is better satisfied for Al, Sb and Bi, whereas a departure from such dependence is observed at lower energies for Ag and Au targets. The results obtained here are in good general agreement with nonlinear stopping power calculations based on density functional theory. Comparison with semiempirical predictions, and other experimental results are also done. (orig.)

  7. Enhanced photo-stability and photocatalytic activity of Ag3PO4 via modification with BiPO4 and polypyrrole

    Science.gov (United States)

    Cai, Li; Jiang, Hui; Wang, Luxi

    2017-10-01

    Ag3PO4 photocatalysts modified with BiPO4 and polypyrrole (PPy) were successfully synthesized via a combination of co-precipitation hydrothermal technique and oxidative polymerization method. Their morphologies, structures and optical and electronic properties were characterized by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET) surface areas, X-ray diffraction (XRD), fourier transform infrared spectra (FT-IR), X-ray photo-electron spectroscopy (XPS), UV-vis diffuse reflection spectra (UV-vis DRS), photocurrent technique and electrochemical impedance spectra (EIS). The typical triphenylmethane dye (malachite green) was chosen as a target organic contaminants to estimate the photocatalytic activities and photo-stabilities of Ag3PO4-BiPO4-PPy heterostructures under visible light irradiation. The results indicated that the existence of BiPO4 and PPy not only showed great influences on the photocatalytic activity, but also significantly enhanced photo-stability of Ag3PO4 in repeated and long-term applications. The degradation conversion of Ag3PO4-BiPO4-PPy heterostructures (ABP-3) was 1.58 times of that of pure Ag3PO4. The photo-corrosion phenomenon of Ag3PO4 was effectively avoided. The photocatalytic activity of up to 87% in the Ag3PO4-BiPO4-PPy heterostructures (ABP-3) can be remained after five repeated cycles, while only about 33% of the degradation efficiency can be reserved in pure Ag3PO4. The possible mechanism of enhanced photo-stability and photocatalytic activity of Ag3PO4-BiPO4-PPy heterostructures was also discussed in this work.

  8. Fabrication of Bi2223 bulks with high critical current properties sintered in Ag tubes

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Yasuaki, E-mail: ytakeda@g.ecc.u-tokyo.ac.jp [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Shimoyama, Jun-ichi; Motoki, Takanori [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258 (Japan); Kishio, Kohji [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nakashima, Takayoshi; Kagiyama, Tomohiro; Kobayashi, Shin-ichi; Hayashi, Kazuhiko [Sumitomo Electric Industries, Ltd. 1-1-3 Shimaya, Konohana-ku, Osaka 554-0024 (Japan)

    2017-03-15

    Highlights: • Fabrication conditions of Bi2223 bulks was reconsidered in terms of high J{sub c}. • Pressure of uniaxial pressing and heat treatment conditions were investigated. • The best sample showed higher J{sub c} than that of practically used Bi2223 bulks. - Abstract: Randomly grain oriented Bi2223 sintered bulks are one of the representative superconducting materials having weak-link problem due to very short coherence length particularly along the c-axis, resulting in poor intergrain J{sub c} properties. In our previous studies, sintering and/or post-annealing under moderately reducing atmospheres were found to be effective for improving grain coupling in Bi2223 sintered bulks. Further optimizations of the synthesis process for Bi2223 sintered bulks were attempted in the present study to enhance their intergrain J{sub c}. Effects of applied pressure of uniaxial pressing and sintering conditions on microstructure and superconducting properties have been systematically investigated. The best sample showed intergrain J{sub c} of 2.0 kA cm{sup −2} at 77 K and 8.2 kA cm{sup −2} at 20 K, while its relative density was low ∼65%. These values are quite high as for a randomly oriented sintered bulk of cuprate superconductors.

  9. Fabrication and properties of Ag-Bi2223 tapes with resistive barriers for filament decoupling

    International Nuclear Information System (INIS)

    Inada, Ryoji; Fukumoto, Yohei; Yasunami, Taeko; Nakamura, Yuichi; Oota, Akio; Li Chengshang; Zhang Pingxiang

    2007-01-01

    In this paper, we prepared the Bi2223 multifilamentary tapes with Ca 2 CuO 3 + Bi2212 as interfilamentary resistive barriers to suppress the electromagnetic coupling among the filaments under AC external magnetic field. The tapes with thin barrier layers of Ca 2 CuO 3 + 30 wt% Bi2212 around the filaments were prepared by using a standard powder-in-tube (PIT) method. The outside surface of monocore Ag-sheathed rods was coated by barrier materials. Then, the several coated monocore wires were stacked and packed into another Ag or Ag-Mg alloy tube. The packed tube was drawn and rolled into tape shape. The tape was subsequently sintered to form Bi2223 phase inside filaments. For the characterization of tapes, X-ray diffraction measurements were performed to investigate the phase formation inside the filaments. The uniformity of transport properties (J c ) for barrier tapes were evaluated on the order of several metre lengths and compared with the result for the tapes without barriers. Finally, AC loss characteristics under AC parallel transverse magnetic field were investigated to examine the effect of introducing the barriers on the filament decoupling

  10. Dopant rearrangement and superconductivity in Bi2Sr2-xLaxCuO6 thin films under annealing

    International Nuclear Information System (INIS)

    Cancellieri, C; Lin, P H; Ariosa, D; Pavuna, D

    2007-01-01

    By combining x-ray diffraction (XRD), x-ray photoemission spectroscopy (XPS) and AC susceptibility measurements we investigate the evolution of structural and superconducting properties of La-doped Bi-2201 thin films grown by pulsed laser deposition (PLD) under different annealing conditions. We find that the main effect of oxygen annealing is to improve the crystal coherence by enabling La cation migration to the Sr sites. This activates the desired hole doping. Short-time Ar annealing removes the interstitial oxygen between the BiO layers, fine adjusting the effective hole doping. The superconducting critical temperature is consequently enhanced. However, longer annealings result in phase separation and segregation of the homologous compound Bi-1201. We attribute this effect to the loss of Bi during the annealing

  11. Improved solar-driven photocatalytic performance of Ag_2CO_3/(BiO)_2CO_3 prepared in-situ

    International Nuclear Information System (INIS)

    Zhong, Junbo; Li, Jianzhang; Huang, Shengtian; Cheng, Chaozhu; Yuan, Wei; Li, Minjiao; Ding, Jie

    2016-01-01

    Highlights: • Ag_2CO_3/(BiO)_2CO_3 photocatalysts were prepared in-situ. • The photo-induced charge separation rate has been greatly increased. • The photocatalytic activity has been greatly promoted. - Abstract: Ag_2CO_3/(BiO)_2CO_3 composites have been fabricated in-situ via a facile parallel flaw co-precipitation method. The specific surface area, structure, morphology, and the separation rate of photo-induced charge pairs of the photocatalysts were characterized by Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy(DRS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and surface photovoltage (SPV) spectroscopy, respectively. XRD patterns and DRS demonstrated that Ag_2CO_3 has no effect on the crystal phase and bandgap of (BiO)_2CO_3. The existence of Ag_2CO_3 in the composites enhances the separation rate of photo-induced charge pairs of the photocatalysts. The photocatalytic performance of Ag_2CO_3/(BiO)_2CO_3 was evaluated by the decolorization of methyl orange (MO) aqueous solution under simulated solar irradiation. It was found that the simulated solar-induced photocatalytic activity of Ag_2CO_3/(BiO)_2CO_3 copmposites was significantly improved, which was mainly attributed to the enhanced surface area and the separation rate of photo-induced charge pairs.

  12. Enhanced photocatalytic activity of Bi{sub 2}O{sub 3}–Ag{sub 2}O hybrid photocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xinjuan, E-mail: lxj669635@126.com [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Liu, Junying [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Chu, Haipeng [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Li, Jinliang; Yu, Wei [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Zhu, Guang [Anhui Key Laboratory of Spin Electron and Nanomaterials, Suzhou University, Suzhou 234000 (China); Niu, Lengyuan [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Sun, Zhuo [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Pan, Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Sun, Chang Q. [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China)

    2015-08-30

    Graphical abstract: Bi{sub 2}O{sub 3}–Ag{sub 2}O composites were fabricated for visible light photocatalytic degradation of phenol with a high degradation rate of 92% for 60 min. - Highlights: • Bi{sub 2}O{sub 3}–Ag{sub 2}O composites were synthesized via a co-precipitation method. • The photocatalytic activity for the degradation of phenol is investigated. • A high degradation rate of 92% for 60 min is achieved under visible light irradiation. - Abstract: Bi{sub 2}O{sub 3}–Ag{sub 2}O hybrid photocatalysts were successfully synthesized via a co-precipitation method. The morphology, structure and photocatalytic performance in the degradation of phenol were characterized by using scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, electrochemical impedance spectra and UV–vis absorption spectroscopy, respectively. The results show that Bi{sub 2}O{sub 3}–Ag{sub 2}O hybrid photocatalysts exhibit enhanced photocatalytic performance in the degradation of phenol with a maximum degradation rate of 92% for 60 min under visible light irradiation compared with pure Bi{sub 2}O{sub 3} (57%), which is ascribed to the increase in light adsorption and the reduction in electron–hole pair recombination with the introduction of Ag{sub 2}O.

  13. Bi-Sr-Ca-Cu-O superconducting thin films: theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, M [Department of Mechanical Engineering and Mechatronics Engineering Program, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Boybay, M S [Department of Mechanical Engineering and Mechatronics Engineering Program, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Elbuken, C [Department of Mechanical Engineering and Mechatronics Engineering Program, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Andrews, M J [Los Alamos National Lab, PO Box 1663, Mail Stop B 296, Los Alamos, NM 87545 (United States); Hu, C R [Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Ross, J H [Department of Physics, Texas A and M University, College Station, Texas 77843 (United States)

    2006-06-01

    The interest of this paper centers on fabrication and characterization and modeling of vortices in high temperature superconducting thin films. As a first step, the magnetic vertices of the superconducting matrix were modeled. As a second, Bi-Sr-Ca-Cu-O thin films were grown using Pulsed Laser Ablation (PLD) on single crystal MgO substrates as magnetic templates for the potential use for Nano and Microelectronic circuits, and were characterized by x-ray diffraction, electron, and atomic force microscopy. The third step (future work) will be observation and pinning of these vortices using Bitter decoration.

  14. Phase transformation and tribological properties of Ag-MoO3 contained NiCrAlY based composite coatings fabricated by laser cladding

    Science.gov (United States)

    Wang, Lingqian; Zhou, Jiansong; Xin, Benbin; Yu, Youjun; Ren, Shufang; Li, Zhen

    2017-08-01

    Ag-MoO3 contained NiCrAlY based composite coating was successfully prepared on GH4169 stainless steel substrate by high energy ball milling and laser cladding. The microstructure and phase transformation were investigated by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction spectrum (XRD). The tribological behavior and mechanism from room temperature to 800 °C were investigated. Results showed that MoO3 in the composite powders transformed to Mo2C reinforcement under the high energy density of laser, and a series of opposite transformation occurred during friction process. The coating showed the lowest friction coefficient and low wear rate at 600 °C and 800 °C due to the generation of Ag2MoO4 during tribo-chemical reactions and the formation of lubrication glaze on the worn surface. Ag made effective lubrication when the temperature rose up to 200 °C. The coating displayed a relatively high friction coefficient (about 0.51) at 400 °C, because though MoO3 (oxidation products of Mo2C) and Ag2MoO4 were detected on the worn surface, they could not realize effective lubrication at this temperature. Abrasive wear, adhesive wear and plastic deformation contributed to the increased friction and wear.

  15. Research On Bi-Based High-Temperature Superconductors

    Science.gov (United States)

    Banks, Curtis; Doane, George B., III; Golben, John

    1993-01-01

    Brief report describes effects of melt sintering on Bi-based high-temperature superconductor system, as well as use of vibrating-sample magnetometer to determine hysteresis curves at 77 K for partially melt-sintered samples. Also discussed is production of high-temperature superconducting thin films by laser ablation: such films potentially useful in detection of signals of very low power.

  16. Superconductivity in volumetric and film ceramics Bi-Sr-Ca-Cu-O

    International Nuclear Information System (INIS)

    Sukhanov, A.A.; Ozmanyan, Kh.R.; Sandomirskij, B.B.

    1988-01-01

    A superconducting transition with T c0 =82-95 K and T c (R=0)=82-72 K was observed in volumetric and film Bi(Sr 1-x Ca x ) 2 Cu 3 O y samples obtained by solid-phase reaction. Temperature dependences of resistance critical current and magnetic susceptibility are measured

  17. Superconductivity in Bi-Sr-Ca-Cu-O bulk and film ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, A A; Ozmanian, KH R; Sandomirskii, B B

    1988-07-01

    A superconducting transition with Tc0 = 82-95 K and Tc(R = 0) = 82-72 K was observed in Bi(Sr/1-x/Ca/x/)2Cu3O(y) bulk and film specimens obtained via a solid-phase reaction. Temperature dependences of the resistance, critical current, and magnetic susceptibility were measured.

  18. Structural and superconducting properties of YBa2Cu3-xMxOy (M=Ag, Al

    Directory of Open Access Journals (Sweden)

    S Falahati

    2009-08-01

    Full Text Available   Samples of YBa2Cu3-xAgxOy with x=0, 0.1, 0.15, 0.2, 0.3 and samples of YBa2Cu3-xAlxOy with x=0, 0.01, 0.02, 0.03 and 0.045 are prepared by the sol-gel method. Structural and superconducting properties of samples are studied by electrical resistivity (R-T, X-ray diffraction (XRD and scanning electron microscopy (SEM. All the samples show transition to superconducting state and the transition temperatures of the samples increased with increasing Ag doping up to x=0.15. R-T measurements show a small decrease of TC (zero with increasing Al doping up to x=0.02, and followed by a faster decrease with increasing doping concentration. YBCO grains are better linked with increasing Ag doping. So, Ag has positive effects in superconducting properties of YBCO. The crystal structure of samples was refined by MAUD. These results show tha, Ag is substituted for Cu(1 in YBCO. According to these analysis, we introduce x=0.15 as the optimum value for doping concentration .

  19. Bending strain study of Bi-2223/Ag tapes using Hall sensor magnetometry

    International Nuclear Information System (INIS)

    Lahtinen, M.; Paasi, J.; Sarkaniemi, J.; Han, Z.; Freltoft, T.

    1996-01-01

    The influence of room temperature bending on critical current (I c ) of Bi-2223/Ag tapes is studied by Hall sensor magnetometry, four-point method and scanning electron microscopy. Hall sensor magnetometry allows one to assess tape homogeneity and the amount of mechanical damage caused by bending. The microstructure of the Bi-2223 ceramic is found to strongly affect the tape behavior under bending strain. In a tape with moderate I c = 6.1 A at 77 K and a porous ceramic core, crack propagation took place normal to the Ag-ceramic interface, whereas in tapes with dense core, I c above 10 A at 77 K, cracks propagated in the tape plane. In monofilamentary tapes core homogeneity correlated with good bending strain performance. In multifilamentary tapes crack propagation between filaments was prohibited by the Ag matrix, thus leading to enhanced strain tolerance. In the high I c tapes studied, bending to 25 mm radius resulted in 1%--2% I c degradation

  20. The preparation of Ag-BiVO4 metal composite oxides and its application in efficient photocatalytic oxidative thiophene

    Science.gov (United States)

    Gao, Xiao-Ming; Fu, Feng; Zhang, Li-Ping; Li, Wen-Hong

    2013-06-01

    A series of Ag-BiVO4 photocatalysts was synthesized by the hydrothemal synthesis method for different pH values. A strong correlation was found among the prepared processing, structure and property of the samples. With increasing pH value from 5 to 9, the crystallinity increases and the as-prepared Ag-BiVO4 sample gradually disappeared from the nanostructures. The light absorption became higher in the UV and visible range, accompanied by a bathochromic shift of the absorption edge. The competitive relations between crystallinity and surface area affecting photocatalytic activity were also discussed. Photocatalytic desulfurization on the as-prepared Ag-BiVO4 samples using thiophene dissolved in n-octane as a model organosulfur compound was performed. It showed that the photocatalytic desulfurization on the as-prepared Ag-BiVO4 sample at pH=7 can be up to 95%, which existed as various size particles and had significant high surface area of 13.768 m2 g-1.

  1. Studies on Bi-Sr-Ca-Cu-O glasses and superconducting glass ceramics

    International Nuclear Information System (INIS)

    Singh, R.; Zacharias, E.

    1991-01-01

    Bi-Sr-Ca-Cu-O glasses and glass ceramics of various compositions were synthesised. The glass transition temperature varies from 396 to 422degC depending on the glass composition. The bulk glass ceramics of 4334, 4336, 2223 and 4246 compositions show superconductivity when the corresponding glass samples were heat-treated in air at 820degC for 3, 9, 12 and 24 h respectively. X-ray diffraction studies show that the superconducting phase present in all these compositions is Bi 2 Sr 2 Ca 1 Cu 2 O x . The 4334 glass ceramic is almost a single-phase material with a preferred orientation such that the c axis is normal to the sample surface. The 2223 glass ceramic has a higher T c (onset) than the other three compositions indicating the presence of high T c phase (110 K) also. ESR studies on the glass samples indicate the existence of Cu 2+ . The effect of heat treatment on ESR shows that the intensity of resonance decreases with increase in heat-treatment duration. This effect is more pronounced for the 4334 and 2223 compositions. The advantages of synthesizing superconducting materials by glass route are discussed in view of practical applications. (author). 9 refs., 6 figs

  2. Superconductivity in volumetric and film ceramics Bi-Sr-Ca-Cu-O

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, A A; Ozmanyan, Kh R; Sandomirskij, B B

    1988-07-10

    A superconducting transition with T/sub c0/=82-95 K and T/sub c/(R=0)=82-72 K was observed in volumetric and film Bi(Sr/sub 1-x/Ca/sub x/)/sub 2/Cu/sub 3/O/sub y/ samples obtained by solid-phase reaction. Temperature dependences of resistance critical current and magnetic susceptibility are measured.

  3. Microstructure, Mechanical and Tribological Properties of Ag/Bi2Sr2CaCu2O x Self-lubricating Composites

    Science.gov (United States)

    Tang, Hua; Zhang, Du; Wang, Yuqi; Zhang, Yi; Ji, Xiaorui; Song, Haojie; Li, Changsheng

    2014-01-01

    Ag/Bi2Sr2CaCu2O x self-lubricating composites were successfully fabricated by a facile powder metallurgy method. The structure and morphology of the as-synthesized composites and the worn surface after tribometer testing are characterized by using X-ray diffraction and scanning electron microscopy together with energy dispersive spectrometry. The results indicated that self-lubricating composites are composed of superconductor phase and Ag phase. Moreover, the effects of Ag on mechanical and tribological properties of the novel composites were investigated. The friction test results showed that the friction coefficient of the pure Bi2212 against stainless steel is about 0.40 at ambient temperature and abruptly decreases to about 0.17 when the temperature is cooled to 77 K. The friction coefficients of the composites from room temperature to high temperature were lower and more stable than those of pure Bi2Sr2CaCu2O x . When the content of Ag is 10 wt.%, the Ag/Bi2Sr2CaCu2O x composites exhibited excellent tribological performance, the improved tribological properties are attributed to the formation of soft metallic Ag films at the contacted zone of the composites.

  4. Evidence for charge transfer in Bi-based superconductors studied by positron annihilation

    International Nuclear Information System (INIS)

    Tang, Z.; Wang, S.J.; Gao, X.H.; Ce, G.C.; Zhao, Z.X.

    1993-01-01

    We have measured Doppler-broadening annihilation radiation (DBAR) spectra and positron lifetimes in normal and superconducting states for three kinds of Bi-based superconductors: Bi2212, Pb-doped Bi2223, Pb- and F-doped Bi2223. The difference spectra after deconvolution between two states show a sharpening effect with increasing temperature; the F-doped sample has the greatest amplitude in difference spectra but nearly the same positron lifetimes as the Pb-doped sample. The results are interpreted in terms of charge transfer between the Cu-O and Bi-O planes. The role of oxygen defects in charge transfer is discussed. (orig.)

  5. Effects of low-level Ag doping on Bi2Sr2CaCu2O8+x

    International Nuclear Information System (INIS)

    Deis, T.A.; Eror, N.G.; Krishnaraj, P.; Prorok, B.C.; Lelovic, M.; Balachandran, U.

    1995-07-01

    Bi 2 Sr 2 CaCu 2 O 8 has been doped with silver, up to 10,000 ppm, in three ways: excess additions, substitution of Ag for Bi, and substitution of Ag for Sr. Effects of doping on the c-axis lattice parameter and critical temperature (T c ) were measured. Effects from doing were only observed in slow-cooled [10 degree/hr] oxygen equilibrated samples. Doping by excess additions caused a small decrease in T c and an increase in the c-axis length of the lattice. Doping by substitution, compared to excess Ag additions, caused a larger decrease in T c and higher c-axis values for doping levels up to 1,000 ppm. Doping by substitution at higher levels (1,000--10,000 ppm) caused T c to increase and the c-axis to decrease. Samples with similar substitutional doping levels exhibited comparable T c values and samples with Ag substituted for Sr consistently exhibited higher c-axis values than samples that had equivalent amounts of Ag substituted for Bi

  6. Band Structure Engineering of Cs2AgBiBr6 Perovskite through Order-Disordered Transition: A First-Principle Study.

    Science.gov (United States)

    Yang, Jingxiu; Zhang, Peng; Wei, Su-Huai

    2018-01-04

    Cs 2 AgBiBr 6 was proposed as one of the inorganic, stable, and nontoxic replacements of the methylammonium lead halides (CH 3 NH 3 PbI 3 , which is currently considered as one of the most promising light-harvesting material for solar cells). However, the wide indirect band gap of Cs 2 AgBiBr 6 suggests that its application in photovoltaics is limited. Using the first-principle calculation, we show that by controlling the ordering parameter at the mixed sublattice, the band gap of Cs 2 AgBiBr 6 can vary continuously from a wide indirect band gap of 1.93 eV for the fully ordered double-perovskite structure to a small pseudodirect band gap of 0.44 eV for the fully random alloy. Therefore, one can achieve better light absorption simply by controlling the growth temperature and thus the ordering parameters and band gaps. We also show that controlled doping in Cs 2 AgBiBr 6 can change the energy difference between ordered and disordered Cs 2 AgBiBr 6 , thus providing further control of the ordering parameters and the band gaps. Our study, therefore, provides a novel approach to carry out band structure engineering in the mixed perovskites for optoelectronic applications.

  7. Shielded high-T{sub c} (Bi, Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Bi-2223) superconducting tapes

    Energy Technology Data Exchange (ETDEWEB)

    Lelovic, M.; Eror, N.G. [Department of Materials Science, University of Pittsburgh, Pittsburgh, PA (United States); Balachandran, U.; Prorok, B. [Energy Technology Division, Argonne National Laboratory, Argonne, IL (United States); Selvamanickam, V.; Haldar, P. [Intermagnetics General Corporations, Latham, NY (United States); Talvacchio, J.; Young, R. [Science and Technology Center, Northrop Grumman, Pittsburgh, PA (United States)

    1998-11-01

    A new composite tape was fabricated in which the primary function of the central Ag-sheathed (Bi, Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Bi-2223) filaments was to conduct transport current. A YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (Y-123) thin film was deposited on the top of the Ag-sheathed Bi-2223 tape to shield the applied magnetic field and to protect the central Bi-2223 filaments. The critical current densities of the Y-123-coated, Ag-sheathed Bi-2223 tapes were better than those of an uncoated tape. However, the Y-123 thin film exhibited T{sub c} approx.= 72 K and a broad transition region that shifted the effect to lower temperatures. Furthermore, pole figure measurements showed widely spread a,b planes along the rolling direction, indicating high-angle grain boundaries that diminished the magnitude of the effect. Microstructural observations showed platelike grains of Y-123 with fine growth ledges in the thin film that was heat treated, in contrast with the microstructure of an as-coated thin film that showed large twinned grains. From the processing point of view, the results showed that heat treating Y-123 thin film according to the Bi-2223 tape schedule was compatible with and beneficial for Y-123. These preliminary results may provide a basis for further improvements in processing of long-length Bi-2223 tapes for high-field applications. (author)

  8. Grain boundaries and defects in superconducting Bi-Sr-Ca-Cu-O ceramics

    International Nuclear Information System (INIS)

    Ramesh, R.; Bagley, B.G.; Tarascon, J.M.; Green, S.M.; Rudee, M.L.; Luo, H.L.

    1990-01-01

    Defects and structural interfaces in superconducting Bi-Sr-Ca-Cu-O have been characterized by transmission electron microscopy. The superconducting phase exhibits frequent variations in the stacking sequence (polytypoids). Dislocations, observed inside the grains, either introduce or accommodate the shear in the a-b plane and the local composition fluctuations. In general, the grains exhibit a platelike morphology with the a-b plane as the grain boundary plane. Grain boundaries along the short edge are generally disordered, whereas those near the long edge generally have a thin layer of the lower T c polytypoid. Coherent intragranular boundaries are also observed

  9. Stability analysis of high temperature superconducting coil in liquid hydrogen

    International Nuclear Information System (INIS)

    Nakayama, T.; Yagai, T.; Tsuda, M.; Hamajima, T.

    2007-01-01

    Recently, it is expected that hydrogen plays an important role in energy source including electric power in near future. Liquid hydrogen has high potential for cooling down superconducting coil wound with high temperature superconductors (HTS), such as BSCCO, YBCO. In this paper, we study stabilities of the coils wound with BSCCO tapes, which are immersed in the liquid hydrogen, and compare stability results with those cooled by liquid helium. We treat a minimum propagation zone (MPZ) theory to evaluate the coil stability considering boiling heat flux of the liquid hydrogen, and specific heat, heat conduction and resistivity of HTS materials as a function of temperature. It is found that the coil cooled by the liquid hydrogen has higher stability margin than that cooled by the liquid helium. We compare the stability margins of both coils wound with Bi-2223/Ag tape and Bi-2212/Ag tape in liquid hydrogen. As a result, it is found that the stability of Bi-2212 coil is equivalent to that of Bi-2223 coil in low and high magnetic field, while the maximum current of Bi-2212 coil exceeds a little bit that of Bi-2223 coil in both magnetic fields

  10. Second Harmonic Generation of Violet Light in Femtosecond-Laser-Inscribed BiB3O6 Cladding Waveguides

    Directory of Open Access Journals (Sweden)

    Jia Yuechen

    2013-11-01

    Full Text Available We report on the second harmonic generation of violet light of a nonlinear cladding waveguide in BiB3O6 crystal produced by femtosecond laser inscription. Under continuous-wave pump laser at 800 nm, the guided second harmonic wave at 400 nm with a conversion efficiency of ~0.32% has been realized through the Type I birefringence phase matching configuration.

  11. Fast preparation of Bi2GeO5 nanoflakes via a microwave-hydrothermal process and enhanced photocatalytic activity after loading with Ag nanoparticles

    International Nuclear Information System (INIS)

    Li, Zhao-Qian; Lin, Xin-Shan; Zhang, Lei; Chen, Xue-Tai; Xue, Zi-Ling

    2012-01-01

    Highlights: ► Bi 2 GeO 5 nanoflakes were successfully synthesized via a microwave-assisted solution-phase approach. ► Ag nanoparticles were deposited on the Bi 2 GeO 5 nanoflakes by a photoreduction procedure. ► Catalytic activity of the Ag/Bi 2 GeO 5 nanocomposite in the photo-degradation of rhodamine B (RhB) was much higher than that of pure Bi 2 GeO 5 . -- Abstract: In this work, a facile and rapid microwave-assisted hydrothermal route has been developed to prepare Bi 2 GeO 5 nanoflakes. Ag nanoparticles were subsequently deposited on the Bi 2 GeO 5 nanoflakes by a photoreduction procedure. The phases and morphologies of the products were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectroscopy. Photocatalytic experiments indicate that such Ag/Bi 2 GeO 5 nanocomposite possesses higher photocatalytic activity for RhB degradation under UV light irradiation in comparison to pure Bi 2 GeO 5 . The amount of Ag in the nanocomposite affects the catalytic activity, and 3 wt% Ag showed the highest photodegradation efficiency. Moreover, the catalyst remains active after four consecutive tests. The present study provides a new strategy to design composite materials with enhanced photocatalytic activity.

  12. Tailoring particle size and morphology of colloidal Ag particles via chemical precipitation for Ag-BSCCO composites

    International Nuclear Information System (INIS)

    Medendorp, N.W. Jr.; Bowman, K.J.; Trumble, K.P.

    1996-01-01

    The chemical precipitation of silver particles is an effective method for tailoring the particle size and morphology. This article investigates a chemical precipitation method for producing silver colloids, and how processing parameters affected particle size, morphology and adherence. Decreasing the silver nitrate concentration during precipitation with sodium borohydride decreased the colloidal silver particle size. Decreasing the addition rate of the reducing agent produced faceted particles. Reversing the reactant addition order also changed the particle size and the morphology. Precipitated colloids demonstrated a difference between the growth-dominated and the equilibrium structures. Co-dispersing Bi-based superconducting platelets during precipitation allowed Ag colloids to preferentially nucleate on the platelets and to remain adhered even after the additional processing. (orig.)

  13. Strain induced irreversible critical current degradation in highly dense Bi-2212 round wire

    CERN Document Server

    Bjoerstad, R; Rikel, M.O.; Ballarino, A; Bottura, L; Jiang, J; Matras, M; Sugano, M; Hudspeth, J; Di Michiel, M

    2015-01-01

    The strain induced critical current degradation of overpressure processed straight Bi 2212/Ag wires has been studied at 77 K in self-field. For the first time superconducting properties, lattice distortions, composite wire stress and strain have been measured simultaneously in a high energy synchrotron beamline. A permanent Ic degradation of 5% occurs when the wire strain exceeds 0.60%. At a wire strain of about 0.65% a drastic n value and Ic reduction occur, and the composite stress and the Bi-2212 lattice parameter reach a plateau, indicating Bi-2212 filament fracturing. The XRD measurements show that Bi-2212 exhibits linear elastic behaviour up to the irreversible strain limit.

  14. Growth rate of YBCO-Ag superconducting single grains

    Science.gov (United States)

    Congreve, J. V. J.; Shi, Y. H.; Dennis, A. R.; Durrell, J. H.; Cardwell, D. A.

    2017-12-01

    The large scale use of (RE)Ba2Cu3O7 bulk superconductors, where RE=Y, Gd, Sm, is, in part, limited by the relatively poor mechanical properties of these inherently brittle ceramic materials. It is reported that alloying of (RE)Ba2Cu3O7 with silver enables a significant improvement in the mechanical strength of bulk, single grain samples without any detrimental effect on their superconducting properties. However, due to the complexity and number of inter-related variables involved in the top seeded melt growth (TSMG) process, the growth of large single grains is difficult and the addition of silver makes it even more difficult to achieve successful growth reliably. The key processing variables in the TSMG process include the times and temperatures of the stages within the heating profile, which can be derived from the growth rate during the growth process. To date, the growth rate of the YBa2Cu3O7-Ag system has not been reported in detail and it is this lacuna that we have sought to address. In this work we measure the growth rate of the YBCO-Ag system using a method based on continuous cooling and isothermal holding (CCIH). We have determined the growth rate by measuring the side length of the crystallised region for a number of samples for specified isothermal hold temperatures and periods. This has enabled the growth rate to be modelled and from this an optimized heating profile for the successful growth of YBCO-Ag single grains to be derived.

  15. Preparation and characterization of Ag-added Bi1⋅84Pb0 ...

    Indian Academy of Sciences (India)

    Unknown

    microscopy (SEM), electrical transport and a.c. susceptibility techniques. The tube ... high current conductor is high Jc. However, non-textured, porous structure with ... contact resistance studies on Ag added (0–25 wt%) Bi-. 2223 bulk tubes ...

  16. Lead-doped electron-beam-deposited Bi-Sr-Ca-Cu-O superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Agnihotry, S.A.; Saini, K.K.; Kant, C.; Sharma, C.P.; Ekbote, S.N.; Asthana, P.; Nagpal, K.C.; Chandra, S. (National Physical Lab., New Delhi (India))

    1991-03-20

    Superconducting thin films of the lead-doped Bi-Sr-Ca-Cu-O system have been prepared on (100) single-crystal SrTiO{sub 3} substrates by an electron beam deposition technique using a single sintered pellet as the evaporation source. As-deposited films are amorphous and non-superconducting; post-deposition annealing at an optimized temperature in air has been found to result in crystalline and superconducting films. The superconducting characteristics of the films have been observed to be sensitive not only to the duration and temperature of post-deposition annealing but also to the lead content and the sintering parameters for the pellet to be used as the evaporation source. A pellet with nominal composition Bi{sub 3}Pb{sub 1}Sr{sub 3}Ca{sub 3}Cu{sub 4}O{sub y} that had been sintered for 200 h zero resistivity Tc{sup 0}=112 K. However, films deposited using such a pellet as the evaporation source had Tc{sup 0} {approx equal} 73-78 K, as had the films deposited from a pellet without any lead. We investigated systematically films deposited from pellets with more lead and sintered for different durations. It is evident from these investigations that pellets with nominal composition Bi{sub 3}Pb{sub 2}Sr{sub 3}Ca{sub 3}Cu{sub 4}O{sub y}, i.e. with an excess of lead, and sintered for about 75 h when used as the evaporation source yield films with Tc{sup 0} {approx equal} 100 K when annealed between 835 and 840deg C for an optimized long duration. The films are characterized by X-ray diffraction and energy-dispersive spectroscopy techniques and have been found to be highly c axis oriented. The effect of lead in promoting a high Tc{sup 0}=110 K phase seems to be similar to that in bulk ceramics. (orig.).

  17. Cs2AgBiBr6 single-crystal X-ray detectors with a low detection limit

    Science.gov (United States)

    Pan, Weicheng; Wu, Haodi; Luo, Jiajun; Deng, Zhenzhou; Ge, Cong; Chen, Chao; Jiang, Xiaowei; Yin, Wan-Jian; Niu, Guangda; Zhu, Lujun; Yin, Lixiao; Zhou, Ying; Xie, Qingguo; Ke, Xiaoxing; Sui, Manling; Tang, Jiang

    2017-11-01

    Sensitive X-ray detection is crucial for medical diagnosis, industrial inspection and scientific research. The recently described hybrid lead halide perovskites have demonstrated low-cost fabrication and outstanding performance for direct X-ray detection, but they all contain toxic Pb in a soluble form. Here, we report sensitive X-ray detectors using solution-processed double perovskite Cs2AgBiBr6 single crystals. Through thermal annealing and surface treatment, we largely eliminate Ag+/Bi3+ disordering and improve the crystal resistivity, resulting in a detector with a minimum detectable dose rate as low as 59.7 nGyair s-1, comparable to the latest record of 0.036 μGyair s-1 using CH3NH3PbBr3 single crystals. Suppressed ion migration in Cs2AgBiBr6 permits relatively large external bias, guaranteeing efficient charge collection without a substantial increase in noise current and thus enabling the low detection limit.

  18. Simulation of transport critical current of Bi2223/Ag tape with ferromagnetic shielding

    International Nuclear Information System (INIS)

    Gu, C.; Alamgir, A.K.M.; Qu, T.M.; Han, Z.

    2008-01-01

    Ferromagnetic shielding (FS) was coated onto the surface of the Bi2223/Ag multi-filamentary tape. Transport critical current of the Bi2223/Ag multi-filamentary tape with a FS was systematically studied by numerical simulation. In the help of a finite element analysis (FEA) tool, we are able to understand how the FS alters the flux inside the superconductor region and thus increases and decreases the critical current density locally. The results show the open FS function both positively and negatively to the performance of the tape. An optimization process was proposed, aiming to reach a tradeoff between I c increasing and less usage of the ferromagnetic material. Three important shielding parameters, shielding width, shielding thickness, and shielding material were taken into account

  19. Simulation of transport critical current of Bi2223/Ag tape with ferromagnetic shielding

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China)], E-mail: guchen@tsinghua.edu.cn; Alamgir, A.K.M. [Faculty of Engineering, Yokohama National University, 75-9 Tokiwadai, Hodogaya, ku, Yokohama (Japan); Qu, T.M. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education (China); Han, Z. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China)

    2008-09-15

    Ferromagnetic shielding (FS) was coated onto the surface of the Bi2223/Ag multi-filamentary tape. Transport critical current of the Bi2223/Ag multi-filamentary tape with a FS was systematically studied by numerical simulation. In the help of a finite element analysis (FEA) tool, we are able to understand how the FS alters the flux inside the superconductor region and thus increases and decreases the critical current density locally. The results show the open FS function both positively and negatively to the performance of the tape. An optimization process was proposed, aiming to reach a tradeoff between I{sub c} increasing and less usage of the ferromagnetic material. Three important shielding parameters, shielding width, shielding thickness, and shielding material were taken into account.

  20. Fabrication of Ag-decorated BiOBr-mBiVO4 dual heterojunction composite with enhanced visible light photocatalytic performance for degradation of malachite green

    Science.gov (United States)

    Regmi, Chhabilal; Dhakal, Dipesh; Kim, Tae-Ho; Yamaguchi, Takutaro; Wohn Lee, Soo

    2018-04-01

    A visible light active Ag-decorated BiVO4-BiOBr dual heterojunction photocatalyst was prepared using a facile hydrothermal method, followed by the photodeposition of Ag. The photocatalytic activity of the synthesized samples was investigated by monitoring the change in malachite green (MG) concentration upon visible light irradiation. The synthesized sample was highly effective for the degradation of non-biodegradable MG. The enhanced activity observed was ascribed to the efficient separation and transfer of charge carriers across the dual heterojunction structure as verified by photoluminescence measurements. The removal of MG was primarily initiated by hydroxyl radicals and holes based on scavenger’s effect. To gain insight into the degradation mechanism, both high performance liquid chromatography and high resolution-quantitative time of flight, electrospray ionization mass spectrometry measurements during the degradation process were carried out. The degradation primarily followed the hydroxylation and N-demethylation process. A possible reaction pathway is proposed on the basis of all the information obtained under various experimental conditions.

  1. A review of Pb-Sb(As-S, Cu(Ag-Fe(Zn-Sb(As-S, Ag(Pb-Bi(Sb-S and Pb-Bi-S(Te sulfosalt systems from the Boranja orefield, West Serbia

    Directory of Open Access Journals (Sweden)

    Radosavljević Slobodan A.

    2016-01-01

    Full Text Available Recent mineralogical, chemical, physical, and crystallographic investigations of the Boranja orefield showed very complex mineral associations and assemblages where sulfosalts have significant role. The sulfosalts of the Boranja orefield can be divided in four main groups: (i Pb-Sb(As-S system with ±Fe and ±Cu; (ii Cu(Ag-Fe(Zn-Sb(As-S system; (iii Ag(Pb-Bi(Sb-S; (iv and Pb-Bi-S(Te system. Spatially, these sulfosalts are widely spread, however, they are the most abundant in the following polymetallic deposits and ore zones: Cu(Bi-FeS Kram-Mlakva; Pb(Ag-Zn-FeS2 Veliki Majdan (Kolarica-Centralni revir-Kojići; Sb-Zn-Pb-As Rujevac; and Pb-Zn-FeS2-BaSO4 Bobija. The multi stage formation of minerals, from skarnhydrothermal to complex hydrothermal with various stages and sub-stages has been determined. All hydrothermal stages and sub-stages of various polymetallic deposits and ore zones within the Boranja orefield are followed by a variety of sulfosalts. [Projekat Ministarstva nauke Republike Srbije, br. OI-176016: Magmatism and geodynamics of the Balkan Peninsula from Mesozoic to present day: Significance for the formation of metallic and non-metallic mineral deposits

  2. Interfacial properties of the enhanced visible-light plasmonic Ag/Bi{sub 2}WO{sub 6} (0 0 1) nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Fang [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Chengdu 610500 (China); Cao, Kun; Wu, Yi [The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Chengdu 610500 (China); Zhang, Kun-Hao [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China); Zhou, Ying, E-mail: yzhou@swpu.edu.cn [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Chengdu 610500 (China)

    2016-01-01

    Graphical abstract: - Highlights: • The parallel adsorption of silver on Bi{sub 2}WO{sub 6} (0 0 1) makes energetically favorable configurations. The positive charged Ag cluster may act as excited electron traps. • New isolated levels appear above the valence bands due to the hybridization of Ag 5s and O 2p, and they become dispersed as Ag content increases. This is responsible for the improved visible-light response. • Optical spectra confirm obvious red-shifts of the absorption edge with the increment of silver content, which enhances efficiently the photocatalytic activity of Bi{sub 2}WO{sub 6} (0 0 1). - Abstract: First principle calculations are performed to study the interfacial photoelectric properties of Ag{sub n}/Bi{sub 2}WO{sub 6} (0 0 1) (n = 1, 2, 3, 4) hybrid photocatalyst. The parallel adsorption of Ag cluster leads to more energetic favorable structures due to stronger interfacial interactions. The positive charged Ag cluster may act as excited electron traps and facilitate the electron–hole separation. In particular, hybridization between Ag 5s and O 2p leads to the formation of isolated energy levels above the valence bands, and they become more dispersed with broader bandwidth with the increment of silver cluster size, which is responsible for the enhanced absorption in visible-light region. In the deep valence region, Ag 4d orbital turns more delocalized and hybrid with O 2p states as the cluster size increases, which contributes to more covalent bond feature of Ag–O. Moreover, optical spectra demonstrate obvious red-shifts of the absorption edge with the increment of silver content, which enhances efficiently the visible-light photocatalytic activities of Bi{sub 2}WO{sub 6} (0 0 1). The study provides insights into the enhanced photocatalyic mechanism of Ag/Bi{sub 2}WO{sub 6} (0 0 1) and aids in the design of noble metal loaded visible-light plasmonic photocatalyst.

  3. Light regulated I–V hysteresis loop of Ag/BiFeO{sub 3}/FTO thin film

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Lujun; Sun, Bai; Zhao, Wenxi; Li, Hongwei; Chen, Peng, E-mail: pchen@swu.edu.cn

    2017-01-30

    A hysteresis loop of current–voltage characteristics based multiferroic BiFeO{sub 3} nanoribbons memory device is observed. Moreover, the white-light can greatly regulate both the current–voltage hysteresis loop and the ferroelectric hysteresis loop. The stored space charges within the electrodes/BiFeO{sub 3} interface can lead to hysteresis-type I–V characteristics of Ag/BiFeO{sub 3}/FTO devices. The white-light controlled I–V loop and ferroelectric loop result from photon-generated carries. Since the I–V hysteresis loop and ferroelectric hysteresis loop have a potential application prospect to the memory devices, these two white-light controlled the hysteresis loops curves are likely to provide promising opportunity for developing the multi-functional memory devices.

  4. Microstructure and phase evolution during the dealloying of bi-phase Al–Ag alloy

    International Nuclear Information System (INIS)

    Song, T.T.; Gao, Y.L.; Zhang, Z.H.; Zhai, Q.J.

    2013-01-01

    Highlights: ► Selective leaching of α-Al(Ag) and Ag 2 Al occurs simultaneously during dealloying. ► Diffusion of Al and vacancy controlled mechanism dominate the etching of Ag 2 Al. ► The coarsening of ligaments in NPS follows a time dependence of d ∝t 2/5 . - Abstract: The chemical dealloying of bi-phase Al-35Ag alloy has been investigated within the parting limit. The dealloying of α-Al(Ag) and Ag 2 Al commenced simultaneously, and all α-Al(Ag) and part of Ag 2 Al were dealloyed, leaving residual Ag 2 Al to be dealloyed afterwards. The dealloying of the residual Ag 2 Al is associated with vacancy controlled mechanism and diffusion of Al atoms. It is revealed that the diffusions of the Al and Ag atoms during dealloying are significant. The Ag skeletons formed at the initial stage, and became coarsened gradually with a time dependence of d ∝t 2/5 , illustrating the vital role of diffusion of Ag atoms.

  5. Laser soldering of Sn-Ag-Cu and Sn-Zn-Bi lead-free solder pastes

    Science.gov (United States)

    Takahashi, Junichi; Nakahara, Sumio; Hisada, Shigeyoshi; Fujita, Takeyoshi

    2004-10-01

    It has reported that a waste of an electronics substrate including lead and its compound such as 63Sn-37Pb has polluted the environment with acid rain. For that environment problem the development of lead-free solder alloys has been promoted in order to find out the substitute for Sn-Pb solders in the United States, Europe, and Japan. In a present electronics industry, typical alloys have narrowed down to Sn-Ag-Cu and Sn-Zn lead-free solder. In this study, solderability of Pb-free solder that are Sn-Ag-Cu and Sn-Zn-Bi alloy was studied on soldering using YAG (yttrium aluminum garnet) laser and diode laser. Experiments were peformed in order to determine the range of soldering parameters for obtaining an appropriate wettability based on a visual inspection. Joining strength of surface mounting chip components soldered on PCB (printed circuit board) was tested on application thickness of solder paste (0.2, 0.3, and 0.4 mm). In addition, joining strength characteristics of eutectic Sn-Pb alloy and under different power density were examined. As a result, solderability of Sn-Ag-Cu (Pb-free) solder paste are equivalent to that of coventional Sn-Pb solder paste, and are superior to that of Sn-Zn-Bi solder paste in the laser soldering method.

  6. Strain reduced critical current in Bi-2223/Ag superconductors under axial tension and compression

    International Nuclear Information System (INIS)

    Haken, B. ten; Godeke, A.; Kate, H.H.J. ten

    1997-01-01

    The critical current of Ag sheathed Bi(Pb)SrCaCuO-2223 tape conductors is investigated as a function of various strain components. A reduction of the critical current occurs due to both tensile or a compressive strain. The critical current reduction is qualitatively similar with the results as observed in Bi-2212 conductors. An axial compression leads to an immediate critical current reduction. The critical current in an axially elongated sample remains nearly constant up to a certain limit typically close to 0.3% strain. For a larger elongation the critical current reduces rapidly. A transverse pressure acting on the tape surface leads also to an irreversible critical current reduction. This behavior is compared with the influence of an axial compression with an effective Young's modulus. The deformation induced critical current reductions in Bi-2223 conductors can be described by a model that is already proposed for Bi-2212 conductors. This model is based on the irreversible nature of the critical current reduction due to a certain deformation

  7. Martensitic transformation behavior in Ti–Ni–X (Ag, In, Sn, Sb, Te, Tl, Pb, Bi) ternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jai-young; Chun, Su-jin; Kim, Nam-suk; Cho, Jeung-won; Kim, Jae-hyun [School of Materials Science and Engineering, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Yeom, Jong-taek [Light Metal Division, Korea Institute of Materials Science (KIMS), Changwon 642-831 (Korea, Republic of); Kim, Jae-il [Materials Science and Engineering, University of Dong-A, Hadan-dong, Saha-gu, Busan 604-714 (Korea, Republic of); Nam, Tae-hyun, E-mail: tahynam@gnu.ac.kr [School of Materials Science and Engineering, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of)

    2013-12-15

    Graphical abstract: - Highlights: • Ag, In and Sn were soluble in TiNi matrix, while Sb, Te, Tl, Pb and Bi were not. • The B2-R-B19′transformation occurred in Ti-Ni-(Ag, In, Sn) alloys. • Solid solution hardening was essential for inducing the B2-R transformation. - Abstract: The microstructures and transformation behaviors of Ti–Ni–X (Ag, In, Sn, Sb, Te, Tl, Pb, Bi) ternary alloys were investigated using electron probe micro-analysis (EPMA), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Micro Vickers hardness tests. All specimens consisted of Ti–Ni matrices and second phase particles. Ag, In and Sn were soluble in Ti–Ni matrices with a limited solubility (≤1.0 at%), while Sb, Te, Tl, Pb and Bi were not soluble. Two-stage B2-R-B19′ transformation occurred in Ti–48.8Ni–1.2Ag, Ti–49.0Ni–1.0In and Ti–49.0Ni–1.0Sn alloys, while one-stage B2-B19′ transformation occurred in Ti–49.0Ni–1.0Ag, Ti–49.0Ni–1.0Sb, Ti–49.0Ni–1.0Te, Ti–49.0Ni–1.0Pb and Ti–49.0Ni–1.0Bi alloys. Micro Vickers hardness of the alloys displaying the B2-R-B19′ transformation (Hv 250–368) was much larger than that (

  8. Martensitic transformation behavior in Ti–Ni–X (Ag, In, Sn, Sb, Te, Tl, Pb, Bi) ternary alloys

    International Nuclear Information System (INIS)

    Jang, Jai-young; Chun, Su-jin; Kim, Nam-suk; Cho, Jeung-won; Kim, Jae-hyun; Yeom, Jong-taek; Kim, Jae-il; Nam, Tae-hyun

    2013-01-01

    Graphical abstract: - Highlights: • Ag, In and Sn were soluble in TiNi matrix, while Sb, Te, Tl, Pb and Bi were not. • The B2-R-B19′transformation occurred in Ti-Ni-(Ag, In, Sn) alloys. • Solid solution hardening was essential for inducing the B2-R transformation. - Abstract: The microstructures and transformation behaviors of Ti–Ni–X (Ag, In, Sn, Sb, Te, Tl, Pb, Bi) ternary alloys were investigated using electron probe micro-analysis (EPMA), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Micro Vickers hardness tests. All specimens consisted of Ti–Ni matrices and second phase particles. Ag, In and Sn were soluble in Ti–Ni matrices with a limited solubility (≤1.0 at%), while Sb, Te, Tl, Pb and Bi were not soluble. Two-stage B2-R-B19′ transformation occurred in Ti–48.8Ni–1.2Ag, Ti–49.0Ni–1.0In and Ti–49.0Ni–1.0Sn alloys, while one-stage B2-B19′ transformation occurred in Ti–49.0Ni–1.0Ag, Ti–49.0Ni–1.0Sb, Ti–49.0Ni–1.0Te, Ti–49.0Ni–1.0Pb and Ti–49.0Ni–1.0Bi alloys. Micro Vickers hardness of the alloys displaying the B2-R-B19′ transformation (Hv 250–368) was much larger than that (< Hv 200) of the alloys displaying the B2-B19′ transformation. Solid solution hardening was an important factor for inducing the B2-R transformation in Ti–Ni–X (X = non-transition elements) alloys

  9. Efficient degradation of tetrabromobisphenol A by heterostructured Ag/Bi5Nb3O15 material under the simulated sunlight irradiation

    International Nuclear Information System (INIS)

    Guo, Yingna; Chen, Ling; Ma, Fengyan; Zhang, Shengqu; Yang, Yuxin; Yuan, Xing; Guo, Yihang

    2011-01-01

    Heterostructured metallic silver-layered bismuth niobate two-component system (Ag/Bi 5 Nb 3 O 15 ) was developed for the first time by a mild hydrothermal method combined with photodeposition. The Ag/Bi 5 Nb 3 O 15 exhibited single-crystalline orthorhombic structure with small particle size (50-200 nm) and octahedral as well as sheet-like shape; additionally, it possessed photoresponse in both UV and visible region. As a novel alternative photocatalysts to TiO 2 , the photocatalytic activity of the Ag/Bi 5 Nb 3 O 15 was evaluated by the degradation of tetrabromobisphenol A, a member from the family of the brominated flame retardant, under solar simulating Xe lamp irradiation, and enhanced photocatalytic activity in compared to Bi 5 Nb 3 O 15 itself and Degussa P25 was obtained.

  10. Three-dimensional Ag2O/Bi5O7I p-n heterojunction photocatalyst harnessing UV-vis-NIR broad spectrum for photodegradation of organic pollutants.

    Science.gov (United States)

    Chen, Yannan; Zhu, Gangqiang; Hojamberdiev, Mirabbos; Gao, Jianzhi; Zhu, Runliang; Wang, Chenghui; Wei, Xiumei; Liu, Peng

    2018-02-15

    Ag 2 O nanoparticles-loaded Bi 5 O 7 I microspheres forming a three dimensional Ag 2 O/Bi 5 O 7 I p-n heterojunction photocatalyst with wide-spectrum response were synthesized in this study. The results of transmission electron microscopy observations revealed that the Ag 2 O nanoparticles with the diameter of ca. 10-20nm were distributed on the surfaces of Bi 5 O 7 I nanosheets. The as-synthesized Ag 2 O/Bi 5 O 7 I exhibited an excellent wide-spectrum response to wavelengths ranging from ultraviolet (UV) to near-infrared (NIR), indicating its potential for effective utilization of solar energy. Compared with pure Bi 5 O 7 I, the Ag 2 O/Bi 5 O 7 I composite also demonstrated excellent photocatalytic activity for the degradation of Bisphenol A and phenol in aqueous solution under visible LED light irradiation. Among samples, the 20% Ag 2 O/Bi 5 O 7 I composite photocatalyst showed the highest photocatalytic activity for the degradation of Bisphenol A and phenol in aqueous solution. In addition, the 20% Ag 2 O/Bi 5 O 7 I composite also exhibited a photocatalytic activity for the degradation of Bisphenol A under NIR light irradiation. The improved photocatalytic activity is attributed to the formation of a p-n heterojunction between Ag 2 O and Bi 5 O 7 I, allowing the efficient utilization of solar energy (from UV to NIR) and high separation efficiency of photogenerated electron-hole pairs. The present work is desirable to explore a possible avenue for the full utilization of solar energy. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Electrical and thermal characteristics of Bi2212/Ag HTS coils for conduction-cooled SMES

    Science.gov (United States)

    Hayakawa, N.; Noguchi, S.; Kurupakorn, C.; Kojima, H.; Endo, F.; Hirano, N.; Nagaya, S.; Okubo, H.

    2006-06-01

    In this paper, we investigated the electrical and thermal performance of conduction-cooled Bi2212/Ag HTS coils with 4K-GM cryocooler system. First, we measured the critical current Ic for different ambient temperatures T0 at 4.2 K - 40 K. Experimental results revealed that Ic increased with the decrease in T0 and was saturated at T0 account of temperature dependence of specific heat and thermal conductivity of the materials. We also measured the temperature rise of Bi2212/Ag HTS coil for different continuous current levels at T0 = 4.8 K. Experimental results revealed the criterion of thermal runaway, which was discussed in terms of heat generation and propagation in the test coil.

  12. Enhanced photocatalytic activity and characterization of magnetic Ag/BiOI/ZnFe2O4 composites for Hg0 removal under fluorescent light irradiation

    Science.gov (United States)

    Li, Chengwei; Zhang, Anchao; Zhang, Lixiang; Song, Jun; Su, Sheng; Sun, Zhijun; Xiang, Jun

    2018-03-01

    A series of magnetic Ag/BiOI/ZnFe2O4 hybrids synthesized via hydrothermal process, subsequent deposition-precipitation and photoreduction method were employed to remove elemental mercury (Hg0) under fluorescent light irradiation. The effects of Ag content, fluorescent light irradiation, reaction temperature, pH value, flue gas composition, anions and photocatalyst dosage on Hg0 removal were investigated in detail. The as-synthesized photocatalysts were characterized using N2 adsorption-desorption, XRD, SEM, TEM, HRTEM, XPS, VSM, DRS, ESR, PL and photocurrent response. The results showed that the ternary Ag/BiOI/ZnFe2O4 hybrids possessed enhanced visible-light-responsive photocatalytic performances for Hg0 removal. Ag/BiOI/ZnFe2O4 photocatalyst could be easily recovered from the reaction solution by an extra magnet and was stable in the process of Hg0 removal. Lower content of Ag was highly dispersed on the surface of BiOI/ZnFe2O4, while higher content of Ag would result in some aggregations and/or the blockages of micropore. In comparison to BiOI/ZnFe2O4, Ag deposited BiOI/ZnFe2O4 material showed lower recombination rate of electron-hole pairs. The superior Hg0 oxidation removal could correspond to good match of BiOI and ZnFe2O4, excellent fluidity and surface plasmon resonance effect of Ag0 nanoparticles, which led to higher separation efficiency of photogenerated electrons and holes, thereby enhancing the hybrids' photocatalytic activity.

  13. Novel phenomenon of magnetism and superconductivity in Fe-doped superconductor Bi{sub 4-x}Fe{sub x}O{sub 4}S{sub 3} (0 ≤ x ≤ 0.1)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qing [Shanghai University, Department of Physics, Shanghai (China); Shanghai University, Materials Genome Institute, Shanghai (China); Wang, Difei; Yu, Chuan; Yin, Xunqing; Kang, Jian; Cheng, Cheng; Deng, Dongmei; Jing, Chao [Shanghai University, Department of Physics, Shanghai (China); Feng, Zhenjie; Cao, Shixun; Zhang, Jincang [Shanghai University, Department of Physics, Shanghai (China); Shanghai University, Materials Genome Institute, Shanghai (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai (China); Chu, Hao [California Institute of Technology, Department of Applied Physics, Pasadena, CA (United States); Li, Xiaolong [Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai (China)

    2017-06-15

    We report the effects of Fe doping on the BiS{sub 2}-based superconductor Bi{sub 4}O{sub 4}S{sub 3}. It has been found that the superconducting transition temperature (T{sub C}{sup onset}) is slightly enhanced by Fe doping. The magnetic susceptibility results reveal the coexistence of superconductivity and long-range ferrimagnetism in these samples. A new magnetic transition temperature T{sub V} (Verwey transition) from the M-T curves at ∝112 K is observed. The isothermal magnetization curves (M-H) indicate a weak ferrimagnetism, which is probably due to the antiparallel ordering of Fe{sup 2+} and Fe{sup 3+} magnetic moments. The coexistence of superconductivity and ferro/ferrimagnetism makes bismuth oxysulfide superconductor a platform for understanding superconductivity from a new perspective. (orig.)

  14. Electronic structure of superconducting Bi2212 crystal by angle resolved ultra violet photoemission

    International Nuclear Information System (INIS)

    Saini, N.L.; Shrivastava, P.; Garg, K.B.

    1993-01-01

    The electronic structure of a high quality superconducting Bi 2 Sr 2 CaCu 2 Osub(8+δ) (Bi2212) single crystal is studied by angle resolved ultra violet photoemission (ARUPS) using He I (21.2 eV). Our results appear to show two bands crossing the Fermi level in ΓX direction of the Brillouin zone as reported by Takahashi et al. The bands at higher binding energy do not show any appreciable dispersion. The nature of the states near the Fermi level is discussed and the observed band structure is compared with the band structure calculations. (author)

  15. Superconductivity and magnetic order in the noncentrosymmetric half-Heusler compound ErPdBi

    NARCIS (Netherlands)

    Pan, Y.; Nikitin, A.M.; Bay, T.V.; Huang, Y.K.; Paulsen, C.; Yan, B.H.; de Visser, A.

    2013-01-01

    We report superconductivity at Tc = 1.22 K and magnetic order at TN = 1.06\\ K in the semimetallic noncentrosymmetric half-Heusler compound ErPdBi. The upper critical field, Bc2, has an unusual quasi-linear temperature variation and reaches a value of 1.6 T for T - 0 . Magnetic order is found below

  16. Creep Behavior of a Sn-Ag-Bi Pb-Free Solder

    Science.gov (United States)

    Vianco, Paul; Rejent, Jerome; Grazier, Mark; Kilgo, Alice

    2012-01-01

    Compression creep tests were performed on the ternary 91.84Sn-3.33Ag-4.83Bi (wt.%, abbreviated Sn-Ag-Bi) Pb-free alloy. The test temperatures were: −25 °C, 25 °C, 75 °C, 125 °C, and 160 °C (± 0.5 °C). Four loads were used at the two lowest temperatures and five at the higher temperatures. The specimens were tested in the as-fabricated condition or after having been subjected to one of two air aging conditions: 24 hours at either 125 °C or 150 °C. The strain-time curves exhibited frequent occurrences of negative creep and small-scale fluctuations, particularly at the slower strain rates, that were indicative of dynamic recrystallization (DRX) activity. The source of tertiary creep behavior at faster strain rates was likely to also be DRX rather than a damage accumulation mechanism. Overall, the strain-time curves did not display a consistent trend that could be directly attributed to the aging condition. The sinh law equation satisfactorily represented the minimum strain rate as a function of stress and temperature so as to investigate the deformation rate kinetics: dε/dtmin = Asinhn (ασ) exp (−ΔH/RT). The values of α, n, and ΔH were in the following ranges (±95% confidence interval): α, 0.010–0.015 (±0.005 1/MPa); n, 2.2–3.1 (±0.5); and ΔH, 54–66 (±8 kJ/mol). The rate kinetics analysis indicated that short-circuit diffusion was a contributing mechanism to dislocation motion during creep. The rate kinetics analysis also determined that a minimum creep rate trend could not be developed between the as-fabricated versus aged conditions. This study showed that the elevated temperature aging treatments introduced multiple changes to the Sn-Ag-Bi microstructure that did not result in a simple loss (“softening”) of its mechanical strength.

  17. Study of interfacial reactions in Sn-3.5Ag-3.0Bi and Sn-8.0Zn-3.0Bi sandwich structure solder joint with Ni(P)/Cu metallization on Cu substrate

    International Nuclear Information System (INIS)

    Sun, Peng; Andersson, Cristina; Wei, Xicheng; Cheng, Zhaonian; Shangguan, Dongkai; Liu, Johan

    2007-01-01

    In this paper, the coupling effect in Sn-3.5Ag-3.0Bi and Sn-8.0Zn-3.0Bi solder joint with sandwich structure by long time reflow soldering was studied. It was found that the interfacial compound at the Cu substrate was binary Cu-Sn compound in Sn-Ag-Bi solder joint and Cu 5 Zn 8 phase in Sn-Zn-Bi solder joint. The thickness of the Cu-Zn compound layer formed at the Cu substrate was greater than or equal to that of Cu-Sn compound layer, although the reflow soldering temperature of Sn-Zn-Bi (240 o C) was lower than that of Sn-Ag-Bi (250 o C). The stable Cu-Zn compound was the absolute preferential phase in the interfacial layer between Sn-Zn-Bi and the Cu substrate. The ternary (Cu, Ni) 6 Sn 5 compound was formed at the Sn-Ag-Bi/Ni(P)-Cu metallization interface, and a complex alloy Sn-Ni-Cu-Zn was formed at the Sn-Zn-Bi/Ni(P)-Cu metallization interface. It was noted that Cu atoms could diffuse from the Cu substrate through the solder matrix to the Ni(P)-Cu metallization within 1 min reflow soldering time for both solder systems, indicating that just 30 s was long enough for Cu to go through 250 μm diffusion length in the Sn-Ag-Bi solder joint at 250 o C. The coupling effect between Ni(P)/Cu metallization and Cu substrate was confirmed as the type of IMCs at Ni(P) layer had been changed from Ni-Sn system to Cu-Sn system apparently by the diffusion effect of Cu atoms. The (Cu, Ni) 6 Sn 5 layer at the Ni(P)/Cu metallization grew significantly and its thickness was even greater than that of the Cu-Sn compound on the opposite side, however the growth of the complex alloy including Sn, Ni, Cu and Zn on the Ni(P)/Cu metallization was suppressed

  18. Growth of superconducting Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+//sub x/ films on alumina, silicon, and fused quartz

    International Nuclear Information System (INIS)

    Hung, L.S.; Agostinelli, J.A.; Paz-Pujalt, G.R.; Mir, J.M.

    1988-01-01

    Interactions between superconducting Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+//sub x/ films and substrates were investigated by ion backscattering, x-ray diffraction, and four-point probe resistivity measurements. During annealing at temperatures above- 800 /sup 0/C, Bi/sub 2/Sr/sub 2/CaCu/sub 2/ oxide films rapidly reacted with alumina, Si, Si covered with SiO/sub 2/, and quartz, resulting in catastrophic failure. Zr-based barrier layers were used to minimize film-substrate interactions. When a single ZrO/sub 2/ layer was interposed between the superconducting oxide film and the underlying substrate, the Bi/sub 2/Sr/sub 2/CaCu/sub 2/ oxide films showed a large-grained polycrystalline microstructure and exhibited the orthorhombic structure. Films on sapphire showed transitions to the superconducting state beginning near 100 K with zero resistance achieved at 70 K. Films on Si and thermally grown SiO/sub 2/ showed a similar drop in resistance around 95 K, whereas the transition was broad and the zero resistance state was not reached. For films on quartz, high thermal stress caused cracking of the superconducting oxide film. Best results were achieved using a barrier composed of a Zr-Si-O mixed layer underneath ZrO/sub 2/. In this case, the films grown on Si and quartz were uniform and showed the onset to superconductivity at 95 K, attaining zero resistance at 70 K

  19. Synthesis, structure and superconductivity in Ba1-xKxBiO3

    International Nuclear Information System (INIS)

    Hinks, D.G.

    1989-01-01

    Ba 1-x K x BiO 3 (with x = 0.4) has the highest T c (30 K) of any copperless compound. The superconducting transition temperature of this material is expected to be at the limit of conventional electron-phonon coupling. Since this material is much simpler than the copper containing high-T c superconductors (it is cubic in its superconducting state and only sp electrons are involved in the transport properties), it should be much easier to unravel the nature of the superconducting pairing mechanism in this system. Understanding this system may help explain superconductivity in the more complex copper-oxide materials. In this paper, the authors report on the development of a synthesis method which allows the preparation of stoichiometric, single-phase materials with x between 0.0 and 0.5. The structural phase diagram was determined using powder neutron diffraction as a function of both composition and temperature. Superconductivity only occurs in the cubic perovskite phase which is stable for x larger than 0.3. At a x = 0.3 composition the material undergoes a semiconductor to metal transition with a maximum value for T c . As the K content is further increased, T c is reduced

  20. Conductivity and superconductivity of (Bi,Pb)-Sr-Ca-Cu-O

    International Nuclear Information System (INIS)

    Gazda, M.; Kusz, B.; Klimczuk, T.; Natali, R.; Stizza, S.

    2007-01-01

    The (Bi,Pb)-Sr-Ca-Cu-O glass-ceramics may be considered as disordered metal and superconductor. Depending on the heat treatment conditions the materials are either composed of the oval grains of the 2212 or 2201 phases embedded in the insulating matrix or they mainly contain the 2212 plate-like crystallites weakly connected one with another. The materials have large resistivity and usually large negative temperature coefficient of resistivity (TCR). The granular and disordered character of the materials is also reflected in their superconducting properties. Both the normal-state and superconducting properties correlate one with another. The glass-ceramic samples were obtained by annealing the amorphous solid at temperatures between 840 and 860 deg. C. The measurements of the temperature dependence of resistivity in annealed samples were carried out with the conventional four-terminal method in a temperature range from 3 to 300 K

  1. A jelly-roll process for high temperature superconducting tapes and wires

    International Nuclear Information System (INIS)

    Tsuei, C.C.; Chi, C.C.; Frey, T.; Mitzi, D.B.; Kazyaka, T.; Haugan, T.; Ye, J.; Patel, S.; Shaw, D.T.; Wu, M.K.

    1992-01-01

    As an alternative to the powder-in-tube method, a new technique called the jelly-roll process is proposed for making high-T c superconducting tapes and wires. A normal-metal sheet coated with high-T c cuprate is configured in a jelly-roll fashion and cold worked into tapes or wires made of alternating cuprate superconductor and normal metal layers. The feasibility of this new process is demonstrated for both the YBa 2 Cu 3 O 7 /Ag and Bi 2 Sr 2 CaCu 2 O 8 /Ag composite systems. The role of reduction in the cross-sectional area by cold-rolling, heat treatment and oxygenation in optimizing T c and J c has been studied. Preliminary results indicate that partialmelt texturing, in the Bi 2 Sr 2 CaCu 2 O 8 /Ag system, results in a relatively field independent J c (H c (H = 0) ∝5 X 10 4 A cm -2 at 4.2 K

  2. Composite superconducting wires produced by rapid coating in Bi-Sr-Ca-Cu-O metal oxide system

    International Nuclear Information System (INIS)

    Grozav, A.D.; Konopko, L.A.; Leoporda, N.I.

    1989-01-01

    Method for producing superconducting composite wires by dip coating of copper wires in metal-oxide BiSrCaCu 2 O x melt is developed. The thickness of the coating is regulated by the change of dip rate, melt viscosity and by the number of passages through the melt. Wire annealing at 700-800 deg C leads to the production of two phases, one of them being superconducting with T c =80K

  3. Self-field AC losses in Bi-2223 superconducting tapes

    International Nuclear Information System (INIS)

    Mueller, K. H.; Leslie, K.E.

    1996-01-01

    Full text: The self-field AC loss in Bi-2223 silver sheathed tapes for AC currents of up to 100 A was measured at 77 K and frequencies of 60 Hz and 600 Hz using a lock-in amplifier. The frequency dependence indicated a purely hysteretic loss which can be well described in terms of the critical state model for a flat superconducting strip. The only parameter needed to predict the self-field AC loss is the critical current of the critical state. Because the loss voltage is extremely small compared with the inductive voltage, a very high accuracy of the lock-in amplifier phase setting is required. Unlike in loss measurements on cylindrical superconducting samples, in the case of the tape the measuring circuit leads have to be brought out from the surface forming a loop where the changing magnetic field induces an additional voltage. Only if the loop formed by the leads at the voltage tabs is large enough will the apparent power dissipation approach the real AC loss associated with the length of the sample probed

  4. Superconducting properties of Pb nanoislands on Pb/Ag/Si(111) studied by a "3He-cooled scanning tunnelling microscope in magnetic fields at variable temperatures

    International Nuclear Information System (INIS)

    Leon Vanegas, Alvaro Augusto

    2015-01-01

    A "3He-cooled scanning tunneling microscope was used to investigate the superconducting properties of Pb single layers on Si(111) and Ag/Si(111) and Pb islands on Pb/Ag/Si(111) at temperatures between 0.38 K and 6 K and in magnetic fields of up to 3 T. The spectroscopy measurements show that in contrast with Pb/Si(111), a single Pb layer on Ag/Si(111) is non-superconducting. The superconductivity of Pb islands on Pb/Ag/Si(111) was characterized as a function of temperature and magnetic field. A non-uniform critical magnetic field for suppression of superconductivity on islands of uniform thickness but sitting of regions of different height is reported. The proximity induced superconductivity on the wetting layer surrounding a Pb island on Pb/Ag/Si(111) was studied. Spatially resolved, magnetic field dependent spectroscopy uncovers a non-trivial reduction of the extension of the induced superconductivity with increasing field. A breakdown of the proximity effect for fields larger than 0.5 T is found. Tunneling spectroscopy reveals a strong decrease of the proximity length with increasing temperature. This is ascribed to the thermally induced broadening of the electronic density of states in the tip used in the STM experiment.

  5. Environment dependent enhanced photoluminescence and Boolean logic gates like behavior of Bi2O3 and Ag:Bi2O3 nanostructures

    Science.gov (United States)

    Hariharan, S.; Karthikeyan, B.

    2018-03-01

    In the evolution of nanotechnology research for smart and precise sensor fabrication, here we report the implementation of simple logic gate operations performing by luminescent nanostructures in biomolecule environment based on photoluminescence (PL) technique. This present work deals with the luminescence property of α-Bi2O3 and Ag modified α-Bi2O3 nanostructures for D-glucose and Bovine serum albumin (BSA) sensing applications. These nanostructures are prepared by simple co-precipitation method and their morphology are examined using transmission electron microscope (TEM). We explore the PL characteristics of the prepared nanostructures and observe their change in PL intensity in the presence of D-glucose and BSA molecules. Enhancement in PL intensity is observed in the presence of D-glucose and BSA. Based on the PL response of prepared nanostructures in the biomolecule environment, we demonstrate biophotonic logic gates including YES, PASS 0, OR and INHIBIT gates.

  6. Controlled synthesis of Fe{sub 2}O{sub 3} modified Ag-{sub 010}BiVO{sub 4} heterostructures with enhanced photoelectrochemical activity toward the dye degradation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Junqi, E-mail: sfmlab@163.com; Zhou, Jian; Hao, Hongjuan; Li, Weijie

    2017-03-31

    Highlights: • Z-scheme system and n-n heterogeneous were constructed on the (010) and (110) facet. • The n-n-Z system realizes the wide absorption range, high charge-separation and strong redox ability. • The PEC performance of the Fe{sub 2}O{sub 3} modified Ag-BiVO{sub 4} was enhanced than that of the pure BiVO{sub 4}. - Abstract: Crystal facet dependence is an important approach for optimizing the performance of photocatalyst. In consideration that there is a close correlation between the photoelectric conversion efficiencies and crystal facet, the monoclinic bismuth vanadate (m-BiVO{sub 4}) with (010) and (110) crystal facets has drawn attention. We designed the Ag nanoparticles modified the (010) facet of the BiVO{sub 4} (Ag-{sub 010}BiVO{sub 4}) and then the Ag-{sub 010}BiVO{sub 4} heterogeneous nanostructure was modified by the Fe{sub 2}O{sub 3} nanoparticles. In the Fe{sub 2}O{sub 3} modified Ag-{sub 010}BiVO{sub 4}, the (110) facet of the BiVO{sub 4} was only modified by the Fe{sub 2}O{sub 3} nano-particles to construct the n-n heterojunction structure. Simultaneously, the Z-scheme system was fabricated on the (010) facet of the BiVO{sub 4}, where was modified by the Ag and Fe{sub 2}O{sub 3} nano-particles. We investigated its photoelectrochemical (PEC) and photocatalytic activities by the measurement of the electrochemical performance and degradation of methyl orange (MO). The Ag species in the system is only treated as the solid state electron mediator. As was expected, the Fe{sub 2}O{sub 3} modified Ag-{sub 010}BiVO{sub 4} heterojunction structure exhibited the highest photocurrent density and the smallest impedance. Besides, the Fe{sub 2}O{sub 3} modified Ag-{sub 010}BiVO{sub 4} heterojunction structure exhibited excellent redox ability and the MO could be degraded 92% after 150 min. It is worth noting that the outstanding performance should be attributed to the synergistic effect of n-n and Z-scheme system in the different facets, which

  7. Structure and superconductivity in (Bi{sub 0.35}Cu{sub 0.65})Sr{sub 2}YCu{sub 2}O{sub 7} and related materials

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, R.A.; Williams, S.P.; Greaves, C. [Univ. of Birmingham (United Kingdom)

    1994-12-31

    The recently reported (Bi/Cu)Sr{sub 2}YCu{sub 2}O{sub 7} phase has been studied by time of flight powder neutron diffraction. The proposed 1212 structure has been confirmed and refinements have shown the oxygen in the (Bi/Cu)O layer is displaced by 0.78{angstrom} from the ideal (1/2,1/2,0) site (P4/mmm space group) along (100). Bond Valence Sum calculations have suggested oxidation states of Bi{sup 5+} and Cu{sup 2+} for the cations in the (Bi/Cu)O layers. The material is non-superconducting and all attempts to induce superconductivity have been unsuccessful. Work on the related material (Ce/Cu)Sr{sub 2}YCu{sub 2}O{sub y} has shown the ideal Ce content to be 0.5 Ce per formula unit. The introduction of Ba (10%) onto the Sr site dramatically increases phase stability and also induces superconductivity (62K).

  8. A study of the formation processes of the 2212 phase in the Bi-based superconductor systems. [BiSrCaCuO

    Energy Technology Data Exchange (ETDEWEB)

    Wai, Lo; Glowacki, B A [Interdisciplinary Research Centre in Superconductivity, Univ. of Cambridge (United Kingdom)

    1992-04-15

    A study towards the identification of the reactions contributing to and accompanying the formation of the 2212 phase from oxides and carbonates by solid state reaction processes was conducted. The formation processes were investigated by thermal analysis, powder X-ray diffractometry and AC magnetic susceptometry. The 2212 phase was found to form from reactions between the 2201 phases (the non-superconducting pseudo-tetragonal and the superconducting monoclinic phases), Bi{sub 6}Ca{sub 7}O{sub 16}, CuO and SrCO{sub 3}. The 2201 phases were produced by the reactions of Bi-Sr-Cu-O or Bi-Sr-O compounds with SrCO{sub 3} or CuO. The 2201 phases could also be formed through the direct reaction between Bi{sub 2}CuO{sub 4} and SrCO{sub 3}. (orig.).

  9. Screen printed Y and Bi-based superconductors

    Science.gov (United States)

    Haertling, Gene H.; Hsi, Chi-Shiung

    1992-01-01

    High T(sub c) superconducting thick film was prepared by screen printing process. Y-based (YBa2Cu3O(7 - x)) superconducting thick films were printed on 211/Al2O3, SNT/Al2O3, and YSZ substrates. Because of poor adhesion of the superconducting thick films to 211/Al2O3 and SNT/Al2O3 substrates, relatively low T(sub c) and J(sub c) values were obtained from the films printed on these substrates. Critical temperatures of YBa2Cu3O(7 - x) thick films deposited on 211/Al2O3 and SNT/Al2O3 substrates were about 80 K. The critical current densities of these films were less than 2 A/cm(exp 2). Higher T(sub c) and J(sub c) films were printed on the YSZ substrates; T(sub c) = 86.4 K and J(sub c) = 50.4 A/cm(exp 2). Multiple lead samples were also prepared on the YSZ substrates. These showed lower T(sub c) and J(sub c) values than plain samples. The heat treatment conditions of the multiple lead samples are still under investigation. Bi-based superconductor thick films have been obtained so far. Improving the superconducting properties of the BSCCO screen printed thick films will be emphasized in future work.

  10. Superconductivity in Ba sub 1 sub - sub x K sub x BiO sub 3 : possible scenario of spatially separated Fermi-Bose mixture

    CERN Document Server

    Menushenkov, A P; Kuznetsov, A V; Kagan, M Y

    2001-01-01

    A new scenario for the metal-insulator phase transition and superconductivity in the perovskite-like bismuthates Ba sub 1 sub - sub x K sub x BiO sub 3 (BKBO) is proposed. It is shown that two types of charge carriers, the local pairs (real-space bosons) and the itinerant electrons, exist in the metallic compound BKBO (x >= 0.37). The real-space bosons are responsible for the charge transport in semiconducting BaBiO sub 3 and for superconductivity in the metallic BKBO. The appearance of the Fermi-liquid state as the percolation threshold is overcome (x >= 0.37) explains the observed metal-insulator phase transition. Because bosons and fermions occupy different types of the octahedral BiO sub 6 complexes, they are separated in real space, and therefore, the spatially separated Fermi-Bose mixture of a new type is likely to be realized in the bismuthates. The nature of superconductivity is consistently explained in the framework of this scenario. A new superconducting oxide Ba sub 1 sub - sub x La sub x PbO sub ...

  11. Growth of high T/sub c/ superconducting Bi4(Ca,Sr)6Cu4O/sub 16+//sub x/ crystals

    International Nuclear Information System (INIS)

    Morris, P.A.; Bonner, W.A.; Bagley, B.G.; Hull, G.W.; Stoffel, N.G.; Greene, L.H.; Meagher, B.; Giroud, M.

    1988-01-01

    To determine intrinsic properties of the newly discovered Bi-Ca-Sr-Cu-O high T/sub c/ superconductors, single crystals are necessary. Compositions in this system have been heat treated to survey the melting temperatures and phase field in which superconductivity is detected. The nucleation and growth of the 85 K phase from the melted composition Bi 4 Ca 3 Sr 3 Cu 4 O/sub 16+//sub x/ is observed to be a kinetically slow process which can be precluded by a sufficiently rapid quench, but post-anneals produce the 85 and 110 K phases in the quenched material. The melted composition (23% Bi 2 O 3 -46% CaO,SrO-31% CuO), after subsequent slow cooling, results in large discrete crystals of the 85 K superconducting phase and a residual flux

  12. Bean model and ac losses in Bi2Ca2Cu3O10/Ag tapes

    International Nuclear Information System (INIS)

    Suenaga, M.; Chiba, T.; Wiesmann, H.J.; Haldar, P.

    1997-01-01

    The Bean model is almost solely used to interpret ac losses in the powder-in-tube processed composite conductor, Bi 2 Sr 2 Ca 2 Cu 3 O 10 /Ag. In order to examine the limits of the applicability of the model, a detailed comparison was made between the values of critical current density J c for Bi(2223)/Ag tapes which were determined by standard four-probe-dc measurement, and which were deduced from the field dependence of the ac losses utilizing the model. A significant inconsistency between these values of J c were found, particularly at high fields. Possible sources of the discrepancies are discussed

  13. Crystalline phases and electronic structures in superconducting Bi endash Sr endash Ca endash Cu oxides

    International Nuclear Information System (INIS)

    Giardina, M.D.; Feduzi, R.; Inzaghi, D.; Manara, A.; Giori, C.; Sora, I.N.; Dallacasa, V.

    1997-01-01

    Two classes of samples, designated A and B, of layered Bi endash Sr endash Ca endash Cu oxides having the same nominal composition 4:3:3:4, but different thermal histories, were investigated by using field modulated microwave absorption (ESR), powder x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and x-ray absorption near the edge structure (XANES). Previous electrical resistivity measurements showed that the B samples only presented two superconducting phases with midpoints of the transition temperatures at ∼80K and ∼105K. The microwave absorption technique indicated instead the presence of islands which became superconducting at the above-mentioned temperatures also in the A samples. The crystalline and electronic structures of the two types of samples are illustrated and discussed. A plausible theoretical interpretation of the experimental results, based on a quantum percolation model with Coulomb interaction, is also given. copyright 1997 Materials Research Society

  14. Development and fabrication of a Bi-2223 racetrack coil for generator applications

    International Nuclear Information System (INIS)

    Herd, K.G.; Salasoo, L.; Laskaris, E.T.; Ranze, R.A.; King, C.G.

    1996-01-01

    The development and fabrication of a layer-wound, epoxy-impregnated Bi-2223 high-temperature superconducting (HTS) racetrack coil which generates 40,000 ampere-turns of magnetomotive force (MMF) at 25 K is described. The coil was wound using Ag-sheathed Bi-2223 tape conductor laminated with copper foils for strength enhancement and insulated using a paper-wrap method. After epoxy impregnation, the coil was tested over a range of 16--25 K in a vacuum dewar using a closed-cycle helium refrigeration system. Descriptions of the tape lamination and insulation processing, the coil winding and impregnation, and the experimental test setup are given

  15. Study on the Visible-Light Photocatalytic Performance and Degradation Mechanism of Diclofenac Sodium under the System of Hetero-Structural CuBi2O4/Ag3PO4 with H2O2

    Directory of Open Access Journals (Sweden)

    Xiaojuan Chen

    2018-03-01

    Full Text Available Two kinds of CuBi2O4/Ag3PO4 with different heterojunction structures were prepared based on the combination of hydrothermal and in-situ precipitation methods with surfactant additives (sodium citrate and sodium stearate, and their characteristics were systematically resolved by X-ray Diffraction (XRD, Brunauer–Emmett–Teller (BET, X-ray Photoelectron Spectroscopy (XPS, Scanning Electron Microscope (SEM/ High-resolution Transmission Electron Microscopy (HRTEM, UV-vis Diffuse Reflectance Spectra (DRS and Photoluminescence (PL. Meanwhile, the photocatalytic properties of the catalysts were determined for diclofenac sodium (DS degradation and the photocatalytic mechanism was also explored. The results indicate that both of the two kinds of CuBi2O4/Ag3PO4 exhibit higher photocatalytic efficiency, mineralization rate, and stability than that of pure CuBi2O4 or Ag3PO4. Moreover, the catalytic activity of CuBi2O4/Ag3PO4 can be further enhanced by adding H2O2. The free radical capture experiments show that in the pure CuBi2O4/Ag3PO4 photocatalytic system, the OH• and O2•− are the main species participating in DS degradation; however, in the CuBi2O4/Ag3PO4 photocatalytic system with H2O2, all OH•, h+, and O2•− take part in the DS degradation, and the contribution order is OH• > h+ > O2•−. Accordingly, the photocatalytic mechanism of CuBi2O4/Ag3PO4 could be explained by the Z-Scheme theory, while the catalysis of CuBi2O4/Ag3PO4 with H2O2 follows the heterojunction energy band theory.

  16. Superconducting properties of Pb nanoislands on Pb/Ag/Si(111) studied by a {sup 3}He-cooled scanning tunnelling microscope in magnetic fields at variable temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Leon Vanegas, Alvaro Augusto

    2015-02-26

    A {sup 3}He-cooled scanning tunneling microscope was used to investigate the superconducting properties of Pb single layers on Si(111) and Ag/Si(111) and Pb islands on Pb/Ag/Si(111) at temperatures between 0.38 K and 6 K and in magnetic fields of up to 3 T. The spectroscopy measurements show that in contrast with Pb/Si(111), a single Pb layer on Ag/Si(111) is non-superconducting. The superconductivity of Pb islands on Pb/Ag/Si(111) was characterized as a function of temperature and magnetic field. A non-uniform critical magnetic field for suppression of superconductivity on islands of uniform thickness but sitting of regions of different height is reported. The proximity induced superconductivity on the wetting layer surrounding a Pb island on Pb/Ag/Si(111) was studied. Spatially resolved, magnetic field dependent spectroscopy uncovers a non-trivial reduction of the extension of the induced superconductivity with increasing field. A breakdown of the proximity effect for fields larger than 0.5 T is found. Tunneling spectroscopy reveals a strong decrease of the proximity length with increasing temperature. This is ascribed to the thermally induced broadening of the electronic density of states in the tip used in the STM experiment.

  17. LED Die-Bonded on the Ag/Cu Substrate by a Sn-BiZn-Sn Bonding System

    Science.gov (United States)

    Tang, Y. K.; Hsu, Y. C.; Lin, E. J.; Hu, Y. J.; Liu, C. Y.

    2016-12-01

    In this study, light emitting diode (LED) chips were die-bonded on a Ag/Cu substrate by a Sn-BixZn-Sn bonding system. A high die-bonding strength is successfully achieved by using a Sn-BixZn-Sn ternary system. At the bonding interface, there is observed a Bi-segregation phenomenon. This Bi-segregation phenomenon solves the problems of the brittle layer-type Bi at the joint interface. Our shear test results show that the bonding interface with Bi-segregation enhances the shear strength of the LED die-bonding joints. The Bi-0.3Zn and Bi-0.5Zn die-bonding cases have the best shear strength among all die-bonding systems. In addition, we investigate the atomic depth profile of the deposited Bi-xZn layer by evaporating Bi-xZn E-gun alloy sources. The initial Zn content of the deposited Bi-Zn alloy layers are much higher than the average Zn content in the deposited Bi-Zn layers.

  18. Possible superconductivity in the Bismuth IV solid phase under pressure.

    Science.gov (United States)

    Valladares, Ariel A; Rodríguez, Isaías; Hinojosa-Romero, David; Valladares, Alexander; Valladares, Renela M

    2018-04-13

    The first successful theory of superconductivity was the one proposed by Bardeen, Cooper and Schrieffer in 1957. This breakthrough fostered a remarkable growth of the field that propitiated progress and questionings, generating alternative theories to explain specific phenomena. For example, it has been argued that Bismuth, being a semimetal with a low number of carriers, does not comply with the basic hypotheses underlying BCS and therefore a different approach should be considered. Nevertheless, in 2016 based on BCS we put forth a prediction that Bi at ambient pressure becomes a superconductor at 1.3 mK. A year later an experimental group corroborated that in fact Bi is a superconductor with a transition temperature of 0.53 mK, a result that eluded previous work. So, since Bi is superconductive in almost all the different structures and phases, the question is why Bi-IV has been elusive and has not been found yet to superconduct? Here we present a study of the electronic and vibrational properties of Bi-IV and infer its possible superconductivity using a BCS approach. We predict that if the Bi-IV phase structure were cooled down to liquid helium temperatures it would also superconduct at a T c of 4.25 K.

  19. Improved solar-driven photocatalytic performance of Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} prepared in-situ

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Junbo, E-mail: junbozhong@163.com [Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan, College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Li, Jianzhang, E-mail: lschmanuscript@163.com [Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan, College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Huang, Shengtian; Cheng, Chaozhu; Yuan, Wei [Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan, College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Li, Minjiao [Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan, College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Sichuan Provincial Academician (Expert) Workstation, Sichuan University of Science and Engineering, Zigong 643000 (China); Ding, Jie [Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan, College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China)

    2016-05-15

    Highlights: • Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} photocatalysts were prepared in-situ. • The photo-induced charge separation rate has been greatly increased. • The photocatalytic activity has been greatly promoted. - Abstract: Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} composites have been fabricated in-situ via a facile parallel flaw co-precipitation method. The specific surface area, structure, morphology, and the separation rate of photo-induced charge pairs of the photocatalysts were characterized by Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy(DRS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and surface photovoltage (SPV) spectroscopy, respectively. XRD patterns and DRS demonstrated that Ag{sub 2}CO{sub 3} has no effect on the crystal phase and bandgap of (BiO){sub 2}CO{sub 3}. The existence of Ag{sub 2}CO{sub 3} in the composites enhances the separation rate of photo-induced charge pairs of the photocatalysts. The photocatalytic performance of Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} was evaluated by the decolorization of methyl orange (MO) aqueous solution under simulated solar irradiation. It was found that the simulated solar-induced photocatalytic activity of Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} copmposites was significantly improved, which was mainly attributed to the enhanced surface area and the separation rate of photo-induced charge pairs.

  20. Effect of lead content on phase evolution and microstructural development in Ag-clad Bi-2223 composite conductors

    International Nuclear Information System (INIS)

    Merchant, N.N.; Maroni, V.A.; Fischer, A.K.; Dorris, S.E.; Zhong, W.; Ashcom, N.

    1997-02-01

    A two powder process was used to prepare silver-sheathed monofilamentary Bi 1.8 Pb x Sr 1.98 Ca 1.97 Cu 3.08 O y (Bi-2223) tapes with varying lead contents, x, from 0.2 to 0.5. The resulting tapes were subjected to thermomechanical processing and then characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray analysis (EDX). Layered phase texture was accessed using image analysis software on scanned SEM micrographs. Transport currents were measured at 77 K and zero field by the four-probe method. It was found that tapes with low lead content (X = 0.2 and 0.25) showed incomplete conversion to Bi-2223, had small grain size and poor c-axis texture. Tapes having higher lead content (x = 0.4 and 0.5) also showed incomplete conversion and the presence of lead-rich secondary phases. Tapes with lead content x = 0.3 and 0.35 showed complete conversion to Bi-2223, and had the least amount of secondary phases, the best c-axis texture, and the highest transport current (j c ). The carbon content of the precursor powder also had a strong influence on secondary-phase chemistry

  1. Slow voltage oscillations in Ag-doped superconducting Y-Ba-Cu-O

    International Nuclear Information System (INIS)

    Altinkok, A.; Yetis, H.; Kilic, K.; Kilic, A.; Olutas, M.

    2008-01-01

    The time effects in Ag-doped YBa 2 Cu 3 O 7-x sample (YBCO/Ag) were examined by means of transport relaxation measurements (V-t curves). At well-defined values of transport current (I), temperature (T) and external magnetic field (H), an abrupt rise in sample voltage was observed at the early stage of the relaxation process. After reducing the initial current to a finite value, the sample voltage levels off within a very short time. The rapid voltage drops seen in V-t curves were attributed to the rapid dynamic reorganization of flux lines traversing the sample edges. These observations were also interpreted as an indication of doping of YBCO with Ag and easy suppression of superconducting order parameter due to the presence of Ag. In addition, we investigated the influence of bidirectional square wave (BSW) current on the evolution of V-t curves at different temperatures and external magnetic fields. It was observed that a nonlinear response seen in V-t curves to BSW current with sufficiently short periods or sufficiently low amplitude reflects itself as regular sinusoidal- type voltage oscillations, which were discussed mainly in terms of the dynamic competition between pinning and depinning

  2. Uniaxial Strain Induced Critical Current Degradation of Ag-Sheathed Bi-2212 Round Wire

    NARCIS (Netherlands)

    Dai, Chao; Qin, Jinggang; Liu, Bo; Liu, Peihang; Wu, Yu; Nijhuis, Arend; Zhou, Chao; Li, Chenshan; Hao, Qingbin; Liu, Sheng

    2018-01-01

    The critical current degradation of Bi-2212 Ag-sheathed round wire subjected to uniaxial strain was studied at 4.2 K in 14 T background field. The strains applied on the sample are both tension and compression. The additional tensile strain caused by the difference in thermal expansion between the

  3. Spin-rotation symmetry breaking and triplet superconducting state in doped topological insulator CuxBi2Se3

    Science.gov (United States)

    Zheng, Guo-Qing

    Spontaneous symmetry breaking is an important concept for understanding physics ranging from the elementary particles to states of matter. For example, the superconducting state breaks global gauge symmetry, and unconventional superconductors can break additional symmetries. In particular, spin rotational symmetry is expected to be broken in spin-triplet superconductors. However, experimental evidence for such symmetry breaking has not been obtained so far in any candidate compounds. We report 77Se nuclear magnetic resonance measurements which showed that spin rotation symmetry is spontaneously broken in the hexagonal plane of the electron-doped topological insulator Cu0.3Bi2Se3 below the superconducting transition temperature Tc =3.4 K. Our results not only establish spin-triplet (odd parity) superconductivity in this compound, but also serve to lay a foundation for the research of topological superconductivity (Ref.). We will also report the doping mechanism and superconductivity in Sn1-xInxTe.

  4. Critical current density, irreversibility line, and flux creep activation energy in silver-sheathed Bi2Sr2Ca2Cu3Ox superconducting tapes

    International Nuclear Information System (INIS)

    Shi, D.; Wang, Z.; Sengupta, S.; Smith, M.; Goodrich, L.F.; Dou, S.X.; Liu, H.K.; Guo, Y.C.

    1992-08-01

    Transport data, magnetic hysteresis and flux creep activation energy experimental results are presented for silver-sheathed high-T c Bi 2 Sr 2 Ca 2 Cu 3 O x superconducting tapes. The 110 K superconducting phase was formed by lead doping in a Bi-Sr-Ca-Cu-0 system. The transport critical current density was measured at 4.0 K to be 0.7 x 10 5 A/cm 2 (the corresponding critical current is 74 A) at zero field and 1.6 x 10 4 A/cm 2 at 12 T for H parallel ab. Excellent grain alignment in the a-b plane was achieved by a short-melting method, which considerably improved the critical current density and irreversibility line. Flux creep activation energy as a function of current is obtained based on the magnetic relaxation measurements

  5. Effect of Silver Doping on Transport Properties of Bi2Se3: AgxBi2Se3 and Bi2-xAgxSe3

    Science.gov (United States)

    Zhang, Min; Wei, Zhan-Tao

    2018-03-01

    Ag-doped Bi2Se3 with the formula AgxBi2Se3 and Bi2-xAgxSe3 were prepared and their electrical and magnetic transport properties have been investigated to study the influence of silver doping on transport properties of Bi2Se3 with different Ag-doped method. All samples exhibited metallic resistivity and the resistivity increased with increasing Ag concentration. The lattice parameter c of Ag-substituted and Ag-intercalated samples displays a contrary change as the Ag concentration increased. For the Ag-intercalated samples, both the resistance upturn were observed in the curves of temperature dependent of resistivity and temperature dependent of magnetoresistance, respectively, indicating that the enhanced surface effect was obtained in those samples. Monotonously, field-induced MR peaks around 200 K were also observed in those samples. Similar behaviors were not observed in the Ag-substituted samples.

  6. Effect of Silver Doping on Transport Properties of Bi2Se3: AgxBi2Se3 and Bi2-xAgxSe3

    Science.gov (United States)

    Zhang, Min; Wei, Zhan-Tao

    2018-05-01

    Ag-doped Bi2Se3 with the formula AgxBi2Se3 and Bi2-xAgxSe3 were prepared and their electrical and magnetic transport properties have been investigated to study the influence of silver doping on transport properties of Bi2Se3 with different Ag-doped method. All samples exhibited metallic resistivity and the resistivity increased with increasing Ag concentration. The lattice parameter c of Ag-substituted and Ag-intercalated samples displays a contrary change as the Ag concentration increased. For the Ag-intercalated samples, both the resistance upturn were observed in the curves of temperature dependent of resistivity and temperature dependent of magnetoresistance, respectively, indicating that the enhanced surface effect was obtained in those samples. Monotonously, field-induced MR peaks around 200 K were also observed in those samples. Similar behaviors were not observed in the Ag-substituted samples.

  7. Carrier doping into a superconducting BaPb0.7Bi0.3O3‑δ epitaxial film using an electric double-layer transistor structure

    Science.gov (United States)

    Komori, S.; Kakeya, I.

    2018-06-01

    Doping evolution of the unconventional superconducting properties in BaBiO3-based compounds has yet to be clarified in detail due to the significant change of the oxygen concentration accompanied by the chemical substitution. We suggest that the carrier concentration of an unconventional superconductor, BaPb0.7Bi0.3O3‑δ , is controllable without inducing chemical or structural changes using an electric double-layer transistor structure. The critical temperature is found to decrease systematically with increasing carrier concentration.

  8. Bi2(Sr, Ln)2CuOz (Ln = Nd, Sm) phases: stability, crystal growth and superconducting properties

    International Nuclear Information System (INIS)

    Faqir, H.; Kikuchi, M.; Syono, Y.; Mansori, M.; Satre, P.; Sebaoun, A.; Vacquier, G.

    2000-01-01

    Bi 2 (Sr,Ln) 2 CuO z (Ln = Nd, Sm) single crystals were successfully grown by a self-flux method from stoichiometric and (Bi, Cu)-rich melts. Thermal analysis and thermogravimetry were used to determine stability and the melting sequence of Bi 2 (Sr,Ln) 2 CuO z phases in air. As-grown crystals of the ideal Bi 2 (Sr,Ln) 2 CuO z phase, of dimensions 1x0.5x0.03 mm 3 , exhibit superconducting behaviour with critical temperature T c = 21 K for the Bi 1.9 Sr 1.6 Nd 0.6 CuO z crystal and Tc = 14 K for the Bi 1.8 Sr 1.6 Sm 0.6 CuO z crystal. The compositions of these crystals were homogeneous and close to the stoichiometric composition. We report on the growth of Bi 2 Sr 2-x Sm x CuO z single crystals of large dimensions 9x3x0.03 mm 3 using Bi 2 Sr 1.5 Sm 0.5 CuO z as precursor and Bi 2 CuO 4 as flux. (author)

  9. Corrosion behaviour of cladded nickel base alloys

    International Nuclear Information System (INIS)

    Brandl, W.; Ruczinski, D.; Nolde, M.; Blum, J.

    1995-01-01

    As a consequence of the high cost of nickel base alloys their use as surface layers is convenient. In this paper the properties of SA-as well as RES-cladded NiMo 16Cr16Ti and NiCr21Mo14W being produced in single and multi-layer technique are compared and discussed with respect to their corrosion behaviour. Decisive criteria describing the qualities of the claddings are the mass loss, the susceptibility against intergranular corrosion and the pitting corrosion resistance. The results prove that RES cladding is the most suitable technique to produce corrosion resistant nickel base coatings. The corrosion behaviour of a two-layer RES deposition shows a better resistance against pitting than a three layer SAW cladding. 7 refs

  10. Abrupt onset of a second energy gap at the superconducting transition of underdoped Bi2212

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Zahid; Lee, W.S.; Vishik, I.M.; Tanaka, K.; Lu, D.H.; Sasagawa, T.; Nagaosa, N.; Devereaux, T.P.; Hussain, Z.; Shen, Z.-X.

    2007-05-26

    he superconducting gap--an energy scale tied to the superconducting phenomena--opens on the Fermi surface at the superconducting transition temperature (Tc) in conventional BCS superconductors. In underdoped high-Tc superconducting copper oxides, a pseudogap (whose relation to the superconducting gap remains a mystery) develops well above Tc (refs 1, 2). Whether the pseudogap is a distinct phenomenon or the incoherent continuation of the superconducting gap above Tc is one of the central questions in high-Tc research3, 4, 5, 6, 7, 8. Although some experimental evidence suggests that the two gaps are distinct9, 10, 11, 12, 13, 14, 15, 16, 17, 18, this issue is still under intense debate. A crucial piece of evidence to firmly establish this two-gap picture is still missing: a direct and unambiguous observation of a single-particle gap tied to the superconducting transition as function of temperature. Here we report the discovery of such an energy gap in underdoped Bi2Sr2CaCu2O8+delta in the momentum space region overlooked in previous measurements. Near the diagonal of Cu?O bond direction (nodal direction), we found a gap that opens at Tc and has a canonical (BCS-like) temperature dependence accompanied by the appearance of the so-called Bogoliubov quasi-particles, a classical signature of superconductivity. This is in sharp contrast to the pseudogap near the Cu?O bond direction (antinodal region) measured in earlier experiments19, 20, 21.

  11. Efficient visible light photocatalytic NO{sub x} removal with cationic Ag clusters-grafted (BiO){sub 2}CO{sub 3} hierarchical superstructures

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xin [Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environment and Resources, Engineering Research Center for Waste Oil Recovery Technology and Equipment of Ministry of Education, College of Environment and Resources, Chongqing Technology and Business University, Chongqing 40067 (China); Zhang, Wendong [Department of Scientific Research Management, Chongqing Normal University, Chongqing 401331 (China); Deng, Hua [State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Ni, Zilin [Department of Scientific Research Management, Chongqing Normal University, Chongqing 401331 (China); Dong, Fan, E-mail: dfctbu@126.com [Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environment and Resources, Engineering Research Center for Waste Oil Recovery Technology and Equipment of Ministry of Education, College of Environment and Resources, Chongqing Technology and Business University, Chongqing 40067 (China); Zhang, Yuxin, E-mail: zhangyuxin@cqu.edu.cn [College of Materials Science and Engineering, National Key Laboratory of Fundamental Science of Micro/Nano-Devices and System Technology, Chongqing University, Chongqing 400044 (China)

    2017-01-15

    Graphical abstract: The cationic Ag clusters-grafted (BiO){sub 2}CO{sub 3} hierarchical superstructures exhibits highly enhanced visible light photocatalytic air purification through an interfacial charge transfer process induced by Ag clusters. - Highlights: • Microstructural optimization and surface cluster-grafting were firstly combined. • Cationic Ag clusters were grafted on the surface of (BiO){sub 2}CO{sub 3} superstructures. • The Ag clusters-grafted BHS displayed enhanced visible light photocatalysis. • Direct interfacial charge transfer (IFCT) from BHS to Ag clusters was proposed. • The charge transfer process and the dominant reactive species were revealed. - Abstract: A facile method was developed to graft cationic Ag clusters on (BiO){sub 2}CO{sub 3} hierarchical superstructures (BHS) surface to improve their visible light activity. Significantly, the resultant Ag clusters-grafted BHS displayed a highly enhanced visible light photocatalytic performance for NOx removal due to the direct interfacial charge transfer (IFCT) from BHS to Ag clusters. The chemical and coordination state of the cationic Ag clusters was determined with the extended X-ray absorption fine structure (EXAFS) and a theoretical structure model was proposed for this unique Ag clusters. The charge transfer process and the dominant reactive species (·OH) were revealed on the basis of electron spin resonance (ESR) trapping. A new photocatalysis mechanism of Ag clusters-grafted BHS under visible light involving IFCT process was uncovered. In addition, the cationic Ag clusters-grafted BHS also demonstrated high photochemical and structural stability under repeated photocatalysis runs. The perspective of enhancing photocatalysis through combination of microstructural optimization and IFCT could provide a new avenue for the developing efficient visible light photocatalysts.

  12. Bandgap Engineering of Lead-Free Double Perovskite Cs2 AgBiBr6 through Trivalent Metal Alloying.

    Science.gov (United States)

    Du, Ke-Zhao; Meng, Weiwei; Wang, Xiaoming; Yan, Yanfa; Mitzi, David B

    2017-07-03

    The double perovskite family, A 2 M I M III X 6 , is a promising route to overcome the lead toxicity issue confronting the current photovoltaic (PV) standout, CH 3 NH 3 PbI 3 . Given the generally large indirect band gap within most known double perovskites, band-gap engineering provides an important approach for targeting outstanding PV performance within this family. Using Cs 2 AgBiBr 6 as host, band-gap engineering through alloying of In III /Sb III has been demonstrated in the current work. Cs 2 Ag(Bi 1-x M x )Br 6 (M=In, Sb) accommodates up to 75 % In III with increased band gap, and up to 37.5 % Sb III with reduced band gap; that is, enabling ca. 0.41 eV band gap modulation through introduction of the two metals, with smallest value of 1.86 eV for Cs 2 Ag(Bi 0.625 Sb 0.375 )Br 6 . Band structure calculations indicate that opposite band gap shift directions associated with Sb/In substitution arise from different atomic configurations for these atoms. Associated photoluminescence and environmental stability of the three-metal systems are also assessed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Slow voltage oscillations in Ag-doped superconducting Y-Ba-Cu-O

    Energy Technology Data Exchange (ETDEWEB)

    Altinkok, A. [Abant Izzet Baysal University, Department of Physics, Turgut Gulez Research Laboratory, 14280 Bolu (Turkey)], E-mail: altinkok_a@ibu.edu.tr; Yetis, H.; Kilic, K.; Kilic, A.; Olutas, M. [Abant Izzet Baysal University, Department of Physics, Turgut Gulez Research Laboratory, 14280 Bolu (Turkey)

    2008-09-15

    The time effects in Ag-doped YBa{sub 2}Cu{sub 3}O{sub 7-x} sample (YBCO/Ag) were examined by means of transport relaxation measurements (V-t curves). At well-defined values of transport current (I), temperature (T) and external magnetic field (H), an abrupt rise in sample voltage was observed at the early stage of the relaxation process. After reducing the initial current to a finite value, the sample voltage levels off within a very short time. The rapid voltage drops seen in V-t curves were attributed to the rapid dynamic reorganization of flux lines traversing the sample edges. These observations were also interpreted as an indication of doping of YBCO with Ag and easy suppression of superconducting order parameter due to the presence of Ag. In addition, we investigated the influence of bidirectional square wave (BSW) current on the evolution of V-t curves at different temperatures and external magnetic fields. It was observed that a nonlinear response seen in V-t curves to BSW current with sufficiently short periods or sufficiently low amplitude reflects itself as regular sinusoidal- type voltage oscillations, which were discussed mainly in terms of the dynamic competition between pinning and depinning.

  14. Impact of radiation exposure on mechanical and superconducting properties of Bi-2212 superconductor ceramics

    International Nuclear Information System (INIS)

    Azlan Abdul Rahman; Nasri Abdul Hamid; Abdul Aziz Mohamed; Mohd Shahrul Nizam Abdullah; Samsul Isman; Hidayah Zainal

    2013-01-01

    Full-text: For practical applications of high-temperature superconductor ceramics, the compounds must be able to sustain extreme mechanical stress and external magnetic field. Bi-2212 superconductor is one of the existing superconductors that are commonly used in various applications. Improvement in the microstructure enhanced the connectivity of the adjacent grains within the superconducting grains, and as such improved the mechanical strength of the ceramics. The ability of the superconductor ceramics to sustain superconducting properties in external magnetic field is also required. The compounds must be able to maintain high transport critical current density (Jc) in magnetic field. Another potential application of superconductors is at the nuclear facilities. Thus, study on the impact of radiation exposure on the mechanical and superconducting properties is very important to gauge the viability of superconductor ceramics in such environment. In this study, the mechanical and superconducting properties between exposure and non-irradiated samples are compared. Characterization will be done by the temperature dependence on electrical resistance measurements, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and measurements of transport critical current (Jc) dependence on temperature in magnetic field. (author)

  15. Evidence for phonon-mediated coupling in superconducting Ba0.6K0.4BiO3

    International Nuclear Information System (INIS)

    Hinks, D.G.; Dabrowski, B.; Richards, D.R.; Jorgensen, J.D.; Pei, S.; Zasadzinski, J.F.

    1989-01-01

    Superconducting Ba 0.6 K 0.4 BiO 3 , with a T c of 30 K, shows a large 18 O isotope effect which indicates that phonons are involved in the pairing mechanism. Infrared reflectivity measurements indicate a value for the superconducting gap consistent with moderate coupling (2Δ/k T c = 3.5 ± 0.5). A mediating energy for pairing of about 40 meV would be required to obtain a T c of 30 K. Strong coupling of electrons by optical phonons (which are present in this material with energies up to 80 meV) could account for the observed transition temperature. Recent tunneling spectroscopy shows the presence of strongly coupled optical phonons in the 40 to 70 meV region, indicating that superconductivity in this material may be phonon mediated

  16. Two-dimensional peridynamic simulation of the effect of defects on the mechanical behavior of Bi2Sr2CaCu2Ox round wires

    International Nuclear Information System (INIS)

    Le, Q V; Chan, W K; Schwartz, J

    2014-01-01

    Ag/AgX sheathed Bi 2 Sr 2 CaCu 2 O x (Bi2212) is the only superconducting round wire (RW) with high critical current density (J c ) at high magnetic (>25 T) and is thus a strong candidate for high field magnets for nuclear magnetic resonance and high energy physics. A significant remaining challenge, however, is the relatively poor electromechanical behavior of Bi2212 RW, yet there is little understanding of the relationships between the internal Bi2212 microstructure and the mechanical behavior. This is in part due to the complex microstructures within the Bi2212 filaments and the uncertain role of interfilamentary bridges. Here, two-dimensional peridynamic simulations are used to study the stress distribution of the Bi2212 RWs under an axial tensile load. The simulations use scanning electron micrographs obtained from high J c wires as a starting point to study the impact of various defects on the distribution of stress concentration within the Bi2212 microstructure and Ag. The flexibility of the peridynamic approach allows various defects, including those captured from SEM micrographs and artificially created defects, to be inserted into the microstructure for systematic study. Furthermore, this approach allows the mechanical properties of the defects to be varied, so the effects of porosity and both soft and hard secondary phases are evaluated. The results show significant stress concentration around defects, interfilamentary bridges and the rough Bi2212/Ag interface. In general, the stress concentration resulting from porosity is greater than that of solid-phase inclusions. A clear role of the defect geometry is observed. Results indicate that crack growth is likely to initiate at the Ag/Bi2212 interface or at voids, but that voids may also arrest crack growth in certain circumstances. These results are consistent with experimental studies of Bi2212 electromechanical behavior and magneto-optical imaging of crack growth. (paper)

  17. Finite Element-Assisted Assessment of the Thermo-cyclic Characteristics of Leads Soldered with SnAgCu(+Bi,In) Alloys

    Science.gov (United States)

    Lis, Adrian; Nakanishi, Kohei; Matsuda, Tomoki; Sano, Tomokazu; Minagawa, Madoka; Okamoto, Masahide; Hirose, Akio

    2017-07-01

    Solder joints between leads and printed circuit boards in thin small outline packages were produced with conventional Sn1.0Ag0.7Cu (SAC107) and Sn3.0Ag0.7Cu (SAC305) solders as well as various solder alloys with gradually increasing amounts of Bi (up to 3.0 wt.%) and In (up to 1.0 wt.%) within the SAC107 base solder. The reliability of soldered leads in temperature cycle (TC) tests improved most with solder alloys containing both Bi (1.6 wt.%) and In (0.5 wt.%). Microindentation and electron probe microanalysis mappings revealed that the effect originates from a combination of solution and precipitation strengthening of the initial SAC alloy. The distribution of inelastic strain accumulation (ISA), as a measure for degradation, was determined in the solder joints by finite element calculations. It was shown that defects in the solder proximal to the lead (60-75 μm), which was underpinned by similar cracking characteristics along the lead-solder interface. The ISA was confirmed to be lower in SAC+Bi/In alloys owing to their enhanced elasto-plastic properties. Moreover, the addition of a thin Cu coating on the leads could improve the joint reliability, as suggested by the calculation of the ISA and the acceleration factor.

  18. Magnetic properties and superconducting-fluctuation diamagnetism above Tc in Bi2-xPbxSr2CaCu2O8+δ (x=0.0, 0.1, 0.2, 0.3, 0.5) and

    International Nuclear Information System (INIS)

    Lee, W.C.; Cho, J.H.; Johnston, D.C.

    1991-01-01

    The magnetic susceptibilities χ(T) of the title compounds above and below T c are reported. For the Bi 2-x Pb x Sr 2 CaCu 2 O 8+δ (Bi 2:2:1:2) system, optimization of the phase purity and superconducting properties is found between x=0.2 and 0.3. The χ(T) data for these Bi 2:2:1:2 and for the two Bi 2:2:2:3 samples increase monotonically with temperature from T c up to at least 400 K, exhibiting strong negative curvature below ∼200 K. From theoretical fits to the data in the two-dimensional regime above T c using the static Lawrence-Doniach model as modified by Klemm, we conclude that the negative curvature in χ(T) for each sample arises from superconducting-fluctuation diamagnetism (SFD). The data are thus consistent with a superconducting order parameter of s-wave symmetry. From the fits to the data, the Ginzburg-Landau coherence lengths in the CuO 2 planes were obtained and found to be ξ ab (0)=20.4(2) A for Bi 2:2:1:2 and 11.8(4) A for Bi 2:2:2:3. The value for Bi 2:2:1:2 is comparable to those calculated from upper critical magnetic-field data for this compound (23.5--27.1 A). Our ξ ab (0) values for Bi 2:2:1:2 and Bi 2:2:2:3 are also comparable with that (13.6 A) found from our previous similar analysis of the SFD in YBa 2 Cu 3 O 7 . The possible role of the bridging oxygens out of the CuO 2 plane in Bi 2:2:2:3 and the influence of the dynamics in the fits to the SFD in the Bi-based compounds remain to be addressed

  19. Temperature dependence of filament-coupling in Bi-2223 tapes: magneto-optical study

    International Nuclear Information System (INIS)

    Bobyl, A.V.; Shantsev, D.V.; Galperin, Y.M.; Johansen, T.H.; Baziljevich, M.; Gaevski, M.E.

    2000-01-01

    Coupling through random superconducting bridges between filaments in a multifilamentary Ag-sheathed Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ tape has been investigated by magneto-optical imaging at temperatures from 20 K up to T c . Magnetic flux distributions have been measured on the surface of an intact tape in the remanent state on applying a strong perpendicular magnetic field. The flux distributions observed at low temperatures reflect the arrangement of individual filaments. At high temperatures, the distribution becomes more similar to that for a uniform monocore tape, indicating that superconducting connections appear between the filaments. To discuss the relative contributions of the intra- and inter-filament currents, a simple model based on the Bean critical state was proposed and applied to analyse the temperature dependent behaviour. The inter-filament coupling, increasing with temperature, reaches at 77 K a point where the currents flowing in large inter-filament loops are roughly equal to the intra-filament currents. (author)

  20. Current Capacity of Ag/Bi-2223 Wires for Rotating Electric Machinery

    International Nuclear Information System (INIS)

    Hussennether, Volker; Leghissa, Martino; Neumueller, Heinz-Werner

    2006-01-01

    With focus on the application in rotating electric machines we measured the dependence of current capacity of Ag/Bi-2223 wires on temperature and magnetic field. Even for wires stemming from a single manufacturer we observe a significant spread of wire properties. We study different temperature and magnetic field dependence by a parallel path model which allows for a quantitative analysis. The implications of experiments and modelling are discussed with regard to the further wire development and for application within windings

  1. A jelly-roll process for high temperature superconducting tapes and wires

    Energy Technology Data Exchange (ETDEWEB)

    Tsuei, C C; Chi, C C; Frey, T; Mitzi, D B; Kazyaka, T [IBM Thomas J. Watson Research Center, Yorktown Heights, NY (United States); Haugan, T; Ye, J; Patel, S; Shaw, D T [New York State Inst. on Superconductivity, SUNY, Buffalo, Amherst, NY (United States); Wu, M K [Dept. of Physics, National Tsing Hua Univ., Hsinchu (Taiwan)

    1992-07-01

    As an alternative to the powder-in-tube method, a new technique called the jelly-roll process is proposed for making high-T[sub c] superconducting tapes and wires. A normal-metal sheet coated with high-T[sub c] cuprate is configured in a jelly-roll fashion and cold worked into tapes or wires made of alternating cuprate superconductor and normal metal layers. The feasibility of this new process is demonstrated for both the YBa[sub 2]Cu[sub 3]O[sub 7]/Ag and Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8]/Ag composite systems. The role of reduction in the cross-sectional area by cold-rolling, heat treatment and oxygenation in optimizing T[sub c] and J[sub c] has been studied. Preliminary results indicate that partialmelt texturing, in the Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8]/Ag system, results in a relatively field independent J[sub c] (H< or approx.7T) with J[sub c](H = 0) [proportional to]5 X 10[sup 4] A cm[sup -2] at 4.2 K.

  2. Bandgap engineering of lead-free double perovskite Cs_2AgBiBr_6 through trivalent metal alloying

    International Nuclear Information System (INIS)

    Du, Ke-zhao; Mitzi, David B.; Meng, Weiwei; Wang, Xiaoming; Yan, Yanfa

    2017-01-01

    The double perovskite family, A_2M"IM"I"I"IX_6, is a promising route to overcome the lead toxicity issue confronting the current photovoltaic (PV) standout, CH_3NH_3PbI_3. Given the generally large indirect band gap within most known double perovskites, band-gap engineering provides an important approach for targeting outstanding PV performance within this family. Using Cs_2AgBiBr_6 as host, band-gap engineering through alloying of In"I"I"I/Sb"I"I"I has been demonstrated in the current work. Cs_2Ag(Bi_1_-_xM_x)Br_6 (M=In, Sb) accommodates up to 75 % In"I"I"I with increased band gap, and up to 37.5 % Sb"I"I"I with reduced band gap; that is, enabling ca. 0.41 eV band gap modulation through introduction of the two metals, with smallest value of 1.86 eV for Cs_2Ag(Bi_0_._6_2_5Sb_0_._3_7_5)Br_6. Band structure calculations indicate that opposite band gap shift directions associated with Sb/In substitution arise from different atomic configurations for these atoms. Associated photoluminescence and environmental stability of the three-metal systems are also assessed. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Enhanced photocatalytic, electrochemical and photoelectrochemical properties of TiO2 nanotubes arrays modified with Cu, AgCu and Bi nanoparticles obtained via radiolytic reduction

    International Nuclear Information System (INIS)

    Nischk, Michał; Mazierski, Paweł; Wei, Zhishun; Siuzdak, Katarzyna; Kouame, Natalie Amoin; Kowalska, Ewa; Remita, Hynd; Zaleska-Medynska, Adriana

    2016-01-01

    Highlights: • TiO 2 nanotubes were modified with Cu, AgCu, Bi nanoparticles via gamma radiolysis. • Excessive amount of deposited metal decreased photocatalytic activity. • AgCu-modified samples were more active than Cu-modified (with the same Cu content). • AgCu nanoparticles exist in a core (Ag) -shell (Cu) form. • Examined photocatalysts were resistant towards photocorrosion processes. - Abstract: TiO 2 nanotubes arrays (NTs), obtained via electrochemical anodization of Ti foil, were modified with monometallic (Cu, Bi) and bimetallic (AgCu) nanoparticles. Different amounts of metals’ precursors were deposited on the surface of NTs by the spin-coating technique, and the reduction of metals was performed via gamma radiolysis. Surface modification of titania was studied by EDS and XPS analysis. The results show that AgCu nanoparticles exist in a Ag core -Cu shell form. Photocatalytic activity was examined under UV irradiation and phenol was used as a model pollutant of water. Over 95% of phenol degradation was achieved after 60 min of irradiation for almost all examined samples, but only slight difference in degradation efficiency (about 3%) between modified and bare NTs was observed. However, the initial phenol degradation rate and TOC removal efficiency was significantly enhanced for the samples modified with 0.31 and 0.63 mol% of Bi as well as for all the samples modified with Cu and AgCu nanoparticles in comparison with bare titania nanotubes. The saturated photocurrent, under the influence of simulated solar light irradiation, for the most active Bi- and AgCu-modified samples, was over two times higher than for pristine NTs. All the examined materials were resistant towards photocorrosion processes that enables their application for long term processes induced by light.

  4. Anomalous spectral weight transfer at the superconducting transition of Bi2Sr2CaCu2O8+δ

    International Nuclear Information System (INIS)

    Dessau, D.S.; Wells, B.O.; Shen, Z.; Spicer, W.E.; Arko, A.J.; List, R.S.; Mitzi, D.B.; Kapitulnik, A.

    1991-01-01

    Anomalous spectral weight transfer at the superconducting transition of single-crystalline Bi 2 Sr 2 CaCu 2 O 8+δ was observed by high-resolution angle-resolved photoemission spectroscopy. As the sample goes superconducting, not only is there spectral weight transfer from the gap region to the pileup peak as in BCS theory, but along the Γ-bar M direction there is also some spectral weight transfer from higher binding energies in the form of a dip. In addition, we note that at the superconducting transition there is a decrease (increase) in the occupied spectral weight for the spectra taken along Γ-bar M (Γ-X)

  5. Oxygen stoichiometry, superconductivity and structure of the Bi-2212 ceramics after thermal treatment in the inert atmosphere

    International Nuclear Information System (INIS)

    Bratukhin, P.V.; Aksenova, T.D.; Shavkin, S.V.; Komarov, A.O.; Voronkov, S.A.; Mozhaev, A.P.

    1993-01-01

    A complex study of the stoichiometry and superconducting properties has been performed as well as an X-ray structure analysis of Bi 1.6 Pb 0.4 Sr 2 Ca 1 Cu 2 O x ceramic samples after thermal treatment in the helium atmosphere. Annealing has been found to result in the reduction of the oxygen coefficient followed by the critical temperature rise and the decrease of the unit cell parameters which sharply distinguishes Bi2212 from Y123. Anisotropic widening of diffraction lines due to monoclinic distortions has been detected. Correlations between the monoclinic angle and the critical temperature have been disclosed. Structural changes in Bi2122 are 30-100 times smaller than in the Y123 structure under similar changes in T c

  6. Ultrahigh vacuum STM/STS studies of the Bi-O surface in Bi2Sr2CuOy single crystals

    International Nuclear Information System (INIS)

    Ikeda, Kazuto; Tomeno, Izumi; Takamuku, Kenshi; Yamaguchi, Koji; Itti, Rittaporn; Koshizuka, Naoki

    1992-01-01

    Scanning tunneling microscopic and spectroscopic studies were made on cleaved surfaces of Bi 2 Sr 2 CuO y single crystals using an ultrahigh-vacuum scanning tunneling microscope (UHV-STM). The modulation structures of the Bi-O surface were observed at room temperature with atomic resolution. The tunneling spectra showed electronic gap structures similar to those observed for the Bi-O surface of superconducting Bi-2212 single crystals. This suggests that superconductivity is not directly related to the electronic structure observed in the Bi-O plane. (orig.)

  7. The current distribution in Bi-2223/Ag HTS conductors: comparing Hall probe and magnetic knife

    NARCIS (Netherlands)

    Demencik, E.; Dhalle, Marc M.J.; ten Kate, Herman H.J.; Polak, M.

    2006-01-01

    We analyzed the current distribution in three Bi-2223/Ag tapes with different filament lay-out, comparing the results of magnetic knife and Hall probe experiments. Detailed knowledge of the current distribution can be useful for the diagnostics of HTS conductors. The lateral current distribution was

  8. Composite cathode La0.15Bi0.85O1.5-Ag for intermediate-temperature solid oxide fuel cells

    International Nuclear Information System (INIS)

    Gao Zhan; Mao Zongqiang; Huang Jianbing; Gao Ruifeng; Wang Cheng; Liu Zhixiang

    2008-01-01

    Composites consisting of silver and lanthanum stabilized bismuth oxide (La 0.15 Bi 0.85 O 1.5 ) were investigated as cathodes for intermediate-temperature solid oxide fuel cells with doped ceria as electrolyte. No stable phases were formed via reaction between La 0.15 Bi 0.85 O 1.5 and Ag. The microstructure of the interfaces between composite cathodes and Ce 0.8 Sm 0.2 O 1.5 electrolytes was studied by scanning electron microscopy after sintering at various temperatures. Impedance spectroscopy measurements revealed that the performance of cathode fired at 700 deg. C was the best. When the optimum fraction of Ag was 50 vol.%, polarization resistance values for the LSB-Ag50 cathode were as low as 0.14 Ω cm 2 at 700 deg. C and 0.18 Ω cm 2 at 650 deg. C. The steady-state polarization investigations on LSB and LSB-Ag50 cathodes were performed using typical three-electrode test cells in air. The results showed that the LSB-Ag50 composite cathode exhibited a lower overpotential and higher exchange current density than LSB, which indicated the electrochemical performance of LSB-Ag50 for the oxygen reduction reaction was superior to the LSB

  9. Mechanical and physical properties of Bi-2223 and Nb3Sn superconducting materials between 300 K and 7 K

    International Nuclear Information System (INIS)

    Nyilas, Arman; Osamura, Kozo; Sugano, Michinaka

    2003-01-01

    Within the framework of IEC/TC90-WG5 and VAMAS/TWA16, superconducting (SC) materials are investigated with respect to their mechanical properties between 300 K and 7 K. Besides the mechanical tests, physical and electrical properties are also determined for high T c SC-tapes. The mechanical tests comprised the characterization of tensile properties at ambient temperature as well as at 7 K of Nb 3 Sn-reacted strands, Bi2223 tapes, pure silver tapes, silver bars, silver alloy tapes and bare filaments extracted from Bi-2223 tapes. All these investigations are carried out using a variable temperature helium gas flow cryostat equipped with a servo hydraulic tensile machine (MTS, model 810). For the load measurements specially developed, highly sensitive cryogenic proof in situ working load cells are used. For the strain determination of the wires, a high resolution ultra-light double extensometer system with a specially developed low noise signal conditioner is used. The engineering parameters such as yield strength and elastic modulus are evaluated using the obtained data with newly developed software. For the tiny and brittle filaments load versus displacement data are obtained. A determined master line (Young's modulus versus machine compliance) established by thin 0.125 mm O wires of different pure metals is used for the Young's modulus estimation of filaments. For the 4 K electrical voltage-current measurements under magnetic fields of up to 13 T, an existing test facility is used for the high T c tapes. No dependency between applied strain up to 0.3% and the critical current under magnetic field could be observed for the selected specific Bi-2223 tapes. In addition, thermal expansion curves of Bi-2223 tapes along with pure silver and silver alloy (AgMg) are determined between 290 K and 7 K using in situ working extensometers. The coefficient of thermal expansion is evaluated by the determined thermal expansion versus temperature curve

  10. Direct synthesis of antimicrobial coatings based on tailored bi-elemental nanoparticles

    Directory of Open Access Journals (Sweden)

    Giulio Benetti

    2017-03-01

    Full Text Available Ultrathin coatings based on bi-elemental nanoparticles (NPs are very promising to limit the surface-related spread of bacterial pathogens, particularly in nosocomial environments. However, tailoring the synthesis, composition, adhesion to substrate, and antimicrobial spectrum of the coating is an open challenge. Herein, we report on a radically new nanostructured coating, obtained by a one-step gas-phase deposition technique, and composed of bi-elemental Janus type Ag/Ti NPs. The NPs are characterized by a cluster-in-cluster mixing phase with metallic Ag nano-crystals embedded in amorphous TiO2 and present a promising antimicrobial activity including also multidrug resistant strains. We demonstrate the flexibility of the method to tune the embedded Ag nano-crystals dimension, the total relative composition of the coating, and the substrate type, opening the possibility of tailoring the dimension, composition, antimicrobial spectrum, and other physical/chemical properties of such multi-elemental systems. This work is expected to significantly spread the range of applications of NPs coatings, not only as an effective tool in the prevention of healthcare-associated infections but also in other technologically relevant fields like sensors or nano-/micro joining.

  11. Direct synthesis of antimicrobial coatings based on tailored bi-elemental nanoparticles

    Science.gov (United States)

    Benetti, Giulio; Cavaliere, Emanuele; Canteri, Adalberto; Landini, Giulia; Rossolini, Gian Maria; Pallecchi, Lucia; Chiodi, Mirco; Van Bael, Margriet J.; Winckelmans, Naomi; Bals, Sara; Gavioli, Luca

    2017-03-01

    Ultrathin coatings based on bi-elemental nanoparticles (NPs) are very promising to limit the surface-related spread of bacterial pathogens, particularly in nosocomial environments. However, tailoring the synthesis, composition, adhesion to substrate, and antimicrobial spectrum of the coating is an open challenge. Herein, we report on a radically new nanostructured coating, obtained by a one-step gas-phase deposition technique, and composed of bi-elemental Janus type Ag/Ti NPs. The NPs are characterized by a cluster-in-cluster mixing phase with metallic Ag nano-crystals embedded in amorphous TiO2 and present a promising antimicrobial activity including also multidrug resistant strains. We demonstrate the flexibility of the method to tune the embedded Ag nano-crystals dimension, the total relative composition of the coating, and the substrate type, opening the possibility of tailoring the dimension, composition, antimicrobial spectrum, and other physical/chemical properties of such multi-elemental systems. This work is expected to significantly spread the range of applications of NPs coatings, not only as an effective tool in the prevention of healthcare-associated infections but also in other technologically relevant fields like sensors or nano-/micro joining.

  12. Quench Property of Twisted-Pair MgB$_2$ Superconducting Cables in Helium Gas

    CERN Document Server

    Spurrell, J; Falorio, I; Pelegrin, J; Ballarino, A; Yang, Y

    2015-01-01

    CERN's twisted-pair superconducting cable is a novel design which offers filament transposition, low cable inductance and is particularly suited for tape conductors such as 2G YBCO coated conductors, Ag-sheathed Bi2223 tapes and Ni/Monel-sheathed MgB2 tapes. A typical design of such twistedpair cables consists of multiple superconducting tapes intercalated with thin copper tapes as additional stabilizers. The copper tapes are typically not soldered to the superconducting tapes so that sufficient flexibility is retained for the twisting of the tape assembly. The electrical and thermal contacts between the copper and superconducting tapes are an important parameter for current sharing, cryogenic stability and quench propagation. Using an MgB2 twisted-pair cable assembly manufactured at CERN, we have carried out minimum quench energy (MQE) and propagation velocity (vp) measurements with point-like heat deposition localized within a tape. Furthermore, different contacts between the copper and superconductor aroun...

  13. Enhanced photocatalytic, electrochemical and photoelectrochemical properties of TiO{sub 2} nanotubes arrays modified with Cu, AgCu and Bi nanoparticles obtained via radiolytic reduction

    Energy Technology Data Exchange (ETDEWEB)

    Nischk, Michał [Department of Chemical Technology, Faculty of Chemistry, Gdansk University of Technology, 11/12 G. Narutowicza 11/12 St., 80-233 Gdansk (Poland); Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 63 Wita Stwosza St., 80-308 Gdansk (Poland); Mazierski, Paweł [Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 63 Wita Stwosza St., 80-308 Gdansk (Poland); Wei, Zhishun [Institute for Catalysis, Hokkaido University, N21, W10, 001-0021, Sapporo (Japan); Siuzdak, Katarzyna [Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdansk (Poland); Kouame, Natalie Amoin [Laboratoire de Chimie Physique, CNRS—UMR 8000,Université Paris-Sud, Université Paris-Saclay, Bâtiment 349, 91405 Orsay (France); Kowalska, Ewa [Institute for Catalysis, Hokkaido University, N21, W10, 001-0021, Sapporo (Japan); Remita, Hynd [Laboratoire de Chimie Physique, CNRS—UMR 8000,Université Paris-Sud, Université Paris-Saclay, Bâtiment 349, 91405 Orsay (France); Zaleska-Medynska, Adriana, E-mail: adriana.zaleska@ug.edu.pl [Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 63 Wita Stwosza St., 80-308 Gdansk (Poland)

    2016-11-30

    Highlights: • TiO{sub 2} nanotubes were modified with Cu, AgCu, Bi nanoparticles via gamma radiolysis. • Excessive amount of deposited metal decreased photocatalytic activity. • AgCu-modified samples were more active than Cu-modified (with the same Cu content). • AgCu nanoparticles exist in a core{sub (Ag)}-shell{sub (Cu)} form. • Examined photocatalysts were resistant towards photocorrosion processes. - Abstract: TiO{sub 2} nanotubes arrays (NTs), obtained via electrochemical anodization of Ti foil, were modified with monometallic (Cu, Bi) and bimetallic (AgCu) nanoparticles. Different amounts of metals’ precursors were deposited on the surface of NTs by the spin-coating technique, and the reduction of metals was performed via gamma radiolysis. Surface modification of titania was studied by EDS and XPS analysis. The results show that AgCu nanoparticles exist in a Ag{sub core}-Cu{sub shell} form. Photocatalytic activity was examined under UV irradiation and phenol was used as a model pollutant of water. Over 95% of phenol degradation was achieved after 60 min of irradiation for almost all examined samples, but only slight difference in degradation efficiency (about 3%) between modified and bare NTs was observed. However, the initial phenol degradation rate and TOC removal efficiency was significantly enhanced for the samples modified with 0.31 and 0.63 mol% of Bi as well as for all the samples modified with Cu and AgCu nanoparticles in comparison with bare titania nanotubes. The saturated photocurrent, under the influence of simulated solar light irradiation, for the most active Bi- and AgCu-modified samples, was over two times higher than for pristine NTs. All the examined materials were resistant towards photocorrosion processes that enables their application for long term processes induced by light.

  14. Effect of impregnation of ZrO2 on the chemical stability and the superconductivity of Y- and Bi-systems

    International Nuclear Information System (INIS)

    Muroya, Masaaki; Minamiyama, Hideaki

    1994-01-01

    The results are given concerning the influence of impregnation of Zr on chemical stability and superconductivity of YBa 2 (Cu 1-x · Zr x ) 3 O 7-y (123-system) and Bi 1.84 Zr x Pb 0.34 Sr 1.91 Ca 2.03 Cu 3.06 O y (2223-system) superconductors, when the samples are contacted with the solutions of acid (pH3), distilled water (pH5.6) and base (pH9), where x = 0-0.35. It is concluded that the low chemical stability was found in the case of YBZCO, barium hydroxide and/or barium carbonate were precipitated into the solutions, even though mechanical strength was increased by impregnation of Zr, and the chemical stability of Bi-system is high compared with that of the Y-system. 8 refs., 5 figs

  15. Self-field AC losses and critical currents in multi-tube Ag-Bi-2223 conductors

    Energy Technology Data Exchange (ETDEWEB)

    Ciszek, M; Ashworth, S P; Campbell, A M [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); James, M P; Glowacki, B A [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Garre, R; Conti, S [Centro Ricerche Europa Metalli, Fornaci di Barga, LU (Italy)

    1996-05-01

    The purpose of this work was to investigate the influence of different technological treatments of silver sheathed Bi-2223 tapes on the critical current density and the AC transport losses. The tapes were produced using the 'tube-in-tube' technique, by including a silver rod in the centre of the superconducting powder during packing of the silver tube. The aim of the process is to increase the silver to superconductor surface area and thus also the alignment at the centre of the conductor ceramic core. AC transport losses were measured by means of an electrical method using sinusoidally varying currents in the frequency range 30-180 Hz. In this range the power losses are hysteretic. The measured variation in losses from those predicted by a critical state model is attributed to the complex geometry of superconducting regions existing in these tapes. (author)

  16. Superconducting glass-ceramics in BiSrCaCu2Al0.5Ox---Comparison between rod and powder compacted specimens

    International Nuclear Information System (INIS)

    Hirata, K.; Abe, Y.

    1991-01-01

    Superconducting properties are studied for glass-ceramics which were prepared by reheating glass rods and the glass powder compacts in the BiSrCaCu 2 Al 0.5 O x system, respectively. The glass-ceramic rod specimens obtained by reheating rod glass at 800--830 degree C for 50 h have a T c (R=0) of 85 K, while the disk specimens obtained by reheating the powered glass compacts in the same way do not exhibit superconductivity above 77 K. This difference in superconductivity between the specimens is discussed in terms of crystallization process and the amount of oxygen absorption of the specimens during heating

  17. How to improve J(c(T)) in Ag/(BiPb)2Sr2Ca2Cu3O10 tapes

    Science.gov (United States)

    Karkut, M.; Fossheim, K.

    1994-06-01

    We consider how to improve the magnetic field dependence of the critical current density J(c) in Ag/BSCCO superconducting tapes. First we look at mechanisms that provide pinning in the oxide superconductors and then consider the special problems that one encounters with Ag/BSCCO tapes. We propose several testable propositions to be performed in collaboration with NKT, Denmark and Tampere University, Finland.

  18. Microstructure and adhesion strength of Sn-9Zn-1.5Ag-xBi (x = 0 wt% and 2 wt%)/Cu after electrochemical polarization in a 3.5 wt% NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Li, W.-L. [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Chen, Y.-R.; Chang, K.-M. [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Liu, C.-Y.; Hon, M.-H. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Wang, M.-C. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shihchuan 1st Road, Kaohsiung 80728, Taiwan (China)], E-mail: mcwang@kmu.edu.tw

    2008-08-11

    The microstructure and adhesion strength of the Sn-9Zn-1.5Ag-xBi (x = 0 wt% and 2 wt%)/Cu interface after electrochemical polarization have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and pull-off testing. The equilibrium potentials of Sn-9Zn-1.5Ag/Cu and Sn-9Zn-1.5Ag-2Bi/Cu are -1.31 V{sub sce} and -1.22 V{sub sce}, respectively, indicating that Sn-9Zn-1.5Ag-2Bi/Cu has a better corrosion resistance than that of Sn-9Zn-1.5Ag/Cu. The intermetallic compounds of Cu{sub 6}Sn{sub 5}, Cu{sub 5}Zn{sub 8} and Ag{sub 3}Sn are formed at the soldered interface between the Sn-9Zn-1.5Ag-xBi solder alloy and the Cu substrate. The scallop-shaped Cu{sub 6}Sn{sub 5} is close to the Cu substrate and the scallop-shaped Cu{sub 5}Zn{sub 8} is found at the interface in the solder matrix after soldering at 250 deg. C for 10 s. The corrosion products are ZnCl{sub 2}, SnCl{sub 2} and ZnO. On the other hand, pits are also formed on the surface of both solder alloys. The interfacial adhesion strength of the Sn-9Zn-1.5Ag/Cu and Sn-9Zn-1.5Ag-2Bi/Cu decreases from 8.27 {+-} 0.56 MPa and 12.67 {+-} 0.45 MPa to 4.78 {+-} 0.45 MPa and 8.14 {+-} 0.38 MPa, respectively, after electrochemical polarization in a 3.5 wt% NaCl solution. The fracture path of the Sn-9Zn-1.5Ag-2Bi/Cu is along the solder alloy/ZnO and solder/Cu{sub 6}Sn{sub 5} interfaces.

  19. A study on the development of high Tc superconducting materials and on the effects of neutron irradiation

    International Nuclear Information System (INIS)

    Won, Dong Yeon; Chang, In Soon; Lee, Jong Min

    1990-08-01

    An Ag-sheathed (Pb,Bi)SrCaCuO superconducting tape was prepared by the cold rolling and post heat treatment method. The tape shows a c-oriented texture perpendicular to the rolling direction. The aligned grain structure may be resulted from the anisotropic grain growth of the high Tc superconducting phase. The bulk (Pb,Bi)SrCaCuO samples with (a) Tc=10lK and (b) 96K were prepared by the solid state reaction method and were neutron-irradiated up to 1.5 x 10 1 8 n/cm 2 . After irradiation the zero resistance temperature(Tc) of (a) was decreased to 96K but (b) did not show any change in Tc. The critical current density of (a) also decreased from 0.75A/cm 2 but (b) was constant as 1.5 A/cm 2 after irradiation. (Author)

  20. Highly oriented Bi-system bulk sample prepared by a decomposition-crystallization process

    International Nuclear Information System (INIS)

    Xi Zhengping; Zhou Lian; Ji Chunlin

    1992-01-01

    A decomposition-crystallization method, preparing highly oriented Bi-system bulk sample is reported. The effects of processing parameter, decomposition temperature, cooling rate and post-treatment condition on texture and superconductivity are investigated. The method has successfully prepared highly textured Bi-system bulk samples. High temperature annealing does not destroy the growing texture, but the cooling rate has some effect on texture and superconductivity. Annealing in N 2 /O 2 atmosphere can improve superconductivity of the textured sample. The study on the superconductivity of the Bi(Pb)-Sr-Ca-Cu-O bulk material has been reported in numerous papers. The research on J c concentrates on the tape containing the 2223 phase, with very few studies on the J c of bulk sample. The reason for the lack of studies is that the change of superconducting phases at high temperatures has not been known. The authors have reported that the 2212 phase incongruently melted at about 875 degrees C and proceeded to orient the c-axis perpendicular to the surface in the process of crystallization of the 2212 phase. Based on that result, a decomposition-crystallization method was proposed to prepare highly oriented Bi-system bulk sample. In this paper, the process is described in detail and the effects of processing parameters on texture and superconductivity are reported

  1. Single Crystal Growth and Superconducting Properties of Antimony-Substituted NdO0.7F0.3BiS2

    Directory of Open Access Journals (Sweden)

    Satoshi Demura

    2017-12-01

    Full Text Available Antimony (Sb substitution of less than 8% was examined on a single crystal of a layered superconductor NdO0.7F0.3BiS2. The superconducting transition temperature of the substituted samples decreased as Sb concentration increased. A lattice constant along the c-axis showed a large decrease compared with that along the a-axis. Since in-plane chemical pressure monotonically decreased as Sb concentration increased, the suppression of the superconductivity is attributed to the decrease in the in-plane chemical pressure.

  2. Influence of transverse compressive stress on Ic degradation of Ag alloy sheathed Bi-2223 tapes

    International Nuclear Information System (INIS)

    Oh, S S; Ha, D W; Ha, H S; Park, C; Kwon, Y K; Ryu, K S; Shin, H S

    2004-01-01

    In order to investigate the degradation of critical current (I c ) in the Ag alloy sheathed Bi-2223 tapes due to a transverse compressive stress introduced during manufacturing and operation of the HTS systems, a sample holder consisting of the upper block made of Ti alloy and the lower support plate made of glass fibre reinforced plastic was prepared. A shorter spacing of voltage taps caused large degradation of critical current with respect to compressive stress. It was found that the extent of the I c degradation is proportional to the initial critical current density of the tapes. Through the experiment optimizing the shape of voltage terminals and the pressing load for the continuous contact type 4-probe I c measurement system, it was found that the conical shape tip with large curvature radius was effective in suppressing the I c degradation in Bi-2223 tapes during the I c measurement. A hard alloy sheath of Ag-0.6wt%Mn was found to be quite tolerant to the I c degradation against the pressing load of voltage terminals

  3. Tl, Bi, and Pb doping in Ba4BiPb2TlO12-δ

    International Nuclear Information System (INIS)

    Sutto, T.E.; Averill, B.A.

    1992-01-01

    To determine the effects of different 6s metal concentrations on the superconducting nature of Ba 4 BiPb 2 TlO 12-δ , materials produced via four doping schemes were examined: Ba 4 Bi(Pb, Tl) 3 O 12-δ , Ba 4 -(BiPb) 3 TlO 12-δ , Ba 4 (Bi,Tl) 2 Pb 2 O 12-δ , and Ba 4 Bi x Pb 4-2x Tl x O 12-δ . For the parent compound a value of δ = 0.91 was observed, indicating that approximately 1/4 oxygen atom was missing per cubic subsection of the unit cell. For all samples, the symmetry of the parent compound changed from orthorhombic to tetragonal as the system moved away from the ideal composition. This was usually accompanied by the loss of superconductivity, which exhibited a maximum T c of 10.5 K for the parent compound Ba 4 BiPb 2 TlO 12-δ . Also reported are high-temperature magnetic susceptibility results, which are used to determine the effect of metal substitution on the density of states at the Fermi level. For each set of variants on the parent composition, the onset of superconductivity was accompanied by a significant decrease in the size of the Pauli paramagnetic signal. 16 refs., 6 figs

  4. The preparation and characterization of Bi-2212 film on Ag substrate by dip-coating method

    International Nuclear Information System (INIS)

    Song Yang; Zhao Liang; Li Pei; Qu Timing; Huang Yong; Han Zhenghe

    2006-01-01

    In this paper we report on the processing parameters and resulting critical current densities of Bi 2 Sr 2 Ca 1 Cu 2 O x thick films on Ag substrate. Bi-2212 tapes and wires are prepared by dip-coating method. It is found that parameters during partial melting (maximum process temperature T max and solidification temperature T s ) have strong influences on the transition temperature T c . The 0.5 mm diameter dip-coated wire can carry 4000 A/cm 2 critical current in 77 K, self field. Post-annealing on different temperatures and atmospheres are studied as well to obtain varied T c samples

  5. Analysis of thermodynamic properties for high-temperature superconducting oxides

    International Nuclear Information System (INIS)

    Kushwah, S.S.; Shanker, J.

    1993-01-01

    Analysis of thermodynamic properties such as specific heat, Debye temperature, Einstein temperature, thermal expansion coefficient, bulk modulus, and Grueneisen parameter is performed for rare-earth-based, Tl-based, and Bi-based superconducting copper oxides. Values of thermodynamic parameters are calculated and reported. The relationship between the Debye temperature and the superconducting transition temperature is used to estimate the values of T c using the interaction parameters from Ginzburg. (orig.)

  6. Research on laser cladding control system based on fuzzy PID

    Science.gov (United States)

    Zhang, Chuanwei; Yu, Zhengyang

    2017-12-01

    Laser cladding technology has a high demand for control system, and the domestic laser cladding control system mostly uses the traditional PID control algorithm. Therefore, the laser cladding control system has a lot of room for improvement. This feature is suitable for laser cladding technology, Based on fuzzy PID three closed-loop control system, and compared with the conventional PID; At the same time, the laser cladding experiment and friction and wear experiment were carried out under the premise of ensuring the reasonable control system. Experiments show that compared with the conventional PID algorithm in fuzzy the PID algorithm under the surface of the cladding layer is more smooth, the surface roughness increases, and the wear resistance of the cladding layer is also enhanced.

  7. Experimental evidence for s-wave pairing symmetry in superconducting Cu(x)Bi2Se3 single crystals using a scanning tunneling microscope.

    Science.gov (United States)

    Levy, Niv; Zhang, Tong; Ha, Jeonghoon; Sharifi, Fred; Talin, A Alec; Kuk, Young; Stroscio, Joseph A

    2013-03-15

    Topological superconductors represent a newly predicted phase of matter that is topologically distinct from conventional superconducting condensates of Cooper pairs. As a manifestation of their topological character, topological superconductors support solid-state realizations of Majorana fermions at their boundaries. The recently discovered superconductor Cu(x)Bi(2)Se(3) has been theoretically proposed as an odd-parity superconductor in the time-reversal-invariant topological superconductor class, and point-contact spectroscopy measurements have reported the observation of zero-bias conductance peaks corresponding to Majorana states in this material. Here we report scanning tunneling microscopy measurements of the superconducting energy gap in Cu(x)Bi(2)Se(3) as a function of spatial position and applied magnetic field. The tunneling spectrum shows that the density of states at the Fermi level is fully gapped without any in-gap states. The spectrum is well described by the Bardeen-Cooper-Schrieffer theory with a momentum independent order parameter, which suggests that Cu(x)Bi(2)Se(3) is a classical s-wave superconductor contrary to previous expectations and measurements.

  8. Bandgap engineering of lead-free double perovskite Cs{sub 2}AgBiBr{sub 6} through trivalent metal alloying

    Energy Technology Data Exchange (ETDEWEB)

    Du, Ke-zhao; Mitzi, David B. [Department of Mechanical Engineering and Materials Science, and Department of Chemistry, Duke University, Durham, NC (United States); Meng, Weiwei; Wang, Xiaoming; Yan, Yanfa [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, OH (United States)

    2017-07-03

    The double perovskite family, A{sub 2}M{sup I}M{sup III}X{sub 6}, is a promising route to overcome the lead toxicity issue confronting the current photovoltaic (PV) standout, CH{sub 3}NH{sub 3}PbI{sub 3}. Given the generally large indirect band gap within most known double perovskites, band-gap engineering provides an important approach for targeting outstanding PV performance within this family. Using Cs{sub 2}AgBiBr{sub 6} as host, band-gap engineering through alloying of In{sup III}/Sb{sup III} has been demonstrated in the current work. Cs{sub 2}Ag(Bi{sub 1-x}M{sub x})Br{sub 6} (M=In, Sb) accommodates up to 75 % In{sup III} with increased band gap, and up to 37.5 % Sb{sup III} with reduced band gap; that is, enabling ca. 0.41 eV band gap modulation through introduction of the two metals, with smallest value of 1.86 eV for Cs{sub 2}Ag(Bi{sub 0.625}Sb{sub 0.375})Br{sub 6}. Band structure calculations indicate that opposite band gap shift directions associated with Sb/In substitution arise from different atomic configurations for these atoms. Associated photoluminescence and environmental stability of the three-metal systems are also assessed. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Quench characteristics of Ag/AuBi2223 HTS-stainless steel stack used for the hybrid current leads of the large hadron collider

    CERN Document Server

    Al-Mosawi, M K; Beduz, C; Yang, Y; Ballarino, A

    2008-01-01

    The quench characteristics of Ag/Au sheathed Bi2223 tapes have been investigated in an adiabatic condition and in a configuration similar to that used in hybrid high temperature superconducting current leads, namely the 13000A leads used for the Large Hadron Collider at CERN. A specialised rig was designed and constructed to provide a carefully controlled environment. The samples were prepared from HTS tape soldered onto a stainless steel substrate with a number of temperature sensors at various positions along the length of tape. One end of the lead (cold end) was maintained at 6K using G-M cryo-cooler whereas the temperature of the other end (warm end) can be varied and maintained at temperatures up to 100K. The thermal runaway currents (quench currents) at various warm end temperatures (in the range of 40-100K) were determined. The temperature evolutions at various locations along the tape were recorded at different top end temperatures and currents. The effect of the stainless steel mechanical reinforceme...

  10. Superconducting Properties of Lead-Bismuth Films Controlled by Ferromagnetic Nanowire Arrays

    Science.gov (United States)

    Ye, Zuxin; Lyuksyutov, Igor F.; Wu, Wenhao; Naugle, Donald G.

    2011-03-01

    Superconducting properties of lead-bismuth (82% Pb and 18% Bi) alloy films deposited on ferromagnetic nanowire arrays have been investigated. Ferromagnetic Co or Ni nanowires are first electroplated into the columnar pores of anodic aluminum oxide (AAO) membranes. Superconducting Pb 82 Bi 18 films are then quench-condensed onto the polished surface of the AAO membranes filled with magnetic nanowires. A strong dependence of the Pb 82 Bi 18 superconducting properties on the ratio of the superconducting film thickness to the magnetic nanowire diameter and the material variety was observed.

  11. Facet Engineered Interface Design of Plasmonic Metal and Cocatalyst on BiOCl Nanoplates for Enhanced Visible Photocatalytic Oxygen Evolution.

    Science.gov (United States)

    Bai, Lijie; Ye, Fan; Li, Luna; Lu, Jingjing; Zhong, Shuxian; Bai, Song

    2017-10-01

    Integration of plasmonic metal and cocatalyst with semiconductor is a promising approach to simultaneously optimize the generation, transfer, and consumption of photoinduced charge carriers for high-performance photocatalysis. The photocatalytic activities of the designed hybrid structures are greatly determined by the efficiencies of charge transfer across the interfaces between different components. In this paper, interface design of Ag-BiOCl-PdO x hybrid photocatalysts is demonstrated based on the choice of suitable BiOCl facets in depositing plasmonic Ag and PdO x cocatalyst, respectively. It is found that the selective deposition of Ag and PdO x on BiOCl(110) planes realizes the superior photocatalytic activity in O 2 evolution compared with the samples with other Ag and PdO x deposition locations. The reason was the superior hole transfer abilities of Ag-(110)BiOCl and BiOCl(110)-PdO x interfaces in comparison with those of Ag-(001)BiOCl and BiOCl(001)-PdO x interfaces. Two effects are proposed to contribute to this enhancement: (1) stronger electronic coupling at the BiOCl(110)-based interfaces resulted from the thinner contact barrier layer and (2) the shortest average hole diffuse distance realized by Ag and PdO x on BiOCl(110) planes. This work represents a step toward the interface design of high-performance photocatalyst through facet engineering. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Laser Cladding of Ultra-Thin Nickel-Based Superalloy Sheets

    Directory of Open Access Journals (Sweden)

    Tobias Gabriel

    2017-03-01

    Full Text Available Laser cladding is a well-established process to apply coatings on metals. However, on substrates considerably thinner than 1 mm it is only rarely described in the literature. In this work 200 µm thin sheets of nickel-based superalloy 718 are coated with a powder of a cobalt-based alloy, Co–28Cr–9W–1.5Si, by laser cladding. The process window is very narrow, therefore, a precisely controlled Yb fiber laser was used. To minimize the input of energy into the substrate, lines were deposited by setting single overlapping points. In a design of experiments (DoE study, the process parameters of laser power, laser spot area, step size, exposure time, and solidification time were varied and optimized by examining the clad width, weld penetration, and alloying depth. The microstructure of the samples was investigated by optical microscope (OM and scanning electron microscopy (SEM, combined with electron backscatter diffraction (EBSD and energy dispersive X-ray spectroscopy (EDX. Similarly to laser cladding of thicker substrates, the laser power shows the highest influence on the resulting clad. With a higher laser power, the clad width and alloying depth increase, and with a larger laser spot area the weld penetration decreases. If the process parameters are controlled precisely, laser cladding of such thin sheets is manageable.

  13. Laser Cladding of Ultra-Thin Nickel-Based Superalloy Sheets.

    Science.gov (United States)

    Gabriel, Tobias; Rommel, Daniel; Scherm, Florian; Gorywoda, Marek; Glatzel, Uwe

    2017-03-10

    Laser cladding is a well-established process to apply coatings on metals. However, on substrates considerably thinner than 1 mm it is only rarely described in the literature. In this work 200 µm thin sheets of nickel-based superalloy 718 are coated with a powder of a cobalt-based alloy, Co-28Cr-9W-1.5Si, by laser cladding. The process window is very narrow, therefore, a precisely controlled Yb fiber laser was used. To minimize the input of energy into the substrate, lines were deposited by setting single overlapping points. In a design of experiments (DoE) study, the process parameters of laser power, laser spot area, step size, exposure time, and solidification time were varied and optimized by examining the clad width, weld penetration, and alloying depth. The microstructure of the samples was investigated by optical microscope (OM) and scanning electron microscopy (SEM), combined with electron backscatter diffraction (EBSD) and energy dispersive X-ray spectroscopy (EDX). Similarly to laser cladding of thicker substrates, the laser power shows the highest influence on the resulting clad. With a higher laser power, the clad width and alloying depth increase, and with a larger laser spot area the weld penetration decreases. If the process parameters are controlled precisely, laser cladding of such thin sheets is manageable.

  14. Superconducting tin core fiber

    International Nuclear Information System (INIS)

    Homa, Daniel; Liang, Yongxuan; Hill, Cary; Kaur, Gurbinder; Pickrell, Gary

    2015-01-01

    In this study, we demonstrated superconductivity in a fiber with a tin core and fused silica cladding. The fibers were fabricated via a modified melt-draw technique and maintained core diameters ranging from 50-300 microns and overall diameters of 125-800 microns. Superconductivity of this fiber design was validated via the traditional four-probe test method in a bath of liquid helium at temperatures on the order of 3.8 K. The synthesis route and fiber design are perquisites to ongoing research dedicated all-fiber optoelectronics and the relationships between superconductivity and the material structures, as well as corresponding fabrication techniques. (orig.)

  15. Induced critical current density limit of Ag sheathed Bi-2223 tape conductor

    International Nuclear Information System (INIS)

    Ogiwara, H.; Satou, M.; Yamada, Y.; Kitamura, T.; Hasegawa, T.

    1994-01-01

    The authors have already reported the best critical current density of 66,000 A/cm 2 with an Ag sheathed Bi-2223 tape conductor. The Brick-wall model is for explaining the current transport mechanism of this conductor. The model has its roots in the fact that the Bi-2223 tape core is a complicated stack of crystals which have a mica-flake structure. The orientation of the crystals which have a mica-flake structure. The orientation of the crystals seriously affects the current transport capability. Moreover, the contacts between the stacking crystals are very important. The transport current flows dividing into many branch paths. Under high magnetic field, the different paths experienced different electromagnetic forces. Differences between the electromagnetic forces on the different crystals can affect the contacts so as to increase resistivity and decrease overall critical current density of the tape. This effect can foretell the limit of the critical current density obtainable with these kinds of conductors

  16. Applied rolling and sensitivity of Bi(2223)/Ag tapes on Ic degradation by mechanical stress

    International Nuclear Information System (INIS)

    Kovac, P.; Bukva, P.; Husek, I.; Richens, P.E.; Jones, H.

    1999-01-01

    An experimental study of multicore Bi(2223)/Ag tapes, roll-sintered by different methods and subjected to bending and tension stresses has been performed. The tapes, of various technological histories, were bent and tensioned and subsequently the transport current was measured at each stressed state. Comparison of I c degradation curves shows that applied rolling may influence the sensitivity of Bi-2223 filaments against the mechanical stress. The existence of transverse microcracks caused by intermediate rolling leads to a higher sensitivity of the tape to bending. A lowering of critical current degradation was observed for two-axially rolled tapes having a higher filament density and better homogeneity prior to sintering treatment. (author)

  17. Comparison of self-field effects between Bi-2223/Ag tapes and pancake coils

    International Nuclear Information System (INIS)

    Alamgir, A.K.M.; Gu, C.; Han, Z.

    2005-01-01

    Knowledge on self-field behavior in HTS tape and coil becomes important for the design of HTS devices. We report on the comparative nature and influence of self-field in Bi-2223/Ag tape and pancake coils in terms of critical current and ac loss. Measured dc and ac properties of short tape and pancake coils are verified based on the self-field. It is proved that perpendicular component of self-field acting in opposite direction at the two halves of tape-width determines critical current in short tape and single-turn coil. On the other hand, perpendicular component of self-field pointed in the same direction at the two halves of tape-width determines critical current in multi-turn coils. Influence of magnitude and orientation of self-field on ac loss is also investigated for a series of pancake coils based on the measured self-field ac loss in short sample

  18. Comparison of self-field effects between Bi-2223/Ag tapes and pancake coils

    Energy Technology Data Exchange (ETDEWEB)

    Alamgir, A.K.M. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Building Li Zhai, Room 209, Beijing 100084 (China)]. E-mail: alam643@yahoo.com; Gu, C. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Building Li Zhai, Room 209, Beijing 100084 (China); Han, Z. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Building Li Zhai, Room 209, Beijing 100084 (China)

    2005-08-15

    Knowledge on self-field behavior in HTS tape and coil becomes important for the design of HTS devices. We report on the comparative nature and influence of self-field in Bi-2223/Ag tape and pancake coils in terms of critical current and ac loss. Measured dc and ac properties of short tape and pancake coils are verified based on the self-field. It is proved that perpendicular component of self-field acting in opposite direction at the two halves of tape-width determines critical current in short tape and single-turn coil. On the other hand, perpendicular component of self-field pointed in the same direction at the two halves of tape-width determines critical current in multi-turn coils. Influence of magnitude and orientation of self-field on ac loss is also investigated for a series of pancake coils based on the measured self-field ac loss in short sample.

  19. The reaction process of the Bi-Sr-Ca-Cu-O system and the forming mechanism of the 2212 superconducting phase

    International Nuclear Information System (INIS)

    Xiong Guohong; Wang Minquan; Fan Xianping; Tang Xiaoming

    1993-01-01

    The reaction process and the reaction behavior of each component in the Bi-Sr-Ca-Cu-O system are presented in this paper. It reveals that the reaction is carried out in three different stages: forming of an insulating interphase at 680 C-790 C, forming of the 2212 superconducting phase at 790 C-860 C and forming of semiconducting phases in the presence of the liquid phase at 860 C-970 C. It is also confirmed that the 2212 superconducting phase (T c =85 K) is formed by the reaction of a trinary interphase together with CuO, SrO and CaO. A new two-step method is presented to prepare the 2212 superconducting phase by a presynthesized interphase. (orig.)

  20. The reaction process of the Bi-Sr-Ca-Cu-O system and the forming mechanism of the 2212 superconducting phase

    Science.gov (United States)

    Xiong, Guohong; Wang, Minquan; Fan, Xianping; Tang, Xiaoming

    1993-02-01

    The reaction process and the reaction behavior of each component in the Bi-Sr-Ca-Cu-O system are presented in this paper. It reveals that the reaction is carried out in three different stages: forming of an insulating interphase at 680°C 790°C, forming of the 2212 superconducting phase at 790°C 860°C and forming often semiconducting phases in the presence of the liquid phase at 860°C 970°C. It is also confirmed that the 2212 superconducting phase ( T c=85 K) is formed by the reaction of a trinary interphase together with CuO, SrO and CaO. A new two-step method is presented to prepare the 2212 superconducting phase by a presynthesized interphase.

  1. The reaction process of the Bi-Sr-Ca-Cu-O system and the forming mechanism of the 2212 superconducting phase

    Energy Technology Data Exchange (ETDEWEB)

    Xiong Guohong (Zhejiang Univ., Hangzhou (China). Dept. of Materials Science and Engineering); Wang Minquan (Zhejiang Univ., Hangzhou (China). Dept. of Materials Science and Engineering); Fan Xianping (Zhejiang Univ., Hangzhou (China). Dept. of Materials Science and Engineering); Tang Xiaoming (Zhejiang Univ., Hangzhou (China). Center for Analysis and Measurement)

    1993-02-01

    The reaction process and the reaction behavior of each component in the Bi-Sr-Ca-Cu-O system are presented in this paper. It reveals that the reaction is carried out in three different stages: forming of an insulating interphase at 680 C-790 C, forming of the 2212 superconducting phase at 790 C-860 C and forming of semiconducting phases in the presence of the liquid phase at 860 C-970 C. It is also confirmed that the 2212 superconducting phase (T[sub c]=85 K) is formed by the reaction of a trinary interphase together with CuO, SrO and CaO. A new two-step method is presented to prepare the 2212 superconducting phase by a presynthesized interphase. (orig.)

  2. Superconducting Helical Snake Magnet for the AGS

    CERN Document Server

    Willen, Erich; Escallier, John; Ganetis, George; Ghosh, Arup; Gupta, Ramesh C; Harrison, Michael; Jain, Animesh K; Luccio, Alfredo U; MacKay, William W; Marone, Andrew; Muratore, Joseph F; Okamura, Masahiro; Plate, Stephen R; Roser, Thomas; Tsoupas, Nicholaos; Wanderer, Peter

    2005-01-01

    A superconducting helical magnet has been built for polarized proton acceleration in the Brookhaven AGS. This "partial Snake" magnet will help to reduce the loss of polarization of the beam due to machine resonances. It is a 3 T magnet some 1940 mm in magnetic length in which the dipole field rotates with a pitch of 0.2053 degrees/mm for 1154 mm in the center and a pitch of 0.3920 degrees/mm for 393 mm in each end. The coil cross-section is made of two slotted cylinders containing superconductor. In order to minimize residual offsets and deflections of the beam on its orbit through the Snake, a careful balancing of the coil parameters was necessary. In addition to the main helical coils, a solenoid winding was built on the cold bore tube inside the main coils to compensate for the axial component of the field that is experienced by the beam when it is off-axis in this helical magnet. Also, two dipole corrector magnets were placed on the same tube with the solenoid. A low heat leak cryostat was built so that t...

  3. Preparation of nickel-based amorphous alloys with finely dispersed lead and lead-bismuth particles and their superconducting properties

    International Nuclear Information System (INIS)

    Inoue, A.; Oguchi, M.; Harakawa, Y.; Masumoto, T.; Matsuzaki, K.

    1986-01-01

    The application of the melt-quenching technique to Ni-Si-B-Pb, Ni-P-B-Pb, Ni-Si-B-Pb-Bi and Ni-P-B-Pb-Bi alloys containing immiscible elements such as lead and bismuth has been tried and it has been found to result in the formation of a new type of material consisting of fine fcc Pb or hcp epsilon(Pb-Bi) + bct X(Pb-Bi) particles dispersed uniformly in the nickel-based amorphous matrix. The particle size and interparticle distance were 1 to 3 and 1 to 4 μm, respectively, for the lead phase, and less than 0.2 to 0.5 μm and 0.2 to 1.0 μm for the Pb-Bi phase. The uniform dispersion of such fine particles into the amorphous matrix was achieved in the composition range below about 6 at% Pb and 7 at% (Pb+Bi). Additionally, these amorphous alloys have been found to exhibit a superconductivity by the proximity effect of fcc Pb or epsilon(Pb-Bi) superconducting particles. The transition temperature Tsub(c) was in the range 6.8 to 7.5 K for the Ni-Si (or P)-B-Pb alloys and 8.6 to 8.8 K for the Ni-Si (or P)-B-Pb-Bi alloys. The upper critical field Hsub(c2) and the critical current density Jsub(c) for (Nisub(0.8)Psub(0.1)Bsub(0.1)) 95 Pb 3 Bi 2 at 4.2 K were, respectively, about 1.6 T and of the order of 7 x 10 7 Am -2 at zero applied field. (author)

  4. Cryocooled superconducting magnets for high magnetic fields at the HFLSM and future collaboration with the TML

    International Nuclear Information System (INIS)

    Watanabe, K; Nishijima, G; Awaji, S; Koyama, K; Takahashi, K; Kobayashi, N; Kiyoshi, T

    2006-01-01

    A hybrid magnet needs a large amount of liquid helium for operation. In order to make an easy-to-operate hybrid magnet system, we constructed a cryocooled 28 T hybrid magnet, consisting of an outer cryocooled 10 T superconducting magnet and an inner traditional water-cooled 19 T resistive magnet. As a performance test, the cryocooled hybrid magnet generated 27.5 T in a 32 mm room temperature experimental bore. As long as Nb3Sn superconducting wires are employed, the expected maximum high field generation in the cryocooled superconducting magnet will be 17 T at 5 K. We adopted the high temperature superconducting insert coil, employing Ag-sheathed Bi 2 Sr 2 Ca 2 Cu 3 O 10 superconducting tape. In combination with the low temperature 16.5 T back-up coil with a 174 mm cold bore, the cryocooled high temperature superconducting magnet successfully generated the total central field of 18.1 T in a 52 mm room temperature bore. As a next step, we start the collaboration with the National Institute for Materials Science for the new developmental works of a 30 T high temperature superconducting magnet and a 50 T-class hybrid magnet

  5. High-pressure band-gap engineering in lead-free Cs{sub 2}AgBiBr{sub 6} double perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qian [Department of Chemistry, Southern University of Science and Technology, SUSTech, Shenzhen, Guangdong (China); College of Chemistry, Nankai University, Tianjin (China); Wang, Yonggang; Yang, Wenge [High Pressure Synergetic Consortium, HPSynC, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, IL (United States); Pan, Weicheng; Tang, Jiang [Wuhan National Laboratory for Optoelectronics, WNLO and School of Optical and Electronic Information, Huazhong University of Science and Technology, HUST, Wuhan (China); Zou, Bo [State Key Laboratory of Superhard Materials, Jilin University, Changchun (China); Quan, Zewei [Department of Chemistry, Southern University of Science and Technology, SUSTech, Shenzhen, Guangdong (China)

    2017-12-11

    Novel inorganic lead-free double perovskites with improved stability are regarded as alternatives to state-of-art hybrid lead halide perovskites in photovoltaic devices. The recently discovered Cs{sub 2}AgBiBr{sub 6} double perovskite exhibits attractive optical and electronic features, making it promising for various optoelectronic applications. However, its practical performance is hampered by the large band gap. In this work, remarkable band gap narrowing of Cs{sub 2}AgBiBr{sub 6} is, for the first time, achieved on inorganic photovoltaic double perovskites through high pressure treatments. Moreover, the narrowed band gap is partially retainable after releasing pressure, promoting its optoelectronic applications. This work not only provides novel insights into the structure-property relationship in lead-free double perovskites, but also offers new strategies for further development of advanced perovskite devices. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Elaboration and characterization of silver sheathed YBaCuO and BiSrCaCuO wires

    International Nuclear Information System (INIS)

    Regnier, P.; Chaffron, L.; Schmirgeld, L.

    1990-01-01

    We report on our recent progress in the elaboration of silver sheathed high-Tc superconducting wires. It is shown that careful optimization of the swaging and pressing stages leads to a compacity of nearly 100% for the green ceramic, which considerably reduces the problem of its shrinkage in the silver clad during sintering, and consequently increases the critical current density far above 10 3 A/cm 2 at 77 K. Electrical and microstructural characterization of the wires are presented and compared with other published data. In particular, for both YBaCuO and BiSrCaCuO ribbons, it is shown that the thinner the ribbon the higher the critical current density. But this effect is much more pronounced for BiSrCaCuO because, due to partial melting of the former ceramic during the elaboration process, there is a pronounced enhancement of its texture as its thickness is reduced

  7. Ac susceptibility studies on Bi-Sr-Ca-Cu-O system

    International Nuclear Information System (INIS)

    Chakravarti, Arani; Mukherjee, C.D.; Ranganathan, R.; Chatterjee, N.; Raychaudhuri, A.K.

    1991-01-01

    We report the low a.c. susceptibility data χ'(T,Hsub(rms)), χsup(double inverted commas)(T,Hsub(rms)) for the newly prepared superconducting system Bi x Sr 4 Ca 2 Cu 4 O y (x=0.5, 1.0 and 1.5) containing Bi at concentrations lower than that in the conventional Bi-based system. The experimental results are discussed in the light of existing theories. (author). 10 refs., 3 figs

  8. Ag{sub 3}PO{sub 4} nanocrystals deposited on monoclinic olive-like BiVO{sub 4} with efficient photodegradation of organic dyes under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jingshuai, E-mail: chen-jshuai@ahu.edu.cn; Jiang, Liang-Liang; Liu, Xing-Pei; Mao, Chang-Jie, E-mail: maochangjie@sina.com; Song, Ji-Ming; Niu, Helin; Zhang, Shengyi [Anhui University, School of Chemistry and Chemical Engineering (China)

    2017-05-15

    Olive-like BiVO{sub 4} microstructures with lengths of 600–1000 nm and widths of 300–600 nm have been synthesized via a facile and additive-free solvothermal method. Studies find that the type of solvent plays an important role in the morphology of the final products. Furthermore, Ag{sub 3}PO{sub 4} nanocrystals are successfully deposited on monoclinic olive-like BiVO{sub 4} via in situ precipitation method. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL) spectra, and UV–vis diffuse reflectance spectra (DRS). The photocatalytic activities of the catalysts are evaluated by degradation of rhodamine B (RhB) and methylene blue (MB) under visible light (≥420 nm) irradiation. The experimental results suggest that catalytic activity of the composite photocatalysts is greatly influenced by the loading level of Ag{sub 3}PO{sub 4}. The molar ratio of 0.8:1.0 Ag{sub 3}PO{sub 4}-loaded BiVO{sub 4} exhibits higher photocatalytic activity in both the decolorization of RhB and MB than that of individual BiVO{sub 4} and P25. The observed improvement in photocatalytic activity is associated with the extended absorption in the visible light region resulting from the Ag{sub 3}PO{sub 4} nanoparticles, and the effective separation of photogenerated carriers at the Ag{sub 3}PO{sub 4}/BiVO{sub 4} interfaces through the formation of heterojunction structure. The study provides a general and effective method in the fabrication of composite with sound heterojunctions that may show a variety of applications.

  9. Kinetics of intermetallic phase formation at the interface of Sn-Ag-Cu-X (X = Bi, In) solders with Cu substrate

    International Nuclear Information System (INIS)

    Hodulova, Erika; Palcut, Marian; Lechovic, Emil; Simekova, Beata; Ulrich, Koloman

    2011-01-01

    Highlights: → In substitutes Sn in intermetallic compounds formed at the Cu-solder interface. → Bi and In decrease the parabolic rate constant of Cu 3 Sn layer growth. → In increases the parabolic rate constant of Cu 6 Sn 5 layer growth. → High In concentrations should be avoided since they may lead to a pre-mature solder joint degradation. - Abstract: The effects of Bi and In additions on intermetallic phase formation in lead-free solder joints of Sn-3.7Ag-0.7Cu; Sn-1.0Ag-0.5Cu-1.0Bi and Sn-1.5Ag-0.7Cu-9.5In (composition given in weight %) with copper substrate are studied. Soldering of copper plate was conducted at 250 deg. C for 5 s. The joints were subsequently aged at temperatures of 130-170 deg. C for 2-16 days in a convection oven. The aged interfaces were analyzed by optical microscopy and energy dispersive X-ray spectroscopy (EDX) microanalysis. Two intermetallic layers are observed at the interface - Cu 3 Sn and Cu 6 Sn 5 . Cu 6 Sn 5 is formed during soldering. Cu 3 Sn is formed during solid state ageing. Bi and In decrease the growth rate of Cu 3 Sn since they appear to inhibit tin diffusion through the grain boundaries. Furthermore, indium was found to produce a new phase - Cu 6 (Sn,In) 5 instead of Cu 6 Sn 5 , with a higher rate constant. The mechanism of the Cu 6 (Sn,In) 5 layer growth is discussed and the conclusions for the optimal solder chemical composition are presented.

  10. Preparation of (Bi, Pb)-2223/Ag tapes by high temperature sintering and post-annealing process

    DEFF Research Database (Denmark)

    Hua, L.; Grivel, Jean-Claude; Andersen, L.G.

    2002-01-01

    A novel heat treatment process was developed to fabricate (Bi, Pb)-2223/Ag tapes with high critical current density (J(c)). The process can be divided into two parts: reformation and post-annealing. Tapes were first heated to the maximum temperature (830-860 degreesC) followed by slow cooling...... (reformation). Then, tape, were annealed between 760 and 820 degreesC (post-annealing). Reformation is expected to produce a large amount of liquid phase which may heat microcracks, decrease porosity, and improve grain growth. However, since the sintering temperature is beyond the Bi-2223 single-phase region......-energy synchrotron XRD and SEM/EDX. Some process parameters e.g. sintering temperature. cooling rate. and post-annealing time were optimised. (C) 2002 Elsevier Science B.V. All rights reserved....

  11. Raman probes based on optically-poled double-clad fiber and coupler

    DEFF Research Database (Denmark)

    Brunetti, Anna Chiara; Margulis, Walter; Rottwitt, Karsten

    2012-01-01

    of a sample of dimethyl sulfoxide (DMSO), when illuminating the waveguide with 1064nm laser light. The Raman signal is collected in the inner cladding, from which it is retrieved with either a bulk dichroic mirror or a double-clad fiber coupler. The coupler allows for a substantial reduction of the fiber......Two fiber Raman probes are presented, one based on an optically-poled double-clad fiber and the second based on an optically-poled double-clad fiber coupler respectively. Optical poling of the core of the fiber allows for the generation of enough 532nm light to perform Raman spectroscopy...

  12. High-Pressure Band-Gap Engineering in Lead-Free Cs 2 AgBiBr 6 Double Perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qian [Department of Chemistry, Southern University of Science and Technology, SUSTech, Shenzhen Guangdong 518055 P.R. China; College of Chemistry, Nankai University, Tianjin 300071 P.R. China; Wang, Yonggang [High Pressure Synergetic Consortium, HPSynC, Geophysical Laboratory, Carnegie Institution of Washington, Argonne IL 60439 USA; Pan, Weicheng [Wuhan National Laboratory for Optoelectronics, WNLO and School of Optical and Electronic Information, Huazhong University of Science and Technology, HUST, Wuhan 430074 P.R. China; Yang, Wenge [High Pressure Synergetic Consortium, HPSynC, Geophysical Laboratory, Carnegie Institution of Washington, Argonne IL 60439 USA; Zou, Bo [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 P.R. China; Tang, Jiang [Wuhan National Laboratory for Optoelectronics, WNLO and School of Optical and Electronic Information, Huazhong University of Science and Technology, HUST, Wuhan 430074 P.R. China; Quan, Zewei [Department of Chemistry, Southern University of Science and Technology, SUSTech, Shenzhen Guangdong 518055 P.R. China

    2017-11-15

    Novel inorganic lead-free double perovskites with improved stability are regarded as alternatives to state-of-art hybrid lead halide perovskites in photovoltaic devices. The recently discovered Cs2AgBiBr6 double perovskite exhibits attractive optical and electronic features, making it promising for various optoelectronic applications. However, its practical performance is hampered by the large band gap. In this work, remarkable band gap narrowing of Cs2AgBiBr6 is, for the first time, achieved on inorganic photovoltaic double perovskites through high pressure treatments. Moreover, the narrowed band gap is partially retainable after releasing pressure, promoting its optoelectronic applications. This work not only provides novel insights into the structure–property relationship in lead-free double perovskites, but also offers new strategies for further development of advanced perovskite devices.

  13. Synthesis of the phase with T sub c =110 K in Bi(Pb)-Sr-Ca-Cu-O superconducting ceramics. Sintez fazy T sub c =110 K sverkhprovodyashchej keramiki sostava Bi(Pb)-Sr-Ca-Cu-O

    Energy Technology Data Exchange (ETDEWEB)

    Dubovitskij, A V; Makarov, E F; Makova, M K; Merzhanov, V A; Topnikov, V N [AN SSSR, Moscow (USSR). Inst. Khimicheskoj Fiziki

    1991-05-01

    Synthesis of 110 K single-phase bismuth ceramics (BiPb){sub 2}Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub x} was conducted in narrow temperature and time range. Diffusion of bismuth ions is proposed to be the decisive factor of synthesis of bismuth ceramics. The diffusion depends on prehistory of basic burden preparation and on its dispersivity and homogeneity in particluar. Optimal time of synthesis for lead doped ceramics of 2223 composition, synthesized from initial nitrate components, is equal to 65 h at 850 deg C. The role of Pb{sup 2+} ions is probably reduced to decrease of diffusion mobility of Bi{sup 3+} ions over the bismuth sublattice. Ceramics doping with CdO and CdCl{sub 2} compounds instead of lead stabilizes superconductivity in bismuth ceramics, but with worth superconducting parameters.

  14. Oxygen permeation properties of dense Bi1.5Er0.5O3-Ag cermet membranes

    NARCIS (Netherlands)

    ten Elshof, Johan E.; Nguyen, N.Q.; den Otter, M.W.; Bouwmeester, Henricus J.M.

    1997-01-01

    Oxygen permeation experiments were performed on dense mixed-conducting ceramic-metal composite membranes (thickness 0.2 to 2 mm) Bi1.5Er0.5O3-Ag with 10.0, 27.8, and 40.0 volume percent (v/o) silver, respectively, in the temperature range 873 to 993 K and oxygen partial pressure range 10–3.5 to 1

  15. Superconducting energy gap of BaPb/sub 1-//sub x/Bi/sub x/O3

    International Nuclear Information System (INIS)

    Schlesinger, Z.; Collins, R.T.; Scott, B.A.; Calise, J.A.

    1988-01-01

    We report the first infrared measurement of the superconducting energy gap of BaPb/sub 1-//sub x/Bi/sub x/O 3 . In our polycrystalline samples with T/sub c/≅9.5 K (x≅0.2) we obtain 2Δ≅3.2kT/sub c/, roughly in agreement with the weak-coupling Bardeen-Cooper-Schrieffer prediction, 2Δ = 3.5kT/sub c/, and with tunneling measurements of the gap. We do not observe any structure above the gap energy associated with strong coupling

  16. Thermoelectric properties of p-type pseudo-binary (Ag0.365Sb0.558Te) x -(Bi0.5Sb1.5Te3)1-x (x=0-1.0) alloys prepared by spark plasma sintering

    International Nuclear Information System (INIS)

    Cui, J.L.; Xue, H.F.; Xiu, W.J.; Jiang, L.; Ying, P.Z.

    2006-01-01

    In this paper, pseudo-binary (Ag 0.365 Sb 0.558 Te) x -(Bi 0.5 Sb 1.5 Te 3 ) 1- x (x=0-1.0) alloys were prepared using spark plasma sintering technique, and the composition-dependent thermoelectric properties were evaluated. Electrical conductivities range from 7.9x10 4 to 15.6x10 4 Ω -1 m -1 at temperatures of 507 and 318 K, respectively, being about 3.0 and 8.5 times those of Bi 0.5 Sb 1.5 Te 3 alloy at the corresponding temperatures. The optimal dimensionless figure of merit (ZT) of the sample with molar fraction x=0.025 reaches 1.1 at 478 K, whereas that of the ternary Bi 0.5 Sb 1.5 Te 3 alloy is 0.58 near room temperature. The results also reveal that a direct introduction of Ag 0.365 Sb 0.558 Te in the Bi-Sb-Te system is much more effective to the property improvement than naturally precipitated Ag 0.365 Sb 0.558 Te in the Ag-doped Ag-Bi-Sb-Te system. - Graphical abstract: The temperature dependence of the dimensionless thermoelectric figure of merit ZT for different (Ag 0.365 Sb 0.558 Te) x -(Bi 0.5 Sb 1.5 Te 3 ) 1- x (x=0-1.0) alloys prepared by spark plasma sintering

  17. AC losses in Ag-sheathed Bi2223 tapes with Ca2CuO3 as interfilamentary resistive barriers

    International Nuclear Information System (INIS)

    Inada, R.; Iwata, Y.; Tateyama, K.; Nakamura, Y.; Oota, A.; Zhang, P.X.

    2006-01-01

    In this study, we prepared the Bi2223 multifilamentary tapes with Ca 2 CuO 3 as interfilamentary resistive barriers and evaluated their AC magnetization loss properties at 77 K. The Bi2223 tapes with thin barrier layers of Ca 2 CuO 3 around the filaments were prepared by using a standard powder-in-tube (PIT) method. To fabricate the Ca 2 CuO 3 layers around each filament, the outside surface of monocore Ag-sheathed wires was coated by Ca 2 CuO 3 with the slurry. After the heat treatment to decompose and evaporate the organic binder in the slurry, the several coated monocore wires were stacked and packed into another Ag-tube. Then, the packed tube was drawn and rolled into tape shape. The tape was subsequently sintered to form Bi2223 phase inside filaments. The AC magnetization losses in an AC transverse magnetic field were measured by a pick-up coil method. The loss properties in the barrier tape were compared with those in the tape without barriers. The results indicated that introducing Ca 2 CuO 3 barriers is very effective to suppress the electromagnetic coupling among the filaments and also to reduce the magnetization losses under parallel transverse field

  18. Dielectric properties of glasses prepared by quenching melts of superconducting Bi-Ca-Sr-Cu-O cuprates

    Energy Technology Data Exchange (ETDEWEB)

    Varma, K. B. R.; Subbanna, G. N.; Ramakrishnan, T. V.; Rao, C. N. R.

    1989-07-03

    Glasses obtained from quenching melts of superconducting bismuth cuprates of the formula Bi/sub 2/(Ca,Sr)/sub /ital n/+1/Cu/sub /ital n//O/sub 2/ital n/+4/ with /ital n/=1 and 3 exhibit novel dielectric properties. They possess relatively high dielectric constants as well as high electrical conductivity. The novel dielectric properties of these cuprate glasses are likely to be of electronic origin. They exhibit a weak microwave absorption due to the presence of microcrystallites.

  19. Effect of laser power on clad metal in laser-TIG combined metal cladding

    Science.gov (United States)

    Utsumi, Akihiro; Hino, Takanori; Matsuda, Jun; Tasoda, Takashi; Yoneda, Masafumi; Katsumura, Munehide; Yano, Tetsuo; Araki, Takao

    2003-03-01

    TIG arc welding has been used to date as a method for clad welding of white metal as bearing material. We propose a new clad welding process that combines a CO2 laser and a TIG arc, as a method for cladding at high speed. We hypothesized that this method would permit appropriate control of the melted quantity of base metal by varying the laser power. We carried out cladding while varying the laser power, and investigated the structure near the boundary between the clad layer and the base metal. Using the laser-TIG combined cladding, we found we were able to control appropriately the degree of dilution with the base metal. By applying this result to subsequent cladding, we were able to obtain a clad layer of high quality, which was slightly diluted with the base metal.

  20. Mineralogical data on angelaite, Cu2AgPbBiS4, from the Los Manantiales District, Chubut, Argentina

    DEFF Research Database (Denmark)

    Topa, D.; Paar, W.H.; Putz, H.

    2010-01-01

    Angelaite, ideally Cu2AgPbBiS4, occurs as a hypogene mineral in polymetallic ores at the Ángela groups of veins in the mining district of Los Manantiales, in the province of Chubut, Argentina. The new mineral species is predominantly associated with pyrite, sphalerite, chalcopyrite, hematite...

  1. Bi-Polaron Condensation in High Tc Superconductors

    International Nuclear Information System (INIS)

    Ranninger, J.

    1995-01-01

    On the basis of optical measurements-, photoemission-, EXAFS- and neutron scattering-experiments we conclude that itinerant valence electrons coexist with localized bi-polarons.Entering the metallic phase upon chemical doping, a charge transfer between the two electronic subsystems is triggered off. We show that as the temperature is lowered towards Tc this process leads to a delocalization of bi-polarons due to a precursor effect of superfluidity of those bi-polarons. Upon entering the superconducting phase, these bipolarons ultimately condense into a superfluid state which is expected to largely determine the superconducting properties of high Tc materials. (authors)

  2. Anisotropic two-gap superconductivity and the absence of a Pauli paramagnetic limit in single-crystalline LaO0.5F0.5BiS2

    Science.gov (United States)

    Chan, Y. C.; Yip, K. Y.; Cheung, Y. W.; Chan, Y. T.; Niu, Q.; Kajitani, J.; Higashinaka, R.; Matsuda, T. D.; Yanase, Y.; Aoki, Y.; Lai, K. T.; Goh, Swee K.

    2018-03-01

    Ambient-pressure-grown LaO0.5F0.5BiS2 with a superconducting transition temperature Tc˜3 K possesses a highly anisotropic normal state. By a series of electrical resistivity measurements with a magnetic-field direction varying between the crystalline c axis and the a b plane, we present datasets displaying the temperature dependence of the out-of-plane upper critical field Hc2 ⊥(T ) , the in-plane upper critical field Hc2 ∥(T ) , as well as the angular dependence of Hc 2 at fixed temperatures for ambient-pressure-grown LaO0.5F0.5BiS2 single crystals. The anisotropy of the superconductivity, Hc2 ∥/Hc2 ⊥ , reaches ˜16 on approaching 0 K, but it decreases significantly near Tc. A pronounced upward curvature of Hc2 ∥(T ) is observed near Tc, which we analyze using a two-gap model. Moreover, Hc2 ∥(0 ) is found to exceed the Pauli paramagnetic limit, which can be understood by considering the strong spin-orbit coupling associated with Bi as well as the breaking of the local inversion symmetry at the electronically active BiS2 bilayers. Hence, LaO0.5F0.5BiS2 with a centrosymmetric lattice structure is a unique platform to explore the physics associated with local parity violation in the bulk crystal.

  3. Growth of layered superconductor β-PdBi{sub 2} films using molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, N.V., E-mail: denisov@iacp.dvo.ru [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); Matetskiy, A.V.; Tupkalo, A.V. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); Zotov, A.V. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); School of Natural Sciences, Far Eastern Federal University, 690950 Vladivostok (Russian Federation); Department of Electronics, Vladivostok State University of Economics and Service, 690600 Vladivostok (Russian Federation); Saranin, A.A. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); School of Natural Sciences, Far Eastern Federal University, 690950 Vladivostok (Russian Federation)

    2017-04-15

    Highlights: • Bulk β-PdBi{sub 2} is layered material with advanced properties of topological superconductor. • We present a method for growing β-PdBi{sub 2} films of a desired thickness. • Method utilizes MBE growth of β-PdBi{sub 2}, using Bi(111) film on Si(111) as a template. • Electronic and superconducting properties of the films are similar to those of bulk β-PdBi{sub 2}. - Abstract: Bulk β-PdBi{sub 2} layered material exhibits advanced properties and is supposed to be probable topological superconductor. We present a method based on molecular beam epitaxy that allows us to grow β-PdBi{sub 2} films from a single β-PdBi{sub 2} triple layer up to the dozens of triple layers, using Bi(111) film on Si(111) as a template. The grown films demonstrate structural, electronic and superconducting properties similar to those of bulk β-PdBi{sub 2} crystals. Ability to grow the β-PdBi{sub 2} films of desired thickness opens the promising possibilities to explore fascinating properties of this advanced material.

  4. Structural cladding /clad structures

    DEFF Research Database (Denmark)

    Beim, Anne

    2012-01-01

    Structural Cladding /Clad Structures: Studies in Tectonic Building Practice A. Beim CINARK – Centre for Industrialized Architecture, Institute of Architectural Technology, The Royal Danish Academy of Fine Arts School of Architecture, Copenhagen, Denmark ABSTRACT: With point of departure in the pr......Structural Cladding /Clad Structures: Studies in Tectonic Building Practice A. Beim CINARK – Centre for Industrialized Architecture, Institute of Architectural Technology, The Royal Danish Academy of Fine Arts School of Architecture, Copenhagen, Denmark ABSTRACT: With point of departure...... to analyze, compare, and discuss how these various construction solutions point out strategies for development based on fundamentally different mindsets. The research questions address the following issues: How to learn from traditional construction principles: When do we see limitations of tectonic maneuver......, to ask for more restrictive building codes. As an example, in Denmark there are series of increasing demands in the current building legislations that are focused at enhancing the energy performance of buildings, which consequently foster rigid insulation standards and ask for improvement of air...

  5. Effects of out-of-plane disorder on the superconductivity of Bi{sub 2}Sr{sub 2-x}La{sub x}CuO{sub 6+{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Roehler, Juergen; Trabant, Christoph; Frielingsdorf, Johanna; Djemour, Rabia [Universitaet Koeln, 50937 Koeln (Germany); Martovitsky, Victor [Lebedev-Institute, 119991 Moscow (Russian Federation); Dudy, Lenart; Dwelk, Helmut; Krapf, Alica [Humboldt Universitaet Berlin, 12489 Berlin (Germany)

    2008-07-01

    The effects of out-of-plane substitutional order/disorder on cuprate superconductivity remains to a large extent an unresolved issue. We have investigated the connection between superconductivity and the lattice effects arising from the heterovalent doping of Bi{sub 2}Sr{sub 2-x}La{sub x}CuO{sub 6+{delta}}, x = 0.8-0.1. Decreasing lanthanum content tunes the compound through the entire underdoped and overdoped regimes. Cu-K and La- K EXAFS served as local structural probes, and single crystal X-ray diffraction for the determination of the basic unit cell, and the symmetry of the supercell. The oxygen atoms in the CuO{sub 2} planes were found significantly disordered, dependent on doping, and to exhibit minimum disorder around x{sub opt}=0.33. But the degree of substitutional disorder in the out-of-plane La environment turned out independent on the concentration of the La dopants, the superstructure symmetry, and the crystal growth parameters, whereas T{sub c} depends sensitively on them. No evidence was found for possible concentration dependent site changes of the La dopant from the nominal Sr to the Bi sites. We discuss the probably crucial role of the interstitial oxygen atoms for the superconducting properties of the Bi{sub 2}Sr{sub 2-x}La{sub x}CuO{sub 6+{delta}} system.

  6. Comparative study of A-site order in the lead-free bismuth titanates M1/2Bi1/2TiO3 (M=Li, Na, K, Rb, Cs, Ag, Tl) from first-principles

    International Nuclear Information System (INIS)

    Gröting, Melanie; Albe, Karsten

    2014-01-01

    We investigate the possibility of enhancing chemical order in the relaxor ferroelectric Na 1/2 Bi 1/2 TiO 3 upon substitution of Na + by other monovalent cations M + using total energy calculations based on density functional theory. All chemically available monovalent cations M + , which are Li, Na, Ag, K, Tl, Rb and Cs, are considered and an analysis of the structurally relaxed structures in terms of symmetry-adapted distortion modes is given in order to quantify the chemically induced structural distortions. We demonstrate that the replacement of Na + by other monovalent cations can hardly alter the tendency of chemical order with respect to Na 1/2 Bi 1/2 TiO 3 . Only Tl 1/2 Bi 1/2 TiO 3 and Ag 1/2 Bi 1/2 TiO 3 show enhanced tendency for chemical ordering. Both heavy metals behave similar to the light alkali metals in terms of structural relaxations and relative stabilities of the ordered configurations. Although a comparison of the Goldschmidt factors of components (M TiO 3 ) − reveals for Tl a value above the upper stability limit for perovskites, the additional lone-pair effect of Tl + stabilizes the ordered structure. - Graphical abstract: Amplitudes of chemically induced distortion modes in different ordered perovskites M 1/2 Bi 1/2 TiO 3 and visualisation of atomic displacements associated with distortion mode X + 1 in the 001-ordered compounds Li 1/2 Bi 1/2 TiO 3 and Cs 1/2 Bi 1/2 TiO 3 . Due to a substantial size mismatch between bismuth (green) and caesium (dark blue), incorporation of the latter leads to enhanced displacements of oxygen atoms (red) and suppresses displacements of titanium (silver) as compared to lithium (light blue) or other smaller monovalent cations. - Highlights: • Lead-free A-site mixed bismuth titanates M 1/2 Bi 1/2 TiO 3 are studied by first-principles calculations. • Investigation of chemical ordering tendency for M=Li, Na, K, Rb, Cs, Ag, and Tl. • Group theoretical analysis of different ordered structures. • Ag and Tl

  7. The role of cladding material for performance of LWR control assemblies

    International Nuclear Information System (INIS)

    Dewes, P.; Roppelt, A.

    2000-01-01

    The lifetime of control assemblies in LWRs can be limited presently by mechanical failure of the absorber cladding. The major cause of failure is mechanical interaction of the absorber with the cladding due to irradiation induced dimensional changes such as absorber swelling and cladding creep, resulting in cracking of the clad. Such failures occurred in both BWRs and PWRs. Experience and in-reactor tests revealed that cracking can be avoided principally by two ways: First, if strain rates and hence, stresses in the cladding are kept low (well below the yield strength), significant strains can be tolerated. This is the case for the cladding of PWR control assemblies with slowly swelling Ag-In-Cd absorber. Recent examinations of highly exposed PWR control assemblies confirmed the design correlation up to the presently used strain limit. Second, in such cases where strongly swelling absorber material like boron carbide is still preferred, materials which are resistant against irradiation assisted stress corrosion cracking (IASCC) can be used. The influence of material composition and condition on IASCC was studied in-reactor using tubular samples of various stainless steels and Ni-base alloys stressed by swelling mandrels. In several programme steps high purity materials with special features had been identified as resistant to IASCC. Another process of cladding damage which may occur in PWRs is wear caused by friction of the control rods in the surrounding guide structure. For replacement control assemblies this problem is solved by coating of the cladding. There exists meanwhile excellent experience of up to 18 operation cycles with coated claddings. (author)

  8. Electromechanical characterization of superconducting wires and tapes at 77 K

    CERN Document Server

    Bjoerstad, Roger

    The strain dependency of the critical current in state-of-the-art cuprate high-temperature superconductors (HTS) has been characterized. A universal test machine (UTM) combined with a critical current measurement system has been used to characterize the mechanical and the superconducting properties of conductors immersed in an open liquid nitrogen dewar. A set-up has been developed in order to perform simultaneous measurements of the superconductor lattice parameter changes, critical current, as well as the stress and strain at 77 K in self-field in a high energy synchrotron beamline. The HTS tapes and wires studied were based on YBCO, Bi-2223 and Bi-2212. The YBCO tapes were produced by SuperPower and American Superconductors (AMSC). Two types of Bi-2223 tapes, HT and G, were produced by Sumitomo Electric Industries (SEI). The Bi-2212 wires were produced by Oxford Superconducting Technology (OST) using Nexans granulate precursor, before undergoing a specialized over pressure (OP) processing and heat treatmen...

  9. Angle-resolved-photoemission study of Bi2Sr2CaCu2O8+δ: Metallicity of the Bi-O plane

    International Nuclear Information System (INIS)

    Wells, B.O.; Shen, Z.; Dessau, D.S.; Spicer, W.E.; Olson, C.G.; Mitzi, D.B.; Kapitulnik, A.; List, R.S.; Arko, A.

    1990-01-01

    We have performed high-resolution angle-resolved-photoemission experiments on Bi 2 Sr 2 CaCu 2 O 8+δ single crystals with different annealing histories. By depositing a small amount of Au on the surface, we were able to distinguish electronic states associated with the Bi-O surface layer. We found that the Bi-O atomic surface layer is metallic and superconducting for samples that were high-temperature annealed in oxygen but not for as-grown samples. The Cu-O plane is found to be superconducting in all samples

  10. Superconducting thin films of Bi-Sr-Ca-Cu-O by laser ablation

    International Nuclear Information System (INIS)

    Bedekar, M.M.

    1992-01-01

    The discovery of a new class of copper oxide superconductors has led to the development of three major systems that exhibit superconducting properties. The Bi-Sr-Ca-Cu-O superconductors offer intrinsic advantages due to the high T c , chemical inertness and tolerance for a range of compositions. However, thin film research on these materials has progressed more slowly than the other cuprate systems. This dissertation examines the film growth, by laser ablation, of the Bi-Sr-Ca-Cu-O superconductors and the effect of the deposition parameters such as the laser target interaction, substrate temperature, target to substrate distance, deposition and cooling pressure, target type and processing and the substrate type. CO 2 laser ablation was shown to give rise to a non-stoichiometric material transfer due to the low fluences and long pulse lengths. In situ superconducting thin films with T c(0) 's of 76 K could be deposited using the KrF laser at substrate temperatures of 5 degrees C to 20 degrees C below phases. Lower temperatures gave rise to a mixture of 2201 and glassy phases. An increase in the target to substrate distance led to a deterioration of the electrical and structural properties of the films due to a decrease in the energy for film formation. A maximum in T c(0) was observed at 450 mtorr as the deposition pressure was varied between 200 to 700 mtorr. Optimum oxygen incorporation could be achieved by cooling the films in high oxygen pressures and the best films were obtained with 700 torr cooling pressure. The oxygen deficiency of the hot pressed targets led to inferior properties compared to the conventionally sintered targets. The microwave surface resistance of the films measured at 35 GHz showed an onset at 80 K and dropped below that of copper at 30 K. The study of the laser ablation process in this system revealed the presence of a stoichiometric forward directed component and a diffuse evaporation component

  11. Phase equilibria and homogeneity range of the high temperature superconducting compound (Bi,Pb)2+xSr2Ca2Cu3O10+δ

    International Nuclear Information System (INIS)

    Kaesche, S.

    1995-01-01

    For the superconducting cuprates (Bi,Pb) 2+x Sr 2 Ca 2 Cu 3 O 10+y phase equilibria, the homogeneity region, and the phase formation has been studied in the temperture range 800 to 890 C. Sintered samples were prepared by a solid state reaction starting from Bi 2 O 3 , PbO, CuO and carbonates CaCO 3 and SrCO 3 in a three-stage calcination process. For the phase identification polarization microscopy, X-ray diffraction and susceptibility measurements have been applied. Multi-phase regions were determined in the cross section of the quasi-ternary system (Bi,Pb) 2 O 3 -SrO-CaO-CuO with constant Bi/(Bi+Pb) ratio 0.84 taking into account the 2223-phase. The homogeneity region was determined as function of Sr, Ca, Bi and Pb concentration. Its maximum size was found at 850 C

  12. Contact interaction of the Bi12GeO20, Bi12SiO20, and Bi4Ge3O12 melts with noble metals

    Science.gov (United States)

    Denisov, V. M.; Podkopaev, O. I.; Denisova, L. T.; Kuchumova, O. V.; Istomin, S. A.; Pastukhov, E. A.

    2014-02-01

    The sessile drop method is used to study the contact interaction of Ag, Au, Pd, Pt, and Ir with the Bi2O3-GeO2 and Bi2O3-SiO2 melts. These melts spread over Ag and Pd and, in some cases, over Au and Pt at a rather high speed and form equilibrium contact angles on Ir.

  13. Calorimetric investigations of U-Bi system

    International Nuclear Information System (INIS)

    Agarwal, Renu; Joshi, A.R.

    2013-01-01

    U 0.333 Bi 0.667 is a compound that may form on breach of clad during reactor operation with metallic fuel and lead-bismuth coolant. Therefore, enthalpy of mixing of U-Bi liquid solution in limited composition range and enthalpy of formation of U 0.333 Bi 0.667 compound were measured by high temperature calorimetry. The enthalpy of mixing follows subregular solution model and enthalpy of formation U 0.333 Bi 0.667 from U(l) and Bi(l) at 843 K was -52.5 kJ/mol and -40.8 kJ/mol from U(s) and Bi(s) at 298.15 K. Both enthalpy of mixing and enthalpy of formation of intermetallic compound obtained experimentally were compared with Miedema model values. (author)

  14. Microstructure and tribological properties of TiAg intermetallic compound coating

    International Nuclear Information System (INIS)

    Guo Chun; Chen Jianmin; Zhou Jiansong; Zhao Jierong; Wang Linqian; Yu Youjun; Zhou Huidi

    2011-01-01

    TiAg intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding using Ag powder as the precursor. It has been found that the prepared coating mainly comprised TiAg and Ti phases. The high resolution transmission electron microscopy results further conform the existence of TiAg intermetallic compound in the prepared coating. The magnified high resolution transmission electron microscopy images shown that the laser cladding coating contains TiAg nanocrystalline with the size of about 4 nm. Tribological properties of the prepared TiAg intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiAg intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiAg intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate increased as the normal load increased.

  15. Microstructure and tribological properties of TiAg intermetallic compound coating

    Energy Technology Data Exchange (ETDEWEB)

    Guo Chun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Chen Jianmin, E-mail: chenjm@lzb.ac.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhou Jiansong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhao Jierong; Wang Linqian; Yu Youjun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Zhou Huidi [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2011-10-01

    TiAg intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding using Ag powder as the precursor. It has been found that the prepared coating mainly comprised TiAg and Ti phases. The high resolution transmission electron microscopy results further conform the existence of TiAg intermetallic compound in the prepared coating. The magnified high resolution transmission electron microscopy images shown that the laser cladding coating contains TiAg nanocrystalline with the size of about 4 nm. Tribological properties of the prepared TiAg intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiAg intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiAg intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate increased as the normal load increased.

  16. Characterization of superconducting coil for fault current limitation

    International Nuclear Information System (INIS)

    Polasek, Alexander; Dias, Rodrigo; Niedu, Daniel Brito; Ogasawara, Tsuneharu; Oliveira Filho, Orsino Borges de; Serra, Eduardo Torres; Gomes Junior, George; Amorim, Helio Salim

    2010-01-01

    The increasing power demand has been raising fault currents up to dangerous levels. Superconducting fault current limiters are a promising solution for this problem. In the present work, we studied a superconducting Bi-2212 coil that is used for fault current limitation. Samples were analyzed by XRD, SEM/EDS and measurement of critical temperature (Tc). The Rietveld method was employed for phase quantification. Relatively high Bi-2212 fractions were found. However, Tc varies from a sample to another one. Variations of local Tc are attributed to variations of oxygen content in Bi- 2212 phase. (author)

  17. Enhanced ferroelectric photoelectrochemical properties of polycrystalline BiFeO{sub 3} film by decorating with Ag nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qing; Shen, Mingrong; Fang, Liang, E-mail: lfang@suda.edu.cn [College of Physics, Optoelectronics and Energy and Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006 (China); Zhou, Yang; You, Lu; Wang, Junling [School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore)

    2016-01-11

    Polycrystalline BiFeO{sub 3} (BFO) films are fabricated on Pt/Ti/SiO{sub 2}/Si(100) substrate as photoelectrode using sol-gel method. The microstructure, optical, and photoelectrochemical (PEC) properties of the films are characterized and optimized by controlling the film thickness. Moreover, the PEC properties of the BFO films are dependent on ferroelectric polarization, which is mainly ascribed to the modulation of band structure at the BFO/electrolyte interface by the polarization. Further enhancement of PEC properties is obtained by decorating the samples with appropriate amounts of Ag nanoparticles, which is attributed to the reduced electron-hole recombination, and localized surface plasmon resonance effect of Ag nanoparticles.

  18. Preparation of Ag4Bi2O5/MnO2 Corn/Cob Like Nano Material as a Superior Catalyst for Oxygen Reduction Reaction in Alkaline Solution

    Directory of Open Access Journals (Sweden)

    Xun Zeng

    2017-12-01

    Full Text Available Ag4Bi2O5/MnO2 nano-sized material was synthesized by a co-precipitation method in concentrated KOH solution. The morphology characterization indicates that MnO2 nanoparticles with a size of 20 nm are precipitated on the surface of nano Ag4Bi2O5, forming a structure like corn on the cob. The obtained material with 60% Mn offers slightly higher initial potential (0.098 V vs. Hg/HgO and limiting current density (−5.67 mA cm−2 at a rotating speed of 1600 rpm compared to commercial Pt/C (−0.047 V and −5.35 mA cm−2, respectively. Furthermore, the obtained material exhibits superior long-term durability and stronger methanol tolerance than commercial Pt/C. The remarkable features suggest that the Ag4Bi2O5/MnO2 nano-material is a very promising oxygen reduction reaction catalyst.

  19. Characteristics of Ni-based coating layer formed by laser and plasma cladding processes

    International Nuclear Information System (INIS)

    Xu Guojian; Kutsuna, Muneharu; Liu Zhongjie; Zhang Hong

    2006-01-01

    The clad layers of Ni-based alloy were deposited on the SUS316L stainless plates by CO 2 laser and plasma cladding processes. The smooth clad bead was obtained by CO 2 laser cladding process. The phases of clad layer were investigated by an optical microscope, scanning electron microscopy (SEM), X-ray diffractometer (XRD), electron probe microanalysis (EPMA) and energy-dispersive spectrometer (EDS). The microstructures of clad layers belonged to a hypereutectic structure. Primary phases consist of boride CrB and carbide Cr 7 C 3 . The eutectic structure consists of Ni + CrB or Ni + Cr 7 C 3 . Compared with the plasma cladding, the fine microstructures, low dilutions, high Vickers hardness and excellent wear resistance were obtained by CO 2 laser cladding. All that show the laser cladding process has a higher efficiency and good cladding quality

  20. Facile Synthesis of Magnetic Photocatalyst Ag/BiVO4/Mn1−xZnxFe2O4 and Its Highly Visible-Light-Driven Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Taiping Xie

    2018-05-01

    Full Text Available Ag/BiVO4/Mn1−xZnxFe2O4 was synthesized with a dip-calcination in situ synthesis method. This work was hoped to provide a simple method to synthesis three-phase composite. The phase structure, optical properties and magnetic feature were confirmed by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectrometer (XPS, transmission electron microscopy (TEM, ultraviolet-visible diffuse reflectance spectrophotometer (UV-vis DRS, and vibrating sample magnetometer (VSM. The photocatalytic activity was investigated by Rhodamine B (RhB photo-degradation under visible light irradiation. The photo-degradation rate of RhB was 94.0~96.0% after only 60 min photocatalytic reaction under visible light irradiation, revealing that it had an excellent visible-light-induced photocatalytic activity. In the fifth recycle, the degradation rate of Ag/BiVO4/Mn1−xZnxFe2O4 still reached to 94.0%. Free radical tunnel experiments confirmed the dominant role of •O2− in the photocatalytic process for Ag/BiVO4/Mn1−xZnxFe2O4. Most importantly, the mechanism that multifunction Ag could enhance photocatalytic activity was explained in detail.

  1. Electrical and thermal characteristics of Bi2212/Ag HTS coils for conduction-cooled SMES

    International Nuclear Information System (INIS)

    Hayakawa, N; Noguchi, S; Kurupakorn, C; Kojima, H; Endo, F; Hirano, N; Nagaya, S; Okubo, H

    2006-01-01

    In this paper, we investigated the electrical and thermal performance of conduction-cooled Bi2212/Ag HTS coils with 4K-GM cryocooler system. First, we measured the critical current I c for different ambient temperatures T 0 at 4.2 K - 40 K. Experimental results revealed that I c increased with the decrease in T 0 and was saturated at T 0 0 = 4.8 K. Experimental results revealed the criterion of thermal runaway, which was discussed in terms of heat generation and propagation in the test coil

  2. Synthesis and characterization of superconducting bismuthates

    International Nuclear Information System (INIS)

    Tang, Horngyi.

    1991-01-01

    A new electrosynthetic technique for low-temperature crystal growth of superconducting bismuthates was developed, and its utility demonstrated by growing various high-quality BiO 3 crystals. The crystals of Ba 1-x K x BiO 3 and Ba 1-x Rb x BiO 3 display their T c onset at 31.8k and 28k, respectively, using SQUID magnetometry. The structure of a KBiO 3 x H 2 O single crystal determined by single crystal x-ray diffraction confirms previous results from powder samples that it is isostructural with KSbO 3 . The crystals of Ba 1-x Cs x BiO 3 do not show superconductivity to 4k. Chemical vapor-transport experiments leading to the fabrication of MoS 2 /WSe 2 junctions were also performed and are described in detail

  3. Superconducting thin films of Bi-Sr-Ca-Cu-O by laser ablation

    Science.gov (United States)

    Bedekar, M. M.; Safari, A.; Wilber, W.

    1992-11-01

    Superconducting thin films of Bi-Sr-Ca-Cu-O have been deposited by KrF excimer laser ablation. The best in situ films showed a Tc onset of 110 K and a Tc(0) of 76 K. A study of the laser plume revealed the presence of two distinct regimes. The forward directed component increased with fluence and the film composition was stoichiometric in this region. This is in agreement with the results on the 123 system by Venkatesan et al. [1]. The film properties were found to be critically dependent on the substrate temperature and temperatures close to melting gave rise to 2212 and 2223 phases. At lower temperatures, 2201 and amorphous phases were obtained. The film morphology and superconducting properties were a function of the target to substrate distance and the oxygen pressure during deposition and cooling. An increase in the target to substrate distance led to a deterioration of the properties due to the energy consideration for the formation of 2212 and 2223 phases. The best films were obtained using cooling pressures of 700 Torr. The microwave surface resistance of the films measured at 35 GHz dropped below that of copper at 30 K. Film growth was studied using X-ray diffraction and STM/AFM. This work is a discussion of the role of the different variables on the film properties.

  4. Effect of Silicon on Activity Coefficients of P, Bi, Cd, Sn, and Ag in Liquid Fe-Si, and Implications for Core Formation

    Science.gov (United States)

    Righter, K.; Pando, K.; Ross, D. K.; Righter, M.; Lapen, T. J.

    2018-01-01

    Cores of differentiated bodies (Earth, Mars, Mercury, Moon, Vesta) contain light elements such as S, C, Si, and O. We have previously measured small effects of Si on Ni and Co, and larger effects on Mo, Ge, Sb, As metal/silicate partitioning. The effect of Si on metal-silicate partitioning has been quantified for many siderophile elements, but there are a few key elements for which the effects are not yet quantified. Here we report new experiments designed to quantify the effect of Si on the partitioning of Bi, Cd, Sn, Ag, and P between metal and silicate melt. The results will be applied to Earth, Mars, Moon, and Vesta, for which we have good constraints on the mantle Bi, Cd, Sn, Ag, and P concentrations from mantle and/or basalt samples.

  5. Strain tolerance of Bi2Sr2Ca1Cu2O8-δ/Ag composites at high field

    International Nuclear Information System (INIS)

    Li, Q.; Ostenson, J.E.; Finnemore, D.K.

    1991-01-01

    Strain tolerance of Bi 2 Sr 2 Ca 1 Cu 2 O 8-δ /Ag composites have been studied at fields up to 20 T and bending strains up to 2.6% in order to determine the factors that control the critical current density. The goal is to find the best way to distribute Ag such as to give both high strain tolerance and high critical current density. Partial melt processed samples prepared from micromilled mixtures containing 30% Ag by volume show a gradually decreasing critical current all the way out to 2.6% strain. Samples typically show about 1000 A/cm 2 at 4.2 K, 20 T, and 0.75% strain. At 20 K, these values occur at 4 T and 0.75% strain

  6. Phases and structural characteristics of high Tc superconducting oxide in (Bi, Pb)-Sr-Ca-Cu-O system

    International Nuclear Information System (INIS)

    Chen, Zuyano; Li, Zhengrong; Qian, Yitai; Zhou, Quien; Cheng, Tingzhu

    1989-01-01

    The various phases, which are responsible for variant maximum d-value including 18.5 angstrom, 15.4 angstrom, 12.2 angstrom, 6.2 angstrom, 3.2 angstrom and possible 9.1 angstrom respectively, observed in high Tc superconducting complex oxide of (Bi,Pb)-Sr-Ca-Cu-O system are reported in this paper according to the result of X-ray diffraction on platelike crystals or crystallites synthesized under different preparation conditions. The phase of tetragonal system with c=3.21 angstrom, a=3.86 angstrom is possible parent structural unit and it is of great significance to the structure constitution of various phases with large lattice parameter c and structural characteristics of superconducting oxide. In view of the above a model of two-dimension stack-up which causes a stack in variant styles along c-axis and constitute various phases with different lattice parameter c is proposed and discussed

  7. Valence skipping driven superconductivity and charge Kondo effect

    International Nuclear Information System (INIS)

    Yanagisawa, Takashi; Hase, Izumi

    2013-01-01

    Highlights: •Valence skipping in metallic compounds can give rise to an unconventional superconductivity. •Several elements in the periodic table show valence skipping (or valence missing), for example, Bi forms the compounds in valence states +3 and +5. •The doping of valence skipping elements will induce superconductivity and this will lead to a possibility of high temperature superconductivity. •We consider the Wolf model with negative-U impurities, and show a phase diagram including superconducting phase. •There is a high temperature region near the boundary. -- Abstract: Valence skipping in metallic compounds can give rise to an unconventional superconductivity. Several elements in the periodic table show valence skipping (or valence missing), for example, Bi forms the compounds in valence states +3 and +5. The doping of valence skipping elements will induce superconductivity and this will lead to a possibility of high temperature superconductivity. We consider the Wolf model with negative-U impurities, and show a phase diagram including superconducting phase. The superconducting state is changed into a metallic state with a local singlet as the attractive interaction |U| increases. There is a high temperature region near the boundary

  8. Oxygen stoichiometry and the high Tc superconducting oxides

    International Nuclear Information System (INIS)

    Tarascon, J.M.; Bagley, B.G.

    1989-01-01

    Methods for determining the oxygen content in high Tc materials, such as thermogravimetric analysis and chemical analysis, are discussed. Consideration is given to La-based cuprates, Y-based cuprates, and Bi-based cuprates. Superconducting transition temperatures are analyzed as a function of the Cu(1)-O(4) bond lengths for several different compositions in the Y-based system. 28 references

  9. Stress-Strain Distribution Analysis in Bi2212 Subcable Based on Numerical Modeling and Experiment

    NARCIS (Netherlands)

    Qin, J.; Dai, C.; Wang, Q; Liu, P.; Liu, B.; Li, C.; Hao, Q.; Zhou, Chao

    2016-01-01

    There has been sustained interest in the development of the Bi2212/Ag round wire (RW) because of its unique potential for applications in high-field magnets (25 T or higher). The Bi2212 conductor is a round strand, which is a very favorable shape to produce multistage twisted cable-in-conduit

  10. Rotational Symmetry Breaking in a Trigonal Superconductor Nb-doped Bi_{2}Se_{3}

    Directory of Open Access Journals (Sweden)

    Tomoya Asaba

    2017-01-01

    Full Text Available The search for unconventional superconductivity has been focused on materials with strong spin-orbit coupling and unique crystal lattices. Doped bismuth selenide (Bi_{2}Se_{3} is a strong candidate, given the topological insulator nature of the parent compound and its triangular lattice. The coupling between the physical properties in the superconducting state and its underlying crystal symmetry is a crucial test for unconventional superconductivity. In this paper, we report direct evidence that the superconducting magnetic response couples strongly to the underlying trigonal crystal symmetry in the recently discovered superconductor with trigonal crystal structure, niobium (Nb-doped Bi_{2}Se_{3}. As a result, the in-plane magnetic torque signal vanishes every 60°. More importantly, the superconducting hysteresis loop amplitude is enhanced along one preferred direction, spontaneously breaking the rotational symmetry. This observation indicates the presence of nematic order in the superconducting ground state of Nb-doped Bi_{2}Se_{3}.

  11. Interplay of superconductivity and bosonic coupling in the peak-dip-hump structure of Bi2Sr2CaCu2O8 +δ

    Science.gov (United States)

    Miller, Tristan L.; Zhang, Wentao; Ma, Jonathan; Eisaki, Hiroshi; Moore, Joel E.; Lanzara, Alessandra

    2018-04-01

    Because of the important role of electron-boson interactions in conventional superconductivity, it has long been asked whether any similar mechanism is at play in high-temperature cuprate superconductors. Evidence for strong electron-boson coupling is observed in cuprates with angle-resolved photoemission spectroscopy (ARPES), in the form of a dispersion kink and peak-dip-hump structure. What is missing is evidence of a causal relation to superconductivity. Here we revisit the problem using the technique of time-resolved ARPES on Bi2Sr2CaCu2O8 +δ . We focus on the peak-dip-hump structure, and show that laser pulses shift spectral weight into the dip as superconductivity is destroyed on picosecond time scales. We compare our results to simulations of Eliashberg theory in a superconductor with an Einstein boson, and find that the magnitude of the shift in spectral weight depends on the degree to which the bosonic mode contributes to superconductivity. Further study could address one of the longstanding mysteries of high-temperature superconductivity.

  12. Second and third peaks in the non-resonant microwave absorption spectra of superconducting Bi2212 crystals

    CSIR Research Space (South Africa)

    Srinivasu, V V

    2010-04-01

    Full Text Available . Bhat, S.V., Ganguly, P., Ramakrishnan, T.V., Rao, C.N.R.: J. Phys. C 20, L559 (1987) 2. Blazey, K.W., Muller, K.A., Bednorz, J.G., Berlinger, W., Amoretti, G., Buluggiu, E., Vera, A., Matacotta, F.C.: Phys. Rev. B 36, 7241 (1987) 3. Kachaturyan, K... 10.1007/s10948-009-0530-5 O R I G I NA L PA P E R Second and Third Peaks in the Non-resonant Microwave Absorption Spectra of Superconducting Bi2212 Crystals V.V. Srinivasu Received: 19 August 2009 / Accepted: 25 August 2009 ' Springer Science...

  13. Effect of Pb and Cr Substitutions on Phase Formation and Excess Conductivity of Bi-2212 Superconductor

    International Nuclear Information System (INIS)

    Khir, F. L. M.; Mohamed, Z.; Yusuf, A. A.; Yusof, M. I. M.; Yahya, A. K.

    2010-01-01

    The influence of Pb and Cr substitutions on the superconducting properties of Bi 2 Sr 2 CaCu 2 O 8 (Bi-2212) superconductors is reported. The samples were prepared from Bi 2-x Pb x Sr 2 Ca 2-y Cr y Cu 3 O 10-δ (x = 0-0.3, y = 0-0.3) starting composition by the solid-state-reaction method. XRD analysis showed formation of pure Bi-2212 for (x = 0, y = 0), (x = 0.3, y = 0.2,) and (x = 0.3, y = 0.2,) starting compositions. Excess conductivity analysis based on Asmalazov-Larkin theory on single-phased Bi2212 samples showed 2D to 3D transition in superconducting fluctuation behavior (SFB) for all the samples. Highest 2D-3D transition temperature, T 2D-3D was observed at Pb and Cr substitutions of x = 0.3, and x = 0.2, respectively.

  14. Coexistence of magnetism and superconductivity in the hole doped FeAs-based superconducting compound

    International Nuclear Information System (INIS)

    Lu, T.P.; Wu, C.C.; Chou, W.H.; Lan, M.D.

    2010-01-01

    The magnetic and superconducting properties of the Sm-doped FeAs-based superconducting compound were investigated under wide ranges of temperature and magnetic field. After the systematical magnetic ion substitution, the superconducting transition temperature decreases with increasing magnetic moment. The hysteresis loop of the La 0.87-x Sm x Sr 0.13 FeAsO sample shows a superconducting hysteresis and a paramagnetic background signal. The paramagnetic signal is mainly attributed to the Sm moments. The experiment demonstrates that the coexistence of magnetism and superconductivity in the hole doped FeAs-based superconducting compounds is possible. Unlike the electron doped FeAs-based superconducting compounds SmFeAsOF, the hole doped superconductivity is degraded by the substitution of La by Sm. The hole-doped and electron-doped sides are not symmetric.

  15. Influence of doping on transport and magnetisation properties of Bi 2212 tapes - vortex pinning; Influence du dopage sur les proprietes de transport et d`aimantation de rubans polycristallins de Bi 2212 - ancrage de vortex

    Energy Technology Data Exchange (ETDEWEB)

    Zani, L

    1999-12-31

    Bismuth-based superconductors ar now thoroughly studied and are thought to be one of the best High Critical Temperature Superconductors (HSTC) that could be industrially developed. Though their synthesis is one of the easiest to achieve, their strong anisotropy affects drastically their transport properties under magnetic field, especially in the low field regime. In order to avoid vortices motion, two main methods have been used to introduce pinning centers: irradiation defects or dissemination of non-superconducting particles. An original method of synthesis has been developed in our laboratories, alternating electrolytic depositions and heat treatments with which one can obtain Bi 2212 tapes on silver substrate. Though we have good performances at 77 K, the J{sub c} drops by a factor of 5 at 7 T for B parallel to c-axis. By including Ag, MgO and ZrO{sub 2} particles, we tried to introduce efficient pinning centers in the superconducting matrix. Some of these dopants played also a role on intergranular connectivity. By magnetisation and transport studies, we have been able to improve the situation in these two fields. (author) 195 refs.

  16. Influence of doping on transport and magnetisation properties of Bi 2212 tapes - vortex pinning; Influence du dopage sur les proprietes de transport et d`aimantation de rubans polycristallins de Bi 2212 - ancrage de vortex

    Energy Technology Data Exchange (ETDEWEB)

    Zani, L

    1998-12-31

    Bismuth-based superconductors ar now thoroughly studied and are thought to be one of the best High Critical Temperature Superconductors (HSTC) that could be industrially developed. Though their synthesis is one of the easiest to achieve, their strong anisotropy affects drastically their transport properties under magnetic field, especially in the low field regime. In order to avoid vortices motion, two main methods have been used to introduce pinning centers: irradiation defects or dissemination of non-superconducting particles. An original method of synthesis has been developed in our laboratories, alternating electrolytic depositions and heat treatments with which one can obtain Bi 2212 tapes on silver substrate. Though we have good performances at 77 K, the J{sub c} drops by a factor of 5 at 7 T for B parallel to c-axis. By including Ag, MgO and ZrO{sub 2} particles, we tried to introduce efficient pinning centers in the superconducting matrix. Some of these dopants played also a role on intergranular connectivity. By magnetisation and transport studies, we have been able to improve the situation in these two fields. (author) 195 refs.

  17. AC magnetic losses in Bi-2223/Ag tapes with different aspect ratios

    Energy Technology Data Exchange (ETDEWEB)

    Fang, J.; Luo, X.M.; Chen, D.X.; Collings, E.W.; Lee, E.; Sumption, M.D.; Alamgir, A.K.M.; Yi, H.P.; Fang, J.G.; Gu, C.; Guo, S.Q.; Liu, M.L.; Xin, Y.; Han, Z

    2004-10-01

    AC losses in multi-filamentary tapes depend on various parameters. Among them, the overall tape width and thickness are expected to have an important influence. In order to study this geometrical effect, five Bi-2223/Ag tapes with different aspect ratios from 5 to 26 have been prepared. AC losses have been measured at 77 K when a perpendicular AC magnetic field is applied. It has been found that at any frequencies the magnetic loss per cycle increases as the aspect ratio increases. For AC magnetic loss, with increasing frequency from 3 to 9000 Hz the losses as a function of frequency show a maximum if the field amplitude is much less than the full penetration field or increase continuously if the field amplitude is larger.

  18. AC magnetic losses in Bi-2223/Ag tapes with different aspect ratios

    International Nuclear Information System (INIS)

    Fang, J.; Luo, X.M.; Chen, D.X.; Collings, E.W.; Lee, E.; Sumption, M.D.; Alamgir, A.K.M.; Yi, H.P.; Fang, J.G.; Gu, C.; Guo, S.Q.; Liu, M.L.; Xin, Y.; Han, Z.

    2004-01-01

    AC losses in multi-filamentary tapes depend on various parameters. Among them, the overall tape width and thickness are expected to have an important influence. In order to study this geometrical effect, five Bi-2223/Ag tapes with different aspect ratios from 5 to 26 have been prepared. AC losses have been measured at 77 K when a perpendicular AC magnetic field is applied. It has been found that at any frequencies the magnetic loss per cycle increases as the aspect ratio increases. For AC magnetic loss, with increasing frequency from 3 to 9000 Hz the losses as a function of frequency show a maximum if the field amplitude is much less than the full penetration field or increase continuously if the field amplitude is larger

  19. Texturing of superconducting Bi-Pb-Sr-Ca-Cu-O ceramics by combining the effect of a magnetic field and hot pressing in one direction; Texturation des ceramiques supraconductrices Bi-Pb-Sr-Ca-Cu-O par combinaison des effets du champ magnetique et de la contrainte uniaxiale a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Noudem, J G

    1995-10-27

    Superconducting Bi-(Pb)-Sr-Ca-Cu-O (Bi:2223) ceramics have a weak 77 K transport critical current density (Jc) due to porosity and the presence of misaligned platelets. In order to obtain higher critical current densities in these materials, it is necessary to increase their density and induce a preferential crystallographic orientation. We have developed a texturing process using solidification in a magnetic field combined with hot pressing. The experimental set-up provides a uniaxial pressure of 60 MPa and temperature up to 1100 deg C in a magnetic field of 8 T. Magnetic melt texturing (MMT) proved to be very effective in producing bulk oriented samples of polycrystalline Bi:2223 (crystallite c-axis oriented parallel to the field direction). These samples have Jc values of up to 1450 A/cm{sup 2} and a density of 5.1 g/cm{sup 3}. The texturing by hot pressing (HP) gives homogeneous, dense ({approx} 6 g/cm{sup 3}; 95 % of the theoretical limit) ceramics with a Jc of 2500 A/cm{sup 2}. Tapes of Ag/Bi:2223 provided by Alcatel Alsthom were also successful textured using HP. Finally we have demonstrated that the combination of solidification in a magnetic field with hot pressing (MMHPT) improves both the texture and density of the samples. Moreover the samples are very homogeneous and mechanically resistant. The 77 K transport critical current densities have values up to 3800 A/cm{sup 2} and 1100 A/cm{sup 2} along the (ab) and c-axis respectively. We have demonstrated that these samples are of potential use a current limiters. (author) 146 refs.

  20. Quench studies on a layer-wound Bi2Sr2CaCu2Ox/AgX coil at 4.2 K

    International Nuclear Information System (INIS)

    Trociewitz, U P; Czabaj, B; Hong, S; Huang, Y; Knoll, D C; Larbalestier, D C; Markiewicz, W D; Miao, H; Meinesz, M; Wang, X; Schwartz, J

    2008-01-01

    To evaluate the controlled quench behavior of high temperature superconducting (HTS) coils, particularly when using HTS coils in a hybrid configuration as an insert in a low temperature superconducting magnet, a layer-wound solenoid using Bi 2 Sr 2 CaCu 2 O wire was instrumented with several strip heaters to generate quenches in the axial and azimuthal directions. An array of distributed voltage taps and thermocouples were used to monitor the quench signals. Minimum quench energies (MQE) and quench propagation velocities (NZPVs) were determined. Results show that quench energies were moderate. NZPVs were slow but quench reaction times were of the same order as reaction times obtained at low quench energy densities in Nb 3 Sn coils

  1. Superconductivity in Bismuth. A New Look at an Old Problem.

    Science.gov (United States)

    Mata-Pinzón, Zaahel; Valladares, Ariel A; Valladares, Renela M; Valladares, Alexander

    2016-01-01

    To investigate the relationship between atomic topology, vibrational and electronic properties and superconductivity of bismuth, a 216-atom amorphous structure (a-Bi216) was computer-generated using our undermelt-quench approach. Its pair distribution function compares well with experiment. The calculated electronic and vibrational densities of states (eDOS and vDOS, respectively) show that the amorphous eDOS is about 4 times the crystalline at the Fermi energy, whereas for the vDOS the energy range of the amorphous is roughly the same as the crystalline but the shapes are quite different. A simple BCS estimate of the possible crystalline superconducting transition temperature gives an upper limit of 1.3 mK. The e-ph coupling is more preponderant in a-Bi than in crystalline bismuth (x-Bi) as indicated by the λ obtained via McMillan's formula, λc = 0.24 and experiment λa = 2.46. Therefore with respect to x-Bi, superconductivity in a-Bi is enhanced by the higher values of λ and of eDOS at the Fermi energy.

  2. Superconductivity: materials and applications

    International Nuclear Information System (INIS)

    Duchateau, J.L.; Kircher, F.; Leveque, J.; Tixador, P.

    2008-01-01

    This digest paper presents the different types of superconducting materials: 1 - the low-TC superconductors: the multi-filament composite as elementary constituent, the world production of NbTi, the superconducting cables of the LHC collider and of the ITER tokamak; 2 - the high-TC superconductors: BiSrCaCuO (PIT 1G) ribbons and wires, deposited coatings; 3 - application to particle physics: the the LHC collider of the CERN, the LHC detectors; 4 - applications to thermonuclear fusion: Tore Supra and ITER tokamaks; 5 - NMR imaging: properties of superconducting magnets; 6 - applications in electrotechnics: cables, motors and alternators, current limiters, transformers, superconducting energy storage systems (SMES). (J.S.)

  3. Single-mode fiber laser based on core-cladding mode conversion.

    Science.gov (United States)

    Suzuki, Shigeru; Schülzgen, Axel; Peyghambarian, N

    2008-02-15

    A single-mode fiber laser based on an intracavity core-cladding mode conversion is demonstrated. The fiber laser consists of an Er-doped active fiber and two fiber Bragg gratings. One Bragg grating is a core-cladding mode converter, and the other Bragg grating is a narrowband high reflector that selects the lasing wavelength. Coupling a single core mode and a single cladding mode by the grating mode converter, the laser operates as a hybrid single-mode laser. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area step-index fibers.

  4. Pulsed Laser Cladding of Ni Based Powder

    Science.gov (United States)

    Pascu, A.; Stanciu, E. M.; Croitoru, C.; Roata, I. C.; Tierean, M. H.

    2017-06-01

    The aim of this paper is to optimize the operational parameters and quality of one step Metco Inconel 718 atomized powder laser cladded tracks, deposited on AISI 316 stainless steel substrate by means of a 1064 nm high power pulsed laser, together with a Precitec cladding head manipulated by a CLOOS 7 axes robot. The optimization of parameters and cladding quality has been assessed through Taguchi interaction matrix and graphical output. The study demonstrates that very good cladded layers with low dilution and increased mechanical proprieties could be fabricated using low laser energy density by involving a pulsed laser.

  5. Enhancement of visible-light photocatalytic activity of silver and mesoporous carbon co-modified Bi2WO6

    International Nuclear Information System (INIS)

    Zhao, Qian; Gong, Ming; Liu, Wangping; Mao, Yulin; Le, Shukun; Ju, Shang; Long, Fei; Liu, Xiufang; Liu, Kai; Jiang, Tingshun

    2015-01-01

    Graphical abstract: - Highlights: • Silver and mesoporous carbon co-modified Bi 2 WO 6 (Ag/Bi 2 WO 6 /CMK-3) composite was prepared. • Photocatalytic activity of Bi 2 WO 6 was remarkably enhanced by co-modification of silver and mesoporous carbon. • The degradation rate of MB can reach ca. 95.1% under visible light irradiation. • The Ag/Bi 2 WO 6 /CMK-3 composite has good stability and potential application prospects. - Abstract: Ordered mesoporous carbon CMK-3 was prepared by hard template method using SBA-15 as template, sucrose as carbon source. Flower/sphere-like Bi 2 WO 6 and CMK-3/Bi 2 WO 6 photocatalysts were synthesized by hydrothermal method, and then Ag/Bi 2 WO 6 and Ag/Bi 2 WO 6 /CMK-3 composite photocatalysts were prepared via a photoreduction process. The samples were characterized by XRD, UV–vis, TEM (HR-TEM), SEM, N 2 physical adsorption and PL and their photocatalytic activities were evaluated by the photocatalytic degradation of methylene blue (MB) under visible light irradiation. The results show that both incorporating of CMK-3 and Ag loading greatly improved the photocatalytic activity of Bi 2 WO 6 , and the content of CMK-3 and silver have an impact on the photocatalytic activity of Bi 2 WO 6 . The photocatalytic activity of Ag/Bi 2 WO 6 /CMK-3 photocatalyst is superior to the activities of CMK-3/Bi 2 WO 6 and Ag/Bi 2 WO 6 under comparable conditions, and Ag/Bi 2 WO 6 /CMK-3 photocatalyst has high stability and is easy to be recycled. Also, the mechanism for the enhancement of the photocatalytic activity of CMK-3 and Ag co-modified Bi 2 WO 6 was also investigated

  6. Microstructural and wear characteristics of cobalt free, nickel base intermetallic alloy deposited by laser cladding

    International Nuclear Information System (INIS)

    Awasthi, Reena; Kumar, Santosh; Viswanadham, C.S.; Srivastava, D.; Dey, G.K.; Limaye, P.K.

    2011-01-01

    This paper describes the microstructural and wear characteristics of Ni base intermetallic hardfacing alloy (Tribaloy-700) deposited on stainless steel-316 L substrate by laser cladding technique. Cobalt base hardfacing alloys have been most commonly used hardfacing alloys for application involving wear, corrosion and high temperature resistance. However, the high cost and scarcity of cobalt led to the development of cobalt free hardfacing alloys. Further, in the nuclear industry, the use of cobalt base alloys is limited due to the induced activity of long lived radioisotope 60 Co formed. These difficulties led to the development of various nickel and iron base alloys to replace cobalt base hardfacing alloys. In the present study Ni base intermetallic alloy, free of Cobalt was deposited on stainless steel- 316 L substrate by laser cladding technique. Traditionally, welding and thermal spraying are the most commonly employed hardfacing techniques. Laser cladding has been explored for the deposition of less diluted and fusion-bonded Nickel base clad layer on stainless steel substrate with a low heat input. The laser cladding parameters (Laser power density: 200 W/mm 2 , scanning speed: 430 mm/min, and powder feed rate: 14 gm/min) resulted in defect free clad with minimal dilution of the substrate. The microstructure of the clad layer was examined by Optical microscopy, Scanning electron microscopy, with energy dispersive spectroscopy. The phase analysis was performed by X-ray diffraction technique. The clad layer exhibited sharp substrate/clad interface in the order of planar, cellular, and dendritic from the interface upwards. Dilution of clad with Fe from substrate was very low passing from ∼ 15% at the interface (∼ 40 μm) to ∼ 6% in the clad layer. The clad layer was characterized by the presence of hexagonal closed packed (hcp, MgZn 2 type) intermetallic Laves phase dispersed in the eutectic of Laves and face centered cubic (fcc) gamma solid solution. The

  7. First results on T91 claddings with and without modified FeCrAlY coatings exposed in PbBi under varying conditions

    International Nuclear Information System (INIS)

    Weisenburger, A.; Heinzel, A.; Miller, G.; Rousanov, A.

    2008-01-01

    It is well known that at temperatures above 500 deg C low activation austenitic steels suffer from severe corrosion in lead or lead-bismuth. Low activation martensitic steels instead form under similar conditions concerning temperature and oxygen content thick oxide scales that periodically may span off. Both groups of materials are therefore restricted to areas having lower temperature load. For parts that are intended to be used in high-temperature regions, like claddings, surface protection has to be applied. From gas turbines the role of elements forming thin stable oxide scales is well understood. The concept chosen here for thermally high loaded parts, the claddings, is the deposition of a FeCrAlY coating of about 30 vt,m thickness that is afterwards re-melted applying a pulsed electron beam (GESA). The beam energy is adjusted in a way to melt the entire coating together with a few thin region of the bulk to create a perfect intermixing at the boundary. This results in a new surface area of the cladding with an aluminium content of the order of 5 wt.% that will be sufficiently high to grow thin stable oxide scales. This concept is proven for austenitic cladding materials like 1.4970 as well as for martensitic ones like T91. In long-term corrosion tests the compatibility to Pb or PbBi, the resistance against corrosion and severe oxidation, was clearly demonstrated. No negative response of such a modified coating on the mechanical properties and the stability under irradiation has been observed as of yet. This paper will focus on the surface modification process, the corrosion results thus far obtained and on the evaluation of some mechanical properties. For example, the swelling of the fuel by irradiation will lead during operation to an increase of the internal pressure. This is simulated in experiments where an internal pressure of defined value was applied on T91 cladding tubes. The influence of flow velocity between to 3 m/s on the oxidation behaviour of T

  8. Effect of cooldown and residual magnetic field on the performance of niobium–copper clad superconducting radio-frequency cavity

    International Nuclear Information System (INIS)

    Dhakal, Pashupati; Ciovati, Gianluigi

    2017-01-01

    Here, we present the results of rf measurements on a niobium–copper clad superconducting radio-frequency cavity with different cooldown conditions and residual magnetic field in a vertical test Dewar in order to explore the effect of thermal current induced magnetic field and its trapping on the performance of the cavity. The residual resistance, extracted from the Q 0 (T) curves in the temperature range 4.3–1.5 K, showed no dependence on a temperature gradient along the cavity during the cooldown across the critical temperature up to ~50 K m –1 . The rf losses due to the trapping of residual magnetic field during the cavity cooldown were found to be ~4.3 nΩ μT –1 , comparable to the values measured in bulk niobium cavities. An increase of residual resistance following multiple cavity quenches was observed along with evidence of trapping of magnetic flux generated by thermoelectric currents.

  9. Conduction spectroscopy of a proximity induced superconducting topological insulator

    Science.gov (United States)

    Stehno, M. P.; Hendrickx, N. W.; Snelder, M.; Scholten, T.; Huang, Y. K.; Golden, M. S.; Brinkman, A.

    2017-09-01

    The combination of superconductivity and the helical spin-momentum locking at the surface state of a topological insulator (TI) has been predicted to give rise to p-wave superconductivity and Majorana bound states. The superconductivity can be induced by the proximity effect of a s-wave superconductor (S) into the TI. To probe the superconducting correlations inside the TI, dI/dV spectroscopy has been performed across such S-TI interfaces. Both the alloyed Bi1.5Sb0.5Te1.7Se1.3 and the stoichiometric BiSbTeSe2 have been used as three-dimensional TI. In the case of Bi1.5Sb0.5Te1.7Se1.3, the presence of disorder induced electron-electron interactions can give rise to an additional zero-bias resistance peak. For the stoichiometric BiSbTeSe2 with less disorder, tunnel barriers were employed in order to enhance the signal from the interface. The general observations in the spectra of a large variety of samples are conductance dips at the induced gap voltage, combined with an increased sub-gap conductance, consistent with p-wave predictions. The induced gap voltage is typically smaller than the gap of the Nb superconducting electrode, especially in the presence of an intentional tunnel barrier. Additional uncovered spectroscopic features are oscillations that are linearly spaced in energy, as well as a possible second order parameter component.

  10. Superconductivity and ceramic superconductors II; Proceedings of the Symposium, Orlando, FL, Nov. 12-15, 1990. Ceramic transactions. Vol. 18

    International Nuclear Information System (INIS)

    Nair, K.M.; Balachandran, U.; Chiang, Y.-M.; Bhalla, A.S.

    1991-01-01

    The present symposium on superconductivity and ceramic superconductors discusses fundamentals and general principles, powder processing and properties, fabrication and properties, and device reliability and applications. Attention is given to phase formation in the Tl-Ca-Ba-Cu-O system, comparative defect studies in La2CuO4 and La2NiO4, solid solution and defect behavior in high Tc oxides, oxygen ion transport and disorder in cuprates, and Sr-free Bi-Ln-Ca-Cu-O superconductors. Topics addressed include the preparation of superconductor Y-Ba-Cu-O powder by single-step calcining in air, low-temperature synthesis of YBa2Cu3O(7-x), synthesis of high-phase purity ceramic oxide superconductors by the xerogel method, and the preparation and characterization of the BYa2Cu4O8 superconductor. Also discussed are optical studies of humidity-based corrosion effects on thin film and bulk ceramic YBa2Cu3O(7-delta), thermomechanical processing of YBa2Cu3O(x)/Ag sheathed wires, and the expansion of high-Tc superconducting ceramics

  11. Correlation of the superconducting transition to oxygen stoichiometry in single-crystal Ba1-xKxBiO3-y

    Science.gov (United States)

    Mosley, W. D.; Dykes, J. W.; Klavins, P.; Shelton, R. N.; Sterne, P. A.; Howell, R. H.

    1993-07-01

    Temperature-dependent positron-lifetime experiments have been performed from room temperature to 15 K on single crystals of the oxide superconductor Ba1-xKxBiO3-y. Results indicate that the filling of oxygen vacancies has a marked impact on the superconducting properties of this system. Cation defect concentrations were below the detectable limit of positron-annihilation-analysis techniques in this material, which is in sharp contrast to identical studies on polycrystalline samples. We find that the positron lifetime in these electrochemically deposited single crystals is determined by the oxygen stoichiometry of the lattice, but there is no experimental signature of strong positron localization. By performing a subsequent oxygen anneal on the crystals, the superconducting transition is sharpened and the onset is raised. The observed change in positron lifetime associated with this annealing procedure is in quantitative agreement with theory.

  12. Oxygen stoichiometry and its influence on superconductivity in Bi2Sr2CaCu2O8+x

    International Nuclear Information System (INIS)

    Krishnaraj, P.; Lelovic, M.; Eror, N.G.; Balachandran, U.

    1994-01-01

    Bi 2 Sr 2 CaCu 2 O 8+x (2212) was synthesized from freeze-dried precursors. The oxygen content of 2212 was determined as a function of temperature and oxygen partial pressure and the variation of Tc with oxygen content was determined. It was found that 2212 without excess oxygen (x = 0) is superconducting. This points to the role of the (Bi-O) ∞ layers as a source for holes in 2212. Four probe resistivity measurements were also performed on 2212. The nature of oxygen intercalation and oxygen removal in 2212 was studied by thermogravimetry and resistivity. It was also found that samples of 2212 with the same oxygen content had different T c 's depending on thermal history. This difference in T c is thought to arise from oxygen occupying different sites in the lattice while maintaining the same total oxygen content

  13. Cladding Alloys for Fluoride Salt Compatibility

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan [ORNL; Wilson, Dane F [ORNL; Walker, Larry R [ORNL; Santella, Michael L [ORNL; Holcomb, David Eugene [ORNL

    2011-06-01

    This report provides an overview of several candidate technologies for cladding nickel-based corrosion protection layers onto high-temperature structural alloys. The report also provides a brief overview of the welding and weld performance issues associated with joining nickel-clad nickel-based alloys. From the available techniques, two cladding technologies were selected for initial evaluation. The first technique is a line-of-sight method that would be useful for cladding large structures such as vessel interiors or large piping. The line-of-sight method is a laser-based surface cladding technique in which a high-purity nickel powder mixed into a polymer binder is first sprayed onto the surface, baked, and then rapidly melted using a high-power laser. The second technique is a vapor phase technique based on the nickel-carbonyl process that is suitable for cladding inaccessible surfaces such as the interior surfaces of heat exchangers. An initial evaluation for performed on the quality of nickel claddings processed using the two selected cladding techniques.

  14. Cladding Effects on Structural Integrity of Nuclear Components

    International Nuclear Information System (INIS)

    Sattari-Far, Iradi; Andersson, Magnus

    2006-06-01

    Based on this study, the following conclusions and recommendations can be made: Due to significant differences in the thermal and mechanical properties between the austenitic cladding and the ferritic base metal, residual stresses are induced in the cladding and the underlying base metal. These stresses are left in clad components even after Post-Weld Heat Treatment (PWHT). The different restraint conditions of the clad component have a minor influence on the magnitude of the cladding residual stresses in the cladding layer. The thickness of the clad object is the main impacting geometrical dimension in developing cladding residual stresses. A clad object having a base material thickness exceeding 10 times the cladding thickness would be practically sufficient to introduce cladding residual stresses of a thick reactor pressure vessel. For a clad component that received PWHT, the peak tensile stress is in the cladding layer, and the residual stresses in the underlying base material are negligible. However, for clad components not receiving PWHT, for instance the repair welding of the cladding, the cladding residual stresses of tensile type exist even in the base material. This implies a higher risk for underclad cracking for clad repairs that received no PWHT. For certain clad geometries, like nozzles, the profile of the cladding residual stresses depends on the clad thickness and position, and significant tensile stresses can also exist in the base material. Based on different measurements reported in the literature, a value of 150 GPa can be used as Young's Modulus of the austenitic cladding material at room temperature. The control measurements of small samples from the irradiated reactor pressure vessel head did not reveal a significant difference of Young's Modulus between the irradiated and the unirradiated cladding material condition. No significant differences between the axial and tangential cladding residual stresses are reported in the measurement of

  15. Development of high J c Bi2223/Ag thick film materials prepared by heat treatment under low P O2

    Science.gov (United States)

    Takeda, Y.; Shimoyama, J.; Motoki, T.; Nakamura, S.; Nakashima, T.; Kobayashi, S.; Kato, T.

    2018-07-01

    In general, a dense and c-axis grain-oriented microstructure is desirable in order to achieve the high critical current properties of Bi2223 polycrystalline materials. On the other hand, our recent studies have shown that precise control of the chemical compositions of Bi2223 is also effective for the enhancement of intergrain J c. In this study, the development of Bi2223 thick film materials with high critical current properties was attempted by controlling both the microstructure and the chemical compositions. A high intergrain J c of ∼8 kA cm‑2 at 77 K of a film with ∼40 μm t was achieved by increasing the Pb substitution level for the Bi site and controlling the nonstoichiometric chemical compositions. Furthermore, it was revealed that an increase in the thickness enabled us to obtain high I c films suitable for practical applications. In contrast, there are still issues, especially in controlling the grain alignment at the inner part of the film, which suggests that the J c properties of thick film materials could be further improved by forming a more ideal microstructure, as realized in the Bi2223 filaments of multi-filamentary Ag-sheathed tapes.

  16. Melt processing of Bi-Ca-Sr-Cu-O superconductors

    International Nuclear Information System (INIS)

    Zanotto, E.D.; Cronin, J.P.; Dutta, B.

    1988-01-01

    Several Bi-Ca-Sr-Cu-O compositions were melted in Al/sub 2/O/sub 3/ or Pt crucibles at temperatures between 1050C and 1200C. As-quenched specimens crystallized from the upper surfaces, while the bottom layers were glassy. Glass formation was improved for higher Bi/sub 2/O/sub 3/ concentrations. The crystalline portions were highly conductive, while the glassy layers were insulating. Both did not show superconductivity down to 10K. Thermal treatment in air caused a dramatic effect on the electronic properties; and annealing at 865C for long periods converted the two types of specimens (previously glassy or crystalline) to superconductors, at least for one composition. Aluminum impurity (up to 8.6 atom. pct.) had no detectable effect on the transition temperatures, i.e., T/sub c/ 85K for all superconducting samples. The flake-like (Bi/sub 2/Ca/sub 1/Sr/sub 2/Cu/sub 2/) phase, reported by other authors, was responsible for superconductivity

  17. Effect of dc field on ac-loss peak in a commercial Bi:2223/Ag tape

    Science.gov (United States)

    Öztürk, Ali; Düzgün, İbrahim; Çelebi, Selahattin

    2017-12-01

    Measurements of the ac susceptibility in a commercial Bi:2223/Ag tape for some different ac magnetic field amplitudes, Hac, in the presence of bias magnetic field Hdc directed along Hac are reported. It is found that the peak values of the imaginary component of ac susceptibility χ″max versus Hac trace a valley for the orientation where applied field Ha perpendicular to wide face of the tape total. We note that the observation of the valley depends on various parameters such as field dependence parameter n in the critical current density, in the simple power law expression jc = α(T)/Bn, choice of the bias field Hdc together with selected ac field amplitudes Hac, and dimension and geometry of sample studied. Our calculations based on critical state model with jc = α(1 - T/Tcm)p/Bn using the fitting parameters of n = 0.25, p = 2.2, Tcm = 108 K gives quite good results to compare the experimental and calculated curves.

  18. Cladding Effects on Structural Integrity of Nuclear Components

    Energy Technology Data Exchange (ETDEWEB)

    Sattari-Far, Iradi; Andersson, Magnus [lnspecta Technology AB, Stockholm (Sweden)

    2006-06-15

    Based on this study, the following conclusions and recommendations can be made: Due to significant differences in the thermal and mechanical properties between the austenitic cladding and the ferritic base metal, residual stresses are induced in the cladding and the underlying base metal. These stresses are left in clad components even after Post-Weld Heat Treatment (PWHT). The different restraint conditions of the clad component have a minor influence on the magnitude of the cladding residual stresses in the cladding layer. The thickness of the clad object is the main impacting geometrical dimension in developing cladding residual stresses. A clad object having a base material thickness exceeding 10 times the cladding thickness would be practically sufficient to introduce cladding residual stresses of a thick reactor pressure vessel. For a clad component that received PWHT, the peak tensile stress is in the cladding layer, and the residual stresses in the underlying base material are negligible. However, for clad components not receiving PWHT, for instance the repair welding of the cladding, the cladding residual stresses of tensile type exist even in the base material. This implies a higher risk for underclad cracking for clad repairs that received no PWHT. For certain clad geometries, like nozzles, the profile of the cladding residual stresses depends on the clad thickness and position, and significant tensile stresses can also exist in the base material. Based on different measurements reported in the literature, a value of 150 GPa can be used as Young's Modulus of the austenitic cladding material at room temperature. The control measurements of small samples from the irradiated reactor pressure vessel head did not reveal a significant difference of Young's Modulus between the irradiated and the unirradiated cladding material condition. No significant differences between the axial and tangential cladding residual stresses are reported in the

  19. Reinforced fluropolymer nanocomposites with high-temperature superconducting Bi2Sr2CaCu2Oy

    Science.gov (United States)

    Jayasree, T. K.

    2014-10-01

    Bismuth Strontium Calcium Copper Oxide (Bi2Sr2CaCu2Oy)/Polyvinylidene fluoride (PVDF) nanocomposite was prepared and their thermal properties were analyzed. The composite consists of the polyvinylidene fluoride (PVDF) as an insulating polymer matrix, and homogenously distributed Bismuth strontium calcium copperoxide (2212) nanoparticles. SEM data shows flaky grains of the superconductor coated and linked by polymer. Differential scanning calorimetry (DSC) results indicated that the melting point was not affected significantly by the addition of BSCCO. However, the addition of superconducting ceramic resulted in an extra melting peak at a lower temperature (145°C). Thermogravimetric analysis of the samples shows that the onset decomposition temperature of the PVDF matrix was decreased by the addition of SC filler.

  20. Nonphonon mechanism of superconductivity in compounds of transition metals

    International Nuclear Information System (INIS)

    Ivanov, V.A.; Zaitsev, R.O.

    1989-01-01

    The kinematical mechanism of superconductivity is applied to the Emery-Hirsch model for the CuO 2 and BiO 3 layers. A superconducting region due to strong kinematic interaction of p- and s, d-electrons are determined as a function of n p and n s,d -degrees of non-filling of 2p 6 ,6s 2 ,3d 10 shells of O 2 - ,Bi 3 + ,Cu + . The T c is calculated taking into account the spin flip relaxation time. Magnetostatic properties of a superconducting state in a weak magnetic field are investigated. Coefficients of the Ginzburg-Landau equation are calculated. The ground state energy of the Emery-Hirsch model is also calculated

  1. On one possibility for application of new thermoelectric materials based on Ag2Te

    International Nuclear Information System (INIS)

    Vassilev, Venceslav; Parvanov, Svetlin; Vachkov, Valeri

    2011-01-01

    The thermoelectric characteristics of Ag 2 Te and Ag 1,84 Cd 0,08 Te (solid solution based on Ag 2 Te) are investigated and analyzed. The main thermoelectric characteristics of the solid solution: α=118 μV/K; σ = 2230 S/cm and = 2,45.10 -2 W/(cm.K) ensure coefficient of thermoelectric efficiency z = 1,27. 10-3 K -1 (at 300 ), which increases this of the Ag 2 Te. A composition for commutation material is developed, which connects the N- and the P-branches of a single thermo element (52 wt. % In + 48 wt. % Sn) with melting temperature of 390 K. The possibility for application of the Ag 1,84 Cd 0,08 Te solid solution as N-branch of a thermo element in combination with the solid solution Bi 0,5 Sb 1,5 Te 3 (P-branch) is investigated. The thermo element guarantees values of z from 0,71.10 -3 to 1,27.10 -3 K -1 in the temperature interval 250 - 350 . The maximum z value is registered at 300 K (z = 1,27.10 -3 K -1 ). Keywords: Silver telluride, Solid solutions, Thermoelectric properties, Thermo element

  2. Superconducting properties of Bi-based ceramics with column 3A elements

    Czech Academy of Sciences Publication Activity Database

    Smrčková, O.; Sýkorová, D.; Rubešová, K.; Vašek, Petr

    2002-01-01

    Roč. 321, - (2002), s. 292-294 ISSN 0921-4526 R&D Projects: GA ČR GA106/99/1441; GA ČR GA104/99/1440 Institutional research plan: CEZ:AV0Z1010914 Keywords : Bi2223 * substitution B, Al, Ca, In * critical phenomena Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.609, year: 2002

  3. Void and Phase Evolution during the Processing of Bi-2212 Superconducting Wires monitored by combined fast Synchrotron Micro-tomography and X-Ray Diffraction

    CERN Document Server

    Scheuerlein, C; Scheel, M; Jiang, J; Kametani, F; Malagoli, A; Hellstrom, E E; Larbalestier, D C

    2011-01-01

    Recent study of the current-limiting mechanisms in Bi-2212 round wires has suggested that agglomeration of the residual Bi-2212 powder porosity into bubbles of filament-diameter size occurs on melting the Bi-2212 filaments. These pores introduce a major obstacle to current flow, which greatly reduces the critical current density (Jc). Here we present an in situ non-destructive tomographic and diffraction study of the changes occurring during the heat treatment of wires and starting powder, as well as a room temperature study of ex situ processed wires. The in situ through-process study shows that the agglomeration of residual porosity is more complex than previously seen. Filament changes start with coalescence of the quasi-uniform and finely divided powder porosity into lens-shaped defects at about 850 0C when the Bi-2201 impurity phase decomposes before the Bi-2212 starts to melt. These lens-shaped voids grow to bubbles of a filament diameter on melting of the Bi-2212 and continue to lengthen and then to ag...

  4. On the relations among the pseudogap, electronic charge order and Fermi-arc superconductivity in Bi2Sr2CaCu2O8+δ

    International Nuclear Information System (INIS)

    Oda, M; Liu, Y H; Kurosawa, T; Takeyama, K; Ido, M; Momono, N

    2008-01-01

    On the basis of STM/STS, break-junction tunneling and electronic Raman scattering experiments on Bi 2 Sr 2 CaCu 2 O 8+δ reported so far, we suggest that the static, electronic charge order is associated with inhomogeneous electronic states on antinodal parts of the Fermi surface that are outside the Fermi-arc around the node and responsible for the pseudogap, and coexists with the homogeneous superconductivity caused by the pairing of coherent quasiparticles on the Fermi-arc, the so-called 'Fermi-arc superconductivity', in the real space, although the two electronic orders or the corresponding energy gaps compete with each other in the k-space

  5. Laser cladding of a Mg based Mg–Gd–Y–Zr alloy with Al–Si powders

    International Nuclear Information System (INIS)

    Chen, Erlei; Zhang, Kemin; Zou, Jianxin

    2016-01-01

    Graphical abstract: A Mg based Mg–Gd–Y–Zr alloy was treated by laser cladding with Al–Si powders at different laser scanning speeds. The laser clad layer mainly contains Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases distributed in the Mg matrix. After laser cladding, the corrosion resistance of the Mg alloy was significantly improved together with increased microhardness in the laser clad layers. - Highlights: • A Mg based Mg–Gd–Y–Zr alloy was laser clad with Al–Si powders. • The microstructure and morphology vary with the depth of the clad layer and the laser scanning speed. • Hardness and corrosion resistance were significantly improved after laser cladding. - Abstract: In the present work, a Mg based Mg–Gd–Y–Zr alloy was subjected to laser cladding with Al–Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from −1.77 V for the untreated alloy to −1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10"−"5 A cm"−"2 to 1.64 × 10"−"6 A cm"−"2. The results show that laser cladding is an efficient method to improve surface properties of Mg–Rare earth alloys.

  6. Laser patterning: A new approach to measure local magneto-transport properties in multifilamentary superconducting tapes

    International Nuclear Information System (INIS)

    Sanchez Valdes, C.F.; Perez-Penichet, C.; Noda, C.; Arronte, M.; Batista-Leyva, A.J.; Haugen, O.; Johansen, T.H.; Han, Z.; Altshuler, E.

    2007-01-01

    The determination of inter- and intra-filament characteristics in superconducting composites such as BSCCO-Ag tapes is of great importance for material evaluation towards applications. Most attempts to separate the two contributions have relied on indirect methods based on magnetic measurements such as SQUID or magneto-optic imaging techniques. Here we show that laser patterning of superconducting BSCCO-Ag tapes constitutes a simple approach to measure local transport properties in a direct way, even able to separate inter- and intra-filament contributions to the overall transport behavior of the sample

  7. Development of Pb-rich (Bi, Pb) sub 3 Sr sub 2 Ca sub 2 Cu sub 1 O sub x phase during reformation of lead doped 2223 superconducting phase from melt quenched glass. [BiPbSrCaCuO

    Energy Technology Data Exchange (ETDEWEB)

    Oezkan, N; Glowacki, B A [IRC in Superconductivity, Univ. of Cambridge (United Kingdom)

    1992-05-01

    The reformation process of the lead doped superconducting 2223 phase from the melt quenched glass was investigated. It was shown that during the crystallisation of the glass a new lead rich phase, Bi{sub 0.5}Pb{sub 3}Sr{sub 2}Ca{sub 2}Cu{sub 1}O{sub x}, was formed and severe copper segregation was observed. The volume fraction of the high Tc 2223 phase increased with annealing time for an annealing temperature of 840degC. A glass sample annealed at 840degC for 150 h showed two superconducting transitions Tc = 107 K and Tc = 70 K. (orig.).

  8. Analysis of stress-strain behavior in Bi2223 composite tapes

    International Nuclear Information System (INIS)

    Sugano, M.; Osamura, K.; Nyilas, A.

    2004-01-01

    Tensile test was carried out for Bi2223/Ag/Ag alloy composite tapes at RT, 77 and 7 K. Two yielding points are observed in the stress-strain curves. From the stress-strain behavior of the components and critical current (I c ) as a function of tensile strain, it was found that the microscopic reason for these yieldings is attributed to yielding of Ag alloy and fracture of Bi2223, respectively. The strain at the second yielding has temperature dependence and it becomes larger with decreasing measured temperature. From the thermo-mechanical analysis, it can be explained by temperature dependence of compressive residual strain of Bi2223. Reversible recovery of I c was found during loading-unloading test. The relationship between the reversible strain limit and the intrinsic strain of Bi2223 was discussed

  9. Microscopic Analysis and Electrochemical Behavior of Fe-Based Coating Produced by Laser Cladding

    Directory of Open Access Journals (Sweden)

    Jinlin Chen

    2017-10-01

    Full Text Available The effect of laser cladding on the surface microstructure and corrosion properties of coated/uncoated specimens were investigated. Fe-based alloy coating was produced on 35CrMo steel by laser cladding. The phase composition, microstructure, interface element distribution, microhardness and corrosion resistance of the cladding coating were measured. The results show that the cladding layer is mainly composed of α-Fe phases, the microstructure presents a gradient distribution, and a good metallurgical bond is formed at the boundary with the substrate. Microhardness profiles show that the average microhardness of the cladding coating is about 2.1 times higher than that of the uncoated specimen. In addition, the electrochemical results show that the coated specimen exhibits far better corrosion resistance than to the uncoated specimen.

  10. Extensive Characterisation of Copper-clad Plates, Bonded by the Explosive Technique, for ITER Electrical Joints

    CERN Document Server

    Langeslag, S A E; Libeyre, P; Gung, C Y

    2015-01-01

    Cable-in-conduit conductors will be extensively implemented in the large superconducting magnet coils foreseen to confine the plasma in the ITER experiment. The design of the various magnet systems imposes the use of electrical joints to connect unit lengths of superconducting coils by inter-pancake coupling. These twin-box lap type joints, produced by compacting each cable end in into a copper - stainless steel bimetallic box, are required to be highly performing in terms of electrical and mechanical prop- erties. To ascertain the suitability of the first copper-clad plates, recently produced, the performance of several plates is studied. Validation of the bonded interface is carried out by determining microstructural, tensile and shear characteristics. These measure- ments confirm the suitability of explosion bonded copper-clad plates for an overall joint application. Additionally, an extensive study is conducted on the suitability of certain copper purity grades for the various joint types.

  11. Reference Data for the Density, Viscosity, and Surface Tension of Liquid Al-Zn, Ag-Sn, Bi-Sn, Cu-Sn, and Sn-Zn Eutectic Alloys

    Science.gov (United States)

    Dobosz, Alexandra; Gancarz, Tomasz

    2018-03-01

    The data for the physicochemical properties viscosity, density, and surface tension obtained by different experimental techniques have been analyzed for liquid Al-Zn, Ag-Sn, Bi-Sn, Cu-Sn, and Sn-Zn eutectic alloys. All experimental data sets have been categorized and described by the year of publication, the technique used to obtain the data, the purity of the samples and their compositions, the quoted uncertainty, the number of data in the data set, the form of data, and the temperature range. The proposed standard deviations of liquid eutectic Al-Zn, Ag-Sn, Bi-Sn, Cu-Sn, and Sn-Zn alloys are 0.8%, 0.1%, 0.5%, 0.2%, and 0.1% for the density, 8.7%, 4.1%, 3.6%, 5.1%, and 4.0% for viscosity, and 1.0%, 0.5%, 0.3%, N/A, and 0.4% for surface tension, respectively, at a confidence level of 95%.

  12. On the superconducting state in Ba0.6K0.4BiO3 perovskite oxide

    Science.gov (United States)

    Szcześniak, D.; Kaczmarek, A. Z.; Drzazga, E. A.; Szewczyk, K. A.; Szcześniak, R.

    2018-05-01

    We report study on the superconducting state in Ba0.6K0.4BiO3 (BKBO) perovskite oxide, motivated by the inconclusive results on the pairing mechanism in this compound. Our investigations are conducted within the Migdal-Eliashberg formalism, to account for the phonon-mediated superconducting phase. The considered doping level of the discussed material corresponds to the highest critical temperature in this compound, and allows simultaneous analysis of the oxygen isotope effect, for the O16 and O18 isotopes, respectively. We found that such effect is particularly visible for the critical values of the Coulomb pseudopotential (μC⋆) , which equals to 0.18 for the O16 and 0.16 for the O18 isotope in BKBO. Moreover, we determine the size of the superconducting energy band gap (Δg) and note that obtained values (9.68 meV and 9.55 meV for the O16 and O18, respectively) are in good agreement with the experimental predictions which give Δg ∼ 8.68 meV . Finally, we calculate the characteristic dimensionless parameters, such as the zero-temperature energy gap to the critical temperature, the ratio for the specific heat, as well as the ratio associated with the zero-temperature thermodynamic critical field, which suggest occurrence of the strong-coupling and retardation effects within the phonon-mediated scenario in the analyzed material. Where possible the dimensionless ratios are compared to the experimental estimates, and agrees with these which account for the strong-coupling character of the BKBO superconductor.

  13. Electra-Clad

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-05-04

    The study relates to the use of building-integrated photovoltaics. The Electra-Clad project sought to use steel-based cladding as a substrate for direct fabrication of a fully integrated solar panel of a design similar to the ICP standard glass-based panel. The five interrelated phases of the project are described. The study successfully demonstrated that the principles of the panel design are achievable and sound. But, despite intensive trials, a commercially realistic solar performance has not been achieved: the main failing was the poor solar conversion efficiency as the active area of the panel was increased in size. The problem lies with the coating used on the steel cladding substrates and it was concluded that a new type of coating will be required. ICP Solar Technologies UK carried out the work under contract to the DTI.

  14. Cladding technique for development of Ag-In-Cd decoupler

    International Nuclear Information System (INIS)

    Teshigawara, M.; Harada, M.; Saito, S.; Kikuchi, K.; Kogawa, H.; Ikeda, Y.; Kawai, M.; Kurishita, H.; Konashi, K.

    2005-01-01

    To develop a Ag (silver)-In (indium)-Cd (cadmium) alloy decoupler, a method is needed to bond the decoupler between two plates of the Al alloy (A6061-T6). We found that a better HIP condition was temperature, pressure and holding time at 803 K, 100 MPa and 1 h, respectively, for small test pieces (φ 22 mm in diam. x 5 mm in height). Especially, a sandwich case (a Ag-In plate with thickness of 0.5 mm between two Ag-Cd plates with thickness of 1.25 mm) gave easier (or better) bonding results. Though a hardened layer is found in the bonding layer, the rupture strength of the bonding layer is more than 30 MPa, which is higher than the design stress in our application

  15. Laser cladding of a Mg based Mg–Gd–Y–Zr alloy with Al–Si powders

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Erlei [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zhang, Kemin, E-mail: zhangkm@sues.edu.cn [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zou, Jianxin [National Engineering Research Center of Light Alloys Net Forming & School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2016-03-30

    Graphical abstract: A Mg based Mg–Gd–Y–Zr alloy was treated by laser cladding with Al–Si powders at different laser scanning speeds. The laser clad layer mainly contains Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases distributed in the Mg matrix. After laser cladding, the corrosion resistance of the Mg alloy was significantly improved together with increased microhardness in the laser clad layers. - Highlights: • A Mg based Mg–Gd–Y–Zr alloy was laser clad with Al–Si powders. • The microstructure and morphology vary with the depth of the clad layer and the laser scanning speed. • Hardness and corrosion resistance were significantly improved after laser cladding. - Abstract: In the present work, a Mg based Mg–Gd–Y–Zr alloy was subjected to laser cladding with Al–Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from −1.77 V for the untreated alloy to −1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10{sup −5} A cm{sup −2} to 1.64 × 10{sup −6} A cm{sup −2}. The results show that laser cladding is an efficient method to improve

  16. Development of low AC loss windings for superconducting traction transformer

    International Nuclear Information System (INIS)

    Kamijo, H; Hata, H; Fukumoto, Y; Tomioka, A; Bohno, T; Yamada, H; Ayai, N; Yamasaki, K; Kato, T; Iwakuma, M; Funaki, K

    2010-01-01

    We have been developing a light weight and high efficiency superconducting traction transformer for railway rolling stock. We designed and fabricated a prototype superconducting traction transformer of a floor-mount type for Shinkansen rolling stock in 2004. We performed the type-test, the system-test, and the vibration-test. Consequently, we could verify that the transformer satisfied the requirement almost exactly as initially planned. However, there have been raised some problems to be solved to put superconducting traction transformer into practical use such that AC loss of the superconducting tape must be lower and the capacity of the refrigerator must be larger. Especially it is the most important to reduce the AC loss of superconducting windings for lightweight and high efficiency. The AC loss must be reduced near the theoretical value of superconducting tape with multifilament. In this study, we fabricated and evaluated the Bi2223 tapes as introduced various measures to reduce the AC loss. We confirmed that the AC loss of the narrow type of Bi2223 tapes with twist of filaments is lower, and we fabricated windings of this tape for use in superconducting traction transformer.

  17. Fabrication of Ba-K-Bi-O thick film artefacts with improved critical currents

    International Nuclear Information System (INIS)

    Moore, J.C.; Salter, C.J.; Jenkins, R.J.; Grovenor, C.R.M.; Jones, H.

    1993-01-01

    The Ba-K-Bi-O system has a maximum T c of around 30K for a composition of Ba 0.6 K 0.4 BiO 3 . Fabrication of good quality single phase samples is extremely difficult and requires careful control of the fabrication conditions. Successful synthesis procedures for Ba-K-Bi-O powder and melt cast material which allow some control of the potassium content of the product were established by Hinks et al. The process is based on a melt and sinter step in an inert atmosphere which creates oxygen vacancies and allows potassium to enter the lattice. The oxygen vacancies are then filled by a subsequent oxygen anneal to obtain superconductivity. Ba-K-Bi-O is, therefore, metastable and consequently difficult to synthesise. There have been few reports of transport measurements and even fewer reports of transport critical currents for bulk material. It is often accepted that Ba-K-Bi-O has an intrinsically low critical current, and extremely poor critical current densities of 0.05 Acm -2 have been quoted for melt cast material. It has been suggested that the presence of weak links is the cause. However, there has been little research into the relationship between process conditions and superconducting properties for melt processed Ba-K-Bi-O to confirm this. (orig.)

  18. Current high-temperature superconducting coils and applications in Japan

    International Nuclear Information System (INIS)

    Matsushita, T.

    2000-01-01

    In Japan, four projects for the application of Bi-based superconducting magnets to practical apparatus are currently underway. These projects involve the development of an insert magnet for a 1 GHz nuclear magnetic resonance spectrometer, a magnet for a silicon single-crystal pulling apparatus, a magnet for a magnetic separation system, and a 1 T pulse magnet for a superconducting magnet energy storage system. For example, the magnet for the silicon single-crystal pulling apparatus is of the class with stored energy of 1 MJ to be operated at around 20 K. This review focuses on the present status of the development of these magnets, followed by a discussion of the problems of the present superconducting tapes that need to be overcome for future applications. (author)

  19. The impedance of inductive superconducting fault current limiters operating with stacks of thin film Y123/Au washers or bulk Bi2223 rings as secondaries

    International Nuclear Information System (INIS)

    Fernandez, J A Lorenzo; Osorio, M R; Toimil, P; Ferro, G; Blanch, M; Veira, J A; Vidal, F

    2006-01-01

    Inductive fault current limiters operating with stacks of various small superconducting elements acting as secondaries were studied. The stacks consist of Y 1 Ba 2 Cu 3 O 7-δ thin film washers or Bi 1.8 Pb 0.26 Sr 2 Ca 2 Cu 3 O 10+x bulk rings. A central result of our work is an experimental demonstration that the limiting capability of the device is strongly reduced when several bulk rings are stacked, whereas it remains almost unchanged for thin film washers. The use of thin films should therefore allow us to build more efficient high power inductive limiters based on stacks of small washers

  20. Processing of bulk Bi-2223 high-temperature superconductor

    Directory of Open Access Journals (Sweden)

    Alexander Polasek

    2005-12-01

    Full Text Available The Bi2Sr2Ca2Cu3 O10+x (Bi-2223 is one of the main high temperature superconductors for applications. One of these applications is the Superconductor Fault Current Limiter (SCFCL, which is a very promising high temperature superconducting device. SCFCL's can be improved by using bulk superconductors with high critical currents, which requires a sufficiently dense and textured material. In the present work, a process for improving the microstructure of Bi-2223 bulk samples is investigated. Pressed precursor blocks are processed by sintering with a further partial melting step, in order to enhance the Bi-2223 grain texture and to healing cracks induced by pressing. In order to improve the microstructure, the precursor is mixed with silver powder before pressing. Samples with and without silver powder have been studied, with the aim of investigating the influence of silver on the microstructure evolution. The phase contents and the microstructure obtained have been analyzed through XRD and SEM/EDS. The electromagnetic characterization has been performed by Magnetic Susceptibility Analysis. We present and discuss the process and the properties of the superconducting blocks. High fractions of textured Bi-2223 grains have been obtained.

  1. Inducing phase decomposition and superconductivity of Bi2Sr2CaCu2Oy single crystals treated in sulphur atmosphere at low temperature

    International Nuclear Information System (INIS)

    Chen, Q.W.; China Univ. of Science and Technology, Hefei, AH; Wu, W.B.; Qian, Y.T.; China Univ. of Science and Technology, Hefei, AH; Wang, L.B.; Li, F.Q.; Zhou, G.E.; Chen, Z.Y.; Zhang, Y.H.

    1995-01-01

    As it has been pointed out, phase decomposition which may be hard to be detected in a polycrystalline system and is likely to correlate with changes in both oxygen content and microstructure, has been observed frequently in annealed single crystals especially at higher temperatures (> 500 C). This is still an open question to some degree because the mechanism of phase decomposition is very complex and is dominated by the composition of the Bi-2212 phase, the condition of heat treatment, and the atmosphere. Hence, inducing oxygen loss at low temperature to avoid the evaporation of Bi atoms and other undetected structure changes which would occur at higher temperature annealing undoubtedly provides important information about the relationship between oxygen loss and phase decomposition, as well as the relationship between oxygen content and superconductivity. In this note, we report on the results of treatments of Bi 2 Sr 2 CaCu 2 O y single crystals in sulphur atmosphere at 160 C. (orig.)

  2. Critical cladding radius for hybrid cladding modes

    Science.gov (United States)

    Guyard, Romain; Leduc, Dominique; Lupi, Cyril; Lecieux, Yann

    2018-05-01

    In this article we explore some properties of the cladding modes guided by a step-index optical fiber. We show that the hybrid modes can be grouped by pairs and that it exists a critical cladding radius for which the modes of a pair share the same electromagnetic structure. We propose a robust method to determine the critical cladding radius and use it to perform a statistical study on the influence of the characteristics of the fiber on the critical cladding radius. Finally we show the importance of the critical cladding radius with respect to the coupling coefficient between the core mode and the cladding modes inside a long period grating.

  3. Charge Fluctuations in the NdO1-xFxBiS2 Superconductors

    Science.gov (United States)

    Athauda, Anushika; Mizuguchi, Yoshikazu; Nagao, Masanori; Neuefeind, Joerg; Louca, Despina

    2017-12-01

    The local atomic structure of superconducting NdO1-xFxBiS2 (x = 0.2 and 0.4) is investigated using neutron diffraction and the pair density function analysis technique. In the non-superconducting x = 0.2 composition, ferrodistortive displacements of the pyramidal sulfur ions break the tetragonal symmetry and a superlattice structure emerges with peaks appearing at h + k odd reflections superimposed on the even reflections of the P4/nmm symmetry. In the superconducting x = 0.4 composition, similar ferrodistortive displacements are observed but with different magnitudes coupled with in-plane Bi distortions which are indicative of charge fluctuations.

  4. Heat treatment control of Bi-2212 coils: I. Unravelling the complex dependence of the critical current density of Bi-2212 wires on heat treatment

    Science.gov (United States)

    Shen, Tengming; Li, Pei; Ye, Liyang

    2018-01-01

    A robust and reliable heat treatment is crucial for developing superconducting magnets from several superconductors especially Bi-2212. An improper heat treatment may significantly reduce the critical current density Jc of a Bi-2212 superconducting coil, even to zero, since the Jc of Bi-2212 wires is sensitive to parameters of its heat treatment (partial melt processing). To provide an essential database for heat treating Bi-2212 coils, the dependence of Jc on heat treatment is studied systematically in 11 industrial Bi-2212 wires, revealing several common traits shared between these wires and outlier behaviors. The dependence of the Jc of Bi-2212 on heat treatment is rather complex, with many processing parameters affecting Jc, including the peak processing temperature Tp, the time at the peak temperature tp, the time in the melt tmelt, the rate at which Bi-2212 melt is initially cooled CR1, the rate at which the solidification of Bi-2212 melt occurs CR2, and the temperature Tq at which the cooling rate switches from CR1 to CR2. The role of these parameters is analyzed and clarified, in the perspective of heat treating a coil. Practical advices on heat treatment design are given. The ability of a Bi-2212 coil to follow the prescribed recipe decreases with increasing coil sizes. The size of a coil that can be properly heat treated is determined.

  5. Effect of powders refinement on the tribological behavior of Ni-based composite coatings by laser cladding

    International Nuclear Information System (INIS)

    Wang Lingqian; Zhou Jiansong; Yu Youjun; Guo Chun; Chen Jianmin

    2012-01-01

    NiCr + Cr 3 C 2 + Ag + BaF 2 /CaF 2 composite coatings were produced on stainless steel (1Cr18Ni9Ti) substrates by laser cladding. Corresponding powders were prepared by high-energy ball milling technique. The friction and wear behavior at room temperature was investigated through sliding against the Si 3 N 4 ball. The morphologies of the wear debris, worn surfaces of both samples and the Si 3 N 4 ball were analyzed by scanning electron microscopy and three dimensional non-contact surface mapping. Results showed that milling time had a great effect on the size, morphology, uniformity of the powders as well as the microstructure and properties of laser cladding coatings. The wear mechanism of the coatings is dominated by abrasive wear, plastic deformation and slight adhesive wear. The consecutive evolution trend of friction coefficient, wear rate as well as microhardness of the serials of coatings produced with powders of different sizes was presented.

  6. Effect of powders refinement on the tribological behavior of Ni-based composite coatings by laser cladding

    Science.gov (United States)

    Wang, Lingqian; Zhou, Jiansong; Yu, Youjun; Guo, Chun; Chen, Jianmin

    2012-06-01

    NiCr + Cr3C2 + Ag + BaF2/CaF2 composite coatings were produced on stainless steel (1Cr18Ni9Ti) substrates by laser cladding. Corresponding powders were prepared by high-energy ball milling technique. The friction and wear behavior at room temperature was investigated through sliding against the Si3N4 ball. The morphologies of the wear debris, worn surfaces of both samples and the Si3N4 ball were analyzed by scanning electron microscopy and three dimensional non-contact surface mapping. Results showed that milling time had a great effect on the size, morphology, uniformity of the powders as well as the microstructure and properties of laser cladding coatings. The wear mechanism of the coatings is dominated by abrasive wear, plastic deformation and slight adhesive wear. The consecutive evolution trend of friction coefficient, wear rate as well as microhardness of the serials of coatings produced with powders of different sizes was presented.

  7. Thick films of Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O by solution processes

    International Nuclear Information System (INIS)

    Barboux, P.; Tarascon, J.M.; Shokoohi, F.; Wilkens, B.J.; Schwartz, C.L.

    1988-01-01

    We have prepared superconducting thick films of the Bi-based and the Tl-based cuprates via the decomposition of aqueous-glycerol solutions containing the salts of the elements. Preliminary results are presented in this work. The substrates are coated prior to heat treating, either by dipping or by spraying on various substrates heated at 200 0 C. Short firing times are required in order to minimize the loss of the constituent Bi (Tl). We find that nitrates of the constituents dissolved in a water-glycerol solution increase the reaction rate in comparison to pure nitrate aqueous solutions. They also help to produce the correct superconducting phase before some reaction with the substrate occurs or too much of the constituent Bi (Tl) is lost during heating to form the superconducting phase. However, the thallium phases cannot be obtained if the films are not fired in the presence of a high pressure of thallium in a sealed capsule. The films are composed of platelets, a few microns large, that are on average oriented parallel to the substrate with their c axis normal. The Bi films show an onset temperature at 85 K and zero resistance at 75 K while the Tl films show an onset temperature of 105 K and zero resistance at 95 K. The critical currents obtained to date are quite low (∼50 A/cm 2 at 77 K for the thallium phase)

  8. LASER CLADDING ON ALUMINIUM BASE ALLOYS

    OpenAIRE

    Pilloz , M.; Pelletier , J.; Vannes , A.; Bignonnet , A.

    1991-01-01

    laser cladding is often performed on iron or titanium base alloys. In the present work, this method is employed on aluminum alloys ; nickel or silicon are added by powder injection. Addition of silicon leads to sound surface layers, but with moderated properties, while the presence of nickel induces the formation of hard intermetallic compounds and then to an attractive hardening phenomena ; however a recovery treatment has to be carried out, in order to eliminate porosity in the near surface...

  9. Superconducting spin switch based on superconductor-ferromagnet nanostructures for spintronics

    International Nuclear Information System (INIS)

    Kehrle, Jan; Mueller, Claus; Obermeier, Guenter; Schreck, Matthias; Gsell, Stefan; Horn, Siegfried; Tidecks, Reinhard; Zdravkov, Vladimir; Morari, Roman; Sidorencko, Anatoli; Prepelitsa, Andrei; Antropov, Evgenii; Socrovisciiuc, Alexei; Nold, Eberhard; Tagirov, Lenar

    2011-01-01

    Very rapid developing area, spintronics, needs new devices, based on new physical principles. One of such devices - a superconducting spin-switch, consists of ferromagnetic and superconducting layers, and is based on a new phenomenon - reentrant superconductivity. The tuning of the superconducting and ferromagnetic layers thickness is investigated to optimize superconducting spin-switch effect for Nb/Cu 41 Ni 59 based nanoscale layered systems.

  10. Alternating-gradient canted cosine theta superconducting magnets for future compact proton gantries

    Directory of Open Access Journals (Sweden)

    Weishi Wan

    2015-10-01

    Full Text Available We present a design of superconducting magnets, optimized for application in a gantry for proton therapy. We have introduced a new magnet design concept, called an alternating-gradient canted cosine theta (AG-CCT concept, which is compatible with an achromatic layout. This layout allows a large momentum acceptance. The 15 cm radius of the bore aperture enables the application of pencil beam scanning in front of the SC-magnet. The optical and dynamic performance of a gantry based on these magnets has been analyzed using the fields derived (via Biot-Savart law from the actual windings of the AG-CCT combined with the full equations of motion. The results show that with appropriate higher order correction, a large 3D volume can be rapidly scanned with little beam shape distortion. A very big advantage is that all this can be done while keeping the AG-CCT fields fixed. This reduces the need for fast field ramping of the superconducting magnets between the successive beam energies used for the scanning in depth and it is important for medical application since this reduces the technical risk (e.g., a quench associated with fast field changes in superconducting magnets. For proton gantries the corresponding superconducting magnet system holds promise of dramatic reduction in weight. For heavier ion gantries there may furthermore be a significant reduction in size.

  11. Preparation of thin layers of BiSrCaCuO by method MOCVD

    International Nuclear Information System (INIS)

    Beran, P.; Stejskal, J.; Strejc, A.; Nevriva, M.; Sedmibudsky, D.; Leitner, J.

    1999-01-01

    Preparation of superconducting material on the basis mixed oxides of BiSrCaCuO by chemical vapour deposition (CVD) method is described. Surface morphology and concentration profiles of elements were analyzed by scanning electron microscope and microprobe. Phase of layers was analysed by X-ray diffraction (radiation of Cu kα ). Samples of thin layers were characterized by magnetic susceptibility in temperature interval 10 to 150 K. Obtained results confirm formation of superconducting phases Bi 2 Sr 2 Ca 1 Cu 2 O x and Bi 2 Sr 2 Xa 2 Cu 3 O x

  12. Resistive and magnetoresistive properties of BiSrCaCuO granulated films

    International Nuclear Information System (INIS)

    Mal'tsev, V.A.; Kulikovskij, A.V.; Kustikov, E.V.; Morozov, D.Yu.; Sokolov, Yu.S.

    1995-01-01

    Transport properties of superconducting bridges produced by laser etching of granulated films BiSrCaCuO have been studied. Analysis of nonlinear voltammetric characteristics of the bridges permits making the conclusion on the change in the character of conductivity (two-dimensional-three dimensional system), when approaching the critical point. Measurements of magnetoresistance of the samples suggest a possibility of application of high-temperature superconducting bridges in Bi-system as sensors of weak magnetic fields. 11 refs.; 4 figs

  13. Phase formations in the KOH-BaO2-KI(I2)-Bi2O3 system

    International Nuclear Information System (INIS)

    Klinkova, L.A.; Barkovskij, N.V.; Nikolajchik, V.I.

    2004-01-01

    Phase composition of electrochemical synthesis products in the system KOH-BaO 2 -KI(I 2 )-Bi 2 O 3 and its influence on superconducting properties of bismuth-containing oxides are studied by the methods of X-ray phase and elementary analyses, electron diffraction in transmission electron microscope and by measuring temperature dependence of magnetic susceptibility. It was been ascertained that in the presence of iodine introduced as KI or I 2 oxoiodides KBi 6 O 9 I and Bi 5 O 7 I are formed in the system above, giving rise to a change in the composition of synthesis products in KOH-BaO 2 -Bi 2 O 3 matrix system towards formation of superconducting oxides K n Ba m Bi m+n O y rich in bismuth, which are characterized by low values of superconducting transition point [ru

  14. Enhancing photocatalytic activity for hydrogen production and pollutant degradation by modifying tetragonal ZrO2 with monolayers slab surface of BiVO4, Ag3PO4, SrTiO3 and WO3: A first-principles study

    CSIR Research Space (South Africa)

    Opoku, F

    2017-10-01

    Full Text Available Semiconductor-based photocatalysis has received increasing attention in energy storage and environmental remediation process due to the abundant solar energy. For this purpose, heterostructures of ZrO2 coupled with BiVO4, Ag3PO4, SrTiO3 and WO3...

  15. Method of manufacturing a niobium-aluminum-germanium superconductive material

    Science.gov (United States)

    Wang, J.L.F.; Pickus, M.R.; Douglas, K.E.

    A method for manufacturing flexible Nb/sub 3/ (Al,Ge) multifilamentary superconductive material in which a sintered porous Nb compact is infiltrated with an Al-Ge alloy. It is deformed and heat treated in a series of steps at successively higher temperatures preferably below 1000/sup 0/C during the heat treatment, cladding material such as copper can be applied to facilitate a deformation step preceding the heat treatment and can remain in place through the heat treatment to serve as a temperature stabilizer for the superconductive material produced. These lower heat treatment temperatures favor formation of filaments with reduced grain size and with more grain boundaries which in turn increase the current-carrying capacity of the superconductive material.

  16. Variation of local critical current and its influence on overall current of bent multifilamentary Bi2223/Ag tape

    International Nuclear Information System (INIS)

    Ochiai, S.; Doko, D.; Rokkaku, H.; Fujimoto, M.; Okuda, H.; Hojo, M.; Tanaka, M.; Sugano, M.; Osamura, K.; Mimura, M.

    2006-01-01

    The correlation between the local and overall currents in a multifilamentary Bi2223/Ag/Ag alloy composite tape under bending strain was studied. The correlation of the measured distributed local critical current and n-value to overall critical current was described comprehensively with a voltage summation model that regards the overall sample to be composed of a series circuit. The analysis of the measured critical current and n-value revealed that the distribution of local critical current could be described with the Weibull distribution function and the n-value could be expressed as a function of critical current as a first approximation. By combining the Weibull distribution function of the local critical current, the empirical formula of the n-value as a function of critical current, voltage summation model and Monte Carlo method, the overall current and n-value could be predicted fairly well from those of local elements

  17. Electronic structure of Pr doped into superconducting Bi-Pb-Sr-Ca-Cu-O ceramics

    International Nuclear Information System (INIS)

    Egorov, A.I.; Karazhanova, G.I.; Smirnov, Yu.P.; Sovestnov, A.E.; Tyunis, A.V.; Shaburov, V.A.

    1992-07-01

    The shift of K α 1 and K β 1 X-ray lines of Pr in HTS-ceramic Bi 1.7 Pb 0.3 Sr 2-x Pr x Ca 2 Cu 3 O y (0,10≤x≤0,50, refer to PrF 3 ) are measured experimentally. The valence m(x), the charge q(x) and the 4f(x)-, 5d(x)-levels population of Pr are determined from experimental shifts. It is found that the Pr valence is near 3; the small valence increasing m≅3,04 at x=0,1 is observed. The small of Pr 5d-electron localization in ceramics in comparison with PrF 3 is revealed (∼0,1-0,2 5d-electron per Pr-atom). The probable cause of the superconductivity suppression in Y 1-x Pr xB a 2 Cu 3 O 7-δ system is discussed. 26 refs.; 6 figs.; 1 tab

  18. Properties and Microstructures of Sn-Bi-X Lead-Free Solders

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2016-01-01

    Full Text Available The Sn-Bi base lead-free solders are proposed as one of the most popular alloys due to the low melting temperature (eutectic point: 139°C and low cost. However, they are not widely used because of the lower wettability, fatigue resistance, and elongation compared to traditional Sn-Pb solders. So the alloying is considered as an effective way to improve the properties of Sn-Bi solders with the addition of elements (Al, Cu, Zn, Ga, Ag, In, Sb, and rare earth and nanoparticles. In this paper, the development of Sn-Bi lead-free solders bearing elements and nanoparticles was reviewed. The variation of wettability, melting characteristic, electromigration, mechanical properties, microstructures, intermetallic compounds reaction, and creep behaviors was analyzed systematically, which can provide a reference for investigation of Sn-Bi base solders.

  19. Transmission electron microscopy characterization of laser-clad iron-based alloy on Al-Si alloy

    International Nuclear Information System (INIS)

    Mei, Z.; Wang, W.Y.; Wang, A.H.

    2006-01-01

    Microstructure characterization is important for controlling the quality of laser cladding. In the present work, a detailed microstructure characterization by transmission electron microscopy was carried out on the iron-based alloy laser-clad on Al-Si alloy and an unambiguous identification of phases in the coating was accomplished. It was found that there is austenite, Cr 7 C 3 and Cr 23 C 6 in the clad region; α-Al, NiAl 3 , Fe 2 Al 5 and FeAl 2 in the interface region; and α-Al and silicon in the heat-affected region. A brief discussion was given for their existence based on both kinetic and thermodynamic principles

  20. High temperature superconducting material: Bismuth strontium calcium copper oxide. (Latest citations from the Aerospace database). Published Search

    International Nuclear Information System (INIS)

    1993-11-01

    The bibliography contains citations concerning the development, fabrication, and analysis of a high temperature superconducting material based on bismuth-strontium-calcium-copper-oxides (Bi-Sr-Ca-Cu-O). Topics include the physical properties, structural and compositional analysis, magnetic field and pressure effects, and noble metal dopings of Bi-Sr-Ca-Cu-O based systems. The highest transition temperature recorded to date for this material was 120 degrees Kelvin. Fabrication methods and properties of Bi-Sr-Ca-Cu-O films and ceramics are also considered. (Contains 250 citations and includes a subject term index and title list.)

  1. Magnetoresistance oscillations in topological insulator microwires contacted with normal and superconducting leads

    Science.gov (United States)

    Konopko, Leonid; Nikolaeva, Albina; Huber, Tito E.; Rogacki, Krzysztof

    2018-05-01

    Recent efforts to detect and manipulate Majorana fermions in solid state devices have employed topological insulator (TI) nanowires proximity coupled to superconducting (SC) leads. This combination holds some promises for the fundamental physics and applications. We studied the transverse magnetoresistance (MR) of polycrystal Bi2Te2Se and single-crystal Bi0.83Sb0.17 TI microwires contacted with superconducting In2Bi leads. Bi2Te2Se has a simple band structure with a single Dirac cone on the surface and a large non-trivial bulk gap of 300 meV. The semiconducting alloy Bi0.83Sb0.17 is a strong topological insulator due to the inversion symmetry of bulk crystalline Bi and Sb. To study the TI/SC interface, we prepared Bi2Te2Se and Bi0.83Sb0.17 glass-coated microwire samples using superconducting alloy In2Bi (Tc = 5.6 K) to provide a contact of one side of the microwires with copper leads and gallium to provide a contact of the other side of microwires with copper leads. The MR oscillations equidistant in a transverse magnetic field (up to 1 T) at the TI/SC interface were observed at various temperatures (4.2 K-1.5 K) in both the Bi2Te2Se and Bi0.83Sb0.17 samples. In the Bi2Te3 sample with a diameter of d = 17 μm, this oscillations exist with a period of ΔB = 18 mT; in the Bi0.83Sb0.17 sample with d = 1.7 μm MR oscillations are characterized by a period of ΔB = 46 mT. The observed oscillations cannot be referred to the Shubnikov de Haas oscillations because they are not periodic in an inverse magnetic field and their amplitude decreases with increasing magnetic field. Most probably, transverse MR oscillations arise owing to the appearance of highly conducting edge states on the planar boundary of SC/TI.

  2. Fabrication of Superconducting Traction Transformer for Railway Rolling Stock

    International Nuclear Information System (INIS)

    Kamijo, H; Hata, H; Fujimoto, H; Inoue, A; Nagashima, K; Ikeda, K; Yamada, H; Sanuki, Y; Tomioka, A; Uwamori, K; Yoshida, S; Iwakuma, M; Funaki, K

    2006-01-01

    We designed a floor type single-phase 4 MVA superconducting traction transformer for Shinkansen rolling stock. In this study, we fabricated a prototype superconducting traction transformer based on this design. This transformer of the core-type design has a primary winding, four secondary windings and a tertiary winding. The windings are wound by Bi2223 superconducting tapes and cooled by subcooled liquid nitrogen. The core is kept at room temperature. The cryostat is made of GFRP with two holes to pass core legs through. The outer dimensions are about 1.2m x 0.7m x 1.9m excluding the compressor. Its weight is 1.71t excluding that of refrigerator and compressor. The transformer was tested according to Japanese Industrial Standards (JIS)-E5007. We confirmed that the performance of transformer has been achieved almost exactly as planned. The rated capacity is equivalent to 3.5MVA in the superconducting state

  3. Electronic Structure, Irreversibility Line and Magnetoresistance of Cu_0_._3Bi_2Se_3 Superconductor

    International Nuclear Information System (INIS)

    Yi He-Mian; Chen Chao-Yu; Sun Xuan; Xie Zhuo-Jin; Feng Ya; Liang Ai-Ji; Peng Ying-Ying; He Shao-Long; Zhao Lin; Liu Guo-Dong; Dong Xiao-Li; Zhang Jun; Zhou Xing-Jiang; Chen Chuang-Tian; Xu Zu-Yan; Gu Gen-Da

    2015-01-01

    Cu_xBi_2Se_3 is a superconductor that is a potential candidate for topological superconductors. We report our laser-based angle-resolved photoemission measurement on the electronic structure of the Cu_xBi_2Se_3 superconductor, and a detailed magneto-resistance measurement in both normal and superconducting states. We find that the topological surface state of the pristine Bi_2Se_3 topological insulator remains robust after the Cu-intercalation, while the Dirac cone location moves downward due to electron doping. Detailed measurements on the magnetic field-dependence of the resistance in the superconducting state establishes an irreversibility line and gives a value of the upper critical field at zero temperature of ∼4000 Oe for the Cu_0_._3Bi_2Se_3 superconductor with a middle point T_c of 1.9K. The relation between the upper critical field H_c_2 and temperature T is different from the usual scaling relation found in cuprates and in other kinds of superconductors. Small positive magneto-resistance is observed in Cu_0_._3Bi_2Se_3 superconductors up to room temperature. These observations provide useful information for further study of this possible candidate for topological superconductors. (paper)

  4. Transmission electron microscopy investigation of Bi-2223/Ag tapes

    DEFF Research Database (Denmark)

    Andersen, L.G.; Bals, S.; Tendeloo, G. Van

    2001-01-01

    during the tape processing, (3) a study of the grain boundaries on an atomic scale, including intergrowth investigations. Tapes with different process parameters have been compared with respect to the microstructure. A fully processed tape has on the average 50% thicker Bi-2223 grains than a tape after......The microstructure of (Bi,Pb)(2)Sr2Ca2CuOx (Bi-2223) tapes has been investigated by means of transmission electron microscopy (TEM) and high-resolution TEM. The emphasis has been placed on: (1) an examination of the grain morphology and size, (2) grain and colony boundary angles, which are formed...

  5. Electrospinning synthesis of superconducting BSCCO nanowires

    International Nuclear Information System (INIS)

    Duarte, Edgar A.; Quintero, Pedro A.; Meisel, Mark W.; Nino, Juan C.

    2013-01-01

    Highlights: •Bi 2 Sr 2 CaCu 2 O 8+x nanowires 150 nm to 250 nm thick are synthesized using the electrospinning. •Bi 2 Sr 2 CaCu 2 O 8+x nanowires are obtained after a heat treatment at 850 °C. •Bi 2 Sr 2 CaCu 2 O 8+x nanowires show a T c = 78.7 K consistent with bulk superconductor behavior. -- Abstract: This paper presents the synthesis and characterization of Bi 2 Sr 2 CaCu 2 O 8+x superconducting nanowires. Bi 2 Sr 2 CaCu 2 O 8+x nanowires with a T c = 78.7 K are synthesized using the electrospinning process employing sol–gel precursors. A sol–gel methodology is used to obtain a homogeneous PVP solution containing Bi, Sr, Ca, and Cu acetates. Mats of randomly oriented nanowires and aligned nanowires are also collected. After a heat treatment at 850 °C in ambient atmosphere using heating rates of 100 and 400 °C/h, fully crystallized Bi 2 Sr 2 CaCu 2 O 8+x nanowires are obtained. The morphology, microstructure, and crystal structure of these nanowires are then examined to reveal a rectangular morphology having typical wire thickness in the range of 150–250 nm, and a wire width between 400 and 600 nm. DC magnetization studies are conducted to investigate the critical transition temperature (T c ) of Bi 2 Sr 2 CaCu 2 O 8+x nanowires and to compare their magnetic properties to those of bulk Bi 2 Sr 2 CaCu 2 O 8+x powder. The T c for the commercial powder is observed at 78.6 K, and that of the obtained nanowires at 78.7 K. These results point to the superconducting nature of Bi 2 Sr 2 CaCu 2 O 8+x nanowires, and the potential of the electrospinning process for the synthesis of this superconductor material

  6. Composite elements with superconducting ceramic materials and preparation process

    International Nuclear Information System (INIS)

    Drifford, M.; Lambard, J.

    1990-01-01

    Supraconducting ceramic powder is introduced in a ductile metal with an open porosity, then the tube is sealed at both ends and necked to form a composite element which is sintered and the ceramic becomes superconductive by gaseous diffusion. Then the composite element can be placed into a gasproof cladding [fr

  7. NMR studies of spin excitations in superconducting Bi2Sr2CaCu2O8+δ single crystals

    Science.gov (United States)

    Takigawa, M.; Mitzi, D. B.

    1994-08-01

    The oxygen NMR shift and the Cu nuclear spin-lattice relaxation rate (1/T1) were measured in Bi2.1Sr1.9Ca0.9Cu2.1O8+δ single crystals. While both the shift and 1/(T1T) decrease sharply near Tc, 1/(T1T) becomes nearly constant at low temperatures, indicating a gapless superconducting state with finite density of states at the Fermi level. From the oxygen shift data, the residual spin susceptibility at T=0 is estimated to be 10% of the value at room temperature. Our results are most consistent with a d-wave pairing model with strong (resonant) impurity scattering.

  8. Modeling the current distribution in HTS tapes with transport current and applied magnetic field

    NARCIS (Netherlands)

    Yazawa, T.; Yazawa, Takashi; Rabbers, J.J.; Chevtchenko, O.A.; ten Haken, Bernard; ten Kate, Herman H.J.; Maeda, Hideaki

    1999-01-01

    A numerical model is developed for the current distribution in a high temperature superconducting (HTS) tape, (Bi,Pb)2Sr2 Ca2Cu3Ox-Ag, subjected to a combination of a transport current and an applied magnetic field. This analysis is based on a two-dimensional formulation of Maxwell's equations in

  9. The spatial distribution of temperature and oxygen deficiency in spark-plasma sintered superconducting Bi-based materials

    International Nuclear Information System (INIS)

    Govea-Alcaide, E.; Pérez-Fernández, J.E.; Machado, I.F.; Jardim, R.F.

    2014-01-01

    Pre-reacted powders of (Bi–Pb) 2 Sr 2 Ca 2 Cu 3 O 10+δ (Bi-2223) were consolidated by using the spark plasma sintering (SPS) technique under vacuum and at different consolidate temperatures T D . X-ray diffraction patterns revealed that the dominant phase in all SPS samples is the Bi-2223 phase, but traces of the Bi 2 Sr 2 CaCu 2 O 10+x (Bi-2212) phase were identified. We have found that the transport properties of SPS samples depend on their oxygen content because the SPS process is performed under vacuum. Simulations by using the finite element method (FEM) were performed for determining the actual temperature in which powders are consolidated. From these results we have inferred that SPS samples are oxygen deficient and such a deficiency is more marked near the grain boundaries, suggesting the occurrence of grains with core–shell morphology. We also argued that the width of the shell depends on the consolidation temperature, a feature corroborated by the FEM simulations

  10. Superconductivity program for electric systems, Superconductivity Technology Center, Los Alamos National Laboratory, annual progress report for fiscal year 1997

    Energy Technology Data Exchange (ETDEWEB)

    Willis, J.O.; Newnam, B.E. [eds.; Peterson, D.E.

    1999-03-01

    Development of high-temperature superconductors (HTS) has undergone tremendous progress during the past year. Kilometer tape lengths and associated magnets based on BSCCO materials are now commercially available from several industrial partners. Superconducting properties in the exciting YBCO coated conductors continue to be improved over longer lengths. The Superconducting Partnership Initiative (SPI) projects to develop HTS fault current limiters and transmission cables have demonstrated that HTS prototype applications can be produced successfully with properties appropriate for commercial applications. Research and development activities at LANL related to the HTS program for Fiscal Year 1997 are collected in this report. LANL continues to support further development of Bi2223 and Bi2212 tapes in collaboration with American Superconductor Corporation (ASC) and Oxford Superconductivity Technology, Inc. (OSTI), respectively. The tape processing studies involving novel thermal treatments and microstructural characterization have assisted these companies in commercializing these materials. The research on second-generation YBCO-coated conductors produced by pulsed-laser deposition (PLD) over buffer template layers produced by ion beam-assisted deposition (IBAD) continues to lead the world. The applied physics studies of magnetic flux pinning by proton and heavy ion bombardment of BSCCO and YBCO tapes have provided many insights into improving the behavior of these materials in magnetic fields. Sections 4 to 7 of this report contain a list of 29 referred publications and 15 conference abstracts, a list of patent and license activities, and a comprehensive list of collaborative agreements in progress and completed.

  11. Enhanced thermoelectric properties of polycrystalline Bi2Te3 core fibers with preferentially oriented nanosheets

    Directory of Open Access Journals (Sweden)

    Min Sun

    2018-03-01

    Full Text Available Bi2Te3-based materials have been reported to be one of the best room-temperature thermoelectric materials, and it is a challenge to substantially improve their thermoelectric properties. Here novel Bi2Te3 core fibers with borosilicate glass cladding were fabricated utilizing a modified molten core drawing method. The Bi2Te3 core of the fiber was found to consist of hexagonal polycrystalline nanosheets, and polycrystalline nanosheets had a preferential orientation; in other words, the hexagonal Bi2Te3 lamellar cleavage more tended to be parallel to the symmetry axis of the fibers. Compared with a homemade 3-mm-diameter Bi2Te3 rod, the polycrystalline nanosheets’ preferential orientation in the 89-μm-diameter Bi2Te3 core increased its electrical conductivity, but deduced its Seebeck coefficient. The Bi2Te3 core exhibits an ultrahigh ZT of 0.73 at 300 K, which is 232% higher than that of the Bi2Te3 rod. The demonstration of fibers with oriented nano-polycrystalline core and the integration with an efficient fabrication technique will pave the way for the fabrication of high-performance thermoelectric fibers.

  12. Influence of micro-additions of bismuth on structures, mechanical and electrical transport properties of rapidly solidified Sn-3.5% Ag Alloy from melt

    International Nuclear Information System (INIS)

    El Bahay, M.M.; Mady, H.A.

    2005-01-01

    The present study was undertaken to investigate the influence of the Bi addition in the Sn-3.5 Ag rapidly solidified binary system for use as a Pb-free solder. The resulting properties of the binary system were extended to the Sn based ternary systems Sn 9 6.5-X Ag 3 .5 Bi x (0≤ X ≤ 2.5) solder. The structure and electrical resistivity of rapidly solidified (melt spun) alloys have been investigated. With the addition of up to 2.5 mass % Bi, the melting temperature decreases from 221.1 to 214.8 degree C. Wetting contact angle of the six alloys on Cu Zn 3 0 substrate are carried out at 573 K. Microhardness evaluations were also performed on the Sn-Ag-Bi alloys. The measured values and other researcher's results were compared with the calculated data

  13. The Au-Ag-Sb-Bi-Te mineralization from the deposit Bytíz (mine 19), the Příbram uranium-polymetallic ore discrit, Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Litochleb, J.; Sejkora, J.; Šrein, Vladimír

    2006-01-01

    Roč. 28, Spec. pap. (2006), s. 133-135 ISSN 1896-2203. [Central European Mineralogical Conference /1./. Vyšná Boca, 11.09.2006-15.09.2006] Institutional research plan: CEZ:AV0Z30460519 Keywords : Au-Ag-Sb-Bi-Te * mineralization * uranium-polymetallic ore Subject RIV: DB - Geology ; Mineralogy

  14. Effect of powders refinement on the tribological behavior of Ni-based composite coatings by laser cladding

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lingqian [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Zhou Jiansong, E-mail: jszhou@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Yu Youjun; Guo Chun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Chen Jianmin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2012-06-15

    NiCr + Cr{sub 3}C{sub 2} + Ag + BaF{sub 2}/CaF{sub 2} composite coatings were produced on stainless steel (1Cr18Ni9Ti) substrates by laser cladding. Corresponding powders were prepared by high-energy ball milling technique. The friction and wear behavior at room temperature was investigated through sliding against the Si{sub 3}N{sub 4} ball. The morphologies of the wear debris, worn surfaces of both samples and the Si{sub 3}N{sub 4} ball were analyzed by scanning electron microscopy and three dimensional non-contact surface mapping. Results showed that milling time had a great effect on the size, morphology, uniformity of the powders as well as the microstructure and properties of laser cladding coatings. The wear mechanism of the coatings is dominated by abrasive wear, plastic deformation and slight adhesive wear. The consecutive evolution trend of friction coefficient, wear rate as well as microhardness of the serials of coatings produced with powders of different sizes was presented.

  15. Dirac state in a centrosymmetric superconductor α -PdBi2

    Science.gov (United States)

    Dimitri, Klauss; Hosen, M. Mofazzel; Dhakal, Gyanendra; Choi, Hongchul; Kabir, Firoza; Sims, Christopher; Kaczorowski, Dariusz; Durakiewicz, Tomasz; Zhu, Jian-Xin; Neupane, Madhab

    2018-04-01

    Topological superconductor (TSC) hosting Majorana fermions has been established as a milestone that may shift our scientific trajectory from research to applications in topological quantum computing. Recently, superconducting Pd-Bi binaries have attracted great attention as a possible medium for the TSC phase as a result of their large spin-orbit coupling strength. Here, we report a systematic high-resolution angle-resolved photoemission spectroscopy (ARPES) study on the normal state electronic structure of superconducting α -PdBi2 (Tc=1.7 K). Our results show the presence of Dirac states at higher-binding energy with the location of the Dirac point at 1.26 eV below the chemical potential at the zone center. Furthermore, the ARPES data indicate multiple band crossings at the chemical potential, consistent with the metallic behavior of α -PdBi2 . Our detailed experimental studies are complemented by first-principles calculations, which reveal the presence of surface Rashba states residing in the vicinity of the chemical potential. The obtained results provide an opportunity to investigate the relationship between superconductivity, topology, and the Majorana fermion, as well as explore pathways to possible future platforms for topological quantum computing.

  16. Analysis of corrosion behavior of KOFA cladding

    International Nuclear Information System (INIS)

    Lee, Chan Bock; Kim, Ki Hang; Seo, Keum Seok; Chung, Jin Gon

    1994-01-01

    The corrosion behavior of KOFA cladding was analyzed using the oxide measurement data of KOFA fuel irradiated up to the fuel rod burnup of 35,000 MWD/MTU for two cycles in Kori-2. Even though KOFA cladding is a standard Zircaloy-4 manufactured by Westinghouse according to the Siemens/KWU's HCW (Highly Cold Worked) standard Zircaloy-4 specification, it was expected that in-pile corrosion behavior of KOFA cladding would not be equivalent to that of Siemens/KWU's cladding due to the differences in such manufacturing processes as cold work and heat treatment. The analysis of measured KOFA cladding oxidation showed that oxidation of KOFA cladding is at least 19 % lower than the design analysis based upon Siemens/KWU's HCW standard Zircaloy-4 cladding. Lower corrosion of KOFA cladding seems to result from the differences in the manufacturing processes and chemical composition although the burnup and oxide layer thickness of the measured fuel rods is relatively low and the amount of the oxidation data base is small

  17. Growth of Ba1-zSrzBiO3-y single crystals and the prospects for its application for liquid phase epitaxy of Ba1-xKxBiO3-δ superconductor

    International Nuclear Information System (INIS)

    Soldatov, A.G.; Barilo, S.N.; Shiryaev, S.V.; Finskaya, V.M.

    2002-01-01

    In order to get a substrate for liquid phase epitaxy of the Ba 1-x K x BiO 3-δ (BKBO) superconducting films a possibility to grow single crystals of the Ba 1-z Sr z BiO 3-y (BSBO) solid solution series was investigated. The BSBO crystals with z = 0; 0.2; 0.29; 0.45; 0.49; 0.50; 0.54; 0.58 were obtained by crystallization from melt. The temperature versus composition phase diagram of the BaO · 1/2Bi 2 O 3 -SrO · 1/2Bi 2 O 3 system was constructed. A comparative analysis of the effect of cation composition and oxygen nonstoichiometry on the BSBO lattice parameters was carried out. The growth features of superconducting BKBO films onto BSBO substrates are discussed [ru

  18. Performance of bismuth tape current leads under vibration; Bi tepu sei denryu rido no shindo tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, E.; Kurihara, M. [Railway Techniical Research Institute, Tokyo (Japan)

    2000-02-25

    The superconducting magnets on Maglev vehicles when running vibrate mechanically due to electromagnetic disturbance from the ground coils. Therefore, the current leads fixed on the superconducting coil, which is vibration at about 98 m/s{sup 2} (=10g), are also required to endure the vibration. We executed dynamic vibration tests for two types of current leads (straight and arc types) which had a multi-stacked configuration of Ag-sheathed Bi2223 tapes impregnated with epoxy resin in a concaved reinforcing gutter. We evaluated the straight-type lead for an operating current of 700 A after every vibration test in liquid nitrogen for one hour under the dynamic strain deformation of 50-100 {mu} on the surface of the reinforcing material covering the current lead. We could not detect degradation of the current lead by vibration through the total cycles of 3.9 x 10{sup 6} after continuous vibration tests. We also executed vibration tests for arc-type current leads which were combined with an actual energized superconducting coil for a Maglev. Large accelerations of these current leads occurred at frequencies of 308 and 375 Hz. In spite of the maximum acceleration of 600-700 m/s{sup 2} generated by actuating the excessive force on a superconducting coil for two seconds, which occurred on these current leads carrying 500 A, the superconductivity of the current leads did not shift to normal conductivity. There was no damage to either type of current lead during these vibration tests. So we confirmed the good prospect for the application of these current leads to actual Maglev superconducting magnets. (author)

  19. Geometry dependence of magnetic and transport AC losses in Bi-2223/Ag tapes with different aspect ratios

    Energy Technology Data Exchange (ETDEWEB)

    Fang, J [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Luo, X M [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Chen, D X [ICREA and Grup Electromagnetisme, Departament de Fisica, Universitat Autonoma Barcelona, 08193 Bellaterra (Spain); Alamgir, A K M [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Collings, E W [MSE, Ohio State University, Columbus, OH 43210 (United States); Lee, E [MSE, Ohio State University, Columbus, OH 43210 (United States); Sumption, M D [MSE, Ohio State University, Columbus, OH 43210 (United States); Fang, J G [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Yi, H P [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Song, X H [Innova Superconductor Technology Co., Ltd, 7 Rongchang Dongjie, Longsheng Industrial Park, Beijing Economic and Technological Development Area, 100176 (China); Guo, S Q [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Liu, M L [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Xin, Y [Innopower Superconductor Cable Co., Ltd, 7 Rongchang Dongjie, Longsheng Industrial Park, Beijing Economic and Technological Development Area, 100176 (China); Han, Z [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China)

    2004-10-01

    On five Bi-2223/Ag tapes with different aspect ratios from 5 to 26, AC losses have been measured at 77 K while a parallel AC magnetic field or a perpendicular AC magnetic field or a longitudinal AC transport current is applied. It has been found that at any frequency the perpendicular magnetic losses per cycle increase, but the parallel magnetic losses per cycle and the transport losses per cycle decrease as the aspect ratio increases. These experimental results are in accord with theoretical results. Meanwhile, we investigated the geometry dependence of the decay time constant of coupling current and that of full penetration field.

  20. Geometry dependence of magnetic and transport AC losses in Bi-2223/Ag tapes with different aspect ratios

    International Nuclear Information System (INIS)

    Fang, J; Luo, X M; Chen, D X; Alamgir, A K M; Collings, E W; Lee, E; Sumption, M D; Fang, J G; Yi, H P; Song, X H; Guo, S Q; Liu, M L; Xin, Y; Han, Z

    2004-01-01

    On five Bi-2223/Ag tapes with different aspect ratios from 5 to 26, AC losses have been measured at 77 K while a parallel AC magnetic field or a perpendicular AC magnetic field or a longitudinal AC transport current is applied. It has been found that at any frequency the perpendicular magnetic losses per cycle increase, but the parallel magnetic losses per cycle and the transport losses per cycle decrease as the aspect ratio increases. These experimental results are in accord with theoretical results. Meanwhile, we investigated the geometry dependence of the decay time constant of coupling current and that of full penetration field

  1. Attempting to realize n-type BiCuSeO

    Science.gov (United States)

    Zhang, Xiaoxuan; Feng, Dan; He, Jiaqing; Zhao, Li-Dong

    2018-02-01

    As an intrinsic p-type semiconductor, BiCuSeO has been widely researched in the thermoelectric community, however, n-type BiCuSeO has not been reported so far. In this work, we successfully realized n-type BiCuSeO through carrying out several successive efforts. Seebeck coefficient of BiCuSeO was increased through introducing extra Bi/Cu to fill the Bi/Cu vacancies that may produce holes, and the maximum Seebeck coefficient was increase from +447 μVK-1 for undoped BiCuSeO to +638 μVK-1 for Bi1.04Cu1.05SeO. The Seebeck coefficient of Bi1.04Cu1.05SeO was changed from p-type to n-type through electron doping through introducing Br/I in Se sites, the maximum negative Seebeck coefficient can reach ∼ -465 μVK-1 and -543 μVK-1 for Bi1.04Cu1.05Se1-xIxO and Bi1.04Cu1.05Se1-xBrxO, respectively. Then, after compositing Bi1.04Cu1.05Se0.99Br0.01O with Ag, n-type BiCuSeO can be absolutely obtained in the whole temperature range of 300-873 K, the maximum ZT 0.05 was achieved at 475 K in the Bi1.04Cu1.05Se0.99Br0.01O+15% Ag. Our report indicates that it is possible to realize n-type conducting behaviors in BiCuSeO system.

  2. Alternative designs of high-temperature superconducting synchronous generators

    OpenAIRE

    Goddard, K. F.; Lukasik, B.; Sykulski, J. K.

    2010-01-01

    This paper discusses the different possible designs of both cored and coreless superconducting synchronous generators using high-temperature superconducting (HTS) tapes, with particular reference to demonstrators built at the University of Southampton using BiSCCO conductors. An overview of the electromagnetic, thermal, and mechanical issues is provided, the advantages and drawbacks of particular designs are highlighted, the need for compromises is explained, and practical solutions are offer...

  3. Electrical transport effects due to oxygen content modifications in a Bi2Sr2CaCu2O8+δ superconducting whisker

    International Nuclear Information System (INIS)

    Cagliero, Stefano; Agostino, Angelo; Bonometti, Elisabetta; Truccato, Marco

    2007-01-01

    We report a set of resistivity measurements along the a-axis of a Bi 2 Sr 2 CaCu 2 O 8+δ microscopic superconducting whisker. The effect of the storage environment on sample ageing has been studied, considering both an air atmosphere at 273 K and a helium atmosphere at about 300 K for an overall storage time of about 100 days. It is clearly shown that the material underwent a remarkable resistivity increase of 26% at 260 K accompanied by a decrease in the critical temperature of 0.6 K during the whole ageing period. The helium atmosphere increased the average process rate by about two orders of magnitude. The present results are in agreement with previous findings on room temperature structural modifications in Bi 2 Sr 2 CaCu 2 O 8+δ whiskers and can be ascribed to oxygen depletion phenomena from the material

  4. Correlation between modulation structure and electronic inhomogeneity on Pb-doped Bi-2212 single crystals

    International Nuclear Information System (INIS)

    Sugimoto, A.; Kashiwaya, S.; Eisaki, H.; Yamaguchi, H.; Oka, K.; Kashiwaya, H.; Tsuchiura, H.; Tanaka, Y.

    2005-01-01

    The correlation between nanometer-size electronic states and surface structure is investigated by scanning tunneling microscopy/spectroscopy (STM/S) on Pb-doped Bi 2-x Pb x Sr 2 CaCu2O 8+y (Pb-Bi-2212) single crystals. The advantage of the Pb-Bi-2212 samples is that the modulation structure can be totally or locally suppressed depending on the Pb contents and annealing conditions. The superconducting gap (Δ) distribution on modulated Pb-Bi-2212 samples showed the lack of correlation with modulation structure except a slight reduction of superconducting island size for the b-axis direction. On the other hand, the optimal doped Pb-Bi-2212 (x = 0.6) samples obtained by reduced-annealing showed totally non-modulated structure in topography, however, the spatial distribution of Δ still showed inhomogeneity of which features were quite similar to those of modulated samples. These results suggest that the modulation structure is not the dominant origin of inhomogeneity although it modifies the streaky Δ structure sub-dominantly. From the gap structure variation around the border of narrow gap and broad gap regions, a trend of the coexistence of two separated phases i.e., superconducting phase and pseudogap like phase, is detected

  5. Effects of Out-of-Plane Disorder on the Nodal Quasiparticle and Superconducting Gap in Single-Layer Bi_2Sr_1.6Ln_0.4CuO_6 delta (Ln = La, Nd, Gd)

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, M.

    2011-01-04

    How out-of-plane disorder affects the electronic structure has been investigated for the single-layer cuprates Bi{sub 2}Sr{sub 1.6}Ln{sub 0.4}CuO{sub 6+{delta}} (Ln = La, Nd, Gd) by angle-resolved photoemission spectroscopy. We have observed that, with increasing disorder, while the Fermi surface shape and band dispersions are not affected, the quasi-particle width increases, the anti-nodal gap is enhanced and the superconducting gap in the nodal region is depressed. The results indicate that the superconductivity is significantly depressed by out-of-plane disorder through the enhancement of the anti-nodal gap and the depression of the superconducting gap in the nodal region.

  6. Zinc Cadmium Selenide Cladded Quantum Dot Based Electroluminescent and Nonvolatile Memory Devices

    Science.gov (United States)

    Al-Amody, Fuad H.

    This dissertation presents electroluminescent (EL) and nonvolatile memory devices fabricated using pseudomorphic ZnCdSe-based cladded quantum dots (QDs). These dots were grown using our own in-school built novel reactor. The EL device was fabricated on a substrate of ITO (indium tin oxide) coated glass with the quantum dots sandwiched between anode and cathode contacts with a small barrier layer on top of the QDs. The importance of these cladded dots is to increase the quantum yield of device. This device is unique as they utilize quantum dots that are pseudomorphic (nearly lattice-matched core and the shell of the dot). In the case of floating quantum dot gate nonvolatile memory, cladded ZnCdSe quantum dots are deposited on single crystalline gate insulator (ZnMgS/ZnMgSe), which is grown using metal-organic chemical vapor deposition (MOCVD). The control gate dielectric layer of the nonvolatile memory is Si3N4 or SiO2 and is grown using plasma enhanced chemical vapor deposition (PECVD). The cladded dots are grown using an improved methodology of photo-assisted microwave plasma metal-organic chemical vapor deposition (PMP-MOCVD) enhanced reactor. The cladding composition of the core and shell of the dots was engineered by the help of ultraviolet light which changed the incorporation of zinc (and hence composition of ZnCdSe). This makes ZnxCd1--xSe-ZnyCd1--y Se QDs to have a low composition of zinc in the core than the cladding (x

  7. Coulomb-Gas scaling law for a superconducting Bi(2+y)Sr(2-x-y)La(x)CuO(6+delta) thin films in magnetic fields

    Science.gov (United States)

    Zhang; Deltour; Zhao

    2000-10-16

    The electrical transport properties of epitaxial superconducting Bi(2+y)Sr(2-x-y)La(x)CuO(6+delta) thin films have been studied in magnetic fields. Using a modified Coulomb-gas scaling law, we can fit all the magnetic field dependent low resistance data with a universal scaling curve, which allows us to determine a relation between the activation energy of the thermally activated flux flow resistance and the characteristic temperature scaling parameters.

  8. Destruction of superconductivity in the Bi2Sr2Ca1-xGdxCu2-yLiyO8+d system

    International Nuclear Information System (INIS)

    Jayaram, B.; Lanchester, P.C.; Weller, M.T.

    1991-01-01

    We have measured the T c , resistivity, and magnetoresistivity of a series of Bi 2 Sr 2 Ca 1-x Gd x Cu 2-y Li y O 8+d samples, with x=0 and 0.4 and 0≤y≤0.6. We find that the suppression of T c , the logarithmic variation of the resistivity above the superconducting transition, and the field-independent nature of the temperature variation of magnetoresistivity illustrate the enhancement of the Coulomb interaction with increasing normal-state resistivity (ρ n ). We also find a gradual crossover from a logarithmic to an exponential dependence with increasing ρ n

  9. Single phase in Ba-dopped Bi-based high-T/sub c/ compound

    International Nuclear Information System (INIS)

    Rehman, M.A.; Maqsood, A.

    2001-01-01

    Ba-doped, Bi-based, high-Tc superconductor was prepared by a solid state reaction method. The nominal composition used was Bi/sub 1.6/Pb/sub 0.4/Sr/sub 1.6/Ba/sub 0.4/Ca/sub 2/Cu/sub 3/O/sub y/. The samples were characterized by dc electrical resistivity and ac magnetic susceptibility both as a function of temperature (T). Room temperature x-ray diffraction studies were also done. Binder chemicals do affect the properties of the samples and it was observed that samples prepared with polyvinyl alcohol binder chemical showed good reproducible results. All the Above measurements showed that in the compound Bi/sub 1.6/Pb/sub 0.4/Ca/sub 2/Cu/sub 3/O/sub y/ there exists a single high-T/sub c/ phase with T/sub c.0≅/109 plus minus 1K. It behaves like an ideal metal before the superconducting transition in ρ-T plot and the Mathiessen's rule could be fitted. The ac susceptibility measurements support the observations of electrical resistivity. The lattice constants of the material are a=5.416(7) degree A, b=5.455(6) degree A, and c=37.26(8) degree A. The c-axis lattice constant slightly increased with Ba-doping. This fact indicated that Ba was probably incorporated into the Sr site of the crystal structure. Large sized samples (Diameter '28mm and length' 11mm) are under investigation for thermal transport properties by transient Plane Source (TPS) method. (author)

  10. Moessbauer and transport studies of amorphous and icosahedral Zr-Ni-Cu-Ag-Al alloys

    International Nuclear Information System (INIS)

    Stadnik, Z.M.; Rapp, O.; Srinivas, V.; Saida, J.; Inoue, A.

    2002-01-01

    The alloy Zr 65 Al 7.5 Ni 10 Cu 7.3 Fe 0.2 Ag 10 in the amorphous and icosahedral states, and the bulk amorphous alloy Zr 65 Al 7.5 Ni 10 Cu 7.5 Ag 10 , have been studied with 57 Fe Moessbauer spectroscopy, electrical resistance and magnetoresistance techniques. The average quadrupole splitting in both alloys decreases with temperature as T 3/2 . The average quadrupole splitting in the icosahedral alloy is the largest ever reported for a metallic system. The lattice vibrations of the Fe atoms in the amorphous and icosahedral alloys are well described by a simple Debye model, with the characteristic Moessbauer temperatures of 379(29) and 439(28) K, respectively. Amorphous alloys Zr 65 Al 7. )5Ni 10 Cu 7.5 Ag 10 and Zr 65 Al 7.5 Ni 10 Cu 7.3 Fe 0.2 Ag 10 have been found to be superconducting with the transition temperature, T c , of about 1.7 K. The magnitude of Tc and the critical field slope at Tc are in agreement with previous work on Zr-based amorphous superconductors, while the low-temperature normal state resistivity is larger than typical results for binary and ternary Zr-based alloys. The resistivity of icosahedral Zr 65 Al 7.5 Ni 10 Cu 7.3 Fe 0.2 Ag 10 is larger than that for the amorphous ribbon of the same composition, as inferred both from direct measurements on the ribbons and from the observed magnetoresistance. However the icosahedral sample is non-superconducting in the measurement range down to 1.5 K. The results for the resistivity and the superconducting T c both suggest a stronger electronic disorder in the icosahedral phase than in the amorphous phase. (author)

  11. Processing of Bi-2212 and Nb$_3$Sn studied in situ by high energy synchrotron diffraction and micro-tomography

    CERN Document Server

    Kadar, Julian

    Next generation superconducting wires have been studied to obtain more information on the evolution of phase growth, crystallite size and strain state during wire processing. The high energy scattering beam line ID15 at the European Synchrotron Radiation Facility provides a very high flux of high energy photons for very fast in situ X-ray diffraction and micro-tomography studies of Bi-2212/Ag and Nb$_3$S/Cu wire samples. The typical wire processing conditions could be imitated in the X-ray transparent furnace at ID15 for diffraction and tomography studies. Efficient data analysis is mandatory in order to handle the very fast data acquisition rate. For this purpose an Excel-VBA based program was developed that allows a semi-automated fitting and tracking of peaks with pre-set constraints. With this method, more than one thousand diffraction patterns have been analysed to extract d-spacing, peak intensity and peak width values. X ray absorption micro tomograms were recorded simultaneously with the X-ray diffrac...

  12. Design and Test of a Thermal Triggered Persistent Current System using High Temperature Superconducting Tapes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Dong Keun [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Kang, Hyoungku [Electro-Mechanical Research Institute, Hyundai Heavy Industries, Yongin (Korea, Republic of); Ahn, Min Cheol [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Yang, Seong Eun [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Yoon, Yong Soo [Department of Electrical Engineering, Ansan College of Technology, 671 Choji-Dong, Danwon-Gu, Ansan, 425-792 (Korea, Republic of); Lee, Sang Jin [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Ko, Tae Kuk [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of)

    2006-06-01

    A superconducting magnet which is operated in persistent current mode in SMES, NMR, MRI and MAGLEV has many advantages such as high uniformity of magnetic field and reduced thermal loss. A high temperature superconducting (HTS) persistent current switch (PCS) system was designed and tested in this research. The HTS PCS was optimally designed using two different HTS tapes, second generation coated conductor (CC) HTS tape and Bi-2223 HTS tape by the finite element method (FEM) in thermal quench characteristic view. The CC tape is more prospective applicable wire in these days for its high n value and critical current independency from external magnetic field than Bi-2223 tape. Also a prototype PCS system using Bi-2223 tape was manufactured and tested. The PCS system consists of a PCS part, a heater which induces the PCS to quench, and a superconducting magnet. The test was performed in various conditions of transport current. An initial current decay appeared when the superconducting magnet was energized in a PCS system was analyzed. This paper would be foundation of HTS PCS researches.

  13. US superconducting magnet data base assessment for INTOR

    International Nuclear Information System (INIS)

    Schultz, J.H.; Montgomery, D.B.

    1984-01-01

    Because of its size, performance requirements and exposure to neutron and gamma irradiation, the superconducting magnet system for INTOR would represent a significant advance in superconducting magnet technology. US programs such as LCP, MFTF-B and others provide a significant data base for the INTOR application. The assessment of the adequacy of the US data base for the INTOR magnets is largely generic, and applies to the superconducting magnet systems for other magnetic confinement fusion reactors. Assessments of the data base generated by other national magnet technology programs are being prepared by the other INTOR participants

  14. Interaction between thorium and potential clad materials

    International Nuclear Information System (INIS)

    Kale, G.B.; Gawde, P.S.; Sengupta, Pranesh

    2005-01-01

    Thorium based fuels are being used for nuclear reactors. The structural stability of fuel-clad assemblies in reactor systems depend upon the nature of interdiffusion reaction between fuel-cladding materials. Interdiffusion reaction thorium and various cladding materials is presented in this paper. (author)

  15. Preparation of (Bi,Pb)2Sr2Ca2Cu3Ox precursor powders by a modified polyethylene glycol based sol-gel process

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Andersen, N.H.

    2002-01-01

    A modified sol-gel process based on polyethylene glycol has been developed for preparing (Bi,Pb)(2)Sr2Ca2Cu3Ox precursor powders in view of Ag-sheeted tape manufacture. A careful control of the pH and concentration temperature yields an amorphous gel, which can be converted to a fine and extremely...

  16. Magnetic properties of bi-, tri- and multicrystals of 3D topological insulator Bi{sub 1−x}–Sb{sub x}(0.06⩽x⩽0.2)

    Energy Technology Data Exchange (ETDEWEB)

    Muntyanu, F.M. [Institute of Electronic Engineering and Industrial Technologies, Academy of Sciences of Moldova, Chisinau 2028 (Moldova, Republic of); International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53421 (Poland); Gilewski, A., E-mail: andrzej.gilewski@ml.pan.wroc.pl [International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53421 (Poland); Nenkov, K. [International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53421 (Poland); Leibniz-Institut fur Festkorper und Werkstofforschung, Dresden 01171 (Germany); Rogacki, K. [International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53421 (Poland); Institute of Low Temperatures and Structural Research, Polish Academy of Sciences, Wroclaw 50950 (Poland); Zaleski, A.J. [Institute of Low Temperatures and Structural Research, Polish Academy of Sciences, Wroclaw 50950 (Poland); Fuks, G. [International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53421 (Poland); Leibniz-Institut fur Festkorper und Werkstofforschung, Dresden 01171 (Germany); Chistol, V. [Technical University of Moldova, Chisinau 2004 (Moldova, Republic of)

    2014-03-01

    The magnetic properties of bi-, tri- and multicrystals of 3D topological insulator Bi{sub 1−x}Sb{sub x}(0.06superconducting phases associated with adjacent and central layers of the crystallite interfaces of the bicrystals are identified. It has been found that due to the different stress structure the transition temperature T{sub c} for one superconducting phase changes considerably, from 8.3 to 36 K, while for another superconducting phase, T{sub c} remains within the range 3.7–4.6 K. In tricrystals and bicrystals with high contents of structural disorder and topological defects, ferromagnetic hysteresis loops and magnetic field expulsion have been observed simultaneously.

  17. Microstructures and superconducting properties of Y-Ba-Cu and Bi-Sr-Ca-Cu oxide wires and coils prepared by the explosive compaction technique

    International Nuclear Information System (INIS)

    Hagino, S.; Suzuki, M.; Takeshita, T.; Takashima, K.; Tonda, H.

    1989-01-01

    It has been shown that explosive compaction technique can be used to densify metal, and ceramics powders and their mixtures. The authors discuss how they applied this technique to produce silver sheathed superconducting oxide wires and coils (Y-B-Cu-O and Bi-Sr-Ca-Cu-O). The wires and coils to be compacted were placed into metal tube and the tube was filled with SiC powder as a pressure propagating medium and the tube was compacted by a cylindrically axisymmetric method. The wires and coils compacted were then heat-treated in order to improve grain boundary connections of superconducting oxide crystalline grains. The oxide cores heat-treated were seen to be very dense, and a part of a Y-Ba-Cu oxide coil which was heat-treated optimally was found to have a critical current density higher than 13,000A/cm 2 at 77K

  18. Critical current anisotropy in Ag/(Pb,Bi){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} multifilamentary tapes: influence of self-magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Majoros, M [IRC in Superconductivity, University of Cambridge, Cambridge (United Kingdom); Institute of Electrical Engineering, Slovak Academy of Sciences, Bratislava (Slovakia); Glowacki, B A [IRC in Superconductivity, University of Cambridge, Cambridge (United Kingdom); Department of Materials Science and Metallurgy, University of Cambridge, Cambridge (United Kingdom); Campbell, A M [IRC in Superconductivity, University of Cambridge, Cambridge (United Kingdom)

    2001-06-01

    Two factors affect critical current anisotropy in multifilamentary Ag/(Pb,Bi){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} tapes - the intrinsic material anisotropy and the geometry. Experimental results on the magnetic field dependence and anisotropy of the critical current in a multifilamentary Ag/(Pb,Bi){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} tape after correction for self-magnetic field effects were found to fit the anisotropic Kim relation. Based on this relation a finite-element-method numerical code for solving the nonlinear Poisson equation for vector magnetic potential was adopted. It allowed the experimental data to be reproduced by back calculation and made possible the study of the interplay of self and external magnetic fields in different cases with well defined physical parameters of the material. The model was used to analyse the distribution of the critical current in individual filaments as well as to evaluate the influence of their geometrical arrangements on the critical current of the tape. The self-field critical current of an individual filament 'extracted' from the tape was compared with the critical current of the overall tape. The effect of the self-magnetic field on critical current distribution obtained by the cutting method was determined. The critical currents of the tapes with different cross sections were calculated and compared with experiments and the influence of the self-field was analysed. The anisotropic properties of a low anisotropy architecture of a multifilamentary Ag/(Pb,Bi){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} conductor were studied. The dependence of critical currents (normalized to self-field critical currents) on external magnetic field corrected for the self-field was found to follow nearly the same curves as those for tapes with different critical current densities (in the range 20-70 kA cm{sup -2} in a self-field), which makes the numerical model applicable to different tapes. (author)

  19. Analyses on Silicide Coating for LOCA Resistant Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Sweidan, Faris B.; Lee, You Ho; Ryu, Ho Jin [KAIST, Daejeon (Korea, Republic of)

    2015-10-15

    A particular focus of accident-tolerant fuel has been cladding due to the rapid high-temperature oxidation of zirconium-based cladding with the evolution of H2 when steam is a reactant. Some key features of the coated cladding include high-temperature resistance to oxidation, lower processing temperatures, and a high melting point of the coating. Zirconium alloys exhibit a reasonably high melting temperature, so a coating for the cladding is appealing if the coating increases the high-temperature resistance to oxidation. In this case, the cladding is protected from complete oxidation. The cladding coating involves the application of zirconium silicide onto Zr-based cladding. Zirconium silicide coating is expected to produce a glassy layer that becomes more protective at elevated temperature. For this reason, silicide coatings on cladding offer the potential for improved reliability at normal operating temperatures and at the higher transient temperatures encountered during accidents. Although ceramic coatings are brittle and may have weak points to be used as coating materials, several ceramic coatings were successful and showed adherent behavior and high resistance to oxidation. In this study, the oxidation behavior of zirconium silicide and its oxidation kinetics are analyzed. Zirconium silicide is a new suggested material to be used as coatings on existing Zr-based cladding alloys, the aim of this study is to evaluate if zirconium silicide is applicable to be used, so they can be more rapidly developed using existing cladding technology with some modifications. These silicide coatings are an attractive alternative to the use of coatings on zirconium claddings or to the lengthy development of monolithic ceramic or ceramic composite claddings and coatings.

  20. Analyses on Silicide Coating for LOCA Resistant Cladding

    International Nuclear Information System (INIS)

    Sweidan, Faris B.; Lee, You Ho; Ryu, Ho Jin

    2015-01-01

    A particular focus of accident-tolerant fuel has been cladding due to the rapid high-temperature oxidation of zirconium-based cladding with the evolution of H2 when steam is a reactant. Some key features of the coated cladding include high-temperature resistance to oxidation, lower processing temperatures, and a high melting point of the coating. Zirconium alloys exhibit a reasonably high melting temperature, so a coating for the cladding is appealing if the coating increases the high-temperature resistance to oxidation. In this case, the cladding is protected from complete oxidation. The cladding coating involves the application of zirconium silicide onto Zr-based cladding. Zirconium silicide coating is expected to produce a glassy layer that becomes more protective at elevated temperature. For this reason, silicide coatings on cladding offer the potential for improved reliability at normal operating temperatures and at the higher transient temperatures encountered during accidents. Although ceramic coatings are brittle and may have weak points to be used as coating materials, several ceramic coatings were successful and showed adherent behavior and high resistance to oxidation. In this study, the oxidation behavior of zirconium silicide and its oxidation kinetics are analyzed. Zirconium silicide is a new suggested material to be used as coatings on existing Zr-based cladding alloys, the aim of this study is to evaluate if zirconium silicide is applicable to be used, so they can be more rapidly developed using existing cladding technology with some modifications. These silicide coatings are an attractive alternative to the use of coatings on zirconium claddings or to the lengthy development of monolithic ceramic or ceramic composite claddings and coatings

  1. Accident tolerant fuel cladding development: Promise, status, and challenges

    Science.gov (United States)

    Terrani, Kurt A.

    2018-04-01

    The motivation for transitioning away from zirconium-based fuel cladding in light water reactors to significantly more oxidation-resistant materials, thereby enhancing safety margins during severe accidents, is laid out. A review of the development status for three accident tolerant fuel cladding technologies, namely coated zirconium-based cladding, ferritic alumina-forming alloy cladding, and silicon carbide fiber-reinforced silicon carbide matrix composite cladding, is offered. Technical challenges and data gaps for each of these cladding technologies are highlighted. Full development towards commercial deployment of these technologies is identified as a high priority for the nuclear industry.

  2. Simulation of ferromagnetic shielding to the critical current of Bi2223/Ag tape under external fields

    Energy Technology Data Exchange (ETDEWEB)

    Gu Chen [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Alamgir, A K M [Faculty of Engineering, Yokohama National University, 75-9 Tokiwadai, Hodogaya-ku, Yokohama (Japan); Qu Timing [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Han, Z [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China)

    2007-03-15

    Ferromagnetic material was electroplated onto the surface of the Bi2223/Ag multi-filamentary tape and as a result changed the I{sub c}(B) characteristic of the tape correspondingly. A numerical simulation was used to investigate the influence of ferromagnetic shielding (FS) on the performance of the tape, in particular the I{sub c} behaviour under perpendicular external fields. Using finite element analysis, we are able to understand how FS alters the flux distribution within the superconductor region under any arbitrary shielding structure. The shielding width, thickness and nonlinear property of the ferromagnetic material were taken into account for the simulation. Finally, optimized shielding parameters in association with different operating fields were suggested and these values could be considered for the next run of experimental work.

  3. Simulation of ferromagnetic shielding to the critical current of Bi2223/Ag tape under external fields

    International Nuclear Information System (INIS)

    Gu Chen; Alamgir, A K M; Qu Timing; Han, Z

    2007-01-01

    Ferromagnetic material was electroplated onto the surface of the Bi2223/Ag multi-filamentary tape and as a result changed the I c (B) characteristic of the tape correspondingly. A numerical simulation was used to investigate the influence of ferromagnetic shielding (FS) on the performance of the tape, in particular the I c behaviour under perpendicular external fields. Using finite element analysis, we are able to understand how FS alters the flux distribution within the superconductor region under any arbitrary shielding structure. The shielding width, thickness and nonlinear property of the ferromagnetic material were taken into account for the simulation. Finally, optimized shielding parameters in association with different operating fields were suggested and these values could be considered for the next run of experimental work

  4. Stress analysis and probabilistic assessment of multi-layer SiC-based accident tolerant nuclear fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Stone, J.G., E-mail: Joshua.Stone@ga.com; Schleicher, R.; Deck, C.P.; Jacobsen, G.M.; Khalifa, H.E.; Back, C.A.

    2015-11-15

    Silicon carbide (SiC) fiber, SiC matrix composites (SiC/SiC) are being considered as a cladding material for light water reactors in order to improve safety performance. Engineered, multi-layer cladding designs consisting of both monolithic SiC (mSiC) and SiC/SiC have been examined as promising concepts to meet both strength and impermeability requirements. A new model has been developed to calculate stresses and failure probabilities for multi-layer cladding consisting of SiC-based materials in reactor operating conditions. The results show that stresses in SiC-based cladding are dominated by temperature-dependent irradiation-induced swelling, with the largest stresses occurring during the cold shutdown conditions. Failure probabilities are driven by the resulting tensile stresses at the cladding inner wall, while the outer wall is subject to compressive stresses. This indicates that the inner SiC/SiC, outer mSiC concept has the lowest failure probability, as the pseudo-plastic deformation of the composite reduces tensile loading and the compressed monolith provides a reliable, impermeable barrier to fission product release.

  5. Conceptual design of a 20-kA current lead using forced-flow cooling and Ag-alloy-sheathed Bi-2223 high-temperature superconductors

    International Nuclear Information System (INIS)

    Heller, R.; Hull, J.R.

    1994-01-01

    High-temperature superconductors (HTSs), consisting of Bi-2223 HTS tapes sheathed with Ag alloys are proposed for a 20-kA current lead for the planned stellarator WENDELSTEIN 7-X. Forced-flow He cooling is used, and 4-K He cooling of the whole lead as well as 60-K He cooling of the copper part of the lead, is discussed. Power consumption and behavior in case of loss of He flow are given

  6. Ceramic Coatings for Clad (The C3 Project): Advanced Accident-Tolerant Ceramic Coatings for Zr-Alloy Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Sickafus, Kurt E. [Univ. of Tennessee, Knoxville, TN (United States); Wirth, Brian [Univ. of Tennessee, Knoxville, TN (United States); Miller, Larry [Univ. of Tennessee, Knoxville, TN (United States); Weber, Bill [Univ. of Tennessee, Knoxville, TN (United States); Zhang, Yanwen [Univ. of Tennessee, Knoxville, TN (United States); Patel, Maulik [Univ. of Tennessee, Knoxville, TN (United States); Motta, Arthur [Pennsylvania State Univ., University Park, PA (United States); Wolfe, Doug [Pennsylvania State Univ., University Park, PA (United States); Fratoni, Max [Univ. of California, Berkeley, CA (United States); Raj, Rishi [Univ. of Colorado, Boulder, CO (United States); Plunkett, Kenneth [Univ. of Colorado, Boulder, CO (United States); Was, Gary [Univ. of Michigan, Ann Arbor, MI (United States); Hollis, Kendall [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nelson, Andy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stanek, Chris [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Comstock, Robert [Westinghouse Electric Corporation, Pittsburgh, PA (United States); Partezana, Jonna [Westinghouse Electric Corporation, Pittsburgh, PA (United States); Whittle, Karl [Univ. of Sheffield (United Kingdom); Preuss, Michael [Univ. of Manchester (United Kingdom); Withers, Philip [Univ. of Manchester (United Kingdom); Wilkinson, Angus [Univ. of Oxford (United Kingdom); Donnelly, Stephen [Univ. of Huddersfield (United Kingdom); Riley, Daniel [Australian Nuclear Science and Technology Organisation, Syndney (Australia)

    2017-02-14

    The goal of this NEUP-IRP project is to develop a fuel concept based on an advanced ceramic coating for Zr-alloy cladding. The coated cladding must exhibit demonstrably improved performance compared to conventional Zr-alloy clad in the following respects: During normal service, the ceramic coating should decrease cladding oxidation and hydrogen pickup (the latter leads to hydriding and embrittlement). During a reactor transient (e.g., a loss of coolant accident), the ceramic coating must minimize or at least significantly delay oxidation of the Zr-alloy cladding, thus reducing the amount of hydrogen generated and the oxygen ingress into the cladding. The specific objectives of this project are as follows: To produce durable ceramic coatings on Zr-alloy clad using two possible routes: (i) MAX phase ceramic coatings or similar nitride or carbide coatings; and (ii) graded interface architecture (multilayer) ceramic coatings, using, for instance, an oxide such as yttria-stabilized zirconia (YSZ) as the outer protective layer. To characterize the structural and physical properties of the coated clad samples produced in 1. above, especially the corrosion properties under simulated normal and transient reactor operating conditions. To perform computational analyses to assess the effects of such coatings on fuel performance and reactor neutronics, and to perform fuel cycle analyses to assess the economic viability of modifying conventional Zr-alloy cladding with ceramic coatings. This project meets a number of the goals outlined in the NEUP-IRP call for proposals, including: Improve the fuel/cladding system through innovative designs (e.g. coatings/liners for zirconium-based cladding) Reduce or eliminate hydrogen generation Increase resistance to bulk steam oxidation Achievement of our goals and objectives, as defined above, will lead to safer light-water reactor (LWR) nuclear fuel assemblies, due to improved cladding properties and built-in accident resistance, as well as

  7. An analytical method for calculating stresses and strains of ATF cladding based on thick walled theory

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Hyun; Kim, Hak Sung [Hanyang University, Seoul (Korea, Republic of); Kim, Hyo Chan; Yang, Yong Sik; In, Wang kee [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    In this paper, an analytical method based on thick walled theory has been studied to calculate stress and strain of ATF cladding. In order to prescribe boundary conditions of the analytical method, two algorithms were employed which are called subroutine 'Cladf' and 'Couple' of FRACAS, respectively. To evaluate the developed method, equivalent model using finite element method was established and stress components of the method were compared with those of equivalent FE model. One of promising ATF concepts is the coated cladding, which take advantages such as high melting point, a high neutron economy, and low tritium permeation rate. To evaluate the mechanical behavior and performance of the coated cladding, we need to develop the specified model to simulate the ATF behaviors in the reactor. In particular, the model for simulation of stress and strain for the coated cladding should be developed because the previous model, which is 'FRACAS', is for one body model. The FRACAS module employs the analytical method based on thin walled theory. According to thin-walled theory, radial stress is defined as zero but this assumption is not suitable for ATF cladding because value of the radial stress is not negligible in the case of ATF cladding. Recently, a structural model for multi-layered ceramic cylinders based on thick-walled theory was developed. Also, FE-based numerical simulation such as BISON has been developed to evaluate fuel performance. An analytical method that calculates stress components of ATF cladding was developed in this study. Thick-walled theory was used to derive equations for calculating stress and strain. To solve for these equations, boundary and loading conditions were obtained by subroutine 'Cladf' and 'Couple' and applied to the analytical method. To evaluate the developed method, equivalent FE model was established and its results were compared to those of analytical model. Based on the

  8. Capturing reflected cladding modes from a fiber Bragg grating with a double-clad fiber coupler.

    Science.gov (United States)

    Baiad, Mohamad Diaa; Gagné, Mathieu; Lemire-Renaud, Simon; De Montigny, Etienne; Madore, Wendy-Julie; Godbout, Nicolas; Boudoux, Caroline; Kashyap, Raman

    2013-03-25

    We present a novel measurement scheme using a double-clad fiber coupler (DCFC) and a fiber Bragg grating (FBG) to resolve cladding modes. Direct measurement of the optical spectra and power in the cladding modes is obtained through the use of a specially designed DCFC spliced to a highly reflective FBG written into slightly etched standard photosensitive single mode fiber to match the inner cladding diameter of the DCFC. The DCFC is made by tapering and fusing two double-clad fibers (DCF) together. The device is capable of capturing backward propagating low and high order cladding modes simply and efficiently. Also, we demonstrate the capability of such a device to measure the surrounding refractive index (SRI) with an extremely high sensitivity of 69.769 ± 0.035 μW/RIU and a resolution of 1.433 × 10(-5) ± 8 × 10(-9) RIU between 1.37 and 1.45 RIU. The device provides a large SRI operating range from 1.30 to 1.45 RIU with sufficient discrimination for all individual captured cladding modes. The proposed scheme can be adapted to many different types of bend, temperature, refractive index and other evanescent wave based sensors.

  9. Superconductivity: materials and applications; La supraconductivite: materiaux et apllications

    Energy Technology Data Exchange (ETDEWEB)

    Duchateau, J.L. [CEA Cadarache, 13 - Saint Paul lez Durance (France); Kircher, F. [CEA Saclay, 91 - Gif sur Yvette (France); Leveque, J. [Groupe de Recherche en Electrotechnique et Electronique de Nancy, GREEN - UHP, 54 - Vandoeuvre les Nancy (France); Tixador, P. [INP/Institut Neel, 38 - Grenoble (France)

    2008-07-01

    This digest paper presents the different types of superconducting materials: 1 - the low-TC superconductors: the multi-filament composite as elementary constituent, the world production of NbTi, the superconducting cables of the LHC collider and of the ITER tokamak; 2 - the high-TC superconductors: BiSrCaCuO (PIT 1G) ribbons and wires, deposited coatings; 3 - application to particle physics: the the LHC collider of the CERN, the LHC detectors; 4 - applications to thermonuclear fusion: Tore Supra and ITER tokamaks; 5 - NMR imaging: properties of superconducting magnets; 6 - applications in electrotechnics: cables, motors and alternators, current limiters, transformers, superconducting energy storage systems (SMES). (J.S.)

  10. Ag-based semiconductor photocatalysts in environmental purification

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiade; Fang, Wen [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi Province (China); Yu, Changlin, E-mail: yuchanglinjx@163.com [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi Province (China); School of Environment Engineering and biology Engineering, Guangdong University of Petrochemical Technology, Maoming, 525000 Guangdong Province (China); Zhou, Wanqin [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi Province (China); State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, 350002 (China); Zhu, Lihua [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi Province (China); Xie, Yu, E-mail: xieyu_121@163.com [College of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063, Jiangxi (China)

    2015-12-15

    Graphical abstract: Ag-based semiconductors as promising visible light-driven photocatalysts have aroused much interesting due to their strong visible light responsibility. Formation of heterojunction could largely promote the electron/hole pair separation, resulting in highly photocatalytic activity and stability. - Highlights: • Recent research progress in the fabrication and application of Ag-based semiconductor photocatalyts. • The advantages and disadvantages of Ag-based semiconductor as photocatalysts. • Strategies in design Ag-based semiconductor photocatalysts with high performance. - Abstract: Over the past decades, with the fast development of global industrial development, various organic pollutants discharged in water have become a major source of environmental pollution in waste fields. Photocatalysis, as green and environmentally friendly technology, has attracted much attention in pollutants degradation due to its efficient degradation rate. However, the practical application of traditional semiconductor photocatalysts, e.g. TiO{sub 2}, ZnO, is limited by their weak visible light adsorption due to their wide band gaps. Nowadays, the study in photocatalysts focuses on new and narrow band gap semiconductors. Among them, Ag-based semiconductors as promising visible light-driven photocatalysts have aroused much interesting due to their strong visible light responsibility. Most of Ag-based semiconductors could exhibit high initial photocatalytic activity. But they easy suffer from poor stability because of photochemical corrosion. Design heterojunction, increasing specific surface area, enriching pore structure, regulating morphology, controlling crystal facets, and producing plasmonic effects were considered as the effective strategies to improve the photocatalytic performance of Ag-based photocatalyts. Moreover, combining the superior properties of carbon materials (e.g. carbon quantum dots, carbon nano-tube, carbon nanofibers, graphene) with Ag-based

  11. Ag-based semiconductor photocatalysts in environmental purification

    International Nuclear Information System (INIS)

    Li, Jiade; Fang, Wen; Yu, Changlin; Zhou, Wanqin; Zhu, Lihua; Xie, Yu

    2015-01-01

    Graphical abstract: Ag-based semiconductors as promising visible light-driven photocatalysts have aroused much interesting due to their strong visible light responsibility. Formation of heterojunction could largely promote the electron/hole pair separation, resulting in highly photocatalytic activity and stability. - Highlights: • Recent research progress in the fabrication and application of Ag-based semiconductor photocatalyts. • The advantages and disadvantages of Ag-based semiconductor as photocatalysts. • Strategies in design Ag-based semiconductor photocatalysts with high performance. - Abstract: Over the past decades, with the fast development of global industrial development, various organic pollutants discharged in water have become a major source of environmental pollution in waste fields. Photocatalysis, as green and environmentally friendly technology, has attracted much attention in pollutants degradation due to its efficient degradation rate. However, the practical application of traditional semiconductor photocatalysts, e.g. TiO 2 , ZnO, is limited by their weak visible light adsorption due to their wide band gaps. Nowadays, the study in photocatalysts focuses on new and narrow band gap semiconductors. Among them, Ag-based semiconductors as promising visible light-driven photocatalysts have aroused much interesting due to their strong visible light responsibility. Most of Ag-based semiconductors could exhibit high initial photocatalytic activity. But they easy suffer from poor stability because of photochemical corrosion. Design heterojunction, increasing specific surface area, enriching pore structure, regulating morphology, controlling crystal facets, and producing plasmonic effects were considered as the effective strategies to improve the photocatalytic performance of Ag-based photocatalyts. Moreover, combining the superior properties of carbon materials (e.g. carbon quantum dots, carbon nano-tube, carbon nanofibers, graphene) with Ag-based

  12. Comparison of fiber lasers based on distributed side-coupled cladding-pumped fibers and double-cladding fibers.

    Science.gov (United States)

    Huang, Zhihe; Cao, Jianqiu; Guo, Shaofeng; Chen, Jinbao; Xu, Xiaojun

    2014-04-01

    We compare both analytically and numerically the distributed side-coupled cladding-pumped (DSCCP) fiber lasers and double cladding fiber (DCF) lasers. We show that, through optimization of the coupling and absorbing coefficients, the optical-to-optical efficiency of DSCCP fiber lasers can be made as high as that of DCF lasers. At the same time, DSCCP fiber lasers are better than the DCF lasers in terms of thermal management.

  13. Evidence for length-dependent wire expansion, filament dedensification and consequent degradation of critical current density in Ag-alloy sheathed Bi-2212 wires

    International Nuclear Information System (INIS)

    Malagoli, A; Lee, P J; Jiang, J; Trociewitz, U P; Hellstrom, E E; Larbalestier, D C; Ghosh, A K; Scheuerlein, C; Di Michiel, M

    2013-01-01

    It is well known that longer Bi-2212 conductors have significantly lower critical current density (J c ) than shorter ones, and recently it has become clear that a major cause of this reduction is internal gas pressure generated during heat treatment, which expands the wire diameter and dedensifies the Bi-2212 filaments. Here we report on the length-dependent expansion of 5–240 cm lengths of state-of-the-art, commercial Ag alloy sheathed Bi-2212 wire after full and some partial heat treatments. Detailed image analysis along the wire length shows that the wire diameter increases with distance from the ends, longer samples often showing evident damage and leaks provoked by the internal gas pressure. Comparison of heat treatments carried out just below the melting point and with the usual melt process makes it clear that melting is crucial to developing high internal pressure. The decay of J c away from the ends is directly correlated to the local wire diameter increase, which decreases the local Bi-2212 filament mass density and lowers J c , often by well over 50%. It is clear that control of the internal gas pressure is crucial to attaining the full J c of these very promising round wires and that the very variable properties of Bi-2212 wires are due to the fact that this internal gas pressure has so far not been well controlled. (paper)

  14. Annealing Effect on the Photoelectrochemical Properties of BiVO_4 Thin Film Electrodes

    International Nuclear Information System (INIS)

    Siti Nur Farhana Mohd Nasir; Mohd Asri Mat Teridi; Mehdi Ebadi; Sagu, J.S.

    2015-01-01

    Monoclinic bismuth vanadate (BiVO_4) thin film electrodes were fabricated on fluorine-doped tin oxide via aerosol-assisted chemical vapour deposition (AACVD). Annealing and without annealing effect of thin films were analysed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet-visible spectrophotometry (UV-Vis) and current voltage measurement. All BiVO_4 thin films showed an anodic photocurrent. The sample of BiVO_4 annealed at 400 degree Celsius exhibited the highest photocurrent density of 0.44 mAcm"-"2 vs. Ag/ AgCl at 1.23 V. (author)

  15. Solidification of Bi2Sr2Ca1Cu2Oy and Bi2Sr1.75Ca0.25CuOy

    International Nuclear Information System (INIS)

    Holesinger, T.G.; Miller, D.J.; Viswanathan, H.K.; Chumbley, L.S.

    1993-01-01

    The solidification processes for the compositions Bi 2 Sr 2 CaCu 2 O y (2212) and Bi 2 Sr 1.75 Ca 0.25 CuO y (2201) were determined as a function of oxygen partial pressure. During solidification in argon, the superconducting phases were generally not observed to form for either composition. In both cases, the solidus is lowered to approximately 750 degree C. Solidification of Bi 2 Sr 1.75 Ca 0.25 CuO y in Ar resulted in a divorced eutectic structure of Bi 2 Sr 2-x Ca x O y (22x) and Cu 2 O while solidification of Bi 2 Sr 2 CaCu 2 O y in Ar resulted in a divorced eutectic structure of Bi 2 Sr 3-x Ca x O y (23x) and Cu 2 O. Solidification of Bi 2 Sr 1.75 Ca 0.25 CuO y in O 2 resulted in large grains of 2201 interspersed with small regions containing the eutectic structure of 22x and CuO/Cu 2 O. Solidification of Bi 2 Sr 2 CaCu 2 O y in partial pressures of 1%, 20%, and 100% oxygen resulted in multiphase samples consisting of 2212, 2201, some alkaline-earth cuprates, and both divorced eutectic structures found during solidification in Ar. For both compositions, these latter structures can be attributed to oxygen deficiencies present in the melt regardless of the overpressure of oxygen. These eutectic structures are unstable and convert into the superconducting phases during subsequent anneals in oxygen. The formation process of the 2212 phase during solidification from the melt was determined to proceed through an intermediate state involving the 2201 phase

  16. Optimization of Ni-Based WC/Co/Cr Composite Coatings Produced by Multilayer Laser Cladding

    Directory of Open Access Journals (Sweden)

    Andrea Angelastro

    2013-01-01

    Full Text Available As a surface coating technique, laser cladding (LC has been developed for improving wear, corrosion, and fatigue properties of mechanical components. The main advantage of this process is the capability of introducing hard particles such as SiC, TiC, and WC as reinforcements in the metallic matrix such as Ni-based alloy, Co-based alloy, and Fe-based alloy to form ceramic-metal composite coatings, which have very high hardness and good wear resistance. In this paper, Ni-based alloy (Colmonoy 227-F and Tungsten Carbides/Cobalt/Chromium (WC/Co/Cr composite coatings were fabricated by the multilayer laser cladding technique (MLC. An optimization procedure was implemented to obtain the combination of process parameters that minimizes the porosity and produces good adhesion to a stainless steel substrate. The optimization procedure was worked out with a mathematical model that was supported by an experimental analysis, which studied the shape of the clad track generated by melting coaxially fed powders with a laser. Microstructural and microhardness analysis completed the set of test performed on the coatings.

  17. Crystal substructure and physical properties of the superconducting phase Bi4(Sr,Cr)6Cu4O16μ/sub x/

    International Nuclear Information System (INIS)

    Tarascon, J.M.; Le Page, Y.; Barboux, P.; Bagley, B.G.; Greene, L.H.; McKinnon, W.R.; Hull, G.W.; Giroud, M.; Hwang, D.M.

    1988-01-01

    We have isolated a high-T/sub c/ phase in the Bi-Sr-Ca-Cu-O system of composition Bi 4 (Sr,Ca) 6 Cu 4 O 16 μ/sub x/. The crystal substructure has a tetragonal unit cell (a = 3.817 A, c = 30.6 A) with similarities to both the oxygen-defect perovskites YBa 2 Cu 3 O 7 √/sub x/ and the K 2 NiF 4 structure of La 2 CuO 4 . The oxygen content, determined by titration and thermogravimetric analysis (TGA) experiments, corresponds to a formal oxidation state Cu(2.15). Oxygen can be reversibly depleted in an argon ambient in an amount corresponding to the reduction of the Cu(III) into Cu(II). The compound has a metalliclike resistance above its T/sub c/ near 85 K. Processing this precursor compound by heating to temperatures near its melting point (885 0 C) produces a sharp resistivity drop near 110 K that we show by ac susceptibility and Meissner effect is due to a superconducting transition

  18. Spin-on Bi4Sr3Ca3Cu4O16μ/sub x/ superconducting thin films from citrate precursors

    International Nuclear Information System (INIS)

    Furcone, S.L.; Chiang, Y.

    1988-01-01

    Thin films in the Bi-Sr-Ca-Cu-O system have been synthesized from homogeneous liquid citrate precursors by a spin-coating and pyrolysis method. Films prepared on SrTiO 3 substrates of [100] orientation show strongly textured orientations with the c axis of the predominant Bi 4 Sr 3 Ca 3 Cu 4 O 16 μ/sub x/ phase normal to the film plane. In a single coating and firing, crack-free films of 0.2--0.5 μm thickness are obtained. For films fired to peak temperatures of 850--875 0 C, linearly decreasing resistance with temperature is observed, with rho (300 K)∼460 μΩ cm and rho (300 K)rho (100 K)∼2.4. Clear onsets of superconductivity are observed at 90--100 K, with occasional films showing smaller resistant drops at 110--120 K. For all films, T/sub c/ (R = 0) occurs in the range 70--75 K. High critical current densities at 4.2 K of 5--8 x 10 5 Acm 2 are measured by direct transport

  19. Electronic Raman scattering in Bi2Sr2CaCu2O8=δ

    International Nuclear Information System (INIS)

    Quilty, J.W.; Trodahl, H.J.; Pooke, D.

    1996-01-01

    Full text: High-T c superconductors exhibit a definite Electronic Raman Scattering (ERS) continuum, which most materials do not. Typically, the continuum is relatively flat in the normal state, while below T c the ERS spectrum shows reduced scattering at the lowest Raman shifts and a peak close to the superconducting gap energy. The behaviour below T c is due to the breaking of Cooper pairs and reflects the superconducting density of states, hence revealing the superconducting gap. Through an appropriate choice of incident and scattered polarisation vectors, the electronic Raman continuum of high-T c superconductors may also be used to reveal information on the symmetry of the superconducting gap. Previous studies of the electronic continuum show that a broad peak associated with the superconducting gap forms in the continuum below T c in these materials, when compared to the normal-state. We report temperature and polarisation dependent ERS measurements on differently-doped Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212) single crystals, within a temperature range of 300 K to 10 K

  20. Amorphous-like interfacial layer between a high-Tc superconducting Tl-1223 film and a Ag substrate examined by high-voltage high-resolution transmission electron microscopy

    International Nuclear Information System (INIS)

    Kim, Bongjun; Kim, Hyuntak; Nagai, Takuro; Matsui, Yoshio; Horiuchi, Shigeo; Jeong, Daeyeong; Deinhofer, Christian; Gritzner, Gerhard; Kim, Youngmin; Kim, Younjoong

    2006-01-01

    The thin amorphous-like layer, formed at the interface between a high-T c superconducting (Tl 0.5 , Pb 0.5 )(Sr 0.8 , Ba 0.2 )Ca 2 Cu 3 O y (Tl-1223) film and a Ag substrate during heating at 910 .deg. C, has been examined by using high-voltage high-resolution transmission electron microscopy. The interfacial layer is less than 10 nm in thickness. It contacts the (001) plane of Tl-1223 and the (113) or (133) planes of Ag in most cases. Its composition is similar to that of Tl-1223, except for the inclusion of a substantial amount of Ag. Its formation proceeds by diffusion of Ag into Tl-1223, during which a structure change first occurs at the layer of CuO 2 + Ca planes. The Tl(Pb)O + the Sr(Ba)O layers are then destroyed to cause the total structure to become amorphous-like. Furthermore, we have found that it is formed under an irradiation of highly energetic electrons.

  1. Microwave dynamics of YBCO bi-epitaxial Josephson structures

    DEFF Research Database (Denmark)

    Constantinian, K. Y.; Ovsyannikov, G. A.; Mashtakov, A. D.

    1996-01-01

    The processes of interaction of microwaves (frequency View the MathML source) with a single high-Tc superconducting YBa2Cu3Ox (YBCO) bi-epitaxial grain-boundary junction and with an array of two junctions connected in series, have been investigated experimentally at temperatures T = 4.2− 77 K......, as well as the subharmonic detector response at weak magnetic fields φ microwave field induced frequency synchronization of two series connected bi-epitaxial YBCO junctions....

  2. Research Progress on Laser Cladding Amorphous Coatings on Metallic Substrates

    Directory of Open Access Journals (Sweden)

    CHEN Ming-hui

    2017-01-01

    Full Text Available The microstructure and property of amorphous alloy as well as the limitations of the traditional manufacturing methods for the bulk amorphous alloy were briefly introduced in this paper.Combined with characteristics of the laser cladding technique,the research status of the laser cladding Fe-based,Zr-based,Ni-based,Cu-based and Al-based amorphous coatings on the metal substrates were mainly summarized.The effects of factors such as laser processing parameter,micro-alloying element type and content and reinforcing phase on the laser cladding amorphous coatings were also involved.Finally,the main problems and the future research directions of the composition design and control of the laser-cladded amorphous coating,the design and optimization of the laser cladding process,and the basic theory of the laser cladding amorphous coatings were also put forward finally.

  3. Laser cladding of nickel base alloy on SS316L for improved wear and corrosion behaviour

    International Nuclear Information System (INIS)

    Awasthi, Reena; Kushwaha, R.P.; Chandra, Kamlesh; Viswanadham, C.S.; Srivastava, D.; Dey, G.K.; Limaye, P.K.

    2013-01-01

    Laser cladding by an Nd:YAG laser was employed to deposit Ni base alloy (Ni-Mo-Cr-Si) on stainless steel-316 L substrate. The resulting defect-free clad with minimum dilution of the substrate was characterized by optical microscopy, scanning electron microscopy, X-ray diffraction and Vickers microhardness test. Dry sliding wear of the cladding and the substrate was evaluated using a ball-on-plate reciprocating wear tester against different counter bodies (WC and 52100 Cr steel). The reciprocating sliding wear resistance of the coating was evaluated as a function of the normal load, keeping the sliding amplitude and sliding speed constant. Wear mechanisms were analyzed by observation of wear track morphology using SEM-EDS. The electrochemical corrosion behavior of clad layer was studied in reducing environment (HCl) to estimate the general corrosion resistance of the laser clad layer in comparison with the substrate SS-316L. The clad layer showed higher wear resistance under reducing condition than that of the substrate material stainless steel 316L. (author)

  4. Study of Bi-2212 phase doped Sn(Pb) by means of pat

    International Nuclear Information System (INIS)

    Ma Qingzhu; Huang Xiaoqian; Xiong Xiaotao

    1997-01-01

    Investigation on the effect of Sn/Pb-doped Bi-2212 superconductors has been carried out by the simultaneous measurements of the spectra of positron annihilation lifetime and positron Doppler broadening, together with X-ray diffraction. The results of samples with different doping level show the occupation of Sn atoms on Bi sites. At weak doping level, Sn doping results in a enhancement of cooperation between layers and increment of superconducting transition temperature. At the strong doping level, Sn atoms occupy the sites of Cu-O layers, and at the same time, the other nonsuperconducting phases appear, which results in a decline of the superconducting transition temperature

  5. Superconductivity in the unconventional high pressure phase bismuth-III

    Energy Technology Data Exchange (ETDEWEB)

    Semeniuk, Konstantin; Brown, Philip; Vasiljkovic, Aleksandar; Grosche, Malte [University of Cambridge (United Kingdom)

    2015-07-01

    One of the most surprising developments in high pressure research was the realisation that many elements assume very unexpected high pressure structures, described in terms of extremely large or even infinite unit cells. Elemental bismuth, which has been known to undergo a series of pressure induced structural transitions between 25 kbar and 80 kbar, is an interesting example: the intermediate pressure Bi-III phase has a complex 'host-guest' structure consisting of two incommensurate sublattices. Since the unit cell is infinitely large, the description of electronic and lattice excitations is problematic. Apart from its metallic character and the observation of superconductivity at low temperature, little is known about the electronic structure in this phase. We investigate the electrical resistivity within the metallic Bi-III phase under high hydrostatic pressure and in applied magnetic field using a piston cylinder cell. Superconductivity is observed below 7.1 K, and we extract the temperature dependence of the upper critical field, which exceeds 2 T at low temperature. The normal state resistivity exhibits an approximately linear temperature dependence. This could be attributed to strong scattering from low-lying excitations, as caused by an unusually soft phonon spectrum. The results suggest that strong coupling superconductivity arises within the host-guest structure of Bi-III out of an unusual electronic state.

  6. Cladding Alloys for Fluoride Salt Compatibility Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan [ORNL; Wilson, Dane F [ORNL; Santella, Michael L [ORNL; Holcomb, David Eugene [ORNL

    2011-05-01

    This interim report provides an overview of several candidate technologies for cladding nickel-based corrosion protection layers onto high-temperature structural alloys. The report also provides a brief overview of the welding and weld performance issues associated with joining nickel-clad nickel-based alloys. From the available techniques, two cladding technologies were selected for initial evaluation. The first technique is a line-of-sight method that would be useful for coating large structures such as vessel interiors or large piping. The line-of-sight method is a laser-based surface cladding technique in which a high-purity nickel powder mixed into a polymer binder is first sprayed onto the surface, baked, and then rapidly melted using a high power laser. The second technique is a vapor phase technique based on the nickel-carbonyl process that is suitable for coating inaccessible surfaces such as the interior surfaces of heat exchangers. The final project report will feature an experimental evaluation of the performance of the two selected cladding techniques.

  7. Mechanism of the formation of silver-sheathed HTSC ceramics and its fine structure

    International Nuclear Information System (INIS)

    Blinova, Yu.V.; Sudareva, S.V.; Krinitsina, T.P.; Romanov, E.P.; Akimov, I.I.

    2005-01-01

    Electron microscopical data are reported which point to the fact that two mechanisms of formation of main superconducting phase 2223 in Bi,Pb-2223/Ag exist: liquid phase mechanism and solid-phase one. Along crystallite boundaries the spherical outlined by Ag interlayers are observed. These are former eutectic liquid droplets of ∼ 2223 composition from which Ag is liberated on solidification. In the initial stage of phase formation inside of a 2212 phase the platelets of phase 2223 are found out with the same orientation as the matrix (a solid-phase mechanism). Certain relationships of structure to superconducting properties are shown [ru

  8. Theoretical analyses of superconductivity in iron based ...

    African Journals Online (AJOL)

    This paper focuses on the theoretical analysis of superconductivity in iron based superconductor Ba1−xKxFe2As2. After reviewing the current findings on this system, we suggest that phononexciton combined mechanism gives a right order of superconducting transition temperature (TC) for Ba1−xKxFe2As2 . By developing ...

  9. Development of innovative superconducting DC power cable

    Energy Technology Data Exchange (ETDEWEB)

    Matsushita, Teruo; Kiuchi, Masaru [Dept. of Computer Science and Electronics Kyushu Institute of Technology, Iizuka (Japan)

    2017-09-15

    It is required to reduce the cost of superconducting cable to realize a superconducting DC power network that covers a wide area in order to utilize renewable energy. In this paper a new concept of innovative cable is introduced that can enhance the current-carrying capacity even though the same superconducting tape is used. Such a cable can be realized by designing an optimal winding structure in such a way that the angle between the tape and magnetic field becomes small. This idea was confirmed by preliminary experiments for a single layer model cable made of Bi-2223 tapes and REBCO coated conductors. Experiments of three and four layer cables of practical sizes were also done and it was found that the current-carrying capacity increased as theoretically predicted. If the critical current properties of commercial superconducting tapes are further improved in a parallel magnetic field, the enhancement will become pronounced and this technology will surely contribute to realization of superconducting DC power network.

  10. Structure refinement of Ag-free heyrovskýite from Vulcano (Aeolian Islands, Italy)

    DEFF Research Database (Denmark)

    Pinto, Daniella; Balic Zunic, Tonci; Garavelli, Anna

    2011-01-01

    The first single-crystal structure refinement of Ag- and Cu-free heyrovskýite was performed in this study. Crystals investigated were sampled from the high-temperature fumaroles of La Fossa crater of Vulcano, Aeolian Islands, Italy. Electron microprobe analyses gave the average chemical formula (Pb...... with Fo > 4s(Fo). In Ag-free heyrovskýite from Vulcano, as well as in the synthetic Pb6Bi2S9, the trigonal prismatic coordinated position Me1, as well as the octahedrally coordinated position Me3 are occupied only by Pb. Me2, also octahedrally coordinated, is dominated by Pb, whereas the octahedra...... the ideal composition, Pb6Bi2S9. Selenium is preferentially ordered at the fivefold-coordinated anionic sites. Taking into account vacancies, as well as Se for S substitutions the structural formula of Ag-free heyrovskýite from Vulcano is Pb5.82Bi2.12¿0.06S8.70Se0.30. Comparison with the Ag...

  11. Initial Cladding Condition

    International Nuclear Information System (INIS)

    Siegmann, E.

    2000-01-01

    The purpose of this analysis is to describe the condition of commercial Zircaloy clad fuel as it is received at the Yucca Mountain Project (YMP) site. Most commercial nuclear fuel is encased in Zircaloy cladding. This analysis is developed to describe cladding degradation from the expected failure modes. This includes reactor operation impacts including incipient failures, potential degradation after reactor operation during spent fuel storage in pool and dry storage and impacts due to transportation. Degradation modes include cladding creep, and delayed hydride cracking during dry storage and transportation. Mechanical stresses from fuel handling and transportation vibrations are also included. This Analysis and Model Report (AMR) does not address any potential damage to assemblies that might occur at the YMP surface facilities. Ranges and uncertainties have been defined. This analysis will be the initial boundary condition for the analysis of cladding degradation inside the repository. In accordance with AP-2.13Q, ''Technical Product Development Planning'', a work plan (CRWMS M andO 2000c) was developed, issued, and utilized in the preparation of this document. There are constraints, caveats and limitations to this analysis. This cladding degradation analysis is based on commercial Pressurized Water Reactor (PWR) fuel with Zircaloy cladding but is applicable to Boiling Water Reactor (BWR) fuel. Reactor operating experience for both PWRs and BWRs is used to establish fuel reliability from reactor operation. It is limited to fuel exposed to normal operation and anticipated operational occurrences (i.e. events which are anticipated to occur within a reactor lifetime), and not to fuel that has been exposed to severe accidents. Fuel burnup projections have been limited to the current commercial reactor licensing environment with restrictions on fuel enrichment, oxide coating thickness and rod plenum pressures. The information provided in this analysis will be used in

  12. Ab initio study of properties of BaBiO3 at high pressure

    Science.gov (United States)

    Martoňák, Roman; Ceresoli, Davide; Kagayama, Tomoko; Tosatti, Erio

    BaBiO3 is a mixed-valence perovskite which escapes metallic state by creating a Bi-O bond disproportionation or CDW pattern, resulting in a Peierls semiconductor with gap of nearly 1 eV at zero pressure. Evolution of structural and electronic properties at high pressure is, however, largely unknown. Pressure, it might be natural to expect, could reduce the bond-disproportionation and bring the system closer to metalicity or even superconductivity. We address this question by ab initio DFT methods based on GGA and hybrid functionals in combination with crystal structure prediction techniques based on genetic algorithms. We analyze the pressure evolution of bond disproportionation as well as other order parameters related to octahedra rotation for various phases in connection with corresponding evolution of the electronic structure. Results indicate that BaBiO3 continues to resist metalization also under pressure, through structural phase transitions which sustain and in fact increase the diversity of length of Bi-O bonds for neighboring Bi ions, in agreement with preliminary high pressure resistivity data. R.M. Slovak Research and Development Agency Contract APVV-15-0496, VEGA project No. 1-0904-15; E.T. ERC MODPHYSFRICT Advanced Grant No. 320796.

  13. Microstructural behavior of iron and bismuth added Sn-1Ag-Cu solder under elevated temperature aging

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Bakhtiar, E-mail: engrbakhtiaralikhan@gmail.com; Sabri, Mohd Faizul Mohd, E-mail: faizul@um.edu.my; Jauhari, Iswadi, E-mail: iswadi@um.edu.my [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2016-07-19

    An extensive study was done to investigate the microstructural behavior of iron (Fe) and bismuth (Bi) added Sn-1Ag-0.5Cu (SAC105) under severe thermal aging conditions. The isothermal aging was done at 200 °C for 100 h, 200 h, and 300 h. Optical microscopy with cross-polarized light revealed that the grain size significantly reduces with Fe/Bi addition to the base alloy SAC105 and remains literally the same after thermal aging. The micrographs of field emission scanning electron microscopy (FESEM) with backscattered electron detector and their further analysis via imageJ software indicated that Fe/Bi added SAC105 showed a significant reduction in the IMCs size (Ag{sub 3}Sn and Cu{sub 6}Sn{sub 5}), especially the Cu{sub 6}Sn{sub 5} IMCs, as well as β-Sn matrix and a refinement in the microstructure, which is due to the presence of Bi in the alloys. Moreover, their microstructure remains much more stable under severe thermal aging conditions, which is because of the presence of both Fe and Bi in the alloy. The microstructural behavior suggests that Fe/Bi modified SAC105 would have much improved reliability under severe thermal environments. These modified alloys also have relatively low melting temperature and low cost.

  14. Study of the electromagnetic characteristics of multiple HTSPPT modules based on the configuration of toroidal structure for inductive pulsed power supply

    Science.gov (United States)

    Zhang, Cunshan; Zheng, Xinxin; Li, Haitao; Li, Zhenmei; Zhang, Tao; Jiao, Can

    2018-04-01

    High temperature superconducting pulsed power transformer (HTSPPT) is an important device for pulsed power supplies. It consists of a superconducting primary and a normal conducting secondary, which is used for energy storage and current amplification. The critical current density, the energy storage, and the coupling coefficient are three main performance indexes. They are affected by the geometry parameters of HTSPPT modules, such as the height and the width of the superconducting coils. In addition, the hoop stress of the HTSPPT coils is limited by the maximum tensile strength of high temperature superconducting (HTS) tapes. In this paper, Bi-2223/Ag HTS tapes are selected as the wire of primary inductor and the toroidal structure model is selected for multiple HTSPPT modules. The relationships between the geometry parameters of HTSPPT modules and the electrical performance are studied.

  15. A study on the development of high Tc superconducting materials

    International Nuclear Information System (INIS)

    Won, Dong Yeon; Lee, Hee Gyoun; Kim, Chan Joong

    1990-01-01

    The microstructure, crystal structure and formation kinetics for the superconducting phases were studied in the lead-doped BiSrCaCuO system. The formation kinetics was also investigated in the samples with different Pb/Bi ratio and it was observed that the 30 % Pb addition is most perferable for the formation of the high T c phase. The formation of the high T c phase was delayed by the excessive addition of Pb. The lattice parameter (c) of the unit cell of both low T c and high T c phases increased with increasing Pb content. Superconducting thin film was sucessfully prepared by chemical vapor deposition (CVD). Film deposited on MgO substrate showed a T c , onset of 85 K and did not reach to zero resistivity down to 77 K. Superconducting 124 phase in Y-system, which is more stable than 123 phase at high temperature showed a T c , onser of 84 K. Additionally, 0.1 mole of Pb, Sn and Ca was substituted for yttrium in 124 phase, respectively. For Pb and Sn-subsituted specimens, 124 phase was formed and for Ca substituted specimen, 124 phase was not formed and revealed no superconductivity down to 77 K. For Sn-substituted specimens, 124 phase was formed but showed no superconductivity down to 77 K. (author)

  16. Superconducting properties of clustered PbBi films

    International Nuclear Information System (INIS)

    Lobb, C.J.; Tinkham, M.; Klapwijk, T.M.; Smith, A.D.; Harvard Univ., Cambridge, MA

    1981-01-01

    Superconducting films with high resistance/square have been widely studied as a model of the Kosterlitz-Thouless transition. We show that the behavior of high R clean films near the thickness at which electrical conduction begins is dominated by a few paths across the film and thus should not be interpreted as a Kosterlitz-Thouless transition. Instead, this behavior is consistent with a simple percolation model for the connectivity fluctuations across the film. (orig.)

  17. Duplex stainless steel surface bay laser cladding

    International Nuclear Information System (INIS)

    Amigo, V.; Pineda, Y.; Segovia, F.; Vicente, A.

    2004-01-01

    Laser cladding is one of the most promising techniques to restore damaged surfaces and achieve properties similar to those of the base metal. In this work, duplex stainless steels have been cladded by a nickel alloy under different processing conditions. The influence of the beam speed and defocusing variables ha been evaluated in the microstructure both of the cladding and heat affected zone, HAZ. These results have been correlated to mechanical properties by means of microhardness measurements from cladding area to base metal through the interface. This technique has shown to be very appropriate to obtain controlled mechanical properties as they are determined by the solidification microstructure, originated by the transfer of mass and heat in the system. (Author) 21 refs

  18. Effect of Cobalt on Microstructure and Wear Resistance of Ni-Based Alloy Coating Fabricated by Laser Cladding

    Directory of Open Access Journals (Sweden)

    Kaiming Wang

    2017-12-01

    Full Text Available Ni-based alloy powders with different contents of cobalt (Co have been deposited on a 42CrMo steel substrate surface using a fiber laser. The effects of Co content on the microstructure, composition, hardness, and wear properties of the claddings were studied by scanning electron microscopy (SEM, an electron probe microanalyzer (EPMA, X-ray diffraction (XRD, a hardness tester, and a wear tester. The results show that the phases in the cladding layers are mainly γ, M7(C, B3, M23(C, B6, and M2B. With the increase in Co content, the amounts of M7(C, B3, M23(C, B6, and M2B gradually decrease, and the width of the eutectic structure in the cladding layer also gradually decreases. The microhardness decreases but the wear resistance of the cladding layer gradually improves with the increase of Co content. The wear resistance of the NiCo30 cladding layer is 3.6 times that of the NiCo00 cladding layer. With the increase of Co content, the wear mechanism of the cladding layer is changed from abrasive wear to adhesive wear.

  19. Modelling of pellet-clad interaction during power ramps

    International Nuclear Information System (INIS)

    Zhou, G.; Lindback, J.E.; Schutte, H.C.; Jernkvist, L.O.; Massih, A.R.; Massih, A.R.

    2005-01-01

    A computational method to describe the pellet-clad interaction phenomenon is presented. The method accounts for the mechanical contact between fragmented pellets and the zircaloy clad, as well as for chemical reaction of fission products with zircaloy during power ramps. Possible pellet-clad contact states, soft, hard and friction, are taken into account in the computational algorithm. The clad is treated as an elastic-plastic-viscoplastic material with irradiation hardening. Iodine-induced stress corrosion cracking is described by using a fracture mechanics-based model for crack propagation. This integrated approach is used to evaluate two power ramp experiments made on boiling water reactor fuel rods in test reactors. The influence of the pellet-clad coefficient of friction on clad deformation is evaluated and discussed. Also, clad deformations, pellet-clad gap size and fission product gas release for one of the ramped rods are calculated and compared with measured data. (authors)

  20. Fiber laser cladding of nickel-based alloy on cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Arias-González, F., E-mail: felipeag@uvigo.es [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Val, J. del [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Comesaña, R. [Materials Engineering, Applied Mechanics and Construction Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Penide, J.; Lusquiños, F.; Quintero, F.; Riveiro, A.; Boutinguiza, M.; Pou, J. [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain)

    2016-06-30

    Highlights: • Fiber laser cladding of Ni-based alloy on cast iron was experimentally studied. • Two different types of cast iron have been analyzed: gray and ductile cast iron. • Suitable processing parameters to generate a Ni-based coating were determined. • Dilution is higher in gray cast iron samples than in ductile cast iron. • Ni-based coating presents higher hardness than cast iron but similar Young's modulus. - Abstract: Gray cast iron is a ferrous alloy characterized by a carbon-rich phase in form of lamellar graphite in an iron matrix while ductile cast iron presents a carbon-rich phase in form of spheroidal graphite. Graphite presents a higher laser beam absorption than iron matrix and its morphology has also a strong influence on thermal conductivity of the material. The laser cladding process of cast iron is complicated by its heterogeneous microstructure which generates non-homogeneous thermal fields. In this research work, a comparison between different types of cast iron substrates (with different graphite morphology) has been carried out to analyze its impact on the process results. A fiber laser was used to generate a NiCrBSi coating over flat substrates of gray cast iron (EN-GJL-250) and nodular cast iron (EN-GJS-400-15). The relationship between processing parameters (laser irradiance and scanning speed) and geometry of a single laser track was examined. Moreover, microstructure and composition were studied by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD). The hardness and elastic modulus were analyzed by means of micro- and nanoindentation. A hardfacing coating was generated by fiber laser cladding. Suitable processing parameters to generate the Ni-based alloy coating were determined. For the same processing parameters, gray cast iron samples present higher dilution than cast iron samples. The elastic modulus is similar for the coating and the substrate, while the Ni-based

  1. THE STRUCTURE AND PROPERTIES OF COMPOSITE LASER CLAD COATINGS WITH Ni BASED MATRIX WITH WC PARTICLES

    Directory of Open Access Journals (Sweden)

    Zita Iždinská

    2010-09-01

    Full Text Available In this work, the influence of the processing conditions on the microstructure and abrasive wear behavior of composite laser clad coatings with Ni based matrix reinforced with 50% WC particles is analyzed. Composite powder was applied in the form of coatings onto a mild steel substrate (Fe–0.17% C by different laser powers and cladding speeds. The microstructure of the coatings was analyzed by scanning electron microscopy (SEM. Tribological properties of coatings were evaluated by pin-on-disc wear test. It appeared that the hardness of the matrix of composite coatings decreases with increasing cladding speed. However, wear resistance of composite coatings with decreasing hardness of Ni based matrix increases. Significantly enhanced wear resistance of WC composite coatings in comparison with Ni based coatings is attributed to the hard phase structures in composite coatings.

  2. Residual stress and crack initiation in laser clad composite layer with Co-based alloy and WC + NiCr

    International Nuclear Information System (INIS)

    Lee, Changmin; Park, Hyungkwon; Yoo, Jaehong; Lee, Changhee; Woo, WanChuck; Park, Sunhong

    2015-01-01

    Highlights: • Major problem, clad cracking in laser cladding process, was researched. • Residual stress measurements were performed quantitatively by neutron diffraction method along the surface of specimens. • Relationship between the residual stress and crack initiation was showed clearly. • Ceramic particle effect in the metal matrix was showed from the results of residual stress measurements. • Initiation sites of generating clad cracks were specifically studied in MMC coatings. - Abstract: Although laser cladding process has been widely used to improve the wear and corrosion resistance, there are unwanted cracking issues during and/or after laser cladding. This study investigates the tendency of Co-based WC + NiCr composite layers to cracking during the laser cladding process. Residual stress distributions of the specimen are measured using neutron diffraction and elucidate the correlation between the residual stress and the cracking in three types of cylindrical specimens; (i) no cladding substrate only, (ii) cladding with 100% stellite#6, and (iii) cladding with 55% stellite#6 and 45% technolase40s. The microstructure of the clad layer was composed of Co-based dendrite and brittle eutectic phases at the dendritic boundaries. And WC particles were distributed on the matrix forming intermediate composition region by partial melting of the surface of particles. The overlaid specimen exhibited tensile residual stress, which was accumulated through the beads due to contraction of the coating layer generated by rapid solidification, while the non-clad specimen showed compressive. Also, the specimen overlaid with 55 wt% stellite#6 and 45 wt% technolase40s showed a tensile stress higher than the specimen overlaid with 100% stellite#6 possibly, due to the difference between thermal expansion coefficients of the matrix and WC particles. Such tensile stresses can be potential driving force to provide an easy crack path ways for large brittle fractures

  3. Residual stress and crack initiation in laser clad composite layer with Co-based alloy and WC + NiCr

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Changmin; Park, Hyungkwon; Yoo, Jaehong [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Changhee, E-mail: chlee@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Woo, WanChuck [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Park, Sunhong [Research Institute of Industrial Science & Technology, Hyo-ja-dong, Po-Hang, Kyoung-buk, San 32 (Korea, Republic of)

    2015-08-01

    Highlights: • Major problem, clad cracking in laser cladding process, was researched. • Residual stress measurements were performed quantitatively by neutron diffraction method along the surface of specimens. • Relationship between the residual stress and crack initiation was showed clearly. • Ceramic particle effect in the metal matrix was showed from the results of residual stress measurements. • Initiation sites of generating clad cracks were specifically studied in MMC coatings. - Abstract: Although laser cladding process has been widely used to improve the wear and corrosion resistance, there are unwanted cracking issues during and/or after laser cladding. This study investigates the tendency of Co-based WC + NiCr composite layers to cracking during the laser cladding process. Residual stress distributions of the specimen are measured using neutron diffraction and elucidate the correlation between the residual stress and the cracking in three types of cylindrical specimens; (i) no cladding substrate only, (ii) cladding with 100% stellite#6, and (iii) cladding with 55% stellite#6 and 45% technolase40s. The microstructure of the clad layer was composed of Co-based dendrite and brittle eutectic phases at the dendritic boundaries. And WC particles were distributed on the matrix forming intermediate composition region by partial melting of the surface of particles. The overlaid specimen exhibited tensile residual stress, which was accumulated through the beads due to contraction of the coating layer generated by rapid solidification, while the non-clad specimen showed compressive. Also, the specimen overlaid with 55 wt% stellite#6 and 45 wt% technolase40s showed a tensile stress higher than the specimen overlaid with 100% stellite#6 possibly, due to the difference between thermal expansion coefficients of the matrix and WC particles. Such tensile stresses can be potential driving force to provide an easy crack path ways for large brittle fractures

  4. Method of depositing thin films of high temperature Bi-Sr-Ca-Cu-O-based ceramic oxide superconductors

    International Nuclear Information System (INIS)

    Budd, K.D.

    1991-01-01

    This patent describes a method. It comprises preparing a liquid precursor of a Bi-Sr-Ca-Cu-O- based ceramic oxide superconductor phase, wherein the liquid precursor comprises an alkoxyalkanol, copper acrylate, strontium acrylate, bismuth nitrate, and calcium nitrate, wherein the liquid precursor has a cation ratio sufficient to form the desired stoichiometry in the ceramic oxide superconductor phase when the liquid precursor is heated to a temperature and for a time sufficient to provide the desired ceramic oxide superconductor phase, and wherein the copper acrylate, strontium acrylate, bismuth nitrate, and calcium nitrate are mutually soluble in the alkoxyalkanol; applying the liquid precursor to a substrate, wherein the substrate is one of an oxide ceramic, a metal selected from the group consisting of Ag and Ni, and Si; and heating the substrate in an oxygen-containing atmosphere with the liquid precursor applied thereon to a temperature and for a time sufficient to form a thin film comprising at least one Bi-Sr- Ca-Cu-O-based high temperature ceramic oxide superconductor phase

  5. First-principles investigation of the structure and synergistic chemical bonding of Ag and Mg at the Al | Ω interface in a Al-Cu-Mg-Ag alloy

    International Nuclear Information System (INIS)

    Sun Lipeng; Irving, Douglas L.; Zikry, Mohammed A.; Brenner, D.W.

    2009-01-01

    Density functional theory was used to characterize the atomic structure and bonding of the Al | Ω interface in a Al-Cu-Mg-Ag alloy. The most stable interfacial structure was found to be connected by Al-Al bonds with a hexagonal Al lattice on the surface of the Ω phase sitting on the vacant hollow sites of the Al {1 1 1} matrix plane. The calculations predict that when substituted separately for Al at this interface, Ag and Mg do not enhance the interface stability through chemical bonding. Combining Ag and Mg, however, was found to chemically stabilize this interface, with the lowest-energy structure examined being a bi-layer with Ag atoms adjacent to the Al matrix and Mg adjacent to the Ω phase. This study provides an atomic arrangement for the interfacial bi-layer observed experimentally in this alloy.

  6. Superconducting materials suitable for magnets

    CERN Multimedia

    CERN. Geneva. Audiovisual Unit

    2002-01-01

    The range of materials available for superconducting magnets is steadily expanding, even as the choice of material becomes potentially more complex. When virtually all magnets were cooled by helium at ~2-5 K it was easy to separate the domain of Nb-Ti from those of Nb$_{3}$Sn applications and very little surprise that more than 90% of all magnets are still made from Nb-Ti. But the development of useful conductors of the Bi-Sr-Ca-Cu-O and YBa2Cu3Ox high temperature superconductors, coupled to the recent discovery of the 39 K superconductor MgB2 and the developing availability of cryocoolers suggests that new classes of higher temperature, medium field magnets based on other than Nb-based conductors could become available in the next 5-10 years. My talks will discuss the essential physics and materials science of these 5 classes of material - Nb-Ti, Nb$_{3}$Sn, MgB2, Bi-Sr-Ca-Cu-O and YBa2Cu3Ox - in the context of those aspects of their science, properties and fabrication properties, which circumscribe their ap...

  7. Observation of Dirac state in half-Heusler material YPtBi

    OpenAIRE

    Hosen, M. Mofazzel; Dhakal, Gyanendra; Dimitri, Klauss; Choi, Hongchul; Kabir, Firoza; Sims, Christopher; Pavlosiuk, Orest; Wisniewski, Piotr; Durakiewicz, Tomasz; Zhu, Jian-Xin; Kaczorowski, Dariusz; Neupane, Madhab

    2018-01-01

    The prediction of non-trivial topological electronic states hosted by half-Heusler compounds makes them prime candidates for discovering new physics and devices as they harbor a variety of electronic ground states including superconductivity, magnetism, and heavy fermion behavior. Here we report normal state electronic properties of a superconducting half-Heusler compound YPtBi using angle-resolved photoemission spectroscopy (ARPES). Our data reveal the presence of a Dirac state at the zone c...

  8. 56th (fiscal 1997) Meeting on Cryogenics and Superconductivity; Dai 56 kai 1997 nendo shunki teion kogaku chodendo gakkai koen gaiyoshu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-05-14

    In the meeting, 266 papers were made public which deal with the following fields: GM refrigerators, pulse tube refrigerators, cold storage equipment, Bi-2212 system, coil application, superconducting generators, LHD/ITER/accelerators, cable-in conduit conductors, electromagnetic phenomena/proximity effect, oxide cable, Nb3Sn, Nb3Al, metal materials, WE-NET, friction/organic materials, composite materials, Nb3Sn, Nb3Al wires, strand wire structure analysis, hybrid superconducting wire, Y system, Bi system, low temperature device, measurement, high magnetic field NMR magnet, oxide NMR application, Bi-2223 system wire, pinning, NbTi ac wire, pinning/ac loss, various characteristics, superconducting application, refrigerating system, heat transfer, cryostat, Hg/Ti/Y system wire, ac loss/application, superconducting electric power storage system and the development of element technology therefor, current limiter/magnetic flotation, stability and drift of strand conductors, stability, ITER, LHD/accelerator/SLIM, oxide application, conductor stability test and others, and quench of ac cable.

  9. Particle and powder characterisation of Bi-based superconductors

    International Nuclear Information System (INIS)

    Yavuz, M.; Guo, Y. C.; Liu, H. L.; Dou, S. X.; Vance, E. R.

    1996-01-01

    Full text: Superconductor precursor powder was ground in a planetary and an attrition mill using various combinations of grinding container, balls and carrier (dry and wet). Dry milling was found to be more effective than wet milling for reducing particle size irrespective of container and ball materials used in the planetary milling. On the other hand, wet milling was found more effective in the attrition milling. Serious Si contamination was observed in powders milled using agate grinding materials. Some C from polypropylene container was found after milling, but no Zr from YSZ balls. Effect of particle size on the property of Bi 2223/Ag tapes was investigated in terms of critical current density (J c ). Fine particle size was found to show high J c

  10. SERS analysis of Ag nanostructures produced by ion-beam deposition

    Science.gov (United States)

    Atanasov, P. A.; Nedyalkov, N. N.; Nikov, Ru G.; Grüner, Ch; Rauschenbach, B.; Fukata, N.

    2018-03-01

    This study deals with the development of a novel technique for formation of advanced Ag nanostructures (NSs) to be applied to high-resolution analyses based on surface enhanced Raman scattering (SERS). It has direct bearing on human health and food quality, e.g., monitoring small amount or traces of pollutants or undesirable additives. Three types of nanostructured Ag samples were produced using ion-beam deposition at glancing angle (GLAD) on quartz. All fabricated structures were covered with BI-58 pesticide (dimethoate) or Rhodamine 6G (R6G) for testing their potential for use as substrates for (SERS).

  11. Superconductivity proximate to antiferromagnetism in a copper-oxide monolayer grown on Bi2Sr2CaCu2O8 +δ

    Science.gov (United States)

    Wang, Shuai; Zhang, Long; Wang, Fa

    2018-01-01

    A nodeless superconducting (SC) gap was reported in a recent scanning tunneling spectroscopy experiment of a copper-oxide monolayer grown on a Bi2Sr2CaCu2O8 +δ (Bi2212) substrate [Zhong et al., Sci. Bull. 61, 1239 (2016), 10.1007/s11434-016-1145-4], which is in stark contrast to the nodal d -wave pairing gap in the bulk cuprates. Motivated by this experiment, we first show with first-principles calculations that the tetragonal CuO (T-CuO) monolayer on the Bi2212 substrate is more stable than the commonly postulated CuO2 structure. The T-CuO monolayer is composed of two CuO2 layers sharing the same O atoms. The band structure is obtained by first-principles calculations, and its strong electron correlation is treated with the renormalized mean-field theory. We argue that one CuO2 sublattice is hole doped while the other sublattice remains half filled and may have antiferromagnetic (AF) order. The doped Cu sublattice can show d -wave SC; however, its proximity to the AF Cu sublattice induces a spin-dependent hopping, which splits the Fermi surface and may lead to a full SC gap. Therefore, the nodeless SC gap observed in the experiment could be accounted for by the d -wave SC proximity to an AF order, thus it is extrinsic rather than intrinsic to the CuO2 layers.

  12. Method for decontaminating stainless cladding tubes

    International Nuclear Information System (INIS)

    Komatsu, Fumiaki.

    1986-01-01

    Purpose: To form an oxide film over the surface of stainless cladding tubes and to efficiently remove radioactive materials from the steel surface together with the oxide layer by the use of an acid water solution. Method: After the removal of water from cladding tubes that have passed through the re-processing process, an oxide film is formed on the surface of the cladding tubes by heating over 400 deg C in an oxidizing atmosphere and thereafter washed again in an acid water solution. When the cladding tubes are thus oxidized once, the stainless base metal itself is oxidized, an oxide layer of several 10 μm or more being formed thereon. In consequence, since the oxide layer is far inferior in corrosion resistance to stainless metals, a pickling liquid easily penetrates into the stainless metal through the oxide layer, thereby remarkably promoting the peeling of the layer from the base metal surface and also improving the residual radioactive material removing efficiency together. (Takahashi, M.)

  13. Sample size effect on the determination of the irreversibility line of high-Tc superconductors

    International Nuclear Information System (INIS)

    Li, Q.; Suenaga, M.; Li, Q.; Freltoft, T.

    1994-01-01

    The irreversibility lines of a high-J c superconducting Bi 2 Sr 2 Ca 2 Cu 3 O x /Ag tape were systematically measured upon a sequence of subdivisions of the sample. The irreversibility field H r (T) (parallel to the c axis) was found to change approximately as L 0.13 , where L is the effective dimension of the superconducting tape. Furthermore, it was found that the irreversibility line for a grain-aligned Bi 2 Sr 2 Ca 2 Cu 3 O x specimen can be approximately reproduced by the extrapolation of this relation down to a grain size of a few tens of micrometers. The observed size effect could significantly obscure the real physical meaning of the irreversibility lines. In addition, this finding surprisingly indicated that the Bi 2 Sr 2 Ca 2 Cu 2 O x /Ag tape and grain-aligned specimen may have similar flux line pinning strength

  14. Reaction products between Bi-Sr-Ca-Cu-oxide thick films and alumina substrates

    International Nuclear Information System (INIS)

    Alarco, J.A.; Ilushechkin, A.; Yamashita, T.; Bhargava, A.; Barry, J.; Mackinnon, I.D.R.

    1997-01-01

    The structure and composition of reaction products between Bi-Sr-Ca-Cu-oxide (BSCCO) thick films and alumina substrates have been characterized using a combination of electron diffraction, scanning electron microscopy and energy dispersive X-ray spectrometry (EDX). Sr and Ca are found to be the most reactive cations with alumina. Sr 4 Al 6 O 12 SO 4 is formed between the alumina substrates and BSCCO thick films prepared from paste with composition close to Bi-2212 (and Bi-2212+10 wt.% Ag). For paste with composition close to Bi(Pb)-2223 +20 wt.% Ag, a new phase with f.c.c. structure, lattice parameter about a=24.5 A and approximate composition Al 3 Sr 2 CaBi 2 CuO x has been identified in the interface region. Understanding and control of these reactions is essential for growth of high quality BSCCO thick films on alumina. (orig.)

  15. Application of Coating Technology for Accident Tolerant Fuel Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun-Gil; Kim, Il-Hyun; Jung, Yang-Il; Park, Dong-Jun; Park, Jeong-Yong; Koo, Yang-Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    To commercialize the ATF cladding concepts, various factors are considered, such as safety under normal and accident conditions, economy for the fuel cycle, and developing development challenges, and schedule. From the proposed concepts, it is known that the cladding coating, FeCrAl alloy, and Zr-Mo claddings are considered as a near/mid-term application, whereas the SiC material is considered as a long-term application. Among them, the benefit of cladding coating on Zr-based alloys is the fuel cycle economy regarding the manufacturing, neutron cross section, and high tritium permeation characteristics. However, the challenge of cladding coating on Zr-based alloys is the lower oxidation resistance and mechanical strength at high-temperature than other concepts. Another important point is the adhesion property between the Zr-based alloy and coating materials. As an improved coating technology compared to a previous study, a 3D laser coating technology supplied with Cr powders is considered to make a coated cladding because it is possible to make a coated layer on the tubular cladding surface by controlling the 3-diminational axis. We are systematically studying the laser beam power, inert gas flow, cooling of the cladding tube, and powder control as key points to develop 3D laser coating technology. After Cr-coating on the Zr-based cladding, ring compression and ring tensile tests were performed to evaluate the adhesion property between a coated layer and Zr-based alloy tube at room temperature (RT), and a high-temperature oxidation test was conducted to evaluate the oxidation behavior at 1200 .deg. C of the coated tube samples. A 3D laser coating method supplied with Cr powders was developed to decrease the high-temperature oxidation rate in a steam environment through a systematic study for various coating parameters, and a Cr-coated Zircaloy-4 cladding tube of 100 mm in length to the axial direction can be successfully manufactured.

  16. Photoluminescence properties of Bi/Al-codoped silica optical fiber based on atomic layer deposition method

    International Nuclear Information System (INIS)

    Wen, Jianxiang; Wang, Jie; Dong, Yanhua; Chen, Na; Luo, Yanhua; Peng, Gang-ding; Pang, Fufei; Chen, Zhenyi; Wang, Tingyun

    2015-01-01

    Highlights: • We report on a new fabrication method of producing Bi/Al-codoped silica optical fibers. • There are obvious Bi-type ions absorption peaks at 520, 700 and 800 nm. • The fluorescence peaks are 1130 and 1145 nm with 489 and 705 nm excitations, respectively. • Their fluorescence lifetimes are 701 and 721 μs, respectively. • And then there are obvious fluorescence bands in 600–850 and 900–1650 nm with 532 nm pump exciting. • There is a maximum fluorescence intensity peak at 1120 nm, and its full wave at half maximum (FWHM) is approximately 180 nm. • These may mainly result from the interaction between Bi and Al ions. • The Bi/Al-codoped silica optical fibers would be used in high power or broadly tunable laser sources, and optical fiber amplifier in the optical communication fields. - Abstract: The Bi/Al-codoped silica optical fibers are fabricated by atomic layer deposition (ALD) doping technique combing with conventional modified chemical vapor deposition (MCVD) process. Bi 2 O 3 and Al 2 O 3 are induced into silica optical fiber core layer by ALD technique, with Bis (2,2,6,6-tetra-methyl-3,5-heptanedionato) Bismuth(III) (Bi(thd) 3 ) and H 2 O as Bi and O precursors, and with Al(CH 3 ) 3 (TMA) as Al precursor, respectively. The structure features and optical properties of Bi/Al-codoped silica optical fibers are investigated. Bi 2 O 3 stoichiometry is confirmed by X-ray photoelectron spectroscopy (XPS). The valence state of Bi element is +3. Concentration distribution of Si, Ge and O elements is approximately 24–33, 9 and 66 mol%, respectively, in fiber preform core and cladding layer region. Bi and Al ions have been also slightly doped approximately 150–180 and 350–750 ppm in fiber preform core, respectively. Refractive index difference of the Bi/Al-codoped fiber is approximately 0.58% using optical fiber refractive index profiler analyzer. There are obvious Bi-type ions absorption peaks at 520, 700 and 800 nm. The fluorescence

  17. Photoluminescence properties of Bi/Al-codoped silica optical fiber based on atomic layer deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Jianxiang, E-mail: wenjx@shu.edu.cn [Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072 (China); Wang, Jie; Dong, Yanhua; Chen, Na [Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072 (China); Luo, Yanhua; Peng, Gang-ding [Photonics & Optical Communications, School of Electrical Engineering & Telecommunications, University of New South Wales, Sydney 2052, NSW (Australia); Pang, Fufei; Chen, Zhenyi [Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072 (China); Wang, Tingyun, E-mail: tywang@mail.shu.edu.cn [Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072 (China)

    2015-09-15

    Highlights: • We report on a new fabrication method of producing Bi/Al-codoped silica optical fibers. • There are obvious Bi-type ions absorption peaks at 520, 700 and 800 nm. • The fluorescence peaks are 1130 and 1145 nm with 489 and 705 nm excitations, respectively. • Their fluorescence lifetimes are 701 and 721 μs, respectively. • And then there are obvious fluorescence bands in 600–850 and 900–1650 nm with 532 nm pump exciting. • There is a maximum fluorescence intensity peak at 1120 nm, and its full wave at half maximum (FWHM) is approximately 180 nm. • These may mainly result from the interaction between Bi and Al ions. • The Bi/Al-codoped silica optical fibers would be used in high power or broadly tunable laser sources, and optical fiber amplifier in the optical communication fields. - Abstract: The Bi/Al-codoped silica optical fibers are fabricated by atomic layer deposition (ALD) doping technique combing with conventional modified chemical vapor deposition (MCVD) process. Bi{sub 2}O{sub 3} and Al{sub 2}O{sub 3} are induced into silica optical fiber core layer by ALD technique, with Bis (2,2,6,6-tetra-methyl-3,5-heptanedionato) Bismuth(III) (Bi(thd){sub 3}) and H{sub 2}O as Bi and O precursors, and with Al(CH{sub 3}){sub 3} (TMA) as Al precursor, respectively. The structure features and optical properties of Bi/Al-codoped silica optical fibers are investigated. Bi{sub 2}O{sub 3} stoichiometry is confirmed by X-ray photoelectron spectroscopy (XPS). The valence state of Bi element is +3. Concentration distribution of Si, Ge and O elements is approximately 24–33, 9 and 66 mol%, respectively, in fiber preform core and cladding layer region. Bi and Al ions have been also slightly doped approximately 150–180 and 350–750 ppm in fiber preform core, respectively. Refractive index difference of the Bi/Al-codoped fiber is approximately 0.58% using optical fiber refractive index profiler analyzer. There are obvious Bi-type ions absorption

  18. Protective claddings for high strength chromium alloys

    Science.gov (United States)

    Collins, J. F.

    1971-01-01

    The application of a Cr-Y-Hf-Th alloy as a protective cladding for a high strength chromium alloy was investigated for its effectiveness in inhibiting nitrogen embrittlement of a core alloy. Cladding was accomplished by a combination of hot gas pressure bonding and roll cladding techniques. Based on bend DBTT, the cladding alloy was effective in inhibiting nitrogen embrittlement of the chromium core alloy for up to 720 ks (200hours) in air at 1422 K (2100 F). A significant increase in the bend DBTT occurred with longer time exposures at 1422 K or short time exposures at 1589 K (2400 F).

  19. Method of forming a ceramic superconducting composite wire using a molten pool

    International Nuclear Information System (INIS)

    Geballe, T.H.; Feigelson, R.S.; Gazit, D.

    1991-01-01

    This paper describes a method for making a flexible superconductive composite wire. It comprises: drawing a wire of noble metal through a molten material, formed by melting a solid formed by pressing powdered Bi 2 O 3 , CaCO 3 SrCO 3 and CuO in a ratio of components necessary for forming a Bi-Sr-Ca-Cu-O superconductor, into the solid and sintering at a temperature in the range of 750 degrees - 800 degrees C. for 10-20 hours, whereby the wire is coated by the molten material; and cooling the coated wire to solidify the molten material to form the superconductive flexible composite wire without need of further annealing

  20. Topological states in a two-dimensional metal alloy in Si surface: BiAg/Si(111)-4 ×4 surface

    Science.gov (United States)

    Zhang, Xiaoming; Cui, Bin; Zhao, Mingwen; Liu, Feng

    2018-02-01

    A bridging topological state with a conventional semiconductor platform offers an attractive route towards future spintronics and quantum device applications. Here, based on first-principles and tight-binding calculations, we demonstrate the existence of topological states hosted by a two-dimensional (2D) metal alloy in a Si surface, the BiAg/Si(111)-4 ×4 surface, which has already been synthesized experimentally. It exhibits a topological insulating state with an energy gap of 71 meV (˜819 K ) above the Fermi level and a topological metallic state with quasiquantized conductance below the Fermi level. The underlying mechanism leading to the formation of such nontrivial states is revealed by analysis of the "charge-transfer" and "orbital-filtering" effect of the Si substrate. A minimal effective tight-binding model is employed to reveal the formation mechanism of the topological states. Our finding opens opportunities to detect topological states and measure its quantized conductance in a large family of 2D surface metal alloys, which have been or are to be grown on semiconductor substrates.