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Sample records for cu damascene process

  1. Electromigration in Cu(Al) and Cu(Mn) damascene lines

    Science.gov (United States)

    Hu, C.-K.; Ohm, J.; Gignac, L. M.; Breslin, C. M.; Mittal, S.; Bonilla, G.; Edelstein, D.; Rosenberg, R.; Choi, S.; An, J. J.; Simon, A. H.; Angyal, M. S.; Clevenger, L.; Maniscalco, J.; Nogami, T.; Penny, C.; Kim, B. Y.

    2012-05-01

    The effects of impurities, Mn or Al, on interface and grain boundary electromigration (EM) in Cu damascene lines were investigated. The addition of Mn or Al solute caused a reduction in diffusivity at the Cu/dielectric cap interface and the EM activation energies for both Cu-alloys were found to increase by about 0.2 eV as compared to pure Cu. Mn mitigated and Al enhanced Cu grain boundary diffusion; however, no significant mitigation in Cu grain boundary diffusion was observed in low Mn concentration samples. The activation energies for Cu grain boundary diffusion were found to be 0.74 ± 0.05 eV and 0.77 ± 0.05 eV for 1.5 μm wide polycrystalline lines with pure Cu and Cu (0.5 at. % Mn) seeds, respectively. The effective charge number in Cu grain boundaries Z*GB was estimated from drift velocity and was found to be about -0.4. A significant enhancement in EM lifetimes for Cu(Al) or low Mn concentration bamboo-polycrystalline and near-bamboo grain structures was observed but not for polycrystalline-only alloy lines. These results indicated that the existence of bamboo grains in bamboo-polycrystalline lines played a critical role in slowing down the EM-induced void growth rate. The bamboo grains act as Cu diffusion blocking boundaries for grain boundary mass flow, thus generating a mechanical stress-induced back flow counterbalancing the EM force, which is the equality known as the "Blech short length effect."

  2. Electromigration-induced drift in damascene and plasma-etched Al(Cu). II. Mass transport mechanisms in bamboo interconnects

    Science.gov (United States)

    Proost, Joris; Maex, Karen; Delacy, Luc

    2000-01-01

    We have discussed electromigration (EM)-induced drift in polycrystalline damascene versus reactive ion etched (RIE) Al(Cu) in part I. For polycrystalline Al(Cu), mass transport is well documented to occur through sequential stages : an incubation period (attributed to Cu depletion beyond a critical length) followed by the Al drift stage. In this work, the drift behavior of bamboo RIE and damascene Al(Cu) is analyzed. Using Blech-type test structures, mass transport in RIE lines was shown to proceed both by lattice and interfacial diffusion. The dominating mechanism depends on the Cu distribution in the line, as was evidenced by comparing as-patterned (lattice EM) and RTP-annealed (interface EM) samples. The interfacial EM only occurs at metallic interfaces. In that case, Cu alloying was observed to retard Al interfacial mass transport, giving rise to an incubation time. Although the activation energy for the incubation time was found similar to the one controlling Al lattice drift, for which no incubation time was observed, lattice EM is preferred over interfacial EM because it is insensitive to enhancing geometrical effects upon scaling. When comparing interfacial electromigration in RIE with bamboo damascene Al(Cu), with the incubation time rate controlling for both, the higher EM threshold observed for damascene was shown to be insufficient to compensate for its significantly increased Cu depletion rate, contrary to the case of polycrystalline Al(Cu) interconnects. Two factors were demonstrated to contribute. First, there are more metallic interfaces, intrinsically related to the use of wetting or barrier layers in recessed features. Second, specific to this study, the additional formation of TiAl3 at the trench sidewalls further enhanced the Cu depletion rate, and reduced the rate-controlling incubation time. A separate drift study on RIE via-type test structures indicated that it is very difficult to suppress interfacial mass transport in favor of lattice EM

  3. Crystal plasticity in Cu damascene interconnect lines undergoing electromigration as revealed by synchrotron x-ray microdiffraction

    Science.gov (United States)

    Budiman, A. S.; Nix, W. D.; Tamura, N.; Valek, B. C.; Gadre, K.; Maiz, J.; Spolenak, R.; Patel, J. R.

    2006-06-01

    Plastic deformation was observed in damascene Cu interconnect test structures during an in situ electromigration experiment and before the onset of visible microstructural damage (voiding, hillock formation). We show here, using a synchrotron technique of white beam x-ray microdiffraction, that the extent of this electromigration-induced plasticity is dependent on the linewidth. In wide lines, plastic deformation manifests itself as grain bending and the formation of subgrain structures, while only grain rotation is observed in the narrower lines. The deformation geometry leads us to conclude that dislocations introduced by plastic flow lie predominantly in the direction of electron flow and may provide additional easy paths for the transport of point defects. Since these findings occur long before any observable voids or hillocks are formed, they may have direct bearing on the final failure stages of electromigration.

  4. High-etch-rate bottom-antireflective coating and gap-fill materials using dextrin derivatives in via first dual-Damascene lithography process

    Science.gov (United States)

    Takei, Satoshi; Sakaida, Yasushi; Shinjo, Tetsuya; Hashimoto, Keisuke; Nakajima, Yasuyuki

    2008-03-01

    The present paper describes a novel class of bottom antireflective coating (BARC) and gap fill materials using dextrin derivatives. The general trend of interconnect fabrication for such a high performance LSI is to apply cupper (Cu)/ low-dielectric-constant (low-k) interconnect to reduce RC delay. A via-first dual damascene process is one of the most promising processes to fabricate Cu/ low-k interconnect due to its wide miss-alignment margin. The sacrificial materials containing dextrin derivatives under resist for lithography were developed in via-first dual damascene process. The dextrin derivatives in this study was obtained by the esterification of the hydroxyl groups of dextrin resulting in improved solubility in the resist solvents such as propylene glycol monomethylether, propylene glycol monomethylether acetate, and ethyl lactate due to avoid the issue of defects that were caused by incompatability. The etch rate of our developed BARC and gap fill materials using dextrin derivatives was more than two times faster than one of the ArF resists evaluated in a CF4 gas condition using reactive ion etching. The improved etch performance was also verified by comparison with poly(hydroxystyrene), acrylate-type materials and latest low-k materials as a reference. In addition to superior etch performance, these materials showed good resist profiles and via filling performance without voids in via holes.

  5. Multilevel Dual Damascene copper interconnections

    Science.gov (United States)

    Lakshminarayanan, S.

    Copper has been acknowledged as the interconnect material for future generations of ICs to overcome the bottlenecks on speed and reliability present with the current Al based wiring. A new set of challenges brought to the forefront when copper replaces aluminum, have to be met and resolved to make it a viable option. Unit step processes related to copper technology have been under development for the last few years. In this work, the application of copper as the interconnect material in multilevel structures with SiO2 as the interlevel dielectric has been explored, with emphasis on integration issues and complete process realization. Interconnect definition was achieved by the Dual Damascene approach using chemical mechanical polishing of oxide and copper. The choice of materials used as adhesion promoter/diffusion barrier included Ti, Ta and CVD TiN. Two different polish chemistries (NH4OH or HNO3 based) were used to form the interconnects. The diffusion barrier was removed during polishing (in the case of TiN) or by a post CMP etch (as with Ti or Ta). Copper surface passivation was performed using boron implantation and PECVD nitride encapsulation. The interlevel dielectric way composed of a multilayer stack of PECVD SiO2 and SixNy. A baseline process sequence which ensured the mechanical and thermal compatibility of the different unit steps was first created. A comprehensive test vehicle was designed and test structures were fabricated using the process flow developed. Suitable modifications were subsequently introduced in the sequence as and when processing problems were encountered. Electrical characterization was performed on the fabricated devices, interconnects, contacts and vias. The structures were subjected to thermal stressing to assess their stability and performance. The measurement of interconnect sheet resistances revealed lower copper loss due to dishing on samples polished using HNO3 based slurry. Interconnect resistances remained stable upto 400o

  6. Optimized ultra-thin manganin alloy passivated fine-pitch damascene compatible bump-less Cu-Cu bonding at sub 200 °C for three-dimensional Integration applications

    Science.gov (United States)

    Panigrahi, Asisa Kumar; Hemanth Kumar, C.; Bonam, Satish; Ghosh, Tamal; Rama Krishna Vanjari, Siva; Govind Singh, Shiv

    2018-02-01

    Enhanced Cu diffusion, Cu surface passivation, and smooth surface at the bonding interface are the key essentials for high quality Cu-Cu bonding. Previously, we have demonstrated optimized 3 nm thin Manganin metal-alloy passivation from oxidation and also helps to reduce the surface roughness to about 0.8 nm which substantially led to high quality Cu-Cu bonding. In this paper, we demonstrated an ultra fine-pitch (indication of high quality bonding for future multilayer integrations. Furthermore, electrical characterization of the bonded structure was performed under various robust conditions as per International Technology Roadmap for Semiconductors (ITRS Roadmap) in order to satisfy the stability of the bonded structure.

  7. Modeling and Measurement of Stress and Strain Evolution in Cu Interconnects

    International Nuclear Information System (INIS)

    Besser, Paul R.; Zhai, Charlie Jun

    2004-01-01

    The damascene fabrication method and the introduction of low-K dielectrics present a host of reliability challenges to Cu interconnects and fundamentally change the mechanical stress state of Cu lines used as interconnects for integrated circuits. In order to capture the effect of individual process steps on the stress evolution in the BEoL (Back End of Line), a process-oriented finite element modeling (FEM) approach was developed. In this model, the complete stress history at any step of BEoL can be simulated as a dual damascene Cu structure is fabricated. The model was calibrated with both wafer-curvature blanket film measurements and X-Ray diffraction (XRD) measurement of metal line stress. The Cu line stress evolution was simulated during the process of multi-step processing for dual damascene Cu/TEOS and Cu/low-k structures. The in-plane stress of Cu lines is nearly independent of subsequent processes, while the out-of-plane stress increases considerably with the subsequent process steps. The modeling results will be compared with recent XRD measurements and extended generically to illustrate the relative influence of the dielectric (ILD) modulus (E) and coefficient of thermal expansion (CTE) on strain/stress in the Cu lines. It will be shown that the stress magnitude and state (hydrostatic, deviatoric) depend on ILD properties. The stress along the line length (longitudinal) is substrate-dominated, while the transverse and normal stresses vary with both CTE and modulus of the dielectric. The hydrostatic stress is primarily determined by ILD modulus and is nearly independent of the ILD CTE, while the Von Mises stress depends on both CTE and E of the ILD. The stress of the Cu line tends to be more deviatoric with spin-on low K ILDs, and more hydrostatic with oxide encapsulation

  8. Multilevel integration of patternable low-κ material into advanced Cu BEOL

    Science.gov (United States)

    Lin, Qinghuang; Chen, S. T.; Nelson, A.; Brock, P.; Cohen, S.; Davis, B.; Fuller, N.; Kaplan, R.; Kwong, R.; Liniger, E.; Neumayer, D.; Patel, J.; Shobha, H.; Sooriyakumaran, R.; Purushothaman, S.; Spooner, T.; Miller, R.; Allen, R.; Wisnieff, R.

    2010-04-01

    In this paper, we wish to report, for the first time, on a simple, low-cost, novel way to form dual-damascene copper (Cu) on-chip interconnect or Back-End-Of-the-Line (BEOL) structures using a patternable low dielectric constant (low-κ) dielectric material concept. A patternable low-κ dielectric material combines the functions of a traditional resist and a dielectric material into one single material. It acts as a traditional resist during patterning and is subsequently converted to a low-κ dielectric material during a post-patterning curing process. No sacrificial materials (separate resists or hardmasks) and their related deposition, pattern transfer (etch) and removal (strip) are required to form dual-damascene BEOL patterns. We have successfully demonstrated multi-level dual-damascene integration of a novel patternable low-κ dielectric material into advanced Cu BEOL. This κ=2.7 patternable low-κ material is based on the industry standard SiCOH-based (silsesquioxane polymer) material platform and is compatible with 248 nm optical lithography. Multilevel integration of this patternable low-κ material at 45 nm node Cu BEOL fatwire levels has been demonstrated with very high electrical yields using the current manufacturing infrastructure.

  9. PROPORTIONS AND HUMAN SCALE IN DAMASCENE COURTYARD HOUSES

    Directory of Open Access Journals (Sweden)

    M. Salim Ferwati

    2008-03-01

    Full Text Available Interior designers, architects, landscape architects, and even urban designers, agree that environment, as a form of non-verbal communication means, has a symbolic dimension to it. As for its aesthetic dimension, it seems that beauty is related to a certain proportion, partially and as a whole. Suitable proportion leaves a good impression upon the beholders, especially when it matches human proportion. That in fact was the underlining belief of LeCorbusier, according to which he developed his Modular concept. The study searches for a modular, or proportion, system that governs the design of Damascene traditional house. By geometrical and mathematical examinations of 28 traditional houses, it was found that a certain proportional relationship existed; however, these proportional relationships were not fixed ones. The study relied on analyzing the Iwan elevation as well as the inner courtyard proportion in relation to the building area. Charts, diagrams and tables were produced to summarize the results.

  10. Effect of Rosa damascene aromatherapy on sleep quality in cardiac patients: a randomized controlled trial.

    Science.gov (United States)

    Hajibagheri, Ali; Babaii, Atye; Adib-Hajbaghery, Mohsen

    2014-08-01

    Sleep disorders are common among patients hospitalized in coronary care unit (CCU). This study aimed to investigate the effect of Rosa damascene aromatherapy on sleep quality of patients hospitalized in CCU. In this randomized controlled trial, 60 patients who met the inclusion criteria were conveniently sampled and randomly allocated to the experimental and control groups. Patients in the control group received routine care. In the experimental group, patients received routine care and Rosa damascene aromatherapy for three subsequent nights. In the both groups the sleep quality was assessed using the Pittsburgh Sleep Quality Index. After the study, the mean scores of five domains of Pittsburg Sleep Quality Index as well as the mean of total score of the index in the experimental group were significantly lower than the control group. Rosa damascene aromatherapy can significantly improve the sleep quality of patients hospitalized in CCUs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. MFM observation of spin structures in nano-magnetic-dot arrays fabricated by damascene technique

    International Nuclear Information System (INIS)

    Sato, K.; Yamamoto, T.; Tezuka, T.; Ishibashi, T.; Morishita, Y.; Koukitu, A.; Machida, K.; Yamaoka, T.

    2006-01-01

    Regularly aligned arrays of magnetic nano dots buried in silicon wafers have been fabricated using damascene technique with the help of electron beam lithography. Arrays of square, rectangular, cross-shaped and Y-shaped structures of submicron size have been obtained. Spin distributions have been observed by means of magnetic force microscopy and analyzed by a micromagnetic simulation with Landau-Lifshitz-Gilbert equations. Importance of magnetostatic interactions working between adjacent dots has been elucidated

  12. Via fill properties of organic BARCs in dual-damascene application

    Science.gov (United States)

    Huang, Runhui

    2004-05-01

    With the introduction of copper as the interconnect metal, the Dual Damascene (DD) process has been integrated into integrated circuit (IC) device fabrication. The DD process utilizes organic bottom anti-reflective coatings (BARCs) not only to eliminate the thin film interference effects but also to act as via fill materials. However, three serious processing problems are encountered with organic BARCs. One is the formation of voids, which are trapped gas bubbles (evaporating solvent, byproduct of the curing reaction and air) inside the vias. Another problem is non-uniform BARC layer thickness in different via pitch areas. The third problem is the formation of fences during plasma etch. Fences are formed from materials that are removed by plasma and subsequently deposited on the sidewall surrounding the via openings during the etching process. Voids can cause variations in BARC top thickness, optical properties, via fill percentage, and plasma etch rate. This study focuses on the factors that influence the formation of voids and addresses the ways to eliminate them by optimizing the compositions of formulations and the processing conditions. Effects of molecular weight of the polymer, nature of the crosslinker, additives, and bake temperature were examined. The molecular weight of the polymer is one of the important factors that needs to be controlled carefully. Polymers with high molecular weights tend to trap voids inside the vias. Low molecular weight polymers have low Tg and low viscosity, which enables good thermal flow so that the BARC can fill vias easily without voids. Several kinds of crosslinkers were investigated in this study. When used with the same polymer system, formulations with different crosslinkers show varying results that affect planar fill, sidewall coverage, and, in some cases, voids. Additives also can change via fill behavior dramatically, and choosing the right additive will improve the via fill property. Processing conditions such as

  13. Processing of R-Ba-Cu-O superconductors

    International Nuclear Information System (INIS)

    Wu, H.

    1998-01-01

    Precipitation processes were developed to introduce second phases as flux pinning centers in Gd-Ba-Cu-O and Nd-Ba-Cu-O superconductors. In Gd-Ba-Cu-O, precipitation is caused by the decrease of the upper solubility limit of Gd 1+x Ba 2-x Cu 3 O 7 solid solution (Gd123ss) in low oxygen partial pressure. Processing of supersaturated Gd 1.2 Ba 1.8 Cu 3 O 7 in low oxygen partial pressure can produce dispersed second phases. Gd211 is formed as a separate phase while extensive Gd124 type stacking fault is formed instead of a separate CuO phase. As a result of the precipitation reaction, the transition temperature and critical current density are increased. In Nd-Ba-Cu-O, precipitation is caused by the decrease of the lower solubility limit of Nd 1+x Ba 2-x Cu 3 O 7 solid solution (Nd123ss) in oxygen. DTA results reveal the relative stability of Nd123ss in different oxygen partial pressures. In 1 bar oxygen partial pressure, Nd123ss with x = 0.1 is the most stable phase. In lower oxygen partial pressures, the most stable composition shifts towards the stoichiometric composition. The relative stability changes faster with decreasing oxygen partial pressure. Therefore, processing in oxygen and air tends to produce broad superconducting transitions but sharp transitions can be achieved in 0.01 bar and 0.001 bar oxygen partial pressures. While the lower solubility limits in 0.01 bar and 0.001 bar oxygen partial pressures remain at x = 0.00, the solubility limits in oxygen and air show a narrowing with decreasing temperature. Because of the narrowing of the solubility range in oxygen, oxygen annealing of Nd123 initially processed in low oxygen partial pressures will result in precipitation of second phases. The equilibrium second phase is BaCuO 2 for temperature above 608 C, and at lower temperatures the equilibrium second phases are Ba 2 CuO 3.3 and Ba 2 Cu 3 O 5+y . However, annealing at low temperature may produce a fine metastable transition phase. A coherent intermediate

  14. Study on the Effects of Corrosion Inhibitor According to the Functional Groups for Cu Chemical Mechanical Polishing in Neutral Environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Won; Kim, Jae Jeong [Institute of Chemical Process, Seoul National University, Seoul (Korea, Republic of)

    2015-08-15

    As the aluminum (Al) metallization process was replaced with copper (Cu), the damascene process was introduced, which required the planarization step to eliminate over-deposited Cu with Chemical Mechanical Polishing (CMP) process. In this study, the verification of the corrosion inhibitors, one of the Cu CMP slurry components, was conducted to find out the tendency regarding the carboxyl and amino functional group in neutral environment. Through the results of etch rate, removal rate, and chemical ability of corrosion inhibitors based on 1H-1,2,4-triazole as the base corrosion inhibitor, while the amine functional group presents high Cu etching ability, carboxyl functional group shows lower Cu etching ability than base-corrosion inhibitor which means that it increases passivation effect by making strong passivation layer. It implies that the corrosion inhibitor with amine functional group was proper to apply for 1st Cu CMP slurry owing to the high etch rate and with carboxyl functional group was favorable for the 2nd Cu CMP slurry due to the high Cu removal rate/dissolution rate ratio.

  15. Category Cued Recall Evokes a Generate-Recognize Retrieval Process

    Science.gov (United States)

    Hunt, R. Reed; Smith, Rebekah E.; Toth, Jeffrey P.

    2016-01-01

    The experiments reported here were designed to replicate and extend McCabe, Roediger, and Karpicke's (2011) finding that retrieval in category cued recall involves both controlled and automatic processes. The extension entailed identifying whether distinctive encoding affected 1 or both of these 2 processes. The first experiment successfully…

  16. ECAE-processed Cu-Nb and Cu-Ag nanocomposite wires for pulse magnet applications

    International Nuclear Information System (INIS)

    Edgecumbe Summers, T.S.; Walsh, R.P.; Pernambuco-Wise, P.

    1997-01-01

    Cu-Nb and Cu-Ag nanocomposites have recently become of interest to pulse magnet designers because of their unusual combination of high strength with reasonable conductivity. In the as-cast condition, these conductors consist of two phases, one of almost pure Nb (or Ag) and the other almost pure Cu. When these castings are cold worked as in a wire-drawing operation for example, the two phases are drawn into very fine filaments which produce considerable strengthening without an unacceptable decrease in conductivity. Unfortunately, any increase in strength with operations such as wire drawing is accompanied by a reduction in the cross section of the billet, and thus far, no wires with strengths on the order of 1.5 GPa or more have been produced with cross sections large enough to be useful in magnet applications. Equal Channel Angular Extrusion (ECAE) is an innovative technique which allows for the refinement of the as-cast ingot structure without a reduction in the cross sectional dimensions. Samples processed by the ECAE technique prior to wire drawing should be stronger at a given wire diameter than those processed by wire drawing alone. The tensile properties of wire-drawn Cu-18%Nb and Cu-25%Ag both with and without prior ECAE processing were tested and compared at both room temperature and 77K. All samples were found to have resistivities consistent with their strengths, and the strengths of the ECAE-processed wires were significantly higher than their as-cast and drawn counterparts. Therefore, with ECAE processing prior to wire drawing, it appears to be possible to make high-strength conductors with adequately large cross sections for pulse magnets

  17. Microstructure, impurity and metal cap effects on Cu electromigration

    Energy Technology Data Exchange (ETDEWEB)

    Hu, C.-K.; Gignac, L. G.; Ohm, J.; Breslin, C. M.; Huang, E.; Bonilla, G.; Liniger, E.; Rosenberg, R. [IBM T. J. Watson Research Center, Yorktown Heights, NY 10598 (United States); Choi, S.; Simon, A. H. [IBM Microelectronic Division, Hopewell Junction, NY 12533 (United States)

    2014-06-19

    Electromigration (EM) lifetimes and void growth of pure Cu, Cu(Mn) alloy, and pure Cu damascene lines with a CoWP cap were measured as a function of grain structure (bamboo, near bamboo, and polycrystalline) and sample temperature. The bamboo grains in a bamboo-polycrystalline grained line play the key role in reducing Cu mass flow. The variation in Cu grain size distribution among the wafers was achieved by varying the metal line height and wafer annealing process step after electroplating Cu and before or after chemical mechanical polishing. The Cu grain size was found to have a large impact on Cu EM lifetime and activation energy, especially for the lines capped with CoWP. The EM activation energy for pure Cu with a CoWP cap from near-bamboo, bamboo-polycrystalline, mostly polycrystalline to polycrystalline only line grain structures was reduced from 2.2 ± 0.2 eV, to 1.7 ± 0.1 eV, to 1.5 ± 0.1 eV, to 0.72 ± 0.05 eV, respectively. The effect of Mn in Cu grain boundary diffusion was found to be dependent on Mn concentration in Cu. The depletion of Cu at the cathode end of the Cu(Mn) line is preceded by an incubation period. Unlike pure Cu lines with void growth at the cathode end and hillocks at the anode end of the line, the hillocks grew at a starting position roughly equal to the Blech critical length from the cathode end of the Cu(Mn) polycrystalline line. The effectiveness of Mn on Cu grain boundary migration can also be qualitatively accounted for by a simple trapping model. The free migration of Cu atoms at grain boundaries is reduced by the presence of Mn due to Cu-solute binding. A large binding energy of 0.5 ± 0.1 eV was observed.

  18. Production and processing of Cu-Cr-Nb alloys

    International Nuclear Information System (INIS)

    Ellis, D.L.; Michal, G.M.; Orth, N.W.

    1990-01-01

    A new Cu-based alloy possessing high strength, high conductivity, and good stability at elevated temperatures was recently produced. This paper details the melting of the master alloys, production of rapidly solidified ribbon, and processing of the ribbon to sheet by hot pressing and hot rolling

  19. Production and processing of Cu-Cr-Nb alloys

    Science.gov (United States)

    Ellis, David L.; Michal, Gary M.; Orth, Norman W.

    1990-01-01

    A new Cu-based alloy possessing high strength, high conductivity, and good stability at elevated temperatures was recently produced. This paper details the melting of the master alloys, production of rapidly solidified ribbon, and processing of the ribbon to sheet by hot pressing and hot rolling.

  20. Kinetic process of mechanical alloying in Fe50Cu50

    DEFF Research Database (Denmark)

    Huang, J.Y.; Jiang, Jianzhong; Yasuda, H.

    1998-01-01

    It is shown that mechanical alloying in the immiscible Fe-Cu system is governed by the atomic shear event and shear-induced diffusion process. We found that an alpha-to-gamma phase transformation, as evidenced by the Nishiyama-Wasserman orientation relationship, occurs by simultaneous shearing...

  1. Ultrafine grained Cu processed by compression with oscillatory torsion

    OpenAIRE

    K. Rodak

    2007-01-01

    Purpose: The aim of this work is a study of Cu microstructure after severe plastic deformation process by usingcompression with oscillatory torsion test.Design/methodology/approach: Cu samples were deformed at torsion frequency (f) changed from 0 Hz(compression) to 1.8 Hz under a constant torsion angle (α) ≈8° and compression speed (v)=0.1mm/s. Structuralinvestigations were conducted by using light microscopy (LM) and transmission electron microscopy (TEM).Findings: The structural analysis ma...

  2. Infrared processed Cu composites reinforced with WC particles

    International Nuclear Information System (INIS)

    Deshpande, P.K.; Li, J.H.; Lin, R.Y.

    2006-01-01

    Copper matrix composites with WC particle reinforcements have been prepared with an innovative infrared infiltration technique. The volume content of the reinforcement particles in the composite is about 53%. The relative composite density of as high as 99.9% has been obtained with this process. The electric conductivity of composites prepared in this study as determined by a four-point probe method, is similar to commercially available Cu/W composites containing 52 vol% tungsten. Microhardness, microstructure and wear resistance of the composites were also determined. The microstructure of Cu/WC composite reveals excellent wetting between the two constituent phases, WC and copper. The microhardness values of all completely infiltrated Cu/WC composites were in the range of 360-370 HV which is significantly higher than the microhardness of pure copper, 65 HV. Wear resistance of the composites was determined with a pin on disk wear test technique. The wear test results show that composites prepared in this study performed much better than those commercially available Cu/W composites by more than two-fold against silicon carbide abrasive disks

  3. Theories of transporting processes of Cu in Jiaozhou Bay

    Science.gov (United States)

    Yang, Dongfang; Su, Chunhua; Zhu, Sixi; Wu, Yunjie; Zhou, Wei

    2018-02-01

    Many marine bays have been polluted along with the rapid development of industry and population size, and understanding the transporting progresses of pollutants is essential to pollution control. In order to better understanding the transporting progresses of pollutants in marine, this paper carried on a comprehensive research of the theories of transporting processes of Cu in Jiaozhou Bay. Results showed that the transporting processes of Cu in this bay could be summarized into seven key theories including homogeneous theory, environmental dynamic theory, horizontal loss theory, source to waters transporting theory, sedimentation transporting theory, migration trend theory and vertical transporting theory, respectively. These theories helpful to better understand the migration progress of pollutants in marine bay.

  4. Evolution process of the synthesis of TiC in the Cu-Ti-C system

    International Nuclear Information System (INIS)

    Liang, Y.H.; Wang, H.Y.; Yang, Y.F.; Wang, Y.Y.; Jiang, Q.C.

    2008-01-01

    The evolution process of TiC formation in the 20 wt.% Cu-Ti-C powder mixtures was studied by using differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The Ti x Cu y compounds (Ti 2 Cu, TiCu, Ti 3 Cu 4 and TiCu 4 ) formed initially via solid-state diffusion reactions between Cu and Ti particles; and then Ti 2 Cu and TiCu can form a Cu-Ti eutectic liquids at about 1233 K. The unreacted Ti and C particles dissolved into the Cu-Ti liquids and led to the formation of Cu-Ti-C ternary liquids; subsequently, TiC particulates precipitated out of the saturated liquids. At the same time, also the formation of Ti 2 Cu occurred at the interface between the Cu-Ti liquids and the unreacted Ti particles. As the temperature increased further, the Ti 2 Cu melted and more Cu-Ti liquids formed; and then C particles continuously dissolved into the Cu-Ti-C liquids and TiC particulates gradually precipitated out of the saturated liquids

  5. Cytotoxic and genotoxic studies of essential oil from Rosa damascene Mill., Kashan, Iran.

    Science.gov (United States)

    Shokrzadeh, Mohammad; Habibi, Emran; Modanloo, Mona

    2017-08-01

    Aim Rosa damascene Mill. belongs to the family of Roseaceae and its essential oil is produced in large amounts in Iran. The wide application of rose oil has raised questions about potential adverse health effects. We have investigated cytotoxic activity and genotoxic effects of Rosa oil from Kashan, Iran. Methods The cytotoxic effect and IC50 of the essential oil on the cell lines was studied followed by MTT assay. In this assay mitochondrial oxidoreductase enzymes with reducing the tetrazolium dye MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) reflect the number of viable cells. Genotoxic effect of the oil was evaluated by micronucleus assay by evaluating produced micronuclei due to cytogenetic damage in binucleated lymphocytes. Results The results showed that essential oil significantly had cytotoxic and genotoxic effects at doses over 10µg/mL (pessential oil of Rose showed lower IC50 in cancer cell line (A549) in comparison with the normal cell line (NIH3T3). Conclusion Cytotoxic and genotoxic properties of essential oil of Rose in Kashan, Iran, are safe at a dose of 10µg/mL. Also, a good cytotoxic effect was shown and could be introduced as an anticancer compound. Further studies are needed with regard to anti-cancer effects of Rose essential oil. Copyright© by the Medical Assotiation of Zenica-Doboj Canton.

  6. Microstructure characterization of Cu processed by compression with oscillatory torsion

    International Nuclear Information System (INIS)

    Rodak, K.; Pawlicki, J.

    2014-01-01

    High purity Cu (99.9%) was subjected to severe plastic deformation up to a total effective strain ε ft = 130 through compression with the oscillatory torsion method at room temperature. This method produces an ultrafine grain microstructure. The microstructure evolution was investigated with respect to the value of the total effective strain using a scanning electron microscope with an electron-backscattered diffraction technique and a scanning transmission electron microscope. The results of the structural analyses show that increasing ε ft from 2 to 50 causes progress in the grain refinement. A quantitative study of the microstructure parameters, such as fraction of high angle boundaries, grain and subgrain diameter, and the area fraction of grains up to 1 μm, shows that deformation at ε ft = 45 guaranteed the best conditions for refining the microstructure of Cu. Using high values of ε ft in the range 60 to 130 restricts grain refinement because intensive recovery begins to dominate in the microstructure. - Highlights: • Cu was processed by SPD metodto an effective strain 130. • The microstructure evolution has been investigated. • The method allows to produce an ultrafine grain microstructure

  7. Microstructure characterization of Cu processed by compression with oscillatory torsion

    Energy Technology Data Exchange (ETDEWEB)

    Rodak, K., E-mail: kinga.rodak@polsl.pl [Institute of Materials Science, Silesian University of Technology, Krasińskiego 8, 40-019 Katowice (Poland); Pawlicki, J., E-mail: jacek.pawlicki@polsl.pl [Department of Automotive Vehicle Construction, Silesian University of Technology, Krasińskiego 8, 40–019 Katowice (Poland)

    2014-08-15

    High purity Cu (99.9%) was subjected to severe plastic deformation up to a total effective strain ε{sub ft} = 130 through compression with the oscillatory torsion method at room temperature. This method produces an ultrafine grain microstructure. The microstructure evolution was investigated with respect to the value of the total effective strain using a scanning electron microscope with an electron-backscattered diffraction technique and a scanning transmission electron microscope. The results of the structural analyses show that increasing ε{sub ft} from 2 to 50 causes progress in the grain refinement. A quantitative study of the microstructure parameters, such as fraction of high angle boundaries, grain and subgrain diameter, and the area fraction of grains up to 1 μm, shows that deformation at ε{sub ft} = 45 guaranteed the best conditions for refining the microstructure of Cu. Using high values of ε{sub ft} in the range 60 to 130 restricts grain refinement because intensive recovery begins to dominate in the microstructure. - Highlights: • Cu was processed by SPD metodto an effective strain 130. • The microstructure evolution has been investigated. • The method allows to produce an ultrafine grain microstructure.

  8. Aromatherapy with Rosa Damascenes in Apnea, Bradycardia and Spo2 of Preterm Infants; a Randomized Clinical Trial

    Directory of Open Access Journals (Sweden)

    Saeideh Aghagoli

    2016-06-01

    Full Text Available Background  Apnea is one of the most common problems in preterm neonates. This study aimed to evaluate the effectiveness of aromatherapy on the reduction of apnea, bradycardia, and Pulse Oximetry (SPO2 in premature infants. Materials and Methods In a clinical trial study, 60 preterm neonates randomly divided in two groups and exposed to aromatherapy with Rosa damascenes distillate or distilled water beside the routine treatment. In experimental group, two drops of 10% Rosa damascenes distillate was dropped on the pad eye in second day of birth at 6 Am. The intervention was repeated in 9 AM, 12 Am, 15 PM and 18 PM hours. A same condition applied for control group and distilled water was dropped on the pad eye. The number of apnea attacks, bradycardia and decrease in SpO2 compared between two groups using chi-square test, independent t-test and repeated measure test. Results The overall apnea attacks, bradycardia, and SPO2 in tree studied days were lower in intervention group than control group (0.47±0.13 vs. 2.6±0.41, 0.47±0.13 vs. 2.56±0.41 and 0.70±0.17 vs. 2.77±0.21, respectively. In addition, the repeated measurement test showed that the mean number of apnea attacks, decrease in heart pulse rate, and decrease in SpO2 was statistically lower in intervention group with aromatherapy than controls in first, second, third and sum of three days (P< 0.05. Conclusion Aromatherapy with Rosa damascenes distillate can reduce more and speedy the occurrence of apnea attacks, bradycardia and SPO2 in premature infants, along with other routine treatment.

  9. Adsorption Behavior of TBPS in the Process of Cu Electrodeposition on an Au Film.

    Science.gov (United States)

    Chen, Liang-Huei; Liu, Yung-Fang; Krug, Klaus; Lee, Yuh-Lang

    2018-05-15

    The adsorption behavior of an Cu electroplating additive, 3,3 thiobis-(1-propanesulfonic acid sodium salt) (TBPS) in a process of Cu deposition onto a single crystalline Au(111) surface is studied by an in-situ Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS). The SEIRAS spectra of the TBPS adlayer on a Cu film is investigated first and compared to that on an Au film. These results are utilized to evaluate the characteristics of TBPS adlayer on the electrode surface during the Cu deposition and stripping processes. The results show that the SEIRAS spectra of TBPS adsorbed on the Cu film resembles closely to that on the Au film, and the most pronounced peaks are symmetric S-O (ss-SO) and asymmetric S-O (as-SO) stretching modes. However, the as-SO band is sharper with a higher intensity on the Cu film. Since the ss-SO and as-SO peaks correspond to the molecular with upright and lie-down orientations, respectively, it implies that the TBPS molecules have higher ratio of lie-down orientation on the Cu film. In the Cu electrodeposition process, the cyclic voltammetry (CV) result shows that the presence of the TBPS in the HClO 4 solution can decrease the inhibition effect of HClO 4 to the Cu deposition. For the spectra measured at various potential during cathodic and anodic sweeping, an obvious change of the spectra occurs at ca. 0.6 V, the initiation of Cu underpotential deposition (Cu-UPD). For potentials higher and lower than 0.6 V, the spectra are similar, respectively, to those measured for the Au and Cu films. This result indicates that the TBPS molecules originally adsorbing on the Au film transfer to the surface of deposited Cu layer. This inference is also confirmed by the variation in wavenumber and peak intensity of ss-SO and as-SO peaks during the potential sweeping.

  10. Simple solution-processed CuOX as anode buffer layer for efficient organic solar cells

    International Nuclear Information System (INIS)

    Shen, Wenfei; Yang, Chunpeng; Bao, Xichang; Sun, Liang; Wang, Ning; Tang, Jianguo; Chen, Weichao; Yang, Renqiang

    2015-01-01

    Graphical abstract: - Highlights: • Simple solution-processed CuO X hole transport layer for efficient organic solar cell. • Good photovoltaic performances as hole transport layer in OSCs with P3HT and PBDTTT-C as donor materials. • The device with CuO X as hole transport layer shows great improved stability compared with that of device with PEDOT:PSS as hole transport layer. - Abstract: A simple, solution-processed ultrathin CuO X anode buffer layer was fabricated for high performance organic solar cells (OSCs). XPS measurement demonstrated that the CuO X was the composite of CuO and Cu 2 O. The CuO X modified ITO glass exhibit a better surface contact with the active layer. The photovoltaic performance of the devices with CuO X layer was optimized by varying the thickness of CuO X films through changing solution concentration. With P3HT:PC 61 BM as the active layer, we demonstrated an enhanced PCE of 4.14% with CuO X anode buffer layer, compared with that of PEDOT:PSS layer. The CuO X layer also exhibits efficient photovoltaic performance in devices with PBDTTT-C:PC 71 BM as the active layer. The long-term stability of CuO X device is better than that of PEDOT:PSS device. The results indicate that the easy solution-processed CuO X film can act as an efficient anode buffer layer for high-efficiency OSCs

  11. W-Cu gradient materials - processing, properties and application possibilities

    International Nuclear Information System (INIS)

    Joensson, M.; Kieback, B.

    2001-01-01

    The functionally graded material (FGM) of tungsten with its high thermal and mechanical resistance and copper with its very high thermal and electrical conductivity and ductility expands the application fields of this material in the direction of extreme demands such as plasma facing components in fusion reactors. The PM-production of W-Cu-gradients recommends itself because of the possibility to form the gradient by the mixing of powder components, but is also demanding because of the differences in their sintering behavior and thermal expansions. W-Gu-gradient samples of different concentration profiles have been formed in layers by powder stacking in a die and continuously by centrifugal powder forming. The consolidation routes were determined by the concentration areas of the gradients and encompass liquid phase sintering, pressure assisted solid phase sintering and the application of coated Tungsten powder and sintering additives. The microstructure and the concentration profiles of the samples have been investigated metaliographically and by EDX. The influence of processing and the gradient profile of the properties have been characterized by TRS and the investigation of residual thermal stresses by neutron diffraction. (author)

  12. Processing and characterization of composite CuO/CuO/Cu-CGO obtained by a chemical synthesis route in one step

    International Nuclear Information System (INIS)

    Sousa, A.R.O. de; Menezes, A.J.; Souza, G.S.; Lima, C.G.M. de; Souza, G.S.; Dutra, R.P.S.; Macedo, D.A.

    2016-01-01

    This paper deals with the processing and characterization of composite CuO / ceria doped with 10 mol% gadolinia (CuO-Ce0,9Gd0,1O1,95) obtained by a chemical synthesis route in one step. It was varied CuO content at 40, 50 and 60% by weight, resulting in resin precursor, which was mixed with the CGO and then heat treated at 350 ° C and subsequently calcined at 1050 deg C. The particulate materials were characterized by X-ray diffractometry using powders, it was possible to synthesize and deposit, by serigraphy, films of the anodes of the three compositions CGO electrolyte. The technique of impedance spectroscopy allowed the analysis of the electrical properties of the material, as well as the understanding of their behavior when subjected to different atmospheres of hydrogen and methane. (author)

  13. Gradient nanostructured surface of a Cu plate processed by incremental frictional sliding

    DEFF Research Database (Denmark)

    Hong, Chuanshi; Huang, Xiaoxu; Hansen, Niels

    2015-01-01

    The flat surface of a Cu plate was processed by incremental frictional sliding at liquid nitrogen temperature. The surface treatment results in a hardened gradient surface layer as thick as 1 mm in the Cu plate, which contains a nanostructured layer on the top with a boundary spacing of the order...

  14. Effects of processing parameters on Be/CuCrZr joining

    International Nuclear Information System (INIS)

    Park, Jeong-Yong; Lee, Jung-Suk; Choi, Byung-Kwon; Park, Sang-Yun; Hong, Bong Guen; Jeong, Yong Hwan; Jung, Ki-Jung

    2007-01-01

    A joining of Be/CuCrZr has been considered as the key technology for the fabrication of the ITER first wall. Among the joining methods, Hot isostatic pressing (HIP), which is one of the diffusion bonding methods, is the most feasible method to join the Be and CuCrZr alloy. In the HIP joining of Be and CuCrZr, the interlayer was used to prevent the formation of brittle intermetallic compounds in the interface. Therefore, it is crucial to select a suitable interlayer for a joining of Be and CuCrZr. On the other hand, the diffusion between Be and CuCrZr would be enhanced with an increase of the HIP joining temperature, thereby increasing the joint strength. However, the HIP joining temperature is limited by the mechanical properties of CuCrZr. During the fabrication process of the ITER first wall, CuCrZr is subjected to several thermal cycles including a solution annealing, a cooling and an aging. The HIP joining of Be and CuCrZr corresponds to the aging of CuCrZr. The HIP joining at a higher temperature would cause a degradation of the mechanical properties of CuCrZr by an overaging effect although it is preferable for an improvement of the joint strength. In this study, the effect of the cooling rate on the mechanical properties of aged CuCrZr was investigated to find the maximum HIP temperature without a degradation of the mechanical properties of CuCrZr

  15. One-step electrodeposition process of CuInSe2: Deposition time effect

    Indian Academy of Sciences (India)

    Administrator

    CuInSe2 thin films were prepared by one-step electrodeposition process using a simplified two- electrodes system. ... homojunctions or heterojunctions (Rincon et al 1983). Efficiency of ... deposition times onto indium thin oxide (ITO)-covered.

  16. Uncovering the Problem-Solving Process: Cued Retrospective Reporting Versus Concurrent and Retrospective Reporting

    NARCIS (Netherlands)

    Van Gog, Tamara; Paas, Fred; Van Merriënboer, Jeroen; Witte, P.

    2007-01-01

    This study investigated the amounts of problem-solving process information ("action," "why," "how," and "metacognitive") elicited by means of concurrent, retrospective, and cued retrospective reporting. In a within-participants design, 26 participants completed electrical circuit troubleshooting

  17. Effect of annealing process on the heterostructure CuO/Cu2O as a highly efficient photocathode for photoelectrochemical water reduction

    Science.gov (United States)

    Du, Fan; Chen, Qing-Yun; Wang, Yun-Hai

    2017-05-01

    CuO/Cu2O photocathodes were successfully prepared via simply annealing the electrodeposited Cu2O on fluoride doped tin oxide (FTO) substrate. They were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscope (TEM), UV-vis absorption spectra and X-ray photoelectron spectroscopy (XPS). The results showed that the heterojunction of CuO/Cu2O was formed during the annealing process and presented the nature of p-type semiconductor. The photocurrent density and photoelectrochemical (PEC) stability of the p-type heterostructure CuO/Cu2O photocathode was improved greatly compared with the pure Cu2O, which was greatly affected by annealing time and temperature. The highest photo current density of -0.451 mA/cm2 and highest stability was obtained via annealing at 650 °C for 15 min (at -0.3 V vs. Ag/AgCl), which gave a remarkable improvement than the as-deposited Cu2O (-0.08 mA/cm2). This suggested that the CuO/Cu2O heterojunction facilitated the electron-hole pair separation and improved the photocathode's current and stability.

  18. Flux pinning enhancement by Y2BaCuO5 inclusions in melt processed YBaCuO superconductors

    International Nuclear Information System (INIS)

    Murakami, M.

    1991-01-01

    While nonsuperconducting particles are known to serve as effective pinning centers in conventional superconductors, their effect in high T c superconductors is still controversial. In this paper, the author gives evidence that nonsuperconducting Y 2 BaCuO 5 (21 1) inclusions can act as pinning centers in melt processed YBaCuO superconductors even when their size is orders of magnitude larger than the coherence length. In such a case, the interface provides pinning. Theoretical estimates based on direct summations agree well with the experimental results. The applications of direct summation for obtaining the bulk pinning force is justified by direct observation of the FLL (flux line lattice), where the FLL has no long range order and the fluxoids are pinned by 211 inclusions

  19. Homogeneous (Cu, Ni)6Sn5 intermetallic compound joints rapidly formed in asymmetrical Ni/Sn/Cu system using ultrasound-induced transient liquid phase soldering process.

    Science.gov (United States)

    Li, Z L; Dong, H J; Song, X G; Zhao, H Y; Tian, H; Liu, J H; Feng, J C; Yan, J C

    2018-04-01

    Homogeneous (Cu, Ni) 6 Sn 5 intermetallic compound (IMC) joints were rapidly formed in asymmetrical Ni/Sn/Cu system by an ultrasound-induced transient liquid phase (TLP) soldering process. In the traditional TLP soldering process, the intermetallic joints formed in Ni/Sn/Cu system consisted of major (Cu, Ni) 6 Sn 5 and minor Cu 3 Sn IMCs, and the grain morphology of (Cu, Ni) 6 Sn 5 IMCs subsequently exhibited fine rounded, needlelike and coarse rounded shapes from the Ni side to the Cu side, which was highly in accordance with the Ni concentration gradient across the joints. However, in the ultrasound-induced TLP soldering process, the intermetallic joints formed in Ni/Sn/Cu system only consisted of the (Cu, Ni) 6 Sn 5 IMCs which exhibited an uniform grain morphology of rounded shape with a remarkably narrowed Ni concentration gradient. The ultrasound-induced homogeneous intermetallic joints exhibited higher shear strength (61.6 MPa) than the traditional heterogeneous intermetallic joints (49.8 MPa). Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Synthesis and characterization of CuO flower-nanostructure processing by a domestic hydrothermal microwave

    International Nuclear Information System (INIS)

    Volanti, D.P.; Keyson, D.; Cavalcante, L.S.; Simoes, A.Z.; Joya, M.R.; Longo, E.; Varela, J.A.; Pizani, P.S.; Souza, A.G.

    2008-01-01

    The synthesis and characterization of CuO flower-nanostructure processed in domestic hydrothermal microwave oven was presented. Phase analysis was carried out using X-ray diffraction (XRD) and micro-Raman scattering (MRS) and the results confirmed the CuO flower-nanostructure as a single-phase. The field-emission scanning electron microscopy (FEG-SEM) was used to estimate the average spheres diameter while transmission electron microscope (TEM) to observe the thorn of the flower-nanostructures. The mechanism of CuO flower-nanostructures formation is proposed and explained

  1. Synthesis and characterization of CuO flower-nanostructure processing by a domestic hydrothermal microwave

    Energy Technology Data Exchange (ETDEWEB)

    Volanti, D.P. [Laboratorio Interdisciplinar em Ceramica, Departamento de Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP (Brazil); Keyson, D. [Laboratorio de Ensino de Ciencias e Laboratorio de Combustiveis e Materiais, Departamento de Quimica, Universidade Federal da Paraiba, 58051-900 Joao Pessoa, PB (Brazil); Cavalcante, L.S. [Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, Universidade Federal de Sao Carlos, P.O. Box 676, 13565-905 Sao Carlos, SP (Brazil)], E-mail: laeciosc@bol.com.br; Simoes, A.Z. [Laboratorio Interdisciplinar em Ceramica, Departamento de Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP (Brazil); Joya, M.R. [Departamento de Fisica, Universidade Federal de Sao Carlos, P.O. Box 676, 13565-905 Sao Carlos, SP (Brazil); Longo, E.; Varela, J.A. [Laboratorio Interdisciplinar em Ceramica, Departamento de Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP (Brazil); Pizani, P.S. [Departamento de Fisica, Universidade Federal de Sao Carlos, P.O. Box 676, 13565-905 Sao Carlos, SP (Brazil); Souza, A.G. [Laboratorio de Ensino de Ciencias e Laboratorio de Combustiveis e Materiais, Departamento de Quimica, Universidade Federal da Paraiba, 58051-900 Joao Pessoa, PB (Brazil)

    2008-07-14

    The synthesis and characterization of CuO flower-nanostructure processed in domestic hydrothermal microwave oven was presented. Phase analysis was carried out using X-ray diffraction (XRD) and micro-Raman scattering (MRS) and the results confirmed the CuO flower-nanostructure as a single-phase. The field-emission scanning electron microscopy (FEG-SEM) was used to estimate the average spheres diameter while transmission electron microscope (TEM) to observe the thorn of the flower-nanostructures. The mechanism of CuO flower-nanostructures formation is proposed and explained.

  2. Uncovering the problem-solving process: cued retrospective reporting versus concurrent and retrospective reporting.

    Science.gov (United States)

    van Gog, Tamara; Paas, Fred; van Merriënboer, Jeroen J G; Witte, Puk

    2005-12-01

    This study investigated the amounts of problem-solving process information ("action," "why," "how," and "metacognitive") elicited by means of concurrent, retrospective, and cued retrospective reporting. In a within-participants design, 26 participants completed electrical circuit troubleshooting tasks under different reporting conditions. The method of cued retrospective reporting used the original computer-based task and a superimposed record of the participant's eye fixations and mouse-keyboard operations as a cue for retrospection. Cued retrospective reporting (with the exception of why information) and concurrent reporting (with the exception of metacognitive information) resulted in a higher number of codes on the different types of information than did retrospective reporting.

  3. Alleviation of process-induced cracking of the antireflection TiN coating (ARC-TiN) in Al-Cu and Al-Cu-Si films

    CERN Document Server

    Peng, Y C; Yang, Y R; Hsieh, W Y; Hsieh, Y F

    1999-01-01

    The alleviation of cracking of the TiN-ARC layer on Al-Cu and Al-Cu-Si films after the development process has been achieved. For the TiN-ARC/Al-Cu system, the stress-induced defects decreased with increasing TiN-ARC layer thickness. In contrast, for the TiN-ARC/Al-Cu-Si system, Si nodules formed during cooling, thereby inducing poor coverage with high aspect-ratio holes. As a result, the photoresist developer penetrated through the films. Chemical vapor deposition of TiN-ARC or predeposition of a Ti Interposing layer was used to eliminate the formation of Si nodules.

  4. 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

  5. Uncovering the Problem-Solving Process: Cued Retrospective Reporting Versus Concurrent and Retrospective Reporting

    OpenAIRE

    Van Gog, Tamara; Paas, Fred; Van Merriënboer, Jeroen; Witte, P.

    2007-01-01

    This study investigated the amounts of problem-solving process information ("action," "why," "how," and "metacognitive") elicited by means of concurrent, retrospective, and cued retrospective reporting. In a within-participants design, 26 participants completed electrical circuit troubleshooting tasks under different reporting conditions. The method of cued retrospective reporting used the original computer-based task and a superimposed record of the participant's eye fixations and mouse-keyb...

  6. The influence of precursor Cu content and two-stage processing conditions on the microstructure of Cu{sub 2}ZnSnSe{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Márquez-Prieto, J., E-mail: jose.prieto@northumbria.ac.uk [Northumbria Photovoltaic Application Centre, Faculty of Engineering and Environment, Northumbria University, Ellison Building, Newcastle upon Tyne NE1 8ST (United Kingdom); Ren, Y. [Ångström Solar Center, Solid State Electronics, Uppsala University, Uppsala 751 21 (Sweden); Miles, R.W.; Pearsall, N.; Forbes, I. [Northumbria Photovoltaic Application Centre, Faculty of Engineering and Environment, Northumbria University, Ellison Building, Newcastle upon Tyne NE1 8ST (United Kingdom)

    2015-05-01

    This paper reports the influence of processing temperature on the microstructure of Cu{sub 2}ZnSnSe{sub 4} (CZTSe) absorber layers for temperatures between 380 and 550 °C produced using a 2-stage process. X-ray diffraction analysis showed the formation of Cu{sub 2}ZnSnSe{sub 4} over this temperatures range. The Williamson-Hall method was used for microstructural analysis of the CZTSe absorbers, and this showed a progressive decrease of the micro-strain of the CZTSe with increasing selenisation temperature. The influence of precursor Cu content on the microstructure of the CZTSe was also studied. An increase of Cu content in the precursor is correlated to an increase in grain size and a decrease in micro-strain. Raman measurements show an asymmetrical broadening towards lower energies of the main 197 cm{sup −1} mode for Cu-poor compositions. This study provides an insight into the dependency of the crystallinity of CZTSe on composition and synthesis temperature. - Highlights: • We fabricate Cu{sub 2}ZnSnSe{sub 4} thin films by sputtering and post-reactive annealing. • The micro-strain of Cu{sub 2}ZnSnSe{sub 4} increases when Cu content decreases. • The micro-strain of Cu{sub 2}ZnSnSe{sub 4} decreases with increasing processing temperature. • The defect concentration of Cu{sub 2}ZnSnSe{sub 4} increases when Cu content decreases.

  7. Direct, CMOS In-Line Process Flow Compatible, Sub 100 °C Cu-Cu Thermocompression Bonding Using Stress Engineering

    Science.gov (United States)

    Panigrahi, Asisa Kumar; Ghosh, Tamal; Kumar, C. Hemanth; Singh, Shiv Govind; Vanjari, Siva Rama Krishna

    2018-05-01

    Diffusion of atoms across the boundary between two bonding layers is the key for achieving excellent thermocompression Wafer on Wafer bonding. In this paper, we demonstrate a novel mechanism to increase the diffusion across the bonding interface and also shows the CMOS in-line process flow compatible Sub 100 °C Cu-Cu bonding which is devoid of Cu surface treatment prior to bonding. The stress in sputtered Cu thin films was engineered by adjusting the Argon in-let pressure in such a way that one film had a compressive stress while the other film had tensile stress. Due to this stress gradient, a nominal pressure (2 kN) and temperature (75 °C) was enough to achieve a good quality thermocompression bonding having a bond strength of 149 MPa and very low specific contact resistance of 1.5 × 10-8 Ω-cm2. These excellent mechanical and electrical properties are resultant of a high quality Cu-Cu bonding having grain growth between the Cu films across the boundary and extended throughout the bonded region as revealed by Cross-sectional Transmission Electron Microscopy. In addition, reliability assessment of Cu-Cu bonding with stress engineering was demonstrated using multiple current stressing and temperature cycling test, suggests excellent reliable bonding without electrical performance degradation.

  8. Direct, CMOS In-Line Process Flow Compatible, Sub 100 °C Cu-Cu Thermocompression Bonding Using Stress Engineering

    Science.gov (United States)

    Panigrahi, Asisa Kumar; Ghosh, Tamal; Kumar, C. Hemanth; Singh, Shiv Govind; Vanjari, Siva Rama Krishna

    2018-03-01

    Diffusion of atoms across the boundary between two bonding layers is the key for achieving excellent thermocompression Wafer on Wafer bonding. In this paper, we demonstrate a novel mechanism to increase the diffusion across the bonding interface and also shows the CMOS in-line process flow compatible Sub 100 °C Cu-Cu bonding which is devoid of Cu surface treatment prior to bonding. The stress in sputtered Cu thin films was engineered by adjusting the Argon in-let pressure in such a way that one film had a compressive stress while the other film had tensile stress. Due to this stress gradient, a nominal pressure (2 kN) and temperature (75 °C) was enough to achieve a good quality thermocompression bonding having a bond strength of 149 MPa and very low specific contact resistance of 1.5 × 10-8 Ω-cm2. These excellent mechanical and electrical properties are resultant of a high quality Cu-Cu bonding having grain growth between the Cu films across the boundary and extended throughout the bonded region as revealed by Cross-sectional Transmission Electron Microscopy. In addition, reliability assessment of Cu-Cu bonding with stress engineering was demonstrated using multiple current stressing and temperature cycling test, suggests excellent reliable bonding without electrical performance degradation.

  9. Heap leaching of Cu contaminated soil with [S,S]-EDDS in a closed process loop

    International Nuclear Information System (INIS)

    Finzgar, Neza; Zumer, Alenka; Lestan, Domen

    2006-01-01

    Heap leaching of Cu contaminated soil (412 ± 11 mg kg -1 ) with 5 mmol kg -1 ethylenediamine disuccinate [S,S]-EDDS as a chelator was tested in a laboratory-scale soil column study. The washing solution was recycled in a closed process loop after microbial (using a microbially active permeable bed, composed of substrate and absorbent) and oxidative chemical (using combined ozonation and UV irradiation) degradation of metal-[S,S]-EDDS complexes and retention of released Cu on a commercial absorbent Slovakite. Heap leaching using the permeable bed removed 25.5 ± 3.6% of initial total Cu from the soil. Ozone/UV treatment of the [S,S]-EDDS washing solution removed much more, 47.5 ± 7.4%, of Cu. Both methods yielded a clear and colorless final (waste) washing solution, with 7.0 ± 10.0 and 2.6 ± 0.7 mg L -1 Cu (permeable bed and ozone/UV method, respectively). The results of our study indicate that chemical treatment of chelator washing solution with ozone/UV in a closed process loop could lead to the development of a new, efficient and environmentally safe remediation method with controllable Cu emissions

  10. Electromigration-induced plasticity and texture in Cu interconnects

    International Nuclear Information System (INIS)

    Advanced Light Source; Tamura, Nobumichi; Budiman, A. S.; Hau-Riege, C.S.; Besser, P. R.; Marathe, A.; Joo, Y.-C.; Tamura, N.; Patel, J. R.; Nix, W. D.

    2007-01-01

    Plastic deformation has been observed in damascene Cu interconnect test structures during an in-situ electromigration experiment and before the onset of visible microstructural damage (ie. voiding) using a synchrotron technique of white beam X-ray microdiffraction. We show here that the extent of this electromigration-induced plasticity is dependent on the texture of the Cu grains in the line. In lines with strong textures, the extent of plastic deformation is found to be relatively large compared to our plasticity results in the previous study [1] using another set of Cu lines with weaker textures. This is consistent with our earlier observation that the occurrence of plastic deformation in a given grain can be strongly correlated with the availability of a direction of the crystal in the proximity of the direction of the electron flow in the line (within an angle of 10 o ). In out-of-plane oriented grains in a damascene interconnect scheme, the crystal plane facing the sidewall tends to be a {110} plane,[2-4] so as to minimize interfacial energy. Therefore, it is deterministic rather than probabilistic that the grains will have a direction nearly parallel to the direction of electron flow. Thus, strong textures lead to more plasticity, as we observe

  11. Electromigration-induced Plasticity and Texture in Cu Interconnects

    Science.gov (United States)

    Budiman, A. S.; Hau-Riege, C. S.; Besser, P. R.; Marathe, A.; Joo, Y.-C.; Tamura, N.; Patel, J. R.; Nix, W. D.

    2007-10-01

    Plastic deformation has been observed in damascene Cu interconnect test structures during an in-situ electromigration experiment and before the onset of visible microstructural damage (ie. voiding) using a synchrotron technique of white beam X-ray microdiffraction. We show here that the extent of this electromigration-induced plasticity is dependent on the texture of the Cu grains in the line. In lines with strong textures, the extent of plastic deformation is found to be relatively large compared to our plasticity results in the previous study[1] using another set of Cu lines with weaker textures. This is consistent with our earlier observation that the occurrence of plastic deformation in a given grain can be strongly correlated with the availability of a direction of the crystal in the proximity of the direction of the electron flow in the line (within an angle of 10°). In out-of-plane oriented grains in a damascene interconnect scheme, the crystal plane facing the sidewall tends to be a {110} plane,[2-4] so as to minimize interfacial energy. Therefore, it is deterministic rather than probabilistic that the grains will have a direction nearly parallel to the direction of electron flow. Thus, strong textures lead to more plasticity, as we observe.

  12. Electromigration-induced plasticity and texture in Cu interconnects

    Energy Technology Data Exchange (ETDEWEB)

    Advanced Light Source; Tamura, Nobumichi; Budiman, A. S.; Hau-Riege, C.S.; Besser, P. R.; Marathe, A.; Joo, Y.-C.; Tamura, N.; Patel, J. R.; Nix, W. D.

    2007-10-31

    Plastic deformation has been observed in damascene Cu interconnect test structures during an in-situ electromigration experiment and before the onset of visible microstructural damage (ie. voiding) using a synchrotron technique of white beam X-ray microdiffraction. We show here that the extent of this electromigration-induced plasticity is dependent on the texture of the Cu grains in the line. In lines with strong <111> textures, the extent of plastic deformation is found to be relatively large compared to our plasticity results in the previous study [1] using another set of Cu lines with weaker textures. This is consistent with our earlier observation that the occurrence of plastic deformation in a given grain can be strongly correlated with the availability of a <112> direction of the crystal in the proximity of the direction of the electron flow in the line (within an angle of 10{sup o}). In <111> out-of-plane oriented grains in a damascene interconnect scheme, the crystal plane facing the sidewall tends to be a {l_brace}110{r_brace} plane,[2-4] so as to minimize interfacial energy. Therefore, it is deterministic rather than probabilistic that the <111> grains will have a <112> direction nearly parallel to the direction of electron flow. Thus, strong <111> textures lead to more plasticity, as we observe.

  13. In-situ EC-STM studies on the influence of halide anions on structure and reactivity of dibenzylviologen on Cu(100)

    Energy Technology Data Exchange (ETDEWEB)

    Gentz, Knud; Wandelt, Klaus [Institute of Physical and Theoretical Chemistry, Bonn University (Germany); Broekmann, Peter [University of Bern (Switzerland)

    2009-07-01

    Copper has become a focus of research activities over the last two decades due to its use as interconnect material in microchip design. Nitrogen-containing cationic organic molecules have been studied as additives for the so-called copper damascene process. In the present investigation the structures and reactivity of a dibenzylviologen (DBV) layer adsorbed on a bromide-modified Cu(100) surface have been studied by in-situ electrochemical STM and will be compared to the results on the chloride-modified substrate and the related Diphenylviologen (DPV). N,N'-dibenzyl-4,4'-bipyridinium molecules (dibenzylviologen, DBV) spontaneously adsorb on a halide-modified Cu(100)-surface, forming distinctive patterns, which have been characterized by in-situ scanning tunneling microscopy. Depending on the adsorption potential a striped phase, a cavitand phase and an amorphous phase have been identified. Cyclic voltammetry indicates that even more processes take place on the surface, because if the potential is decreased beyond a range of fully reversible processes, an irreversible surface phase formation is observed at -450 mV vs. RHE. This surface phase passivates the surface against adsorption of the dicationic phase, so the charge reversal of the interface in the outer Helmholtz layer seems to be reduced.

  14. Structure evolution during the cooling and coalesced cooling processes of Cu-Co bimetallic clusters

    International Nuclear Information System (INIS)

    Li Guojian; Wang Qiang; Li Donggang; Lue Xiao; He Jicheng

    2008-01-01

    Constant-temperature molecular dynamics with general EAM was employed to study the structure evolutions during the cooling and coalesced cooling processes of Cu-Co bimetallic clusters. It shows that the desired particle morphologies and structures can be obtained by controlling the composition and distribution of hetero atoms during synthesis process

  15. Effect of extrusion processing on the microstructure, mechanical properties, biocorrosion properties and antibacterial properties of Ti-Cu sintered alloys

    International Nuclear Information System (INIS)

    Zhang, Erlin; Li, Shengyi; Ren, Jing; Zhang, Lan; Han, Yong

    2016-01-01

    Ti-Cu sintered alloys, Ti-Cu(S) alloy, have exhibited good anticorrosion resistance and strong antibacterial properties, but low ductility in previous study. In this paper, Ti-Cu(S) alloys were subjected to extrusion processing in order to improve the comprehensive property. The phase constitute, microstructure, mechanical property, biocorrosion property and antibacterial activity of the extruded alloys, Ti-Cu(E), were investigated in comparison with Ti-Cu(S) by X-ray diffraction (XRD), optical microscopy (OM), scanning electronic microscopy (SEM) with energy disperse spectroscopy (EDS), mechanical testing, electrochemical testing and plate-count method in order to reveal the effect of the extrusion process. XRD, OM and SEM results showed that the extrusion process did not change the phase constitute but refined the grain size and Ti 2 Cu particle significantly. Ti-Cu(E) alloys exhibited higher hardness and compressive yield strength than Ti-Cu(S) alloys due to the fine grain and Ti 2 Cu particles. With the consideration of the total compressive strain, it was suggested that the extrusion process could improve the ductility of Ti-Cu alloy(S) alloys. Electrochemical results have indicated that the extrusion process improved the corrosion resistance of Ti-Cu(S) alloys. Plate-count method displayed that both Ti-Cu(S) and Ti-Cu(E) exhibited strong antibacterial activity (> 99%) against S. aureus. All these results demonstrated that hot forming processing, such as the extrusion in this study, refined the microstructure and densified the alloy, in turn improved the ductility and strength as well as anticorrosion properties without reduction in antibacterial properties. - Highlights: • Hot extrusion refined the grain size and Ti 2 Cu phase significantly. • Hot extrusion increased the mechanical properties and the corrosion resistance. • The antibacterial properties was not affected by the hot process.

  16. Increasing the carbon capture efficiency of the Ca/Cu looping process for power production with advanced process schemes

    NARCIS (Netherlands)

    Martini, M.; Martinez, I.; Romano, M.C.; Chiesa, P.; Gallucci, F.; van Sint Annaland, M.

    2017-01-01

    The Ca-Cu process is a novel concept for hydrogen production with inherent CO2 capture that has received great attention in the last years as potential low-CO2 emission technology for power generation and hydrogen production from natural gas. The process is based on the reforming of natural gas in

  17. Treatment of reverse osmosis (RO) concentrate by the combined Fe/Cu/air and Fenton process (1stFe/Cu/air-Fenton-2ndFe/Cu/air).

    Science.gov (United States)

    Ren, Yi; Yuan, Yue; Lai, Bo; Zhou, Yuexi; Wang, Juling

    2016-01-25

    To decompose or transform the toxic and refractory reverse osmosis (RO) concentrate and improve the biodegradability, 1stFe/Cu/air-Fenton-2ndFe/Cu/air were developed to treat RO concentrate obtained from an amino acid production plant in northern China. First, their operating conditions were optimized thoroughly. Furthermore, 5 control experiments were setup to confirm the superiority of 1stFe/Cu/air-Fenton-2ndFe/Cu/air and synergistic reaction between Fe/Cu/air and Fenton. The results suggest that the developed method could obtain high COD removal (65.1%) and BOD5/COD ratio (0.26) due to the synergistic reaction between Fe/Cu/air and Fenton. Under the optimal conditions, the influent and effluent of 1stFe/Cu/air-Fenton-2ndFe/Cu/air and 5 control experiments were analyzed by using UV, FTIR, EEM and LC, which confirm the superiority of 1stFe/Cu/air-Fenton-2ndFe/Cu/air. Therefore, the developed method in this study is a promising process for treatment of RO concentrate. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Phase transformation and microstructural changes during ageing process of an Ag-Pd-Cu-Au alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Chin-Ho; Park, Mi-Gyoung; Kwon, Yong Hoon; Seol, Hyo-Joung [Department of Dental Materials, School of Dentistry and Medical Research Institute, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of); Kim, Hyung-Il [Department of Dental Materials, School of Dentistry and Medical Research Institute, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of)], E-mail: hilkim@pusan.ac.kr

    2008-07-28

    Age-hardening behaviour and the related phase transformation and microstructural changes during isothermal ageing process were studied to elucidate the age-hardening mechanism of an Ag-based dental casting alloy composed of Ag-Pd-Cu-Au-Zn, Ir and In by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and energy dispersive spectroscopic microanalysis (EDS). In the hardness test at 350 and 400 deg. C, the hardness of the solution-treated specimen began to increase and reached a maximum value with increasing ageing time, and subsequently the hardness decreased gradually. By considering XRD results and SEM observations together, the solution-treated specimen consisted of three phases, the Ag-rich {alpha}{sub 1} phase as a matrix, the Cu-Pd {alpha}{sub 2} phase and the CuPd {beta} phase with a CsCl-type as particle-like structures. By ageing the solution-treated specimen, the Ag-rich {alpha}{sub 1} and Cu-Pd {alpha}{sub 2} phases were transformed into the Ag-rich {alpha}{sup '}{sub 1} and Cu{sub 3}Pd {alpha}{sup '}{sub 2} phases, respectively. The CuPd {beta} phase with a CsCl-type was not changed apparently during the ageing process. From the results of the hardness test, XRD study, SEM observations and EDS analysis, it could be derived that the hardness increased by the diffusion and precipitation of the Cu-rich phase from the Ag-rich matrix during the early stage of phase transformation of {alpha}{sub 1} into {alpha}{sup '}{sub 1} and that the progress of coarsening of the Cu-rich precipitates with an entanglement structure caused the hardness decrease during the later stage of phase transformation of {alpha}{sub 1} into {alpha}{sup '}{sub 1}. The particle-like structures composed of the Cu-Pd {alpha}{sub 2} and the CuPd {beta} phase with a CsCl-type contributed little to the hardness increase which occurred in the early stage of aging process.

  19. Hot Deformation Behavior and Processing Maps of Diamond/Cu Composites

    Science.gov (United States)

    Zhang, Hongdi; Liu, Yue; Zhang, Fan; Zhang, Di; Zhu, Hanxing; Fan, Tongxiang

    2018-06-01

    The hot deformation behaviors of 50 vol pct uncoated and Cr-coated diamond/Cu composites were investigated using hot isothermal compression tests under the temperature and strain rate ranging from 1073 K to 1273 K (800 °C to 1000 °C) and from 0.001 to 5 s-1, respectively. Dynamic recrystallization was determined to be the primary restoration mechanism during deformation. The Cr3C2 coating enhanced the interfacial bonding and resulted in a larger flow stress for the Cr-coated diamond/Cu composites. Moreover, the enhanced interfacial affinity led to a higher activation energy for the Cr-coated diamond/Cu composites (238 kJ/mol) than for their uncoated counterparts (205 kJ/mol). The strain-rate-dependent constitutive equations of the diamond/Cu composites were derived based on the Arrhenius model, and a high correlation ( R = 0.99) was observed between the calculated flow stresses and experimental data. With the help of processing maps, hot extrusions were realized at 1123 K/0.01 s-1 and 1153 K/0.01 s-1 (850 °C/0.01 s-1 and 880 °C/0.01 s-1) for the uncoated and coated diamond/Cu composites, respectively. The combination of interface optimization and hot extrusion led to increases of the density and thermal conductivity, thereby providing a promising route for the fabrication of diamond/Cu composites.

  20. Microanalysis on CuInSe2 compound synthesized by mechanochemical processing

    International Nuclear Information System (INIS)

    Wu Sumei; Xue Yuzhi; Zhang Zhihua

    2010-01-01

    CuInSe 2 (CIS) compound has been synthesized by mechanochemical processing (MCP) with different process parameters. The effect of milling time and different molar ratios of Cu:In:Se was investigated. The obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) for evaluating their crystal structure, grain size, morphology and composition. Field emission transmission electron microscopy (FETEM) was used to detect the smog particles produced during the milling. The results revealed that the obtained powder was chalcopyrite CuInSe 2 and the particle size was smaller than 5 μm after milling for 60 min. The EDS analysis indicated that the smog was volatile selenium. The composition of the products deviated from those of starting materials after MCP. The mechanism about mechanically induced self-propagating reaction which occurred during milling copper, indium and selenium powders was also discussed.

  1. Melt-spin processing of YBa2Cu3O7-x

    International Nuclear Information System (INIS)

    Folkerts, T.J.; Kramer, M.J.; McCallum, R.W.; Iowa State Univ. of Science and Technology, Ames, IA

    1991-01-01

    We introduce a novel containerless melt-spin processing technique for YBa 2 Cu 3 O 7-x using prereacted oxide powders which are rapidly melted and subsequentially quenched in a controlled atmosphere. This results in flakes with typical dimensions of 3000x150x15 μm 3 . Powder XRD indicates that all samples contain Y 2 O 3 , but that the Ba--Cu--O phases present depend on the processing parameters. SEM and TEM studies show these phases are finely dispersed: the typical grain size for Y 2 O 3 is 1--2 μm, and for the Ba--Cu--O phases it is <0.5 μm

  2. Cu and Zn Isotopes as New Tracers of Early Solar Nebula and Asteroidal processes

    Science.gov (United States)

    LUCK, J.; BEN OTHMAN, D.; ALBAREDE, F.

    2001-12-01

    Cu and Zn isotopic variations are now identified in extra-terrestrial samples, as has been the case for terrestrial samples (1). The main parameters which may cause these variations are : redox state, temperature, biological activity (Earth), and volatility (extra-terrestrial samples). We report data for meteorites from various groups and classes, including carbonaceous chondrites, ordinary and diffentiated chondrites (iron meteorites, SNC and HED). All analyses have been duplicated (from powder aliquot to final measurement). Values are expressed as relative deviations from NIST and JMC standards for 65Cu/63Cu and 66Zn64Zn, respectively (deltas in permil). Carefull chemistry and MC-ICP-MS measurements allow an overall precision of +/-0.04 permil. I- Carbonaceous Chondrites A very important feature is that each group seems to exhibit a specific isotopic signature : Cu gets isotopically lighter from CI to CM to CO to CV, spanning an overall range of 1.5 permil. Zn shows a reverse order, getting heavier from CI to CM to CO. Zn in CV chondrites (whole rock) seems more variable. This order is the same as that observed for trace elements. Cu and Zn isotopic compositions are generally correlated to trace element content from one group to another, particularly those of similar volatility (e.g. Mn for Cu; Ge for Zn). Cu and Zn isotopic signatures exhibit remarkable relationships with Oxygen isotopes. Each group is well identified. Cu is linearly correlated with Oxygen, whereas Zn-O data display strong curvature : the difference in shape can be related to the nearly constant Cu content in all groups, and by the decreasing Zn content from CI to CO. Since Oxygen variations (from CV to CI) are thought to reflect progressive interaction of liquid water with initial solid (asteroid), Cu isotopic variations may also reflect this progressive alteration process. It may be so for Zn too, although its more volatile character might play a role. II-Allende Progressive leaching

  3. Effect of extrusion processing on the microstructure, mechanical properties, biocorrosion properties and antibacterial properties of Ti-Cu sintered alloys.

    Science.gov (United States)

    Zhang, Erlin; Li, Shengyi; Ren, Jing; Zhang, Lan; Han, Yong

    2016-12-01

    Ti-Cu sintered alloys, Ti-Cu(S) alloy, have exhibited good anticorrosion resistance and strong antibacterial properties, but low ductility in previous study. In this paper, Ti-Cu(S) alloys were subjected to extrusion processing in order to improve the comprehensive property. The phase constitute, microstructure, mechanical property, biocorrosion property and antibacterial activity of the extruded alloys, Ti-Cu(E), were investigated in comparison with Ti-Cu(S) by X-ray diffraction (XRD), optical microscopy (OM), scanning electronic microscopy (SEM) with energy disperse spectroscopy (EDS), mechanical testing, electrochemical testing and plate-count method in order to reveal the effect of the extrusion process. XRD, OM and SEM results showed that the extrusion process did not change the phase constitute but refined the grain size and Ti2Cu particle significantly. Ti-Cu(E) alloys exhibited higher hardness and compressive yield strength than Ti-Cu(S) alloys due to the fine grain and Ti2Cu particles. With the consideration of the total compressive strain, it was suggested that the extrusion process could improve the ductility of Ti-Cu alloy(S) alloys. Electrochemical results have indicated that the extrusion process improved the corrosion resistance of Ti-Cu(S) alloys. Plate-count method displayed that both Ti-Cu(S) and Ti-Cu(E) exhibited strong antibacterial activity (>99%) against S. aureus. All these results demonstrated that hot forming processing, such as the extrusion in this study, refined the microstructure and densified the alloy, in turn improved the ductility and strength as well as anticorrosion properties without reduction in antibacterial properties. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Fuzzy analytical hierarchy process and GIS for predictive cu -au ...

    African Journals Online (AJOL)

    Mineral exploration generally starts on small scale (small areas) and, then progresses to large scale (small area). There are many methods for achieving this goal. To achieve this goal one of these methods is Fuzzy analytical hierarchy process (Fuzzy AHP) that is the most popular multi-criteria decision-making techniques.

  5. FE modeling of Cu wire bond process and reliability

    NARCIS (Netherlands)

    Yuan, C.A.; Weltevreden, E.R.; Akker, P. van den; Kregting, R.; Vreugd, J. de; Zhang, G.Q.

    2011-01-01

    Copper based wire bonding technology is widely accepted by electronic packaging industry due to the world-wide cost reduction actions (compared to gold wire bond). However, the mechanical characterization of copper wire differs from the gold wire; hence the new wire bond process setting and new bond

  6. Levels of Processing with Free and Cued Recall and Unilateral Temporal Lobe Epilepsy

    Science.gov (United States)

    Lespinet-Najib, Veronique; N'Kaoua, Bernard; Sauzeon, Helene; Bresson, Christel; Rougier, Alain; Claverie, Bernard

    2004-01-01

    This study investigates the role of the temporal lobes in levels-of-processing tasks (phonetic and semantic encoding) according to the nature of recall tasks (free and cued recall). These tasks were administered to 48 patients with unilateral temporal epilepsy (right ''RTLE''=24; left ''LTLE''=24) and a normal group (n=24). The results indicated…

  7. An efficient synthesis of isocoumarins via a CuI catalyzed cascade reaction process

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    3-Alkyl isocoumarins are provided by CuI/amino acid-catalyzed Sonogashira coupling reaction of o-bromo benzoic acids and terminal alkynes and the subsequent additive cyclization. This cascade process allows synthesis of diverse isocoumarins by varying both coupling partners bearing a wide range of functional groups.

  8. Ceramic Composites of 3Y-TZP Doped with CuO: Processing, Microstructure and Tribology

    NARCIS (Netherlands)

    Ran, S.

    2006-01-01

    The work described in this thesis is about processing, microstructure and tribology of CuO doped 3Y-TZP (3 mol% yttria stabilised tetragonal zirconia polycrystals) composite ceramics. This group of materials has shown attractive properties such as superplastic behaviour at elevated temperature and a

  9. Processing-property relations in YBa2Cu3O(6+x) superconductors

    Science.gov (United States)

    Safari, A.; Wachtman, J. B., Jr.; Parkhe, V.; Caracciolo, R.; Jeter, D.

    Processing of YBa2Cu3O(6+x) superconducting samples by employing different precursor powder preparation techniques such as ball milling, attrition milling, and narrow particle size distribution powder preparation through coprecipitation by spraying will be discussed. CuO coated with oxalates shows the lowest resistance above Tc up to room temperature. The extent of corrosion by water has been studied by employing magnetic susceptibility, XPS, and X-ray diffraction. Superconducting samples are affected to a considerable extent when treated in water at 60 C and the severity of the attack increases with time.

  10. Optimization of a Cu CMP process modeling parameters of nanometer integrated circuits

    International Nuclear Information System (INIS)

    Ruan Wenbiao; Chen Lan; Ma Tianyu; Fang Jingjing; Zhang He; Ye Tianchun

    2012-01-01

    A copper chemical mechanical polishing (Cu CMP) process is reviewed and analyzed from the view of chemical physics. Three steps Cu CMP process modeling is set up based on the actual process of manufacturing and pattern-density-step-height (PDSH) modeling from MIT. To catch the pattern dependency, a 65 nm testing chip is designed and processed in the foundry. Following the model parameter extraction procedure, the model parameters are extracted and verified by testing data from the 65 nm testing chip. A comparison of results between the model predictions and test data show that the former has the same trend as the latter and the largest deviation is less than 5 nm. Third party testing data gives further evidence to support the great performance of model parameter optimization. Since precise CMP process modeling is used for the design of manufacturability (DFM) checks, critical hotspots are displayed and eliminated, which will assure good yield and production capacity of IC. (semiconductor technology)

  11. In Situ Study of Reduction Process of CuO Paste and Its Effect on Bondability of Cu-to-Cu Joints

    Science.gov (United States)

    Yao, Takafumi; Matsuda, Tomoki; Sano, Tomokazu; Morikawa, Chiaki; Ohbuchi, Atsushi; Yashiro, Hisashi; Hirose, Akio

    2018-04-01

    A bonding method utilizing redox reactions of metallic oxide microparticles achieves metal-to-metal bonding in air, which can be alternative to lead-rich high-melting point solder. However, it is known that the degree of the reduction of metallic oxide microparticles have an influence on the joint strength using this bonding method. In this paper, the reduction behavior of CuO paste and its effect on Cu-to-Cu joints were investigated through simultaneous microstructure-related x-ray diffraction and differential scanning calorimetry measurements. The CuO microparticles in the paste were gradually reduced to submicron Cu2O particles at 210-250°C. Subsequently, Cu nanoparticles were generated instantaneously at 300-315°C. There was a marked difference in the strengths of the joints formed at 300°C and 350°C. Thus, the Cu nanoparticles play a critical role in sintering-based bonding using CuO paste. Furthermore, once the Cu nanoparticles have formed, the joint strength increases with higher bonding temperature (from 350°C to 500°C) and pressure (5-15 MPa), which can exceed the strength of Pb-5Sn solder at higher temperature and pressure.

  12. Synthesis of Cu-coated Graphite Powders Using a Chemical Reaction Process

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jun-Ho; Park, Hyun-Kuk; Oh, Ik-Hyun [Korea Institute of Industrial Technology (KITECH), Gwangju (Korea, Republic of); Lim, Jae-Won [Chonbuk National University, Jeonju (Korea, Republic of)

    2017-05-15

    In this paper, Cu-coated graphite powders for a low thermal expansion coefficient and a high thermal conductivity are fabricated using a chemical reaction process. The Cu particles adhere to the irregular graphite powders and they homogeneously disperse in the graphite matrix. Cu-coated graphite powders are coarser at approximately 3-4 μm than the initial graphite powders; furthermore, their XRD patterns exhibit a low intensity in the oxide peak with low Zn powder content. For the passivation powders, the transposition solvent content has low values, and the XRD pattern of the oxide peaks is almost non-existent, but the high transposition solvent content does not exhibit a difference to the non-passivation treated powders.

  13. Melt-processed LRE-Ba-Cu-O superconductors and prospects for their applications

    International Nuclear Information System (INIS)

    Yoo, S.I.; Fujimoto, H.; Sakai, N.; Murakami, M.

    1997-01-01

    We have recently found that control of the oxygen partial pressure (PO 2 ) during melt processing, named the oxygen-controlled melt-growth (OCMG) process, is critical for obtaining a high superconducting transition temperature (T c ) in the light rare earth (LRE)-Ba-Cu-O (LREBCO) superconductors particularly for Nd, Sm and Eu. Further, compared to a good melt-processed Y-Ba-Cu-O (YBCO) bulk superconductor, LREBCO bulks exhibit larger critical current density (J c ) in high magnetic field and a much improved irreversibility field (H irr ) at 77 K, implying that more effective flux pinning can be realized in a commercially feasible way. In this paper, properties and characteristic flux pinning of OCMG-processed LREBCO (LRE: Nd,Sm,Eu) superconductors are described on the basis of our study during the last several years. We also present the prospects for bulk-type applications, such as the magnetic bearings, flywheels and magnetically levitated (MAGLEV) trains. (orig.)

  14. Simple solution-processed CuO{sub X} as anode buffer layer for efficient organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Wenfei [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Institute of Hybrid Materials, The Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Yang, Chunpeng [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Bao, Xichang, E-mail: baoxc@qibebt.ac.cn [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Sun, Liang; Wang, Ning [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Tang, Jianguo [Institute of Hybrid Materials, The Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Chen, Weichao [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Yang, Renqiang, E-mail: yangrq@qibebt.ac.cn [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China)

    2015-10-15

    Graphical abstract: - Highlights: • Simple solution-processed CuO{sub X} hole transport layer for efficient organic solar cell. • Good photovoltaic performances as hole transport layer in OSCs with P3HT and PBDTTT-C as donor materials. • The device with CuO{sub X} as hole transport layer shows great improved stability compared with that of device with PEDOT:PSS as hole transport layer. - Abstract: A simple, solution-processed ultrathin CuO{sub X} anode buffer layer was fabricated for high performance organic solar cells (OSCs). XPS measurement demonstrated that the CuO{sub X} was the composite of CuO and Cu{sub 2}O. The CuO{sub X} modified ITO glass exhibit a better surface contact with the active layer. The photovoltaic performance of the devices with CuO{sub X} layer was optimized by varying the thickness of CuO{sub X} films through changing solution concentration. With P3HT:PC{sub 61}BM as the active layer, we demonstrated an enhanced PCE of 4.14% with CuO{sub X} anode buffer layer, compared with that of PEDOT:PSS layer. The CuO{sub X} layer also exhibits efficient photovoltaic performance in devices with PBDTTT-C:PC{sub 71}BM as the active layer. The long-term stability of CuO{sub X} device is better than that of PEDOT:PSS device. The results indicate that the easy solution-processed CuO{sub X} film can act as an efficient anode buffer layer for high-efficiency OSCs.

  15. Simple thermodynamic model of the extension of solid solution of Cu-Mo alloys processed by mechanical alloying

    International Nuclear Information System (INIS)

    Aguilar, C.; Guzman, D.; Rojas, P.A.; Ordonez, Stella; Rios, R.

    2011-01-01

    Highlights: → Extension of solid solution in Cu-Mo systems achieved by mechanical alloying. → Simple thermodynamic model to explain extension of solid solution of Mo in Cu. → Model gives results that are consistent with the solubility limit extension reported in other works. - Abstract: The objective of this work is proposing a simple thermodynamic model to explain the increase in the solubility limit of the powders of the Cu-Mo systems or other binary systems processed by mechanical alloying. In the regular solution model, the effects of crystalline defects, such as; dislocations and grain boundary produced during milling were introduced. The model gives results that are consistent with the solubility limit extension reported in other works for the Cu-Cr, Cu-Nb and Cu-Fe systems processed by mechanical alloying.

  16. Melt spin processing and recrystallization of REBa2Cu3O7-x

    International Nuclear Information System (INIS)

    Folkerts, T.J.; Kramer, M.J.; Dennis, K.W.; McCallum, R.W.

    1992-01-01

    This paper introduces a containerless melt-spin processing technique for REBa 2 Cu 3 O 7-x using pre-reacted oxide powders which are rapidly melted and subsequentially quenched in a controlled atmosphere. This results in flakes with typical dimensional of 3000 x 150 x 15μm 3 . Gd123 and Nd123 form nearly amorphous ribbons with only minor BaCu 2 O 2 when dropped in N 2 . Y123 contains Y 2 O 3 , but that the Ba-Cu-P phases present depend on the processing parameters. SEM and TEM studies show these phases are finely diapered; the typical grain size for Y 2 O 3 is 1-2μm, and for the Ba-Cu-O phases it is <0.5μm. Upon recrystallization from the amorphous ribbon, the Gd123 and Nd123 form field directly into the 123 phase while the recrystallization of the Y123 ribbons is less direct

  17. Mono-domain YBa2Cu3Oy superconductor fabrics prepared by an infiltration process

    International Nuclear Information System (INIS)

    Sudhakar Reddy, E.; Noudem, J.G.; Tarka, M.; Schmitz, G.J.

    2000-01-01

    A novel process for the fabrication of a new form of YBa 2 Cu 3 O y (123) superconducting material, with the dimensions of a thick film and the microstructure of a melt-textured single-domain bulk is described. The process allows the fabrication of 123 as a self-supporting fabric or as a thick film on various substrate materials. The process, which is generic and economical, uses commercially available Y 2 O 3 fabrics as a precursor material. The Y 2 O 3 cloth is infiltrated with barium cuprates and copper oxides from a liquid-phase source, then converted into Y 2 BaCuO 5 (211) phase and eventually to 123. The nucleation and growth of the 123 phase is controlled by seeding the cloth with an oriented heterogeneous MgO or Nd123 seed. Interesting application areas for the new form of the 123 mono-domain fabric are discussed. (author)

  18. The electrical conductivity of CuCrZr alloy after SPD processing

    International Nuclear Information System (INIS)

    Lipińska, M; Bazarnik, P; Lewandowska, M

    2014-01-01

    CuCrZr alloys exhibit very good relation between mechanical properties and electrical conductivity. However, for its use in some advanced applications improvement of mechanical strength while preserving high electrical conducting is required. Therefore, in this work a CuCrZr alloy was subjected to a series of thermo-mechanical treatments, including solution annealing and water quenching, SPD processing (using hydrostatic extrusion and ECAP) as well as aging in order to improve mechanical strength. The influence of these processing procedures on microstructure features and mechanical properties was determined by TEM observation and microhardness measurements, respectively. Electrical conductivity of the samples was measured by four-points method. The results have shown that it is possible to improve mechanical strength while preserving good electrical conductivity by a proper combination of SPD processing and heat treatment

  19. Influence of Y2BaCuO5 precipitates on the current density of melt processed YBa2Cu3Ox superconductor

    International Nuclear Information System (INIS)

    Salama, K.; Selvamanickam, V.

    1992-01-01

    YBa 2 Cu 3 O x superconductors fabricated by melt processing methods have been shown to exhibit current density around 10 5 A/cm 2 at 77 K. Since YBa 2 Cu 3 O x decomposes peritectically above 1000 C, more than 50 vol. % of Y 2 BaCuO 5 (211) precipitates are formed during the incongruent melting. Even under stringent slow cooling conditions, a significant amount of these precipitates remain unreacted with the liquid and are left embedded in the long 123 grains. The potential of these precipitates as flux pinning sites has been investigated extensively, but remains controversial. In this study, we have performed transport current density measurements on melt processed YBa 2 Cu 3 O x superconductor prepared with varying amount of 211 precipitates. The current density measurements were performed in magnetic fields up to 1.5 T at 77 K with the field aligned at different angles to the a-b plane. The results provided in this paper show that Jc decreases monotonically with increasing amount of 211, irrespective of the angle between the field and the a-b plane indicating the absence of significant pinning by 211 precipitates in melt processed YBa 2 Cu 3 O x superconductor

  20. Neural correlates of encoding processes predicting subsequent cued recall and source memory.

    Science.gov (United States)

    Angel, Lucie; Isingrini, Michel; Bouazzaoui, Badiâa; Fay, Séverine

    2013-03-06

    In this experiment, event-related potentials were used to examine whether the neural correlates of encoding processes predicting subsequent successful recall differed from those predicting successful source memory retrieval. During encoding, participants studied lists of words and were instructed to memorize each word and the list in which it occurred. At test, they had to complete stems (the first four letters) with a studied word and then make a judgment of the initial temporal context (i.e. list). Event-related potentials recorded during encoding were segregated according to subsequent memory performance to examine subsequent memory effects (SMEs) reflecting successful cued recall (cued recall SME) and successful source retrieval (source memory SME). Data showed a cued recall SME on parietal electrode sites from 400 to 1200 ms and a late inversed cued recall SME on frontal sites in the 1200-1400 ms period. Moreover, a source memory SME was reported from 400 to 1400 ms on frontal areas. These findings indicate that patterns of encoding-related activity predicting successful recall and source memory are clearly dissociated.

  1. Study of processes of interligand exchange between Cu(AA)2 and Y(DPM)3 in geseous phase

    International Nuclear Information System (INIS)

    Girichev, G.V.; Giricheva, N.I.; Belova, N.V.; Kuz'mina, N.P.; Kaul', A.R.; Gorbenko, O.Yu.

    1993-01-01

    Mass-spectrometric method was used to study the process, proceeding between gaseous copper acetylacetonate and yttrium dipivaloylmethanate in 150-630 deg C range. It was established that intensive ligand exchange with formation of Cu(DPM) (AA), Y(DPM) 2 (AA), Cu(DPM) 2 compounds in gaseous mixture took place between components. Thermal decomposition of copper and yttrium β-diketonates was observed with temperature growth, along with reactions of interligand exchange. Molecular forms of Y(DPM) 2 , Y(DPM)(AA), Cu(DPM) 2 and Cu(DPM)(AA) were the most thermally stable at that

  2. Microstructure and associated properties of YBa2Cu3Ox superconductors prepared by melt-processing techniques

    International Nuclear Information System (INIS)

    Balachandran, U.; Zhong, W.; Youngdahl, C.A.; Poeppel, R.B.

    1993-03-01

    From the standpoint of applications, melt-processed bulk YBa 2 Cu 3 O x (YBCO) superconductors are of considerable interest. We have studied the microstructure and levitation force of melt-processed YBCO, YBCO plus Y 2 BaCuO 5 , and YBCO plus Pt samples. Large single crystalline samples, grown using a seeding technique, were also studied. The levitation force is highest in melt-processed samples made by the seeding technique. 6 figs, 24 refs

  3. The facile synthesis of a chitosan Cu(II) complex by solution plasma process and evaluation of their antioxidant activities.

    Science.gov (United States)

    Ma, Fengming; Li, Pu; Zhang, Baiqing; Wang, Zhenyu

    2017-10-01

    Synthesis of chitosan-Cu(II) complex by solution plasma process (SPP) irradiation was investigated. The effects of the distance between the electrodes, initial Cu(II) concentration, and initial pH on the Cu(II) adsorption capacity were evaluated. The results showed that narrower distance between the electrodes, higher initial Cu(II) concentration and higher initial pH (at pHchitosan-Cu(II) complex by ultraviolet-visible (UV-vis), fourier transform infrared (FT-IR) and electron spin resonance (ESR) spectroscopy revealed that the main structure of chitosan was not changed after irradiation. Thermogravimetry (TG) analysis indicated that Cu(II) ions were well incorporated into the chitosan. The antioxidant activity of the chitosan-Cu(II) complex was evaluated by DPPH, ABTS, and reducing power assays. The chitosan-Cu(II) complex exhibited greater antioxidant activity than the original chitosan. Thus, SPP could be used for preparation of chitosan-Cu(II) complexes. Copyright © 2017. Published by Elsevier B.V.

  4. In Situ Synthesis of Al-Si-Cu Alloy During Brazing Process and Mechanical Property of Brazing Joint

    Directory of Open Access Journals (Sweden)

    LONG Wei-min

    2016-06-01

    Full Text Available The Al-Si-Cu alloy system is considered to be a promising choice of filler metal for aluminium alloys brazing due to its high strength and low melting point. The greatest obstacle is its lack of plastic forming ability and being difficult to be processed by conventional methods. This disadvantage is ascribed to the considerable amount of brittle CuAl2 intermetallic compound which forms when alloy composition is around the ternary eutectic point. In order to overcome this deficiency, authors of this article proposed to synthesize Al-Si-Cu filler metal by using in situ synthesis method, and the structure and properties of brazing joints were studied. The results show that AlSi alloy is used as the wrap layer, and CuAl alloy is used as the powder core in the composite brazing wire, the two alloys have similar melting points. The machinability of the composite brazing wire is much superior to the traditional Al-Si-Cu filler metal. During the induction brazing of 3A21 alloy, when using AlSi-CuAl composite filler wire, AlSi and CuAl alloys melt almost simultaneously, then after short time holding, Al-Si-Cu braze filler is obtained, the brazing seam has uniform composition and good bonding interface, also, the shearing strength of the brazing joints is higher than the joint brazed by conventional Al-Si-Cu filler metal.

  5. Biodegradation of CuTETA, an effluent by-product in mineral processing.

    Science.gov (United States)

    Cushing, Alexander M L; Kelebek, Sadan; Yue, Siqing; Ramsay, Juliana A

    2018-04-13

    Polyamines such as triethylenetetramine (TETA) and other amine chelators are used in mineral processing applications. Formation of heavy metal complexes of these reagents as a by-product in effluent water is a recent environmental concern. In this study, Paecilomyces sp. was enriched from soil on TETA as the sole source of carbon and nitrogen and was found to degrade > 96 and 90% CuTETA complexes at initial concentrations of 0.32 and 0.79 mM respectively, following 96-h incubation. After destabilization, most of the copper (> 78%) was complexed extracellularly and the rest was associated with the cell. Mass spectroscopy results provided confirmation that copper re-complexed with small, extracellular, and organic molecules. There are no reports in the literature that Paecilomyces or any other organism can grow on TETA or CuTETA. This study is the first to show that biological destabilization of CuTETA complexes in mineral processing effluents is feasible.

  6. Atomistic scale nanoscratching behavior of monocrystalline Cu influenced by water film in CMP process

    Science.gov (United States)

    Shi, Junqin; Chen, Juan; Fang, Liang; Sun, Kun; Sun, Jiapeng; Han, Jing

    2018-03-01

    The effect of water film on the nanoscratching behavior of monocrystalline Cu was studied by molecular dynamics (MD) simulation. The results indicate that the friction force acting on abrasive particle increases due to the resistance of water film accumulating ahead of particle, but the water film with lubrication decreases friction force acting on Cu surface. The accumulation of water molecules around particle causes the anisotropy of ridge and the surface damage around the groove, and the water molecules remaining in the groove lead to the non-regular groove structure. The dislocation evolution displays the re-organization of the dislocation network in the nanoscratching process. The evaluation of removal efficiency shows the number of removed Cu atoms decreases with water film thickness. It is considered that an appropriate rather than a high removal efficiency should be adopted to evaluate the polishing process in real (chemical mechanical polishing) CMP. These results are helpful to reveal the polishing mechanism under the effect of water film from physical perspective, which benefits the development of ultra-precision manufacture and miniaturized components, as well as the innovation of CMP technology.

  7. Loss mechanisms in hydrazine-processed Cu2ZnSn(Se,S)4 solar cells

    Science.gov (United States)

    Gunawan, Oki; Todorov, Teodor K.; Mitzi, David B.

    2010-12-01

    We present a device characterization study for hydrazine-processed kesterite Cu2ZnSn(Se,S)4 (CZTSSe) solar cells with a focus on pinpointing the main loss mechanisms limiting device efficiency. Temperature-dependent study and time-resolved photoluminescence spectroscopy on these cells, in comparison to analogous studies on a reference Cu(In,Ga)(Se,S)2 (CIGS) cell, reveal strong recombination loss at the CZTSSe/CdS interface, very low minority-carrier lifetimes, and high series resistance that diverges at low temperature. These findings help identify the key areas for improvement of these CZTSSe cells in the quest for a high-performance indium- and tellurium-free solar cell.

  8. Efficient Destruction of Pollutants in Water by a Dual-Reaction-Center Fenton-like Process over Carbon Nitride Compounds-Complexed Cu(II)-CuAlO2.

    Science.gov (United States)

    Lyu, Lai; Yan, Dengbiao; Yu, Guangfei; Cao, Wenrui; Hu, Chun

    2018-04-03

    Carbon nitride compounds (CN) complexed with the in-situ-produced Cu(II) on the surface of CuAlO 2 substrate (CN-Cu(II)-CuAlO 2 ) is prepared via a surface growth process for the first time and exhibits exceptionally high activity and efficiency for the degradation of the refractory pollutants in water through a Fenton-like process in a wide pH range. The reaction rate for bisphenol A removal is ∼25 times higher than that of the CuAlO 2 . According to the characterization, Cu(II) generation on the surface of CuAlO 2 during the surface growth process results in the marked decrease of the surface oxygen vacancies and the formation of the C-O-Cu bridges between CN and Cu(II)-CuAlO 2 in the catalyst. The electron paramagnetic resonance (EPR) analysis and density functional theory (DFT) calculations demonstrate that the dual reaction centers are produced around the Cu and C sites due to the cation-π interactions through the C-O-Cu bridges in CN-Cu(II)-CuAlO 2 . During the Fenton-like reactions, the electron-rich center around Cu is responsible for the efficient reduction of H 2 O 2 to • OH, and the electron-poor center around C captures electrons from H 2 O 2 or pollutants and diverts them to the electron-rich area via the C-O-Cu bridge. Thus, the catalyst exhibits excellent catalytic performance for the refractory pollutant degradation. This study can deepen our understanding on the enhanced Fenton reactivity for water purification through functionalizing with organic solid-phase ligands on the catalyst surface.

  9. Processing of Cu-Cr alloy for combined high strength and high conductivity

    Directory of Open Access Journals (Sweden)

    A.O Olofinjanaa

    2017-11-01

    Full Text Available High strength and high conductivity (HSHC are two intrinsic properties difficult to combine in metallic alloy design because; almost all strengthening mechanisms also lead to reduced conductivity. Precipitation hardening by nano-sized precipitates had proven to be the most adequate way to achieve the optimum combination of strength and conductivity in copper based alloys. However, established precipitation strengthened Cu- alloys are limited to very dilute concentration of solutes thereby limiting the volume proportion hardening precipitates. In this work, we report the investigation of the reprocessing of higher Cr concentration Cu- based alloys via rapid solidification. It is found that the rapid solidification in the as-cast ribbon imposed combined solution extension and ultra-refinement of Cr rich phases. X-ray diffraction evidences suggest that the solid solution extension was up to 6wt%Cr. Lattice parameters determined confirmed the many folds extension of solid solution of Cr in Cu.  Thermal aging studies of the cast ribbons indicated that peak aging treatments occurred in about twenty minutes. Peak aged hardness ranged from about 200 to well over 300Hv. The maximum peak aged hardness of 380Hv was obtained for alloy containing 6wt.%Cr but with conductivity of about 50%IACS. The best combined strength/conductivity was obtained for 4wt.%Cr  alloy with hardness of 350HV and conductivity of 80% IACS. The high strengths observed are attributed to the increased volume proportion of semi-coherent Cr rich nano-sized precipitates that evolved from the supersaturated solid solution of Cu-Cr that was achieved from the high cooling rates imposed by the ribbon casting process. The rapid overaging of the high Cr concentration Cu-Cr alloy is still a cause for concern in optimising the process for reaching peak HSHC properties. It is still important to investigate a microstructural design to slow or severely restrict the overaging process. The optimum

  10. Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Shafarman, William N. [Univ. of Delaware, Newark, DE (United States)

    2015-10-12

    This project “Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells”, completed by the Institute of Energy Conversion (IEC) at the University of Delaware in collaboration with the Department of Chemical Engineering at the University of Florida, developed the fundamental understanding and technology to increase module efficiency and improve the manufacturability of Cu(InGa)(SeS)2 films using the precursor reaction approach currently being developed by a number of companies. Key results included: (1) development of a three-step H2Se/Ar/H2S reaction process to control Ga distribution through the film and minimizes back contact MoSe2 formation; (2) Ag-alloying to improve precursor homogeneity by avoiding In phase agglomeration, faster reaction and improved adhesion to allow wider reaction process window; (3) addition of Sb, Bi, and Te interlayers at the Mo/precursor junction to produce more uniform precursor morphology and improve adhesion with reduced void formation in reacted films; (4) a precursor structure containing Se and a reaction process to reduce processing time to 5 minutes and eliminate H2Se usage, thereby increasing throughput and reducing costs. All these results were supported by detailed characterization of the film growth, reaction pathways, thermodynamic assessment and device behavior.

  11. Influences on Distribution of Solute Atoms in Cu-8Fe Alloy Solidification Process Under Rotating Magnetic Field

    Science.gov (United States)

    Zou, Jin; Zhai, Qi-Jie; Liu, Fang-Yu; Liu, Ke-Ming; Lu, De-Ping

    2018-05-01

    A rotating magnetic field (RMF) was applied in the solidification process of Cu-8Fe alloy. Focus on the mechanism of RMF on the solid solution Fe(Cu) atoms in Cu-8Fe alloy, the influences of RMF on solidification structure, solute distribution, and material properties were discussed. Results show that the solidification behavior of Cu-Fe alloy have influenced through the change of temperature and solute fields in the presence of an applied RMF. The Fe dendrites were refined and transformed to rosettes or spherical grains under forced convection. The solute distribution in Cu-rich phase and Fe-rich phase were changed because of the variation of the supercooling degree and the solidification rate. Further, the variation in solute distribution was impacted the strengthening mechanism and conductive mechanism of the material.

  12. The defect structures and mechanical properties of Cu and Cu–Al alloys processed by split Hopkinson pressure bar

    International Nuclear Information System (INIS)

    Tao, Jingmei; Yang, Kai; Xiong, Haiwu; Wu, Xiaoxiang; Zhu, Xinkun; Wen, Cuie

    2013-01-01

    Pure Cu, Cu-5 at%Al, Cu-10 at%Al and Cu-15 at%Al with different stacking fault energy (SFE) of 78, 37, 7 and 5 mJ/m 2 , respectively, were processed through split Hopkinson pressure bar (SHPB) with the strain rate of 10 3 /sec. The influence of high strain rate on the evolution of microstructures and mechanical properties of Cu and Cu–Al alloys was investigated. X-ray diffraction measurements indicate that, the microstructures of Cu and Cu–Al alloys have been refined to the nano scale after deformed by SHPB, and with decreasing SFE, the average grain size decreases gradually from 72 to 40 nm, while the dislocation density increases from 0.55×10 14 to 4.4×10 14 m −2 and the twin density increases from 0.04% to 1.07%. The formation of deformation twins is an additional factor that contributes to the microhardness and strength of Cu and Cu–Al alloys except the solid solution strengthening effect. Cu-15 at%Al has the biggest strain hardening rate at larger strains due to its lowest SFE which results in the highest twin density. The results confirm that lower SFE improves both strength and strain hardening rate of materials

  13. Significance of stacking fault energy on microstructural evolution in Cu and Cu-Al alloys processed by high-pressure torsion

    Science.gov (United States)

    An, X. H.; Lin, Q. Y.; Wu, S. D.; Zhang, Z. F.; Figueiredo, R. B.; Gao, N.; Langdon, T. G.

    2011-09-01

    Disks of pure Cu and several Cu-Al alloys were processed by high-pressure torsion (HPT) at room temperature through different numbers of turns to systematically investigate the influence of the stacking fault energy (SFE) on the evolution of microstructural homogeneity. The results show there is initially an inhomogeneous microhardness distribution but this inhomogneity decreases with increasing numbers of turns and the saturation microhardness increases with increasing Al concentration. Uniform microstructures are more readily achieved in materials with high or low SFE than in materials with medium SFE, because there are different mechanisms governing the microstructural evolution. Specifically, recovery processes are dominant in high or medium SFE materials, whereas twin fragmentation is dominant in materials having low SFE. The limiting minimum grain size (d min) of metals processed by HPT decreases with decreasing SFE and there is additional evidence suggesting that the dependence of d min on the SFE decreases when the severity of the external loading conditions is increased.

  14. Laser Trimming of CuAlMo Thin-Film Resistors: Effect of Laser Processing Parameters

    Science.gov (United States)

    Birkett, Martin; Penlington, Roger

    2012-08-01

    This paper reports the effect of varying laser trimming process parameters on the electrical performance of a novel CuAlMo thin-film resistor material. The films were prepared on Al2O3 substrates by direct-current (DC) magnetron sputtering, before being laser trimmed to target resistance value. The effect of varying key laser parameters of power, Q-rate, and bite size on the resistor stability and tolerance accuracy were systematically investigated. By reducing laser power and bite size and balancing this with Q-rate setting, significant improvements in resistor stability and resistor tolerance accuracies of less than ±0.5% were achieved.

  15. Pb, Cd, Cu and Zn biogeochemical behaviour and biological transfer processes in the Northwestern Mediterranean

    International Nuclear Information System (INIS)

    Nicolas, E.; Marty, J.C.; Miquel, J.C.; Fowler, S.W.

    1999-01-01

    Cd, Pb, Cu and Zn concentrations were determined in planktonic organisms (Salps, copepods), their associated faecal pellets and in particles collected at 200 and 2000 m depth in sediment traps moored in the Ligurian Sea. Al and P were also measured and taken as tracers of lithogenic and biogenic components, respectively. The aim of this work was to determine the fluxes of trace metals in the Ligurian Sea and their variations with depth, and to to assess the biogeochemical behaviour of elements having, for some of them, an anthropogenic origin, by the study of biologically-mediated uptake and removal processes

  16. Electrochemical properties of CuO hollow nanopowders prepared from formless Cu–C composite via nanoscale Kirkendall diffusion process

    Energy Technology Data Exchange (ETDEWEB)

    Won, Jong Min [Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713 (Korea, Republic of); Kim, Jong Hwa [Daegu Center, Korea Basic Science Institute, 80 Daehakro Bukgu, Daegu 702-701 (Korea, Republic of); Choi, Yun Ju [Suncheon Center, Korea Basic Science Institute, Suncheon 540-742 (Korea, Republic of); Cho, Jung Sang [Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713 (Korea, Republic of); Kang, Yun Chan, E-mail: yckang@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713 (Korea, Republic of)

    2016-06-25

    Hollow CuO nanopowders are prepared using a simple spray drying process that relied on nanoscale Kirkendall diffusion; these nanopowders have potential applications in lithium-ion batteries. Citric acid is used as both the carbon source material and chelating agent and plays a key role in the preparation of the hollow nanopowders. The formless Cu–C composite that formed as an intermediate product transforms into slightly aggregated CuO hollow nanopowders after post-treatment at 300 and 400 °C under an air atmosphere. The CuO hollow nanopowders exhibit higher initial discharge capacities and better cycling performances than those of the filled-structured CuO nanopowders, which are prepared at a post-treatment temperature of 500 °C under an air atmosphere. The discharge capacities of the CuO nanopowders post-treated at 300, 400, and 500 °C for the 150{sup th} cycle at a current density of 1 A g{sup −1} are 793, 632, and 464 mA h g{sup −1}, respectively, and their capacity retentions calculated from the maximum discharge capacities are 88, 80, and 73%, respectively. The CuO nanopowders with hollow structures exhibit better structural stability for repeated lithium insertion and desertion processes than those with filled structures. - Highlights: • Hollow CuO nanopowders are prepared using a simple spray drying process. • Cu–C composite transforms into CuO hollow nanopowders by Kirkendall diffusion. • Hollow CuO nanopowders show good electrochemical properties for lithium-ion storage.

  17. Electrical and photovoltaic characteristics of CuInSe2 thin films processed by nontoxic Cu–In precursor solutions

    International Nuclear Information System (INIS)

    Choi, Ik Jin; Jang, Jin Woo; Lee, Seung Min; Yeon, Deuk Ho; Jo, Yeon Hwa; Lee, Myung Ho; Cho, Yong Soo; Yun, Jae Ho; Yoon, Kyung Hoon

    2013-01-01

    Nontoxic Cu–In solution-processed CuInSe 2 absorber thin films and resultant photovoltaic cells have been investigated. Acetate-based Cu–In precursors having different Cu/In ratios of 0.8–1.2 were deposited by spin-coating and then selenized in Se atmosphere up to 550 °C. Single tetragonal CuInSe 2 phase was dominantly obtained regardless of Cu/In ratios, with the segregation of Cu 2−x Se secondary phase only in the case of Cu-rich films as evidenced by Raman spectra. The films with the 1.1 ratio demonstrated a larger grain size of ∼1.06 µm with an increased carrier concentration of ∼1.7 × 10 18 cm −3 and a decreased band gap of ∼1.02 eV, compared to the values obtained for Cu-deficient absorber films. The resultant best cell efficiency was ∼3.1% for the absorber having the 1.1 ratio, suggesting a potential of this simple spin-coating method as an alternative to typical vacuum processes. (paper)

  18. Flux motion and anisotropy in melt-processed YBa2Cu3O7-δ

    International Nuclear Information System (INIS)

    Koblischka, M.R.; Schuster, Th.; Kuhn, H.; Gluecker, M.; Dalen, A.J.J. van; Griessen, R.; Kronmueller, H.

    1993-01-01

    The melt-processing of YBa 2 Cu 3 O 7-δ - and Bi 2 Sr 2 CaCu 2 O 8+δ -samples offers a promising way to achieve high critical current densities also in bulk materials. This is of main interest for strong current applications of high-T c superconductors. Interesting basic features can also be studied using melt-processed samples, from which good quality crystals can be cut out. For example, such samples make it possible to do measurements in various angular positions without drastically changing the demagnetizing factors along the main crystallographic axes. Usually, most measurements studying the influence of intrinsic pinning have been carried out on thin films (1). To observe flux distributions in superconductors, we use the High Resolution Faraday (HRF) technique. This enables one to local observations of flux distributions, combining a high spatial resolution (∼0.8 μm) with the unique possibility to observe dynamic processes in the flux distribution such as flux motion due to flux creep (2,3). Additionally, torque measurements up to 7 T in the temperature range 10 - 77 K have been carried out on the identical sample for a comparison of the local HRF data with integral critcal current torque data. (orig.)

  19. Neutron-rich isotopes around the r-process 'waiting-point' nuclei 2979Cu50 and 3080Zn50

    International Nuclear Information System (INIS)

    Kratz, K.L.; Gabelmann, H.; Pfeiffer, B.; Woehr, A.

    1991-01-01

    Beta-decay half-lives (T 1/2 ) and delayed-neutron emission probabilities (P n ) of very neutron-rich Cu to As nuclei have been measured, among them the new isotopes 77 Cu 48 , 79 Cu 50 , 81 Zn 51 and 84 Ga 53 . With the T 1/2 and P n -values of now four N≅50 'waiting-point' nuclei known, our hypothesis that the r-process has attained a local β-flow equilibrium around A≅80 is further strengthened. (orig.)

  20. Stress/strain characteristics of Cu alloy sheath in situ processed MgB2 superconducting wires

    International Nuclear Information System (INIS)

    Katagiri, Kazumune; Kasaba, Koichi; Shoji, Yoshitaka

    2005-01-01

    The mechanical properties of copper and copper alloy (Cu-Zr, Cu-Be and Cu-Cr) sheath in situ PIT-processed MgB 2 superconducting wires were studied at room temperature (RT) and 4.2 K. The effects of stress-strain on the critical current (I c ) of the wires have also been studied at 4.2 K and in magnetic fields up to 5 T. It has been clarified that alloying the Cu sheath significantly increases the yield and flow stresses of the wires at both RT and 4.2 K. The 0.5% flow stresses of the Cu alloy sheath wire were 147-237 MPa, whereas that of Cu was 55 MPa. At RT, serration corresponding to multiple cracking was observed around a strain of 0.4% and the stress-strain curves saturated beyond that point. The strain dependence of I c prior to the critical strain (ε irr ) was different depending on the magnetic field; being almost constant at 2 T and increasing with strain at 5 T. The I c decreased beyond ε irr , which is much larger for Cu alloy sheath wires as compared to Cu sheath wire. This is due to the difference in the residual compressive strain in the MgB 2 core during cooling from the heat-treatment temperature to 4.2 K, which is determined through relaxation by yielding in the sheath materials. The transverse compression tests revealed that the I c of the Cu alloy sheath wire did not degrade up to 314 MPa, which is also higher than that of Cu sheath wire. (author)

  1. Numerical Analysis of Warpage Induced by Thermo-Compression Bonding Process of Cu Pillar Bump Flip Chip Package

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Oh Young; Jung, Hoon Sun; Lee, Jung Hoon; Choa, Sung-Hoon [Seoul Nat’l Univ. of Science and Technology, Seoul (Korea, Republic of)

    2017-06-15

    In flip chip technology, the conventional solder bump has been replaced with a copper (Cu) pillar bump owing to its higher input/output (I/O) density, finer pitch, and higher reliability. However, Cu pillar bump technology faces several issues, such as interconnect shorting and higher low-k stress due to stiffer Cu pillar structure when the conventional reflow process is used. Therefore, the thermal compression bonding (TCB) process has been adopted in the flip chip attachment process in order to reduce the package warpage and stress. In this study, we investigated the package warpage induced during the TCB process using a numerical analysis. The warpage of the TCB process was compared with that of the reflow process.

  2. A flexible angle sensor made from MWNT/CuO/Cu{sub 2}O nanocomposite films deposited by an electrophoretic co-deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Toboonsung, Buppachat, E-mail: buppachattt@yahoo.co.th [Physics and General Science Program, Faculty of Science and Technology, Nakhon Ratchasima Rajabhat University, Nakhon Ratchasima 30000 (Thailand); Singjai, Pisith, E-mail: singjai@hotmail.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai, 50200 (Thailand)

    2012-08-25

    Highlights: Black-Right-Pointing-Pointer MWNT/CuO/Cu{sub 2}Onanocomposite films were coated on a PET sheet. Black-Right-Pointing-Pointer The film resistance and application as angle sensor were investigated. Black-Right-Pointing-Pointer Thesensor showed a linear relation between the film resistance and the bending angle. Black-Right-Pointing-Pointer A minimum loop area and a high stability in sensitivity over a thousand bending cycles were obtained. - Abstract: A flexible angle sensor was prepared using an electrophoretic co-deposition process to form nanocomposite networks of multi-wall carbon nanotube/cupric oxide/cuprous oxide (MWNT/CuO/Cu{sub 2}O) on a polyethylene terephthalate (PET) sheet. The deposition method used copper and stainless steel electrodes, and the effects of varying of electrode separation, MWNT concentration in deionized water, voltage and deposition time were studied. The film resistance of the as-deposited samples decreased with increasing the MWNT concentration up to 0.3 mg/ml. The angle sensor showed a linear relation between the film resistance and the bending angle, a relationship that was illustrated with loop area and sensitivity data. The best angle sensor was successfully made with an electrode separation of 8 mm, a concentration of 0.3 mg/ml, a voltage of 10 V and a deposition time of 3 h, parameters that resulted in a minimum loop area and the most stability in sensitivity over a thousand bending cycles.

  3. Critical current properties in superconducting melt processed Y-Ba-Cu-O

    International Nuclear Information System (INIS)

    Matsushita, Teruo

    1993-01-01

    The critical current density in bulk superconducting Y-Ba-Cu-O has been remarkably improved by employing the so-called melt process. However, its value is still far below those reported in single-crystalline thin films. Important key factors that determine the critical current density are the flux pinning mechanism and defective structures such as cracks or weak links. In this article, these factors in melt-processed Y-Ba-Cu-O are argued from various measurements of the critical current density on the microstructure dependence, the magnetic field dependence, the temperature dependence, the history effect, the longitudinal field effect and the imaginary ac susceptibility. As for the pinning mechanism, it is concluded that the dominant pinning centers in the high temperature region around 77 K are normal 211 (Y 2 BaCuO 5 ) particles, while small defects such as lattice defects or oxygen deficiencies seem to be dominant in the lower temperature region. It is suggested that much finer normal particles should be introduced in order to improve the critical current density especially at higher temperatures. From the rapid decrease of the critical current density with elevating temperature below 30 K, some kind of weak links are considered to still remain in these materials. However, the observed critical current density did not depend on the history of application of the magnetic field and a large enhancement of the critical current density was observed in the longitudinal field geometry at 4.2 K. These results suggest that the weak links in these materials are of much different kind from those at large angle grain boundaries in sintered polycrystalline materials. From the X-ray diffraction measurements, a domain structure of a mean domain size of about 100 μm was found. These domain boundaries may cause weak links in melt-processed Y-Ba-Cu-O. It is also shown that the typical size of channels of flowing current can be obtained by the imaginary ac susceptibility

  4. The fate of sulphur in the Cu-based Chemical Looping with Oxygen Uncoupling (CLOU) Process

    International Nuclear Information System (INIS)

    Adánez-Rubio, Iñaki; Abad, Alberto; Gayán, Pilar; García-Labiano, Francisco; Diego, Luis F. de; Adánez, Juan

    2014-01-01

    Highlights: • 15 h of CLOU experiments using lignite were carried out in a continuously unit. • The sulphur split between fuel- and air-reactor streams in the process was analysed. • Most of the sulphur introduced with the fuel exits as SO 2 at the fuel-reactor. • The use of a carbon separation system to reduce the S emission was evaluated. • Coals with high S content can be burnt in a CLOU process with a Cu-based material. - Abstract: The Chemical Looping with Oxygen Uncoupling (CLOU) process is a type of Chemical Looping Combustion (CLC) technology that allows the combustion of solid fuels with air, as with conventional combustion, through the use of oxygen carriers that release gaseous oxygen inside the fuel reactor. The aim of this work was to study the behaviour of the sulphur present in fuel during CLOU combustion. Experiments using lignite as fuel were carried out in a continuously operated 1.5 kW th CLOU unit during more than 15 h. Particles containing 60 wt.% CuO on MgAl 2 O 4 , prepared by spray drying, were used as the oxygen carrier in the CLOU process. The temperature in the fuel reactor varied between 900 and 935 °C. CO 2 capture, combustion efficiency and the sulphur split between fuel and air reactor streams in the process were analysed. Complete combustion of the fuel to CO 2 and H 2 O was found in all experiments. Most of the sulphur introduced with the fuel exited as SO 2 at the fuel reactor outlet, although a small amount of SO 2 was measured at the air reactor outlet. The SO 2 concentration in the air reactor exit flow decreased as the temperature in the fuel reactor increased. A carbon capture efficiency of 97.6% was achieved at 935 °C, with 87.9 wt.% of the total sulphur exiting as SO 2 in the fuel reactor. Both the reactivity and oxygen transport capacity of the oxygen carrier were unaffected during operation with a high sulphur content fuel, and agglomeration problems did not occur. Predictions were calculated regarding the use

  5. Cu-Fe welding techniques by electromagnetic and electron beam welding processes

    International Nuclear Information System (INIS)

    Kumar, Satendra; Saroj, P.C.; Kulkarni, M.R.; Sharma, A.; Rajawat, R.K.; Saha, T.K.

    2015-01-01

    Electromagnetic welding being a solid state welding process has been found suitable for welding Copper and Iron which are conventionally very tricky. Owing to good electrical conductivity of both copper and iron, they are best suited combination for EM welding. For the experimental conditions presented above, 1.0 mm wall thickness of Cu tube was lap welded to Fe disc. A heavy duty four disc stainless steel coil was used for electromagnetic welding of samples. MSLD of the welded samples indicated leak proof joints. Metallographic examination of the welds also revealed defect free interfaces. Electron beam welding is also a non-conventional welding process used for joining dissimilar materials. Autogenous welding of the above specimen was carried out by EBW method for the sake of comparison. A characterization analysis of the above mentioned joining processes will be discussed in the paper. (author)

  6. Microstructure and mechanical properties of Cu/SiC metal matrix composite fabricated via friction stir processing

    International Nuclear Information System (INIS)

    Akramifard, H.R.; Shamanian, M.; Sabbaghian, M.; Esmailzadeh, M.

    2014-01-01

    Highlights: • Designing a net hole was effective to achieve uniform distribution SiC particles and prevent agglomeration of them. • SZ has fine and equiaxed grains and distribution of SiC particles in the matrix is almost uniform. • No intermetallic compound was formed after FSP. • In comparison to pure Cu, Cu/SiC composite shows higher hardness and better wear behavior. - Abstract: In the present investigation, pure Cu sheets were reinforced with 25 μm SiC particles to fabricate a composite surface layer by friction stir processing (FSP). In order to improve distribution of reinforcing SiC particles, a net of holes were designed by drill on the surface of pure Cu sheet. For evaluation of microstructure, Optical Microscope (OM) and Scanning Electron Microscope (SEM) were used. Microstructural observation confirmed fine and equiaxed grains in the stir zone (SZ) and showed that SiC particles act as heterogeneous nucleation sites in the dynamic recrystallization of Cu grains. Moreover, agglomeration of particles was not observed and fine particles had a good distribution in SZ. In the SEM micrographs, porosities were detected as microstructure defects. Microhardness measurements showed that surface hardness was two times as high as that of substrate. The rotational wear tests demonstrated that use of SiC particles enhanced wear resistance and increased average friction coefficient of pure Cu. No intermetallic compound was found in Cu/SiC composite as revealed by XRD analysis

  7. Microstructure within domains of melt-processed YBa2Cu3O7-x superconductors

    International Nuclear Information System (INIS)

    Alexander, K.B.; Goyal, A.; Kroeger, D.M.; Selvamanickam, V.; Salama, K.

    1992-01-01

    The microstructure within single domains of melt-processed YBa 2 Cu 3 O 7-x (1:2:3) material has been examined. Rather than composing a ''brick-wall'' structure, the stacked, parallel platelets within the domains are actually portions of a single crystal. A growth mechanism is proposed that is consistent with the observed microstructural features. The anisotropic nature of the growth of 1:2:3 results in gaps separating the platelets. The gaps, however, terminate within domains, resulting in interconnected single-crystalline material. The absence of weak-link behavior for current flow along the c axis and the high critical-current densities observed within domains of melt-processed 1:2:3 material are readily explained by the fact that current flow is solely through single-crystalline material

  8. Process parameters, orientation, and functional properties of melt-processed bulk Y-Ba-Cu-O superconductors

    International Nuclear Information System (INIS)

    Zakharchenko, I.V.; Terryll, K.M.; Rao, K.V.; Balachandran, U.

    1995-03-01

    This study compared the microstructure, texturing, and functional properties (critical currents) of YBa 2 Cu 3 O 7-x -based bulk pellets that were prepared by the quench-melt-growth-process (QMGP), melt-textured growth (MTG), and conventional solid-state reaction (SSR) approaches. Using two X-ray diffraction (XRD) methods, θ-2θ, and rocking curves, the authors found that the individual grains of two melt-processed pellets exhibited remarkable preferred orientational alignment (best rocking curve width = 3.2 degree). However, the direction of the preferred orientation among the grains was random. Among the three types of bulk materials studied, the QMGP sample was found to have the best J c values, ∼ 4,500 A/cm 2 at 77 K in a field of 2 kG, as determined from SQUID magnetic data

  9. Melt processing of the Bi2Sr2CaCu2Oy superconductor in oxygen and argon atmospheres

    International Nuclear Information System (INIS)

    Holesinger, T.G.; Miller, D.J.; Chumbley, L.S.

    1992-08-01

    Solidification and subsequent annealing of Bi 2 Sr 2 CaCu 2 O y (2212) in oxygen and argon atmospheres were investigated in order to identify alternative processing routes for controlling microstructures and superconducting properties. In addition to 2212, several other phases formed on cooling in O 2 and did not disappear upon subsequent annealing. Crystallization in Ar resulted in a divorced eutetic structure of Bi 2 Sr 3-x Ca x O y and Cu 2 O/CuO. The superconductor was formed on subsequent anneals. Samples melted in Ar and then annealed generally possessed a more uniform microstructure compared with samples that were melted in oxygen and annealed. Compositional measurements of the 2212 phase suggest that CaO segregation in the melt may be minimized with an overall composition such as Bi 2.15 Sr 2 Ca 0.85 Cu 2 O y

  10. An Alternative Cu-Based Bond Layer for Electric Arc Coating Process

    Science.gov (United States)

    Fadragas, Carlos R.; Morales, E. V.; Muñoz, J. A.; Bott, I. S.; Lariot Sánchez, C. A.

    2011-12-01

    A Cu-Al alloy has been used as bond coat between a carbon steel substrate and a final coating deposit obtained by applying the twin wire electric arc spraying coating technique. The presence of a copper-based material in the composite system can change the overall temperature profile during deposition because copper exhibits a thermal conductivity several times higher than that of the normally recommended bond coat materials (such as nickel-aluminum alloys or nickel-chromium alloys). The microstructures of 420 and 304 stainless steels deposited by the electric arc spray process have been investigated, focusing attention on the deposit homogeneity, porosity, lamellar structure, and microhardness. The nature of the local temperature gradient during deposition can strongly influence the formation of the final coating deposit. This study presents a preliminary study, undertaken to investigate the changes in the temperature profile which occur when a Cu-Al alloy is used as bond coat, and the possible consequences of these changes on the microstructure and adhesion of the final coating deposit. The influence of the thickness of the bond layer on the top coating temperature has also been also evaluated.

  11. Antibacterial property of CuCrO{sub 2} nanopowders prepared by a self-combustion glycine nitrate process

    Energy Technology Data Exchange (ETDEWEB)

    Nien, Yung-Tang, E-mail: ytnien@nfu.edu.tw [Deparment of Materials Science and Engineering, National Formosa University, Yunlin, 63201, Taiwan (China); Hu, Mon-Ru [Deparment of Materials Science and Engineering, National Formosa University, Yunlin, 63201, Taiwan (China); Chiu, Te-Wei [Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei, 10608, Taiwan (China); Chu, Jaw-Shiow [Bioresource Collection and Research Center, Food Industry Research and Development Institute, Hsinchu, 30062, Taiwan (China)

    2016-08-15

    Porous CuCrO{sub 2} nanopowders were prepared via glycine nitrate process (GNP) at 175 °C in ambient air. The X-ray diffraction patterns showed a pure delafossite phase of CuCrO{sub 2} with numerous broad peaks, indicating a crystallite size of approximately 20 nm. The surface area of the CuCrO{sub 2} nanopowders was larger than 50 m{sup 2}/g, nearly 100 times greater than that of bulk powders (0.47 m{sup 2}/g). Pathogenic Gram-negative bacteria Escherichia coli (E. coli) were chosen as the antibacterial evaluation indicators for both the nanopowders and bulk powders. The results showed that 1750 ppm nanopowders inhibited the growth of E. coli. As a control, the bulk powders showed a normal growth profile. The antibacterial property of the CuCrO{sub 2} nanopowders can be attributed to the extremely large surface area, which induces rapid release of Cu ions and strong adhesion of nanopowders to bacteria. - Highlights: • CuCrO{sub 2} nanopowders was prepared by low-temperature glycine nitrate process. • 1250–1500 ppm of CuCrO{sub 2} nanopowders were found to depress the growth of Escherichia coli. • Bulk powders by the solid state reaction exhibited no antibacterial property. • The antibacterial property of nanopowders was attributed to rapid Cu ion releases. • Heavy adhesion of nanopowders to bacteria also resulted in antibacterial property.

  12. The Use of Al, Cu, and Fe in an Integrated Electrocoagulation-Ozonation Process

    Directory of Open Access Journals (Sweden)

    Carlos E. Barrera Díaz

    2015-01-01

    Full Text Available This study presents the effect of supplying electrochemically generated metallic ions (Al, Cu, and Fe during an ozonation process for treating industrial wastewater. The pollutant removal efficiencies of the electrocoagulation (EC, ozonation, and coupled EC-ozonation processes were examined by the decrease in chemical oxygen demand (COD as a function of treatment time. The EC was performed in a raw industrial wastewater, which has contributions from 39 chemical, 34 metal finishing, 22 textile, 11 leather, and 5 automotive plants, at pH (7.3 using a current density of 150 A/m2 for 60 min, giving a 45% reduction in COD. The ozonation process was more effective with the same wastewater, reducing the COD by 52% after 60 min of treatment. Combining the EC and ozonation methods resulted in a synergistic process that improves the reduction of COD in a shorter time. In just 12 min the integrated process reduced the COD by 88%. Thus, the combination of EC and ozonation processes improves noticeably the wastewater quality, decreasing the treatment time and also reducing the sludge production.

  13. Phase evolution and thermal stability of 2 Mg–Cu alloys processed by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Martínez, C., E-mail: carola.martinezu@usach.cl [Departamento de Ingeniería Metalúrgica, Facultad de Ingeniería, Universidad de Santiago de Chile, Av. Lib. Bernardo O’Higgins 3363, Casilla de correo 10233, Santiago (Chile); Ordoñez, S., E-mail: stella.ordonez@usach.cl [Departamento de Ingeniería Metalúrgica, Facultad de Ingeniería, Universidad de Santiago de Chile, Av. Lib. Bernardo O’Higgins 3363, Casilla de correo 10233, Santiago (Chile); Guzmán, D. [Departamento de Ingeniería en Metalurgia, Facultad de Ingeniería, Universidad de Atacama y CRIDESAT, Av. Copayapu 485, Casilla de Correo 240, Copiapó (Chile); Serafini, D. [Departamento de Física, Facultad de Ciencia, Universidad de Santiago de Chile, Av. Lib. Bernardo O’Higgins 3363, Casilla de correo 307, Santiago (Chile); Iturriza, I. [CEIT, Manuel de Lardizábal 15, 20018 San Sebastián, España (Spain); Bustos, O. [Departamento de Ingeniería Metalúrgica, Facultad de Ingeniería, Universidad de Santiago de Chile, Av. Lib. Bernardo O’Higgins 3363, Casilla de correo 10233, Santiago (Chile)

    2013-12-25

    Highlights: •Study of phase evolution of elemental powders Mg and Cu by mechanical alloying. •The presence of an amorphous precursor which crystallizes to Mg{sub 2}Cu can be observed. •Establishing the sequence of phase transformations leading to the formation of Mg{sub 2}Cu. •The feasibility to obtain Mg{sub 2}Cu by means two possible routes has been established. -- Abstract: Phase evolution during mechanical alloying (MA) of elemental Mg and Cu powders and their subsequent heat treatment is studied. Elemental Mg and Cu powders in a 2:1 atomic ratio were mechanically alloyed in a SPEX 8000D mill using a 10:1 ball-to-powder ratio. X-ray diffraction (XRD) shows that the formation of the intermetallic Mg{sub 2}Cu takes place between 3 and 4 h of milling, although traces of elemental Cu are still present after 10 h of milling. The thermal behavior of different powder mixtures was evaluated by differential scanning calorimetry (DSC). The combination of DSC, heat treatment and XRD has shown a sequence of phase transformations that results in the intermetallic Mg{sub 2}Cu from an amorphous precursor. This amorphous phase is converted into Mg{sub 2}Cu by heating at low temperature (407 K). Short MA times and the formation of the amorphous precursor, together with its subsequent transformation into Mg{sub 2}Cu at low temperatures; represent an advantageous alternative route for its preparation.

  14. Decomplexation efficiency and mechanism of Cu(II)-EDTA by H2O2 coupled internal micro-electrolysis process.

    Science.gov (United States)

    Zhou, Dongfang; Hu, Yongyou; Guo, Qian; Yuan, Weiguang; Deng, Jiefan; Dang, Yapan

    2016-12-29

    Internal micro-electrolysis (IE) coupled with Fenton oxidation (IEF) was a very effective technology for copper (Cu)-ethylenediaminetetraacetic acid (EDTA) wastewater treatment. However, the mechanisms of Cu 2+ removal and EDTA degradation were scarce and lack persuasion in the IEF process. In this paper, the decomplexation and removal efficiency of Cu-EDTA and the corresponding mechanisms during the IEF process were investigated by batch test. An empirical equation and the oxidation reduction potential (ORP) index were proposed to flexibly control IE and the Fenton process, respectively. The results showed that Cu 2+ , total organic carbon (TOC), and EDTA removal efficiencies were 99.6, 80.3, and 83.4%, respectively, under the proper operation conditions of iron dosage of 30 g/L, Fe/C of 3/1, initial pH of 3.0, Fe 2+ /H 2 O 2 molar ratio of 1/4, and reaction time of 20 min, respectively for IE and the Fenton process. The contributions of IE and Fenton to Cu 2+ removal were 91.2 and 8.4%, respectively, and those to TOC and EDTA removal were 23.3, 25.1, and 57, 58.3%, respectively. It was found that Fe 2+ -based replacement-precipitation and hydroxyl radical (•OH) were the most important effects during the IEF process. •OH played an important role in the degradation of EDTA, whose yield and productive rate were 3.13 mg/L and 0.157 mg/(L min -1 ), respectively. Based on the intermediates detected by GC-MS, including acetic acid, propionic acid, pentanoic acid, amino acetic acid, 3-(diethylamino)-1,2-propanediol, and nitrilotriacetic acid (NTA), a possible degradation pathway of Cu-EDTA in the IEF process was proposed. Graphical abstract The mechanism diagram of IEF process.

  15. Production of diamond wire by Cu15 v-% Nb 'in situ' process

    International Nuclear Information System (INIS)

    Filgueira, M.; Pinatti, D.G.

    2001-01-01

    Diamond wires are cutting tools used in the slabbing of dimension stones, such as marbles and granites, as well as in cutting of concrete structures. This tool consists of a steel cable on which diamond annular segments (pearls) are mounted with spacing between them. This work has developed a new technological route to obtain the diamond wires, whose fabrication involves metal forming processes such as rotary forging and wire drawing, copper tubes restacking, and thermal treatments of sintering and recrystallization. It was idealized the use of Cu 15v% Nb composite wires as the high tensile strength cable, covered with an external cutting rope made of bronze 4wt% diamond composite, along the overall wire surface. Investigations were carried out on the mechanical behavior and on the microstructural evolution of the Cu 15 vol % Nb wires, which showed ultimate tensile strength (UTS) of 960 MPa and deformation of approximately 3,0 %. The cutting external rope of 1.84 mm in diameter showed UTS = 230 MPa. On the microstructural side aspect it was observed that the diamond crystals were uniformly distributed throughout the tool bulk in the several processing steps. Cutting tests were carried out starting with an external diamond rope of 1.93 mm in diameter, which cut a marble sectional area of 1188 cm 2 , and the tool degraded to a final diameter of 1.23 mm. For marble the 'in situ' wire showed a probable performance 4 times higher than the diamond saws, however their probable performance was about 5 to 8 times less than the conventional diamond wires due to the low abrasion resistance of the bronze matrix and the low adhesion between the pair bronze-diamond. (author)

  16. Influence of Oxygen Partial Pressure during Processing on the Thermoelectric Properties of Aerosol-Deposited CuFeO₂.

    Science.gov (United States)

    Stöcker, Thomas; Exner, Jörg; Schubert, Michael; Streibl, Maximilian; Moos, Ralf

    2016-03-24

    In the field of thermoelectric energy conversion, oxide materials show promising potential due to their good stability in oxidizing environments. Hence, the influence of oxygen partial pressure during synthesis on the thermoelectric properties of Cu-Delafossites at high temperatures was investigated in this study. For these purposes, CuFeO₂ powders were synthetized using a conventional mixed-oxide technique. X-ray diffraction (XRD) studies were conducted to determine the crystal structures of the delafossites associated with the oxygen content during the synthesis. Out of these powders, films with a thickness of about 25 µm were prepared by the relatively new aerosol-deposition (AD) coating technique. It is based on a room temperature impact consolidation process (RTIC) to deposit dense solid films of ceramic materials on various substrates without using a high-temperature step during the coating process. On these dense CuFeO₂ films deposited on alumina substrates with electrode structures, the Seebeck coefficient and the electrical conductivity were measured as a function of temperature and oxygen partial pressure. We compared the thermoelectric properties of both standard processed and aerosol deposited CuFeO₂ up to 900 °C and investigated the influence of oxygen partial pressure on the electrical conductivity, on the Seebeck coefficient and on the high temperature stability of CuFeO₂. These studies may not only help to improve the thermoelectric material in the high-temperature case, but may also serve as an initial basis to establish a defect chemical model.

  17. Comparison of Two Powder Processing Techniques on the Properties of Cu-NbC Composites

    Directory of Open Access Journals (Sweden)

    B. D. Long

    2014-01-01

    Full Text Available An in situ Cu-NbC composite was successfully synthesized from Cu, Nb, and C powders using ball milling and high pressure torsion (HPT techniques. The novelty of the new approach, HPT, is the combination of high compaction pressure and large shear strain to simultaneously refine, synthesize, and consolidate composite powders at room temperature. The HPTed Cu-NbC composite was formed within a short duration of 20 min without Fe contamination from the HPT’s die. High porosity of 3–9%, Fe and niobium oxidations, from grinding media and ethanol during ball milling led to low electrical conductivity of the milled Cu-NbC composite. The electrical conductivity of the HPTed Cu-NbC composite showed a value 50% higher than that of milled Cu-NbC composite of the same composition.

  18. Recurrent intergrowths in the topotactic reduction process of LaBaCuCoO5.2.

    Science.gov (United States)

    Ruiz-González, Luisa; Boulahya, Khalid; Parras, Marina; Alonso, José; González-Calbet, José M

    2002-12-16

    A new perovskite-related oxide with the LaBaCuCoO5.2 composition has been stabilised. Its structure can be described as formed by the recurrent intergrowth of two alternating blocks of YBaCuFeO5 (2ac, i.e., two-fold perovskite superlattice) and YBa2Fe3O8 (3ac) structural types. From the starting material LaBaCuCoO5.2-delta (delta = 0), the rigorous control of the oxygen content has allowed the stabilisation of three new five fold perovskite-related superstructures with the compositions delta = 0.4, 0.8 and 1.1, which can also be described as recurrent intergrowths of two blocks showing 2ac and 3ac periodicity. The reduction process takes place through the 3ac periodic blocks, when 0 topotactic reaction, since their basic structure is kept through the reduction process.

  19. Initial crystallization and growth in melt processing of large-domain YBa2Cu3Ox for magnetic levitation

    International Nuclear Information System (INIS)

    Shi, D.

    1994-10-01

    Crystallization temperature in YBa 2 Cu 3 O x (123) during peritectic reaction has been studied by differential thermal analysis (DTA) and optical microscopy. It has been found that YBa 2 Cu 3 O x experiences partial melting near 1,010 C during heating while crystallization takes place at a much lower temperature range upon cooling indicating a delayed nucleation process. A series of experiments have been conducted to search for the initial crystallization temperature in the Y 2 BaCuO x + liquid phase field. The authors have found that the slow-cool period (1 C/h) for the 123 grain texturing can start at as low as 960 C. This novel processing has resulted in high-quality, large-domain, strongly pinned 123 magnetic levitators

  20. Processing of CuInSe2-Based Solar Cells: Characterization of Deposition Processes in Terms of Chemical Reaction Analyses. Final Report, 6 May 1995 - 31 December 1998

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, T.J.; Stanbery, B.J.

    2001-07-16

    This project describes a novel rotating-disc reactor has been designed and built to enable modulated flux deposition of CuInSe2 and its related binary compounds. The reactor incorporates both a thermally activated source and a novel plasma-activated source of selenium vapor, which have been used for the growth of epitaxial and polycrystalline thin-film layers of CuInSe2. A comparison of the different selenium reactant sources has shown evidence of increases in its incorporation when using the plasma source, but no measurable change when the thermally activated source was used. We concluded that the chemical reactivity of selenium vapor from the plasma source is significantly greater than that provided by the other sources studied. Epitaxially grown CuInSe2 layers on GaAs, ZnTe, and SrF2 demonstrate the importance of nucleation effects on the morphology and crystallographic structure of the resulting materials. These studies have resulted in the first reported growth of the CuAu type-I crystallographic polytype of CuInSe2, and the first reported epitaxial growth of CuInSe2 on ZnTe. Polycrystalline binary (Cu,Se) and (In,Se) thin films have been grown, and the molar flux ratio of selenium to metals was varied. It is shown that all of the reported binary compounds in each of the corresponding binary phase fields can be synthesized by the modulated flux deposition technique implemented in the reactor by controlling this ratio and the substrate temperature. These results were employed to deposit bilayer thin films of specific (Cu,Se) and (In,Se) compounds with low melting-point temperature, which were used to verify the feasibility of synthesizing CuInSe2 by subsequent rapid-thermal processing. The studies of the influence of sodium during the initial stages of epitaxy have led to a new model to explain its influences based on the hypothesis that it behaves as a surfactant in the Cu-In-Se material system. This represents the first unified theory on the role of sodium

  1. Rapid processing method for solution deposited YBa2Cu3O7-δ thin films

    International Nuclear Information System (INIS)

    Dawley, J.T.; Clem, P.G.; Boyle, T.J.; Ottley, L.M.; Overmyer, D.L.; Siegal, M.P.

    2004-01-01

    YBa 2 Cu 3 O 7-δ (YBCO) films, deposited on buffered metal substrates, are the primary candidate for second-generation superconducting (SC) wires, with applications including expanded power grid transmission capability, compact motors, and enhanced sensitivity magnetic resonance imaging. Feasibility of manufacturing such superconducting wires is dependent on high processing speed, often a limitation of vapor and solution-based YBCO deposition processes. In this work, YBCO films were fabricated via a new diethanolamine-modified trifluoroacetic film solution deposition method. Modifying the copper chemistry of the YBCO precursor solution with diethanolamine enables a hundredfold decrease in the organic pyrolysis time required for MA/cm 2 current density (J c ) YBCO films, from multiple hours to ∼20 s in atmospheric pressure air. High quality, ∼0.2 μm thick YBCO films with J c (77 K) values ≥2 MA/cm 2 at 77 K are routinely crystallized from these rapidly pyrolyzed films deposited on LaAlO 3 . This process has also enabled J c (77 K)=1.1 MA/cm 2 YBCO films via 90 m/h dip-coating on Oak Ridge National Laboratory RABiTS textured metal tape substrates. This new YBCO solution deposition method suggests a route toward inexpensive and commercializable ∼$10/kA m solution deposited YBCO coated conductor wires

  2. Task Difficulty Differentially Affects Two Measures of Processing Load: The Pupil Response during Sentence Processing and Delayed Cued Recall of the Sentences

    Science.gov (United States)

    Zekveld, Adriana A.; Festen, Joost M.; Kramer, Kramera

    2013-01-01

    Purpose: In this study, the authors assessed the influence of masking level (29% or 71% sentence perception) and test modality on the processing load during language perception as reflected by the pupil response. In addition, the authors administered a delayed cued stimulus recall test to examine whether processing load affected the encoding of…

  3. Process of preparing superconductive oxide complexes containing L, Ba, Cu and O and method of using the same

    International Nuclear Information System (INIS)

    Salama, K.; Selvamanickam, V.

    1995-01-01

    A superconductor material having a current density, J, of from about 30,000 to about 85,000 amps/cm 2 at zero magnetic field and 77 K is disclosed. The 123 superconductor, of the formula L 1 Ba 2 Cu 3 O 6+δ wherein L is preferably yttrium, is capable of entrapping sufficiently high magnetic fields and exhibits a low microwave surface resistance. The process of preparing the superconductor comprises compacting the bulk product, L 1 Ba 2 Cu 3 O, and then sintering the reaction product at a temperature between about 40 C to about 90 C below its melting point, i.e., for Y 1 Ba 2 Cu 3 O 6+δ at a temperature of approximately 940 C. The composition is then heated in a preheated chamber maintained at approximately 1090 C to about 1,200 C (approximately 1,100 C for Y 1 Ba 2 Cu 3 O 6+δ ) until it has been decomposed, and is then rapidly cooled to a temperature between about 10 C to about 30 C above its melting point, i.e. for Y 1 Ba 2 Cu 3 O 6+δ a temperature of 1,030 C, and then is controlled cooled at a rate of 1 C/hr until it reaches a temperature of about 20 C to about 40 C below its melting point, i.e., for Y 1 Ba 2 Cu 3 O 6+δ a temperature of 980 C. The composition is steadily held at this temperature for at least eight hours, and then cooled to a temperature of approximately 400 C below its melting point (for Y 1 Ba 2 Cu 3 O 6+δ approximately a temperature of 600 C). The material is then slowly cooled by another 200 C and is then annealed in oxygen. 5 figs

  4. Stress-strain effects in alumina-Cu reinforced Nb3Sn wires fabricated by the tube process

    International Nuclear Information System (INIS)

    Murase, Satoru; Nakayama, Shigeo; Masegi, Tamaki; Koyanagi, Kei; Nomura, Shunji; Shiga, Noriyuki; Kobayashi, Norio; Watanabe, Kazuo.

    1997-01-01

    In order to fabricate a large-bore, high-field magnet which achieves a low coil weight and volume, a high strength compound superconducting wire is required. For those demands we have developed the reinforced Nb 3 Sn wire using alumina dispersion strengthened copper (alumina-Cu) as a reinforcement material and the tube process of the Nb 3 Sn wire fabrication. The ductility study of the composites which consisted of the reinforcement, Nb tube, Cu, and Cu clad Sn brought a 1 km long alumina-Cu reinforced Nb 3 Sn wire successfully. Using fabricated wires measurements and evaluations of critical current density as parameters of magnetic field, tensile stress, tensile strain, and transverse compressive stress, and those of stress-strain curves at 4.2 K were performed. They showed superior performance such as high 0.3% proof stress (240 MPa at 0.3% strain) and high maximum tolerance stress (320 MPa) which were two times as large as those of conventional Cu matrix Nb 3 Sn wire. The strain sensitivity parameters were obtained for the reinforced Nb 3 Sn wire and the Cu matrix one using the scaling law. Residual stress of the component materials caused by cooling down to 4.2 K from heat-treatment temperature was calculated using equivalent Young's modulus, equivalent yield strength, thermal expansion coefficient and other mechanical parameters. Calculated stress-strain curves at 4.2 K for the reinforced Nb 3 Sn wire and the Cu matrix one based on calculation of residual stress, had good agreement with the experimental values. (author)

  5. Fabrication of Copper-Rich Cu-Al Alloy Using the Wire-Arc Additive Manufacturing Process

    Science.gov (United States)

    Dong, Bosheng; Pan, Zengxi; Shen, Chen; Ma, Yan; Li, Huijun

    2017-12-01

    An innovative wire-arc additive manufacturing (WAAM) process is used to fabricate Cu-9 at. pct Al on pure copper plates in situ, through separate feeding of pure Cu and Al wires into a molten pool, which is generated by the gas tungsten arc welding (GTAW) process. After overcoming several processing problems, such as opening the deposition molten pool on the extremely high-thermal conductive copper plate and conducting the Al wire into the molten pool with low feed speed, the copper-rich Cu-Al alloy was successfully produced with constant predesigned Al content above the dilution-affected area. Also, in order to homogenize the as-fabricated material and improve the mechanical properties, two further homogenization heat treatments at 1073 K (800 °C) and 1173 K (900 °C) were applied. The material and mechanical properties of as-fabricated and heat-treated samples were compared and analyzed in detail. With increased annealing temperatures, the content of precipitate phases decreased and the samples showed gradual improvements in both strength and ductility with little variation in microstructures. The present research opened a gate for in-situ fabrication of Cu-Al alloy with target chemical composition and full density using the additive manufacturing process.

  6. A low-cost batch process for high-performance melt-textured GdBaCuO pellets

    Czech Academy of Sciences Publication Activity Database

    Muralidhar, M.; Tomita, M.; Suzuki, K.; Jirsa, Miloš; Fukumoto, .Y.; Ishihara, A.

    2010-01-01

    Roč. 23, č. 4 (2010), 045033/1-045033/7 ISSN 0953-2048 Institutional research plan: CEZ:AV0Z10100520 Keywords : superconducting magnet * GdBaCuO * batch process * high-Tc bulk Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.402, year: 2010

  7. Effects of deep cryogenic treatment on the solid-state phase transformation of Cu-Al alloy in cooling process

    Science.gov (United States)

    Wang, Yuhui; Liao, Bo; Liu, Jianhua; Chen, Shuqing; Feng, Yu; Zhang, Yanyan; Zhang, Ruijun

    2012-07-01

    The solid-state phase transformation temperature and duration of deep cryogenic treated and untreated Cu-Al alloys in cooling process were measured by differential scanning calorimetry measurement. The solid-state phase transformation activation energy and Avrami exponent were calculated according to these measurements. The effects of deep cryogenic treatment on the solid-state phase transformation were investigated based on the measurement and calculation as well as the observation of alloy's microstructure. The results show that deep cryogenic treatment can increase the solid-phase transformation activation energy and shorten the phase transformation duration, which is helpful to the formation of fine grains in Cu-Al alloy.

  8. Effects of advanced process approaches on electromigration degradation of Cu on-chip interconnects

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, M.A.

    2007-07-12

    This thesis provides a methodology for the investigation of electromigration (EM) in Cu-based interconnects. An experimental framework based on in-situ scanning electron microscopy (SEM) investigations was developed for that purpose. It is capable to visualize the EM-induced void formation and evolution in multi-level test structures in real time. Different types of interconnects were investigated. Furthermore, stressed and unstressed samples were studied applying advanced physical analysis techniques in order to obtain additional information about the microstructure of the interconnects as well as interfaces and grain boundaries. These data were correlated to the observed degradation phenomena. Correlations of the experimental results to recently established theoretical models were highlighted. Three types of Cu-based interconnects were studied. Pure Cu interconnects were compared to Al-alloyed (CuAl) and CoWP-coated interconnects. The latter two represent potential approaches that address EM-related reliability concerns. It was found that in such interconnects the dominant diffusion path is no longer the Cu/capping layer interface for interconnects as in pure Cu interconnects. Instead, void nucleation occurs at the bottom Cu/barrier interface with significant effects from grain boundaries. Moreover, the in-situ investigations revealed that the initial void nucleation does not occur at the cathode end of the lines but several micrometers away from it. The mean times-to-failure of CuAl and CoWP-coated interconnects were increased by at least one order of magnitude compared to Cu interconnects. The improvements were attributed to the presence of foreign metal atoms at the Cu/capping layer interface. Post-mortem EBSD investigations were used to reveal the microstructure of the tested samples. The data were correlated to the in-situ observations. (orig.)

  9. Containerless processing of YBa2Cu3O7-δ superconductors

    International Nuclear Information System (INIS)

    Olive, J.R.; Hofmeister, W.H.; Bayuzick, R.J.; Carro, G.; McHugh, J.P.; Hopkins, R.H.; Vlasse, M.

    1993-01-01

    Containerless processing of YBa 2 Cu 3 O 7-δ was performed using drop tube and aero-acoustic levitation techniques. In drop tube experiments, two solidification microstructures developed which corresponded to the degree of melting. In aero-acoustic levitation experiments, three solidification microstructures developed. One microstructure was the result of incomplete homogenization of the melt. The second was due to slight undercooling into the Y 2 O 3 + liquid region of the phase diagram upon which primary Y 2 O 3 dendrites formed. The third was due to much deeper undercooling. In this case, the primary solidification structure consisted of dendrites of tetragonal 1:2:3 and some other interdendritic phase. Subsequent to solidification processing, these samples were annealed to single phase 1:2:3 with orthorhombic symmetry. SQUID magnetometer measurements indicated a sharp superconducting transition at approximately 85 K. Magnetic J c values, calculated using the Bean critical state model, indicated that the deeply undercooled and annealed samples had critical current densities on the order of 10 4 Acm -2

  10. Solution processing of YBa2Cu3O7-x thin films

    International Nuclear Information System (INIS)

    Singhal, A.; Paranthaman, M.; Specht, E.D.; Hunt, R.D.; Beach, D.B.; Martin, P.M.; Lee, D.F.

    1997-12-01

    The aim of this work was to develop a non-vacuum chemical deposition technique for YBa 2 Cu 3 O 7-x (YBCO) coated conductors on rolling-assisted biaxially textured substrates (RABiTS). The authors have chosen the metal-organic decomposition (MOD) and sol-gel precursor routes to grow textured YBCO films. In the MOD process, yttrium 2-ethylhexonate, barium neodecanoate, copper 2-ethylhexonate and toluene were used as the starting reagents. YBCO films processed by the MOD method on SrTiO 3 (100) single crystal substrates were consisted of c and a-axis oriented materials. These films also contained some amount of the random phase. The c and a-axis oriented materials were epitaxial on SrTiO 3 substrates. Films have a T c,onset of 89K and the best superconducting transition temperature of 63K. Films pyrolyzed at 525 C and subsequently annealed at 780 C in a p(O 2 ) of 3.5 x 10 -4 atm contained YBCO phase predominantly in a-axis orientation. In the sol-gel route, yttrium-isopropoxide, barium metal, copper methoxide and 2-methoxyethanol were used as the starting reagents. Sol-gel YBCO films on SrTiO 3 substrates were epitaxial and c-axis oriented

  11. The development of hydrazine-processed Cu(In,Ga)(Se,S){sub 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Bob, Brion; Lei, Bao; Chung, Choong-Heui; Yang, Wenbing; Hsu, Wan-Ching; Duan, Hsin-Sheng; Hou, William Wei-Jen; Li, Sheng-Han; Yang, Yang [Department of Materials Science and Engineering, University of California, Los Angeles, CA (United States)

    2012-05-15

    The hydrazine-based deposition of Cu(In,Ga)(S,Se){sub 2} (CIGS) thin films has attracted considerable attention in recent years due to its potential for the high-throughput production of photovoltaic devices based on this absorber material. This article provides an introduction as well as presenting a complete picture of the current status of hydrazine-based CIGS solar-cell fabrication, including the three major steps of this deposition process: dissolution of the precursor materials in hydrazine, deposition of a film from the resulting precursor solution, and the completion and characterization of a photovoltaic device following absorber deposition. Recent discoveries are then discussed, regarding the dissolution chemistry of the relevant precursor complexes in hydrazine, which together represent the true foundation of this processing method. Recent studies on CIGS film formation are then summarized, including the control and analysis of the crystalline phase, electronic bandgap, and film morphology. Finally, the latest progress in high-performance device fabrication is highlighted, with a focus on optoelectronic characterization including current-voltage, junction capacitance, and minority carrier lifetime measurements. Finally, a discussion and future outlook is provided. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Study on the process of sintering matrix metallic Fe-Cu-25%Nb and Fe-Cu-25%Co during hot pressing

    International Nuclear Information System (INIS)

    Batista, A.C.; Oliveira, H.C.P.; Souza, M.H.; Assis, P.S.

    2016-01-01

    The sintering process promotes densification and the evolution of the microstructure of the material, with consequent significant increase in hardness and mechanical strength. However, few studies show the influence of pressure and temperature during sintering by hot pressing. In this sense, this work aims to evaluate the microstructural changes and properties with the variation of pressure and temperature and the type suffered by sintering metal powders during sintering by hot pressing. For this, two samples were studied by changing the sintering parameters: 25% Fe-50% Cu-25% Nb and 25% Fe-50% Cu-25% Co. Samples were analyzed by SEM / EDS in order to check the morphology and the presence of pores, as well as the interaction between the metallic constituents of each sample by the EDS analysis in line. They also determined the relative density, porosity and Vickers hardness (HV5). At the end of the study it was concluded that niobium alloy composite element by sintering activated suffered together with the liquid phase sintering. For cobalt alloys were observed by liquid phase sintering. The increase in the severity of the sintering conditions (temperature and pressure) led to an improvement in physical and mechanical properties of the alloys, which indicates that these parameters are directly related to the mechanisms of diffusion in the sintering process, improving the properties and diffusivity between elements. (author)

  13. The effect of the sulfur concentration on the phase transformation from the mixed CuO-Bi{sub 2}O{sub 3} system to Cu{sub 3}BiS{sub 3} during the sulfurization process

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lijian; Jin, Xin; Yuan, Chenchen; Jiang, Guoshun; Liu, Weifeng, E-mail: liuwf@ustc.edu.cn; Zhu, Changfei, E-mail: cfzhu@ustc.edu.cn

    2016-12-15

    Highlights: • Cu{sub 3}BiS{sub 3} thin films were creatively fabricated by sulfurizing metal oxide precursor. • The phase transformation mechanism during the sulfurization process was studied. • The reason why the excess S restrained the formation of Cu{sub 3}BiS{sub 3} was discussed. • The effect of temperature on film morphology and bandgap was studied. - Abstract: The ternary semiconductor Cu{sub 3}BiS{sub 3}, as a promising light-absorber material for thin film solar cells, was creatively synthesized by sulfurizing the mixed metal oxides precursor film deposited by spin-coating chemical solution method. Two kinds of sulfurization techniques were introduced to study the effect of the sulfur concentration on the phase formation for the pure Cu{sub 3}BiS{sub 3}. It was found that Cu-poor S-rich phases such as Cu{sub 3}Bi{sub 3}S{sub 7} and Cu{sub 4}Bi{sub 4}S{sub 9} were easily generated at high S concentration and then can transform to Cu{sub 3}BiS{sub 3} phase by a simple desulphurization process, which means the sulfur concentration had a significant influence on the formation of Cu{sub 3}BiS{sub 3} during the sulfurization process. The probable transformation mechanism from the mixed metal oxides to the pure Cu{sub 3}BiS{sub 3} phase during the sulfurization process was studied in detail through the XRD analysis and thermodynamic calculation. In addition, the electrical properties were characterized by Hall measurement and the effects of sulfurization temperature on the phase transformation, morphology and optical band gap of the absorber layer were also studied in detail.

  14. Consolidation processing parameters and alternative processing methods for powder metallurgy Al-Cu-Mg-X-X alloys

    Science.gov (United States)

    Sankaran, K. K.

    1987-01-01

    The effects of varying the vacuum degassing parameters on the microstructure and properties of Al-4Cu-1Mg-X-X (X-X = 1.5Li-0.2Zr or 1.5Fe-0.75Ce) alloys processed from either prealloyed (PA) or mechanically alloyed (M) powder, and consolidated by either using sealed aluminum containers or containerless vacuum hot pressing were studied. The consolidated billets were hot extruded to evaluate microstructure and properties. The MA Li-containing alloy did not include Zr, and the MA Fe- and Ce-containing alloy was made from both elemental and partially prealloyed powder. The alloys were vacuum degassed both above and below the solution heat treatment temperature. While vacuum degassing lowered the hydrogen content of these alloys, the range over which the vacuum degassing parameters were varied was not large enough to cause significant changes in degassing efficiency, and the observed variations in the mechanical properties of the heat treated alloys were attributed to varying contributions to strengthening by the sub-structure and the dispersoids. Mechanical alloying increased the strength over that of alloys of similar composition made from PA powder. The inferior properties in the transverse orientation, especially in the Li-containing alloys, suggested deficiencies in degassing. Among all of the alloys processed for this study, the Fe- and Ce-containing alloys made from MA powder possessed better combinations of strength and toughness.

  15. Air plasma spray processing and electrochemical characterization of Cu-SDC coatings for use in solid oxide fuel cell anodes

    Energy Technology Data Exchange (ETDEWEB)

    Benoved, Nir [Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Sciences Lane, Vancouver, British Columbia (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, Ontario (Canada)

    2009-09-05

    Air plasma spraying has been used to produce porous composite anodes based on Ce{sub 0.8}Sm{sub 0.2}O{sub 1.9} (SDC) and Cu for use in solid oxide fuel cells (SOFCs). Preliminarily, a range of plasma conditions has been examined for the production of composite coatings from pre-mixed SDC and CuO powders. Plasma gas compositions were varied to obtain a range of plasma temperatures. After reduction in H{sub 2}, coatings were characterized for composition and microstructure using EDX and SEM. As a result of these tests, symmetrical sintered electrolyte-supported anode-anode cells were fabricated by air plasma spraying of the anodes, followed by in situ reduction of the CuO to Cu. Full cells deposited on SS430 porous substrates were then produced in one integrated process. Fine CuO and SDC powders have been used to produce homogeneously mixed anode coatings with higher surface area microstructures, resulting in area-specific polarization resistances of 4.8 {omega} cm{sup 2} in impedance tests in hydrogen at 712 C. (author)

  16. Air plasma spray processing and electrochemical characterization of Cu-SDC coatings for use in solid oxide fuel cell anodes

    Science.gov (United States)

    Benoved, Nir; Kesler, O.

    Air plasma spraying has been used to produce porous composite anodes based on Ce 0.8Sm 0.2O 1.9 (SDC) and Cu for use in solid oxide fuel cells (SOFCs). Preliminarily, a range of plasma conditions has been examined for the production of composite coatings from pre-mixed SDC and CuO powders. Plasma gas compositions were varied to obtain a range of plasma temperatures. After reduction in H 2, coatings were characterized for composition and microstructure using EDX and SEM. As a result of these tests, symmetrical sintered electrolyte-supported anode-anode cells were fabricated by air plasma spraying of the anodes, followed by in situ reduction of the CuO to Cu. Full cells deposited on SS430 porous substrates were then produced in one integrated process. Fine CuO and SDC powders have been used to produce homogeneously mixed anode coatings with higher surface area microstructures, resulting in area-specific polarization resistances of 4.8 Ω cm 2 in impedance tests in hydrogen at 712 °C.

  17. Effect of processing variables on microstructure and properties of two Al-Li-Cu-Mg-Zr alloys

    International Nuclear Information System (INIS)

    Palmer, I.G.; Lewis, R.E.; Crooks, D.D.

    1984-01-01

    Two Al-Li-Cu-Mg-Zr alloys have been prepared in the form of both powder metallurgy (PM) and ingot metallurgy (IM) alloys. The compositions were selected to meet certain program goals based on the results of an alloy development phase, the details of which have been previously published. The target compositions were Al-3Li-1.5Cu-1Mg-0.2Zr and Al-3Cu-2Li-1Mg-0.2Zr. The PM alloys were prepared from chill cast remelt stock by centrifugal atomization in helium, followed by screening, degassing, and extrusion. The IM alloys were prepared by direct chill (DC) casting, homogenization and extrusion. Full details of the production of the alloys are given. The effects of various processing conditions on microstructure and properties were evaluated, including different heat treatments and stretching conditions. These effects are described in detail with particular emphasis on a comparison of the PM and IM alloys. 10 references

  18. P-type Cu2O/SnO bilayer thin film transistors processed at low temperatures

    KAUST Repository

    Al-Jawhari, Hala A.

    2013-10-09

    P-type Cu2O/SnO bilayer thin film transistors (TFTs) with tunable performance were fabricated using room temperature sputtered copper and tin oxides. Using Cu2O film as capping layer on top of a SnO film to control its stoichiometry, we have optimized the performance of the resulting bilayer transistor. A transistor with 10 nm/15 nm Cu2O to SnO thickness ratio (25 nm total thickness) showed the best performance using a maximum process temperature of 170 C. The bilayer transistor exhibited p-type behavior with field-effect mobility, on-to-off current ratio, and threshold voltage of 0.66 cm2 V-1 s-1, 1.5×10 2, and -5.2 V, respectively. The advantages of the bilayer structure relative to single layer transistor are discussed. © 2013 American Chemical Society.

  19. High-coercivity ultrafine-grained anisotropic Nd–Fe–B magnets processed by hot deformation and the Nd–Cu grain boundary diffusion process

    International Nuclear Information System (INIS)

    Sepehri-Amin, H.; Ohkubo, T.; Nagashima, S.; Yano, M.; Shoji, T.; Kato, A.; Schrefl, T.; Hono, K.

    2013-01-01

    The grain boundary diffusion process using an Nd 70 Cu 30 eutectic alloy has been applied to hot-deformed anisotropic Nd–Fe–B magnets, resulting in a substantial enhancement of coercivity, from 1.5 T to 2.3 T, at the expense of remanence. Scanning electron microscopy showed that the areal fraction of an Nd-rich intergranular phase increased from 10% to 37%. The intergranular phase of the hot-deformed magnet initially contained ∼55 at.% ferromagnetic element, while it diminished to an undetectable level after the process. Microscale eutectic solidification of Nd/NdCu as well as a fine lamellae structure of Nd 70 (Co,Cu) 30 /Nd were observed in the intergranular phase. Micromagnetic simulations indicated that the reduction of the magnetization in the intergranular phases leads to the enhancement of coercivity in agreement with the experimental observation

  20. Development of brazing process for W-EUROFER joints using Cu-based fillers

    Science.gov (United States)

    de Prado, J.; Sánchez, M.; Ureña, A.

    2016-02-01

    A successful joint between W and EUROFER using high temperature brazing technique has been achieved for structural application in future fusion power plants. Cu-based powder alloy mixed with a polymeric binder has been used as filler. Microstructural analysis of the joints revealed that the joint consisted mainly of primary phases and acicular structures in a Cu matrix. Interaction between EUROFER and filler took place at the interface giving rise to several Cu-Ti-Fe rich layers. A loss of hardness at the EUROFER substrate close to the joint due to a diffusion phenomenon during brazing cycle was measured; however, the joints had an adequate shear strength value.

  1. High-density Bi-Pb-Sr-Ca-Cu-O superconductor prepared by rapid thermal melt processing

    Science.gov (United States)

    Moon, B. M.; Lalevic, B.; Kear, B. H.; McCandlish, L. E.; Safari, A.; Meskoob, M.

    1989-10-01

    A high quality, dense Bi-Pb-Sr-Ca-Cu-O superconductor has been successfully synthesized by rapid thermal melt processing. Conventionally sintered pellets were melted at 1200 °C, cooled rapidly, and then annealed. As-melted samples exhibited semiconductor behavior, which upon annealing became superconducting at 115 K [Tc(zero)=105 K]. A detailed study of various processing techniques has been carried out.

  2. Solution processed Cu2SnS3 thin films for visible and infrared photodetector applications

    Directory of Open Access Journals (Sweden)

    Sandra Dias

    2016-02-01

    Full Text Available The Cu2SnS3 thin films were deposited using an economic, solution processible, spin coating technique. The films were found to possess a tetragonal crystal structure using X-ray diffraction. The film morphology and the particle size were determined using scanning electron microscopy. The various planes in the crystal were observed using transmission electron microscopy. The optimum band gap of 1.23 eV and a high absorption coefficient of 104 cm−1 corroborate its application as a photoactive material. The visible and infrared (IR photo response was studied for various illumination intensities. The current increased by one order from a dark current of 0.31 μA to a current of 1.78 μA at 1.05 suns and 8.7 μA under 477.7 mW/cm2 IR illumination intensity, at 3 V applied bias. The responsivity, sensitivity, external quantum efficiency and specific detectivity were found to be 10.93 mA/W, 5.74, 2.47% and 3.47 × 1010 Jones respectively at 1.05 suns and 16.32 mA/W, 27.16, 2.53% and 5.10 × 1010 Jones respectively at 477.7 mW/cm2 IR illumination. The transient photoresponse was measured both for visible and IR illuminations.

  3. Fabrication and heat treatment of high strength Al-Cu-Mg alloy processed using selective laser melting

    Science.gov (United States)

    Zhang, Hu; Zhu, Haihong; Nie, Xiaojia; Qi, Ting; Hu, Zhiheng; Zeng, Xiaoyan

    2016-04-01

    The proposed paper illustrates the fabrication and heat treatment of high strength Al-Cu-Mg alloy produced by selective laser melting (SLM) process. Al-Cu-Mg alloy is one of the heat treatable aluminum alloys regarded as difficult to fusion weld. SLM is an additive manufacturing technique through which components are built by selectively melting powder layers with a focused laser beam. The process is characterized by short laser-powder interaction times and localized high heat input, which leads to steep thermal gradients, rapid solidification and fast cooling. In this research, 3D Al-Cu-Mg parts with relative high density of 99.8% are produced by SLM from gas atomized powders. Room temperature tensile tests reveal a remarkable mechanical behavior: the samples show yield and tensile strengths of about 276 MPa and 402 MPa, respectively, along with fracture strain of 6%. The effect of solution treatment on microstructure and related tensile properties is examined and the results demonstrate that the mechanical behavior of the SLMed Al-Cu-Mg samples can be greatly enhanced through proper heat treatment. After T4 solution treatment at 540°C, under the effect of precipitation strengthening, the tensile strength and the yield strength increase to 532 MPa and 338 MPa, respectively, and the elongation increases to 13%.

  4. Effect of gate dielectrics on the performance of p-type Cu2O TFTs processed at room temperature

    KAUST Repository

    Al-Jawhari, Hala A.

    2013-12-01

    Single-phase Cu2O films with p-type semiconducting properties were successfully deposited by reactive DC magnetron sputtering at room temperature followed by post annealing process at 200°C. Subsequently, such films were used to fabricate bottom gate p-channel Cu2O thin film transistors (TFTs). The effect of using high-κ SrTiO3 (STO) as a gate dielectric on the Cu2O TFT performance was investigated. The results were then compared to our baseline process which uses a 220 nm aluminum titanium oxide (ATO) dielectric deposited on a glass substrate coated with a 200 nm indium tin oxide (ITO) gate electrode. We found that with a 150 nm thick STO, the Cu2O TFTs exhibited a p-type behavior with a field-effect mobility of 0.54 cm2.V-1.s-1, an on/off ratio of around 44, threshold voltage equaling -0.62 V and a sub threshold swing of 1.64 V/dec. These values were obtained at a low operating voltage of -2V. The advantages of using STO as a gate dielectric relative to ATO are discussed. © (2014) Trans Tech Publications, Switzerland.

  5. Practical UXO Classification: Enhanced Data Processing Strategies for Technology Transition - Fort Ord: Dynamic and Cued Metalmapper Processing and Classification

    Science.gov (United States)

    2017-06-06

    information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this...ms. 4 2.2 CLASSIFICATION Target classification is usually carried out using cued interrogation data acquired over anomalies initially...identified in the detection data. These cued interrogations eliminate relative positional errors by acquiring data with a stationary sensor. The multi-static

  6. CuGaS2 and CuGaS2–ZnS Porous Layers from Solution-Processed Nanocrystals

    Science.gov (United States)

    Guardia, Pablo; Estradé, Sònia; Peiró, Francesca; Cabot, Andreu

    2018-01-01

    The manufacturing of semiconducting films using solution-based approaches is considered a low cost alternative to vacuum-based thin film deposition strategies. An additional advantage of solution processing methods is the possibility to control the layer nano/microstructure. Here, we detail the production of mesoporous CuGaS2 (CGS) and ZnS layers from spin-coating and subsequent cross-linking through chalcogen-chalcogen bonds of properly functionalized nanocrystals (NCs). We further produce NC-based porous CGS/ZnS bilayers and NC-based CGS–ZnS composite layers using the same strategy. Photoelectrochemical measurements are used to demonstrate the efficacy of porous layers, and particularly the CGS/ZnS bilayers, for improved current densities and photoresponses relative to denser films deposited from as-produced NCs. PMID:29621198

  7. CuGaS2 and CuGaS2–ZnS Porous Layers from Solution-Processed Nanocrystals

    Directory of Open Access Journals (Sweden)

    Taisiia Berestok

    2018-04-01

    Full Text Available The manufacturing of semiconducting films using solution-based approaches is considered a low cost alternative to vacuum-based thin film deposition strategies. An additional advantage of solution processing methods is the possibility to control the layer nano/microstructure. Here, we detail the production of mesoporous CuGaS2 (CGS and ZnS layers from spin-coating and subsequent cross-linking through chalcogen-chalcogen bonds of properly functionalized nanocrystals (NCs. We further produce NC-based porous CGS/ZnS bilayers and NC-based CGS–ZnS composite layers using the same strategy. Photoelectrochemical measurements are used to demonstrate the efficacy of porous layers, and particularly the CGS/ZnS bilayers, for improved current densities and photoresponses relative to denser films deposited from as-produced NCs.

  8. Improvisation of mechanical and electrical properties of Cu by reinforcing MWCNT using modified electro-co-deposition process

    Science.gov (United States)

    Belgamwar, Sachin U.; Sharma, N. N.

    2018-04-01

    Multi-walled Carbon nanotubes–copper (MWCNT/Cu) composite powders with variable MWCNT content were synthesized by modified electro-co-deposition method. The electro-co-deposited MWCNT/Cu powders were consolidated by conventional compaction and sintering process. The consolidated products were then hot rolled and cold drawn to fine wires. The MWCNT/Cu composite wire samples were characterized for electrical and mechanical properties. We have been able to achieve an increase of around 8% in electrical conductivity of the form wires repeatedly. It has been observed that there was gradual improvement in the properties with reinforcement of MWCNT in the copper matrix. The betterment of electrical property has been achieved with simultaneous improvement in mechanical properties of the wire. The yield strength of MWCNT/Cu composite wire was found to be four times and the tensile strength two times greater than that of pure copper. The improved properties are attributed to the proper distribution of MWCNTs in the copper matrix and excellent interfacial bonding between MWCNT and composite copper fabricated by the modified method.

  9. Interactions between salt marsh plants and Cu nanoparticles - Effects on metal uptake and phytoremediation processes.

    Science.gov (United States)

    Andreotti, Federico; Mucha, Ana Paula; Caetano, Cátia; Rodrigues, Paula; Rocha Gomes, Carlos; Almeida, C Marisa R

    2015-10-01

    The increased use of metallic nanoparticles (NPs) raises the probability of finding NPs in the environment. A lot of information exists already regarding interactions between plants and metals, but information regarding interactions between metallic NPs and plants, including salt marsh plants, is still lacking. This work aimed to study interactions between CuO NPs and the salt marsh plants Halimione portulacoides and Phragmites australis. In addition, the potential of these plants for phytoremediation of Cu NPs was evaluated. Plants were exposed for 8 days to sediment elutriate solution doped either with CuO or with ionic Cu. Afterwards, total metal concentrations were determined in plant tissues. Both plants accumulated Cu in their roots, but this accumulation was 4 to 10 times lower when the metal was added in NP form. For P. australis, metal translocation occurred when the metal was added either in ionic or in NP form, but for H. portulacoides no metal translocation was observed when NPs were added to the medium. Therefore, interactions between plants and NPs differ with the plant species. These facts should be taken in consideration when applying these plants for phytoremediation of contaminated sediments in estuaries, as the environmental management of these very important ecological areas can be affected. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Low energy positron diffraction from Cu(111): Importance of surface loss processes at large angles of incidence

    International Nuclear Information System (INIS)

    Lessor, D.L.; Duke, C.B.; Lippel, P.H.; Brandes, G.R.; Canter, K.F.; Horsky, T.N.

    1990-10-01

    Intensities of positrons specularly diffracted from Cu(111) were measured at the Brandeis positron beam facility and analyzed in the energy range 8eV i = 4eV. At lower energies strong energy dependences occur associated both with multiple elastic scattering phenomena within atomic layers of Cu parallel to the surface and with the thresholds of inelastic channels (e.g., plasmon creation). Use of the free electron calculation of V i shows that energy dependence of inelastic processes is necessary to obtain a satisfactory description of the absolute magnitude of the diffracted intensities below E = 50eV. Detailed comparison of the calculated and observed diffraction intensities reveals the necessity of incorporating surface loss processes explicitly into the model in order to achieve a quantitative description of the measured intensities for E 40 degree. 30 refs., 5 figs., 1 tab

  11. Reduced thermal budget processing of Y-Ba-Cu-O films by rapid isothermal processing assisted metalorganic chemical vapor deposition

    International Nuclear Information System (INIS)

    Singh, R.; Sinha, S.; Hsu, N.J.; Ng, J.T.C.; Chou, P.; Thakur, R.P.S.; Narayan, J.

    1991-01-01

    Metalorganic chemical vapor deposition (MOCVD) has the potential of emerging as a viable technique to fabricate ribbons, tapes, coated wires, and the deposition of films of high-temperature superconductors, and related materials. As a reduced thermal budget processing technique, rapid isothermal processing (RIP) based on incoherent radiation as the source of energy can be usefully coupled to conventional MOCVD. In this paper we report on the deposition and characterization of high quality superconducting thin films of Y-Ba-Cu-O (YBCO) on yttrium stabilized zirconia substrates by RIP assisted MOCVD. Using O 2 gas as the source of oxygen, YBCO films deposited initially at 600 degree C for 1 min and at 745 degree C for 25 min followed by deposition at 780 degree C for 45 s are primarily c-axis oriented and zero resistance is observed at 89--90 K. The zero magnetic field current density at 53 and 77 K are 1.2x10 6 and 3x10 5 A/cm 2 , respectively. By using a mixture of N 2 O and O 2 as the oxygen source substrate temperature was further reduced in the deposition of YBCO films. The films deposited initially at 600 degree C for 1 min and than at 720 degree C for 30 min are c-axis oriented and with zero resistance being observed at 91 K. The zero magnetic field current densities at 53 and 77 K are 3.4x10 6 and 1.2x10 6 A/cm 2 , respectively. To the best of our knowledge this is the highest value of critical current density, J c for films deposited by MOCVD at a substrate temperature as low as 720 degree C. It is envisioned that high energy photons from the incoherent light source and the use of a mixture of N 2 O and O 2 as the oxygen source, assist chemical reactions and lower overall thermal budget for processing of these films

  12. Design and Synthesis of novel CuxGeOy/Cu/C nanowires by in situ chemical reduction process with highly reversible capacity for Lithium Batteries

    International Nuclear Information System (INIS)

    Wang, Linlin; Zhang, Xiaozhu; Peng, Xia; Tang, Kaibin

    2015-01-01

    The synthesis and use of ternary metal oxides/metal particles/carbon hybrids, especially 1D naowires composed of MGeO 3 /M/C hybrids for energy storage, remains very few reports. In this work, 1D Cu x GeO y /Cu/C NWs (x < 1, y < 3) were successfully prepared by a simple method involving chemical reduction process and simultaneous carbon coating. It was found that through the polydopamine(PDA)-assisted chemical reduction process performed on the CuGeO 3 NWs, the phase partially transformed to a mixture of crystalline Cu (∼70 nm) and amorphous Cu x GeO y NWs with carbon coating, but the nanowire-shaped morphology was maintained. Electrochemical measurements showed that the Cu x GeO y /Cu/C NWs exhibited a stable reversible capacity of ∼900 mA h g −1 after 100 cycles. Even at 800 mA g −1 , it also exhibited excellent high rate capacity of 350 mA h g −1 . The newly generated Cu x GeO y @Cu@CNWs exhibit enhanced cycle stability with high lithium-storage capability compared to that of the as-preparedCuGeO 3 NWs. (*) The in situ-synthesized Cu nanoparticles, amorphous state and carbon coating might play an important role in activating and enhancing the reversibility of the conversion reaction of Cu x GeO y . In addition, this effective synthetic method might provide the methodology for the development of other ternary metal oxides/metal particles/carbon hybrids materials for energy storage.

  13. Colloidal Precursors from 'Ball-Milling in Liquid Medium' Process for CuInSe{sub 2} Thin Film

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Jae Hoon; Kim, Seung Joo [Ajou University, Suwon (Korea, Republic of)

    2010-09-15

    CIS thin film can be fabricated by using the precursor obtained through ball-milling the elemental reagents in liquid media. The amorphous colloidal precursor with good dispersity was prepared in the medium that contains strong base and polar solvent (2 M ethylenediamine in DMF solution as used in this study). The 'ball-milling in liquid medium' method requires only elemental sources as starting materials and a proper solution so that it can be employed without additional processes for separation and purification. As a simple and less-toxic preparative route, this method would be practically available to prepare CIS-related solar cells. CuInSe{sub 2} (CIS) and related chalcopyrite compounds are very promising materials for thin film solar cells due to their favorable band gap, high optical absorption coefficient and long-term stability. CIS-based solar cells have shown the highest conversion efficiency reaching a value of 20%. However, the vacuum-based processes that are used to fabricate CIS thin-films have some drawbacks such as the complexity in process, high production cost and difficulty in scaling up. Recently, several research groups have proposed different non-vacuum deposition processes for CIS solar cell. For example, H. W. Hillhouse et al. prepared the CIS absorber layer by using 'nanocrystal ink method' in which a colloidal nanocrystal ink was obtained from reaction of CuCl, InCl{sub 3} and Se in oleylamine. D. B. Mitzi et al. used a solution-based precursor that was prepared by dissolution of Cu{sub 2}Se, In{sub 2}Se{sub 3}, Ga{sub 2}Se{sub 3} and Se in hydrazine to fabricate the Ga-containing absorber layer, Cu(In,Ga)Se{sub 2}.

  14. Solid state reactions and diffusion processes during rapid thermal processing of Cu-In-S based semiconductors

    International Nuclear Information System (INIS)

    Enzenhofer, T.

    2007-01-01

    In this thesis thin layers of the system Cu-In-S were studied for the photovoltaic application by means of structural and electro-optical procedures. The effect of small quantities of group II elements on the absorber and component properties could be explained by a widely appointed study. The motivation to insert extraneous elements into CuInS 2 absorber layers results from the too low zero-current voltage of CuInS 2 based solar cells. It could be shown that by addition of small quantities of Zn and/or Mg ( 2 solar cells aimed efficiencies, which were also determined for the reference system. As limiting factor in the doped system the zero-current has been proved. The intensive analysis of the absorber properties showed the the extraneous atoms effect in the bulk and on the surface different modifications

  15. Effects of process variables on the properties of YBa2Cu3O(7-x) ceramics formed by investment casting

    Science.gov (United States)

    Hooker, M. W.; Taylor, T. D.; Leigh, H. D.; Wise, S. A.; Buckley, J. D.; Vasquez, P.; Buck, G. M.; Hicks, L. P.

    1993-01-01

    An investment casting process has been developed to produce net-shape, superconducting ceramics. In this work, a factorial experiment was performed to determine the critical process parameters for producing cast YBa2Cu3O7 ceramics with optimum properties. An analysis of variance procedure indicated that the key variables in casting superconductive ceramics are the particle size distribution and sintering temperature. Additionally, the interactions between the sintering temperature and the other process parameters (e.g., particle size distribution and the use of silver dopants) were also found to influence the density, porosity, and critical current density of the fired ceramics.

  16. Counter-current acid leaching process for the removal of Cu, Pb, Sb and Zn from shooting range soil.

    Science.gov (United States)

    Lafond, Stéphanie; Blais, Jean-François; Mercier, Guy; Martel, Richard

    2013-01-01

    This research explores the performance of a counter-current leaching process (CCLP) for Cu, Pb, Sb and Zn extraction in a polluted shooting range soil. The initial metal concentrations in the soil were 1790 mg Cu/kg, 48,300 mg Pb/kg, 840 mg Sb/kg and 368 mg Zn/kg. The leaching process consisted of five one-hour acid leaching steps, which used 1 M H2SO4 + 4 M NaCl (20 degrees C, soil suspension = 100 g/L) followed by two water rinsing steps. Ten counter-current remediation cycles were completed and the average metal removal yields were 98.3 +/- 0.3% of Cu, 99.5 +/- 0.1% of Pb, 75.5 +/- 5.1% of Sb and 29.1 +/- 27.2% of Zn. The quality of metal leaching did not deteriorate throughout the 10 remediation cycles completed for this study. The CCLP reduced acid and salt use by approximately 68% and reduced water consumption by approximately 60%, exceeding reductions achieved by a standard acid leaching process.

  17. Radiation enhanced copper clustering processes in Fe-Cu alloys during electron and ion irradiations as measured by electrical resistivity

    International Nuclear Information System (INIS)

    Ishino, S.; Chimi, Y.; Bagiyono; Tobita, T.; Ishikawa, N.; Suzuki, M.; Iwase, A.

    2003-01-01

    To study the mechanism of radiation-enhanced clustering of copper atoms in Fe-Cu alloys, in situ electrical resistivity measurements are performed during irradiation with 100 MeV carbon ions and with 2 MeV electrons at 300 K. Two kinds of highly pure Fe-Cu alloys with Cu content of 0.02 and 0.6 wt% are used. The results are summarized as follows: - Although there is a steep initial resistivity increase below about 10 μdpa, the resistivity steadily decreases after this initial transient in Fe-0.6wt%Cu alloy, while in Fe-0.02wt%Cu alloy, the resistivity either decreases slowly or stays almost constant. The rate of change in resistivity depends on copper concentration. - The rate of change in resistivity per dpa is larger for electron irradiation than for ion irradiation. - Change in dose rate from 10 -8 to 10 -9 dpa/s slightly enhances the rate of resistivity change per dpa. The decrease in resistivity with dose is considered to be due to clustering or precipitation of copper atoms. The initial abrupt increase in resistivity is too large to be accounted for by initial introduction of point defects before copper clustering. Tentatively the phenomenon is explained as due to the formation of embryos of copper precipitates with a large strain field around them. Quantitative evaluation of the results using resistivity contribution of a unit concentration of Frenkel pairs and that of copper atoms gives an important conclusion that more than one copper atom are removed from solid solution by one Frenkel pair. The clustering efficiency is surprisingly high in the present case compared with the ordinary radiation-induced or radiation-enhanced precipitation processes

  18. Simultaneous decomplexation in blended Cu(II)/Ni(II)-EDTA systems by electro-Fenton process using iron sacrificing electrodes.

    Science.gov (United States)

    Zhao, Zilong; Dong, Wenyi; Wang, Hongjie; Chen, Guanhan; Tang, Junyi; Wu, Yang

    2018-05-15

    This research explored the application of electro-Fenton (E-Fenton) technique for the simultaneous decomplexation in blended Cu(II)/Ni(II)-EDTA systems by using iron sacrificing electrodes. Standard discharge (0.3 mg L -1 for Cu and 0.1 mg L -1 for Ni in China) could be achieved after 30 min reaction under the optimum conditions (i.e. initial solution pH of 2.0, H 2 O 2 dosage of 6 mL L -1  h -1 , current density of 20 mA/cm 2 , inter-electrode distance of 2 cm, and sulfate electrolyte concentration of 2000 mg L -1 ). The distinct differences in apparent kinetic rate constants (k app ) and intermediate removal efficiencies corresponding to mere and blended systems indicated the mutual promotion effect toward the decomplexation between Cu(II) and Ni(II). Massive accumulation of Fe(Ⅲ) favored the further removal of Cu(II) and Ni(II) by metal ion substitution. Species distribution results demonstrated that the decomplexation of metal-EDTA in E-Fenton process was mainly contributed to the combination of various reactions, including Fenton reaction together with the anodic oxidation, electro-coagulation (E-coagulation) and electrodeposition. Unlike hypophosphite and citrate, the presence of chlorine ion displayed favorable effects on the removal efficiencies of Cu(II) and Ni(II) at low dosage, but facilitated the ammonia nitrogen (NH 4 + -N) removal only at high dosage. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Functional Roles of Neural Preparatory Processes in a Cued Stroop Task Revealed by Linking Electrophysiology with Behavioral Performance.

    Science.gov (United States)

    Wang, Chao; Ding, Mingzhou; Kluger, Benzi M

    2015-01-01

    It is well established that cuing facilitates behavioral performance and that different aspects of instructional cues evoke specific neural preparatory processes in cued task-switching paradigms. To deduce the functional role of these neural preparatory processes the majority of studies vary aspects of the experimental paradigm and describe how these variations alter markers of neural preparatory processes. Although these studies provide important insights, they also have notable limitations, particularly in terms of understanding the causal or functional relationship of neural markers to cognitive and behavioral processes. In this study, we sought to address these limitations and uncover the functional roles of neural processes by examining how variability in the amplitude of neural preparatory processes predicts behavioral performance to subsequent stimuli. To achieve this objective 16 young adults were recruited to perform a cued Stroop task while their brain activity was measured using high-density electroencephalography. Four temporally overlapping but functionally and topographically distinct cue-triggered event related potentials (ERPs) were identified: 1) A left-frontotemporal negativity (250-700 ms) that was positively associated with word-reading performance; 2) a midline-frontal negativity (450-800 ms) that was positively associated with color-naming and incongruent performance; 3) a left-frontal negativity (450-800 ms) that was positively associated with switch trial performance; and 4) a centroparietal positivity (450-800 ms) that was positively associated with performance for almost all trial types. These results suggest that at least four dissociable cognitive processes are evoked by instructional cues in the present task, including: 1) domain-specific task facilitation; 2) switch-specific task-set reconfiguration; 3) preparation for response conflict; and 4) proactive attentional control. Examining the relationship between ERPs and behavioral

  20. Functional Roles of Neural Preparatory Processes in a Cued Stroop Task Revealed by Linking Electrophysiology with Behavioral Performance.

    Directory of Open Access Journals (Sweden)

    Chao Wang

    Full Text Available It is well established that cuing facilitates behavioral performance and that different aspects of instructional cues evoke specific neural preparatory processes in cued task-switching paradigms. To deduce the functional role of these neural preparatory processes the majority of studies vary aspects of the experimental paradigm and describe how these variations alter markers of neural preparatory processes. Although these studies provide important insights, they also have notable limitations, particularly in terms of understanding the causal or functional relationship of neural markers to cognitive and behavioral processes. In this study, we sought to address these limitations and uncover the functional roles of neural processes by examining how variability in the amplitude of neural preparatory processes predicts behavioral performance to subsequent stimuli. To achieve this objective 16 young adults were recruited to perform a cued Stroop task while their brain activity was measured using high-density electroencephalography. Four temporally overlapping but functionally and topographically distinct cue-triggered event related potentials (ERPs were identified: 1 A left-frontotemporal negativity (250-700 ms that was positively associated with word-reading performance; 2 a midline-frontal negativity (450-800 ms that was positively associated with color-naming and incongruent performance; 3 a left-frontal negativity (450-800 ms that was positively associated with switch trial performance; and 4 a centroparietal positivity (450-800 ms that was positively associated with performance for almost all trial types. These results suggest that at least four dissociable cognitive processes are evoked by instructional cues in the present task, including: 1 domain-specific task facilitation; 2 switch-specific task-set reconfiguration; 3 preparation for response conflict; and 4 proactive attentional control. Examining the relationship between ERPs and behavioral

  1. A buffer bridge process for growing multiple YBa2Cu3O7-y grains from one top seed

    International Nuclear Information System (INIS)

    Lee, J-H; Park, S-D; Jun, B-H; Lee, J S; Kim, C-J; Han, S C; Han, Y H

    2011-01-01

    This study presents a buffer bridge process that allows growing multiple YBa 2 Cu 3 O 7-y (Y123) grains from one top seed. This process uses a buffer bridge pellet (Y 2 BaCuO 5 or Y123) to deliver the Y123 growth from one seed to several Y123 compacts. The top seeded melt growth (TSMG) process combined with the buffer bridge process facilitated the fabrication of several single-grained Y123 superconductors using one seed. In addition to achieving the growth of multiple Y123 grains, this process ensured a uniform distribution of superconducting properties of the top surface because the seed/compact interface area (the number of seeds), which is the route for the impurities from the seeds, was minimized. Additionally, the impurity contamination from a seed was considerably suppressed using a buffer pellet. One (110) diagonal facet line, as a result of the corner-to-corner growth, developed on the top surfaces of the prepared Y123 compacts, which is comparable to the x-like facet line of the conventional TSMG processed samples. The trapped magnetic field (H) profiles at 77 K of the prepared Y123 compacts, which were estimated using an Nd-B-Fe permanent magnet, showed the H contour map of a single-grain mode. The force-distance curves for the field cooled and zero-field cooled Y123 compacts at 77 K showed high and reliable levitation forces with a small deviation among compacts. The buffer bridge process can be applied to a batch process for the mass production of single-grain REBa 2 Cu 3 O 7-y (RE: rare-earth elements) superconductors with uniform top surface properties.

  2. Mineralogy and skarnification processes at the Avan Cu-Fe Skarn, northeast of Kharvana, NW Iran

    Directory of Open Access Journals (Sweden)

    Mir Ali Asghar Mokhtari

    2017-02-01

    Full Text Available Introduction The Avan Cu-Fe skarn is located at the southern margin of Qaradagh batholith, about 60 km north of Tabriz. The Skarn-type metasomatic alteration is the result of Qaradagh batholith intrusion into the Upper Cretaceous impure carbonates. The studied area belongs to the Central Iranian structural zone. In regional scale, the studied area is a part of the Zangezour mineralization zone in the Lesser Caucasus. Several studies (Karimzadeh Somarin and Moayed, 2002; Calagari and Hosseinzadeh, 2005; Mokhtari, 2008; Baghban Asgharinezhad, 2012; Mokhtari, 2012 including master’s theses and research programs have been done on some skarns in the Azarbaijan area considering their petrologic and mineralization aspects. However, before this study, the Avan skarn aureole has not been studied in detail. In this paper, various geological aspects of the Avan skarn including mineralogy, bi-metasomatic alteration, metasomatism and mineralization during the progressive and retrograde stages of the skarnification processes have been studied in detail. Research Method This research consists of field and laboratory studies. Field studies include preparation of the geological map, identifying the relationship between the intrusion and the skarn aureole, identifying the relationship between different parts of the skarn zone and also collecting samples for laboratory studies. Laboratory studies include petrography, mineralography and microprobe studies. Cameca SX100 Microprobe belonging to Geological Survey of the Czech Republic was used in order to determine the chemical composition of the calc-silicate minerals such as pyroxene and garnet in garnet skarn and pyroxene- garnet skarn sub-zones. Discussion and conclusion Qaradagh batholith is composed of discrete acid to mafic phases including gabbro, diorite, quartz diorite, quartz monzonite, quartz monzodiorite, tonalite, granodiorite, monzogranite and granite porphyry which is dominated by granodiorite

  3. Thermal storage/discharge performances of Cu-Si alloy for solar thermochemical process

    Science.gov (United States)

    Gokon, Nobuyuki; Yamaguchi, Tomoya; Cho, Hyun-seok; Bellan, Selvan; Hatamachi, Tsuyoshi; Kodama, Tatsuya

    2017-06-01

    The present authors (Niigata University, Japan) have developed a tubular reactor system using novel "double-walled" reactor/receiver tubes with carbonate molten-salt thermal storage as a phase change material (PCM) for solar reforming of natural gas and with Al-Si alloy thermal storage as a PCM for solar air receiver to produce high-temperature air. For both of the cases, the high heat capacity and large latent heat (heat of solidification) of the PCM phase circumvents the rapid temperature change of the reactor/receiver tubes at high temperatures under variable and uncontinuous characteristics of solar radiation. In this study, we examined cyclic properties of thermal storage/discharge for Cu-Si alloy in air stream in order to evaluate a potentiality of Cu-Si alloy as a PCM thermal storage material. Temperature-increasing performances of Cu-Si alloy are measured during thermal storage (or heat-charge) mode and during cooling (or heat-discharge) mode. A oxidation state of the Cu-Si alloy after the cyclic reaction was evaluated by using electron probe micro analyzer (EPMA).

  4. Processing and properties of Cu based micro- and nano-composites

    Indian Academy of Sciences (India)

    The decrease in structural weight, increase in creep strength, high fatigue strength, high .... cate Al2O3 particles while the white portion corresponds to Cu matrix ..... preceding the frac- ture and rapid crack growth accompanied by loud noise ...

  5. Antibacterial studies of novel Cu2WS4 ternary chalcogenide synthesized by hydrothermal process

    Science.gov (United States)

    Kannan, Selvaraj; Vinitha, Perumal; Mohanraj, Kannusamy; Sivakumar, Ganesan

    2018-02-01

    This is the first report for the synthesis of L-cysteine mediated Cu2WS4 nanoparticles for different temperatures by an inexpensive and less pollutive hydrothermal method. The as-synthesized particles were characterized by XRD, FTIR, FESEM, UV-vis diffuse reflectance and PL spectra technique respectively. The phase purity and structural confirmation were studied by X-ray powder diffraction technique. It is observed that the synthesis temperature affecting the crystalline size. The optical analysis of the Cu2WS4 nanoparticles showed direct band gap in the range of 2.1-2.3 eV. The intensity of the PL emission spectra decreases with increase of reaction temperature. The antibacterial performance of Cu2WS4 nanoparticles were investigated by agar well diffusion method and the results confirm that the antibacterial activity of Cu2WS4 against Gram-positive (B. subtilis, M. luteus) and Gram-negative (E. coli, P. aeruginosa and K. pneumoniae) bacteria.

  6. Episodic feeling-of-knowing accuracy and cued recall in the elderly: evidence for double dissociation involving executive functioning and processing speed.

    Science.gov (United States)

    Perrotin, Audrey; Isingrini, Michel; Souchay, Céline; Clarys, David; Taconnat, Laurence

    2006-05-01

    This research investigated adult age differences in a metamemory monitoring task-episodic feeling-of-knowing (FOK) and in an episodic memory task-cued recall. Executive functioning and processing speed were examined as mediators of these age differences. Young and elderly adults were administered an episodic FOK task, a cued recall task, executive tests and speed tests. Age-related decline was observed on all the measures. Correlation analyses revealed a pattern of double dissociation which indicates a specific relationship between executive score and FOK accuracy, and between speed score and cued recall. When executive functioning and processing speed were evaluated concurrently on FOK and cued recall variables, hierarchical regression analyses showed that executive score was a better mediator of age-related variance in FOK, and that speed score was the better mediator of age-related variance in cued recall.

  7. Effect of processing of mechanical alloying and powder metallurgy on microstructure and properties of Cu-Al-Ni-Mn alloy

    International Nuclear Information System (INIS)

    Xiao Zhu; Li Zhou; Fang Mei; Xiong Shiyun; Sheng Xiaofei; Zhou Mengqi

    2008-01-01

    The fabrication conditions of Cu-Al-Ni-Mn alloy powder by mechanical alloying and powder metallurgy have been systematically studied. The mechanically alloyed powder (MAed powder) was fabricated at a speed between 100 rpm and 300 rpm for various milling times with and without process control agent (PCA). With an increasing of milling time, the size of crystallite grain decreases. Only the Cu diffraction pattern appear as the rotation speed is up to 300 rpm for 25 h. The elemental powders with PCA agglomerate slightly, but the degree of alloying is lower than that without PCA. The shape memory recovery of the quenched sample hot-extruded at extrusion rate of 50:1 is measured to be 100% recovered in 250 deg. C oil bath for 40 s after deformed to 4.0%. After aging at 120 deg. C for 10 days, the shape memory recovery of the alloy remains 98%

  8. Development of a hybrid sputtering/evaporation process for Cu(In,Ga)Se{sub 2} thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Acciarri, M.; Binetti, S.; Le Donne, A.; Lorenzi, B.; Caccamo, L.; Miglio, L. [Dipartimento di Scienza dei Materiali e Solar Energy Research Center MIB-SOLAR, Universita di Milano Bicocca, Milan (Italy); Moneta, R.; Marchionna, S.; Meschia, M. [Voltasolar s.r.l, Turate (Italy)

    2011-08-15

    In this paper we report a new method for Cu(In,Ga)Se{sub 2} deposition for solar cell application. Differently from the common co-evaporation process, an alterative approach for thin film Cu(In,Ga)Se{sub 2} has been tested: the sputtering deposition of metal elements combined with the selenium evaporation. We have studied the relationships between the growth parameters of our hybrid sputtering/evaporation method and the chemical-physical properties of the CIGS films. The cells are completed with a CdS buffer layer deposited by chemical bath deposition and ZnO + ITO deposited by RF sputtering. Test solar cells of 0.5 cm{sup 2} have shown an efficiency of 10% and 2.5% on glass and stainless steel substrate respectively. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Melt-processed Gd-Ba-Cu-O superconductor with trapped field of 3 T at 77 K

    International Nuclear Information System (INIS)

    Nariki, S; Sakai, N; Murakami, M

    2005-01-01

    We fabricated a single-domain Gd-Ba-Cu-O bulk superconductor 65 mm in diameter and studied the microstructure, superconducting and field-trapping properties. Melt-processing was performed under a controlled oxygen partial pressure of 1.0% using a precursor containing Gd123 and Gd211 powders in a molar ratio of 2:1, with 0.5 wt% of Pt and 20 wt% of Ag 2 O added. The distribution of Ag and Gd211 particles was almost homogeneous. The addition of Ag was very effective in reducing the amount of cracking in the sample. The maximum trapped magnetic field recorded was 3.05 T at 77 K. We also measured the trapped field between two Gd-Ba-Cu-O bulk samples in order to minimize the demagnetizing effect and found that the trapped field reached 4.3 T at 77 K

  10. Photoluminescence of Cu(In,Ga)Se2 in the solar cell preparation process

    International Nuclear Information System (INIS)

    Sho, Shirakata; Shinji, Yudate; Jyunji, Honda; Naoki, Iwado

    2010-01-01

    Full text : Sequential step by step photoluminescence (PL) measurements have been carried out on Cu(In,Ga)Se 2 (CIGS) films just after each thin-film processes for the fabrication of the CIGS solar cell. These include, (i) the CIGS film deposition on the Mo-coated soda-lime glass substrate by three-stage method (CIGS/Mo/SLG), (ii) the chemical-bath deposition (CBD) of CdS buffer layer, (iii) deposition of undoped ZnO window layer by RF sputtering, (iv) deposition of Al doped ZnO high-conductive window layer by RF sputtering, (v) Al grid electrode deposition for the CIGS solar cell, and (vi) the mechanical scribing for the electrical isolation of small test cells. Roomtemperature PL measurements have been done with the excitation of a He-Ne laser (632.8 nm, 1 mW) focused on the sample surface to 0.2 mm diameter. PL was dispersed by a polycromator (Horiba: MicroHR) and detected by a cooled InGaAs multichannel detector (1024 pixels). In order to study the uniformity of PL within CIGS films, the two dimensional PL spectrum mapping measurement has been done (0.4-0.6 mm step) using an x-y stage operating in the raster scanning mode. Acquisition time of one PL spectrum was 1 s. Once the fresh CIGS film is exposed to the air, intensity of the near-band-edge PL decreases slowly with time. After few days, PL intensity was one order of magnitude weaker than its initial value. Thus, PL measurement was performed just after the deposition. It was shown that PL spectra of CIGS films taken for each process in the CIGS solar cell preparation. PL of the CIGS film exhibited nearband-edge peak at 1.18 eV. The slight increase of PL intensity was observed after depositions of CdS and ZnO films. After the high conductive ZnO:Al deposition, PL intensity decreases to one third of the initial PL intensity of the fresh CIGS film. No change has been observed with respect to the line shape of PL peaks during the process. In the CIGS solar cell (open circuit condition), PL intensity recovers

  11. Friction-stir processing of a high-damping Mn-Cu alloy used for marine propellers

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, S.P.; Edwards, D.P.; Majumdar, A. [Defence Science and Technology Organisation, Melbourne (Australia); Moutsos, S. [Centre for Advanced Materials Technology, Monash Univ. (Australia); Mahoney, M.W. [Rockwell Scientific, Thousand Oaks (United States)

    2003-07-01

    Mn-Cu alloys are used for specialised applications, such as marine propellers, where high noise-damping characteristics are required. These alloys tend to have more severe shrinkage porosity than conventional propeller alloys, and the corrosion resistance (including stress-corrosion and corrosion-fatigue resistance) of the alloys is not as high as desirable. Friction-stir processing (FSP) trials on one such alloy (tradename Sonoston) have shown that near-surface porosity can be eliminated and that the coarse, as-cast microstructure can be significantly refined. The corrosion resistance of processed material is substantially improved provided a heat treatment to relieve residual stress is carried out after FSP. (orig.)

  12. Use of Hopcalite derived Cu-Mn mixed oxide as Oxygen Carrier for Chemical Looping with Oxygen Uncoupling Process

    OpenAIRE

    Adánez-Rubio, Iñaki; Abad Secades, Alberto; Gayán Sanz, Pilar; Adánez-Rubio, Imanol; Diego Poza, Luis F. de; Garcia-Labiano, Francisco; Adánez Elorza, Juan

    2016-01-01

    Chemical-Looping with Oxygen Uncoupling (CLOU) is an alternative Chemical Looping process for the combustion of solid fuels with inherent CO2 capture. The CLOU process needs a material as oxygen carrier with the ability to give gaseous O2 at suitable temperatures for solid fuel combustion, e.g. copper oxide and manganese oxide. In this work, treated commercial Carulite 300® was evaluated as oxygen carrier for CLOU. Carulite 300® is a hopcalite material composed of 29.2 wt.% CuO and 67.4 wt.% ...

  13. Optical properties of La2CuO4 and La2−xCaxCuO4 crystallites in UV–vis–NIR region synthesized by sol–gel process

    International Nuclear Information System (INIS)

    Li Yifeng; Huang Jianfeng; Cao Liyun; Wu Jianpeng; Fei Jie

    2012-01-01

    La 2 CuO 4 and La 2−x Ca x CuO 4 crystallites were prepared via a simple sol–gel process. The as-prepared La 2 CuO 4 and La 2 −x Ca x CuO 4 crystallites were characterized by X-ray diffraction, transmission electron microscope and UV–vis–NIR spectra. Results show that the grain size of La 2 CuO 4 crystallites increases with the increase of heat treatment temperature from 600 °C to 800 °C. Optical properties show that La 2 CuO 4 crystallites have broad absorption both in the UV–vis region and in the NIR region. The band gap of the as-prepared crystallites decreases from 1.367 eV to 1.284 eV with the increase of calcination temperature from 600 °C to 800 °C. In the series of La 2−x Ca x CuO 4 compounds (x = 0.05, 0.08, 0.10, 0.12, 0.15 and 0.20), all of the samples exhibit an orthogonal crystal structure and the solubility limit of Ca 2+ in La 2 CuO 4 is within the range of x = 0.12–0.15. In the whole UV–vis–NIR region, La 2−x Ca x CuO 4 crystallites exhibit a broad absorption and the corresponding band gap first increases and then decreases with increasing of Ca 2+ content. - Highlights: ► The optical band gap can be tuned by adjusting the grain size and Ca 2+ content. ► La 2 CuO 4 crystallites exhibit a broad absorption band both in the UV–vis region and in the NIR region. ► The band gap increases from 1.284 eV to 1.319 eV with the decrease of heat treatment temperature. ► In the whole UV–vis–NIR region, the La 2−x Ca x CuO 4 crystallites displayed a broad absorption. ► The band gap of La 2−x Ca x CuO 4 increases linearly with doping level when 0 ≤ x ≤ 0.12.

  14. Solution-processed inorganic copper(I) thiocyanate (CuSCN) hole transporting layers for efficient p–i–n perovskite solar cells

    KAUST Repository

    Zhao, Kui; Munir, Rahim; Yan, Buyi; Yang, Yang; Kim, Taesoo; Amassian, Aram

    2015-01-01

    CuSCN is a highly transparent, highly stable, low cost and easy to solution process HTL that is proposed as a low cost replacement to existing organic and inorganic metal oxide hole transporting materials. Here, we demonstrate hybrid organic

  15. Structure and Mechanical Properties of AlSiCuMg Alloy after Thermo Processing

    Directory of Open Access Journals (Sweden)

    Piątkowski J.

    2015-03-01

    Full Text Available In the dissertation it has been shown, that so called „time-thermal treatment” (TTT of the alloy in liquid state, as overheating the metal with around 250°C above the Tliq. and detaining it in this temperature for around 30 minutes, improves the mechanical properties (HB, Rm, R0,2. It was ascertained, that overheating the AlSi17Cu5Mg alloy aids the modification, resulting with microcrystalline structure. Uniform arrangement of the Si primeval crystals in the warp, and α(Al solution type, supersaturated with alloying elements present in the base content (Cu, Mg assures not only increased durability in the ambient temperature, but also at elevated temperature (250°C, what is an advantage, especially due to the use in car industry.

  16. Study of the precipitation hardening process in recycled Al-Si-Cu cast alloys

    Directory of Open Access Journals (Sweden)

    Kuchariková L.

    2017-03-01

    Full Text Available The formation of extremely small uniformly dispersed particles of a second phase within the original phase matrix during heat treatment changed material properties. Therefore the characterization of precipitation had been investigated using high resolution transmission electron microscopy (TEM and electron diffraction of thin foils for an AlSi9Cu3 cast alloy. For investigation the hardening effect onto mechanical properties of aluminium cast was used heat treatment, which consisted from solution treatment at 515°C / 4 hours (h, followed by quenching into water with temperature 50°C and artificial aging using different temperatures 170°C and 190°C with different holding time 2, 4, 8, 16, and 32 hours. The observations of microstructure and substructure reveals that precipitation hardening has caused great changes in size, morphology and distributions of structural components, the formation of precipitates of Cu phases, and the change of mechanical properties as well.

  17. A novel process for textured thick film YBa2Cu3Oy coated conductors based on a constitutional gradients principle

    International Nuclear Information System (INIS)

    Reddy, E Sudhakar; Tarka, M; Noudem, J G; Goodilin, E A; Schmitz, G J

    2005-01-01

    A new method for the processing of textured YBa 2 Cu 3 O y (Y 123) thick film stripes on metallic tapes is discussed. The process involves the texturing of Y123 grains by a localized directional solidification method by creating constitutional gradients along the width of the precursor Y 2 BaCuO 5 (Y 211) stripe during an infiltration and growth process. The differences in the solidification temperatures of different rare earth 123 compounds were utilized to generate the constitutional gradients. The sample configuration involves printed lines of light (Nd) and heavy (Yb) rare earth compounds on either side of an airbrushed Y211 stripe underneath a liquid phase (barium cuprates) layer. The higher peritectic temperature (T p ) Nd regions serve as nucleating sites for Y123 grains nucleated in the adjacent Y211 stripes and the constitutional gradients produced due to the diffusion of respective rare earth ions between the Nd and Yb regions, typically of 200 K cm -1 in the region, induce a driving force for the directional growth of the nucleated grains. The solidification is analogous to that in a typical Bridgman furnace in applied high temperature gradients. The process, being independent of growth rate parameter and texture of the underlying substrate, is suitable for the fabrication of long length thick film conductors by a wind and react process in simple box type furnaces

  18. Microstructures and mechanical properties evolution of an Al–Fe–Cu alloy processed by repetitive continuous extrusion forming

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Xiangxin [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Zhang, Hui, E-mail: zhanghui63hunu@163.com [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Hunan Province Key Laboratory for Spray Deposition Technology and Application, Hunan University, Changsha 410082 (China); Ji, Xiankun [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)

    2014-08-26

    Repetitive continuous extrusion forming process (R-Conform process), as a continuous severe plastic deformation method, was performed on a horizontal continuous casting Al–0.74Fe–0.23Cu alloy. The microstructural evolution and mechanical properties were studied by optical microscope, X-ray diffraction, scanning electron microscope, transmission electron microscope, and tensile testing. The results show that tensile ductility of the Al–0.74Fe–0.23Cu alloy is greatly improved but tensile strength is gradually decreased after repetitive Conform processing. The necking is more intense and the size of dimples becomes bigger with increasing Conform passes. The first pass Conform process induces obviously grains refining, dissolution of AlFe, AlFeSi and AlSi primary phases, strain-induced precipitation and transformation of crystal orientation distributions, but further Conform deformation only changes the redistribution of precipitates. The changes of mechanical properties may be attributed to a complex progress of recovery, recrystallization and redistribution of precipitates during repetitive Conform process.

  19. Electric field-induced hole transport in copper(i) thiocyanate (CuSCN) thin-films processed from solution at room temperature

    KAUST Repository

    Pattanasattayavong, Pichaya; Ndjawa, Guy Olivier Ngongang; Zhao, Kui; Chou, Kang Wei; Yaacobi-Gross, Nir; O'Regan, Brian C.; Amassian, Aram; Anthopoulos, Thomas D.

    2013-01-01

    The optical, structural and charge transport properties of solution-processed films of copper(i) thiocyanate (CuSCN) are investigated in this work. As-processed CuSCN films of ∼20 nm in thickness are found to be nano-crystalline, highly transparent and exhibit intrinsic hole transporting characteristics with a maximum field-effect mobility in the range of 0.01-0.1 cm2 V-1 s-1. © 2013 The Royal Society of Chemistry.

  20. Effect of Process Parameters on Fatigue and Fracture Behavior of Al-Cu-Mg Alloy after Creep Aging

    Directory of Open Access Journals (Sweden)

    Lihua Zhan

    2018-04-01

    Full Text Available A set of creep aging tests at different aging temperatures and stress levels were carried out for Al-Cu-Mg alloy, and the effects of creep aging on strength and fatigue fracture behavior were studied through tensile tests and fatigue crack propagation tests. The microstructures were further analyzed by using scanning electron microscopy (SEM and transmission electron microscopy (TEM. The results show that temperature and stress can obviously affect the creep behavior, mechanical properties, and fatigue life of Al-Cu-Mg alloy. As the aging temperature increases, the fatigue life of alloy first increases, and then decreases. The microstructure also displays a transition from the Guinier-Preston-Bagaryatsky (GPB zones to the precipitation of S phase in the grain interior. However, the precipitation phases grow up and become coarse at excessive temperatures. Increasing stress can narrow the precipitation-free zone (PFZ at the grain boundary and improve the fatigue life, but overhigh stress can produce the opposite result. In summary, the fatigue life of Al-Cu-Mg alloy can be improved by fine-dispersive precipitation phases and a narrow PFZ in a suitable creep aging process.

  1. Microstructure And Mechanical Properties Of An Al-Zn-Mg-Cu Alloy Produced By Gravity Casting Process

    Directory of Open Access Journals (Sweden)

    Saikawa S.

    2015-06-01

    Full Text Available High-strength aluminum alloy are widely used for structural components in aerospace, transportation and racing car applications. The objective of this study is to enhance the strength of the Al-Zn-Mg-Cu alloy used for gravity casting process. All alloys cast into stepped-form sand mold (Sand-mold Casting; SC and Y-block shaped metal mold(Permanent mold Casting; PC C and then two –step aged at 398-423 K after solution treated at 743 K for 36 ks. The tensile strength and total elongation of the two-step aged SC alloys were 353-387 MPa and about 0.4% respectively. This low tensile properties of the SC alloys might be caused by remaining of undissolved crystallized phase such as Al2CuM, MgZn2 and Al-Fe-Cu system compounds. However, good tensile properties were obtained from PC alloys, tensile strength and 0.2% proof stress and elongation were 503-537 MPa, 474-519 MPa and 1.3-3.3%.

  2. Fabrication of CuInS2-sensitized solar cells via an improved SILAR process and its interface electron recombination.

    Science.gov (United States)

    Xu, Xueqing; Wan, Qingcui; Luan, Chunyan; Mei, Fengjiao; Zhao, Qian; An, Ping; Liang, Zhurong; Xu, Gang; Zapien, Juan Antonio

    2013-11-13

    Tetragonal CuInS2 (CIS) has been successfully deposited onto mesoporous TiO2 films by in-sequence growth of InxS and CuyS via a successive ionic layer absorption and reaction (SILAR) process and postdeposition annealing in sulfur ambiance. X-ray diffraction and Raman measurements showed that the obtained tetragonal CIS consisted of a chalcopyrite phase and Cu-Au ordering, which related with the antisite defect states. For a fixed Cu-S deposition cycle, an interface layer of β-In2S3 formed at the TiO2/CIS interface with suitable excess deposition of In-S. In the meantime, the content of the Cu-Au ordering phase decreased to a reasonable level. These facts resulted in the retardance of electron recombination in the cells, which is proposed to be dominated by electron transfer from the conduction band of TiO2 to the unoccupied defect states in CIS via exponentially distributed surface states. As a result, a relatively high efficiency of ~0.92% (V(oc) = 0.35 V, J(sc) = 8.49 mA cm(-2), and FF = 0.31) has been obtained. Last, but not least, with an overloading of the sensitizers, a decrease in the interface area between the sensitized TiO2 and electrolytes resulted in deceleration of hole extraction from CIS to the electrolytes, leading to a decrease in the fill factor of the solar cells. It is indicated that the unoccupied states in CIS with energy levels below EF0 of the TiO2 films play an important role in the interface electron recombination at low potentials and has a great influence on the fill factor of the solar cells.

  3. Instantaneous preparation of CuInSe2 films from elemental In, Cu, Se particles precursor films in a non-vacuum process

    International Nuclear Information System (INIS)

    Kaigawa, R.; Uesugi, T.; Yoshida, T.; Merdes, S.; Klenk, R.

    2009-01-01

    CuInSe 2 (CIS) films are successfully prepared by means of non-vacuum, instantaneous, direct synthesis from elemental In, Cu, Se particles precursor films without prior synthesis of CIS nanoparticle precursors and without selenization with H 2 Se or Se vapor. Our precursor films were prepared on metal substrates by spraying the solvent with added elemental In, Cu, and Se particles. Precursor films were instantaneously sintered using a spot welding machine. When the electric power was fixed to 0.6 kVA, elemental In, Cu, or Se peaks were not observed and only peaks of CIS are observed by X-ray diffraction (XRD) on the film sintered for 7/8 s. We can observe XRD peaks indicative of the chalcopyrite-type structure, such as (101), (103) and (211) diffraction peaks. We conclude that the synthesized CIS crystals have chalcopyrite-type structure with high crystallinity

  4. Processing of W-Cu functionally graded materials (FGM) through the powder metallurgy route: application as plasma facing components for ITER-like thermonuclear fusion reactor

    International Nuclear Information System (INIS)

    Raharijaona, J.J.

    2009-11-01

    The aim of this study was to study and optimize the sintering of W-Cu graded composition materials, for first wall of ITER-like thermonuclear reactor application. The graded composition in the material generates graded functional properties (Functionally Graded Materials - FGM). Rough thermomechanical calculations have shown the interest of W-Cu FGM to improve the lifetime of Plasma Facing Components (PFC). To process W-Cu FGM, powder metallurgy route was analyzed and optimized from W-CuO powder mixtures. The influence of oxide reduction on the sintering of powder mixtures was highlighted. An optimal heating treatment under He/H 2 atmosphere was determined. The sintering mechanisms were deduced from the analysis of the effect of the Cu-content. Sintering of W-Cu materials with a graded composition and grain size has revealed two liquid migration steps: i) capillary migration, after the Cu-melting and, ii) expulsion of liquid, at the end of sintering, from the dense part to the porous part, due to the continuation of W-skeleton sintering. These two steps were confirmed by a model based on capillary pressure calculation. In addition, thermal conductivity measurements were conducted on sintered parts and showed values which gradually increase with the Cu-content. Hardness tests on a polished cross-section in the bulk are consistent with the composition profiles obtained and the differential grain size. (author)

  5. Synthesis of Ag-Cu and Ag-Cu{sub 2}O alloy nanoparticles using a seed-mediated polyol process, thermodynamic and kinetic aspects

    Energy Technology Data Exchange (ETDEWEB)

    Niknafs, Yasaman; Amirjani, Amirmostafa; Marashi, Pirooz, E-mail: pmarashi@aut.ac.ir; Fatmehsari, Davoud Haghshenas

    2017-03-01

    In this paper, Ag, Ag-Cu and Ag-Cu{sub 2}O nanoparticles were synthesized using a modified polyol method. Size, shape and composition of the obtained nanostructures were effectively controlled by adjusting the kinetic and thermodynamic conditions. Response surface methodology was employed to consider the interaction of parameters and to develop a polynomial equation for predicting the size of the silver nanoparticles. The precisely controlled silver nanoaprticles were used as the seeds for the formation of alloyed nanoparticles. By manipulating the involved parameters, both spherical and cubical Ag-Cu and Ag-Cu{sub 2}O nanostructures are obtainable in the size range of 90–100 nm. The morphological, optical and compositional characteristics of the obtained nanostructures were studied using SEM, FE-SEM, UV–Vis, EDS and XRD. - Highlights: • Synthesis of Ag, Ag-Cu and Ag-Cu{sub 2}O alloy nanostructures. • RSM was successfully employed for predicting the size of the AgNPs. • Size and composition tuning by adjusting the kinetic and thermodynamic conditions.

  6. Effect of selenization time on the structural and morphological properties of Cu(In,Ga)Se2 thin films absorber layers using two step growth process

    Science.gov (United States)

    Korir, Peter C.; Dejene, Francis B.

    2018-04-01

    In this work two step growth process was used to prepare Cu(In, Ga)Se2 thin film for solar cell applications. The first step involves deposition of Cu-In-Ga precursor films followed by the selenization process under vacuum using elemental selenium vapor to form Cu(In,Ga)Se2 film. The growth process was done at a fixed temperature of 515 °C for 45, 60 and 90 min to control film thickness and gallium incorporation into the absorber layer film. The X-ray diffraction (XRD) pattern confirms single-phase Cu(In,Ga)Se2 film for all the three samples and no secondary phases were observed. A shift in the diffraction peaks to higher 2θ (2 theta) values is observed for the thin films compared to that of pure CuInSe2. The surface morphology of the resulting film grown for 60 min was characterized by the presence of uniform large grain size particles, which are typical for device quality material. Photoluminescence spectra show the shifting of emission peaks to higher energies for longer duration of selenization attributed to the incorporation of more gallium into the CuInSe2 crystal structure. Electron probe microanalysis (EPMA) revealed a uniform distribution of the elements through the surface of the film. The elemental ratio of Cu/(In + Ga) and Se/Cu + In + Ga strongly depends on the selenization time. The Cu/In + Ga ratio for the 60 min film is 0.88 which is in the range of the values (0.75-0.98) for best solar cell device performances.

  7. Visible-light photocatalytic decolorization of reactive brilliant red X-3B on Cu{sub 2}O/crosslinked-chitosan nanocomposites prepared via one step process

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Chunhua [College of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, College of Chemical and Environmental Engineering, Jianghan University, Wuhan 430056 (China); Xiao, Ling, E-mail: xiaoling9119@yahoo.cn [College of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Liu, Li; Zhu, Huayue [College of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Chen, Chunhua; Gao, Lin [Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, College of Chemical and Environmental Engineering, Jianghan University, Wuhan 430056 (China)

    2013-04-15

    Cu{sub 2}O/crosslinked-chitosan nanocomposites (Cu{sub 2}O/CS NCs) were in situ prepared via a simple one-step liquid phase precipitation–reduction process and characterized by XRD, FT-IR, SEM, TEM, BET, XPS and UV–vis/DRS. The characterization results showed that Cu{sub 2}O/CS NCs were almost similar spherical or ellipsoidal and the surface was rough and porous because Cu{sub 2}O particle was wrapped in chitosan. The chitosan layer was especially favorable for improving the adsorption ability of dye and molecular oxygen and restraining the recombination of electrons–holes pair. The visible-light photocatalytic decolorization behavior on Cu{sub 2}O/CS NCs was evaluated using reactive brilliant red X-3B (X-3B) as a model pollutant. The influences of various experimental factors on X-3B decolorization were investigated. It was found that the photocatalytic decolorization process on Cu{sub 2}O/CS NCs followed apparent pseudo-first-order kinetics model. The dye X-3B could be decolorized more efficiently in acidic media than in alkaline media. Cu{sub 2}O/CS NCs exhibited enhanced visible-light photocatalytic activity compared with other photocatalysts reported before under similar experimental conditions.

  8. Hyper- and hypobaric processing of Tl-Ba-Ca-Cu-O superconductors

    Science.gov (United States)

    Goretta, K. C.; Routbort, J. L.; Shi, Donglu; Chen, J. G.; Hash, M. C.

    1989-11-01

    Tl-based superconductors of initial composition Tl:Ca:Ba:Cu equal to 2:2:2:3 and 1:3:1:3 were heated in oxygen at pressures of 10(sup 4) to 6 (times) 10(sup 5) Pa. The 2:2:2:3 composition formed primarily the 2-layer superconductor with zero resistance from 77 to 104 K. The 1:3:1:3 composition formed nearly phase pure 3-layer superconductor with a maximum zero resistance temperature of 120 K. Application of hyperbaric pressure influenced phase purities and transition temperatures slightly; phase purities decreased significantly with application of hypobaric pressures.

  9. Process design of a hydrogen production plant from natural gas with CO2 capture based on a novel Ca/Cu chemical loop

    International Nuclear Information System (INIS)

    Martínez, I.; Romano, M.C.; Fernández, J.R.; Chiesa, P.; Murillo, R.; Abanades, J.C.

    2014-01-01

    Highlights: • Process design of a H 2 production plant based on a novel Ca/Cu looping process is presented. • CuO reduction with syngas provides energy for CaCO 3 calcination. • The effect of operating conditions on plant performance indexes is analysed. • Carbon capture efficiencies of around 94% are obtained. • Around 6% points of equivalent H 2 efficiency improvement on conventional reforming. - Abstract: A detailed and comprehensive design of a H 2 production plant based on a novel Ca/Cu chemical looping process is presented in this work. This H 2 production process is based on the sorption-enhanced reforming concept using natural gas together with a CaO/CaCO 3 chemical loop. A second Cu/CuO loop is incorporated to supply energy for the calcination of the CaCO 3 via the reduction of CuO with a fuel gas. A comprehensive energy integration description of the different gas streams available in the plant is provided to allow a thermodynamic assessment of the process and to highlight its advantages and drawbacks. Hydrogen equivalent efficiencies of up to 77% are feasible with this novel Ca/Cu looping process, using an active reforming catalyst based on Pt, high oxidation temperatures and moderate gas velocities in the fixed bed system, which are around 6% points above the efficiency of a reference H 2 production plant based on conventional steam reforming including CO 2 capture with MDEA. Non-converted carbon compounds in the reforming stage are removed as CO 2 in the calcination stage of the Ca/Cu looping process, which will be compressed and sent for storage. Carbon capture efficiencies of around 94% can be obtained with this Ca/Cu looping process, which are significantly higher than those obtained in the reference plant that uses MDEA absorption (around 85%). Additional advantages, such as its compact design and the use of cheaper materials compared to other commercial processes for H 2 production with CO 2 capture, confirm the potential of the Ca/Cu

  10. Hole-transporting transistors and circuits based on the transparent inorganic semiconductor copper(I) thiocyanate (CuSCN) processed from solution at room temperature

    KAUST Repository

    Pattanasattayavong, Pichaya

    2012-12-27

    The wide bandgap and highly transparent inorganic compound copper(I) thiocyanate (CuSCN) is used for the first time to fabricate p-type thin-film transistors processed from solution at room temperature. By combining CuSCN with the high-k relaxor ferroelectric polymeric dielectric P(VDF-TrFE-CFE), we demonstrate low-voltage transistors with hole mobilities on the order of 0.1 cm2 V-1 s-1. By integrating two CuSCN transistors, unipolar logic NOT gates are also demonstrated. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Friction and wear characteristics of Al-Cu/C composites synthesized using partial liquid phase casting process

    International Nuclear Information System (INIS)

    Ng, W.B.; Gupta, M.; Lim, S.C.

    1997-01-01

    During the sliding of aluminium alloys dispersed with graphite particulates, a layer of graphite is usually present at the sliding interface. This tribo-layer significantly reduces the amount of direct metal-to-metal contact, giving rise to low friction and a low rate of wear, making these composites useful candidate materials for anti-friction applications. Such self-lubricating composites are commonly fabricated via the squeeze casting, slurry casting or powder metallurgy route. These processes are expensive while the less-expensive conventional casting route is limited by the agglomeration of graphite particles in the composites, giving rise to poor mechanical properties. In this work, graphite particulate-reinforced Al-4.5 wt.% Cu composites with two effective graphite contents (Al-4.5 Cu/4.2 wt.% C and Al-4.5 Cu/6.8 wt.% C) were synthesized through an innovative partial liquid phase casting (rheocasting) technique, which is a modification of the conventional casting process. Unlubricated (without the use of conventional liquid lubrication) friction and wear performance of these composites as well as the un-reinforced aluminium alloy was determined using a pin-on-disk tester. The results revealed that the graphite-reinforced composites have a higher wear rate than the un-reinforced matrix alloy while their frictional characteristics are very similar within the range of testing conditions. Combining these with the information gathered from worn-surface examinations and wear-debris analysis, it is suggested that there exists a certain threshold for the amount and size of graphite particulates in these composites to enable them to have improved tribological properties. (Copyright (c) 1997 Elsevier Science B.V., Amsterdam. All rights reserved.)

  12. 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.).

  13. Investigations into alterntive substrate, absorber, and buffer layer processing for Cu(In,Ga)Se{sub 2}-based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tuttle, J.R.; Berens, T.A.; Keane, J. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    High-performance Cu(In,Ga)Se{sub 2}(CIGS)-based solar cells are presently fabricated within a narrow range of processing options. In this contribution, alternative substrate, absorber, and buffer layer processing is considered. Cell performance varies considerably when alternative substrates are employed. These variations are narrowed with the addition of Na via a Na{sub 2}S compound. Sputtered and electrodeposited CIGS precursors and completed absorbers show promise as alternatives to evaporation. A recrystallization process is required to improve their quality. (In,Ga){sub y}Se buffer layers contribute to cell performance above 10. Further improvements in these alternatives will lead to combined cell performance greater than 10% in the near term.

  14. Materials process and applications of single grain (RE)-Ba-Cu-O bulk high-temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Li Beizhan; Zhou Difan; Xu Kun; Hara, Shogo; Tsuzuki, Keita; Miki, Motohiro; Felder, Brice; Deng Zigang [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology (TUMSAT), 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Izumi, Mitsuru, E-mail: izumi@kaiyodai.ac.jp [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology (TUMSAT), 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan)

    2012-11-20

    This paper reviews recent advances in the melt process of (RE)-Ba-Cu-O [(RE)BCO, where RE represents a rare earth element] single grain high-temperature superconductors (HTSs), bulks and its applications. The efforts on the improvement of the magnetic flux pinning with employing the top-seeded melt-growth process technique and using a seeded infiltration and growth process are discussed. Which including various chemical doping strategies and controlled pushing effect based on the peritectic reaction of (RE)BCO. The typical experiment results, such as the largest single domain bulk, the clear TEM observations and the significant critical current density, are summarized together with the magnetization techniques. Finally, we highlight the recent prominent progress of HTS bulk applications, including Maglev, flywheel, power device, magnetic drug delivery system and magnetic resonance devices.

  15. Microstructure and mechanical properties of Al-Mg-Si-Cu matrix composites reinforced with AINp. processed by extrusion of powders

    International Nuclear Information System (INIS)

    Ortiz, J. L.; Amigo, V.; Salvador, M. D.; Perz, C. R.

    2000-01-01

    This article presents an experimental investigation on the structure and mechanical properties of an Al-Mg-Si-Cu P/M alloy reinforced with 5%, 10% and 15% aluminum nitride, produced by extrusion of cold compacted powders mixtures. Mechanical properties in as extruded and T6 conditions are compared. Differential Scanning Calorimetry and Dilatometric analysis were conducted to gain further insight into the precipitation process of these materials. Low cost 6061 Al/AINp composites can be produced with rate and small porosity by extrusion of cold compacted shapes without canning. The mechanical properties of the MMCs obtained by this process have limitations for high particles fractions because of clustering effects. All materials are always harder than the matrix and shows a similar behavior during aging processes but kinetics is changed. Potential applications of dilatometric techniques in the aging investigations of aluminum alloys and aluminum matrix composites have been established. (Author) 23 refs

  16. Materials process and applications of single grain (RE)-Ba-Cu-O bulk high-temperature superconductors

    Science.gov (United States)

    Li, Beizhan; Zhou, Difan; Xu, Kun; Hara, Shogo; Tsuzuki, Keita; Miki, Motohiro; Felder, Brice; Deng, Zigang; Izumi, Mitsuru

    2012-11-01

    This paper reviews recent advances in the melt process of (RE)-Ba-Cu-O [(RE)BCO, where RE represents a rare earth element] single grain high-temperature superconductors (HTSs), bulks and its applications. The efforts on the improvement of the magnetic flux pinning with employing the top-seeded melt-growth process technique and using a seeded infiltration and growth process are discussed. Which including various chemical doping strategies and controlled pushing effect based on the peritectic reaction of (RE)BCO. The typical experiment results, such as the largest single domain bulk, the clear TEM observations and the significant critical current density, are summarized together with the magnetization techniques. Finally, we highlight the recent prominent progress of HTS bulk applications, including Maglev, flywheel, power device, magnetic drug delivery system and magnetic resonance devices.

  17. [Influence of Spectral Pre-Processing on PLS Quantitative Model of Detecting Cu in Navel Orange by LIBS].

    Science.gov (United States)

    Li, Wen-bing; Yao, Lin-tao; Liu, Mu-hua; Huang, Lin; Yao, Ming-yin; Chen, Tian-bing; He, Xiu-wen; Yang, Ping; Hu, Hui-qin; Nie, Jiang-hui

    2015-05-01

    Cu in navel orange was detected rapidly by laser-induced breakdown spectroscopy (LIBS) combined with partial least squares (PLS) for quantitative analysis, then the effect on the detection accuracy of the model with different spectral data ptetreatment methods was explored. Spectral data for the 52 Gannan navel orange samples were pretreated by different data smoothing, mean centralized and standard normal variable transform. Then 319~338 nm wavelength section containing characteristic spectral lines of Cu was selected to build PLS models, the main evaluation indexes of models such as regression coefficient (r), root mean square error of cross validation (RMSECV) and the root mean square error of prediction (RMSEP) were compared and analyzed. Three indicators of PLS model after 13 points smoothing and processing of the mean center were found reaching 0. 992 8, 3. 43 and 3. 4 respectively, the average relative error of prediction model is only 5. 55%, and in one word, the quality of calibration and prediction of this model are the best results. The results show that selecting the appropriate data pre-processing method, the prediction accuracy of PLS quantitative model of fruits and vegetables detected by LIBS can be improved effectively, providing a new method for fast and accurate detection of fruits and vegetables by LIBS.

  18. Microstructure and transport current characterization of YBa2Cu3O7-x thick films prepared by modified solid-liquid melt growth and powder melt process routes

    International Nuclear Information System (INIS)

    Langhorn, J.; McGinn, P.J.

    1999-01-01

    From the characterization of superconducting YBa 2 Cu 3 O 7-x (YBCO) thick films processed by melt texturing on yttria-stabilized zirconia substrates from YBCO precursors it is clear that the properties are highly dependent on the precursor powder. Increased YBCO grain sizes have been induced in thick films processed from by modified solid-liquid melt growth (SLMG) and powder melt (PMP) processes with respect to those processed from pre-reacted YBCO materials. The SLMG and PMP routes utilize precursors consisting of BaCuO 2 -CuO flux material mixed with Y 2 O 3 and Y 2 BaCuO 5 respectively. Cross-sectional analysis of films textured by these routes shows a decreased Y 2 BaCuO 5 size and an increased homogeneity within the matrix with respect to films processed from YBCO powder. Such microstructural improvements lead to an improvement of both the flux pinning and current-carrying characteristics of the processed YBCO films. (author)

  19. Preparation and properties of superconducting Bi-Sr-Ca-Cu-O materials by the alkoxide process

    International Nuclear Information System (INIS)

    Uchikawa, Fusaoki; Kobayashi, Toshio; Usami, Ryo; Yoshizaki, Kiyoshi

    1989-01-01

    Homogeneous starting solutions were synthesized using Bi, Sr, Ca and Cu alkoxides. Powders, thick films and gel fibers were prepared respectively by controlling hydrolysis using the same solutions. The synthesized powder had a homogeneous particle size. The fired powder showed a good crystallization property. The thick film coated on MgO substrate using the synthesized sol solution had a smooth surface and a uniformity of each metal elements. The film showed the c-axis orientation and was shown to have the zero resistance temperature of 90 K and the critical current density of 180 A/cm 2 at 77 K. The fiber drawn from the viscous gel solution showed a comparatively large shrinkage with hear treatment. The fired fiber was brittle and had a low strength. It was also found for the fired fiber that zero resistance temperature was 70 K and the critical current density was 90 A/cm 2 at 77 K

  20. Obtainment of the alloy Cu13Al4Ni using processed by powder metallurgy

    International Nuclear Information System (INIS)

    Grossi, L.J.; Damasceno, N.; Muterlle, P.V.

    2016-01-01

    The powder metallurgy is a technique environmentally advantageous that allows the production of many pieces, with a good superficial finishing and dimensional tolerance. For the production of pieces using technique, basics steps are carried out, as the characterization of powders, the mixing and homogenization, compacting and sintering. In this context, this work has as objective the obtainment of the Cu13Al4Ni alloy via powder metallurgy. For this, was made a high energy milling for 2, 4 and 8 hours. Then, the milled powder was compacted and posteriorly, sintered in an oven with controlled atmosphere. It was observed that the milling time affects directly in sintering of the pieces. The best results obtained were for the samples that were milled for 4 hours. This samples have showed 21, 52% of porosity and 6,382 g/cm³ of the density of sintered. (author)

  1. Anisotropic Responses of Mechanical and Thermal Processed Cast Al-Si-Mg-Cu Alloy

    Science.gov (United States)

    Adeosun, S. O.; Akpan, E. I.; Balogun, S. A.; Onoyemi, O. K.

    2015-05-01

    The effects of ambient directional rolling and heat treatments on ultimate tensile strength (UTS), hardness (HD), percent elongation (PE), and impact energy (IE) on Al-Si-Mg-Cu alloy casting with reference to inclination to rolling direction are discussed in this article. The results show that rolled and quenched (CQ) sample possess superior UTS and HD to as-cast and those of rolled and aged samples (CA). Improved IE resistance with ductility is shown by both CQ and CA samples. However, these mechanical properties are enhanced as changes in the test sample direction moved away from rolling direction for all heat-treated samples. The CQ samples displayed highest tensile strength (108 MPa) and PE (19.8%) in the 90° direction.

  2. Experimental studies of fundamental aspects of Auger emission process in Cu(100) and Ag(100)

    Science.gov (United States)

    Joglekar, Prasad Vivek

    Auger spectra at the low energies are accompanied by large contributions unrelated to the Auger transition. The Auger unrelated contributions can obscure the Auger peak and affect the quantitative analysis of the materials under investigation. In this dissertation we present a methodology to measure experimentally the Auger unrelated contributions and eliminate it from the Auger spectrum for obtaining an Auger spectrum inherent to the Auger transition. We used Auger Photoelectron Coincidence Spectroscopy (APECS) to obtain the Auger spectrum. APECS measures the Auger spectrum in coincidence with the core energy level and thus discriminating the contributions arising from secondary electrons and electrons arising from the non-Auger transition. Although APECS removes most of the Auger unrelated contributions, it cannot distinguish the contribution which is measured in coincidence with the inelastically scattered valence band electrons emitted at the core energy. To measure this inelastically scattered valence band contribution we did a series of measurements on Ag(100) to study NVV Auger spectrum in coincidence with 4p energy level and Cu(100) to study MVV Auger spectrum in coincidence with 3p energy level. The coincidence detection of the core and Auger-valence electrons was achieved by the two cylindrical mirror analyzers (CMAs). One CMA was fixed over a range of energies in between VB and core energy level while other CMA scanned corresponding low energy electrons from 0 to70eV. The spectrums measured were fit to a parameterized function which was extrapolated to get an estimate of inelastically scattered valence band electrons. The estimated contribution was subtracted for the Ag and Cu APECS spectrum to obtain a spectrum solely due to Auger transition with inelastically scattered Auger electron and multi Auger decay contributions associated with the transition. In the latter part of this dissertation, we propose a theoretical model based on the spectral intensity

  3. Mechanical and microstructural properties of Cu-Al-Ni-Mn-Zr shape memory alloy processed by spray forming

    Energy Technology Data Exchange (ETDEWEB)

    Cava, R.D.; Bolfarini, C.; Kiminami, C.S.; Mazzer, E.M.; Pedrosa, V.M.; Botta, W.J.; Gargarella, P. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2016-07-01

    Full text: Cu-based shape memory alloys (SMA) presents higher thermal and electrical conductivities, low material cost and combine good mechanical properties with a pronounced shape memory effect [1]. By using rapid solidification methods, their microstructure is refined and detrimental segregations can be avoided, which results in better mechanical properties. Additionally, the microalloying additions as Ti, B, Si and Zr can refine the grains and improve of mechanical and thermal properties of Cu-based SMA alloys [2-4]. In this investigation the Cu81.95Al11.35Ni3.2Mn3Zr0.5 (wt%) SMA alloy has been processed by spray forming in order to investigate the potential of achieving a deposit with adequate microstructure with goal to a SMA part production. The alloy was atomized with nitrogen gas at pressure of 0.5MPa. The microstructure of the deposit was characterized by optical and scanning electron microscopy and X-ray diffraction. The deposit presented homogeneous microstructure consisting of equiaxial grains with martensite microstructure and mean grain size of 30 ?m. The shape memory effect and the temperatures transformation have been evaluated by differential scanning calorimetric. The mechanical properties were evaluated by tensile and compression tests at room and at 220 deg C(T>Af) temperatures. [1] T. Waitz, et al., T, J. of the Mechanics and Physics of Solids, 55, 2007. [2] D. W. Roh, et al., Metall Trans. A, 21, 1990. [3] D. W. Roh, et al., Mat. Sci. and Eng. A136, 1991. (author)

  4. Density and superconducting properties of metal-sheathed YBa2Cu3Oy ceramic processed by hydrostatic extrusion

    International Nuclear Information System (INIS)

    Karpov, M.I.; Korzhov, V.P.; Artamoshin, A.V.; Prokopenko, V.M.

    1994-01-01

    Brittle materials can be deformed without cracking and rupturing using hydrostatic extrusion, which provides the greatest pore annihilation in powder-processed materials and allows large degrees of one-step deformation, which is favorable for texturing. Earlier, a casting slip prepared by mixing a starting powder of Y-based ceramic with an organic binder was conventionally extruded to produce a wire 150 μm in diameter. After special sintering, the critical-current density in the material attained a few hundred amperes per square centimeter at 77 K, and the wire could be rolled into a winding ≥0.3 m in diameter. Hydrostatic extrusion of an assembly composed of Y-based ceramic in a bimetallic Nb/Cu tube 30 mm in diameter was used to produce rods 6 mm in diameter; drawing of these rods yielded samples of wire 2 to 3 mm in diameter. It was shown that the extrusion pressure and strain substantially influence the yield of the rupture-free wire. No signs of rupturing, cracking, or necking were observed in wire extruded at pressures ≤700 MPa and degrees of deformation ≤50%. A pronounced instability of the hydrostatic extrusion, the appearance of defects, and even the rupture of the rods were caused by an increase in the pressure up to 2000 MPa and in the degree of one-step deformation up to 80%. In this work, the authors focus on the possibility of producing thin YBa 2 Cu 3 O y superconductors using only hydrostatic extrusion. They determined the parameters for the hydrostatic extrusion of the metal-sheathed YBa 2 Cu 3 O y ceramic to a diameter of 3 mm or to a rectangular cross section. Effects of the ceramic core, and of the reduction coefficient on superconducting-transition parameters and the critical-current density of the ceramic were examined

  5. Ex Situ and Operando Studies on the Role of Copper in Cu-Promoted SiO2-MgO Catalysts for the Lebedev Ethanol-to-Butadiene Process

    NARCIS (Netherlands)

    Angelici, Carlo|info:eu-repo/dai/nl/345731506; Meirer, Florian; van der Eerden, Ad M. J.|info:eu-repo/dai/nl/304840483; Schaink, Herrick L.; Goryachev, Andrey; Hofmann, Jan P.|info:eu-repo/dai/nl/355351110; Hensen, Emiel J. M.; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397; Bruijnincx, Pieter C. A.|info:eu-repo/dai/nl/33799529X

    2015-01-01

    Dehydrogenation promoters greatly enhance the performance of SiO2-MgO catalysts in the Lebedev process. Here, the effect of preparation method and order of addition of Cu on the structure and performance of Cu-promoted SiO2-MgO materials is detailed. Addition of Cu to MgO via incipient wetness

  6. Evaluating print performance of Sn-Ag-Cu lead-free solder pastes used in electronics assembly process

    Science.gov (United States)

    Mallik, S.; Bauer, R.; Hübner, F.; Ekere, N. N.

    2011-01-01

    Solder paste is the most widely used interconnection material in the electronic assembly process for attaching electronic components/devices directly onto the surface of printed circuit boards, using stencil printing process. This paper evaluates the performance of three different commercially available Sn-Ag-Cu solder pastes formulated with different particle size distributions (PSD), metal content and alloy composition. A series of stencil printing tests were carried out using a specially designed stencil of 75 μm thickness and apertures of 300×300 μm2 dimension and 500 μm pitch sizes. Solder paste printing behaviors were found related to attributes such as slumping and surface tension and printing performance was correlated with metal content and PSD. The results of the study should benefit paste manufacturers and SMT assemblers to improve their products and practices.

  7. Studies on Al-Cu-Li-Mg-Ag-Zr alloy processed through vacuum induction melting (VIM) technique

    International Nuclear Information System (INIS)

    Nayan, Niraj; Govind; Nair, K. Suseelan; Mittal, M.C.; Sudhakaran, K.N.

    2007-01-01

    A new technique of lithium addition has been adapted for the processing of Al-Cu-Li-Ag-Mg-Zr alloy, which gives more than 90% recovery of lithium throughout the billet. Processing studies on this alloy include casting, three step homogenization, to avoid incipient melting, and mechanical working particularly forging and rolling. The products in the form of sheets were subjected to various T6 (solution treatment + water quenching + aging) tempers. Mechanical properties were evaluated at room temperature and correlated with microstructure. Characterizations using optical microscope and post-fracture analysis have been carried out using Scanning electron microscope (SEM). Experimental investigation shows highest mechanical properties for the Al-1.3%Li alloy in T6 (500 deg. C/1 h + WQ + 190 deg. C/24 h) condition

  8. Process Parameters Optimization for Friction Stir Welding of Pure Aluminium to Brass (CuZn30 using Taguchi Technique

    Directory of Open Access Journals (Sweden)

    Elfar O. M. R.

    2016-01-01

    Full Text Available In this research, the friction stir welding of dissimilar commercial pure aluminium and brass (CuZn30 plates was investigated and the process parameters were optimized using Taguchi L9 orthogonal array. The considered process parameters were the rotational speed, traverse speed and pin offset. The optimum setting was determined with reference to ultimate tensile strength of the joint. The predicted optimum value of ultimate tensile strength was confirmed by experimental run using optimum parameters. Analysis of variance revealed that traverse speed is the most significant factor in controlling the joint tensile strength and pin offset also plays a significant role. In this investigation, the optimum tensile strength is 50% of aluminium base metal. Metallographic examination revealed that intermetallic compounds were formed in the interface of the optimum joint where the tensile failure was observed to take place.

  9. Characterization of process-induced damage in Cu/low-k interconnect structure by microscopic infrared spectroscopy with polarized infrared light

    Energy Technology Data Exchange (ETDEWEB)

    Seki, Hirofumi, E-mail: Hirofumi-Seki@trc.toray.co.jp; Hashimoto, Hideki [Toray Research Center, Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567 (Japan); Ozaki, Yukihiro [Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1, Gakuen, Sanda, Hyogo 669-1337 (Japan)

    2016-09-07

    Microscopic Fourier-transform infrared (FT-IR) spectra are measured for a Cu/low-k interconnect structure using polarized IR light for different widths of low-k spaces and Cu lines, and for different heights of Cu lines, on Si substrates. Although the widths of the Cu line and the low-k space are 70 nm each, considerably smaller than the wavelength of the IR light, the FT-IR spectra of the low-k film were obtained for the Cu/low-k interconnect structure. A suitable method was established for measuring the process-induced damage in a low-k film that was not detected by the TEM-EELS (Transmission Electron Microscope-Electron Energy-Loss Spectroscopy) using microscopic IR polarized light. Based on the IR results, it was presumed that the FT-IR spectra mainly reflect the structural changes in the sidewalls of the low-k films for Cu/low-k interconnect structures, and the mechanism of generating process-induced damage involves the generation of Si-OH groups in the low-k film when the Si-CH{sub 3} bonds break during the fabrication processes. The Si-OH groups attract moisture and the OH peak intensity increases. It was concluded that the increase in the OH groups in the low-k film is a sensitive indicator of low-k damage. We achieved the characterization of the process-induced damage that was not detected by the TEM-EELS and speculated that the proposed method is applicable to interconnects with line and space widths of 70 nm/70 nm and on shorter scales of leading edge devices. The location of process-induced damage and its mechanism for the Cu/low-k interconnect structure were revealed via the measurement method.

  10. The influence of post-processing on creep and microstructure of rolled Cu-8Cr-4Nb

    Energy Technology Data Exchange (ETDEWEB)

    Walley, J.L.; Heelan, J.L.; Vettraino, L.G.; Groza, J.R. [Department of Chemical Engineering and Materials Science, University of California, One Shields Ave., Davis, CA 95616 (United States); Gibeling, J.C., E-mail: jcgibeling@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, One Shields Ave., Davis, CA 95616 (United States)

    2010-10-15

    Research highlights: {yields} A simulated-life heat treatment anneal of 24 h at 773 K reduced the steady-state creep rate and increased the creep life of a rolled powder metallurgy Cu-8Cr-4Nb alloy. {yields} The primary microstructural difference between the rolled form and the annealed form of Cu-8Cr-4Nb is the development of annealing twins during heat treatment causing a decrease in the intensity of the texture. {yields} Friction stir welding of rolled Cu-8Cr-4Nb negatively affected creep ductility, thereby decreasing creep life at the temperature tested. Strain localization in the soft heat-affected zone of the weld is hypothesized to be the cause of the decreased creep ductility. - Abstract: Previous work has shown that rolling of an extruded Cu-8Cr-4Nb (GRCop-84) alloy results in higher steady-state creep rates over a range of stresses, leading to concern that other post-processing methods could have substantial deleterious effects on creep properties. To explore that possibility, constant-stress creep tests were conducted at 773 K on rolled GRCop-84 after it was subjected to either friction stir welding (FSW) or a 24 h 1073 K simulated-life heat treatment. The FSW had no measurable effect on the creep rate of the rolled material, but did have detrimental effects on the creep ductility caused by softening, and thus strain localization, in the heat-affected zone of the weld. The simulated-life heat treatment decreased the steady-state creep rate by approximately 45% as compared to the rolled material, leading to longer creep life at a particular applied stress. Electron backscatter diffraction methods were used to compare the microstructural features of extruded, rolled and annealed material forms. It was determined that the rolling procedure decreased the grain size, and decreased the intensity of the texture as compared to the extruded form. The simulated-life heat treatment allowed for the substantial development of twins along with minor grain growth, and

  11. The influence of post-processing on creep and microstructure of rolled Cu-8Cr-4Nb

    International Nuclear Information System (INIS)

    Walley, J.L.; Heelan, J.L.; Vettraino, L.G.; Groza, J.R.; Gibeling, J.C.

    2010-01-01

    Research highlights: → A simulated-life heat treatment anneal of 24 h at 773 K reduced the steady-state creep rate and increased the creep life of a rolled powder metallurgy Cu-8Cr-4Nb alloy. → The primary microstructural difference between the rolled form and the annealed form of Cu-8Cr-4Nb is the development of annealing twins during heat treatment causing a decrease in the intensity of the texture. → Friction stir welding of rolled Cu-8Cr-4Nb negatively affected creep ductility, thereby decreasing creep life at the temperature tested. Strain localization in the soft heat-affected zone of the weld is hypothesized to be the cause of the decreased creep ductility. - Abstract: Previous work has shown that rolling of an extruded Cu-8Cr-4Nb (GRCop-84) alloy results in higher steady-state creep rates over a range of stresses, leading to concern that other post-processing methods could have substantial deleterious effects on creep properties. To explore that possibility, constant-stress creep tests were conducted at 773 K on rolled GRCop-84 after it was subjected to either friction stir welding (FSW) or a 24 h 1073 K simulated-life heat treatment. The FSW had no measurable effect on the creep rate of the rolled material, but did have detrimental effects on the creep ductility caused by softening, and thus strain localization, in the heat-affected zone of the weld. The simulated-life heat treatment decreased the steady-state creep rate by approximately 45% as compared to the rolled material, leading to longer creep life at a particular applied stress. Electron backscatter diffraction methods were used to compare the microstructural features of extruded, rolled and annealed material forms. It was determined that the rolling procedure decreased the grain size, and decreased the intensity of the texture as compared to the extruded form. The simulated-life heat treatment allowed for the substantial development of twins along with minor grain growth, and a substantial

  12. In situ resistance measurements of bronze process Nb-Sn-Cu-Ta multifilamentary composite conductors during reactive diffusion

    International Nuclear Information System (INIS)

    Tan, K S; Hopkins, S C; Glowacki, B A; Majoros, M; Astill, D

    2004-01-01

    The conditions under which the Nb 3 Sn intermetallic layer is formed by solid-state reactive diffusion processes in bronze process multifilamentary conductors greatly influence the performance of the conductors. By convention, isothermal heat treatment is used and often causes non-uniformity of A15 layers formed across the wire. Therefore, characterization and optimization of the conductor during the reactive diffusion processes is crucial in order to improve the overall conductor's performance. In this paper, a different characterization approach and perhaps an optimization technique is presented, namely in situ resistance measurement by an alternating current (AC) method. By treating the components of such multifilamentary wires as a set of parallel resistors, the resistances of the components may be combined using the usual rules for resistors in parallel. The results show that the resistivity of the entire wire changes significantly during the reactive diffusion processes. The development of the Nb 3 Sn layer in bronze process Nb-Sn-Cu-Ta multifilamentary wires at different stages of the reactive diffusion processes has been monitored using measured resistivity changes, and correlated with results from DTA, ACS, SEM and EDS

  13. Solution-processed inorganic copper(I) thiocyanate (CuSCN) hole transporting layers for efficient p–i–n perovskite solar cells

    KAUST Repository

    Zhao, Kui

    2015-08-27

    CuSCN is a highly transparent, highly stable, low cost and easy to solution process HTL that is proposed as a low cost replacement to existing organic and inorganic metal oxide hole transporting materials. Here, we demonstrate hybrid organic-inorganic perovskite-based p-i-n planar heterojunction solar cells using a solution-processed copper(I) thiocyanate (CuSCN) bottom hole transporting layer (HTL). CuSCN, with its high workfunction, increases the open circuit voltage (Voc) by 0.23 V to 1.06 V as compared with devices based on the well-known poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) (0.83 V), resulting in a superior power conversion efficiency (PCE) of 10.8% without any notable hysteresis. Photoluminescence measurements suggest a similar efficiency of charge transfer at HTL/perovskite interface as PEDOT:PSS. However, we observe more efficient light harvesting in the presence of CuSCN at shorter wavelengths despite PEDOT:PSS being more transparent. Further investigation of the microstructure and morphology reveals differences in the crystallographic texture of the polycrystalline perovskite film, suggesting somewhat modified perovskite growth on the surface of CuSCN. The successful demonstration of the solution-processed inorganic HTL using simple and low temperature processing routes bodes well for the development of reliable and efficient flexible p-i-n perovskite modules or for integration as a front cell in hybrid tandem solar cells.

  14. A comparison of acoustic levitation with microgravity processing for containerless solidification of ternary Al-Cu-Sn alloy

    Science.gov (United States)

    Yan, N.; Hong, Z. Y.; Geng, D. L.; Wei, B.

    2015-07-01

    The containerless rapid solidification of liquid ternary Al-5 %Cu-65 %Sn immiscible alloy was accomplished at both ultrasonic levitation and free fall conditions. A maximum undercooling of 185 K (0.22 T L) was obtained for the ultrasonically levitated alloy melt at a cooling rate of about 122 K s-1. Meanwhile, the cooling rate of alloy droplets in drop tube varied from 102 to 104 K s-1. The macrosegregation was effectively suppressed through the complex melt flow under ultrasonic levitation condition. In contrast, macrosegregation became conspicuous and core-shell structures with different layers were formed during free fall. The microstructure formation mechanisms during rapid solidification at containerless states were investigated in comparison with the conventional static solidification process. It was found that the liquid phase separation and structural growth kinetics may be modulated by controlling both alloy undercooling and cooling rate.

  15. Investigation on Hot Workability of Homogenized Al-Zn-Mg-Cu Alloy Based on Activation Energy and Processing Map

    Science.gov (United States)

    Peng, Xiaoyan; Su, Wusen; Xiao, Dan; Xu, Guofu

    2018-06-01

    Hot deformation behaviors of the homogenized Al-Zn-Mg-Cu alloy were studied by uniaxial compression tests carried out at 623-743 K and strain rates of 0.01-10 s-1. The constitutive equation was developed for the activation energy, and thus the activation energy map was constructed. During the hot deformation, the dominated softening mechanisms were the dynamic recovery and dynamic recrystallization, which were most likely to be driven with increasing temperature and decreasing activation energy. Based on the superposition of the activation energy map and the processing map, together with the microstructure characteristics, the optimized hot workability of the alloy was proposed at the domain (670-743 K and 0.01-0.16 s-1), where the peak efficiency was 0.39 and the activation energy range was 196-260 kJ mol-1.

  16. Nanocrystalline FeSiBNbCu alloys: Differences between mechanical and thermal crystallization process in amorphous precursors

    International Nuclear Information System (INIS)

    Lopez, M.; Marin, P.; Agudo, P.; Carabias, I.; Venta, J. de la; Hernando, A.

    2007-01-01

    Nanocrystalline magnetic particles obtained by high energy ball milling of FeSiBNbCu alloy were prepared from rapidly quenched ribbons as a starting material. Structural characterization was made by using X-ray diffraction (XRD), differential scanning calorimetry (DSC), atomic force microscopy (AFM) and Moessbauer spectroscopy. The structural changes observed in this amorphous material suggest that nanocrystallization process takes place in a different way from the one induced by thermal treatments. Our different studies reveals that after short grinding times (up to 40 h) the material is composed by a two phase system of very fine nanocrystals embedded in a residual amorphous phase, while for largest periods of milling (from 140 h) the sample consists of a very fine nanocrystalline phase with a large fraction of grain boundary

  17. Multilayer Transparent Top Electrode for Solution Processed Perovskite/Cu(In,Ga)(Se,S)2 Four Terminal Tandem Solar Cells.

    Science.gov (United States)

    Yang, Yang Michael; Chen, Qi; Hsieh, Yao-Tsung; Song, Tze-Bin; Marco, Nicholas De; Zhou, Huanping; Yang, Yang

    2015-07-28

    Halide perovskites (PVSK) have attracted much attention in recent years due to their high potential as a next generation solar cell material. To further improve perovskites progress toward a state-of-the-art technology, it is desirable to create a tandem structure in which perovskite may be stacked with a current prevailing solar cell such as silicon (Si) or Cu(In,Ga)(Se,S)2 (CIGS). The transparent top electrode is one of the key components as well as challenges to realize such tandem structure. Herein, we develop a multilayer transparent top electrode for perovskite photovoltaic devices delivering an 11.5% efficiency in top illumination mode. The transparent electrode is based on a dielectric/metal/dielectric structure, featuring an ultrathin gold seeded silver layer. A four terminal tandem solar cell employing solution processed CIGS and perovskite cells is also demonstrated with over 15% efficiency.

  18. The mechanism of degradation of bisphenol A using the magnetically separable CuFe_2O_4/peroxymonosulfate heterogeneous oxidation process

    International Nuclear Information System (INIS)

    Xu, Yin; Ai, Jia; Zhang, Hui

    2016-01-01

    Highlights: • Copper ferrite (CuFe_2O_4) was fabricated and utilized in heterogeneous PMS process. • The influence of reaction parameters for the mineralization of BPA were evaluated. • Possible reaction mechanism and the stability of CuFe_2O_4 were investigated. • Surface bound radicals (mainly ·OH) may be responsible for the BPA degradation. - Abstract: The removal of bisphenol A (BPA) in aqueous solution by an oxidation process involving peroxymonosulfate (PMS) activated by CuFe_2O_4 magnetic nanoparticles (MNPs) is reported herein. The effects of PMS concentration, CuFe_2O_4 dosage, initial pH, initial BPA concentration, catalyst addition mode, and anions (Cl"−, F"−, ClO_4"− and H_2PO_4"−) on BPA degradation were investigated. Results indicate that nearly complete removal of BPA (50 mg/L) within 60 min and 84.0% TOC removal in 120 min could be achieved at neutral pH by using 0.6 g/L CuFe_2O_4 MNPs and 0.3 g/L PMS. The generation of reactive radicals (mainly hydroxyl radicals) was confirmed using electron paramagnetic resonance (EPR). Possible mechanisms on the radical generation from CuFe_2O_4/PMS system are proposed based on the results of radical identification tests and XPS analysis. The lack of inhibition of the reaction by free radical scavengers such as methanol and tert-butyl alcohol suggests that these species may not be generated in the bulk solution, and methylene blue probe experiments confirm that this process does not involve free radical generation. Surface-bound, rather than free radicals generated by a surface catalyzed-redox cycle involving both Fe(III) and Cu(II), are postulated to be responsible for the mineralization of bisphenol A.

  19. Structural evolution, thermomechanical recrystallization and electrochemical corrosion properties of Ni-Cu-Mg amorphous coating on mild steel fabricated by dual-anode electrolytic processing

    Energy Technology Data Exchange (ETDEWEB)

    Abdulwahab, M., E-mail: mabdulwahab@abu.edu.ng [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Metallurgical and Materials Engineering, Ahmadu Bello University, Zaria (Nigeria); Fayomi, O.S.I., E-mail: ojosundayfayomi3@gmail.com [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Mechanical Engineering, Covenant University, Ota (Nigeria); Popoola, A.P.I., E-mail: popoolaapi@tut.ac.za [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa)

    2016-07-01

    Highlights: • The surface of the coat containing Ni-Cu-Mg alloy on mild steel have sufficiently enhanced the properties. • Isothermally treated composites demonstrated 45% increase in the micro-hardness and 79.6% corrosion resistance. • The thermal stability of the developed Ni-Cu-Mg thin films on mild steel was excellent. - Abstract: The electrolytic Ni-Cu based alloy coating with admixed interfacial blend of Mg have been successfully prepared on mild steel substrate by dual anode electroplating processes over a range of applied current density and dwell time. The electrocodeposition of Ni-Cu-Mg coating was investigated in the presence of other bath additives. The influence of deposition current on surface morphology, adhesion behavior, preferred crystal orientation, surface topography and electrochemical activity of Ni-Cu-Mg alloy coating on mild steel were systematically examined. The thermal stability of the developed composite materials was examined via isothermal treatment. Scanning electron microscope equipped with EDS, X-ray diffraction, Atomic force microscope, micro-hardness tester and 3 μmetrohm Potentiostat/galvanostat were used to compare untreated and isothermally treated electrocodeposited composite. The induced activity of the Ni-Cu-Mg alloy changed the surface modification and results to crystal precipitation within the structural interface by the formation of Cu{sub ,} Ni{sub 2}Mg{sub 3} phase. The obtained results showed that the introduction of Mg particles in the plating bath generally modified the surface and brings an increase in the hardness and corrosion resistance of Ni-Cu-Mg layers fabricated. Equally, isothermally treated composites demonstrated an improved properties indicating 45% increase in the micro-hardness and 79.6% corrosion resistance which further showed that the developed composite is thermally stable.

  20. Depth Profile of Impurity Phase in Wide-Bandgap Cu(In1-x ,Ga x )Se2 Film Fabricated by Three-Stage Process

    Science.gov (United States)

    Wang, Shenghao; Nazuka, Takehiro; Hagiya, Hideki; Takabayashi, Yutaro; Ishizuka, Shogo; Shibata, Hajime; Niki, Shigeru; Islam, Muhammad M.; Akimoto, Katsuhiro; Sakurai, Takeaki

    2018-02-01

    For copper indium gallium selenide [Cu(In1-x ,Ga x )Se2, CIGS]-based solar cells, defect states or impurity phase always form due to both the multinary compositions of CIGS film and the difficulty of controlling the growth process, especially for high Ga concentration. To further improve device performance, it is important to understand such formation of impurity phase or defect states during fabrication. In the work presented herein, the formation mechanism of impurity phase Cu2-δ Se and its depth profile in CIGS film with high Ga content, in particular CuGaSe2 (i.e., CGS), were investigated by applying different growth conditions (i.e., normal three-stage process and two-cycle three-stage process). The results suggest that impurity phase Cu2-δ Se is distributed nonuniformly in the film because of lack of Ga diffusion. The formed Cu2-δ Se can be removed by etching the as-deposited CGS film with bromine-methanol solution, resulting in improved device performance.

  1. Formation of nanoparticles and defects in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} prepared by the metal organic deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Goswami, R. [Naval Research Laboratory, Washington, DC 20375 (United States); SAIC, Washington, DC 20003 (United States)], E-mail: goswami@anvil.nrl.navy.mil; Holtz, R.L. [Naval Research Laboratory, Washington, DC 20375 (United States); Rupich, M.W. [American Superconductors Inc., Westborough, MA 01581 (United States); Spanos, G. [Naval Research Laboratory, Washington, DC 20375 (United States)

    2007-11-15

    Nanoparticles and defects have been investigated using transmission electron microscopy in fully reacted YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO), prepared by the metal-organic deposition (MOD) process. Two types of particles, Y{sub 2}O{sub 3} and CuY{sub 2}O{sub 5}, ranging from 10 to 100 nm, have been observed in the YBCO matrix. The YBCO contains a large number of planar defects and a considerable number of (1 1 0) rotational twins. Details of the nanoparticles and defects in the MOD-processed YBCO films are presented in this paper.

  2. Preparation of PtSnCu/C and PtSn/C electrocatalysts and activation by dealloying processes for ethanol electrooxidation

    International Nuclear Information System (INIS)

    Crisafulli, Rudy

    2013-01-01

    PtSnCu/C (with different Pt:Sn:Cu atomic ratios) and PtSn/C (50:50) electrocatalysts were prepared by borohydride (BR) and alcohol-reduction (AR) processes using H 2 PtCl 6 .6H 2 O, SnCl 2 .2H 2 O and CuCl 2 .2H 2 O as metal sources, NaBH 4 and ethylene glycol as reducing agents, 2-propanol and ethylene glycol/water as solvents and carbon black as support. In a further step, these electrocatalysts were activated by chemical (CD) and electrochemical (ED) dealloying processes through acid treatment and thin porous coating technique, respectively. These materials were characterized by energy dispersive X-ray, Xray diffraction, transmission electron microscopy, line scan energy dispersive Xray and cyclic voltammetry. Electrochemical studies for ethanol electro-oxidation were performed by cyclic voltammetry, chronoamperometry and in single Direct Ethanol Fuel Cell using Membrane Electrode Assembly (MEA). The anodic effluents were analysed by gas chromatography. The X-ray diffractograms of the as-synthesized electrocatalysts showed the typical face-centered cubic structure (FCC) of platinum and its alloys. After dealloying, the X-ray diffractograms showed that the Pt FCC structure was preserved. The crystallite sizes of the assynthesized electrocatalysts were in the range of PtSnCu/C (50:40:10) AR/ED > PtSnCu/C (50:10:40) BR/CD. PtSn/C (50:50) BR/CD, PtSnCu/C (50:10:40) BR/CD, PtSnCu/C (50:40:10) AR/CD electrocatalysts and Pt/C BASF, PtSn/C (75:25) BASF commercial electrocatalysts were tested in single Direct Ethanol Fuel Cell. The results showed the following performance for ethanol electro-oxidation: PtSn/C (50:50) BR/CD > PtSnCu/C (50:40:10) AR/CD > PtSnCu/C > PtSn/C (75:25) BASF > PtSnCu/C (50:10:40) BR/CD > Pt/C BASF. (author)

  3. N-type Cu2O Film for Photocatalytic and Photoelectrocatalytic Processes: Its stability and Inactivation of E. coli

    International Nuclear Information System (INIS)

    Xiong, Liangbin; Ng, Tsz Wai; Yu, Ying; Xia, Dehua; Yip, Ho Yin; Li, Guiying; An, Taicheng; Zhao, Huijun; Wong, Po Keung

    2015-01-01

    Highlights: • Photoelectrocatalytic inactivation of E. coli by Cu 2 O film was firstly reported. • 7 log of E. coli could be completely inactivated in 2 h by Cu 2 O with a 0.1 V bias. • Charge transfer between Cu 2 O and E. coli was monitored by electrochemical technique. • Inactivation of E. coli by electric charges of electrodes was in-depth investigated. • Stability of N-type Cu 2 O as a photocatalyst was studied for the first time. - ABSTRACT: Photoelectrocatalytic (PEC) inactivation of Escherichia coli K-12 by cuprous oxide (Cu 2 O) film irradiated by visible light is firstly reported. A complete inactivation of about 7 log of E. coli was obtained for Cu 2 O film within 6 h. The bacterial inactivation efficiency was significantly improved in a photoelectrochemical cell, in which 7 log of E. coli could be completely inactivated within 2 h by Cu 2 O film with a 0.1 V bias. Electric charge transfer between electrodes and E. coli, and electric charge inactivation towards E. coli were investigated using membrane-separated reactor combined with short circuit photocurrent technique. H 2 O 2 , hole, and toxicity of Cu 2 O film were found responsible for the inactivation of E. coli. Toxicity of copper ions (including Cu 2+ and Cu + ) leakage from Cu 2 O films was determined and the results showed that the amount of leakage copper ions was not toxic to E. coli. Finally, the Cu 2 O film was proved to be effective and reusable for PC and PEC inactivation of E. coli

  4. Preparation of Cu2Sn3S7 Thin-Film Using a Three-Step Bake-Sulfurization-Sintering Process and Film Characterization

    Directory of Open Access Journals (Sweden)

    Tai-Hsiang Lui

    2015-01-01

    Full Text Available Cu2Sn3S7 (CTS can be used as the light absorbing layer for thin-film solar cells due to its good optical properties. In this research, the powder, baking, sulfur, and sintering (PBSS process was used instead of vacuum sputtering or electrochemical preparation to form CTS. During sintering, Cu and Sn powders mixed in stoichiometric ratio were coated to form the thin-film precursor. It was sulfurized in a sulfur atmosphere to form CTS. The CTS film metallurgy mechanism was investigated. After sintering at 500°C, the thin film formed the Cu2Sn3S7 phase and no impurity phase, improving its energy band gap. The interface of CTS film is continuous and the formation of intermetallic compound layer can increase the carrier concentration and mobility. Therefore, PBSS process prepared CTS can potentially be used as a solar cell absorption layer.

  5. Room-temperature-processed flexible n-InGaZnO/p-Cu2O heterojunction diodes and high-frequency diode rectifiers

    International Nuclear Information System (INIS)

    Chen, Wei-Chung; Hsu, Po-Ching; Chien, Chih-Wei; Chang, Kuei-Ming; Hsu, Chao-Jui; Chang, Ching-Hsiang; Lee, Wei-Kai; Chou, Wen-Fang; Wu, Chung-Chih; Hsieh, Hsing-Hung

    2014-01-01

    In this work, we report successful implementation of room-temperature-processed flexible n-InGaZnO/p-Cu 2 O heterojunction diodes on polyethylene naphthalate (PEN) plastic substrates using the sputtering technique. Using n-type InGaZnO and p-type Cu 2 O films deposited by sputtering at room temperature, flexible n-InGaZnO/p-Cu 2 O heterojunction diodes were successfully fabricated on PEN plastic substrates. The didoes on PEN substrates exhibited a low apparent turn-on voltage of 0.44 V, a high rectification ratio of up to 3.4 × 10 4 at ±1.2 V, a high forward current of 1 A cm −2 around 1 V and a decent ideality factor of 1.4, similar to the characteristics of n-InGaZnO/p-Cu 2 O diodes fabricated on glass substrates. The characterization of the frequency response of the room-temperature-processed flexible n-InGaZnO/p-Cu 2 O heterojunction diode rectifiers indicated that they are capable of high-frequency operation up to 27 MHz, sufficient for high-frequency (13.56 MHz) applications. Preliminary bending tests on diode characteristics and rectifier frequency responses indicate their promise for applications in flexible electronics. (paper)

  6. In-situ studies of the recrystallization process of CuInS2 thin films by energy dispersive X-ray diffraction

    International Nuclear Information System (INIS)

    Thomas, D.; Mainz, R.; Rodriguez-Alvarez, H.; Marsen, B.; Abou-Ras, D.; Klaus, M.; Genzel, Ch.; Schock, H.-W.

    2011-01-01

    Recrystallization processes during the sulfurization of CuInS 2 (CIS) thin films have been studied in-situ using energy dispersive X-ray diffraction (EDXRD) with synchrotron radiation. In order to observe the recrystallization isolated from other reactions occurring during film growth, Cu-poor, small grained CIS layers covered with CuS on top were heated in a vacuum chamber equipped with windows for synchrotron radiation in order to analyze the grain growth mechanism within the CIS layer. In-situ monitoring of the grain size based on diffraction line profile analysis of the CIS-112 reflection was utilized to interrupt the recrystallization process at different points. Ex-situ studies by electron backscatter diffraction (EBSD) and energy dispersive X-ray spectroscopy (EDX) performed on samples of intermediate recrystallization states reveal that during the heat treatment Cu and In interdiffuse inside the layer indicating the importance of the mobility of these two elements during CuInS 2 grain growth.

  7. Reduced thermal budget processing of Y--Ba--Cu--O high temperature superconducting thin films by metalorganic chemical vapor deposition

    International Nuclear Information System (INIS)

    Singh, R.; Sinha, S.; Hsu, N.J.; Ng, J.T.C.; Chou, P.; Thakur, R.P.S.; Narayan, J.

    1991-01-01

    Metalorganic chemical vapor deposition (MOCVD) has the potential of emerging as a viable technique to fabricate ribbons, tapes, coated wires, and the deposition of films of high temperature superconductors, and related materials. As a reduced thermal budget processing technique, rapid isothermal processing (RIP) based on incoherent radiation as the source of energy can be usefully coupled to conventional MOCVD. In this paper we report on the deposition and characterization of high quality superconducting thin films of Y--Ba--Cu--O (YBCO) on MgO and SrTiO 3 substrates by RIP assisted MOCVD. By using a mixture of N 2 O and O 2 as the oxygen source films deposited initially at 600 degree C for 1 min and then at 740 degree C for 30 min are primarily c-axis oriented and with zero resistance being observed at 84 and 89 K for MgO and SrTiO 3 substrates, respectively. The zero magnetic field current densities at 77 K for MgO and SrTiO 3 substrates are 1.2x10 6 and 1.5x10 6 A/cm 2 , respectively. It is envisaged that high energy photons from the incoherent light source and the use of a mixture of N 2 O and O 2 as the oxygen source, assist chemical reactions and lower overall thermal budget for processing of these films

  8. Influence of thermo-mechanical processing on the microstructure of Cu-based shape memory alloys produced by powder metallurgy

    International Nuclear Information System (INIS)

    Rodriguez, P.P.; Ibarra, A.; Iza-Mendia, A.; Recarte, V.; Perez-Landazabal, J.I.; San Juan, J.; No, M.L.

    2003-01-01

    Cu-Al-Ni shape memory alloys processed by powder metallurgy show very good thermo-mechanical properties, much better than those found in alloys produced by conventional casting. In this paper, we present the microstructural characterisation of these powder metallurgy alloys in order to find the microscopic mechanisms, linked to the powder metallurgy processing method, which are indeed responsible of such good thermo-mechanical behaviour. Electron microscopy studies [scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM)] show that powder metallurgy processing creates a sub-grain structure characterised by the presence of low angle sub-boundaries. These sub-boundaries are found to be lying on {1 1 0} and {1 1 2} lattice planes and are composed by an arrangement of superdislocations. These sub-boundaries may improve ductility in two ways: acting as a sink of dislocations which promotes plastic deformation and decreasing stress concentration at grain boundaries. Moreover, since sub-boundaries act as weak obstacles for the movement of martensite plates, the improvement on ductility is accomplished by an adequate thermo-mechanical behaviour

  9. Influence of relaxation processes on the evaluation of the metastable defect density in Cu(In,Ga)Se{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Maciaszek, M.; Zabierowski, P. [Faculty of Physics, Warsaw University of Technology, Koszykowa 75, Warszawa 00 662 (Poland)

    2016-06-07

    In this contribution, we investigated by means of numerical simulations the influence of relaxation processes related to metastable defects on electrical characteristics of Cu(In,Ga)Se{sub 2}. In particular, we analyzed the relaxation of a metastable state induced by illumination at a fixed temperature as well as the dependence of the hole concentration on the temperature during cooling. The knowledge of these two relaxation processes is crucial in the evaluation of the hole concentration in the relaxed state and after light soaking. We have shown that the distribution of the metastable defects can be considered frozen below 200 K. The hole capture cross section was estimated as ∼3 × 10{sup −15} cm{sup 2}. It was shown that the usually used cooling rates may lead to relevant changes of the hole concentration. We calculated the lower limit of the hole concentration after cooling, and we presented how it depends on densities of shallow acceptors and metastable defects. Moreover, we proposed a method which allows for the evaluation of shallow acceptor and metastable defect densities from two capacitance-voltage profiles measured in the relaxed and light soaking states. Finally, we indicated experimental conditions in which the influence of relaxation processes on the accuracy of this method is the smallest.

  10. Bonding Be to Cu alloys using a proprietary Brush Wellman process and new results for bonding Be to AlBeMet

    Energy Technology Data Exchange (ETDEWEB)

    Dombrowski, D.E. [Brush Wellman Inc., Cleveland, OH (United States)

    1998-01-01

    A novel process has been investigated for bonding of beryllium to copper alloys. The process is compatible with current manufacturing capabilities and can be readily scaled up from laboratory to production scale. The effect of process variations on the bond are shown. Also shown are several new approaches for direct bonding of beryllium to an AlBeMet interlayer. Bond strengths of Be/AlBeMet 162/Cu alloy couples are presented. (author)

  11. The role of metasomatism in the balance of halogens in ore-forming process at porphyry Cu-Mo deposits

    Science.gov (United States)

    Berzina, A. N.

    2009-04-01

    Volatile components play an important role in the evolution of ore-magmatic systems and their ore potential. Of special interest are fluorine and chlorine compounds that principally control the transportation of ore elements by the fluid in a magmatic process and under high-temperature hydrothermal conditions. Study of the evolution of fluorine-chlorine activity in the ore-forming process and their source is usually based on analysis of their magmatic history, whereas the additional source of fluorine and chlorine released during metasomatic alteration of rocks hosting mineralization is poorly discussed in the existing literature. Based on microprobe data on Cl and F abundances in halogen-containing minerals (biotite, amphibole, apatite, titanite) in intrusive rocks and their hydrothermally altered varieties, the role of metasomatic processes in the balance of volatiles in the ore-forming system is discussed by the example of porphyry Cu-Mo deposits of Siberia (Russia) and Mongolia. Two groups of the deposits are considered: copper-molybdenum (Erdenetiin Ovoo, Mongolia and Aksug, Russia) with prevailing propylitic and phyllic alteration and molybdenum-copper (Sora, Russia), with predominant potassic alteration. All types of hydrothermal alterations have led to drastic decrease in Cl contents in metasomatic minerals as compared with halogen-containing magmatic minerals. All studied deposits (particularly those where propylitic and phyllic alteration were developed) show a nearly complete chlorine removal from altered halogen-containing rock-forming minerals (biotite and amphibole). The Cl content in amphibole decreases several times at the stage of replacement with actinolite in the process of propylitization. In the later chlorites (ripidolite and brunsvigite) that replace amphibole, actinolite, and biotite, chlorine is not detected by microprobe (detection limit 0.01-0.02% Cl). Chlorine was also not detected in white micas (muscovite-phengite series) in quartz

  12. Fabrication of Surface Level Cu/Si Cp Nano composites by Friction Stir Processing Route

    International Nuclear Information System (INIS)

    Srinivasan, R. C.; Karunanithi, M.

    2015-01-01

    Friction stir processing (FSP) technique has been successfully employed as low energy consumption route to prepare copper based surface level nano composites reinforced with nano sized silicon carbide particles (Si Cp). The effect of FSP parameters such as tool rotational speed, processing speed, and tool tilt angle on microstructure and microhardness was investigated. Single pass FSP was performed based on Box-Behnken design at three factors in three levels. A cluster of blind holes 2 mm in diameter and 3 mm in depth was used as particulate deposition technique in order to reduce the agglomeration problem during composite fabrication. K-type thermocouples were used to measure temperature histories during FSP. The results suggest that the heat generation during FSP plays a significant role in deciding the microstructure and microhardness of the surface composites. Microstructural observations revealed a uniform dispersion of nano sized Si Cp without any agglomeration problem and well bonded with copper matrix at different process parameter combinations. X-ray diffraction study shows that no intermetallic compound was produced after processing. The microhardness of nano composites was remarkably enhanced and about 95% more than that of copper matrix

  13. Fabrication of Surface Level Cu/SiCp Nanocomposites by Friction Stir Processing Route

    Directory of Open Access Journals (Sweden)

    Cartigueyen Srinivasan

    2015-01-01

    Full Text Available Friction stir processing (FSP technique has been successfully employed as low energy consumption route to prepare copper based surface level nanocomposites reinforced with nanosized silicon carbide particles (SiCp. The effect of FSP parameters such as tool rotational speed, processing speed, and tool tilt angle on microstructure and microhardness was investigated. Single pass FSP was performed based on Box-Behnken design at three factors in three levels. A cluster of blind holes 2 mm in diameter and 3 mm in depth was used as particulate deposition technique in order to reduce the agglomeration problem during composite fabrication. K-type thermocouples were used to measure temperature histories during FSP. The results suggest that the heat generation during FSP plays a significant role in deciding the microstructure and microhardness of the surface composites. Microstructural observations revealed a uniform dispersion of nanosized SiCp without any agglomeration problem and well bonded with copper matrix at different process parameter combinations. X-ray diffraction study shows that no intermetallic compound was produced after processing. The microhardness of nanocomposites was remarkably enhanced and about 95% more than that of copper matrix.

  14. 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...

  15. Crystallite-growth, phase transition, magnetic properties, and sintering behaviour of nano-CuFe2O4 powders prepared by a combustion-like process

    International Nuclear Information System (INIS)

    Köferstein, Roberto; Walther, Till; Hesse, Dietrich; Ebbinghaus, Stefan G.

    2014-01-01

    The synthesis of nano-crystalline CuFe 2 O 4 powders by a combustion-like process is described herein. Phase formation and evolution of the crystallite size during the decomposition process of a (CuFe 2 )—precursor gel were monitored up to 1000 °C. Phase-pure nano-sized CuFe 2 O 4 powders were obtained after reaction at 750 °C for 2 h resulting in a crystallite size of 36 nm, which increases to 96 nm after calcining at 1000 °C. The activation energy of the crystallite growth process was calculated as 389 kJ mol −1 . The tetragonal⇄cubic phase transition occurs between 402 and 419 °C and the enthalpy change (ΔH) was found to range between 1020 and 1229 J mol −1 depending on the calcination temperature. The optical band gap depends on the calcination temperature and was found between 2.03 and 1.89 eV. The shrinkage and sintering behaviour of compacted powders were examined. Dense ceramic bodies can be obtained either after conventional sintering at 950 °C or after a two-step sintering process at 800 °C. Magnetic measurements of both powders and corresponding ceramic bodies show that the saturation magnetization rises with increasing calcination-/sintering temperature up to 49.1 emu g −1 (2.1 µ B fu −1 ), whereas the coercivity and remanence values decrease. - Graphical abstract: A cheap one-pot synthesis was developed to obtain CuFe 2 O 4 nano-powders with different crystallite sizes (36–96 nm). The optical band gaps, phase transition temperatures and enthalpies were determined depending on the particle size. The sintering behaviour of nano CuFe 2 O 4 was studied in different sintering procedures. The magnetic behaviour of the nano-powders as well as the corresponding ceramic bodies were investigated. - Highlights: • Eco-friendly and simple synthesis for nano CuFe 2 O 4 powder using starch as polymerization agent. • Monitoring the phase evolution and crystallite growth kinetics during the synthesis. • Determination of the optical band gap

  16. Microstructure and sliding wear characterization of Cu/TiB2 copper matrix composites fabricated via friction stir processing

    Directory of Open Access Journals (Sweden)

    I. Dinaharan

    2017-09-01

    Full Text Available The poor wear performance of copper is improved by reinforcing hard ceramic particles. The present work reports the fabrication of Cu/TiB2 (0, 6, 12, 18 vol.% copper matrix composites (CMCs using friction stir processing (FSP. TiB2 particles were initially packed together into a machined groove and were subjected to FSP under a constant set of process parameters. The microstructure was observed using optical, scanning and transmission electron microscopy. The wear behavior was examined using a pin-on-disc apparatus. The micrographs showed a homogeneous distribution of TiB2 particles without aggregation and segregation. The distribution of TiB2 particles was closely persistent across the stir zone. TiB2 particles were well bonded with the copper matrix without any interfacial reaction. Many TiB2 particles fractured during FSP. The grains in the composite were extensively refined because of dynamic recrystallization and pinning effect of TiB2 particles. The wear behavior under dry sliding condition was presented in detail.

  17. The Effect of Carrier Properties on the Ballistic Processing of Sn-0.7 Cu Thick Films

    Science.gov (United States)

    Hille, David M.

    The need for metallic films has increased since the creation of electronic components. The continued miniaturization of systems and components has led to a greater demand for both thick and thin films, especially in the technology field. Computers, hand held devices, and solar cells are a few of the multitudes of uses for these films. This thesis investigates a novel additive manufacturing process known as Ballistic Manufacturing (BM), invented at the Advanced Materials Processing Lab (AMPL) at San Diego State University. Lead free solder (Tin (Sn)-0.7%Copper (Cu)) was chosen as the testing material due to its low melting temperature. The effects of varying thermal conductivity via the change in carrier material type, the effect of raising substrate temperature, and surface finish differences were investigated. An increase in thermal conductivity resulted in an increase in film thickness and decrease in cell size. As substrate temperature was raised, film thickness decreased, while cell size decreased. Surface finish provided a proof of concept to the transfer of substrate features to the resultant film surface. Evaluation of dendritic microstructures led to relative cooling rates reflective of changes in parameters. The mechanical behavior was also investigated using tensile tests to determine stress-stain relationships and measure elastic modulus. With the current work of this thesis, and previous work by Cavero and Stewart, Ballistic Manufacturing is proven to be an alternative method in the production of metallic films.

  18. Effect of ammonium hydroxide on preparation process of YBa2Cu3O7-x superconductor by sol gel method

    Directory of Open Access Journals (Sweden)

    H Arabi

    2006-09-01

    Full Text Available  In this paper the effect of ammonium hydroxide addition to the solution of metallic oxide on sol gel preparation process of YBCO is studied with differential thermal analysis, thermal graviometry and X-ray diffraction. Two samples with and without ammonium hydroxide. Ammonium hydroxide prevents both barium nitrate precipitate during the gel preparation and also unwanted reaction as well as increasing homogeneous product. After drying the gel, the samples heated up to 1050°C in DTA apparatus in order to find more accurate the type and the temperature of reaction during the preparation process. After the initial reactions in the samples, Y2Cu2O5 and 123 phases are created in the range of 780-840°C and then the 123 phase is strengthened at 900-950°C. As shown in X-ray data, 123 was the only phase after this range. In addition ammonium hydroxide support and increase the creation of 123 phase at lower temperature.

  19. The influence of target oxygen on the YBa2Cu3O6+δ DC Magnetron sputtering process

    International Nuclear Information System (INIS)

    Larsson, G.; Selinder, T.I.; Helmersson, U

    1990-01-01

    The oxygen partial pressure and the target potential have been monitored under a range of process conditions during single target dc magnetron sputtering of Y-Ba-Cu-O. The introduced sputtering gas consisted in all but one instance of pure argon and hence the oxygen present in the plasma originated mainly from the target. During the first hours of sputtering the oxygen partial pressure was of the same magnitude as the argon pressure (3.0 Pa). As the oxygen was released from the target and subsequently removed by pumping, the target potential increased and the film composition became more stoichiometric. After 30-40 hours of sputtering the target potential and the oxygen pressure stabilized and the film composition was equal to that of the stoichiometric target. If an oxygen flow exceeding a critical level was mixed into the sputtering gas the target potential and the deposition rate decreased swiftly. This was due to target oxidation, further manifested in changing plasma and target colours. In some instances the stabilization after 'presputtering' was incomplete and oscillations in target voltage and oxygen partial pressure were observed. The fluctuations made it virtually impossible to obtain stoichiometric films. The oscillative behaviour of the sputtering process is tentatively explained by a target temperature dependent oxygen diffusion. (au)

  20. Age-hardening of an Al-Li-Cu-Mg alloy (2091) processed by high-pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seungwon, E-mail: chominamlsw@gmail.com [Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); WPI, International Institute for Carbon-Neutral Energy Research (I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); Horita, Zenji [Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); WPI, International Institute for Carbon-Neutral Energy Research (I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); Hirosawa, Shoichi [Department of Mechanical Engineering and Materials Science, Yokohama National University, Yokohama 240-8501 (Japan); Matsuda, Kenji [Graduate School of Science and Engineering for Research, University of Toyama, Toyama 930-8555 (Japan)

    2012-06-01

    This research presents the successful strengthening of an Al-Li-Cu-Mg alloy (2091) through the simultaneous use of grain refinement and age hardening. Following solid-solution treatment, the alloy was processed by high-pressure torsion (HPT) at room temperature and the grain size was refined to {approx}140 nm. The Vickers microhardness increased with increasing strain, and saturated to a constant level of 225 Hv. A further increase in the hardness to {approx}275 Hv was achieved by aging the HPT-processed alloy at 100 Degree-Sign C and 150 Degree-Sign C. Bending tests for the samples treated using the peak aging conditions demonstrated that the stress was significantly increased while considerable ductility was retained. Transmission electron microscopy revealed that the small grains are well retained even after prolonged aging, and the precipitation of fine {delta} Prime particles occurred within the small grains, which confirms that simultaneous strengthening from grain refinement and age hardening is feasible in this alloy.

  1. Development of novel processes for Cu concentrates without producing sulfuric acid; Hiryusan hasseigata no atarashii doshigen shori gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Awakura, Y; Hirato, T [Kyoto University, Kyoto (Japan)

    1997-02-01

    Studies are conducted to develop a new wet method for copper concentrates to replace the conventional dry smelting method for the settlement of problems involving the processing of impurities for environmental protection. A specimen of pyrites polycrystals is subjected to leaching at 80 {degree}C in a strongly acidic cupric solution. Findings are that the element sulfur generated in this process does not impede leaching and only approximately 4% of the sulfur is oxidized into sulfur ions; that the presence of more than 2g/liter of bromide ions produced during bromine-aid leaching of gold changes the structure of sulfur for the inhibition of leaching; that circulation of a bromine-containing leaching liquid is not desired since even a small amount of approximately 0.02mol/liter inhibits the leaching rate. Controlled potential electrolysis is performed for the anode in an acid solution containing CuCl, NaCl, and NaBr, for the observation of oxidation/reduction potentials predicted by Nernst`s equation. It is then disclosed that bromine is more effective than chlorine in gold leaching and that the solution potential during leaching agent regeneration enables the monitoring of solution constitution. 2 refs.

  2. Influence of Temperature on Mechanical Behavior During Static Restore Processes of Al-Zn-Mg-Cu High Strength Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    ZHANG Kun

    2017-06-01

    Full Text Available Flow stress behaviors of as-cast Al-Zn-Mg-Cu high strength aluminum alloy during static restore processes were investigated by: Isothermal double-pass compression tests at temperatures of 300-400℃, strain rates of 0.01-1 s-1, strains of 33% +20% with the holding times of 0~900 s after the first pass compression. The results indicate that the deformation temperature has a dramatical effect on mechanical behaviors during static restore processes of the alloy. (1 At 300 ℃ and 330 ℃ lower temperatures, the recovery during the deformation is slow, and deformation energy stored in matrix is higher, flow stresses at the second pass deformation decreased during the recovery and recrystallization, and the stress softening phenomena is observed. Stress softening is increased with the increasing holding time; Precipitation during the holding time inhibites the stress softening. (2 At 360 ℃ and 400 ℃ higher temperatures, the recovery during deformation is rapid, and deformation energy stored in matrix is lower. Solid solubility is higher after holding, so that flow stress at the second pass deformation is increased, stress hardening phenomena is observed. Stress hardening decreased with the increasing holding time duo to the recovery and recrystallization during holding period at 360 ℃; Precipitation during holding also inhibited the stress softening. However, Stress hardening remains constant with the increasing holding time duo to the reasanenal there are no recovery and recrystallization during holding period at 400 ℃.

  3. Processing-Microstructure-Property Relationships for Cold Spray Powder Deposition of Al-Cu Alloys

    Science.gov (United States)

    2015-06-01

    Champagne [18]. The simulations were completed to compare the simulated particle exit velocities versus the measured particle exit velocities. In...620 m/s to 670 m/s [39]. V. Champagne states that for pure aluminum, an acceptable critical velocity for the deposition of pure aluminum is anything...Materials and Processess, vol. 168, no. 5, pp. 53–55, May 2010. [3] V. K. Champagne and P. F. Leyman, “Cold Spray Process Development for the Reclamation

  4. Cu-Doped ZnO Thin Films Deposited by a Sol-Gel Process Using Two Copper Precursors: Gas-Sensing Performance in a Propane Atmosphere

    Directory of Open Access Journals (Sweden)

    Heberto Gómez-Pozos

    2016-01-01

    Full Text Available A study on the propane gas-sensing properties of Cu-doped ZnO thin films is presented in this work. The films were deposited on glass substrates by sol-gel and dip coating methods, using zinc acetate as a zinc precursor, copper acetate and copper chloride as precursors for doping. For higher sensitivity values, two film thickness values are controlled by the six and eight dippings, whereas for doping, three dippings were used, irrespective of the Cu precursor. The film structure was analyzed by X-ray diffractometry, and the analysis of the surface morphology and film composition was made through scanning electron microscopy (SEM and secondary ion mass spectroscopy (SIMS, respectively. The sensing properties of Cu-doped ZnO thin films were then characterized in a propane atmosphere, C3H8, at different concentration levels and different operation temperatures of 100, 200 and 300 °C. Cu-doped ZnO films doped with copper chloride presented the highest sensitivity of approximately 6 × 104, confirming a strong dependence on the dopant precursor type. The results obtained in this work show that the use of Cu as a dopant in ZnO films processed by sol-gel produces excellent catalysts for sensing C3H8 gas.

  5. Self-doping processes between planes and chains in the metal-to-superconductor transition of YBa2Cu3O6.9.

    Science.gov (United States)

    Magnuson, M; Schmitt, T; Strocov, V N; Schlappa, J; Kalabukhov, A S; Duda, L-C

    2014-11-12

    The interplay between the quasi 1-dimensional CuO-chains and the 2-dimensional CuO2 planes of YBa(2)Cu(3)O(6+x) (YBCO) has been in focus for a long time. Although the CuO-chains are known to be important as charge reservoirs that enable superconductivity for a range of oxygen doping levels in YBCO, the understanding of the dynamics of its temperature-driven metal-superconductor transition (MST) remains a challenge. We present a combined study using x-ray absorption spectroscopy and resonant inelastic x-ray scattering (RIXS) revealing how a reconstruction of the apical O(4)-derived interplanar orbitals during the MST of optimally doped YBCO leads to substantial hole-transfer from the chains into the planes, i.e. self-doping. Our ionic model calculations show that localized divalent charge-transfer configurations are expected to be abundant in the chains of YBCO. While these indeed appear in the RIXS spectra from YBCO in the normal, metallic, state, they are largely suppressed in the superconducting state and, instead, signatures of Cu trivalent charge-transfer configurations in the planes become enhanced. In the quest for understanding the fundamental mechanism for high-Tc-superconductivity (HTSC) in perovskite cuprate materials, the observation of such an interplanar self-doping process in YBCO opens a unique novel channel for studying the dynamics of HTSC.

  6. Obtainment of the alloy Cu13Al4Ni using processed by powder metallurgy; Obtencao da liga Cu13Al4Ni via metalurgia do po

    Energy Technology Data Exchange (ETDEWEB)

    Grossi, L.J.; Damasceno, N.; Muterlle, P.V., E-mail: larajgrossi@yahoo.com.br [Universidade de Brasilia (UnB), Brasilia, DF (Brazil). Departamento de Engenharia Mecanica

    2016-07-01

    The powder metallurgy is a technique environmentally advantageous that allows the production of many pieces, with a good superficial finishing and dimensional tolerance. For the production of pieces using technique, basics steps are carried out, as the characterization of powders, the mixing and homogenization, compacting and sintering. In this context, this work has as objective the obtainment of the Cu13Al4Ni alloy via powder metallurgy. For this, was made a high energy milling for 2, 4 and 8 hours. Then, the milled powder was compacted and posteriorly, sintered in an oven with controlled atmosphere. It was observed that the milling time affects directly in sintering of the pieces. The best results obtained were for the samples that were milled for 4 hours. This samples have showed 21, 52% of porosity and 6,382 g/cm³ of the density of sintered. (author)

  7. Sol-gel process for preparing YBa2Cu4O8 precursors from Y, Ba, and Cu acidic acetates/ammonia/ascorbic acid systems

    International Nuclear Information System (INIS)

    Deptula, A.; Lada, W.; Olczak, T.; Goretta, K.C.

    1995-08-01

    Sols were prepared by addition of ammonia to acidic acetate solutions of Y 3+ , Ba 2+ , and Cu 2+ . Ascorbic acid was added to a part of the sol. The resultant sols were gelled to a shard, a film, or microspheres by evaporation at 60 C or by extraction of water from drops of emulsion suspended in 2-ethylhexanol-1. Addition of ethanol to the sols facilitated the formation of gel films, fabricated by a dipping technique, on glass or silver substrates. At 100 C, gels that were formed in the presence of ascorbic acid were perfectly amorphous, in contrast to the crystalline acetate gels. Conversion of the amorphous ascorbate gels to final products was easier than for the acetate gels. The quality of coatings prepared from ascorbate gels was superior to that of acetate gel coatings

  8. Effects of Post-Sinter Processing on an Al–Zn–Mg–Cu Powder Metallurgy Alloy

    Directory of Open Access Journals (Sweden)

    Matthew David Harding

    2017-09-01

    Full Text Available The objective of this work was to study the effects of several post-sinter processing operations (heat-treatment, sizing, shot peening on a press-and-sinter 7xxx series aluminum powder metallurgy (PM alloy. The characterization of the products was completed through a combination of non-contact surface profiling, hardness measurements, differential scanning calorimetry (DSC, transmission electron microscopy (TEM, X-ray diffraction (XRD, tensile, and three-point bend fatigue testing. It was determined that sizing in the as-quenched state imparted appreciable reductions in surface hardness (78 HRB and fatigue strength (168 MPa relative to counterpart specimens that were sized prior to solutionizing (85 HRB and 228 MPa. These declines in performance were ascribed to the annihilation of quenched in vacancies that subsequently altered the nature of precipitates within the finished product. The system responded well to shot peening, as this process increased fatigue strength to 294 MPa. However, thermal exposure at 353 K (80 °C and 433 K (160 °C then reduced fatigue performance to 260 MPa and 173 MPa, respectively, as a result of residual stress relaxation and in-situ over-aging.

  9. CuO reduction induced formation of CuO/Cu2O hybrid oxides

    Science.gov (United States)

    Yuan, Lu; Yin, Qiyue; Wang, Yiqian; Zhou, Guangwen

    2013-12-01

    Reduction of CuO nanowires results in the formation of a unique hierarchical hybrid nanostructure, in which the parent oxide phase (CuO) works as the skeleton while the lower oxide (Cu2O) resulting from the reduction reaction forms as partially embedded nanoparticles that decorate the skeleton of the parent oxide. Using in situ transmission electron microscopy observations of the reduction process of CuO nanowires, we demonstrate that the formation of such a hierarchical hybrid oxide structure is induced by topotactic nucleation and growth of Cu2O islands on the parent CuO nanowires.

  10. A new wire fabrication processing using high Ga content Cu-Ga compound in V3Ga compound superconducting wire

    International Nuclear Information System (INIS)

    Hishinuma, Yoshimitsu; Nishimura, Arata; Kikuchi, Akihiro; Iijima, Yasuo; Takeuchi, Takao

    2007-01-01

    A superconducting magnet system is also one of the important components in an advanced magnetic confinement fusion reactor. Then it is required to have a higher magnetic field property to confine and maintain steady-sate burning deuterium (D)-tritium (T) fusion plasma in the large interspace during the long term operation. Burning plasma is sure to generate 14 MeV fusion neutrons during deuterium-tritium reaction, and fusion neutrons will be streamed and penetrated to superconducting magnet through large ports with damping neutron energy. Therefore, it is necessary to consider carefully not only superconducting property but also neutron irradiation property in superconducting materials for use in a future fusion reactor, and a 'low activation and high field superconducting magnet' will be required to realize the fusion power plant beyond International Thermonuclear Experimental Reactor (ITER). V-based superconducting material has a much shorter decay time of induced radioactivity compared with the Nb-based materials. We thought that the V 3 Ga compound was one of the most promising materials for the 'low activation and higher field superconductors' for an advanced fusion reactor. However, the present critical current density (J c ) property of V 3 Ga compound wire is insufficient for apply to fusion magnet applications. We investigated a new route PIT process using a high Ga content Cu-Ga compound in order to improve the superconducting property of the V 3 Ga compound wire. (author)

  11. Temporal-contextual processing in working memory: evidence from delayed cued recall and delayed free recall tests.

    Science.gov (United States)

    Loaiza, Vanessa M; McCabe, David P

    2012-02-01

    Three experiments are reported that addressed the nature of processing in working memory by investigating patterns of delayed cued recall and free recall of items initially studied during complex and simple span tasks. In Experiment 1, items initially studied during a complex span task (i.e., operation span) were more likely to be recalled after a delay in response to temporal-contextual cues, relative to items from subspan and supraspan list lengths in a simple span task (i.e., word span). In Experiment 2, items initially studied during operation span were more likely to be recalled from neighboring serial positions during delayed free recall than were items studied during word span trials. Experiment 3 demonstrated that the number of attentional refreshing opportunities strongly predicts episodic memory performance, regardless of whether the information is presented in a spaced or massed format in a modified operation span task. The results indicate that the content-context bindings created during complex span trials reflect attentional refreshing opportunities that are used to maintain items in working memory.

  12. Twinning processes in Cu-Al-Ni martensite single crystals investigated by neutron single crystal diffraction method

    International Nuclear Information System (INIS)

    Molnar, P.; Sittner, P.; Novak, V.; Lukas, P.

    2008-01-01

    A neutron single crystal diffraction method for inspecting the quality of martensite single crystals is introduced. True interface-free martensite single crystals are indispensable for, e.g. measurement of elastic constants of phases by ultrasonic techniques. The neutron diffraction method was used to detect and distinguish the presence of individual lattice correspondence variants of the 2H orthorhombic martensite phase in Cu-Al-Ni as well as to follow the activity of twinning processes during the deformation test on the martensite variant single crystals. When preparing the martensite single variant prism-shaped crystals by compression deformation method, typically a small fraction of second unwanted martensitic variant (compound twin) remains in the prism samples. Due to the very low stress (∼1 MPa) for the compound twinning in many shape memory alloys, it is quite difficult not only to deplete the martensite prisms of all internal interfaces but mainly to keep them in the martensite single variant state for a long time needed for further investigations

  13. Microstructure and Texture in Surface Deformation Layer of Al-Zn-Mg-Cu Alloy Processed by Milling

    Directory of Open Access Journals (Sweden)

    CHEN Yanxia

    2017-12-01

    Full Text Available The microstructural and crystallographic features of the surface deformation layer in Al-Zn-Mg-Cu alloy induced by milling were investigated by means of transmission electron microscopy (TEM and precession electron diffraction (PED assisted nanoscale orientation mapping. The result shows that the surface deformation layer is composed by the top surface of equiaxed nanograins/ultrafine grains and the subsurface of lamellar nanograins/ultrafine grains surrounded by coarse grain boundary precipitates (GBPs. The recrystallized nanograins/ultrafine grains in the deformation layer show direct evidence that dynamic recrystallization plays an important role in grain refining process. The GBPs and grain interior precipitates (GIPs show a great difference in size and density with the matrix due to the thermally and mechanically induced precipitate redistribution. The crystallographic texture of the surface deformation layer is proved to be a mixture of approximate copper{112}, rotated cube{001} and F {111}. The severe shear deformation of the surface induced by milling is responsible for the texture evolution.

  14. Development of novel processes for Cu concentrates without producing sulfuric acid; Hiryusan hasseigata no atarashii doshigen shori gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, T; Noguchi, F; Takasu, T; Ito, H [Kyushu Inst. of Technology, Kitakyushu (Japan). Faculty of Engineering

    1997-02-01

    In the refining process for the production of copper from pyrites, heat treatment is carried out in a neutral atmosphere so that part of the sulphur will be collected in the form of simple sulfur and that pyrites naturally low in reactivity will be made active. A basic study is also conducted of a very high speed electrolytic method. The chemical aspects of pyrites which are various in composition (mainly CuFeS2) are clarified by X-ray diffraction, and then is subjected to heat-treatment in a 773K-1073K argon atmosphere. There is a decrease in the amount of sulfur at a temperatures not lower than 973K. The X-ray main diffraction line splits for the emergence of some lower angle diffraction lines. The specimen is then subjected to a leach test in a copper chloride base liquor, to disclose that leachability grows remarkably higher in the presence of a great change in the X-ray diffraction lattice constant. An experiment follows in which an electrolyte is allowed to flow at a high speed for accelerating the rate of electrolytic refining in an effort to prevent the passivation of anode and deposition of dendrite on the cathode that is apt to occur when the current density is high. Passivation is prevented when the flow rate is 10m/min or higher in the vicinity of the anode surface for the formation of a smooth electrodeposited surface. 2 refs., 2 figs., 2 tabs.

  15. Solution processible Cu{sub 2}SnS{sub 3} thin films for cost effective photovoltaics: Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Sandra, E-mail: dias.sandra123@gmail.com; Murali, Banavoth; Krupanidhi, S.B.

    2015-11-01

    Thin films of Cu{sub 2}SnS{sub 3} (CTS) were deposited by the facile solution processed sol–gel route followed by a low-temperature annealing. The Cu–Sn-thiourea complex formation was analysed using Fourier Transform Infrared spectrophotometer (FTIR). The various phase transformations and the deposition temperature range for the initial precursor solution was determined using Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). X-Ray Diffraction (XRD) studies revealed the tetragonal phase formation of the CTS annealed films. Raman spectroscopy studies further confirmed the tetragonal phase formation and the absence of any deterioratory secondary phases. The morphological investigations and compositional analysis of the films were determined using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) respectively. Atomic Force Microscopy (AFM) was used to estimate the surface roughness of 1.3 nm. The absorption coefficient was found to be 10{sup 4} cm{sup −1} and bandgap 1.3 eV which qualifies CTS to be a potential candidate for photovoltaic applications. The refractive index, extinction coefficient and relative permittivity of the film were measured by Spectroscopic ellipsometry. Hall effect measurements, indicated the p type nature of the films with a hole concentration of 2 × 10{sup 18} cm{sup −3}, electrical conductivity of 9 S/cm and a hole mobility of 29 cm{sup 2}/V. The properties of CTS as deduced from the current study, present CTS as a potential absorber layer material for thin film solar cells. - Highlights: • Cu{sub 2}SnS{sub 3} thin films have been synthesized by spin coating of a precursor solution. • The Cu–Sn-thiourea complex precursor was analysed. • The structural, optical and electrical properties of the thin films were studied. • Totally 24 infra-red, 30 optical, 29 Raman and 30 hyper Raman modes are active. • Refractive index, extinction coefficient and relative

  16. Damage in Creep Aging Process of an Al-Zn-Mg-Cu Alloy: Experiments and Modeling

    Directory of Open Access Journals (Sweden)

    Chao Lei

    2018-04-01

    Full Text Available In creep age forming (CAF, large integral panel components of high-strength aluminum alloy can be shaped and strengthened under external elastic loading at an elevated temperature through creep deformation and age hardening, simultaneously. However, the high ribbed structure on panel may induce stress concentration, inhomogeneous plastic deformation and even damage evolution on the bending rib, leading to the difficulty in controlling forming precision and material properties. Therefore, the generation and evolution of damage are necessary to be considered in the design of CAF. Taking 7050 aluminum alloy as the case material, the continuous and interrupted creep aging tests at 165 °C and three stress levels (300, 325, and 350 MPa were conducted, and the corresponding material properties, precipitate, and damage microstructures were studied by mechanical properties tests, transmission electron microscope (TEM and scanning electron microscope (SEM characterizations. With the increase of stress level, the creep deformation occurs easier, the precipitates grow up faster, the creep damage occurs earlier, the growth rate and the size of microvoids increase, the mechanical properties decrease more rapidly, and the dominant mechanism of creep fracture changes from shear to microvoid coalescence. To simulate creep aging behavior with damage, a continuum damage mechanics (CDM based model is calibrated and numerically implemented into ABAQUS solver via CREEP subroutine. The CAF of 7050 aluminum alloy panels with different height ribs were conducted by experiment and FE simulation. The forming process presents a typical stress relaxation phenomenon. The creep damage mainly occurs on the bending rib due to the severe stress concentration. With the increase of rib height, the creep strain and damage degree increase, but the springback decreases.

  17. Effects of calcium doping on the superconducting properties of top-seeded melt growth processed Y1.5Ba2-xCaxCu3Oy superconductors

    International Nuclear Information System (INIS)

    Park, S.D.; Kim, H.J.; Park, B.J.; Han, Y.H.; Jun, B.-H.; Lee, J.S.; Kim, C.-J.

    2011-01-01

    We study effects of calcium doping in melt processed Y123 superconductors. We examine a superconducting transition temperature and current density. A transition temperature and current density decreases by calcium doping. Calcium doping leads to coarseing of Y211 particles. Y211 refining effect by CeO 2 is disappreared by calcium doping. The effect of calcium doping on the superconducting properties of top seeded melt growth (TSMG) processed Y 1.5 Ba 2-x Ca x Cu 3 O y superconductors was studied in terms of calcium content (X ca ). YBa 2-x Ca x Cu 3 O 7-δ (X ca = 0, 0.005, 0.01, 0.02, 0.04, 0.1, 0.3) powders were synthesized by the powder calcination method. YBa 2-x Ca x Cu 3 O 7-δ powders were mixed with 0.25 mole Y 2 O 3 powder and 1 wt.% CeO 2 as Y 2 BaCuO 5 (Y211) refiner, and finally made into Y 1 . 5 Ba 2-x Ca x Cu 3 O y (Y1.5) + 1 wt.% CeO 2 composition. The single Y123 growth on the top surface was observed up to X ca = 0.1, while the multiple Y123 growth was observed at X ca ≥ 0.1. The superconducting transition temperature (T c ) and critical current density (J c ) of TSMG processed Y1.5 samples were inversely proportional to X ca . The Y211 size increased with increasing X ca due to the enhancement of Y211 coarsening by calcium doping. No Y211 refining effect by CeO 2 was observed in the calcium doped samples. The T c and J c decrease by calcium doping are likely to be due to the calcium incorporation with the Y123 lattice and formation of coarse Y211 particles.

  18. The calculation of specific heats for some important solid components in hydrogen production process based on CuCl cycle

    Directory of Open Access Journals (Sweden)

    Avsec Jurij

    2014-01-01

    Full Text Available Hydrogen is one of the most promising energy sources of the future enabling direct production of power and heat in fuel cells, hydrogen engines or furnaces with hydrogen burners. One of the last remainder problems in hydrogen technology is how to produce a sufficient amount of cheap hydrogen. One of the best options is large scale thermochemical production of hydrogen in combination with nuclear power plant. copper-chlorine (CuCl cycle is the most promissible thermochemical cycle to produce cheap hydrogen.This paper focuses on a CuCl cycle, and the describes the models how to calculate thermodynamic properties. Unfortunately, for many components in CuCl cycle the thermochemical functions of state have never been measured. This is the reason that we have tried to calculate some very important thermophysical properties. This paper discusses the mathematical model for computing the thermodynamic properties for pure substances and their mixtures such as CuCl, HCl, Cu2OCl2 important in CuCl hydrogen production in their fluid and solid phase with an aid of statistical thermodynamics. For the solid phase, we have developed the mathematical model for the calculation of thermodynamic properties for polyatomic crystals. In this way, we have used Debye functions and Einstein function for acoustical modes and optical modes of vibrations to take into account vibration of atoms. The influence of intermolecular energy we have solved on the basis of Murnaghan equation of state and statistical thermodynamics.

  19. Comparison in processing routes by copper mold casting injection and suction in the Cu46Zr42Al7Y5 vitreous alloy

    International Nuclear Information System (INIS)

    Batalha, W.; Aliaga, L.C.R.; Bolfarini, C.; Botta, W.J.; Kiminami, C.S.

    2014-01-01

    To expand the application of glassy metals, the development of processing routes and compositions that allow the production of parts with dimensions of millimeters or even centimeters, is very important. The present work aims the contribution to the technological development of processing routes for the production of Cu-based bulk metallic glasses. Wedge-shaped samples of Cu 46 Zr 42 Al 7 Y 5 (atom percent) chemical composition were processed using copper mold casting by suction and injection. Characterization was made combining scanning electron microscopy, x-ray diffraction and differential scanning calorimetry. The critical amorphous thickness obtained by those two different routes was carefully observed. The suction route allow obtaining the best results with critical amorphous thickness about 8 mm. This result was analyzed considering the different extrinsic parameters to the glass forming ability of the alloy. (author)

  20. Surface Oxidation of the High-Strength Steels Electrodeposited with Cu or Fe and the Resultant Defect Formation in Their Coating during the Following Galvanizing and Galvannealing Processes

    Science.gov (United States)

    Choi, Yun-Il; Beom, Won-Jin; Park, Chan-Jin; Paik, Doojin; Hong, Moon-Hi

    2010-12-01

    This study examined the surface oxidation of high-strength steels electrodeposited with Cu or Fe and the resultant defect formation in their coating during the following galvanizing and galvannealing processes. The high-strength steels were coated with an Cu or Fe layer by the electroplating method. Then, the coated steels were annealed in a reducing atmosphere, dipped in a molten zinc, and finally transformed into galvannealed steels through the galvannealing process. The formation of Si and Mn oxides on the surface of the high-strength steel was effectively suppressed, and the density of surface defects on the galvanized steel was significantly reduced by the pre-electrodeposition of Cu and Fe. This effect was more prominent for the steels electrodeposited at higher cathodic current densities. The finer electrodeposit layer formed at higher cathodic current density on the steels enabled the suppression of partial surface oxidation by Mn or Si and better wetting of Zn on the surface of the steels in the following galvanizing process. Furthermore, the pre-electrodeposited steels exhibited a smoother surface without surface cracks after the galvannealing process compared with the untreated steel. The diffusion of Fe and Zn in the Zn coating layer in the pre-electrodeposited steels appears to occur more uniformly during the galvannealing process due to the low density of surface defects induced by oxides.

  1. The mechanism of degradation of bisphenol A using the magnetically separable CuFe{sub 2}O{sub 4}/peroxymonosulfate heterogeneous oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yin; Ai, Jia [Department of Environmental Engineering, Wuhan University, Wuhan 430079 (China); Shenzhen Research Institute of Wuhan University, Shenzhen 518057 (China); Zhang, Hui, E-mail: eeng@whu.edu.cn [Department of Environmental Engineering, Wuhan University, Wuhan 430079 (China); Shenzhen Research Institute of Wuhan University, Shenzhen 518057 (China)

    2016-05-15

    Highlights: • Copper ferrite (CuFe{sub 2}O{sub 4}) was fabricated and utilized in heterogeneous PMS process. • The influence of reaction parameters for the mineralization of BPA were evaluated. • Possible reaction mechanism and the stability of CuFe{sub 2}O{sub 4} were investigated. • Surface bound radicals (mainly ·OH) may be responsible for the BPA degradation. - Abstract: The removal of bisphenol A (BPA) in aqueous solution by an oxidation process involving peroxymonosulfate (PMS) activated by CuFe{sub 2}O{sub 4} magnetic nanoparticles (MNPs) is reported herein. The effects of PMS concentration, CuFe{sub 2}O{sub 4} dosage, initial pH, initial BPA concentration, catalyst addition mode, and anions (Cl{sup −}, F{sup −}, ClO{sub 4}{sup −} and H{sub 2}PO{sub 4}{sup −}) on BPA degradation were investigated. Results indicate that nearly complete removal of BPA (50 mg/L) within 60 min and 84.0% TOC removal in 120 min could be achieved at neutral pH by using 0.6 g/L CuFe{sub 2}O{sub 4} MNPs and 0.3 g/L PMS. The generation of reactive radicals (mainly hydroxyl radicals) was confirmed using electron paramagnetic resonance (EPR). Possible mechanisms on the radical generation from CuFe{sub 2}O{sub 4}/PMS system are proposed based on the results of radical identification tests and XPS analysis. The lack of inhibition of the reaction by free radical scavengers such as methanol and tert-butyl alcohol suggests that these species may not be generated in the bulk solution, and methylene blue probe experiments confirm that this process does not involve free radical generation. Surface-bound, rather than free radicals generated by a surface catalyzed-redox cycle involving both Fe(III) and Cu(II), are postulated to be responsible for the mineralization of bisphenol A.

  2. Temperature dependence of the mechanical properties of melt-processed Dy-Ba-Cu-O bulk superconductors evaluated by three point bending tests

    International Nuclear Information System (INIS)

    Katagiri, K; Nyilas, A; Sato, T; Hatakeyama, Y; Hokari, T; Teshima, H; Iwamoto, A; Mito, T

    2006-01-01

    Dy-Ba-Cu-O bulk superconductor has an excellent capability of trapping magnetic flux and lower heat conductivity at cryogenic temperatures as compared with Y-Ba-Cu-O bulk superconductor. The Young's modulus and the bending strength in the range from room temperature to 7 K were measured by the three-point bending tests using specimens cut from a melt-processed Dy-Ba-Cu-O bulk superconductor. They were tested in a helium gas flow type cryostat at Forschungszentrum Karlsruhe and in a liquid nitrogen bath at Iwate University. The Young's modulus was calculated by either the slope of stress-strain curve or that of the load-deflection curve of the specimen. Although the bending strength measured in the two institutes coincided well, there was a significant discrepancy in the Young's modulus. The Young's modulus and bending strength increased with decrease of temperature down to 7 K. The amount of increase in the Young's modulus and the bending strength were about 32% and 36% of those at room temperature, respectively. The scatter of data for each run was significant and did not depend on temperature. The temperature dependence of the Young's modulus coincided with that in Y-Ba-Cu-O obtained by ultrasonic velocity. The temperature dependence of the Young's modulus and the bending strength was discussed from the view point of interatomic distance of the bulk crystal

  3. Aluminum doping of CuInSe{sub 2} synthesized by solution process and its effect on structure, morphology, and bandgap tuning

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Zhi; Deng, Weizhi; Zhang, Xia; Yuan, Qian; Deng, Peiran; Sun, Lei [Material Engineering College, Shanghai University of Engineering Science (China); Liang, Jun [School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen University Town (China)

    2014-11-15

    Al-doped CuInSe{sub 2} material is prepared by a low-cost wet chemical process. The key properties of Al-doped CuInSe{sub 2} as a successful solar cell material are investigated, such as crystal structure, morphology, optical properties, and bandgap. In situ X-ray diffraction measurements indicate that the doping of Al has induced noticeable lattice distortion. The material shows excellent thermal stability up to 600 C annealing temperature. By increasing the Al-doping concentration, the crystal unit-cell parameter of the material becomes smaller and the change of crystal structure leads to an increase of the grain size and surface roughness. The bandgap of Al-doped CuInSe{sub 2} can be continuously tuned in a range of 1.07-1.67 eV as Al/(Al + In) content ratio varies from 0 to 0.49. Finally, the effect mechanism on the properties of CuInSe{sub 2} after Al doping is discussed based on the ionic radius, crystal structure, and bonding state. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Fabrication and characterization of Bi2Sr2CaCu2O8+δ stacks by self-planarizing process

    International Nuclear Information System (INIS)

    Okanoue, K.; Ishida, H.; Funabiki, H.; Hamasaki, K.; Shimakage, N.; Kawakami, A.; Wang, Z.; Abe, H.

    2005-01-01

    We developed a new fabrication process of stacked intrinsic Josephson junctions using superconducting Bi 2 Sr 2 CaCu 2 O 8+δ (Bi-2212) single crystals. In the proposed self-planarizing process, the Bi-2212 crystal around the junction window was modified to insulator by soaking into the solution of dilute (0.05-0.2%) hydrochloric acid for 5 s. Energy dispersive X-ray (EDX) spectroscopy revealed that the acid-treated Bi-2212 exhibited the decrease of Cu and Sr contents in the crystals. The current-voltage characteristic of the stacks showed distinct resistive branches with large hysteresis at 77 K. The number of intrinsic junctions in the stacks linearly decreased with decreasing the concentration of the solution. The well controllability of the number of junctions in the self-planarized stacks may be useful for electronic device applications

  5. Colloidal Precursors from 'Ball-Milling in Liquid Medium' Process for CuInSe2 Thin Film

    International Nuclear Information System (INIS)

    Chung, Jae Hoon; Kim, Seung Joo

    2010-01-01

    CIS thin film can be fabricated by using the precursor obtained through ball-milling the elemental reagents in liquid media. The amorphous colloidal precursor with good dispersity was prepared in the medium that contains strong base and polar solvent (2 M ethylenediamine in DMF solution as used in this study). The 'ball-milling in liquid medium' method requires only elemental sources as starting materials and a proper solution so that it can be employed without additional processes for separation and purification. As a simple and less-toxic preparative route, this method would be practically available to prepare CIS-related solar cells. CuInSe 2 (CIS) and related chalcopyrite compounds are very promising materials for thin film solar cells due to their favorable band gap, high optical absorption coefficient and long-term stability. CIS-based solar cells have shown the highest conversion efficiency reaching a value of 20%. However, the vacuum-based processes that are used to fabricate CIS thin-films have some drawbacks such as the complexity in process, high production cost and difficulty in scaling up. Recently, several research groups have proposed different non-vacuum deposition processes for CIS solar cell. For example, H. W. Hillhouse et al. prepared the CIS absorber layer by using 'nanocrystal ink method' in which a colloidal nanocrystal ink was obtained from reaction of CuCl, InCl 3 and Se in oleylamine. D. B. Mitzi et al. used a solution-based precursor that was prepared by dissolution of Cu 2 Se, In 2 Se 3 , Ga 2 Se 3 and Se in hydrazine to fabricate the Ga-containing absorber layer, Cu(In,Ga)Se 2

  6. An Efficient and Practical Process for Pd/Cu Cocatalyzed Homocoupling Reaction of Terminal Alkynes Using Sodium Percarbonate as a Dual Reagent in Aqueous Media

    Institute of Scientific and Technical Information of China (English)

    ZHOU, Lei; ZHAN, Hai-Ying; LIU, Hai-Ling; JIANG, Huan-Feng

    2007-01-01

    A new process for the Pd/Cu co-catalyzed homocoupling reaction of terminal alkynes was developed. The reaction was carried out in aqueous media with sodium percarbonate as both a clean oxidant and a base. Meanwhile, a palladium complex immobilized on a synthetic PS-PEG400-PPh2 resin was used as the catalyst, which may be recovered by simple filtration and reused for several times with high activity.

  7. Consolidation of powders of the superconductor YBa/sub 2/Cu/sub 3/O/sub 7-. delta. / by high energy-high rate processing

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.Y.; Persad, C.; Swinnea, J.S.; Marcus, H.L.; Steinfink, H. (Texas Univ., Austin, TX (USA). Center for Materials Science and Engineering)

    1988-01-01

    The consolidation response of powders of the superconducting compound YBa/sub 2/Cu/sub 3/O/sub 7-{delta}/ by itself and admixed with metal powders is reported. The processing approach relies on short duration (

  8. The role of external and internal mass transfer in the process of Cu2+ removal by natural mineral sorbents.

    Science.gov (United States)

    Sljivić, M; Smiciklas, I; Plećas, I; Pejanović, S

    2011-07-01

    The kinetics of Cu2+ sorption on to zeolite, clay and diatomite was investigated as a function of initial metal concentrations. For consideration of the mass transfer phenomena, single resistance models based on both film and intraparticle diffusion were tested and compared. The obtained results suggested that the rate-limiting step in Cu2+ sorption strongly depended on the sorbent type, as well as on initial cation concentration. The decrease in external mass transfer coefficients with the increase in initial metal concentrations was in excellent agreement with expressions based on Sherwood and Schmidt dimensionless numbers. The internal diffusivities through zeolite particles were in the range 1.0 x 10(-11) to 1.0 x 10(-13) m2/min, depending on the Cu2+ concentration and the applied theoretical model.

  9. Solid state reactions and diffusion processes during rapid thermal processing of Cu-In-S based semiconductors; Festkoerperreaktionen und Diffusionsprozesse bei der schnellen Bildung von Halbleiterschichten im System Cu-In-S

    Energy Technology Data Exchange (ETDEWEB)

    Enzenhofer, T

    2007-12-14

    In this thesis thin layers of the system Cu-In-S were studied for the photovoltaic application by means of structural and electro-optical procedures. The effect of small quantities of group II elements on the absorber and component properties could be explained by a widely appointed study. The motivation to insert extraneous elements into CuInS{sub 2} absorber layers results from the too low zero-current voltage of CuInS{sub 2} based solar cells. It could be shown that by addition of small quantities of Zn and/or Mg (<1 at.%) the zero-current voltage can be increased by 90 mV. The best doped CuInS{sub 2} solar cells aimed efficiencies, which were also determined for the reference system. As limiting factor in the doped system the zero-current has been proved. The intensive analysis of the absorber properties showed the the extraneous atoms effect in the bulk and on the surface different modifications.

  10. Processing of single- and multi-domain YBa2Cu3Ox bulk materials for levitation applications by Nd1+xBa2-xCu3Oy seeding

    International Nuclear Information System (INIS)

    Todt, V.R.

    1995-01-01

    Melt processing of YBa 2 Cu 3 O x (Y123) is a well established technique to produce materials for levitation applications. We report our new results on the melt-processing of Y123. To achieve materials with high levitation forces we utilize a seeding technique using Nd 1+x Ba 2-x Cu 3 O y- seeds (Nd123). Two different kinds of Nd13-seeds, one plate-shaped and the other cube-shaped, were developed and used for this study. The microstructures of the levitators depended strongly on the type of the seeding material used and on the seeding geometry. We were able to produce large single domains as well as materials containing five domains with three different c-axis orientations. Levitation forces up to 8.2 N for samples with a diameter of about 18 mm were found for the multi-domain samples, which is well within the area of the levitation forces measured for the single domain materials

  11. Growth and process identification of CuInS 2 on GaP by chemical vapor deposition

    Science.gov (United States)

    Hwang, H. L.; Sun, C. Y.; Fang, C. S.; Chang, S. D.; Cheng, C. H.; Yang, M. H.; Lin, H. H.; Tuwan-Mu, H.

    1981-10-01

    Experimental techniques for growing CuInS 2 layers on GaP substrates by the metalorganic method have been developed. Hydrogen sulfide gas together with the vapors of CuCl( NCCH3) n and InCl3( NCCH3) both of which were generated by bubbling nitrogen through sources, using a solvent of acetonitride, were used as transport agents. Various characterization techniques such as atomic absorption (AA), neutron activation analysis (NAA), energy dispersive analysis by X-rays (EDAX), Rutherford back-scattering analysis (RBS), and X-ray analyses were used to help understand the fundamental mechanism of the CVD growth.

  12. Surface-reconstructed Cu Electrode via a Facile Electrochemical Anodization-Reduction Process for Low Overpotential CO 2 reduction

    KAUST Repository

    Min, Shixiong

    2017-03-21

    A high-surface-area Cu electrode, fabricated by a simple electrochemical anodization-reduction method, exhibits high activity and selectivity for CO2 reduction at low overpotential in 0.1 M KHCO3 solution. A faradaic efficiency of 37% for HCOOH and 27% for CO production was achieved with the current density of 1.5 mA cm-2 at −0.64 V vs. RHE, much higher than that of polycrystalline Cu. The enhanced catalytic performance is a result of the formation of the high electrochemical active surface area and high density of preferred low-index facets.

  13. Layer growth and electronic defect properties of CuInS{sub 2} absorber layers from the sequence process; Schichtwachstum und elektronische Defekteigenschaften von CuInS{sub 2}-Absorberschichten aus dem sequentiellen Prozess

    Energy Technology Data Exchange (ETDEWEB)

    Siemer, K.

    2000-10-01

    The following topics were covered: synthesis of CuInS{sub 2} solar cells, layer growth of CuInS{sub 2} absorbers, electrical characterization, C-V and DLTS spectroscopy, defect spectroscopy of CuInS{sub 2} solar cells.

  14. In situ TEM observation of stress-induced martensitictransformations and twinning processes in CuAlNi single crystals

    Czech Academy of Sciences Publication Activity Database

    Zárubová, Niva; Gemperlová, Juliana; Gemperle, Antonín; Dlabáček, Zdeněk; Šittner, Petr; Novák, Václav

    2010-01-01

    Roč. 58, č. 15 (2010), s. 5109-5119 ISSN 1359-6454 R&D Projects: GA AV ČR(CZ) IAA200100627 Institutional research plan: CEZ:AV0Z10100520 Keywords : CuAlNi shape memory alloy * martensitic transformation * in situ TEM straining Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.781, year: 2010

  15. Surface-reconstructed Cu Electrode via a Facile Electrochemical Anodization-Reduction Process for Low Overpotential CO 2 reduction

    KAUST Repository

    Min, Shixiong; Yang, Xiulin; Lu, Ang-Yu; Tseng, Chien-Chih; Hedhili, Mohamed N.; Lai, Zhiping; Li, Lain-Jong; Huang, Kuo-Wei

    2017-01-01

    A high-surface-area Cu electrode, fabricated by a simple electrochemical anodization-reduction method, exhibits high activity and selectivity for CO2 reduction at low overpotential in 0.1 M KHCO3 solution. A faradaic efficiency of 37% for HCOOH

  16. OMS-2-Supported Cu Hydroxide-Catalyzed Benzoxazoles Synthesis from Catechols and Amines via Domino Oxidation Process at Room Temperature.

    Science.gov (United States)

    Meng, Xu; Wang, Yanmin; Wang, Yuanguang; Chen, Baohua; Jing, Zhenqiang; Chen, Gexin; Zhao, Peiqing

    2017-07-07

    In the presence of manganese oxide octahedral molecular sieve (OMS-2) supported copper hydroxide Cu(OH) x /OMS-2, aerobic synthesis of benzoxazoles from catechols and amines via domino oxidation/cyclization at room temperature is achieved. This heterogeneous benzoxazoles synthesis initiated by the efficient oxidation of catechols over Cu(OH) x /OMS-2 tolerates a variety of substrates, especially amines containing sensitive groups (hydroxyl, cyano, amino, vinyl, ethynyl, ester, and even acetyl groups) and heterocycles, which affords functionalized benzoxazoles in good to excellent yields by employing low catalyst loading (2 mol % Cu). The characterization and plausible catalytic mechanism of Cu(OH) x /OMS-2 are described. The notable features of our catalytic protocol such as the use of air as the benign oxidant and EtOH as the solvent, mild conditions, ease of product separation, being scalable up to the gram level, and superior reusability of catalyst (up to 10 cycles) make it more practical and environmentally friendly for organic synthesis.

  17. Twinning processes in Cu-Al-Ni martensite single crystals investigated by neutron single crystal diffraction method

    Czech Academy of Sciences Publication Activity Database

    Molnar, P.; Šittner, P.; Novák, V.; Lukáš, Petr

    2008-01-01

    Roč. 481, Sp.Iss.SI (2008), s. 513-517 ISSN 0921-5093 R&D Projects: GA AV ČR IAA100480704 Institutional research plan: CEZ:AV0Z10480505 Keywords : Cu-Al-Ni * single crystals * neutron diffraction Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.806, year: 2008

  18. A comparative study on Cu, Cr and As removal from CCA-treated wood waste by dialytic and electrodialytic processes

    DEFF Research Database (Denmark)

    Velizarova, Emiliya; Ribeiro, Alexandra B.; Ottosen, Lisbeth M.

    2002-01-01

    In this study, electrodialytic and dialytic techniques were used for Cu, Cr and As removal from 20-years out-of-service CCA-treated Pinus pinaster Ait. pole. The effect of applying direct current, as "cleaning agent", of up to 120mA was investigated. Focus was given to a parallel comparison...

  19. Consolidation of powders of the oxide superconductor YBa/sub 2/Cu/sub 3/Ox by high energy-high rate processing

    Energy Technology Data Exchange (ETDEWEB)

    Persad, C.; Lee, S.J.; Peterson, D.R.; Swinnea, J.S.; Schmerling, M.

    1988-01-01

    The consolidation response of powders of the superconducting compound YBa/sub 2/Cu/sub 3/Ox is reported. Copper, silver, tin, and Cu-based metallic glass infiltrates have also been employed in preliminary fabricability studies. The processing approach relies on short-duration (< 1s), high-current-density 10000 A/sq.cm, pulse-resistive heating of powders under applied pressures of 200 MPa to 400 MPa. Powders and fabricated disk compacts were characterized by X-ray diffraction, optical and scanning electron microscopy, and resistivity measurements. X-ray diffraction comparisons of starting powder and consolidated material show retention of the single phase 1-2-3 structure and the development of a preferred orientation. In the consolidated pure YBa/sub 2/Cu/sub 3/0x, Tc onsets of 87K were accompanied by broad transitions. Iodometric analyses indicated oxygen depletion in the as-consolidated disks. Observed oxygen-content profiles across the sample thickness had values 0.11< x <0.35. The variation in the peak processing temperature within the disk was found to correlate with the oxygen content profile.

  20. Convenient hydrothermal decomposition process for preparation of nanocrystalline mineral Cu3BiS3 and Pb1-xBi2x/3S

    International Nuclear Information System (INIS)

    Hu Junqing; Deng Bin; Wang Chunrui; Tang Kaibin; Qian Yitai

    2003-01-01

    Mineral nanocrystalline Cu 3 BiS 3 and Pb 1-x Bi 2x/3 S (or Bi 0.22 Pb 0.89 S 1.22 ) have been prepared at low synthetic temperature of 100-150 deg. C by convenient hydrothermal decomposition process. X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectra, and element analysis were used to characterize and measure the samples. The as-prepared Cu 3 BiS 3 sample consisted of whisker-like particles with an average size of 50x10 nm 2 and the Pb 1-x Bi 2x/3 S sample displayed aggregative particles with size in the range of 30-50 nm. Preliminary results showed that the prepared precursors, reaction temperature and time played a role in the formation of the final products. A possible reaction mechanism was also discussed briefly

  1. The effects of microalloying with Cd on precipitation processes in Al-1.7 Cu-0.3 mg (At. %) alloys

    International Nuclear Information System (INIS)

    Sofyan, Bondan T.

    2002-01-01

    The present work investigates the effects of microalloying with Cd on precipitation processes in Al-1.7 Cu-0.3 mg (At. %) alloys. Analytical STEM (Scanning Transmission Electron Microscope) revealed the presence of clusters rich in Cd and Mg at early stages of ageing, which is believed to be responsible in promoting the nucleation of θ (Al,Cu) in the alloy on its (001) planes. The Cd-Mg clusters then grow as Cd-Mg-rich particles when ageing is continued beyond the peak hardness. The presence of Cd-Mg-rich clusters is thought to play an important role on the nucleation of θ phase by accommodating the misfit strain on the non-coherent rim of the phase. The accommodation of misfit strain is made available by the presence of large amount of vacancies, which is trapped by Cd and Mg atoms during quenching, around θ platelet nuclei

  2. 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.)

  3. 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.

  4. 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.)

  5. FTIR study of formic acid interaction with TiO2 and TiO2 doped with Pd and Cu in photocatalytic processes

    International Nuclear Information System (INIS)

    Arana, J.; Garriga i Cabo, C.; Dona-Rodriguez, J.M.; Gonzalez-Diaz, O.; Herrera-Melian, J.A.; Perez-Pena, J.

    2004-01-01

    In this study the different processes occurring on the TiO 2 and Pd and Cu doped TiO 2 surfaces during the photocatalytic formic acid degradation in the presence or absence of S 2 O 8 2- or H 2 O 2 have been investigated. FTIR studies have shown the relevance of the H-bounded hydroxyl groups. It has been observed that formate molecules interact simultaneously with the dopants and surfacial Ti atoms yielding an intermediate species which plays an important role in the phototacatalytic degradation mechanism. Also, it has been determined that Pd or Cu oxides may act as receptors or transmitters of the TiO 2 photogenerated electrons and thus modify the degradation mechanism. Different redox reactions have been proposed according to the obtained results

  6. Rapid formation of the 110 K phase in Bi-Pb-Sr-Ca-Cu-O through freeze-drying powder processing

    International Nuclear Information System (INIS)

    Song, K.H.; Liu, H.K.; Dou, S.X.; Sorrell, C.C.

    1990-01-01

    This paper reports three techniques for processing Bi-Pb-Sr-Ca-Cu-O (BPSCCO) powders investigated: dry-mixing, sol-gel formation, and freeze-drying. It was found that sintering for 120 h at 850 degrees C is required to form nearly single-phase (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10-y by dry-mixing, whereas sintering for 30 h at 840 degrees C was sufficient to form the 110 K (2223) phase when freeze-drying was used. The sol-gel route was found to be intermediate in efficiency between these two techniques. Freeze-drying provided highly reactive, intimately mixed, and carbon-free precursors. The presence of carbonates in the uncalcined powders was the major cause of phase segregation and sluggishness of the 110 K phase formation

  7. Analysis of process parameters in the laser deposition of YBa{sub 2}Cu{sub 3}O{sub 7} superconducting films by using SVR

    Energy Technology Data Exchange (ETDEWEB)

    Cai, C.Z., E-mail: caiczh@gmail.com [Department of Applied Physics, Chongqing University, Chongqing 401331 (China); Xiao, T.T. [Department of Applied Physics, Chongqing University, Chongqing 401331 (China); Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, CAEP, P.O. Box 919-988, Mianyang 621900 (China); Tang, J.L.; Huang, S.J. [Department of Applied Physics, Chongqing University, Chongqing 401331 (China)

    2013-10-15

    Highlights: • Proposed new ideas and strategies to improve energy storage density for SMES system. • One is to increase the effective current density in the superconducting coils. • Another is to optimize the configuration of the SMES coil. • A new conceive of energy compression is also proposed. -- Abstract: There are several process parameters in the growth of YBa{sub 2}Cu{sub 3}O{sub 7} superconducting films by using pulsed laser deposition (PLD). The relationship between the response and process parameters is highly nonlinear and quite complicated. It is very valuable to quantitatively estimate the response under different deposition parameters. In this study, according to an experimental data set on the superconducting transition temperature (T{sub c}) and relative resistance ratio (r{sub R}) of 17 samples of YBa{sub 2}Cu{sub 3}O{sub 7} films deposited under various parameters, the support vector regression (SVR) combined with particle swarm optimization (PSO), was proposed to predict the T{sub c} and r{sub R} for YBa{sub 2}Cu{sub 3}O{sub 7} films. The prediction performance of SVR was compared with that of multiple regression analysis (MRA) models. The results strongly support that the generalization ability of SVR model consistently surpasses that of MRA via leave-one-out cross validation (LOOCV). The mean absolute percentage errors for T{sub c} and r{sub R} are 0.37% and 1.51% respectively via LOOCV test of SVR. Sensitivity analysis discovered the most sensitive parameters affecting the T{sub c} and r{sub R}. This study suggests that the established SVR model can be used to accurately foresee the T{sub c} and r{sub R}. And it can be used to optimizing the deposition parameters in the development of YBa{sub 2}Cu{sub 3}O{sub 7} films via PLD.

  8. Low-temperature synthesis of CuFeO{sub 2} (delafossite) at 70 °C: A new process solely by precipitation and ageing

    Energy Technology Data Exchange (ETDEWEB)

    John, Melanie, E-mail: melanie.john@min.uni-muenchen.de [Section Mineralogy, Petrology & Geochemistry, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Heuss-Aßbichler, Soraya [Section Mineralogy, Petrology & Geochemistry, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Park, So-Hyun [Section Crystallography, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Ullrich, Aladin [Experimental Physics II, University of Augsburg, Universitätsstr. 1, 86159 Augsburg (Germany); Benka, Georg [Physics Department, Technical University Munich, James-Franck-Straße 1, 85748 Garching (Germany); Petersen, Nikolai [Section Geophysics, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Rettenwander, Daniel [Department of Materials Research & Physics, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Horn, Siegfried R. [Experimental Physics II, University of Augsburg, Universitätsstr. 1, 86159 Augsburg (Germany)

    2016-01-15

    This study presents a new low temperature synthesis method to obtain pure delafossite (Cu{sup 1+}Fe{sup 3+}O{sub 2}) at a temperature of 70 °C within 24 h. For the first time delafossite is synthesized solely by precipitation and subsequent ageing process and without usage of any additives controlling the oxidation state of copper. The synthesized material, called LT-delafossite, consists of pure Cu{sup 1+}Fe{sup 3+}O{sub 2} exclusive of any side products. Rietveld analysis confirms the presence of both 3R (space group (SG): R-3m) and 2H (SG: P6{sub 3}/mmc) polytypes in LT-delafossite. Electron microscopy images show nanometer-sized hexagonal plates with a diameter <500 nm and a thickness of <30 nm. Measurements of the magnetic susceptibility from 2 K to 350 K in zero-field show one peak ∼18.5 K, which is attributed to an AFM phase transition. Zero-field-cooled magnetization data between −14 T and +14 T at 2 K revealed an s-shape form around the origin having no remanent magnetization. - Highlights: • New process: low temperature synthesis of pure CuFeO{sub 2} nanoparticles. • Synthesis at 70 °C within 24 h solely by precipitation and ageing. • Nanoparticle characterization by XRD, FTIR, SEM, ICP–OES, TEM and Mößbauer. • Special magnetic properties of nano-sized CuFeO{sub 2} synthesized at low temperatures.

  9. In-situ optical emission spectroscopy for a better control of hybrid sputtering/evaporation process for the deposition of Cu(In,Ga)Se{sub 2} layers

    Energy Technology Data Exchange (ETDEWEB)

    Posada, Jorge; Jubault, Marie [Institute of Research and Development on Photovoltaic Energy (IRDEP), EDF-CNRS-Chimie ParisTech, UMR 7174, 6 Quai Watier, 78401 Chatou (France); Bousquet, Angélique; Tomasella, Eric [Clermont Université, Université Blaise Pascal, Institute of Chemistry of Clermont-Ferrand (ICCF), CNRS-UMR 6296, 24 Avenue des Landais, 63171 Aubière (France); Lincot, Daniel [Institute of Research and Development on Photovoltaic Energy (IRDEP), EDF-CNRS-Chimie ParisTech, UMR 7174, 6 Quai Watier, 78401 Chatou (France)

    2015-05-01

    In this work, we have developed a hybrid one-step co-sputtering/evaporation Cu(In,Ga)Se{sub 2} (CIGS) process, where Cu, In and Ga are sputtered simultaneously with the thermal evaporation of selenium, thus avoiding the H{sub 2}Se use. An appropriate control of the selenium flux is very important to prevent the target poisoning and hence some material flux variations. Indeed, the control of the CIGS composition must be rigorous to ensure reproducible solar cell properties. In this regard, a study of the correlations between plasma species and thin film composition, structure and morphology has been performed by varying power values and Se evaporation temperature in the 170 to 230 °C range. We started by studying the plasma with a powerful technique: optical emission spectroscopy, following light emissions from different plasma species: sputtered Cu, Ga, In but also evaporated Se. Hence, we determined the Se flow threshold avoiding target poisoning and the main parameter controlling the CIGS composition. Obviously, we also focused our interest on the material. We measured film composition and thickness of the samples with X-ray fluorescence and by energy dispersive X-ray. Different phases formed during the process were identified by Raman spectroscopy and X-ray diffraction. The optoelectronic cell properties showed promising efficiency of 10.3% for an absorber with composition ratios of [Cu]/([In] + [Ga]) = 1.02 and [Ga]/([In] + [Ga]) = 0.44. Finally, this work shows that we are able to control this hybrid process and thus the structure and composition of CIGS thin film for industrial transfer in the photovoltaic field. - Highlights: • We have developed a hybrid one-step co-sputtering/evaporation Cu(In,Ga)Se{sub 2} process. • Correlations between plasma species and thin film composition have been performed. • We determined the Se flow threshold avoiding target poisoning. • Efficient small-area CIGS cells with 10.3% efficiency were fabricated.

  10. Optimization of the Hot Forging Processing Parameters for Powder Metallurgy Fe-Cu-C Connecting Rods Based on Finite Element Simulation

    Science.gov (United States)

    Li, Fengxian; Yi, Jianhong; Eckert, Jürgen

    2017-12-01

    Powder forged connecting rods have the problem of non-uniform density distributions because of their complex geometric shape. The densification behaviors of powder metallurgy (PM) connecting rod preforms during hot forging processes play a significant role in optimizing the connecting rod quality. The deformation behaviors of a connecting rod preform, a Fe-3Cu-0.5C (wt pct) alloy compacted and sintered by the powder metallurgy route (PM Fe-Cu-C), were investigated using the finite element method, while damage and friction behaviors of the material were considered in the complicated forging process. The calculated results agree well with the experimental results. The relationship between the processing parameters of hot forging and the relative density of the connecting rod was revealed. The results showed that the relative density of the hot forged connecting rod at the central shank changed significantly compared with the relative density at the big end and at the small end. Moreover, the relative density of the connecting rod was sensitive to the processing parameters such as the forging velocity and the initial density of the preform. The optimum forging processing parameters were determined and presented by using an orthogonal design method. This work suggests that the processing parameters can be optimized to prepare a connecting rod with uniform density distribution and can help to better meet the requirements of the connecting rod industry.

  11. Copper(I) Thiocyanate (CuSCN) Hole-Transport Layers Processed from Aqueous Precursor Solutions and Their Application in Thin-Film Transistors and Highly Efficient Organic and Organometal Halide Perovskite Solar Cells

    KAUST Repository

    Wijeyasinghe, Nilushi

    2017-07-28

    This study reports the development of copper(I) thiocyanate (CuSCN) hole-transport layers (HTLs) processed from aqueous ammonia as a novel alternative to conventional n-alkyl sulfide solvents. Wide bandgap (3.4–3.9 eV) and ultrathin (3–5 nm) layers of CuSCN are formed when the aqueous CuSCN–ammine complex solution is spin-cast in air and annealed at 100 °C. X-ray photoelectron spectroscopy confirms the high compositional purity of the formed CuSCN layers, while the high-resolution valence band spectra agree with first-principles calculations. Study of the hole-transport properties using field-effect transistor measurements reveals that the aqueous-processed CuSCN layers exhibit a fivefold higher hole mobility than films processed from diethyl sulfide solutions with the maximum values approaching 0.1 cm2 V−1 s−1. A further interesting characteristic is the low surface roughness of the resulting CuSCN layers, which in the case of solar cells helps to planarize the indium tin oxide anode. Organic bulk heterojunction and planar organometal halide perovskite solar cells based on aqueous-processed CuSCN HTLs yield power conversion efficiency of 10.7% and 17.5%, respectively. Importantly, aqueous-processed CuSCN-based cells consistently outperform devices based on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate HTLs. This is the first report on CuSCN films and devices processed via an aqueous-based synthetic route that is compatible with high-throughput manufacturing and paves the way for further developments.

  12. Electroreflectance of CuInS{sub 2}-solar cells for the optimization of the process parameters during the absorbers production process; Elektroreflexion an CuInS{sub 2}-Solarzellen im Hinblick auf die Optimierung der Prozessparameter bei der Absorber-Herstellung

    Energy Technology Data Exchange (ETDEWEB)

    Henninger, R.

    2002-07-01

    CuInS{sub 2} thin film solar cells were prepared by a new sequential process. The quality of these layers and the conversion efficiency of the solar cells depends on the process parameters of the sequential process. Electroreflectance measurements are used to characterize these solar cells. This method is suitable to measure optical properties like band gap energy and to detect secondary phases in the vicinity of the heterojunction and defects in the semiconductor. Electroreflectance measurements of the thin film solar cells shows clearly a dependence of film growth from the process parameters copper to indium ratio and sulfurization temperature. From the correlation of electroreflectance results with photoluminescence, X-ray-diffraction and external quantum efficiency measurements a model of film growth was derived. Solar cells made from optimized CuInS{sub 2} films reach an active area efficiency of 12,5%. This is the best efficiency reported so far for this type of solar cell. (orig.) [German] Mit einem neuen sequentiellen Verfahren wurden CuInS{sub 2}-Duennfilme fuer die Solarzellen-Anwendung hergestellt. Die Qualitaet dieser Schichten und damit der Solarzellenwirkungsgrad haengen von den Prozessparametern des sequentiellen Prozesses ab. Elektroreflexion wurde als Messverfahren zur Charakterisierung der fertigen Solarzellen eingesetzt. Dieses Verfahren ist geeignet um optische Eigenschaften, wie die Bandlueckenenergie, zu bestimmen und Fremdphasen in der Naehe des pn-Ueberganges sowie Defekte im Halbleiter nachzuweisen. In Elektroreflexionsmessungen an den hergestellten Duennfilmsolarzellen zeigte sich deutlich eine Abhaengigkeit des Schichtwachstums von den Prozessparametern Kupfer-Indium-Verhaeltnis und Sulfurisierungstemperatur. Aus der Korrelation der Elektroreflexionsergebnisse mit Photolumineszenz-, Roentgenbeugungs- und Quantenausbeutemessungen wurde ein Modell zur Schichtbildung von CuInS{sub 2} abgeleitet. Solarzellen aus optimierten CuInS{sub 2

  13. Phase formation and reaction kinetics during the processing of the chalkopyrite-solar-cell-material Cu(In,Ga)(Se,S){sub 2}; Phasenbildung und Reaktionskinetik bei der Herstellung des Chalkopyrit-Solarzellenmaterials Cu(In,Ga)(Se,S){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Purwins, Michael

    2010-02-05

    The SEL/RTP-procedure (Stacked-Elemental-Layer/Rapid-Thermal-Process) is a method which is used to produce CuInSe{sub 2}-based absorbers/semiconductors for the application in thin film solar cells and modules, respectively. The SEL/RTP-procedure consists of two consecutive steps. During the first step a stack of several layers of the metals Cu, Ga and In as well as Se and/or S are deposited onto a substrate to form the so called precursor. By annealing the precursor, reaching temperatures of about 550 C, the stacked layers are converted into the compound semiconductor Cu(In{sub 1-x}Ga{sub x})(S{sub 1-y}Se{sub y}){sub 2} (CIGSSe). During the thermal process the central component of the later solar cell, the highly light absorbing, photoelectric active layer is formed. Thus, the second step is of great importance. This is not only because of the fact that the absorbers physical properties are established by the thermal process. Additionally the profitability of the whole manufacturing process is affected. To be able to optimize the SEL/RTP-procedure a deep and comprehensive understanding of the occurring phase formation processes and reaction kinetic mechanisms associated with them is necessary. This was the goal of the present thesis which therefore deals with the phase formation processes during the deposition of the precursor and its reaction kinetics during the following selenization and sulfurization process. Therefore the influence of different sputtering parameters on the formation of phases and the evolution of the precursor's morphology during its production by sputtering alternating stacked layers of Cu:Ga-alloys (i.e. Cu{sub 85}Ga{sub 15}, Cu{sub 75}Ga{sub 25} and CuGa{sub 2}) and/or the elements Cu and In was investigated. It was found that the deposition of Cu{sub 75/85}Ga{sub 25/15} onto In leads to the formation of CuIn{sub 2} and/or a metastable Cu(In,Ga)-alloy that is rich in copper. This deposition sequence is crucial for the precursor

  14. Correlation between processing conditions of Cu2ZnSn(SxSe1-x)4 and modulated surface photovoltage

    Science.gov (United States)

    Lin, X. Z.; Dittrich, Th.; Fengler, S.; Lux-Steiner, M. Ch.; Ennaoui, A.

    2013-04-01

    Cu2ZnSn(SxSe1-x)4 (CZTSSe) layers deposited from multi-component nanoparticle inks were characterized by modulated surface photovoltage (SPV) spectroscopy to investigate the effect of annealing conditions. The SPV signals increased strongly with decreasing sulfur content. Band gaps were obtained in terms of SPV onset energy. A diffusion length of above 1 μm was estimated for photo-generated electrons at x = 0.28. The band gap increased with increasing x showing an anomaly in the range of 0.5 < x < 1. The results suggested that an excess of selenium is required for the formation of a photo-active phase reliable for efficient Cu2ZnSn(SxSe1-x)4-based solar cells.

  15. Microstructure processes induced by phase transitions in a CuAu alloy as studied by acoustic emission and optical cinematography

    Energy Technology Data Exchange (ETDEWEB)

    Masek, P.; Chmelik, F.; Sima, V. [Charles Univ., Prague (Czech Republic). Dept. of Metal Physics; Brinck, A.; Neuhaeuser, H. [Technische Univ. Braunschweig (Germany). Inst. fuer Metallphysik und Nukleare Festkoerperphysik

    1999-01-15

    Combined acoustic emission measurements and surface cinematography observations have been applied to determine the structure evolution during thermal loading of the CuAu alloy. Thermal history and the fashion of thermal loading have been shown to affect considerably the structure response of the CuAu alloy on temperature changes. On thermal loading, intense plastic deformation occurs in certain temperature intervals due to the relaxation of internal stresses induced by phase transitions and structure anisotropy. The main mechanism is twinning taking place most probably in (110) planes. Dislocation glide and grain-boundary sliding have also been observed as minor mechanisms. A shape-restoration effect associated with the order-disorder transition is revealed. Thermal cycling with upper temperatures over 500 C may also result in structural damage.

  16. A magneto-optic technique for studying magnetization reversal processes and anisotropies applied to Co/Cu/Co trilayer structures

    Science.gov (United States)

    Daboo, C.; Bland, J. A. C.; Hicken, R. J.; Ives, A. J. R.; Baird, M. J.; Walker, M. J.

    1993-05-01

    We report the magnetization reversal and magnetic anisotropy behavior of ultrathin Co/Cu(111)/Co (dCu=20 and 27 Å) trilayer structures prepared by MBE on a 500-Å Ge/GaAs(110) epilayer. We describe an arrangement in which the magnetization components parallel and perpendicular to the applied field are both determined from longitudinal MOKE measurements. For the samples examined, coherent rotation of the magnetization vector is observed when the magnetic field is applied along the hard in-plane anisotropy axis, with the magnitude of the magnetization vector constant and close to its bulk value. Results of micromagnetic calculations closely reproduce the observed parallel and perpendicular magnetization loops, and yield strong uniaxial magnetic anisotropies in both layers while the interlayer coupling appears to be absent or negligible in comparison with the anisotropy strengths. An absence of antiferromagnetic (AF) coupling has been observed previously [W. F. Egelhoff, Jr. and M. T. Kief, Phys. Rev. B 45, 7795 (1992)] in contrast to recent results, indicating that AF coupling [M. T. Johnson et al., Phys. Rev. Lett. 69, 969 (1992)] and GMR [D. Grieg et al., J. Magn. Magn. Mater. 110, L239 (1992)] can occur in Co/Cu(111)/Co structures grown by MBE, but these properties are sensitively dependent on growth conditions. The absence of coupling in our samples is attributed to the presence of a significant interface roughness induced by the Ge epilayer. The uniaxial anisotropies are assumed to arise from strain or defects induced in the film.

  17. Effect of preparation conditions on the properties of Cu3BiS3 thin films grown by a two - step process

    Science.gov (United States)

    Mesa, F.; Gordillo, G.

    2009-05-01

    Cu3BiS3 thin films were prepared on soda-lime glass substrates by co-evaporation of the precursors in a two-step process; for that, the metallic precursors were evaporated from a tungsten boat in presence of elemental sulfur evaporated from a tantalum effusion cell. The films were characterized by spectral transmittance, atomic force microscopy AFM and x-ray diffraction (XRD) measurements to investigate the effect of the growth conditions on the optical, morphological and structural properties. The results revealed that, independently of the deposition conditions, the films grow only in the orthorhombic Cu3BiS3 phase. It was also found that the Cu3BiS3 films present p-type conductivity, a high absorption coefficient (greater than 104 cm-1) and an energy band gap Eg of about 1.41 eV, indicating that this compound has good properties to perform as absorbent layer in thin film solar cells.

  18. High-performance inverted planar heterojunction perovskite solar cells based on a solution-processed CuOx hole transport layer.

    Science.gov (United States)

    Sun, Weihai; Li, Yunlong; Ye, Senyun; Rao, Haixia; Yan, Weibo; Peng, Haitao; Li, Yu; Liu, Zhiwei; Wang, Shufeng; Chen, Zhijian; Xiao, Lixin; Bian, Zuqiang; Huang, Chunhui

    2016-05-19

    During the past several years, methylammonium lead halide perovskites have been widely investigated as light absorbers for thin-film photovoltaic cells. Among the various device architectures, the inverted planar heterojunction perovskite solar cells have attracted special attention for their relatively simple fabrication and high efficiencies. Although promising efficiencies have been obtained in the inverted planar geometry based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) sulfonic acid ( PSS) as the hole transport material (HTM), the hydrophilicity of the PSS is a critical factor for long-term stability. In this paper, a CuOx hole transport layer from a facile solution-processed method was introduced into the inverted planar heterojunction perovskite solar cells. After the optimization of the devices, a champion PCE of 17.1% was obtained with an open circuit voltage (Voc) of 0.99 V, a short-circuit current (Jsc) of 23.2 mA cm(-2) and a fill factor (FF) of 74.4%. Furthermore, the unencapsulated device cooperating with the CuOx film exhibited superior performance in the stability test, compared to the device involving the PSS layer, indicating that CuOx could be a promising HTM for replacing PSS in inverted planar heterojunction perovskite solar cells.

  19. Effects of Heat Treatment on the Microstructures and High Temperature Mechanical Properties of Hypereutectic Al-14Si-Cu-Mg Alloy Manufactured by Liquid Phase Sintering Process

    Science.gov (United States)

    Heo, Joon-Young; Gwon, Jin-Han; Park, Jong-Kwan; Lee, Kee-Ahn

    2018-05-01

    Hypereutectic Al-Si alloy is an aluminum alloy containing at least 12.6 wt.% Si. It is necessary to evenly control the primary Si particle size and distribution in hypereutectic Al-Si alloy. In order to achieve this, there have been attempts to manufacture hypereutectic Al-Si alloy through a liquid phase sintering. This study investigated the microstructures and high temperature mechanical properties of hypereutectic Al-14Si-Cu-Mg alloy manufactured by liquid phase sintering process and changes in them after T6 heat treatment. Microstructural observation identified large amounts of small primary Si particles evenly distributed in the matrix, and small amounts of various precipitation phases were found in grain interiors and grain boundaries. After T6 heat treatment, the primary Si particle size and shape did not change significantly, but the size and distribution of CuAl2 ( θ) and AlCuMgSi ( Q) changed. Hardness tests measured 97.36 HV after sintering and 142.5 HV after heat treatment. Compression tests were performed from room temperature to 300 °C. The results represented that yield strength was greater after heat treatment (RT 300 °C: 351 93 MPa) than after sintering (RT 300 °C: 210 89 MPa). Fracture surface analysis identified cracks developing mostly along the interface between the primary Si particles and the matrix with some differences among temperature conditions. In addition, brittle fracture mode was found after T6 heat treatment.

  20. Effect of preparation conditions on the properties of Cu{sub 3}BiS{sub 3} thin films grown by a two - step process

    Energy Technology Data Exchange (ETDEWEB)

    Mesa, F; Gordillo, G, E-mail: fgmesar@unal.edu.c, E-mail: ggordillog@unal.edu.c [Departamento de Fisica, Universidad Nacional de Colombia, Bogota Cr.30 No 45-03 (Colombia)

    2009-05-01

    Cu{sub 3}BiS{sub 3} thin films were prepared on soda-lime glass substrates by co-evaporation of the precursors in a two-step process; for that, the metallic precursors were evaporated from a tungsten boat in presence of elemental sulfur evaporated from a tantalum effusion cell. The films were characterized by spectral transmittance, atomic force microscopy AFM and x-ray diffraction (XRD) measurements to investigate the effect of the growth conditions on the optical, morphological and structural properties. The results revealed that, independently of the deposition conditions, the films grow only in the orthorhombic Cu{sub 3}BiS{sub 3} phase. It was also found that the Cu{sub 3}BiS{sub 3} films present p-type conductivity, a high absorption coefficient (greater than 10{sup 4} cm{sup -1}) and an energy band gap Eg of about 1.41 eV, indicating that this compound has good properties to perform as absorbent layer in thin film solar cells.

  1. Electron spin relaxation governed by Raman processes both for Cu2+ ions and carbonate radicals in KHCO3 crystals: EPR and electron spin echo studies

    Science.gov (United States)

    Hoffmann, Stanislaw K.; Goslar, Janina; Lijewski, Stefan

    2012-08-01

    EPR studies of Cu2+ and two free radicals formed by γ-radiation were performed for KHCO3 single crystal at room temperature. From the rotational EPR results we concluded that Cu2+ is chelated by two carbonate molecules in a square planar configuration with spin-Hamiltonian parameters g|| = 2.2349 and A|| = 18.2 mT. Free radicals were identified as neutral HOCOrad with unpaired electron localized on the carbon atom and a radical anion CO3·- with unpaired electron localized on two oxygen atoms. The hyperfine splitting of the EPR lines by an interaction with a single hydrogen atom of HOCOrad was observed with isotropic coupling constants ao = 0.31 mT. Two differently oriented radical sites were identified in the crystal unit cell. Electron spin-lattice relaxation measured by electron spin echo methods shows that both Cu2+ and free radicals relax via two-phonon Raman processes with almost the same relaxation rate. The temperature dependence of the relaxation rate 1/T1 is well described with the effective Debye temperature ΘD = 175 K obtained from a fit to the Debye-type phonon spectrum. We calculated a more realistic Debye temperature value from available elastic constant values of the crystal as ΘD = 246 K. This ΘD-value and the Debye phonon spectrum approximation give a much worse fit to the experimental results. Possible contributions from a local mode or an optical mode are considered and it is suggested that the real phonon spectrum should be used for the relaxation data interpretation. It is unusual that free radicals in KHCO3 relax similarly to the well localized Cu2+ ions, which suggests a small destruction of the host crystal lattice by the ionizing irradiation allowing well coupling between radical and lattice dynamics.

  2. Room-Temperature and Solution-Processable Cu-Doped Nickel Oxide Nanoparticles for Efficient Hole-Transport Layers of Flexible Large-Area Perovskite Solar Cells.

    Science.gov (United States)

    He, Qiqi; Yao, Kai; Wang, Xiaofeng; Xia, Xuefeng; Leng, Shifeng; Li, Fan

    2017-12-06

    Flexible perovskite solar cells (PSCs) using plastic substrates have become one of the most attractive points in the field of thin-film solar cells. Low-temperature and solution-processable nanoparticles (NPs) enable the fabrication of semiconductor thin films in a simple and low-cost approach to function as charge-selective layers in flexible PSCs. Here, we synthesized phase-pure p-type Cu-doped NiO x NPs with good electrical properties, which can be processed to smooth, pinhole-free, and efficient hole transport layers (HTLs) with large-area uniformity over a wide range of film thickness using a room-temperature solution-processing technique. Such a high-quality inorganic HTL allows for the fabrication of flexible PSCs with an active area >1 cm 2 , which have a power conversion efficiency over 15.01% without hysteresis. Moreover, the Cu/NiO x NP-based flexible devices also demonstrate excellent air stability and mechanical stability compared to their counterpart fabricated on the pristine NiO x films. This work will contribute to the evolution of upscaling flexible PSCs with a simple fabrication process and high device performances.

  3. A rapid process of Yba2Cu3O7-δ thin film fabrication using trifluoroacetate metal-organic deposition with polyethylene glycol additive

    DEFF Research Database (Denmark)

    Wu, Wei; Feng, Feng; Shi, Kai

    2013-01-01

    Trifluoroacetate metal-organic deposition (TFA-MOD) is a promising technique to fabricate YBa2Cu3O7-δ (YBCO) superconducting films. However, its slow pyrolysis process, which usually takes more than 10 h, constitutes a barrier for industrial production. In this study, polyethylene glycol (PEG......) was utilized to reduce the stress generation inside the coated films when the strong pyrolysis reactions happen. With the addition of 30 wt% PEG2000 to the precursor solution, a smooth film surface could be obtained through a rapid pyrolysis process of 15 min. After the optimizations of the crystallization...... and oxygenation processes, mass percentage and molecular weight of PEG additive, YBCO thin films with Jc of about 4.5 MA cm-2 (77 K, self-field) could be routinely fabricated using (20-30) wt% PEG(1000-2000) additive with a total treatment time of about 2 h including the 15 min pyrolysis process time. The effects...

  4. Transport critical current density and microstructure in extruded YBa2Cu3O7-x wires processed by zone melting

    International Nuclear Information System (INIS)

    Shi, D.; Krishnan, H.; Hong, J.M.; Miller, D.; McGinn, P.J.; Chen, W.H.; Xu, M.; Chen, J.G.; Fang, M.M.; Welp, U.; Lanagan, M.T.; Goretta, K.C.; Dusek, J.T.; Picciolo, J.J.; Balachandran, U.

    1990-01-01

    YBa 2 Cu 3 O 7-x compounds were extruded into long wires with the diameter of 1 mm after sintering. The sintered wires were subsequently zone melted to develop a highly textured microstructure. Magnetization experiments at 77 K indicated a J c value of 1x10 5 A/cm 2 at 1 T. Transport measurements at 77 K showed a greatly enhanced field dependence of the critical current density. Transmission electron microscopy revealed an important grain-boundary feature which eliminated the weak-link behavior. Large amounts of dislocations have also been found in the zone-melted sample which may contribute to flux pinning in the system

  5. Magnetization reversal process and nonlinear magneto-impedance in Cu/NiFe and Nb/NiFe composite wires

    Energy Technology Data Exchange (ETDEWEB)

    Antonov, A.S.; Buznikov, N.A. E-mail: n_buznikov@mail.ru; Granovsky, A.B.; Iakubov, I.T.; Prokoshin, A.F.; Rakhmanov, A.L.; Yakunin, A.M

    2002-08-01

    The magnetization reversal of Cu/NiFe and Nb/NiFe composite wires carrying AC current is studied. The frequency spectrum of a voltage induced in a pick-up coil wound around the wire is analyzed. The frequency spectrum is shown to consist of even harmonics within a wide range of AC current amplitudes and longitudinal DC magnetic fields. The strong dependencies of the harmonic amplitudes on the DC field are found. The results obtained may be of importance for the design of weak magnetic field sensors.

  6. Magnetization reversal process and nonlinear magneto-impedance in Cu/NiFe and Nb/NiFe composite wires

    International Nuclear Information System (INIS)

    Antonov, A.S.; Buznikov, N.A.; Granovsky, A.B.; Iakubov, I.T.; Prokoshin, A.F.; Rakhmanov, A.L.; Yakunin, A.M.

    2002-01-01

    The magnetization reversal of Cu/NiFe and Nb/NiFe composite wires carrying AC current is studied. The frequency spectrum of a voltage induced in a pick-up coil wound around the wire is analyzed. The frequency spectrum is shown to consist of even harmonics within a wide range of AC current amplitudes and longitudinal DC magnetic fields. The strong dependencies of the harmonic amplitudes on the DC field are found. The results obtained may be of importance for the design of weak magnetic field sensors

  7. Electromagnetic Stirring versus ECAP: Morphological Comparison of Al-Si-Cu Alloys to Make the Microstructural Refinement for Use in SSM Processing

    Directory of Open Access Journals (Sweden)

    Luis Vanderlei Torres

    2016-01-01

    Full Text Available This work evaluates the morphological evolution at the semisolid state of the Al-4.0wt%Si-2.5wt%Cu alloy produced by direct chill casting under electromagnetic stirring (EMS and by one equal channel angular pressing (ECAP pass. The ECAP emerged as a promising technique capable of reduction and homogeneous metals microstructure imposing large deformations occurs in a matrix that contains two channels of the same cross-sectional area and forms an angle of 120°. The materials were submitted to reheating treatment in condition of 60% solid fraction at treatment times of 0, 30, and 90 s. Comparing the two cases, we have the presented ECAP process that had an excellent response to the recovery and recrystallization mechanisms, and refined microstructures ideal for thixoforming were produced. Primary particle sizes of about 45 μm and grain sizes of about 75 μm and a circularity shape factor of more than 0.60 were obtained. The low silicon alloy, Al-4.0wt%Si-2.5wt%Cu, presented excellent refinement when processed via equal channel angular pressing, presenting good morphological stability at the semisolid state, without significant changes in size or shape of the solid particles. This fully globular structure is favourable for thixoforming processes.

  8. Scanning electron microscopical examination of the impact of laser patterning on microscopic inhomogeneities of Cu(In,Ga)(Se,S)2 absorbers produced by rapid thermal processing

    International Nuclear Information System (INIS)

    Künecke, U.; Hölzing, A.; Jost, S.; Lechner, R.; Vogt, H.; Heiß, A.; Palm, J.; Hock, R.; Wellmann, P.

    2013-01-01

    Laser scribing of the Mo back electrode is commonly applied to define the cell structure of Cu(In,Ga)(Se,S) 2 (CIGSSe) thin film solar cells. The patterning process was performed on laboratory samples using ns and ps pulse length laser processes. After structuring, CIGSSe absorbers were processed by rapid thermal processing (RTP) of stacked elemental layer precursors. Microscopic inhomogeneities were investigated on different sample positions. For samples structured with ns pulse, the absorber morphology in the laser line vicinity is different as compared to the morphology in the unstructured cell area. Scanning electron microscopy and energy-dispersive X-ray spectroscopy show significant changes in the absorber grain size and chemical composition. Close to the laser line, the typically observed Ga accumulation on the back contact is less pronounced and more Ga is incorporated closer to the surface leading to a smaller grain size. The observed changes are attributed to partial damaging of a diffusion barrier between glass and Mo induced by the ns laser process, which allows diffusion of sodium from the glass substrate into the absorber during RTP. The enhanced Ga incorporation closer to the surface is an indication for the influence of sodium on the local phase development during RTP. The damages of the diffusion barrier can be effectively prevented by the application of a ps laser scribing process. CIGSSe absorbers processed on samples structured with ps pulse length do not show the described microscopic inhomogeneities around the laser line. - Highlights: ► Scanning electron microscopy on Cu(In,Ga)(Se,S) 2 solar cell absorbers ► Laser patterning with ns laser pulse damages the sodium diffusion barrier. ► Improved laser patterning with ps laser pulse leaves diffusion barrier intact. ► Additional sodium changes phase development during absorber formation. ► Gallium content is increased at surface and decreased at backside of absorber

  9. An evaluation of absorption spectroscopy to monitor YBa2Cu3O7-x precursors for metal organics chemical vapor deposition processing

    International Nuclear Information System (INIS)

    Matthew Edward Thomas

    1999-01-01

    Absorption spectroscopy was evaluated as a technique to monitor the metal organics chemical vapor deposition (MOCVD) process for forming YBa 2 Cu 3 O 7-x superconducting coated conductors. Specifically, this study analyzed the feasibility of using absorption spectroscopy to monitor the MOCVD supply vapor concentrations of the organic ligand 2,2,6,6-tetramethyl-3,5-heptanedionate (TMHD) metal chelates of barium, copper, and yttrium. Ba(TMHD) 2 , Cu(TMHD) 2 , and Y(TMHD) 3 compounds have successfully been vaporized in the MOCVD processing technique to form high temperature superconducting ''coated conductors,'' a promising technology for wire fabrication. The absorption study of the barium, copper, and yttrium (TMHD) precursors was conducted in the ultraviolet wavelength region from 200nm to 400nm. To simulate the MOCVD precursor flows the Ba(TMHD) 2 , Cu(TMHD) 2 , and Y(TMHD) 3 complexes were vaporized at vacuum pressures of (0.03--10)Torr. Spectral absorption scans of each precursor were conducted to examine potential measurement wavelengths for determining vapor concentrations of each precursor via Beer's law. The experimental results show that under vacuum conditions the barium, copper, and yttrium (TMHD) precursors begin to vaporize between 90 C and 135 C, which are considerably lower vaporization temperatures than atmospheric thermal gravimetric analyses indicate. Additionally, complete vaporization of the copper and yttrium (TMHD) precursors occurred during rapid heating at temperatures between 145 C and 195 C and after heating at constant temperatures between 90 C and 125 C for approximately one hour, whereas the Ba(TMHD) 2 precursor did not completely vaporize. At constant temperatures, near constant vaporization levels for each precursor were observed for extended periods of time. Detailed spectroscopic scans at stable vaporization conditions were conducted

  10. Controllable synthesis and enhanced photocatalytic properties of Cu2O/Cu31S16 composites

    International Nuclear Information System (INIS)

    Liu, Xueqin; Li, Zhen; Zhang, Qiang; Li, Fei

    2012-01-01

    Highlights: ► Facile sonochemical route. ► The content of Cu 31 S 16 in the Cu 2 O/Cu 31 S 16 can be easily controlled. ► Structure and optical properties of Cu 2 O/Cu 31 S 16 were discussed. ► Enhanced photocatalytic property of Cu 2 O/Cu 31 S 16 . ► Cu 2 O/Cu 31 S 16 core/shell structures were more stable than single Cu 2 O particles. -- Abstract: The controlled synthesis of Cu 2 O/Cu 31 S 16 microcomposites with hierarchical structures had been prepared via a convenient sonochemical route. Ultrasonic irradiation of a mixture of Cu 2 O and (NH 2 ) 2 CS in an aqueous medium yielded Cu 2 O/Cu 31 S 16 composites. The content of Cu 31 S 16 in the Cu 2 O/Cu 31 S 16 can be easily controlled by adjusting the synthesis time. The Cu 31 S 16 layer not only protected and stabilized Cu 2 O particles, but also prohibited the recombination of photogenerated electrons–holes pair between Cu 31 S 16 and Cu 2 O. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) spectra, ultraviolet–visible (UV–Vis) spectroscopy and photoluminescence (PL) spectroscopy were used to characterize the products. Photocatalytic performance of the Cu 2 O/Cu 31 S 16 hierarchical structures was evaluated by measuring the decomposition rate of methyl orange solution under natural light. To the best of our knowledge, this is the first report on the preparation and photocatalytic activity of Cu 2 O/Cu 31 S 16 microcomposite. Additionally, the Cu 2 O/Cu 31 S 16 core/shell structures were more stable than single Cu 2 O particles during photocatalytic process since the photocatalytic activity of the second reused architecture sample was much higher than that of pure Cu 2 O. The Cu 2 O/Cu 31 S 16 microcomposites may be a good promising candidate for wastewater treatment.

  11. Magnetic Properties of (Nia-ZnbX Cu1-X Ferrite Nanoparticle Fabricated by Sol-Gel Process

    Directory of Open Access Journals (Sweden)

    Yang S.

    2017-06-01

    Full Text Available In future, more mobile devices with different frequencies will be used at the same time. Therefore, it is expected that the trouble caused by wave interference between devices will be further intensified. In order to prevent this trouble, investigation of selective frequency transmission or absorption material is required. In this paper, magnetic properties of nickel-zinc-copper ferrite nano powder was researched as wave absorber. (Nia-ZnbxCu1-xFe2O4(NZCF nanoparticles were fabricated by the sol-gel method. The influence of copper substitution on lattice parameter change was analyzed by X-ray diffraction (XRD, particle size was analyzed by scanning electron microscopy (SEM, and Magnetic properties analyzed by vibrating sample magnetometer (VSM. The NZCF and Nickel-zinc ferrite (NZF lattice parameter difference was 0.028 Å and particle size was calculated as 30 nm with the XRD peak. The VSM results of (Ni0.3-Zn0.30.6Cu1-0.6Fe2O4 annealed sample at 700°C for 3hous were 58.5 emu/g (Ms, 22.8 Oe (Hc. It was the most suitable magnetic properties for wave absorber in this investigation.

  12. Investigation of sol-gel processed CuO/SiO2 nanocomposite as a potential photoanode material

    Directory of Open Access Journals (Sweden)

    Tenkyong Tenzin

    2015-12-01

    Full Text Available Synthesis and characterization of a highly efficient photoconductive nanocomposite comprising of two common metal oxides: copper oxide (CuO and silicon dioxide (SiO2 are being reported in this paper. The CuO/SiO2 nanocomposite has been synthesized using a cost-effective and facile sol gel route. The structural, chemical and optical properties of the prepared samples have been studied using various characterization techniques. The UV-Vis analysis revealed better absorption in the case of the nanocomposite as compared to its parent materials. X-ray diffraction (XRD analysis has been employed to determine the structural formation of the nanocomposite and the crystallite size with the use of Scherrer’s formula. The photo conductivity study of the sample showed enhanced photocurrent in the case of nanocomposite as compared to its single components, thus, presenting it as a potential candidate for solar cell applications, especially as photoanode material in the dye-sensitized solar cells (DSSC.

  13. Temperature field in the hot-top during casting a new super-high strength Al-Zn-Mg-Cu alloy by low frequency electromagnetic process

    Directory of Open Access Journals (Sweden)

    Yubo ZUO

    2005-08-01

    Full Text Available The billets of a new super-high strength Al-Zn-Mg-Cu alloy in 200 mm diameter were produced by the processed of low frequency electromagnetic casting (LFEC and conventional direct chill(DCcasting, respectively. The effects of low frequency electromagnetic field on temperature field of the melt in the hot-top were investigated by temperature thermocouples into the casting during the processes. The results show that during LFEC process the temperature field in the melt applying the hot-top is very uniform, which is helpful to reduce the difference of thermal gradients between the surface and the center, and then to reduce the thermal stress and to eliminate casting crack.

  14. Influence of cobalt and chromium additions on the precipitation processes in a Cu-4Ti alloys; Influencia de la adicion de cobalto y cromo en el proceso de precipitacion en una aleacion de Cu-4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Donoso, E.

    2010-07-01

    The influence of 0.5% atomic cobalt and 1% atomic chromium additions on the precipitation hardening of Cu-4Ti alloy was studied by differential scanning calorimetry (DSC) and microhardness measurements. The analysis of the calorimetric curves, for binary alloy, shows the presence of two overlapping exothermic reactions (stages 1 and 2) attributed to the formation of Cu{sub 4}Ti and Cu{sub 3}Ti particles in the copper matrix, respectively. DSC curves for Cu-4Ti-0.5Co alloy shows three exothermic effects (overlapping stages 3 and 4 and stage 5) associated to the formation of phases Ti{sub 2}Co, TiCo and Cu{sub 4}Ti, respectively. DSC curves for Cu-4Ti1Cr alloy shows three exothermic reactions (stages 6, 7 and 9) and one endothermic peak (stage 8). The exothermic reactions correspond to the formation of phases Cr{sub 2}Ti, Cu{sub 4}Ti and Cu{sub 3}Ti, respectively, and the endothermic reactions are attributed to the Cr{sub 2}Ti dissolution. The activation energies calculated using the modified Kissinger method were lower than the ones corresponding to diffusion of cobalt, chromium, and titanium in copper. Kinetic parameters were obtained by a convolution method based on the Johnson-Mehl-Avrami (JMA) formalism. Microhardness measurements confirmed the formation of the mentioned phases. Also, these measurements confirmed the effect of cobalt and chromium addition on the binary alloy hardness. (Author). 31 refs.

  15. Cu/Cu{sub 2}O/CuO nanoparticles: Novel synthesis by exploding wire technique and extensive characterization

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, Anshuman [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, A-10, Sector-62, Noida 201307 (India); Goswami, Navendu, E-mail: navendugoswami@gmail.com [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, A-10, Sector-62, Noida 201307 (India); Kaushik, S.D. [UGC-DAE-Consortium for Scientific Research Mumbai Centre, R5 Shed, BARC, Mumbai 400085 (India); Tripathi, Shilpa [UGC-DAE Consortium for Scientific Research, Indore, M.P. (India)

    2016-12-30

    Highlights: The salient features of this research article are following: • Mixed phase synthesis of Cu/Cu{sub 2}O/CuO nanoparticles prepared by Exploding Wire Technique (EWT). • Predominant Cu/Cu{sub 2}O phases along with minor CuO phase revealed through XRD, TEM, Raman, FTIR, UV–Visible and PL analyses. • XPS analysis provided direct evidences of Cu{sup 2+} and Cu{sup +} along with O deficiency for prepared nanoparticles. • Room temperature weak ferromagnetic behaviour was demonstrated for Cu/Cu{sub 2}O/CuO nanoparticles. - Abstract: In this article, we explore potential of Exploding Wire Technique (EWT) to synthesize the copper nanoparticles using the copper metal in a plate and wire geometry. Rietveld refinement of X-ray diffraction (XRD) pattern of prepared material indicates presence of mixed phases of copper (Cu) and copper oxide (Cu{sub 2}O). Agglomerates of copper and copper oxide comprised of ∼20 nm average size nanoparticles observed through high resolution transmission electron microscope (HRTEM) and energy dispersive x-ray (EDX) spectroscopy. Micro-Raman (μR) and Fourier transform infrared (FTIR) spectroscopies of prepared nanoparticles reveal existence of additional minority CuO phase, not determined earlier through XRD and TEM analysis. μR investigations vividly reveal cubic Cu{sub 2}O and monoclinic CuO phases based on the difference of space group symmetries. In good agreement with μRaman analysis, FTIR stretching modes corresponding to Cu{sub 2}-O and Cu-O were also distinguished. Investigations of μR and FTIR vibrational modes are in accordance and affirm concurrence of CuO phases besides predominant Cu and Cu{sub 2}O phase. Quantum confinement effects along with increase of band gaps for direct and indirect optical transitions of Cu/Cu{sub 2}O/CuO nanoparticles are reflected through UV–vis (UV–vis) spectroscopy. Photoluminescence (PL) spectroscopy spots the electronic levels of each phase and optical transitions processes

  16. Correlation between product purity and process parameters for the synthesis of Cu2ZnSnS4 nanoparticles using microwave irradiation

    Science.gov (United States)

    Ahmad, R.; Nicholson, K. S.; Nawaz, Q.; Peukert, W.; Distaso, M.

    2017-07-01

    Kesterites (CZT(S,Se)4) emerged as a favourable photovoltaic material, leading to solar cell efficiencies as high as 12.7%. The development of sustainable roll-to-roll printing processes that make use of Cu2ZnSnS4 (CZTS) nanoparticle inks requires the proper design of synthetic approaches and the understanding of the relation between process parameters and product purity. In the current paper, we developed this relationship by calculating a specific energy factor. A microwave-assisted synthetic method that operates at atmospheric pressure and makes use of eco-friendly solvents is established. Four solvents, i.e. ethylene glycol (EG), diethylene glycol (di-EG), triethylene glycol (tri-EG) and tetraethylene glycol (tet-EG) are compared and the temperature during the reaction is assessed by two different methods. In particular, two by-products have been identified, i.e. Cu2 - x S and a hexagonal phase. We show that the variation of reaction parameters such as power irradiation, type of solvent and precursor concentration influences the nanoparticles' sizes (from 12 to 6 nm) and also the temperature-time profile of reaction which, in turn, can be related to phase purity of CZTS nanoparticles. The results suggest that the product purity scales with the specific energy factor providing a useful tool to a rational design of high-quality CZTS nanoparticles.

  17. Corrosion and wear behavior of Ni60CuMoW coatings fabricated by combination of laser cladding and mechanical vibration processing

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hongxi, E-mail: piiiliuhx@sina.com [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Xu, Qian [Faculty of Adult Education, Kunming University of Science and Technology, Kunming 650051 (China); Wang, Chuanqi; Zhang, Xiaowei [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

    2015-02-05

    Highlights: • Ni60CuMoW coatings were fabricated by mechanical vibration assisted laser cladding hybrid process. • The maximum micro-hardness of the coating with mechanical vibration increases by 16%. • The mass loss and friction coefficient of the coating decreases by 17% and 16%, respectively. • The E{sub corr} positive shifts 1134.9 mV and i{sub corr} decreases by nearly one order of magnitude. • The ideal vibration parameters is vibration frequency 200 Hz and vibration amplitude 140 μm. - Abstract: Ni60CuMoW composite coatings were fabricated on 45 medium carbon steel using mechanical vibration assisted laser cladding surface modification processing. The microstructure, element distribution, phase composition, microhardness, wear and corrosion resistance of cladding coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), hardness tester, friction and wear apparatus and electrochemical workstation. The results indicate that the microstructure of M{sub 23}C{sub 6} (Cr{sub 23}C{sub 6} or (Fe, Ni){sub 23}C{sub 6}) carbide dispersion strengthening phase is uniformly distributed in eutectic (Ni, Fe) phase. The in-situ BCr and MoC compounds distribute in lamellar structure Fe{sub 3}B and dendrite Fe{sub 3}Ni{sub 3}Si, and some new W{sub 2}C phases also generated in Ni60CuMoW coating. In addition, the coarse dendrite has been replaced by some fine grain structure at the bonding interface. The fine grain hard phase makes the average microhardness of cladding coating increase from 720 to 835 HV{sub 0.5}. Under the condition of 200 Hz mechanical vibration frequency, the wear mass loss and friction coefficient of Ni60CuMoW coating are 7.6 mg and 0.068, 17% and 16% lower than the coating without mechanical vibration, respectively. The corrosion potential of cladding coating with mechanical vibration increases by 1134.9 mV and the corrosion current density decreases by nearly one order of

  18. Nd-Fe-B-Cu hot deformation processing: a comparison of deformation modes, microstructural development and magnetic properties

    International Nuclear Information System (INIS)

    Ferrante, M.; Sinka, V.; Assis, O.B.G.; Oliveira, I. de; Freitas, E. de

    1996-01-01

    Due to its relative simplicity and low cost the hot deformation of Nd-Fe-B ingots is rapidly reaching the status of a valid alternative to sintering. Among the possible deformation modes, pressing, rolling and forging are perhaps the most successful. This paper describes the research programme undertaken so far, by discussing the relationship between deformation mode, microstructure and magnetic properties of magnets produced by hot deformation mode, microstructure and magnetic properties of magnets produced by hot deformation of a number of Nd-fe-B-Cu alloys. Microstructural observation showed that both pressed and forged samples are characterized by a heterogeneous microstructure and from magnetic measurements it was concluded that magnetic properties differ when taken in the center or in the periphery of the sample. On the other hand roller magnets were homogeneous both in terms of microstructure and magnetic properties, and interpretations of the mechanisms of texture development and of microstructural development of hot deformed magnets is put forward. (author)

  19. Processing tetramethylammonium-carbonate-coprecipitated slurries to obtain small-particle-size YBa2Cu3O7

    International Nuclear Information System (INIS)

    Spencer, N.D.; Peders, T.S.; Baer, M.B.

    1991-01-01

    The effect of different drying and calcination methods on the ultimate particle size of YBa 2 Cu 3 O 7 (Y-123) has been investigated. The starting material was a tetramethylammonium (TMA) carbonate-precipitated slurry. Spray-drying the slurry after filtering and reslurrying (to remove residual TMA), was most effective in the ultimate formation of finely divided Y-123. The morphology of the spray-dried powder could be preserved by calcining in very low total pressures of flowing oxygen. When a slurry with 0.16% solids content was spray dried, and this powder calcined at 750 degree C in 2 Torr of flowing oxygen, a Y-123 powder of mean particle size 0.74 μm (66% submicron) was obtained

  20. Shape memory characteristics and mechanical properties of powder metallurgy processed Ti50Ni40Cu10 alloy.

    Science.gov (United States)

    Kim, Yeon-Wook

    2014-10-01

    Ti-Ni-Cu alloy powders were prepared by gas atomization and porous bulk specimens were fabricated by spark plasma sintering (SPS). The microstructure of as-solidified powders exhibited a cellular structure and they contained a high density of nano-sized porosities which were located in the intercellular regions. XRD analysis showed that one-step martensitic transformation of B2-B19 occurred in all alloy powders and SPS specimens. When the martensitic transformation start temperature (M(s)) and austenite transformation finish temperature (A(f)) were determined in order to analyze the dependence of powder size on transformation temperatures, the M(s) increased slightly from -17.5 degrees C to - 14.6 degrees C as increasing the powder size ranging from between 25 and 50 μm to ranging between 100 and 150 μm. However, the M(s) and A(f) of the as-atomized powders is much smaller than those of SPS specimens and the M(s) of porous specimen was about 10.9 degrees C. Loading-unloading compressive tests were carried out to investigate the mechanical properties of porous Ti-Ni-Cu specimen. The specimen was compressed to the strain of 6% at a temperature higher than A,. After unloading, the residual strain was 2.1%. After the compressed specimen was heated to 60 degrees C and held for 30 minutes and then cooled to room temperature, the changes in the length of the specimens were measured. Then it was found that the recovered strain ascribed to shape memory effect was 1.5%.

  1. Highly Conductive Cu 2– x S Nanoparticle Films through Room-Temperature Processing and an Order of Magnitude Enhancement of Conductivity via Electrophoretic Deposition

    KAUST Repository

    Otelaja, Obafemi O.

    2014-11-12

    © 2014 American Chemical Society. A facile room-temperature method for assembling colloidal copper sulfide (Cu2-xS) nanoparticles into highly electrically conducting films is presented. Ammonium sulfide is utilized for connecting the nanoparticles via ligand removal, which transforms the as-deposited insulating films into highly conducting films. Electronic properties of the treated films are characterized with a combination of Hall effect measurements, field-effect transistor measurements, temperature-dependent conductivity measurements, and capacitance-voltage measurements, revealing their highly doped p-type semiconducting nature. The spin-cast nanoparticle films have carrier concentration of ∼1019 cm-3, Hall mobilities of ∼3 to 4 cm2 V-1 s-1, and electrical conductivities of ∼5 to 6 S·cm-1. Our films have hole mobilities that are 1-4 orders of magnitude higher than hole mobilities previously reported for heat-treated nanoparticle films of HgTe, InSb, PbS, PbTe, and PbSe. We show that electrophoretic deposition (EPD) as a method for nanoparticle film assembly leads to an order of magnitude enhancement in film conductivity (∼75 S·cm-1) over conventional spin-casting, creating copper sulfide nanoparticle films with conductivities comparable to bulk films formed through physical deposition methods. The X-ray diffraction patterns of the Cu2-xS films, with and without ligand removal, match the Djurleite phase (Cu1.94S) of copper sulfide and show that the nanoparticles maintain finite size after the ammonium sulfide processing. The high conductivities reported are attributed to better interparticle coupling through the ammonium sulfide treatment. This approach presents a scalable room-temperature route for fabricating highly conducting nanoparticle assemblies for large-area electronic and optoelectronic applications.

  2. A Sustainable and Selective Roasting and Water-Leaching Process to Simultaneously Extract Valuable Metals from Low-Grade Ni-Cu Matte

    Science.gov (United States)

    Cui, Fuhui; Mu, Wenning; Wang, Shuai; Xin, Haixia; Xu, Qian; Zhai, Yuchun

    2018-03-01

    Due to stringent environmental requirements and the complex occurrence of valuable metals, traditional pyrometallurgical methods are unsuitable for treating low-grade nickel-copper matte. A clean and sustainable two-stage sulfating roasting and water-leaching process was used to simultaneously extract valuable metals from low-grade nickel-copper matte. Ammonium and sodium sulfate were used as sulfating agents. The first roasting temperature, mass ratio of ammonium sulfate to matte, roasting time, dosage of sodium sulfate, second roasting temperature and leaching temperature were studied. Under optimal conditions, 98.89% of Ni, 97.48% of Cu and 95.82% of Co, but only 1.34% of Fe, were extracted. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to reveal the sulfating mechanism during the roasting process.

  3. From Solidification Processing to Microstructure to Mechanical Properties: A Multi-scale X-ray Study of an Al-Cu Alloy Sample

    Science.gov (United States)

    Tourret, D.; Mertens, J. C. E.; Lieberman, E.; Imhoff, S. D.; Gibbs, J. W.; Henderson, K.; Fezzaa, K.; Deriy, A. L.; Sun, T.; Lebensohn, R. A.; Patterson, B. M.; Clarke, A. J.

    2017-11-01

    We follow an Al-12 at. pct Cu alloy sample from the liquid state to mechanical failure, using in situ X-ray radiography during directional solidification and tensile testing, as well as three-dimensional computed tomography of the microstructure before and after mechanical testing. The solidification processing stage is simulated with a multi-scale dendritic needle network model, and the micromechanical behavior of the solidified microstructure is simulated using voxelized tomography data and an elasto-viscoplastic fast Fourier transform model. This study demonstrates the feasibility of direct in situ monitoring of a metal alloy microstructure from the liquid processing stage up to its mechanical failure, supported by quantitative simulations of microstructure formation and its mechanical behavior.

  4. Investigation of different ethylenediamine-N,N'-disuccinic acid-enhanced washing configurations for remediation of a Cu-contaminated soil: process kinetics and efficiency comparison between single-stage and multi-stage configurations.

    Science.gov (United States)

    Ferraro, Alberto; Fabbricino, Massimiliano; van Hullebusch, Eric D; Esposito, Giovanni

    2017-09-01

    A comparison of Cu extraction yields for three different ethylenediamine-N,N'-disuccinic acid (EDDS)-enhanced washing configurations was performed on a Cu-contaminated soil. Batch experiments were used to simulate a single-stage continuous stirred tank reactor (CSTR) and a multi-stage (side feeding and counter-current) reactor. Single-stage CSTR conditions were simulated for various EDDS:(Cu + Cd + Pb + Co + Ni + Zn) molar ratio (EDDS:M ratio) (from 1 to 30) and liquid to soil (L/S) ratio (from 15 to 45). The highest Cu extraction yield (≃56%) was achieved with EDDS:M = 30. In contrast, a Cu extraction yield decrease was observed with increasing L/S ratio with highest extracted Cu achievement (≃48%) for L/S = 15. Side feeding configuration was tested in four experimental conditions through different fractionation mode of EDDS dose and treatment time at each washing step. Results from the four tests showed all enhanced Cu extraction (maximum values from ≃43 to ≃51%) achieved at lower treatment time and lower EDDS:M molar ratio compared to CSTR configuration with L/S = 25 and EDDS:M = 10. The counter-current washing was carried out through two washing flows achieving a process performance enhancement with 27% increase of extracted Cu compared to single-stage CSTR configuration. Higher Cu extraction percentage (36.8%) was observed in the first washing phase than in the second one (24.7%).

  5. Y{sub 2}BaCuO{sub 5} particle distribution in YBa{sub 2}Cu{sub 3}O{sub 7-y} grains of melt growth processed YBCO oxides; Y{sub 2}BaCuO{sub 5}-Partikelverteilung in YBa{sub 2}Cu{sub 3}O{sub 7-y}-Koernern durch das Melt-Growth-Verfahren verarbeiteter YBCO-Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan-Joong; Park, Soon-Dong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of). Neutron Science Div.; Park, Hai-Woong [Korea Univ. of Technology and Education, Chungnam (Korea, Republic of). College of Energy, Materials and Chemical Engineering

    2013-02-01

    Y{sub 2}BaCuO{sub 5} (Y211) particle distribution within YBa{sub 2}Cu{sub 3}O{sub 7-y} (Y123) grains of YBCO samples melt growth (MG) processed was examined. To understand the processing variables on the Y211 distribution, a cooling rate (R{sub C}=1 K/h to R{sub C}=20 K/h) through a peritectic temperature (T{sub p} = 1010 C), a precursor powder size and composition were changed. Two different Y211 distributions (a linear x-like track and planar butterfly-like pattern) were observed, depending on the processing variables. The linear x-like Y211 tracks were observed in the Y123 samples prepared using a stoichiometric Y123 precursor, whereas the planar butterfly-like Y211 patterns were observed in the Y{sub 1.8}Ba{sub 2.4}Cu{sub 3.4}O{sub 7-d} (Y1.8) samples prepared using an Y211-excess composition precursor. The track and planar Y211 patterns were clearer at lower R{sub C} (slower growth rate of Y123 grains) and for the smaller Y211 particles. In contrast, the random Y211 distribution was dominant at the higher R{sub C} and for the larger Y211 particles. The Y211 distribution patterns in the Y123 grains were explained in terms of the interfacial energy difference among growing Y123 fronts. (orig.)

  6. Growth orientation and superconducting properties of YBa2Cu3O7-δ films prepared by the low-fluorine sol-gel process

    International Nuclear Information System (INIS)

    Lei Li; Zhao Gaoyang; Xu Hui; Zhao Juanjuan

    2010-01-01

    YBa 2 Cu 3 O 7-δ (YBCO) films were deposited on (100)-oriented LaAlO 3 (LAO) single crystal substrates by the dip-coating process using low-fluorine solution. Their microstructures were characterized with the aid of X-ray diffractometry, scanning electron microscopy and high-resolution transmission electron microscopy. Their superconducting properties were measured by the standard four-probe method. The experiment results show that the film obtained under high enough humidity conditions exhibits better c-axis texture and superconducting properties than the film under a relatively low humidity conditions. Based on the classical nucleation and chemical reaction thermodynamics theory, the underlying crystalline and growth mechanisms of YBCO films under certain humidity conditions are explained in combination with our experimental results. It is suggested that the unreacted intermediate phases such as BaF 2 and CuO aggregated in the YBCO grain boundary will cause lattice distortion in the YBCO matrix and further induce the formation of a-axis oriented YBCO grains as crystallization proceeds. Therefore, it is believed that the relative content of water vapor within the heat-treatment atmosphere plays quite an important role in the preparation of c-axis oriented YBCO film with good superconducting properties. (semiconductor materials)

  7. Simulation of the concomitant process of nucleation-growth-coarsening of Al2Cu particles in a 319 foundry aluminum alloy

    International Nuclear Information System (INIS)

    Martinez, R; Larouche, D; Cailletaud, G; Guillot, I; Massinon, D

    2015-01-01

    The precipitation of Al 2 Cu particles in a 319 T7 aluminum alloy has been modeled. A theoretical approach enables the concomitant computation of nucleation, growth and coarsening. The framework is based on an implicit scheme using the finite differences. The equation of continuity is discretized in time and space in order to obtain a matricial form. The inversion of a tridiagonal matrix gives way to determining the evolution of the size distribution of Al 2 Cu particles at t  +Δt. The fluxes of in-between the boundaries are computed in order to respect the conservation of the mass of the system, as well as the fluxes at the boundaries. The essential results of the model are compared to TEM measurements. Simulations provide quantitative features on the impact of the cooling rate on the size distribution of particles. They also provide results in agreement with the TEM measurements. This kind of multiscale approach allows new perspectives to be examined in the process of designing highly loaded components such as cylinder heads. It enables a more precise prediction of the microstructure and its evolution as a function of continuous cooling rates. (paper)

  8. Solution-processed p-type copper(I) thiocyanate (CuSCN) for low-voltage flexible thin-film transistors and integrated inverter circuits

    KAUST Repository

    Petti, Luisa

    2017-03-17

    We report on low operating voltage thin-film transistors (TFTs) and integrated inverters based on copper(I) thiocyanate (CuSCN) layers processed from solution at low temperature on free-standing plastic foils. As-fabricated coplanar bottom-gate and staggered top-gate TFTs exhibit hole-transporting characteristics with average mobility values of 0.0016 cm2 V−1 s−1 and 0.013 cm2 V−1 s−1, respectively, current on/off ratio in the range 102–104, and maximum operating voltages between −3.5 and −10 V, depending on the gate dielectric employed. The promising TFT characteristics enable fabrication of unipolar NOT gates on flexible free-standing plastic substrates with voltage gain of 3.4 at voltages as low as −3.5 V. Importantly, discrete CuSCN transistors and integrated logic inverters remain fully functional even when mechanically bent to a tensile radius of 4 mm, demonstrating the potential of the technology for flexible electronics.

  9. The grinding behavior of ground copper powder for Cu/CNT nanocomposite fabrication by using the dry grinding process with a high-speed planetary ball mill

    Science.gov (United States)

    Choi, Heekyu; Bor, Amgalan; Sakuragi, Shiori; Lee, Jehyun; Lim, Hyung-Tae

    2016-01-01

    The behavior of ground copper powder for copper-carbon nanotube (copper-CNT) nanocomposite fabrication during high-speed planetary ball milling was investigated because the study of the behavior characteristics of copper powder has recently gained scientific interest. Also, studies of Cu/CNT composites have widely been done due to their useful applications to enhanced, advanced nano materials and components, which would significantly improve the properties of new mechatronics-integrated materials and components. This study varied experimental conditions such as the rotation speed and the grinding time with and without CNTs, and the particle size distribution, median diameter, crystal structure and size, and particle morphology were monitored for a given grinding time. We observed that pure copper powders agglomerated and that the morphology changed with changing rotation speed. The particle agglomerations were observed with maximum experiment conditions (700 rpm, 60 min) in this study of the grinding process for mechanical alloys in the case of pure copper powders because the grinding behavior of Cu/CNT agglomerations was affected by the addition of CNTs. Indeed, the powder morphology and the crystal size of the composite powder could be changed by increasing the grinding time and the rotation speed.

  10. Preparation of PtSnCu/C and PtSn/C electrocatalysts and activation by dealloying processes for ethanol electrooxidation; Preparacao de eletrocatalisadores PtSnCu/C e PtSn/C e ativacao por processos de dealloying para aplicacao na oxidacao eletroquuimica do etanol

    Energy Technology Data Exchange (ETDEWEB)

    Crisafulli, Rudy

    2013-06-01

    PtSnCu/C (with different Pt:Sn:Cu atomic ratios) and PtSn/C (50:50) electrocatalysts were prepared by borohydride (BR) and alcohol-reduction (AR) processes using H{sub 2}PtCl{sub 6}.6H{sub 2}O, SnCl{sub 2}.2H{sub 2}O and CuCl{sub 2}.2H{sub 2}O as metal sources, NaBH{sub 4} and ethylene glycol as reducing agents, 2-propanol and ethylene glycol/water as solvents and carbon black as support. In a further step, these electrocatalysts were activated by chemical (CD) and electrochemical (ED) dealloying processes through acid treatment and thin porous coating technique, respectively. These materials were characterized by energy dispersive X-ray, Xray diffraction, transmission electron microscopy, line scan energy dispersive Xray and cyclic voltammetry. Electrochemical studies for ethanol electro-oxidation were performed by cyclic voltammetry, chronoamperometry and in single Direct Ethanol Fuel Cell using Membrane Electrode Assembly (MEA). The anodic effluents were analysed by gas chromatography. The X-ray diffractograms of the as-synthesized electrocatalysts showed the typical face-centered cubic structure (FCC) of platinum and its alloys. After dealloying, the X-ray diffractograms showed that the Pt FCC structure was preserved. The crystallite sizes of the assynthesized electrocatalysts were in the range of <=2 nm to 3 nm and after dealloying there were no significant variations in sizes. The energy dispersive Xray analysis of the as-synthesized electrocatalysts showed a Pt:Sn and Pt:Sn:Cu atomic ratios similar to the nominal values. After chemical and electrochemical dealloying of the electrocatalysts the ranged Pt:Sn and Pt:Sn:Cu atomic ratios showed that Cu and Sn atoms were removed. However, chemical dealloying process proved to be more efficient for removing Cu and electrochemical dealloying for removing Sn. The line scan energy dispersive X-ray analysis showed that acid and electrochemical treatments were efficient to dealloying Cu and/or Sn superficial atoms of

  11. CH{sub 4} dehydrogenation on Cu(1 1 1), Cu@Cu(1 1 1), Rh@Cu(1 1 1) and RhCu(1 1 1) surfaces: A comparison studies of catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Riguang; Duan, Tian [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Ling, Lixia [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Research Institute of Special Chemicals, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Wang, Baojun, E-mail: wangbaojun@tyut.edu.cn [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China)

    2015-06-30

    Highlights: • Adsorbed Rh atom on Cu catalyst exhibits better catalytic activity for CH{sub 4} dehydrogenation. • The adsorbed Rh atom is the reaction active center for CH{sub 4} dehydrogenation. • The morphology of Cu substrate has negligible effect on CH{sub 4} dehydrogenation. - Abstract: In the CVD growth of graphene, the reaction barriers of the dehydrogenation for hydrocarbon molecules directly decide the graphene CVD growth temperature. In this study, density functional theory method has been employed to comparatively probe into CH{sub 4} dehydrogenation on four types of Cu(1 1 1) surface, including the flat Cu(1 1 1) surface (labeled as Cu(1 1 1)) and the Cu(1 1 1) surface with one surface Cu atom substituted by one Rh atom (labeled as RhCu(1 1 1)), as well as the Cu(1 1 1) surface with one Cu or Rh adatom (labeled as Cu@Cu(1 1 1) and Rh@Cu(1 1 1), respectively). Our results show that the highest barrier of the whole CH{sub 4} dehydrogenation process is remarkably reduced from 448.7 and 418.4 kJ mol{sup −1} on the flat Cu(1 1 1) and Cu@Cu(1 1 1) surfaces to 258.9 kJ mol{sup −1} on RhCu(1 1 1) surface, and to 180.0 kJ mol{sup −1} on Rh@Cu(1 1 1) surface, indicating that the adsorbed or substituted Rh atom on Cu catalyst can exhibit better catalytic activity for CH{sub 4} complete dehydrogenation; meanwhile, since the differences for the highest barrier between Cu@Cu(1 1 1) and Cu(1 1 1) surfaces are smaller, the catalytic behaviors of Cu@Cu(1 1 1) surface are very close to the flat Cu(1 1 1) surface, suggesting that the morphology of Cu substrate does not obviously affect the dehydrogenation of CH{sub 4}, which accords with the reported experimental observations. As a result, the adsorbed or substituted Rh atom on Cu catalyst exhibit a better catalytic activity for CH{sub 4} dehydrogenation compared to the pure Cu catalyst, especially on Rh-adsorbed Cu catalyst, we can conclude that the potential of synthesizing high-quality graphene with the

  12. The influence of the addition of depleted uranium on particle pushing in melt-processed, bulk Y-Ba-Cu-O

    International Nuclear Information System (INIS)

    Diko, P; Zmorayova, K; Babu, N Hari; Krabbes, G; Cardwell, D A

    2004-01-01

    The microstructure of single-grain, melt-processed (MP) YBa 2 Cu 3 O 7 /Y 2 BaCuO 5 (Y-123/Y-211) samples (YBCO) containing varying amounts of depleted uranium (DU) and Pt has been studied. Only partial refinement of the Y-211 particle size was observed in Pt-free samples, which generally contained both small and large Y-211 particles. Small Y-211 particles in these samples are pushed extensively in the c-growth sector (c-GS) and all Y-211 particles (small and large) coarsen with the distance from the seed and with increasing DU concentration. Samples fabricated with Pt contained only very fine Y-211 particles, which were generally pushed strongly in the c-GS. In this case the size of the Y-211 particles did not vary significantly with distance from the seed. U- and U/Pt-containing sub-micron sized particles present in the melt-processed YBCO microstructure were not pushed during solidification, although their arrangement within the structure of the sample was influenced clearly by the growth process. The so-called cyclic growth was observed in the c-GS at the highest DU concentration (0.8 wt%). In these samples, this growth pattern is associated with the formation of a liquid phase rich in U and Y at the growth front. The cyclic growth mechanism was modified by the addition of Pt. Crystals of Y 2 Ba 4 UCuO x with Ba 3 YUO x phase inclusions were observed to be present in the U/Y-rich melt

  13. Effects of improved process for CuO-doped NKN lead-free ceramics on high-power piezoelectric transformers.

    Science.gov (United States)

    Yang, Song-Ling; Tsai, Cheng-Che; Liou, Yi-Cheng; Hong, Cheng-Shong; Li, Bing-Jing; Chu, Sheng-Yuan

    2011-12-01

    In this paper, the effects of the electrical proper- ties of CuO-doped (Na(0.5)K(0.5))NbO(3) (NKN) ceramics prepared separately using the B-site oxide precursor method (BO method) and conventional mixed-oxide method (MO method) on high-power piezoelectric transformers (PTs) were investigated. The performances of PTs made with these two substrates were compared. Experimental results showed that the output power and temperature stability of PTs could be enhanced because of the lower resonant impedance of the ceramics prepared using the BO method. In addition, the output power of PTs was more affected by the resonant impedance than by the mechanical quality factor (Q(m)) of the ceramics. The PTs fabricated with ceramics prepared using the BO method showed a high efficiency of more than 94% and a maximum output power of 8.98 W (power density: 18.3 W/cm(3)) with temperature increase of 3°C under the optimum load resistance (5 kΩ) and an input voltage of 150 V(pp). This output power of the lead-free disk-type PTs is the best reported so far.

  14. Copper(I) Thiocyanate (CuSCN) Hole-Transport Layers Processed from Aqueous Precursor Solutions and Their Application in Thin-Film Transistors and Highly Efficient Organic and Organometal Halide Perovskite Solar Cells

    KAUST Repository

    Wijeyasinghe, Nilushi; Regoutz, Anna; Eisner, Flurin; Du, Tian; Tsetseris, Leonidas; Lin, Yen-Hung; Faber, Hendrik; Pattanasattayavong, Pichaya; Li, Jinhua; Yan, Feng; McLachlan, Martyn A.; Payne, David J.; Heeney, Martin; Anthopoulos, Thomas D.

    2017-01-01

    spectra agree with first-principles calculations. Study of the hole-transport properties using field-effect transistor measurements reveals that the aqueous-processed CuSCN layers exhibit a fivefold higher hole mobility than films processed from diethyl

  15. Importance of controlling the Tl-oxide partial pressure throughout the processing of TlBa2CaCu2O7 thin films

    International Nuclear Information System (INIS)

    Siegal, M.P.; Venturini, E.L.; Newcomer, P.P.; Overmyer, D.L.; Dominguez, F.; Dunn, R.

    1995-01-01

    TlBa 2 CaCu 2 O 7 (Tl-1212) superconducting films 5000--6000 A thick have been grown on LaAlO 3 (100) substrates using oxide precursors in a closed two-zone thallination furnace. Tl-1212 films can be grown with transition temperatures ∼100 K, and critical current densities measured by magnetization of J cm (5 K)>10 7 A/cm 2 and J cm (77 K)>10 5 A/cm 2 . Processing conditions, substrate temperatures and Tl-oxide source temperatures are found which result in smooth, nearly phase-pure Tl-1212 films. Variations in the respective temperature ramps of the Tl-oxide zone and the substrate zone can greatly influence resulting film properties such as microstructure, morphology, superconducting transition temperature, and critical current density. copyright 1995 American Institute of Physics

  16. Non-linear effects of initial melt temperatures on microstructures and mechanical properties during quenching process of liquid Cu{sub 46}Zr{sub 54} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Yun-Fei [School of Physics and Microelectronics Science, Hunan University, Changsha, 410082 (China); Liu, Rang-Su, E-mail: liurangsu@sina.com [School of Physics and Microelectronics Science, Hunan University, Changsha, 410082 (China); Tian, Ze-An; Liang, Yong-Chao [School of Physics and Microelectronics Science, Hunan University, Changsha, 410082 (China); Zhang, Hai-Tao [School of Physics and Microelectronics Science, Hunan University, Changsha, 410082 (China); Department of Electronic and Communication Engineering, Changsha University, Changsha 410003 (China); Hou, Zhao-Yang [Department of Applied Physics, Chang’an University, Xi’an 710064 (China); Liu, Hai-Rong [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Zhang, Ai-long [College of Physics and Electronics, Hunan University of Arts and Science, Changde 415000 (China); Zhou, Li-Li [Department of Information Engineering, Gannan Medical University, Ganzhou 341000 (China); Peng, Ping [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Xie, Zhong [School of Physics and Microelectronics Science, Hunan University, Changsha, 410082 (China)

    2015-05-15

    A MD simulation of liquid Cu{sub 46}Zr{sub 54} alloys has been performed for understanding the effects of initial melt temperatures on the microstructural evolution and mechanical properties during quenching process. By using several microstructural analyzing methods, it is found that the icosahedral and defective icosahedral clusters play a key role in the microstructure transition. All the final solidification structures obtained at different initial melt temperatures are of amorphous structures, and their structural and mechanical properties are non-linearly related to the initial melt temperatures, and fluctuated in a certain range. Especially, there exists a best initial melt temperature, from which the glass configuration possesses the highest packing density, the optimal elastic constants, and the smaller extent of structural softening under deforming.

  17. Spectrographic determination of impurities in ammonium bifluoride. III. Study of the processes of vaporization, transport and excitation of the elements Al, B, Cu and Cr

    International Nuclear Information System (INIS)

    Alduan, F. A.; Roca, M.; Capdevila, C.

    1979-01-01

    The influences of the processes of vaporization, transport and excitation on the shape of the volatilization-excitation curves and on the values of the spectral-line intensities have been investigated in a method for the spectrographic determination of Al, B, Cu and Cr In ammonium bifluoride samples by direct current are excitation in Scribner type electrodes, with addition of different matrices (graphite, 63203, GeO 2 , MgO and Zn0). The reaction products in the electrode cavity have been identified by X-ray powder diffraction analysis and the percentages of vaporized and diffused element evaluated through analysis by total-burning spectrographic methods. In addition, the values of both the number of particles entering the discharge column and the transport efficiencies have been calculated. Thus, the origin of most observed differences has been explained. (Author) 11 refs

  18. Impact of optical properties of front glass substrates on Cu(In,Ga)Se{sub 2} solar cells using lift-off process

    Energy Technology Data Exchange (ETDEWEB)

    Tamura, Akihiro, E-mail: ro005080@ed.ritsumei.ac.jp [College of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-0058 (Japan); Abe, Yasuhiro [Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, Kusatsu, Shiga 525-0058 (Japan); Minemoto, Takashi [College of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-0058 (Japan)

    2013-11-01

    Transmittance of a front glass is one of the important factors in the development of high efficiency superstrate-type Cu(In,Ga)Se{sub 2} (CIGS) solar cells. In this study, we investigated the impact of optical properties of the front glass on the solar cell performance of the CIGS solar cells fabricated using the lift-off process. First, optical properties of quartz substrates and soda-lime glass (SLG) substrates with various thicknesses were investigated. Although optical properties of the SLG substrates depend on the thickness, those of the quartz substrates hardly depend on the thickness. Secondly, the superstrate-type CIGS solar cells were fabricated using 1-mm-thick SLG or 1-mm-thick quartz substrates. As a result, the short-circuit current density of the superstrate-type CIGS solar cell with 1-mm-thick quartz substrate was approximately 7% higher than that with 1-mm-thick SLG substrate, and its conversion efficiency was 7.1%. The external quantum efficiency of the solar cells was also improved using the quartz substrate as a front glass because transmittance and absorptance of the quartz substrate were superior to those of the SLG substrate. We therefore conclude that optical properties of the front glasses play an important role in the improvement of the superstrate-type solar cells. - Highlights: • Superstrate type Cu(In,Ga)Se{sub 2} solar cells are fabricated by lift-off process. • Various glasses are used as front glass for lift-off. • The impact of optical properties of the glasses on cell performance is investigated. • Quartz front glass gives 7% higher short-circuit current than soda-lime glass. • High transmittance is desired for front glass.

  19. Dynamics of CO and D{sub 2}O on Cu(111). Laser induced and thermally induced processes Dynamik von CO und D{sub 2}O auf Cu(111); Dynamik von CO und D{sub 2}O auf Cu(111). Laserinduzierte und thermisch induzierte Prozesse

    Energy Technology Data Exchange (ETDEWEB)

    Mehlhorn, M.

    2005-07-15

    molecules in crystalline ice clusters on Cu(111) is investigated as an example for a surfaces reaction induced by electrons from the tunneling tip. Two processes could be separated. The first is the dissociation of single water molecules in the cluster surface by electron attachment. The second process is the dissociation at the interface between dissociated and crystalline regions. This process is also mediated by electron injection into the conduction band. (orig.)

  20. Mapping processing strategies in learning from expository text: an exploratory eye tracking study followed by a cued recall

    OpenAIRE

    Catrysse, Leen; Gijbels, D.; Donche, V.; de Maeyer, Sven; van den Bossche, Piet; Gommers, L.

    2016-01-01

    This study starts from the observation that current empirical research on students' processing strategies in higher education has mainly focused on the use of self-report instruments to measure students' general preferences towards processing strategies. In contrast, there is a rather limited use of more direct and online observation techniques to uncover differences in processing strategies at a task specific level. We based our study on one of the most influential studies in the domain of S...

  1. Optimization and Surface Modification of Al-6351 Alloy Using SiC-Cu Green Compact Electrode by Electro Discharge Coating Process

    Science.gov (United States)

    Chakraborty, Sujoy; Kar, Siddhartha; Dey, Vidyut; Ghosh, Subrata Kumar

    2017-06-01

    This paper introduces the surface modification of Al-6351 alloy by green compact SiC-Cu electrode using electro-discharge coating (EDC) process. A Taguchi L-16 orthogonal array is employed to investigate the process by varying tool parameters like composition and compaction load and electro-discharge machining (EDM) parameters like pulse-on time and peak current. Material deposition rate (MDR), tool wear rate (TWR) and surface roughness (SR) are measured on the coated specimens. An optimum condition is achieved by formulating overall evaluation criteria (OEC), which combines multi-objective task into a single index. The signal-to-noise (S/N) ratio, and the analysis of variance (ANOVA) is employed to investigate the effect of relevant process parameters. A confirmation test is conducted based on optimal process parameters and experimental results are provided to illustrate the effectiveness of this approach. The modified surface is characterized by optical microscope and X-ray diffraction (XRD) analysis. XRD analysis of the deposited layer confirmed the transfer of tool materials to the work surface and formation of inter-metallic phases. The micro-hardness of the resulting composite layer is also measured which is 1.5-3 times more than work material’s one and highest layer thickness (LT) of 83.644μm has been successfully achieved.

  2. Antimony assisted low-temperature processing of CuIn{sub 1-x}Ga{sub x}Se{sub 2-y}S{sub y} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Min, Yuan [IBM T. J. Watson Research Center, P. O. Box 218, Yorktown Heights, NY 10598 (United States); Mitzi, David B., E-mail: dmitzi@us.ibm.co [IBM T. J. Watson Research Center, P. O. Box 218, Yorktown Heights, NY 10598 (United States); Gunawan, Oki [IBM T. J. Watson Research Center, P. O. Box 218, Yorktown Heights, NY 10598 (United States); Kellock, Andrew J [IBM Almaden Research Center, 650 Harry Rd, San Jose, CA 95120 (United States); Chey, S Jay [IBM T. J. Watson Research Center, P. O. Box 218, Yorktown Heights, NY 10598 (United States); Deline, Vaughn R [IBM Almaden Research Center, 650 Harry Rd, San Jose, CA 95120 (United States)

    2010-11-01

    Application of the Sb-doping method to low-temperature ({<=} 400 {sup o}C) processing of CuIn{sub 1-x}Ga{sub x}Se{sub 2-y}S{sub y} (CIGS) solar cells is explored, using a hydrazine-based approach to deposit the absorber films. Power conversion efficiencies of 10.5% and 8.4% have been achieved for CIGS devices (0.45 cm{sup 2} device area) processed at 400 {sup o}C and 360 {sup o}C, respectively, with an Sb-incorporation level at 1.2 mol % (relative to the moles of CIGS). Significant Sb-induced grain size enhancement was confirmed for these low processing temperatures using cross-sectional scanning electron microscopy, and an average 2-3% absolute efficiency improvement was achieved in Sb-doped samples compared to their Sb-free sister samples. With Sb inclusion, the CIGS film grain growth temperature is lowered to well below 450 {sup o}C, a range compatible with flexible polymer substrate materials such as polyimide. This method opens up access to opportunities in low-temperature processing of CIGS solar cells, an area that is being actively pursued using both traditional vacuum-based as well as other solution-based deposition techniques.

  3. Antimony assisted low-temperature processing of CuIn1-xGaxSe2-ySy solar cells

    International Nuclear Information System (INIS)

    Yuan Min; Mitzi, David B.; Gunawan, Oki; Kellock, Andrew J.; Chey, S. Jay; Deline, Vaughn R.

    2010-01-01

    Application of the Sb-doping method to low-temperature (≤ 400 o C) processing of CuIn 1-x Ga x Se 2-y S y (CIGS) solar cells is explored, using a hydrazine-based approach to deposit the absorber films. Power conversion efficiencies of 10.5% and 8.4% have been achieved for CIGS devices (0.45 cm 2 device area) processed at 400 o C and 360 o C, respectively, with an Sb-incorporation level at 1.2 mol % (relative to the moles of CIGS). Significant Sb-induced grain size enhancement was confirmed for these low processing temperatures using cross-sectional scanning electron microscopy, and an average 2-3% absolute efficiency improvement was achieved in Sb-doped samples compared to their Sb-free sister samples. With Sb inclusion, the CIGS film grain growth temperature is lowered to well below 450 o C, a range compatible with flexible polymer substrate materials such as polyimide. This method opens up access to opportunities in low-temperature processing of CIGS solar cells, an area that is being actively pursued using both traditional vacuum-based as well as other solution-based deposition techniques.

  4. Microstructure of shear-induced thixoformed Al- 4.5Cu-1.5Mg alloy via RAP and SSTT processes

    Directory of Open Access Journals (Sweden)

    Siamak Nikzad

    2017-07-01

    Full Text Available In this research, the effect of the thixoforming temperature on the microstructure and mechanical properties was investigated in the thixoforming of the feedstock produced by the RAP (recrystallization and partial melting and SSTT (semi-solid thermal transformation processes for Al-4.5Cu-1.5Mg alloy. In the RAP process, the percentage reduction in area was approximately 35%. Thixoforming was done at 610, 620, and 630 °C. Globular microstructure was observed at all temperatures and conditions. The minimum average globule size was 39 μm, and it was obtained in the thixoforming of the feedstock produced by the RAP process in the section of 4 mm in diameter at 620 ° C after applying shear. Its corresponding compressive strength was -877.44 MPa. The maximum average globule size was 136 μm, and it was obtained in the thixoforming of the feedstock produced by the SSTT process in the section of 10 mm in diameter at 630 °C before applying shear. Its corresponding compressive strength was -769.18 MPa. The finest and most spherical globules, as well as the highest compressive strength were obtained at 620 °C in both RAP and SSTT states.

  5. Wavelength dependence in laser floating zone processing. A case study with Bi-Sr-Ca-Cu-O superconductors

    International Nuclear Information System (INIS)

    Fuente, G.F. de la; Diez, J.C.; Angurel, L.A.; Pena, J.I.; Sotelo, A.; Navarro, R.

    1995-01-01

    Laser floating zone processing methods are particularly suitable for studying crystal growth and the development of texture from the melt in many materials used in electrooptics, for example. A system is described that allows different laser wavelengths to be used, and first results on BSCCO superconducting fibers processed using different lasers are presented. (orig.)

  6. Mapping processing strategies in learning from expository text: an exploratory eye tracking study followed by a cued recall

    NARCIS (Netherlands)

    Catrysse, Leen; Gijbels, D.; Donche, V.; de Maeyer, Sven; van den Bossche, Piet; Gommers, L.

    2016-01-01

    This study starts from the observation that current empirical research on students' processing strategies in higher education has mainly focused on the use of self-report instruments to measure students' general preferences towards processing strategies. In contrast, there is a rather limited use of

  7. Mapping Processing Strategies in Learning from Expository Text: An Exploratory Eye Tracking Study Followed by a Cued Recall

    Science.gov (United States)

    Catrysse, Leen; Gijbels, David; Donche, Vincent; De Maeyer, Sven; Van den Bossche, Piet; Gommers, Luci

    2016-01-01

    This study starts from the observation that current empirical research on students' processing strategies in higher education has mainly focused on the use of self-report instruments to measure students' general preferences towards processing strategies. In contrast, there is a rather limited use of more direct and online observation techniques to…

  8. Scanning and Deep Processing of Information in Hypertext: An Eye Tracking and Cued Retrospective Think-Aloud Study

    Science.gov (United States)

    Salmerón, L.; Naumann, J.; García, V.; Fajardo, I.

    2017-01-01

    When students solve problems on the Internet, they have to find a balance between quickly scanning large sections of information in web pages and deeply processing those that are relevant for the task. We studied how high school students articulate scanning and deeper processing of information while answering questions using a Wikipedia document,…

  9. Rapid processing method for solution deposited YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dawley, J.T.; Clem, P.G.; Boyle, T.J.; Ottley, L.M.; Overmyer, D.L.; Siegal, M.P

    2004-02-01

    YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) films, deposited on buffered metal substrates, are the primary candidate for second-generation superconducting (SC) wires, with applications including expanded power grid transmission capability, compact motors, and enhanced sensitivity magnetic resonance imaging. Feasibility of manufacturing such superconducting wires is dependent on high processing speed, often a limitation of vapor and solution-based YBCO deposition processes. In this work, YBCO films were fabricated via a new diethanolamine-modified trifluoroacetic film solution deposition method. Modifying the copper chemistry of the YBCO precursor solution with diethanolamine enables a hundredfold decrease in the organic pyrolysis time required for MA/cm{sup 2} current density (J{sub c}) YBCO films, from multiple hours to {approx}20 s in atmospheric pressure air. High quality, {approx}0.2 {mu}m thick YBCO films with J{sub c} (77 K) values {>=}2 MA/cm{sup 2} at 77 K are routinely crystallized from these rapidly pyrolyzed films deposited on LaAlO{sub 3}. This process has also enabled J{sub c} (77 K)=1.1 MA/cm{sup 2} YBCO films via 90 m/h dip-coating on Oak Ridge National Laboratory RABiTS textured metal tape substrates. This new YBCO solution deposition method suggests a route toward inexpensive and commercializable {approx}$10/kA m solution deposited YBCO coated conductor wires.

  10. A Comprehensive Study of One-Step Selenization Process for Cu(In1-x Ga x )Se2 Thin Film Solar Cells.

    Science.gov (United States)

    Chen, Shih-Chen; Wang, Sheng-Wen; Kuo, Shou-Yi; Juang, Jenh-Yih; Lee, Po-Tsung; Luo, Chih Wei; Wu, Kaung-Hsiung; Kuo, Hao-Chung

    2017-12-01

    In this work, aiming at developing a rapid and environmental-friendly process for fabricating CuIn 1-x Ga x Se 2 (CIGS) solar cells, we demonstrated the one-step selenization process by using selenium vapor as the atmospheric gas instead of the commonly used H 2 Se gas. The photoluminescence (PL) characteristics indicate that there exists an optimal location with superior crystalline quality in the CIGS thin films obtained by one-step selenization. The energy dispersive spectroscopy (EDS) reveals that the Ga lateral distribution in the one-step selenized CIGS thin film is intimately correlated to the blue-shifted PL spectra. The surface morphologies examined by scanning electron microscope (SEM) further suggested that voids and binary phase commonly existing in CIGS films could be successfully eliminated by the present one-step selenization process. The agglomeration phenomenon attributable to the formation of MoSe 2 layer was also observed. Due to the significant microstructural improvement, the current-voltage (J-V) characteristics and external quantum efficiency (EQE) of the devices made of the present CIGS films have exhibited the remarkable carrier transportation characteristics and photon utilization at the optimal location, resulting in a high conversion efficiency of 11.28%. Correlations between the defect states and device performance of the one-step selenized CIGS thin film were convincingly delineated by femtosecond pump-probe spectroscopy.

  11. Enhancement of the photo conversion efficiencies in Cu(In,Ga)(Se,S){sub 2} solar cells fabricated by two-step sulfurization process

    Energy Technology Data Exchange (ETDEWEB)

    Yang, JungYup; Nam, Junggyu; Kim, Dongseop; Lee, Dongho, E-mail: dhlee0333@gmail.com, E-mail: ddang@korea.ac.kr [Photovoltaic Development Team, Energy Storage Business Division, Samsung SDI, Cheonan-si 331-300 (Korea, Republic of); Kim, GeeYeong; Jo, William [Department of Physics and New and Renewable Energy Research Center, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Kang, Yoonmook, E-mail: dhlee0333@gmail.com, E-mail: ddang@korea.ac.kr [KUKIST Green School, Graduate School of Energy and Environment, Korea University, Seoul 136-701 (Korea, Republic of)

    2015-11-09

    Cu(In,Ga)(Se,S){sub 2} (CIGSS) absorber layers were fabricated by using a modified two-stage sputter and a sequential selenization/sulfurization method, and the sulfurization process is changed from one-step to two-step. The two-step sulfurization was controlled with two different H{sub 2}S gas concentrations during the sulfurization treatment. This two-step process yielded remarkable improvements in the efficiency (+0.7%), open circuit voltage (+14 mV), short circuit current (+0.23 mA/cm{sup 2}), and fill factor (+0.21%) of a CIGSS device with 30 × 30 cm{sup 2} in size, owing to the good passivation at the grain boundary surface, uniform material composition among the grain boundaries, and modified depth profile of Ga and S. The deterioration of the P/N junction quality was prevented by the optimized S content in the CIGSS absorber layer. The effects of the passivation quality at the grain boundary surface, the material uniformity, the compositional depth profiles, the microstructure, and the electrical characteristics were examined by Kelvin probe force microscopy, X-ray diffraction, secondary ion mass spectrometry, scanning electron microscopy, and current-voltage curves, respectively. The two-step sulfurization process is experimentally found to be useful for obtaining good surface conditions and, enhancing the efficiency, for the mass production of large CIGSS modules.

  12. Enhanced Carrier Collection from CdS Passivated Grains in Solution-Processed Cu2ZnSn(S,Se)4 Solar Cells.

    Science.gov (United States)

    Werner, Melanie; Keller, Debora; Haass, Stefan G; Gretener, Christina; Bissig, Benjamin; Fuchs, Peter; La Mattina, Fabio; Erni, Rolf; Romanyuk, Yaroslav E; Tiwari, Ayodhya N

    2015-06-10

    Solution processing of Cu2ZnSn(S,Se)4 (CZTSSe)-kesterite solar cells is attractive because of easy manufacturing using readily available metal salts. The solution-processed CZTSSe absorbers, however, often suffer from poor morphology with a bilayer structure, exhibiting a dense top crust and a porous bottom layer, albeit yielding efficiencies of over 10%. To understand whether the cell performance is limited by this porous layer, a systematic compositional study using (scanning) transmission electron microscopy ((S)TEM) and energy-dispersive X-ray spectroscopy of the dimethyl sulfoxide processed CZTSSe absorbers is presented. TEM investigation revealed a thin layer of CdS that is formed around the small CZTSSe grains in the porous bottom layer during the chemical bath deposition step. This CdS passivation is found to be beneficial for the cell performance as it increases the carrier collection and facilitates the electron transport. Electron-beam-induced current measurements reveal an enhanced carrier collection for this buried region as compared to reference cells with evaporated CdS.

  13. Physical mechanisms of Cu-Cu wafer bonding

    International Nuclear Information System (INIS)

    Rebhan, B.

    2014-01-01

    Modern manufacturing processes of complex integrated semiconductor devices are based on wafer-level manufacturing of components which are subsequently interconnected. When compared with classical monolithic bi-dimensional integrated circuits (2D ICs), the new approach of three-dimensional integrated circuits (3D ICs) exhibits significant benefits in terms of signal propagation delay and power consumption due to the reduced metal interconnection length and allows high integration levels with reduced form factor. Metal thermo-compression bonding is a process suitable for 3D interconnects applications at wafer level, which facilitates the electrical and mechanical connection of two wafers even processed in different technologies, such as complementary metal oxide semiconductor (CMOS) and microelectromechanical systems (MEMS). Due to its high electrical conductivity, copper is a very attractive material for electrical interconnects. For Cu-Cu wafer bonding the process requires typically bonding for around 1 h at 400°C and high contact pressure applied during bonding. Temperature reduction below such values is required in order to solve issues regarding (i) throughput in the wafer bonder, (ii) wafer-to-wafer misalignment after bonding and (iii) to minimise thermo-mechanical stresses or device degradation. The aim of this work was to study the physical mechanisms of Cu-Cu bonding and based on this study to further optimise the bonding process for low temperatures. The critical sample parameters (roughness, oxide, crystallinity) were identified using selected analytical techniques and correlated with the characteristics of the bonded Cu-Cu interfaces. Based on the results of this study the impact of several materials and process specifications on the bonding result were theoretically defined and experimentally proven. These fundamental findings subsequently facilitated low temperature (LT) metal thermo-compression Cu-Cu wafer bonding and even room temperature direct

  14. Cu/Cu2O/CuO nanoparticles: Novel synthesis by exploding wire technique and extensive characterization

    Science.gov (United States)

    Sahai, Anshuman; Goswami, Navendu; Kaushik, S. D.; Tripathi, Shilpa

    2016-12-01

    In this article, we explore potential of Exploding Wire Technique (EWT) to synthesize the copper nanoparticles using the copper metal in a plate and wire geometry. Rietveld refinement of X-ray diffraction (XRD) pattern of prepared material indicates presence of mixed phases of copper (Cu) and copper oxide (Cu2O). Agglomerates of copper and copper oxide comprised of ∼20 nm average size nanoparticles observed through high resolution transmission electron microscope (HRTEM) and energy dispersive x-ray (EDX) spectroscopy. Micro-Raman (μR) and Fourier transform infrared (FTIR) spectroscopies of prepared nanoparticles reveal existence of additional minority CuO phase, not determined earlier through XRD and TEM analysis. μR investigations vividly reveal cubic Cu2O and monoclinic CuO phases based on the difference of space group symmetries. In good agreement with μRaman analysis, FTIR stretching modes corresponding to Cu2-O and Cu-O were also distinguished. Investigations of μR and FTIR vibrational modes are in accordance and affirm concurrence of CuO phases besides predominant Cu and Cu2O phase. Quantum confinement effects along with increase of band gaps for direct and indirect optical transitions of Cu/Cu2O/CuO nanoparticles are reflected through UV-vis (UV-vis) spectroscopy. Photoluminescence (PL) spectroscopy spots the electronic levels of each phase and optical transitions processes occurring therein. Iterative X-ray photoelectron spectroscopy (XPS) fitting of core level spectra of Cu (2p3/2) and O (1s), divulges presence of Cu2+ and Cu+ in the lattice with an interesting evidence of O deficiency in the lattice structure and surface adsorption. Magnetic analysis illustrates that the prepared nanomaterial demonstrates ferromagnetic behaviour at room temperature.

  15. Cu-Cr Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Need, Ryan F. [Los Alamos National Laboratory

    2012-08-09

    Cu-Cr alloys are part of a class of face-centered cubic (FCC)-body-centered cubic (BCC) composites that includes similar alloys, such as Cu-Nb and Cu-Ta. When heavily deformed, these FCC-BCC materials create 'in situ' composites with a characteristic structure-nanoscale BCC filaments in a ductile FCC matrix. The strength of these composites is vastly greater than predicted by the rule of mixtures, and has been shown to be inversely proportional to the filament spacing. Lower raw materials costs suggest that Cu-Cr alloys may offer more economical solution to high-strength, high-conductivity wire than either their Nb or Ta counterparts. However, Cr is also more brittle and soluble in Cu than Nb or Ta. These qualities necessitate thermal treatments to remove solute atoms from the Cu matrix, improve conductivity, and maintain the ductility of the Cr filaments. Through the use of different thermomechanical processing routes or the addition of select dopants, alloys with strength in excess of 1 GPa at 70% IACS have been achieved. To date, previous research on Cu-Cr alloys has focused on a relatively small number of alloy compositions and processing methods while the effects of dopants and ageing treatments have only been studied independently. Consequently, there remains considerable opportunity for the development and optimization of these alloys as a leading high-strength, high-conductivity material.

  16. Fabrication of Cu{sub 2}ZnSn(S{sub x}Se{sub 1−x}){sub 4} solar cells by ethanol-ammonium solution process

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Cong; Li, Jianmin; Wang, Yaguang; Jiang, Guoshun; Weifeng, Liu, E-mail: liuwf@ustc.edu.cn; Zhu, Changfei, E-mail: cfzhu@ustc.edu.cn

    2016-10-15

    Highlights: • The CBD precipitates were utilized to fabricate the CZTS/CZTSSe solar cells. • A solvent mixture of ethanol and ammonium hydroxide was used to form SnS-Cu2O-ZnS slurry. • Formation of CZTS/CZTSSe with good crystalline quality confirmed by XRD and Raman spectra. • CZTS and CZTSSe thin film solar cells obtained the best PCE of 1.99% and 2.95%, respectively. - Abstract: In this paper, Cu{sub 2}ZnSn(S{sub x}Se{sub 1−x}){sub 4} precursor films were produced by doctor blade process from SnS-Cu{sub 2}O-ZnS slurry. To prepare the slurry, SnS, ZnS and Cu{sub 2}O precipitates, which are outgrowths of stacked layer ZnS/Cu/SnS by CBD (chemical bath deposition)-annealing route, were dissolved in the mixture solvent of ethanol and NH{sub 3}·H{sub 2}O. Synthesized precursor films were then annealed at different conditions. The post-annealed films were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman measurements and UV–vis–NIR spectroscopy. SEM studies reveal that the rough and relatively compact absorber thin films are obtained via the sulfidation and sulfidation-selenization processes. X-ray diffraction and Raman spectrum results verify that the obtained films are composed of Cu{sub 2}ZnSnS{sub 4} and Cu{sub 2}ZnSnSe{sub 4} phases, which have high absorbance in visible range and direct band gap energy of 1.01–1.47 eV. The best devices yield total area power conversion efficiency of 1.99% and 2.95% corresponding to Cu{sub 2}ZnSnS{sub 4} and Cu{sub 2}ZnSn(S{sub x}Se{sub 1−x}){sub 4} thin film solar cells under AM1.5 illumination without any anti-reflection layer.

  17. TPD IR studies of CO desorption from zeolites CuY and CuX

    Science.gov (United States)

    Datka, Jerzy; Kozyra, Paweł

    2005-06-01

    The desorption of CO from zeolites CuY and CuX was followed by TPD-IR method. This is a combination of temperature programmed desorption and IR spectroscopy. In this method, the status of activated zeolite (before adsorption), the process of adsorption, and the status of adsorbed molecules can be followed by IR spectroscopy, and the process of desorption (with linear temperature increase) can be followed both by IR spectroscopy and by mass spectrometry. IR spectra have shown two kinds of Cu + sites in both CuY and CuX. Low frequency (l.f.) band (2140 cm -1 in CuY and 2130 cm -1 in CuX) of adsorbed CO represents Cu + sites for which π back donation is stronger and σ donation is weaker whereas high frequency h.f. band (2160 cm -1 in CuY and 2155 cm -1 in CuX) represent Cu + sites for which π back donation is weaker and σ donation is stronger. The TPD-IR experiments evidenced that the Cu + sites represented by l.f. band bond CO more weakly than those represented by h.f. one, indicating that σ donation has more important impact to the strength of Cu +-CO bonding. On the contrary, π back donation has bigger contribution to the activation of adsorbed molecules.

  18. Fabrication of High-Quality SmBa2Cu3O7-δ Thin Films by a Modified TFA-MOD Process

    International Nuclear Information System (INIS)

    Kim, Duck Jin; Moon, Seung Hyun; Park, Chan; Yoo, Sang Im; Song, Kyu Jeong

    2005-01-01

    We report a successful fabrication of high-quality SmBa 2 Cu 3 O 7-δ (SmBCO) thin films on LaAlO 3 (LAO)(100) single crystalline substrates by a modified TFA-MOD method. After the pyrolysis heat treatment of spin-coated films up to 400 degree C, SmBCO films were fired at various temperatures ranging from 810 to 850 degree C in a reduced oxygen atmosphere (10 ppm O 2 in Ar). Optimally processed SmBCO films exhibited the zero-resistance temperature (T c ,zero) of 90.2 K and the critical current density (J c ) of 0.8 MA/cm 2 at 77K in self-field. Compared with the J c values (normally, > 2 MA/cm 2 at 77 K) of MOD-TFA processed YBCO films, rather depressed J c values in SmBCO films are most probably attributed to the existence of alpha-axis oriented grains.

  19. Improved performance of low cost CuInS2 superstrate-type solar cells using Zinc assisted spray pyrolysis processing

    Science.gov (United States)

    Cheshme Khavar, Amir Hossein; Mahjoub, Ali Reza; Taghavinia, Nima

    2017-12-01

    Superstrate configuration CuInS2 (CIS) solar cells are fabricated using a spray pyrolysis method. We avoided selenization process, cyanide etching and CdS buffer layer, to keep the process ‘green’. CIS layers are formed by spray pyrolysis of an aqueous precursor ink containing metal chloride salts and thiourea at 350 °C. We investigated the effect of intentional Zn doping on structural, morphological and photovoltaic response of the fabricated CIS films by dissolving ZnCl2 in aqueous precursor solution. At a zinc doping level ranging between 0.25 and 1.00 mol%, Zn doping is found to improve the CIS crystal growth and surface morphology of CIS films. Compared with the performance of the non-doped CIS cell, the Zn-doped CIS solar cell displayed a remarkable efficiency enhancement of 58-97% and the maximum enhancement was obtained at a Zn content of 0.5 mol%. The device structure consists of    and show promising PCE of 4.29 % without any anti-reflection coating. Over the course of 300 d under ambient condition, the fabricated device showed only 1% loss in efficiency.

  20. Fabrication of Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSSe) absorber films based on solid-phase synthesis and blade coating processes

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ruixin, E-mail: mrx_601@126.com [School of Metallurgy and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Laboratory of Special Melting and Preparation of High-end Metal Materials, Beijing 100083 (China); Yang, Fan; Li, Shina; Zhang, Xiaoyong; Li, Xiang; Cheng, Shiyao; Liu, Zilin [School of Metallurgy and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2016-04-15

    Graphical abstract: - Highlights: • Pure CZTS nano-crystalline have been prepared based on solid-phase synthesis. • A simple and modified doctor blade process followed by a selenization technique was utilized to fabricate CZTSSe absorber films. • Comparative studies on the properties of CZTS and CZTSSe absorber films have been investigated. • The band gap of CZTSSe absorber films was determined to be 1.26 eV. - Abstract: CZTSSe is an important earth abundant collection of materials for the development of low cost and high efficiency thin film solar cells. This work developed a simple non-vacuum-based route to fabricate CZTSSe absorber films. This was demonstrated by first synthesizing Cu{sub 2}ZnSnS{sub 4} (CZTS) nano-crystalline based on solid-phase synthesis. Then a stable colloidal ink composed of CZTS nano-crystalline was blade coated on Mo-coated substrates followed by an annealing process under Ar atmosphere. After CZTS films formation, the films were sintered into CZTSSe absorber films by exposing them under Selenium vapor. The formation of a kesterite type CZTS was confirmed using X-ray diffraction and Raman scattering measurements. The band gap of CZTSSe absorber films was determined to be 1.26 eV, which was appropriate for use as an absorber layer in thin film solar cells. The CZTSSe absorber films showed a good photovoltatic performance, demonstrating this simple approach had great potential for CZTSSe solar cell production.

  1. Effect of milling duration on the evolution of shape memory properties in a powder processed Cu-Al-Ni-Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mohit; Gupta, Gaurav K.; Shafeeq, Muhamed M.; Modi, Om P.; Prasad, Braj K. [CSIR - Advanced Materials and Processes Research Institute, Bhopal (India)

    2013-09-15

    The present work describes the effect of milling duration on the properties of a powder metallurgy processed Cu-Al-Ni-Ti shape memory alloy employing mechanical alloying. Powder mixtures milled for different durations were sintered in order to investigate the formation of solid solution and evolution of martensitic structure. The idea was to optimize the duration of milling (mechanical alloying) to obtain chemical homogeneity as well as shape memory properties in the processed material without undergoing extensive post homogenization treatment. The martensitic structure was noted to evolve in the powder mix milled for at least 16 hrs, whereas complete transformation to martensite occurred after milling for 40 hrs. Interestingly, the dissolution of alloying elements (to form the {beta} phase prior to the formation of martensite) was noted to complete partially only during mechanical alloying for 40 hrs and remaining during subsequent sintering for 1 hr. The hot pressed compacts of the powders milled for 40 hrs were chemically homogeneous and consisted of fully martensite phase, which is essential for the realization of shape memory properties. They also revealed almost 100% shape recovery at the applied pre-strain levels of 1 and 2%. (orig.)

  2. Cu(In,Ga)Se{sub 2} absorber thinning and the homo-interface model: Influence of Mo back contact and 3-stage process on device characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, E.; Arzel, L.; Tomassini, M.; Barreau, N., E-mail: nicolas.barreau@univ-nantes.fr [Institut des Matériaux Jean Rouxel (IMN)-UMR 6502, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France); Zabierowski, P. [Faculty of Physics, Warsaw University of Technology, Koszykowa 75, PL 00-662 Warsaw (Poland); Fuertes Marrón, D. [Instituto de Energía Solar–ETSIT, Technical University of Madrid, Ciudad Universitaria s.n., 28040 Madrid (Spain)

    2014-08-21

    Thinning the absorber layer is one of the possibilities envisaged to further decrease the production costs of Cu(In,Ga)Se{sub 2} (CIGSe) thin films solar cell technology. In the present study, the electronic transport in submicron CIGSe-based devices has been investigated and compared to that of standard devices. It is observed that when the absorber is around 0.5 μm-thick, tunnelling enhanced interface recombination dominates, which harms cells energy conversion efficiency. It is also shown that by varying either the properties of the Mo back contact or the characteristics of 3-stage growth processing, one can shift the dominating recombination mechanism from interface to space charge region and thereby improve the cells efficiency. Discussions on these experimental facts led to the conclusions that 3-stage process implies the formation of a CIGSe/CIGSe homo-interface, whose location as well as properties rule the device operation; its influence is enhanced in submicron CIGSe based solar cells.

  3. Processing of Bi2.1Sr1.8Ca1.1Cu2O8 source material for float-zone fiber growth

    International Nuclear Information System (INIS)

    Peszkin, P.N.; Raymakers, R.J.; Feigelson, R.S.; Moulton, L.V.; Lu, Z.

    1991-01-01

    Bi 2.1 Sr 1.8 Ca 1.1 Cu 2 O 8 fibers having excellent superconducting properties can be grown by a laser-heated float zone process. In order to maintain stable growth conditions and thereby obtain fibers free of diameter fluctuations and voids, dense ceramic starting material containing only the 2212 phase is required. In this study various processing parameters, including calcining and sintering temperatures and times, grain size of the powders used, and pressing pressures were optimized to yield dense, chemically homogeneous starting material. It was found that under most conditions there was no increase in the density on sintering. Retrograde densification was the usual situation except at higher pressures and was found to depend on pressing pressure, calcination history, and sintering temperature. Cold-pressing at higher pressures (100 000 psi) yielded denser but chemically inhomogeneous material. Ceramic samples sintered for long times (>48 h) yielded source rods that produced instabilities during fiber growth, presumably due to preferential loss of mass during sintering

  4. Influence of Sr, Fe and Mn content and casting process on the microstructures and mechanical properties of AlSi7Cu3 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zaidao [Laboratoire de Mécanique de Lille (LML), FRE 3723, Ecole Centrale de Lille, 59651 Villeneuve d' Ascq (France); Unité Matériaux et Transformations, UMR CNRS 8207, Univ. Lille 1, 59655 Villeneuve d' Ascq (France); Limodin, Nathalie; Tandjaoui, Amina; Quaegebeur, Philippe [Laboratoire de Mécanique de Lille (LML), FRE 3723, Ecole Centrale de Lille, 59651 Villeneuve d' Ascq (France); Osmond, Pierre [PSA Peugeot Citröen, Direction de la Recherche et de l' Innovation Automobile, Route de Gisy-78943, Vélizy-Villacoublay Cedex (France); Balloy, David [Unité Matériaux et Transformations, UMR CNRS 8207, Univ. Lille 1, 59655 Villeneuve d' Ascq (France)

    2017-03-24

    The effects of Strontium (Sr), Iron (Fe) and Manganese (Mn) additions, casting process (i.e., cooling rate) on the microstructures and mechanical properties of AlSi7Cu3 alloy were investigated. 2D and 3D metallographic and image analysis have been performed to measure the microstructural changes occurring at different Sr, Fe and Mn levels and casting process. The evolution of mechanical properties of the alloys has been monitored by Brinell and Vickers hardness measurement and tensile tests. Addition of Sr slightly refines the eutectic silicon particles but it also introduces more pores. The combined addition of Fe and Mn induces an increase of Fe-rich intermetallic compounds which include both α-Al{sub 15}(Fe,Mn){sub 3}Si{sub 2} and β-Al{sub 5}FeSi phase, while the volume fraction of porosity decreases with the Fe and Mn content increase. The secondary dendrite arm spacing slightly decreases with the addition of Sr, Fe and Mn alloying elements.

  5. Effect of Thermomechanical Processing on Microstructure, Texture Evolution, and Mechanical Properties of Al-Mg-Si-Cu Alloys with Different Zn Contents

    Science.gov (United States)

    Wang, X. F.; Guo, M. X.; Chen, Y.; Zhu, J.; Zhang, J. S.; Zhuang, L. Z.

    2017-07-01

    The effect of thermomechanical processing on microstructure, texture evolution, and mechanical properties of Al-Mg-Si-Cu alloys with different Zn contents was studied by mechanical properties, microstructure, and texture characterization in the present study. The results show that thermomechanical processing has a significant influence on the evolution of microstructure and texture and on the final mechanical properties, independently of Zn contents. Compared with the T4P-treated (first preaged at 353 K (80 °C) for 12 hours and then naturally aged for 14 days) sheets with high final cold rolling reduction, the T4P-treated sheets with low final cold rolling reduction possess almost identical strength and elongation and higher average r values. Compared with the intermediate annealed sheets with high final cold rolling reduction, the intermediate annealed sheets with low final cold rolling reduction contain a higher number of particles with a smaller size. After solution treatment, in contrast to the sheets with high final cold rolling reduction, the sheets with low final cold rolling reduction possess finer grain structure and tend to form a weaker recrystallization texture. The recrystallization texture may be affected by particle distribution, grain size, and final cold rolling texture. Finally, the visco-plastic self-consistent (VPSC) model was used to predict r values.

  6. Cu-62, Cu-64 and Cu-66 production with 4.2 MeV deuterons

    International Nuclear Information System (INIS)

    Avila, Mario; Morales, J.R.; Riquelme, H.O.

    1996-01-01

    Full text: The natural copper irradiation with deuterons produces the Cu-62, Cu-64 and Cu-66 radionuclides. Of two radioisotopes, those with deficiencies in neutrons, are applied in nuclear medicine diagnostic processes, mainly for the nuclear characteristic of the decay modes. The positron emitters, of short life mean Cu-62 (9.1 min, β + ) and Cu(12.7 h), are radionuclides applied in radio pharmacological preparation for brain, core, blood flux studies. The radiochemical process consists in the de solution of the irradiated metallic copper target, in acid medium. The result solution, can be neutralized with a base or a buffer at wished pH. Using a deuteron beam of 4,2 ± 0,1 MeV energy has been obtained total yields of 1,103 ± 0,011 μCl/μAh medium for 62 Cu and of 0,148 ± 0,015 μCl/μAh for 64 Cu

  7. Literature review on the properties of cuprous oxide Cu{sub 2}O and the process of copper oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Korzhavyi, P. A.; Johansson, B. (Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm (Sweden))

    2011-10-15

    The purpose of the present review is to provide a reference guide to the most recent data on the properties of copper(I) oxide as well as on the atomic processes involved in the initial stages of oxidation of copper. The data on the structure of surfaces, as obtained from atomic-resolution microscopy studies (for example, STM) or from first-principles calculations, are reviewed. Information of this kind may be useful for understanding the atomic mechanisms of corrosion and stress-corrosion cracking of copper

  8. Laboratory scale electroplating and processing of long lengths of an in situ Cu-Nb3Sn superconductors

    International Nuclear Information System (INIS)

    LeHuy, H.; Germain, L.; Roberge, R.; Foner, S.; Massachusetts Inst. of Tech., Cambridge

    1984-01-01

    A laboratory scale continuous tin electroplating system is described and used to evaluate the effect of various parameters of the alkaline and acid baths plating process. Tin electroplating is shown to be simple and reliable. With an 8 m immersion length production speeds of the order of 1 m min -1 are possible in an alkaline bath at 80degC. An acid bath gives satisfactory tinning deposits with a production speed of up to 3 m min -1 at room temperature. (author)

  9. Literature review on the properties of cuprous oxide Cu2O and the process of copper oxidation

    International Nuclear Information System (INIS)

    Korzhavyi, P. A.; Johansson, B.

    2011-10-01

    The purpose of the present review is to provide a reference guide to the most recent data on the properties of copper(I) oxide as well as on the atomic processes involved in the initial stages of oxidation of copper. The data on the structure of surfaces, as obtained from atomic-resolution microscopy studies (for example, STM) or from first-principles calculations, are reviewed. Information of this kind may be useful for understanding the atomic mechanisms of corrosion and stress-corrosion cracking of copper

  10. Properties of the ablation process for excimer laser ablation of Y1Ba2Cu3O7

    International Nuclear Information System (INIS)

    Neifeld, R.A.; Potenziani, E.; Sinclair, W.R.; Hill III, W.T.; Turner, B.; Pinkas, A.

    1991-01-01

    The process of excimer laser ablation has been studied while varying the laser fluence from 0.237 to 19.1 J/cm 2 . Ion time-of-flight, total charge, target etch depth per pulse, and etch volume per pulse have been measured. Results indicate a maximum ablation volume and minimum ionization fraction occur near 5 J/cm 2 . Several of the parameters measured vary rapidly in the 1--5 J/cm 2 range. Variation in these parameters strongly influences the properties of films grown by this technique

  11. Application of Zr/Ti-Pic in the adsorption process of Cu(II), Co(II) and Ni(II) using adsorption physico-chemical models and thermodynamics of the process; Aplicacao de Zr/Ti-PILC no processo de adsorcao de Cu(II), Co(II) e Ni(II) utilizando modelos fisico-quimicos de adsorcao e termodinamica do processo

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, Denis Lima; Airoldi, Claudio [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Quimica. Dept. de Quimica Inorganica]. E-mail: dlguerra@iqm.unicamp.br; Lemos, Vanda Porpino; Angelica, Romulo Simoes [Universidade Federal do Para (UFPa), Belem (Brazil); Viana, Rubia Ribeiro [Universidade Federal do Mato Grosso (UFMT), Cuiaba (Brazil). Inst. de Ciencias Exatas e da Terra. Dept. de Recursos Minerais

    2008-07-01

    The aim of this investigation is to study how Zr/Ti-Pic adsorbs metals. The physico-chemical proprieties of Zr/Ti-Pic have been optimized with pillarization processes and Cu(II), Ni(II) and Co(II) adsorption from aqueous solution has been carried out, with maximum adsorption values of 8.85, 8.30 and 7.78 x-1 mmol g{sup -1}, respectively. The Langmuir, Freundlich and Temkin adsorption isotherm models have been applied to fit the experimental data with a linear regression process. The energetic effect caused by metal interaction was determined through calorimetric titration at the solid-liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant. (author)

  12. Comparison in processing routes by copper mold casting injection and suction in the Cu{sub 46}Zr{sub 42}Al{sub 7}Y{sub 5} vitreous alloy; Comparacao entre as rotas de processamento por fundicao com injecao e com succao da liga vitrea Cu{sub 46}Zr{sub 42}Al{sub 7}Y{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Batalha, W.; Aliaga, L.C.R.; Bolfarini, C.; Botta, W.J.; Kiminami, C.S. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

    2014-07-01

    To expand the application of glassy metals, the development of processing routes and compositions that allow the production of parts with dimensions of millimeters or even centimeters, is very important. The present work aims the contribution to the technological development of processing routes for the production of Cu-based bulk metallic glasses. Wedge-shaped samples of Cu{sub 46}Zr{sub 42}Al{sub 7}Y{sub 5} (atom percent) chemical composition were processed using copper mold casting by suction and injection. Characterization was made combining scanning electron microscopy, x-ray diffraction and differential scanning calorimetry. The critical amorphous thickness obtained by those two different routes was carefully observed. The suction route allow obtaining the best results with critical amorphous thickness about 8 mm. This result was analyzed considering the different extrinsic parameters to the glass forming ability of the alloy. (author)

  13. Effect of processing parameters on Cu-Co-Fe-based diamond impregnated metal matrix composite for stone cutting

    International Nuclear Information System (INIS)

    Mawani, K.; Shahid, M.; Arshad, S.N.; Hasaini, M.H.; Khan, B.S.

    2005-01-01

    Diamond Impregnated Metal Matrix Composites (DIMMC), manufactured by powder metallurgy route, playa major role in stone cutting tool industry. Unfortunately, these diamond tools are not manufactured locally. Our industry relies heavily on the import of these diamond tools to meet the local demand. This study was undertaken as a first step towards indigenous development of these diamond tools. Most of the diamond tools exist in the form of a composite structure with diamond grits embedded in a metallic matrix. This paper investigates the effect of various processing variables on the properties of DIMMC. Effect of pressure on the compaction behavior, sintering time and temperature has been investigated. Relatively better homogeneity has been observed with dry mixing of individual powders using zinc stearate as lubricant compared to wet mixing. A linear increase in green density has been found by increasing compaction pressure up to 400 MPa. (author)

  14. Solution-processed all-oxide bulk heterojunction solar cells based on CuO nanaorod array and TiO2 nanocrystals

    Science.gov (United States)

    Wu, Fan; Qiao, Qiquan; Bahrami, Behzad; Chen, Ke; Pathak, Rajesh; Tong, Yanhua; Li, Xiaoyi; Zhang, Tiansheng; Jian, Ronghua

    2018-05-01

    We present a method to synthesize CuO nanorod array/TiO2 nanocrystals bulk heterojunction (BHJ) on fluorine-tin-oxide (FTO) glass, in which single-crystalline p-type semiconductor of the CuO nanorod array is grown on the FTO glass by hydrothermal reaction and the n-type semiconductor of the TiO2 precursor is filled into the CuO nanorods to form well-organized nano-interpenetrating BHJ after air annealing. The interface charge transfer in CuO nanorod array/TiO2 heterojunction is studied by Kelvin probe force microscopy (KPFM). KPFM results demonstrate that the CuO nanorod array/TiO2 heterojunction can realize the transfer of photo-generated electrons from the CuO nanorod array to TiO2. In this work, a solar cell with the structure FTO/CuO nanoarray/TiO2/Al is successfully fabricated, which exhibits an open-circuit voltage (V oc) of 0.20 V and short-circuit current density (J sc) of 0.026 mA cm‑2 under AM 1.5 illumination. KPFM studies indicate that the very low performance is caused by an undesirable interface charge transfer. The interfacial surface potential (SP) shows that the electron concentration in the CuO nanorod array changes considerably after illumination due to increased photo-generated electrons, but the change in the electron concentration in TiO2 is much less than in CuO, which indicates that the injection efficiency of the photo-generated electrons from CuO to TiO2 is not satisfactory, resulting in an undesirable J sc in the solar cell. The interface photovoltage from the KPFM measurement shows that the low V oc results from the small interfacial SP difference between CuO and TiO2 because the low injected electron concentration cannot raise the Fermi level significantly in TiO2. This conclusion agrees with the measured work function results under illumination. Hence, improvement of the interfacial electron injection is primary for the CuO nanorod array/TiO2 heterojunction solar cells.

  15. On the Development of an Al4.8 wt% Cu Alloy Obtained from Recycled Aluminum Cans Designed for Thixoforming Process

    Directory of Open Access Journals (Sweden)

    Ronan Miller Vieira

    2016-01-01

    Full Text Available This work has focused on the development of a new aluminum alloy containing 4.8 wt% of Cu alloy obtained from recycled aluminium cans designed for thixoforming process. After the step of melting and solidification of the alloy in a metallic permanent mold, samples were solution heat treated at 525°C for times ranging from 2 h to 48 h, quenched in water and followed by natural aging. Results have shown the evolution of hardness so from them solubilization solution heat treatment was chosen for 24 h. The best condition for aging was 190°C during 3 h. With this data pieces were thixoforged at 580°C and 615°C corresponding, respectively, to solid fraction (fs of 0.8 and 0.6. The optimized T6 temper was applied and tensile tests were performed. The mechanical properties obtained are compatible with those obtained for consolidated alloys processed in semisolid state (SS and after T6 temper hardness increases from 95 HB to 122 HB and the best results were a tensile strength of 324 MPa ± 10 MPa, yield strength of 257 MPa ± 18 MPa, and an elongation of 7.1%  ±  1%. For alloys designed for thixoforming process, these results are in accordance with what was expected whereas globular microstructure, high ductility, and good performance under cyclic conditions are desirable.

  16. Processing of La(1.8)Sr(0.2)CuO4 and YBa2Cu3O7 superconducting thin films by dual-ion-beam sputtering

    Science.gov (United States)

    Madakson, P.; Cuomo, J. J.; Yee, D. S.; Roy, R. A.; Scilla, G.

    1988-03-01

    High-quality La(1.8)Sr(0.2)CuO4 and YBa2Cu3O7 superconducting thin films, with zero resistance at 88 K, have been made by dual-ion-beam sputtering of metal and oxide targets at elevated temperatures. The films are about 1.0 micron thick and are single phase after annealing. The substrates investigated are Nd-YAP, MgO, SrF2, Si, CaF2, ZrO2-(9 pct)Y2O3, BaF2, Al2O3, and SrTiO3. Characterization of the films was carried out using Rutherford backscattering spectroscopy, resistivity measurements, TEM, X-ray diffraction, and SIMS. Substrate/film interaction was observed in every case. This generally involves diffusion of the substrate into the film, which is accompanied by, for example, the replacement of Ba by Sr in the YBa2Cu2O7 structure, in the case of SrTiO3 substrate. The best substrates were those that did not significantly diffuse into the film and which did not react chemically with the film.

  17. Processing of La/sub 1.8/Sr/sub 0.2/CuO4 and YBa2Cu3O7 superconducting thin films by dual-ion-beam sputtering

    International Nuclear Information System (INIS)

    Madakson, P.; Cuomo, J.J.; Yee, D.S.; Roy, R.A.; Scilla, G.

    1988-01-01

    High quality La/sub 1.8/Sr/sub 0.2/CuO 4 and YBa 2 Cu 3 O 7 superconducting thin films, with zero resistance at 88 K, have been made by dual-ion-beam sputtering of metal and oxide targets at elevated temperatures. The films are about 1.0 μm thick and are single phase after annealing. The substrates investigated are Nd-YAP, MgO, SrF 2 , Si, CaF 2 , ZrO 2 -9% Y 2 O 3 , BaF 2 , Al 2 O 3 , and SrTiO 3 . Characterization of the films was carried out using Rutherford backscattering spectroscopy, resistivity measurements, transmission electron microscopy, x-ray diffraction, and secondary ion mass spectroscopy. Substrate/film interaction was observed in every case. This generally involves diffusion of the substrate into the film, which is accompanied by, for example, the replacement of Ba by Sr in the YBa 2 Cu 2 O 7 structure, in the case of SrTiO 3 substrate. The best substrates were those that did not significantly diffuse into the film and which did not react chemically with the film. In general, the superconducting transition temperature is found to depend on substrate temperature and ion beam energy, film composition, annealing conditions, and the nature and the magnitude of the substrate/film interaction

  18. Effects of plasma pretreatment on the process of self-forming Cu–Mn alloy barriers for Cu interconnects

    Directory of Open Access Journals (Sweden)

    Jae-Hyung Park

    2018-02-01

    Full Text Available This study investigated the effect of plasma pretreatment on the process of a self-forming Cu–Mn alloy barrier on porous low-k dielectrics. To study the effects of plasma on the performance of a self-formed Mn-based barrier, low-k dielectrics were pretreated with H2 plasma or NH3 plasma. Cu–Mn alloy materials on low-k substrates that were subject to pretreatment with H2 plasma exhibited lower electrical resistivity values and the formation of thicker Mn-based interlayers than those on low-k substrates that were subject to pretreatment with NH3 plasma. Transmission electron microscopy (TEM, X-ray photoemission spectroscopy (XPS, and thermal stability analyses demonstrated the exceptional performance of the Mn-based interlayer on plasma-pretreated low-k substrates with regard to thickness, chemical composition, and reliability. Plasma treating with H2 gas formed hydrophilic Si–OH bonds on the surface of the low-k layer, resulting in Mn-based interlayers with greater thickness after annealing. However, additional moisture uptake was induced on the surface of the low-k dielectric, degrading electrical reliability. By contrast, plasma treating with NH3 gas was less effective with regard to forming a Mn-based interlayer, but produced a Si–N/C–N layer on the low-k surface, yielding improved barrier characteristics.

  19. In-situ laser processing and microstructural characteristics of YBa2Cu3O7-δ thin films on Si with TiN buffer layer

    International Nuclear Information System (INIS)

    Tiwari, P.; Zheleva, T.; Narayan, J.

    1993-01-01

    The authors have prepared high-quality superconducting YBa 2 Cu 3 O 7 -δ (YBCO) thin films on Si(100) with TiN as a buffer layer using in-situ multitarget deposition system. Both TiN and YBCO thin films were deposited sequentially by KrF excimer laser ( | = 248 nm ) at substrate temperature of 650 C . Thin films were characterized using X-ray diffraction (XRD), four-point-probe ac resistivity, scanning electron microscopy (S E M), transmission electron microscopy (TEM), and Rutherford backscattering (RBS). The TiN buffer layer was epitaxial and the epitaxial relationship was found to be cube on cube with TiN parallel Si. YBCO thin films on Si with TiN buffer layer showed the transition temperature of 90-92K with T co (zero resistance temperature) of 84K. The authors have found that the quality of the buffer layer is very important in determining the superconducting transition temperature of the thin film. The effects of processing parameters and the correlation of microstructural features with superconducting properties are discussed in detail

  20. A Comparative Study of Additively Manufactured Thin Wall and Block Structure with Al-6.3%Cu Alloy Using Cold Metal Transfer Process

    Directory of Open Access Journals (Sweden)

    Baoqiang Cong

    2017-03-01

    Full Text Available In order to build a better understanding of the relationship between depositing mode and porosity, microstructure, and properties in wire + arc additive manufacturing (WAAM 2319-Al components, several Al-6.3%Cu deposits were produced by WAAM technique with cold metal transfer (CMT variants, pulsed CMT (CMT-P and advanced CMT (CMT-ADV. Thin walls and blocks were selected as the depositing paths to make WAAM samples. Porosity, microstructure and micro hardness of these WAAM samples were investigated. Compared with CMT-P and thin wall mode, CMT-ADV and block process can effectively reduce the pores in WAAM aluminum alloy. The microstructure varied with different depositing paths and CMT variants. The micro hardness value of thin wall samples was around 75 HV from the bottom to the middle, and gradually decreased toward the top. Meanwhile, the micro hardness value ranged around 72–77 HV, and varied periodically in block samples. The variation in micro hardness is consistent with standard microstructure characteristics.

  1. DOE applied to study the effect of process parameters on silicon spacing in lost foam Al-Si-Cu alloy casting

    International Nuclear Information System (INIS)

    Shayganpour, A; Izman, S; Idris, M H; Jafari, H

    2012-01-01

    Lost foam casting as a relatively new manufacturing process is extensively employed to produce sound complicated castings. In this study, an experimental investigation on lost foam casting of an Al-Si-Cu aluminium cast alloy was conducted. The research was aimed in evaluating the effect of different pouring temperatures, slurry viscosities, vibration durations and sand grain sizes on eutectic silicon spacing of thin-wall castings. A stepped-pattern was used in the study and the focus of the investigations was at the thinnest 3 mm section. A full two-level factorial design experimental technique was used to plan the experiments and afterwards identify the significant factors affecting casting silicon spacing. The results showed that pouring temperature and its interaction with vibration time have pronounced effect on eutectic silicon phase size. Increasing pouring temperature coarsened the eutectic silicon spacing while the higher vibration time diminished coarsening effect. Moreover, no significant effects on silicon spacing were found with variation of sand size and slurry viscosity.

  2. Preferred Orientation Contribution to the Anisotropic Normal State Resistivity in Superconducting Melt-Cast Processed Bi2Sr2CaCu2O8+δ

    Directory of Open Access Journals (Sweden)

    Aline Dellicour

    2017-05-01

    Full Text Available We describe how the contribution of crystallographic texture to the anisotropy of the resistivity of polycrystalline samples can be estimated by averaging over crystallographic orientations through a geometric mean approach. The calculation takes into account the orientation distribution refined from neutron diffraction data and literature values for the single crystal resistivity tensor. The example discussed here is a melt-cast processed Bi2Sr2CaCu2O8+δ (Bi-2212 polycrystalline tube in which the main texture component is a <010> fiber texture with relatively low texture strength. Experimentally-measured resistivities along the longitudinal, radial, and tangential directions of the Bi-2212 tube were compared to calculated values and found to be of the same order of magnitude. Calculations for this example and additional simulations for various texture strengths and single crystal resistivity anisotropies confirm that in the case of highly anisotropic phases such as Bi-2212, even low texture strengths have a significant effect on the anisotropy of the resistivity in polycrystalline samples.

  3. Fabrication of Cu(In,Ga)Se2 thin films by a combination of mechanochemical and screen-printing/sintering processes

    International Nuclear Information System (INIS)

    Wada, T.; Matsuo, Y.; Nomura, S.; Nakamura, Y.; Miyamura, A.; Chiba, Y.; Konagai, M.; Yamada, A.

    2006-01-01

    We prepared fine Cu(In,Ga)Se 2 (CIGS) powder suitable for screen printing using a mechanochemical process. Particulate precursors were deposited in a thin layer by a screen-printing technique, the remaining organic solvent was removed from the screen-printed CIGS film and finally the porous precursor layer was sintered into a dense polycrystalline film by atmospheric-pressure firing. The crystal structure of the film was analyzed by X-ray diffraction and the microstructure was observed in a SEM. The thickness of the film was 5-10 μm with a grain size of about 2 μm. The films were also observed in a TEM. The grain size of the as-prepared powder was less than 1 μm; however, it enlarged to 2-3 μm after firing at 575 C under a Se ambient. Preliminary CIGS solar cells with our standard Al grid/B-doped ZnO/i-ZnO/ CdS/CIGS/Mo/soda-lime glass structure were fabricated. An efficiency of 2.7%, a V oc of 0.325 V, a J sc of 28.3 mA/cm 2 and a FF of 0.295 was obtained. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  4. Thermal plasma properties for Ar–Al, Ar–Fe and Ar–Cu mixtures used in welding plasmas processes: I. Net emission coefficients at atmospheric pressure

    International Nuclear Information System (INIS)

    Cressault, Y; Gleizes, A

    2013-01-01

    This article is devoted to the calculation of the net emission coefficient (NEC) of Ar–Al, Ar–Fe and Ar–Cu mixtures at atmospheric pressure for arc welding processes. The results are given in data tables for temperatures between 3 kK and 30 kK, for five plasma thicknesses (0, 0.5, 1, 2, 5 mm) and ten concentrations of metallic vapours (pure gas, 0.01%, 0.1%, 1%, 5%, 10%, 25%, 50%, 75% and pure metal vapours in mass proportions). The results are in good agreement with most of the works published on the subject for such mixtures. They highlight the influence of three parameters on the radiation of the plasma: the NEC is directly related to temperature and inversely related to plasma radius and is highly sensitive to the presence of metal vapours. Finally, numerical data are supplied in tables in order to develop accurate computational modelling of welding arc and to estimate both qualitatively and quantitatively the influence of each metallic vapour on the size and on the shape of the weld pool. (paper)

  5. Evaluation of hardening and softening behaviors in Zn–21Al–2Cu alloy processed by equal channel angular pressing

    Directory of Open Access Journals (Sweden)

    José Luis Hernández-Rivera

    2017-10-01

    Full Text Available The microstructural evolution of as-cast and homogenized Zn–21Al–2Cu samples after two and six passes in an equal channel angular pressing (ECAP at room temperature was reported. A homogenization treatment for 24 h at 350 °C was applied to the as-cast samples followed by deformation. An annealing heat treatment was performed on all samples after the ECAP process. Our results showed that the homogenized and deformed samples displayed a uniform fine-grained microstructure after annealing, while as-cast samples without homogenization treatment presented only some regions of fine-grained microstructure. The level of microsegregation was higher in the as-cast samples as compared to the homogenized ones even after annealing. Vickers microhardness measurement on samples after deformation is smaller than the original material indicating a softening. However, after the annealing treatment, the microhardness increased, indicating that there was a slight hardening of the material. Keywords: Severe plastic deformation, ECAP, Work softening, Annealing, Hardening, Fine grain

  6. Highly Conductive Cu 2– x S Nanoparticle Films through Room-Temperature Processing and an Order of Magnitude Enhancement of Conductivity via Electrophoretic Deposition

    KAUST Repository

    Otelaja, Obafemi O.; Ha, Don-Hyung; Ly, Tiffany; Zhang, Haitao; Robinson, Richard D.

    2014-01-01

    © 2014 American Chemical Society. A facile room-temperature method for assembling colloidal copper sulfide (Cu2-xS) nanoparticles into highly electrically conducting films is presented. Ammonium sulfide is utilized for connecting the nanoparticles

  7. Facile synthesis of dendritic Cu by electroless reaction of Cu-Al alloys in multiphase solution

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ying; Liang, Shuhua, E-mail: liangxaut@gmail.com; Yang, Qing; Wang, Xianhui

    2016-11-30

    Highlights: • Nano- or micro-scale fractal dendritic copper (FDC) was synthesized by electroless immersing of Cu-Al alloys in CuCl{sub 2} + HCl. • FDC size increases with the increase of Al content in Cu-Al alloys immersed in CuCl{sub 2} + HCl solution. • Nanoscale Cu{sub 2}O was found at the edge of FDC. Nanoporous copper (NPC) can also be obtained by using Cu{sub 17}Al{sub 83} alloy. • The potential difference between CuAl{sub 2} and α-Al phase and the replacement reaction in multiphase solution are key factors. - Abstract: Two-dimensional nano- or micro-scale fractal dendritic coppers (FDCs) were synthesized by electroless immersing of Cu-Al alloys in hydrochloric acid solution containing copper chloride without any assistance of template or surfactant. The FDC size increases with the increase of Al content in Cu-Al alloys immersed in CuCl{sub 2} + HCl solution. Compared to Cu{sub 40}Al{sub 60} and Cu{sub 45}Al{sub 55} alloys, the FDC shows hierarchical distribution and homogeneous structures using Cu{sub 17}Al{sub 83} alloy as the starting alloy. The growth direction of the FDC is <110>, and all angles between the trunks and branches are 60°. Nanoscale Cu{sub 2}O was found at the edge of FDC. Interestingly, nanoporous copper (NPC) can also be obtained through Cu{sub 17}Al{sub 83} alloy. Studies showed that the formation of FDC depended on two key factors: the potential difference between CuAl{sub 2} intermetallic and α-Al phase of dual-phase Cu-Al alloys; a replacement reaction that usually occurs in multiphase solution. The electrochemical experiment further proved that the multi-branch dendritic structure is very beneficial to the proton transfer in the process of catalyzing methanol.

  8. Effects of Medium-Term Amendment with Diversely Processed Sewage Sludge on Soil Humification—Mineralization Processes and on Cu, Pb, Ni, and Zn Bioavailability

    Directory of Open Access Journals (Sweden)

    Gabriella Rossi

    2018-03-01

    Full Text Available The organic fraction of sewage sludge administered to agricultural soil can contribute to slowing down the loss of soil’s organic carbon and, in some cases, can improve the physical and mechanical properties of the soil. One of the main constraints to the agricultural use of sewage sludge is its heavy metals content. In the long term, agricultural administration of sewage sludge to soil could enhance the concentration of soil heavy metals (as total and bioavailable fractions. The aim of this research was to evaluate the effects of medium-term fertilization with diversely processed sewage sludge on the soil’s organic carbon content and humification–mineralization processes, on the physical–mechanical properties of soil and their influence on the pool of potentially bioavailable heavy metals, in order to assess their effectiveness as soil organic amendments. After eight years of sludge administration; an increase in the concentrations of bioavailable form was evidenced in all the heavy metals analyzed; independently of the type of sludge administered. The form of sludge administration (liquid, dehydrated, composted has differently influenced the soil humification–mineralization processes and the physical–mechanical properties of soil. The prolonged amendment with composted sewage sludge contributed to keeping the soil humification–mineralization process in equilibrium and to improving the physical and mechanical qualities of the treated soil.

  9. LoCuSS: THE SLOW QUENCHING OF STAR FORMATION IN CLUSTER GALAXIES AND THE NEED FOR PRE-PROCESSING

    Energy Technology Data Exchange (ETDEWEB)

    Haines, C. P. [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Correo Central, Santiago (Chile); Pereira, M. J.; Egami, E.; Rawle, T. D. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Smith, G. P.; Ziparo, F.; McGee, S. L. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Babul, A. [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8P 1A1 (Canada); Finoguenov, A. [Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, FI-0014 Helsinki (Finland); Okabe, N. [Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), P.O. Box 23-141, Taipei 10617, Taiwan (China); Moran, S. M., E-mail: cphaines@das.uchile.cl [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

    2015-06-10

    We present a study of the spatial distribution and kinematics of star-forming galaxies in 30 massive clusters at 0.15 < z < 0.30, combining wide-field Spitzer 24 μm and GALEX near-ultraviolet imaging with highly complete spectroscopy of cluster members. The fraction (f{sub SF}) of star-forming cluster galaxies rises steadily with cluster-centric radius, increasing fivefold by 2r{sub 200}, but remains well below field values even at 3r{sub 200}. This suppression of star formation at large radii cannot be reproduced by models in which star formation is quenched in infalling field galaxies only once they pass within r{sub 200} of the cluster, but is consistent with some of them being first pre-processed within galaxy groups. Despite the increasing f{sub SF}-radius trend, the surface density of star-forming galaxies actually declines steadily with radius, falling ∼15× from the core to 2r{sub 200}. This requires star formation to survive within recently accreted spirals for 2–3 Gyr to build up the apparent over-density of star-forming galaxies within clusters. The velocity dispersion profile of the star-forming galaxy population shows a sharp peak of 1.44 σ{sub ν} at 0.3r{sub 500}, and is 10%–35% higher than that of the inactive cluster members at all cluster-centric radii, while their velocity distribution shows a flat, top-hat profile within r{sub 500}. All of these results are consistent with star-forming cluster galaxies being an infalling population, but one that must also survive ∼0.5–2 Gyr beyond passing within r{sub 200}. By comparing the observed distribution of star-forming galaxies in the stacked caustic diagram with predictions from the Millennium simulation, we obtain a best-fit model in which star formation rates decline exponentially on quenching timescales of 1.73 ± 0.25 Gyr upon accretion into the cluster.

  10. Luminescence investigation of Cu(In,Ga)Se{sub 2}solar cells with different Ga-contents grown in a three-stage-process on glass substrate

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, Kristin; Mueller, Mathias; Hempel, Thomas; Bertram, Frank; Christen, Juergen [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg (Germany); Abou-Ras, Daniel; Rissom, Thorsten; Unold, Thomas; Schock, Hans-Werner [Helmholtz-Zentrum Berlin for Materials and Energy (Germany)

    2011-07-01

    A fundamental advantage of Cu(In,Ga)Se{sub 2} (CIGS) alloys as absorber materials in thin-film solar cells is their direct band gap energies which can be varied between 1.04 eV (CuInSe{sub 2}) and 1.68 eV (CuGaSe{sub 2}). Photoluminescence (PL) spectra of complete CIGS solar cells with a systematic variation of the Ga-content in the absorber layer will be presented. The CIGS cells investigated were grown on a Mo back contact sputtered on soda lime glass and have a Ga-concentration ranging over the entire range from CuInSe{sub 2} to CuGaSe{sub 2}. Samples with Ga-contents between 100 % and 33 % show two broad luminescence bands. In contrast, CuInSe{sub 2} exhibits only one broad luminescence band. Each band is composed of two or three different transitions. Varying excitation density over four orders of magnitude results for samples with Ga-content of 0 % and 33 % in a blueshift of the main peak with increasing excitation density. For higher Ga-concentrations, first a blue- and then a redshift of the dominating peak with increasing excitation density is visible. The temperature dependence of the PL spectra is investigated going from 4 K to 300 K.

  11. Cu-Doping Effects in CdI(2) Nanocrystals: The Role of Cu-Agglomerates.

    Science.gov (United States)

    Miah, M Idrish

    2008-11-22

    Cu-doping effects in CdI(2) nanocrystals are studied experimentally. We use the photostimulated second harmonic generation (PSSHG) as a tool to investigate the effects. It is found that the PSSHG increases with increasing Cu content up to 0.6% and then decreases due to the formation of the Cu-agglomerates. The PSSHG for the crystal with Cu content higher than 1% reduces to that for the undoped CdI(2) crystal. The results suggest that a crucial role of the Cu-metallic agglomerates is involved in the processes as responsible for the observed effects.

  12. Cu-Doping Effects in CdI2Nanocrystals: The Role of Cu-Agglomerates

    Directory of Open Access Journals (Sweden)

    Miah M

    2008-01-01

    Full Text Available Abstract Cu-doping effects in CdI2nanocrystals are studied experimentally. We use the photostimulated second harmonic generation (PSSHG as a tool to investigate the effects. It is found that the PSSHG increases with increasing Cu content up to 0.6% and then decreases due to the formation of the Cu-agglomerates. The PSSHG for the crystal with Cu content higher than 1% reduces to that for the undoped CdI2crystal. The results suggest that a crucial role of the Cu-metallic agglomerates is involved in the processes as responsible for the observed effects.

  13. Plasma ash processing solutions for advanced interconnect technology

    International Nuclear Information System (INIS)

    Fuller, N.C.M.; Worsley, M.A.; Tai, L.; Bent, S.; Labelle, C.; Arnold, J.; Dalton, T.

    2008-01-01

    A mechanism for the modification of porous ultra low-k (ULK) and extreme ultra low-k (EULK) SiCOH-based materials is proposed. This is achieved by correlating film damage on a patterned structure measured by angular resolved x-ray photoelectron spectroscopy (ARXPS) with corresponding changes in reactive species radical density and ion current in the plasma measured by optical emission spectroscopy (OES), rare gas actinometry, and modeling. Line-to-line electrical leakage and capacitance data of nested line structures exposed to downstream ash plasmas suggest that other etching steps during back-end-of-the-line (BEOL) dual damascene processing are also critical for the overall modification induced to these materials

  14. Effect of defect on the nonlinear and dielectric property of Ca(1–x)SrxCu3Ti4O12 ceramics synthesized by sol–gel process

    International Nuclear Information System (INIS)

    Li, Tao; Liu, Dewei; Dai, Haiyang; Xiang, Huiwen; Chen, Zhenping; He, Huifang; Chen, Zhiquan

    2014-01-01

    Highlights: • Ca (1−x) Sr x Cu 3 Ti 4 O 12 ceramics are synthesized by sol–gel process. • Positron annihilation lifetime spectra is used to investigate the defects of samples. • Nonlinear and dielectric properties are controlled by density and defects of samples. - Abstract: Ca (1−x) Sr x Cu 3 Ti 4 O 12 (x = 0, 0.05, 0.1, 0.15, 0.2, 0.3 and 0.4) ceramics are synthesized by sol–gel process. The XRD patterns show that weak peaks of Sr 4 Ti 3 O 10 , TiO 2 and Ca 1.7 Sr 0.3 CuO 3 begin to appear at x ⩾ 0.2. Sr-doping is conductive to increase the density and reduce the defect concentration Ca (1−x) Sr x Cu 3 Ti 4 O 12 ceramics as x ⩽ 0.15. With increasing x (0.2 ⩽ x ⩽ 0.4), Sr-doping reduces the density and enhances the concentration of defects for the ceramics. The nonlinear coefficient value increases and reaches a maximum 13.5 at x = 0.15, and then decreases gradually with increasing x. The dielectric properties demonstrate that, as x ⩽ 0.15, Sr-doping not only increases the dielectric permittivity value and decreases the dielectric loss but also reduces the dependence on frequency at low frequencies. With increasing x (0.2 ⩽ x ⩽ 0.4), Sr-doping begins to lead to an inverse result in dielectric behaviors. The nonlinear and dielectric properties of Ca (1−x) Sr x Cu 3 Ti 4 O 12 ceramics are directly controlled by the density and defects

  15. Cu-62, Cu-64 and Cu-66 production with 4.2 MeV deuterons; Produccion de {sup 62} Cu y {sup 64} Cu con deuterones de 4,2 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Avila, Mario; Morales, J R; Riquelme, H O [Chile Univ., Santiago (Chile). Facultad de Ciencias. Dept. de Fisica

    1997-12-31

    Full text: The natural copper irradiation with deuterons produces the Cu-62, Cu-64 and Cu-66 radionuclides. Of two radioisotopes, those with deficiencies in neutrons, are applied in nuclear medicine diagnostic processes, mainly for the nuclear characteristic of the decay modes. The positron emitters, of short life mean Cu-62 (9.1 min, {beta}{sup +}) and Cu(12.7 h), are radionuclides applied in radio pharmacological preparation for brain, core, blood flux studies. The radiochemical process consists in the de solution of the irradiated metallic copper target, in acid medium. The result solution, can be neutralized with a base or a buffer at wished pH. Using a deuteron beam of 4,2 {+-} 0,1 MeV energy has been obtained total yields of 1,103 {+-} 0,011 {mu}Cl/{mu}Ah medium for 62 Cu and of 0,148 {+-} 0,015 {mu}Cl/{mu}Ah for 64 Cu.

  16. Cu-TDPAT, an rht -type dual-functional metal-organic framework offering significant potential for use in H 2 and natural gas purification processes operating at high pressures

    KAUST Repository

    Wu, Haohan; Yao, Kexin; Zhu, Yihan; Li, Baiyan; Shi, Zhan; Krishna, Rajamani A A; Li, Jing

    2012-01-01

    The separations of CO 2/CO/CH 4/H 2, CO 2/H 2, CH 4/H 2, and CO 2/CH 4 mixtures at pressures ranging to 7 MPa are important in a variety of contexts, including H 2 production, natural gas purification, and fuel-gas processing. The primary objective of this study is to demonstrate the selective adsorption potential of an rht-type metal-organic framework [Cu 3(TDPAT)(H 2O) 3]·10H 2O·5DMA (Cu-TDPAT), possessing a high density of both open metal sites and Lewis basic sites. Experimental high pressure pure component isotherm data for CO 2, CO, CH 4, and H 2 are combined with the Ideal Adsorbed Solution Theory (IAST) for estimation of mixture adsorption equilibrium. The separation performance of Cu-TDPAT is compared with four other microporous materials, specifically chosen in order to span a wide range of physicochemical characteristics: MgMOF-74, MIL-101, LTA-5A, and NaX. For all mixtures investigated, the capacity of Cu-TDPAT to produce the desired product, H 2 or CH 4, satisfying stringent purity requirements, in a fixed bed operating at pressures exceeding about 4 MPa, is either comparable to, or exceeds, that of other materials. © 2012 American Chemical Society.

  17. Enhanced electrical properties of pulsed laser-deposited CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} thin films via processing control

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Yeon Hwa; Mohanty, Bhaskar Chandra; Cho, Yong Soo [Department of Materials Science and Engineering, Yonsei University, Seoul (Korea, Republic of)

    2010-12-15

    Polycrystalline CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} thin films were prepared on soda-lime glass substrates using pulsed laser deposition (PLD) with various process parameters such as laser energy, repetition rate and substrate temperature. It was confirmed that there existed a limited laser energy, i.e. less than 300 mJ, to get phase pure CIGS thin films at room temperature. Particularly, even at room temperature, distinct crystalline CIGS phase was observed in the films. Crystallinity of the films improved with increasing substrate temperature as evidenced by the decrease of FWHM from 0.65 degto 0.54 deg. Slightly Cu-rich surface with Cu{sub 2-x}Se phase was confirmed to exist by Raman spectra, depending on substrate temperature. Improved electrical properties, i.e., carrier concentration of {proportional_to}10{sup 18} cm{sup -3} and resistivity of 10{sup -1}{omega} cm at higher substrate temperature for the optimal CIGS films are assumed to be induced by the potential contributions from highly crystallized thin films, existence of Cu{sub 2-x}Se phase and diffusion of Na from substrates to films. (author)

  18. Cu-TDPAT, an rht -type dual-functional metal-organic framework offering significant potential for use in H 2 and natural gas purification processes operating at high pressures

    KAUST Repository

    Wu, Haohan

    2012-08-09

    The separations of CO 2/CO/CH 4/H 2, CO 2/H 2, CH 4/H 2, and CO 2/CH 4 mixtures at pressures ranging to 7 MPa are important in a variety of contexts, including H 2 production, natural gas purification, and fuel-gas processing. The primary objective of this study is to demonstrate the selective adsorption potential of an rht-type metal-organic framework [Cu 3(TDPAT)(H 2O) 3]·10H 2O·5DMA (Cu-TDPAT), possessing a high density of both open metal sites and Lewis basic sites. Experimental high pressure pure component isotherm data for CO 2, CO, CH 4, and H 2 are combined with the Ideal Adsorbed Solution Theory (IAST) for estimation of mixture adsorption equilibrium. The separation performance of Cu-TDPAT is compared with four other microporous materials, specifically chosen in order to span a wide range of physicochemical characteristics: MgMOF-74, MIL-101, LTA-5A, and NaX. For all mixtures investigated, the capacity of Cu-TDPAT to produce the desired product, H 2 or CH 4, satisfying stringent purity requirements, in a fixed bed operating at pressures exceeding about 4 MPa, is either comparable to, or exceeds, that of other materials. © 2012 American Chemical Society.

  19. Effects of processing parameters on the morphology, structure, and magnetic properties of Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} nanoparticles synthesized with chemical methods

    Energy Technology Data Exchange (ETDEWEB)

    Ivantsov, R.D. [Kirensky Institute of Physics, Russian Academy of Sciences, Krasnoyarsk, 660036 (Russian Federation); Edelman, I.S., E-mail: ise@iph.krasn.ru [Kirensky Institute of Physics, Russian Academy of Sciences, Krasnoyarsk, 660036 (Russian Federation); Zharkov, S.M.; Velikanov, D.A. [Kirensky Institute of Physics, Russian Academy of Sciences, Krasnoyarsk, 660036 (Russian Federation); Siberian Federal University, Krasnoyarsk, 660041 (Russian Federation); Petrov, D.A. [Kirensky Institute of Physics, Russian Academy of Sciences, Krasnoyarsk, 660036 (Russian Federation); Ovchinnikov, S.G. [Kirensky Institute of Physics, Russian Academy of Sciences, Krasnoyarsk, 660036 (Russian Federation); Siberian Federal University, Krasnoyarsk, 660041 (Russian Federation); Lin, Chun-Rong [National Pingtung University, Pingtung City, Pingtung County, 90003, Taiwan (China); Li, Oksana [Siberian Federal University, Krasnoyarsk, 660041 (Russian Federation); National Pingtung University, Pingtung City, Pingtung County, 90003, Taiwan (China); Tseng, Yaw-Teng [National Pingtung University, Pingtung City, Pingtung County, 90003, Taiwan (China)

    2015-11-25

    Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} nanoparticles with x = 0, 0.2, and 0.4 were synthesized via thermal decomposition of metal nitrate or chloride salts and selenium powder using different precursor compositions and processing details. Single crystalline nano-belts or nano-rods coexist in the synthesized powder samples with hexagon-shaped plates in dependence on the precursor composition. The belts gathered into conglomerates forming “hierarchical” particles. Visible magnetic circular dichroism (MCD) of Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} nanoparticles embedded into a transparent matrix was investigated for the first time. The similarity of the MCD spectra of all samples showed the similarity of the nanoparticles electronic structure independent of their morphology. Basing on the MCD spectral maxima characteristics, electron transitions from the ground to the excited states were identified with the help of the conventional band theory and the multi-electron approach. - Highlights: • Single crystalline Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} nanoparticles with x = 0, 0.2, 0.4 were synthesized. • Correlation between synthesis conditions and nanoparticles morphology were obtained. • The nanoparticles magnetization behavior was studied. • Visible MCD of the Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} nanoparticles were studied for the first time.

  20. Effect of Joint Scale and Processing on the Fracture of Sn-3Ag-0.5Cu Solder Joints: Application to Micro-bumps in 3D Packages

    Science.gov (United States)

    Talebanpour, B.; Huang, Z.; Chen, Z.; Dutta, I.

    2016-01-01

    In 3-dimensional (3D) packages, a stack of dies is vertically connected to each other using through-silicon vias and very thin solder micro-bumps. The thinness of the micro-bumps results in joints with a very high volumetric proportion of intermetallic compounds (IMCs), rendering them much more brittle compared to conventional joints. Because of this, the reliability of micro-bumps, and the dependence thereof on the proportion of IMC in the joint, is of substantial concern. In this paper, the growth kinetics of IMCs in thin Sn-3Ag-0.5Cu joints attached to Cu substrates were analyzed, and empirical kinetic laws for the growth of Cu6Sn5 and Cu3Sn in thin joints were obtained. Modified compact mixed mode fracture mechanics samples, with adhesive solder joints between massive Cu substrates, having similar thickness and IMC content as actual micro-bumps, were produced. The effects of IMC proportion and strain rate on fracture toughness and mechanisms were investigated. It was found that the fracture toughness G C decreased with decreasing joint thickness ( h Joint). In addition, the fracture toughness decreased with increasing strain rate. Aging also promoted alternation of the crack path between the two joint-substrate interfaces, possibly proffering a mechanism to enhance fracture toughness.

  1. Solution processing of CuSe quantum dots: Photocatalytic activity under RhB for UV and visible-light solar irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kaviyarasu, K., E-mail: kaviyarasuloyolacollege@gmail.com [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology Laboratories, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), Materials Research Department (MSD), iThemba LABS-National Research Foundation - NRF, 1 Old Faure Road, 7129, P O Box 722, Somerset West, Western Cape Province (South Africa); Ayeshamariam, A. [Department of Physics, Khadir Mohideen College, Adirampattinam, Tamil Nadu (India); Research and Development Centre, Bharathiyar University, Coimbatore, Tamil Nadu (India); Manikandan, E. [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology Laboratories, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); Central Research Laboratory, Sree Balaji Medical College & Hospital, Bharath University, Chrompet, Chennai, Tamil Nadu 600044 (India); Kennedy, J. [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology Laboratories, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); National Isotope Centre, GNS Science, PO Box 31312, Lower Hutt 5010 (New Zealand); Ladchumananandasivam, R. [Department of Textile Engineering & Post Graduate Programme in Mechanical Engineering, Centre of Technology, Federal University of the State of Rio Grande do Norte, Campus Universitario, 59078-970 Natal, RN (Brazil); Umbelino Gomes, Uilame [Graduate Program in Materials Science and Engineering, Departamento de Fisica, Universidade Federal do Rio Grande do Norte, 59.072 Natal, RN (Brazil); Jayachandran, M. [Electrochemical Materials Science Division, CSIR-Central Electrochemical Research Institute, Council of Scientific & Industrial Research New Delhi, Karaikudi, 630 006 Tamil Nadu (India); and others

    2016-08-15

    Highlights: • Reflex method generates highly crystalline products with high purity. • Photocatalytic activities are closely related with their surface area. • The average lattice constants are a = 3.96 Å & c = 17.23 Å. • Atomic percentage of Cu and Se elements sample is 54.65 and 45.35. • Stoichiometric atomic percentage of Cu is 33.33% and Se is 66.67%. - Graphical Abstract: - Abstract: Exploit of photodegradation and photocatalytic activity of large scale synthesis of (CuSe) copper selenide semiconductor quantum dots was reported. The obtained nanocrystals were characterized by X-ray diffraction (XRD), UV-visible absorption spectroscopy (UV-vis) photoluminescence (PL) and high resolution transmission electron microscopy (HRTEM). The crystalline, nearly monodisperse with uniform size were synthesized by the reflux condensation method. This method promises a range of possibilities for the preparation of CuSe materials with enhanced properties. Experimental investigation shows the nanoscale photocatalysts with high surface area, small particle size and high crystallinity is of current interest in nanophase materials. The chemical composition of the CuSe samples and the valence states of elements were determined by X-ray photoelectron spectroscopy (XPS). We present our investigations to the shape and size of the quantum dots and are good agreement with experimental results.

  2. New Processing and Characterization Approaches for Achieving Full Performance of High Temperature Superconducting Tapes of (Bi,Pb)2Sr2Ca2Cu3Ox

    International Nuclear Information System (INIS)

    E.E. Hellstrom; D.C. Larbalestier

    2006-01-01

    The thrust of this research was to identify and understand current limiting mechanisms (CLMs) that limit the current carrying capacity of (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O x (2223) in Ag-sheathed wire. Our program concentrated on developing new methods to identify CLMs at the micrometer scale and new processing techniques to eliminate CLMs. All of the DOE Superconductivity Partnership Initiative (SPI) programs are using 2223 wire, so increasing the critical current density (J c ) in the wire can improve the technical performance of the demonstration projects, and at the same time it can decrease the cost of the wire. The important cost metric for superconducting wire is $/kA·m, so increasing Jc, which is in the denominator, decreases the wire cost. The obvious CLMs were micrometer size obstacles in the 2223 ceramic that block current flow, including: misaligned grains, cracks, pores, and nonsuperconducting phases. Pores and cracks--regions where there is no superconductor or the grains are not physically connected to one another--cannot carry supercurrent, so they were the first CLMs we tried to eliminate with improved processing. Prior to the contract, we had started investigating overpressure (OP) processing with Williams at ORNL to heal cracks and remove pores. OP processing, which is a variant of hot isostatic pressing (HIP), uses an Ar/O 2 gas mixture to apply a high pressure (up to 200 atm) to compress the sample and to set the oxygen partial pressure (pO 2 ) to form 2223. Williams had a static pressure system we used to demonstrate that OP processing healed cracks and densified the wire, but the static system limited the processing parameters we could investigate. We proposed building a new gas-flow OP system to expand the experimental capabilities and to investigate new processing routes using the gas-flow OP system. Using the gas-flow OP system, we established new world records in 2003 for J c and I c . These records were finally matched by Sumitomo Electric

  3. Nanoscale observation of surface potential and carrier transport in Cu2ZnSn(S,Se)4 thin films grown by sputtering-based two-step process.

    Science.gov (United States)

    Kim, Gee Yeong; Kim, Ju Ri; Jo, William; Son, Dae-Ho; Kim, Dae-Hwan; Kang, Jin-Kyu

    2014-01-08

    Stacked precursors of Cu-Zn-Sn-S were grown by radio frequency sputtering and annealed in a furnace with Se metals to form thin-film solar cell materials of Cu2ZnSn(S,Se)4 (CZTSSe). The samples have different absorber layer thickness of 1 to 2 μm and show conversion efficiencies up to 8.06%. Conductive atomic force microscopy and Kelvin probe force microscopy were used to explore the local electrical properties of the surface of CZTSSe thin films. The high-efficiency CZTSSe thin film exhibits significantly positive bending of surface potential around the grain boundaries. Dominant current paths along the grain boundaries are also observed. The surface electrical parameters of potential and current lead to potential solar cell applications using CZTSSe thin films, which may be an alternative choice of Cu(In,Ga)Se2.PACS number: 08.37.-d; 61.72.Mm; 71.35.-y.

  4. A new fabrication process for YBa2Cu4O8 superconducting filaments by the solution spinning method under ambient pressure

    International Nuclear Information System (INIS)

    Goto, T.; Kojima, K.

    1992-01-01

    The Y 1 Ba 2 Cu 4 O 8 superconducting filament has successfully been prepared by dry-spinning through a homogeneous aqueous solution containing Y, Ba and Cu acetates, polyvinyl alcohol and other organic acids. After removing volatile components, the 124 filament is obtained by heating at 780deg C for 3 h. A decomposition of the 124 filament is investigated for introducing fine flux-pinning centers into the 123 filament. A high transport J c value of 1900 A/cm 2 at 77 K and at 0 T is attained for the 123 filament through the decomposition of the 124 filament. (orig.)

  5. Sol-gel process for preparation of YBa2Cu4O8 from acidic acetates/ammonia/ascorbic acid systems

    International Nuclear Information System (INIS)

    Deptula, A.; Lada, W.; Olczak, T.; Goretta, K.C.

    1997-01-01

    YBa 2 Cu 4 O x sols were prepared by addition of ammonia to acidic acetate solutions of Y 3+ , Ba 2+ , and Cu 2+ . Ascorbic acid was added to part of the sol. The resultant sols were gelled to a shard or a coating by evaporation at 60 C. Addition of ethanol to the sols facilitated formation of gel coatings, fabricated by a dipping technique, on Ag or glass or substrates. At 100 C, gels formed in the presence of ascorbic acid were perfectly amorphous, in contrast to crystalline acetate gels. The quality of coatings prepared from ascorbate gels was superior to that of acetate gel coatings

  6. Thermal and mechanical properties of lead-free SnZn–xNa casting alloys, and interfacial chemistry on Cu substrates during the soldering process

    Energy Technology Data Exchange (ETDEWEB)

    Gancarz, Tomasz, E-mail: tomasz.gancarz@imim.pl [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Krakow (Poland); Bobrowski, Piotr; Pstruś, Janusz [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Krakow (Poland); Pawlak, Sylwia [Wroclaw Research Centre EIT+, Wroclaw (Poland)

    2016-09-15

    The microstructural features, thermal properties and mechanical properties of eutectic Sn–Zn alloys with varying Na content (0.1, 0.2, 0.5, 1.0 3.0 and 5.0 at. %) were examined in this study. In the scanning electron microscopy, transmission electron microscopy, and X-ray diffraction analysis data, precipitates of NaSn were observed. The addition of Na to eutectic Sn–Zn alloy improved the mechanical properties and increased electrical resistivity, and reduced the coefficient of thermal expansion; however, the melting point did not change. Wettability tests carried out using Na-doped Sn–15Zn alloys on Cu substrates showed the formation of Cu–Zn phases at the interfaces. Wettability studies were performed using flux ALU33 after 60, 180, 480, 900, 1800 and 3600 s of contact, at temperatures of 230, 250, 280 and 320 °C. The experiments were designed to demonstrate the effect of Na addition on the formation and growth kinetics of Cu{sub 5}Zn{sub 8} and CuZn{sub 4} phases, which were identified using XRDs and EDS. The addition of Na to SnZn causes a reduction in the thickness of the intermetallic compounds layer created at the interface between the liquid solder and the Cu substrate, and an increase in the activation energy of the Cu{sub 5}Zn{sub 8} phase compared to eutectic SnZn. - Highlights: • Precipitates of NaSn was observed and confirmed using TEM and XRD. • Addition Na to eutectic SnZn cussed increased the mechanical properties. • IMCs of Na–Zn and Na–Sn increased electrical resistivity and reduced the CTE. • IMCs layers CuZn{sub 4} and Cu{sub 5}Zn{sub 8} was found at the interface. • Na content changing the character of growth CuZn{sub 4} layer in SnZnNa alloys.

  7. Interfacial Reaction of Sn-Ag-Cu Lead-Free Solder Alloy on Cu: A Review

    Directory of Open Access Journals (Sweden)

    Liu Mei Lee

    2013-01-01

    Full Text Available This paper reviews the function and importance of Sn-Ag-Cu solder alloys in electronics industry and the interfacial reaction of Sn-Ag-Cu/Cu solder joint at various solder forms and solder reflow conditions. The Sn-Ag-Cu solder alloys are examined in bulk and in thin film. It then examines the effect of soldering conditions to the formation of intermetallic compounds such as Cu substrate selection, structural phases, morphology evolution, the growth kinetics, temperature and time is also discussed. Sn-Ag-Cu lead-free solder alloys are the most promising candidate for the replacement of Sn-Pb solders in modern microelectronic technology. Sn-Ag-Cu solders could possibly be considered and adapted in miniaturization technologies. Therefore, this paper should be of great interest to a large selection of electronics interconnect materials, reliability, processes, and assembly community.

  8. Corrosion behavior of Cu during graphene growth by CVD

    International Nuclear Information System (INIS)

    Dong, Yuhua; Liu, Qingqing; Zhou, Qiong

    2014-01-01

    Highlights: • Graphene films were deposited on the Cu by chemical vapor deposition method. • Annealing affects the corrosion property of Cu. • Graphene films improve corrosion performance of Cu for a short period of time. - Abstract: The corrosion performance of Cu samples may be affected by annealing at high temperatures during graphene growth via the chemical vapor deposition method. In this study, multiple graphene films were deposited on Cu and characterized by Raman spectroscopy and transmission electron microscopy. The corrosion behavior of Cu immersed in 3.5 wt.% NaCl solution was investigated using electrochemical impedance spectroscopy. The Cu morphology was observed by optical microscopy and scanning electron microscopy. Results indicated that annealing affects the corrosion process of Cu. The presence of graphene films on the Cu substrate improved the corrosion performance of the material for a short period of time

  9. Microstructures and Tensile Properties of Al–Cu Matrix Composites Reinforced with Nano-Sized SiCp Fabricated by Semisolid Stirring Process

    Directory of Open Access Journals (Sweden)

    Feng Qiu

    2017-02-01

    Full Text Available The nano-sized SiCp/Al–Cu composites were successfully fabricated by combining semisolid stirring with ball milling technology. Microstructures were examined by an olympus optical microscope (OM, field emission scanning electron microscope (FESEM and transmission electron microscope (TEM. Tensile properties were studied at room temperature. The results show that the α-Al dendrites of the composites were strongly refined, especially in the composite with 3 wt. % nano-sized SiCp, of which the morphology of the α-Al changes from 200 μm dendritic crystal to 90 μm much finer equiaxial grain. The strength and ductility of the composites are improved synchronously with the addition of nano-sized SiCp particles. The as-cast 3 wt. % nano-sized SiCp/Al–Cu composite displays the best tensile properties, i.e., the yield strength, ultimate tensile strength (UTS and fracture strain increase from 175 MPa, 310 MPa and 4.1% of the as-cast Al–Cu alloy to 220 MPa, 410 MPa and 6.3%, respectively. The significant improvement in the tensile properties of the composites is mainly due to the refinement of the α-Al dendrites, nano-sized SiCp strengthening, and good interface combination between the SiCp and Al–Cu alloys.

  10. Solution-processed p-type copper(I) thiocyanate (CuSCN) for low-voltage flexible thin-film transistors and integrated inverter circuits

    KAUST Repository

    Petti, Luisa; Pattanasattayavong, Pichaya; Lin, Yen-Hung; Mü nzenrieder, Niko; Cantarella, Giuseppe; Yaacobi-Gross, Nir; Yan, Feng; Trö ster, Gerhard; Anthopoulos, Thomas D.

    2017-01-01

    , depending on the gate dielectric employed. The promising TFT characteristics enable fabrication of unipolar NOT gates on flexible free-standing plastic substrates with voltage gain of 3.4 at voltages as low as −3.5 V. Importantly, discrete CuSCN transistors

  11. Hole-transporting transistors and circuits based on the transparent inorganic semiconductor copper(I) thiocyanate (CuSCN) processed from solution at room temperature

    KAUST Repository

    Pattanasattayavong, Pichaya; Yaacobi-Gross, Nir; Zhao, Kui; Ndjawa, Guy Olivier Ngongang; Li, Jinhua; Yan, Feng; O'Regan, Brian C.; Amassian, Aram; Anthopoulos, Thomas D.

    2012-01-01

    ferroelectric polymeric dielectric P(VDF-TrFE-CFE), we demonstrate low-voltage transistors with hole mobilities on the order of 0.1 cm2 V-1 s-1. By integrating two CuSCN transistors, unipolar logic NOT gates are also demonstrated. Copyright © 2013 WILEY

  12. Effect of alkali elements in thin-film Cu2ZnSnS4 solar cells produced by solution-processing

    DEFF Research Database (Denmark)

    Engberg, Sara Lena Josefin; Canulescu, Stela; Schou, Jørgen

    The effect of adding Li, Na, and K to Cu2ZnSnS4 nanoparticle thin-film absorber layers has been investigated. Among them, K is found to enhance grain growth as well as increase the photoluminescence of the films....

  13. Characteristics of La0.7Ca0.3MnO3-Cu composites fabricated by an electroless process

    International Nuclear Information System (INIS)

    Xiong, Y H; Song, S J; Xu, W; Pi, H L; Ren, Z M; Zhang, J; Bao, X C; Xiong, J; Li, D G; Huang, W H; Sun, C L; Cheng, X W; Xiong, C S

    2007-01-01

    Ferromagnet-metal-type composites, La 0.7 Ca 0.3 MnO 3 (LCMO)-Cu, have been fabricated by a three-step route. We got LCMO powder using the conventional solid state method. Then, LCMO powders coated by Cu are obtained using a novel electroless plating technique, in which the contents of copper are controlled by changing the plating time. Finally these powders are pelletized and then sintered at different temperatures in argon. The powders coated by Cu are characterized by x-ray powder diffraction and scanning electron microscope. The temperature dependence of resistivity and the magnetoresistance in the applied field of 3000 Oe are measured. It is observed that the metal-insulator transition temperature (Tp) is improved above 20 K approximately up to 280 K compared with that of LCMO powder using the conventional solid state method without being coated by Cu; meanwhile, a second broad peak occurs in low temperature in the resistivity-temperature curve when sintering temperature is changed. Also an anisotropic magnetoresistance effect is observed

  14. Cu and Cu2O films with semi-spherical particles grown by electrochemical deposition

    International Nuclear Information System (INIS)

    Zheng, Jin You; Jadhav, Abhijit P.; Song, Guang; Kim, Chang Woo; Kang, Young Soo

    2012-01-01

    Cu and Cu 2 O films can be prepared on indium-doped tin oxide glass substrates by simple electrodeposition in a solution containing 0.1 M Cu(NO 3 ) 2 and 3 M lactic acid at different pH values. At low pH (pH = 1.2), the uniform Cu films were obtained; when pH ≥ 7, the pure Cu 2 O films can be deposited. Especially, at pH = 11, the deposited Cu 2 O films exhibited cubic surface morphology exposing mainly {100} plane; in contrast, the films consisting of semi-spherical particles were obtained when the solution was being stirred for 2 weeks prior to use. The possible growth process and mechanism were comparatively discussed. - Highlights: ► Cu and Cu 2 O films were prepared by facile electrodeposition. ► Electrodeposition was preformed in electrolyte at different pH values. ► Dendritic Cu films were obtained at 1.2 pH with relatively high deposition potential. ► Semi-spherical Cu 2 O films were obtained with solution at 11 pH and stirred for 2 weeks. ► The possible growth mechanism of semi-spherical Cu 2 O films was discussed.

  15. Investigation of gallium redistribution processes during Cu(In,Ga)Se{sub 2} absorber formation from electrodeposited/annealed oxide precursor films

    Energy Technology Data Exchange (ETDEWEB)

    Sidali, T., E-mail: tarik.sidali@edf.fr; Duchatelet, A.; Chassaing, E.; Lincot, D.

    2015-05-01

    A way to prepare metallic precursors for CuIn{sub 1−x},Ga{sub x}Se{sub 2} (CIGS) solar cells has been recently introduced leading to efficiencies above 12.4%. It consists in the electrodeposition of Cu-In-Ga mixed oxides in an acidic nitrate aqueous solution followed by thermal reduction and selenization. This paper investigates, in a first part, the nucleation and growth mechanisms taking place during the co-electrodeposition of Cu-In-Ga oxide/hydroxide film. Scanning Electron Microscope observations coupled to Energy Dispersive X-ray spectrometry point out that the deposition is initiated by the formation of metallic copper nuclei. These nuclei enable the growth of Cu-In-Ga oxide film. This observation confirms that freshly deposited copper catalyzes nitrate reduction leading to an increase in the surface pH enabling the precipitation of the Cu-In-Ga hydroxides. In a second part, precursor films were elaborated with increasing Ga(NO{sub 3}){sub 3} concentration. After reduction of the films in hydrogen and selenization heat treatments, X-ray diffraction analysis shows the incorporation of Ga into the CIGS phase with increasing Ga content in the optimal composition range for photovoltaic applications (x = 0.25-0.34). Gallium composition profiles are evidenced in the films with a tendency to higher concentration near the Mo surface. Increasing annealing temperature allows a better homogenization of Ga in the film. The consequences are correlated to optoelectronic measurements (Eg and cell efficiency) with bandgap measurement and cell efficiencies (10 to 12%). - Highlights: • Electrodeposition starts with copper nucleation. • Gallium content in the precursor is tuned by Ga(III) concentration. • Increasing selenization temperature promotes Ga homogenization in CIGS.

  16. Processing of CuInSe{sub 2}-based solar cells: Characterization of deposition processes in terms of chemical reaction analyses. Phase 2 Annual Report, 6 May 1996--5 May 1997

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, T.

    1999-10-20

    This report describes research performed by the University of Florida during Phase 2 of this subcontract. First, to study CIGS, researchers adapted a contactless, nondestructive technique previously developed for measuring photogenerated excess carrier lifetimes in SOI wafers. This dual-beam optical modulation (DBOM) technique was used to investigate the differences between three alternative methods of depositing CdS (conventional chemical-bath deposition [CBD], metal-organic chemical vapor deposition [MOCVD], and sputtering). Second, a critical assessment of the Cu-In-Se thermochemical and phase diagram data using standard CALPHAD procedures is being performed. The outcome of this research will produce useful information on equilibrium vapor compositions (required annealing ambients, Sex fluxes from effusion cells), phase diagrams (conditions for melt-assisted growth), chemical potentials (driving forces for diffusion and chemical reactions), and consistent solution models (extents of solid solutions and extending phase diagrams). Third, an integrated facility to fabricate CIS PV devices was established that includes migration-enhanced epitaxy (MEE) for deposition of CIS, a rapid thermal processing furnace for absorber film formation, sputtering of ZnO, CBD or MOCVD of CdS, metallization, and pattern definition.

  17. To Enhance Performance of Light Soaking Process on ZnS/CuIn1-xGaxSe2 Solar Cell

    Directory of Open Access Journals (Sweden)

    Yu-Jen Hsiao

    2013-01-01

    Full Text Available The ZnS/CuInGaSe2 heterojunction solar cell fabricated on Mo coated glass is studied. The crystallinity of the CIGS absorber layer is prepared by coevaporated method and the ZnS buffer layer with a band gap of 3.21 eV. The MoS2 phase was also found in the CuInGaSe2/Mo system form HRTEM. The light soaking effect of photoactive film for 10 min results in an increase in F.F. from 55.8 to 64%, but series resistivity from 7.4 to 3.8 Ω. The efficiency of the devices improved from 8.12 to 9.50%.

  18. Analysis of sulphurisation processes of electrodeposited S-rich CuIn (S,Se){sub 2} layers for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Izquierdo-Roca, V.; Fontane, X. [EME/CERMAE/IN2UB, Departament d' Electronica, Universitat de Barcelona, C. Marti i Franques 1, 08028 Barcelona (Spain); Calvo-Barrio, L. [EME/CERMAE/IN2UB, Departament d' Electronica, Universitat de Barcelona, C. Marti i Franques 1, 08028 Barcelona (Spain); Lab. Analisis de Superficies, SCT, Univ. Barcelona, C. Lluis Sole i Sabaris 1-3, 08028 Barcelona (Spain); Perez-Rodriguez, A. [EME/CERMAE/IN2UB, Departament d' Electronica, Universitat de Barcelona, C. Marti i Franques 1, 08028 Barcelona (Spain)], E-mail: perez-ro@el.ub.es; Morante, J.R. [EME/CERMAE/IN2UB, Departament d' Electronica, Universitat de Barcelona, C. Marti i Franques 1, 08028 Barcelona (Spain); Alvarez-Garcia, J. [Centre de Recerca i Investigacio de Catalunya (CRIC), Travessera de Gracia 108, 08012 Barcelona (Spain); Duault, F.; Parissi, L.; Bermudez, V. [IRDEP, Institute of Research and Development of Photovoltaic Energy (UMR 71714, CNRS/EDF/ENSCP), 6 Quai Watier - BP 49, 78401 Chatou cedex (France)

    2009-02-02

    This work reports a microstructural analysis of S-rich CuIn (S,Se){sub 2} layers produced by electrodeposition of CuInSe{sub 2} precursors followed by annealing at 500 deg. C under sulphurising conditions, as function of the annealing time (t{sub ann}). The characterisation of the layers by Raman scattering (RS) and Scanning Electron Microscopy (SEM) techniques has allowed to observe a strong dependence of the layer microstructure and the secondary phases synthesised during the sulphurising step on the annealing parameters. The experimental data show the existence of two distinct regimes: For t{sub ann} < 20 min, increasing t{sub ann} leads to a significant improvement of the crystalline quality of the absorbers. For longer annealing times, the changes observed in the frequency of the main CuIn (S,Se){sub 2} A{sub 1} mode in the Raman spectra have been attributed to a higher incorporation of S in the chalcopyrite lattice. The characterisation of devices fabricated with these absorbers has allowed to analyse the impact of the microstructural features on the parameters of the solar cells, observing the existence of a strong correlation between the solar cell parameters and the spectral features of the main Raman mode.

  19. Vacancy behavior in Cu(In{sub 1−x}Ga{sub x})Se{sub 2} layers grown by a three-stage coevaporation process probed by monoenergetic positron beams

    Energy Technology Data Exchange (ETDEWEB)

    Uedono, Akira; Islam, Muhammad M.; Sakurai, Takeaki [Division of Applied Physics, Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Hugenschmidt, Christoph [Physics Department E21 and Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, 85748 Garching (Germany); Egger, Werner [Universität der Bundeswehr München, Institut für Angewandte Physik und Messtechnik, 85577 Neubiberg (Germany); Scheer, Roland; Krause-Rehberg, Reinhard [Department of Physics, Martin Luther University Halle, 06099 Halle (Germany); Akimoto, Katsuhiro [Division of Applied Physics, Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan)

    2016-03-31

    Vacancy-type defects in Cu(In{sub 1−x}Ga{sub x})Se{sub 2} (x ≅ 0.45 and 1) grown by a three-stage coevaporation process were probed using monoenergetic positron beams. Measurements of Doppler broadening spectra of the annihilation radiation and positron lifetime spectra showed that two different defect species coexist in the Cu(In{sub 1−x}Ga{sub x})Se{sub 2} layers, and these were identified as mono/divacancy-type defects and vacancy clusters, respectively. The vacancy clusters were mainly introduced during the third growth stage, and were located in the subsurface region. The concentration of the defects affected the short-circuit current density and the conversion efficiency of the solar cells. The defect concentration and their depth distributions varied depending on Se beam equivalent pressure, growth time, and post-growth annealing time. The behavior of the vacancy-type defects is discussed also with respect to results obtained using an electron probe micro-analyzer. - Highlights: • We applied positron annihilation to characterize Cu(In{sub 1−x}Ga{sub x})Se{sub 2}. • Defect species were identified as mono/divacancy-type defects and vacancy clusters. • The conversion efficiency increased with a decreasing vacancy concentration.

  20. Record critical current densities in IG processed bulk YBa{sub 2}Cu{sub 3}O{sub y} fabricated using ball-milled Y{sub 2}Ba{sub 1}Cu{sub 1}O{sub 5} phase

    Energy Technology Data Exchange (ETDEWEB)

    Muralidhar, Miryala; Kenta, Nakazato; Murakami, Masato [Department of Materials Science and Engineering, Superconducting Materials Laboratory, Shibaura Institute of Technology, Tokyo (Japan); Zeng, XianLin; Koblischka, Michael R. [Institute of Experimental Physics, Saarland University, Saarbruecken (Germany); Diko, Pavel [Institute of Experimental Physics, Material Physics Laboratory, Slovak Academy of Sciences, Kosice (Slovakia)

    2016-02-15

    The infiltration-growth (IG) technique enables the uniform and controllable Y{sub 2}BaCuO{sub 5} (Y211) secondary phase particles formation within the YBa{sub 2}Cu{sub 3}O{sub y} (Y123) matrix. Recent results clarified that the flux pinning performance of the Y123 material was dramatically improved by optimizing the processing conditions during the IG process. In this paper, we adapted the IG technique and produced several samples with addition of nanometer-sized Y211 secondary phase particles, which were produced by a ball milling technique. We found that the performance of the IG processed Y123 material dramatically improved in the low field region for a ball milling time of 12 h as compared to the samples without a ball milling step. Magnetization measurements showed a sharp superconducting transition with an onset T{sub c} at around 92 K. The critical current density (J{sub c}) at 77 K and zero field was determined to be 224 022 Acm{sup -2}, which is higher than the not ball-milled sample. Furthermore, microstructural observations exhibited a uniform microstructure with homogenous distribution of nanosized Y-211 inclusions within the Y-123 matrix. The improved performance of the Y-123 material can be understood in terms of fine distribution of the secondary phases. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Facile synthesis of dendritic Cu by electroless reaction of Cu-Al alloys in multiphase solution

    Science.gov (United States)

    Wang, Ying; Liang, Shuhua; Yang, Qing; Wang, Xianhui

    2016-11-01

    Two-dimensional nano- or micro-scale fractal dendritic coppers (FDCs) were synthesized by electroless immersing of Cu-Al alloys in hydrochloric acid solution containing copper chloride without any assistance of template or surfactant. The FDC size increases with the increase of Al content in Cu-Al alloys immersed in CuCl2 + HCl solution. Compared to Cu40Al60 and Cu45Al55 alloys, the FDC shows hierarchical distribution and homogeneous structures using Cu17Al83 alloy as the starting alloy. The growth direction of the FDC is , and all angles between the trunks and branches are 60°. Nanoscale Cu2O was found at the edge of FDC. Interestingly, nanoporous copper (NPC) can also be obtained through Cu17Al83 alloy. Studies showed that the formation of FDC depended on two key factors: the potential difference between CuAl2 intermetallic and α-Al phase of dual-phase Cu-Al alloys; a replacement reaction that usually occurs in multiphase solution. The electrochemical experiment further proved that the multi-branch dendritic structure is very beneficial to the proton transfer in the process of catalyzing methanol.

  2. Effect of defect on the nonlinear and dielectric property of Ca{sub (1–x)}Sr{sub x}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics synthesized by sol–gel process

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tao; Liu, Dewei; Dai, Haiyang; Xiang, Huiwen [Department of Technology and Physics, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Chen, Zhenping, E-mail: chaodaotai@126.com [Department of Technology and Physics, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); He, Huifang; Chen, Zhiquan [Department of Physics, Hubei Nuclear Solid Physics Key Laboratory, Wuhan University, Wuhan 430072 (China)

    2014-06-25

    Highlights: • Ca{sub (1−x)}Sr{sub x}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics are synthesized by sol–gel process. • Positron annihilation lifetime spectra is used to investigate the defects of samples. • Nonlinear and dielectric properties are controlled by density and defects of samples. - Abstract: Ca{sub (1−x)}Sr{sub x}Cu{sub 3}Ti{sub 4}O{sub 12} (x = 0, 0.05, 0.1, 0.15, 0.2, 0.3 and 0.4) ceramics are synthesized by sol–gel process. The XRD patterns show that weak peaks of Sr{sub 4}Ti{sub 3}O{sub 10}, TiO{sub 2} and Ca{sub 1.7}Sr{sub 0.3}CuO{sub 3} begin to appear at x ⩾ 0.2. Sr-doping is conductive to increase the density and reduce the defect concentration Ca{sub (1−x)}Sr{sub x}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics as x ⩽ 0.15. With increasing x (0.2 ⩽ x ⩽ 0.4), Sr-doping reduces the density and enhances the concentration of defects for the ceramics. The nonlinear coefficient value increases and reaches a maximum 13.5 at x = 0.15, and then decreases gradually with increasing x. The dielectric properties demonstrate that, as x ⩽ 0.15, Sr-doping not only increases the dielectric permittivity value and decreases the dielectric loss but also reduces the dependence on frequency at low frequencies. With increasing x (0.2 ⩽ x ⩽ 0.4), Sr-doping begins to lead to an inverse result in dielectric behaviors. The nonlinear and dielectric properties of Ca{sub (1−x)}Sr{sub x}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics are directly controlled by the density and defects.

  3. Antimicrobial Cu-bearing stainless steel scaffolds

    International Nuclear Information System (INIS)

    Wang, Qiang; Ren, Ling; Li, Xiaopeng; Zhang, Shuyuan; Sercombe, Timothy B.; Yang, Ke

    2016-01-01

    Copper-bearing stainless steel scaffolds with two different structures (Body Centered Cubic and Gyroid labyrinth) at two solid fractions (25% and 40%) were fabricated from both 316L powder and a mixture of 316L and elemental Cu powder using selective laser melting, and relative 316L scaffolds were served as control group. After processing, the antimicrobial testing demonstrated that the 316L-Cu scaffolds presented excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus, and the cell viability assay indicated that there was no cytotoxic effect of 316L-Cu scaffolds on rat marrow mesenchymal stem cells. As such, these have the potential to reduce implant-associated infections. The Cu was also found to homogeneously distribute within the microstructure by scanning electronic microcopy. The addition of Cu would not significantly affect its strength and stiffness compared to 316L scaffold, and the stiffness of all the scaffolds (3-20GPa) is similar to that of bone and much less than that of bulk stainless steel. Consequently, fabrication of such low stiffness porous structures, especially coupled with the addition of antimicrobial Cu, may provide a new direction for medical stainless steels. - Highlights: • 316L-Cu scaffolds were fabricated by using selective laser melting (SLM). • 316L-Cu scaffolds showed satisfied antimicrobial activities. • 316L-Cu scaffolds have no cytotoxic effect on normal cells. • Other properties of 316L-Cu scaffolds were similar to 316L scaffolds. • 316L-Cu scaffolds have the potential to be used in orthopedic applications.

  4. Antimicrobial Cu-bearing stainless steel scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qiang, E-mail: mfqwang@163.com [School of Stomatology, China Medical University, Shenyang 110002 (China); Ren, Ling [Institute of Metal Research, Chinese Academy of Sciences (China); Li, Xiaopeng [School of Mechanical and Chemical Engineering, The University of Western Australia (Australia); Zhang, Shuyuan [Institute of Metal Research, Chinese Academy of Sciences (China); Sercombe, Timothy B., E-mail: tim.sercombe@uwa.edu.au [School of Mechanical and Chemical Engineering, The University of Western Australia (Australia); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences (China)

    2016-11-01

    Copper-bearing stainless steel scaffolds with two different structures (Body Centered Cubic and Gyroid labyrinth) at two solid fractions (25% and 40%) were fabricated from both 316L powder and a mixture of 316L and elemental Cu powder using selective laser melting, and relative 316L scaffolds were served as control group. After processing, the antimicrobial testing demonstrated that the 316L-Cu scaffolds presented excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus, and the cell viability assay indicated that there was no cytotoxic effect of 316L-Cu scaffolds on rat marrow mesenchymal stem cells. As such, these have the potential to reduce implant-associated infections. The Cu was also found to homogeneously distribute within the microstructure by scanning electronic microcopy. The addition of Cu would not significantly affect its strength and stiffness compared to 316L scaffold, and the stiffness of all the scaffolds (3-20GPa) is similar to that of bone and much less than that of bulk stainless steel. Consequently, fabrication of such low stiffness porous structures, especially coupled with the addition of antimicrobial Cu, may provide a new direction for medical stainless steels. - Highlights: • 316L-Cu scaffolds were fabricated by using selective laser melting (SLM). • 316L-Cu scaffolds showed satisfied antimicrobial activities. • 316L-Cu scaffolds have no cytotoxic effect on normal cells. • Other properties of 316L-Cu scaffolds were similar to 316L scaffolds. • 316L-Cu scaffolds have the potential to be used in orthopedic applications.

  5. Effects of diethanolamine on sol–gel–processed Cu{sub 2}ZnSnS{sub 4} photovoltaic absorber thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kahraman, S., E-mail: suleymanmku@gmail.com; Çetinkaya, S.; Çetinkara, H.A.; Güder, H.S.

    2014-02-01

    Highlights: • DEA content significantly affected the crystal structure and the phase purity. • The films’ crystallite sizes increased with increasing DEA content. • Two different impurity levels were found for each film via R-T characteristics. • Under different illuminations, the n-Si/CZTS exhibited good photo-response. • The light on/off current ratios confirmed the photo-sensitivity of the junction. - Abstract: As a promising solar absorber, the Cu{sub 2}ZnSnS{sub 4} compound has been popular recently for the production of green and economical thin-film solar cells owing to the abundancy and non-toxicity of all the constituents. In this study, we have produced Cu{sub 2}ZnSnS{sub 4} films via the sol–gel technique. As a stabilizer, the effects of the diethanolamine on the properties of the films were investigated. The amount of diethanolamine significantly affected the crystal structure, crystallite sizes and phase purity of the films. X-ray diffraction and Raman spectroscopy analyses confirmed the formation of phase-pure CZTS films. It was found that the film produced by using 2 ml of diethanolamine in sol exhibited pure CZTS phase, compact and dense morphology and enhanced photo-sensitivity. Light on/off current ratio of the n-Si/Cu{sub 2}ZnSnS{sub 4} junction was found to be 47 under 100 mW/cm{sup 2} of illumination. Electrical activation energies of the films were investigated and the variations were attributed to delocalized phonon states generating from the presence of other phases and lattice defects.

  6. The effect of the melt spinning processing parameters on the solidification structures in Ti-30 at.% Ni-20 at.% Cu shape memory alloys

    International Nuclear Information System (INIS)

    Kim, Yeon-wook; Yun, Young-mok; Nam, Tae-hyun

    2006-01-01

    Solidification structures and shape memory characteristics of Ti-30 at.% Ni-20 at.% Cu alloy ribbons prepared by melt spinning were investigated by means of differential scanning calorimetry and X-ray diffraction. In these experiments particular attention has been paid to change the ejection temperature of the melt from 1350 to 1500 deg. C and the velocity of cooling wheel from 33 to 55 m/s. Then the cooling rates of ribbons were controlled. The effect of this cooling rate on solidification structures and martensitic transformation behaviors is discussed

  7. Use of multivariate statistical tool for data processing in the analysis of Cu, Cr, Fe, Pb, Mo and Mg in lubricating oil by LIBS

    International Nuclear Information System (INIS)

    Alves, Luana F.N.; Sarkis, Jorge E.S.; Bordon, Isabela C.A.C.

    2015-01-01

    Analysis of industrial lubricants is widely used for monitoring and predicting maintenance requirements in a broad range of mechanical systems. Laser induced breakdown spectroscopy has been used to evaluate the potentiality of the technique for the determination of metals in lubricating oils. Prior to quantitative analysis, the LIBS system was calibrated using standard samples containing the elements investigated (Cu, Cr, Fe, Pb, Mo and Mg). This study presents the usefulness of multivariate statistical techniques for evaluation and interpretation of large complex data sets in order to get more information about concentration of metals in oils lubricants is related to engine wear. (author)

  8. Steps Towards Industrialization of Cu-III-VI2Thin-Film Solar Cells:Linking Materials/Device Designs to Process Design For Non-stoichiometric Photovoltaic Materials.

    Science.gov (United States)

    Hwang, Huey-Liang; Chang, Hsueh-Hsin; Sharma, Poonam; Letha, Arya Jagadhamma; Shao, Lexi; Zhang, Yafei; Tseng, Bae-Heng

    2016-10-01

    The concept of in-line sputtering and selenization become industrial standard for Cu-III-VI 2 solar cell fabrication, but still it's very difficult to control and predict the optical and electrical parameters, which are closely related to the chemical composition distribution of the thin film. The present review article addresses onto the material design, device design and process design using parameters closely related to the chemical compositions. Its variation leads to change in the Poisson equation, current equation, and continuity equation governing the device design. To make the device design much realistic and meaningful, we need to build a model that relates the opto-electrical properties to the chemical composition. The material parameters as well as device structural parameters are loaded into the process simulation to give a complete set of process control parameters. The neutral defect concentrations of non-stoichiometric CuMSe 2 (M = In and Ga) have been calculated under the specific atomic chemical potential conditions using this methodology. The optical and electrical properties have also been investigated for the development of a full-function analytical solar cell simulator. The future prospects regarding the development of copper-indium-gallium-selenide thin film solar cells have also been discussed.

  9. Epitaxial growth of Cu on Cu(001): Experiments and simulations

    International Nuclear Information System (INIS)

    Furman, Itay; Biham, Ofer; Zuo, Jiang-Kai; Swan, Anna K.; Wendelken, John

    2000-01-01

    A quantitative comparison between experimental and Monte Carlo simulation results for the epitaxial growth of Cu/Cu(001) in the submonolayer regime is presented. The simulations take into account a complete set of hopping processes whose activation energies are derived from semiempirical calculations using the embedded-atom method. The island separation is measured as a function of the incoming flux and the temperature. A good quantitative agreement between the experiment and simulation is found for the island separation, the activation energies for the dominant processes, and the exponents that characterize the growth. The simulation results are then analyzed at lower coverages, which are not accessible experimentally, providing good agreement with theoretical predictions as well

  10. Optimisation of thallium ''1223'' high-temperature superconducting wire by a single-stage cold deformation process. [TlPbSrCaCuO

    Energy Technology Data Exchange (ETDEWEB)

    Glowacki, B A [IRC in Superconductivity, Cambridge (United Kingdom) Materials Science and Metallurgy, Cambridge (United Kingdom); Ashworth, S P [BICC Cables Ltd., Erith (United Kingdom)

    1992-09-15

    Superconducting tapes containing (Tl[sub 0.5]Pb[sub 0.5])Sr[sub 2]Ca[sub 2]Cu[sub 3]O[sub 9] were manufactured by a powder-in-tube technique and a single annealing stage. The (Tl[sub 0.5]Pb[sub 0.5])Sr[sub 2]Ca[sub 2]Cu[sub 3]O[sub 9] forms a ''1223'' structure with a Tc of over 120 K. A cold pressing stage was found to be necessary to achieve the higher J[sub c] values at 77 K. The transport J[sub c] was found to depend on: the annealing temperature, annealing time and pressing pressure. SEM examination of the Tl-1223 grain structure showed a marked difference between rolled and pressed tapes. This is ascribed to the production of a lead-rich phase during pressing, this is supported by XRD evidence. No significant degree of grain alignment was found in the Tl-1223 tapes, either by XRD analysis or by the measurement of transport critical current in applied magnetic fields. (orig.).

  11. Effects of forming temperature and sintering rate to the final properties of FeCuAl powder compacts formed through uniaxial die compaction process

    Science.gov (United States)

    Rahman, M. M.; Ismail, M. A.; Sopyan, I.; Rahman, H. Y.

    2018-01-01

    This paper presents the outcomes of an experimental investigation on the effects of forming temperature and sintering schedule to the final characteristics of FeCuAl powder mass formed at different temperature and sintered at different schedule. A lab-scale uni-axial die compaction rig was designed and fabricated which enabled the compaction of powder mass at room temperature as well as elevated temperature. Iron (Fe) powder ASC 100.29 was mechanically mixed with other elemental powders, namely copper (Cu), and aluminum (Al) for 60 minutes and compacted at three different temperature, i.e., 30°C, 150°C, and 200°C by applying 425 MPa of simultaneous downward and upward axial loading to generate green compacts. The as-pressed samples were inspected visually and the defect-free green compacts were subsequently sintered in an argon gas fired furnace at 800°C for 60 min at three different heating/cooling rates, i.e., 5, 10, and 15°C/min, respectively. The sintered samples were then characterised for their physical, electrical, and mechanical properties. The microstructures of the sintered samples were also analysed. The results revealed that a forming temperature of 150°C and a sintering rate of 10°C/min could produce a product with better characteristics.

  12. Effect of processing routes on microstructure, electrical and dielectric behavior of Mg-doped CaCu3Ti4O12 electro-ceramic

    Science.gov (United States)

    Singh, Laxman; Rai, U. S.; Mandal, K. D.; Rai, Alok Kumar

    2013-09-01

    In the present communication, data on magnesium-doped calcium copper titanate CaCu2.90Mg0.10Ti4O12 (CCMTO) electro-ceramic, synthesized by the semi-wet route (SWR), ball-milled route (BMR) and solid-state route (SSR), is characterized by TG-DTA, XRD, SEM, EDX and TEM techniques. XRD confirmed the formation of single phase in CCMTO ceramic. The CuO phase present at grain boundaries in SWR ceramic was shown by the SEM micrograph, which was verified by EDX. The TEM image of SWR ceramic shows nanocrystalline particles in the range 80±20 nm. The value of the dielectric constant of SWR ( ɛ r ˜20091) ceramic is higher than those of BMR and SSR ( ɛ r ˜1247) ceramics at 1 kHz at 450 K. A dielectric relaxation has been observed in the frequency range 100 Hz-100 kHz. The high-temperature dielectric dispersion shows one large low-frequency response and two Debye-type relaxations. The impedance and modulus studies show the highest grain-boundary resistance for BMR ceramic.

  13. Effect of heat treatments and window layer processing on the characteristics of CuInGaSe{sub 2} thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ramanathan, K.; Contreras, M.A.; Tuttle, J.R. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    Interaction between chemical bath deposited CdS and ZnO window layers are a focus of this paper. Low temperature anneals were used to follow the changes at the interface. Optical absorption spectra show that CdS and ZnO intermix upon annealing. When applied to ZnO/CdS/CuInGaSe{sub 2} thin film solar cells, changes in the short and long wavelength response were observed. The latter is attributed to an increase in the energy gap of the absorber by diffusion of S. The interdiffusion is shown to increase the short wavelength collection, and hence the current density of the devices. Photoluminescence data provides some indication of the quality of the interface.

  14. Band gap grading and photovoltaic performance of solution-processed Cu(In,Ga)S2 thin-film solar cells.

    Science.gov (United States)

    Sohn, So Hyeong; Han, Noh Soo; Park, Yong Jin; Park, Seung Min; An, Hee Sang; Kim, Dong-Wook; Min, Byoung Koun; Song, Jae Kyu

    2014-12-28

    The photophysical properties of CuInxGa1-xS2 (CIGS) thin films, prepared by solution-based coating methods, are investigated to understand the correlation between the optical properties of these films and the electrical characteristics of solar cells fabricated using these films. Photophysical properties, such as the depth-dependent band gap and carrier lifetime, turn out to be at play in determining the energy conversion efficiency of solar cells. A double grading of the band gap in CIGS films enhances solar cell efficiency, even when defect states disturb carrier collection by non-radiative decay. The combinational stacking of different density films leads to improved solar cell performance as well as efficient fabrication because a graded band gap and reduced shunt current increase carrier collection efficiency. The photodynamics of minority-carriers suggests that the suppression of defect states is a primary area of improvement in CIGS thin films prepared by solution-based methods.

  15. Effect of annealing temperature on a single step processed Cu{sub 2}ZnSnS{sub 4} thin film via solution method

    Energy Technology Data Exchange (ETDEWEB)

    Prabeesh, P.; Selvam, I. Packia; Potty, S.N.

    2016-05-01

    Cu{sub 2}ZnSnS{sub 4} (CZTS) is a promising material for thin film solar cell applications because of its excellent photovoltaic properties, high abundance and non-toxicity. Thin films of CZTS are generally fabricated by vacuum based techniques or by using toxic solvents and these routes reduce its attention as a low cost and environmental friendly material. In this study, we have prepared CZTS through a solution based single step approach using non-toxic chemicals by spin coating and studied the effect of annealing temperature in the range 350–550 °C in nitrogen atmosphere on structural, optical and electrical properties. XRD results revealed the formation of kesterite phase at all annealing temperatures, while the Raman studies indicated Cu{sub 2}SnS{sub 2} impurity phase in the film annealed at 550 °C. Band gap of the films annealed in nitrogen varies from 1.46 eV to 1.56 eV, depending on the annealing temperature. Optimum properties, such as, good crystallinity, dense structure, ideal band gap (1.49 eV) and good absorption coefficient (10{sup 4} cm{sup −1}), were obtained for the film annealed at 500 °C for 30 min in nitrogen. - Highlights: • Prepared CZTS film through one-step liquid based approach using non-toxic chemicals. • Studied the effect of N{sub 2} annealing on structural, optical and electrical properties. • The phase pure CZTS absorber film exhibited excellent photovoltaic properties • The film annealed at 500 °C for 30 min in nitrogen exhibited optimum properties.

  16. Low-Temperature Cu-Cu Bonding Using Silver Nanoparticles Fabricated by Physical Vapor Deposition

    Science.gov (United States)

    Wu, Zijian; Cai, Jian; Wang, Junqiang; Geng, Zhiting; Wang, Qian

    2018-02-01

    Silver nanoparticles (Ag NPs) fabricated by physical vapor deposition (PVD) were introduced in Cu-Cu bonding as surface modification layer. The bonding structure consisted of a Ti adhesive/barrier layer and a Cu substrate layer was fabricated on the silicon wafer. Ag NPs were deposited on the Cu surface by magnetron sputtering in a high-pressure environment and a loose structure with NPs was obtained. Shear tests were performed after bonding, and the influences of PVD pressure, bonding pressure, bonding temperature and annealing time on shear strength were assessed. Cu-Cu bonding with Ag NPs was accomplished at 200°C for 3 min under the pressure of 30 MPa without a post-annealing process, and the average bonding strength of 13.99 MPa was reached. According to cross-sectional observations, a void-free bonding interface with an Ag film thickness of around 20 nm was achieved. These results demonstrated that a reliable low-temperature short-time Cu-Cu bonding was realized by the sintering process of Ag NPs between the bonding pairs, which indicated that this bonding method could be a potential candidate for future ultra-fine pitch 3D integration.

  17. Platinum-group elements, S, Se and Cu in highly depleted abyssal peridotites from the Mid-Atlantic Ocean Ridge (ODP Hole 1274A): Influence of hydrothermal and magmatic processes

    Science.gov (United States)

    Marchesi, Claudio; Garrido, Carlos J.; Harvey, Jason; González-Jiménez, José María; Hidas, Károly; Lorand, Jean-Pierre; Gervilla, Fernando

    2013-11-01

    Highly depleted harzburgites and dunites were recovered from ODP Hole 1274A, near the intersection between the Mid-Atlantic Ocean Ridge and the 15°20'N Fracture Zone. In addition to high degrees of partial melting, these peridotites underwent multiple episodes of melt-rock reaction and intense serpentinization and seawater alteration close to the seafloor. Low concentrations of Se, Cu and platinum-group elements (PGE) in harzburgites drilled at around 35-85 m below seafloor are consistent with the consumption of mantle sulfides after high degrees (>15-20 %) of partial melting and redistribution of chalcophile and siderophile elements into PGE-rich residual microphases. Higher concentrations of Cu, Se, Ru, Rh and Pd in harzburgites from the uppermost and lowest cores testify to late reaction with a sulfide melt. Dunites were formed by percolation of silica- and sulfur-undersaturated melts into low-Se harzburgites. Platinum-group and chalcophile elements were not mobilized during dunite formation and mostly preserve the signature of precursor harzburgites, except for higher Ru and lower Pt contents caused by precipitation and removal of platinum-group minerals. During serpentinization at low temperature (desulfurization to S-poor sulfides (mainly heazlewoodite) and awaruite. Contrary to Se and Cu, sulfur does not record the magmatic evolution of peridotites but was mostly added in hydrothermal sulfides and sulfate from seawater. Platinum-group elements were unaffected by post-magmatic low-temperature processes, except Pt and Pd that may have been slightly remobilized during oxidative seawater alteration.

  18. A new hybrid two-zone/crucible furnace process for the growth of epitaxial Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8} superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Siegal, M.P.; Overmyer, D.L.; Venturini, E.L.; Dominguez, F.; Padilla, R.R. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States)

    1998-12-01

    Epitaxial Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8} (Tl-2212) films {approximately}5500 {Angstrom} thick are grown on LaAlO{sub 3}(100) substrates using a new hybrid two-zone/crucible furnace process enabling precise control of thallination. This method combines the best features of both conventional crucible and two-zone processing for the first time: superb film properties and reduced handling of hazardous Tl-oxide powders. Single-phase, highly {ital c}-axis oriented Tl-2212 films are grown with smooth morphology, Meissner transition {approximately}103 K, and critical current density {approximately}1.1{times}10{sup 7}A/cm{sup 2} at 5 K for twenty consecutive runs without having to change or add to the Tl-oxide source. {copyright} {ital 1998 Materials Research Society.}

  19. Kinetics of photocurrent generation and an efficient charge separation of a dye-sensitized n-Cu2O/p-CuSCN junction photoelectrode in a solid-state photovoltaic cell

    International Nuclear Information System (INIS)

    Fernando, C A N; Kumara, N T R N; Gamage, T N

    2010-01-01

    A Cu/n-Cu 2 O/dye/p-CuSCN junction photoelectrode is fabricated to produce a solid-state dye-sensitized photovoltaic cell. Samples are characterized by XRD, SEM and surface resistivity measurements. Photocurrent generation is found due to light absorption of n-Cu 2 O thin film and dye sensitization between p-CuSCN and the dye. Kinetics of the photocurrent generation of the dye sensitization is studied solving the rate equations by the iteration method obtaining a relationship for the photocurrent quantum efficiency (Φ) depending on the surface concentration (D o ) of the dye and the rate constants of the reactions with connection to the dye sensitization process. The solution obtained in the steady state by iteration is found to be of the form Φ = AD o −BD o 2 (A and B are constants related to the reaction rates of the photocurrent generation process and the concentration of the n-Cu 2 O film). The variation of the n-Cu 2 O concentration with photocurrent is presented. A photocurrent enhancement is observed for the Cu/n-Cu 2 O/dye/p-CuSCN photovoltaic cell compared to that of Cu/n-Cu 2 O, Cu/p-CuSCN/dye and Cu/n-Cu 2 O/p-CuSCN photovoltaic cells. Good rectification characteristics are observed for the Cu/n-Cu 2 O/p-CuSCN photoelectrode compared to that of Cu/n-Cu 2 O and Cu/p-CuSCN photoelectrodes. Photocurrent enhancement is found due to the efficient charge separation process at the n–p junction. Energy band structures of the n–p junction are proposed according to the onset potentials which are used to discuss the mechanism of the efficient charge separation suppressing the recombination process

  20. Surface chemistry of 2-butanol and furfural on Cu, Au and Cu/Au single crystals

    OpenAIRE

    Megginson, Rory

    2016-01-01

    In this study, the adsorption of 2-butanol and furfural was investigated on Au (111), Cu (111) and Cu/Au (111) surfaces. It was hoped that by studying how these species adsorbed on these surfaces , insight would be provided into the roles of Cu and Au in the “hydrogen free” hydrogenation of furfural to furfuryl alcohol. This is a valuable process as currently furfuryl alcohol is derived from crude oil but it is possible to derive furfural from corn husk making it a greener process...

  1. Spectrographic determination of impurities in ammonium bifluoride. III. Study of the processes of vaporization, transport and excitation of the elements Al, B, Cu and Cr; Determinacion espectrografico de impurezas en bifluoruro amonico. III. Estudio de los procesos de volatilizacion, transporte y excitacion de los elementos Al, B, Cu, Cr

    Energy Technology Data Exchange (ETDEWEB)

    Alduan, F A; Roca, M; Capdevila, C

    1979-07-01

    The influences of the processes of vaporization, transport and excitation on the shape of the volatilization-excitation curves and on the values of the spectral-line intensities have been investigated in a method for the spectrographic determination of Al, B, Cu and Cr In ammonium bifluoride samples by direct current are excitation in Scribner type electrodes, with addition of different matrices (graphite, 63203, GeO{sub 2}, MgO and Zn0). The reaction products in the electrode cavity have been identified by X-ray powder diffraction analysis and the percentages of vaporized and diffused element evaluated through analysis by total-burning spectrographic methods. In addition, the values of both the number of particles entering the discharge column and the transport efficiencies have been calculated. Thus, the origin of most observed differences has been explained. (Author) 11 refs.

  2. Growth orientation and superconducting properties of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} films prepared by the low-fluorine sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Lei Li; Zhao Gaoyang; Xu Hui; Zhao Juanjuan, E-mail: leili813@gmail.co [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an 710048 (China)

    2010-08-15

    YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) films were deposited on (100)-oriented LaAlO{sub 3} (LAO) single crystal substrates by the dip-coating process using low-fluorine solution. Their microstructures were characterized with the aid of X-ray diffractometry, scanning electron microscopy and high-resolution transmission electron microscopy. Their superconducting properties were measured by the standard four-probe method. The experiment results show that the film obtained under high enough humidity conditions exhibits better c-axis texture and superconducting properties than the film under a relatively low humidity conditions. Based on the classical nucleation and chemical reaction thermodynamics theory, the underlying crystalline and growth mechanisms of YBCO films under certain humidity conditions are explained in combination with our experimental results. It is suggested that the unreacted intermediate phases such as BaF{sub 2} and CuO aggregated in the YBCO grain boundary will cause lattice distortion in the YBCO matrix and further induce the formation of a-axis oriented YBCO grains as crystallization proceeds. Therefore, it is believed that the relative content of water vapor within the heat-treatment atmosphere plays quite an important role in the preparation of c-axis oriented YBCO film with good superconducting properties. (semiconductor materials)

  3. Influence of Solution and Aging Treatment Conditions on the Formation of Ultrafine-Grained Structure of CuFe2 Alloy Processed by Rolling with Cyclic Movement of Rolls

    Directory of Open Access Journals (Sweden)

    Urbańczyk-Gucwa A.

    2016-06-01

    Full Text Available The effect of second phase particles on grain refinement in CuFe2 alloy has been investigated by using rolling with the cyclic movement of rolls (RCMR method. Two different population of second phase particles of Fe: coherent, about 10 nm in diameter and about 100 nm in size were obtained by applying aging treatment followed at 500°C for 2 h and at 700°C for 24 h respectively. In addition, solution treated samples were deformed by RCMR method at the same parameters. The microstructures of the CuFe2 alloy were analyzed using light microscope (LM, electron backscattered diffraction (EBSD microscope technique and scanning transmission electron microscope (STEM. The presence of high-density of coherent Fe particles in the matrix inhibits recovery process and in the result obtained grain/subgrain boundaries have diffused character and are weakly visible. The largest particles which are not coherent with the matrix act as an effective barrier against the boundary motion.

  4. Synthesis and photocatalytic activity of carbon spheres loaded Cu2O/Cu composites

    International Nuclear Information System (INIS)

    Li, Yinhui; Zhao, Mengyao; Zhang, Na; Li, Ruijuan; Chen, Jianxin

    2015-01-01

    Highlights: • Carbon spheres loaded Cu 2 O/Cu composites are obtained by hydrothermal process. • Cu 2 O/Cu nanocrystals grow on the surface of carbon spheres. • The composites with core–shell structure show highly photo-catalytic activity. • The composites can degrade methyl orange under simulated solar light irradiation. • The composites can be used to treat dye wastewater or organic pollutants. - Abstract: In this work, using amylose as carbon source and cupric acetate as copper source, carbon spheres loaded Cu 2 O/Cu composites were obtained by hydrothermal synthesis. The effects of the molar ratios between glucose and Cu(II), and hydrothermal time on the morphology and sizes of the composites were investigated. The result of photocatalytic experiments demonstrated that the composites could degrade methyl orange in aqueous solution under simulated solar light irradiation. The highest degradation rate was achieved to 93.83% when the composites were prepared by hydrothermal synthesis at 180 °C for 16 h and the molar ratio between glucose and Cu(II) was 10/1. The composites, as new and promising materials, can be used to treat dye wastewater or other organic pollutants

  5. Synthesis and characterization of micrometer Cu/PVP architectures

    International Nuclear Information System (INIS)

    Luo, Huajuan; Zhao, Yanbao; Sun, Lei

    2011-01-01

    Graphical abstract: A simple method for the synthesis of novel micrometer flower-like Cu/PVP architectures was introduced. Highlights: → Micrometer flower-like copper/polyvinylpyrrolidone architectures were obtained by a simple chemical route. → The amount of N 2 H 4 ·H 2 O, the reaction temperature, the molar ratio of CuCl 2 to PVP and different molecular weights of PVP play an important role in the controlling the morphology of the Cu/PVP architectures. → A possible mechanism of the formation of Cu/PVP architectures was discussed. -- Abstract: Micrometer-sized flower-like Cu/polyvinylpyrrolidone (PVP) architectures are synthesized by the reduction of copper (II) salt with hydrazine hydrate in aqueous solution in the presence of PVP capping agent. The resulting Cu/PVP architectures are investigated by UV-vis spectroscopy, transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). The Cu/PVP flowers have uniform morphologies with an average diameter of 10 μm, made of several intercrossing plates. The formation of Cu/PVP flowers is a new kinetic control process, and the factors such as the amount of N 2 H 4 ·H 2 O, reaction temperature, molar ratio of CuCl 2 to PVP and molecular weight of PVP have significant effect on the morphology of Cu/PVP architectures. A possible mechanism of the formation of micrometer Cu/PVP architectures was discussed.

  6. Diffusion processes in Cu-Al-Ni shape memory alloys studied by mechanical spectroscopy and in situ transmission electron microscopy at high temperatures

    International Nuclear Information System (INIS)

    No, M.L.; Ibarra, A.; Lopez-Echarri, A.; Bocanegra, E.H.; San Juan, J.

    2006-01-01

    We have studied the mobility of defects in the frozen β phase of the Cu-Al-Ni shape memory alloys by mechanical spectroscopy as a function of temperature. In parallel, we have characterized the microstructure and their evolution with over-heating treatments. Thermal treatments have been performed in situ in a transmission electron microscope by using a heating stage. Internal friction and modulus defect measurements have been correlated with the microstructural observations by transmission electron microscopy. We discuss the behavior of the internal friction spectra, corresponding to over-heating in the β-phase, and propose microscopic mechanisms responsible for the evolution when the material is not in thermal equilibrium. In particular, the dislocations became mobile in the temperature range between 750 and 800 K where the L2 1 atomic order changes to the B2 order. A relaxation peak has been observed in the equilibrium β phase domain, which has been examined in detail by isothermal measurements as a function of frequency. The activation enthalpy of the peak has been determined to be 3.05 ± 0.1 eV, and possible microscopic mechanisms responsible for the peak are discussed

  7. Effect of thermo-mechanical processing on the material properties at low temperature of a large size Al-Ni stabilized Nb-Ti/Cu superconducting cable

    Science.gov (United States)

    Langeslag, S. A. E.; Curé, B.; Sgobba, S.; Dudarev, A.; ten Kate, H. H. J.; Neuenschwander, J.; Jerjen, I.

    2014-01-01

    For future high-resolution particle experiments, a prototype for a 60 kA at 5 T, 4.2 K class conductor is realized by co-extrusion of a large, 40-strand Nb-Ti/Cu superconducting cable with a precipitation type Al-0.1wt.%Ni stabilizer. Microalloying with nickel contributes to the strength of the stabilizer, and avoids significant degradation in residual resistivity ratio, owing to its low solid solubility in aluminum. Sections of the conductor are work hardened to increase the mechanical properties of the as-extruded temper. Mechanical and resistivity characteristics are assessed as function of the amount of work hardening, at room temperature as well as at 4.2 K. Thermal treatments, like resin curing after coil winding, can cause partial annealing of the cold-worked material and reverse the strengthening effect. However, targeted thermal treatments, applied at relatively low temperature can result in precipitation hardening. The depletion of nickel in the aluminum-rich matrix around the precipitates results in an increased strength and a decreased effect of nickel on the thermal and electrical resistivity of the material. The present work aims at identifying an optimal work hardening sequence, and an optimal thermal treatment, possibly coinciding with a suitable coil resin curing cycle, for the Al-Ni stabilized superconductor.

  8. Electronic defect study on low temperature processed Cu(In,Ga)Se2 thin-film solar cells and the influence of an Sb layer

    International Nuclear Information System (INIS)

    Van Puyvelde, L; Lauwaert, J; Devulder, W; Detavernier, C; Vrielinck, H; Tempez, A; Nishiwaki, S; Pianezzi, F; Tiwari, A N

    2015-01-01

    A way to lower the manufacturing cost of Cu(In,Ga)Se 2 (CIGS) thin-film solar cells is to use flexible polymer substrates instead of rigid glass. Because such substrates require lower temperature during absorber deposition, the grain growth of the absorber layer can be hindered which leads to a lower cell performance. Partial compensation of this efficiency loss might be accomplished by growing the absorber in the presence of Sb, which is reported to promote grain growth. In this work CIGS solar cells, deposited on glass substrates, at a reduced substrate temperature with a thin Sb layer (7, 12 nm) on top of the Mo contact are investigated. The diffusion profile of Sb is measured with plasma profiling time of flight mass spectrometry. The beneficial effect of Sb on efficiency and grain size is shown in quantum efficiency measurements and with scanning electron microscopy, respectively. Electric spectroscopy is used to explore the possible effects on the defect structure, more in particular on the dominant shallow acceptor. Admittance spectra exhibit a capacitance step to the geometric capacitance plateau at low temperature (5–60 K). Analyzing this capacitance step, we obtained a good estimate of the activation energy of the intrinsic defects that provide the p-type conductivity of the CIGS absorber. The measurements did not show a change in the nature of the dominant acceptor upon Sb treatment. (paper)

  9. Nanostructural characterization of artificial pinning centers in PLD-processed REBa{sub 2}Cu{sub 3}O{sub 7-δ} films

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, T. [Department of Materials Science and Engineering, Kyushu University, 744, Motooka, Nishi, Fukuoka 819-0395 (Japan); Kaneko, K., E-mail: kaneko@zaiko.kyushu-u.ac.jp [Department of Materials Science and Engineering, Kyushu University, 744, Motooka, Nishi, Fukuoka 819-0395 (Japan); Yamada, K.; Roy, A.; Sato, Y.; Teranishi, R. [Department of Materials Science and Engineering, Kyushu University, 744, Motooka, Nishi, Fukuoka 819-0395 (Japan); Kato, T. [Japan Fine Ceramics Center, 2-4-1, Mutsuno, Atsuta, Nagoya 456-8587 (Japan); Izumi, T. [Research Institute for Energy Conservation, Department of Energy and Environment, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba East, 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564 (Japan); Shiohara, Y. [Industrial Superconductivity Technology Research Association, KSP R& D Wing A-9F, 3-2-1 Sakado, Takatsu, Kawasaki, Kanagawa 213-0012 (Japan)

    2017-05-15

    In the context of high temperature superconductors, pulsed laser deposition derived GdBa{sub 2}Cu{sub 3}O{sub 7-δ} sample with BaHfO{sub 3} nanoparticles has been reported to achieve high current density and good I{sub C}-B-θ characteristics at high temperatures. Herein, we have carried out a thorough nanostrucural characterization of BaHfO{sub 3} nanoparticles embedded in GdBCO matrix using scanning transmission electron microscopy, with an emphasis on the dispersion behavior, morphologies and nanostrain, to understand the role of BaHfO{sub 3} nanoparticles. - Highlights: • There were two distinct regions available of the way nanoparticles being dispersed within the matrix. • Tilted nanoparticle were found inclined slightly towards opposite direction. • The morphological studies suggested that they were slightly distorted octagonal prism. • Local strains were present at the interface between small BHO nanorod and GdBCO matrix. • The amount of the local strain in the matrix was decreased gradually from the interface.

  10. Effects of magnetostatic interaction on the magnetization processes in Fe73.5Cu1Nb3Si13.5B9 nanocrystalline wires

    International Nuclear Information System (INIS)

    Li, Y.F.; Vazquez, M.; Chen, D.X.; Hernando, A.

    2002-01-01

    Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 amorphous wire was annealed at different temperatures (T a =400-700 deg. C, for 30 min) that result in partial devitrification and subsequently, the quasi-saturated hysteresis loop was measured. It is found that the loops are not symmetric, exhibiting two coercive fields, H c1 and H c2 , on descending and ascending branches, respectively. Moreover, the asymmetry degree is modified when the sample is previously magnetized under a field of 60 kA m -1 . The dependence on both maximum measured field, H m , and temperature, T, of the displaced loop has been determined. With increasing H m , the shift H sh =(H c2 +H c1 )/2 decreases and the coercivity H c =(H c2 -H c1 )/2 increases, but H sh -H c H c1 remains constant. Both H sh and the magnetic polarization, μ 0 M m , at maximum field decreases with elevating T. The loop of this sample also shows a remarkable time-effect. The H m - and T-dependent H sh is discussed considering the existence of an effective bias-field generated from the magnetostatic interaction between the nanocrystalline particles and residual soft matrix, and the time-effect could be ascribed to the dipolar interaction among the particles. (author)

  11. The stored energy in processed Cu-0.4 wt.%Cr-0.12 wt.%Zr-0.02 wt.%Si-0.05 wt.%Mg

    International Nuclear Information System (INIS)

    Li, X.F.; Dong, A.P.; Wang, L.T.; Yu, Z.; Meng, L.

    2011-01-01

    Research highlights: → The crystal orientation in processed Cu-0.4 wt.%Cr-0.12 wt.%Zr-0.02 wt.%Si-0.05 wt.%Mg is deviating from the as-cast specimens and microstrain of the alloy is gradually increasing as the draw ratio rising before η ≤ 6.7. → The dynamic recovery has taken place as 6.7 texture is formed with the draw ratio rising. Meanwhile, the stored energy also increases with the draw ratio rising and a peak is reached with draw ratio of 6.7. The release of stored energy is primarily due to the decrease of dislocation density. The flow stress estimated from the stored energy has a similar variation trend with the measured data with a stress difference ∼20 to 120 MPa. The main strengthening effect is attributed to dislocation mechanism.

  12. Effect of the post-deposition processing ambient on the preparation of superconducting YBa2Cu3O/sub 7-//sub x/ coevaporated thin films using a BaF2 source

    International Nuclear Information System (INIS)

    Chan, S.; Bagley, B.G.; Greene, L.H.; Giroud, M.; Feldmann, W.L.; Jenkin, K.R. II; Wilkins, B.J.

    1988-01-01

    We have investigated the effect of the post-deposition processing ambient on the preparation of YBa 2 Cu 3 O/sub 7-//sub x/ thin films from a BaF 2 source. The role of H 2 O vapor during the high-temperature anneal is understood through a thermodynamic analysis of the fluorine removal reaction. The role of a HF getter (e.g., SiO 2 ) is understood through the same type of analysis. We have demonstrated that a zero resistance transition temperature at 77 K can be obtained for an annealing temperature as low as 690 0 C for films deposited on SrTiO 3 substrates by increasing the P/sub H>2/O$ and decreasing P/sub HF/ during the high-temperature soak cycle

  13. Synthesis and characterization of bulk Cu2ZnSnX4 (X: S, Se) via thermodynamically supported mechano-chemical process

    International Nuclear Information System (INIS)

    Pareek, Devendra; Balasubramaniam, K.R.; Sharma, Pratibha

    2015-01-01

    Materials with the general formula, Cu 2 ZnSnX 4 (CZTX; X: Group 16 elements), with X being S/Se, have been receiving considerable attention due to their utility as an absorber layer in solar photovoltaics (PV). This paper reports on the synthesis of CZTSe and CZTS nanocrystalline powders at low temperatures, starting from elemental metal and chalcogen powders, via the low cost, scalable technique of ball milling. The prepared samples were well characterized using the different characterization tools. XRD, Raman, SEM and TEM studies confirm the formation of single-phase, stoichiometric, nano-crystalline kesterite CZTS and CZTSe powders. The low temperature phase selection of the complex quaternary compound in this system is seen as a direct consequence of the thermodynamic facilitation, coupled with the capability of mechano-chemical synthesis to aid in overcoming kinetic constraints. The optical bandgap of the various samples of CZTS was observed in the range of 1.4–1.6 eV and corresponding values for CZTSe was observed to be in the range of 1.08–1.18 eV. Our work provides a pathway for developing cheap, scalable, and ink-based techniques for low cost solar PV. - Graphical abstract: Display Omitted - Highlights: • A scalable route for synthesis of near phase pure CZTS/Se nano-crystals has been demonstrated. • Stoichiometric CZTS and CZTSe were synthesized via mechano-chemical synthesis route. • Synthesis at near room temperature is supported by thermodynamic calculations

  14. Influence of selenium amount on the structural and electronic properties of Cu(In,Ga)Se{sub 2} thin films and solar cells formed by the stacked elemental layer process

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, B.J., E-mail: bjm.mueller@web.de [Institute of Micro- and Nanomaterials, University of Ulm, D-89081 Ulm (Germany); Corporate Research, Robert Bosch GmbH, D-71272 Renningen (Germany); Opasanont, B.; Haug, V. [Corporate Research, Robert Bosch GmbH, D-71272 Renningen (Germany); Hergert, F. [Bosch Solar CISTech GmbH, D-14772 Brandenburg (Germany); Zweigart, S. [Corporate Research, Robert Bosch GmbH, D-71272 Renningen (Germany); Herr, U., E-mail: ulrich.herr@uni-ulm.de [Institute of Micro- and Nanomaterials, University of Ulm, D-89081 Ulm (Germany)

    2016-06-01

    In the following article the influence of selenium supply on the stacked elemental layer process during the final annealing step is investigated. We find that the Se supply strongly influences the phase formation in the Cu(In,Ga)Se {sub 2} resulting in a modified Ga/In distribution. The effects of Se supply on the structural and electronic properties of the films are reported. The solar cell performance has been investigated in detail using current voltage and external quantum efficiency measurements. We find that the chalcopyrite crystal formation is strongly influenced by the Se supply during the growth process. Furthermore the interdiffusion of Ga and In is accelerated with increasing Se amount. This has direct consequences on band gap and series resistance, which leads to changes in the values of short-circuit current density, open-circuit voltage and fill factor. The open-circuit voltage increases with increasing band gap of the Cu(In,Ga)Se {sub 2}, whereas the short-circuit current density decreases with increasing band gap. The fill factor is affected by the formation of MoSe {sub 2} at the back contact. The experimental findings are compared with the theoretical efficiency limits calculated from the Shockley–Queisser model, and also with numerical 1D SCAPS simulations. - Highlights: • Adjustment of the Ga/In distribution by the Se supply • Enhanced Ga incorporation near-surface • Interdiffusion coefficients of Ga/In are investigated. • Shockley–Queisser modeling and 1D SCAPS simulations • Fill factor is strongly coupled on the MoSe2/Mo ratio.

  15. Soldering-induced Cu diffusion and intermetallic compound formation between Ni/Cu under bump metallization and SnPb flip-chip solder bumps

    Science.gov (United States)

    Huang, Chien-Sheng; Jang, Guh-Yaw; Duh, Jenq-Gong

    2004-04-01

    Nickel-based under bump metallization (UBM) has been widely used as a diffusion barrier to prevent the rapid reaction between the Cu conductor and Sn-based solders. In this study, joints with and without solder after heat treatments were employed to evaluate the diffusion behavior of Cu in the 63Sn-37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure. The atomic flux of Cu diffused through Ni was evaluated from the concentration profiles of Cu in solder joints. During reflow, the atomic flux of Cu was on the order of 1015-1016 atoms/cm2s. However, in the assembly without solder, no Cu was detected on the surface of Ni even after ten cycles of reflow. The diffusion behavior of Cu during heat treatments was studied, and the soldering-process-induced Cu diffusion through Ni metallization was characterized. In addition, the effect of Cu content in the solder near the solder/intermetallic compound (IMC) interface on interfacial reactions between the solder and the Ni/Cu UBM was also discussed. It is evident that the (Cu,Ni)6Sn5 IMC might form as the concentration of Cu in the Sn-Cu-Ni alloy exceeds 0.6 wt.%.

  16. Fabrication and tensile properties of rapidly solidified Cu-10wt. %Ni alloy. [Cu-10Ni

    Energy Technology Data Exchange (ETDEWEB)

    Baril, D; Angers, R; Baril, J [Dept. of Mining and Metallurgy, Laval Univ., Ste-Foy, Quebec (Canada)

    1992-10-15

    Cu-10wt.%Ni ribbons were produced by melt spinning and cut into small particles with a blade cutter mill. The powders were then hot consolidated to full density by hot pressing followed by hot extrusion. Tensile properties of the resulting pieces were measured. Cu-10wt.%Ni cast ingots were also hot extruded and mechanically tested to compare with the rapidly solidified alloy and to evaluate the possible benefits brought by the rapid solidification process.

  17. Exploring Cu2O/Cu cermet as a partially inert anode to produce aluminum in a sustainable way

    International Nuclear Information System (INIS)

    Feng, Li-Chao; Xie, Ning; Shao, Wen-Zhu; Zhen, Liang; Ivanov, V.V.

    2014-01-01

    Highlights: • Cu 2 O/Cu cermet was used as a candidate partially inert anode material to produce aluminum alloys. • The thermal corrosion behavior of Cu 2 O/Cu was investigated in molten salt at 960 °C. • The corrosion rate is largely governed by the geometrical structures of Cu in the prepared samples. • The corrosion rate increases with decreasing sizes and increasing filling contents of Cu phase. • The corrosion rate was 1.8–9 cm/y and the Cu contents is less than 6.2 wt.% in the produced aluminum. - Abstract: As an energy-intensive process, aluminum production by the Hall–Héroult method accounts for significant emissions of CO 2 and some toxic greenhouse gases. The utilization of an inert anode in place of a carbon anode was considered as a revolutionary technique to solve most of the current environmental problems resulting from the Hall–Héroult process. However, the critical property requirements of the inert anode materials significantly limit the application of this technology. In light of the higher demand for aluminum alloys than for pure aluminum, a partially inert anode was designed to produce aluminum alloys in a more sustainable way. Here, Cu 2 O/Cu cermet was chosen as the material of interest. The thermal corrosion behavior of Cu 2 O/Cu was investigated in Na 3 AlF 6 –CaF 2 –Al 2 O 3 electrolyte at 960 °C to elucidate the corrosion mechanisms of this type of partially inert anode for the production of aluminum or aluminum alloys. Furthermore, the effects of the geometrical structure of the Cu phase on the thermal corrosion behavior of Cu 2 O/Cu cermet in the electrolyte were investigated as well. The thermal corrosion rate was evaluated by the weight loss method and the results show that the samples prepared with branch-like Cu have higher thermal corrosion rate than those prepared with spherical Cu, and the corrosion rate increases with decreasing size and increasing filling content of Cu phase. The calculated corrosion rate

  18. Optimisation of the solution heat treatment of Rheo-processed Al-Cu-Mg-(Ag) Alloys A206 and A201

    CSIR Research Space (South Africa)

    Masuku, EP

    2009-06-01

    Full Text Available The traditional solution treatment cycles that are currently applied to rheo-processed A201 are mostly those that are used for conventional castings. These solution treatments are not necessarily the optimum solution treatments for rheo...

  19. Based on Cu as framework constructed nanoporous CuO/Cu composites by a dealloy method for sodium-ion battery anode

    Science.gov (United States)

    Zheng, Tian; Li, Guangda; Li, Deming; Meng, Xiangeng

    2018-05-01

    Nanoporous CuO/Cu composites with a continuous channel structure were fabricated through a corroding Cu-Al alloy process. The width of the continuous channels was about 20 50 nm. Nanoporous structure could effectively sustain the volume expansion during the Na+ insertion/extraction process and shorten the Na+ diffusion length as well, which thus helps improve the Na+ storage performance. Moreover, the nanoporous structure can improve the contact area between the electrolyte and the electrode, leading to an increment in the number of Na+ insertion/extraction sites. When used as the anode for sodium-ion batteries, the CuO/Cu exhibited an initial capacity of 580 mAh g-1, and the capacity is maintained at 200 mAh g-1 after 200 cycles at a current density of 500 mA g-1.

  20. Room temperature Cu-Cu direct bonding using surface activated bonding method

    International Nuclear Information System (INIS)

    Kim, T.H.; Howlader, M.M.R.; Itoh, T.; Suga, T.

    2003-01-01

    Thin copper (Cu) films of 80 nm thickness deposited on a diffusion barrier layered 8 in. silicon wafers were directly bonded at room temperature using the surface activated bonding method. A low energy Ar ion beam of 40-100 eV was used to activate the Cu surface prior to bonding. Contacting two surface-activated wafers enables successful Cu-Cu direct bonding. The bonding process was carried out under an ultrahigh vacuum condition. No thermal annealing was required to increase the bonding strength since the bonded interface was strong enough at room temperature. The chemical constitution of the Cu surface was examined by Auger electron spectroscope. It was observed that carbon-based contaminations and native oxides on copper surface were effectively removed by Ar ion beam irradiation for 60 s without any wet cleaning processes. An atomic force microscope study shows that the Ar ion beam process causes no surface roughness degradation. Tensile test results show that high bonding strength equivalent to bulk material is achieved at room temperature. The cross-sectional transmission electron microscope observations reveal the presence of void-free bonding interface without intermediate layer at the bonded Cu surfaces

  1. Mechanochemical synthesis of Cu-Al and methyl orange intercalated Cu-Al layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Jun, E-mail: forsjun@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); He, Xiaoman; Chen, Min; Hu, Huimin [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Zhang, Qiwu, E-mail: zhangqw@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Liu, Xinzhong [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350118 China (China)

    2017-04-15

    In this study, a mechanochemical route to synthesize a Cu-Al layered double hydroxide (LDH) and a methyl orange (MO) intercalated one (MO-LDH) was introduced, in which basic cupric carbonate (Cu{sub 2}(OH){sub 2}CO{sub 3}) and aluminum hydroxide (Al(OH){sub 3}) with Cu/Al molar ratio at 2/1 was first dry ground for 2 h and then agitated in water or methyl orange solution for another 4 h to obtain the LDH and MO-LDH products without any heating operation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The products showed high crystallinity phase of Cu-Al and MO intercalated Cu-Al LDH with no evident impurities, proving that the craft introduced here was facile and effective. The new idea can be applied in other fields to produce organic-inorganic composites. - Highlights: • A facile mechanochemical route to synthesize Cu-Al and MO intercalated Cu-Al LDH. • The products possesses high crystalline of LDH phase with no impure phases. • The dry milling process induces the element substitution between the raw materials. • The agitation operation helps the grain growth of LDH.

  2. Mechanochemical synthesis of Cu-Al and methyl orange intercalated Cu-Al layered double hydroxides

    International Nuclear Information System (INIS)

    Qu, Jun; He, Xiaoman; Chen, Min; Hu, Huimin; Zhang, Qiwu; Liu, Xinzhong

    2017-01-01

    In this study, a mechanochemical route to synthesize a Cu-Al layered double hydroxide (LDH) and a methyl orange (MO) intercalated one (MO-LDH) was introduced, in which basic cupric carbonate (Cu_2(OH)_2CO_3) and aluminum hydroxide (Al(OH)_3) with Cu/Al molar ratio at 2/1 was first dry ground for 2 h and then agitated in water or methyl orange solution for another 4 h to obtain the LDH and MO-LDH products without any heating operation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The products showed high crystallinity phase of Cu-Al and MO intercalated Cu-Al LDH with no evident impurities, proving that the craft introduced here was facile and effective. The new idea can be applied in other fields to produce organic-inorganic composites. - Highlights: • A facile mechanochemical route to synthesize Cu-Al and MO intercalated Cu-Al LDH. • The products possesses high crystalline of LDH phase with no impure phases. • The dry milling process induces the element substitution between the raw materials. • The agitation operation helps the grain growth of LDH.

  3. Aging properties studies in a Cu-Ag-Cr Alloy

    International Nuclear Information System (INIS)

    Jia, S.G.; Zheng, M.S.; Liu, P.; Ren, F.Z.; Tian, B.H.; Zhou, G.S.; Lou, H.F.

    2006-01-01

    A Cu-Ag-Cr alloy was produced by means of vacuum induction melting. The effects of aging processes on microhardness and conductivity of Cu-Ag-Cr alloy were studied. The microstructure of the alloy was examined using transmission electron microscope (TEM). Aging at 450 deg. C for 4 h, the alloy has an excellent combination of microhardness and conductivity, the microhardness and conductivity reach 132 HV and 80% IACS, respectively. The precipitates responsible for the age-hardening effect are fcc Cr. The fine and dispersed precipitates are fully coherent with the Cu matrix and make the Cu-Ag-Cr alloy possesses higher hardness and conductivity

  4. Development of cold sprayed Cu coating for canister

    International Nuclear Information System (INIS)

    Kim, Hyung Jun; Kang, Yoon Ha

    2010-01-01

    Cold sprayed Cu deposition was studied for the application of outer part of canister for high level nuclear waste. Five commercially available pure Cu powders were analyzed and sprayed by high pressure cold spray system. Electrochemical corrosion test using potentiostat in 3.5% NaCl solution was conducted as well as microstructural analysis including hardness and oxygen content measurements. Overall evaluation of corrosion performance of cold sprayed Cu deposition is inferior to forged and extruded Cu plates, but some of Cu depositions are comparable to Cu plates. The simulated corrosion test in 200m underground cave is still in progress. The effect of cold spray process parameters was also studied and the results show that the type of nozzle is the most important other than powder feed rate, spray distance, and scan speed. 1/10 scale miniature of canister was manufactured confirming that the production of full scale canister is possible

  5. Growth, characterization and electrochemical properties of hierarchical CuO nanostructures for supercapacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Krishnamoorthy, Karthikeyan [Nanomaterials and System Laboratory, Department of Mechanical Engineering, Jeju National University, Jeju 690 756 (Korea, Republic of); Kim, Sang-Jae, E-mail: kimsangj@jejunu.ac.kr [Nanomaterials and System Laboratory, Department of Mechanical Engineering, Jeju National University, Jeju 690 756 (Korea, Republic of); Department of Mechatronics Engineering, Jeju National University, Jeju 690 756 (Korea, Republic of)

    2013-09-01

    Graphical abstract: - Highlights: • Hierarchical CuO nanostructures were grown on Cu foil. • Monoclinic phase of CuO was grown. • XPS analysis revealed the presence of Cu(2p{sub 3/2}) and Cu(2p{sub 1/2}) on the surfaces. • Specific capacitance of 94 F/g was achieved for the CuO using cyclic voltammetry. • Impedance spectra show their pseudo capacitor applications. - Abstract: In this paper, we have investigated the electrochemical properties of hierarchical CuO nanostructures for pseudo-supercapacitor device applications. Moreover, the CuO nanostructures were formed on Cu substrate by in situ crystallization process. The as-grown CuO nanostructures were characterized using X-ray diffraction (XRD), Fourier transform-infra red spectroscopy (FT-IR), X-ray photoelectron spectroscopy and field emission-scanning electron microscope (FE-SEM) analysis. The XRD and FT-IR analysis confirm the formation of monoclinic CuO nanostructures. FE-SEM analysis shows the formation of leave like hierarchical structures of CuO with high uniformity and controlled density. The electrochemical analysis such as cyclic voltammetry and electrochemical impedance spectroscopy studies confirms the pseudo-capacitive behavior of the CuO nanostructures. Our experimental results suggest that CuO nanostructures will create promising applications of CuO toward pseudo-supercapacitors.

  6. Growth, characterization and electrochemical properties of hierarchical CuO nanostructures for supercapacitor applications

    International Nuclear Information System (INIS)

    Krishnamoorthy, Karthikeyan; Kim, Sang-Jae

    2013-01-01

    Graphical abstract: - Highlights: • Hierarchical CuO nanostructures were grown on Cu foil. • Monoclinic phase of CuO was grown. • XPS analysis revealed the presence of Cu(2p 3/2 ) and Cu(2p 1/2 ) on the surfaces. • Specific capacitance of 94 F/g was achieved for the CuO using cyclic voltammetry. • Impedance spectra show their pseudo capacitor applications. - Abstract: In this paper, we have investigated the electrochemical properties of hierarchical CuO nanostructures for pseudo-supercapacitor device applications. Moreover, the CuO nanostructures were formed on Cu substrate by in situ crystallization process. The as-grown CuO nanostructures were characterized using X-ray diffraction (XRD), Fourier transform-infra red spectroscopy (FT-IR), X-ray photoelectron spectroscopy and field emission-scanning electron microscope (FE-SEM) analysis. The XRD and FT-IR analysis confirm the formation of monoclinic CuO nanostructures. FE-SEM analysis shows the formation of leave like hierarchical structures of CuO with high uniformity and controlled density. The electrochemical analysis such as cyclic voltammetry and electrochemical impedance spectroscopy studies confirms the pseudo-capacitive behavior of the CuO nanostructures. Our experimental results suggest that CuO nanostructures will create promising applications of CuO toward pseudo-supercapacitors

  7. Nanoporous Al sandwich foils using size effect of Al layer thickness during Cu/Al/Cu laminate rolling

    Science.gov (United States)

    Yu, Hailiang; Lu, Cheng; Tieu, A. Kiet; Li, Huijun; Godbole, Ajit; Kong, Charlie

    2018-06-01

    The roll bonding technique is one of the most widely used methods to produce metal laminate sheets. Such sheets offer interesting research opportunities for both scientists and engineers. In this paper, we report on an experimental investigation of the 'thickness effect' during laminate rolling for the first time. Using a four-high multifunction rolling mill, Cu/Al/Cu laminate sheets were fabricated with a range of thicknesses (16, 40, 70 and 130 μm) of the Al layer. The thickness of the Cu sheets was a constant 300 μm. After rolling, TEM images show good bonding quality between the Cu and Al layers. However, there are many nanoscale pores in the Al layer. The fraction of nanoscale pores in the Al layer increases with a reduction in the Al layer thickness. The finite element method was used to simulate the Cu/Al/Cu rolling process. The simulation results reveal the effect of the Al layer thickness on the deformation characteristics of the Cu/Al/Cu laminate. Finally, we propose that the size effect of the Al layer thickness during Cu/Al/Cu laminate rolling may offer a method to fabricate 'nanoporous' Al sandwich laminate foils. Such foils can be used in electromagnetic shielding of electrical devices and noisy shielding of building.

  8. A novel nonenzymatic amperometric hydrogen peroxide sensor based on CuO@Cu2O nanowires embedded into poly(vinyl alcohol).

    Science.gov (United States)

    Chirizzi, Daniela; Guascito, Maria Rachele; Filippo, Emanuela; Tepore, Antonio

    2016-01-15

    A new, very simple, rapid and inexpensive nonenzymatic amperometric sensor for hydrogen peroxide (H2O2) detection is proposed. It is based on the immobilization of cupric/cuprous oxide core shell nanowires (CuO@Cu2O-NWs) in a poly(vinyl alcohol) (PVA) matrix directly drop casted on a glassy carbon electrode surface to make a CuO@Cu2O core shell like NWs PVA embedded (CuO@Cu2O-NWs/PVA) sensor. CuO nanowires with mean diameters of 120-170nm and length in the range 2-5μm were grown by a simple catalyst-free thermal oxidation process based on resistive heating of pure copper wires at ambient conditions. The oxidation process of the copper wire surface led to the formation of a three layered structure: a thick Cu2O bottom layer, a CuO thin intermediate layer and CuO nanowires. CuO nanowires were carefully scratched from Cu2O layer with a sharp knife, dispersed into ethanol and sonicated. Then, the NWs were embedded in PVA matrix. The morphological and spectroscopic characterization of synthesized CuO-NWs and CuO@Cu2O-NWs/PVA were performed by transmission electron microscopy (TEM), selected area diffraction pattern (SAD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. Moreover a complete electrochemical characterization of these new CuO@Cu2O-NWs/PVA modified glassy carbon electrodes was performed by Cyclic Voltammetry (CV) and Cronoamperometry (CA) in phosphate buffer (pH=7; I=0.2) to investigate the sensing properties of this material against H2O2. The electrochemical performances of proposed sensors as high sensitivity, fast response, reproducibility and selectivity make them suitable for the quantitative determination of hydrogen peroxide substrate in batch analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. /Cu-Al System

    Science.gov (United States)

    Kish, Orel; Froumin, Natalya; Aizenshtein, Michael; Frage, Nachum

    2014-05-01

    Wettability and interfacial interaction of the Ta2O5/Cu-Al system were studied. Pure Cu does not wet the Ta2O5 substrate, and improved spreading is achieved when relatively a high fraction of the active element (~40 at.% Al) was added. The Al2O3 and AlTaO4 phases were observed at the Ta2O5/Cu-Al interface. A thermodynamic evaluation allowed us to suggest that the lack of wetting bellow 40 at.% Al is due to the presence of a native oxide, which covers the drop. The conditions of the native oxide decomposition and the formation of the volatile Al2O suboxide strongly depend on the vacuum level during sessile drop experiments and the composition of the Cu-Al alloy. In our case, Al contents greater than 40% provides thermodynamic conditions for the formation of Al2O (as a result of Al reaction with Al2O3) and the drop spreading. It was suggested that the final contact angle in the Ta2O5/Cu-Al system (50°) is determined by Ta adsorption on the newly formed alumina interlayer.

  10. Development of an Efficient Methanol Production Process for Direct CO2 Hydrogenation over a Cu/ZnO/Al2O3 Catalyst

    Directory of Open Access Journals (Sweden)

    Fereshteh Samimi

    2017-11-01

    Full Text Available Carbon capture and utilization as a raw material for methanol production are options for addressing energy problems and global warming. However, the commercial methanol synthesis catalyst offers a poor efficiency in CO2 feedstock because of a low conversion of CO2 and its deactivation resulting from high water production during the process. To overcome these barriers, an efficient process consisting of three stage heat exchanger reactors was proposed for CO2 hydrogenation. The catalyst volume in the conventional methanol reactor (CR is divided into three sections to load reactors. The product stream of each reactor is conveyed to a flash drum to remove methanol and water from the unreacted gases (H2, CO and CO2. Then, the gaseous stream enters the top of the next reactor as the inlet feed. This novel configuration increases CO2 conversion almost twice compared to one stage reactor. Also to reduce water production, a water permselective membrane was assisted in each reactor to remove water from the reaction side. The proposed process was compared with one stage reactor and CR from coal and natural gas. Methanol is produced 288, 305, 586 and 569 ton/day in CR, one-stage, three-stage and three-stage membrane reactors (MR, respectively. Although methanol production rate in three-stage MR is a bit lower than three stage reactors, the produced water, as the cause of catalyst poisoning, is notably reduced in this configuration. Results show that the proposed process is a strongly feasible way to produce methanol that can competitive with a traditional synthesis process.

  11. Cu and Cu(Mn) films deposited layer-by-layer via surface-limited redox replacement and underpotential deposition

    Energy Technology Data Exchange (ETDEWEB)

    Fang, J.S., E-mail: jsfang@nfu.edu.tw [Department of Materials Science and Engineering, National Formosa University, Huwei 63201, Taiwan (China); Sun, S.L. [Department of Materials Science and Engineering, National Formosa University, Huwei 63201, Taiwan (China); Cheng, Y.L. [Department of Electrical Engineering, National Chi-Nan University, Nan-Tou 54561, Taiwan (China); Chen, G.S.; Chin, T.S. [Department of Materials Science and Engineering, Feng Chia University, Taichung 40724, Taiwan (China)

    2016-02-28

    Graphical abstract: - Abstract: The present paper reports Cu and Cu(Mn) films prepared layer-by-layer using an electrochemical atomic layer deposition (ECALD) method. The structure and properties of the films were investigated to elucidate their suitability as Cu interconnects for microelectronics. Previous studies have used primarily a vacuum-based atomic layer deposition to form a Cu metallized film. Herein, an entirely wet chemical process was used to fabricate a Cu film using the ECALD process by combining underpotential deposition (UPD) and surface-limited redox replacement (SLRR). The experimental results indicated that an inadequate UPD of Pb affected the subsequent SLRR of Cu and lead to the formation of PbSO{sub 4}. A mechanism is proposed to explain the results. Layer-by-layer deposition of Cu(Mn) films was successfully performed by alternating the deposition cycle-ratios of SLRR-Cu and UPD-Mn. The proposed self-limiting growth method offers a layer-by-layer wet chemistry-based deposition capability for fabricating Cu interconnects.

  12. Composition of Cu/Al system constructed by means of dynamic atomic deposition

    International Nuclear Information System (INIS)

    Tashlykov, I.S.; Tul'ev, V.V.

    2011-01-01

    Rutherford backscattering and RUMP simulation programme have been applied to investigate composition of Cu/Al system prepared using dynamic atomic deposition process when deposition of Cu thin film on Al substrate was assisted with 6 keV Ar + ions irradiation. It is estimated that thin ( ~15 nm) surface layer consists of ~50 at.% Cu, ~10 at.% Ar, ~4 at.% O and the remaining is Al. Dynamic deposition of Cu on Al substrate is accompanied with radiation enhanced diffusion of Cu, O, Ar atoms in substrate and out diffusion of Al atoms in deposited Cu coating. (authors)

  13. Modifikasi Zeolit Dengan Tembaga (Cu) Dan Uji Sifat Katalitiknya Pada Reaksi Esterifikasi

    OpenAIRE

    Arjek, Orien Claudia Handayani; Fatimah, Is

    2017-01-01

    Zeolite modification with Cu has been conducted. Material modification is done by impregnating Cu through a zeolite powder reflux process with CuSO4.5H2O solution so that theoretical Cu concentration is 5% followed by oxidation and reduction of solids. Material characterization was performed by x-ray diffraction analysis (XRD), Fourier Transform Infra-Red (FTIR) and acidity testing of Cu/Zeolite catalyst.The results showed that the crystallinity level of Cu/Zeolite did not change significantl...

  14. Bulk and thick films of the superconducting phase YBa2Cu3O7/sub -//sub y/ made by controlled precipitation and sol-gel processes

    International Nuclear Information System (INIS)

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

    1988-01-01

    The synthesis of high-temperature superconducting oxides using solution chemistry has been investigated and physical properties are compared to ceramics obtained by conventional solid-state reactions. We report on controlled precipitation and sol-gel processes, both of which produce materials with particle sizes smaller than 5 μm. We find that the superconducting properties of the high T/sub c/ ceramics are affected by their manner of preparation, such that the transitions are slightly lower in temperature, but sharper, for samples made by solution rather than solid-state chemistry. The ability to prepare stable viscous gels provides an opportunity for obtaining large areas of superconducting coatings. For thick films on alumina or silicon substrates, contamination from the substrate is shown to be a problem. Finally, we observe that the sol-gel process lowers the synthesis temperature by 100 0 C.ing,

  15. Preliminaries on pollution risk factors related to mining and ore processing in the Cu-rich pollymetallic belt of Eastern Carpathians, Romania.

    Science.gov (United States)

    Stumbea, Dan

    2013-11-01

    The present study focuses on the mineralogical and geochemical patterns of mining and ore-processing wastes from some occurrences in the Eastern Carpathians; its aim is to identify the main factors and processes that could lead to the pollution of the environment. In this respect, the following types of solid waste were investigated: efflorescent salts developed on the surface of rock blocks from a quarry, ore-processing waste from two tailings ponds, and salt crusts developed at the surface of a tailings pond. The potential risks emphasized by these preliminary investigations are the following: (1) the risk of wind-driven removal and transport of the waste from the surface of tailings ponds, given that fine grains prevail (up to 80%); (2) the risk of tailings removal through mechanical transport by water, during heavy rainfall; (3) the appearance of hydrated sulfates on the rock fragments from the mining waste, sulfates which are highly susceptible to the generation of acid mine drainage (pHmine drainage leachates contain; and (5) the development of a salt crust on the flat, horizontal surfaces of the waste deposit, due to this very shape. Statistical data regarding the amount of both major and minor elements in the tailings have revealed two statistical populations for nearly all the toxic metals. This suggests that, beyond the effect that the tailings have upon the environment through their mere presence in a given area, there are alleged additional factors and processes which intensify the pollution: the location of the waste deposit relative to the topography of the area; the shape of the waste deposit; the development of low areas on the surface of the deposit, areas which favor the appearance of salt crusts; and the mineralogy of efflorescent aggregates.

  16. The effect of high hydrostatic pressure on creep behaviour of pure Al and a Cu-0.2 wt% Zr alloy processed by equal-channel angular pressing

    Czech Academy of Sciences Publication Activity Database

    Dvořák, Jiří; Sklenička, Václav; Betekhtin, V. I.; Kadomtsev, A. G.; Král, Petr; Kvapilová, Marie; Svoboda, Milan

    2013-01-01

    Roč. 584, NOV (2013), s. 103-113 ISSN 0921-5093 R&D Projects: GA ČR(CZ) GAP108/11/2260; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Equal-channel angular processing * Nanostructured materials * Mechanical characterization * Electron microscopy * Grain boundaries Subject RIV: JG - Metallurgy Impact factor: 2.409, year: 2013

  17. Mechanical characterization of Cu-Zn wire electrode base used in EDM and study of influence of the process of machining on its properties

    Energy Technology Data Exchange (ETDEWEB)

    Sedjal, H., E-mail: hasedjal@yahoo.fr; Amirat, B. [Département of Mechanical engineering, University of M.MAMMERI, Tizi Ouzou (Algeria); Aichour, M.; Marouf, T.; Chitroub, M. [Engineering and Material Sciences Laboratory, Department of Metallurgy, Polytechnic national school, Algiers (Algeria)

    2015-03-30

    This work is part of a Research National project (PNR) carried out by the group of research of the engineering and material sciences laboratory of the polytechnic national school at Algiers in collaboration with company BCR, which relates to “the characterization of the wire intended for the EDM of matrices metal. The goal of this work is to bring metallographic explanations on the wire electrode used by the machine ROBOFIL 290P, mechanically characterized this wire as of knowing of advantage about the process of its manufacturing (wiredrawing, .) The methods of studies used are it micro Vickers pyramid hardness, the tensile test, optical microscopy and scan electronic microscopy SEM.

  18. Properties of the ablation process for excimer laser ablation of Y sub 1 Ba sub 2 Cu sub 3 O sub 7

    Energy Technology Data Exchange (ETDEWEB)

    Neifeld, R.A.; Potenziani, E. (United States Army, Electronics Technology and Devices Laboratory, Fort Monmouth, New Jersey 07703-5000 (US)); Sinclair, W.R. (Martin Goffman Associates, 3 Dellview Drive, Edison, New Jersey 08820-2545 (US)); Hill III, W.T.; Turner, B.; Pinkas, A. (Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (US))

    1991-01-15

    The process of excimer laser ablation has been studied while varying the laser fluence from 0.237 to 19.1 J/cm{sup 2}. Ion time-of-flight, total charge, target etch depth per pulse, and etch volume per pulse have been measured. Results indicate a maximum ablation volume and minimum ionization fraction occur near 5 J/cm{sup 2}. Several of the parameters measured vary rapidly in the 1--5 J/cm{sup 2} range. Variation in these parameters strongly influences the properties of films grown by this technique.

  19. Eddy current measurement of the thickness of top Cu film of the multilayer interconnects in the integrated circuit (IC) manufacturing process

    Science.gov (United States)

    Qu, Zilian; Meng, Yonggang; Zhao, Qian

    2015-03-01

    This paper proposes a new eddy current method, named equivalent unit method (EUM), for the thickness measurement of the top copper film of multilayer interconnects in the chemical mechanical polishing (CMP) process, which is an important step in the integrated circuit (IC) manufacturing. The influence of the underneath circuit layers on the eddy current is modeled and treated as an equivalent film thickness. By subtracting this equivalent film component, the accuracy of the thickness measurement of the top copper layer with an eddy current sensor is improved and the absolute error is 3 nm for sampler measurement.

  20. Synthesis of high efficient Cu/TiO2 photocatalysts by grinding and their size-dependent photocatalytic hydrogen production

    Science.gov (United States)

    Ni, Dawei; Shen, Haiyan; Li, Huiqiao; Ma, Ying; Zhai, Tianyou

    2017-07-01

    Recently, copper species have been extensively investigated to replace Pt as efficient co-catalysts for the evolution of H2 due to their low cost and relatively high activity. Cu nanoparticles less than 5 nm are successfully decorated on TiO2 surface in this work by an easy and mild milling process. These Cu nanoparticles are highly dispersed on TiO2 when the loading amount of Cu is no more than 10 wt%. The sizes of Cu nanoparticles can be controlled by changing the milling environment and decrease in the order of Cu-ethanol > Cu-water > Cu nanoparticles obtained through drying milling. The highest and stable hydrogen generation can be realized on Cu/TiO2 with 2.0 wt% Cu and sizes of Cu nanoparticles ranging from 2 to 4 nm, in which high and stable photocurrent confirms promoted photogenerated charge separation. Smaller Cu clusters are demonstrated to be detrimental to hydrogen evolution at same Cu content. High loading of Cu nanoparticles of 2-4 nm will benefit photogenerated electron-hole recombination and thus decrease the activity of Cu/TiO2. The results here demonstrate the key roles of Cu cluster size in addition to Cu coverage on photocatalytic activity of Cu/TiO2 composite photocatalysts.

  1. Conducting mechanisms of forming-free TiW/Cu{sub 2}O/Cu memristive devices

    Energy Technology Data Exchange (ETDEWEB)

    Yan, P.; Li, Y.; Hui, Y. J.; Zhong, S. J.; Zhou, Y. X.; Xu, L.; Liu, N.; Qian, H.; Sun, H. J., E-mail: shj@mail.hust.edu.cn; Miao, X. S. [Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan 430074 (China); School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-08-24

    P-type Cu{sub 2}O is a promising CMOS-compatible candidate to fabricate memristive devices for next-generation memory, logic and neuromorphic computing. In this letter, the microscopic switching and conducting mechanisms in TiW/Cu{sub 2}O/Cu memristive devices have been thoroughly investigated. The bipolar resistive switching behaviors without an electro-forming process are ascribed to the formation and rupture of the conducting filaments composed of copper vacancies. In the low resistive state, the transport of electrons in the filaments follows Mott's variable range hopping theory. When the devices switch back to high resistive state, the coexistence of Schottky emission at the Cu/Cu{sub 2}O interface and electron hopping between the residual filaments is found to dominate the conducting process. Our results will contribute to the further understanding and optimization of p-type memristive materials.

  2. Microstructural and mechanical characterization of melt spun process Sn-3.5Ag and Sn-3.5Ag-xCu lead-free solders for low cost electronic assembly

    Energy Technology Data Exchange (ETDEWEB)

    Mostafa Shalaby, Rizk; Kamal, Mustafa [Metal Physics Laboratory, Physics Department, Faculty of Science, Mansoura University, P.O.Box: 35516, Mansoura (Egypt); Ali, Esmail A.M. [Basic Science Department, Faculty of Engineering, University of Science & Technology (Yemen); Gumaan, Mohammed S., E-mail: m.gumaan1@gmail.com [Metal Physics Laboratory, Physics Department, Faculty of Science, Mansoura University, P.O.Box: 35516, Mansoura (Egypt); Basic Science Department, Faculty of Engineering, University of Science & Technology (Yemen)

    2017-04-06

    This paper aims to investigate the reliability of mechanical and creep behavior for the eutectic Sn-Ag and Sn-Ag-Cu Solder joints rapidly solidified after hot compressing (HC) in terms of structural changes and its relationship with thermal behavior, which has been discussed and compared with their properties before HC process by Mustafa et al. (2016) . These solder joints were prepared by melt-spinning technique and tested by HC at 30 MPa pressure and 150 °C for 90 min, their structural, mechanical and thermal properties after HC process have been investigated by X-ray diffraction (XRD), dynamic resonance techniques (DRT) and differential scanning calorimetry (DSC) techniques respectively and compared with these solders before HC. The results revealed that the pressure caused some fractures on the solders morphology surfaces. But some benefits for these solders have been occurred, like eliminating the internal stresses through recrystallization process whose evidence by the particle size increases after they HC, stabilized structure after HC was due to the metastable phases rearrangements, new intermetallic compounds (IMCs) formation, decreasing, melting temperature range (∆T), lattice strains (ƹ) and entropy change (S). These sequential benefits are considered to be the main reasons which lead to decreasing energy loss (Q{sup −1}), creep rate (É›) and thermal stability enhancement. Elastic modulus increment might be due to low elastic lattice distortions after HC, while the stress exponent (n) reduction refers to viscous glide mechanism of deformation after HC instead of climb deformation mechanism before HC.

  3. Microstructure of Multi-Pass Friction-Stir-Processed Al-Zn-Mg-Cu Alloys Reinforced by Nano-Sized TiB2 Particles and the Effect of T6 Heat Treatment

    Directory of Open Access Journals (Sweden)

    Xiaofei Ju

    2017-11-01

    Full Text Available In this work, a fine-grained structure with a uniform distribution of TiB2 particles and precipitates was achieved in TiB2 particle-reinforced (PR Al-Zn-Mg-Cu alloys by friction stir processing (FSP. The effects of multi-pass FSP on the microstructure, and TiB2 particle distribution, as well as the microstructural evolution in the following T6 treatment, were investigated by X-ray diffraction, scanning electron microscopy and associated electron backscattered diffraction. The results showed that the distribution of TiB2 particles and alloy precipitates was further improved with an increase in the FSP passes. Moreover, compared with alloy segregation in the as-cast PR alloys during T6 treatment, a complete solution of the precipitates was achieved in the FSP-treated PR alloys. The fine-grained structure of the FSP-treated PR alloys was thermally stable without any abnormal growth at the high temperature of T6 treatment due to the pinning effect of dispersed TiB2 particles. The strength and ductility of the PR alloys were simultaneously improved by the combination of FSP and T6 treatment.

  4. Nanocavity formation processes in MgO(1 0 0) by light ion (D, He, Li) and heavy ion (Kr, Cu, Au) implantation

    International Nuclear Information System (INIS)

    Veen, A. van; Huis, M.A. van; Fedorov, A.V.; Schut, H.; Labohm, F.; Kooi, B.J.; Hosson, J.Th.M. de

    2002-01-01

    In studies on the controlled growth of metallic precipitates in MgO it is attempted to use nanometer size cavities as precursors for formation of metallic precipitates. In MgO nanocavities can easily be generated by light gas ion bombardment at room temperature with typically 30 keV ion energy to a dose of 10 16 cm -2 , followed by annealing to 1300 K. It has been shown earlier by transmission electron microscopy (TEM) that the cavities (thickness 2-3 nm and length/width 5-10 nm) have a perfectly rectangular shape bounded by {1 0 0} faces. The majority of the gas has been released at this temperature and the cavities are stable until annealing at 1500 K. The depth location of the cavities and the implanted ions is monitored by positron beam analysis, neutron depth profiling, RBS/channeling and energy dispersive spectroscopy. The presence of metallic nanoprecipitates is detected by optical absorption measurements and by high-resolution XTEM. Surprisingly, all the metallic implants induce, in addition to metallic precipitates in a band at the mean ion range, small rectangular and cubic nanocavities. These are most clearly observed at a depth shallower than the precipitate band. In the case of gold the cavities are produced in close proximity to the crystal surface. The results indicate that in MgO vacancy clustering dominates over Frenkel-pair recombination. Results of molecular dynamics calculations will be used to discuss the observed defect recovery and clustering processes in MgO

  5. Nanocavity formation processes in MgO(1 0 0) by light ion (D, He, Li) and heavy ion (Kr, Cu, Au) implantation

    Energy Technology Data Exchange (ETDEWEB)

    Veen, A. van E-mail: avveen@iri.tudelft.nl; Huis, M.A. van; Fedorov, A.V.; Schut, H.; Labohm, F.; Kooi, B.J.; Hosson, J.Th.M. de

    2002-05-01

    In studies on the controlled growth of metallic precipitates in MgO it is attempted to use nanometer size cavities as precursors for formation of metallic precipitates. In MgO nanocavities can easily be generated by light gas ion bombardment at room temperature with typically 30 keV ion energy to a dose of 10{sup 16} cm{sup -2}, followed by annealing to 1300 K. It has been shown earlier by transmission electron microscopy (TEM) that the cavities (thickness 2-3 nm and length/width 5-10 nm) have a perfectly rectangular shape bounded by {l_brace}1 0 0{r_brace} faces. The majority of the gas has been released at this temperature and the cavities are stable until annealing at 1500 K. The depth location of the cavities and the implanted ions is monitored by positron beam analysis, neutron depth profiling, RBS/channeling and energy dispersive spectroscopy. The presence of metallic nanoprecipitates is detected by optical absorption measurements and by high-resolution XTEM. Surprisingly, all the metallic implants induce, in addition to metallic precipitates in a band at the mean ion range, small rectangular and cubic nanocavities. These are most clearly observed at a depth shallower than the precipitate band. In the case of gold the cavities are produced in close proximity to the crystal surface. The results indicate that in MgO vacancy clustering dominates over Frenkel-pair recombination. Results of molecular dynamics calculations will be used to discuss the observed defect recovery and clustering processes in MgO.

  6. Microstructure, microtexture and precipitation in the ultrafine-grained surface layer of an Al-Zn-Mg-Cu alloy processed by sliding friction treatment

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yanxia [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an 710072 (China); Yang, Yanqing, E-mail: yqyang@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an 710072 (China); Feng, Zongqiang [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Zhao, Guangming; Huang, Bin; Luo, Xian [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an 710072 (China); Zhang, Yusheng; Zhang, Wei [Northwest Institute for Nonferrous Metal Research, Xi' an 710016 (China)

    2017-01-15

    Precipitate redistribution and texture evolution are usually two concurrent aspects accompanying grain refinement induced by various surface treatment. However, the detailed precipitate redistribution characteristics and process, as well as crystallographic texture in the surface refined grain layer, are still far from full understanding. In this study, we focused on the microstructural and crystallographic features of the sliding friction treatment (SFT) induced surface deformation layer in a 7050 aluminum alloy. With the combination of transmission electron microscopy (TEM) and high angle angular dark field scanning TEM (HAADF-STEM) observations, a surface ultrafine grain (UFG) layer composed of both equiaxed and lamellar ultrafine grains and decorated by high density of coarse grain boundary precipitates (GBPs) were revealed. Further precession electron diffraction (PED) assisted orientation mapping unraveled that high angle grain boundaries rather than low angle grain boundaries are the most favorable nucleation sites for GBPs. The prominent precipitate redistribution can be divided into three successive and interrelated stages, i.e. the mechanically induced precipitate dissolution, solute diffusion and reprecipitation. The quantitative prediction based on pipe diffusion along dislocations and grain boundary diffusion proved the distribution feasibility of GBPs around UFGs. Based on PED and electron backscatter diffraction (EBSD) analyses, the crystallographic texture of the surface UFG layer was identified as a shear texture composed of major rotated cube texture (001) 〈110〉 and minor (111) 〈112〉, while that of the adjoining lamellar coarse grained matrix was pure brass. The SFT induced surface severe shear deformation is responsible for texture evolution. - Highlights: •The surface ultrafine grain layer in a 7050 aluminum alloy was focused. •Precipitate redistribution and texture evolution were discussed. •The quantitative prediction proved the