Structural Defects of Silver Hollandite, Ag(x)Mn8O(y), Nanorods: Dramatic Impact on Electrochemistry.

Science.gov (United States)

Wu, Lijun; Xu, Feng; Zhu, Yimei; Brady, Alexander B; Huang, Jianping; Durham, Jessica L; Dooryhee, Eric; Marschilok, Amy C; Takeuchi, Esther S; Takeuchi, Kenneth J

2015-08-25

Hollandites (OMS-2) are an intriguing class of sorbents, catalysts, and energy storage materials with a tunnel structure permitting one-dimensional insertion and deinsertion of ions and small molecules along the c direction. A 7-fold increase in delivered capacity for Li/AgxMn8O16 electrochemical cells (160 versus 23 mAh/g) observed upon a seemingly small change in silver content (x ∼1.1 (L-Ag-OMS-2) and 1.6 (H-Ag-OMS-2)) led us to characterize the structure and defects of the silver hollandite material. Herein, Ag hollandite nanorods are studied through the combined use of local (atomic imaging, electron diffraction, electron energy-loss spectroscopy) and bulk (synchrotron based X-ray diffraction, thermogravimetric analysis) techniques. Selected area diffraction and high resolution transmission electron microscopy show a structure consistent with that refined by XRD; however, the Ag occupancy varies significantly even within neighboring channels. Both local and bulk measurements indicate a greater quantity of oxygen vacancies in L-Ag-OMS-2, resulting in lower average Mn valence relative to H-Ag-OMS-2. Electron energy loss spectroscopy shows a lower Mn oxidation state on the surface relative to the interior of the nanorods, where the average Mn valence is approximately Mn(3.7+) for H-Ag-OMS-2 and Mn(3.5+) for L-Ag-OMS-2 nanorods, respectively. The higher delivered capacity of L-Ag-OMS-2 may be related to more oxygen vacancies compared to H-Ag-OMS-2. Thus, the oxygen vacancies and MnO6 octahedra distortion are assumed to open the MnO6 octahedra walls, facilitating Li diffusion in the ab plane. These results indicate crystallite size and surface defects are significant factors affecting battery performance.

The Effect of Ag Addition on the Enhancement of the Thermal and Mechanical Properties of CuZrAl Bulk Metallic Glasses

Directory of Open Access Journals (Sweden)

Tsan-Man Chung

2016-09-01

Full Text Available In this study, the thermal and mechanical properties of Cu50−xZr43Al7Agx (x = 0, 3, 4, 5, 6 bulk metallic glasses (BMGs are investigated by using an X-ray diffractometer (XRD, a differential scanning calorimeter (DSC, differential thermal analysis (DTA, a Vickers hardness tester, a material test system (MTS, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. Cu50−xZr43Al7Agx (x = 0, 3, 4, 5, 6 BMGs were made by arc-melting and an injection casting process. The results revealed that the glass transition temperature (Tg and the crystallization temperature (Tx of CuZrAl alloy decreased with the Ag addition. Hence, the supercooled liquid region and γ of Cu45Zr43Al7Ag5 alloy increased to 76 K and 0.42, respectively. The thermal stability and glass forming ability of CuZrAlAg BMG alloys were enhanced by the microalloyed Ag content. The room temperature compressive fracture strength and strain measured of Cu47Zr43Al7Ag3 were about 2200 MPa and 2.1%, respectively. The distribution of vein patterns and the formation of nanocrystalline phases on the fracture surface of Cu47Zr43Al7Ag3 alloy can be observed by SEM and TEM to be significant, indicating a typical ductile fracture behavior and an improved plasticity of alloys with the addition of microalloyed Ag from 0 to 6 atom %.

The Effect of (Ag, Ni, Zn)-Addition on the Thermoelectric Properties of Copper Aluminate

DEFF Research Database (Denmark)

Yanagiya, Shun-ichi; Van Nong, Ngo; Xu, Jianxiao Jackie

2010-01-01

Polycrystalline bulk copper aluminate Cu1-x-yAgxByAlO2 with B = Ni or Zn were prepared by spark plasma sintering and subsequent thermal treatment. The influence of partial substitution of Ag, Ni and Zn for Cu-sites in CuAlO2 on the high temperature thermoelectric properties has been studied......, indicating a significant improvement compared with the non-doped CuAlO2 sample...

Computational investigation of CO adsorbed on Aux, Agx and (AuAg)x nanoclusters (x = 1 - 5, 147) and monometallic Au and Ag low-energy surfaces*

Science.gov (United States)

Gould, Anna L.; Catlow, C. Richard A.; Logsdail, Andrew J.

2018-02-01

Density functional theory calculations have been performed to investigate the use of CO as a probe molecule for the determination of the structure and composition of Au, Ag and AuAg nanoparticles. For very small nanoclusters (x = 1 - 5), the CO vibrational frequencies can be directly correlated to CO adsorption strength, whereas larger 147-atom nanoparticles show a strong energetic preference for CO adsorption at a vertex position but the highest wavenumbers are for the bridge positions. We also studied CO adsorption on Au and Ag (100) and (111) surfaces, for a 1 monolayer coverage, which proves to be energetically favourable on atop only and bridge positions for Au (100) and atop for Ag (100); vibrational frequencies of the CO molecules red-shift to lower wavenumbers as a result of increased metal coordination. We conclude that CO vibrational frequencies cannot be solely relied upon in order to obtain accurate compositional analysis, but we do propose that elemental rearrangement in the core@shell nanoclusters, from Ag@Au (or Au@Ag) to an alloy, would result in a shift in the CO vibrational frequencies that indicate changes in the surface composition. Contribution to the Topical Issue "Shaping Nanocatalysts", edited by Francesca Baletto, Roy L. Johnston, Jochen Blumberger and Alex Shluger.Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjb/e2017-80280-7

Synthesis and Characterization of Ag-Ag2O/TiO2@polypyrrole Heterojunction for Enhanced Photocatalytic Degradation of Methylene Blue

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Rajeev Kumar

2016-05-01

Full Text Available Hybrid multi-functional nanomaterials comprising two or more disparate materials have become a powerful approach to obtain advanced materials for environmental remediation applications. In this work, an Ag-Ag2O/TiO2@polypyrrole (Ag/TiO2@PPy heterojunction has been synthesized by assembling a self-stabilized Ag-Ag2O (p type semiconductor (denoted as Ag and polypyrrole (π-conjugated polymer on the surface of rutile TiO2 (n type. Ag/TiO2@PPy was synthesized through simultaneous oxidation of pyrrole monomers and reduction of AgNO3 in an aqueous solution containing well-dispersed TiO2 particles. Thus synthesized Ag/TiO2@PPy was characterized using X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, and UV-Vis diffuse reflectance spectroscopy (UV-vis DSR. The photocatalytic activity of synthesized heterojunction was investigated for the decomposition of methylene blue (MB dye under UV and visible light irradiation. The results revealed that π-conjugated p-n heterojunction formed in the case of Ag/TiO2@PPy significantly enhanced the photodecomposition of MB compared to the p-n type Ag/TiO2 and TiO2@PPy (n-π heterojunctions. A synergistic effect between Ag-Ag2O and PPy leads to higher photostability and a better electron/hole separation leads to an enhanced photocatalytic activity of Ag/TiO2@PPy under both UV and visible light irradiations.

The structure and band gap design of high Si doping level Ag1−xGa1−xSixSe2 (x=1/2)

International Nuclear Information System (INIS)

Zhang, Shiyan; Mei, Dajiang; Du, Xin; Lin, Zheshuai; Zhong, Junbo; Wu, Yuandong; Xu, Jingli

2016-01-01

Ag 1−x Ga 1−x Si x Se 2 solutions with high Si doping level (x=1/2) are considered and new compound AgGaSiSe 4 has been synthesized. It crystallizes in space group Aea2 and possesses very long axis of a=63.06(1)Å. The three-dimensional framework in AgGaSiSe 4 is composed of AgSe 3 trigonal planar units, AgSe 4 tetrahedra and MSe 4 (M=Si, Ga) tetrahedra. AgGaSiSe 4 is a congruently melting compound with the melt temperature of 759 °C. The diffuse reflectance measurements reveal the band gap of 2.63 eV in AgGaSiSe 4 and the value is 0.33 eV larger than that of Ag 3 Ga 3 SiSe 8 (2.30 eV). - Graphical abstract: The Ag 1−x Ga 1−x Si x Se 2 with high Si doping level (x=1/2) has been studied and the new compound AgGaSiSe 4 was synthesized for the first time. AgGaSiSe 4 crystallizes in a new structure type in space group Aea2 and adopts a three-dimensional framework consisting of AgSe 3 trigonal planar units, AgSe 4 tetrahedra and MSe 4 (M=Si, Ge) tetrahedra. Display Omitted - Highlights: • Study of Ag 1−x Ga 1−x Si x Se 2 with high Si doping level (x=1/2). • Successful synthesis of new compound named AgGaSiSe 4 . • AgGaSiSe 4 crystallizes in space group Aea2 and adopts a three-dimensional framework. • The energy band gap of AgGaSiSe 4 is enlarged compared with Ag 3 Ga 3 SiSe 8 .

The Effect of (Ag, Ni, Zn-Addition on the Thermoelectric Properties of Copper Aluminate

Directory of Open Access Journals (Sweden)

Jianxiao Xu

2010-01-01

Full Text Available Polycrystalline bulk copper aluminate Cu1-x-yAgxByAlO2 with B = Ni or Zn were prepared by spark plasma sintering and subsequent thermal treatment. The influence of partial substitution of Ag, Ni and Zn for Cu-sites in CuAlO2 on the high temperature thermoelectric properties has been studied. The addition of Ag and Zn was found to enhance the formation of CuAlO2 phase and to increase the electrical conductivity. The addition of Ag or Ag and Ni on the other hand decreases the electrical conductivity. The highest power factor of 1.26 × 10-4 W/mK2 was obtained for the addition of Ag and Zn at 1,060 K, indicating a significant improvement compared with the non-doped CuAlO2 sample.

Using 13X, LiX, and LiPdAgX zeolites for CO_2 capture from post-combustion flue gas

International Nuclear Information System (INIS)

Chen, S.J.; Zhu, M.; Fu, Y.; Huang, Y.X.; Tao, Z.C.; Li, W.L.

2017-01-01

Highlights: • We synthesized a novel adsorbent named LiPdAgX zeolite. • CCS was proposed from microstructure, selectivity and separation factor of zeolite. • The static and flowing adsorption using CO_2/N_2 mixture on X zeolites were studied. • LiPdAgX zeolite required less energy for regeneration compared to 13X and MEA. • LiPdAgX zeolite can effectively capture CO_2 from post-combustion flue gas. - Abstract: This work investigates the application of X zeolites for capturing CO_2 from post-combustion flue gas. LiX and LiPdAgX zeolites were prepared by an ion-exchange method using 13X zeolite. X-ray diffraction analysis showed that all samples exhibited characteristic peaks of X zeolites, where the peak intensities increased in the order: LiPdAgX > LiX > 13X. The enhanced intensity of the diffraction peaks can increase the activity of the X zeolites and improve their adsorption performance. Scanning electron microscopy imaging showed that the intergranular pore canals of LiPdAgX zeolite were more concentrated. Pore structure analysis indicated that addition of Li"+ to the 13X zeolite enhanced the specific surface areas and pore volumes of the zeolites. Among the 13X, LiX, and LiPdAgX zeolites, LiPdAgX showed the highest CO_2/N_2selectivity, where the difference in the CO_2 adsorption capacity was due to differences in the number of adsorption sites and thermal conductivities of the X zeolites. The CO_2 breakthrough time increased in succession for the 13X, LiX, and LiPdAgX zeolites. The CO_2/N_2 separation factor of the LiPdAgX zeolite was twice that of the 13X zeolite at a CO_2 concentration of 20 vol.%. The temperature variations during the adsorption process were used to determine the regeneration energy and adsorption capacity of the X zeolites. LiPdAgX zeolite required less energy for regeneration than 13X zeolite and MEA. After regeneration, the separation factor of LiPdAgX zeolite remained at 6.38 for 20 vol.% CO_2 in the flue gas. Therefore, LiPdAgX

Two crystal structures of Ag sup + -and Tl sup + -exchanged zeolite X, Ag sub 2 sub 7 Tl sub 6 sub 5 -X and Ag sub 2 sub 3 Tl sub 6 sub 9 -X

CERN Document Server

Kim, S Y; Kim, Y

2002-01-01

Two crystal structures of dehydrated Ag sup + -and Tl sup + -exchanged zeolite X (Ag sub 2 sub 7 Tl sub 6 sub 5 -X and Ag sub 2 sub 3 Tl sub 6 sub 9 -X) have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21(1) .deg. C (a = 24.758(4) A, a = 24.947(4) A, respectively). Their structures were refined to the final error indices R sub 1 = 0.055 and wR sub 2 = 0.057 with 375 reflections, and R sub 1 = 0.058 and wR sub 2 = 0.057 with 235 reflections, respectively, for which I> 3 sigma(I). In the structure of Ag sub 2 sub 7 Tl sub 6 sub 5 -X, 27 Ag sup + ions were found at two crystallographic sites: 15 Ag sup + ions at site I at the center of the hexagonal prism and the remaining 12 Ag sup + ions at site II' in the sodalite cavity. Sixty-five Tl sup + ions were located at three crystallographic sites: 20 Tl sup + ions at site II opposite single six-rings in the supercage, 18 Tl sup + ions at site I' in the sodalite cavity opposite the D6Rs, and the remaining 27 Tl sup ...

A PdAg bimetallic nanocatalyst for selective reductive amination of nitroarenes.

Science.gov (United States)

Li, Linsen; Niu, Zhiqiang; Cai, Shuangfei; Zhi, Yun; Li, Hao; Rong, Hongpan; Liu, Lichen; Liu, Lei; He, Wei; Li, Yadong

2013-08-07

Herein we have identified an optimal catalyst, Pd1Ag1.7, for the tandem reductive amination between nitroarenes and aldehydes (selectivity > 93%). Key to the success is the ability to control the compositions of the investigational Pd1-xAgx (x = 0-1) catalysts, as well as the clear composition dependent activity/selectivity trend observed in this study. This catalyst features a wide substrate scope, excellent recyclability, activity and selectivity under ambient conditions.

A simple solution-phase approach to synthesize high quality ternary AgInSe2 and band gap tunable quaternary AgIn(S1-xSe x)2 nanocrystals

KAUST Repository

Bai, Tianyu

2014-01-01

A facile solution-phase route for the preparation of AgInSe2 nanocrystals was developed by using silver nitrate, indium stearate, and oleylamine-selenium (OAm-Se) as precursors. The evolution process of the AgInSe2 nanocrystals is discussed in detail and different reaction conditions all have a great impact on the growth and morphology of the nanocrystals. Alloyed AgIn(S1-xSex)2 nanocrystals with controlled composition across the entire range (0 ≤ x ≤ 1) was also successfully prepared by modulating the S/Se reactant mole ratio. X-ray diffraction (XRD), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were used to confirm that the alloyed AgIn(S1-xSex)2 nanocrystals are homogeneous. The UV-vis absorption spectra revealed that the band gap energies of the alloyed AgIn(S1-xSex)2 nanocrystals could be continuously tuned by increasing the Se content. © The Royal Society of Chemistry 2014.

Monomer functionalized silica coated with Ag nanoparticles for enhanced SERS hotspots

Science.gov (United States)

Newmai, M. Boazbou; Verma, Manoj; Kumar, P. Senthil

2018-05-01

Mesoporous silica (SiO2) spheres are well-known for their excellent chromatographic properties such as the relatively high specific surface, large pore volume, uniform particle size, narrow pore size distribution with favorable pore connectivity; whereas the noble metal Ag nanoparticles have unique size/shape dependant surface plasmon resonance with wide ranging applications. Thus, the desire to synchronize both their properties for specific applications has naturally prompted research in the design and synthesis of core-shell type novel nanoAg@mesoSiO2 nanocomposites, which display potential utility in applications such as photothermal therapy, photocatalysis, molecular sensing, and photovoltaics. In the present work, SiO2 spheres were carefully functionalized with the monomer, N-vinyl pyrrolidone (NVP), which cohesively controls the uniform mass transfer of Ag+ metal ions, thereby enabling its sequential reduction to zerovalent Ag (in the presence of slightly excess NaOH) by electron transfer from nucleophilic attack of the NVP vinyl group by the water molecules even under ambient conditions. Complete metal nanoshell coverage of the silica surface was obtained after multiple Ag deposition cycles, as systematically confirmed from the BET, TEM, optical and FTIR characterization. Our present Ag-coated silica spheres were directly utilized as viable SERS substrates with high sensitivity in contrast with other long chain polymer/surfactant coated silica spheres, owing to the presence of significant number of nanogaps enhanced SERS 'hotspots', which were methodically analyzed utilizing two example analytes, such as crystal violet (CV) and calendula officinalis (CaF).

The structure and band gap design of high Si doping level Ag{sub 1−x}Ga{sub 1−x}Si{sub x}Se{sub 2} (x=1/2)

Energy Technology Data Exchange (ETDEWEB)

Zhang, Shiyan [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Mei, Dajiang, E-mail: meidajiang718@pku.edu.cn [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Du, Xin [Beijing National Laboratory for Molecular Sciences and State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Lin, Zheshuai [Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Chinese Academy of Sciences, Beijing 100190 (China); Zhong, Junbo [Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan, College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Wu, Yuandong, E-mail: wuyuandong2013@outlook.com [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Xu, Jingli [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China)

2016-06-15

Ag{sub 1−x}Ga{sub 1−x}Si{sub x}Se{sub 2} solutions with high Si doping level (x=1/2) are considered and new compound AgGaSiSe{sub 4} has been synthesized. It crystallizes in space group Aea2 and possesses very long axis of a=63.06(1)Å. The three-dimensional framework in AgGaSiSe{sub 4} is composed of AgSe{sub 3} trigonal planar units, AgSe{sub 4} tetrahedra and MSe{sub 4}(M=Si, Ga) tetrahedra. AgGaSiSe{sub 4} is a congruently melting compound with the melt temperature of 759 °C. The diffuse reflectance measurements reveal the band gap of 2.63 eV in AgGaSiSe{sub 4} and the value is 0.33 eV larger than that of Ag{sub 3}Ga{sub 3}SiSe{sub 8} (2.30 eV). - Graphical abstract: The Ag{sub 1−x}Ga{sub 1−x}Si{sub x}Se{sub 2} with high Si doping level (x=1/2) has been studied and the new compound AgGaSiSe{sub 4} was synthesized for the first time. AgGaSiSe{sub 4} crystallizes in a new structure type in space group Aea2 and adopts a three-dimensional framework consisting of AgSe{sub 3} trigonal planar units, AgSe{sub 4} tetrahedra and MSe{sub 4} (M=Si, Ge) tetrahedra. Display Omitted - Highlights: • Study of Ag{sub 1−x}Ga{sub 1−x}Si{sub x}Se{sub 2} with high Si doping level (x=1/2). • Successful synthesis of new compound named AgGaSiSe{sub 4}. • AgGaSiSe{sub 4} crystallizes in space group Aea2 and adopts a three-dimensional framework. • The energy band gap of AgGaSiSe{sub 4} is enlarged compared with Ag{sub 3}Ga{sub 3}SiSe{sub 8}.

The effects of substituting Ag for In on the magnetoresistance and magnetocaloric properties of Ni-Mn-In Heusler alloys

Directory of Open Access Journals (Sweden)

Sudip Pandey

2016-05-01

Full Text Available The effect of substituting Ag for In on the structural, magnetocaloric, and thermomagnetic properties of Ni50Mn35In15−xAgx (x = 0.1, 0.2, 0.5, and 1 Heusler alloys was studied. The magnitude of the magnetization change at the martensitic transition temperature (TM decreased with increasing Ag concentration. Smaller magnetic entropy changes (ΔSM were observed for the alloys with larger Ag concentrations and the martensitic transition shifted to higher temperature. A shift of TM by about 25 K to higher temperature was observed for an applied hydrostatic pressure of P = 6.6 kbar with respect to ambient pressure. A large drop in resistivity was observed for large Ag concentration. The magnetoresistance was dramatically suppressed due to an increase in the disorder of the system with increasing Ag concentration. Possible mechanisms responsible for the observed behavior are discussed.

Partial substitution of Zn Effects on the Structural and Electrical Properties of High Temperature Hg0.95Ag0.05Ba2Ca2Cu3O8+δ Superconductors

Science.gov (United States)

Abed, Noor S.; Fathi, Sabah J.; Jassim, Kareem A.; Mahdi, Shatha H.

2018-05-01

The effect of the Ag partial substitution at Hg site in HgOδ layer and Zn partial substitution at Ca site in CaO layer on the structure,Tc,electrical properties, and oxygen content for Hg-1223 have been studied. Bulk polycrystalline Hg1-xAgxBa2Ca2-yZnyCu3O8+δ compound samples with x=0.05 and y=0.0, 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3, are synthesized by a solid state reaction process. Structural properties are studied by using X-ray powder pattern, the high temperature phase superconductor (Hg-1223) of the tetragonal structure didn't change with the partial substitution of Zn and Ag ions, lattice parameters c,c/a are established to vary with Ag and Zn- substitution. The surface morphology has been studied by using atomic force microscopes (AFM), showed that all specimens have good crystalline and homogeneous surface. Also give a best nano size value is 75.72 nm at x=0.05 and y=0.3. Four probe technique is used to measure Tc. The Tc were found to be increases from 129 K to 147 K and oxygen content were found to be increases with increasing Zn. In addition, dielectric properties (dielectric constant, dielectric loss factor, and the alternating electrical conductivity) are characterized directly by relating with Ag and Zn concentration.

Effect of Mixed Glass Former on Ionic Conductivity of Silver Boron Tungstate glass system x[0.75AgI:0.25AgCl]: (1-x) [Ag2O-(B2O3:WO3)

International Nuclear Information System (INIS)

Dehariya, Harsha; Kumar, R; Polu, A R

2012-01-01

The idea to explore new 'Superionic Electrolytes', 'Fast ionic conductors' is due to their tremendous potential applications in solid state electrochemical devices viz. solid state batteries, fuel cells, sensors, super capacitors. Superionic glasses have attracted great deal of attention due to their several advantageous over their crystalline counterparts such as high ionic conductivity, easy preparation, wide selection of compositions, isotropic properties and high stability etc [4-7]. Large numbers of silver ion based glasses have been reported in the literature for the glassy system of AgI:Ag2O: MxOy (MxOy = B2O3, SiO2, P2O5, GeO2, V2O5, As2O5, CrO3, SeO2, MoO3 and TeO3 etc many of them shows high silver ion conductivity [8]. Ion transport behavior of Silver Boro Tungstate glass system x[0.75AgI:0.25AgCl]: (1-x) [Ag2O(B2O3:WO3)], where 0 ≤ x ≤ 1 in molar wt% prepared by melt quench technique were reported. The new host [0.75AgI:0.25AgCl] was used as a better alternate in place of conventional host salt AgI. Conductivity measurement were carried out on this glass system as a function of frequency from 50 Hz to 5 MHz, over a temperature range of 27 C to 200 C, for different compositions by Impedance spectroscopy. The composition 0.7[0.75AgI:0.25AgCl]: 0.3[Ag2O(B2O3:WO3)] shows the highest conductivity of the order of σrt ∼ 2.76x10-2 S/cm, referred to as the Optimum Conducting Composition (OCC). The enhancement in the conductivity has been obtained by mixed former effect. XRD result shows that the system is completely amorphous. Temperature dependence of conductivity of all compositions were studied and reported. Activation energies (Ea) were also evaluated from the slope of .Log(σ) vs 1000/T, Arrhenius plots.

AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films for solar cell applications

Energy Technology Data Exchange (ETDEWEB)

González, J.O. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450, México (Mexico); Shaji, S.; Avellaneda, D. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450, México (Mexico); Universidad Autónoma de Nuevo León-CIIDIT, Apodaca, Nuevo León, México (Mexico); Castillo, A.G.; Roy, T.K. Das [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450, México (Mexico); and others

2013-05-15

Highlights: ► AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films were formed by heating Na{sub 2}SeSO{sub 3} dipped Sb{sub 2}S{sub 3}/Ag layers. ► S/Se ratio was varied by changing the dipping time in Na{sub 2}SeSO{sub 3} solution. ► Characterized the films using XRD, XPS, SEM, Optical and electrical measurements. ► Band gap engineering of 1−1.1 eV for x = 0.51 and 0.52 respectively. ► PV Glass/FTO/CdS/AgSb(S{sub x}Se{sub 1−x}){sub 2}/C were prepared showing V{sub oc} = 410 mV, J{sub sc} = 5.7 mA/cm{sup 2}. - Abstract: Silver antimony sulfoselenide (AgSb(S{sub x}Se{sub 1−x}){sub 2}) thin films were prepared by heating glass/Sb{sub 2}S{sub 3}/Ag layers after selenization using sodium selenosulphate solution. First, Sb{sub 2}S{sub 3} thin films were deposited on glass substrates from a chemical bath containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3}. Then Ag thin films were thermally evaporated onto glass/Sb{sub 2}S{sub 3}, followed by selenization by dipping in an acidic solution of Na{sub 2}SeSO{sub 3}. The duration of selenium dipping was varied as 30 min and 2 h. The heating condition was at 350 °C for 1 h in vacuum. Analysis of X-ray diffraction pattern of the thin films formed after heating showed the formation of AgSb(S{sub x}Se{sub 1−x}){sub 2}. Morphology and elemental analysis were done by scanning electron microscopy and energy dispersive X-ray detection. Depth profile of composition of the thin films was performed by X-ray Photoelectron Spectroscopy. The spectral study showed the presence of Ag, Sb, S, and Se, and the corresponding binding energy analysis confirmed the formation of AgSb(S{sub x}Se{sub 1−x}){sub 2}. Photovoltaic structures (PV) were prepared using AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films as absorber and CdS thin films as window layers on FTO coated glass substrates. The PV structures were heated at 60–80 °C in air for 1 h to improve ohmic contact. Analysis of J–V characteristics of the PV structures showed V

Characterization of Ag-doped vanadium oxide (AgxV2O5) thin film for cathode of thin film battery

International Nuclear Information System (INIS)

Hwang, H.S.; Oh, S.H.; Kim, H.S.; Cho, W.I.; Cho, B.W.; Lee, D.Y.

2004-01-01

The effect of silver co-sputtering on the characteristics of amorphous V 2 O 5 films, grown by dc reactive sputtering, is investigated. The co-sputtering process influences the growth mechanism as well as the characteristics of the V 2 O 5 films. X-ray diffraction (XRD), Inductively coupled plasma-atomic emission spectrometry (ICP-AES), field emission-scanning electron microscopy (FE-SEM), Fourier transform infrared spectrometry (FT-IR) and X-ray photoelectron spectrometry (XPS) results indicate that the microstructure of the V 2 O 5 films is affected by the rf power of the co-sputtered silver. In addition, an all-solid-state thin film battery with full cell structure of Li/LiPON/Ag x V 2 O 5 /Pt has been fabricated. It is found that the silver co-sputtered V 2 O 5 cathode film exhibits better cycle performance than an undoped one

Effect of Mixed Glass Former on Ionic Conductivity of Silver Boro Tungstate glass system x[0.75AgI:0.25AgCl]: (1-x) [Ag2O-{B2O3:WO3}

Science.gov (United States)

Dehariya, Harsha; Kumar, R.; Polu, A. R.

2012-05-01

The idea to explore new 'Superionic Electrolytes', "Fast ionic conductors" is due to their tremendous potential applications in solid state electrochemical devices viz. solid state batteries, fuel cells, sensors, super capacitors. Superionic glasses have attracted great deal of attention due to their several advantageous over their crystalline counterparts such as high ionic conductivity, easy preparation, wide selection of compositions, isotropic properties and high stability etc [4-7]. Large numbers of silver ion based glasses have been reported in the literature for the glassy system of AgI:Ag2O: MxOy (MxOy = B2O3, SiO2, P2O5, GeO2, V2O5, As2O5, CrO3, SeO2, MoO3 & TeO3 etc many of them shows high silver ion conductivity [8]. Ion transport behavior of Silver Boro Tungstate glass system x[0.75AgI:0.25AgCl]: (1-x) [Ag2O{B2O3:WO3}], where 0 <= x <= 1 in molar wt% prepared by melt quench technique were reported. The new host [0.75AgI:0.25AgCl] was used as a better alternate in place of conventional host salt AgI. Conductivity measurement were carried out on this glass system as a function of frequency from 50 Hz to 5 MHz, over a temperature range of 27°C to 200°C, for different compositions by Impedance spectroscopy. The composition 0.7[0.75AgI:0.25AgCl]: 0.3[Ag2O{B2O3:WO3}] shows the highest conductivity of the order of σrt ~ 2.76 × 10-2 S/cm, referred to as the Optimum Conducting Composition (OCC). The enhancement in the conductivity has been obtained by mixed former effect. XRD result shows that the system is completely amorphous. Temperature dependence of conductivity of all compositions were studied & reported. Activation energies (Ea) were also evaluated from the slope of .Log(σ) vs 1000/T, Arrhenius plots.

Pressure dependence of Raman modes in the chalcopyrite quaternary alloy AgxCu1-xGaS2

International Nuclear Information System (INIS)

Choi, In-Hwan; Yu, Peter Y.

2000-01-01

Raman scattering in the chalcopyrite quaternary alloy Ag x Cu 1-x GaS 2 has been studied under high pressure (up to 7 GPa) and at low temperature (50 K) using a diamond anvil high pressure cell for alloy concentrations x=1, 0.75, 0.5, 0.25 and 0. This has allowed us to determine the dependence of their zone-center phonon modes on both pressure and alloy concentration. The resultant phonon pressure coefficients are helpful in understanding the nature of the phonon modes in these chalcopyrites

Preparation and electrochemical performance of AgxLi1-xV3O8

International Nuclear Information System (INIS)

Sun Junli; Jiao Lifang; Yuan Huatang; Liu Li; Wei Xin; Miao Yanli; Yang Lin; Wang Yongmei

2009-01-01

We report here the preparation of Ag-doped LiV 3 O 8 for use as a cathode material in rechargeable lithium ion batteries. Synthesis was carried out by sol-gel methods and low temperature calcination using V 2 O 5 wet gel, LiOH.H 2 O, and AgNO 3 as raw materials. The product was characterized by X-ray diffraction (XRD), and its electrochemical behavior as a cathode material was studied by galvanostatic charge-discharge, cyclic voltammetry, and ac impedance techniques. The experimental results show that Ag-doped LiV 3 O 8 cathodes have greater initial discharge capacity than undoped cathode. And those Ag-doped LiV 3 O 8 electrodes, especially Ag 0.04 Li 0.96 V 3 O 8 , show the best long-life cycling performance. All of the doped powders show better stability at the 2.6 V plateau efficiency, due to their more stable cell impedance

Piezoelectric and opto-electrical properties of silver-doped ZnO nanorods synthesized by low temperature aqueous chemical method

Directory of Open Access Journals (Sweden)

E. S. Nour

2015-07-01

Full Text Available In this paper, we have synthesized Zn1−xAgxO (x = 0, 0.03, 0.06, and 0.09 nanorods (NRs via the hydrothermal method at low temperature on silicon substrate. The characterization and comparison between the different Zn1−xAgxO samples, indicated that an increasing Ag concentration from x = 0 to a maximum of x = 0.09; All samples show a preferred orientation of (002 direction with no observable change of morphology. As the quantity of the Ag dopant was changed, the transmittances, as well as the optical band gap were decreased. X-ray photoelectron spectroscopy data clearly indicate the presence of Ag in ZnO crystal lattice. A nanoindentation-based technique was used to measure the effective piezo-response of different concentrations of Ag for both direct and converse effects. The value of the piezoelectric coefficient (d33 as well as the piezo potential generated from the ZnO NRs and Zn1−xAgxO NRs was found to decrease with the increase of Ag fraction. The finding in this investigation reveals that Ag doped ZnO is not suitable for piezoelectric energy harvesting devices.

Synthesis and antibacterial evaluation of calcinated Ag-doped nano-hydroxyapatite with dispersibility.

Science.gov (United States)

Furuzono, Tsutomu; Motaharul, Mazumder; Kogai, Yasumichi; Azuma, Yoshinao; Sawa, Yoshiki

2015-05-01

Dispersible hydroxyapatite (HAp) nanoparticles are very useful for applying a monolayer to implantable medical devices using the nano-coating technique. To improve tolerance to infection on implanted medical devices, silver-doped HAp (Ag-HAp) nanoparticles with dispersiblity and crystallinity were synthesized, avoiding calcination-induced sintering, and evaluated for antibacterial activity. The Ca10-xAgx(PO4)6(OH)2 with x = 0 and 0.2 were prepared by wet chemical processing at 100°C. Before calcination at 700°C for 2 h, two kinds of anti-sintering agents, namely a Ca(NO3)2 (Ca salt) and a polyacrylic acid/Ca salt mixture (PAA-Ca), were used. Escherichia coli was used to evaluate the antibacterial activity of the nanopowder. When PAA-Ca was used as an anti-sintering agent in calcination to prepare the dispersible nanoparticles, strong metallic Ag peaks were observed at 38.1° and 44.3° (2θ) in the X-ray diffraction (XRD) profile. However, the Ag peak was barely observed when Ca salt was used alone as the anti-sintering agent. Thus, using Ca salt alone was more effective for preparation of dispersible Ag-HAp than PAA-Ca. The particle average size of Ag-HAp with 0.5 mol% of Ag content was found to be 325 ± 70 nm when the formation of large particleaggregations was prevented, as determined by dynamic light scattering instrument. The antibacterial activity of the Ag-HAp nanoparticles possessing 0.5 mol% against E. coli was greater than 90.0%. Dispersible and crystalline nano Ag-HAp can be obtained by using Ca salt alone as an anti-sintering agent. The nanoparticles showed antibacterial activity.

Valor Nutritivo de Silagens de Híbridos de Sorgo (Sorghum bicolor (L. Moench sob Doses Crescentes de Adubação Nutritive Value of Five Sorghum Hybrids (Sorghum bicolor (L. Moench Silages under Increasing Fertilization Levels

Directory of Open Access Journals (Sweden)

Magno José Duarte Cândido

2002-02-01

Full Text Available Avaliou-se o valor nutritivo das silagens de cinco híbridos de sorgo (AG2002, AG2005E, AGX202, AGX213 e AGX215, cultivados sob doses crescentes de adubação (tratamento sem adubação, 0,5; 1,0; e 2,0 vezes a recomendação de adubação, consistindo de 0; 45,5; 91; e 182 kg/ha de N; 0; 49; 98; e 196 kg/ha de P2O5 ; e 0; 14; 28; e 56 kg/ha de K2O, além de 0; 42; 84; e 168 kg/ha de S, respectivamente, advindos da utilização de sulfato de amônio em cobertura, adotando-se o esquema fatorial 5x4 no delineamento em blocos casualizados, com quatro repetições. O plantio foi realizado no dia 06.11.1997, e as parcelas foram colhidas com os grãos no estádio farináceo. De cada parcela útil retirou-se uma amostra para enchimento dos silos experimentais, que, após 60 dias, foram abertos e amostrados novamente para se proceder à pré-secagem e às determinações do valor nutritivo (PB, fração fibrosa e DIVMS. Os dados foram interpretados por análise de variância e regressão, desdobrando-se a interação híbrido x adubo independentemente da sua significância. Os fatores qualitativos foram comparados, utilizando-se o teste de Tukey. Os modelos foram escolhidos, baseando-se na significância dos coeficientes de regressão, utilizando o teste de "t", Student, a 10% de probabilidade, e no coeficiente de determinação. O valor nutritivo das silagens diferiu entre os híbridos, observando-se maior valor nutritivo para a silagem do AG2005E, enquanto as silagens do AG2002 e do AGX213 apresentaram maior produção de nutrientes por unidade de área. O valor nutritivo das silagens foi afetado pelas doses de recomendação de adubação, embora de forma inconsistenteThe nutritive value of five sorghum hybrids (AG-2002, AG-2005E, AG-X202, AG-X213 and AG-X215 silages, cultivated under increasing fertilization levels (control, 0.5, 1.0, and 2.0 times of the recommended fertilization, corresponding to 0, 45.5, 91, and 182 kg/ha N; 0, 49, 98, and 196 kg

X-ray spectroscopy results for the pristine nanosilver solution and solution after undergoing the specific usage scenario

Data.gov (United States)

U.S. Environmental Protection Agency — The results demonstrate the Ag 3d5/2-3/2 spectrum of the pristine AgNPs. Furthermore, the XAS spectra from the analysis of the nanosilver solution (ASAP-AGX-32)...

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

Science.gov (United States)

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

2014-01-01

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

Phase diagrams of two dimensional Pd{sub x}Ag{sub 1-x}/Pd(111) and Pt{sub x}Ag{sub 1-x}/Pt(111) surface alloys

Energy Technology Data Exchange (ETDEWEB)

Engstfeld, Albert K.; Roetter, Ralf T.; Bergbreiter, Andreas; Hoster, Harry E.; Behm, R. Juergen [Institute of Surface Chemistry and Catalysis, Ulm University (Germany)

2011-07-01

The distribution of Ag and Pd or Pt in Ag{sub x}Pd{sub 1-x}/Pd(111) and Ag{sub x}Pt{sub 1-x}/Pt(111) surface alloys was studied by high resolution UHV-STM. The alloys were prepared by evaporating Ag on the respective substrate and subsequent annealing to 800 K. From quantitative 2D atom distributions we can show that AgPt tends towards two dimensional clustering and AgPd towards a 'quasi' random distribution, with small deviations for low and high coverages. From effective pair interactions, we are able to calculate the surface mixing energy and determine 2D phase diagrams. Furthermore we will elucidate whether the size mismatch or the differences in the intermetallic bonding are the dominant factor for the respective distribution in the surface alloy.

Photochemical modification of magnetic properties in organic low-dimensional conductors

International Nuclear Information System (INIS)

Naito, Toshio; Kakizaki, Akihiro; Wakeshima, Makoto; Hinatsu, Yukio; Inabe, Tamotsu

2009-01-01

Magnetic properties of organic charge transfer salts Ag(DX) 2 (DX=2,5-dihalogeno-N,N'-dicyanoquinonediimine; X=Cl, Br, I) were modified by UV irradiation from paramagnetism to diamagnetism in an irreversible way. The temperature dependence of susceptibility revealed that such change in magnetic behavior could be continuously controlled by the duration of irradiation. The observation with scanning electron microprobe revealed that the original appearance of samples, e.g. black well-defined needle-shaped shiny single crystals, remained after irradiation irrespective of the irradiation conditions and the duration. Thermochemical analysis and X-ray diffraction study demonstrated that the change in the physical properties were due to (partial) decomposition of Ag(DX) 2 to AgX, which was incorporated in the original Ag(DX) 2 lattices. Because the physical properties of low-dimensional organic conductors are very sensitive to lattice defects, even a small amount of AgX could effectively modify the electronic properties of Ag(DX) 2 without making the original crystalline appearance collapse. - Graphical abstract: By UV irradiation with appropriate masks, a part of single crystal of organic conductors irreversibly turned diamagnetic retaining their original crystalline shapes.

Thermodynamic properties of solid solutions in the system Ag2S–Ag2Se

International Nuclear Information System (INIS)

Pal’yanova, G.A.; Chudnenko, K.V.; Zhuravkova, T.V.

2014-01-01

We have summarized experimental data on the phase diagram of the system Ag 2 S–Ag 2 Se. Standard thermodynamic functions of four solid solutions in this system have been calculated using the model of regular and subregular solutions: a restricted fcc solid solution γ-Ag 2 S-Ag 2 S 1−x Se x (x 2 S–Ag 2 Se, monoclinic solid solution (α) from Ag 2 S to Ag 2 S 0.4 Se 0.6 , and orthorhombic solid solution (α) from Ag 2 S 0.3 Se 0.7 to the Ag 2 Se. G mix and S mix have been evaluated using the subregular model for asymmetric solution for the region Ag 2 S 0.4 Se 0.6 –Ag 2 S 0.3 Se 0.7 . The thermodynamic data can be used for modeling in complex natural systems and in matters of semiconductor materials

Híbridos de Sorgo (Sorghum bicolor (L. Moench Cultivados sob Níveis Crescentes de Adubação: Rendimento, Proteína Bruta e Digestibilidade in Vitro Sorghum (Sorghum bicolor (L. Moench Hybrids Cultivated under Increasing Fertilization Levels: Yield, Crude Protein and in Vitro Digestibility

Directory of Open Access Journals (Sweden)

Miguel Marques Gontijo Neto

2002-07-01

Full Text Available Objetivou-se com este trabalho avaliar o rendimento forrageiro, os teores de proteína bruta (PB e a digestibilidade in vitro de matéria seca (DIVMS de cinco híbridos de sorgo forrageiro (AG-2002, AG-2005E, AG-X202, AG-X213 e AG-X215, cultivados sob quatro níveis de adubação NPK. Utilizou-se o delineamento em blocos casualizados, em um esquema fatorial 5 x 4 com quatro repetições. Os híbridos avaliados apresentaram altas produções médias de MS/ ha e resposta linear positiva, em função da adubação, ressalvando a alta produtividade (15,47 t/ha nas parcelas sem adubação, em função da fertilidade do solo e das condições climáticas. Os híbridos apresentaram respostas diferenciadas quanto aos teores de PB, em função da adubação, predominando respostas quadráticas, determinando o comportamento quadrático da produção de proteína bruta. A DIVMS e a produção de matéria seca digestiva apresentaram respostas lineares positivas em função da adubação, sendo a produção de matéria seca digestível fortemente correlacionada (0,91** com o aumento da produção de MS/ha.The objective of this research was to evaluate the forage yield, crude protein (CP contents and dry matter (DM in vitro digestibility of five forage sorghum hybrids (AG-2002, AG-2005E, AG-X202, AG-X213 e AG-X215, cultivated under four NPK fertilization levels. A randomized blocks design, in a 5 x 4 factorial scheme, with four replicates, was used. The evaluated hybrids showed high average DM/ha yield and positive linear answer in function of fertilization, except for the high productivity (15.47 t/ha in the plots without fertilization, in function of soil fertilization and climatic conditions. The hybrids showed different answers for the CP contents, according to the fertilization, in a quadratic way, determining the quadratic behavior for the crude protein yield. IVDMD and digestive dry matter yield showed positive linear answers in function of

Ag on Ge(111): 2D x-ray structure analysis of the #sq root#3 x #sq root#3 superstructure

DEFF Research Database (Denmark)

Dornisch, D.; Moritz, W.; Schulz, H.

1992-01-01

We have studied the Ag/Ge(111) square-root 3 x square-root 3 superstructure by grazing-incidence X-ray diffraction. In our structural analysis we find striking similarities to the geometry of Au on Si(111). The Ag atoms form trimer clusters with an Ag-Ag distance of 2.94 +/- 0.04 angstrom...

Flower-like Ag/AgCl microcrystals: Synthesis and photocatalytic activity

International Nuclear Information System (INIS)

Daupor, Hasan; Wongnawa, Sumpun

2015-01-01

Silver/silver chloride (Ag/AgCl) composites with a novel flower-like morphology were prepared via a hot precipitation assisted by the vinyl acetate monomer (VAM) route. An aqueous solution of AlCl 3 was mixed with the vinyl acetate monomer and acetic acid before adding a AgNO 3 solution at a temperature of 100 °C. The octapod shaped flower-like Ag/AgCl particles (or “flower-like Ag/AgCl” hereinafter) has eight petals each of which was about 7–11 μm in length. The flower-like octapods were formed by preferential overgrowth along the <111> directions of the cubic seeds. Detailed studies of the growth process at different AlCl 3 concentrations revealed that the concave cube developed into a Rubik's cube where eight corners grew further into the flower-like structures. The VAM and acetic acid concentration strongly affected the growth of the Ag/AgCl to the flower-like structure and their optimum concentrations were determined. The morphologies of these particles were carefully examined by scanning electron microscopy (SEM). The crystal structures and orientation relationship were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–visible diffused reflectance spectroscopy (DRS). The flower-like Ag/AgCl microcrystals were tested for their photocatalytic degradation of orange G dye (OG) catalyzed by visible light. From comparative test runs, the flower-like Ag/AgCl exhibited better photocatalytic activity than simple and commercial Ag/AgCl particles. - Highlights: • Interesting transformation of microcrystals Ag/AgCl from concave cube via Rubik's cube to flower-like shape. • The first to use VAM as morphology control reagent. • High photocatalytic activity under visible light irradiation

Selective Oxidation of Styrene to Benzaldehyde by Co-Ag Codoped ZnO Catalyst and H2O2 as Oxidant

Directory of Open Access Journals (Sweden)

Abderrazak Aberkouks

2018-01-01

Full Text Available Various ratio of Co-Ag supported on ZnO have been evaluated in the selective catalytic oxidation of styrene to benzaldehyde, using H2O2 as an oxidant. The catalysts were prepared by a sol-gel process and were characterized using XRD, FT-IR, TG-DTG, BET, and SEM/EDX. The performance of the prepared catalyst was investigated under different parameters such as solvent, temperature, substrate/oxidant molar ratios, reaction time, and doping percent. The Zn1−x−yAgxCoyO catalysts exhibit a good activity and a high selectivity towards benzaldehyde (95% with the formation of only 5% of acetophenone.

Transformaciones de fase en aleaciones Zn-22%Al-2%Cu y Zn-22%Al-2%Cu-X (X = 1, 2 y 3%Ag envejecidas isotérmicamente

Directory of Open Access Journals (Sweden)

Flores-Ramos, Alfredo

2014-12-01

Full Text Available The study of phase transformations that take place in Zn-22%Al-2%Cu and Zn-22%Al-2%Cu-X (X = 1, 2 and 3%Ag alloys was carried out using X-Ray Diffraction (XRD and Scanning Electron Microscopy (SEM. Alloys were homogenized at 350 °C during 10 days and quenched at ~2 °C. Subsequently, samples were aged at 200 °C for different times. The initial microstructure consists in a matrix of fine equiaxial grains of α and η phases for all the alloys. Besides isolated particles of ε and Φ were observed without and with Ag addition, respectively. During the aging, the four phase reaction, α + ε→η + τ’, takes place to obtain the equilibrium η, α and τ’ phases. However, the Ag addition promotes the formation of the Φ phase, which retards or inhibits the four phase reaction. The stability of the Φ phase is obtained with 3%Ag, which could improve the dimensional stability of the alloy for future industrial applications.En el presente estudio sobre las transformaciones de fase en las aleaciones Zn-22%Al-2%Cu y Zn-22%Al-2%Cu-X (X = 1, 2 y 3%Ag se utilizó Difracción de Rayos X (DRX y Microscopía Electrónica de Barrido (MEB. Las aleaciones fueron homogeneizadas a 350 °C durante 10 días, templadas a ~2 °C y posteriormente envejecidas a 200 °C durante diferentes tiempos. Todas las aleaciones ensayadas presentaron una microestructura inicial formada por una matriz de granos finos y equiaxiales de las fases α y η. Además, para las aleaciones sin Ag se observa la presencia de partículas de la fase ε (CuZn4 y de Φ ((Ag, Cu Zn4 en las que se adicionó Ag. Durante el envejecido, ocurre la reacción de cuatro fases, α + ε→η + τ’, para obtener las fases de equilibrio η, α y τ’. Sin embargo, la adición de Ag promueve la formación de la fase Φ, la cual retarda e incluso inhibe la reacción de cuatro fases. La estabilidad de la fase Φ se obtiene con 3%Ag, lo que podría mejorar la estabilidad dimensional de la aleación para

thermal, electrical and structural characterization of fast ion conducting glasses (Ag Br)x(AgPO)1-x

International Nuclear Information System (INIS)

Kartini, E.; Yufus, S.; Priyanto, T; Indayaningsih, N; Collins, M F

2001-01-01

Fast ion conducting glasses are of considerable technological interest because of their possible application in batteries, sensors, and displays. One of the main scientific challenges is to explain how the disordered structure of the glass is related to the high ionic conductivity that can be achieved at ambient temperature. Fast ion conducting glasses (AgBr) x (AgPO3) 1- x with x=0.0; 0.2; 0.3; 0.4; 0.5; 0.7; and 0.85 were prepared by rapid quenching. The studies of structure, thermal property and electrical conductivity have been made. The X-ray diffraction patterns of this system show that the sample are glasses for x 0.5. The neutron diffraction data shows that all AgBr doped glasses exhibit a strong and relatively sharp diffraction peak at anomalously low momentum transfer value, Q∼ 0.7 Α - 1. The low Q-peak is not observed in AgPO 3 glass, and in the X-ray data. The results of electrical conductivity show that the conduction is essentially ionic and due to silver ions alone. The logarithm of the ionic conductivity increases with increasing AgBr mole fraction, and reaches maximum for x = 0.5. The thermal property results measured by differential scanning calorimetric show that the temperatures of the glass transition, the crystallization and the melt reach minimum for the glass with composition x 0.5. We conclude that there appears to be a relation between higher conductivity at ambient temperature, and the low Q-peak. Based on this investigation a better fast ion conducting glass proposed is (AgBr) 0 .5(AgPO 3 ) 0 .5 with the conductivity of 8 x 10 - 5 S/cm

Model and experimental investigation of frequency conversion in AgGaGexS2(1+x) (x = 0, 1) crystals

International Nuclear Information System (INIS)

Wang Tiejun; Kang Zhihui; Zhang Hongzhi; Feng Zhishu; Jiang Yun; Gao Jinyue; Andreev, Yury M; Lanskii, Gregory V; Shaiduko, Anna V

2007-01-01

Analysis of available and developed data on phase matching in AgGaGe x S 2(1+x) (x = 0, 1) crystals is carried out. Nanosecond AgGaS 2 type I optical parametric oscillator with a continuously tunable range 2.65-5.29 μm is demonstrated pumped by a Q-switched Nd : YAG laser. An output pulse energy of up to 0.56 mJ at 4 μm is recorded. Phase matching of second harmonic generation in both crystals is represented. Best sets of Sellmeier equations for two crystals are determined

Anomalous Hall effect and magnetoresistance behavior in Co/Pd1−xAgx multilayers

KAUST Repository

Guo, Z. B.

2013-02-13

In this paper, we report anomalous Hall effect (AHE) correlated with the magnetoresistance behavior in [Co/Pd1-xAg x]n multilayers. For the multilayers with n = 6, the increase in Ag content from x = 0 to 0.52 induces the change in AHE sign from negative surface scattering-dominated AHE to positive interface scattering-dominated AHE, which is accompanied with the transition from anisotropy magnetoresistance (AMR) dominated transport to giant magnetoresistance (GMR) dominated transport. For n = 80, scaling analysis with Rs ∝ρ xx γ yields γ ∼ 3.44 for x = 0.52 which presents GMR-type transport, in contrast to γ ∼ 5.7 for x = 0 which presents AMR-type transport. © 2013 American Institute of Physics.

A simple solution-phase approach to synthesize high quality ternary AgInSe2 and band gap tunable quaternary AgIn(S1-xSe x)2 nanocrystals

KAUST Repository

Bai, Tianyu; Li, Chunguang; Li, Feifei; Zhao, Lan; Wang, Zhaorui; Huang, He; Chen, Cailing; Han, Yu; Shi, Zhan; Feng, Shouhua

2014-01-01

in detail and different reaction conditions all have a great impact on the growth and morphology of the nanocrystals. Alloyed AgIn(S1-xSex)2 nanocrystals with controlled composition across the entire range (0 ≤ x ≤ 1) was also successfully prepared

Electrical conductivity studies in (Ag3AsS3)x(As2S3)1-x superionic glasses and composites

Science.gov (United States)

Studenyak, I. P.; Neimet, Yu. Yu.; Kranjčec, M.; Solomon, A. M.; Orliukas, A. F.; Kežionis, A.; Kazakevičius, E.; Šalkus, T.

2014-01-01

Compositional, frequency, and temperature studies of impedance and electrical conductivity in (Ag3AsS3)x(As2S3)1-x superionic glasses and composites were performed. Frequency range from 10 Hz to 3 × 109 Hz and temperature interval 300-400 K were used for the measurements. Compositional dependences of electrical conductivity and activation energy are analyzed; the most substantial changes are observed with the transition from (Ag3AsS3)0.4(As2S3)0.6 glass to (Ag3AsS3)0.5(As2S3)0.5 composite. With increase of Ag3AsS3 content, the investigated materials are found to have crystalline inclusions and show the two-phase composite nature. Addition of Ag3AsS3 leads to the increase of electrical conductivity whereas the activation energy decreases.

Development and Application of TiO2 Nanoparticles Coupled with Silver Halide

Directory of Open Access Journals (Sweden)

Xiaojia Wan

2014-01-01

Full Text Available Titanium dioxide (TiO2 is proposed to be effective photocatalyst for wastewater treatment, air purification, and self-cleaning ability, because of its strong oxidation and superhydrophilicity. In order to conquer the limits of TiO2, a variety of methods have been used. This paper presents a critical review of novel research and achievements in the modification of TiO2 nanoparticles with silver halide (AgX, X=Cl, Br, I, which aims at enhancing the visible light absorption and photosensitivity. Herein we study the synthesis, physical and chemical properties, and the mechanism of this composite photocatalyst.

Thermal Co-Decomposition of Silver Acetylacetonate and Tin (II) Hexafluoroacetylacetonate: Formation of Carbonaceous Ag/AgxSn(x=4 and 6.7)/SnO2 Composites

Czech Academy of Sciences Publication Activity Database

Křenek, T.; Duchek, P.; Urbanová, Markéta; Pokorná, Dana; Bezdička, Petr; Jakubec, Ivo; Pola, M.; Čerstvý, R.; Kovářík, T.; Galíková, Anna; Pola, Josef

2013-01-01

Roč. 566, AUG 20 (2013), s. 92-99 ISSN 0040-6031 Grant - others:GA MŠK(CZ) CZ1.05/2.1.00/03.0088 Institutional support: RVO:67985858 ; RVO:61388980 Keywords : co-decomposition * thermal gravimetric analysis * Ag-Sn intermetallic compounds Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.105, year: 2013

Nanostructured Iron and Manganese Oxide Electrode Materials for Lithium Batteries: Influence of Chemical and Physical Properties on Electrochemistry

Science.gov (United States)

Durham, Jessica L.

The widespread use of portable electronics and growing interest in electric and hybrid vehicles has generated a mass market for batteries with increased energy densities and enhanced electrochemical performance. In order to address a variety of applications, commercially fabricated secondary lithium-ion batteries employ transition metal oxide based electrodes, the most prominent of which include lithium nickel manganese cobalt oxide (LiNixMn yCo1-x-yO2), lithium iron phosphate (LiFePO4), and lithium manganese oxide (LiMn 2O4). Transition metal oxides are of particular interest as cathode materials due to their robust framework for lithium intercalation, potential for high energy density, and utilization of earth-abundant elements (i.e. iron and manganese) leading to decreased toxicity and cost-effective battery production on industrial scales. Specifically, this research focuses on MgFe2O4, AgxMn8O16, and AgFeO 2 transition metal oxides for use as electrode materials in lithium-based batteries. The electrode materials are prepared via co-precipitation, reflux, and hydrothermal methods and characterized by several techniques (XRD, SEM, BET, TGA, DSC, XPS, Raman, etc.). The low-temperature syntheses allowed for precise manipulation of structural, compositional, and/or functional properties of MgFe2O4, AgxMn8 O16, and AgFeO2 which have been shown to influence electrochemical behavior. In addition, advanced in situ and ex situ characterization techniques are employed to study the lithiation/de-lithiation process and establish valid redox mechanisms. With respect to both chemical and physical properties, the influence of MgFe2O4 particle size and morphology on electrochemical behavior was established using ex situ X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) imaging. Based on composition, tunneled AgxMn8O16 nanorods, prepared with distinct Ag+ contents and crystallite sizes, display dramatic differences in ion-transport kinetics due to

Sputtering of two-phase AgxCuγ alloys

International Nuclear Information System (INIS)

Bibic, N.; Milosavljevic, M.; Perusko, D.; Wilson, I.H.

1992-01-01

Elemental sputtering yields from two phase AgCu alloys were measured for 20, 40 and 50 at % Ag. Argon ion bombardment energies were in the range 35-55 keV and the ion dose was 1 x 10 19 ions cm -2 . The sputtering yield for silver was found to be considerably below what was expected by simple selective sputtering of a two component alloy. Analysis by electron probe X-ray microanalysis and scanning electron microscopy of the eroded surface indicated that surface diffusion of copper from copper rich grains and geometrical constraints in the dense cone forest on Cu/Ag eutectic regions combine to reduce the sputtering yield for silver. (author)

Structure of AgxNa1-xPO3 glasses by neutron diffraction and reverse Monte Carlo modelling

International Nuclear Information System (INIS)

Hall, Andreas; Swenson, Jan; Karlsson, Christian; Adams, Stefan; Bowron, Daniel T

2007-01-01

We have performed structural studies of mixed mobile ion phosphate glasses Ag x Na 1-x PO 3 using diffraction experiments and reverse Monte Carlo simulations. This glass system is particularly interesting as a model system for investigations of the mixed mobile ion effect, due to its anomalously low magnitude in the system. As for previously studied mixed alkali phosphate glasses, with a much more pronounced mixed mobile ion effect, we find no substantial structural alterations of the phosphorous-oxygen network and the local coordination of the mobile cations. Furthermore, the mobile Ag + and Na + ions are randomly mixed with no detectable preference for either similar or dissimilar pairs of cations. However, in contrast to mixed mobile ion systems with a very pronounced mixed mobile ion effect, the two types of mobile ions have, in this case, very similar local environments. For all the studied glass compositions the average Ag-O and Na-O distances in the first coordination shell are determined to be 2.5 ± 0.1 and 2.5 ± 0.1 A, and the corresponding average coordination numbers are approximately 3.2 and 3.7, respectively. The similar local coordinations of the two types of mobile ions suggests that the energy mismatch for a Na + ion to occupy a site that previously has been occupied by a Ag + ion (and vice versa) is low, and that this low energy mismatch is responsible for the anomalously weak mixed mobile ion effect

Improvement in the properties of Ag-doped YBa2Cu3O7-x grain boundary Josephson junctions

International Nuclear Information System (INIS)

Bolanos, G.; Baca, E.; Osorio, J.; Prieto, P.

2000-01-01

Ag-doped YBa 2 Cu 3 O 7-x (YBCO) thin films using 5 to 20 wt% Ag-doped YBCO targets have been grown by a DC sputtering technique on SrTiO 3 bicrystals. Critical currents of 4 to 5 x 10 6 A/cm 2 at 77 K were measured in YBCO films doped with 5 wt% Ag which has been found to be higher than the value of 1 x 10 6 A/cm 2 measured in undoped samples. The normal resistivity decreases by a doping of 5 wt% Ag and increases for higher Ag concentrations. The critical temperature, T c , of the Ag-YBCO films remained unchanged at 92 K as in the undoped YBCO samples. An I c R n product of 170 μV at 77 K was found in grain boundary Josephson junctions (GBJJs) with 5 wt% Ag, compared with the value of 100 μV measured in undoped samples at the same temperature. Current-voltage characteristics were measured in GBJJs, showing Shapiro steps under microwave radiation and Fraunhofer patterns with an external magnetic field. The improvement in the normal and superconducting properties of Ag-doped YBCO films has been interpreted using the De Genes model to establish that YBCO containing metallic Ag addition shows a superconductor-normal metal-superconductor (S-N-S) behavior, thereby the Ag-doping enhances the weak link behavior and is, therefore, appropriate for electronic applications. (orig.)

Plasmonic Ag{sub 2}MoO{sub 4}/AgBr/Ag composite: Excellent photocatalytic performance and possible photocatalytic mechanism

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhongliao [College of Physics and Electronic Information, Anhui Key Laboratory of Energetic Materials, Huaibei Normal University, Huaibei, 235000 (China); Zhang, Jinfeng, E-mail: zjf_y2004@126.com [College of Physics and Electronic Information, Anhui Key Laboratory of Energetic Materials, Huaibei Normal University, Huaibei, 235000 (China); Lv, Jiali [College of Physics and Electronic Information, Anhui Key Laboratory of Energetic Materials, Huaibei Normal University, Huaibei, 235000 (China); Dai, Kai, E-mail: daikai940@chnu.edu.cn [College of Physics and Electronic Information, Anhui Key Laboratory of Energetic Materials, Huaibei Normal University, Huaibei, 235000 (China); Liang, Changhao [College of Physics and Electronic Information, Anhui Key Laboratory of Energetic Materials, Huaibei Normal University, Huaibei, 235000 (China); Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031 (China)

2017-02-28

Highlights: • Novel Ag{sub 2}MoO{sub 4}/AgBr/Ag photocatalyst was prepared. • Ag{sub 2}MoO{sub 4}/AgBr/Ag showed high photocatalytic activity. • Ag{sub 2}MoO{sub 4}/AgBr/Ag showed long reusable life. - Abstract: Plasmonic Ag{sub 2}MoO{sub 4}/AgBr/Ag composite is fabricated by in-situ ion exchange and reduction methods at room temperature. The samples are characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance (DRS), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM) and photoluminescence (PL) measurements. The results show that butterfly-like Ag{sub 2}MoO{sub 4} nanosheets served as the precursor, and Ag{sub 2}MoO{sub 4}/AgBr/Ag is formed in phase transformation with MoO{sub 4}{sup 2−} displaced by Br{sup −}. The ternary Ag{sub 2}MoO{sub 4}/AgBr/Ag composite photocatalysts show greatly enhanced photocatalytic activity in photodegrading methylene blue (MB) under visible light irradiation compared with AgBr and Ag{sub 2}MoO{sub 4}. The pseudo-first-order rate constant k{sub app} of Ag{sub 2}MoO{sub 4}/AgBr/Ag is 0.602 min{sup −1}, which is 11.6 and 18.3 times as high as that of AgBr and Ag{sub 2}MoO{sub 4}, respectively. Meanwhile, the efficiency of degradation still kept 90% after ten times cyclic experiments. Eventually, possible photocatalytic mechanism was proposed.

AgSbSe2 and AgSb(S,Se)2 thin films for photovoltaic applications

International Nuclear Information System (INIS)

Garza, J.G.; Shaji, S.; Rodriguez, A.C.; Das Roy, T.K.; Krishnan, B.

2011-01-01

Silver antimony selenide (AgSbSe 2 ) thin films were prepared by heating sequentially deposited multilayers of antimony sulphide (Sb 2 S 3 ), silver selenide (Ag 2 Se), selenium (Se) and silver (Ag). Sb 2 S 3 thin film was prepared from a chemical bath containing SbCl 3 and Na 2 S 2 O 3 , Ag 2 Se from a solution containing AgNO 3 and Na 2 SeSO 3 and Se thin films from an acidified solution of Na 2 SeSO 3 , at room temperature on glass substrates. Ag thin film was deposited by thermal evaporation. The annealing temperature was 350 deg. C in vacuum (10 -3 Torr) for 1 h. X-ray diffraction analysis showed that the thin films formed were polycrystalline AgSbSe 2 or AgSb(S,Se) 2 depending on selenium content in the precursor films. Morphology and elemental analysis of these films were done using scanning electron microscopy and energy dispersive X-ray spectroscopy. Optical band gap was evaluated from the UV-visible absorption spectra of these films. Electrical characterizations were done using Hall effect and photocurrent measurements. A photovoltaic structure: glass/ITO/CdS/AgSbSe 2 /Al was formed, in which CdS was deposited by chemical bath deposition. J-V characteristics of this structure showed V oc = 435 mV and J sc = 0.08 mA/cm 2 under illumination using a tungsten halogen lamp. Preparation of a photovoltaic structure using AgSbSe 2 as an absorber material by a non-toxic selenization process is achieved.

Interaction of Ag with YBa2Cu3O7-x

International Nuclear Information System (INIS)

Shamrai, V.F.; Efimov, Yu.V.; Frolova, T.M.; Myasnikova, E.A.; Postnikov, A.M.

1992-01-01

The aim of the work was to investigate the effect of Ag (0.3 to 20 mass%) on the structure, the composition and some superconducting and magnetic properties of Y-HTSC. The alloys were studied by scanning electron microscopy (in secondary and elastically backscattering electron mode) and X-ray diffraction analysis (DRON-2.0; CuKα-radiation). T c was measured by both resistive and inductive methods at T >> 77 K. The resistivity was determined by four-point technique (Ag solder) at 100 to 300 K and with 1 mA (operating current). Magnetic flux penetration was studied by a mechanical method in sound frequency interval. (orig./MM) [de

Preparation and Characterization of γ-AgI in Superionic Composite Glasses (AgIx(AgPO31-x

Directory of Open Access Journals (Sweden)

S. Suminta

2007-07-01

Full Text Available The γ-AgI phase was stabilized at room temperature in the composites glasses (AgIx(AgPO31-x with x = 0.6 and 0.7 via rapid quenching of their molten mixture. The measurement of the crystal structure has been carried out using an X-ray Difractometer at the Physics Departement of Ibaraki University, Japan. The micro strain and crystal size are derived from Hall’s equation. The X-ray diffraction pattern shows some Bragg peaks that correspond to the crystalline γ-AgI. By increasing the concentration of AgI, the peak width becomes more narrow and the position shifts to the higher angle. This indicates that the crystalline size and microstrain are increasing. The increase of micro strain (η, and particle size (D will increase the ionic mobility, thus increasing the ionic conductivity. It is concluded that solidification process on melt AgI into glass matrix AgPO3 not only decreases the micro strain and the particle size, but it also increases the ionic conductivity.

Avaliação de Diferentes Híbridos de Sorgo (Sorghum bicolor, L. Moench quanto aos Componentes da Planta e Silagens Produzidas Evaluation of Different Sorghum Hybrids (Sorghum bicolor, L. Moench Related to Plant Components and Produced Silages

Directory of Open Access Journals (Sweden)

Mikael Neumann

2002-01-01

Full Text Available O experimento foi conduzido com o objetivo de avaliar as características qualitativas dos componentes da planta e da silagem e as características de fermentação da silagem de diferentes híbridos de sorgo forrageiros AGX-213 e AG-2002 e de duplo propósito AGX-217 e AG-2005E. O componente panícula apresentou maiores teores de matéria seca (MS, proteína bruta (PB, matéria mineral (MM e digestibilidade in vitro da matéria seca (DIVMS e menores teores dos constituintes da parede celular da planta com relação aos componentes colmo e folhas. Não houve diferenças entre as silagens dos híbridos de sorgo para os teores de MM e DIVMS. A silagem do AG-2005E apresentou maior teor de MS (35,50%, PB (6,69%, extrato etéreo (2,28% e extrativos não-nitrogenados (58,56% frente aos demais genótipos. Não houve diferença entre as silagens para os teores de nitrogênio insolúvel na FDA. As silagens de híbridos de sorgo forrageiro (AGX-213 e AG-2002 apresentaram menor pH e teor de N-NH3 (% do N total em comparação aos híbridos de duplo propósito (AGX-217 e AG-2005E.The experiment was conducted with the purpose to evaluate the qualitative traits of the plant components and fermentation characteristics of silages from different sorghum hybrids AGX-213, AG-2002 (forage and AGX-217, AG-2005E (double purpose. The panicle component showed higher percentages of dry matter (DM, crude protein (CP, mineral material (MM and in vitro dry matter digestibility (IVDMD, and lower percentages of plant cell wall than the stems and leaves. No differences were observed among the sorghum silages for MM and IVDMD percentages. The AG-2005E silage showed higher contents of DM (35.5%, CP (6.69%, ether extract (2.28% and nitrogen-free extract (58.56% in comparison with the other genotypes. No difference was observed among the sorghum silages for acid detergent insoluble nitrogen (ADIN content. The silages of the forage hybrids (AGX-213 and AG-2002 showed lower pH and

In-place testing of off-gas iodine filters

International Nuclear Information System (INIS)

Duce, S.W.; Tkachyk, J.W.; Motes, B.G.

1980-01-01

At the Idaho National Engineering Laboratory, both charcoal and silver zeolite (AgX) filters are used for radioactive iodine off-gas cleanup of reactor systems. These filters are used in facilities which are conducting research in the areas of reactor fuel failure, reactor fuel inspection, and loss of fluids from reactor vessels. Iodine retention efficiency testing of these filters is dictated by prudent safety practices and regulatory guidelines. A procedure for determining iodine off-gas filter efficiency in-place has been developed and tested on both AgX and charcoal filters. The procedure involves establishing sample points upstream and downstream of the filter to be tested. A step-by-step approach for filter efficiency testing is presented

Thermodynamic modeling of the Na-X (X = Si, Ag, Cu, Cr systems

Directory of Open Access Journals (Sweden)

Hao D.

2012-01-01

Full Text Available The Na-X (X = Si, Ag, Cu, Cr systems have been critically reviewed and modeled by means of the CALPHAD approach. The two compounds, NaSi and Ag2Na, are treated as stoichiometric ones. By means of first-principles calculations, the enthalpies of formation at 0 K for the LT-NaSi (low temperature form of NaSi and Ag2Na have been computed to be -5210 and -29821.8 Jmol-1, respectively, with the desire to assist thermodynamic modeling. One set of self-consistent thermodynamic parameters is obtained for each of these binary systems. Comparisons between calculated and measured phase diagrams show that most of the experimental information can be satisfactorily accounted for by the present thermodynamic descriptions.

High field magneto-transport study of YBa{sub 2}Cu{sub 3}O{sub 7}:Ag{sub x} (x = 0.00–0.20)

Energy Technology Data Exchange (ETDEWEB)

Rani, Poonam; Pal, Anand; Awana, V.P.S, E-mail: awana@mail.npindia.org

2014-02-15

Highlights: •YBCO: Ag{sub x} composites. •High field magneto-transport. •The upper critical field. -- Abstract: We report high field (up to 13 T) magneto transport [ρ(T)H] of YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO):Ag{sub x} (x = 0.0, 0.1 and 0.2) composites. The transport properties are significantly improved by Ag doping on the insulating grain boundaries of YBCO. Pure and Ag diffused YBCO superconducting samples are synthesised through solid state reaction route. Both pure and Ag doped YBCO are superconducting at below 90 K. Though, the T{sub c} (ρ = 0) of YBCO:Ag samples under applied field of 13 T is around 65 K, the same is 45 K for pure YBCO under same applied field. The upper critical field [H{sub c2}(0)], being estimated from ρ(T)H is around 70 T for pristine sample, and is above 190 T for Ag doped samples. The boarding of the resistive transition under applied magnetic field is comparatively less and nearly single step for Ag doped samples, while the same is clearly two step and relatively much larger for the pristine YBCO. The resistive broadening is explained on the basis of changed inter-granular coupling and thermally activated flux flow (TAFF). The TAFF activation energy (U{sub 0}) is found to be linear with applied magnetic field for all the samples, but with nearly an order of magnitude less value for the Ag doped samples. Summarily, it is shown that inclusion of Ag significantly improves the superconducting performance of YBCO:Ag composites, in particular under applied field.

SU-E-T-259: Particle Swarm Optimization in Radial Dose Function Fitting for a Novel Iodine-125 Seed

Energy Technology Data Exchange (ETDEWEB)

Wu, X [University of Alabama at Birmingham, Birmingham, Al (United States); Duan, J; Popple, R; Huang, M; Shen, S; Brezovich, I [University of Alabama Birmingham, Birmingham, AL (United States); Cardan, R [UAB University of Alabama, Birmingham, Birmingham, AL (United States); Benhabib, S [University of Alabama at Birmingham, Birmingham, AL (United States)

2014-06-01

Purpose: To determine the coefficients of bi- and tri-exponential functions for the best fit of radial dose functions of the new iodine brachytherapy source: Iodine-125 Seed AgX-100. Methods: The particle swarm optimization (PSO) method was used to search for the coefficients of the biand tri-exponential functions that yield the best fit to data published for a few selected radial distances from the source. The coefficients were encoded into particles, and these particles move through the search space by following their local and global best-known positions. In each generation, particles were evaluated through their fitness function and their positions were changed through their velocities. This procedure was repeated until the convergence criterion was met or the maximum generation was reached. All best particles were found in less than 1,500 generations. Results: For the I-125 seed AgX-100 considered as a point source, the maximum deviation from the published data is less than 2.9% for bi-exponential fitting function and 0.2% for tri-exponential fitting function. For its line source, the maximum deviation is less than 1.1% for bi-exponential fitting function and 0.08% for tri-exponential fitting function. Conclusion: PSO is a powerful method in searching coefficients for bi-exponential and tri-exponential fitting functions. The bi- and tri-exponential models of Iodine-125 seed AgX-100 point and line sources obtained with PSO optimization provide accurate analytical forms of the radial dose function. The tri-exponential fitting function is more accurate than the bi-exponential function.

Preparation of Ag{sub 2}O/Ag{sub 2}CO{sub 3}/MWNTs composite photocatalysts for enhancement of ciprofloxacin degradation

Energy Technology Data Exchange (ETDEWEB)

Wang, Huiqin [School of Materials Science & Engineering, Jiangsu University, Zhenjiang 212013 (China); Li, Jinze [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Huo, Pengwei, E-mail: huopw1@163.com [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Institute of Green Chemistry and Chemical Technology, Jiangsu University, Zhenjiang 212013 (China); Yan, Yongsheng [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Institute of Green Chemistry and Chemical Technology, Jiangsu University, Zhenjiang 212013 (China); Guan, Qingfeng [School of Materials Science & Engineering, Jiangsu University, Zhenjiang 212013 (China)

2016-03-15

Graphical abstract: - Highlights: • Ag{sub 2}O/Ag{sub 2}CO{sub 3}/MWNTs were prepared by calcination of the obtained precipitate. • The holes were main contributor for the degradation processes of ciprofloxacin. • The synergistic effect enhanced the activity and stability of composites. - Abstract: The Ag{sub 2}O/Ag{sub 2}CO{sub 3}/multi-walled carbon nanotube (MWNTs) composite photocatalysts were prepared by calcination of the obtained precipitate. The structures and morphology of as-prepared composite photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS). The Ag{sub 2}O/Ag{sub 2}CO{sub 3}/MWNTs composite photocatalysts exhibit higher degradation rate of ciprofloxacin (CIP) than the pure Ag{sub 2}CO{sub 3}, Ag{sub 2}O/Ag{sub 2}CO{sub 3} and Ag{sub 2}CO{sub 3}/MWNTs under visible light irradiation. The amount of loaded Ag{sub 2}CO{sub 3} onto MWNTs and calcined time for Ag{sub 2}CO{sub 3}/MWNTs were systematically investigated, and the optimal amount of loaded Ag{sub 2}CO{sub 3} and calcined time of Ag{sub 2}CO{sub 3}/MWNTs are 150 wt% and 10 min, respectively. The highest photocatalytic degradation rate of CIP could reach 76% under optimal conditions. The active species trapping experiments were also analyzed, the results show that the holes are main contributor for the degradation processes of CIP, furthermore the electrons, ·O{sub 2}{sup −} and ·OH are also crucially influenced the photocatalytic degradation processes of CIP. The possible photocatalytic processes of CIP with Ag{sub 2}O/Ag{sub 2}CO{sub 3}/MWNTs composite photocatalyst are also proposed.

Room temperature synthesis and photocatalytic property of AgO/Ag2Mo2O7 heterojunction nanowires

International Nuclear Information System (INIS)

Hashim, Muhammad; Hu, Chenguo; Wang, Xue; Wan, Buyong; Xu, Jing

2012-01-01

Graphical abstract: The AgO nanoparticles are attached on the surface of the Ag 2 Mo 2 O 7 nanowires to form a heterojunction structure. The AgO nanoparticles start embedding into the nanowires with increasing reaction temperature or time. Highlights: ► AgO/Ag 2 Mo 2 O 7 heterojunction NWs were synthesized at room temperature for the first time. ► AgO particles embed into the Ag 2 Mo 2 O 7 NWs with increase in reaction time and temperature. ► The heterojunction NWs display much better photocatalytic activity than the none-heterojunction NWs. ► The catalytic mechanism was proposed. -- Abstract: AgO/Ag 2 Mo 2 O 7 heterojunction nanowires were synthesized at temperatures of 25 °C, 50 °C, 80 °C, and 110 °C, under magnetic stirring in solution reaction. The catalytic activity of AgO/Ag 2 Mo 2 O 7 nanowires was evaluated by the degradation of Rhodmine B dye under the irradiation of the simulated sunlight. The synthesized samples were characterized by X-ray diffractometer, energy dispersive spectrometry, X-ray photoelectron spectrometer, scanning electron microscopy, and transmission electron microscopy. The results show that the AgO nanoparticles are attached on the surface of the Ag 2 Mo 2 O 7 nanowires to form a heterojunction structure. The length of the nanowires is up to 10 μm and the size of the AgO nanoparticles is 10–20 nm. The length of nanowires increases with increasing reaction time and temperature while the AgO particles are gradually embedded into the nanowires. The photocatalytic activity is greatly improved for the AgO/Ag 2 Mo 2 O 7 heterojunction nanowires compared with that of the pure Ag 2 Mo 2 O 7 nanowires, indicating a remarkable role of AgO particles on the Ag 2 Mo 2 O 7 nanowires in the photodegradation.

Effect of second introduced phase on magnetic and magnetotransport properties of (1-x)La0.7Sr0.3Mn0.9Co0.1O3/x% Ag (x=0%, 2%, 4%) nanocomposites

Science.gov (United States)

Shah, Hiral D.; Bhalodia, J. A.

2018-05-01

The structural, magnetic and magnetotransport properties of (1-x)La0.7Sr0.3Mn0.9Co0.1O3(LSMCO)/x% Ag (x=0%, 2%, 4%) nanocomposites were investigated to explore the role of second introduced phase. (1-x) LSMCO/x% Ag (x=0%, 2%, 4%) nanocomposites are prepared via solid-state reaction method. X-ray diffraction (XRD) and SEM analysis indicated that x% of Ag are not substituted into the main LSMCO phase and remains an additive to the second phase at grain boundaries [1]. The structural parameters and the reliability factors for all the samples were successfully determined by the Rietveld refinement. Magnetization and transport properties of (1-x)LSMCO/x% Ag nanocomposites have been reported. Resistivity of the composite samples increases with Ag content in comparison with the pure LSMCO, and suppressed with applied magnetic field in all the composite samples [2]. The metal-insulator transition (TMI) and accompanied paramagnetic-ferromagnetic transition (TC) temperatures decrease with increase in Ag content. The electrical resistivity of the experimental results is explored by theoretical model below TMI. The maximum MR was observed to be 55% in the x=4% sample at 5 K temperature under 7 T magnetic field, this value is larger than that of pure LSMCO (19% at 5 K and 7 T), which is encouraging for practical application. Summarily, the addition of Ag in LSMCO improves MR% values significantly due to the more grain boundary contribution and result in better physical properties of the parent manganite system.

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

Science.gov (United States)

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

2017-11-01

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

Properties of Y Ba2 Cu3 O7-x-Ag prepared by the citrate technique

International Nuclear Information System (INIS)

Fonseca, Fabio Coral

1996-01-01

Y Ba 2 Cu 3 O 7-x (Y123) ceramic superconductor and YBa 2 Cu 3 O 7-x- Ag composite superconductors have been prepared by the citrate technique. Microstructural analysis has been done by X-ray diffractometry and optical ceramography. The superconducting behavior has been studied by 4 probe dc electrical resistivity in the 77 K - 140 K temperature range. Silver percolation in the ceramic matrix was studied by electrical resistivity measurements at room temperature; the percolation threshold was found to be approximately 25 vol. % (35.5 wt. %) Ag. Specimens with silver addition showed improvement in the flexural strength of the Y123 compound. The main results show that the critical temperatures does not depend on the silver content in the composite specimens, the normal state electrical behavior of the superconductor is affected by silver addition and approximately 3 wt. % (1.8 vol. %) Ag doping yields and optimized composite superconductor from the electrical, mechanical and microstructural pont of view, with platelet-like grain shapes. (author)

Staging structures of the intercalation compounds Ag/sub x/TiS2

International Nuclear Information System (INIS)

Bardhan, K.K.; Kirczenow, G.; Jackle, G.; Irwin, J.C.

1986-01-01

An extensive investigation of the structure, and in particular the staging, of powdered samples of the intercalation compounds Ag/sub x/TiS 2 (0 0 C. The (T,x) phase diagram contains three phases: a high-x (dense) stage-1 phase, a stage-disordered phase, which at low x or high temperatures appears to become a pure low-x (dilute) stage-1 phase, and a simple stage-2 phase. On the high-x side of its stability region the stage-2 phase undergoes an apparent first-order transition to the dense stage-1 phase, but on the high-temperature side it proceeds continuously, through stage-disordered states, to a dilute stage-1 phase. On the low-x side of the stage-2 region there is also a dilute stage-1 phase. At sufficiently high temperatures a novel coexistence of the two stage-1 phases is observed. This is the first time that the high-temperature stability limit of the stage-2 region has been probed in any intercalation compound. The results are compared with recent theoretical models

Effect of silver doping on infrared reflectance and Tc of superconducting GdBa2Cu(1 - x)3Ag3xO7

International Nuclear Information System (INIS)

Memon, A.; Khan, M.N.; Al-Dallal, S.; Tanner, D.B.; Porter, C.D.

1990-01-01

This paper reports on infrared reflectance of GdBa 2 Cu(1 - x) 3 Ag 3x O 7 ceramic superconductor with the composition of x = 0.025 and 0.05 performed in the frequency range of 100--5000 cm -1 . All the infrared active phonon modes allowed by the selection rules were observed in the reflection spectra of these compounds. The optical conductivity as calculated from K--K analysis further confirms the existence of these optical phonons. Besides the increase of the reflectivity in the silver doped samples, an extra phonon mode is observed, which is normally not seen at room temperature reflectance of GdBa 2 Cu 3 O 7 compounds. The four probe resistivity measurement show zero resistance at 88 K for x = 0, and 78 K for x = 0.025 in GdBa 2 Cu(1 - x) 3 Ag 3x O 7 compound

Homogeneous-inhomogeneous models of Ag x (Ge0.25Se0.75)100-x bulk glasses

International Nuclear Information System (INIS)

Arcondo, B.; Urena, M.A.; Piarristeguy, A.; Pradel, A.; Fontana, M.

2007-01-01

Ge-Se system presents an extensive glass forming composition range even when different metals (Ag, Sb, Bi) are added. In spite that the addition of Ag (up to 30 at%) to Ge-Se does not affect substantially the glass forming tendency, it impacts significantly on the transport properties. (Ge 0.25 Se 0.75 ) 100- x Ag x is a fast ionic conductor with x≥8 at% whereas it is a semiconductor for x 0.25 Se 0.75 ) 100- x Ag x bulk samples. These results appear to sustain this model. However previous structural and thermal studies oppose it. Moessbauer spectrometry on samples (0≤x≤25) containing 0.5 at% of 57 Fe is performed at T≤300 K. The main contribution to the glasses spectra correspond to low spin Fe 2+ in octahedral coordination and high spin Fe 2+ in distorted octahedral environments. The relative population of both sites changes continuously as Ag concentration varies denoting that the change in the transport behavior obeys to a percolation phenomenon. The low temperature results are discussed with the aim to throw light on the controversy about the homogeneity-inhomogeneity of the studied bulk glasses

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

Directory of Open Access Journals (Sweden)

Shuanglong Lin

2016-10-01

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

An experimental investigation of ionic transport properties in CuI-Ag2WO4 and CuI-Ag2CrO4 mixed systems

International Nuclear Information System (INIS)

Suthanthiraraj, S. Austin; Premchand, Y. Daniel

2004-01-01

The phenomenon of ionic transport in the case of two different mixed systems (CuI) (1-x) -(Ag 2 WO 4 ) x (0.15= (1-y) -(Ag 2 CrO 4 ) y (0.15= -3 Scm -1 for the composition (CuI) 0.45 -(Ag 2 WO 4 ) 0.55 and 1.1x10 -4 Scm -1 in the case of (CuI) 0.55 -(Ag 2 CrO 4 ) 0.45 at room temperature has been discussed in terms of the observed characteristics

Understanding the Composition Dependence of the Fragility of AgI-Ag2O-MxOy Glassy Systems

International Nuclear Information System (INIS)

Aniya, M

2011-01-01

It has been reported that the fragility in the AgI-Ag 2 O-M x O y (M = B, Ge, P, Mo) system is determined by Ag 2 O-M x O y and does not depend on the amount of AgI. This is an interesting result and provides a hint to understand the nature of the glassy state of these materials. However, the origin of such behavior has not been sufficiently discussed. In the present report a model for the above behavior is presented. According to the model, the behavior arises from the solid like nature of the network formed by Ag 2 O-M x O y and the liquid like AgI which flow between the networks. The model is consistent with the structural model of superionic glasses proposed previously.

First-principles calculations of dynamical and thermodynamic properties of cuprite doped with silver (Cu2(1‑x)Ag2xO)

Science.gov (United States)

Musari, A. A.; Joubert, D. P.; Adebayo, G. A.

2018-04-01

Cuprite (Cu2O) is a solid mineral and a compound whose simplicity of preparation, non toxic nature, low band gap and its abundance has made it a prospective candidate for the realisation of low cost photovoltaic applications. The present work successfully dopes Cuprite with Ag ({{{Cu}}}2(1-{{x})}{{{Ag}}}2{{x}}{{O}}) at different concentrations x = 0, 0.25, 0.5, 0.75 and 1, their first-principle calculations of their electronic, dynamical and thermodynamic properties have been investigated extensively within the generalised gradient approximation. Direct band gap energies at {{Γ }} are predicted for all the studied systems. A small bowing parameter for lattice constants ba and bulk modulus bB of 0.4245 \\mathring{{A}} and 0.8747 GPa were obtained when compared to Vegard’s law. The results of phonon dispersion when x = 0 and 1 indicate stability, these agree with available theoretical and experimental results while negative frequencies observed along the Brillouin zone for the doped systems when x = 0.25, 0.5 and 0.75 imply that they are dynamically unstable. The thermodynamic properties between 0 to 800 K were determined using the calculated phonon density of states within the harmonic approximation and the values of the specific heat capacity at constant volume at ambient temperature and the temperature at which lattice vibrations and thermal motion of electrons contribute to the constant volume specific heat capacity are presented for all the systems.

LaCu_6-xAg_x: A promising host of an elastic quantum critical point

Energy Technology Data Exchange (ETDEWEB)

Poudel, Lekh [ORNL; Dela Cruz, Clarina R. [ORNL; Koehler, Michael R. [University of Tennessee, Knoxville (UTK); McGuire, Michael A. [ORNL; Keppens, Veerle [University of Tennessee, Knoxville (UTK); Mandrus, David [ORNL; Christianson, Andrew D. [ORNL

2018-05-01

Structural properties of LaCu_6-xAg_x have been investigated using neutron and x-ray diffraction, and resonant ultrasound spectroscopy (RUS) measurements. Diffraction measurements indicate a continuous structural transition from orthorhombic (Pnma) to monoclinic (P2₁/C) structure. RUS measurements show softening of natural frequencies at the structural transition, consistent with the elastic nature of the structural ground state. The structural transition temperatures in LaCu_6-xAg_x decrease with Ag composition until the monoclinic phase is completely suppressed at x_c=0.225. All of the evidence is consistent with the presence of an elastic quantum critical point in LaCu_6-xAg_x.

AgSbSe{sub 2} and AgSb(S,Se){sub 2} thin films for photovoltaic applications

Energy Technology Data Exchange (ETDEWEB)

Garza, J.G. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Shaji, S. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Facultad de Ingenieria Mecanica y Electrica, CIIDIT - Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); Rodriguez, A.C.; Das Roy, T.K. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Krishnan, B., E-mail: kbindu_k@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Facultad de Ingenieria Mecanica y Electrica, CIIDIT - Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

2011-10-01

Silver antimony selenide (AgSbSe{sub 2}) thin films were prepared by heating sequentially deposited multilayers of antimony sulphide (Sb{sub 2}S{sub 3}), silver selenide (Ag{sub 2}Se), selenium (Se) and silver (Ag). Sb{sub 2}S{sub 3} thin film was prepared from a chemical bath containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3}, Ag{sub 2}Se from a solution containing AgNO{sub 3} and Na{sub 2}SeSO{sub 3} and Se thin films from an acidified solution of Na{sub 2}SeSO{sub 3}, at room temperature on glass substrates. Ag thin film was deposited by thermal evaporation. The annealing temperature was 350 deg. C in vacuum (10{sup -3} Torr) for 1 h. X-ray diffraction analysis showed that the thin films formed were polycrystalline AgSbSe{sub 2} or AgSb(S,Se){sub 2} depending on selenium content in the precursor films. Morphology and elemental analysis of these films were done using scanning electron microscopy and energy dispersive X-ray spectroscopy. Optical band gap was evaluated from the UV-visible absorption spectra of these films. Electrical characterizations were done using Hall effect and photocurrent measurements. A photovoltaic structure: glass/ITO/CdS/AgSbSe{sub 2}/Al was formed, in which CdS was deposited by chemical bath deposition. J-V characteristics of this structure showed V{sub oc} = 435 mV and J{sub sc} = 0.08 mA/cm{sup 2} under illumination using a tungsten halogen lamp. Preparation of a photovoltaic structure using AgSbSe{sub 2} as an absorber material by a non-toxic selenization process is achieved.

Using Ag/Ag2O/SnO2 Nanocomposites to Remove Malachite Green by a Photocatalytic Process

Science.gov (United States)

Taufik, A.; Paramarta, V.; Prakoso, S. P.; Saleh, R.

2017-03-01

Silver/silver oxide/tin oxide nanocomposites of various weight ratios were synthesized using a microwave-assisted method. The Ag/Ag2O:SnO2 nanoparticle weight ratios used were 25:75, 50:50, and 75:25. All samples were characterized using X-ray diffraction, UV-Vis spectroscopy, Differential Scanning Calorimetry and Thermogravimetric Analysis (TGA). The Ag/Ag2O/SnO2 nanocomposites contained cubic structures provided by the Ag and Ag2O and tetragonal structures provided by the SnO2. The silver resulted in surface plasmon resonance (SPR) at a wavelength of about 435 nm. The silver oxide material was transformed into pure Ag at a temperature of about 370 °C The photocatalytic activity was tested on the degradation of malachite green (MG) from an aqueous solution. The results showed that Ag/Ag2O/SnO2 at a ratio of 50:50 exhibited the best photocatalytic performance for degrading MG under visible-light irradiation. The degradation of MG using Ag/Ag2O/SnO2 nanocomposites followed pseudo first-order kinetic reactions, and electron holes were found to be the main species acting on the degradation process.

Atom distribution and interactions in Ag{sub x}Pt{sub 1-x} and Au{sub x}Pt{sub 1-x} surface alloys on Pt(111)

Energy Technology Data Exchange (ETDEWEB)

Roetter, Ralf T.; Bergbreiter, Andreas; Hoster, Harry E.; Behm, R. Juergen [Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm (Germany)

2009-07-01

The atom distributions in Ag{sub x}Pt{sub 1-x}/Pt(111) and Au{sub x}Pt{sub 1-x}/Pt(111) surface alloys were studied by high resolution UHV-STM. These surfaces were prepared by submonolayer Ag (Au) metal deposition on Pt(111), followed by annealing at 900 K or 1000 K, respectively, which in both cases results in surface confined 2D alloys, with equilibrated distribution of the components. Both systems show a tendency towards two-dimensional clustering, which fits well to their known bulk immiscibility. Effective cluster interactions (ECIs) will be derived by a quantitative evaluation of the 2D atom distributions in the surface alloys. By comparing the ECIs for PtAg and PtAu on Pt(111), and considering that Ag and Au have almost similar lattice constants, the results allow conclusion on the physical origin of the tendency for clustering.

The (AgInSe{sub 2}){sub 1-x}(VSe){sub x} system (0{<=}x{<=}0.5): X-ray diffraction and differential thermal analysis measurements

Energy Technology Data Exchange (ETDEWEB)

Duran, S.; Grima, P.; Quintero, M.; Ruiz, J. [Centro de Estudio en Semiconductores (C.E.S.), Dpto. Fisica, Fac. Ciencias, Universidad de Los Andes, Merida (Venezuela); Munoz, M. [Centro de Estudio en Semiconductores (C.E.S.), Dpto. Fisica, Fac. Ciencias, Universidad de Los Andes, Merida (Venezuela); Ceballos, L. [Laboratorio de Cristalografia, Dpto. Quimica, Fac. Ciencias, Universidad de Los Andes, Merida (Venezuela); Briceno, J.M. [Laboratorio de Analisis Quimico y Estructural (LAQUEM), Dpto. Fisica, Fac. Ciencias, Universidad de Los Andes, Merida (Venezuela); Romero, H. [Laboratorio de Magnetismo de Solidos, Dpto. Fisica, Fac. Ciencias, Universidad de Los Andes, Merida (Venezuela)

2005-08-01

Polycrystalline samples of the (AgInSe{sub 2}){sub 1-x}(VSe){sub x} system were prepared by the melt and anneal method. The anneal temperature was 900 K and the anneal time one month. The step composition was 0.1 and the weight of each sample approximately 1 g. Additionally, the composition x=1/3 was also prepared, since these alloys have been reported as electronic, i.e. definite compounds exist in the diagram at precise values of composition, one of them x=1/3. The stoichiometric relation of the samples was investigated by SEM technique. The experimental values, in average, are very close to the nominal values, all of them lying inside the interval of the experimental error ({+-}5%). X-Ray Diffraction (XRD) and Differential Thermal Analysis (DTA) techniques were used for characterization of the alloy samples. Guinier photographs were obtained for all the samples and unit cell parameters were calculated using the available software for indexation. The diffraction patterns show sharp lines indicating good thermal equilibrium of the samples. Transition temperatures obtained from DTA measurements were manually obtained from the T vs. T graph with the criteria that the transition occurs at the intersection of the base line with the slope of the thermal transition peak, as usually. From the analysis of the experimental results it was observed that the solid solubility of VSe in AgInSe{sub 2} is approximately 20%, i.e. the single-phase region exists in the composition range 0{<=}x<0.2, whereas for x>0.2 at least two phases coexist. A schematic T-x phase diagram is proposed. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Crystallographic information of intermediate phases in binary Mg–X (X=Sn, Y, Sc, Ag alloys

Directory of Open Access Journals (Sweden)

Dongyan Liu

2015-09-01

Full Text Available The compositions and structures of thermodynamically stable or metastable precipitations in binary Mg-X (X=Sn, Y, Sc, Ag alloys are predicted using ab-initio evolutionary algorithm. The geometry optimizations of the predicted intermetallic compounds are carried out in the framework of density functional theory (DFT [1]. A complete list of the optimized crystallographic information (in cif format of the predicted intermetallic phases is presented here. The data is related to “Predictions on the compositions, structures, and mechanical properties of intermediate phases in binary Mg–X (X=Sn, Y, Sc, Ag alloys” by Liu et al. [2].

Piezoelectric properties and thermal stability of (Na0.53K0.47-xAgx)Nb1-xSbxO3 ceramics

International Nuclear Information System (INIS)

Zheng, Limei; Wang, Jinfeng; Wang, Chunming; Gai, Zhigang; Wu, Qingzao; Zhang, Rui

2011-01-01

Many (K 1-x Na x )NbO 3 (KNN)-based ceramics with high piezoelectric performance exhibit undesirable strong temperature dependence due to the orthorhombic-tetragonal polymorphic phase transition near room temperature. In order to improve the temperature stability of the ceramics, many additives have been added into the KNN-based ceramics to shift T O-T down to below room temperature. Contrary to the previous approach (Na 0.53 K 0.47-x Ag x )Nb 1-x Sb x O 3 (NKANS) ceramics with T O-T well above room temperature have been prepared by a conventional solid-state reaction method. The density and the electrical properties are effectively improved by the addition of AgSbO 3 , and optimum piezoelectric properties are found in the ceramics with 0.05 ≤ x ≤ 0.07, with maximum k p ∝ 0.46 for NKANS5 and maximum d 33 ∝ 199 pC/N for NKANS7. More importantly, k p remains virtually almost unchanged up to the T O-T temperature (≥100 C), indicating that the NKANS ceramics exhibit a much improved piezoelectric thermal stability. The analyses suggest that both the high T O-T value and diffuse orthorhombic-tetragonal phase transition should be responsible for the good temperature stability. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Transformation from Ag@Ag{sub 3}PO{sub 4} to Ag@Ag{sub 2}SO{sub 4} hybrid at room temperature: preparation and its visible light photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Wei, Ting; Gao, Shanmin, E-mail: gaosm@ustc.edu; Wang, Qingyao; Xu, Hui [Ludong University, College of Chemistry and Materials Science (China); Wang, Zeyan; Huang, Baibiao, E-mail: bbhuang@sdu.edu.cn; Dai, Ying [Shandong University, State Key Laboratory of Crystal Materials (China)

2017-02-15

In the present study, Ag/Ag{sub 2}SO{sub 4} hybrid photocatalysts were obtained via a facile redox–precipitation reaction approach by using Ag@Ag{sub 3}PO{sub 4} nanocomposite as the precursor and KMnO{sub 4} as the oxidant. Multiple techniques, such as X-ray diffraction pattern (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS) and Brunauer–Emmett–Teller (BET), photocurrent and electrochemical impedance spectroscopy (EIS), were applied to investigate the structures, morphologies, optical, and electronic properties of as-prepared samples. The photocatalytic activities were evaluated by photodegradation of organic rhodamine B (RhB) and methyl orange (MO) under visible light irradiation. It was found that pure Ag{sub 2}SO{sub 4} can partially transform into metallic Ag during the photocatalytic degradation of organic pollutants, but the Ag/Ag{sub 2}SO{sub 4} hybrids can maintain its structure stability and show enhanced visible light photocatalytic activity because of the surface plasma resonance effect of the metallic Ag.

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

Energy Technology Data Exchange (ETDEWEB)

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

2008-08-11

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

The (AgInSe2)1-x(VSe)x system (0≤x≤0.5): X-ray diffraction and differential thermal analysis measurements

International Nuclear Information System (INIS)

Duran, S.; Grima, P.; Quintero, M.; Ruiz, J.; Munoz, M.; Ceballos, L.; Briceno, J.M.; Romero, H.

2005-01-01

Polycrystalline samples of the (AgInSe 2 ) 1-x (VSe) x system were prepared by the melt and anneal method. The anneal temperature was 900 K and the anneal time one month. The step composition was 0.1 and the weight of each sample approximately 1 g. Additionally, the composition x=1/3 was also prepared, since these alloys have been reported as electronic, i.e. definite compounds exist in the diagram at precise values of composition, one of them x=1/3. The stoichiometric relation of the samples was investigated by SEM technique. The experimental values, in average, are very close to the nominal values, all of them lying inside the interval of the experimental error (±5%). X-Ray Diffraction (XRD) and Differential Thermal Analysis (DTA) techniques were used for characterization of the alloy samples. Guinier photographs were obtained for all the samples and unit cell parameters were calculated using the available software for indexation. The diffraction patterns show sharp lines indicating good thermal equilibrium of the samples. Transition temperatures obtained from DTA measurements were manually obtained from the T vs. T graph with the criteria that the transition occurs at the intersection of the base line with the slope of the thermal transition peak, as usually. From the analysis of the experimental results it was observed that the solid solubility of VSe in AgInSe 2 is approximately 20%, i.e. the single-phase region exists in the composition range 0≤x 0.2 at least two phases coexist. A schematic T-x phase diagram is proposed. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

SEM-EDS Observation of Structure Changes in Synthetic Zeolites Modified for CO2 Capture Needs

Science.gov (United States)

Wdowin, Magdalena; Panek, Rafal; Franus, Wojciech

Carbon dioxide is the main greenhouse gas and its amount still increase in the atmosphere. Air pollution and greenhouse effect caused by CO2 emission have become a major threat to the environment on a global scale. Carbon dioxide sequestration (i.e. capture and consequently geological storage) is the key strategy within the portfolio of actions to reduce CO2 emission to the atmosphere. The most costly stage is capture of CO2, therefore there is a need to search new solutions of this technology. For this purpose it was examined Na-X synthetic zeolites, that were silver and PEI (polyethyleneimine) activated. SEM-EDS investigation enable to find a changes in structure of this materials after treatment. Where, as a result of silver activation from EDS analysis it is seen that Ag occur in Na-X structure, what indicate a substitution of Ag2+ for Na+ ions in crystal lattice. Analysing wt% the EDS analysis has shown that zeolite Na-X after silver impregnation becomes Ag-X zeolite. For Na-X-PEI activated it is observed a distinct organic compound in the form of coatings on Na-X crystals causing a sealing of pores in tested zeolite. Further examination of these materials concern determination of surface properties and experiments of CO2 sorption. But SEM-EDS analysis enable to determine the extent of activation, what is very important in determination of optimal conditions for such treatment in order to obtain better sorbent of CO2.

Cytotoxicity of serum protein-adsorbed visible-light photocatalytic Ag/AgBr/TiO2 nanoparticles

International Nuclear Information System (INIS)

Seo, Ji Hye; Jeon, Won Il; Dembereldorj, Uuriintuya; Lee, So Yeong; Joo, Sang-Woo

2011-01-01

Highlights: ► Photocytotoxicity of visible-light catalytic NPs was examined in vitro. ► Ag/AgBr/TiO 2 NPs were well internalized in cells after adsorption of serum proteins. ► Cell viability was decreased by 40–60% using ∼8 ppm NPs and 60 W/cm 2 visible light within 5 h. ► Mitochondria activity test indicated the reactive oxygen species for photo-destruction of cells. ► Ag/AgBr/TiO 2 NPs were found to eliminate xenograft tumors significantly in vivo. - Abstract: Photocytotoxicity of visible-light catalytic Ag/AgBr/TiO 2 nanoparticles (NPs) was examined both in vitro and in vivo. The Ag/AgBr/TiO 2 NPs were prepared by the deposition–precipitation method. Their crystalline structures, atomic compositions, and light absorption property were examined by X-ray diffraction (XRD) patterns, X-ray photoelectron (XPS) intensities, and ultraviolet-visible (UV–vis) diffuse reflectance spectroscopic tools. The Ag/AgBr/TiO 2 NPs appeared to be well internalized in human carcinoma cells as evidenced by transmission electron microscopy (TEM). The cytotoxicity of cetylmethylammonium bromide (CTAB) appeared to be significantly reduced by adsorption of serum proteins in the cellular medium on the NP surfaces. Two types of human cervical HeLa and skin A431 cancer cells were tested to check their viability after the cellular uptake of the Ag/AgBr/TiO 2 NPs and subsequent exposure to an illumination of visible light from a 60 W/cm 2 halogen lamp. Fluorescence images taken to label mitochondria activity suggest that the reactive oxygen species should trigger the photo-destruction of cancer cells. After applying the halogen light illumination for 50–250 min and ∼8 ppm (μg/mL) of photocatalytic Ag/AgBr/TiO 2 NPs, we observed a 40–60% selective decrease of cell viability. Ag/AgBr/TiO 2 NPs were found to eliminate xenograft tumors significantly by irradiating visible light in vivo for 10 min.

Synergetic interaction between neighbouring platinum monomers in CO2 hydrogenation

Science.gov (United States)

Li, Hongliang; Wang, Liangbing; Dai, Yizhou; Pu, Zhengtian; Lao, Zhuohan; Chen, Yawei; Wang, Menglin; Zheng, Xusheng; Zhu, Junfa; Zhang, Wenhua; Si, Rui; Ma, Chao; Zeng, Jie

2018-05-01

Exploring the interaction between two neighbouring monomers has great potential to significantly raise the performance and deepen the mechanistic understanding of heterogeneous catalysis. Herein, we demonstrate that the synergetic interaction between neighbouring Pt monomers on MoS2 greatly enhanced the CO2 hydrogenation catalytic activity and reduced the activation energy relative to isolated monomers. Neighbouring Pt monomers were achieved by increasing the Pt mass loading up to 7.5% while maintaining the atomic dispersion of Pt. Mechanistic studies reveal that neighbouring Pt monomers not only worked in synergy to vary the reaction barrier, but also underwent distinct reaction paths compared with isolated monomers. Isolated Pt monomers favour the conversion of CO2 into methanol without the formation of formic acid, whereas CO2 is hydrogenated stepwise into formic acid and methanol for neighbouring Pt monomers. The discovery of the synergetic interaction between neighbouring monomers may create a new path for manipulating catalytic properties.

Low-cost spray-processed Ag{sub 1−x}Cu{sub x}InS{sub 2} nano-films: Structural and functional investigation within the Lattice Compatibility Theory framework

Energy Technology Data Exchange (ETDEWEB)

Gherouel, D. [Unité de Physique des Dispositifs à Semi-conducteurs, Faculté des Sciences de Tunis, Tunis El Manar University, 2092 Tunis (Tunisia); Yumak, A. [Physics Department, The Faculty of Arts and Science,Marmara University, 34722 Göztepe, Istanbul (Turkey); Znaidi, M. [Institut Préparatoire Aux Etudes d’Ingénieurs de Nabeul, Merazka, 8000 Nabeul (Tunisia); Bouzidi, A. [Unité de Physique des Dispositifs à Semi-conducteurs, Faculté des Sciences de Tunis, Tunis El Manar University, 2092 Tunis (Tunisia); Boubaker, K., E-mail: mmbb11112000@yahoo.fr [Unité de Physique des Dispositifs à Semi-conducteurs, Faculté des Sciences de Tunis, Tunis El Manar University, 2092 Tunis (Tunisia); Yacoubi, N. [Institut Préparatoire Aux Etudes d’Ingénieurs de Nabeul, Merazka, 8000 Nabeul (Tunisia); Amlouk, M. [Unité de Physique des Dispositifs à Semi-conducteurs, Faculté des Sciences de Tunis, Tunis El Manar University, 2092 Tunis (Tunisia)

2015-08-15

Highlights: • Cu{sub x}Ag{sub 1−x}InS{sub 2} with a minimal lattice mismatch between absorbers and buffers. • The lattice compatibility for understanding silver–copper kinetics. • Controlled and enhanced spray pyrolisis method as a low-cost synthesis protocol. - Abstract: This work deals with some structural and optical investigations about Cu{sub x}Ag{sub 1−x}InS{sub 2} alloys sprayed films and the beneficial effect of copper incorporation in AgInS{sub 2} ternary matrices. The main purpose of this work is to obtain the band gap energy E{sub g} as well as different lattice parameters. The studied properties led to reaching minimum of lattice mismatch between absorber and buffer layers within solar cell devices. As a principal and original finding, the lattice compatibility between both silver and copper indium disulfide structures has been proposed as a guide for understanding kinetics of these materials crystallization.

Directly coupled direct current superconducting quantum interference device magnetometers based on ramp-edge Ag:YBa2Cu3O7-x/PrBa2Cu3O7-x/Ag:YBa2Cu3O7-x junctions

International Nuclear Information System (INIS)

Jia, Q.X.; Yan, F.; Mombourquette, C.; Reagor, D.

1998-01-01

Directly coupled dc superconducting quantum interference device (SQUID) magnetometers on LaAlO 3 substrates were fabricated using ramp-edge superconductor/normal-metal/superconductor junctions, where Ag-doped YBa 2 Cu 3 O 7-x was used for the electrode and PrBa 2 Cu 3 O 7-x for the normal-metal barrier. A flux noise of 8x10 -6 Φ 0 Hz -1/2 at 10 kHz measured with a dc bias current was achieved at 75 K, which corresponded to a field sensitivity of 400fTHz -1/2 for a magnetometer with a pick-up loop area of 8.5mmx7.5mm. Most significantly, the noise floor increased at lower frequencies with a frequency dependence slightly less than 1/f. The field noise of the SQUID magnetometers increased by only 25% after cycling the devices from zero field to 500 mG. In a static earth close-quote s magnetic field background, the field noise of the SQUID magnetometers increased by less than a factor of 2. copyright 1998 American Institute of Physics

Structural analysis of quaternary Se{sub 85−x}Sb{sub 10}In{sub 5}Ag{sub x} bulk glassy alloys

Energy Technology Data Exchange (ETDEWEB)

Sharma, Rita, E-mail: reetasharma2012@gmail.com; Sharma, Shaveta; Kumar, Praveen; Chander, Ravi; Thangaraj, R.; Mian, M. [Semiconductors Laboratory, Department of Physics, GND University, Amritsar (India)

2015-08-28

The physical properties of chalcogenide semiconductor have attracted much attention recently due to their applications in optical recording media and inorganic resist due to photo induced structural transformations observed in these materials. The bulk samples of Se{sub 85-x}Sb{sub 10}In{sub 5}Ag{sub x} system are prepared by melt-quenching technique. X-ray diffraction technique and RAMAN spectroscopy have been used to study the role of Ag additive on the amorphous/crystalline nature and molecular structure of Se{sub 85}Sb{sub 10}In{sub 5} glassy alloys. The phases Sb{sub 2}Se{sub 3}, In-Sb and In{sub 2}Se{sub 3} has been observed by X-ray diffraction. The formation of AgInSe{sub 2} phase along with the enhancement in intensity has been observed with the Ag addition.Three bands observed by raman spectroscopy for Se85Sb10In5 are at 70 cm-1, 212cm-1 and 252cm-1. The formation of small bands up to wavenumber 188cm{sup -1} and shifting in second band along with the increase in intensity up to sample x=5 has been observed with the Ag addition. The enhancement in intensity in third band with Ag content has been observed.

Molecular structure of virgin and Tg cycled (Ag2Se)x (AsSe)1-x bulk glasses

Science.gov (United States)

Wachtman, Jacob; Chen, Ping; Boochand, P.

2009-03-01

AsSe, the base glass (x = 0) in the titled ternary, is an interesting example of a chalcogenide that is partially de-mixed into As4Se4 molecules segregated from a connected AsSe network, with the latter determining glass network properties. Raman scattering reveals sharp modes of the Realgar molecules that are superimposed on broad modes coming from of the backbone. Upon Tg cycling virgin samples (as quenched melts), the concentration of de-mixed As4Se4 molecules decreases, suggesting that thermally induced polymerization occurs; molecules break up to form part of the connective tissue. Modulated DSC experiments reveal a broad exotherm near 140 ^oC in virgin samples, which becomes nearly extinct in Tg cycled samples. The exotherm may represent Realgar molecules nano-crystallizing as the temperature approaches Tg. Compositional trends in thermal parameters such as Tg(x), δCp(x), and the δHnr(x) as a function of Ag2Se content `x' of the glasses will be reported.

Sustainable Poly(Ionic Liquids) for CO2 Capture Based on Deep Eutectic Monomers

KAUST Repository

Isik, Mehmet; Zulfiqar, Sonia; Edhaim, Fatimah; Ruiperez, Fernando; Rothenberger, Alexander; Mecerreyes, David

2016-01-01

The design of high performance solid sorbent materials for CO2 capture is a technology which has been employed to mitigate global warming. However, the covalent incorporation of functionalities into polymeric supports usually involves multistep energy-intensive chemical processes. This fact makes the net CO2 balance of the materials negative even though they possess good properties as CO2 sorbents. Here we show a new family of polymers which are based on amines, amidoximes, and natural carboxylic acids and can be obtained using sustainable low energy processes. Thus, deep eutectic monomers based on natural carboxylic acids, amidoximes, and amines have been prepared by just mixing with cholinium type methacrylic ammonium monomer. The formation of deep eutectic monomers was confirmed by differential scanning calorimetry measurements. In all cases, the monomers displayed glass transition temperatures well below room temperature. Computational studies revealed that the formation of eutectic complexes lengthens the distance between the cation and the anion causing charge delocalization. The liquid nature of the resulting deep eutectic monomers (DEMs) made it possible to conduct a fast photopolymerization process to obtain the corresponding poly(ionic liquids). Materials were characterized by means of nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction to evaluate the properties of the polymers. The polymers were then used as solid sorbents for CO2 capture. It has been shown that the polymers prepared with citric acid displayed better performance both experimentally and computationally. The current endeavor showed that sustainable poly(ionic liquids) based on deep eutectic monomers can be easily prepared to produce low-energy-cost alternatives to the materials currently being researched for CO2 capture. © 2016 American Chemical Society.

Sustainable Poly(Ionic Liquids) for CO2 Capture Based on Deep Eutectic Monomers

KAUST Repository

Isik, Mehmet

2016-10-05

The design of high performance solid sorbent materials for CO2 capture is a technology which has been employed to mitigate global warming. However, the covalent incorporation of functionalities into polymeric supports usually involves multistep energy-intensive chemical processes. This fact makes the net CO2 balance of the materials negative even though they possess good properties as CO2 sorbents. Here we show a new family of polymers which are based on amines, amidoximes, and natural carboxylic acids and can be obtained using sustainable low energy processes. Thus, deep eutectic monomers based on natural carboxylic acids, amidoximes, and amines have been prepared by just mixing with cholinium type methacrylic ammonium monomer. The formation of deep eutectic monomers was confirmed by differential scanning calorimetry measurements. In all cases, the monomers displayed glass transition temperatures well below room temperature. Computational studies revealed that the formation of eutectic complexes lengthens the distance between the cation and the anion causing charge delocalization. The liquid nature of the resulting deep eutectic monomers (DEMs) made it possible to conduct a fast photopolymerization process to obtain the corresponding poly(ionic liquids). Materials were characterized by means of nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction to evaluate the properties of the polymers. The polymers were then used as solid sorbents for CO2 capture. It has been shown that the polymers prepared with citric acid displayed better performance both experimentally and computationally. The current endeavor showed that sustainable poly(ionic liquids) based on deep eutectic monomers can be easily prepared to produce low-energy-cost alternatives to the materials currently being researched for CO2 capture. © 2016 American Chemical Society.

Shape-controlled synthesis of polypyrrole/Ag nanostructures in the presence of chitosan.

Science.gov (United States)

Feng, Xiaomiao; Huang, Haiping; Xu, Lin; Zhu, Jun-Jie; Hou, Wenhua

2008-01-01

Polypyrrole (PPy)-coated Ag nanoparticles and nanowires were fabricated through the redox reaction between pyrrole monomer and silver nitrate in the presence of chitosan. The morphologies, compositions, and electrochemical activities of PPy/Ag composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Cyclic voltammetry. The synthetic route employed here is simple and inexpensive and can be extended to prepare other conducting polymer/inorganic nanocomposites.

Visualization of monomer and polymer inside porous stones by using X-ray tomography

International Nuclear Information System (INIS)

Brunetti, Antonio; Princi, Elisabetta; Vicini, Silvia; Pincin, Silvia; Bidali, Simone; Mariani, Alberto

2004-01-01

Estimate of sorption of liquid materials inside porous stones is an important parameter in industrial material testing and cultural heritage conservation. In the latter case, a suitable polymer can be used for both consolidation and conservation, it being applied either in the final form or as its parent monomer, which is subsequently allowed to polymerize in situ by the classical method or by frontal polymerization. However, the sorption of such materials through the stone is often difficult because of their viscosity and/or stone porosity. For this reason, the amount of monomer (or polymer) is a parameter of great interest in order to determine the extent of protection reachable by the treatment. In this paper a new methodology based on X-ray tomography is presented. The methodology makes use of a contrast agent added to the monomer that does not interact with its propagation inside the stone and allows to increase the absorption coefficient and so to observe the monomer inside the sample, which is finally frontally polymerized

Synthesis and photoactivity of the highly efficient Ag species/TiO2 nanoflakes photocatalysts

International Nuclear Information System (INIS)

Liu Yong; Hu Juncheng; Li Jinlin

2011-01-01

Research highlights: → Highly efficient Ag species-TiO 2 nanoflakes catalyst was prepared. → The variety and relative amount of Ag species in TiO 2 can be well tuned. → The enhanced photocatalytic activity can be attributed to the Ag species. - Abstract: Ag species/TiO 2 nanoflakes photocatalysts with different relative contents (Ag + , Ag 2+ , Ag 0 ) have been successfully synthesized by a simple template-free synthetic strategy. X-ray photoelectron spectroscopy, X-ray diffraction, and UV-vis diffuse reflectance spectra indicated that the dopant ions (Ag + or Ag 2+ ) were partly incorporated into the titanium dioxide nanoflakes. Meanwhile, part of the silver ions migrated to the surface after the subsequent calcination and aggregated into ultra-small metallic Ag nanoclusters (NCs) (1-2 nm), which are well dispersed on the surface of TiO 2 nanoflakes. The photocatalytic activities of the Ag species/TiO 2 materials obtained were evaluated by testing the photodegradation of the azo dye reactive brilliant X-3B (X-3B) under near UV irradiation. Interestingly, it was found that the maximum photocatalytic efficiency was observed when Ag species coexisted in three valence states (Ag + , Ag 2+ , Ag 0 NCs), which was higher than that of Degussa P25. The high photocatalytic activity of the Ag species/TiO 2 can be attributed to the synergy effect of the three Ag species.

Electronic structure of Co islands grown on the {radical}3 x {radical}3-Ag/Ge(111) surface

Energy Technology Data Exchange (ETDEWEB)

Huang, Xiao-Lan; Chou, Chi-Hao; Lin, Chun-Liang; Tomaszewska, Agnieszka; Fu, Tsu-Yi, E-mail: phtifu@phy.ntnu.edu.tw

2011-09-30

By means of room temperature scanning tunneling spectroscopy (RT STS), we have studied the electronic structure of two different Ag/Ge(111) phases as well as Co islands grown on the {radical}3 x {radical}3-Ag/Ge (111) forming either {radical}13 x {radical}13 or 2 x 2 patterns. The spectrum obtained from 4 x 4-Ag/Ge(111) structure shows the existence of a shoulder at 0.7 V which is also present in the electronic structure of the Ge(111)-c2 x 8 and indicates donation of Ge electrons to electronic states of the Ag-driven phase. However, this fact is not supported by the electronic spectrum taken from the {radical}3 x {radical}3-Ag/Ge (111). The complexity of the Co-{radical}13 x {radical}13 islands bonding with the substrate is mirrored by a large number of peaks in their electronic spectra. The spectra obtained from the Co-2 x 2 islands which had grown on the step differ from those taken from Co-2 x 2 islands located along the edge of the terrace by a number of peaks at negative sample bias. This discrepancy is elucidated in terms of dissimilarities of Co-substrate interaction accompanying Co islands growth on different areas of the stepped surface.

Preparation, characterization and photocatalytic activity of visible-light-driven plasmonic Ag/AgBr/ZnFe2O4 nanocomposites

International Nuclear Information System (INIS)

Li, Xiaojuan; Tang, Duanlian; Tang, Fan; Zhu, Yunyan; He, Changfa; Liu, Minghua; Lin, Chunxiang; Liu, Yifan

2014-01-01

Highlights: • A plasmonic Ag/AgBr/ZnFe 2 O 4 photocatalyst has been successfully synthesized. • Ag/AgBr/ZnFe 2 O 4 nanocomposites exhibit high visible light photocatalytic activity. • Ag/AgBr/ZnFe 2 O 4 photocatalyst is stable and magnetically separable. - Abstract: A visible-light-driven plasmonic Ag/AgBr/ZnFe 2 O 4 nanocomposite has been successfully synthesized via a deposition–precipitation and photoreduction through a novel one-pot process. X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy were employed to investigate the crystal structure, chemical composition, morphology, and optical properties of the as-prepared nanocomposites. The photocatalytic activities of the nanocomposites were evaluated by photodegradation of Rhodamine B (RhB) and phenol under visible light. The results demonstrated that the obtained Ag/AgBr/ZnFe 2 O 4 nanocomposites exhibited higher photocatalytic activity as compared to pure ZnFe 2 O 4 . In addition, the sample photoreduced for 20 min and calcined at 500 °C achieved the highest photocatalytic activity. Furthermore, the Ag/AgBr/ZnFe 2 O 4 nanocomposite has high stability under visible light irradiation and could be conveniently separated by using an external magnetic field

Crystal Structure of AgBi2I7 Thin Films.

Science.gov (United States)

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

2016-10-06

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

Synthesis of β-AgVO3 nanowires decorated with Ag2CrO4, with improved visible light photocatalytic performance

Science.gov (United States)

Ouyang, Qi; Li, Zhonghua; Liu, Jiawen

2018-05-01

Silver chromate‑silver vanadate (Ag2CrO4/β-AgVO3) heterojunction composites are synthesized through a facile precipitation process. The Ag2CrO4/β-AgVO3 hybrids obtained exhibit better photocatalytic activity in degradation of RhB than both pure Ag2CrO4 and β-AgVO3 under visible light irradiation. The 20 wt% Ag2CrO4/β-AgVO3 heterojunction possesses the best photocatalytic ability for degrading RhB: 24.4 times that of pristine β-AgVO3 nanowires and 3.2 times that of individual Ag2CrO4 particles. The phase of the nanocomposites was analyzed using x-ray diffraction as well as x-ray photoelectron spectroscopy. Their morphology was observed via scanning electron microscopy and transmission electron microscopy. The improvement in photocatalytic performance is chiefly ascribed to the synergies between Ag2CrO4/β-AgVO3 heterostructure, which can enhance the light absorbance ability and also accelerate the separation and transfer of photoinduced electrons and holes under visible light irradiation; this is also confirmed by UV–vis diffuse reflection spectrometry and fluorescence emission spectra.

Medium-range correlation of Ag ions in superionic melts of Ag{sub 2}Se and AgI by reverse Monte Carlo structural modelling-connectivity and void distribution

Energy Technology Data Exchange (ETDEWEB)

Tahara, Shuta; Ohno, Satoru [Faculty of Pharmacy, Niigata University of Pharmacy and Applied Life Sciences, 265-1 Higashijima, Akiha-ku, Niigata 956-8603 (Japan); Ueno, Hiroki; Takeda, Shin' ichi [Department of Physics, Faculty of Sciences, Kyushu University 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Ohara, Koji; Kohara, Shinji [Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Kawakita, Yukinobu [J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

2011-06-15

High-energy x-ray diffraction measurements on molten Ag{sub 2}Se were performed. Partial structure factors and radial distribution functions were deduced by reverse Monte Carlo (RMC) structural modelling on the basis of our new x-ray and earlier published neutron diffraction data. These partial functions were compared with those of molten AgI. Both AgI and Ag{sub 2}Se have a superionic solid phase prior to melting. New RMC structural modelling for molten AgI was performed to revise our previous model with a bond-angle restriction to reduce the number of unphysical Ag triangles. The refined model of molten AgI revealed that isolated unbranched chains formed by Ag ions are the cause of the medium-range order of Ag. In contrast with molten AgI, molten Ag{sub 2}Se has 'cage-like' structures with approximately seven Ag ions surrounding a Se ion. Connectivity analysis revealed that most of the Ag ions in molten Ag{sub 2}Se are located within 2.9 A of each other and only small voids are found, which is in contrast to the wide distribution of Ag-void radii in molten AgI. It is conjectured that the collective motion of Ag ions through small voids is required to realize the well-known fast diffusion of Ag ions in molten Ag{sub 2}Se, which is comparable to that in molten AgI.

The Ag2Se-HgSe-GeSe2 system and crystal structures of the compounds

International Nuclear Information System (INIS)

Parasyuk, O.V.; Gulay, L.D.; Romanyuk, Ya.E.; Olekseyuk, I.D.; Piskach, L.V.

2003-01-01

The phase diagram of the quasi-ternary Ag 2 Se-HgSe-GeSe 2 system at 298 K was investigated using X-ray phase analysis and metallography. The formation of five intermediate quaternary phases β (Ag ∼7.12-∼6.32 Hg ∼0.44-∼0.82 GeSe 6 ), γ (Ag ∼6.08-∼4.00 Hg ∼0.96-∼2.00 GeSe 6 ), δ (Ag 3.4 Hg 2.3 GeSe 6 ), ε (Ag ∼2.24-∼2.00 Hg ∼2.88-∼3.00 GeSe 6 ) and ∼Ag 1.4 Hg 1.3 GeSe 6 was established. The crystal structure of the β-phase (for the Ag 6.504 Hg 0.912 GeSe 6 composition) was determined using X-ray single crystal diffraction. It crystallizes in a cubic structure (space group F4-bar 3m) with the lattice parameter a=1.09026(4) nm. The crystal structure of the δ-phase (Ag 3.4 Hg 2.3 GeSe 6 ) was determined using X-ray powder diffraction (space group F4-bar 3m, a=1.07767(8) nm). The crystal structure determination of the γ-phase (space group Pmn2 1 ) was performed for the compositions Ag 5.6 Hg 1.2 GeSe 6 , Ag 4.8 Hg 1.6 GeSe 6 and Ag 4 Hg 2 GeSe 6 using X-ray powder diffraction. The crystal structure of the LT-Hg 2 GeSe 4 compound (space group I4-bar , a=0.56786(2), c=1.12579(5) nm) was confirmed by powder diffraction also.

Ag screen contacts to sintered YBa/sub 2/Cu/sub 3/O/sub x/ powder for rapid superconductor characterization

International Nuclear Information System (INIS)

Moreland, J.; Goodrich, L.F.

1989-01-01

The authors have developed a new method for making current contacts and voltage taps to YBa/sub 2/Cu/sub 3/O/sub x/ sintered pellets for rapid superconductor characterization. Ag wire screens are interleaved between calcined powder sections and then fired at 930 0 C to form a composite pellet for resistivity and critical current measurements. The Ag diffuses into the powder during the sintering process forming a proximity contact that is permeable to O/sub 2/. Contact surface resistivities (area-resistance product) range from 1 to 10μΩ-cm/sup 2/ at 77 K for the Ag-powder interface. In this configuration, current can be uniformly injected into the ends of the pellet through the bonded Ag screen electrodes. Also, Ag screen voltage contacts, which span a cross section of the pellet, may provide an ideal geometry for detecting voltage drops along the pellet, minimizing current transfer effects

Effect of Ag film thickness on the optical and the electrical properties in CuAlO2/Ag/CuAlO2 multilayer films grown on glass substrates

International Nuclear Information System (INIS)

Oh, Dohyun; No, Young Soo; Kim, Su Youn; Cho, Woon Jo; Kwack, Kae Dal; Kim, Tae Whan

2011-01-01

Research highlights: The CuAlO 2 /Ag/CuAlO 2 multilayer films were grown on glass substrates using radio-frequency magnetron sputtering at room temperature. Effects of Ag film thickness on the optical and the electrical properties in CuAlO 2 /Ag/CuAlO 2 multilayer films grown on glass substrates were investigated. X-ray diffraction patterns showed that the phase of the CuAlO 2 layer was amorphous. Atomic force microscopy images showed that Ag films with a thickness of a few nanometers had island structures. The morphology Ag films with a thickness of 8 nm was uniform. The morphology of the Ag films inserted in the CuAlO 2 films significantly affected the optical transmittance and the resistivity of the CuAlO 2 films deposited on glass substrates. The maximum transmittance of the CuAlO 2 /Ag/CuAlO 2 multilayer films with a thickness of 8 nm was 89.16%. The resistivity of the CuAlO 2 /Ag/CuAlO 2 multilayer films with an Ag film thickness of 18 nm was as small as about 2.8 x 10 -5 Ω cm. The resistivity of the CuAlO 2 /Ag/CuAlO 2 multilayer films was decreased as a result of the thermal annealing treatment. These results indicate that CuAlO 2 /Ag/CuAlO 2 multilayer films grown on glass substrates hold promise for potential applications as TCO films in solar cells. - Abstract: Effects of Ag film thickness on the optical and the electrical properties in CuAlO 2 /Ag/CuAlO 2 multilayer films grown on glass substrates were investigated. Atomic force microscopy images showed that Ag films with a thickness of a few nanometers had island structures. X-ray diffraction patterns showed that the phase of the CuAlO 2 layer was amorphous. The resistivity of the 40 nm-CuAlO 2 /18 nm-Ag/40 nm-CuAlO 2 multilayer films was 2.8 x 10 -5 Ω cm, and the transmittance of the multilayer films with an Ag film thickness of 8 nm was approximately 89.16%. These results indicate that CuAlO 2 /Ag/CuAlO 2 multilayer films grown on glass substrates hold promise for potential applications as

Oligonucleotides with 1,4-dioxane-based nucleotide monomers

DEFF Research Database (Denmark)

Madsen, Andreas S; Wengel, Jesper

2012-01-01

An epimeric mixture of H-phosphonates 5R and 5S has been synthesized in three steps from known secouridine 1. Separation of the epimers has been accomplished by RP-HPLC, allowing full characterization and incorporation of monomers X and Y into 9-mer oligonucleotides using H-phosphonates building...... blocks 5R and 5S, respectively. A single incorporation of either monomer X or monomer Y in the central position of a DNA 9-mer results in decreased thermal affinity toward both DNA and RNA complements (ΔT(m) = -3.5 °C/-3.5 °C for monomer X and ΔT(m) = -11.0 °C/-6.5 °C for monomer Y). CD measurements do...

Preparation and characterization of Pd{sub x}Ag{sub y}/C electrocatalysts for ethanol electrooxidation reaction in alkaline media

Energy Technology Data Exchange (ETDEWEB)

Li Guanglan [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Jiang Luhua [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Jiang Qian [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Wang Suli [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Sun Gongquan, E-mail: gqsun@dicp.ac.cn [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

2011-09-01

Highlights: {center_dot} The effects of Pd or PdAg particle size and PdAg alloy degrees on the EOR activity are investigated. {center_dot} The Pd lattice constant of the PdAg increases with increasing the Ag content. {center_dot} The EOR activity of the PdAg/C presents a 'volcano' plot with increasing the Pd lattice constant. {center_dot} The optimal Pd/Ag atomic ratio locates between 2/1 and 3/1. {center_dot} The EOR activity of the PdAg/C increases with increasing the PdAg particle size from 3.4 to 5.2 nm. - Abstract: Carbon-supported bimetallic PdAg catalysts with Pd/Ag atomic ratios varying from 4/1 to 1/2 were prepared by an impregnation-reduction method. The impregnated black mixture was treated in H{sub 2}/N{sub 2} atmosphere at a temperature varying from 180 to 500 deg. C. The obtained Pd{sub x}Ag{sub y}/C catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV) and chronoamperometry (CA). XRD results show that the lattice constant of Pd is dilated, suggesting the formation of PdAg alloy. The lattice constant of Pd for the Pd{sub x}Ag{sub y}/C-500 (reduced at 500 deg. C by H{sub 2}) increases linearly and the average metal particle size decreases slightly from 6.8 to 5.1 nm with increasing Ag fractions from 20% to 67% in the PdAg composition. For Pd{sub x}Ag{sub y}/C catalysts with a certain specific Pd/Ag atomic ratio, e.g., Pd{sub 2}Ag{sub 1}/C, the dilated lattice constant of Pd is independent of the reducing temperature, indicating the alloy degree for the Pd{sub 2}Ag{sub 1}/C-t catalysts is comparable. The average metal particle size for the Pd{sub 2}Ag{sub 1}/C-t catalysts increases from 3.4 to 5.2 nm with H{sub 2} reduction temperature increasing from 180 to 500 deg. C. The potentiodynamic measurements on ethanol electrooxidation reaction (EOR) show that the catalytic activities for the Pd{sub x}Ag{sub y}/C-t catalysts toward the EOR are improved by alloying Pd with Ag. At

Photoinduced formation of Ag nanoparticles on the surface of As2S3/Ag thin bilayer

International Nuclear Information System (INIS)

Binu, S; Khan, Pritam; Barik, A R; Sharma, Rituraj; Adarsh, K V; Golovchak, R; Jain, H

2014-01-01

In this article, we demonstrate the combined effect of photodoping and photoinduced-surface deposition in a bilayer of chalcogenide glass (ChG) and Ag as an alternative method to optically synthesize Ag nanoparticles (AgNP) on the surface of ChG. In our experiment, AgNP formation occurs through two distinct stages: In the first stage, Ag is transported through the As 2 S 3 layer as Ag + ions, and in the second stage Ag + ions are photo-deposited as AgNP. The ex situ x-ray photoelectron spectroscopy measurements and AFM observations show photoinduced Ag mass transport and the formation of AgNP. (paper)

Investigation of the resistive switching in Ag{sub x}AsS{sub 2} layer by conductive AFM

Energy Technology Data Exchange (ETDEWEB)

Zhang, Bo [Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska 573, Pardubice, 532 10 Czech Republic (Czech Republic); Kutalek, Petr [Joint Laboratory of Solid State Chemistry of Institute of Macromolecular Chemistry Academy of Sciences of Czech Republic, v.v.i., and University of Pardubice, University of Pardubice, Studentska 573, Pardubice, 532 10 (Czech Republic); Knotek, Petr [Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska 573, Pardubice, 532 10 Czech Republic (Czech Republic); Hromadko, Ludek; Macak, Jan M. [Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, Pardubice, 53002 (Czech Republic); Wagner, Tomas, E-mail: tomas.wagner@upce.cz [Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska 573, Pardubice, 532 10 Czech Republic (Czech Republic); Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, Pardubice, 53002 (Czech Republic)

2016-09-30

Highlights: • The resistive switching was studied from topological maps and spread current maps by conductive AFM. • Both surface particles and filaments were created under bias from conductive AFM. • The combination of topological map and spread current map proves the current did not flow through surface particles. • A model, consisting of interactions between charge carriers and Ag ions, were introduced to explain the experiment phenomena. - Abstract: In this paper, a study of resistive switching in Ag{sub x}AsS{sub 2} layer, based on a utilization of conductive atomic force microscope (AFM), is reported. As the result of biasing, two distinct regions were created on the surface (the conductive region and non-conductive region). Both were analysed from the spread current maps. The volume change, corresponding to the growth of Ag particles, was derived from the topological maps, recorded simultaneously with the current maps. Based on the results, a model explaining the mechanism of the Ag particle and Ag filament formation was proposed from the distribution of charge carriers and Ag ions.

Study of the pseudo-ternary Ag2SAs2S3HgI2 vitreous system

Science.gov (United States)

Boidin, R.; Le Coq, D.; Cuisset, A.; Hindle, F.; Brubach, J.-B.; Michel, K.; Bychkov, E.

2013-03-01

Chalcogenide alloys in the Ag2SAs2S3HgI2 pseudo-ternary system were synthesized and their vitreous nature was verified by X-ray diffraction. The glass transition and crystallization temperatures (Tg and Tc), the density (d), and the total electrical conductivity (σ) were measured for all samples of three series, A, B, and C corresponding to (Ag2S)50-x/2(As2S3)50-x/2(HgI2)x, (Ag2S)y(As2S3)80-y(HgI2)20 and (Ag2S)z(As2S3)50(HgI2)50-z, respectively. The maximum of Tg was approximately 160 °C for glasses with low HgI2 content whereas the maximum of density (5.75 g cm-3) was obtained for the sample in the B-series with the highest Ag2S concentration (z=60 mol%). This composition also possesses the highest conductivity at 298 K (σ298 K≈10-3 S cm-1). Unexpectedly the conductivity of the A-series samples was observed to decrease as a function of the Ag2S content. The far-infrared transmission in the 100-600 cm-1 window range (3.3-18.2 THz, 100-16.6 μm) was also given for a few glass compositions highlighting the strong influence of the HgI2 content.

Reducing strength prevailing at root surface of plants promotes reduction of Ag+ and generation of Ag(0/Ag2O nanoparticles exogenously in aqueous phase.

Directory of Open Access Journals (Sweden)

Peddisetty Pardha-Saradhi

Full Text Available Potential of root system of plants from wide range of families to effectively reduce membrane impermeable ferricyanide to ferrocyanide and blue coloured 2,6-dichlorophenol indophenol (DCPIP to colourless DCPIPH2 both under non-sterile and sterile conditions, revealed prevalence of immense reducing strength at root surface. As generation of silver nanoparticles (NPs from Ag+ involves reduction, present investigations were carried to evaluate if reducing strength prevailing at surface of root system can be exploited for reduction of Ag+ and exogenous generation of silver-NPs. Root system of intact plants of 16 species from 11 diverse families of angiosperms turned clear colorless AgNO3 solutions, turbid brown. Absorption spectra of these turbid brown solutions showed silver-NPs specific surface plasmon resonance peak. Transmission electron microscope coupled with energy dispersive X-ray confirmed the presence of distinct NPs in the range of 5-50 nm containing Ag. Selected area electron diffraction and powder X-ray diffraction patterns of the silver NPs showed Bragg reflections, characteristic of crystalline face-centered cubic structure of Ag(0 and cubic structure of Ag2O. Root system of intact plants raised under sterile conditions also generated Ag(0/Ag2O-NPs under strict sterile conditions in a manner similar to that recorded under non-sterile conditions. This revealed the inbuilt potential of root system to generate Ag(0/Ag2O-NPs independent of any microorganism. Roots of intact plants reduced triphenyltetrazolium to triphenylformazon and impermeable ferricyanide to ferrocyanide, suggesting involvement of plasma membrane bound dehydrogenases in reduction of Ag+ and formation of Ag(0/Ag2O-NPs. Root enzyme extract reduced triphenyltetrazolium to triphenylformazon and Ag+ to Ag(0 in presence of NADH, clearly establishing potential of dehydrogenases to reduce Ag+ to Ag(0, which generate Ag(0/Ag2O-NPs. Findings presented in this manuscript put

Microstructure of Co/X (X=Cu,Ag,Au) epitaxial thin films grown on Al2O3(0001) substrates

International Nuclear Information System (INIS)

Ohtake, Mitsuru; Akita, Yuta; Futamoto, Masaaki; Kirino, Fumiyoshi

2007-01-01

Epitaxial thin films of Co/X (X=Cu,Ag,Au) were prepared on Al 2 O 3 (0001) substrates at substrate temperatures of 100 and 300 degree sign C by UHV molecular beam epitaxy. A complicated microstructure was realized for the epitaxial thin films. In-situ reflection high-energy electron diffraction observation has shown that X atoms of the buffer layer segregated to the surface during Co layer deposition, and it yielded a unique epitaxial granular structure. The structure consists of small Co grains buried in the X buffer layer, where both the magnetic small Co grains and the nonmagnetic X layer are epitaxially grown on the single crystal substrate. The structure varied depending on the X element and the substrate temperature. The crystal structure of Co grains is influenced by the buffer layer material and determined to be hcp and fcc structures for the buffer layer materials of Au and Cu, respectively

Microstructure and adhesion strength of Sn-9Zn-xAg lead-free solders wetted on Cu substrate

International Nuclear Information System (INIS)

Chang, T.-C.; Chou, S.-M.; Hon, M.-H.; Wang, M.-C.

2006-01-01

The microstructure and adhesion strength of the Sn-9Zn-xAg lead-free solders wetted on Cu substrates have been investigated by differential scanning calorimetry, optical microscopy, scanning electron microscopy, energy dispersive spectrometry and pull-off testing. The liquidus temperatures of the Sn-9Zn-xAg solder alloys are 222.1, 226.7, 231.4 and 232.9 deg. C for x = 2.5, 3.5, 5.0 and 7.5 wt%, respectively. A flat interface can be obtained as wetted at 350 deg. C at a rate of 11.8 mm/s. The adhesion strength of the Sn-9Zn-xAg/Cu interfaces decreases from 23.09 ± 0.31 to 12.32 ± 1.40 MPa with increasing Ag content from 2.5 to 7.5 wt% at 400 deg. C. After heat treatment at 150 deg. C, the adhesion strength of the Sn-9Zn-xAg/Cu interface decreases with increasing aging time

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

International Nuclear Information System (INIS)

Tenbrink, J.; Krauth, H.

1994-01-01

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

Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: An Expanding Shell Model of Monomer Distribution

International Nuclear Information System (INIS)

Richter, Andrew; Dergunov, Sergey; Ganus, Bill; Thomas, Zachary; Pingali, Sai Venkatesh; Urban, Volker S.; Liu, Yun; Porcar, Lionel; Pinkhassik, Eugene

2011-01-01

Hydrophobic monomers partially phase separate from saturated lipids when loaded into lipid bilayers in amounts exceeding a 1:1 monomer/lipid molar ratio. This conclusion is based on the agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in an increase in bilayer thickness and a slight increase in the diameter of liposomes. A homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to an increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS), was approximately half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was intermediate between values predicted for a homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at a 1.2 monomer/lipid ratio approximately half of the monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for the directed covalent assembly of organic nanomaterials. In particular, the partial phase separation of monomers from lipids corroborates the successful creation of nanothin polymer materials with uniform imprinted nanopores. Pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films.

Effect of Ag on the peritectic decomposition of Bi2Sr2CaCu2Ox

International Nuclear Information System (INIS)

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

1995-01-01

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

Silver carbonate and stability in colloidal silver: A by-product of the electric spark discharge method

International Nuclear Information System (INIS)

Tseng, Kuo-Hsiung; Liao, Chih-Yu; Tien, Der-Chi

2010-01-01

Many methods of producing colloidal silver (CS) include the introduction of surfactants to improve the suspensivity of the silver particles. The electric spark discharge method (ESDM) which involves pulses of direct current being passed through a silver electrode submerged in deionized water has been shown to successfully produce colloidal silver in a stable suspension without the use of chemical additives. A by-product of the electric spark discharge method, a silver ion compound (AgX), is shown to be the cause of the high suspensivity of the silver nanoparticles (AgNPs). The silver ion compound has been identified as Ag 2 CO 3 using X-ray diffraction, and it has been determined that the Ag 2 CO 3 is formed during the electric spark discharge process through a reaction with atmospheric CO 2 . It has been shown that an Ag 2 CO 3 concentration of 10 ppm or more is sufficient to generate a stable suspension of silver particles. Because of the occurrence of Ag 2 CO 3 , the electric spark discharge method can produce stable colloidal silver.

Preparation of Ag deposited TiO2 (Ag/TiO2) composites and investigation on visible-light photocatalytic degradation activity in magnetic field

Science.gov (United States)

Zhang, L.; Ma, C. H.; Wang, J.; Li, S. G.; Li, Y.

2014-12-01

In this study, Ag deposited TiO2 (Ag/TiO2) composites were prepared by three different methods (Ultraviolet Irradiation Deposition (UID), Vitamin C Reduction (VCR) and Sodium Borohydride Reduction (SBR)) for the visible-light photocatalytic degradation of organic dyes in magnetic field. And then the prepared Ag deposited TiO2 (Ag/TiO2) composites were characterized physically by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The visible-light photocatalytic activities of these three kinds of Ag deposited TiO2 (Ag/TiO2) composites were examined and compared through the degradation of several organic dyes under visible-light irradiation in magnetic field. In addition, some influence factors such as visible-light irradiation time, organic dye concentration, revolution speed, magnetic field intensity and organic dye kind on the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composite were reviewed. The research results showed that the presence of magnetic field significantly enhanced the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composites and then contributed to the degradation of organic dyes.

Phase relations in the M2MoO4 - Ag2MoO4 - Hf(MoO4)2 (M=Li, Na) systems

International Nuclear Information System (INIS)

Bazarova, Zh.G.; Bazarov, B.G.; Balsanova, L.V.

2002-01-01

The M 2 MoO 4 - Ag 2 MoO 4 - Hf(MoO 4 ) 2 (M=Li, Na) systems were studied by X-ray diffraction and differential thermal analyses in the subsolidus area (450 - 500 Deg C) for the first time. The formation of the binary compound with the variable composition Li 4-x Hf 1+0.2x (MoO 4 ) 4 (0 ≤ x ≤ 0.6) in the Li 2 MoO 4 - Hf(MoO 4 ) 2 system and the ternary molybdates Li 4 Ag 2 Hf(MoO 4 ) 5 (S 1 ) and Na 2 Ag 2 Hf(MoO 4 ) 4 (S 2 ) was established and the thermal characteristics of the prepared compounds were examined. The new binary molybdate Ag 2 Hf(MoO 4 ) 3 was prepared by the reaction between Ag 2 MoO 4 and Hf(MoO 4 ) 2 [ru

Measurement of excitation functions and isomeric ratios of the reactions 103Rh(3He, xn) sup(106-x)Ag where x=2, 3 and 4

International Nuclear Information System (INIS)

Borges, A.M.

1981-01-01

The excitation functions and isomer ratios for the reactions 103 Rh( 3 He, xn) sup(106-x)Ag, where x=2, 3 and 4, were measured with projectile Lab energy varying from 23 to 35 MeV. Since the half-life of sup(103m)Ag is equal to 5.7 s. the use of a recoil nucleous gas jet transport system became necessary. The values measured for the cross-sections were compared to those yielded by the ALICE code. The experimental isomer ratios are smaller than those calculated using the residual nucleus spin distribution obtained with the ALICE code. By-pass fractions as expected in this mass region were also obtained. (Author) [pt

Phase formation in the Ag2O - MgO - MoO3 system and the crystal structure of new double molybdate Ag2Mg2(MoO4)3

International Nuclear Information System (INIS)

Tsyrenova, G.D.; Khajkina, E.G.; Khobrakova, Eh.T.; Solodovnikov, S.F.

2001-01-01

The phase correlations in subsolidus area of the Ag 2 O - MgO - MoO 3 system were studied, the Ag 2 MoO 4 - MgMoO 4 polythermal cross-section was investigated and its T-x diagram was constructed. X-ray diffraction and thermal analytic researches were conducted. The formation of the new double Ag 2 Mg 2 (MoO 4 ) 3 molybdates relating to the structural group Na 2 Mg 5 (MoO 4 ) 6 was established, and its structure (a=6.978(1), b=8.715(2), c=10.294(2) A, α=107.56(3) Deg, β=105.11(3) Deg, γ=103.68(3) Deg, Z=2, sp. gr. P 1-bar, R=0.038) was determined. The mixed carcass from the twin MgO 6 -octahedrons and MoO 4 -tetrahedrons, in which blankness the Ag atoms are arranged, stand out in the structure.The character of disordering in the part of Ag + is analogous to previously found one in the Ag 2 Zn 2 (MoO 4 ) 3 structure. The possible limits in the fields of homogeneity of silver-magnesium molybdate and its analogs, as well as the differences their structure from the structure of isotopic sodium-containing phases, are discussed [ru

Ionic-to-Electronic Conductivity Crossover in CdTe-AgI-As2Te3 Glasses: An 110mAg Tracer Diffusion Study.

Science.gov (United States)

Kassem, M; Alekseev, I; Bokova, M; Le Coq, D; Bychkov, E

2018-04-12

Conductivity isotherms of (CdTe) x (AgI) 0.5- x/2 (As 2 Te 3 ) 0.5- x/2 glasses (0.0 ≤ x ≤ 0.15) reveal a nonmonotonic behavior with increasing CdTe content reminiscent of mixed cation effect in oxide and chalcogenide glasses. Nevertheless, the apparent similarity appears to be partly incorrect. Using 110m Ag tracer diffusion measurements, we show that semiconducting CdTe additions produce a dual effect: (i) decreasing the Ag + ion transport by a factor of ≈200 with a simultaneous increase of the diffusion activation energy and (ii) increasing the electronic conductivity by 1.5 orders of magnitude. Consequently, the conductivity minimum at x = 0.05 reflects an ionic-to-electronic transport crossover; the silver-ion transport number decreases by 3 orders of magnitude with increasing x.

Synthesis and Characterization of Oligodeoxyribonucleotides Modified with 2'-Amino-α-l-LNA Adenine Monomers

DEFF Research Database (Denmark)

Andersen, Nicolai K; Anderson, Brooke A; Wengel, Jesper

2013-01-01

The development of conformationally restricted nucleotide building blocks continues to attract considerable interest because of their successful use within antisense, antigene, and other gene-targeting strategies. Locked nucleic acid (LNA) and its diastereomer α-l-LNA are two interesting examples...... (ONs) modified with 2'-amino-α-l-LNA adenine monomers W-Z. The synthesis of the target phosphoramidites 1-4 is initiated from pentafuranose 5, which upon Vorbrüggen glycosylation, O2'-deacylation, O2'-activation and C2'-azide introduction yields nucleoside 8. A one-pot tandem Staudinger....... ONs modified with pyrene-functionalized 2'-amino-α-l-LNA adenine monomers X-Z display greatly increased affinity toward DNA targets (ΔTm/modification up to +14 °C). Results from absorption and fluorescence spectroscopy suggest that the duplex stabilization is a result of pyrene intercalation...

Facile Synthesis of Magnetic Photocatalyst Ag/BiVO4/Mn1−xZnxFe2O4 and Its Highly Visible-Light-Driven Photocatalytic Activity

Directory of Open Access Journals (Sweden)

Taiping Xie

2018-05-01

Full Text Available Ag/BiVO4/Mn1−xZnxFe2O4 was synthesized with a dip-calcination in situ synthesis method. This work was hoped to provide a simple method to synthesis three-phase composite. The phase structure, optical properties and magnetic feature were confirmed by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectrometer (XPS, transmission electron microscopy (TEM, ultraviolet-visible diffuse reflectance spectrophotometer (UV-vis DRS, and vibrating sample magnetometer (VSM. The photocatalytic activity was investigated by Rhodamine B (RhB photo-degradation under visible light irradiation. The photo-degradation rate of RhB was 94.0~96.0% after only 60 min photocatalytic reaction under visible light irradiation, revealing that it had an excellent visible-light-induced photocatalytic activity. In the fifth recycle, the degradation rate of Ag/BiVO4/Mn1−xZnxFe2O4 still reached to 94.0%. Free radical tunnel experiments confirmed the dominant role of •O2− in the photocatalytic process for Ag/BiVO4/Mn1−xZnxFe2O4. Most importantly, the mechanism that multifunction Ag could enhance photocatalytic activity was explained in detail.

Recognition of double-stranded DNA using energetically activated duplexes with interstrand zippers of 1-, 2-or 4-pyrenyl-functionalized O2 '-alkylated RNA monomers

DEFF Research Database (Denmark)

Karmakar, Saswata; Madsen, Andreas Stahl; Guenther, Dale C.

2014-01-01

'-alkylated uridine monomers X-Z by means of thermal denaturation experiments, optical spectroscopy, force-field simulations and recognition experiments using DNA hairpins as model targets. We demonstrate that Invaders with +1 interstrand zippers of X or Y monomers efficiently recognize mixed-sequence DNA...

α-K2AgF4: Ferromagnetism induced by the weak superexchange of different eg orbitals from the nearest neighbor Ag ions

Science.gov (United States)

Zhang, Xiaoli; Zhang, Guoren; Jia, Ting; Zeng, Zhi; Lin, H. Q.

2016-05-01

We study the abnormal ferromagnetism in α-K2AgF4, which is very similar to high-TC parent material La2CuO4 in structure. We find out that the electron correlation is very important in determining the insulating property of α-K2AgF4. The Ag(II) 4d9 in the octahedron crystal field has the t2 g 6 eg 3 electron occupation with eg x2-y2 orbital fully occupied and 3z2-r2 orbital partially occupied. The two eg orbitals are very extended indicating both of them are active in superexchange. Using the Hubbard model combined with Nth-order muffin-tin orbital (NMTO) downfolding technique, it is concluded that the exchange interaction between eg 3z2-r2 and x2-y2 from the first nearest neighbor Ag ions leads to the anomalous ferromagnetism in α-K2AgF4.

α-K2AgF4: Ferromagnetism induced by the weak superexchange of different eg orbitals from the nearest neighbor Ag ions

Directory of Open Access Journals (Sweden)

Xiaoli Zhang

2016-05-01

Full Text Available We study the abnormal ferromagnetism in α-K2AgF4, which is very similar to high-TC parent material La2CuO4 in structure. We find out that the electron correlation is very important in determining the insulating property of α-K2AgF4. The Ag(II 4d9 in the octahedron crystal field has the t 2 g 6 e g 3 electron occupation with eg x2-y2 orbital fully occupied and 3z2-r2 orbital partially occupied. The two eg orbitals are very extended indicating both of them are active in superexchange. Using the Hubbard model combined with Nth-order muffin-tin orbital (NMTO downfolding technique, it is concluded that the exchange interaction between eg 3z2-r2 and x2-y2 from the first nearest neighbor Ag ions leads to the anomalous ferromagnetism in α-K2AgF4.

Measurement of the energetics of metal film growth on a semiconductor: Ag/ Si(100)-2x1

DEFF Research Database (Denmark)

Starr, D.E.; Ranney, J.T.; Larsen, Jane Hvolbæk

2001-01-01

The first direct calorimetric measurements of the energetics of metal film growth on a semiconductor surface are presented. The heat of adsorption of Ag on Si(100)-(2 x 1) at 300 K decreases from similar to 347 to 246 kJ/mol with coverage in the first monolayer (ML) due to overlap of substrate...... strain from nearby Ag islands. It then rises quickly toward the bulk sublimation enthalpy (285 kJ/mol) as 3D particles grow. A wetting layer grows to 1.0 ML, but is metastable above similar to0.55 ML and dewets when kinetics permit. This may be common when adsorbate islands induce a large strain...

New two-step synthesis of N-(2-ethylhexyl)-2,7-diiodocarbazole as a monomer for conjugated polymers

Czech Academy of Sciences Publication Activity Database

Výprachtický, Drahomír; Kmínek, Ivan; Pokorná, Veronika; Kaňková, Dana; Cimrová, Věra

2013-01-01

Roč. 16, č. 1 (2013), s. 31-37 ISSN 1385-772X R&D Projects: GA MŠk(CZ) 1M06031; GA ČR GAP106/12/0827 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : monomer synthesis * carbazole * ring closure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.210, year: 2013

Structural and electric properties of AgGaTe{sub 2} layers prepared using mixed source of Ag{sub 2}Te and Ga{sub 2}Te{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Uruno, Aya [Department of Electrical Engineering and Bioscience, Waseda University, Tokyo (Japan); Kobayashi, Masakazu [Department of Electrical Engineering and Bioscience, Waseda University, Tokyo (Japan); Kagami Memorial Research Institute for Materials Science and Technology, Waseda University, Tokyo (Japan)

2017-01-15

AgGaTe{sub 2} layers were prepared on Si substrates by a closed space sublimation method using a mixed powder source of Ag{sub 2}Te and Ga{sub 2}Te{sub 3}. Ag{sub 2}Te buffer layer deposition was introduced to eliminate melt-back etching. The effect of the molar ratio of Ag{sub 2}Te and Ga{sub 2}Te{sub 3} in the mixed source on the crystallinity of the AgGaTe{sub 2} layer was investigated. The composition and the phase of the layer was found to change depending on the molar ratio in the deposits, which could be controlled by the source molar ratio along with the Ag{sub 2}Te buffer layer thickness. It was confirmed that (112) oriented uniform AgGaTe{sub 2} layer with an abrupt interface between AgGaTe{sub 2} and Si was formed after those parameters were tuned. The obtained layer exhibited the acceptor concentration of around 2.5 x 10{sup 16} cm{sup -3}. A solar cell was fabricated using the p-AgGaTe{sub 2}/n-Si heterojunction, and exhibited a conversion efficiency of 1.15%. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Improved current transport properties of post annealed Y1Ba2Cu3O7-x thin films using Ag doping

DEFF Research Database (Denmark)

Clausen, Thomas; Skov, Johannes; Jacobsen, Claus Schelde

1996-01-01

The influence of Ag doping on the transport properties of Y1Ba2Cu3O7–x thin films prepared by Y, BaF2, and Cu co-evaporation and optimized ex situ post annealing has been investigated. Both undoped and Ag doped films have values of Tc above 90 K, but Jc (77 K) is highly dependent on the nominal...... thickness (tnom) of the as-deposited film. For undoped films with tnom>106 A/cm2) decreases monotonically with increasing film thickness. Above 300 nm Jc (77 K) decreases rapidly to values below 5×105 A/cm2. Ag doped films with tnom>=200 nm have higher Jc (77 K) values than those of undoped films. Ag doped...... films have a maximum in Jc (77 K) around 250 nm. As for the undoped films, there is a large decrease in Jc (77 K) for Ag doped films with tnom>=300 nm. It was found that the higher values of Jc (77 K) for the Ag doped films were due to a better epitaxial growth of the YBCO compound. The low values of Jc...

Silver Nanocube and Nanobar Growth via Anisotropic Monomer Addition and Particle Attachment Processes

Energy Technology Data Exchange (ETDEWEB)

Xiao, Dongdong [Physical; Wu, Zhigang [School; Song, Miao [Physical; Chun, Jaehun [Physical; Schenter, Gregory K. [Physical; Li, Dongsheng [Physical

2018-01-11

Understanding the growth mechanism of noble metal nanocrystals during solution synthesis is of significant importance for shape and property control. However, much remains unknown about the growth pathways of metal nanoparticles due to lack of direct observation. Using an in-situ transmission electron microscopy technique, we directly observed Ag nanocube and nanobar growth in aqueous solution through both classical monomer-by-monomer addition and non-classical particle attachment processes. During the particle attachment process, Ag nanocubes and nanobars formed via both oriented and non-oriented attachment. Our calculations, along with dynamics of the observed attachment, showed that van der Waals force overcame hydrodynamic and friction forces and drove the particles toward each other. During classical growth, an anisotropic growth was also revealed, and the resulting unsymmetrical shape constituted an intermediate state for Ag nanocube growth. We hypothesized that the temporary symmetry breaking resulted from different growth rates on {001} surfaces due to a local surface concentration variation caused by the imbalance between the consumption of Ag+ near the surface and the diffusion of Ag+ from bulk to surface.

Neutral dipole-dipole dimers: A new field in science

Science.gov (United States)

Kosower, Edward M.; Borz, Galina

2018-03-01

Dimer formation with dipole neutralization produces species such as low polarity water (LPW) compatible with hydrophobic surfaces (Phys. Chem. Chem. Phys. 2015, 17, 24895-24900) Dimerization and dipole neutralization occurs for N-methylacetamide on polyethylene, a behavior drastically different from its contortions in acetonitrile on AgBr:AgCl planar crystals (AgX) (ChemPhysChem 2014, 15, 3598-3607). The weak infrared absorption of the amide dimer on polyethylene is shown experimentally. Dimerization of palmitic acid is shown along with some of the many ramifications for intracellular systems. Polyoligomers of water are present on polyethylene surfaces. Some high resolution spectra of three of the polyoligomers of water are shown along with a mechanistic scheme for polyoligomer formation and dissolution. The structures of some of the oligomers are known from spectroscopic studies of water on AgX. The scope of the article begins with PE, generally accepted as hydrophobic. The IR of PE revealed not only that water was present but that it appeared in two forms, oligomers (O) and polyoligomers (PO). How did we recognize what they were? These species had been observed as especially strong "marker" peaks in the spectra1 of water placed on planar AgX, a platform developed by Katzir and his coworkers [6]. But there was a problem: the proximity to PE of oligomers with substantial (calculated) dipole moments and thus polarity, including cyclic hexamers of water (chair and boat forms), the cyclic pentamer, the books I and II, and the cyclic trimer [7a]. Another link was needed, a role perfectly fit by the already cited low polarity water (LPW). The choice was experimentally supported by the detection of low intensity absorption in the bending region.Some important generalities flow from these results. What other dimers might be present in the biological or chemical world? Palmitic acid dimer (PAD) would be a candidate for decreasing the polarity of the acid (PA). Another

Synthesis, structural, electronic and linear electro-optical features of new quaternary Ag2Ga2SiS6 compound

Science.gov (United States)

Piasecki, M.; Myronchuk, G. L.; Parasyuk, O. V.; Khyzhun, O. Y.; Fedorchuk, A. O.; Pavlyuk, V. V.; Kozer, V. R.; Sachanyuk, V. P.; El-Naggar, A. M.; Albassam, A. A.; Jedryka, J.; Kityk, I. V.

2017-02-01

For the first time phase equilibria and phase diagram of the AgGaS2-SiS2 system were successfully explored by differential thermal and X-ray phase analysis methods. Crystal structure of low-temperature (LT) modification of Ag2Ga2SiS6 (LT- Ag2Ga2SiS6) was studied by X-ray powder method and it belongs to tetragonal space group I-42d, with unit cell parameters a=5.7164(4) Å, c=9.8023(7) Å, V=320.32(7) Å3. Additional details regarding the crystal structure exploration are available at the web page Fachinformationszentrum Karlsruhe. X-ray photoelectron core-level and valence-band spectra were measured for pristine LT- Ag2Ga2SiS6 crystal surface. In addition, the X-ray photoelectron valence-band spectrum of LT-Ag2Ga2SiS6 was matched on a common energy scale with the X-ray emission S Kβ1,3 and Ga Kβ2 bands, which give information on the energy distribution of the S 3p and Ga 4p states, respectively. The presented X-ray spectroscopy results indicate that the valence S p and Ga p atomic states contribute mainly to the upper and central parts of the valence band of LT-Ag2Ga2SiS6, respectively, with a less significant contribution also to other valence-band regions. Band gap energy was estimated by measuring the quantum energy in the spectral range of the fundamental absorption. We have found that energy gap Eg is equal to 2.35 eV at 300 K. LT-Ag2Ga2SiS6 is a photosensitive material and reveals two spectral maxima on the curve of spectral photoconductivity spectra at λmax1 =590 nm and λmax2 =860 nm. Additionally, linear electro-optical effect of LT-Ag2Ga2SiS6 for the wavelengths of a cw He-Ne laser at 1150 nm was explored.

Tunneling-recombination luminescence between Ag0 and Ag2+ in KCl:AgCl

International Nuclear Information System (INIS)

Delbecq, C.J.; Dexter, D.L.; Yuster, P.H.

1978-01-01

Appropriate treatment of a KCl:AgCl crystal results in the trapping of electrons as silver atoms, Ag 0 , and positive holes as AgCl 4 2- , Ag 2+ , centers. Optical excitation of Ag 0 in such a crystal at T 0 and Ag 2+ pairs, similar to the Ag 0 -Cl 2 - tunneling-recombination studies we previously reported. We have shown that Ag 2+ centers are involved in the emission process by preferentially orienting the anisotropic Ag 2+ at 6 K by excitation with polarized light and observing that the afterglow is polarized. Upon warming to 50 K, where the preferentially oriented Ag 2+ can change orientation, a strong reversal in the degree of polarization occurs which finally decays to zero. The characteristics of this luminescence can be understood if we assume: (i) a tunneling-recombination mechanism in which the orientation of the electric vector of the emitted radiation depends on the position of the Ag 0 relative to the Ag 2+ and (ii) the tunneling is anisotropic and depends on the location of the Ag 0 relative to the anisotropic Ag 2+ . The latter assumption is based on the tetragonal (d-like) symmetry of the Ag 2+ complex. Good quantitative agreement between theory and experiment has been obtained on the decay kinetics, the degree of polarization, and the polarization reversal

Structural features of AgCaCdMg2(PO4)3 and AgCd2Mg2(PO4)3, two new compounds with the alluaudite-type structure, and their catalytic activity in butan-2-ol conversion

International Nuclear Information System (INIS)

Kacimi, Mohammed; Ziyad, Mahfoud; Hatert, Frederic

2005-01-01

AgCaCdMg 2 (PO 4 ) 3 and AgCd 2 Mg 2 (PO 4 ) 3 , two new compounds with the alluaudite-type structure, were synthesized by a solid state reaction in air at 750 deg. C. The X-ray powder diffraction pattern of AgCaCdMg 2 (PO 4 ) 3 indicates the presence of small amounts of (Ca, Mg) 3 (PO 4 ) 2 with the whitlockite structure, as impurity, whereas AgCd 2 Mg 2 (PO 4 ) 3 is constituted by pure alluaudite. The Rietveld refinements of the X-ray powder diffraction patterns indicate an ordered cationic distribution for AgCd 2 Mg 2 (PO 4 ) 3 , with Ag on A(2)', Cd on A(1) and M(1), and Mg on M(2), whereas a disordered distribution of Cd and Ca between the A(1) and M(1) sites is observed for AgCaCdMg 2 (PO 4 ) 3 . The catalytic properties of these compounds has been measured in reaction of butan-2-ol dehydrogenation. In the absence of oxygen, both samples exhibit poor dehydrogenation activity. All samples displayed no dehydration activity. Introduction of oxygen into the feed changed totally the catalytic behavior of the catalysts. The production of methyl ethyl ketone increases with time on stream and the reaction temperature. AgCaCdMg 2 (PO 4 ) 3 is more efficient than AgCd 2 Mg 2 (PO 4 ) 3

Plasma-induced formation of flower-like Ag2O nanostructures

International Nuclear Information System (INIS)

Yang, Zen-Hung; Ho, Chun-Hsien; Lee, Szetsen

2015-01-01

Graphical abstract: Flower-like Ag 2 O nanostructures. - Highlights: • Flower-like Ag 2 O nanostructures were synthesized from Ag colloids using plasma. • XPS was used to monitor plasma treatment effect on Ag colloids. • SERS of methyl orange was used to monitor the plasma oxidation–reduction processes. • Photocatalytic degradation of methylene blue was performed using Ag 2 O. • Ag 2 O is a more efficient visible light photocatalyst than Ag colloids. - Abstract: Plasma treatment effect on Ag colloids was investigated using X-ray photoelectron spectroscopy (XPS) and surface-enhanced Raman scattering (SERS) techniques. XPS showed that O 2 plasma was critical in removing organic residues in Ag colloids synthesized using citric acid as a reducing agent. With O 2 plasma treatment, Ag colloids were also oxidized to form flower-like Ag 2 O nanostructures. The formation mechanism is proposed. The SERS spectral intensity of methyl orange (MO) adsorbed on Ag surface became deteriorated with O 2 plasma treatment. Followed by H 2 plasma treatment, the SERS intensity of MO on Ag regained, which indicated that Ag 2 O has been reduced to Ag. Nonetheless, the reduction by H 2 plasma could not bring Ag back to the original as-synthesized nanoparticle morphology. The flower-like nanostructure morphology still remained. The photocatalytic degradation reactions of methylene blue (MB) aqueous solutions were carried out using Ag colloids and Ag 2 O nanostructures. The results show that Ag 2 O is more efficient than Ag colloids and many other metal oxides for the photocatalytic degradation of MB in solution when utilizing visible light

Glass formation in AgI:Ag2O:V2O5 and AgI:Ag2O:(V2O5+B2O3) systems

International Nuclear Information System (INIS)

Kaushik, R.; Hariharan, K.

1988-01-01

Transport properties of glasses in the system AgI:Ag 2 O: V 2 O 5 and AgI:Ag 2 O: (V 2 O 5 +B 2 O 3 ) have ben investigated. It was found that, at high AgI concentrations, the addition of another glass former (B 2 O 3 ) did not improve the conduction characteristics of the pure vanadate glasses, the best conducting composition of which had ambient temperature, ionic conductivity comparable to that of conventional liquid electrolytes. The highest conducting composition was used as an electrolyte in the study of silver solid state cells. The discharge characteristics of different cells fabricated with the glassy electrolyte, have been compared with those having the best conducting polycrystalline ompositions as electrolytes. 11 refs.; 4 figs.; 1 table

Microstructure analyses and thermoelectric properties of Ag1−xPb18Sb1+yTe20

International Nuclear Information System (INIS)

Perlt, S.; Höche, Th.; Dadda, J.; Müller, E.; Bauer Pereira, P.; Hermann, R.; Sarahan, M.; Pippel, E.; Brydson, R.

2012-01-01

This study reports microstructural investigations of long-term annealed Ag 1−x Pb m Sb 1+y Te 2+m (m=18, x=y=0, hereinafter referred to as AgPb 18 SbTe 20 ) (Lead–Antimony–Silver–Tellurium, LAST-18) as well as of Ag 1−x Pb 18 Sb 1+y Te 20 , i.e. Ag-deficient and Sb-excess LAST-18 (x≠0,y≠0), respectively. Two different length scales are explored. The micrometer scale was evaluated by SEM to analyze the volume fraction and the number of secondary phases as well as the impact of processing parameters on the homogeneity of bulk samples. For AgPb 18 SbTe 20 , site-specific FIB liftout of TEM lamellae from thermoelectrically characterized samples was accomplished to investigate the structure on the nanometer scale. High-resolution TEM and energy-filtered TEM were performed to reveal shape and size distribution of nanoprecipitates, respectively. A hypothesis concerning the structure–property relationship is set out within the frame of a gradient annealing experiment. This study is completed by results dealing with inhomogeneities on the micrometer scale of Ag 1−x Pb 18 Sb 1+y Te 20 and its electronic properties. Highlights: ► SEM and TEM microstructure investigation of long-term annealed AgPb 18 SbTe 20 . ► SEM and thermoelectric studies on Ag 1−x Pb 18 Sb 1+y Te 20 . ► Discussion concerning structure–property relationship in long-term annealed AgPb 18 SbTe 20 . ► Correlation between Ag 1−x Pb 18 Sb 1+y Te 20 microscale structure and electronic properties.

Influence of Cu substitution on the structural ordering, photocatalytic activity and photoluminescence emission of Ag3-2xCuxPO4 powders

Science.gov (United States)

Pereira, Wyllamanney da S.; Sczancoski, Júlio C.; Calderon, Yormary N. C.; Mastelaro, Valmor R.; Botelho, Gleice; Machado, Thales R.; Leite, Edson R.; Longo, Elson

2018-05-01

Materials presenting high photocatalytic performance and interesting photoluminescence emissions are promising candidates for photodegradation of organic pollutants discharged into natural waters as well as for development of new electro-optical devices, respectively. In this study, Ag3-2xCuxPO4 (x = 0.00, 0.01, 0.02, 0.04 and 0.08) powders were synthesized by the precipitation method. The long- and short-range structural ordering was affected when the copper (Cu) content was increased in the lattice, as identified by X-ray diffraction patterns, Fourier transform infrared spectroscopy and Raman spectroscopy, respectively. The field emission scanning electron microscope and transmission electron microscope revealed a particle system composed of irregular spherical-like microcrystals. The presence of Cu as well as its real amount in the samples were confirmed by means of X-ray photoelectron spectroscopy and inductively coupled plasma-atomic emission spectrometry, respectively. On increasing Cu level, a slight variation was noted on the photocatalytic activity of Ag3-2xCuxPO4 powders for degradation of rhodamine B under visible light irradiation. A photodegradation mechanism was proposed in details. The photoluminescence emissions were explained by electronic transitions involving intermediary energy levels in the band gap. The origin these energy levels was related to defects caused by the substitution of Ag by Cu in the crystalline structure.

Effects of low-level Ag doping on Bi2Sr2CaCu2O8+x

International Nuclear Information System (INIS)

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

1995-07-01

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

Silver(I) complexes of the weakly coordinating solvents SO(2) and CH(2)Cl(2): crystal structures, bonding, and energetics of [Ag(OSO)][Al{OC(CF(3))(3)}(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(CH(2)Cl(2))(2)][SbF(6)].

Science.gov (United States)

Decken, Andreas; Knapp, Carsten; Nikiforov, Grigori B; Passmore, Jack; Rautiainen, J Mikko; Wang, Xinping; Zeng, Xiaoqing

2009-06-22

Pushing the limits of coordination chemistry: The most weakly coordinated silver complexes of the very weakly coordinating solvents dichloromethane and liquid sulfur dioxide were prepared. Special techniques at low temperatures and the use of weakly coordinating anions allowed structural characterization of [Ag(OSO)][Al{OC(CF(3))(3)}(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(Cl(2)CH(2))(2)][SbF(6)] (see figure). An investigation of the bonding shows that these complexes are mainly stabilized by electrostatic monopole-dipole interactions.The synthetically useful solvent-free silver(I) salt Ag[Al(pftb)(4)] (pftb=--OC(CF(3))(3)) was prepared by metathesis reaction of Li[Al(pftb)(4)] with Ag[SbF(6)] in liquid SO(2). The solvated complexes [Ag(OSO)][Al(pftb)(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(CH(2)Cl(2))(2)][SbF(6)] were prepared and isolated by special techniques at low temperatures and structurally characterized by single-crystal X-ray diffraction. The SO(2) complexes provide the first examples of coordination of the very weak Lewis base SO(2) to silver(I). The SO(2) molecule in [Ag(OSO)][Al(pftb)(4)] is eta(1)-O coordinated to Ag(+), while the SO(2) ligands in [Ag(OSO)(2/2)][SbF(6)] bridge two Ag(+) ions in an eta(2)-O,O' (trans,trans) manner. [Ag(CH(2)Cl(2))(2)][SbF(6)] contains [Ag(CH(2)Cl(2))(2)](+) ions linked through [SbF(6)](-) ions to give a polymeric structure. The solid-state silver(I) ion affinities (SIA) of SO(2) and CH(2)Cl(2), based on bond lengths and corresponding valence units in the corresponding complexes and tensimetric titrations of Ag[Al(pftb)(4)] and Ag[SbF(6)] with SO(2) vapor, show that SO(2) is a weaker ligand to Ag(+) than the commonly used weakly coordinating solvent CH(2)Cl(2) and indicated that binding strength of SO(2) to silver(I) in the silver(I) salts increases with increasing size of the corresponding counteranion ([Al(pftb)(4)](-)>[SbF(6)](-)). The experimental findings are in good agreement with theoretical gas-phase ligand

Optical spectra and band structure of Ag(x)Ga(x)Ge(1-x)Se2 (x = 0.333, 0.250, 0.200, 0.167) single crystals: experiment and theory.

Science.gov (United States)

Reshak, A H; Parasyuk, O V; Fedorchuk, A O; Kamarudin, H; Auluck, S; Chyský, J

2013-12-05

Theoretical and experimental studies of the Ag(x)Ga(x)Ge(1-x)Se2 (x = 0.333, 0.250, 0.200, 0.167) single crystals are performed. These crystals possess a lot of intrinsic defects which are responsible for their optoelectronic features. The theoretical investigations were performed by means of DFT calculations using different exchange-correlation potentials. The experimental studies were carried out using the modulated VUV ellipsometry for dielectric constants and birefringence studies. The comparison of the structure obtained from X-ray with the theoretically optimized structure is presented. The crucial role of the intrinsic defect states is manifested in the choice of the exchange correlation potential used. The data may be applicable for a large number of the ternary chalcogenides which are sensitive to the presence of the local disordered states near the band edges.

Antibacterial, kinetics and bacteriolytic properties of silver(I) pyridinedicarboxylate compounds

Energy Technology Data Exchange (ETDEWEB)

Azócar, M. Ignacio, E-mail: manuel.azocar@usach.cl [Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernardo O' Higgins 3363, Santiago (Chile); Gómez, Grace; Velásquez, Carla; Abarca, Romina [Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernardo O' Higgins 3363, Santiago (Chile); Kogan, Marcelo J. [Departamento de Quimica Farmacologica y Toxicologica, Facultad de Ciencias Quimicas y Farmaceuticas, Universidad de Chile. Advanced Center for Chronic Diseases (ACCDiS) (Chile); Páez, Maritza [Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernardo O' Higgins 3363, Santiago (Chile)

2014-04-01

Antibacterial properties of silver(I)-pyridinedicarboxylate compounds (with Pyridine-2,3-dicarboxylic(Lutidinic acid), pyridine-2,4-dicarboxylic (Quinolinic acid) and pyridine-2,5-dicarboxylic (Isocinchomeronic acid)) were studied against Escherichia coli, Listeria monocytogenes (ISP-65-08), Salmonella typhi and Staphylococcus aureus (ATCC 25923) using kinetics of grown inhibition, viability assays, minimum inhibitory concentration and optical microscopy. The 3 silver compounds were tested toward UV-radiation in order to characterize their light insensitivity for potential medical devices: UV-radiation curable polymers. Photophysical measurements show remarkable differences toward UV-radiation, which were explained based on their polymeric structures with multiple nature bonds between pyridinedicarboxylic ligands and Ag(I) centers. We found a bacteriolytic effect and differences in the antibacterial efficiency depending on the structure of the complexes and the nature of Ag-X (X = oxygen and nitrogen) bonds: AgQuinol > AgLutidin > AgIsocinchom. - Highlights: • Antibacterial efficiency of silver(I) complexes • Improving antimicrobial properties of silver(I) complexes • Insensitivity to air and UV light for medical devices • Broad-spectrum antibiotic ointment • Bacteriolytic mechanism of silver compounds.

Evaluating x-ray detectors for radiographic applications: A comparison of nSCdS:Ag with Gd sub 2 O sub 2 S:Tb and Y sub 2 O sub 2 S:Tb screens

CERN Document Server

Kandarakis, I; Panayiotakis, G S; Nomicos, C D

1997-01-01

ZnSCdS:Ag was evaluated as a radiographic image receptor and was compared with Gd sub 2 O sub 2 S:Tb and Y sub 2 O sub 2 S:Tb phosphors often used in radiography. The valuation of a radiographic receptor was modelled as a three-step process: i) determination of light output intensity as related to the input radiation dose, (ii) determination of visible light characteristics with respect to radiographic optical detectors, and (iii) determination of image information transfer efficiency. The light intensity emitted per unit of x-ray exposure rate was measured and theoretically calculated for laboratory prepared screens with coating thicknesses from 20 to 220 mg cm sup - sup 2 and tube voltages rom 50 to 250 kVp. ZnSCdS:Ag light intensity was higher than that of d sub 2 O sub 2 S:Tb or Y sub 2 O sub 2 S:Tb for tube voltages less than 70 and 80 kVp respectively. ZnSCdS:Ag displayed the highest x-ray to light conversion efficiency (0.207) and had optical properties close to those of Gd sub 2 O sub 2 S:Tb nd Y sub ...

Electrical characteristics for Sn-Ag-Cu solder bump with Ti/Ni/Cu under-bump metallization after temperature cycling tests

Science.gov (United States)

Shih, T. I.; Lin, Y. C.; Duh, J. G.; Hsu, Tom

2006-10-01

Lead-free solder bumps have been widely used in current flip-chip technology (FCT) due to environmental issues. Solder joints after temperature cycling tests were employed to investigate the interfacial reaction between the Ti/Ni/Cu under-bump metallization and Sn-Ag-Cu solders. The interfacial morphology and quantitative analysis of the intermetallic compounds (IMCs) were obtained by electron probe microanalysis (EPMA) and field emission electron probe microanalysis (FE-EPMA). Various types of IMCs such as (Cu1-x,Agx)6Sn5, (Cu1-y,Agy)3Sn, and (Ag1-z,Cuz)3Sn were observed. In addition to conventional I-V measurements by a special sample preparation technique, a scanning electron microscope (SEM) internal probing system was introduced to evaluate the electrical characteristics in the IMCs after various test conditions. The electrical data would be correlated to microstructural evolution due to the interfacial reaction between the solder and under-bump metallurgy (UBM). This study demonstrated the successful employment of an internal nanoprobing approach, which would help further understanding of the electrical behavior within an IMC layer in the solder/UBM assembly.

Systematic research on Ag2X (X = O, S, Se, Te) as visible and near-infrared light driven photocatalysts and effects of their electronic structures

Science.gov (United States)

Jiang, Wei; Wu, Zhaomei; Zhu, Yingming; Tian, Wen; Liang, Bin

2018-01-01

Four silver chalcogen compounds, Ag2O, Ag2S, Ag2Se and Ag2Te, can be utilized as visible-light-driven photocatalysts. In this research, the electronic structures of these compounds were analyzed by simulation and experiments to systematically reveal the relationship between photocatalytic performance and energetic structure. All four chalcogenides exhibited interesting photocatalytic activities under ultraviolet, visible and near-infrared light. However, their photocatalytic performances and stability significantly depended on the band gap width, and the valence band and conduct band position, which was determined by their composition. Increasing the X atomic number from O to Te resulted in the upward movement of the valence band top and the conduct band bottom, which resulted in narrower band gaps, a wider absorption spectrum, a weaker photo-oxidization capacity, a higher recombination probability of hole and electron pairs, lower quantum efficiency, and worse stability. Among them, Ag2O has the highest photocatalytic performance and stability due to its widest band gap and lowest position of VB and CB. The combined action of photogenerated holes and different radicals, depending on the different electronic structures, including anion ozone radical, hydroxide radical, and superoxide radical, was observed and understood. The results of experimental observations and simulations of the four silver chalcogen compounds suggested that a proper electronic structure is necessary to obtain a balance between photocatalytic performance and absorbable light region in the development of new photocatalysts.

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-12-15

Graphical abstract: - Highlights: • Ag, In and Sn were soluble in TiNi matrix, while Sb, Te, Tl, Pb and Bi were not. • The B2-R-B19′transformation occurred in Ti-Ni-(Ag, In, Sn) alloys. • Solid solution hardening was essential for inducing the B2-R transformation. - Abstract: The microstructures and transformation behaviors of Ti–Ni–X (Ag, In, Sn, Sb, Te, Tl, Pb, Bi) ternary alloys were investigated using electron probe micro-analysis (EPMA), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Micro Vickers hardness tests. All specimens consisted of Ti–Ni matrices and second phase particles. Ag, In and Sn were soluble in Ti–Ni matrices with a limited solubility (≤1.0 at%), while Sb, Te, Tl, Pb and Bi were not soluble. Two-stage B2-R-B19′ transformation occurred in Ti–48.8Ni–1.2Ag, Ti–49.0Ni–1.0In and Ti–49.0Ni–1.0Sn alloys, while one-stage B2-B19′ transformation occurred in Ti–49.0Ni–1.0Ag, Ti–49.0Ni–1.0Sb, Ti–49.0Ni–1.0Te, Ti–49.0Ni–1.0Pb and Ti–49.0Ni–1.0Bi alloys. Micro Vickers hardness of the alloys displaying the B2-R-B19′ transformation (Hv 250–368) was much larger than that (2-B19′ transformation. Solid solution hardening was an important factor for inducing the B2-R transformation in Ti–Ni–X (X = non-transition elements) alloys.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Hydrothermal Synthesis and Mechanism of Unusual Zigzag Ag2Te and Ag2Te/C Core-Shell Nanostructures

Directory of Open Access Journals (Sweden)

Saima Manzoor

2014-01-01

Full Text Available A single step surfactant-assisted hydrothermal route has been developed for the synthesis of zigzag silver telluride nanowires with diameter of 50–60 nm and length of several tens of micrometers. Silver nitrate (AgNO3 and sodium tellurite (Na2TeO3, are the precursors and polyvinylpyrrolidone (PVP is used as surfactant in the presence of the reducing agent, that is, hydrazine hydrate (N2H4·H2O. In addition to the zigzag nanowires a facile hydrothermal reduction-carbonization route is proposed for the preparation of uniform core-shell Ag2Te/C nanowires. In case of Ag2Te/C synthesis process the same precursors are employed for Ag and Te along with the ethylene glycol used as reducing agent and glucose as the carbonizing agent. Morphological and compositional properties of the prepared products are analyzed with the help of scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy, respectively. The detailed formation mechanism of the zigzag morphology and reduction-carbonization growth mechanism for core-shell nanowires are illustrated on the bases of experimental results.

Structural Investigation of Photocatalyst Solid Ag1−xCuxInS2 Quaternary Alloys Sprayed Thin Films Optimized within the Lattice Compatibility Theory (LCT Scope

Directory of Open Access Journals (Sweden)

A. Colantoni

2014-01-01

Full Text Available CuxAg1−xInS2 solid thin films were fabricated through a low-cost process. Particular process-related enhanced properties lead to reaching a minimum of lattice mismatch between absorber and buffer layers within particular solar cell devices. First, copper-less samples X-ray diffraction analysis depicts the presence of AgInS2 ternary compound in chalcopyrite tetragonal phase with privileged (112 peak (d112=1.70 Å according to JCPDS 75-0118 card. Second, when x content increases, we note a shift of the same preferential orientation (112 and its value reaches 1.63 Å corresponding to CuInS2 chalcopyrite tetragonal material according to JCPDS 89-6095 file. Finally, the formation and stability of these quaternaries have been discussed in terms of the lattice compatibility in relation with silver-copper duality within indium disulfide lattice structure. Plausible explanations for the extent and dynamics of copper incorporation inside AgInS2 elaborated ternary matrices have been proposed.

Step growth of an AB2 monomer, with cycle formation

DEFF Research Database (Denmark)

Cameron, Colin; Fawcett, Allan H.; Hetherington, Cecil R.

1998-01-01

A computer-based lattice model of the step growth reaction of an AB2 monomer, the next elaborate system after an AB monomer, has been devised that allows the simultaneous and explicit occurrence of inter- and intramolecular reactions of A and B groups of the flexible and moving molecules according...... with fractal characteristics. Growth stops when each molecule contains a cycle. For the model explored, in which six lattice sites are used for each monomer, the limiting value of the number average degree of polymerization, 〈x〉n,∞, is 14.6(±0.3) (after infinite time). The occurrence within the system of rings...... of m residues (m=1,2,3,...) is found to depend upon m and the extent of reaction of the A groups, pa, according to Rm=C0pm am-2.71, the constant C0 reflecting the structure of the lattice and the monomer, and being shown to determine the final degree of polymerization. The exponent of the integers m...

Enhanced Jc's of YBa2Cu3O7-x-Ag ex situ annealed coevaporated films on LaAlO3 (100) substrates

DEFF Research Database (Denmark)

Clausen, Thomas; Ejrnæs, Mikkel; Olesen, Michael Wiinberg

1995-01-01

A 5x increase of the critical current density (J(c)) at 77 K was obtained by coating a coevaporated 500 nm thick Y, BaF2, Cu film with 50 nm Ag prior to the ex situ annealing. J(c) increased from 0.2 for uncoated samples to 1 MA/cm(2) for the Ag-coated sample without severely affecting the zero...... resistance transition temperature (T-c0). Scanning electron microscopy showed that the surface morphology was improved and that the normally observed trellislike structure was greatly reduced. By combining electron microscopy and sputter assisted Auger analysis it was found that the Ag nucleated in droplets...

An approach for scalable production of silver (Ag) decorated WS2 nanosheets

Science.gov (United States)

Sumesh, C. K.; Kapatel, Sanni; Chaudhari, Arti

2018-05-01

In the Present study we report the synthesis of Ag nanoparticles (NPs) decorated WS2 nanosheets by sonochemical exfoliation followed by simple chemical reduction process at room temperature. The morphology and microstructure of the as-synthesized Ag-WS2 nanocomposite were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and optical absorption (UV-Vis.) spectroscopy. X-ray and TEM analysis shows the presence of Ag with significant peak over 38.08°, 44.22°, 64.37° and 77.33° at 2θ angle for (111), (200), (220) and (311) respectively. The Ag nanoparticles are randomly distributed throughout the surface of the WS2 nanosheets without undergoing further oxidation during the formation of composites. The formation of Ag-WS2 nanocomposites shows a clear blue shift in the absorption as we obtained the characteristics absorption valleys at 456, 536 and 631 nm from the UV Vis spectroscopy analysis compared to pure WS2 nanosheets. Henceforth a facile method for the Ag decoration on WS2 nanosheets was put forward and briefly discussed. The proposed synthesis method is very promising for the low cost and large-scale synthesis of other noble metal incorporation TMDC compounds.

Silver Nanocube and Nanobar Growth via Anisotropic Monomer Addition and Particle Attachment Processes.

Science.gov (United States)

Xiao, Dongdong; Wu, Zhigang; Song, Miao; Chun, Jaehun; Schenter, Gregory K; Li, Dongsheng

2018-01-30

Understanding the growth mechanism of noble metal nanocrystals during solution synthesis is of significant importance for shape and property control. However, much remains unknown about the growth pathways of metal nanoparticles due to the lack of direct observation. Using an in situ transmission electron microscopy technique, we directly observed Ag nanocube and nanobar growth in an aqueous solution through both classical monomer-by-monomer addition and nonclassical particle attachment processes. During the particle attachment process, Ag nanocubes and nanobars were formed via both oriented and nonoriented attachment. Our calculations, along with the dynamics of the observed attachment, showed that the van der Waals force overcomes hydrodynamic and friction forces and drives the particles toward each other at separations of 10-100 nm in our experiments. During classical growth, anisotropic growth was also revealed, and the resulting unsymmetrical shape constituted an intermediate state for Ag nanocube growth. We hypothesized that the temporary symmetry breaking resulted from different growth rates on (001) surfaces due to a local surface concentration variation caused by the imbalance between the consumption of Ag + near the surface and the diffusion of Ag + from the bulk to the surface.

Synthesis and photocatalytic properties of MgBi2O6 with Ag additions

Science.gov (United States)

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

2018-02-01

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

X-ray enhancement of CsI:Eu{sup 2+} radioluminescence

Energy Technology Data Exchange (ETDEWEB)

Leblans, P., E-mail: paul.leblans@agfa.com [Agfa-HealthCare NV, Septestraat 27, B-2640 Mortsel (Belgium); Struye, L.; Elen, S.; Mans, I. [Agfa-HealthCare NV, Septestraat 27, B-2640 Mortsel (Belgium); Vrielinck, H.; Callens, F. [Electron Magnetic Resonance Research Group, Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, B-9000 Gent (Belgium)

2015-09-15

CsI:Eu{sup 2+} needle crystal layers were produced by Physical Vapour Deposition (PVD). The luminescence properties were studied before and after thermal anneal. It was shown by Electron Paramagnetic Resonance (EPR) that annealing produces Eu{sup 2+} monomer centres, probably starting from Eu clusters in the needle crystalline layers. These centres seem structurally very similar to the Eu{sup 2+} monomer centres in annealed CsBr:Eu{sup 2+} needle layers. They give rise to a narrow luminescence band peaking at about 450 nm (2.76 eV) at room temperature, both under X-ray and UV excitation. The luminescence intensity of as-deposited layers is low. Annealing enhances photo- and radioluminescence on average by a factor of 1.5–3. Surprisingly, further sensitization of radioluminescence with a factor of up to 7 is possible by exposing the annealed needle layers to X-rays or UV, while in contrast, UV excited luminescence is slightly reduced. X-ray enhancement thus leads to a structured scintillator with a conversion efficiency of about 42,000 photons/MeV upon X-ray excitation. A similar radioluminescence enhancement is observed for annealed CsI:Eu{sup 2+} fine powder, but not for large single crystals or conglomerated polycrystals. The measurements and observations are consistent with Eu{sup 2+} monomer centres stabilized by water molecules. These molecules are incorporated via annealing, and that this happens when the morphology is such that water can diffuse throughout the volume of the crystals. The presence of stabilized Eu{sup 2+} monomers is necessary to enhance radioluminescence by X-ray exposure. A mechanism is proposed for the phenomenon.

Ag/Pd core-shell nanoparticles by a successive method: Pulsed laser ablation of Ag in water and reduction reaction of PdCl{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Mottaghi, N. [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Ranjbar, M., E-mail: ranjbar@cc.iut.ac.ir [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Farrokhpour, H. [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Khoshouei, M. [Max Planck Institute of Biochemistry, Department of Molecular Structural Biology, Am Klopferspitz 18, Martinsried 82152 (Germany); Khoshouei, A.; Kameli, P.; Salamati, H. [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Tabrizchi, M. [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Jalilian-Nosrati, M. [Physics department, Central Azad University, Tehran 14676-86831 (Iran, Islamic Republic of)

2014-02-15

In this study Ag/Pd nanoparticles (NPs) have been fabricated by a successive method; first, colloids of Ag nanoparticles (NPs) have been prepared in water by pulsed laser ablation in liquid (PLAL) method. Then PdCl{sub 2} solution (up to 0.2 g/l) were added to the as-prepared or aged colloidal Ag NPs. Characterizations were done using UV–vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmissions electron microscopy (TEM) techniques. Spectroscopy data showed that surface plasmon resonance (SPR) peaks of as-prepared Ag NPs at about λ = 400 nm were completely extinguished after addition of PdCl{sub 2} solution while this effect was not observed when aged Ag NPs are used. XRD and XPS results revealed that by addition of the PdCl{sub 2} solution into the as-prepared Ag NPs, metallic palladium, and silver chloride composition products are generated. TEM images revealed that as a result of this reaction, single and core-shell nanoparticles are obtained and their average sizes are 2.4 nm (Ag) and 3.2 nm (Ag/Pd). The calculated d-spacing values form XRD data with observations on high magnification TEM images were able to explain the chemical nature of different parts of Ag/Pd NPs.

Trivial topological phase of CaAgP and the topological nodal-line transition in CaAg (P1 -xA sx)

Science.gov (United States)

Xu, N.; Qian, Y. T.; Wu, Q. S.; Autès, G.; Matt, C. E.; Lv, B. Q.; Yao, M. Y.; Strocov, V. N.; Pomjakushina, E.; Conder, K.; Plumb, N. C.; Radovic, M.; Yazyev, O. V.; Qian, T.; Ding, H.; Mesot, J.; Shi, M.

2018-04-01

By performing angle-resolved photoemission spectroscopy and first-principles calculations, we address the topological phase of CaAgP and investigate the topological phase transition in CaAg (P1 -xA sx) . We reveal that in CaAgP, the bulk band gap and surface states with a large bandwidth are topologically trivial, in agreement with hybrid density functional theory calculations. The calculations also indicate that application of "negative" hydrostatic pressure can transform trivial semiconducting CaAgP into an ideal topological nodal-line semimetal phase. The topological transition can be realized by partial isovalent P/As substitution at x =0.38 .

Fig .1. X-ray diffraction (XRD) patterns of Ag2Se-G-TiO2 composites.

Indian Academy of Sciences (India)

32

SEM images of Ag2Se-G nanocomposites, (c)TiO2 nanoparticles and (d) SEM images of Ag2Se-. G-TiO2 .... Although photo-catalytic conversion of CO2 using solar energy is the most convenient route for the ..... based structure of graphene, the unpaired π electron merges with the metal nanoparticles, causing a shift in the ...

Plasma-induced formation of flower-like Ag{sub 2}O nanostructures

Energy Technology Data Exchange (ETDEWEB)

Yang, Zen-Hung; Ho, Chun-Hsien; Lee, Szetsen, E-mail: slee@cycu.edu.tw

2015-09-15

Graphical abstract: Flower-like Ag{sub 2}O nanostructures. - Highlights: • Flower-like Ag{sub 2}O nanostructures were synthesized from Ag colloids using plasma. • XPS was used to monitor plasma treatment effect on Ag colloids. • SERS of methyl orange was used to monitor the plasma oxidation–reduction processes. • Photocatalytic degradation of methylene blue was performed using Ag{sub 2}O. • Ag{sub 2}O is a more efficient visible light photocatalyst than Ag colloids. - Abstract: Plasma treatment effect on Ag colloids was investigated using X-ray photoelectron spectroscopy (XPS) and surface-enhanced Raman scattering (SERS) techniques. XPS showed that O{sub 2} plasma was critical in removing organic residues in Ag colloids synthesized using citric acid as a reducing agent. With O{sub 2} plasma treatment, Ag colloids were also oxidized to form flower-like Ag{sub 2}O nanostructures. The formation mechanism is proposed. The SERS spectral intensity of methyl orange (MO) adsorbed on Ag surface became deteriorated with O{sub 2} plasma treatment. Followed by H{sub 2} plasma treatment, the SERS intensity of MO on Ag regained, which indicated that Ag{sub 2}O has been reduced to Ag. Nonetheless, the reduction by H{sub 2} plasma could not bring Ag back to the original as-synthesized nanoparticle morphology. The flower-like nanostructure morphology still remained. The photocatalytic degradation reactions of methylene blue (MB) aqueous solutions were carried out using Ag colloids and Ag{sub 2}O nanostructures. The results show that Ag{sub 2}O is more efficient than Ag colloids and many other metal oxides for the photocatalytic degradation of MB in solution when utilizing visible light.

Crystal and electronic structure study of AgAu and AgCu bimetallic alloy thin films by X-ray techniques

Energy Technology Data Exchange (ETDEWEB)

Ozkendir, O. Murat, E-mail: ozkendir@gmail.com [Mersin University, Faculty of Technology, Energy Systems Engineering, Tarsus (Turkey); Mersin University, Institute of Natural Science, Department of Nanotechnology and Advanced Materials, Mersin (Turkey); Cengiz, E. [Karadeniz Technical University, Faculty of Science, Department of Physics, Trabzon (Turkey); Yalaz, E. [Mersin University, Institute of Natural Science, Department of Nanotechnology and Advanced Materials, Mersin (Turkey); Söğüt, Ö.; Ayas, D.H. [Kahramanmaraş Sütçü İmam Üniversitesi, Faculty of Science and Letters, Department of Physics, Kahramanmaraş (Turkey); Thammajak, B. Nirawat [Synchrotron Light Research Institute (Public Organisation), 111 University Avenue, T. Suranaree, A. Muang, Nakhon Ratchasima 30000 (Thailand)

2016-05-15

Highlights: • Crystal and electronic properties of bimetallic AgCu and AgAu alloy thin films were studied. • Both AgCu and AgAu bimetallic samples were determined to have cubic crystal geometry. • Strong influence of Cu and Au atoms on the electronic structure of the Ag atoms were determined. - Abstract: Crystal and electronic structure properties of bimetallic AgAu and AgCu alloy thin films were investigated by X-ray spectroscopic techniques. The aim of this study is to probe the influence of Au or Cu atoms on the electronic behaviors of Ag ions in bimetallic alloy materials that yields different crystal properties. To identify the mechanisms causing crystal phase transitions, study were supported by the collected EXAFS (Extended X-ray Absorption Fine Structure) data. Crystal structures of both Cu and Au doped bimetallic Ag samples were determined mainly in cubic geometry with “Fm3m” space group. Through the Ag–Au and Ag–Cu molecular interactions during bimetallic alloy formations, highly overlapped electronic levels that supports large molecular band formations were observed with different ionization states. Besides, traces of the d–d interactions in Au rich samples were determined as the main interplay in the broad molecular bond formations. The exact atomic locations and types in the samples were determined by EXAFS studies and supported by the performed calculations with FEFF scientific code.

Development of the ReuseTechnology for Radioactive Waste from Nuclear Fuel Cycle - Development of the off-gas treatment technology

International Nuclear Information System (INIS)

Oh, Won Zin; Lee, H. K.; Park, G. I.; Cho, I. H.; Choi, B. S.; Lee, K. W.; Jeong, M. S.

1998-09-01

Treatment technologies for noble gases and semi-volatile gases generated from nuclear fuel cycle process were evaluated, and the optimal process was selected based on process simplicity and safety of disposal. Evaluation of the adsorption capacity of methyl iodine on AgX(silver-impregnated zeolite) and AgS(silver-impregnated silica gel) at the temperature of 80-300 deg C was carried out, and adsorption performances of AgX and AgS were compared with that of activated carbon. CO 2 removal capacity using soda lime, activated carbon and 13X was investigated, and effect of relative humidity was identified. A preparation method of granular calcium hydroxide as a CO-2 removal sorbent using oyster-shells was characterized. This study involves the comparison of the adsorption capacities of Kr on natural or synthetic zeolites and activated carbon at high concentration and an analysis of humidity effect on water adsorption of natural-zeolite. It also was carried out that performance tests for reuse of activated carbon through desorption and re-impregnation process of TEDA/KI impregnated carbon as a removal sorbent for organic radio iodines. (author). 132 refs., 17 tabs., 29 figs

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-01-15

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

H{sub 2} assisted NH{sub 3}-SCR over Ag/Al{sub 2}O{sub 3} for automotive applications

Energy Technology Data Exchange (ETDEWEB)

Fogel, S.

2013-05-15

The up-coming strict emission legislation demands new and improved catalysts for diesel vehicle deNO{sub x}. The demand for low-temperature activity is especially challenging. H{sub 2}-assisted NH{sub 3}-SCR over Ag/Al{sub 2}O{sub 3} has shown a very promising low-temperature activity and a combination of Ag/Al{sub 2}O{sub 3} and Fe-BEA can give a high NO{sub x} conversion in a broad temperature window without the need to dose H{sub 2} at higher temperatures. The aim of this study has been to investigate the combined Ag/Al{sub 2}O{sub 3} and Fe-BEA catalyst system both at laboratory-scale and in full-scale engine bench testing. The catalysts were combined both in a sequential dual-bed layout and a dual-layer layout where the catalysts were coated on top of each other. The Ag/Al{sub 2}O{sub 3} catalyst was also investigated with the aim of improving the sulphur tolerance and low-temperature activity by testing different alumina-supports. A large focus of this study has been the preparation of monolithic catalyst bricks for the catalyst testing. A high SBET and higher Ag loading gave a high sulphur tolerance and activity. It was believed that the high S{sub BET} is needed to give a higher NH{sub 3} adsorption capacity, necessary for the SCR reaction. A higher Ag loading gives more Ag sites and probably a favourable Ag dispersion. Testing with sulphur gave an increased activity of the catalysts. Testing of monolithic catalysts showed a similar activity enhancement after a few standard test cycles. A change in the dispersion or state of Ag can be possible reasons for the activation seen and the activation was believed to be related to Ag and not the alumina. Small-scale laboratory testing showed that it was preferred to have Ag/Al{sub 2}O{sub 3} either upstream or as the outer layer of Fe-BEA. This was attributed to complete NH{sub 3} oxidation over Fe-BEA giving a deficit of NH{sub 3} over the Ag/Al{sub 2}O{sub 3} if it was placed downstream or as the inner layer

New chalcogenide glasses in the CdTe-AgI-As{sub 2}Te{sub 3} system

Energy Technology Data Exchange (ETDEWEB)

Kassem, M. [Univ. Picardie Jules Verne, F-80000 Amiens (France); Le Coq, D., E-mail: david.lecoq@univ-littoral.fr [Univ. Lille Nord de France, F-59000 Lille (France); ULCO, LPCA, EA 4493, F-59140 Dunkerque (France); Boidin, R.; Bychkov, E. [Univ. Lille Nord de France, F-59000 Lille (France); ULCO, LPCA, EA 4493, F-59140 Dunkerque (France)

2012-02-15

Highlights: Black-Right-Pointing-Pointer Determination of the glass-forming region in the pseudo-ternary CdTe-AgI-As{sub 2}Te{sub 3} system. Black-Right-Pointing-Pointer Characterization of macroscopic properties of the new CdTe-AgI-As{sub 2}Te{sub 3} glasses. Black-Right-Pointing-Pointer Characterization of the total conductivity of CdTe-AgI-As{sub 2}Te{sub 3} glasses. Black-Right-Pointing-Pointer Comparison between the selenide and telluride equivalent systems. -- Abstract: Chalcogenide glasses in the pseudo-ternary CdTe-AgI-As{sub 2}Te{sub 3} system were synthesized and the glass-forming range was determined. The maximum content of CdTe in this glass system was found to be equal to 15 mol.%. The macroscopic characterizations of samples have consisted in Differential Scanning Calorimetry, density, and X-ray diffraction measurements. The cadmium telluride addition does not generate any significant change in the glass transition temperature but the resistance of binary AgI-As{sub 2}Te{sub 3} glasses towards crystallisation is estimated to be decreasing on the base of {Delta}T = T{sub x} - T{sub g} parameter. The total electrical conductivity {sigma} was measured by complex impedance spectroscopy. First, the CdTe additions in the (AgI){sub 0.5}(As{sub 2}Te{sub 3}){sub 0.5} host glass, (CdTe){sub x}(AgI){sub 0.5-x/2}(As{sub 2}Te{sub 3}){sub 0.5-x/2} lead to a conductivity decrease at x {<=} 0.05. Then, the behaviour is reversed at 0.05 {<=} x {<=} 0.15. The obtained results are discussed by comparison with the equivalent selenide system.

Study on antibacterial activity of chemically synthesized PANI-Ag-Au nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Boomi, Pandi [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Prabu, Halliah Gurumallesh, E-mail: hgprabu2010@gmail.com [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Manisankar, Paramasivam [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Ravikumar, Sundaram [Department of Oceanography and Coastal Area Studies, School of Marine Sciences, Alagappa University, Thondi Campus 623 409, Tamil Nadu (India)

2014-05-01

Graphical abstract: - Highlights: • New method of synthesizing PANI-Ag-Au nanocomposite. • Surface Plasmon resonance and formation of composite at nano level were analyzed. • HR-TEM study revealed uniform distribution of nanoparticles. • PANI-Ag-Au nanocomposite exhibited good antibacterial activity. - Abstract: Pristine polyaniline (PANI), PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites have been successfully synthesized by chemical oxidative polymerization method using aniline as monomer, ammonium persulphate as oxidant and metal (Ag, Au and Ag-Au) colloids. UV-Vis analysis exhibited surface Plasmon resonances of Ag, Au, Ag-Au nanoparticles. FT-IR spectra revealed the shift in peak position of N-H stretching. X-ray diffraction (XRD) results confirm the presence of Ag, Au and Au-Ag nanoparticles. HR-TEM images show nanosizes of Ag, Au, Ag-Au and the incorporation of such nanoparticles into the PANI matrix. Pristine PANI, PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites were tested for antibacterial activity by agar well diffusion method. PANI-Ag-Au nanocomposite exhibited higher antibacterial activity against both gram-positive [Streptococcus sp. (MTCC 890), Staphylococcus sp. (MTCC 96)] and gram-negative bacteria [Escherichia coli (MTCC 1671) and Klebsiella sp. (MTCC 7407)] when compared with PANI-Ag nanocomposite, PANI-Au nanocomposite and pristine PANI. The novelty of this study is the polymer-bimetal synthesis and its antibacterial potential.

One-pot synthesis of Ag-SiO2-Ag sandwich nanostructures

International Nuclear Information System (INIS)

Li Chaorong; Mei Jie; Li Shuwen; Lu Nianpeng; Wang Lina; Chen Benyong; Dong Wenjun

2010-01-01

Ag-SiO 2 -Ag sandwich nanostructures were prepared by a facile one-pot synthesis method. The Ag core, SiO 2 shell and Ag nanoparticle shell were all synthesized with polyvinylpyrrolidone, catalysed by ammonia, in the one-pot reaction. The polyvinylpyrrolidone, acting as a smart reducing agent, reduced the Ag + to Ag cores and Ag shells separately. Furthermore, the polyvinylpyrrolidone served as a protective agent to prevent the silver cores from aggregating. The SiO 2 shell and outer layer Ag nanoparticles were obtained when tetraethyl orthosilicate and ammonia were added to the silver core solution. Ammonia, acting as the catalyst, accelerated the hydrolysis of the tetraethyl orthosilicate to SiO 2 , which coated the silver cores. Furthermore, Ag(NH 3 ) 2 + ions were formed when aqueous ammonia was added to the solution, which increased the reduction capability. Then the polyvinylpyrrolidone reduced the Ag(NH 3 ) 2 + ions to small Ag nanoparticles on the surface of the Ag-SiO 2 and formed Ag-SiO 2 -Ag sandwich structures with a standard deviation of less than 4%. This structure effectively prevented the Ag nanoparticles on the silica surface from aggregating. Furthermore, the Ag-SiO 2 -Ag sandwich structures showed good catalysis properties due to the large surface area/volume value and activity of surface atoms of Ag particles.

Synthesis and Characterization of Ag-Modified V2O5 Photocatalytic Materials

Directory of Open Access Journals (Sweden)

Dora Alicia Solis-Casados

2017-01-01

Full Text Available V2O5 powders modified with different theoretical silver contents (1, 5, 10, 15, and 20 wt% as Ag2O were obtained with acicular morphologies observed by scanning electron microscopy (SEM. Shcherbinaite crystalline phase is transformed into the Ag0.33V2O5 crystalline one with the incorporation and increase in silver content as was suggested by X-ray diffraction (XRD and X-ray photoelectron spectroscopy (XPS analysis. With further increase in silver contents the Ag2O phase appears. Catalysts were active in photocatalytic degradation of malachite green dye under simulated solar light, which is one of the most remarkable facts of this work. It was found that V2O5-20Ag was the most active catalytic formulation and its activity was attributed to the mixture of coupled semiconductors that promotes the slight decrease in the rate of the electron-hole pair recombination.

First-principles study of Sb adsorption on Ag(1 1 0)(2 x 2)

International Nuclear Information System (INIS)

Nie, J.L.; Xiao, H.Y.; Zu, X.T.; Gao Fei

2006-01-01

The adsorption of antimony atom on the Ag(1 1 0) surface has been studied within the density functional theory framework. It was turned out that Sb-Ag surface alloy was formed in which Sb atoms substitute Ag atom in the outermost layer and subsurface site absorption was not preferred, suggesting that Sb is well segregated to the surface. Geometric analysis showed that rumpling between substitutional Sb and Ag in the alloy surface is negligible. These results are found to agree well with the experimental finding of Nascimento et al. [Surf. Sci. 572 (2004) 337]. In addition, investigation of the diffusion of Ag atom on bare and Sb-covered Ag(1 1 0) surface showed that Ag adatoms will jump along the so call in-channel direction and Sb substitution has little effect on the diffusion of Ag adatoms on Ag(1 1 0) surface. Such diffusion behavior was found to be different from that of Ag adatoms on Ag(1 1 1) surface, where the diffusion energy barrier was reported to be significantly increased upon Sb substitution [Phys. Rev. Lett. 73 (1993) 2437

Ab initio studies of structural, electronic, optical, elastic and thermal properties of silver gallium dichalcogenides (AgGaX2: X = S, Se, Te)

International Nuclear Information System (INIS)

Sharma, Sheetal; Verma, A.S.; Jindal, V.K.

2014-01-01

Graphical abstract: - Highlights: • FP-LAPW method has been used to compute the solid state properties of AgGaX 2 (X = S, Se, Te). • Electronic and optical properties reported with recently developed mBJ potential. • Thermal expansion, heat capacity, Debye temperature, entropy and Grüneisen parameter were evaluated. • Hardness was calculated for the first time at different temperature and pressure. - Abstract: We have performed ab initio calculations for the structural, electronic, optical, elastic and thermal properties of the silver gallium dichalcogenides (AgGaX 2 : X = S, Se, Te). In this study, we have used the accurate full potential linearized augmented plane wave (FP-LAPW) method to find the equilibrium structural parameters and to compute the six elastic constants (C 11 , C 12 , C 13 , C 33 , C 44 and C 66 ). We have reported electronic and optical properties with the recently developed density functional theory of Tran and Blaha, and this theory is used along with the Wu-Cohen generalized gradient approximation (WC-GGA) for the exchange-correlation potential. Furthermore, optical features such as dielectric functions, refractive indices, extinction coefficient, optical reflectivity, absorption coefficients and optical conductivities were calculated for photon energies up to 40 eV. The thermodynamical properties such as thermal expansion, heat capacity, debye temperature, entropy, Grüneisen parameter and bulk modulus were calculated employing the quasi-harmonic Debye model at different temperatures (0–900 K) and pressures (0–8 GPa) and the silent results were interpreted. Hardness of the materials was calculated for the first time at different temperatures and pressures

Characterization and Comparison of Photocatalytic Activity Silver Ion doped on TiO2(TiO2/Ag+) and Silver Ion doped on Black TiO2(Black TiO2/Ag+)

Science.gov (United States)

Kim, Jin Yi; Sim, Ho Hyung; Song, Sinae; Noh, Yeoung Ah; Lee, Hong Woon; Taik Kim, Hee

2018-03-01

Titanium dioxide (TiO2) is one of the representative ceramic materials containing photocatalyst, optic and antibacterial activity. The hydroxyl radical in TiO2 applies to the intensive oxidizing agent, hence TiO2 is suitable to use photocatalytic materials. Black TiO2was prepared through reduction of amorphous TiO2 conducting under H2 which leads to color changes. Its black color is proven that absorbs 100% light across the whole-visible light, drawing enhancement of photocatalytic property. In this study, we aimed to compare the photocatalytic activity of silver ion doped on TiO2(TiO2/Ag+) and silver ion doped on black TiO2(black TiO2/Ag+) under visible light range. TiO2/Ag+ was fabricated following steps. 1) TiO2 was synthesized by a sol-gel method from Titanium tetraisopropoxide (TTIP). 2) Then AgNO3 was added during an aging process step for silver ion doping on the surface of TiO2. Moreover, Black TiO2/Ag+ was obtained same as TiO2/Ag+ except for calcination under H2. The samples were characterized X-ray diffraction (XRD), UV-visible reflectance (UV-vis DRS), and Methylene Blue degradation test. XRD analysis confirmed morphology of TiO2. The band gap of black TiO2/Ag+ was confirmed (2.6 eV) through UV-vis DRS, which was lower than TiO2/Ag+ (2.9 eV). The photocatalytic effect was conducted by methylene blue degradation test. It demonstrated that black TiO2/Ag+ had a photocatalytic effect under UV light also visible light.

The synthesis of Ag/polypyrrole coaxial nanocables via ion adsorption method using different oxidants

Science.gov (United States)

Qiu, Teng; Xie, Huxiao; Zhang, Jiangru; Zahoor, Amad; Li, Xiaoyu

2011-03-01

Ag/polypyrrole (PPy) coaxial nanocables (NCs) were synthesized by an ion adsorption method. In this method, the pre-made Ag nanowires (NWs) were dispersed in the aqueous solution of copper acetate (Cu(Ac)2), and the Cu2+ ions adsorbed onto the surface of Ag NWs can oxidize pyrrole monomers to polymerize into uniform PPy sheath outside Ag NWs after the Cu(Ac)2-treated Ag NWs were re-dispersed in the aqueous solution of pyrrole. The morphology of NCs was characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). The relationship between the thickness of polymer sheath and the concentration of Cu(Ac)2 was established. As Cu(Ac)2 which served as the oxidant can also be replaced by AgNO3 in this synthesis, the differences on the structure of polymer sheath caused by different oxidants were studied by surface-enhanced Raman scattering (SERS), high-resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Comparing with the characterization results of Ag/PPy NCs synthesized using AgNO3 as the oxidant which indicates the random arrangement of PPy chains at the interface between polymer sheath and Ag NWs, PPy chain oxidized by Cu2+ tends to show a relatively ordered conformation at the interface with the pyrrole rings identically taking the plane vertical to the surface of Ag NWs. In addition, although the main part of the polymer sheath was composed of PPy whatever kind of oxidant was used, the sheath of the NCs oxidized by Cu2+ is typical for the existence of Cu(I)-pyrrole coordinate structures with strong Cu(I)-N bond signal shown in XPS characterization.

The synthesis of Ag/polypyrrole coaxial nanocables via ion adsorption method using different oxidants

International Nuclear Information System (INIS)

Qiu Teng; Xie Huxiao; Zhang Jiangru; Zahoor, Amad; Li Xiaoyu

2011-01-01

Ag/polypyrrole (PPy) coaxial nanocables (NCs) were synthesized by an ion adsorption method. In this method, the pre-made Ag nanowires (NWs) were dispersed in the aqueous solution of copper acetate (Cu(Ac) 2 ), and the Cu 2+ ions adsorbed onto the surface of Ag NWs can oxidize pyrrole monomers to polymerize into uniform PPy sheath outside Ag NWs after the Cu(Ac) 2 -treated Ag NWs were re-dispersed in the aqueous solution of pyrrole. The morphology of NCs was characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). The relationship between the thickness of polymer sheath and the concentration of Cu(Ac) 2 was established. As Cu(Ac) 2 which served as the oxidant can also be replaced by AgNO 3 in this synthesis, the differences on the structure of polymer sheath caused by different oxidants were studied by surface-enhanced Raman scattering (SERS), high-resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Comparing with the characterization results of Ag/PPy NCs synthesized using AgNO 3 as the oxidant which indicates the random arrangement of PPy chains at the interface between polymer sheath and Ag NWs, PPy chain oxidized by Cu 2+ tends to show a relatively ordered conformation at the interface with the pyrrole rings identically taking the plane vertical to the surface of Ag NWs. In addition, although the main part of the polymer sheath was composed of PPy whatever kind of oxidant was used, the sheath of the NCs oxidized by Cu 2+ is typical for the existence of Cu(I)–pyrrole coordinate structures with strong Cu(I)–N bond signal shown in XPS characterization.

Precipitation of Ag2Te in the thermoelectric material AgSbTe2

International Nuclear Information System (INIS)

Sugar, Joshua D.; Medlin, Douglas L.

2009-01-01

The microstructure of AgSbTe 2 , prepared by solidification, is investigated using electron microscopy. During solidification and thermal treatment, the material separates into a two-phase mixture of a rocksalt phase, which is Ag 22 Sb 28 Te 50 , and silver telluride, Ag 2 Te. Ag 2 Te formation results either from eutectic solidification (large lamellar structures), or by solid-state precipitation (fine-scale particles). The crystal structure of the AgSbTe 2 phase determined by electron diffraction is consistent with a rocksalt structure that has a disordered cation sublattice. A preferred crystallographic orientation relationship at the interface between the matrix and the low-temperature monoclinic Ag 2 Te phase is defined and discussed. This orientation relationship is observed for both second-phase morphologies. In both cases, the orientation relationship originates from a topotactic (cube-on-cube) alignment of the Te sublattices in the initially cubic Ag 2 Te and the matrix at elevated temperature. This Te sublattice alignment is retained as the Ag 2 Te undergoes a cubic-to-monoclinic transformation during cooling. This orientation relationship is observed for both second-phase morphologies.

Antimicrobial activity and biocompatibility of Ag+- and Cu2+-doped biphasic hydroxyapatite/α-tricalcium phosphate obtained from hydrothermally synthesized Ag+- and Cu2+-doped hydroxyapatite

International Nuclear Information System (INIS)

Radovanović, Željko; Jokić, Bojan; Veljović, Djordje; Dimitrijević, Suzana; Kojić, Vesna; Petrović, Rada; Janaćković, Djordje

2014-01-01

Hydroxyapatite (HAp) powders doped with Ag + or Cu 2+ were synthesized by a hydrothermal method in order to obtain biomaterial with an antimicrobial effect. The synthesis was performed with two contents of dopant (Ag + or Cu 2+ ) by considering both the antimicrobial activities and biocompatibility of the powders. The doped HAp was annealed at 1200 °C for 2 h with the intention of investigating the influence of doping with Ag + and Cu 2+ on the creation of the biphasic HAp/α-tricalcium phosphate (HAp/α-TCP) and determining the antimicrobial activity and biocompatibility of the obtained biphasic powders. Analyses of all powders, undoped and doped HAp and HAp/α-TCP, were performed by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS) and energy-dispersive X-ray spectroscopy (EDS). The in vitro antibacterial activities of the powders were evaluated against: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. All powders showed good antimicrobial activity but generally the powders of doped HAp/α-TCP had more uniform results against all pathogenic microorganisms than the powders of doped HAp. In vitro biocompatibility tests, MTT and DET, were used to evaluate the biocompatibility of Ag + - and Cu 2+ -doped HAp/α-TCP with MRC-5 human fibroblast cells. These tests confirmed that powders do not have a cytotoxic effect. The HAp/α-TCP powders doped with the lower content of Ag + and Cu 2+ showed especially good biocompatibility. Antimicrobial and biocompatibility tests recommend the Ag + - and Cu 2+ -doped HAp/α-TCP as promising material for use in reconstructive surgery of bone.

Synthesis, structural, electronic and linear electro-optical features of new quaternary Ag{sub 2}Ga{sub 2}SiS{sub 6} compound

Energy Technology Data Exchange (ETDEWEB)

Piasecki, M., E-mail: m.piasecki@ajd.czest.pl [Institute of Physics, Jan Dlugosz University, Armii Krajowej 13/15, PL-42-201 Czestochowa (Poland); Myronchuk, G.L. [Department of Solid State Physics, Lesya Ukrainka Eastern European National University, 13 Voli Ave., Lutsk 43025 (Ukraine); Parasyuk, O.V. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, 13 Voli Ave., Lutsk 43025 (Ukraine); Khyzhun, O.Y. [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky St., Kyiv 03142 (Ukraine); Fedorchuk, A.O. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, 50 Pekarska Street, Lviv 79010 (Ukraine); Pavlyuk, V.V. [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, 6 Kyryla and Mefodiya St., 79005 Lviv (Ukraine); Institute of Chemistry, Environment Protection and Biotechnology, Jan Dlugosz University, al. Armii Krajowej 13/15, 42-200 Czestochowa (Poland); Kozer, V.R.; Sachanyuk, V.P. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, 13 Voli Ave., Lutsk 43025 (Ukraine); El-Naggar, A.M. [Physics Department, Faculty of Science, Ain Shams University, Abassia, Cairo 11566 (Egypt); Research Chair of Exploitation of Renewable Energy Applications in Saudi Arabia, Physics & Astronomy Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Albassam, A.A. [Research Chair of Exploitation of Renewable Energy Applications in Saudi Arabia, Physics & Astronomy Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Jedryka, J.; Kityk, I.V. [Faculty of Electrical Engineering, Czestochowa University Technology, Armii Krajowej 17, Czestochowa (Poland)

2017-02-15

For the first time phase equilibria and phase diagram of the AgGaS{sub 2}–SiS{sub 2} system were successfully explored by differential thermal and X-ray phase analysis methods. Crystal structure of low-temperature (LT) modification of Ag{sub 2}Ga{sub 2}SiS{sub 6} (LРў- Ag{sub 2}Ga{sub 2}SiS{sub 6}) was studied by X-ray powder method and it belongs to tetragonal space group I-42d, with unit cell parameters a=5.7164(4) Å, c=9.8023(7) Å, V=320.32(7) Å{sup 3}. Additional details regarding the crystal structure exploration are available at the web page Fachinformationszentrum Karlsruhe. X-ray photoelectron core-level and valence-band spectra were measured for pristine LРў- Ag{sub 2}Ga{sub 2}SiS{sub 6} crystal surface. In addition, the X-ray photoelectron valence-band spectrum of LРў-Ag{sub 2}Ga{sub 2}SiS{sub 6} was matched on a common energy scale with the X-ray emission S Kβ{sub 1,3} and Ga Kβ{sub 2} bands, which give information on the energy distribution of the S 3p and Ga 4p states, respectively. The presented X-ray spectroscopy results indicate that the valence S p and Ga p atomic states contribute mainly to the upper and central parts of the valence band of LРў-Ag{sub 2}Ga{sub 2}SiS{sub 6}, respectively, with a less significant contribution also to other valence-band regions. Band gap energy was estimated by measuring the quantum energy in the spectral range of the fundamental absorption. We have found that energy gap Eg is equal to 2.35 eV at 300 K. LT-Ag{sub 2}Ga{sub 2}SiS{sub 6} is a photosensitive material and reveals two spectral maxima on the curve of spectral photoconductivity spectra at λ{sub max1} =590 nm and λ{sub max2} =860 nm. Additionally, linear electro-optical effect of LT-Ag{sub 2}Ga{sub 2}SiS{sub 6} for the wavelengths of a cw He-Ne laser at 1150 nm was explored. - Graphical abstract: Manuscript present the technology of growth and investigation of properties a new quaternary compound Ag{sub 2}Ga{sub 2}SiS{sub 6

Coating stainless steel plates with Ag/TiO2 for chlorpyrifos decontamination

Science.gov (United States)

Abdel Fattah, Wafa I.; Gobara, Mohammed M.; El-Hotaby, Walid; Mostafa, Sherif F. M.; Ali, Ghareib W.

2016-05-01

Spray coatings of either nanosilver (Ag), titanium (TiO2) or nanosilver titanium (Ag/TiO2) on stainless steel substrates prepared by sol-gel process were successfully achieved. The efficiency of the Ag/TiO2 coat onto 316 stainless steel surface towards cloropyrifos degradation as a chemical warfare agent (CWA) was proved. The crystalline structure and morphological characterization, as well as surface roughness measurements, were assessed. X-ray diffraction results proved the crystalline TiO2 anatase phase. The uniform distribution of Ag along with TiO2 nanoparticles was evidenced through transmission electron microscopy and scanning electron microscopy mapping. The hydrophilic nature of individual Ag, TiO2 and Ag/TiO2 coats was proved by contact angle measurements. The loading of Ag nanoparticles influenced positively the Ag/TiO2 coats surface roughness. The photocatalytic cloropyrifos degradation achieved about 50% within one-hour post UV treatment proving, therefore, the promising Ag/TiO2 continued decontamination efficiency. In conclusion, tuning the physical and morphological properties of TiO2 coated on stainless steel surface could be significantly enhanced by Ag nanoparticles incorporation. The developed Ag/TiO2 coat could be conveniently applied as CWA decontaminant.

Structural and optical properties of AgCl-sensitized TiO2 (TiO2 @AgCl prepared by a reflux technique under alkaline condition

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V. A. Mu’izayanti

Full Text Available Abstract The AgCl-sensitized TiO2 (TiO2@AgCl has been prepared from the precursor of TiO2-rutile type which on its surface adsorb chloride anion (Cl- and various amounts of silver using AgNO3 as starting material: AgNO3/(AgNO3+TiO2 mass ratio of 0.00, 1.14, 3.25, 6.38 and 10.32%. Reflux under alkaline condition was the employed technique. All samples were characterized by X-ray diffraction (XRD and diffuse reflectance UV-vis spectroscopy. The sample without the addition of AgNO3 was analyzed by scanning electron microscope and surface area analyzer. The morphology of the sample showed a distribution of microspheres of approximately 0.5 to 1.0 µm and the specific surface area was 68 m2/g. XRD patterns indicated that the sample without the addition of AgNO3 contained two types of TiO2: rutile (major and anatase (minor, whereas the samples with the addition of AgNO3 consisted of one phase of AgCl and two types of TiO2: rutile and anatase. The bandgaps of the samples were in the range of 2.97 to 3.24 eV, which were very close to the bandgap of intrinsic TiO2 powder. The presence of 0.8, 2.6 and 4.4 wt% of AgCl in each sample resulted in an additional bandgap in visible light region of 1.90, 1.94 and 2.26 eV, respectively, whereas the presence of 9.4 wt% of AgCl in the sample resulted in two bandgaps in visible light region of 1.98 and 1.88 eV.

Interpretation of dc and ac conductivity of Ag2O–SeO2–MoO3 glass-nanocomposite-semiconductor

International Nuclear Information System (INIS)

Bhattacharya, Sanjib; Kundu, Ranadip; Das, Anindya Sundar; Roy, Debasish

2015-01-01

Highlights: • Polaron hopping. • Dc and ac conductivity. • Mott's model and Greave's model. • Ag 2 MoO 4 , Ag 2 Mo 2 O 7 and Ag 6 Mo 10 O 33 nanoparticles and SeO 3 and SeO 4 nanoclusters. • XRD and FESEM studies. - Abstract: A new type of semiconducting glass-nanocomposites 0.3Ag 2 O–0.7 (xMoO 3 –(1 − x) SeO 2 ) is prepared by melt-quenching route. The formation of Ag 2 MoO 4 , Ag 2 Mo 2 O 7 and Ag 6 Mo 10 O 33 nanoparticles and SeO 3 and SeO 4 nanoclusters in glass-nanocomposites has been confirmed from X-ray diffraction (XRD) and field emission scanning electron microscopic (FESEM) studies. Fourier transform infrared (FTIR) spectroscopy is employed to find out Se−O stretching vibration as well as stretching vibrations of Mo 2 O 7 2− ions. The dc conductivity of them is studied on the light of polaron hopping approach in a wide temperature range. At low temperatures, variable range hopping model (Mott's model) is employed to analyze the conductivity data. Greave's model is used to predict temperature dependent variable range hopping in the high temperature region. Frequency dependent ac conductivity is well explained on the basis of tunneling. I–V characteristics of the as-prepared samples have also been investigated

Silver manganese oxide electrodes for lithium batteries

Science.gov (United States)

Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

2006-05-09

This invention relates to electrodes for non-aqueous lithium cells and batteries with silver manganese oxide positive electrodes, denoted AgxMnOy, in which x and y are such that the manganese ions in the charged or partially charged electrodes cells have an average oxidation state greater than 3.5. The silver manganese oxide electrodes optionally contain silver powder and/or silver foil to assist in current collection at the electrodes and to improve the power capability of the cells or batteries. The invention relates also to a method for preparing AgxMnOy electrodes by decomposition of a permanganate salt, such as AgMnO4, or by the decomposition of KMnO4 or LiMnO4 in the presence of a silver salt.

Natural nanostructure and superlattice nanodomains in AgSbTe{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Carlton, Christopher E.; De Armas, Ricardo; Shao-Horn, Yang, E-mail: delaireoa@ornl.gov, E-mail: shaohorn@mit.edu [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Ma, Jie [Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); May, Andrew F.; Delaire, Olivier, E-mail: delaireoa@ornl.gov, E-mail: shaohorn@mit.edu [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2014-04-14

AgSbTe{sub 2} has long been of interest for thermoelectric applications because of its favorable electronic properties and its low lattice thermal conductivity of ∼0.7 W/mK. In this work, we report new findings from a high-resolution transmission electron microscopy study revealing two nanostructures in single crystal Ag{sub 1−x}Sb{sub 1+x}Sb{sub 2+x} (with x = 0, 0.1, 0.2); (i) a rippled natural nanostructure with a period of ∼2.5–5 nm and (ii) superlattice ordered nanodomains consistent with cation ordering predicted in previous density functional theory studies. These nanostructures, combined with point-defects, probably serve as sources of scattering for phonons, thereby yielding a low lattice thermal conductivity over a wide temperature range.

Thermochemical properties of silver tellurides including empressite (AgTe) and phase diagrams for Ag-Te and Ag-Te-O

Science.gov (United States)

Voronin, Mikhail V.; Osadchii, Evgeniy G.; Brichkina, Ekaterina A.

2017-10-01

This study compiles original experimental and literature data on the thermodynamic properties (ΔfG°, S°, ΔfH°) of silver tellurides (α-Ag2Te, β-Ag2Te, Ag1.9Te, Ag5Te3, AgTe) obtained by the method of solid-state galvanic cell with the RbAg4I5 and AgI solid electrolytes. The thermodynamic data for empressite (AgTe, pure fraction from Empress Josephine Mine, Colorado USA) have been obtained for the first time by the electrochemical experiment with the virtual reaction Ag + Te = AgTe. The Ag-Te phase diagrams in the T - x and log fTe2 (gas) - 1/ T coordinates have been refined, and the ternary Ag-Te-O diagrams with Ag-Te-TeO2 (paratellurite) composition range have been calculated.

[Ag(NH3)2]Ag(OsO3N)2: a new nitridoosmate(VIII)

International Nuclear Information System (INIS)

Wickleder, M.S.; Pley, Martin

2004-01-01

Dark brown single crystals of [Ag(NH 3 ) 2 ]Ag(OsO 3 N) 2 were obtained from the reaction of Ag 2 CO 3 , OsO 4 , and NH 3 in aqueous solution. The crystal structure was solved in the monoclinic space group C2/m, with the following unit-cell dimensions: a=1962.5(3), b=633.1(1), c=812.6(1) pm, β=96.71(1) deg. The final reliability factor was R=0.0256 for 1034 reflections with I>2σ(I). Linear [Ag(NH 3 ) 2 ] + ions are present oriented perpendicular to the [010] direction, leading to short Ag + -Ag + distances of 316 pm. A second type of Ag + ions in the crystal structure present coordination number '6+1' and are surrounded by oxygen and nitrogen atoms of the nitridoosmate groups. Within the first of the two crystallographically distinguishable anions one can clearly differentiate between oxygen and nitrogen atoms while the second one exhibits a N/O disorder over two positions. The infrared spectrum of [Ag(NH 3 ) 2 ]Ag(OsO 3 N) 2 shows the typical absorptions which can be attributed to the complex anions and the NH 3 ligands

Structural and Optical Properties of Chemical Bath Deposited Silver Oxide Thin Films: Role of Deposition Time

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A. C. Nwanya

2013-01-01

Full Text Available Silver oxide thin films were deposited on glass substrates at a temperature of 50°C by chemical bath deposition technique under different deposition times using pure AgNO3 precursor and triethanolamine as the complexing agent. The chemical analysis based on EDX technique shows the presence of Ag and O at the appropriate energy levels. The morphological features obtained from SEM showed that the AgxO structures varied as the deposition time changes. The X-ray diffraction showed the peaks of Ag2O and AgO in the structure. The direct band gap and the refractive index increased as the deposition time increased and was in the range of 1.64–1.95 eV and 1.02–2.07, respectively. The values of the band gap and refractive index obtained indicate possible applications in photovoltaic and photothermal systems.

Infrared Spectroscopy and Raman Scattering Studies on the Structure of Ag2O. B2O3. TeO2 Glass

International Nuclear Information System (INIS)

Thazin Myint; Soe Soe Thin; Pho Kaung; Sein Htoon

2006-06-01

Infrared spectroscopy investigation of silver - borate - tellurite glasses in the system 0.4 Ag2 O. 0.6 (x B2 O2. (1-x) TeO2) for various of x (0 < x < 1) has been performed in order to understand the glass modifying properties of the TeO2. In pure crystalline TeO2 spectra observed absorption bands at 780 cm-1 and 660 cm-1 have been ascribed to the stretching vibration of TeO bonds in the TeO4 units. In the glass 0.4 Ag2 O. 0.6 (x B2 O3. (1-x) TeO2) the bands at 700 cm-1 and 694 cm-1 are assigned to the symmetric breathing vibration of the boroxol group and the pentaborate one. The glasses show bands at 630 cm-1 which corresponds to the vibrations due to TeO4 units

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

International Nuclear Information System (INIS)

Yu, Y.

1995-01-01

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

Synergetic effect of Ag_2O as co-catalyst for enhanced photocatalytic degradation of phenol on N-TiO_2

International Nuclear Information System (INIS)

Chu, Haipeng; Liu, Xinjuan; Liu, Junying; Li, Jinliang; Wu, Tianyang; Li, Haokun; Lei, Wenyan; Xu, Yan; Pan, Likun

2016-01-01

Graphical abstract: Ag_2O/N-TiO_2 composites were synthesized via a co-precipitation method for visible light photocatalytic degradation of organic pollutions with excellent photocatalytic activity. - Highlights: • Ag_2O/N-TiO_2 composites were synthesized via a facile precipitation method. • Ag_2O/N-TiO_2 composites exhibited enhanced photocatalytic activity. • Ag_2O acts as co-catalyst to separate the photo-generated electron-hole pairs. - Abstract: A facile precipitation method was developed to synthesize the Ag_2O/N-TiO_2 composites. Their morphology, structure and photocatalytic performance in the degradation of methylene blue (MB) and phenol under visible light irradiation were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, photoluminescence spectroscopy and UV–vis absorption spectroscopy, respectively. The results show that the Ag_2O/N-TiO_2 composites exhibit excellent photocatalytic performance. The maximum degradation rates of MB and phenol are about 8.9 and 2.9 times that of pure N-TiO_2, respectively. The excellent photocatalytic performance is mainly ascribed to the synergetic effects of Ag_2O and N-TiO_2 including the increased light absorption and the reduced electron-hole pair recombination in N-TiO_2 with the presence of Ag_2O.

Effects of coating process on the characteristics of Ag-SnO2 contact materials

International Nuclear Information System (INIS)

Liu, X.M.; Wu, S.L.; Chu, Paul K.; Chung, C.Y.; Zheng, J.; Li, S.L.

2006-01-01

Good wettability between the SnO 2 and silver matrix can improve the electrical contact performance of Ag-SnO 2 materials. In this work, Ag was deposited onto the surface of Ti-doped SnO 2 particles using chemical plating to enhance the wettability. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the Ag-coated SnO 2 particles. Scanning electron microscopy (SEM), conductivity tests, differential thermal analysis (DTA), and thermogravimetric analysis (TGA) were performed on the Ag-SnO 2 materials. Our results reveal that the chemical plating process can enhance the wettability between the Ti-doped SnO 2 particles and Ag matrix, and the Ag-coated SnO 2 particles are uniformly distributed in the Ag matrix. Both the thermal and electrical conductivity of the Ag-SnO 2 materials are significantly improved

Synthesis and properties of new CdSe-AgI-As2Se3 chalcogenide glasses

International Nuclear Information System (INIS)

Kassem, M.; Le Coq, D.; Fourmentin, M.; Hindle, F.; Bokova, M.; Cuisset, A.; Masselin, P.; Bychkov, E.

2011-01-01

Research highlights: → Determination of the glass-forming region in the pseudo-ternary CdSe-AgI-As 2 Se 3 system. → Characterization of macroscopic properties of the new CdSe-AgI-As 2 Se 3 glasses. → Far infrared transmission of chalcogenide glasses. → Characterization of the total conductivity of CdSe-AgI-As 2 Se 3 glasses. -- Abstract: The glass-forming region in the pseudo-ternary CdSe-AgI-As 2 Se 3 system was determined. Measurements including differential scanning calorimetry (DSC), density, and X-ray diffraction were performed. The effect resulting from the addition of CdSe or AgI has been highlighted by examining three series of different base glasses. The characteristic temperatures of the glass samples, including glass transition (T g ), crystallisation (T x ), and melting (T m ) temperatures are reported and used to calculate their ΔT = T x - T g and their Hruby, H r = (T x - T g )/(T m - T x ), criteria. Evolution of the total electrical conductivity σ and the room temperature conductivity σ 298 was also studied. The terahertz transparency domain in the 50-600 cm -1 region was pointed for different chalcogenide glasses (ChGs) and the potential of the THz spectroscopy was suggested to obtain structural information on ChGs.

Enhanced Photocatalytic Properties of Ag-Loaded N-Doped Tio2 Nanotube Arrays

Directory of Open Access Journals (Sweden)

Gao Dawei

2018-03-01

Full Text Available Highly ordered TiO2 nanotube (TiO2 NT arrays were prepared by anodic oxidizing method on the surface of the Ti substrate. Nitrogen-doped TiO2 nanotube (N-TiO2 NT arrays were carried out by ammonia solution immersion, and Ag nanoparticles loaded N-doped TiO2 nanotube (Ag/N-TiO2 NT arrays were obtained by successive ionic layer adsorption and reaction (SILAR technique. The samples were characterized by the X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, field emission scanning electron microscopy (FESEM, high-resolution transmission electron microscopy (HRTEM, photoluminescence (PL emission spectra, ultraviolet–visible (UV–vis diffuse reflectance spectroscopy (DRS. The result indicated that the diameter and wall thickness of the TiO2 NT are 100–120 and 20–30 nm, respectively. Moreover, the morphology and structure of the highly ordered TiO2 NTs were not affected by N-doping. Furthermore, Ag nanoparticles were evenly deposited on the surface of TiO2 NTs in the form of elemental silver. Finally, the photocatalytic activity of Ag/N-TiO2 NTs was evaluated by degradation of methyl orange (MO under visible-light irradiation. The Ag/N-TiO2 NTs exhibited enhanced photocatalytic properties, which could reach 95% after 90-min irradiation.

Selective hydrodechlorination of 1,2-dichloroethane to ethylene over Pd-Ag/Al_2O_3 catalysts prepared by surface reduction

International Nuclear Information System (INIS)

Han, Yuxiang; Gu, Guangfeng; Sun, Jingya; Wang, Wenjuan; Wan, Haiqin; Xu, Zhaoyi; Zheng, Shourong

2015-01-01

Graphical abstract: - Highlights: • Surface reduction method was used for preparation of Pd-Ag(Cu) bimetallic catalysts. • Hydrodechlorination of 1,2-dichloroethane was investigated for production of ethylene. • Ag(Cu) selectively deposited on Pd surface during surface reduction process. • Ethylene selectivity was enhanced over Pd-Ag(Cu)/Al_2O_3 catalyst prepared by surface reduction. • Isolated Pd site is the key species for ethylene selectivity. - Abstract: Alumina supported Pd-Ag and (Cu) bimetallic catalysts (denoted as sr-Pd-Ag/Al_2O_3 or sr-Pd-Cu/Al_2O_3) with varied Pd/Ag (or Cu) ratios were prepared using the surface reduction method, and the gas-phase catalytic hydrodechlorination of 1,2-dichloroethane over the catalysts were investigated. For comparison, Pd-Ag bimetallic catalysts were prepared by the conventional co-impregnation method (denoted as im-Pd-Ag/Al_2O_3). The catalysts were characterized by N_2 adsorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and CO chemisorption. Characterization results indicated that surface reduction led to selective deposition of metallic Ag on the surface of Pd particles, while Pd and Ag just disorderly mixed in the catalyst prepared by impregnation method. Therefore, sr-Pd-Ag/Al_2O_3 exhibited a higher ethylene selectivity than im-Pd-Ag/Al_2O_3 for hydrodechlorination of 1,2-dichloroethane at a similar Ag loading amount. Moreover, among sr-Pd-Ag/Al_2O_3, sr-Pd-Cu/Al_2O_3 and im-Pd-Ag/Al_2O_3 catalysts, the ethylene selectivity decreased over these catalysts following the order: sr-Pd-Ag/Al_2O_3 > sr-Pd-Cu/Al_2O_3 > im-Pd-Ag/Al_2O_3. The present results indicate that surface reduction can be used as a potential method to synthesize catalyst with enhanced ethylene selectivity in hydrodechlorination of 1,2-dichloroethane.

Effects of realgar on GSH synthesis in the mouse hippocampus: Involvement of system X{sub AG}{sup −}, system X{sub C}{sup −}, MRP-1 and Nrf2

Energy Technology Data Exchange (ETDEWEB)

Wang, Yanlei [Department of Health Laboratory Technology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning 110122 (China); School of Basic Medical Sciences, North China University of Science and Technology, 46 Xinhua Road, Tangshan, Hebei 063009 (China); Chen, Mo; Zhang, Yinghua; Huo, Taoguang [Department of Health Laboratory Technology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning 110122 (China); Fang, Ying [Department of Health Laboratory Technology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning 110122 (China); School of Pharmacy, Liaoning University of Traditional Chinese Medicine, No. 77 Shenning1 Road, Double D Port, Dalian, Liaoning 116600 (China); Jiao, Xuexin [Department of Health Laboratory Technology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning 110122 (China); Yuan, Mingmei [Department of Health Laboratory Technology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning 110122 (China); School of Pharmacy, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning 110122 (China); Jiang, Hong, E-mail: jianghong@mail.cmu.edu.cn [Department of Health Laboratory Technology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning 110122 (China)

2016-10-01

Realgar is a type of mineral drug that contains arsenic and has neurotoxicity. Glutathione (GSH), which is the main antioxidant in the central nervous system, plays a key role in antioxidant defenses and the detoxification of arsenic. However, whether realgar interferes with the synthesis of GSH in the brain and the molecular mechanisms underlying its effects are largely unknown. Here, we used mouse models of exposure to realgar to show that realgar affects the synthesis of GSH in the hippocampus, leading to ultrastructural changes in hippocampal neurons and synapses and deficiencies in cognitive abilities, and that the mechanisms that cause this effect may be associated with alterations in the expression of system X{sub AG}{sup −}, system X{sub C}{sup −}, multidrug resistance-associated protein 1(MRP-1), nuclear factor E2-related factor 2 (Nrf2), γ-glutamylcysteine synthetase (γ-GCS), and the levels of glutamate (Glu) and cysteine (Cys) in the extracellular fluid. These findings provide a theoretical basis for preventing the drug-induced chronic arsenic poisoning in the nervous system that is triggered by realgar. - Highlights: • Realgar can induce neurotoxicity. • Realgar can modulate GSH levels in the hippocampus. • The mechanisms rely on expression changes of system X{sub AG}{sup −}, system X{sub C}{sup −}, MRP-1, Nrf2.

Enhanced photodegradation activity of methyl orange over Ag2CrO4/SnS2 composites under visible light irradiation

International Nuclear Information System (INIS)

Luo, Jin; Zhou, Xiaosong; Ma, Lin; Xu, Xuyao; Wu, Jingxia; Liang, Huiping

2016-01-01

Highlights: • Novel visible-light-driven Ag 2 CrO 4 /SnS 2 composites are synthesized. • Ag 2 CrO 4 /SnS 2 exhibits higher photocatalytic activity than pure Ag 2 CrO 4 and SnS 2 . • Ag 2 CrO 4 /SnS 2 exhibits excellent stability for the photodegradation of MO. • The possible photocatalytic mechanism was discussed in detail. - Abstract: Novel Ag 2 CrO 4 /SnS 2 composites were prepared by a simple chemical precipitation method and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. The visible light photocatalytic tests showed that the Ag 2 CrO 4 /SnS 2 composites enhanced photocatalytic activities for the photodegradation of methyl orange (MO) under visible light irradiation (λ > 420 nm), and the optimum rate constant of Ag 2 CrO 4 /SnS 2 at a weight content of 1.0% Ag 2 CrO 4 for the degradation of MO was 2.2 and 1.5 times larger than that of pure Ag 2 CrO 4 and SnS 2 , respectively. The improved activity could be attributed to high separation efficiency of photogenerated electrons-hole pairs on the interface of Ag 2 CrO 4 and SnS 2 , which arised from the synergistic effect between Ag 2 CrO 4 and SnS 2 . Moreover, the possible photocatalytic mechanism with superoxide radical anions and holes species as the main reactive species in photocatalysis process was proposed on the basis of experimental results.

Fabrication, characterization and photocatalytic properties of Ag nanoparticles modified TiO2 NTs

International Nuclear Information System (INIS)

Wang Qingyao; Yang Xiuchun; Liu Dan; Zhao Jianfu

2012-01-01

Graphical abstract: The TiO 2 NTs were first treated with bi-functional mercaptoacetic acid linkers (HOOC–R–S). The –OH group on the surface of TiO 2 NT provides a strong affinity with the carboxylate group in the linker molecules. The thiol functional group in the linker molecules facilitates the binding with Ag from AgNO 3 solution. After Ag + ions were reduced by NaBH 4 , Ag nanoparticles formed by nucleation and growth. Highlights: ► Ag nanoparticles with an average diameter of 9.2 nm were filled in the TiO 2 nanotubes by a successive ionic layer adsorption and reaction (SILAR) technique. ► Bi-functional mercaptoacetic acid linkers were used to bind TiO 2 nanotubes with Ag nanoparticles. ► Ag nanoparticles modification of TiO 2 NTs largely enhanced the photocatalytic degradation of methyl orange under ultraviolet light irradiation. - Abstract: Ordered anatase TiO 2 nanotubes (TiO 2 NTs) on Ti substrate were synthesized by electrochemical anodization and subsequently vapor-thermal treatment. Ag nanoparticles were decorated on TiO 2 NTs by successive ionic layer adsorption and reaction (SILAR) technique. Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the characterization of surface morphology, phase composition, and microstructure of the original TiO 2 NTs, the vapor-thermally treated TiO 2 NTs and the Ag nanoparticles decorated TiO 2 NTs. The results indicate that vapor-thermal treatment favors to the transformation of amorphous TiO 2 into anatase phase. Increasing the SILAR cycle times favors to increase the loaded amounts of Ag nanoparticles in TiO 2 NTs. Ag nanoparticles are uniformly distributed in the TiO 2 NTs, and the SILAR process does not damage the ordered tubular structure. A possible formation mechanism of Ag/TiO 2 NTs has also been proposed. The

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-01-01

Graphical abstract: - Highlights: • The plasmatic Ag@AgBr surface-sensitized Bi{sub 2}WO{sub 6} composite photocatalysts. • Ag@AgBr greatly increased visible-light absorption for Bi{sub 2}WO{sub 6}. • The plasmonic photocatalysts exhibited enhanced activity for the degradation of MB, phenol and salicylic acid. - Abstract: Nano Ag@AgBr decorated on the surface of flower-like Bi{sub 2}WO{sub 6} (hereafter designated Ag@AgBr/Bi{sub 2}WO{sub 6}) were prepared via a facile oil-in-water self-assembly method. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS), etc. The characterization results indicated that nano Ag@AgBr was observed to be evenly dispersed on the surface of Bi{sub 2}WO{sub 6}, and was approximately 20 nm in size. Ag@AgBr/Bi{sub 2}WO{sub 6} composites exhibited excellent UV–vis absorption, due to quantum dimension effect of Ag@AgBr, the surface plasmonic resonance (SPR) of Ag nanoparticles and the special flower-like structure of Bi{sub 2}WO{sub 6}. The photoelectrochemical measurement verified that the suitable band potential of Ag@AgBr and Bi{sub 2}WO{sub 6} and the existence of metal Ag resulted in the high efficiency in charge separation of the composite. The photocatalytic activities of the Ag@AgBr/Bi{sub 2}WO{sub 6} samples were examined under visible-light irradiation for the degradation of methylene blue (MB). The composite presented excellent photocatalytic activity due to the synergetic effect of Bi{sub 2}WO{sub 6}, AgBr, and Ag nanoparticles. The Ag@AgBr(20 wt.%)/Bi{sub 2}WO{sub 6} sample exhibited the best photocatalytic activity, degrading 95.03% MB after irradiation for 2 h, which was respectively 1.29 times and 1.28 times higher than that of Ag@AgBr and Bi{sub 2}WO{sub 6} photocatalyst. Meanwhile, phenol and salicylic acid were degraded to further prove the degradation ability of Ag@AgBr/Bi{sub 2

Optical and structural properties of TiO2/Ti/Ag/TiO2 and TiO2/ITO/Ag/ITO/TiO2 metal-dielectric multilayers by RF magnetron sputtering for display application

International Nuclear Information System (INIS)

Lee, Jang-Hoon; Lee, Seung-Hyu; Hwangbo, Chang-Kwon; Lee, Kwang-Su

2004-01-01

Electromagnetic-interference (EMI) shielding and near-infrared (NIR) cutoff filters for plasma display panels, based on fundamental structures (ITO/Ag/ITO), (TiO 2 /Ti/Ag/TiO 2 ) and (TiO 2 /ITO/Ag/ITO/TiO 2 ), were designed and prepared by RF-magnetron sputtering. The optical, structural and electrical properties of the filters were investigated by using spectrophotometry, Auger electron spectroscopy, X-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, atomic force microscopy and four-point-probe measurements. The results show that ITO films as the barriers and base layers lead to higher transmittance in the visible spectrum and smoother surface roughness than Ti metal barriers, while maintaining high NIR cutoff characteristics and chemical stability, which may be attributed to the lower absorption in the interfacial layers and better protection of the Ag layers by the ITO layers.

Ag2S/CdS/TiO2 Nanotube Array Films with High Photocurrent Density by Spotting Sample Method.

Science.gov (United States)

Sun, Hong; Zhao, Peini; Zhang, Fanjun; Liu, Yuliang; Hao, Jingcheng

2015-12-01

Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor-Ag2S (0.9 eV) quantum dots (QDs)-in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs fabricated by uniformly depositing the QDs into the TNTs via the successive ionic layer adsorption and reaction (SILAR) method were synthesized, respectively. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) results demonstrated that the Ag2S/CdS/TNTs prepared by SSM and other films were successfully prepared. In comparison with the four films of TNTs, CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs by SILAR, the Ag2S/CdS/TNTs prepared by SSM showed much better absorption capability and the highest photocurrent density in UV-vis range (320~800 nm). The cycles of local deposition have great influence on their photoelectric properties. The photocurrent density of Ag2S/CdS/TNTs by SSM with optimum deposition cycles of 6 was about 37 times that of TNTs without modification, demonstrating their great prospective applications in solar energy utilization fields.

Facile synthesis, structure, and properties of Ag{sub 2}S/Ag heteronanostructure

Energy Technology Data Exchange (ETDEWEB)

Sadovnikov, S. I., E-mail: sadovnikov@ihim.uran.ru; Gusev, A. I. [Ural Branch of the Russian Academy of Sciences, Institute of Solid State Chemistry (Russian Federation)

2016-09-15

Ag{sub 2}S/Ag heteronanostructure has been produced by a simple one-stage chemical deposition from aqueous solutions of silver nitrate, sodium sulfide, and sodium citrate with the use of monochromatic light irradiation. For simultaneous synthesis of Ag{sub 2}S and Ag nanoparticles, deposition has been performed from reaction mixtures with reduced sodium sulfide concentration. The size of Ag{sub 2}S and Ag nanoparticles is 45–50 and 15–20 nm, respectively. It is established that in the contact layer between silver sulfide and silver, nonconducting α-Ag{sub 2}S acanthite transforms into superionic β-Ag{sub 2}S argentite under the action of external electric field. The scheme of the operation of a resistive switch based on an Ag{sub 2}S/Ag heteronanostructure is proposed. The UV–Vis optical absorption spectra of colloidal solutions of Ag{sub 2}S/Ag heteronanostructures have been studied.Graphical Abstract.

Continuous Synthesis of Ag/TiO2 Nanoparticles with Enhanced Photocatalytic Activity by Pulsed Laser Ablation

Directory of Open Access Journals (Sweden)

Rui Zhou

2017-01-01

Full Text Available A facile and environmental friendly synthesis strategy based on pulsed laser ablation has been developed for potential mass production of Ag-loaded TiO2 (Ag/TiO2 nanoparticles. By sequentially irradiating titanium and silver target substrates, respectively, with the same 1064 nm 100 ns fiber laser, Ag/TiO2 particles can be fabricated. A postannealing process leads to the crystallization of TiO2 to anatase phase with high photocatalytic activity. The phase composition, microstructure, and surface state of the elaborated Ag/TiO2 are characterized by X-ray diffraction (XRD, energy dispersive X-ray (EDX, field emission scanning electron microscope (FESEM, transmission electron microscope (TEM, and X-ray photoelectron spectroscopy (XPS techniques. The results suggest that the presence of silver clusters deposited on the surface of TiO2 nanoparticles. The nanostructure is formed through laser interaction with materials. Photocatalytic activity evaluation shows that silver clusters could significantly enhance the photocatalytic activity of TiO2 in degradation of methylene blue (MB under UV light irradiation, which is attributed to the efficient electron traps by Ag clusters. Our developed Ag/TiO2 nanoparticles synthesized via a straightforward, continuous, and green pathway could have great potential applications in photocatalysis.

Ag-Modified In2O3 Nanoparticles for Highly Sensitive and Selective Ethanol Alarming

Directory of Open Access Journals (Sweden)

Jinxiao Wang

2017-09-01

Full Text Available Pure In2O3 nanoparticles are prepared by a facile precipitation method and are further modified by Ag. The synthesized samples are characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Raman and UV-Vis spectra. The results show the successful heterojunction formation between Ag and In2O3. Gas sensing property measurements show that the 5 mol % Ag-modified In2O3 sensor has the response of 67 to 50 ppm ethanol, and fast response and recovery time of 22.3 and 11.7 s. The response is over one magnitude higher than that of pure In2O3, which can be attributed to the enhanced catalytic activity of Ag-modified In2O3 as compared with the pure one. The mechanism of the gas sensor can be explained by the spillover effect of Ag, which enhances the oxygen adsorption onto the surface of In2O3 and thus give rise to the higher activity and larger surface barrier height.

Photocatalytic properties of porous TiO2/Ag thin films

International Nuclear Information System (INIS)

Chang, C.-C.; Chen, J.-Y.; Hsu, T.-L.; Lin, C.-K.; Chan, C.-C.

2008-01-01

In this study, nanocrystalline TiO 2 /Ag composite thin films were prepared by a sol-gel spin-coating technique. By introducing polystyrene (PS) spheres into the precursor solution, porous TiO 2 /Ag thin films were prepared after calcination at a temperature of 500 deg. C for 4 h. Three different sizes (50, 200, and 400 nm) of PS spheres were used to prepare porous TiO 2 films. The as-prepared TiO 2 and TiO 2 /Ag thin films were characterized by X-ray diffractometry (XRD) and by scanning electron microscopy to reveal structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation. When PS spheres of different sizes were introduced after calcination, the as-prepared TiO 2 films exhibited different porous structures. XRD results showed that all TiO 2 /Ag films exhibited a major anatase phase. The photodegradation of porous TiO 2 thin films prepared with 200 nm PS spheres and doped with 1 mol% Ag exhibited the best photocatalytic efficiency where ∼ 100% methylene blue was decomposed within 8 h under UV exposure

Oligodeoxynucleotides containing 2'-amino-LNA nucleotides as constrained morpholino phosphoramidate and phosphorodiamidate monomers

DEFF Research Database (Denmark)

Kristensen, Kim Vejlegaard; Paul, Sibasish; Kosbar, Tamer

2017-01-01

Incorporation in a 2'→5' direction of a phosphorodiamidite 2'-amino-LNA-T nucleotide as the morpholino phosphoramidate and N,N-dimethylamino phosphorodiamidate monomers into six oligonucleotides is reported. Thermal denaturation studies showed that the novel 2'-amino-LNA-based morpholino monomers...

Synthesis of Ag-TiO2 composite nano thin film for antimicrobial application

Science.gov (United States)

Yu, Binyu; Leung, Kar Man; Guo, Qiuquan; Lau, Woon Ming; Yang, Jun

2011-03-01

TiO2 photocatalysts have been found to kill cancer cells, bacteria and viruses under mild UV illumination, which offers numerous potential applications. On the other hand, Ag has long been proved as a good antibacterial material as well. The advantage of Ag-TiO2 nanocomposite is to expand the nanomaterial's antibacterial function to a broader range of working conditions. In this study neat TiO2 and Ag-TiO2 composite nanofilms were successfully prepared on silicon wafer via the sol-gel method by the spin-coating technique. The as-prepared composite Ag-TiO2 and TiO2 films with different silver content were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) to determine the topologies, microstructures and chemical compositions, respectively. It was found that the silver nanoparticles were uniformly distributed and strongly attached to the mesoporous TiO2 matrix. The morphology of the composite film could be controlled by simply tuning the molar ratio of the silver nitrate aqueous solution. XPS results confirmed that the Ag was in the Ag0 state. The antimicrobial effect of the synthesized nanofilms was carried out against gram-negative bacteria (Escherichia coli ATCC 29425) by using an 8 W UV lamp with a constant relative intensity of 0.6 mW cm - 2 and in the dark respectively. The synthesized Ag-TiO2 thin films showed enhanced bactericidal activities compared to the neat TiO2 nanofilm both in the dark and under UV illumination.

Synthesis of Ag-TiO2 composite nano thin film for antimicrobial application

International Nuclear Information System (INIS)

Yu Binyu; Guo Qiuquan; Yang Jun; Leung, Kar Man; Lau, Woon Ming

2011-01-01

TiO 2 photocatalysts have been found to kill cancer cells, bacteria and viruses under mild UV illumination, which offers numerous potential applications. On the other hand, Ag has long been proved as a good antibacterial material as well. The advantage of Ag-TiO 2 nanocomposite is to expand the nanomaterial's antibacterial function to a broader range of working conditions. In this study neat TiO 2 and Ag-TiO 2 composite nanofilms were successfully prepared on silicon wafer via the sol-gel method by the spin-coating technique. The as-prepared composite Ag-TiO 2 and TiO 2 films with different silver content were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) to determine the topologies, microstructures and chemical compositions, respectively. It was found that the silver nanoparticles were uniformly distributed and strongly attached to the mesoporous TiO 2 matrix. The morphology of the composite film could be controlled by simply tuning the molar ratio of the silver nitrate aqueous solution. XPS results confirmed that the Ag was in the Ag 0 state. The antimicrobial effect of the synthesized nanofilms was carried out against gram-negative bacteria (Escherichia coli ATCC 29425) by using an 8 W UV lamp with a constant relative intensity of 0.6 mW cm -2 and in the dark respectively. The synthesized Ag-TiO 2 thin films showed enhanced bactericidal activities compared to the neat TiO 2 nanofilm both in the dark and under UV illumination.

Quantum Dot Sensitized Solar Cells Based on TiO2/AgInS2

Science.gov (United States)

Pawar, Sachin A.; Jeong, Jae Pil; Patil, Dipali S.; More, Vivek M.; Lee, Rochelle S.; Shin, Jae Cheol; Choi, Won Jun

2018-05-01

Quantum dot heterojunctions with type-II band alignment can efficiently separate photogenerated electron-hole pairs and, hence, are useful for solar cell studies. In this study, a quantum dot sensitized solar cell (QDSSC) made of TiO2/AgInS2 is achieved to boost the photoconversion efficiency for the TiO2-based system by varying the AgInS2 layer's thickness. The TiO2 nanorods array film is prepared by using a simple hydrothermal technique. The formation of a AgInS2 QD-sensitized TiO2-nanorod photoelectrode is carried out by successive ionic layer adsorption and reaction (SILAR) technique. The effect of the QD layer on the performance of the solar cell is studied by varying the SILAR cycles of the QD coating. The synthesized electrode materials are characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy and solar cell performances. The results indicate that the nanocrystals have effectively covered the outer surfaces of the TiO2 nanorods. The interfacial structure of quantum dots (QDs)/TiO2 is also investigated, and the growth interface is verified. A careful comparison between TiO2/AgInS2 sensitized cells reveals that the trasfer of electrons and hole proceeds efficiently, the recombination is suppressed for the optimum thickness of the QD layer and light from the entire visible spectrum is utilised. Under AM 1.5G illumination, a high photocurrent of 1.36 mAcm-2 with an improved power conversion efficiency of 0.48% is obtained. The solar cell properties of our photoanodes suggest that the TiO2 nanorod array films co-sensitized by AgInS2 nanoclusters have potential applications in solar cells.

Critical current anisotropy in Ag/(Pb,Bi){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} multifilamentary tapes: influence of self-magnetic field

Energy Technology Data Exchange (ETDEWEB)

Majoros, M [IRC in Superconductivity, University of Cambridge, Cambridge (United Kingdom); Institute of Electrical Engineering, Slovak Academy of Sciences, Bratislava (Slovakia); Glowacki, B A [IRC in Superconductivity, University of Cambridge, Cambridge (United Kingdom); Department of Materials Science and Metallurgy, University of Cambridge, Cambridge (United Kingdom); Campbell, A M [IRC in Superconductivity, University of Cambridge, Cambridge (United Kingdom)

2001-06-01

Two factors affect critical current anisotropy in multifilamentary Ag/(Pb,Bi){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} tapes - the intrinsic material anisotropy and the geometry. Experimental results on the magnetic field dependence and anisotropy of the critical current in a multifilamentary Ag/(Pb,Bi){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} tape after correction for self-magnetic field effects were found to fit the anisotropic Kim relation. Based on this relation a finite-element-method numerical code for solving the nonlinear Poisson equation for vector magnetic potential was adopted. It allowed the experimental data to be reproduced by back calculation and made possible the study of the interplay of self and external magnetic fields in different cases with well defined physical parameters of the material. The model was used to analyse the distribution of the critical current in individual filaments as well as to evaluate the influence of their geometrical arrangements on the critical current of the tape. The self-field critical current of an individual filament 'extracted' from the tape was compared with the critical current of the overall tape. The effect of the self-magnetic field on critical current distribution obtained by the cutting method was determined. The critical currents of the tapes with different cross sections were calculated and compared with experiments and the influence of the self-field was analysed. The anisotropic properties of a low anisotropy architecture of a multifilamentary Ag/(Pb,Bi){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} conductor were studied. The dependence of critical currents (normalized to self-field critical currents) on external magnetic field corrected for the self-field was found to follow nearly the same curves as those for tapes with different critical current densities (in the range 20-70 kA cm{sup -2} in a self-field), which makes the numerical model applicable to different tapes. (author)

Ag K- and L3-edge XAFS study on Ag species in Ag/Ga2O3 photocatalysts

International Nuclear Information System (INIS)

Yamamoto, M; Yamamoto, N; Yoshida, T; Nomoto, T; Yamamoto, A; Yoshida, H; Yagi, S

2016-01-01

Ag loaded Ga 2 O 3 (Ag/Ga 2 O 3 ) shows photocatalytic activity for reduction of CO 2 with water. Ag L 3 -edge XANES and K-edge EXAFS spectra were measured for various Ag/Ga 2 O 3 samples, which suggested that structural and chemical states of Ag species varied with the loading amount of Ag and the preparation method. The Ag species were metallic Ag particles with an AgGaO 2 -like interface structure in the sample with high loading amount of Ag while predominantly Ag metal clusters in the sample with low loading amount of Ag. The XANES feature just above the edge represented the interaction between the Ag species and the Ga 2 O 3 surface, showing that the Ag metal clusters had more electrons in the d -orbitals by interacting with the Ga 2 O 3 surface, which would contribute the high photocatalytic activity. (paper)

Thermoelectric properties of p-type Ag{sub 1−x}(Pb{sub 1−y}Sn{sub y}){sub m}Sb{sub 1−z}Te{sub m+2}

Energy Technology Data Exchange (ETDEWEB)

Ahn, Kyunghan [Department of Chemistry, Northwestern University, Evanston, IL 60208 (United States); Center for Nanoparticle Research, Institute for Basic Science, (IBS), Seoul 151-742 (Korea, Republic of); Kong, Huijun; Uher, Ctirad [Department of Physics, University of Michigan, Ann Arbor, MI 48109 (United States); Kanatzidis, Mercouri G., E-mail: m-kanatzidis@northwestern.edu [Department of Chemistry, Northwestern University, Evanston, IL 60208 (United States)

2016-10-15

The thermoelectric properties of Ag{sub 1−x}(Pb{sub 1−y}Sn{sub y}){sub m}Sb{sub 1−z}Te{sub m+2} (4≤m≤16, −0.1≤x≤0.3, 1/3≤y≤2/3, 0.2≤z≤0.4; Lead Antimony Silver Tellurium Tin, LASTT-m) compositions were investigated in the temperature range of 300 to ~670 K. All samples crystallize in the average NaCl-type structure without any noticeable second phase and exhibit very narrow bandgaps of <0.1 eV. We studied a range of m values, silver concentrations (x), Pb/Sn ratios (y), and antimony concentrations (z) to determine their effects on the thermoelectric properties. The samples were investigated as melt grown polycrystalline ingots. Varying the Ag contents, the Pb/Sn ratios, and the Sb contents off-stoichiometry allowed us to control the electrical conductivity, the Seebeck coefficient, and the thermal conductivity. The electrical conductivity tends to decrease with decreasing m values. The highest ZT of ~1.1 was achieved at ~660 K for Ag{sub 0.9}Pb{sub 5}Sn{sub 5}Sb{sub 0.8}Te{sub 12} mainly due to the very low lattice thermal conductivity of ~0.4 W/(m K) around 660 K. Also, samples with charge-balanced stoichiometries, Ag(Pb{sub 1−y}Sn{sub y}){sub m}SbTe{sub m+2}, were studied and found to exhibit a lower power factor and higher lattice thermal conductivity than the Ag{sub 1−x}(Pb{sub 1−y}Sn{sub y}){sub m}Sb{sub 1−z}Te{sub m+2} compositions. - Graphical abstract: The Ag{sub 1−x}(Pb{sub 1−y}Sn{sub y}){sub m}Sb{sub 1−z}Te{sub m+2} system defines a complex and flexible class of tunable thermoelectric class of materials with high performance.

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-08-30

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

The composite structure of mixed τ-(Ag, Cu)xV2O5 bronzes—Evidence for T dependant guest-species ordering and mobility

Science.gov (United States)

Hermes, Wilfred; Dollé, Mickaël; Rozier, Patrick; Lidin, Sven

2013-03-01

The complex structural behavior of τ-[AgCu]˜0.92V4O10 has been elucidated by single crystal X-ray diffraction and thermal analysis. The τ-phase region is apparently composed of several distinct phases and this study identifies at least three: τ1rt, τ2rt and τlt. τ1rt and τ2rt have slightly different compositions and crystal habits. Both phases transform to τlt at low temperature. The room temperature modification τ1rt crystallizes in an incommensurately modulated structure with monoclinic symmetry C2(0β1/2) [equivalent to no 5.4, B2(01/2γ) in the Intnl. Tables for Crystallography, Volume C] and the cell parameters a=11.757(4) Å, b=3.6942(5) Å c=9.463(2) Å β=114.62(2)° and the q-vector (0 0.92 1/2), but it is more convenient to transform this to a setting with a non-standard centering X=(1/2 1/2 0 0; 0 0 1/2 1/2; 1/2 1/2 1/2 1/2;) and an axial q vector (0 0.92 0). The structure features a vanadate host lattice with Cu and Ag guests forming an incommensurate composite. The structural data indicates perfect Ag/Cu ordering. At low temperature this modification is replaced by a triclinic phase characterized by two independent q-vectors. The τ2rt phase is similar to the low temperature modification τlt but the satellite reflections are generally more diffuse.

Photocatalytic properties of nanocrystalline TiO2 thin film with Ag additions

International Nuclear Information System (INIS)

Chang, C.-C.; Lin, C.-K.; Chan, C.-C.; Hsu, C.-S.; Chen, C.-Y.

2006-01-01

In the present study, nanocrystalline TiO 2 /Ag composite thin films were prepared by a sol-gel spin coating technique. While, by introducing polystyrene (PS) microspheres, porous TiO 2 /Ag films were obtained after calcining at a temperature of 500 o C. The as-prepared TiO 2 and TiO 2 /Ag thin films were characterized by X-ray diffractometry, and scanning electron microscopy to reveal the structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation. After 500 o C calcination, the microstructure of PS-TiO 2 film without Ag addition exhibited a sponge-like microstructure while significant sintering effect was noticed with Ag additions and the films exhibited a porous microstructure. Meanwhile, coalescence of nanocrystalline anatase-phase TiO 2 can be observed with respect to the sharpening of XRD diffraction peaks. The photodegradation of porous TiO 2 doped with 1 mol% Ag exhibited the best photocatalytic efficiency where 72% methylene blue can be decomposed after UV exposure for 12 h

The negative temperature coefficient resistivities of Ag2S-Ag core–shell structures

International Nuclear Information System (INIS)

Yu, Mingming; Liu, Dongzhi; Li, Wei; Zhou, Xueqin

2014-01-01

In this paper, the conductivity of silver nanoparticle films protected by 3-mercaptopropionic acid (Ag/MPA) has been investigated. When the nanoparticles were annealed in air at 200 °C, they converted to stable Ag 2 S-Ag core–shell structures. The mechanism for the formation of the Ag 2 S-Ag core–shell structures along with the compositional changes and the microstructural evolution of the Ag/MPA nanoparticles during the annealing process are discussed. It is proposed that the Ag 2 S-Ag core–shell structure was formed through a solid-state reduction reaction, in which the Ag + ions coming from Ag 2 S were reduced by sulfonate species and sulfur ions. The final Ag 2 S-Ag films display an exponentially decreased resistivity with increasing temperature from 25 to 170 °C. The negative temperature coefficient resistivity of Ag 2 S-Ag films can be adjusted by changing the S/Ag molar ratio used for the synthesis of the Ag/MPA nanoparticles, paving the way for the preparation of negative temperature-coefficient thermistors via printing technology for use in the electronics.

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

Directory of Open Access Journals (Sweden)

Díez, J. C.

2008-06-01

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

Analysis of nanostructuring in high figure-of-merit Ag{sub 1-x}Pb{sub m}SbTe{sub 2+m} thermoelectric materials

Energy Technology Data Exchange (ETDEWEB)

Cook, Bruce A; Harringa, Joel L [Materials and Engineering Physics Program, Ames Laboratory, Iowa State University Ames, IA (United States); Kramer, Matthew J [Materials Science and Engineering, Iowa State University Ames, IA (United States); Han, Mi-Kyung [Department of Chemistry, Northwestern University Evanston, IL (United States); Chung, Duck-Young [Material Science Division, Argonne National Laboratory, IL (United States); Kanatzidis, Mercouri G [Department of Chemistry, Northwestern University Evanston, IL (United States); Material Science Division, Argonne National Laboratory, IL (United States)

2009-04-23

Thermoelectric materials based on quaternary compounds Ag{sub 1-x}Pb{sub m}SbTe{sub 2+m} exhibit high dimensionless figure-of-merit values, ranging from 1.5 to 1.7 at 700 K. The primary factor contributing to the high figure of merit is a low lattice thermal conductivity, achieved through nanostructuring during melt solidification. As a consequence of nucleation and growth of a second phase, coherent nanoscale inclusions form throughout the material, which are believed to result in scattering of acoustic phonons while causing only minimal scattering of charge carriers. Here, characterization of the nanosized inclusions in Ag{sub 0.53}Pb{sub 18}Sb{sub 1.2}Te{sub 20} that shows a strong tendency for crystallographic orientation along the {l_brace}001{r_brace} planes, with a high degree of lattice strain at the interface, consistent with a coherent interfacial boundary is reported. The inclusions are enriched in Ag relative to the matrix, and seem to adopt a cubic, 96 atom per unit cell Ag{sub 2}Te phase based on the Ti{sub 2}Ni type structure. In-situ high-temperature synchrotron radiation diffraction studies indicated that the inclusions remain thermally stable to at least 800 K. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Battery Relevant Electrochemistry of Ag7Fe3(P2O7)4 : Contrasting Contributions from the Redox Chemistries of Ag+ and Fe3+

International Nuclear Information System (INIS)

Zhang, Yiman; Marschilok, Amy C.; Stony Brook University, NY; Takeuchi, Esther S.

2016-01-01

Ag 7 Fe 3 (P 2 O 7 ) 4 is an example of an electrochemical displacement material which contains two different electrochemically active metal cations, where one cation (Ag + ) forms metallic silver nanoparticles external to the crystals of Ag 7 Fe 3 (P 2 O 7 ) 4 via an electrochemical reduction displacement reaction, while the other cation (Fe +3 ) is electrochemically reduced with the retention of iron cations within the anion structural framework concomitant with lithium insertion. These contrasting redox chemistries within one pure cathode material enable high rate capability and reversibility when Ag 7 Fe 3 (P 2 O 7 ) 4 is employed as cathode material in a lithium ion battery (LIB). Further, pyrophosphate materials are thermally and electrically stable, desirable attributes for cathode materials in LIBs. In this article, a bimetallic pyrophosphate material Ag 7 Fe 3 (P 2 O 7 ) 4 is synthesized and confirmed to be a single phase by Rietveld refinement. Electrochemistry of Ag 7 Fe 3 (P 2 O 7 ) 4 is reported for the first time in the context of lithium based batteries using cyclic voltammetry and galvanostatic discharge–charge cycling. The reduction displacement reaction and the lithium (de)insertion processes are investigated using ex situ X-ray absorption spectroscopy and X-ray diffraction of electrochemically reduced and oxidized Ag 7 Fe 3 (P 2 O 7 ) 4 . Ag 7 Fe 3 (P 2 O 7 ) 4 exhibits good reversibility at the iron centers indicated by ~80% capacity retention over 100 cycles following the initial formation cycle and excellent rate capability exhibited by ~70% capacity retention upon a 4-fold increase in current.

Rapid Synthesis of Highly Monodisperse Au x Ag 1− x Alloy Nanoparticles via a Half-Seeding Approach

KAUST Repository

Chng, Ting Ting

2011-05-03

Gold-silver alloy AuxAg1-x is an important class of functional materials promising new applications across a wide array of technological fields. In this paper, we report a fast and facile synthetic protocol for preparation of highly monodisperse AuxAg1-x alloy nanoparticles in the size range of 3-6 nm. The precursors employed in this work are M(I)-alkanethiolates (M = Au and Ag), which can be easily prepared by mixing common chemicals such as HAuCl4 or AgNO3 with alkanethiols at room temperature. In this half-seeding approach, one of the M(I)-alkanethiolates is first heated and reduced in oleylamine solvent, and freshly formed metal clusters will then act as premature seeds on which both the first and second metals (from M(I)-alkanethiolates, M = Au and Ag) can grow accordingly without additional nucleation and thus achieve high monodispersity for product alloy nanoparticles. Unlike in other prevailing methods, both Au and Ag elements present in these solid precursors are in the same monovalent state and have identical supramolecular structures, which may lead to a more homogeneous reduction and complete interdiffusion at elevated reaction temperatures. When the M(I)-alkanethiolates are reduced to metallic forms, the detached alkanethiolate ligands will serve as capping agent to control the growth. More importantly, composition, particle size, and optical properties of AuxAg1-x alloy nanoparticles can be conveniently tuned with this approach. The optical limiting properties of the prepared particles have also been investigated at 532 and 1064 nm using 7 ns laser pulses, which reveals that the as-prepared alloy nanoparticles exhibit outstanding broadband optical limiting properties with low thresholds. © 2011 American Chemical Society.

Precipitation of Ag{sub 2}Te in the thermoelectric material AgSbTe{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Sugar, Joshua D. [Materials Physics Department, Sandia National Laboratories, Livermore, CA (United States)], E-mail: jdsugar@sandia.gov; Medlin, Douglas L. [Materials Physics Department, Sandia National Laboratories, Livermore, CA (United States)

2009-06-10

The microstructure of AgSbTe{sub 2}, prepared by solidification, is investigated using electron microscopy. During solidification and thermal treatment, the material separates into a two-phase mixture of a rocksalt phase, which is Ag{sub 22}Sb{sub 28}Te{sub 50}, and silver telluride, Ag{sub 2}Te. Ag{sub 2}Te formation results either from eutectic solidification (large lamellar structures), or by solid-state precipitation (fine-scale particles). The crystal structure of the AgSbTe{sub 2} phase determined by electron diffraction is consistent with a rocksalt structure that has a disordered cation sublattice. A preferred crystallographic orientation relationship at the interface between the matrix and the low-temperature monoclinic Ag{sub 2}Te phase is defined and discussed. This orientation relationship is observed for both second-phase morphologies. In both cases, the orientation relationship originates from a topotactic (cube-on-cube) alignment of the Te sublattices in the initially cubic Ag{sub 2}Te and the matrix at elevated temperature. This Te sublattice alignment is retained as the Ag{sub 2}Te undergoes a cubic-to-monoclinic transformation during cooling. This orientation relationship is observed for both second-phase morphologies.

Synthesis and characterization of Ag doped TiO{sub 2} heterojunction films and their photocatalytic performances

Energy Technology Data Exchange (ETDEWEB)

Demirci, Selim, E-mail: selim.demirci@marmara.edu.tr [Marmara University, Department of Metallurgical and Materials Engineering, Kadiköy, 34722 Istanbul (Turkey); Dikici, Tuncay [Izmir Katip Celebi University, Department of Materials Science and Engineering, Cigli, 35620 Izmir (Turkey); Yurddaskal, Metin [Department of Metallurgical and Materials Engineering, Dokuz Eylul University, 35390 Izmir (Turkey); Center for Fabrication and Application of Electronic Materials, Dokuz Eylul University, 35390 Izmir (Turkey); Gultekin, Serdar [Department of Nanoscience and Nanoengineering, Dokuz Eylul University, 35390 İzmir (Turkey); Experimental Science Applications and Research Center, Celal Bayar University, 45140 Manisa (Turkey); Toparli, Mustafa; Celik, Erdal [Department of Metallurgical and Materials Engineering, Dokuz Eylul University, 35390 Izmir (Turkey); Department of Nanoscience and Nanoengineering, Dokuz Eylul University, 35390 İzmir (Turkey); Center for Fabrication and Application of Electronic Materials, Dokuz Eylul University, 35390 Izmir (Turkey)

2016-12-30

Highlights: • Ag doped TiO{sub 2} films were successfully synthesized by sol–gel spin coating method. • Ag in TiO{sub 2} lattice enters in intermediate states to decrease TiO{sub 2} bandgap energy. • Ag dopants increase the photoactivity and superhydrophilicity. • The degradation kinetics of methylene blue was studied. • The 0.7 mol% of Ag was found to be the optimum concentration. - Abstract: In this study, undoped and silver (Ag) doped titanium dioxide (TiO{sub 2}) films were successfully synthesized by sol-gel spin coating technique on the Si substrates. Photocatalytic activities of the TiO{sub 2} films with different Ag content were investigated for the degradation of methylene blue (MB) under UV light irradiation. The crystal phase structure, surface morphology, chemical and optical properties of Ag-doped TiO{sub 2} films were characterized using an X-ray diffractometer (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis spectrophotometer, and FTIR spectrophotometer. The results showed that the Ag-doped TiO{sub 2} films calcined at 500 °C had the crystalline anatase phases and the surface morphologies with some cracks. Ag substitution into TiO{sub 2} matrix enhanced the photocatalytic activity of TiO{sub 2} films under UV light irradiation as compared to the undoped TiO{sub 2} film. Furthermore, the results indicated that the 0.7% Ag doped TiO{sub 2} film exhibited a superior photocatalytic activity than that of undoped and other Ag-doped TiO{sub 2} films. This study demonstrated the potential of an application of Ag doped films to efficiently treat dissolved organic contaminants in water.

Photoreduction of Ag{sup +} in Ag/Ag{sub 2}S/Au memristor

Energy Technology Data Exchange (ETDEWEB)

Mou, N.I.; Tabib-Azar, M., E-mail: azar.m@utah.edu

2015-06-15

Highlights: • The effect of illumination on the operating voltages and switching speed of Ag/Ag{sub 2}S/Au memristors is studied • Illumination decreased the average switching time from high to low resistance states by ∼19% and decreased the turn-off voltages dramatically from −0.8 V to −0.25 V. • Photo-induced reduction of silver in Ag{sub 2}S may be used in three dimensional optical memories that can be electronically read and reset. • Illumination changed sulfur's valency and modified its oxidation/reduction potential. - Abstract: Silver halides and chalcogenides are excellent memristor materials that have been extensively used in the past as photosensitive layers in photography. Here we examine the effect of illumination on the operating voltages and switching speed of Ag/Ag{sub 2}S/Au memristors using a green laser (473–523 nm). Our results indicate that illumination decreases the average switching time from high to low resistance states by ∼19% and decreases the turn-off voltages dramatically from −0.8 V to −0.25 V that we attribute to the change in sulfur valency and a photo-induced change in its oxidation/reduction potential. Photo-induced reduction of silver in Ag{sub 2}S may be used in three dimensional optical memories that can be electronically read and reset.

Synthesis and Characterization of Highly Sensitive Hydrogen (H2 Sensing Device Based on Ag Doped SnO2 Nanospheres

Directory of Open Access Journals (Sweden)

Zhaorui Lu

2018-03-01

Full Text Available In this paper, pure and Ag-doped SnO2 nanospheres were synthesized by hydrothermal method and characterized via X-ray powder diffraction (XRD, field emission scanning electron microscopy (FESEM, energy dispersive spectroscopy (EDS, and X-ray photoelectron spectra (XPS, respectively. The gas sensing performance of the pure, 1 at.%, 3 at.%, and 5 at.% Ag-doped SnO2 sensing devices toward hydrogen (H2 were systematically evaluated. The results indicated that compared with pure SnO2 nanospheres, Ag-doped SnO2 nanospheres could not only decrease the optimum working temperature but also significantly improve H2 sensing such as higher gas response and faster response-recovery. Among all the samples, the 3 at.% Ag-doped SnO2 showed the highest response 39 to 100 μL/L H2 at 300 °C. Moreover, its gas sensing mechanism was discussed, and the results will provide reference and theoretical guidance for the development of high-performance SnO2-based H2 sensing devices.

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

International Nuclear Information System (INIS)

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

1990-01-01

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

In situ x-ray diffraction study on AgI nanowire arrays

International Nuclear Information System (INIS)

Wang Yinhai; Ye Changhui; Wang Guozhong; Zhang Lide; Liu Yanmei; Zhao Zhongyan

2003-01-01

The AgI nanowire arrays were prepared in the ordered porous alumina membrane by an electrochemical method. Transmission electron microscopy observation shows that the AgI nanowires are located in the channels of the alumina membrane. In situ x-ray diffractions show that the nanowire arrays possess hexagonal close-packed structure (β-AgI) at 293 K, orienting along the (002) plane, whereas at 473 K, the nanowire arrays possess a body-centered cubic structure (α-AgI), orienting along the (110) plane. The AgI nanowire arrays exhibit a negative thermal expansion property from 293 to 433 K, and a higher transition temperature from the β to α phase. We ascribe the negative thermal expansion behavior to the phase transition from the β to α phase, and the elevated transition temperature to the radial restriction by the channels of alumina membrane

Fabrication of TiO{sub 2}/Ag{sub 2}O heterostructure with enhanced photocatalytic and antibacterial activities under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Liu, Bingkun, E-mail: liubk2015@zzuli.edu.cn [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Mu, Lilong; Han, Bing [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Zhang, Jingtao [School of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Shi, Hengzhen, E-mail: shihz@zzuli.edu.cn [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China)

2017-02-28

Highlights: • TiO{sub 2}/Ag{sub 2}O composite photocatalyst was synthesized successfully. • The composites show better photocatalytic activity for MB under visible light. • The composites also possess good antibacterial properties. • The mechanism of enhanced photocatalytic activities was investigated. - Abstract: TiO{sub 2}/Ag{sub 2}O heterostructure prepared by a facile in situ precipitation route was used as an effective visible light-driven photocatalyst for degradation of methylene blue (MB) and inactivation of E. coli. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed that Ag{sub 2}O nanoparticles were well distributed on the surface of TiO{sub 2} microspheres. The TiO{sub 2}/Ag{sub 2}O composite with optimal mass ratio of TiO{sub 2} and Ag{sub 2}O displayed extremely good photodegradation ability and antibacterial capability under visible light irradiation, which was mainly ascribed to the synergistic effect between Ag{sub 2}O and TiO{sub 2,} including highly dispersed smaller Ag{sub 2}O particles, increased visible light absorption and efficient separation of photo-induced charge carriers. Meanwhile, the roles of the radical species in the photocatalysis process were investigated. Our results showed that the TiO{sub 2}/Ag{sub 2}O could be used as a dual functional material in water treatment of removing the organic pollutant and killing the bacterium at the same time.

Particle growth mechanisms in Ag-ZrO2 and Au-ZrO2 granular films obtained by pulsed laser deposition

International Nuclear Information System (INIS)

Konstantinovic, Zorica; Muro, Montserrat Garcia del; Varela, Manuel; Batlle, Xavier; Labarta, AmIlcar

2006-01-01

Thin films consisting of Ag and Au nanoparticles embedded in amorphous ZrO 2 matrix were grown by pulsed laser deposition in a wide range of metal volume concentrations in the dielectric regime (0.08 Ag Au c (Ag)∼0.28 and x c (Au)∼0.52)

Ultrafine Ag/MnO{sub x} nanowire-constructed hair-like nanoarchitecture: In situ synthesis, formation mechanism and its supercapacitive property

Energy Technology Data Exchange (ETDEWEB)

Li, Yonghe; Wang, Zhenyu; Zhang, Yuefei, E-mail: yfzhang@bjut.edu.cn

2015-09-25

Graphical abstract: In this work, novel hair-like (HL) nanoarchitectures constructed by ultrafine MnO{sub x} nanowires (∼7 nm) entrapped with Ag nanoparticle were first synthesized by facile in situ reaction between Ag nanowires and KMnO{sub 4}, and a following hydrothermal method. The as-prepared HL Ag/MnO{sub x} nanocomposites as electrode delivered a high specific capacitance and good cycle stability. - Highlights: • Ultrafine MnO{sub x} nanowires with Ag nanoparticle dispersed on were in situ prepared. • Kirkendall effect and Ostwald ripening mechanism ascribed to developed morphology. • Desirable specific capacitance and cyclability made it candidate for supercapacitors. - Abstract: Hair-like (HL) nanoarchitectures constructed by ultrafine MnO{sub x} nanowires (∼7 nm) with ultrafine Ag nanoparticles anchored on were synthesized by in situ facile reaction between silver (Ag) nanowires and potassium permanganate (KMnO{sub 4}), and followed by a following hydrothermal method. Based on a serious of time-dependent experiments, an orderly merged Kirkendall effect and dissolution-recrystallization (Ostwald ripening) mechanism were proposed for the formation of this novel morphology. The as-prepared HL Ag/MnO{sub x} nanocomposites as electrode exhibited a high specific capacitance (526 Fg{sup −1} at scan rate of 5 mV s{sup −1} and 450 Fg{sup −1} at current density of 0.1 Ag{sup −1}), good rate capability (ca. 45.5% retention with reference to 205 Fg{sup −1} at 50 times higher current density of 5 Ag{sup −1}) and desirable cycle stability (ranging from initial of 237 Fg{sup −1} to 185 Fg{sup −1} after 800 cycles and still maintaining 87% retention compared to 800th cycle after another 2800 cycles at current density of 2 Ag{sup −1}). Such desirable performance could be attributed to HL Ag/MnO{sub x} nanocomposites core (tubular nanosheets) with uniform dispersion of the ultrafine Ag nanoparticals provides a direct pathway for electron

AgBr and g-C{sub 3}N{sub 4} co-modified Ag{sub 2}CO{sub 3} photocatalyst: A novel multi-heterostructured photocatalyst with enhanced photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Tang, Hua, E-mail: tanghua@mail.ujs.edu.cn [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu Province 212013 (China); Chang, Shufang [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu Province 212013 (China); Tang, Guogang [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu Province 212013 (China); School of Chemistry and Materials Engineering, Zhenjiang College, Zhenjiang, Jiangsu Province 212003 (China); Liang, Wei [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu Province 212013 (China)

2017-01-01

Highlights: • Novel g-C{sub 3}N{sub 4}/Ag{sub 2}CO{sub 3}/AgBr nanocomposites were prepared by a facile method. • g-C{sub 3}N{sub 4}/Ag{sub 2}CO{sub 3}/AgBr-6% has superior activity in degradation of dyes. • The synergetic effect of g-C{sub 3}N{sub 4} and AgBr was the origin of the higher performance. • The photocatalytic mechanism of the g-C{sub 3}N{sub 4}/Ag{sub 2}CO{sub 3}/AgBr was proposed. - Abstract: Novel and highly efficient visible-light-driven g-C{sub 3}N{sub 4}/Ag{sub 2}CO{sub 3}/AgBr multi-heterostructured photocatalysts are achieved from the surface modification of g-C{sub 3}N{sub 4}/Ag{sub 2}CO{sub 3} with AgBr nanoparticles by a facile and efficient ion-exchange method. The as-prepared g-C{sub 3}N{sub 4}/Ag{sub 2}CO{sub 3}/AgBr photocatalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scaning electron microscopy (SEM) and UV–vis diffuse reflectance spectrometry (DRS). Compared with g-C{sub 3}N{sub 4}/Ag{sub 2}CO{sub 3}, g-C{sub 3}N{sub 4}/Ag{sub 2}CO{sub 3}/AgBr hybrids exhibit enhanced the degradation activity for typical RhB, MB, and MO dyes under visible light excitation (>420 nm). Photoluminescence (PL), photo-induced current and electrochemical impedance spectroscopy (EIS) results demonstrate the g-C{sub 3}N{sub 4}/Ag{sub 2}CO{sub 3}/AgBr heterojunctions can effectively suppress the recombination of the generated electron–hole pairs. The higher photocatalytical performance of g-C{sub 3}N{sub 4}/Ag{sub 2}CO{sub 3}/AgBr can be ascribed to the efficient separation of photogenerated electron–hole pairs due to the formation of multi-heterojunctions, in which the Ag nanoparticles acted as the charge transmission bridge. In addition, the possible transferred and separated behavior of electron–hole pairs and photocatalytic mechanisms based on the experimental results are also proposed in detail.

Photoelectrocatalytic properties of Ag nanoparticles loaded TiO2 nanotube arrays prepared by pulse current deposition

International Nuclear Information System (INIS)

Xie Kunpeng; Sun Lan; Wang Chenglin; Lai Yuekun; Wang Mengye; Chen Hongbo; Lin Changjian

2010-01-01

A pulse current deposition technique was adopted to construct highly dispersed Ag nanoparticles on TiO 2 nanotube arrays which were prepared by the electrochemical anodization. The morphology, crystallinity, elemental composition, and UV-vis absorption of Ag/TiO 2 nanotube arrays were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and diffuse reflectance spectra (DRS). In particular, the photoelectrochemical properties and photoelectrocatalytic activity under UV light irradiation and the photocatalytic activity under visible light irradiation for newly synthesized Ag/TiO 2 nanotube arrays were investigated. The maximum incident photon to charge carrier efficiency (IPCE) value of Ag/TiO 2 nanotube arrays was 51%, much higher than that of pure TiO 2 nanotube arrays. Ag/TiO 2 nanotube arrays exhibited higher photocatalytic activities than the pure TiO 2 nanotube arrays under both UV and visible light irradiation. The photoelectrocatalytic activity of Ag/TiO 2 nanotube arrays under UV light irradiation was 1.6-fold enhancement compared with pure TiO 2 nanotube arrays. This approach can be used in synthesizing various metal-loaded nanotube arrays materials.

A radiation-sensitive monomer of 2,4-hexadiyn-1,6-bis(p-toluene sulphonyl urethane) in PVA as a radiochromic film dosimeter

Science.gov (United States)

Soliman, Yasser S.; Abdel-Fattah, A. A.; Hamed, A. A.; Bayomi, A. M. M.

2018-03-01

A conjugated monomer 2,4-hexadiyn-1,6-bis(p-toluene sulphonyl urethane) (HDTU) was synthesized. Thereafter, it was incorporated into polyvinyl alcohol (PVA), and coated on self-adhesive sheet, thus to prepare film dosimeters. The monomer and films were analyzed using X-ray diffraction (XRD), FTIR spectroscopy and specular reflectance colorimetry. This monomer polymerizes in the films by radiation and turns progressively blue in proportion to absorbed dose, indicating the formation of π-conjugated colored poly-HDTU. Color development was investigated at 480 nm and 610 nm for dose monitoring ranging from 10 Gy to 15 kGy. HDTU in PVA film is highly ordered and crystalline and, upon irradiation, it forms a semi-crystalline polymer with nearly the same interplanar distances as the monomer, indicating the occurrence of topochemical polymerization. During irradiation, polymerization of the monomer is nearly independent of humidity in the range of 0-53% and temperature in the range of 25-45 °C. The uncertainty of this system is 5.16% at 95% confidence level.

Diffusion of Ag, Au and Cs implants in MAX phase Ti3SiC2

Energy Technology Data Exchange (ETDEWEB)

Jiang, Weilin; Henager, Charles H.; Varga, Tamas; Jung, Hee Joon; Overman, Nicole R.; Zhang, Chonghong; Gou, Jie

2015-05-16

MAX phases (M: early transition metal; A: elements in group 13 or 14; X: C or N), such as titanium silicon carbide (Ti3SiC2), have a unique combination of both metallic and ceramic properties, which make them attractive for potential nuclear applications. Ti3SiC2 has been considered as a possible fuel cladding material. This study reports on the diffusivities of fission product surrogates (Ag and Cs) and a noble metal Au (with diffusion behavior similar to Ag) in this ternary compound at elevated temperatures, as well as in dual-phase nanocomposite of Ti3SiC2/3C-SiC and polycrystalline CVD 3C-SiC for behavior comparisons. Samples were implanted with Ag, Au or Cs ions and characterized with various methods, including x-ray diffraction, electron backscatter diffraction, energy dispersive x-ray spectroscopy, Rutherford backscattering spectrometry, helium ion microscopy, and transmission electron microscopy. The results show that in contrast to immobile Ag in 3C-SiC, there is a significant outward diffusion of Ag in Ti3SiC2 within the dual-phase nanocomposite during Ag ion implantation at 873 K. Similar behavior of Au in polycrystalline Ti3SiC2 was also observed. Cs out-diffusion and release from Ti3SiC2 occurred during post-implantation thermal annealing at 973 K. This study suggests caution and further studies in consideration of Ti3SiC2 as a fuel cladding material for advanced nuclear reactors operating at very high temperatures.

Nanostructured inorganic materials: Synthesis and associated electrochemical properties

Science.gov (United States)

Yau, Shali Zhu

Synthetic strategy for preparing potential battery materials at low temperature was developed. Magnetite (Fe3O4), silver hollandnite (AgxMn8O16), magnesium manganese oxide (MgxMnO 2˙yH2O), and silver vanadium phosphorous oxide (Ag 2VO2PO4) were studied. Magnetite (Fe3O4) was prepared by coprecipitation induced by triethylamine from aqueous iron(II) and iron(III) chloride solutions of varying concentrations. Variation of the iron(II) and iron(III) concentrations results in crystallite size control of the Fe3O4 products. Materials characterization of the Fe3O4 samples is reported, including Brunauer-Emmitt-Teller (BET) surface area, x-ray powder diffraction (XRD), transmission electron microscopy (TEM), particle size, and saturation magnetization results. A strong correlation between discharge capacity and voltage recovery behavior versus crystallite size was observed when tested as an electrode material in lithium electrochemical cells. Silver hollandite (AgxMn8O16) was successfully synthesized through a low temperature reflux reaction. The crystallite size and silver content of AgxMn8O16 by varying the reactant ratio of silver permanganate (AgMnO4) and manganese sulfate monohydrate (MnSO4˙H2O). Silver hollandite was characterized by Brunauer-Emmitt-Teller (BET) surface area, inductively coupled plasma-optical emission (ICP-OES) spectrometry, helium pycnometry, simultaneous thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), and x-ray powder diffraction (XRD). The crystallite size showed a strong correlation with silver content, BET surface area, and particle sizes. The silver hollandite cathode showed good discharge capacity retention in 30 cycles of discharge-charge. There were a good relationship between crystallite size and rate capability and pulse ability. Magnesium manganese oxide (MgxMnO2˙yH 2O) was made by redox reaction by mixing sodium hydroxide (NaOH), manganese sulfate monohydrate (MnSO4˙HO2), and potassium persulfate (K2S2O8

Antimicrobial activity and biocompatibility of Ag{sup +}- and Cu{sup 2+}-doped biphasic hydroxyapatite/α-tricalcium phosphate obtained from hydrothermally synthesized Ag{sup +}- and Cu{sup 2+}-doped hydroxyapatite

Energy Technology Data Exchange (ETDEWEB)

Radovanović, Željko, E-mail: zradovanovic@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade (Serbia); Jokić, Bojan; Veljović, Djordje; Dimitrijević, Suzana [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade (Serbia); Kojić, Vesna [Oncology Institute of Vojvodina, Institutski put 4, 21204 Sremska Kamenica (Serbia); Petrović, Rada; Janaćković, Djordje [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade (Serbia)

2014-07-01

Hydroxyapatite (HAp) powders doped with Ag{sup +} or Cu{sup 2+} were synthesized by a hydrothermal method in order to obtain biomaterial with an antimicrobial effect. The synthesis was performed with two contents of dopant (Ag{sup +} or Cu{sup 2+}) by considering both the antimicrobial activities and biocompatibility of the powders. The doped HAp was annealed at 1200 °C for 2 h with the intention of investigating the influence of doping with Ag{sup +} and Cu{sup 2+} on the creation of the biphasic HAp/α-tricalcium phosphate (HAp/α-TCP) and determining the antimicrobial activity and biocompatibility of the obtained biphasic powders. Analyses of all powders, undoped and doped HAp and HAp/α-TCP, were performed by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS) and energy-dispersive X-ray spectroscopy (EDS). The in vitro antibacterial activities of the powders were evaluated against: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. All powders showed good antimicrobial activity but generally the powders of doped HAp/α-TCP had more uniform results against all pathogenic microorganisms than the powders of doped HAp. In vitro biocompatibility tests, MTT and DET, were used to evaluate the biocompatibility of Ag{sup +}- and Cu{sup 2+}-doped HAp/α-TCP with MRC-5 human fibroblast cells. These tests confirmed that powders do not have a cytotoxic effect. The HAp/α-TCP powders doped with the lower content of Ag{sup +} and Cu{sup 2+} showed especially good biocompatibility. Antimicrobial and biocompatibility tests recommend the Ag{sup +}- and Cu{sup 2+}-doped HAp/α-TCP as promising material for use in reconstructive surgery of bone.

Synthesis, morphological control, and antibacterial properties of hollow/solid Ag2S/Ag heterodimers

KAUST Repository

Pang, Maolin

2010-08-11

Ag2S and Ag are important functional materials that have received considerable research interest in recent years. In this work, we develop a solution-based synthetic method to combine these two materials into hollow/solid Ag2S/Ag heterodimers at room temperature. Starting from monodisperse Cu2O solid spheres, CuS hollow spheres can be converted from Cu2O through a modified Kirkendall process, and the obtained CuS can then be used as a solid precursor for preparation of the Ag2S/Ag heterodimers through ion exchange and photo-assisted reduction. We have found that formation of the Ag2S/Ag heterodimers is instantaneous, and the size of Ag nanocrystals on the hollow spheres of Ag2S can be controlled by changing the concentration and power of reducing agents in the synthesis. The growth of Ag nanoparticles on hollow spheres of Ag2S in the dimers is along the [111] direction of the silver crystal; the light absorption properties have also been investigated. Furthermore, coupling or tripling of Ag2S/Ag heterodimers into dumbbell-like trimers ((Ag 2S)2/Ag, linear) and triangular tetramers ((Ag 2S)3/Ag, coplanar) can also be attained at 60°C by adding the bidentate ligand ethylenediamine as a cross-linking agent. To test the applicability of this highly asymmetric dipolar composite, photocatalytic inactivation of Escherichia coli K-12 in the presence of the as-prepared Ag 2S/Ag heterodimers has been carried out under UV irradiation. The added Ag2S/Ag heterodimers show good chemical stability under prolonged UV irradiation, and no appreciable solid dissolution is found. Possible mechanisms regarding the enhanced antibacterial activity have also been addressed. © 2010 American Chemical Society.

Compensation effect in H 2 permeation kinetics of PdAg membranes

KAUST Repository

Zeng, Gaofeng

2012-08-30

Knowledge about the (inter)dependence of permeation kinetic parameters on the stoichiometry of H 2-selective alloys is still rudimentary, although uncovering the underlying systematic correlations will greatly facilitate current efforts into the design of novel high-performance H 2 separation membranes. Permeation measurements with carefully engineered, 2-7 μm thick supported Pd 100-xAg x membranes reveal that the activation energy and pre-exponential factor of H 2 permeation laws vary systematically with alloy composition, and both kinetic parameters are strongly correlated for x ≤ 50. We show that this permeation kinetic compensation effect corresponds well with similar correlations in the hydrogen solution thermodynamics and diffusion kinetics of PdAg alloys that govern H 2 permeation rates. This effect enables the consistent description of permeation characteristics over wide temperature and alloy stoichiometry ranges, whereas hydrogen solution thermodynamics may play a role, too, as a yet unrecognized source of kinetic compensation in, for example, H 2-involving reactions over metal catalysts or hydrogenation/ dehydrogenation of hydrogen storage materials. © 2012 American Chemical Society.

Synthesis and characterization of Ag/AgBrO{sub 3} photocatalyst with high photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Song, Limin, E-mail: songlmnk@sohu.com [College of Environment and Chemical Engineering & State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin, 300387 (China); Li, Tongtong [College of Environment and Chemical Engineering & State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin, 300387 (China); Zhang, Shujuan [College of Science, Tianjin University of Science & Technology, Tianjin, 300457 (China)

2016-10-01

A new Ag/AgBrO{sub 3} photocatalyst was prepared by mixing aqueous solutions of AgNO{sub 3} and NaBrO{sub 3}. The catalyst’s structure and performance were investigated with X-ray powder diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The UV–vis absorption spectrum of Ag/AgBrO{sub 3} exhibits a band gap of 3.97 eV. The results show that the Ag/AgBrO{sub 3} semiconductor can be excited by ultraviolet–visible light. The photodegradation of Rhodamine B displayed much higher photocatalytic activity than that of N-doped TiO{sub 2} under the same experimental conditions. Moreover, ·OH and ·O{sub 2}{sup −} generated in the photocatalysis played a key role of the photodegradation of Rhodamine B. - Highlights: • Ag/AgBrO{sub 3} with higher photodegradation ability was synthesized. • ·OH and ·O{sub 2}{sup −} radicals were the main active species in the oxidation of RhB. • The possible reaction mechanism was discussed in details.

File list: ALL.Emb.20.AllAg.2-4h_embryos [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available ALL.Emb.20.AllAg.2-4h_embryos dm3 All antigens Embryo 2-4h embryos SRX127437,SRX482...X372808,SRX197573,SRX183890,SRX197576,SRX661062,SRX183886 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Emb.20.AllAg.2-4h_embryos.bed ...

CO oxidation catalyzed by ag nanoparticles supported on SnO/CeO2

KAUST Repository

Khan, Inayatali

2015-01-01

Ag-Sn/CeO2 catalysts were synthesized by the co-precipitation method with different Ag-Sn wt.% loadings and were tested for the oxidation of CO. The catalysts were characterized by powder X-ray diffractometry (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) techniques. UV-Vis measurements were carried out to elucidate the ionic states of the silver particles, and the temperature-programmed reduction (TPR) technique was employed to check the reduction temperature of the catalyst supported on CeO2. There are peaks for silver crystallites in the X-ray diffraction patterns and the presence of SnO was not well evidenced by the XRD technique due to sintering inside the 3D array channels of CeO2 during the calcination process. The Ag-Sn/CeO2 (4%) catalyst was the most efficient and exhibited 100% CO oxidation at 100 °C due to small particle size and strong electronic interaction with the SnO/CeO2 support. © 2015 Sociedade Brasileira de Química.

Kinetics of the monomer-dimer reaction of yeast hexokinase PI.

Science.gov (United States)

Hoggett, J G; Kellett, G L

1992-10-15

Kinetic studies of the glucose-dependent monomer-dimer reaction of yeast hexokinase PI at pH 8.0 in the presence of 0.1 M-KCl have been carried out using the fluorescence temperature-jump technique. A slow-relaxation effect was observed which was attributed from its dependence on enzyme concentration to the monomer-dimer reaction; the reciprocal relaxation times tau-1 varied from 3 s-1 at low concentrations of glucose to 42 s-1 at saturating concentrations. Rate constants for association (kass.) and dissociation (kdiss.) were determined as a function of glucose concentration using values of the equilibrium association constant of the monomer-dimer reaction derived from sedimentation ultracentrifugation studies under similar conditions, and also from the dependence of tau-2 on enzyme concentration. kass. was almost independent of glucose concentration and its value (2 x 10(5) M-1.s-1) was close to that expected for a diffusion-controlled process. The influence of glucose on the monomer-dimer reaction is entirely due to effects on kdiss., which increases from 0.21 s-1 in the absence of glucose to 25 s-1 at saturating concentrations. The monomer and dimer forms of hexokinase have different affinities and Km values for glucose, and the results reported here imply that there may be a significant lag in the response of the monomer-dimer reaction to changes in glucose concentrations in vivo with consequent hysteretic effects on the hexokinase activity.

Optical and structural properties of TiO{sub 2}/Ti/Ag/TiO{sub 2} and TiO{sub 2}/ITO/Ag/ITO/TiO{sub 2} metal-dielectric multilayers by RF magnetron sputtering for display application

Energy Technology Data Exchange (ETDEWEB)

Lee, Jang-Hoon; Lee, Seung-Hyu; Hwangbo, Chang-Kwon [Inha University, Incheon (Korea, Republic of); Lee, Kwang-Su [Quantum Photonic Science Research Center, Hanyang University, Seoul (Korea, Republic of)

2004-03-15

Electromagnetic-interference (EMI) shielding and near-infrared (NIR) cutoff filters for plasma display panels, based on fundamental structures (ITO/Ag/ITO), (TiO{sub 2}/Ti/Ag/TiO{sub 2}) and (TiO{sub 2}/ITO/Ag/ITO/TiO{sub 2}), were designed and prepared by RF-magnetron sputtering. The optical, structural and electrical properties of the filters were investigated by using spectrophotometry, Auger electron spectroscopy, X-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, atomic force microscopy and four-point-probe measurements. The results show that ITO films as the barriers and base layers lead to higher transmittance in the visible spectrum and smoother surface roughness than Ti metal barriers, while maintaining high NIR cutoff characteristics and chemical stability, which may be attributed to the lower absorption in the interfacial layers and better protection of the Ag layers by the ITO layers.

Fabrication, characterization and photocatalytic properties of Ag nanoparticles modified TiO{sub 2} NTs

Energy Technology Data Exchange (ETDEWEB)

Wang Qingyao [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Yang Xiuchun, E-mail: yangxc@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Liu Dan; Zhao Jianfu [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China)

2012-06-25

Graphical abstract: The TiO{sub 2} NTs were first treated with bi-functional mercaptoacetic acid linkers (HOOC-R-S). The -OH group on the surface of TiO{sub 2} NT provides a strong affinity with the carboxylate group in the linker molecules. The thiol functional group in the linker molecules facilitates the binding with Ag from AgNO{sub 3} solution. After Ag{sup +} ions were reduced by NaBH{sub 4}, Ag nanoparticles formed by nucleation and growth. Highlights: Black-Right-Pointing-Pointer Ag nanoparticles with an average diameter of 9.2 nm were filled in the TiO{sub 2} nanotubes by a successive ionic layer adsorption and reaction (SILAR) technique. Black-Right-Pointing-Pointer Bi-functional mercaptoacetic acid linkers were used to bind TiO{sub 2} nanotubes with Ag nanoparticles. Black-Right-Pointing-Pointer Ag nanoparticles modification of TiO{sub 2} NTs largely enhanced the photocatalytic degradation of methyl orange under ultraviolet light irradiation. - Abstract: Ordered anatase TiO{sub 2} nanotubes (TiO{sub 2} NTs) on Ti substrate were synthesized by electrochemical anodization and subsequently vapor-thermal treatment. Ag nanoparticles were decorated on TiO{sub 2} NTs by successive ionic layer adsorption and reaction (SILAR) technique. Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the characterization of surface morphology, phase composition, and microstructure of the original TiO{sub 2} NTs, the vapor-thermally treated TiO{sub 2} NTs and the Ag nanoparticles decorated TiO{sub 2} NTs. The results indicate that vapor-thermal treatment favors to the transformation of amorphous TiO{sub 2} into anatase phase. Increasing the SILAR cycle times favors to increase the loaded amounts of Ag nanoparticles in TiO{sub 2} NTs. Ag nanoparticles are uniformly distributed in the TiO{sub 2} NTs, and

Synergetic effect of Ag{sub 2}O as co-catalyst for enhanced photocatalytic degradation of phenol on N-TiO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Chu, Haipeng [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Liu, Xinjuan, E-mail: lxj669635@126.com [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Liu, Junying [Research Center for Combustion and Environment Technology, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, Jinliang [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, School of Physics and Materials Science, East China Normal University, Shanghai 200062 (China); Wu, Tianyang; Li, Haokun; Lei, Wenyan; Xu, Yan [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Pan, Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, School of Physics and Materials Science, East China Normal University, Shanghai 200062 (China)

2016-09-15

Graphical abstract: Ag{sub 2}O/N-TiO{sub 2} composites were synthesized via a co-precipitation method for visible light photocatalytic degradation of organic pollutions with excellent photocatalytic activity. - Highlights: • Ag{sub 2}O/N-TiO{sub 2} composites were synthesized via a facile precipitation method. • Ag{sub 2}O/N-TiO{sub 2} composites exhibited enhanced photocatalytic activity. • Ag{sub 2}O acts as co-catalyst to separate the photo-generated electron-hole pairs. - Abstract: A facile precipitation method was developed to synthesize the Ag{sub 2}O/N-TiO{sub 2} composites. Their morphology, structure and photocatalytic performance in the degradation of methylene blue (MB) and phenol under visible light irradiation were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, photoluminescence spectroscopy and UV–vis absorption spectroscopy, respectively. The results show that the Ag{sub 2}O/N-TiO{sub 2} composites exhibit excellent photocatalytic performance. The maximum degradation rates of MB and phenol are about 8.9 and 2.9 times that of pure N-TiO{sub 2}, respectively. The excellent photocatalytic performance is mainly ascribed to the synergetic effects of Ag{sub 2}O and N-TiO{sub 2} including the increased light absorption and the reduced electron-hole pair recombination in N-TiO{sub 2} with the presence of Ag{sub 2}O.

Effect of reactive monomer on PS-b-P2VP film.

Science.gov (United States)

Kim, H J; Shin, D M

2014-08-01

Poly(styrene-b-2-vinyl pyridine) (PS-b-P2VP) lamellar film which is hydrophobic block-hydrophilic polyelectrolyte block polymer of 52 kg/mol-b-57 kg/mol and PS-b-P2VP film with reactive monomer (RM257) were prepared for photonic gel films. The lamellar stacks, which is alternating layer of hydrophilic and hydrophobic moiety of PS-b-P2VP, were obtained by exposing the spin coated film under chloroform vapor. The lamellar films were quaternized with 5 wt% of iodomethane diluted by n-hexane. We reported about the influence of reactive monomer on those photonic gel films. Added reactive monomer photonic gel film had higher absorbance than pure photonic gel films. As a result the photonic gel film with RM had more clear color. The lamellar films were swollen by DI water, ethanol (aq) and calcium carbonate solution. The band gaps of the lamellar films were drastically shifted to longer wavelength swollen by calcium carbonate solution. And the lamellar films were shifted to shorter wave length swollen by ethanol. So each lamellar film showed different color.

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

Science.gov (United States)

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

2018-06-01

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

Synthesis, structure and electrochemistry of Ag-modified LiMn2O4 cathode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Zhou Wenjia; He Benlin; Li Hulin

2008-01-01

Spinel lithium manganese oxide was prepared by sol-gel method and a series of Ag/LiMn 2 O 4 composites with different Ag additive contents were prepared by thermal decomposition of AgNO 3 added to the pure LiMn 2 O 4 powders. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX) and various electrochemical measurement methods were used to examine the structural and electrochemical characteristics of the Ag/LiMn 2 O 4 composite powders. Phase analysis showed that Ag particles were dispersed on the surface of LiMn 2 O 4 instead of entering the spinel structure. According to the electrochemical tests results, it is clearly to see that Ag additives efficiently improved the cycling stability, reversibility and high-rate discharge capacity of pristine LiMn 2 O 4 by increasing the electrical conductivity between LiMn 2 O 4 particles, decreasing the polarization of cathode and reducing the dissolution of Mn. Meanwhile the influence of the Ag additive contents on the electrochemical properties of the Ag/LiMn 2 O 4 composites is also investigated in detail

Thermal expansion behavior of empressite, AgTe: A structural study by means of in situ high-temperature single-crystal X-ray diffraction

International Nuclear Information System (INIS)

Bindi, Luca

2009-01-01

The crystal structure of empressite, AgTe, a rare silver telluride, has been investigated by in situ X-ray single-crystal diffraction methods within the temperature range 298-463 K. AgTe remains orthorhombic, space group Pmnb (Pnma as standard), and shows only normal thermal expansion over the entire temperature range. The unit-cell parameters show a gradual increase with the increase of temperature. Slight adjustments in the geometry of Ag-tetrahedra and in the crystal-chemical environment of tellurium atoms occur in a continuous way without abrupt structural changes. The coefficients of thermal expansion along various axes are: α a = 1.5 x 10 -5 K -1 , α b = 3.0 x 10 -5 K -1 , α c = 2.2 x 10 -5 K -1 , and the bulk thermal expansion coefficient α V is 5.4 x 10 -5 K -1 for the temperature range 298-463 K

Structural, electronic and optical properties of AgXY{sub 2}(X = Al, Ga, In and Y = S, Se, Te)

Energy Technology Data Exchange (ETDEWEB)

Ullah, Saeed; Din, Haleem Ud [Materials Modeling Lab, Department of Physics, Islamia College University, Peshawar (Pakistan); Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Lab, Department of Physics, Islamia College University, Peshawar (Pakistan); Ouahrani, T. [Laboratoire de Physique Théorique, B.P. 119, Université de Tlemcen, Tlemcen 13000 (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, Mascara 29000 (Algeria); Naeemullah [Department of Physics, G.D.C. Darra Adam Khel, F.R. Kohat, KPK (Pakistan); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)

2014-12-25

Highlights: • The compounds are studied by FP-LAPW method within mBJ approximation. • All of the studied materials show isotropic behavior. • All the compounds show direct band gap nature. • Bonding nature is mostly covalent among the studied compounds. • High absorption peaks and reflectivity ensures there utility in optoelectronic devices. - Abstract: The structural, electronic and optical properties of the ternary semiconducting compounds AgXY{sub 2} (X = Al, Ga, In and Y = S, Se, Te) in Heusler and chalcopyrite crystal phases have been investigated using the density functional theory (DFT) based on the full potential linear augmented plane wave (FP-LAPW) method. The calculated lattice constant and band gap values for AgXY{sub 2} in chalcopyrite phase are in good agreement with the available experimental data. Band structure calculations are performed using modified Becke–Johnson (mBJ) method which match closely with experimental data and yield better band gaps rather than those obtained by using generalized gradient approximation (GGA) and Engel–Vosko generalized gradient approximation (EV–GGA). Decrease in band gap is observed by changing cations X and Y from the top to bottom of periodic table. Chemical bonding trends are predicted through charge density plots and quantified by Bader’s analysis. Optical properties reveal that these compounds are suitable candidates for optoelectronic devices in the visible and ultraviolet (UV) regions.

Elucidating the real-time Ag nanoparticle growth on α-Ag2WO4 during electron beam irradiation: experimental evidence and theoretical insights.

Science.gov (United States)

Pereira, Wyllamanney da Silva; Andrés, Juan; Gracia, Lourdes; San-Miguel, Miguel A; da Silva, Edison Z; Longo, Elson; Longo, Valeria M

2015-02-21

Why and how Ag is formed when electron beam irradiation takes place on α-Ag2WO4 in a vacuum transmission electron microscopy chamber? To find an answer, the atomic-scale mechanisms underlying the formation and growth of Ag on α-Ag2WO4 have been investigated by detailed in situ transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM) studies, density functional theory based calculations and ab initio molecular dynamics simulations. The growth process at different times, chemical composition, size distribution and element distribution were analyzed in depth at the nanoscale level using FE-SEM, operated at different voltages (5, 10, 15, and 20 kV), and TEM with energy dispersive spectroscopy (EDS) characterization. The size of Ag nanoparticles covers a wide range of values. Most of the Ag particles are in the 20-40 nm range. The nucleation and formation of Ag on α-Ag2WO4 is a result of structural and electronic changes in the AgOx (x = 2,4, 6, and 7) clusters used as constituent building blocks of this material, consistent with metallic Ag formation. First principle calculations point out that Ag-3 and Ag-4-fold coordinated centers, located in the sub-surface of the (100) surface, are the most energetically favorable to undergo the diffusion process to form metallic Ag. Ab initio molecular dynamics simulations and the nudged elastic band (NEB) method were used to investigate the minimum energy pathways of these Ag atoms from positions in the first slab layer to outward sites on the (100) surface of α-Ag2WO4. The results point out that the injection of electrons decreases the activation barrier for this diffusion step and this unusual behavior results from the presence of a lower energy barrier process.

Influence of Temperature on the Formation of Ag Complexed in a S2O32−–O2 System

Directory of Open Access Journals (Sweden)

Aislinn M. Teja-Ruiz

2017-01-01

Full Text Available Metallic elements of higher economic value, occurring in the mineralogy of Zimapán, are Pb, Zn, Cu, and Fe; said elements are sold as concentrates, which, even after processing, generally include significant concentrations of Mo, Cd, Sb, Ag, and As that can be recovered through different leaching methods. In this work, the influence of temperature in the complexation of silver contained in a concentrate of Zn using the technology of thiosulfate with oxygen injection was studied. Chemical and mineralogical characterization of the mineral concentrate from the state of Hidalgo, Mexico confirmed the existence of silver contained in a sulfide of silver arsenic (AgAsS2 by X-ray Diffraction (XRD. The results obtained by Atomic Absorption Spectrophotometry (AAS reported abundant metallic contents (% w/w (48% Zn, 10.63% Fe, 1.97% Cu, 0.84% Pb, 0.78% As, and 0.25% Ag. These results corroborate the presence of metallic sulfides such as pyrite, chalcopyrite, and wurtzite; this last species was identified as the matrix of the concentrate by X-ray Diffraction (XRD and Scanning Electron Microscopy-Energy-Dispersive X-ray Spectroscopy (SEM-EDS. Pourbaix diagrams were constructed for the AgAsS2–S2O32−–O2 system at different temperatures, which allowed the chemical reaction of leaching to be established, in addition to determining Eh-pH conditions in which to obtain silver in solution. The highest recoveries of the precious metal (97% Ag were obtained at a temperature of 333 K and [S2O32−] = 0.5 M. The formation of silver dithiosulfate complex (Ag(S2O323− was confirmed by the characterization of the leach liquors obtained from the experiments performed in the temperature range of 298 to 333 K using Fourier transform infrared spectroscopy (FTIR.

Synthesis of Ag-TiO{sub 2} composite nano thin film for antimicrobial application

Energy Technology Data Exchange (ETDEWEB)

Yu Binyu; Guo Qiuquan; Yang Jun [Biomedical Engineering Graduate Program, University of Western Ontario, London, ON, N6A 5B9 (Canada); Leung, Kar Man [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON, N6A 5B9 (Canada); Lau, Woon Ming [Surface Science Western, University of Western Ontario, London, ON, N6A 5B9 (Canada)

2011-03-18

TiO{sub 2} photocatalysts have been found to kill cancer cells, bacteria and viruses under mild UV illumination, which offers numerous potential applications. On the other hand, Ag has long been proved as a good antibacterial material as well. The advantage of Ag-TiO{sub 2} nanocomposite is to expand the nanomaterial's antibacterial function to a broader range of working conditions. In this study neat TiO{sub 2} and Ag-TiO{sub 2} composite nanofilms were successfully prepared on silicon wafer via the sol-gel method by the spin-coating technique. The as-prepared composite Ag-TiO{sub 2} and TiO{sub 2} films with different silver content were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) to determine the topologies, microstructures and chemical compositions, respectively. It was found that the silver nanoparticles were uniformly distributed and strongly attached to the mesoporous TiO{sub 2} matrix. The morphology of the composite film could be controlled by simply tuning the molar ratio of the silver nitrate aqueous solution. XPS results confirmed that the Ag was in the Ag{sup 0} state. The antimicrobial effect of the synthesized nanofilms was carried out against gram-negative bacteria (Escherichia coli ATCC 29425) by using an 8 W UV lamp with a constant relative intensity of 0.6 mW cm{sup -2} and in the dark respectively. The synthesized Ag-TiO{sub 2} thin films showed enhanced bactericidal activities compared to the neat TiO{sub 2} nanofilm both in the dark and under UV illumination.

Metal Fe3+ ions assisted synthesis of highly monodisperse Ag/SiO2 nanohybrids and their antibacterial activity

International Nuclear Information System (INIS)

Zhang, Nianchun; Xue, Feng; Yu, Xiang; Zhou, Huihua; Ding, Enyong

2013-01-01

Graphical abstract: TEM images of the Ag/SiO 2 -2 nanohybrids. The homogeneous and more mono-disperse Ag nanoparticles deposit on SiO 2 spheres. Through this method, Ag nanoparticles are easily formed on the surface of SiO 2 compared to other methods. Highlights: ► We prepared homogeneous and mono-dispersed Ag/SiO 2 -2 nanohybrids by adding Fe 3+ ions. ► The Ag/SiO 2 -2 nanohybrids had core(SiO 2 )-shell(Ag) structure. ► The Ag/SiO 2 -2 nanohybrids exhibited excellent antibacterial activity against bacteria. ► The reaction temperature was lower and the yield of Ag/SiO 2 -2 nanohybrids were higher. - Abstract: Highly monodispersed Ag/SiO 2 nanohybrids with excellent antibacterial property were synthesized by using DMF as a reducing agent and employing an additional redox potential of metal Fe 3+ ion as a catalytic agent. The obtained Ag/SiO 2 -2 nanohybrids of about 240 nm were highly monodispersity and uniformity by adding trace Fe 3+ ions into the reaction which Ag + reacted with N,N-dimethyl formamide (DMF) at 70 °C. Compared to the conventional techniques, which need long time and high temperature for silica coating of Ag nanoparticles, this new method was capable of synthesizing monodispersed, uniform, high yield Ag/SiO 2 nanohybrids. The electron was transferred from the Fe 2+ ion to the Ag + ion to accelerate the nucleation of silver nanoparticles. The chemical structures, morphologies and properties of the Ag/SiO 2 nanohybrids were characterized by X-ray diffraction (XRD), (High-resolution, Scanning transmission) transmission electron microscopy (TEM, HRTEM and STEM), and X-ray photoelectron spectroscopy (XPS), and UV–vis spectroscopy (UV–vis) and test of antibacterial. The results demonstrated that the silver nanoparticles supported on the surface of SiO 2 spheres in Ag/SiO 2 -2 nanohybrids structure, the Ag nanoparticles were homogeneous and monodispersed. The results also indicated that the Ag/SiO 2 -2 nanohybrid had excellent antibacterial.

High-temperature deformation of YBa2Cu3O7-δ with Ag additions

International Nuclear Information System (INIS)

Routbort, J.L.; Goretta, K.C.; Singh, J.P.

1990-01-01

The steady-state flow stress of YBa 2 Cu 3 O 7-δ containing 15 to 30 vol.% Ag has been measured in air at nearly constant compressive strain rates between 5 x 10 -6 and 1 x 10 -4 s -1 from 830 to 900 degrees C. Addition of Ag dramatically decreases the flow stress compared to that of the pure superconductor, but the stress exponents and the activation energy for deformation remain unchanged

Enhanced photocatalytic performance of sandwiched ZnO@Ag@Cu2O nanorod films: the distinct role of Ag NPs in the visible light and UV region

International Nuclear Information System (INIS)

Ren, Shoutian; Wang, Yingying; Wang, Benyang; Wang, Qiang; Zhao, Guoliang

2015-01-01

Sandwiched ZnO@Ag@Cu 2 O nanorod films were synthesized by successive electrodeposition, magnetron sputtering and the second electrodeposition. The as-synthesized composites were characterized by x-ray diffraction patterns, field emission scanning electron microscopy, low- and high-resolution transmission electron microscopy and a UV–vis spectrophotometer. Their photocatalytic performance was estimated by the degradation of a methyl orange solution under UV or visible-light irradiation, respectively. In the visible region, due to localized surface plasmon resonance absorption of Ag NPs, ZnO@Ag@Cu 2 O showed a significantly enhanced photocatalytic performance. The enhancement factor of Ag NPs on the catalytic performance of ZnO@Ag@Cu 2 O was estimated as a function of the Cu 2 O deposition time, and the corresponding enhancement mechanism was also evaluated by the monochromatic photocatalytic experiment and discrete dipole approximation simulation. In the UV region, due to the formation of a Schottky junction (e.g. Ag/ZnO, Ag/Cu 2 O), a limited enhanced photocatalytic performance was also realized for ZnO@Ag@Cu 2 O photocatalysts. (paper)

Synthesis and properties of new CdSe-AgI-As{sub 2}Se{sub 3} chalcogenide glasses

Energy Technology Data Exchange (ETDEWEB)

Kassem, M. [Univ Lille Nord de France, F-59000 Lille (France); ULCO, LPCA, EAC CNRS 4493 F-59140 Dunkerque (France); Le Coq, D., E-mail: david.lecoq@univ-littoral.fr [Univ Lille Nord de France, F-59000 Lille (France); ULCO, LPCA, EAC CNRS 4493 F-59140 Dunkerque (France); Fourmentin, M.; Hindle, F.; Bokova, M.; Cuisset, A.; Masselin, P.; Bychkov, E. [Univ Lille Nord de France, F-59000 Lille (France); ULCO, LPCA, EAC CNRS 4493 F-59140 Dunkerque (France)

2011-02-15

Research highlights: {yields} Determination of the glass-forming region in the pseudo-ternary CdSe-AgI-As{sub 2}Se{sub 3} system. {yields} Characterization of macroscopic properties of the new CdSe-AgI-As{sub 2}Se{sub 3} glasses. {yields} Far infrared transmission of chalcogenide glasses. {yields} Characterization of the total conductivity of CdSe-AgI-As{sub 2}Se{sub 3} glasses. -- Abstract: The glass-forming region in the pseudo-ternary CdSe-AgI-As{sub 2}Se{sub 3} system was determined. Measurements including differential scanning calorimetry (DSC), density, and X-ray diffraction were performed. The effect resulting from the addition of CdSe or AgI has been highlighted by examining three series of different base glasses. The characteristic temperatures of the glass samples, including glass transition (T{sub g}), crystallisation (T{sub x}), and melting (T{sub m}) temperatures are reported and used to calculate their {Delta}T = T{sub x} - T{sub g} and their Hruby, H{sub r} = (T{sub x} - T{sub g})/(T{sub m} - T{sub x}), criteria. Evolution of the total electrical conductivity {sigma} and the room temperature conductivity {sigma}{sub 298} was also studied. The terahertz transparency domain in the 50-600 cm{sup -1} region was pointed for different chalcogenide glasses (ChGs) and the potential of the THz spectroscopy was suggested to obtain structural information on ChGs.

Plasmon-resonance-enhanced visible-light photocatalytic activity of Ag quantum dots/TiO2 microspheres for methyl orange degradation

Science.gov (United States)

Yu, Xin; Shang, Liwei; Wang, Dongjun; An, Li; Li, Zhonghua; Liu, Jiawen; Shen, Jun

2018-06-01

We successfully prepared Ag quantum dots modified TiO2 microspheres by facile solvothermal and calcination method. The as-prepared Ag quantum dots/TiO2 microspheres were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The Ag quantum dots/TiO2 photocatalyst showed excellent visible light absorption and efficient photocatalytic activity for methyl orange degradation. And the sample with the molar ratio of 0.05 (Ag to Ti) showed the best visible light photocatalytic activity for methyl orange degradation, mainly because of the surface plasmon resonance (SPR) effects of Ag quantum dots to generate electron and hole pairs for enhanced visible light photocatalysis. Finally, possible visible light photocatalytic mechanism of Ag quantum dots/TiO2 microspheres for methyl orange degradation was proposed in detail.

Efficient visible-light photocatalytic activity by band alignment in mesoporous ternary polyoxometalate-Ag2S-CdS semiconductors

Science.gov (United States)

Kornarakis, I.; Lykakis, I. N.; Vordos, N.; Armatas, G. S.

2014-07-01

Porous multicomponent semiconductor materials show improved photocatalytic performance due to the large and accessible pore surface area and high charge separation efficiency. Here we report the synthesis of well-ordered porous polyoxometalate (POM)-Ag2S-CdS hybrid mesostructures featuring a controllable composition and high photocatalytic activity via a two-step hard-templating and topotactic ion-exchange chemical process. Ag2S compounds and polyoxometalate cluster anions with different reduction potentials, such as PW12O403-, SiW12O404- and PMo12O403-, were employed as electron acceptors in these ternary heterojunction photocatalysts. Characterization by small-angle X-ray scattering, X-ray diffraction, transmission electron microscopy and N2 physisorption measurements showed hexagonal arrays of POM-Ag2S-CdS hybrid nanorods with large internal BET surface areas and uniform mesopores. The Keggin structure of the incorporated POM clusters was also verified by elemental X-ray spectroscopy microanalysis, infrared and diffuse-reflectance ultraviolet-visible spectroscopy. These new porous materials were implemented as visible-light-driven photocatalysts, displaying exceptional high activity in aerobic oxidation of various para-substituted benzyl alcohols to the corresponding carbonyl compounds. Our experiments show that the spatial separation of photogenerated electrons and holes at CdS through the potential gradient along the CdS-Ag2S-POM interfaces is responsible for the increased photocatalytic activity.Porous multicomponent semiconductor materials show improved photocatalytic performance due to the large and accessible pore surface area and high charge separation efficiency. Here we report the synthesis of well-ordered porous polyoxometalate (POM)-Ag2S-CdS hybrid mesostructures featuring a controllable composition and high photocatalytic activity via a two-step hard-templating and topotactic ion-exchange chemical process. Ag2S compounds and polyoxometalate cluster

Fabrication of Ag{sub 2}O/TiO{sub 2} with enhanced photocatalytic performances for dye pollutants degradation by a pH-induced method

Energy Technology Data Exchange (ETDEWEB)

Ren, Hai-Tao, E-mail: renhaitaomail@163.com; Yang, Qing

2017-02-28

Highlights: • Ag{sub 2}O/TiO{sub 2} was synthesized by a pH-induced chemical precipitation method. • Ag{sub 2}O/TiO{sub 2} showed good activities in the photocatalytic degradation of methyl orange. • Hydroxyl radicals played the predominant role in methyl orange photodegradation. - Abstract: Ag{sub 2}O/TiO{sub 2} composites synthesized in this study were applied into the photocatalytic degradation of methyl orange (MO) under UV and visible light irradiation. X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscope analysis demonstrated that Ag{sub 2}O nanoparticles were well distributed on the surface of TiO{sub 2} and the heterostructure of Ag{sub 2}O/TiO{sub 2} was formed. Compared with the pure TiO{sub 2} and Ag{sub 2}O, the 3% and 50% Ag{sub 2}O/TiO{sub 2} composite displayed much higher photocatalytic activities in MO degradation under UV and visible light irradiation, respectively. The degradation rate constant of 50% composite was 0.01508 min{sup −1} under visible light, which was almost 20.1 and 1.2 times more than that of the pure TiO{sub 2} and Ag{sub 2}O, respectively. Moreover, the formation of Ag(0) on the surface of Ag{sub 2}O under illumination contributed to the high stability of Ag{sub 2}O/TiO{sub 2} photocatalysts. It was also found that hydroxyl radicals during the photocatalytic process played the predominant role in MO degradation. The enhanced photochemical activities were attributed to the formation of the heterostructure between Ag{sub 2}O and TiO{sub 2}, the strong visible light absorption and the high separation efficiency of photogenerated electron–hole pairs resulted from the highly dispersed Ag{sub 2}O particles.

Evaluation of the Antimicrobial Activity of Different Antibiotics Enhanced with Silver-Doped Hydroxyapatite Thin Films

Directory of Open Access Journals (Sweden)

Daniela Predoi

2016-09-01

Full Text Available The inhibitory and antimicrobial effects of silver particles have been known since ancient times. In the last few years, a major health problem has arisen due to pathogenic bacteria resistance to antimicrobial agents. The antibacterial activities of new materials including hydroxyapatite (HAp, silver-doped hydroxyapatite (Ag:HAp and various types of antibiotics such as tetracycline (T-HAp and T-Ag:HAp or ciprofloxacin (C-HAp and C-Ag:HAp have not been studied so far. In this study we reported, for the first time, the preparation and characterization of various thin films based on hydroxyapatite and silver-doped hydroxyapatite combined with tetracycline or ciprofloxacin. The structural and chemical characterization of hydroxyapatite and silver-doped hydroxyapatite thin films has been evaluated by X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FTIR. The morphological studies of the HAp, Ag:HAp, T-HAp, T-Ag:HAp, C-HAp and C-Ag:HAp thin solid films were performed using scanning electron microscopy (SEM. In order to study the chemical composition of the coatings, energy dispersive X-ray analysis (EDX and glow discharge optical emission spectroscopy (GDOES measurements have been used, obtaining information on the distribution of the elements throughout the film. These studies have confirmed the purity of the prepared hydroxyapatite and silver-doped hydroxyapatite thin films obtained from composite targets containing Ca10−xAgx(PO46(OH2 with xAg = 0 (HAp and xAg = 0.2 (Ag:HAp. On the other hand, the major aim of this study was the evaluation of the antibacterial activities of ciprofloxacin and tetracycline in the presence of HAp and Ag:HAp thin layers against Staphylococcus aureus and Escherichia coli strains. The antibacterial activities of ciprofloxacin and tetracycline against Staphylococcus aureus and Escherichia coli test strains increased in the presence of HAp and Ag:HAp thin layers.

Thermal expansion behavior of empressite, AgTe: A structural study by means of in situ high-temperature single-crystal X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Bindi, Luca [Museo di Storia Naturale, sez. di Mineralogia, Universita di Firenze, Via La Pira 4, I-50121 Firenze (Italy)], E-mail: luca.bindi@unifi.it

2009-04-03

The crystal structure of empressite, AgTe, a rare silver telluride, has been investigated by in situ X-ray single-crystal diffraction methods within the temperature range 298-463 K. AgTe remains orthorhombic, space group Pmnb (Pnma as standard), and shows only normal thermal expansion over the entire temperature range. The unit-cell parameters show a gradual increase with the increase of temperature. Slight adjustments in the geometry of Ag-tetrahedra and in the crystal-chemical environment of tellurium atoms occur in a continuous way without abrupt structural changes. The coefficients of thermal expansion along various axes are: {alpha}{sub a} = 1.5 x 10{sup -5} K{sup -1}, {alpha}{sub b} = 3.0 x 10{sup -5} K{sup -1}, {alpha}{sub c} = 2.2 x 10{sup -5} K{sup -1}, and the bulk thermal expansion coefficient {alpha}{sub V} is 5.4 x 10{sup -5} K{sup -1} for the temperature range 298-463 K.

Synthesis and Antimicrobial Activity of Silver-Doped Hydroxyapatite Nanoparticles

Directory of Open Access Journals (Sweden)

Carmen Steluta Ciobanu

2013-01-01

Full Text Available The synthesis of nanosized particles of Ag-doped hydroxyapatite with antibacterial properties is of great interest for the development of new biomedical applications. The aim of this study was the evaluation of Ca10−xAgx(PO46(OH2 nanoparticles (Ag:HAp-NPs for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years and became a major health problem. Here, we report a method for synthesizing Ag doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionised water. Also, in this paper Ag:HAp-NPs are evaluated for their antimicrobial activity against Gram-positive and Gram-negative bacteria and fungal strains. The specific antimicrobial activity revealed by the qualitative assay is demonstrating that our compounds are interacting differently with the microbial targets, probably due to the differences in the microbial wall structures.

Synthesis and Antimicrobial Activity of Silver-Doped Hydroxyapatite Nanoparticles