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Hiroshi Kitagawa - One of the best experts on this subject based on the ideXlab platform.
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Ultrafast fabrication of thermally stable protein-coated Silver Iodide nanoparticles for solid-state superionic conductors.
Colloids and surfaces. B Biointerfaces, 2018Co-Authors: Aryane Tofanello, Juscemácia N. Araújo, Iseli L. Nantes-cardoso, Fabio Furlan Ferreira, Jose A. Souza, Dae-woon Lim, Hiroshi Kitagawa, Wanius GarciaAbstract:Abstract Solid-state ionic conductor is an essential and critical part of electrochemical devices such as batteries and sensors. Nano-sized Silver Iodide (AgI) is the most promising ionic conductor due to its superionic conductivity at room temperature. In recent years, proteins have been used as organic templates to obtain high-performance solid-state ionic conductors as well as to extend their applications in a biosensor. Here, we report the unprecedented ultrafast synthesis of thermally stable protein-coated AgI nanoparticles (NPs) through the photo-irradiation method for solid-state electrolyte. The synthesis was performed using a hyperthermostable bacterial β-glucosidase. The protein-coated AgI NPs with an approximate diameter of 13 nm showed that the controllable transition from the α- to β-/γ-phase was drastically suppressed down to 41 °C in the cooling process. After drying, the product represents a thermally stable organic-inorganic hybrid system with superionic conductivity. It is noteworthy that the superionic conductivity (σ ˜ 0.14 S/cm at 170 °C) of thermally stable protein-coated AgI NPs is maintained during several thermal cycles (25–170 °C). To our knowledge, this is the first report showing the diffusion of mobile Ag+ ions on the surface of the AgI NPs through a protein matrix. The facile synthesis method and high performance of the protein-coated AgI NPs may provide a latent application in the mass production of nanobatteries and other technological applications.
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disappearance of the superionic phase transition in sub 5 nm Silver Iodide nanoparticles
Nano Letters, 2017Co-Authors: Takayuki Yamamoto, Hiroshi Kitagawa, Hirokazu Kobayashi, L S R Kumara, Osami Sakata, Kiyofumi Nitta, Tomoya UrugaAbstract:Bulk Silver Iodide (AgI) is known to show a phase transition from the poorly conducting β/γ-phases into the superionic conducting α-phase at 147 °C. Its transition temperature decreases with decreasing the size of AgI, and the α-phase exists stably at 37 °C in AgI nanoparticles with a diameter of 6.3 nm. In this Letter, we investigated the atomic configuration, the phase transition behavior, and the ionic conductivity of AgI nanoparticles with a diameter of 3.0 nm. The combination of pair distribution function (PDF) analysis and reverse Monte Carlo (RMC) modeling based on high-energy X-ray diffraction (XRD) revealed for the first time that they formed the β/γ-phases with atomic disorder. The results of extended X-ray absorption fine structure (EXAFS) analysis, differential scanning calorimetry (DSC), and AC impedance spectroscopy demonstrated that they did not exhibit the superionic phase transition and their ionic conductivity was lower than that of crystalline AgI. The disappearance of the superionic ph...
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The Room-Temperature Superionic Conductivity of Silver Iodide Nanoparticles under Pressure
Journal of the American Chemical Society, 2017Co-Authors: Takayuki Yamamoto, Mitsuhiko Maesato, Naohisa Hirao, Saori I. Kawaguchi, Shogo Kawaguchi, Yasuo Ohishi, Yoshiki Kubota, Hirokazu Kobayashi, Hiroshi KitagawaAbstract:We performed variable-temperature synchrotron powder X-ray diffraction measurements and impedance spectroscopy under pressure for Silver Iodide (AgI) nanoparticles with a diameter of 11 nm. The superionic conducting α-phase of AgI nanoparticles was successfully stabilized down to at least 20 °C by applying a pressure of 0.18 GPa, whereas the transition temperature was 147 °C in bulk AgI at ambient pressure. To our knowledge, this is the first example of the α-phase of AgI existing stably at room temperature.
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Size-controlled stabilization of the superionic phase to room temperature in polymer-coated AgI nanoparticles.
Nature materials, 2009Co-Authors: Rie Makiura, Kenichi Kato, Hiroshi Kitagawa, Takayuki Yonemura, Teppei Yamada, Miho Yamauchi, Ryuichi Ikeda, Masaki TakataAbstract:Silver Iodide is a well-known ionic conductor. However, it shows superionic conductivity only in its high-temperature phase (above∼150 ∘C). It is now demonstrated that various sizes of nanoparticles can be synthesized for which the superionic phase is stable down to ∼30 ∘C. The results suggest promising applications in Silver-ion-based electrochemical devices. Solid-state ionic conductors are actively studied for their large application potential in batteries1 and sensors. From the view of future nanodevices2,3,4,5, nanoscaled ionic conductors are attracting much interest. Silver Iodide (AgI) is a well-known ionic conductor for which the high-temperature α-phase shows a superionic conductivity greater than 1 Ω−1 cm−1 (ref. 6). Below 147 ∘C, α-AgI undergoes a phase transition into the poorly conducting β- and γ-polymorphs, thereby limiting its applications. Here, we report the facile synthesis of variable-size AgI nanoparticles coated with poly-N-vinyl-2-pyrrolidone (PVP) and the controllable tuning of the α- to β-/γ-phase transition temperature (Tc↓). Tc↓ shifts considerably to lower temperatures with decreasing nanoparticle size, leading to a progressively enlarged thermal hysteresis. Specifically, when the size approaches 10–11 nm, the α-phase survives down to 30 ∘C—the lowest temperature for any AgI family material. We attribute the suppression of the phase transition not only to the increase of the surface energy, but also to the presence of defects and the accompanying charge imbalance induced by PVP. Moreover, the conductivity of as-prepared 11 nm β-/γ-AgI nanoparticles at 24 ∘C is ∼1.5×10−2 Ω −1 cm−1—the highest ionic conductivity for a binary solid at room temperature. The stabilized superionic phase and the remarkable transport properties at a practical temperature reported here suggest promising applications in Silver-ion-based electrochemical devices.
Hirokazu Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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disappearance of the superionic phase transition in sub 5 nm Silver Iodide nanoparticles
Nano Letters, 2017Co-Authors: Takayuki Yamamoto, Hiroshi Kitagawa, Hirokazu Kobayashi, L S R Kumara, Osami Sakata, Kiyofumi Nitta, Tomoya UrugaAbstract:Bulk Silver Iodide (AgI) is known to show a phase transition from the poorly conducting β/γ-phases into the superionic conducting α-phase at 147 °C. Its transition temperature decreases with decreasing the size of AgI, and the α-phase exists stably at 37 °C in AgI nanoparticles with a diameter of 6.3 nm. In this Letter, we investigated the atomic configuration, the phase transition behavior, and the ionic conductivity of AgI nanoparticles with a diameter of 3.0 nm. The combination of pair distribution function (PDF) analysis and reverse Monte Carlo (RMC) modeling based on high-energy X-ray diffraction (XRD) revealed for the first time that they formed the β/γ-phases with atomic disorder. The results of extended X-ray absorption fine structure (EXAFS) analysis, differential scanning calorimetry (DSC), and AC impedance spectroscopy demonstrated that they did not exhibit the superionic phase transition and their ionic conductivity was lower than that of crystalline AgI. The disappearance of the superionic ph...
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The Room-Temperature Superionic Conductivity of Silver Iodide Nanoparticles under Pressure
Journal of the American Chemical Society, 2017Co-Authors: Takayuki Yamamoto, Mitsuhiko Maesato, Naohisa Hirao, Saori I. Kawaguchi, Shogo Kawaguchi, Yasuo Ohishi, Yoshiki Kubota, Hirokazu Kobayashi, Hiroshi KitagawaAbstract:We performed variable-temperature synchrotron powder X-ray diffraction measurements and impedance spectroscopy under pressure for Silver Iodide (AgI) nanoparticles with a diameter of 11 nm. The superionic conducting α-phase of AgI nanoparticles was successfully stabilized down to at least 20 °C by applying a pressure of 0.18 GPa, whereas the transition temperature was 147 °C in bulk AgI at ambient pressure. To our knowledge, this is the first example of the α-phase of AgI existing stably at room temperature.
Lulin Xue - One of the best experts on this subject based on the ideXlab platform.
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the dispersion of Silver Iodide particles from ground based generators over complex terrain part ii wrf large eddy simulations versus observations
Journal of Applied Meteorology and Climatology, 2014Co-Authors: Lulin Xue, Roy Rasmussen, Daniel Breed, Xia Chu, Bruce Boe, Bart GeertsAbstract:AbstractA numerical modeling study has been conducted to explore the ability of the Weather Research and Forecasting (WRF) model-based large-eddy simulation (LES) with 100-m grid spacing to reproduce Silver Iodide (AgI) particle dispersion by comparing the model results with measurements made on 16 February 2011 over the Medicine Bow Mountains in Wyoming. Xue et al.'s recently developed AgI cloud-seeding parameterization was applied in this study to simulate AgI release from ground-based generators. Qualitative and quantitative comparisons between the LES results and observed AgI concentrations were conducted. Analyses of turbulent kinetic energy (TKE) features within the planetary boundary layer (PBL) and comparisons between the 100-m LES and simulations with 500-m grid spacing were performed as well. The results showed the following: 1) Despite the moist bias close to the ground and above 4 km AGL, the LES with 100-m grid spacing captured the essential environmental conditions except for a slightly more...
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implementation of a Silver Iodide cloud seeding parameterization in wrf part ii 3d simulations of actual seeding events and sensitivity tests
Journal of Applied Meteorology and Climatology, 2013Co-Authors: Lulin Xue, Sarah A Tessendorf, Roy Rasmussen, S Parkinson, Eric E Nelson, Daniel Breed, Pat Holbrook, D BlestrudAbstract:AbstractFour cloud-seeding cases over southern Idaho during the 2010/11 winter season have been simulated by the Weather Research and Forecasting (WRF) model using the coupled Silver Iodide (AgI) cloud-seeding scheme that was described in Part I. The seeding effects of both ground-based and airborne seeding as well as the impacts of model physics, seeding rates, location, timing, and cloud properties on seeding effects have been investigated. The results were compared with those from Part I and showed the following: 1) For the four cases tested in this study, control simulations driven by the Real-Time Four Dimensional Data Assimilation (RTFDDA) WRF forecast data generated more realistic atmospheric conditions and precipitation patterns than those driven by the North America Regional Reanalysis data. Sensitivity experiments therefore used the RTFDDA data. 2) Glaciogenic cloud seeding increased orographic precipitation by less than 1% over the simulation domain, including the Snake River basin, and by up t...
Takayuki Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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disappearance of the superionic phase transition in sub 5 nm Silver Iodide nanoparticles
Nano Letters, 2017Co-Authors: Takayuki Yamamoto, Hiroshi Kitagawa, Hirokazu Kobayashi, L S R Kumara, Osami Sakata, Kiyofumi Nitta, Tomoya UrugaAbstract:Bulk Silver Iodide (AgI) is known to show a phase transition from the poorly conducting β/γ-phases into the superionic conducting α-phase at 147 °C. Its transition temperature decreases with decreasing the size of AgI, and the α-phase exists stably at 37 °C in AgI nanoparticles with a diameter of 6.3 nm. In this Letter, we investigated the atomic configuration, the phase transition behavior, and the ionic conductivity of AgI nanoparticles with a diameter of 3.0 nm. The combination of pair distribution function (PDF) analysis and reverse Monte Carlo (RMC) modeling based on high-energy X-ray diffraction (XRD) revealed for the first time that they formed the β/γ-phases with atomic disorder. The results of extended X-ray absorption fine structure (EXAFS) analysis, differential scanning calorimetry (DSC), and AC impedance spectroscopy demonstrated that they did not exhibit the superionic phase transition and their ionic conductivity was lower than that of crystalline AgI. The disappearance of the superionic ph...
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The Room-Temperature Superionic Conductivity of Silver Iodide Nanoparticles under Pressure
Journal of the American Chemical Society, 2017Co-Authors: Takayuki Yamamoto, Mitsuhiko Maesato, Naohisa Hirao, Saori I. Kawaguchi, Shogo Kawaguchi, Yasuo Ohishi, Yoshiki Kubota, Hirokazu Kobayashi, Hiroshi KitagawaAbstract:We performed variable-temperature synchrotron powder X-ray diffraction measurements and impedance spectroscopy under pressure for Silver Iodide (AgI) nanoparticles with a diameter of 11 nm. The superionic conducting α-phase of AgI nanoparticles was successfully stabilized down to at least 20 °C by applying a pressure of 0.18 GPa, whereas the transition temperature was 147 °C in bulk AgI at ambient pressure. To our knowledge, this is the first example of the α-phase of AgI existing stably at room temperature.
D Blestrud - One of the best experts on this subject based on the ideXlab platform.
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assessment of ground based and aerial cloud seeding using trace chemistry
Advances in Meteorology, 2018Co-Authors: D Blestrud, Melvin L Kunkel, S Parkinson, J Fisher, Marion Lytle, Nicholas Dawson, Ross Edwards, Shawn G BennerAbstract:Targeting seedable clouds with Silver Iodide in complex terrain adds considerable uncertainty in weather modification studies. This study explores the geographic and temporal distribution of Silver Iodide associated with an active cloud seeding program in central Idaho snowpack using trace chemistry. Over 4,000 snow samples were analyzed for the presence of a cloud seeding Silver Iodide (AgI) signature over two winter seasons. The results indicate the following. At sites within 70 km of AgI sources, Silver enrichments were detected at 88% of cases involving seeding efforts from ground generators, but none from aircraft seeded cases. Real-time snow collection methods were replicable within 0.41 ppt and confirmed seeding signatures for the entire duration of a seeded storm ( ). Sites sampled beyond 70 km of AgI sources ( ) lacked detectable seeding signatures in snow. The results of this study demonstrate some of the strengths and limitations of chemical tracers to evaluate cloud seeding operations and provide observational data that can inform numerical simulations of these processes. The results also indicate that this chemical approach can be used to help constrain the spatiotemporal distribution of Silver from cloud seeding efforts.
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implementation of a Silver Iodide cloud seeding parameterization in wrf part ii 3d simulations of actual seeding events and sensitivity tests
Journal of Applied Meteorology and Climatology, 2013Co-Authors: Lulin Xue, Sarah A Tessendorf, Roy Rasmussen, S Parkinson, Eric E Nelson, Daniel Breed, Pat Holbrook, D BlestrudAbstract:AbstractFour cloud-seeding cases over southern Idaho during the 2010/11 winter season have been simulated by the Weather Research and Forecasting (WRF) model using the coupled Silver Iodide (AgI) cloud-seeding scheme that was described in Part I. The seeding effects of both ground-based and airborne seeding as well as the impacts of model physics, seeding rates, location, timing, and cloud properties on seeding effects have been investigated. The results were compared with those from Part I and showed the following: 1) For the four cases tested in this study, control simulations driven by the Real-Time Four Dimensional Data Assimilation (RTFDDA) WRF forecast data generated more realistic atmospheric conditions and precipitation patterns than those driven by the North America Regional Reanalysis data. Sensitivity experiments therefore used the RTFDDA data. 2) Glaciogenic cloud seeding increased orographic precipitation by less than 1% over the simulation domain, including the Snake River basin, and by up t...
