bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Situ X-Ray Diffraction and In Situ X-Ray Absorption Spectroscopy for Investigation of Intercalation Batteries: Application to the Alkaline H+/γ-MnO2 system.
Authors: Lévy-Clèment C. , Mondoloni C. , Godart C. , Cortès R. 
Published: March 2011

AbstractThis paper presents applications of in situ X-ray diffraction and absorption techniques to the study of H+/MnO2 alkaline batteries. The two complementary in situ techniques are described. Investigation of the electrochemical insertion and deinsertion of H+ has been made through its influence on the evolution of the crystallographic structure of γ-MnO2, while investigation of the transfer of e has been undertaken through the variation of the oxidation state of the manganese during the discharging and charging process of a battery. New insights in the understanding of the mechanisms of proton insertion and charge transfer into γ-MnO2 are discussed.
Montmorillonite (MONT) Complex and their Application
Authors: Wenhai Yu , Wanyu Liu 
Published: March 2011

AbstractMontmorillonite(Mont) has been proved to be a kind of very promising solid electrolyte in recent years because of its good electric properties. It can be composed by polymer to prepare a mont-polymer complex which has high ionic conductivity and excellent plasticity. The film made of mont-polymer complex with room temperature ionic conduction has been used in solid state battery as solid electrolyte. It may be a new type of function material with futher application.
Mixed Ionic Electronic Conduction in Solids
Authors: Riess I. 
Published: March 2011

AbstractChemical diffusion in mixed ionic electronic conductors (MIECs) occurs via ambipolar motion. It finds many applications which are reviewed. The partial ionic and electronic conductivities are also of interest. Methods for determining these quantities are reviewed emphasizing problems with the Hebb-Wagner polarization method and suggesting an alternative method. The use of MIECs for probing simultaneously the ionic and electronic driving forces and for producing p-n junctions is discussed.
Microstructural Design and Conductivity and Ultrasonic Activation in the Ion Exchange of H3O+ and NH4+β"-Aluminas
Authors: Nicholson Patrick S. 
Published: March 2011

AbstractH3O+- and NH4 + -A12O3 polycrystals have been conductivity-optimised by eliminating metastable grain-boundary phases (NaA1O2 and MgAl2O4) and texturing the microstructure. The grain-boundary conductivity is considerably improved (up to 5x10-5(Ω-cm)-i) from 10–6 (Ω-cm)-l). The dc-field-assisted, H3O+ ion exchange process for K+/Na+-β"-A12O3 in HAC has been accelerated by cyclic switching of the dc field (cycle = 3secs) or injecting ultrasonic energy. The formeroubles the steady-state ion-exchange current to 12 μA by dispersing the HAC/electrolyte, interfacial, H3O+ polarisation layer. The ion-exchange currentefficiency is not improved from 0.15. The ultrasound (23 MHz) markedly shortens the time to complete ion-exchange (400 hrs.vs. > 700 hrs), more than doubles the final ion-exchange current (360 μA.vs. 150 μA) and improves the ion-exchange current efficiency to 0.24. These results are interpreted in terms of ionic “activation ”in the electrolyte. Evidence is presented of a mixed-cation-effect in H3O+-K-β"-AI2O3.
Electrochromic Properties of Nickel Oxide Electrodes
Authors: Pileggi R. , Scrosati B. , Passerini S. 
Published: March 2011

AbstractNickel oxide sputtered electrodes can undergo a reversible lithium intercalationdeintercalation process which is accompanied by a net electrochromic effect. The characteristics of this type of electrode and the mechanism of the related electrochromic process are discussed on the basis of results obtained by cyclic voltammetry and optical transmittance. The results show that nickel oxide is electrochromically activated by insertion of lithium in the oxide structure. The lithium intercalation process may be promoted by cyclic voltammetry or, more extensively, by polarizing cathodically the nickel oxide electrode in a non-aqueous electrolyte containing a lithium salt. Activated nickel oxide electrodes are of considerable interest for the realization of new types of efficient solid state electrochromic windows..
High Frequency and Solid State NMR Techniques for the Study of Ionically Conductive Glasses
Authors: Kennedy John H. , Zhang Zhengming , Eckert Hellmut 
Published: March 2011

AbstractThe synthesis, characterization, and electrochemical properties of sulfide-based lithiumglasses are briefly reviewed. Of the many probes that have been used to study these materials two will be discussed in more detail, namely solid state NMR and conductivity measurements at high frequency (106-109 Hz). Solid state NMR is particularly useful in understanding the network structure of these glasses and the role coformers play in modifying the glass network. Electrochemical measurements, including impedance at high frequency, give information concerning dynamic processes, and show that someof these glasses are potentially useful in miniature and thin-film solid state batteries.
A Study of Ag+-Ion Dynamics in Ag2S-GeS2 Glasses
Authors: Owens A.P. , Pradel A. , Ribes M. , Elliott S.R. 
Published: March 2011

AbstractA quasi-elastic neutron scattering (QENS) study of the Ag+-ion diffusion coefficient, D, in glassy (Ag2S)0.5 (GeS2)0.5 has been performed. The results indicate that the magnitude of D is larger, and its activation energy is smaller, than the corresponding quantities inferred from measurements of the d.c. ionic conductivity. This behaviour is ascribed to the fact that QENS probes diffusive processes occurring at very high frequencies (∼1011Hz) where the magnitude of the a.c. conductivity is correspondingly larger, and its temperature dependence is less, than that of the d.c. conductivity.
Structure and Ionic Conductivity of Lithio-Borate Thin Films
Authors: Dzwonkowski P. , Eddrief M. , Julien C. , Balkanski M. 
Published: March 2011

AbstractThin films of vitreous solid electrolyte in the boron-oxide/lithium oxide system have been grown using a thermal evaporation technique. Solid electrolyte films of composition B2O3-xLi2O with 0.5≤x≤5 are obtained from a mixture of lithium metaborate and lithium oxide in good proportion. Structure and ionic conduction are studied as a function of the glass modifier concentration and process conditions. The structure is investigated by the mid-infrared absorption spectroscopyof films deposited on a silicon wafer. Comparison with bulk materials whose structures are known shows that the films have a similar structure, and exhibit the transformation of boroxol rings into triborate or di-triborate units as the Li2O concentration increases. The ionic conductivity has been studied over wide frequency and temperatureranges using the complex impedance spectroscopy in a sandwiched geometry. The ionic conductivity increases with increasing Li content and exhibits a maximum value for B2O3-3Li2O.
A.C. Impedance and Transport Number Measurements of Ba6 Ta2O11
Authors: Goto Takashi , West A.R. 
Published: March 2011

AbstractBa6Ta2O11 with an oxygen—deficient perovskite—related structure, was prepared through solid state reaction of BaCO3 and Ta2O5 powders. The electrical conductivity of sintered Ba6Ta2O11 pellets was measured by a.c. impedance spectroscopy inthe temperature range between 200 and 800ºC. The conductivity at 800ºC was3.7x10-3 Ω-1 cm-1; the activation energy for bulk conduction was 0.93 eV at temperatures between 500 and 800ºC and 1.22 eV below 500ºC. The bulk conductivity was independent of atmosphere, while the grain boundary conductivity, with an activation energy of 1.08 eV, decreased as oxygen partial pressure increased. The oxygen ion transport number obtained from concentration cell measurements was 0.5 to 0.65 at temperatures from 450 to 820ºC.
Evaluation of Variously Doped BaCeO3 Ceramics as Protonic Conductors
Authors: Liu J.F. , Nowick A.S. 
Published: March 2011

AbstractNd—doped BaCeO3 is reported to be an excellent high—temperatureprotonic conductor, while the Gd—doped material is not. In order to better understand the role of different dopants, we have studied BaCeO3 doped with 5 mol% of each Nd3+, Eu3+, Gd3+, Yb3+ and Ca2+. In each case samples were treated in an appropriate gas atmosphere at 900ºC followed by measurement from 25 to 200ºC in a “frozen—in”state. Protonic conduction was deduced from the isotope effect, i.e. comparing conductivity after treatment in D2O—saturated gas with that for H20,as well as by the change between wet and dry treatments. In addition, we measured H2O uptake by observing the weight change between wet and dry treatments, and also carried out some galvanic cell measurements. It was concluded that, of the above dopants, only Nd and Ca give rise to appreciable protonic conduction. In the Nd case, the low activation energy of 0.54 eV is probably the proton hopping energy. On the other hand, Eu, Gd and Yb—doped materials appear to show the dominance of oxygenion conduction in the low temperature range and mixed oxygen—ion and electron—hole conductivity at elevated temperatures. The most likely reason for these differences seems to be centered on the ionic radii of the dopants.
The Effect of Sample Preparation Methods on Glass Performance
Authors: Oh M. S. , Oversby V.M. 
Published: March 2011

ABSTRACTA series of experiments was conducted using SRL 165 synthetic waste glass to investigate the effects of surface preparation and leaching solution composition on the alteration of the glass. Samples of glass with as-cast surfaces produced smooth reaction layers and some evidence for precipitation of secondary phases from solution. Secondary phases were more abundant in samples reacted in deionized water than for those reacted in a silicate solution. Samples with saw-cut surfaces showed a large reduction in surface roughness after 7 days of reaction in either solution. Reaction in silicate solution for up to 91 days produced no further change in surface morphology, while reaction in DIW produced a spongy surface that formed the substrate for further surface layer development. The differences in the surface morphology of the samples may create microclimates that control the details of development of alteration layers on the glass; however, the concentrations of elements in leaching solutions show differences of 50% or less between samples prepared with different surface conditions for tests of a few months duration.
Effects of Heat Treatment on the Microstructure of a Fully Simulated Nuclear Waste Glass
Authors: Palmiter Terese V. , Joseph I. , David Pye L. 
Published: March 2011

ABSTRACTSamples of a fully simulated nuclear waste glass under consideration for use in the West Valley Demonstration Project were isothermally heat treated and studied by scanning transmission electron microscopy (STEM). Both fully oxidized and partially reduced specimens were heat treated for 3 hours at 600°C, 700°C, 800°C and 900°C and for 45 days at 10°C above Tg (447°C -461°C) and at 10°C below TB (427°C -441°C). Microstructural features in untreated as well as the heat-treated glasses were studied using STEM. Analysis by energy dispersive spectroscopy (EDS) was used to identify the elemental compositions of the features observed.The predominant crystalline phase present in the samples heat treated for 3 hours was an Fe3O4 type spinel with Ni and Cr substituting for some of the Fe. The spinels varied in size from 0.02 to 10.0 µm, the larger crystals present at higher heat-treatment temperatures. Long term heat treatment above Tg resulted in the formation of small iron-containing crystals ranging in size from 10 to 35 nm. Heat treatment below Tg produced no crystalline or amorphous phases.
Results from Long-Term Dissolution Tests Using Oxidized Spent Fuel
Authors: Wilson Charles N. 
Published: March 2011

ABSTRACTTwo semi-static dissolution tests using oxidized PWR spent fuel specimens are being conducted under ambient hot cell conditions in Nevada Test Site J-13 well water and unsealed fused silica vessels. The test specimens were oxidized at 250°C in air to bulk oxygen-to-metal (O/M) values of 2.21 and 2.33. Following an initial 191-day test cycle, the specimens were restarted in fresh J-13 water for a second long-term test cycle. Results through the first 40 months of Cycle 2 are compared with results from similar tests at 25°C and 85°C using unoxidized spent fuel specimens.Increased concentrations of U, Am, Cm and Np were measured in 0.4- μm filtered samples from the oxidized fuel tests compared to the unoxidized fuel tested at 25°C; Pu concentrations were not affected by the fuel oxidation state. Most of the Am and Cm, and a portion of the Pu, measured in 0.4-μm filtered samples was removed by 2-nm filtration. Fission product release results were normalized to specimen inventories and reported as fractional release. No attempt was made to normalize the data to surface area. Initial 99Tc release was greatly increased, and prolonged increases in the fractional release rates of 99Tc and 129I occurred as a result of fuel oxidation. Fractional release rates for 137Cs and 90Sr from oxidized fuel eventually decreased to levels similar to those observed with unoxidized fuel after equivalent testing times, suggesting that matrix dissolution rates normalized to fuel mass were not increased as a result of oxidation.
The Critical Condition for the Initiation of Localized Corrosion of Mild Steel Used for Nuclear Waste Package
Authors: Nakayama Gen , Akashi Mastsuna 
Published: March 2011

ABSTRACTThe general corrosion rate of mild steel is so small in neutral water environments that adequately provided corrosion allowance can ensure the requirement of one thousand years’ integrity of geological disposal package of high-level nuclear wastes. In alkaline water environments, however, mild steels can passivate themselves and often undergo localized corrosion in much the same manner stainless steels do in neutral water environments. This paper describes a study of localized corrosion behavior of the mild steel conducted to assess the long-term performance of the disposal packages. The critical potentials for pitting and crevice corrosion and critical pH for general corrosion-to-passivity transition were determined for neutral and alkaline water environments. Effects of temperature, pH, and chloride and other anion concentrations on the critical potentials and the critical pH were discussed. The initiation and propagation behavior of crevice corrosion was also analyzed under potentiostatic conditions.
Near Field Performance of the Advanced Cold Process Canister
Authors: Werme Lars O. , Salo Jukka-Pekka 
Published: March 2011

ABSTRACTA near-field performance evaluation of an advanced cold process canister for spent nuclear fuel has been performed jointly by TVO, Finland and SKB, Sweden. The canister consists of a carbon steel canister as a load bearing element, with an outer corrosion shield of copper. The canister design was originally designed by TVO. In the analysis, internal (ie corrosion processes from the inside of the canister) as well as external processes (mechanical and chemical) have been considered both prior to and after canister breach. Throughout the analysis, present day underground conditions have been assumed to persist during the service life of the canister.
Modeling Geochemical Stability of Cement Formulations for use as Shaft Liner and Sealing Components at Yucca Mountain(1)
Authors: Gardiner Mark A. , Hinkebein Thomas E. , Myers Jonathan 
Published: March 2011

ABSTRACTThe geochemical modeling codes EQ3NR/EQ6 were used to model the interaction of cementitious materials with ground water from the Yucca Mountain proposed nuclear waste repository site in Nevada. This paper presents a preliminary estimate of the compositional changes caused by these interactions in the ground water and in the cement-based compounds proposed for use as sealing and shaft liner materials at the Yucca Mountain site.
Application of Elasto-Plastic Model to Mechanical and Hydraulic Behavior of Buffer Material Under Water Uptake in a Repository
Authors: Fujita T. , Hara K. , Yusa Y. , Sasaki N. 
Published: March 2011

ABSTRACTMechanical and hydraulic behavior of buffer material during water uptake in a repository is a major issue from the viewpoint of mechanical stability of engineered barriers and near-field conditions for performance assessment. This paper presents the results of hydraulic-mechanical modeling of buffer material and the simulations carried out on an engineered barrier system under water uptake.Hydraulic behavior of compacted bentonite of buffer material was modeled as moisture diffusion. An elasto-plastic model was applied to the deformation behavior of compacted bentonite, of which swelling pressure was described by swelling coefficient under restraint condition. The hydraulic diffusivity and swelling coefficient were given based on the result of swelling tests of KUNIGEL-V1 bentonite which contains about 50 % montmorillonite. Being used this model, simulations on re-saturation behavior of an engineered barrier system were carried out for the cases of water uptake from the whole surface of both crystalline and sedimentary rock and from partial surface of opening. The results are : (1) The hydraulic and mechanical behavior of compacted bentonite can be described by a swelling-elasto-plastic model. (2) The distribution of the water content depends on the water uptake conditions. (3) The deformation of compacted bentonite and the displacement of the overpack under water uptake are negligibly small.
Coupled Thermo-Hydraulic Behavior Around Access Shaft Sealed with Backfill Material
Authors: Okamoto J. , Ishihara K. , Sawauchi Y. , Hara K. , Sasaki N. 
Published: March 2011

ABSTRACTGroundwater flow from the repository to the surface through the sealed access shaft may be induced by the heat generated from high-level radioactive waste(HLW). It is important to estimate the effect of this heat generation on groundwater flow.This paper presents an evaluation of groundwater flow in the vicinity of an access shaft filled with a backfill material. The evaluation uses a coupled thermo-hydraulic model. According to the current design, the backfill material within the shaft will be tamped 5 to 15 times every 20 cm depth using a 60 kg vibrating compactor. The properties of the backfill material were determined from experimental results for this construction method.A transient coupled thermo-hydraulic analysis was carried out using an axisymmetric FEM model. Two kinds of repository models were considered, one was a single layered repository located at 1000 m depth, and the other was a two layered repository located at 800 m and 1000 m depths. The access shaft of each model was located at the center of the repository.The results show that the vertical hydraulic gradient of groundwater flow along the sealed shaft will be approximately 0.001 at a time 1000 years after closure of the repository.
Remote Measurements of Actinide Species in Aqueous Solutions Using an Optical Fiber Photoacoustic Spectrometer
Authors: Russo Richard E. , Robouch Piotr B. , Silva Robert J. 
Published: March 2011

ABSTRACTA photoacoustic spectrometer, equipped with an 85 meter optical fiber, was used to perform absorption measurements of lanthanide and actinide samples, located in a glovebox. The spectrometer was tested using aqueous solutions of praseodymium and americium ions; the sensitivity for remote measurements was found to be similar to that achieved in the laboratory without the fiber.
Development of High-Temperature Uv-Vis-Nir Spectroscopy for the Measurement of Free Energies of Complexation at Elevated Temperatures
Authors: Robouch Piotr , Grant Pat , Torres Richard A. , Baisden P. A. , Silva R. J. 
Published: March 2011

ABSTRACTWe have developed instrumentation capable of measuring optical absorption spectra over a wavelength range of 200–1200 nm and a temperature range of 20–100°C. This fiber-optic based spectrometer generates data which allow the computation of metal-ligand equilibrium constants. Studies at five temperatures have been completed using praseodymium-diglycolate as a model system. Fundamental thermodynamic values (free energies, enthalpies, entropies) were obtained from the experimentally-determined stability constants.
Actinide Transport in Topopah Spring Tuff: Pore Size, Particle Size, and Diffusion
Authors: Buchholtz Ten Brink Marilyn , Phinney Douglas L. , Smith David K. 
Published: March 2011

ABSTRACTDiffusive transport rates for aqueous species in a porous medium are a function of sorption, molecular diffusion, and sample tortuosity. With heterogeneous natural samples, an understanding of the effect of multiple transport paths and sorption mechanisms is particularly important since a small amount of radioisotope traveling via a faster-than-anticipated transport path may invalidate the predictions of transport codes which assume average behavior. Static-diffusion experiments using aqueous 238U tracer in tuff indicated that U transport was faster in regions of greater porosity and that apparent diffusion coefficients depended on the scale (mm or μm) over which concentration gradients were measured in Topopah Spring Tuff. If a significant fraction of actinides in high-level waste are released to the environment in forms that do not sorb to the matrix, they may be similarly transported along fast paths in porous regions of the tuff. To test this, aqueous diffusion rates in tuff were measured for 238U and 239Pu leached from doped glass. Measured transport rates and patterns were consistent in both systems with a dual-porosity transport model In addition, filtration or channelling of actinides associated with colloidal particles may significandy affect the radionuclide transport rate in Topopah Spring tuff.
Waste Storage in the Vadose Zone Affected by Water Vapor Condensation and Leaching
Authors: Cary John W. , Gee Glendon W. , Whyatt Greg A. 
Published: March 2011

ABSTRACTOne of the major concerns associated with waste storage in the vadose zone is that toxic materials may somehow be leached and transported by advecting water down to the water table and reach the accessible environment through either a well or discharge to a river. Consequently, care is taken to provide barriers over and around the storage sites to reduce contact between infiltrating water and the buried waste form. In some cases, it is important to consider the intrusion of water vapor as well as water in the liquid phase. Water vapor diffuses through porous material along vapor pressure gradients. A slightly lower temperature, or the presence of water-soluble components in the waste, favors water condensation resulting in leaching of the waste form and advection of water-soluble components to the water table. A simple analysis is presented that allows one to estimate the rate of vapor condensation as a function of waste composition and backfill material. An example using a waste form surrounded by concrete and gravel layers is presented. The use of thermal gradients to offset condensation effects of water-soluble components in the waste form is discussed. Thermal gradients may be controlled by design factors that alter the atmospheric energy exchange across the soil surface or that interrupt the geothermal heat field.Work supported in part by U.S. Department of Energy, OHER, Contract DE-AC06-76RL0 1830