bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of Power Efficiency in Organic Electroluminescent Devices
Authors: Ganzorig Chimed , Fujihira Masamichi 
Published: April 2011

ABSTRACTIn order to improve power efficiency of organic electroluminescent (EL) devices, i.e., ITO/TPD/Alq3/Al, enhanced electron and hole injection at Alq3/Al and ITO/TPD interface, respectively, was attempted by designing proper charge injection at both interfaces. Enhanced charge recombination at TPD/Alq3 was also demonstrated. Here, ITO, TPD, Alq3, and Al are abbreviations for indium-tin-oxide, N,N'-diphenyl-N,N'-bis(3-methyl-phenyl)-1,1'-biphenyl-4,4'-diamine, tris(8-hydroxyquinoline) aluminum, and metal aluminum, respectively. Enhanced electron injection by introducing a thin layer of Li salts of fluoride, acetate, and benzoate was described. We have found that the electron injection was improved in the order of Li+, Na+, K+, Rb+, and Cs+, and Cs salts exhibited the best EL performance. Chemical modification of ITO has been attempted to fine-tuning the work function of ITO in order to reduce hole injection barrier height. EL characteristics were improved dramatically using ITO modified with H-, Cl-, and CF3-terminated benzoyl chlorides. By using reactive -COCl groups, ITO surfaces were covered quickly and the work function of ITO was changed widely depending upon permanent dipole moments introduced in para-position of benzoyl chlorides. Correlation between the change in the work function of ITO and the EL characteristics was examined. The improvement of charge recombination was attained by increasing the interfacial areas, i.e. introducing a mixed layer of TPD and Alq3, or inserting a thin film of rubrene with a higher recombination efficiency.
Nano-Structure Control of Cathode Buffer-Layers and Luminescent Properties of Organic Electroluminescent Device
Authors: Shinbo K. , Sakai E. , Kaneko F. , Kato K. , Kawakami T. , Tadokoro T. , Ohta S. , Advincula R. C. 
Published: April 2011

ABSTRACTOrganic light emitting diodes (OLEDs) containing cathode buffer layers of nanometer thickness were fabricated and their electrical and emitting properties were investigated. The OLEDs have an indium tin oxide (ITO) anode/ copper phthalocyanine (CuPc) / N, N'-dephenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine (TPD) / 8- hydroxyquinoline aluminum (Alq3) / buffer layer / Al cathode structure with the buffer layers made from alternating thin films of Alq3 and Al with nanometer thickness. Improvement of driving voltage and the efficiency for the devices were observed by insertion of the buffer layer. It was estimated that some modulations of the Schottky barrier at the Alq3 and the Al cathode interface were induced due to the insertion of the buffer layer and it caused an enhancement of electron injection from the Al cathode. A model of the band structure at the buffer layer was proposed.
Multi-layer contacts for organic light-emitting diodes with enhanced injection efficiency
Authors: Bakueva Ludmila , Musikhin Sergei , Sargent Edward H. , Shik Alexander 
Published: April 2011

ABSTRACTA low level of electron injection is one of the major obstacles to achieving high-efficiency organic light-emitting diodes. With the goal of improving injection characteristics, we fabricated and investigated herein multi-layer contacts which included a tunnel-transparent dielectric layer of nanometer thickness. Polymer layers were prepared by the spin-coating method and dielectric and metallic contact layers grown by vacuum deposition. The voltage drop at this layer shifts the metal Fermi level relative to the polymer molecular orbitals responsible for the carrier transport, increasing the injection efficiency. The introduction of a suitably chosen dielectric layer results in an increase in the injection efficiency by up to a factor of several tens.Further sophistication of the injecting contacts consists in creating and additional intermediate thin metallic layer playing the role of the third, base electrode, similar to hot-electron transistors with metallic base. Additional bias applied to the base electrode permits variable injection efficiency and quantum yield over a wide range.
Novel Hybrid Covalent / Ionic Self-Assembly Technique for Improved Second-Order Nonlinear Optical Films
Authors: Neyman P. J. , Guzy M. , Shah S. M. , Davis R.M. , VanCott K. E. , Wang H. , Gibson H. W. , Brands C. , Heflin J.R. 
Published: April 2011

ABSTRACTIonically self-assembled monolayer (ISAM) films have been shown to spontaneously produce noncentrosymmetric ordering that gives rise to a substantial second order nonlinear optical (NLO) response. Typically, the ISAM films for NLO response are an assemblage of bilayers of oppositely charged polymers whose thickness can be controlled through variation of pH and ionic strength of the immersion solutions. Here, we investigate the effects of replacing the NLO-active polymer layers with layers of monomeric chromophores containing ionic and covalent bonding sites. Films fabricated exclusively using polyelectrolytes contain some fraction of both randomly oriented and anti-parallel oriented chromophores. We have examined the incorporation of monomeric chromophores into ISAM films in order to increase the net polar orientation of the chromophores and reduce bilayer thickness.
Conjugated polymers for thin film coating process
Authors: Tang Zhexiong , Li Wenguang , Nowak Cheryl , Yang Sze 
Published: April 2011

ABSTRACTIn this paper, we present the syntheses of the conjugated polymers of different “effective molecular weights.” The goal is to be able to optimize the thin film coating process without compromising the electronic, optical and electroactive properties.Our strategy for controlling the effective molecular weight is to synthesize a double-strand conducting polymer that is an inter-polymer complex of a polymeric dopant and a conjugated polymer. The first strand of the two-strand complex is either a polyaniline or a polypyrrole chain, while the second strand is a poly(acrylic acid). The molecular weight of poly(acrylic acid) is used as a parameter for adjusting the coating and film-forming properties.We found that the inter-polymer complexes are dispersible in water. The dispersion stability is strongly dependent on the molecular weight of the poly(acrylic acid) strand. The dispersion is more stable for polymers synthesized with higher molecular weight of poly(acrylic acid). We also found that the particle size and particle morphology are dependent on the effective molecular weight.
Enhanced Photovoltaic Response in Ionically Self-Assembled Monolayer Thin-Film Devices
Authors: Marciu Daniela , Miller Michael B. , Kozikowski Carrie , Heflin J. R. , Cho Sung , Reid Beth A. , Kuroda Kaori , Graupner Willi , Wang Hong , Gibson Harry W. , Davis Richey M. 
Published: April 2011

ABSTRACTWe describe detailed studies of ionically self-assembled monolayer (ISAM) photovoltaic (PV) devices incorporating various electron acceptor materials, such as fullerenes and phthalocyanines. Excitons are generated when the conducting polymer is irradiated, and the electron acceptors aid in dissociating the electron/hole pairs before they can radiatively recombine, thus improving the efficiency of the PV process. The ISAM technique allows the deposition of conducting polymer and electron acceptor materials in alternating layers of nanometer-scale thickness. This ensures that every photoexcited electron-hole pair is in proximity to an electron acceptor, thus minimizing electron-hole recombination and increasing the photocurrent. The individual thickness of each monolayer and the interpenetration of adjacent layers can be precisely controlled through the parameters of the electrolyte solutions. Using the ISAM technique, we have demonstrated that it is possible to create ultrathin films (100 nm) of PV material that have enhanced efficiencies.
Cesium Ion Implantation in Single Crystal Yttria-Stabilized Zirconia (YSZ) and Polycrystalline MgAl2O4-YSZ
Authors: Zhu S. , Zu X.T. , Wang L.M. , Ewing R.C. 
Published: April 2011

ABSTRACTYSZ and MgAl2O4-YSZ composite are two promising materials as in the inert matrix nuclear fuel for the incineration of plutonium. In this study, 400 keV Cs ions were implanted to a fluence of 1×1017 ions/m2 in both materials in order to investigate the retention behavior of fission product at elevated temperature. The implantations were completed at room temperature for the YSZ and 973 K for MgAl2O4-YSZ, respectively. Subsequent annealing at 1273 K was performed after a room temperature implantation of YSZ. After annealing, a high density of gas bubbles formed with diameter from 3 to 40 nm from the surface to a depth of 150 nm in the YSZ matrix. The swelling due to bubbles formation was estimated to be 2.5%. In situ TEM was employed during high temperature ion implantation of the MgAl2O4-YSZ composite. A high density of small bubbles with 5 nm in diameter formed in the MgAl2O4 and YSZ grains after an ion dose of 1×1017 ions/cm2. There was no preferential precipitation along grain boundaries. Electron Paramagnetic resonance (EPR) spectroscopy was used to investigate the type of defects that formed in the YSZ matrix.
Chemical Interactions in the Near-Field of a Spent Fuel Repository - Preliminary Results from a Long-Term Laboratory Experiment
Authors: Aalto H. , Carlsson T. , Kumpulainen H. , Lehikoinen J. , Muurinen A. 
Published: April 2011

ABSTRACTA ten-year-long laboratory experiment was recently started in order to study interactions between the groundwater, the bentonite, and the canister in the near-field of the planned Finnish repository for spent nuclear waste. The experimental set-up consists of a number of samples containing sodium MX-80 bentonite and cast iron cylinders placed in copper vessels. The bentonite stays in contact with an external solution, either distilled water or a 0.5 M NaCl solution, via metal sinters. The experiments are performed under anoxic conditions (N2 atmosphere) at ambient room temperature (∼30 °C). The experimental measurements focus mainly on the development of (1) the water chemistry, (2) the cast iron corrosion, and (3) the diffusion of corrosion products inside the bentonite, since these processes are the most likely ones to produce detectable changes during the ten-year-long programme.The first analyses, after 9 months, showed that the iron corrosion had started and that the corrosion products had migrated into the bentonite. The corrosion products could not be identified by XRD, which either meant that the material was amorphous or present in concentrations too low to be detectable. The analyses of the gas phase indicated the presence of hydrogen, which most probably was the result of the iron corrosion. The compositions of the external water and the porewater were determined with regard to the major species of interest. A closer evaluation of the results will not be given until more data are at hand.
Atmosphere Processing Effects on Titanate Ceramics Designed for Plutonium Disposition
Authors: Stewart M.W.A. , Vance E.R. , Jostsons A. , Finnie K. , Day R.A. , Ebbinghaus B.B. 
Published: April 2011

ABSTRACTBaseline formulation titanate ceramics for surplus Pu disposition are based upon a target mineralogy of 95 wt.% pyrochlore (Ca0.89Gd0.22Hf0.23Pu0.22U0.44Ti2O7) plus 5 wt.% Hf-doped rutile (∼ Ti0.9Hf0.1O2), where Ce is used as an analogue for Pu and U, and Th for Pu. Typically, Pu/U, Th/U and Ce/U-baseline samples form major pyrochlore, plus minor brannerite (AnTi2O6) and rutile. Ce/Ce-baseline ceramics were similar but did not form brannerite. Sintering in air produced more U5+ in the ceramics than sintering in Ar. In the pyrochlore the charge compensation for U5+ principally occurred by an increase in Ca2+ and decrease in Ti4+ and Th4+. In the matrix these phase compositional changes result in an increase in brannerite content of the ceramic at the expense of pyrochlore in the air sintered ceramic relative to the Ar sintered sample. Sintering in reducing 3.7% H2 in Ar atmospheres eliminates the brannerite and rutile and results in 2M-zirconolite and perovskite in addition to the major pyrochlore phase. Varying the sintering temperature between 1250°C and 1400°C had little effect on the phase chemistry other than slightly incomplete reactivity of coarse actinide oxide at the lower sintering temperatures and a general increase in density (to ∼ 1350°C) and grain size with increased sintering temperatures. Th4+ appears to be a good analogue for Pu4+ from a crystal chemistry aspect.
The Use of Cerium Valence State for Evaluation of Accessory Minerals Durability to Radiation Damage
Authors: Bogdanov Roman V. , Zaytsev Yuri M. , Sergeev andrey S. 
Published: April 2011

ABSTRACTCerium-actinide bearing natural minerals which demonstrate their long-time physicochemical durability under the environment effect would be considered as analogues of actinide ceramic waste forms. Radiation damage of crystalline materials causes oxidation of cerium from initial Ce(III) to Ce(IV). Therefore, cerium valence state in actinide-cerium bearing natural minerals in some cases reflects the resistance of such minerals to radiation damage. Cerium valence state was determined in the following natural minerals of similar age and similar U-Th-contents: monazite (four samples), britholite (two samples), and aeschynite (one sample). The method of chemical shifts of X-ray emission (CeKá1 line) was used. The following contents of Ce(IV) were observed: more then 30 % in britholite, 11 % in aeschynite, 0 % in monazite. The results obtained suggest that durability of these actinide host phases with respect to radiation damage decreases in the monazite-aeschynite-britholite series.
Effects of Heavy Metal Ions on Corrosion of Titanium Grade 7 In Concentrated Groundwaters
Authors: Pulvirenti April L. , Needham Karen M. , Adel-Hadadi Mohammad A. , Marks Charles R. , Gormana Jeffery A. , Barkatt Aaron. 
Published: April 2011

ABSTRACTA Titanium Grade 7 (Ti-7) drip shield is being considered for use in the potential nuclear waste repository at Yucca Mountain, Nevada. The purpose of the drip shield is to keep water from reaching the surfaces of the canisters containing nuclear waste. Among the species that may be expected to be present in the water are heavy metals. This paper explores the effects of five species, lead, mercury, cadmium, tin and sodium, on the dissolution rate of Ti-7. The results of these tests indicated that lead, mercury, cadmium and tin ions do not significantly accelerate the general corrosion of Ti-7 under the conditions studied. A highly concentrated solution of NaOH was found to cause significant dissolution of Ti-7. Such a solution is a reasonable approximation of possible service environments.
Alteration-Phase formation and Associated Cesium Release During Alteration of R7T7 Waste Glass
Authors: Inagaki Y. , Idemitsu K. , Arima T. , Maeda T. , Ogawa H. , Itonaga F. 
Published: April 2011

ABSTRACTStatic corrosion tests were performed with an inactive HLW glass of R7T7 type in order to evaluate alteration-phase formation and associated Cs release during the glass corrosion. The tests were performed in NaOH solutions at elevated temperatures in order to accelerate the corrosion. Crystalline phases formed in the corroded glass were analyzed by use of XRD, in addition to the solution analysis. The results indicated that; 1)Analcime or Na-beidellite or both of them form during the corrosion depending on the conditions, 2)Si rich amorphous phases are contained in the alteration-phases, 3)In addition to solution pH, solution concentrations of Na and K sensitively affect formation of analcime and Na-beidellite, 4)Analcime formation accelerates the glass corrosion, 5)Most of Cs in the glass is retained in the alteration-phases by sorption onto Na-beidellite or incorporation into amorphous phases and pollucite
Assessment of Spent Fuel of Alfa Class Nuclear Submarines
Authors: Bugreev M.I. , Efimov E.I. , Ignatiev S.V. , Pankratov D.V. , Tchitaykin V.I. 
Published: April 2011

ABSTRACTAt present spent nuclear cores from Alfa class submarines are being stored in temporary facilities, designed to sore them only for a few years (3 to 5 years). This paper assesses the problems of nuclear safety during long-term unplanned forced storage of spent fuel because of the delay in building permanent facilities. The Nuclear Submarines (NS) cores use heavy liquid metal lead-bismuth coolant in the primary circuit of nuclear reactor. The radiation parameters of the discharged cores from NS of the Project 705K (this is the number of ship engineering design) are determined. Based on that determination a step-by-step solution is proposed and the technological and other challenges that the Project faces are considered.
Release of Neptunium, Plutonium, Uranium and Technetium from the Metallic Waste form from the Electrometallurgical Treatment Process
Authors: Johnson S. G. , Noy M. , DiSanto T. , Barber T. L. 
Published: April 2011

ABSTRACTThis waste form is an alloy consisting of stainless steel with 15 wt% zirconium and acts as a host for the immobilization of radioelements that remain with the spent fuel cladding hulls following their treatment using an electrometallurgical treatment process. The results presented here are from 14, 34 and 90-day immersion tests conducted at 90 °C. These tests show that the release of uranium is considerably higher than that of all other major elements present (Fe, Cr, Ni, Zr), but that release of all constituents is comparable to or lower than that for borosilicate glass.
X-ray Absorption Studies of Vanadium Valence and Local Environment in Borosilicate Waste Glasses
Authors: McKeown David A. , Muller Isabelle S. , Matlack Keith S. , Pegg Ian L. 
Published: April 2011

ABSTRACTXANES and EXAFS data were collected and analyzed to characterize vanadium in borosilicate glasses used for immobilization of sulfur-containing nuclear wastes. Earlier studies suggested that adding vanadium to the melt improves sulfur solubility. Data are presented for a variety of borosilicate glasses, some containing sulfur and some sulfur-free, that have V2O5 concentrations as high as 12 wt%, and for crystalline vanadium sulfide, silicate, and oxide standards. The data for all glasses investigated indicate that most or all vanadium has a +5 valence and is tetrahedrally coordinated by oxygen atoms. Both XANES and EXAFS also show that glasses synthesized under reducing conditions can have pentacoordinated V+4 populations up to approximately 20 to 25% of all vanadium present with the remainder being V+5O4. There is no evidence from XANES or EXAFS of V-S bonds in any of the glasses investigated.
The SR 97 Safety Assessment of a KBS 3 Repository for Spent Nuclear Fuel – Overview, Review Comments and New Developments
Authors: Hedin Allan , Kautsky Ulrik , Morén Lena , Sellin Patrik , Selroos Jan-Olof 
Published: April 2011

ABSTRACTIn preparation for coming site investigations for siting of a deep repository for spent nuclear fuel, the Swedish Nuclear Fuel and Waste Management Company, SKB has carried out the longterm safety assessment SR 97, requested by the Swedish Government. The repository is of the KBS-3 type, where the fuel is placed in isolating copper canisters with a high-strength cast iron insert. The canisters are surrounded by bentonite clay in individual deposition holes at a depth of 500 m in granitic bedrock. Geological data are taken from three sites in Sweden to shed light on different conditions in Swedish granitic bedrock.The future evolution of the repository system is analysed in the form of five scenarios. The first is a base scenario where the repository is postulated to be built entirely according to specifications and where present-day conditions in the surroundings, including climate, persist. The four other scenarios show the evolution if the repository contains a few initially defective canisters, in the event of climate change, in the event of earthquakes, and in the event of future inadvertent human intrusion.The principal conclusion of the assessment is that the prospects of building a safe deep repository for spent nuclear fuel in Swedish granitic bedrock are very good. The results of the assessment also serve as a basis for formulating requirements and preferences regarding the bedrock in site investigations, for designing a programme for site investigations, for formulating functional requirements on the repository's barriers, and for prioritisation of research.SR 97 has been reviewed both by an international group of OECD/NEA experts and by Swedish authorities. The NEA reviewers concluded that “SR 97 provides a sensible illustration of the potential safety of the KBS-3 concept”, and no issues were identified that need to be resolved prior to proceeding to the investigation of potential sites. The authorities' conclusions were in principal consistent with those of the NEA.Uncertainties and lack of knowledge in different areas identified in SR 97 have strongly influenced the contents and structure of SKBs most recent research programme, RD&DProgramme 2001.Since SR 97, the methodology for probabilistic consequence analyses have been further developed. Analytic approximations to the numerical transport models used in SR 97 have been developed. The new models have been used to extend the probabilistic calculations in SR 97.
Properties of Plutonium-Containing Colloids Released from Glass-Bonded Sodalite Nuclear Waste form
Authors: Morss Lester R. , Mertz Carol J. , Kropf A. Jeremy , Holly Jennifer L. 
Published: April 2011

ABSTRACTIn glass-bonded sodalite, which is the ceramic waste form (CWF) to immobilize radioactive electrorefiner salt from spent metallic reactor fuel, uranium and plutonium are found as 20-50 nm (U,Pu)O2 particles encapsulated in glass near glass-sodalite phase boundaries. In order to determine whether the (U,Pu)O2 affects the durability of the CWF, and to determine release behavior of uranium and plutonium during CWF corrosion, tests were conducted to measure the release of matrix and radioactive elements from crushed CWF samples into water and the properties of released plutonium. Released colloids have been characterized by sequential filtration of test solutions followed by elemental analysis, dynamic light scattering, transmission electron microscopy (TEM), and X-ray absorption spectroscopy. This paper reports the composition, size, and agglomeration of these colloids. Significant amounts of colloidal, amorphous aluminosilicates and smaller amounts of colloidal crystalline (U,Pu)O2 were identified in test solutions. The normalized releases of uranium and plutonium were significantly less than the normalized releases of matrix elements, i.e., the CWF retains these radionuclides well.