bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabricating of Diatomite Based Ceramic Water Filter by a Novel Casting Method
Authors: Anil Umit Engin , Al Ebru , Kayaci Kagan , Kara Ferhat
Published: October 2014

In this study, a ceramic water filter with micron sized pores was developed based on diatomite raw material. The slip with diatomite earth which has tubular shaped particles was prepared by using agar. Agar is a gelatinous material derived from sea alges and used as a gelling agent in order to form ceramic filters by gel casting method. Rheology of the slip was investigated by rheometry. In the forming process, polymer and metal molds were used instead of plaster molds. After de-molding, ceramic filter samples were dried and fired at 1200 °C/ h for 2 hours. Density, phase analysis and microstructure properties of porous diatomite based filter material were measured and characterized by He picnometer, XRD and SEM, respectively. Water filtration performance and microbiological test results were also investigated.
Evaluating Porosity in Cordierite Diesel Particulate Filter Materials: Advanced X-Ray Techniques and New Statistical Analysis Methods
Authors: Kupsch Andreas , Lange Axel , Hentschel Manfred P. , Onel Yener , Wolk Thomas , Staude Andreas , Ehrig Karsten , Müller Bernd R. , Bruno Giovanni
Published: October 2014

Bi-continuous porous ceramics for filtration applications possess a particularly complicated microstructure, whereby porosity and solid matter are intermingled. Mechanical, thermal, and filtration properties can only be precisely estimated if the morphology of both solid matter and porosity can be quantitatively determined. Using 3D computed tomography (CT) at different resolutions, and several X-ray refraction-based techniques, we quantitatively evaluated porosity and pore orientation in cordierite diesel particulate filter ceramics.Moreover, applying both Fast Fourier Transform (FFT) and a newly developed image analysis algorithm (directional interface variance analysis, DIVA), we quantitatively evaluated porosity and pore orientation. Both the experimental techniques and the statistical approach allow extraction of spatially resolved or average values.Porosity values from synchrotron computed tomography used turn out to agree with mercury intrusion measurements, while pore orientation factors agree with published crystallographic texture data. This latter point also implies that the study of the pore/matter interface is sufficient to describe the morphological properties of these materials.
Al2O3 Preforms with Gradient Porosity for Brake Disk Application
Authors: Strojny-Nedza Agata , Pietrzak Katarzyna , Chmielewski Marcin , Jach Katarzyna
Published: October 2014

It has been known for many years that the incorporation of metallic particulates into a ceramic matrix can bring about the improvement of the mechanical properties of ceramics. Alumina/copper composites are well-known for their good frictional wear resistance, high resistance to thermal fatigue, high thermal conductivity as well as high absorption and dissipation of heat. The combination of the properties offered by alumina-copper composites makes them particularly interesting for wear applications in both automobile and aerospace industries. In the present paper we report on the design and production of a new class of alumina-copper functionally graded materials (FGM) which have technological potential for application in automotive brake disks. More specifically, this work deals with the development of the interpenetrating network structure of the FGM material. The manufacturing procedure was based on the gas-pressure infiltration of graded porous alumina preforms by liquid copper. The graded porous ceramic preforms with porosity ranging between 20 and 60% were made by casting foils made from slurries, the main components of which were alumina powder and rice starch powder (a pore forming agent), laminating these foils, subsequently burning-out the starch and last but not least performing a sintering process. A fundamental part of the presented investigations was to correlate the grain size of the alumina powders (Almatis, HVA FG and CT 1200 SG) and the pore size distribution, microstructure and selected mechanical and thermal properties of the porous ceramic preforms.
Nanocomposite Photocatalyst Based on Layered Double Hydroxides (LDHs) Associated with TiO2
Authors: Ranogajec Jonjaua , Sever-Skapin Andrijana , Rudic Ognjen , Vucetic Snezana
Published: October 2014

The surfaces of building materials are constantly exposed to the actions of environmental factors, pollutants of inorganic and organic origin as well as to microorganisms, which significantly contribute to corrosion phenomena.The application of coatings decreases the negative action of the pollutants minimizing their direct contact with the substrate. Different types of coatings with additional functions have been developed. A specific problem of these applications is the lack of compatibility of the photocatalysts with the surface of the building materials and the detachment of potentially toxic TiO2 nanoparticles. In the present study, this problem was solved by the proper immobilization of TiO2 nanoparticles onto the photocatalyst support, layered double hydroxides (LDHs). The newly formed coating possesses acceptable porosity for a porous building material (porosity within the range of 30-46 %) and satisfied photocatalytic activity, as well as mineralogical compatibility with the substrates (mortars, renders, bricks). Additionally, a positive effect considering the self-cleaning phenomenon was attained.
Development of a Semi-Wet Process for Ceramic Floor Tile Granule Production
Authors: Ergin Hasan , Kiliç Mert , Durgut Emrah , Kayaci Kagan , Altintaş Ali , Yildirim Yildiz
Published: October 2014

In ceramic tile manufacturing industry, the wet process including wet grinding and spray drying, is widely used for preparing granule. However, due to the high energy consumption for the water evaporation in spray dryer, it has become a major problem in wet process. In recent years, there have been vast amount of researches for developing of dry granulation processes in that granule size distributions cause quality problems in the final products.In this research, it is aimed to develop a new production system, called as Semi-Wet Process. The new system consists of a horizontal dryer, dry ball mill, separator and an additional high speed mixture. The raw-materials having low humidity are ground to the required fineness in dry size reduction process. The other components of recipe, that are prepared in conventional wet process, are mixed with the dry prepared powder in the mixing slurry tank. The addition of dry powder reduces the water ratio of final suspension. Hence, the natural gas consumption of the water evaporation in spray dryer is reduced substantially.The industrial application of the developed Semi Wet System was carried out in Kaleseramik Factory in Turkey, where 28% reduction on gas consumption has been achieved.
Determination of Dry Grinding Properties of Floor Tile Wastes
Authors: Ergin Hasan , Kiliç Mert , Durgut Emrah , Kayaci Kagan , Altintaş Ali , Yildirim Yildiz
Published: October 2014

In ceramic production, there are around 5-8 % of floor tile defects occurred due to unsuitable body compositions or operational failure. The reuse of those fired products creates problems due to the difficult grindability features. These kinds of wastes are stored near factories and create vital environmental problems. There are some attempts to utilize these waste materials by adding to the recipes at small amounts. However, the grinding efficiency of the system is detrimentally affected and the grinding costs increases sharply. The aim of this work is to determine the dry grinding properties of floor tile wastes in order to utilize more and economical manner in the process. This paper includes grinding experiments in the laboratory dry ball mill. It is driven by inverter motor and control panel that allow to adjust the mill rotational speed, measure the grinding time and required energy consumption. Systematic grinding tests were carried out to observe the effect of feed particle size, feed rate, material moisture and mill rotational speed on the grinding efficiency. Finally, it was sought to use the dry prepared powder in glazed porcelain body composition. It was found that there are no inconvenient results on the sintered body up to usage of 20%.
Towards Rational Design of Porcelain Tile Glazes
Authors: Amorós José Luis
Published: October 2014

The complexity of porcelain tile glaze compositions translates into equally complex behaviour during firing in which, concurrently or in partially overlapping form, very different processes develop, such as the dissolution of crystalline phases, the crystallisation of new phases, and sintering phenomena. This complexity, and the scarcity of studies relating to the subject, make it extremely difficult to formulate such glaze compositions scientifically and efficiently. The present study analysed the physico-chemical transformations that occurred during the firing of these glazes, focusing in particular on the sintering process and its kinetics. A kinetic model was developed, first, which describes the sintering of complex glaze compositions (containing more than five components) with significant frit contents (45–70%) that devitrify crystalline phases during firing. A second, more comprehensive kinetic model was then developed, involving a formal multi-step kinetic model that encompassed even more complex glaze compositions (up to nine components), to calculate the effective viscosity of the glaze melt. This property was compared, on the one hand, with the effective viscosity obtained experimentally by hot stage microscopy (HSM) and, on the other, with that estimated theoretically from the chemical and mineralogical composition of the material, at different temperatures. The results obtained by the two methods exhibited very good agreement. The concept of effective viscosity provides a better understanding of the role played by the different glaze constituents and the firing conditions in sintering, enabling more rational design of these materials.
Alkali-Activated Fly Ash Foams – Synthesis, Chemo-Physical Properties and Microstructure Modeling
Authors: Hlaváček Petr , Šmilauer Vit , Škvára František
Published: October 2014

Inorganic foams offer several unique properties such as low thermal conductivity, fire resistance, or UV stability. Inorganic foam specimens were synthesized from fly ash and aluminium powder through an alkali-activation process. Depending on mix proportions, bulk densities ranged between 400 and 800 kg/m3. Thermal treatment at 80°C for 12 hours accelerated curing process. Compressive strength was found in the range 4.5-9.0 MPa, flexural strength 0.6-1.7 MPa, Young's modulus 0.6-1.1 GPa, thermal conductivity 0.14-0.16 W/m/K and thermal capacity around 1100 J/kg/K. Exposing the foams to temperature 800°C led to a small decrease of compressive strength while exposure to 1100°C sintered the foam to higher strength of 13 MPa. Volumetric shrinkage 20% occurred at 1100°C without further disintegration. Residual compressive strength was determined after exposure to NaCl, HCl, Na2SO4, MgSO4, H2SO4. The highest reduction to 20% occured in both acids with pH=2 after one year of exposition. Digitized microstructures entered finite element analysis to validate a stress-strain diagram.
Vitrification and Sinter-Crystallization of Iron-Rich Industrial Wastes
Authors: Karamanov Alexander
Published: October 2014

Results about the vitrification of several hazardous iron-rich industrial wastes (from productions of Zn and Cu metals, as well as EAFD and MSWA) and the usage of obtained glasses for synthesise of sintered glass-ceramics are summarises. It is shown that the appropriated method of sinter-crystallization mainly depends on the crystallization trend of used glasses. When the parent composition is characterised by formation of a moderate amount of crystal phase low temperature sintering with short crystallization step in the interval 800-900 °C can be used. In addition, attractive granite-like building glass-ceramic can be obtained by mixing fine and coarse glass frits and “free” sintering in refractory moulds at 1000-1050 °C. Contrary, when intensive phase formation carries out the crystallization inhibits the sintering resulting in specimens with scarce degree of densification. However, in some cases a secondary densification process occurs at temperatures near to the eutectic ones, leading to well sintered samples with higher crystallinity and improved mechanical properties. It is also highlighted that the preventing of Fe2+oxidation by using inert atmosphere during the heat-treatments leads to a decreasing of sintering temperature, finer crystalline structure and additional enhancement of the mechanical properties.
Development of the Alternative Whitening System for Zirconium Silicate Substition in Porcelain Tile Bodies
Authors: Tamsu Selli Neslihan , Bayrak Vedat
Published: October 2014

Zirconium silicate is generally used as a whitening agent in super white and ultra white porcelain tile compositions. Depend on the market speculation, this material's price fluctuated. To reduce this negative effect of the material on the our profitability, an alternative whitening compositions is developed. The aim of the study is prepare the alternative whitening composition with an innovative approach such as controlling the amount of the amorphous and crystalline phases in the porcelain tile body and produce the new composition with the same property compared standard body such as water absorption, size, strength, color. And also ensure the sustainable production with the same quality.
Composition and Ceramic Characteristics of Cretaceous Clays from Morocco
Authors: Sadik Chaouki , Albizane Abderrahman , el Amrani Iz Eddine
Published: October 2014

Investigations were undertaken to assess the chemical and technological characteristics in clay products from the Cretaceous deposit (Moroccan Meseta), in order to use them in refractory products. We have focused mainly on this clay because of its high content of alumina, silica and magnesium oxide, which are very favorable for the synthesis of refractory and ceramic materials. That is why the study has used several techniques of analysis (FX, XRD, SEM and technological tests. The samples were dry pressed on clay bodies and sintered at temperatures ranging from 900 to 1200°C. The relationship between water absorption, shrinkage and flexural strength as a function of the firing temperature was examined in order to enhance the quality of the final products and to optimize the production process. The results revealed that these clays have qualities necessary for the manufacture of ceramic and refractory products.
Study of Processing Techniques for Nepheline Syenitic Raw Material Exploitation
Authors: del Roveri Carolina , Godoy Letícia H. , Zanardo Antenor , Silva Luciano L. , Moreno Maria Margarita T. , Navarro Fabiano C. , Maestrelli Sylma C.
Published: October 2014

Lavrinhas, a city located 234 km northeast of São Paulo, Brazil, presents syenitic rocks with high content of nepheline, whose preliminary field assessment indicated its potential to be used in the production of ceramic products. The paper aimed to study this raw material with fluxing properties and to determine the best processing methods based on mineralogy and texture, in order to achieve better removal efficiency of the nepheline. Petrographic characterization was carried out in two rock samples, as well as the particle size characterization of the untreated material, the split into fractions for magnetic separation tests and optical microscope observation of the products. In addition, chemical and particle size analysis and melting tests were performed. The latter concerned the material melting color evaluation before and after the magnetic separation, as well as its potential use in glazes and engobes, compared to a standard sample of Nepheline, and inferences for the use in porcelain masses. Preliminary tests showed that after the removal of residual iron oxide, the nepheline raw material bearer has potential to be used in the formulation of porcelain masses, replacing other fluxing materials with higher benefit.
Mould Fluxes Viscosity and Surface Tension Influence on the Wear Mechanisms of Al2O3-C Nozzle
Authors: Brandaleze Elena , Peirani Valeria , Ávalos Martina
Published: October 2014

A deep understanding of the mould flux effect on the wear mechanisms of Al2O3-C nozzles (AG) is relevant to avoid premature damage and to decrease the cost of black refractories in the industry. In this paper, a post mortem study on a nozzle was carried out to identify the causes of the wear mechanisms during the continuous casting of billets. Physical properties such as viscosity and surface tension of the mould fluxes were determined at operation temperature (1550oC), in order to correlate with microstructural results obtained by light and scanning electron microscopy (SEM). Also dihedral angle φ measurements were carried out at high magnification by SEM. Applying EDS analysis the infiltrated mould flux chemical composition was determined. The study was completed by EBSD. The EBSD technique contributed to increase the knowledge on wear mechanisms because of the possibility of identifying and localizing phases together with crystalline condition. The phases, the grain orientations and the properties of grain boundaries, have a large influence on the corrosion behaviour. Therefore, it is essential to have a characterization technique that can provide information such as: grain size, orientation, misorientation angle and the present phases. In this context, EBSD can provide relevant information on crystallographic and structural analysis of AG nozzle including the insert of ZrO2-C.
Digital Image Correlation as a Tool for Monitoring Crack Networks on the Surface of MgO-Based Refractory Castables
Authors: Saracura Rafael G.M. , Canto Rodrigo B. , Pandolfelli Victor Carlos , Schmitt Nicolas , Hild François
Published: October 2014

This paper deals with the characterization of crack networks on the surface of refractory castable slabs, which are induced by stresses arising during the curing and drying (CD) stages. Images of the surface of castable samples placed in a house-made climatic chamber were recorded during the CD stages with a digital camera and processed by Digital Image Correlation (DIC) tomeasure the displacement field. Post-processing of DIC results were performed to estimate the length, orientation and opening of cracks in networks. The methodology is detailed and first analyses of experimental results are shown.
Corrosion Mechanism Analysis of Al2O3-SiC-C Castable
Authors: Pan Chien Nan
Published: October 2014

The present study aims to analyze the corrosion mechanism of Al2O3-SiC-C castables for blast furnace main trough. The anti-oxidation and corrosion properties of the castable caused by slag were studied with residual lining investigation and microstructure analysis. A rapid recognition of grain distribution, ingredients, and mineral phases was achieved by using cathodoluminescence (CL) in conjunction with stereo microscopy. Different materials such as brown fused alumina, spinel, and low-melting CaO containing phases etc. can be detected due to their distinct fluorescence. The result indicated that when carbon in the matrix of castables was oxidized, its non-wetting property to slag was reduced, which causes slag penetrate into the castable and formed low-melting CaO containing phases. On the contrary, when the anti-oxidation property of castable was improved, the carbon in the matrix was not easily oxidized and corroded by slag. Furthermore, MgO of slag reacted with Al2O3 in the matrix to form a continuous spinel layer, which retarded slag to penetrate and corrode the castable.
Study of Reactive Impregnation and Phase Transformations during the Corrosion of High Alumina Refractories by Al2O3-CaO Slag
Authors: de Bilbao Emmanuel , Dombrowski Mathieu , Traon Nicolas , Tonnesen Thorsten , Poirier Jacques , Blond Eric
Published: October 2014

Corrosion of refractories results from reactive transport namely, transport of agents and chemical reactions of these agents with impregnated medium. On one hand, the transport involves either diffusion or impregnation depending on the state of the corrosive agents and the microstructure of the host media. On the other hand, chemical reactions may be very numerous and complex. This study focused on the reactive impregnation of Al2O3-CaO slag into porous high alumina refractory.Transport properties of the porous media have been assessed by performing wicking test. Chemical reactions between the solid high alumina skeleton and Al2O3-CaO slag involve successive dissolution/precipitation mechanisms forming aluminates of lime. Contrary to the thermodynamic properties of the binary system, the kinetics of these solid/liquid reactions is not well known. Corrosion tests associated with quenching method, XRD and high temperature XRD were performed for a better understanding of the kinetics.
Criteria to Select the Refractory Lining in Biomass Co-Combustion Reactors for Energy Production
Authors: Olevano Daniela , Miceli Patrizia , Martini Umberto , di Donato Antonello , Martelli Stefano
Published: October 2014

The addition of biomass in co-combustion reactors for energy production is becoming a promising way for reducing the use of non-renewable fossil fuels. However the presence of alkalis in biofuel can degrade more rapidly the refractory lining of the combustion chamber. The alkalis can penetrate in the refractory and dissolve material components, forming new liquid phases that physically degrade the coherence of the material, increasing the risk of refractory failure.
Modeling and In-Plant Evaluation of Thermal Stresses in Steelmaking Ladles
Authors: Galliano Pablo , Martorello Leandro , Musante Leonardo , Simaro Tomás , Rossi Miguel , Ernst Hugo , Johnson Daniel
Published: October 2014

A thermo-mechanical finite element model was developed by using FEA commercial software, in order to estimate thermal stress levels in a refractory lined steelmaking ladle shell during its first preheating stage. The model considers two refractory linings: an inner working lining and a permanent one besides the external ladle shell. In this way, stresses on both refractory lining and metallic shell due to restricted lining thermal expansion were simulated. Stress-strain curves of refractory lining materials at different temperatures were obtained through lab tests and then used for model optimization. Additionally, creep behavior in the steel shell under different tensile stresses and temperatures was also estimated taking into account previously obtained results from laboratory tests. In plant strain and temperature measurements were done by instrumenting the lower part of the ladle sidewall shell with high temperature strain gauges and thermocouples. Predicted stress evolution showed good agreement with results obtained from in plant measurements.
A Taguchi Approach for the Synthesis Optimization of Metakaolin Based Geopolymers
Authors: Tsitouras Alexandros , Tsivilis Sotirios , Kakali Glykeria
Published: October 2014

There are several factors that affect geopolymerization, including the type and ratios of the starting materials as well as the curing conditions of the initial mixture. The effect of the synthesis parameters on the formation of inorganic polymers are usually examined by “changing one factor at a time”. In this study Taguchi experimental designing model was applied in order to study the synergetic effect of selected synthesis parameters on the compressive strength development of metakaolin based geopolymers. The experimental design involved the variation of three control factors in five levels. The selected factors and the corresponding level range were: i) the alkali to aluminum molar ratio in the starting mixture (0.5-1.5), ii) the kind of alkali ion (Na and/or K) and iii) the molar ratio of Si to alkali oxide in the activation solution (0-2.0). The compressive strength of geopolymers was measured and the final products were also examined by means of XRD, FTIR and SEM. As it is concluded, the optimal synthesis conditions for metakaolin geopolymers are R/Al=0.75, Na/(Na+K)=0.50 and [Si]/R2O=1.50, while the factor having the highest impact on the development of compressive strength is the [Si]/R2O ratio.
Оbtaining of Lightweight Geopolymer Using Ash from Thermal Power Plants
Authors: Hristov Yancho , Kostadinov Yordan , Pashev Plamen , Bogdanov Bogdan
Published: October 2014

A lightweight inorganic polymer is obtained using by ash from thermal power plants and lightweight aggregate from perlite . This inorganic material is activated using small amounts of sodium hydroxide and sodium silicate solution. In addition, porosity and water absorption were determined. Results showed that the lightweight geopolymer blocks with satisfactory strength and density could be made. The 28-day compressive strength of 5.2–13.8 MPa, density of 1075–1345 kg/m3, water absorption of 10–28% and porosity of 15–32% obtained. It can be used as lightweight geopolymer concrete for partition walls.
Hydrogenation of Nanocrystalline Mg2Ni Alloy Prepared by High Energy Ball-Milling Followed by Equal-Channel Angular Pressing or Cold Rolling
Authors: Révész Ádám , Gajdics Marcell , Varga Lajos K. , Spassov Tony
Published: October 2014

Nanocrystalline Mg2Ni powders produced by high energy ball milling (HEBM) were subjected to further severe plastic deformation by cold rolling (CR) or equal-channel angular pressing (ECAP). The microstructure of the alloys have been analysed by the Convolutional whole profile fitting method of the X-ray line profiles. The hydrogenation behavior has been studied by absorption kinetic measurements.
Detecting Aging Phenomena in Commercial Cathodes for Li-Ion Batteries Using High Resolution Computed Tomography
Authors: Komsiyska Lidiya , Garnica Barragan Sergio A. , Lewerenz Meinert , Ledwoch Daniela , Osters Oliver
Published: October 2014

Using high resolution computed tomography (CT) the change of the morphometric parameters in depth of electrodes for lithium ion batteries with aging has been examined. Commercially available 2 Ah Li-ion cells were continuously cycled to different state of health (SOH). The cathodes were subsequently analyzed using CT with voxel size resolution of about 400 nm. For a quantitative analysis binarized images were evaluated and various properties such as the size distribution of active particles analyzed. Using this technique a decrease in the average particle size and an increase in number of particles of LiCoO2 with decreasing SOH of the battery is confirmed experimentally for the first time.
Direct Growth of Polyaniline Chains from Nitrogen Site of N-Doped Carbon Nanotubes for High Performance Supercapacitor
Authors: Lim Joon Won , Haq Atta Ul , Kim Sang Ouk
Published: October 2014

Polymer grafting from graphitic carbon materials has been explored for several decades. Currently existing methods mostly employ harsh chemical treatment to generate defect site in graphitic carbon plane, which are used as active site for polymerization of precursors. Unfortunately, the treatment cause serious degradation of chemical structure and material properties. Here, we present a straightforward route for growth of polyaniline chain from nitrogen (N)-sites of carbon nanotubes. N site in the CNT wall initiates the polymerization of aniline monomer, which generates seamless hybrids composed of polyaniline directly grafted onto the CNT walls. The synthesized hybrids show excellent synergistic electrochemical performance, and are employed for electrodes of pseudo-capacitor. This approach offers an efficient way to obtain hybrid system consisting of conducting polymers directly grafted from graphitic dopant sites.
Development of High Surface Area Titania on Glass Fibre Supports for Photocatalysis
Authors: Yilmaz Pelin , Lacerda Armando Marsden , Larrosa Igor , Dunn Steve
Published: October 2014

We show that we have developed a hydrothermal process that produces a high surface area TiO2 on glass fibre supports. The as produced titania shows good photocatalytic activity against a standard commercial dye – Rhodamine B– giving full decolourisation within 3 hours under UV and visible light irradiation. The samples are mechanically robust and can act as a photocatalytic filter for waste streams and pollutants. In addition to testing the standard titania we also photochemically deposit nanostructures of Pd. These hybrid catalysts show enhanced decolourisation by an order of magnitude over the native titania systems. This enhanced performance is due to the increased energy harvesting of the hybrid system through a visible light plasmon interaction and the direct injection of electrons from the noble metal into the adsorbed dye molecules. There is a clear relationship between the absorbed light and photochemical reactivity of the system which is further explained in terms of electron hole generation and separation and plasmonic interaction. In summary, we have generated a high performance catalyst that is produced on a bulk commodity substrate with enhanced activity due to control of the surface plasmon and direct band gap transition of electron hole pairs in the semi-conductor.
Coherent Electronic Energy Transfer and Organic Photovoltaics
Authors: Collini Elisabetta
Published: October 2014

One of the most surprising and significant advances in the study of the photosynthetic light-harvesting process is the discovery that the electronic energy transfer (ET) might involve long-lived electronic coherences, also at physiologically relevant conditions. This means that the transfer of energy among different chromophores does not follow the expected classical incoherent hopping mechanism, but that quantum-mechanical laws can steer the migration of energy. The implications of such quantum transport regime, although currently under debate, might have a tremendous impact in our way to think about natural and artificial light-harvesting and suggest new directions for the development of artificial devices for the efficient capture and re-use of solar energy. Central to these discoveries has been the development of new ultrafast spectroscopic techniques, in particular two-dimensional electronic spectroscopy, which is now the primary tool to obtain clear and definitive experimental proof of such effects.
Morphological Study of CdSe Nanocrystals Passivated with a Low Band Gap Rod-Coil Diblock Copolymer for Hybrid Solar Cells
Authors: Zappia Stefania , Destri Silvia , Striccoli Marinella , Curri Maria Lucia , di Mauro A. Evelyn , Ameer Zoobia , Maruccio Giuseppe , Rizzo Aurora , Mastria Rosanna
Published: October 2014

Different nanocomposite materials consisting of semiconducting CdSe nanocrystals (NCs) and a low band gap copolymer poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b:3.4-b’]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) were prepared, morphologically characterized, and tested in hybrid solar cells. In addition, a PCPDTBT-based rod-coil diblock copolymer was synthesized through a grafting-onto approach and a preliminary evaluation of the morphology of the hybrid nanocomposites with CdSe NCs was performed.
A Monolithic White-Light LED Based on GaN Doped with Be
Authors: Teisseyre Henryk , Bockowski Michal , Young Toby David , Grzanka Szymon , Zhydachevskii Yaroslav , Grzegory Izabella , Kozanecki Adrian
Published: October 2014

In this communication, the use of gallium nitride doped with beryllium as an efficient converter for white light emitting diode is proposed. Until now beryllium in this material was mostly studied as a potential p-type dopant. Unfortunately, the realization of p-type conductivity in such a way seems impossible. However, due to a very intensive yellow emission, bulk crystals doped with beryllium can be used as light converters. In this communication, it is demonstrated that realisation of such diode is possible and realisation of a colour rendering index is close to that necessary for white light emission.
InGaN/GaN Quantum Dot and Nanowire LEDs and Lasers
Authors: Bhattacharya Pallab , Frost Thomas , Banerjee Animesh , Jahangir Shafat
Published: October 2014

GaN-based InGaN/GaN self-organized quantum dots and InGaN quantum dots (disks) in GaN nanowires are important nanostructures with potential advantages over planar quantum wells, including luminescence at the longer visible wavelengths. We describe the epitaxy and characteristics of red-emitting InGaN/GaN quantum dot edge-emitting lasers and InGaN/GaN nanowire light emitting diodes, which can be used in a host of applications.
The Long Way of Achieving a Durability of 20,000 h in a DMFC System
Authors: Müller Martin , Kimiaie Nicola , Glüsen Andreas , Stolten Detlef
Published: October 2014

Direct Methanol Fuel Cells (DMFC) are an attractive power source for applications in the low kW-range like pallet trucks or uninterruptable power supplies. A significant problem during the past years, however, was the limited durability of DMFC systems. While single cells could be operated for thousands of hours, DMFC systems degraded significantly often within less than 1,000 hours.In an evolution of six generations of DMFC systems in the kW power range over the past decade, we identified the main reasons for degradation. Causes for fast degradation had to be removed first in order to identify what leads to slower degradation over several hundreds or thousands of hours. Interactions of cells and system components also had to be considered.As a result, the operating conditions of all cells must be carefully controlled by suitable operating algorithms and reproducible manufacturing technologies, in order to avoid high potentials on the anode, which would lead to ruthenium corrosion and subsequent poisoning of the cathode catalyst. All components of the stack and the peripheral system must be corrosion-proof and free from contaminants that might leach into the membranes. Finally, a DMFC system for a pallet truck was operated in a realistic load cycle for 20,000 hours.
Effect of Doping of Fe into TiO2 Layer in Fe2O3/TiO2/FTO System for High Performance of Water Splitting
Authors: Azad Aryan , Noh Eul , Yun Kang Seop , Jeong Hee June , Jung Sang Chul , Kang Woo Seung , Moc Nguyen Thai , Kim Sun Jae
Published: October 2014

Hydrogen has unique physical and chemical properties which present benefits and challenges to its successful widespread adoption as a fuel. The photoelectrochemical (PEC) water splitting process with semiconductor metal oxides can be a promising solution to the global energy problem. Although amongst metal oxides Fe2O3 by 2.2 eV bang gap energy is more applicable, for reducing the recombination of electron and hole, Fe was doped into TiO2. In this study Fe2O3/Fe doped TiO2 photocatalysts were compared with Fe-doped TiO2 and TiO2 structures by using layer by layer-self-assemble (LBL-SA) method and dipping process on FTO glass. According to our results the Fe2O3 coated on Fe doped TiO2 /FTO has had best results.
Indian Test Blanket Module in ITER - Development of RAFM Steel and Fabrication Technology
Authors: Jayakumar Tammana , Kumar Ellappan Rajendra
Published: October 2014

A detailed and comprehensive programme is undertaken in India to fabricate Indian Test Blanket Module (TBM) to be tested in ITER. Development of India-specific Reduced Activation Ferritic/Martensitic (RAFM) steel has been realized through melting and physical and mechanical properties characterization of several heats of 9Cr-RAFM steel with varying tungsten and tantalum contents. The RAFM steel having 1.4 wt. % tungsten and 0.06 wt. % tantalum is found to possess better combination of strength and toughness and is considered as India-specific RAFM steel. Different joining processes for fabrication of TBM have been assessed. Hot Isostatic Pressing (HIP) has been demonstrated to fabricate the first wall of TBM. To avoid channel collapse during HIPing, leachable ceramic cores were inserted in the channels. Electron Beam (EB) and Laser Welding processes are used for fabrication of breeder cassettes and hence, these welding procedures have been developed. Tungsten Inert Gas (TIG), Narrow Gap TIG (NG-TIG) and Laser Hybrid welding processes are being considered for integration of the various components such as first wall, back plate, bottom plate, breeder assembly and flow dividers into TBM. RAFM steel welding consumables have also been developed and qualified. Procedure for laser hybrid welding has also been developed. Necessary technologies for inspection and quality assurance of the fabricated TBM are also being developed. Use of ultrasonic C-Scan imaging to examine the bond integrity of the HIP joint has been demonstrated. Phased Array technique that would enable inspection of welds by longitudinal movement of the probe from an optimised lateral distance of the weld without the requirement of lateral movement has also been developed. The challenges in developing the India-specific RAFM steel and the fabrication and inspection technologies for fabrication of Indian TBM are presented.
Leaching Behavior of Salt Wastes Conditioned with Sodalite Blended with Two Different Glass Powders
Authors: Capone Mauro , de Angelis Giorgio , Fedeli Carlo , Giacobbo Francesca , da Ros Mirko , Macerata Elena , Mariani Mario
Published: October 2014

Two different glass powders (a commercially available glass frit and a borosilicate glass) have been used as blending agents for sodalite, an aluminosilicate mineral able to condition chloride salt wastes from pyrometallurgical processes. The synthesis of the mineral phase has been made through a process recently proposed by Idaho National Laboratory in USA, starting from a homogeneous powder of nepheline, chloride salts and glass. The mix, put into an alumina crucible, was introduced in a furnace inside an argon-atmosphere glove-box. The furnace temperature was then raised to 925 C, where it was kept for 7 hours. Leach tests under static conditions, according to ASTM C1285-02, have then been carried out on the final waste forms at room temperature (23 C) and in an oven at 90 C. SEM investigations have also been made before and after leach tests, in order to check the status of the powders. In particular the effect of the leaching process on the surface of the sodalite grains at 90 C from 30 to 150 days has been evidenced. The results obtained in the present study have been usefully compared to those from a similar test on a sodalite added with a glass frit by Idaho National Laboratory. Financial support from the Nuclear Fission Safety Program of the European Union is gratefully acknowledged (project ACSEPT, contract FP7-CP-2007-211 267).
Utilization Research and Development of Hydride Materials in Fast Reactors
Authors: Konashi Kenji , Itoh Kunihiro , Yokoyama Tsugio , Yamawaki Michio
Published: October 2014

Metal hydrides have high hydrogen atom density, which is equivalent to that of liquid water. An application of the hafnium hydride has been investigated as a neutron absorber in the Fast Breeder Reactors (FBRs). Fast neutrons are efficiently moderated by hydrogen in Hf hydrides and are absorbed by Hf. Since three isotopes of Hf have large cross sections, increase in the life of control rod is considered by Hf hydride. Results of design study of the core with Hf hydride control rods shows that the long lived hafnium hydride control rod is feasible in the large sodium-cooled FBR. Results of irradiation test conducted in BOR-60 has demonstrated the integrity of the capsules during irradiation. Na bonded capsule has an advantage in confinement effect of hydrogen compared with He bonded one. An application of hydride technique to transmutation target of MA was also discussed. MA hydride target is able to enhance the transmutation rate in FBR.
Status of the Low Enriched Uranium Fuel Development for High Performance Research Reactors
Authors: Sannen Leo , van den Berghe Sven , Leenaers Ann
Published: October 2014

Historically, uranium enriched to >90% 235U has been used for many peaceful applications requiring high fission densities such as driver fuels for research reactors. However, the use of high-enriched uranium or HEU (all enrichments >20% 235U are considered HEU) for civil applications, is considered a proliferation concern. Since the 1970's, efforts are being devoted to the conversion of research reactors operating on HEU to alternative fuels using uranium with enrichment below 20% or LEU. These efforts imply the development of high-density LEU fuels to replace the low volume-density (mostly) UAlx based HEU fuels. The paper updates the present status of these developments focusing on the UMo dispersion fuel. It aims to provide an overview of the knowledge generated and the lessons learned in roughly 15 years of UMo dispersion fuel R&D in Europe through irradiation experiments and post-irradiation examinations (PIE).
MRAM Concepts for Sub-Nanosecond Switching and Ultimate Scalability
Authors: Prejbeanu Ioan Lucian , Bandiera Sebastien , Sousa Ricardo , Dieny Bernard
Published: October 2014

This work reports on advances in MRAM cells aiming at sub-nanosecond switching and for sub-20nm technology nodes. Ultrafast precessional spin-transfer switching in elliptical magnetic tunnel junction nanopillars is possible to obtain in samples integrating a perpendicular polarizer and a tunnel junction with in-plane magnetized electrodes. We show that spin transfer torque (STT) switching in less than 500ps can be achieved in these structures with corresponding write energy less than 100fJ. For high density integration and possibly sub-20nm diameter cells the use of a thermally assisted concept for perpendicular anisotropy cells, where the intrinsic heating is used to simultaneously achieve high thermal stability and low current switching.
Doped Hafnium Oxide – An Enabler for Ferroelectric Field Effect Transistors
Authors: Mikolajick Thomas , Müller Stefan , Schenk Tony , Yurchuk Ekaterina , Slesazeck Stefan , Schröder Uwe , Flachowsky Stefan , van Bentum Ralf , Kolodinski Sabine , Polakowski Patrick , Müller Johannes
Published: October 2014

Ferroelectrics are very interesting materials for nonvolatile data storage due to the fact that they deliver very low power programming operation combined with nonvolatile retention. For 60 years researchers have been inspired by these fascinating possibilities and have tried to build ferroelectric memory devices that can compete with mainstream technologies in their respective time. The progress of the current concepts is limited by the low compatibility of ferroelectrics like PZT with CMOS processing. Therefore, PZT or SBT based 1T1C ferroelectric memories are not scaling below 130 nm and 1T ferroelectric FETs based on the same materials are still struggling with low retention and very thick memory stacks. Hafnium oxide, a standard material in sub 45 nm CMOS, can show ferroelectric hysteresis with promising characteristics. By adding a few percent of silicon and annealing the films in a mechanically confined manner. Boescke et al. demonstrated ferroelectric hysteresis in hafnium oxide for the first time. Recently, a large number of dopants including Y, Al, Gd and Sr have been used to induce ferroelectricity in HfO2. This paper reviews the current status of hafnium oxide based ferroelectrics, its application to field effect transistors and puts this approach into a wider context of earlier developments in the field.
Evolution of Cu Surface Morphology and its Effect on Graphene Synthesized by Chemical Vapor Deposition
Authors: Ibrahim Ahmed , Owais A. , Atieh M. , Karnik R. , Laoui Tahar
Published: October 2014

Chemical Vapor Deposition (CVD) is generally utilized for producing large area, good quality graphene films on suitable substrates. Copper (Cu) substrate is used mainly as a substrate and catalyst during graphene synthesis process by CVD method. The purpose of the present work is to investigate the evolution of Cu surface morphology after graphene growth and its influence on grown graphene quality. In this study, graphene was grown using methane as the carbon source at temperature 1040 °C for 5 minutes. Scanning electron microscopy (SEM), Optical Microscopy (OM) and atomic force microscopy (AFM) were utilized to analyze the change of Cu surface morphology after graphene synthesis. Raman spectroscopy was used to characterize the characteristics of grown graphene. SEM and AFM results showed that copper substrate surface morphology was modified after graphene growth associated by formation of large size Cu particles located basically on the surface terraces, resulting in deposition of multilayer, very small graphene domains aligned linearly along rolling marks direction.
Development of Density Functional Theory for Plasmon-Assisted Superconductivity
Authors: Arita Ryotaro , Akashi Ryosuke
Published: October 2014

A new scheme of density functional theory (DFT) for unconventional superconductivity is reviewed.To include the effect of charge fluctuations such as low-energy plasmons or excitons, we extendthe conventional formalism of superconducting DFT where the dynamical structure of the screened Coulomb interaction is neglected.We applied the present method to fcc Li under high pressure. We show that the agreement between thetheory and experiment is considerably improved. The present result indicates that plasmons cancooperate with phonons and enhance the pairing instability.
Carbon Coils-Polyurethane Composites for the Shielding Materials of Electromagnetic Interference
Authors: Kang Gi Hwan , Kim Sung Hoon
Published: October 2014

The carbon coils (d-CCs) having the diverse geometries were deposited on Al2O3 substrate by continuous injection of SF6 in C2H2 source gas under the thermal chemical vapor deposition system. d-CCs with polyurethane (PU) composites (d-CCs@PU) were fabricated by dispersing d-CCs in PU solvent with dimethylformamide (DMF) additive. The electromagnetic wave shielding properties of d-CCs@PU composites were investigated in the frequency range of 0.25-1.5 GHz. The shielding effectiveness (SE) of d-CCs@PU composites were measured and discussed according to the weight percent of d-CCs in CCs@PU composites and the thickness of d-CCs@PU composites layers. Based on these results, we discussed the shielding properties of d-CCs@PU composites and the main mechanism of the SE in this work.
Vacancy Diffusion under a Stress and Kinetic of Nanovoid Growth in Cubic Metals
Authors: Nazarov Andrei , Mikheev Alexander , Zaluzhnyi Alexander
Published: October 2014

Elastic fields, generating by defects of the structure, influence the diffusion processes. It leads to the alteration of the phase transformation kinetic. One of the chief aims of our work is to obtain general equations for the diffusion fluxes under strain that give the possibility for using these equations at low temperatures, as in this case the strain influence on the diffusion fluxes is manifested in maximal degree. Our approach takes into consideration, that the strains can alter the surrounding atom configuration near the jumping one and consequently the local magnitude of the activation barrier and a rate of atom jump. The rates of atom jumps in different directions define the flux density of the vacancies. Now we take into account, that strain values are different in the saddle point and in the rest atom position, in differ from our consideration that was done by us earlier. As a result in the development of our approach the general equations for the vacancy fluxes are obtained for fcc and bcc metals. In our paper we discuss the main features of the theory of diffusion under stress and its applications. In particular we examine how elastic stress, arising from nanovoids, influence the diffusion vacancy fluxes and the growth rate of voids in metals.