Fast Solid State Research Articles

Solar light degradation of organic dye pollutants and preparation of bis(indolyl)methanes using core-shell Fe3O4@SiO2@CuO nanocomposite.

In this research, a new ferromagnetic-recoverable core-shell Fe3O4@SiO2@CuO nanocomposite of a certain size (20-25 nm) has been synthesized based on Cu(II) complex coated on Fe3O4@SiO2 nanoparticles by facile and fast solid state microwave irradiation method. The photocatalytic activity of the nanocomposite was investigated for degradation of methylene blue (MB) and methyl orange (MO) dye pollutants in aqueous media under solar light irradiation. The nanocomposite could destroy these dyes with high efficiency in short time. With comparison of degradation percentages can be concluded that the nanocomposite shows better photocatalytic activity for MB dye (97% in 180 s). Kinetic study revealed higher rate constant for degradation of MB (k= 3.6×10-3 s-1) with pseudozero-order model. Also, Fe3O4@SiO2@CuO nanocomposite was an efficient magnetically recoverable catalyst for the preparation of bis(indolyl)methanes (BIMs) through the condensation of an aldehyde with 2 equivalents of indole in EtOH/H2O as green solvents.

Evaluation of the ITER data archiving network API on the DIII-D tokamak

The systems responsible for the archival and access of data at ITER will play a critical role from the very start of tokamak operations. Ensuring the readiness of the software being developed to handle the large amounts of data to be streamed to the archive systems will be of great importance and require extensive testing. To assist in this validation DIII-D offers the flexibility and means for testing on an operational tokamak. Because of the extensive experience gained in supporting data archiving and retrieval for a large and varied set of diagnostics and in-house expertise in Linux based systems, DIII-D is able to provide a uniquely qualified test platform to fully exercise ITER's software. In this paper, we report on the work that was recently performed to setup a data acquisition and archiving test system connected to live diagnostics for the purpose of evaluating the performance and completeness of the ITER Data Archiving Network Application Program Interface (DAN API). Diagnostic data that was made available and examined for archiving into the ITER DAN included data such as plasma current, bolometry, electron density, soft x-ray signals, visible camera images, data from the Thomson scattering and Electron Cyclotron Heating (ECH) systems. The hardware used for the test system was comprised of two high performing archiver computers and two data acquisition streamer computers. The archiver nodes were configured with 64 GB of RAM and 1 TB of fast solid state drive storage, and networked to the acquisition computers in a local 10 Gb/s network. This configuration was chosen in order to push performance limits and test data streaming and archiving to the ITER DAN at rates of up to 1 Gb/s from multiple archive sources.

Synthesis of a Carbazole-[pi]-carbazole Molecular Rotor with Fast Solid State Intramolecular Dynamics and Crystallization-Induced Emission

Herein we report the synthesis of the highly stable crystalline carbazole-based rotor 3 with simultaneous rapid solid state internal rotation and good fluorescence emission. Single crystal and powder X-ray diffraction studies along with microscopy revealed a phase transition from a labile benzene solvate (phase I) to highly stable crystals (phase II) that feature fast intramolecular rotation in the megahertz regime at room temperature, according to variable temperature 2H solid state NMR experiments using isotopically enriched analogues. In addition to the megahertz rotation within its crystals, this crystal phase II displays enhanced solid state fluorescence with a higher quantum yield of ϕ = 0.28, relative to the emission of this compound in THF solution (ϕ = 0.06). These two solid state properties are significantly different from shorter compounds 1 and 2 (static and nonemissive) included here for comparison purposes.

Synthesis, characterization, and electrochemical properties of lithium-based fluorosulfate nanoparticles as cathode for lithium-ion batteries

Lithium-based fluorosulfate nanoparticles were synthesized by a simple and fast solid state reaction from the precursors FeSO4∙7H2O and LiF ground by high energy ball milling. Through the introduction of excess of LiF, relatively pure LiFeSO4F phase with polycrystalline structure was obtained. The structure, morphology, and element valence state were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectra (XPS). The results demonstrate uniformly distributed particles and larger particles consisted of single crystalline structure, besides the valence states for different elements were analyzed and Fe2+ was confirmed. The cyclic voltammograms (CV) and charge-discharge cycling performances were employed to characterize electrochemical properties of prepared cathode material. It is very interesting that double redox peaks appeared reversibly. Meanwhile, it exhibited a relatively higher first-discharge capacity of 115 mAh/g at 0.05C and it still maintained above 60 mAh/g capacity after experiencing 30 times cycles at final 2C rate.

Interface-enhanced Li ion conduction in a LiBH4-SiO2 solid electrolyte.

We have developed a fast solid state Li ion conductor composed of LiBH4 and SiO2 by means of interface engineering. A composite of LiBH4-SiO2 was simply synthesized by high energy ball-milling, and two types of SiO2 (MCM-41 and fumed silica) having different specific surface areas were used to evaluate the effect of the LiBH4/SiO2 interface on the ionic conductivity enhancement. The ionic conductivity of the ball-milled LiBH4-MCM-41 and LiBH4-fumed silica mixture is as high as 10(-5) S cm(-1) and 10(-4) S cm(-1) at room temperature, respectively. In particular, the conductivity of the latter is comparable to the LiBH4 melt-infiltrated into MCM-41. The conductivities of the LiBH4-fumed silica mixtures at different mixing ratios were analyzed employing a continuum percolation model, and the conductivity of the LiBH4/SiO2 interface layer is estimated to be 10(5) times higher than that of pure bulk LiBH4. The result highlights the importance of the interface and indicates that significant enhancement in ionic conductivity can be achieved via interface engineering.

Studies on synthesis and properties of Zr1−Hf W2O8

Abstract In this work, Zr 1− x Hf x W 2 O 8 ( x = 0, 0.2, 0.3, 0.4, 0.5, 0.6, 1) samples were successfully synthesized by fast solid state reaction for the first time. The appropriate temperature range and sintering time are 1573–1693 K and between 10 min to 60 min, respectively. This approach greatly reduces sintering time and energy wasting. The grain sizes are between 1 and 10 μm which is smaller than those by conventional solid state reaction. The structure and phase transition properties of the samples were studied by Raman spectroscopy and X-ray diffraction. The samples crystallized in cubic structure with space group P 2 1 3. The crystal cell parameters and volume decrease with the contents of Hf 4+ . But each mode position is between its corresponding mode positions of them. The internal vibrational modes shift to higher while the external modes shift to lower frequencies, and both gradually approach the mode positions of α-HfW 2 O 8 with the content s of Hf 4+ . The results suggest that the properties of Zr 1− x Hf x W 2 O 8 (0 x 2 O 8 and α-HfW 2 O 8 .

The UC2−x – Carbon eutectic: A laser heating study

The UC2−x – carbon eutectic has been studied by laser heating and fast multi-wavelength pyrometry under inert atmosphere.The study has been carried out on three compositions, two of which close to the phase boundary of the UC2−x – C miscibility gap (with C/U atomic ratios 2 and 2.1), and one, more crucial, with a large excess of carbon (C/U = 2.82). The first two compositions were synthesised by arc-melting. This synthesis method could not be applied to the last composition, which was therefore completed directly by laser irradiation. The U – C – O composition of the samples was checked by using a combustion method in an ELTRA® analyser. The eutectic temperature, established to be 2737 K ± 20 K, was used as a radiance reference together with the cubic – tetragonal (α → β) solid state transition, fixed at 2050 K ± 20 K. The normal spectral emissivity of the carbon-richer compounds increases up to 0.7, whereas the value 0.53 was established for pure hypostoichiometric uranium dicarbide at the limit of the eutectic region. This increase is analysed in the light of the demixing of excess carbon, and used for the determination of the liquidus temperature (3220 K ± 50 K for UC2.82). Due to fast solid state diffusion, also fostered by the cubic – tetragonal transition, no obvious signs of a lamellar eutectic structure could be observed after quenching to room temperature. The eutectic surface C/UC2−x composition could be qualitatively, but consistently, followed during the cooling process with the help of the recorded radiance spectra. Whereas the external liquid surface is almost entirely constituted by uranium dicarbide, it gets rapidly enriched in demixed carbon upon freezing. Demixed carbon seems to quickly migrate towards the inner bulk during further cooling. At the α → β transition, uranium dicarbide covers again the almost entire external surface.

Solid State Synthesis and Characterization of NiTe Nanocrystals

NiTe nanocrystals were prepared through facile and fast solid state reaction (mechanical alloying) of pure elemental tellurium and nickel powders in an argon atmosphere. The samples processed for 3 h, 5 h and 10 h were characterized by X-ray diffraction, transmission electron microscopy, magnetization and Raman spectroscopy. Hexagonal NiTe crystals with an average size of 30 nm can be obtained after only 3 h of processing time. Transmission electron microscopy images showed a broad crystalline size distribution in the agglomerated particles and selected area electron diffraction revealed its crystalline character. NiTe ferromagnetic behavior was confirmed and magnetic parameters were dependent on processing time. Raman spectra showed no unreacted Te or tellurium oxides, but it also showed that laser induced phases transitions (including Te re-crystallization) can be observed for modest laser power (<3 mW).

Storage Management Method for Hybrid Storage System to Reduce Extent Fragmentation

A hybrid storage system consists of a small and fast solid state drive (SSD) and one or more slow and large hard disk drives (HDD). The purpose of a hybrid storage sys-tem is to exploit the IO performance of SSDs to enhance the overall IO performance with comparatively low cost. In a hybrid storage system, since the size of a SSD is small, the storage utilization for the SSD is very important to guarantee the performance of a hybrid storage system. Some existing hybrid storages use extents to manage a large storage efficiently. However, they cause an extent fragmentation problem. The extent fragmentation reduces the SSD utilization and the overall performance of a hybrid storage system. In this paper, to solve the problem we propose a new mapping method that uses different size of IO unit for SSD and HDDs. Also, we perform simulations to show that our proposed method guarantees better SSD utilization than existing methods.

Research on fast solid state DC breaker based on a natural current zero-crossing point

The DC fault characteristics of voltage source converter based high voltage direct current (VSC-HVDC) systems are analyzed in this paper. The phenomenon whereby the capacitor on DC side discharges quickly during a DC fault contributes to a large short-circuit fault current. Neither traditional DC breakers nor DC switches can cut off the fault current under this condition. A fast solid state DC breaker design method is proposed in this paper. This method is based on the fault current characteristics of the inverter in multi-terminal HVDC systems (MTDC), where a fault current appears at the natural zero-crossing point near the inverter. At this point, by coordinating the AC breakers near the rectifier, the DC breaker could reliably cut off the DC fault current and protect the system. A detailed model for this fast solid state DC breaker and its operation sequence are studied, based on this design method. Simulations modeling a five-terminal meshed DC grid and a fast DC breaker were carried out with PSCAD/EMTDC using this design method. The results from the simulations confirmed the validity of the design method.

Special issue for data intensive eScience

Data-intensive science is enabled by the data deluge and has been called the “fourth paradigm” of scientific discovery. New fields are being born, such as drug discovery based on large scale study of correlations in published papers and climate implications from data on the accelerating pace of changes in previously quiescent ice sheets. Astronomy and the search for fundamental particles at the Large Hadron Collider drive mainstream aspects of data-intensive science with many petabytes of data derived from large advanced instruments. Medical imagery and genomics have as much data but from a slew of distributed instruments. It is projected that there will be 24 billion devices on the Internet by 2020. Most of this “Internet of Things” will be small sensors that produce streams of information which will be processed and integrated with other streams and turned into knowledge. The deluge and its impact are pervasive. In synergy with moving to a data-driven world, we are also in the midst of an evolution in the compute landscape of hardware systems. We now live in the world of massive multi-core and GPU processing systems, very large main memory systems, fast networking components, fast solid state drive, and large data centers that consume massive amounts of energy. Computing paradigm is changing and suggesting new programming models, new data structures and more attention to fault tolerance while enabling much easier access to computing. It is clear that many aspects of how we have dealt with data processing have to change in this new world.

Study of the performance of dielectric resonator antennas based on the matrix BiREWO6 [RE = Gd, Y, Nd

AbstractIn this work, we study for the first time the dielectric properties, at microwave frequencies, of the BiREWO6 (RE = Y, Gd, and Nd) dielectric resonator (DR) obtained by microwave assisted fast solid state synthesis. The DRs were excited by a wire antenna protruding above a ground plane and simulations were carried out using high‐frequency structure simulator. The DRs presented permittivity values between 13 and 19 and dielectric loss of around 10−2. The agreement between experimental and simulated values for the resonant frequency and the bandwidth for all dielectric resonator antennas was considered good. The small size of the antenna and its compactness makes it especially attractive for use as an electric monopole in practical applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:18–23, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26486

A 3.9 V polyanion-type cathode material for Li-ion batteries

AbstractMonoclinic phase LiFeSO4F was synthesized by a simple fast solid state reaction from the mixture of FeSO4·7H2O and LiF pulverized by high energy ball milling. m-LiFeSO4F was confirmed by GITT measurement to be a 3.9 V polyanion-type cathode materials for Li-ion batteries. Its electrochemical activity can be enhanced by addition of carbon. A discharge capacity of 105 mA·h/g (70% of theoretical value) was achieved for a m-LiFeSO4F/CNT composite. Phase separation behavior during lithium extraction and insertion was observed by ex-situ XRD test.

New Efficient Intercalation of Bioactive Molecules into Layered Double Hydroxide Materials by Solid-State Exchange: An in Situ XRPD Study

A new soft and fast solid state reaction is exploited for the preparation of exchanged layered double hydroxide materials and, in particular, for intercalating bioactive molecules. The characteriza...

Room-temperature ferromagnetic/ferroelectric BiFeO3 synthesized by a self-catalyzed fast reaction process

Bismuth ferrite BiFeO3 has attracted a great deal of interest because of its multiferroic properties. However, BiFeO3 synthesized by conventional methods in the forms of single crystals, ceramics or thin films only exhibit ferroelectricity and antiferromagnetic order at room temperature, with weak ferromagnetism appearing at very low temperatures. To fully explore the potential of multiferroism in such applications as new memory devices, it is necessary to synthesize materials that show ferromagnetic order at room temperature as well, which will a priori allow for magnetoelectric coupling. In this paper, we report a new synthetic technique for the synthesis of BiFeO3 that exhibits unusual ferromagnetic properties. This method involves a low temperature fast solid state reaction based on tartaric acid. The mechanism of the reaction deduced from thermogravimetric analysis (TGA) and differential thermal analysis (TGA) suggests that a self-catalyzed process in the presence of iron and bismuth oxides triggers the oxidation of tartaric acid at low temperature and gives out a large amount of heat, which, in turn, leads to the formation of BiFeO3. The BiFeO3 synthesized in this way is ferromagnetic. The origin of the unusual ferromagnetism is supposed to be associated with point defects of oxygen vacancies generated during the self-catalyzed extremely fast exothermic reaction, which suppress the spin circular cycloid in BiFeO3. Ferroelectric hysteresis loops are displayed in the BiFeO3 samples. The presence of room temperature ferromagnetic and ferroelectric orders makes BiFeO3 a truly multiferroic material potentially interesting in such applications as magnetoelectric devices.

Ionogels encompassing ionic liquid with liquid like performance preferable for fast solid state electrochromic devices

Novel ionogels encompassing an ionic liquid encaged in an inorganic matrix were synthesized by sol–gel chemistry. The ability of these highly conducting ionogels (∼10 −2 S cm −1 at 25 °C) to act as liquid electrolytes in spite of their solid form has been exploited in inorganic electrochromic devices based on tungsten oxide and Prussian blue electrodes. These devices exhibit extremely fast switching kinetics and make it the best and only candidate for the realization of fast all solid state electrochromic devices.

Ti 및 Si 혼합 분말의 전기방전소결에 의한 Titanium Silicide의 합성 연구

The synthesis and consolidation of titanium silicide by electro-discharge-sintering has been investigated. As-received Ti powder was in flaky shape and the mean particle size was <TEX>$45.0{\mu}m$</TEX>, whereas the mean particle size of the pre-milled Si powder with angular shape was <TEX>$8.0{\mu}m$</TEX>. Single pulse of 2.5 to 5.0 kJ/0.34g-elemental Ti and pre-milled Si powder mixture with the composition of <TEX>$Ti-37.5at.\%$</TEX> Si was applied using <TEX>$300{\mu}F$</TEX> capacitor. The solid with <TEX>$Ti_5Si_3$</TEX> phase has been successfully fabricated by the discharge with the input energy more than 2.5kJ in less than <TEX>$129{\mu}sec.$</TEX> Hv values were found to be higher than <TEX>$1000kgf/mm^2$</TEX>. The formation of <TEX>$Ti_5Si_3$</TEX> occurred through a fast solid state diffusion reaction.

Investigating fast solid state reactions with time-resolved constant wavelength neutron powder diffraction at D20

Investigating fast solid state reactions with time-resolved constant wavelength neutron powder diffraction at D20

Microwave assisted fast solid state synthesis of niobates and titanates

Niobates and titanates are a technologically important class of inorganic materials. $LiNbO_3$ (space group R3c) is ferroelectric, piezoelectric and exhibits high non-linear optic coefAEcient [1, 2]. NaNbO3 is orthorhombic and is antiferroelectric at room temperature [3]. $KNbO_3$ has a perovskite structure, exhibits three structural transitions [4] and closely resembles barium titanate. $BaTiO_3$ is a well known perovskite with many applications in industry [5]. Binary and ternary lead titanates also exhibit interesting piezoelectric, pyroelectric and optoelectronic properties [6, 7]. Synthesis of these materials based on conventional ceramic methods involves extremely long reaction times due to slow diffusion rates in the solid state. For example, (i) the conventional ceramic preparation of $LiNbO_3$ requires programmed heating [8] of the reaction mixture for 8 h at 770 K, for 3 h at 1170 K followed by a controlled slow cooling of the charge (sometimes oxygen annealing of the product for 20-30 h at 1273 K is required); (ii) synthesis of $KNbO_3$ requires 30 h of heating [9] of the reactants at 1273 K and cooling at a very slow rate; (iii) the traditional solid state preparation of $PbZr_{0.52}Ti_{0.48}O_3$ involves stepwise heating of the charge for several hours and also necessitates intermittent grinding [10].

Precision universal temperature ( −200°C to +200°C) controller with fast solid state on-off system

A simple, rugged, reliable, low cost temperature display-cum-controller has been designed and constructed using standard integrated circuits and a 3½ digit LED display. The controller, utilising semiconductor controlled rectifiers as fast solid state on–off switches capable of maintaining the set temperature constant within the temperature range -200°C to + 200°C with a resolution of ±0·05°C. A thermocouple (specifically, a copper-constantan type) sensor has been used because of its fast response time and tolerance of high magnetic fields.