Showing papers on "Ternary operation published in 2010"

Design and Synthesis of Hierarchical MnO2 Nanospheres/Carbon Nanotubes/Conducting Polymer Ternary Composite for High Performance Electrochemical Electrodes

Abstract: For efficient use of metal oxides, such as MnO2 and RuO2, in pseudocapacitors and other electrochemical applications, the poor conductivity of the metal oxide is a major problem. To tackle the problem, we have designed a ternary nanocomposite film composed of metal oxide (MnO2), carbon nanotube (CNT), and conducting polymer (CP). Each component in the MnO2/CNT/CP film provides unique and critical function to achieve optimized electrochemical properties. The electrochemical performance of the film is evaluated by cyclic voltammetry, and constant-current charge/discharge cycling techniques. Specific capacitance (SC) of the ternary composite electrode can reach 427 F/g. Even at high mass loading and high concentration of MnO2 (60%), the film still showed SC value as high as 200 F/g. The electrode also exhibited excellent charge/discharge rate and good cycling stability, retaining over 99% of its initial charge after 1000 cycles. The results demonstrated that MnO2 is effectively utilized with assistance of ot...

Tunable multifunctional topological insulators in ternary Heusler compounds

Abstract: Recently the quantum spin Hall effect was theoretically predicted and experimentally realized in quantum wells based on the binary semiconductor HgTe (refs 1-3). The quantum spin Hall state and topological insulators are new states of quantum matter interesting for both fundamental condensed-matter physics and material science. Many Heusler compounds with C1(b) structure are ternary semiconductors that are structurally and electronically related to the binary semiconductors. The diversity of Heusler materials opens wide possibilities for tuning the bandgap and setting the desired band inversion by choosing compounds with appropriate hybridization strength (by the lattice parameter) and magnitude of spin-orbit coupling (by the atomic charge). Based on first-principle calculations we demonstrate that around 50 Heusler compounds show band inversion similar to that of HgTe. The topological state in these zero-gap semiconductors can be created by applying strain or by designing an appropriate quantum-well structure, similar to the case of HgTe. Many of these ternary zero-gap semiconductors (LnAuPb, LnPdBi, LnPtSb and LnPtBi) contain the rare-earth element Ln, which can realize additional properties ranging from superconductivity (for example LaPtBi; ref. 12) to magnetism (for example GdPtBi; ref. 13) and heavy fermion behaviour (for example YbPtBi; ref. 14). These properties can open new research directions in realizing the quantized anomalous Hall effect and topological superconductors.

Half-Heusler ternary compounds as new multifunctional experimental platforms for topological quantum phenomena

Abstract: Topological insulators have been predicted and recently demonstrated experimentally in a series of binary alloys. It is now show theoretically that ternary half-Heusler alloys have electronic properties similar to those of the experimentally verified topological insulators, and represent a platform for observing quantum topological phenomena.

Finding Nature’s Missing Ternary Oxide Compounds Using Machine Learning and Density Functional Theory

Abstract: Finding new compounds and their crystal structures is an essential step to new materials discoveries. We demonstrate how this search can be accelerated using a combination of machine learning techniques and high-throughput ab initio computations. Using a probabilistic model built on an experimental crystal structure database, novel compositions that are most likely to form a compound, and their most-probable crystal structures, are identified and tested for stability by ab initio computations. We performed such a large-scale search for new ternary oxides, discovering 209 new compounds with a limited computational budget. A list of these predicted compounds is provided, and we discuss the chemistries in which high discovery rates can be expected.

A study of ternary Cu2SnS3 and Cu3SnS4 thin films prepared by sulfurizing stacked metal precursors

Abstract: Thin films of Cu2SnS3 and Cu3SnS4 were grown by sulfurization of dc magnetron sputtered Sn–Cu metallic precursors in a S2 atmosphere. Different maximum sulfurization temperatures were tested which allowed the study of the Cu2SnS3 phase changes. For a temperature of 350 °C the films were composed of tetragonal (I-42m) Cu2SnS3. The films sulfurized at a maximum temperature of 400 °C presented a cubic (F-43m) Cu2SnS3 phase. On increasing the temperature up to 520 °C, the Sn content of the layer decreased and orthorhombic (Pmn21) Cu3SnS4 was formed. The phase identification and structural analysis were performed using x-ray diffraction (XRD) and electron backscattered diffraction (EBSD) analysis. Raman scattering analysis was also performed and a comparison with XRD and EBSD data allowed the assignment of peaks at 336 and 351 cm−1 for tetragonal Cu2SnS3, 303 and 355 cm−1 for cubic Cu2SnS3, and 318, 348 and 295 cm−1 for the Cu3SnS4 phase. Compositional analysis was done using energy dispersive spectroscopy and induced coupled plasma analysis. Scanning electron microscopy was used to study the morphology of the layers. Transmittance and reflectance measurements permitted the estimation of absorbance and band gap. These ternary compounds present a high absorbance value close to 104 cm−1. The estimated band gap energy was 1.35 eV for tetragonal (I-42m) Cu2SnS3, 0.96 eV for cubic (F-43m) Cu2SnS3 and 1.60 eV for orthorhombic (Pmn21) Cu3SnS4. A hot point probe was used for the determination of semiconductor conductivity type. The results show that all the samples are p-type semiconductors. A four-point probe was used to obtain the resistivity of these samples. The resistivities for tetragonal Cu2SnS3, cubic Cu2SnS3 and orthorhombic (Pmn21) Cu3SnS4 are 4.59 × 10−2 Ω cm, 1.26 × 10−2 Ω cm, 7.40 × 10−4 Ω cm, respectively.

A new platform for topological quantum phenomena : Topological Insulator states in thermoelectric Heusler-related ternary compounds

Abstract: Topological insulators (TI) realize a novel state of quantum matter that are distinguished by topological invariants of bulk band structure rather than spontaneously broken symmetries. A number of exotic quantum phenomena have been predicted to exist in multiply-connected geometries which require an enormous amount of materials flexibility. We have extended our previous search for TI materials from binary (Bi2X3 series) to the thermoelectric ternary compounds. We discover that the distorted LuPtSb is the first ternary compound harboring a 3D topological insulator state. We also show that the half-Heusler LuPtSb-type series is a natural platform that hosts a range of candidate compounds, alloys and artificial heterostructures (quantum-wells). We also discovered several different paradigms of trivial and non-trivial topological ordering in this class, including a metallic nontrivial topological state in YAuPb. Some of these materials are grown (results will be reported separately).

Super Toughened Poly(lactic acid) Ternary Blends by Simultaneous Dynamic Vulcanization and Interfacial Compatibilization

Abstract: In this study, a poly(lactic acid) (PLA) ternary blend system consisting of PLA, an epoxy-containing elastomer, and a zinc ionomer was introduced and studied in detail. Transmission electron microscopy revealed that the “salami”-like phase structure was formed in the ternary blends. While increase in blending temperature had little effects on the tensile properties of the resulting blends, it greatly changed the impact strength. For the blends prepared at 240 °C by extrusion blending, the resulting PLA ternary blends displayed supertoughness with moderate levels of strength and modulus. It was found that the zinc ions catalyzed the cross-linking of epoxy-containing elastomer and also promoted the reactive compatibilization at the interface of PLA and the elastomer. Both blending temperature and elastomer/ionomer ratio were found to play important roles in achieving supertoughness of the blends. The significant increase in notched impact strength was attributed to the effective interfacial compatibilizatio...

New Co-based γ-γ′ high-temperature alloys

Abstract: New cobalt-based alloys containing ordered L12 precipitates have been investigated. With additions of Cr, Mo, Ni, Re, Ta, and V to the ternary Co-Al-W system, two phase γ-γ′ microstructures have been established. Solidus and liquidus temperatures are 100°C–150°C higher than advanced nickel-based single-crystal alloys strengthened with the L12 phase. An anomalous rise in flow stress with temperature is observed. Single crystals have been solidified and partitioning during solidification is limited in the ternary system, suggesting a high resistance to convective instabilities. Oxidation at 900°C results in the formation of cobalt oxide. Following oxidation, an inner layer of Al2O3 is observed in uncoated Cr-containing alloys and Cr2O3 is observed in alloys subjected to chromization.

A small-molecule-based ternary data-storage device.

Abstract: High-density data storage (HDDS) is urgently required to address ongoing rapid increases in amounts of information. Here we present a prototype sandwich device that has ternary data-storage performance. Three characteristic currents can be read out using a certain constant voltage after removal of the applied voltage. Two electron pull groups and one electron push group are identified as the species responsible for electron flow. We believe that our observation will offer an interesting and useful theoretical approach for a huge increase in the memory density of potential future devices.

Scalable Routes to Janus Au−SiO2 and Ternary Ag−Au−SiO2 Nanoparticles

Abstract: Segregated ligand coordination on the Au surface was utilized to direct anisotropic silica deposition and generate Janus Au−SiO2 nanoparticles; subsequent growth of Ag selectively on the exposed Au surface led to ternary structures of Ag−Au−SiO2, where the Ag block was either a nanosphere or a nanorod.

Effect of Alloy Composition and Exposure Conditions on the Selective Oxidation Behavior of Ferritic Fe–Cr and Fe–Cr–X Alloys

Abstract: Selective oxidation behavior of ferritic martensitic Fe–Cr base alloys, exposed in various atmospheres containing combinations of O2, CO2, and H2O, were studied at various temperatures relevant to oxy-fuel combustion. This paper begins with a discussion of the required Cr content to form a continuous external chromia scale on a simple binary Fe–Cr alloy exposed in oxygen or air based on experiments and calculations using the classic Wagner model. Then, the effects of the exposure environment and Cr content on the selective oxidation of Fe–Cr alloys are evaluated. Finally, the effects produced by alloying additions of Si, commonly present in various groups of commercially available ferritic steels, are described. The discussion compares the oxide scale formation on simple binary and ternary Fe–Cr base model alloys with that on several commercially available ferritic steels.

Extraction of Benzene or Thiophene from n-Heptane Using Ionic Liquids. NMR and Thermodynamic Study

Abstract: In this work, 1H and 31P NMR spectroscopy were used to study the interactions between thiophene or benzene with three imidazolium based ionic liquids (ILs): 1-butyl-3-methylimidazolium tetrafluoroborate, 1,3-dimethylimidazolium methylphosphonate, and 1-butyl-3-methylimidazolium thiocyanate. NMR study indicates that solubility of thiophene or benzene in ionic liquid strongly depends on the structure of the ionic liquid. Structural organizations of such systems have been proposed. From these results, liquid−liquid equilibria (LLE) measurements of ternary mixtures containing benzene or thiophene with n-heptane and these ILs were carried out at 298.15 K in order to check the ability of these ILs to act as extractive solvents.

Textile Dye Removal from Single and Ternary Systems Using Date Stones: Kinetic, Isotherm, and Thermodynamic Studies

Abstract: In this paper, the removal of the dyes acid green 25 (AG25), acid black 26 (AB26), and acid blue 7 (AB7) onto date stones (DS) from single and ternary systems was investigated. Surface studies of DS were investigated by Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Experiments were carried out as a function of adsorbent dosage, initial dye concentration, inorganic anion (salt), pH, and temperature in single and ternary systems. The adsorption kinetics, isotherms, thermodynamics, and dye desorption were studied in single and ternary dye systems. The adsorption kinetics was modeled using the pseudofirst-order, pseudosecond-order, and intraparticle diffusion kinetics equations. The equilibrium adsorption data of AG25, AB26, and AB7 dyes on DS were analyzed. Thermodynamic parameters of dye adsorption were obtained. In addition, the regeneration of DS was studied using dye desorption in single and ternary dye systems. The adsorption kinetics of the dyes followed pseudosecond-order k...

Tunable Multifunctional Topological Insulators in Ternary Heusler Compounds

Abstract: Recently the Quantum Spin Hall effect (QSH) was theoretically predicted and experimentally realized in a quantum wells based on binary semiconductor HgTe[1-3]. QSH state and topological insulators are the new states of quantum matter interesting both for fundamental condensed matter physics and material science[1-11]. Many of Heusler compounds with C1b structure are ternary semiconductors which are structurally and electronically related to the binary semiconductors. The diversity of Heusler materials opens wide possibilities for tuning the band gap and setting the desired band inversion by choosing compounds with appropriate hybridization strength (by lattice parameter) and the magnitude of spin-orbit coupling (by the atomic charge). Based on the first-principle calculations we demonstrate that around fifty Heusler compounds show the band inversion similar to HgTe. The topological state in these zero-gap semiconductors can be created by applying strain or by designing an appropriate quantum well structure, similar to the case of HgTe. Many of these ternary zero-gap semiconductors (LnAuPb, LnPdBi, LnPtSb and LnPtBi) contain the rare earth element Ln which can realize additional properties ranging from superconductivity (e. g. LaPtBi[12]) to magnetism (e. g. GdPtBi[13]) and heavy-fermion behavior (e. g. YbPtBi[14]). These properties can open new research directions in realizing the quantized anomalous Hall effect and topological superconductors.

Direct Catalytic Asymmetric Addition of Allyl Cyanide to Ketones via Soft Lewis Acid/Hard Brønsted Base/Hard Lewis Base Catalysis

Abstract: We report that a hard Lewis base substantially affects the reaction efficiency of direct catalytic asymmetric gamma-addition of allyl cyanide (1a) to ketones promoted by a soft Lewis acid/hard Bronsted base catalyst. Mechanistic studies have revealed that Cu/(R,R)-Ph-BPE and Li(OC(6)H(4)-p-OMe) serve as a soft Lewis acid and a hard Bronsted base, respectively, allowing for deprotonative activation of 1a as the rate-determining step. A ternary catalytic system comprising a soft Lewis acid/hard Bronsted base and an additional hard Lewis base, in which the basicity of the hard Bronsted base Li(OC(6)H(4)-p-OMe) was enhanced by phosphine oxide (the hard Lewis base) through a hard-hard interaction, outperformed the previously developed binary soft Lewis acid/hard Bronsted base catalytic system, leading to higher yields and enantioselectivities while using one-tenth the catalyst loading and one-fifth the amount of 1a. This second-generation catalyst allows efficient access to highly enantioenriched tertiary alcohols under nearly ideal atom-economical conditions (0.5-1 mol % catalyst loading and a substrate molar ratio of 1:2).

Enhancing Thermoelectric Performance of Ternary Nanocrystals through Adjusting Carrier Concentration

Abstract: The carrier concentration of chemically synthesized Bi2Te3-based nanocrystals (NCs) is for the first time reported to be adjusted by forming ternary Bi2−xSbxTe3 NCs (x = 0.02, 0.05, 0.10, 0.20, 0.50, and 1.50) through partial substitution of Bi with Sb. Carrier concentrations of ternary Bi2−xSbxTe3 NCs were successfully adjusted by a factor of more than 10 controlled by the stoichiometric partial Sb/Bi substitution level. The power factors of the stoichiometric ternary Bi2−xSbxTe3 NCs improved three times compared to the parent Bi2Te3 due to the carrier concentration adjustment.

Solvothermal Synthesis and Characterization of Chalcopyrite CuInSe(2) Nanoparticles.

Abstract: The ternary I-III-VI2 semiconductor of CuInSe2 nanoparticles with controllable size was synthesized via a simple solvothermal method by the reaction of elemental selenium powder and CuCl as well as InCl3 directly in the presence of anhydrous ethylenediamine as solvent. X-ray diffraction patterns and scanning electron microscopy characterization confirmed that CuInSe2 nanoparticles with high purity were obtained at different temperatures by varying solvothermal time, and the optimal temperature for preparing CuInSe2 nanoparticles was found to be between 180 and 220 °C. Indium selenide was detected as the intermediate state at the initial stage during the formation of pure ternary compound, and the formation of copper-related binary phase was completely deterred in that the more stable complex [Cu(C2H8N2)2]+ was produced by the strong N-chelation of ethylenediamine with Cu+. These CuInSe2 nanoparticles possess a band gap of 1.05 eV calculated from UV–vis spectrum, and maybe can be applicable to the solar cell devices.

Separation of Carbon Dioxide and Sulfur Dioxide Using Room-Temperature Ionic Liquid [bmim][MeSO4]

Abstract: A ternary equation of state (EOS) model for the CO2/SO2/1-butyl-3-methylimidazolium methyl sulfate ([bmim][MeSO4]) system has been developed in order to gain further our understanding of capturing and enhanced gaseous selectivity of industrial flue gases containing CO2 and SO2 using room-temperature ionic liquids. The present model is based on a generic Redlich−Kwong (RK) EOS. The empirical binary interaction parameters have been determined using our measured vapor−liquid-equilibrium (VLE) data for SO2/[bmim][MeSO4] and literature data for CO2/[bmim][MeSO4] and CO2/SO2. The validity of the present EOS has been checked by conducting ternary VLE experiments for the present system. With this EOS, an isothermal ternary phase diagram and solubility (VLE) behaviors have been calculated for various (T, P, and feed compositions) conditions. The addition of the [bmim][MeSO4] for small and equimolar CO2/SO2 mole ratios significantly increased the selectivity. For large CO2/SO2 mole ratios, the selectivity was high ...

Band Gap Extension in a One-Dimensional Ternary Metal-Dielectric Photonic Crystal

Abstract: Comparing with an all-dielectric binary photonic crystal, we show, in this work, that the photonic band gap in ternary metal- dielectric photonic crystal can be signiflcantly enlarged. First, the band gap enlargement due to the addition of the metallic fllm is examined in the case of normal incidence. Next, in the oblique incidence, a wider omnidirectional band gap can be obtained in such a ternary metal-dielectric photonic crystal. All the theoretical analyses are made based on the transfer matrix method together with the Drude model of metals.

Aufbaureaktion Redux: Scalable Production of Precision Hydrocarbons from AlR3 (R=Et or iBu) by Dialkyl Zinc Mediated Ternary Living Coordinative Chain‐Transfer Polymerization

Abstract: In 1952, Karl Ziegler introduced the Aufbaureaktion, a process by which the controlled oligomerization of ethene can be accomplished using triethylaluminum (TEA) as a chaingrowth initiator at high pressure but relatively low temperature (cf. 100 8C, 100 bar). Commercial success of the Ziegler process, as it is now commonly known, is secured by the ability to provide a pseudo-Poisson distribution of long-chain linear a-olefins (LAOs) of the general formula H2C=CH(CH2)nCH3 (n = 1–15) and the corresponding saturated terminal alcohols HOCH2(CH2)n+1CH3 through direct chemical transformations of the Al[(CH2)n+2CH3]3 intermediates. [2] In 2006 alone, global production of LAOs stood at four million metric tons, with 55% of this volume being targeted for lubricants, plasticizers, detergents, additives, and fine chemical products. Unfortunately, no Aufbaureaktion for the controlled oligomerization of propene or long-chain a-olefins using TEA or other trialkyl aluminum species AlR3 as chaingrowth initiators has ever been developed. Accordingly, the potential technological value of new classes of hydrocarbonbased products that might be available from such processes on a commodity volume scale remains unknown. Herein, we report a new fundamental strategy, termed ternary living coordinative chain-transfer polymerization (t-LCCTP), for production of precision hydrocarbons (PHCs) through the living oligomerization and co-oligomerization of propene and long-chain a-olefins. PHCs represent a new class of polyolefins that are distinguished by having programmable and architecturally discrete carbon–carbon bonded frameworks, very low (e.g. oligomeric) molecular weights, and extremely narrow molecular weight distributions. With foreseeable benefits to society of PHCs as green and sustainable synthetic base stock oils and waxes for a broad range of technological applications, the ability of t-LCCTP to provide scalable volumes of these materials in a simple atom-economical and cost-effective manner from existing commodity AlR3 reagents at ambient temperatures is highly comparable to the original Ziegler process. Recently, we reported that the living coordinative chaintransfer polymerization (LCCTP) and copolymerization of ethene, propene, long-chain a-olefins, and a,w-nonconjugated dienes could be achieved using [(hC5Me5)Hf(Me){N(Et)C(Me)N(Et)}][B(C6F5)4] (1) as the active transition-metal initiator for chain-growth propagation, along with multiple stoichiometric equivalents (relative to 1) of diethylzinc (DEZ) that serve as surrogate chaingrowth centers. A fundamental requirement for successful LCCTP of these monomers is that the rate and rate constant, nct and kct, respectively, for reversible (polymeryl group) chain transfer between the active transition-metal propagating centers and the inactive surrogate main-group-metal species must be far greater than the corresponding kinetic parameters np and kp for transition-metal-mediated propagation to insure that all active (A) and surrogate (S) species appear to propagate at the same rate. Within this kinetic scheme, the number-average degree of polymerization Cn for the final polyolefin product is defined by Xn = ([monomer]0 [monomer]t)/[A+nxS]0, where x is the initial number of molar equivalents of main-group-metal alkyl species relative to the transition-metal initiator and n is the number of alkyl groups of the surrogate species that engage in rapid and reversible chain transfer (e.g. n = 2 for DEZ). 8] An extremely narrow Poisson molecular weight distribution for the polyolefin product is also expected for the case where kct @ kp, since, to a first-order approximation, the polydispersity index D is defined by D = Mw/Mn 1 + kp/kct, where Mw and Mn are the weight-average and number-average molecular weight indices, respectively. Typically, values of D for polyolefins obtained from LCCTP using 1 and DEZ are 1.04– 1.09. Since the final yield of polyolefin product obtained through LCCTP is now virtually dependent upon only the initial amount of DEZ employed, this process circumvents the critical one-polymer-chain-per-metal-center criterion of traditional living coordination polymerization that has proven to be an insurmountable liability for the scalable production of precision polyolefins and PHCs. 10] On the other hand, from a cost and safety perspective, the transport and handling of industrial volumes of DEZ is still problematic, and accordingly, the existing dependence of the current LCCTP process on this reagent could prove to be an Achilles heel limiting the successful commercialization of PHCs and PHC-based products. In this respect, TEA and triisobutylaluminum (TIBA), which are produced on a commodity scale from aluminum metal, dihydrogen, and ethene and isobutene, respectively, are significantly less expensive and substantially less pyrophoric than DEZ. An additional advantage of these AlR3 compounds over DEZ in terms of product yield is realized if [*] J. Wei, W. Zhang, Prof. L. R. Sita Department of Chemistry and Biochemistry, University of Maryland College Park, MD 20742 (USA) Fax: (+ 1)301-314-9121 E-mail: lsita@umd.edu

The effects of CdSe incorporation into bulk heterojunction solar cells

Abstract: Hybrid solar cells based on CdSe nanoparticles and a PPV-type polymer containing fluorene and thiophene units (PFT) were investigated. The CdSe/PFT devices showed very low photocurrent and fill factor values, which was attributed to the poor charge transport in the TOPO-capped CdSe nanoparticle phase. Thus, ternary systems based on mixtures of PFT/CdSe and the fullerene derivative PCBM were investigated. The CdSe:PCBM ratio was varied, and nanoparticles with different sizes were also used. It was observed that for the optimized composition of 20 wt% PFT + 40 wt% CdSe + 40 wt% PCBM the devices presented higher photocurrents and efficiencies. The photophysical and electrochemical properties and microscopy images (AFM and HRTEM) of the ternary systems were systematically investigated to elucidate the mechanism of action of the inorganic nanoparticles in these ternary hybrid devices.