High-Throughput Study of the Cu(CH3COO)(2)center dot H2O-5-Nitroisophthalic Acid Heterocyclic Ligand System: Synthesis, Structure, Magnetic, and Heterogeneous Catalytic Studies of Three Copper Nitroisophthalates

A high-throughput screening was employed to identify new compounds in Cu(CH3COO)(2)center dot H2O-NIPA-heterocyclic ligand systems. Of the compounds identified, three compounds, Cu-3{(NO2)-C6H3-(COO)(2)}(3)(C3N6H6)] (1), Cu-2(mu(3)-OH)(H2O){(NO2)-C6H3-(COO)(2)}(CN4H)]center dot-(H2O) (II), and Cu-2(mu(3)-OH)(H2O){(NO2)-C6H3-(COO)(2}-)(CN5H2)]center dot 2(H2O) (III), have been isolated as good quality single crystals by employing conventional hydrothermal methods. Three other compounds, Cu-2{(NO2)-C6H3-(COO)(2)}-(CN4H)(H2O) (IIa), Cu-2{(NO2)-C6H3-(COO)(2)}(CN5H2) (IIIa), and Cu-2{(NO2)-C6H3-(COO)(2)}{(CN5H2)(2)}2H(2)O (IIIb), were identified by a combination of elemental analysis, thermogravimetric analysis (TGA), and IR spectroscopic studies, although their structures are yet to be determined. The single crystalline compounds were also characterized by elemental analysis, TGA, IR, UV vis, magnetic, and catalytic studies. The structures of the compounds have paddle wheel (I) and infinite Cu 0(H) Cu chains (II and HI) connected with NLPA and heterocyclic ligands forming two-(II) and three-dimensional (I and III) structures. The bound and lattice water molecules in 11 and 111 could be reversibly removed/inserted without affecting the structure. In the case of II, the removal of water gives rise to a structural transition, but the dehydrated phase reverts back to the original phase on prolonged exposure to atmospheric conditions. Magnetic studies indicate an overall antiferromagnetism in all of the compounds. Lewis acid catalytic studies indicate that compounds II and HI are active for cyanosilylation of imines.

Solid state amorphization in binary Ti---Ni, Ti---Cu and ternary Ti---Ni---Cu system by mechanical alloying

An amorphous phase has been synthesized by mechanical alloying in a planetary mill over a nickel content range of 10�70 at.% in the Ti---Ni system and a copper content range of 10�50 at.% in the Ti---Cu system. In the case of ternary Ti---Ni---Cu alloys the glass-forming composition range has been found to be given by x = 10�20 for Ti60Ni40 ? xCux, x = 10 � 30 for Ti50Ni50 ? xCux and x = 10 � 40 for Ti40Ni60 ? xCux alloys. The difficulty in the amorphization of copper-rich compositions is explained in the light of enthalpy composition diagrams calculated for the ternary solid solution and the amorphous phase.

Activities in the spinel solid solution, phase equilibria and thermodynamic properties of ternary phases in the system Cu Fe O

A review of the structural and thermodynamic information and phase equilibria in the Cu-Fe-O system suggested that a consistent, quantitative description of the system is hampered by lack of data on activities in the spinel solid solution CuFe2O4-Fe3O4. Therefore the activity of Fe3O4 in this solid solution is derived from measurements of the oxygen potentials established at 1000°C by mixtures containing Fe2O3 and spinel solid solutions of known composition. The oxygen pressures were measured manometrically for solid solutions rich in CuFe2O4, while for Fe3O4-rich compositions the oxygen potentials were obtained by an emf technique. The activities show significant negative deviations from Raoult’s law. The compositions of the spinel solid solutions in equilibrium with CuO + CuFeO2 and Cu + CuFeO2 were obtained from chemical analysis of the solid solution after magnetic separation. The oxygen potential of the three-phase mixture Cu + CuFeO2 + Fe3O4(spinel s.s.) was determined by a solid oxide galvanic cell. From these measurements a complete phase diagram and consistent thermodynamic data on the ternary condensed phases, CuFeO2 and CuFeO2O4, were obtained. An analysis of the free energy of mixing of the spinel solid solution furnished information on the distribution of cations and their valencies between the tetrahedral and octahedral sites of the spinel lattice, which is consistent with X-ray diffraction, magnetic and Seebeck coefficient measurements.

Gibbs energy of formation of CuCrO4 and phase relations in the system Cu-Cr-O below 735 K

A solid state galvanic cell incorporating yttria-stabilized zirconia electrolyte and ruthenium(IV) oxide electrodes has been used to measure the equilibrium chemical potential of oxygen corresponding to the decomposition of CuCrO4 in the range 590–760 K. For the reaction CuO(tenorite) + CuCr2O4(spinel) + 1.5O2(g)→2CuCrO4(orth), ΔGXXX = −183540 + 249.6T(±900) J mol−1. The decomposition temperature of CuCrO4 in pure oxygen at a pressure of 1.01 × 105 Pa is 735(±1) K. By combining the results obtained in this study with data on the Gibbs energy of formation of CuCr2O4 and CuCrO2 reported earlier, the standard Gibbs energy of formation of CuCrO4 and the phase relations in the system Cu-Cr-O at temperatures below 735 K have been deduced. Electron microscopic studies have indicated that the decomposition of CuCrO4 to CuCr2O4 is topotactic.

System Cu-Rh-O: Phase diagram and thermodynamic properties of ternary oxides CuRhO2 and CuRh204

An isothermal section of the phase diagram for the system Cu-Rh-O at 1273 K has been established by equilibration of samples representing eighteen different compositions, and phase identification after quenching by optical and scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive analysis of X-rays (EDX). In addition to the binary oxides Cu2O, CuO, and Rh2O3, two ternary oxides CuRhO2 and CuRh2O4 were identified. Both the ternary oxides were in equilibrium with metallic Rh. There was no evidence of the oxide Cu2Rh2O5 reported in the literature. Solid alloys were found to be in equilibrium with Cu2O. Based on the phase relations, two solid-state cells were designed to measure the Gibbs energies of formation of the two ternary oxides. Yttria-stabilized zirconia was used as the solid electrolyte, and an equimolar mixture of Rh+Rh2O3 as the reference electrode. The reference electrode was selected to generate a small electromotive force (emf), and thus minimize polarization of the three-phase electrode. When the driving force for oxygen transport through the solid electrolyte is small, electrochemical flux of oxygen from the high oxygen potential electrode to the low potential electrode is negligible. The measurements were conducted in the temperature range from 900 to 1300 K. The thermodynamic data can be represented by the following equations: {fx741-1} where Δf(ox) G o is the standard Gibbs energy of formation of the interoxide compounds from their component binary oxides. Based on the thermodynamic information, chemical potential diagrams for the system Cu-Rh-O were developed.

Phase relations in the system Cu-La-O and thermodynamic properties of CuLaO2 and CuLa2O4

Phase relations in the system Cu-La-O at 1200 K have been determined by equilibrating samples of different average composition at 1200 K, and phase analysis of quenched samples using optical microscopy, XRD, SEM and EDX. The equilibration experiments were conducted in evacuated ampoules, and under flowing inert gas and pure oxygen. There is only one stable binary oxide La2O3 along the binary La-O, and two oxides Cu2O and CuO along the binary Cu-O. The Cu-La alloys were found to be in equilibrium with La2O3. Two ternary oxides CuLaO2 and CuLa2O4+

Phase relations in the system Cu-Eu-O and thermodynamic properties of CuEu2O4 and CuEuO2

Phase relations in the system Cu-Eu-O have been determined by equilibrating samples of different average composition at 1200 K and by phase analysis after quenching using optical microscopy (OM), x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray (EDX). The equilibration experiments were conducted in evacuated ampoules and under flowing inert gas and pure oxygen. The Cu-Eu alloys were found to be in equilibrium with EuO. The higher oxides of europium, Eu3O4 and Eu2O3, coexist with metallic copper. Two ternary oxides CuEu2O4 and CuEuO2 were found to be stable. The ternary oxide CuEuO2, with copper in the monovalent state, can coexist with Cu, Cu2O, Eu2O3 and CuEu2O4 in different phase fields. The compound CuEu2O4 can be in equilibrium with Cu2O, CuO, CuEuO2, Eu2O3, and O2 gas under different conditions at 1200 K. Thermodynamic properties of the ternary oxides were determined using three solid-state cells based on yttria-stabilized zirconia as the electrolyte in the temperature range from 875 to 1250 K. The cells essentially measure the oxygen chemical potential in the three-phase fields: Cu+Eu2O3+CuEuO2, Cu2O+CuEuO2+CuEu2O4, and Eu2O3+CuEuO2+CuEu2O4. The thermodynamic properties of the ternary oxides can be represented by the equations: $\begin{gathered} {\raise0.5ex\hbox{$Couldn't find \end for begin{gathered} Thermogravimetric analysis (TGA) studies in Ar+O2 mixtures confirmed the results from emf measurements. An oxygen potential diagram for the system Cu-Eu-O at 1200 K was evaluated from the results of this study and information available in the literature on the binary phases.

Influence of Bottom Bubbling Rate on Formation of Metal Emulsion in Al-Cu Alloy and Molten Salt System

In steel refining process, an increase of interfacial area between the metal and slag through the metal droplets emulsified into the slag, so-called ``metal emulsion'', is one prevailing view for improving the reaction rate. The formation of metal emulsion was experimentally evaluated using Al-Cu alloy as metal phase and chloride salt as slag phase under the bottom bubbling condition. Samples were collected from the center of the salt phase in the container. Large number of metal droplets were separated from the salt by dissolving it into water. The number, surface area, and weight of the droplets increased with the gas flow rate and have local maximum values. The formation and sedimentation rates of metal droplets were estimated using a mathematical model. The formation rate increased with the gas flow rate and has a local maximum value as a function of gas flow rate, while the sedimentation rate is independent of the gas flow rate under the bottom bubbling condition. Three types of formation mode of metal emulsion, which occurred by the rupture of metal film around the bubble, were observed using high speed camera. During the process, an elongated column covered with metal film was observed with the increasing gas flow rate. This elongated column sometimes reached to the top surface of the salt phase. In this case, it is considered that fine droplets were not formed and in consequence, the weight of metal emulsion decreased at higher gas flow rate.

Experimental study of phase equilibria in the system Cu-Al-Sn

Phase equilibria in the Cu-rich corner of the ternary system Cu-Al-Sn have been re-investigated. Final equilibrium microstructures of 20 ternary alloy compositions near Cu3Al were used to refine the ternary phase diagram. The microstructures were characterized using optical microscopy (OM), x-ray diffraction (XRD), electron probe microanalysis and transmission electron microscopy. Isothermal sections at 853, 845, 833, 818, 808, 803 and 773 K have been composed. Vertical sections have been drawn at 2 and 3 at% Sn, showing beta(1) as a stable phase. Three-phase fields (alpha + beta + beta(1)) and (beta + beta(1) + gamma(1)) result from beta -> alpha + beta(1) eutectoid and beta + gamma(1) -> beta(1) peritectoid reactions forming metastable beta(1) in the binary Cu-Al. With the lowering of temperature from 853 to 818 K, these three-phase fields are shifted to lower Sn concentrations, with simultaneous shrinkage and shifting of (beta + beta(1)) two-phase field. The three-phase field (alpha + beta + gamma(1)) resulting from the binary reaction beta -> alpha + gamma(1) shifts to higher Sn contents, with associated shrinkage of the beta field, with decreasing temperature. With further reduction of temperature, a new ternary invariant reaction beta + beta(1) -> alpha + gamma(1) is observed at similar to 813 K. The beta disappears completely at 803 K, giving rise to the three-phase field (alpha + beta(1) + gamma(1)). Some general guidelines on the role of ternary additions (M) on the stability of the ordered beta(1) phase are obtained by comparing the results of this study with data in the literature on other systems in the systems group Cu-Al-M.

Purifying water containing both anionic and cationic species using a (Zn, Cu)O, ZnO, and Cobalt Ferrite based multiphase adsorbent system

For the purpose of water purification, novel and low-cost adsorbents which are promising replacements for activated carbon are being actively pursued. However, a single-phase material that adsorbs both cationic and anionic species remains elusive. Hence, a low-cost, multiphase adsorbent bed that purifies water containing both anionic and cationic pollutants is a desirable alternative. We choose anionic (Congo red, Orange G) and cationic (methylene blue, malachite green) dyes as model pollutants. These dyes are chosen since they are widely found in effluents from textile, leather, fishery, and pharmaceutical industries, and their carcinogenic, mutagenic, genotoxic, and cytotoxic impact on mammalian cells is well-established. We show that ZnO, (Zn0.24Cu0.76)O and cobalt ferrite based multiphase fixed adsorbent bed efficiently adsorbs model anionic (Congo red, Orange G) and cationic (methylene blue and malachite green) pollutants, and their complex mixtures. All adsorbent phases are synthesized using room-temperature, high-yield (similar to 96-100%), green chemical processes. The nanoadsorbents are characterized by using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, and zeta potential measurements. The constituent nanophases are deliberately chosen to be beyond 50 nm, in order to avoid the nanotoxic size regime of oxides. Adsorption characteristics of each of the phases are examined. Isotherm based analysis shows that adsorption is both spontaneous and highly favorable. zeta potential measurements indicate that electrostatic interactions are the primary driving force for the observed adsorption behavior. The isotherms obtained are best described using a composite Langmuir-Freundlich model. Pseudo-first-order, rapid kinetics is observed (with adsorption rate constants as high as 0.1-0.2 min(-1) in some cases). Film diffusion is shown to be the primary mechanism of adsorption.

Development of alloys with high strength at elevated temperatures by tuning the bimodal microstructure in the Al-Cu-Ni eutectic system

The development of high-strength aluminum alloys that can operate at 250 degrees C and beyond remains a challenge to the materials community. In this paper we report preliminary development of nanostructural Al-Cu-Ni ternary alloys containing alpha-Al, binary Al2Cu and ternary Al2Cu4Ni intermetallics. The alloys exhibits fracture strength of similar to 1 GPa with similar to 9% fracture strain at room temperature. At 300 degrees C, the alloy retains the high strength. The reasons for such significant mechanical properties are rationalized by unraveling the roles and response of various microstructural features. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effect of Ni content on the diffusion-controlled growth of the product phases in the Cu(Ni)-Sn system

A strong influence of Ni content on the diffusion-controlled growth of the (Cu,Ni)(3)Sn and (Cu,Ni)(6)Sn-5 phases by coupling different Cu(Ni) alloys with Sn in the solid state is reported. The continuous increase in the thickness ratio of (Cu,Ni)(6)Sn-5 to (Cu,Ni)(3)Sn with the Ni content is explained by combined kinetic and thermodynamic arguments as follows: (i) The integrated interdiffusion coefficient does not change for the (Cu,Ni)(3)Sn phase up to 2.5 at.% Ni and decreases drastically for 5 at.% Ni. On the other hand, there is a continuous increase in the integrated interdiffusion coefficient for (Cu,Ni)(6)Sn-5 as a function of increasing Ni content. (ii) With the increase in Ni content, driving forces for the diffusion of components increase for both components in both phases but at different rates. However, the magnitude of these changes alone is not large enough to explain the high difference in the observed growth rate of the product phases because of Ni addition. (iv) Kirkendall marker experiments indicate that the Cu6Sn5 phase grows by diffusion of both Cu and Sn in the binary case. However, when Ni is added, the growth is by diffusion of Sn only. (v) Also, the observed grain refinement in the Cu6Sn5 phase with the addition of Ni suggests that the grain boundary diffusion of Sn may have an important role in the observed changes in the growth rate.

Development of the 2003 CU-HTK conversational telephone speech transcription system

This paper describes the development of the 2003 CU-HTK large vocabulary speech recognition system for Conversational Telephone Speech (CTS). The system was designed based on a multi-pass, multi-branch structure where the output of all branches is combined using system combination. A number of advanced modelling techniques such as Speaker Adaptive Training, Heteroscedastic Linear Discriminant Analysis, Minimum Phone Error estimation and specially constructed Single Pronunciation dictionaries were employed. The effectiveness of each of these techniques and their potential contribution to the result of system combination was evaluated in the framework of a state-of-the-art LVCSR system with sophisticated adaptation. The final 2003 CU-HTK CTS system constructed from some of these models is described and its performance on the DARPA/NIST 2003 Rich Transcription (RT-03) evaluation test set is discussed.

The CU-HTK Mandarin broadcast news transcription system

This paper discusses the development of the CU-HTK Mandarin Broadcast News (BN) transcription system. The Mandarin BN task includes a significant amount of English data. Hence techniques have been investigated to allow the same system to handle both Mandarin and English by augmenting the Mandarin training sets with English acoustic and language model training data. A range of acoustic models were built including models based on Gaussianised features, speaker adaptive training and feature-space MPE. A multi-branch system architecture is described in which multiple acoustic model types, alternate phone sets and segmentations can be used in a system combination framework to generate the final output. The final system shows state-of-the-art performance over a range of test sets. ©2006 British Crown Copyright.