Phase Diagrams Research Papers - Academia.edu (original) (raw)

Pure diblock copolymer melts exhibit a narrow range of conditions at which bicontinuous and cocontinuous phases are stable; such conditions and the morphology of such phases can be tuned by the use of additives. In this work, we have studied a bidisperse system of diblock copolymers using theory and simulation. In particular, we elucidated how a short, lamellar-forming diblock copolymer modifies the phase behavior of a longer, cylinder-forming diblock copolymer. In a narrow range of intermediate compositions, self-consistent field theory predicts the formation of a gyroid phase although particle-based simulations show that three phases compete: the gyroid phase, a disordered cocontinuous phase, and the cylinder phase, all having free energies within error bars of each other. Former experimental studies of a similar system have yielded an unidentified, partially irregular bicontinuous phase, and our simulations suggest that at such conditions the formation of a partially transformed network phase is indeed plausible. Close examination of the spatial distribution of chains reveals that packing frustration (manifested by chain stretching and low density spots) occurs in the majority-block domains of the three competing phases simulated. In all cases, a double interface around the minority-block domains is also detected with the outer one formed by the short chains, and the inner one formed by the longer chains.

- by
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- Engineering, Self Assembly, Polymer Blends, Phase Diagrams

The phase diagram of water as obtained from computer simulations is presented for the first time for two of the most popular models of water, TIP4P and SPC=E. This Letter shows that the prediction of the phase diagram is an extremely stringent test for any water potential function, and that it may be useful in developing improved potentials. The TIP4P model provides a qualitatively correct description of the phase diagram, unlike the SPC=E model which fails in this purpose. New behavior not yet observed experimentally is predicted by the simulations: the existence of metastable reentrant behavior in the melting curves of the low density ices (I; III; V) such that it could be possible to transform them into amorphous phases by adequate changes in pressure.

- by Carlos Vega
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- Phase Diagrams, Computer Simulation, Physical sciences, Free Energy

Inspired by experimental studies of short-ranged attractive patchy particles, we study with computer simulations the phase behavior and the crystalline structures of one-patch colloids with an interaction range equal to 5% of the particle diameter. In particular, we study the effects of the patch surface coverage fraction, defined as the ratio between the attractive and the total surface of a particle. Using free-energy calculations and thermodynamic integration schemes, we evaluate the equilibrium phase diagrams for particles with patch coverage fractions of 30%, 50% and 60%. For a 60% surface coverage fraction, we observe stable lamellar crystals consisting of stacked bilayers that directly coexist with a low density fluid. Inside the coexistence region, we observe the formation of lamellar structures also in direct NVT simulations, indicating that the barrier of formation is low and experimental realization is feasible.

The speed of sound was measured in solutions of sucrose (0-70 wt/vol%), glycerol (0-30 wt/vol%) and orange juice (0-40 solids wt/vol%) as a function of temperature (10°C to À13°C). The velocity (c) in the unfrozen solutions, including the supercooled samples, could be modeled as a simple linear function of temperature (T,°C) and composition (x, wt/vol%): c = c w + k x x + k T T where c w is the speed of sound in water at 0°C, and k x and k T are solute-dependant constants. There was a large increase in ultrasonic velocity corresponding to freezing in these samples (e.g., an unfrozen 10% sucrose solution has a speed of sound of 1416 m s À1 at À5°C while a similar frozen solution has a velocity of 1983 m s À1 ). The ice content was estimated from phase diagrams of similar samples and was a linear function of the change in ultrasonic velocity upon freezing for samples <8°C. Some details of the effects of ice microstructure and possible theoretical approaches to its effects on ultrasonic properties are also discussed.

- by John Coupland
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- Food Engineering, Ultrasound, Phase Diagrams, Models

The effect of tin content in the equilibrium phases of the Cu-Zn-based alloys, within the range of chemical compositions with interest to brass producers is described. For this purpose, ternary alloys with copper contents between 55.4 and 67.5 wt.% and tin contents up to 5.30 wt.% have been studied. The chemical composition of each alloy has been determined by X-ray fluorescence spectrometry (XRF). Isothermal homogenization, followed by rapid cooling, has been employed to determine the equilibrium phases at different temperatures. The homogenized alloys have been observed by scanning electron microscopy and the respective chemical analysis of the phases determined by electron probe microanalysis (EPMA). The statistical analysis of the obtained results enable to correlate the chemical composition of equilibrium phases with temperature. The chemical composition of the three-phase field, for the studied temperatures, has also been determined.

- by Delfim Soares
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- Microstructure, Phase Diagrams, Phase equilibria

High hydrostatic pressure constitutes an efficient physical tool to modify food biopolymers, such as proteins or starches. This review presents data on the effects of high hydrostatic pressure in combination with temperature on protein stability, enzymatic activity and starch gelatinization. Attention is given to the protein thermodynamics in response to combined pressure and temperature treatments specifically on the pressuretemperature-isokineticity phase diagrams of selected enzymes, prions and starches relevant in food processing and biotechnology.

- by D. Knorr and +1
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- Thermodynamics, High Pressure, Starch, Food Processing

Using micromagnetic modeling, we calculate numerically the magnetization reversal of soft permalloy cones of height and diameter ≤ 100nm. By varying the cone height and the base diameter in steps of 10nm and 5nm, respectively, we map the remanent states systematically. We observe reversal mechanisms with remanent configurations ranging from single domains at small diameters, through buckle states and complex C-states through to vortex states at larger diameters and heights. We present a phase-diagram of the remanent states of magnetization as a function of diameter and height. For the largest cones investigated, we find magnetization configurations in the reversal process which consist of two superimposed vortices with cores pointing in orthogonal directions.

- by Alexander Zhukov
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- Mechanical Engineering, Condensed Matter Physics, Micromagnetism, Phase Diagrams

The extended Bose-Hubbard model in a quadratic trap potential is studied using a finitesize density-matrix renormalization group method (DMRG). We compute the boson density profiles, the local compressibility and the hopping correlation functions. We observed the phase separation induced by the trap in all the quantities studied and conclude that the local density approximation is valid in the extended Bose-Hubbard model. From the plateaus obtained in the local compressibility it was possible to obtain the phase diagram of the homogeneous system which is in agreement with previous results.

- by A. Rosengren
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- Localization, Transition, Phase Diagrams, Bose Hubbard Model

- by Carlos Vega
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- Phase Diagrams, Computer Simulation, Physical sciences, Free Energy

A key parameter that controls the crystallization of primordial oceans in large icy moons is the presence of antifreeze compounds, which may have maintained primordial oceans over the age of the solar system. Here we investigate the influence of methanol, a possible anti-freeze candidate, on the crystallization of Titan's primordial ocean. Using a thermodynamic model of the solar nebula and assuming a plausible composition of its initial gas phase, we first calculate the condensation sequence of ices in Saturn's feeding zone, and show that in Titan's building blocks methanol can have a mass fraction of ∼4 wt% relative to water, i.e., methanol can be up to four times more abundant than ammonia. We then combine available data on the phase diagram of the water-methanol system and scaling laws derived from thermal convection to estimate the influence of methanol on the dynamics of the outer ice I shell and on the heat transfer through this layer. For a fraction of methanol consistent with the building blocks composition we determined, the vigor of convection in the ice I shell is strongly reduced. The effect of 5 wt% methanol is equivalent to that of 3 wt% ammonia. Thus, if methanol is present in the primordial ocean of Titan, the crystallization may stop, and a sub-surface ocean may be maintained between the ice I and high-pressure ice layers. A preliminary estimate indicates that the presence of 4 wt% methanol and 1 wt% ammonia may result in an ocean of thickness at least 90 km.

- by Olivier Mousis
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- Organic Chemistry, Astrophysical Plasma, Convection, High Pressure

We have made some progress in studies towards formation and measurement of the behavior of asphaltene micelles nano-structures that might be formed to serve as elements of nano-materials and also on synthetic strategies for creating such structures. An investigation of the micellization and coacervation measurements of asphaltenes in polar solvents at various concentrations and temperatures are made. The critical micellization concentration (CMC) and the micelle coacervation point (MCP) of nano-structure asphaltene micelles are measured using viscometry. At concentration above the CMC, asphaltene in the solution will self-associate, saturation phase will be formed and then at a higher concentration asphaltene nano-structure micelles in the solution will coacervate represented by a second sharp point of innection corresponding to the asphaltene MCP and finally, at a higher concentration the aggregation of asphaltenes coacervates will occur. As a result of these measurements, for the first time it has become possible to produce phase diagrams for the whole range of asphaltene micellization and micelle coacervation.

Many condensed matter experiments explore the finite temperature dynamics of systems near quantum critical points. Often, there are no well-defined quasiparticle excitations, and so quantum kinetic equations do not describe the transport properties completely. The theory shows that the transport co-efficients are not proportional to a mean free scattering time (as is the case in the Boltzmann theory of quasiparticles), but are completely determined by the absolute temperature and by equilibrium thermodynamic observables. Recently, explicit solutions of this quantum critical dynamics have become possible via the AdS/CFT duality discovered in string theory. This shows that the quantum critical theory provides a holographic description of the quantum theory of black holes in a negatively curved anti-de Sitter space, and relates its transport co-efficients to properties of the Hawking radiation from the black hole. We review how insights from this connection have led to new results for experimental systems: (i) the vicinity of the superfluid-insulator transition in the presence of an applied magnetic field, and its possible application to measurements of the Nernst effect in the cuprates, (ii) the magnetohydrodynamics of the plasma of Dirac electrons in graphene and the prediction of a hydrodynamic cyclotron resonance. this state, but there is a well-developed theory of the transport properties of the TL liquid. Historically, this theory evolved over several decades of research on quantum many body systems in one dimension. Key in the historical development were exact solutions of model Hamiltonians via the Bethe Ansatz. Insights gained from the structure of excitations in the Bethe Ansatz solutions led to a more general understanding of the low energy excitations of a generic Hamiltonian, and a universal low energy theory of the TL liquid. Thus while the exact solutions were restricted to artificial models, they played a key role in the development of the general theory. Of course, after the fact, with the general theory of the TL liquid before us, we can justify it in its own terms, and largely dispense with reference to the Bethe Ansatz solutions.

- by Avi Raveh
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- Microstructure, Boundary Layers, Information, Crystal structure

A thermodynamic description is presented for the ternary Cu-Al-Si system in its copper-rich corner. The thermodynamic parameters of the subsystems , Cu-Al, Cu-Si and Al-Si, are taken from earlier SGTE-based assessments and those of the ternary system are optimized in this study by using the experimental mixing enthalpy and phase equilibrium data. The present ternary description is valid for aluminum contents up to 18 wt% and silicon contents up to 8 wt%.

- by Jyrki Miettinen
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- Materials Engineering, Thermodynamics, Chemistry, Computational Modeling

The cluster variation method (CVM) has been used as a tool for modelling the thermodynamics of the b.c.c. Co–Cr–Al system within the irregular tetrahedron approximation. The interaction parameters (nearest and next-nearest neighbour pairs, as well as tetrahedron interactions) for the three binary subsystems have been derived following the so-called phenomenological approach, i.e. the interaction parameters have been fitted to experimental phase diagram and/or thermochemical data. As a result, the three binary phase diagrams of the system and four isothermal sections of the ternary phase diagram have been obtained. The results show that the CVM is thermodynamically self-consistent.

- by Cláudio G Schön
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- Thermodynamics, Intermetallics, Phase Diagrams

Recent binary thermodynamic descriptions are used as a starting point for the modelling of the ternary Nb–Ni–Si phase diagram. First-principles electronic structure calculations, within the framework of the Density Functional Theory (DFT), are performed for the determination of formation energies of known ternary compounds. The results are introduced into a CALPHAD-type thermodynamic model using the Compound Energy Formalism (CEF). The model parameters are then optimised in order to match the experimental 1073 K isothermal section of the ternary phase diagram.

- by Cláudio G Schön and +1
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- Thermodynamics, Intermetallics, Phase Diagrams, Multicomponent Alloys

Clopidogrel, an inhibitor of platelet aggregation, selectively inhibits the binding of adenosine diphosphate (ADP) to its platelet receptor and the subsequent ADP-mediated activation of the glycoprotein GPIIb/IIIa complex, thereby inhibiting platelet aggregation. Oral bioavailability of clopidogrel is very low (less than 50%), due to its poor water solubility. The aim of this investigation was to design and develop a microemulsion formulation of clopidogrel for enhancing its solubility, and hence its oral bioavailability. For this purpose, initially, solubility of clopidogrel was determined in various vehicles. Next, pseudo-ternary phase diagrams were constructed to identify the microemulsion existing zone. Solubility study was also performed for optimization of formulation. The optimized microemulsion formulation was characterized for its transparency, droplet size, zeta potential, viscosity, conductivity, % assay, and phase separation study. Particle size and zeta potential of the...

- by Naazneen Surti
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- Bioinformatics, Chemistry, Life Sciences, Medicine

Since the Bronze Age, humans have been altering the properties of materials by adding alloying elements. For example, a few percent by weight of copper was added to silver to produce sterling silver for coinage a thousand years ago, because pure silver was too soft. Examples from the modern era include steels that consist primarily of iron, to which elements such as carbon and chromium are added for strength and corrosion resistance, respectively, and copper alloyed with beryllium to make it strong and non-sparking for use in explosive environments. With few exceptions, the basic alloying strategy of adding relatively small amounts of secondary elements to a primary element has remained unchanged over millennia. It is even reflected in the way alloys are named after their principal constituent: ferrous alloys, aluminium alloys, titanium alloys, nickel alloys and so on. However, such a primary-element approach drastically limits the total number of possible element combinations and, therefore, alloys, most of which have been identified and exploited. New approaches are needed if the compositional space to explore is to be significantly enlarged. One such approach is based on mixing together multiple principal elements in relatively high (often equi-atomic) concentrations. This approach stands in sharp contrast to the traditional practice and has, therefore, attracted much attention. The related surge in research activity, especially during the past 5 years, can be traced back to the publication of two seminal papers 1,2 in 2004. Two groups independently proposed the study of a new class of alloys containing multiple elements in near-equiatomic concentrations. It was subsequently pointed out that conventional alloys tend to cluster around the corners or edges of phase diagrams, where the number of possible element combinations is limited, and that vastly more numerous combinations are available near the centres of phase diagrams, especially in quaternary, quinary and higher-order systems 3. Owing to their sheer numbers, little is known about concentrated, multi-component alloys but, by the same token, because there are so many possible combinations, the concept offers promise to discover interesting new alloys with useful properties in their midst. Jien-Wei Yeh and co-workers 1 provided an additional intriguing rationale for investigating these alloys: they hypothesized that the presence of multiple (five or more) elements in near-equiatomic proportions would increase the configurational entropy of mixing by an amount sufficient to overcome the enthalpies of compound formation, thereby deterring the formation of potentially harmful intermetallics. This was a counter-intuitive notion because the conventional view-likely based on binary phase diagrams in which solid solutions are typically found at the ends and compounds near the centres-was that the greater the number of elements in concentrated alloys, the higher the probability that some of the elements would react to form compounds. But Yeh and colleagues reasoned that, as the number of elements in an alloy increased, the entropic contribution to the total free energy would overcome the enthalpic contribution and, thereby, stabilize solid solutions (Box 1; Fig. 1). They coined a catchy new name, high-entropy alloys (HEAs), for this Abstract | Alloying has long been used to confer desirable properties to materials. Typically , it involves the addition of relatively small amounts of secondary elements to a primary element. For the past decade and a half, however, a new alloying strategy that involves the combination of multiple principal elements in high concentrations to create new materials called high-entropy alloys has been in vogue. The multi-dimensional compositional space that can be tackled with this approach is practically limitless, and only tiny regions have been investigated so far. Nevertheless, a few high-entropy alloys have already been shown to possess exceptional properties, exceeding those of conventional alloys, and other outstanding high-entropy alloys are likely to be discovered in the future. Here, we review recent progress in understanding the salient features of high-entropy alloys. Model alloys whose behaviour has been carefully investigated are highlighted and their fundamental properties and underlying elementary mechanisms discussed. We also address the vast compositional space that remains to be explored and outline fruitful ways to identify regions within this space where high-entropy alloys with potentially interesting properties may be lurking.

- by Dierk Raabe and +1
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- Thermodynamics, Classical Thermodynamics, Phase Transformations, Microstructure

Stainless steel-zirconium alloys have been developed at Argonne National Laboratory to contain radioactive metal isotopes isolated from spent nuclear fuel. This article discusses the various phases that are formed in as-cast alloys of type 304 stainless steel and zirconium that contain up to 92 wt pct Zr. Microstructural characterization was performed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), and crystal structure information was obtained by Xray diffraction. Type 304SS-Zr alloys with 5 and 10 wt pct Zr have a three-phase microstructure-austenite, ferrite, and the Laves intermetallic, Zr(Fe,Cr,Ni)z+x, whereas alloys with 15, 20, and 30 wt pct Zr contain only two phases-ferrite and Zr(Fe,Cr,Ni)2+x. Alloys with 45 to 67 wt pct Zr contain a mixture of Zr(Fe,Cr,Ni)z+x and Zr2(Ni,Fe), whereas alloys with 83 and 92 wt pet Zr contain three phases-a-Zr, Zr2(Ni,Fe), and Zr(Fe,Cr,Ni)z+x. Fe3Zr-type and Zr3Fe-type phases were not observed in the type 304SS-Zr alloys. The changes in alloy microstructure with zirconium content have been correlated to the Fe-Zr binary phase diagram.

- by Sean McDeavitt
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- Materials Engineering, Mechanical Engineering, Materials Science, Microstructure
- by Vijayaraghavan Gonuguntla
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- Phase Diagrams, Phase equilibria

Here we argue that life emerged on Earth from a redox and pH front at c. 4.2 Ga. This front occurred where hot (c. 150 C), extremely reduced, alkaline, bisulphide-bearing, submarine seepage waters interfaced with the acid, warm (c. 90 C), iron-bearing Hadean ocean. The low pH of the ocean was imparted by the ten bars of CO 2 considered to dominate the Hadean atmosphere/hydrosphere. Disequilibrium between the two solutions was maintained by the spontaneous precipitation of a colloidal FeS membrane. Iron monosulphide bubbles comprising this membrane were inflated by the hydrothermal solution upon sulphide mounds at the seepage sites. Our hypothesis is that the FeS membrane, laced with nickel, acted as a semipermeable catalytic boundary between the two fluids, encouraging synthesis of organic anions by hydrogenation and carboxylation of hydrothermal organic primers. The ocean provided carbonate, phosphate, iron, nickel and protons; the hydrothermal solution was the source of ammonia, acetate, HS , H 2 and tungsten, as well as minor concentrations of organic sulphides and perhaps cyanide and acetaldehyde. The mean redox potential (Eh) across the membrane, with the energy to drive synthesis, would have approximated to 300 millivolts. The generation of organic anions would have led to an increase in osmotic pressure within the FeS bubbles. Thus osmotic pressure could take over from hydraulic pressure as the driving force for distension, budding and reproduction of the bubbles. Condensation of the organic molecules to polymers, particularly organic sulphides, was driven by pyrophosphate hydrolysis. Regeneration of pyrophosphate from the monophosphate in the membrane was facilitated by protons contributed from the Hadean ocean. This was the first use by a metabolizing system of protonmotive force (driven by natural pH) which also would have amounted to c. 300 millivolts. Protonmotive force is the universal energy transduction mechanism of life. Taken together with the redox potential across the membrane, the total electrochemical and chemical energy available for protometabolism amounted to a continuous supply at more than half a volt. The role of the iron sulphide membrane in keeping the two solutions separated was appropriated by the newly synthesized organic sulphide polymers. This organic takeover of the membrane material led to the miniaturization of the metabolizing system. Information systems to govern replication could have developed penecontemporaneously in this same milieu. But iron, sulphur and phosphate, inorganic components of earliest life, continued to be involved in metabolism.

- by Michael Russell
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- Geology, Metabolism, Carbon Dioxide, Phylogeny

xv PREFACIO Querido radioaficionado español:

- by Luis Pardo
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- Crystal structure, Phase Diagrams, Phase equilibria, Gibbs Free Energy

Based on the model of regular solutions and experimental data on quasi-binary sections and individual substances, the liquidus
surfaces of SiC–B4C–MedB2 quasi-ternary eutectic systems (where boride MedB2 – CrB2, VB2, NbB2, TaB2, TiB2, ZrB2, HfB2, W2B5)
are built. The paper provides the comparison of theoretical calculations with experimental data and reviews regularities of SiC–
B4C–MedB2 phase diagrams. It is found that there is a regular decrease in diboride concentration in the ternary eutectics with the
increase in its melting point. Correlations are established between the eutectic temperature and MedB2 melting point teut = f(tm
MedB2),
the eutectic temperature and MedB2 formation enthalpy teut = f(ΔHf
MedB2). The type of correlations is close to similar correlations observed
earlier in SiC–MedB2 and B4C–MedB2 boundary quasi-binary systems. The structure and parameter analysis of the reviewed
systems allows for the conclusion on the prospects of developing a wide range of engineering and functional ceramic materials and
coatings based on these systems and obtained by pressureless sintering, as well as heating and consolidation pulse methods.

- by Dmitriy Nesmelov
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- Ceramic Technology, Phase Diagrams, Superhard Materials

A term first coined by Mott back in 1968 a “pseudogap” is the depletion of the electronic density of states at the Fermi level, and pseudogaps have been observed in many systems. However, since the discovery of the high-temperature superconductors (HTSC) in 1986, the central role attributed to the pseudogap in these systems has meant that by many researchers now associate the term pseudogap exclusively with the HTSC phenomenon. Recently, the problem has got a lot of new attention with the rediscovery of two distinct energy scales (“two-gap scenario”) and charge density waves patterns in the cuprates. Despite many excellent reviews on the pseudogap phenomenon in HTSC, published from its very discovery up to now, the mechanism of the pseudogap and its relation to superconductivity are still open questions. The present review represents a contribution dealing with the pseudogap, focusing on results from angle resolved photoemission spectroscopy (ARPES) and ends up with the conclusion that the pseudogap in cuprates is a complex phenomenon which includes at least three different “intertwined” orders: spin and charge density waves and preformed pairs, which appears in different parts of the phase diagram. The density waves in cuprates are competing to superconductivity for the electronic states but, on the other hand, should drive the electronic structure to vicinity of Lifshitz transition, that could be a key similarity between the superconducting cuprates and iron-based superconductors. One may also note that since the pseudogap in cuprates has multiple origins there is no need to recoin the term suggested by Mott.

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- by suresh menon
- •
- High Pressure, Thermochemistry, Molecular Dynamics, Phase Diagrams

Recent advances in single molecule experiments have raised many challenges. These challenges can be met by a proper understanding of the inter-and intra-molecular interactions in the framework of physics followed by suitable theoretical models substantiated by extensive numerical simulations. In this review, we briefly discuss experimental, theoretical and numerical techniques used to examine the dynamics of biomolecules under the application of external mechanical force. We focus on issues which require special attention: the relationship between the mechanical stability of a protein and the secondary structure of its native conformation, the dependence of the free energy landscape on the pulling direction and secondary structure content, unfolding of a protein through a pore, protein re-folding under quenched force etc. We pay special attention to a single stranded DNA, where the force-extension curve shows a multi-step plateau for the chain made up of adenine while poly-thymine exhibits entropic response only. There are many interesting predictions related to unzipping of double stranded DNA e.g. re-entrance in the force-temperature phase diagram, existence of an ''Eye-phase'', effects of random disorder etc. based on model studies which require further investigation. We will also discuss cases where the theoretical descriptions of the models fail to explain the experimentally observed behavior and when further refinement is needed in order to describe the outcomes of experiments. Finally we suggest certain experimental protocols to observe theoretical predictions in vitro.

- by sanjay kumar
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- Spectroscopy, Single molecule, DNA, Phase Diagrams
- by Tomi Laurila and +1
- •
- Engineering, Thermodynamics, Microstructure, Kinetics

The high entropy alloy (HEA) concept has triggered a renewed interest in alloy design, even though some aspects of the underlying thermodynamic concepts are still under debate. This study addresses the shortcomings of this alloy design strategy with the aim to open up new directions of HEA research targeting specifically non-equiatomic yet massively alloyed compositions. We propose that a wide range of massive single phase solid solutions could be designed by including non-equiatomic variants. It is demonstrated by introducing a set of novel non-equiatomic multi-component CoCrFeMnNi alloys produced by metallurgical rapid alloy prototyping. Despite the reduced configurational entropy, detailed characterization of these materials reveals a strong resemblance to the well-studied equiatomic single phase HEA: The microstructure of these novel alloys exhibits a random distribution of alloying elements (confirmed by Energy-Dispersive Spectroscopy and Atom Probe Tomography) in a single face-centered-cubic phase (confirmed by X-ray Diffraction and Electron Backscatter Diffraction), which deforms through planar slip (confirmed by Electron-Channeling Contrast Imaging) and leads to excellent ductility (confirmed by uniaxial tensile tests). This approach widens the field of HEAs to non-equiatomic multi-component alloys since the concept enables to tailor the stacking fault energy and associated transformation phenomena which act as main mechanisms to design useful strain hardening behavior.

- by Dierk Raabe
- •
- Thermodynamics, Crystallography, Phase Transformations, Microstructure

The phases of ceria-zirconia nanoparticles observed in air are studied as a function of particle size and composition by X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The emergence of two tetragonal phases t 00 and t monotonically moves toward higher zirconia concentrations with decreasing particle size. A smaller particle size increases the solubility of zirconia in cubic ceria, while higher zirconia content in ceria stabilizes against coarsening. In particular, the cubic Ce 1Àx Zr x O 2Ày is persistent and is 8% in phase amount even at 90% zirconia with 33 nm crystal size. Neither the monoclinic phase m nor the tetragonal phase t 0 is observed in the present nanoparticles (o40 nm). The effectiveness of these nanoparticles as oxygen source-and-sink in catalytic support is largely due to the persistence of the cubic and the t 00 phases.

- by Anggia Vicky
- •
- Phase Diagrams

Nearly all nontrivial real-world systems are nonlinear dynamical systems. Chaos describes certain nonlinear dynamical systems that have a very sensitive dependence on initial conditions. Chaotic systems are always deterministic and may be very simple, yet they produce completely unpredictable and divergent behavior. Systems of nonlinear equations are difficult to solve analytically, and scientists have relied heavily on visual and qualitative approaches to discover and analyze the dynamics of nonlinearity. Indeed, few fields have drawn as heavily from visualization methods for their seminal innovations: from strange attractors, to bifurcation diagrams, to cobweb plots, to phase diagrams and embedding. Although the social sciences are increasingly studying these types of systems, seminal concepts remain murky or loosely adopted. This article has three aims. First, it argues for several visualization methods to critically analyze and understand the behavior of nonlinear dynamical systems. Second, it uses these visualizations to introduce the foundations of nonlinear dynamics, chaos, fractals, self-similarity and the limits of prediction. Finally, it presents Pynamical, an open-source Python package to easily visualize and explore nonlinear dynamical systems' behavior.

- by Geoff Boeing
- •
- Control Systems Engineering, Mathematics, Fractal Geometry, Computer Science

Experimentally the theoretical substantiation of the proposed method has been confirmed . The new technological proposals are applicable both for the processing of carnallite, which crystallizes during the evaporation of brine, and for... more

- by Lazar Morgenstern
- •
- Phase Diagrams

This paper presents a new encryption scheme called Compact Coding that encodes information in time, phase, and intensity domains, simultaneously. While these approaches have previously been used one at a time, the proposed scheme brings to bear for the first time their strengths simultaneously leading to an increase in the secure information transfer rate. The proposed scheme is applicable to both optical fibers and free space optics, and can be considered as an alternative to polarization coding. This paper applies the proposed compact coding scheme to multi-photon tolerant quantum protocols in order to produce quantum-level security during information transfer. We present the structure of the proposed coding scheme in a multi-photon environment and address its operation.

- by Vijayaraghavan Gonuguntla
- •
- Phase Diagrams, Phase equilibria, Lead

The objective of our investigation was to design a thermodynamically stable and dilutable nanoemulsion formulation of Ramipril, with minimum surfactant concentration that could improve its solubility, stability and oral bioavailability. Formulations were taken from the o/w nanoemulsion region of phase diagrams, which were subjected to thermodynamic stability and dispersibility tests. The composition of optimized formulation was Sefsol 218 (20% w/w), Tween 80 (18% w/w), Carbitol (18% w/w) and standard buffer solution pH 5 (44% w/w) as oil, surfactant, cosurfactant and aqueous phase, respectively, containing 5 mg of ramipril showing drug release (95%), droplet size (80.9 nm), polydispersity (0.271), viscosity (10.68 cP), and infinite dilution capability. In vitro drug release of the nanoemulsion formulations was highly significant (p < 0.01) as compared to marketed capsule formulation and drug suspension. The relative bioavailability of ramipril nanoemulsion to that of conventional capsule form was found to be 229.62% whereas to that of drug suspension was 539.49%. The present study revealed that ramipril nanoemulsion could be used as a liquid formulation for pediatric and geriatric patients and can be formulated as self-nanoemulsifying drug delivery system (SNEDDS) as a unit dosage form.

- by Roop Khar and +1
- •
- Thermodynamics, Evaluation, Pharmaceutical Technology, Pharmacokinetics

A thermodynamic assessment of the Bi-Sn-Zn ternary system was carried out using the CALPHAD approach along with thermodynamic descriptions from new assessments of the Bi-Sn and Bi-Zn systems. Selected experimental data from the literature and our own work were also used. New sets of optimized thermodynamic parameters were obtained that lead to a very good fit between the calculated and experimental data. The Bi-Sn-Zn system is one of the candidates for lead-free solder materials.

- by Luís Malheiros
- •
- Materials Engineering, Thermodynamics, Phase Diagrams, Phase equilibria

Grains of native gold and tellurium were found in siliceous hydrothermally altered rocks in the high-temperature Ž . Ž . 170-5408C fumarolic field of the La Fossa volcano Island of Vulcano . In addition to Au and Te, Pb-Bi sulfides Ž . cannizzarite and Tl-bromide chloride were found as sublimates in the hottest fumarolic vents of the crater rim. The chemical composition of altered rocks associated with sublimate deposition indicate the presence of a significant Ž . Ž . concentration of Te up to 75 ppm , while gold concentrations are very low -9 ppb . Pb, Bi and Tl are strongly enriched in the hottest and less oxidized fumarolic vents, reaching concentrations of 2186, 146 and 282 ppm, respectively. These Ž . Ž . elements are transported generally as chloride complexes to the surface by volcanic gases, and several of these Bi, Te, Tl are originated from magma degassing. The silicic alteration is produced by the flow of fluids with pH -2. High acidity results from introduction of magmatic gases such as SO , HCl and HF released by the shallow magmatic reservoir of La 2 Fossa volcano. The silicic alteration found at Vulcano may represent an early stage of the ' vuggy silica' facies which characterizes the high-sulfidation epithermal ore deposits, confirming the analogies existing between this type of ore deposit and magmatic-hydrothermal systems associated with island-arc volcanoes. q

- by Alessandro Sbrana
- •
- Geology, Geochemistry, Geophysics, Scanning Electron Microscopy

The solubility of alcohols in a polystyrene matrix during the diffusion process was measured by a gravimetric technique. It is shown that the amount of solvent swelling the polymer reaches an equilibrium saturation, which is dependent on the system and temperature, but independent on the sample preparation. Phase diagrams, similar to those measured by TM-DSC and cloud points of known mixtures, can therefore be constructed. These measurements provide accurate and reliable data for a theoretical treatment. The results have been interpreted by Flory-Huggins theory. Interaction parameters as well as their entropic and enthalpic components have been calculated. An analysis based on Hansen solubility parameters has also been performed.

- by Gabriel Bernardo
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- Materials Engineering, Chemical Engineering, Sample Preparation, Phase Diagrams

A review is given on the theory of vortex-glass phases in impure type-II superconductors in an external field. We begin with a brief discussion of the effects of thermal fluctuations on the spontaneously broken U (1) and translation symmetries, on the global phase diagram and on the critical behaviour. Introducing disorder we restrict ourselves to the experimentally most relevant case of weak uncorrelated randomness which is known to destroy the long-ranged translational order of the Abrikosov lattice in three dimensions. Elucidating possible residual glassy ordered phases, we distinguish between positional and phase-coherent vortex glasses. The study of the behaviour of isolated vortex lines and their generalization -directed elastic manifolds -in a random potential introduces further important concepts for the characterization of glasses. The discussion of elastic vortex glasses, i.e., topologically ordered dislocation-free positional glasses in two and three dimensions occupy the main part of our review. In particular, in three dimensions there exists an elastic vortex-glass phase which still shows quasi-long-range translational order: the 'Bragg glass'. It is shown that this phase is stable with respect to the formation of dislocations for intermediate fields. Preliminary results suggest that the Bragg-glass phase may not show phase-coherent vortex-glass order. The latter is expected to occur in systems with weak disorder only in higher dimensions (or for strong disorder, as the example of unscreened gauge glasses shows). We further demonstrate that the linear resistivity vanishes in the vortex-glass phase. The vortex-glass transition is studied in detail for a superconducting film in a parallel field. Finally, we review some recent developments concerning driven vortex-line lattices moving in a random environment.

- by Thomas Nattermann
- •
- Physics, Condensed Matter Physics, Quantum Physics, Critical phenomena

The phases formed in the ternary system (Na1/2Bi1/2)TiO3–Bi4Ti3O12–BaTiO3 (NBT–BTO–BT) were studied at 1150°C in air. A very accurate picture of the ternary phase diagram was obtained examining almost 90 different compositions, exploiting low-angle XRD analyses to study the layer compounds. New compounds with five perovskite blocks (m=5) were discovered deep in the phase diagram. No compounds with m>5 were found. It was also established that pure perovskite compounds can be obtained only at compositions very close to the NBT–BT line. The relationships between the phases is discussed and it is hypothesized that the number of perovskite blocks in the system is determined by charged sites being created by the progressive substitution of Bi3+ in the A site of the perovskite blocks of BTO with the A cations of the perovskite end-member.

The 3D phase diagram of iron pnictides where the critical temperature depends on charge density and microstrain in the active FeAs layers is proposed. The iron pnictides superconductors are shown to be a practical realization of a heterostructure at the atomic limit made of a superlattice of FeAs layers intercalated by spacers layers. We have focussed our interest on the A 1-x B x Fe 2 As 2 (122) families and we show that FeAs layers have a tensile microstrain due to the misfit strain between the active layers and the spacers. We have identified the critical range of doping and microstrain where the critical temperature gets amplified to its maximum value.

- by A. Bianconi and +1
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- Condensed Matter Physics, Superconductivity, Doping, HIGH TEMPERATURE SUPERCONDUCTIVITY

Thermal behavior, structural properties, and phase equilibria of the (100x)TeO2-xNa2O system were studied in the
5 ≤ x ≤ 50 mol% composition range. Investigation of glass formation behavior in the binary system was realized, and the
glass formation range was determined as 7.5 ≤ x ≤ 40 mol%. Differential thermal analysis (DTA) and Fourier transform
infrared (FTIR) spectroscopy techniques were used for thermal and structural characterization of the glasses. Influence of
Na2O content on glass transition temperature (Tg), glass stability (ΔT), density (q), molar volume (VM), oxygen molar volume
(VO), and oxygen packing density (OPD) values of sodium tellurite glasses was evaluated considering the structural transformations
in the glass network. For the phase equilibria studies, DTA, X-ray diffraction (XRD), and scanning electron
microscopy/energy dispersive X-ray (SEM/EDS) techniques were utilized to characterize the heat-treated samples. According
to the phase equilibria studies, three eutectic regions were detected in the 0 < x < 50 mol% composition range of the
(100x)TeO2-xNa2O system. A new invariant endothermic reaction was detected for the compositions between 40 ≤ x ≤ 45
mol%. Na2O.8TeO2 (11.11 mol% Na2O) compound that was claimed to exist in the binary system in the literature was
found to be the metastable d-TeO2 phase.

- by Miray Çelikbilek and +1
- •
- Phase Diagrams, Glasses, Tellurite Glasses, OXIDE GLASSES

In this work, two low-valued natural raw materials were used, namely a low plasticity and high iron content clay and a powdered rock waste generated during crushing of igneous rocks to produce construction aggregates. After characterization (chemical, mineralogical, thermal and granulometric), mixtures containing up to 75 wt.% of rock powder were prepared and extruded closely following industrial practice, and fired for 60 min from 900 to 1100 °C. Property development was evaluated on as-extruded,
dried and fired pieces. The results obtained were interpreted based on chemical compositions, the estimates from the Al2O3–SiO2–CaO phase diagram and presumed reaction kinetics. Such interpretation showed that physical characteristics dominate not only during shaping and drying, but also during low temperature firing (slow reaction kinetics), when rock additions act as inert material; at high firing
temperatures, however, the rock promotes liquid phase development after first melting (fluxing effect) and thermodynamics prevail. The dominant fluxing effect results in improved fired properties, which
were shown to depend almost linearly on the liquid phase content, predicted by the phase diagram and determined by the chemical composition. These results enabled the identification of behavioural composition ranges to best exploit the materials’ industrial use potential and demonstrate that current paradigms in raw material evaluation and processing in traditional ceramics industries need a re-assessment.

- by Sergio Echeverrigaray and +2
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- Clay Minerals, Phase Diagrams, Solid Wastes, Igneous Rocks

Thermodynamic description of the ternary Cu-Mg-Sn system at its Cu-Mg side is presented. The thermodynamic parameters of the binary sub-systems, Cu-Mg, Cu-Sn and Mg-Sn, are taken from the earlier SGTE-based assessments (modifying the Mg-Sn description slightly) and those of the Cu-Mg-Si system are optimized in this study using the experimental thermodynamic and phase equilibrium data. The solution phases of the systems are described with the substitutional solution model and the intermetallic Cu 2 Mg compound (Laves C15), treated as simple semi-stoichiometric phases of the (A,B) p C q type, is described with the twosublattice model. The present ternary description is valid for tin contents up to 45 wt% (x Sn  0.30).

- by Jyrki Miettinen
- •
- Phase Diagrams

Three isopleths at the Mg-rich corner of Mg-Mn-Ce ternary system were investigated via thermal analysis, SEM/EPMA and XRD. A ternary eutectic reaction was observed at ~ 1wt% Mn and 23wt% Ce and 592 o C. A solid-solution type ternary intermetallic compound, (Mg,Mn) 12 Ce, was observed with 0.5 at% solid solubility of Mn in the tetragonal Mg 12 Ce. With the aid of thermodynamic modeling and experiments, a revised phase diagram for the binary Mg-Ce system and the isopleths of 0.6, 1.8 and 2.5wt% Mn were proposed up to 25wt% Ce.

The colloidal structures of beta carboxylic acid topical vesicle formulations were determined and the changes during evaporation after applications were estimated from phase diagrams. The results showed significant difference during evaporation between salicylic acid on one hand and three water soluble acids; malic, tartaric, and citric acid, on the other. The water soluble acids showed an increase in the acid concentration in the aqueous solution to levels that must be considered harmful, while salicylic acid showed no increase in concentration in the individual phases even after 99% evaporation of water. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95: 1834–1840, 2006

- by abeer al bawab
- •
- Women, Plate Tectonics, Phase Diagrams, Beauty