Dimensional Phase Diagram Research Articles

Novel Alloy Design Concepts Enabling Enhanced Mechanical Properties of High Entropy Alloys

The emergence of High Entropy Alloys (HEAs) in the world of materials has shifted the alloy design strategy based on a single principal element to the multi-principal elements where compositional space can cover almost the entire span of the higher dimensional phase diagrams. This approach can provide advanced materials with unique properties, including high strength with sufficient ductility and fracture toughness and excellent corrosion and wear resistance for a wide range of temperatures due to the concentrated alloying that cannot be obtained by traditional microalloying based on a single principal element. In addition, the alloy design approach provides new alloy systems in astronomical numbers with variety of microstructural attributes that can yield different properties, and hence conventional trial and error experimental methods for alloy development are redundant. With the help of high throughput experiments along with efficient computational tools, and artificial intelligence, mechanisms based mechanistic development of the multi-principal element alloys with tailored solid solution strengthening, stacking fault energy and microstructure is possible. The current review discusses the various design strategies based on multi-principal elements alloys in semblance with the desired mechanical properties dictated by the micro mechanisms associated with them to overcome the bottlenecks presented by the conventional approaches with possible breakthrough applications. The article will shed light on the current status as well as the future prospects of using these approaches to design novel HEAs.

Suppression of superfluid phase stiffness in Bi[formula omitted]Sr[formula omitted]Ca[formula omitted]Ce[formula omitted]Cu[formula omitted]O[formula omitted

Nonlinearity of IV characteristics below the transition temperature Tc gets strongly affected by the coupling channels between the superconducting planes in highly anisotropic superconductors. Drastic reductions in nonlinear exponent and superfluid phase stiffness (SPS) are associated with the electron doping in the coupling channel in Bi2Sr2Ca1−xCexCu2O8+δ (Bi-2212) superconductors. Impact of the current sweeping rate (CSR) on the SPS has been studied. A peak in the variation of SPS as a function of temperature (T) is observed which may be related to the absence of the zero resistive state in superconductors. The rate of the variation of the nonlinear voltage with CSR is found to be highly sensitive to both T and current. A three dimensional phase diagram on the basis of the variation is proposed. Maxima loops in the phase diagram are found to be very sensitive to the electron doping induced suppression of SPS.

Resonant multi-gap superconductivity at room temperature near a Lifshitz topological transition in sulfur hydrides

The maximum critical temperature for superconductivity in pressurized hydrides appears at the top of superconducting domes in Tc vs pressure curves at a particular pressure, which is not predicted by standard superconductivity theories. The high-order anisotropic Van Hove singularity near the Fermi level observed in band-structure calculations of pressurized sulfur hydride, typical of a supermetal, has been associated with the array of metallic hydrogen wire modules forming a nanoscale heterostructure at an atomic limit called the superstripe phase. Here, we propose that pressurized sulfur hydrides behave as a heterostructure made of a nanoscale superlattice of interacting quantum wires with a multicomponent electronic structure. We present first-principles quantum calculation of a universal superconducting dome where Tc amplification in multi-gap superconductivity is driven by the Fano–Feshbach resonance due to a configuration interaction between open and closed pairing channels, i.e., between multiple gaps in the BCS regime, resonating with a single gap in the BCS–Bose–Einstein condensation crossover regime. In the proposed three dimensional phase diagram, the critical temperature shows a superconducting dome where Tc is a function of two variables: (i) the Lifshitz parameter (η) measuring the separation of the chemical potential from the Lifshitz transition normalized by the inter-wire coupling and (ii) the effective electron–phonon coupling (g) in the appearing new Fermi surface including phonon softening. The results will be of help for material design of room-temperature superconductors at ambient pressure.

Electric field-triggered Cassie-Baxter-Wenzel wetting transition on textured surface

Understanding the critical condition and mechanism of the droplet wetting transition between Cassie-Baxter state and Wenzel state triggered by an external electric field is of considerable importance because of its numerous applications in industry and engineering. However, such a wetting transition on a patterned surface is still not fully understood, e.g., the effects of electro-wetting number, geometry of the patterned surfaces, and droplet volume on the transition have not been systematically investigated. In this paper, we propose a theoretical model for the Cassie-Baxter- Wenzel wetting transition triggered by applying an external voltage on a droplet placed on a mircopillared surface or a porous substrate. It is found that the transition is realized by lowering the energy barrier created by the intermediate composite state considerably, which enables the droplet to cross the energy barrier and complete the transition process. Our calculations also indicate that for fixed droplet volume, the critical electrowetting number (voltage) will increase (decrease) along with the surface roughness for a micro-pillar patterned (porous) surface, and if the surface roughness is fixed, a small droplet tends to ease the critical electrowetting condition for the transition. Besides, three dimensional phase diagrams in terms of electrowetting number, surface roughness, and droplet volume are constructed to illustrate the Cassie-Baxter-Wenzel wetting transition. Our theoretical model can be used to explain the previous experimental results about the Cassie-Baxter-Wenzel wetting transition reported in the literature.

The large N phase diagram of mathcal{N} = 2 SU(N) Chern-Simons theory with one fundamental chiral multiplet

We study the theory of a single fundamental fermion and boson coupled to Chern-Simons theory at leading order in the large N limit. Utilizing recent progress in understanding the Higgsed phase in Chern-Simons-Matter theories, we compute the quantum effective potential that is exact to all orders in the ’t Hooft coupling for the lightest scalar operator of this theory at finite temperature. Specializing to the zero temperature limit we use this potential to determine the phase diagram of the large N mathcal{N} = 2 supersymmetric theory with this field content. This intricate two dimensional phase diagram has four topological phases that are separated by lines of first and second order phase transitions and includes special conformal points at which the infrared dynamics is governed by Chern-Simons theory coupled respectively to free bosons, Gross-Neveu fermions, and to a theory of Wilson-Fisher bosons plus free fermions. We also describe the vacuum structure of the most general mathcal{N} = 1 supersymmetric theory with one fundamental boson and one fundamental fermion coupled to an SU(N ) Chern-Simons gauge field, at arbitrary values of the ’t Hooft coupling.

Three dimensional phase diagram of superfluidity controlled voltage nonlinearity in superconductors

We have studied current-voltage (IV) characteristics of (i) underdoped and (ii) electron doped high temperature superconductors (HTS) around the superconducting phase transition. Over a wide range of temperature below the critical temperature a nonlinear current-voltage behavior has been observed both in the undoped and electron doped sample. Following the dependence of the pinning potential on the current sweeping rates (CSR) several moderate values of CSR have been used for the measurement of IV at a constant temperature T. An exponent related to the superfluid density varies with CSR mostly at the range of the lower temperature. Variation of the nonlinear voltage with respect to the sweeping rate is found to be a function of both the applied current and temperature. On the basis of the variation we propose that the three dimensional phase diagram identifies the potential regions of nonlinearity. A collinear arrangement of maxima loops by the driving current is possible in a narrrow range of T.

Original Higgs inflation and phantom crossing

It is a standard practice to ignore the initial kinetic term in an inflationary analysis. Here, we overrule this practice to analyze pre-inflationary, inflationary and post-inflationary dynamics of the original Higgs-inflation model from a wider view. To this end, our calculations are not restricted to slow-roll regime. Perhaps, the most interesting result that we have found is the behavior of the field trajectories which begin their way from a phantom origin, before reaching a quasi de Sitter partial attractor. Both analytical and numerical calculations ultimately confirm that for the original Higgs inflation scenario the mentioned de Sitter path ends in an oscillatory phase which is the required condition for having (p)reheating. This achievement discriminates the current research from the previous studies about the late time phantom crossing scenarios which often end in a de Sitter future world. This confirms that a phantom energy epoch may deliver much more than has been thought earlier. In our calculations, we have employed the dynamical system method and explain the results both analytically and through the plotted numerical calculations. Beside the present results, the dynamical system approach can be used in other studies which deal with non-minimal gravity models. Reducing the number of dynamical variables to two enables us to enjoy the two dimensional phase diagram which is very elusive.

Search for the critical point by the NA61/SHINE experiment

NA61/SHINE is a fixed target experiment operating at CERN SPS. Its main goals are to search for the critical point of strongly interacting matter and to study the onset of deconfinement. For these goals a scan of the two dimensional phase diagram (T−μB) is being performed at the SPS by measurements of hadron production in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy.In this paper the status of the search for the critical point of strongly interacting matter by the NA61/SHINE Collaboration is presented including recent results on proton intermittency, strongly intensive fluctuation observables of multiplicity and transverse momentum fluctuations. These measurements are expected to be sensitive to the correlation length and, therefore, have the ability to reveal the existence of the critical point via possible non-monotonic behavior. The new NA61/SHINE results are compared to the model predictions.

Looking for the Phase Transition—Recent NA61/SHINE Results

The fixed-target NA61/SHINE experiment at the CERN Super Proton Synchrotron (SPS) seeks to find the critical point (CR) of strongly interacting matter as well as the properties of the onset of deconfinement. The experiment provides a scan of measurements of particle spectra and fluctuations in proton–proton, proton–nucleus, and nucleus–nucleus interactions as functions of collision energy and system size, corresponding to a two-dimensional phase diagram (T- μ B ). New NA61/SHINE results are shown here, including transverse momentum and multiplicity fluctuations in Ar+Sc collisions as compared to NA61 p+p and Be+Be data, as well earlier NA49 A+A results. Recently, a preliminary effect of change in the system size dependence, labelled as the “percolation threshold” or the “onset of fireball”, was observed in NA61/SHINE data. This effect is closely related to the vicinity of the hadronic phase space transition region and will be discussed in the text.

News from the NA61/SHINE experiment

NA61/SHINE is a fixed target experiment operating at the CERN SPS. Its main goals are to search for the critical point of strongly interacting matter and to study the onset of deconfinement. For these goals a scan of the two dimensional phase diagram (T-μB) is being performed at the SPS by measurements of hadron production in proton-proton, proton-nucleus and nucleusnucleus interactions as a function of collision energy. In this paper the status of the NA61/SHINE strong interaction physics programme is presented including recent results on proton intermittency, strongly intensive fluctuation observables of multiplicity and transverse momentum fluctuations. These measurements are expected to be sensitive to the correlation length in the produced matter and, therefore, have the ability to reveal the existence of the critical point via possible non-monotonic behavior. The NA61/SHINE results are compared to the model predictions.

Rapid production of monodisperse cross-linked red blood corpuscle-like particles via scalable one-pot dispersion polymerization

Cross-linked polystyrene (PS) particles having red blood corpuscle (RBC)-like shape were synthesized by one-pot dispersion polymerization of styrene with ethanol/water mixture and ethylene glycol dimethacrylate (EGDMA) as the reaction medium and cross-linker, respectively. Monitoring of the reaction showed that RBC-like shape forms due to asymmetric shrinkage of a cross-linked network during the phase separation. In addition, three dimensional phase diagram was generated based on the yielded data that showed that the formation of such unique shape extremely depends on the polarity of the medium and injection time of the cross-linker. In situ synthesis of RBC-like particles, as promising biomaterials in targeted drug delivery and a model for the understanding of the cell behavior, via such fast and high solid content approach makes it to be conducive to subsequent scale up, i.e. potential commercial adoption.

News from Strong Interactions Program of the NA61/SHINE Experiment

The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. This is performed by a two dimensional phase diagram ($T-\mu_B$) scan of measurements of particle spectra and fluctuations in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy and system size. In this contribution new NA61/SHINE results on negative pion production, as well as transverse momentum and multiplicity fluctuations in Ar+Sc collisions are presented. Moreover, the latest results on higher order moments of net-charge multiplicity distribution in p+p collisions are also discussed. The Ar+Sc results are compared to NA61 p+p and Be+Be data, as well as to NA49 $A+A$ results.

Recent results from the NA61/SHINE strong interaction physics programme

The main physics goals of the NA61/SHINE programme on strong interactions are the study of the properties of the onset of deconfinement and the search for signatures of the critical point of strongly interacting matter. For this purpose a scan of the two dimensional phase diagram ($T$-$\mu_{B}$) is being performed at the SPS by measurements of hadron production in nucleus-nucleus collisions as a function of collision energy and system size. This contribution presents intriguing results on the energy dependence of hadron spectra and yields in inelastic p+p and centrality selected Be+Be and Ar+Sc collisions. In particular, the energy dependence of the signals of deconfinement, the "horn", "step" and "kink", and new results on fluctuations and correlations are shown and compared with the corresponding data of other experiments and model predictions.

Transverse Momentum and Multiplicity Fluctuations in Ar+Sc Collisions at the CERN SPS from NA61/SHINE

The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. For these goals a scan of the two dimensional phase diagram ($T$-$\mu_{B}$) is being performed at the SPS by measurements of hadron production in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy and system size. In this contribution preliminary results on transverse momentum and multiplicity fluctuations expressed in terms of strongly intensive quantities from the Ar+Sc energy scan will be presented. These fluctuations are expected to be sensitive to the existence of a critical point. The results are compared with results from the p+p and Be+Be energy scan as well as with NA49 measurements.

Recent results from NA61/SHINE

The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. For these goals a scan of the two dimensional phase diagram (T-$\mu_B$) is being performed at the SPS by measurements of hadron production in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy and system size. In this contribution intriguing results on the energy dependence of hadron spectra and yields in inelastic p+p and centrality selected Be+Be collisions will be presented. In particular, the energy dependence of the signals of deconfinement, the 'horn', 'step' and 'kink', in p+p interactions will be presented and compared with the corresponding results from central Pb+Pb collisions from NA49.

Phases of d-orbital bosons in optical lattices

We explore the properties of bosonic atoms loaded into the d bands of an isotropic square optical lattice. Following the recent experimental success reported in Zhai et al (2013 Phys. Rev. A 87 063638), in which populating d bands with a 99 fidelity was demonstrated, we present a theoretical study of the possible phases that can appear in this system. Using the Gutzwiller ansatz for the three d band orbitals we map the boundaries of the Mott insulating phases. For not too large occupation, two of the orbitals are predominantly occupied, while the third, of a slightly higher energy, remains almost unpopulated. In this regime, in the superfluid phase we find the formation of a vortex lattice, where the vortices come in vortex/anti-vortex pairs with two pairs locked to every site. Due to the orientation of the vortices time-reversal symmetry is spontaneously broken. This state also breaks a discrete -symmetry. We further derive an effective spin-1/2 model that describe the relevant physics of the lowest Mott-phase with unit filling. We argue that the corresponding two dimensional phase diagram should be rich with several different phases. We also explain how to generate anti-symmetric spin interactions that can give rise to novel effects like spin canting.

Polymer-mediated nanorod self-assembly predicted by dissipative particle dynamics simulations.

Self-assembly of nanoparticles in polymer matrices is an interesting and growing subject in the field of nanoscience and technology. We report herein on modelling studies of the self-assembly and phase behavior of nanorods in a homopolymer matrix, with the specific goal of evaluating the role of deterministic entropic and enthalpic factors that control the aggregation/dispersion in such systems. Grafting polymer brushes from the nanorods is one approach to control/impact their self-assembly capabilities within a polymer matrix. From an energetic point of view, miscible interactions between the brush and the matrix are required for achieving a better dispersibility; however, grafting density and brush length are the two important parameters in dictating the morphology. Unlike in previous computational studies, the present Dissipative Particle Dynamics (DPD) simulation framework is able to both predict dispersion or aggregation of nanorods and determine the self-assembled structure, allowing for the determination of a phase diagram, which takes all of these factors into account. Three types of morphologies are predicted: dispersion, aggregation and partial aggregation. Moreover, favorable enthalpic interactions between the brush and the matrix are found to be essential for expanding the window for achieving a well-dispersed morphology. A three-dimensional phase diagram is mapped on which all the afore-mentioned parameters are taken into account. Additionally, in the case of immiscibility between brushes and the matrix, simulations predict the formation of some new and tunable structures.

A New Phase Diagram for Combined-Flow Bedforms

Abstract Combined-flows, which involve a combination of unidirectional and wave-induced oscillatory flow, are omnipresent in coastal and lacustrine environments. Despite the extensive progress made in understanding the bedforms generated by such flows in past studies, there still remains a wide range of unexplored flow conditions where the bedform geometry, and hence consequent sedimentary structures, have not been explored, especially for strong unidirectional flows (greater than 0.30 m s−1) and intermediate oscillation periods (between 2 and 8 seconds). To address this gap in our knowledge, the stability of bedforms in a 0.25 mm diameter sand bed was studied under pure unidirectional, pure-oscillatory, and combined-flow conditions with oscillation periods of 4, 5, and 6 s. The maximum orbital velocity (Uo) was varied from 0.00 to 1.00 m s−1 while the unidirectional component (Uu) was varied from 0 to 0.50 m s−1. The experimental data collected under unidirectional flows stronger than 0.30 m s−1 allows expansion of current understanding of the bed configurations for current-dominated combined-flows, where the phase boundary between combined-flow bedforms and current ripples was uncertain. Under these flow conditions, ten distinctive bedform states can be recognized: no motion (NM), 2D symmetric ripples (2D SR), 3D symmetric ripples (3D SR), 3D symmetric dunes (3D SR), 3D asymmetric ripples (3D AR), 3D quasi-asymmetric ripples (3D QAR), 3D asymmetric dunes (3D AD), 3D current ripples (3D CR), 3D current dunes (3D CD), and upper-stage plane bed (USPB). Each of these bedform stages is described, quantified, and characterized in dimensional phase diagrams. A complete re-evaluation of the nomenclature for combined-flow bedforms is proposed, which includes their planform and cross-sectional geometry, in order to better represent the bed morphologies. This new nomenclature also unifies past research on bedforms in both unidirectional and oscillatory flows and thus presents a new synopsis of bedforms developed under such flows. One of the main changes proposed that allows integration with the nomenclature used in unidirectional flows is the reclassification of large ripples as dunes. Furthermore, the introduction of the planform and cross-sectional geometries as properties by which to classify bedforms leads to the definition of a stable phase space for two-dimensional symmetrical ripples and three-dimensional quasi-asymmetrical ripples. These new data and analysis allow proposition of a new unified phase diagram for combined-flows.

High Field determination of superconducting fluctuations in high-Tc cuprates

Large pulsed magnetic fields up to 60 Tesla are used to suppress the contribution of superconducting fluctuations (SCF) to the ab-plane conductivity above Tc in a series of YBa2Cu3O6+x single crystals. The fluctuation conductivity is found to vanish nearly exponentially with temperature, allowing us to determine precisely the field H'c(T) and the temperature T'c above which the SCFs are fully suppressed. T'c is always found much smaller than the pseudogap temperature A careful investigation near optimal doping shows that T'c is higher than the pseudogap T*, which indicates that pseudogap cannot be assigned to preformed pairs. For nearly optimally doped samples, the fluctuation conductivity can be accounted for by gaussian fluctuations following the Ginzburg-Landau scheme. A phase fluctuation contribution might be invoked for the most underdoped samples in a T range which increases when controlled disorder is introduced by electron irradiation. Quantitative analysis of the fluctuating magnetoconductance allows us to determine the critical field Hc2(0) which is found to be quite similar to H'c(0) and to increase with hole doping. Studies of the incidence of disorder on both T'c and T* enable us to propose a three dimensional phase diagram including a disorder axis, which allows to explain most observations done in other cuprate families.

Force induced phase transition of honeycomb-structured ferroelectric thin film

The external force induced phase transition properties of a honeycomb-structured ferroelectric thin film described by a spin-12 transverse Ising model were investigated by use of the effective field theory with correlations (EFT). The forces were introduced into the systems by performing three different interaction functions. The results demonstrate that characteristic phase diagrams and phase regions are strongly dependent on the added external force. In particular, the whole process of phase transition from ferroelectric to paraelectric and then back to ferroelectric was revealed in a 3-D (dimensional) phase diagram vividly for the first time suggesting that forces can be used to control pseudo-spin polarizations in the hexagonal lattice sensitively.