Complete Phase Research Articles

On the Problem of the Distillation Separation of Secondary Alloys of Magnesium with Zinc and Magnesium with Cadmium

An alternative to the existing method of processing secondary magnesium raw materials by remelting in a salt furnace can be distillation separation into volatile metals (Mg, Zn and Cd), low-volatile metals (Al, Mn and Zr) and rare earth elements. The separation of metals may be tracked based on phase diagrams where the field boundaries of the vapor–liquid equilibrium are plotted. Due to the fact that Mg, Zn and Cd have comparable saturated vapor pressures, the possibility of the distillation separation of Mg–Zn and Mg–Cd systems using full state diagrams including the melt–vapor phase transition boundaries were determined in this work. The boundaries of these systems were calculated based on the partial values of saturated vapor, determined by the boiling point method, and presented in the form of temperature–concentration dependencies with the indicated boundaries. The field boundaries were calculated (L + V) at atmospheric pressure (101.33 kPa) and in vacuum (1.33 kPa and 0.7 kPa,) supposing the implementation of the process. The possibility of the separate extraction of zinc and cadmium from magnesium was considered using complete phase diagrams including the boundaries of the melt–steam phase transition. When considering the boundaries of the vapor–liquid equilibrium in the binary systems Mg–Zn and Mg–Cd, it was established that it is impossible to separate metals in one “evaporation–condensation” cycle in a vacuum of 1.33 and 0.7 kPa. The problem is caused by the small size of the fields (L + V) at the temperature, which suggests processes of the re-evaporation of the condensate from the previous distillation stage. The separation of zinc and cadmium from liquid alloys with magnesium under equilibrium conditions requires several repetitions of the condensate distillation process. In non-equilibrium conditions, the real processes will require a larger number of conversions. This implies the expediency of the joint evaporation of magnesium with zinc and cadmium and the use of condensate for additional charging to liquid magnesium, and the remainder of the distillation, where volatile metals such as Al, Mn, Zr and rare earth elements will be concentrated, should be directed to the preparation of ligatures for special magnesium-based alloys.

Decay and Fission of Magnetic Quivers.

In exploring supersymmetric theories with eight supercharges, the Higgs branches present an intriguing window into strong coupling dynamics. Magnetic quivers serve as crucial tools for understanding these branches. Here, we introduce the decay and fission algorithm for unitary magnetic quivers. It efficiently derives complete phase diagrams (Hasse diagrams) through convex linear algebra. It allows magnetic quivers to undergo decay or fission, reflecting Higgs branch RG flows in the theory. Importantly, the algorithm generates magnetic quivers for the RG fixed points and simplifies the understanding of transverse slice geometry with no need for a list of minimal transitions. In contrast, the algorithm hints to the existence of a new minimal transition, whose geometry and physics need to be explored.

A simple model of the soil freezing characteristic curve for saline soils with two freezing stages

Soil freezing characteristic curve (SFCC) describes the relationship between unfrozen water and subzero temperature, which is of significance for the simulation of heat, water, salt migration in cold regions. There are two phase transition stages in some saline soils, which is often explained by the phase equilibrium of bulk solution. However, the second phase transition and chemical characteristic of solute are ignored in the current coupling numerical models for freezing-thawing soils. The newest SFCC methods considering abovementioned two items are not applicable to numerical models due to complex calculation or irregularly changeable parameters. To solve those problems, a simple model was proposed in this paper. Firstly, the complete phase diagram of pore solution at icing stage was speculated from published experimental SFCCs of saline soils. Then, the temperatures of saline soils at freezing and eutectic points were quantitative expressed with phase diagram of bulk solution and SFCC of nonsaline soil, and the criteria determining whether single icing stage or icing-eutectic stage occurs in saline soils was proposed. A synthetic index was used to describe the effects of soil matrix and initial solute concentration on the exponent. Only three constant parameters were introduced to reflect the soil matrix effect on phase transition points of pore solution and the influence of chemical characteristic of solute on pore water freezing process. Finally, the model was validated by the experimental data of saline soils and showed good results and ease of use compared to a widely used theorical model for saline soil with single freezing stage and other two models both considering two phase transitions. The work provides a deeper view of freezing process in saline soils and promote the improvement of numerical simulation effect for heat, water and salt migration in seasonal freezing-thawing areas.

Independent Phase Control in Gap‐Tuned Metasurfaces for Dual‐Function Switching

AbstractSeeking new ways to actively control the phase using metasurfaces has gained significant attention in recent years, which is the key to achieve controllable wavefronts under external stimuli. Among various active phase control mechanisms, a mechanical method based on gap tuning, termed as gap‐tuned metasurface here, has shown promise in continuous phase adjustment. However, previous studies face limitations in independent and complete phase control at different gap distances, which is crucial in dual‐function switching applications. In this study, a novel type of gap‐tuned metasurfaces are proposed, which can overcome the above limitations through simultaneously manipulating the Pancharatnam–Berry phase and gap‐induced dynamic phase under circularly polarized incidences. Two exemplary gap‐tuned metasurfaces capable of orbital angular momentum (OAM) switching and focusing‐polarity switching are experimentally demonstrated. Furthermore, the special dynamic phase design also exhibits phase conjugate property similar to the Pancharatnam–Berry phase, making circular polarization handedness an alternative route for dual‐function switching. This method provides a straightforward and effective means for the development of active wavefront control devices.

Accelerating zero emission truck adoption in urban applications: Beijing analysis and recommendations

With the complete phase out of national new energy vehicle purchase subsidies, Chinese cities need to explore more policy instruments to simulate the adoption new energy trucks (NETs). The study takes Beijing as an example and aims to address: how Chinese cities can craft policies to further promote NETs, considering different NET models operating in divergent duty cycles by different sizes of operators would have different obstacles with vehicle technologies and costs, to achieve its carbon and air pollutant emission reduction goal, while maintaining the livelihood of small and medium carrier in the freight industry. Based on NET technical performance analysis and surveys WRI conducted on carriers in Beijing, we analyze the technological readiness of NETs and the gaps in total costs of ownership (TCOs) between NETs and ICE trucks for each duty cycle category. The study further identifies the policies that are effective to fill the current (2022—2024) technological and cost gaps of NETs, based on literature review and quantitative analysis.

Inverse identification of thermal behaviour of a paraffin-based phase change material in complete and partial phase change cycles

From the macroscopic point of view, phase change hysteresis (PCH) means that a phase change process (e.g. solidification) does not follow the same temperature-enthalpy path as the opposite phase change process (melting). Although the PCH is observed in most phase change materials (PCMs), it is often neglected in computational models, resulting in discrepancies when compared to experimental data. The PCH can particularly be an issue in the modelling of latent heat thermal energy storage systems, where incomplete (partial) phase transitions are quite common. Lab-scale experimental methods for characterisation of PCMs, such as differential scanning calorimetry or the temperature-history method, employ only small PCM samples, and the obtained results are often insufficient for predicting the thermal behaviour of large volumes of PCMs. The present study explores numerical modelling approaches to the PCH, addressing both complete and partial melting-to-solidification cycles. A set of validation experiments was performed, focusing on phase transitions in a paraffin-based PCM enclosed in a rectangular cavity. An inverse identification method was used to minimise the root mean square error (RMSE) of temperatures in the PCM using the particle swarm optimisation method. A two-curve approach showed the highest accuracy in complete phase change cycles, with a 62% improvement in the RMSE when compared to the manufacturer data. As for cycles with partial phase changes, a curve-scale approach showed superior behaviour, reducing the RMSE as much as 99%. Conversely, another investigated approach – a curve-track model – exhibited inferior performance, making it less suitable for the modelling of partial phase changes.

Study on the Phase Behavior Simulation Method of High-Salinity Reservoirs.

The presence of salinity affects the accuracy of existing correlations used in the equation of state. Moreover, the variation of salinity is often ignored in the systematic analysis of the phase diagram, resulting in a large error in the final calculation result. It is obvious that the conventional phase equilibrium calculation is not applicable in a high-salinity reservoir. By introducing the hydrocarbon-brine binary interaction coefficient and α-function, combined with the definition of salinity, and considering the variation of salinity under different pressure and temperature conditions, a more perfect phase equilibrium calculation model was established. The complete phase diagram was drawn, and the calculation results of salinity distribution are obtained. The effect of the mole percentage of water and salt content on the phase behavior was simulated. Finally, the phase distribution simulation is carried out based on the measured data. The phase state and salinity variation law of a high-salinity reservoir are obtained. According to the fluid composition of different periods, the real phase state of the high-salinity reservoir can be monitored in real time. It can provide a theoretical basis for the gas reservoir development and the dynamic evaluation of gas storage injection and production with a hydrocarbon-brine two-phase system.

A facile route to synthesize β‐Ga2O3 nanoparticles from γ‐polymorph through a rapid microwave route and their optical properties

AbstractDue to the wide bandgap, monoclinic structure and thermodynamic stability, β‐polymorph form of Ga2O3 nanomaterials is well‐received for various applications. However, as the γ‐Ga2O3 is difficult to synthesize, less attention has been paid towards it and its conversion to β‐polymorph. This paper reports the single‐step synthesis of γ‐Ga2O3 using a microwave‐assisted procedure. In this regard, γ‐Ga2O3 powders are synthesized in minutes using benzyl alcohol as the solvent using gallium acetylacetone as the precursor. The XRD of the as‐prepared powders indicates the formation of the γ‐Ga2O3 phase, the very broad peaks indicative of the small crystallite size as confirmed by TEM. The γ‐Ga2O3 powders were annealed at different temperatures and the complete phase conversion of γ‐Ga2O3 phase to β‐Ga2O3 phase happens at 700 °C. The TEM analysis shows the crystallite size to be ≈10 nm for the annealed β‐Ga2O3 phase. The as‐prepared nanopowders show very weak luminescence under excitation and in contrast, a blue‐green emission is observed in case of annealed powders. This confirms the presented strategy as having the potential to use β‐Ga2O3 nanopowders for different optoelectronic applications.

Nonlinear binary indium-tin-oxide terahertz emitters with complete phase and amplitude control

Terahertz (THz) waves have demonstrated immense potential for various applications in multiple fields. To enable the development of compact THz applications, it is crucial to integrate THz emission and wavefront manipulation into a single device. This study proposes and experiments with a nonlinear binary THz emitter that utilizes a patterned indium-tin-oxide (ITO) film. By precisely controlling the displacements and area sizes of the composed ITO patches, we are able to fully and independently manipulate the phase and amplitude of the locally emitted THz wave at the +1st-order diffraction, so as to the corresponding wavefront. Our innovative approach provides a promising path toward miniaturized and functioning THz devices and systems.

Optical vector-eigenmode decomposition for few-mode fibers through deep learning networks

For the optical vector-eigenmode (VE) decomposition, we introduce a novel deep learning-based optical-mode decomposition (OMD) technique for accurate retrieval of near-field beams generated from few-mode fiber (FMF) channel, in which this residual network (Resnet) scheme could obtain complete and accurate amplitude and phase coefficients from the near-field beams. For the case of 3 intra-module modes in the FMF, the correlation coefficient of the OMD reaches 0.9808, while the modal weight error and modal phase error are as low as 0.0287 and 0.0331, respectively. And for the case of 10 inter-module modes in the FMF, the correlation coefficient of the OMD achieves 0.9878, while the mode weight error and mode phase error are recorded down to 0.0071 and 0.0205, respectively. Moreover, the noise-added near-field beams show a good robustness of the OMD based on deep learning. Finally, we also investigate the relationship between modal differences and correlation coefficients, revealing the nature of VE-based OMD functions.

Room Temperature Crystallized Phase-Pure α-FAPbI3 Perovskite with In-Situ Grain-Boundary Passivation.

Energy loss in perovskite grain boundaries (GBs) is a primary limitation toward high-efficiency perovskite solar cells (PSCs). Two critical strategies to address this issue are high-quality crystallization and passivation of GBs. However, the established methods are generally carried out discretely due to the complicated mechanisms of grain growth and defect formation. In this study, a combined method is proposed by introducing 3,4,5-Trifluoroaniline iodide (TFAI) into the perovskite precursor. The TFAI triggers the union of nano-sized colloids into microclusters and facilitates the complete phase transition of α-FAPbI3 at room temperature. The controlled chemical reactivity and strong steric hindrance effect enable the fixed location of TFAI and suppress defects at GBs. This combination of well-crystallized perovskite grains and effectively passivated GBs leads to an improvement in the open circuit voltage (Voc) of PSCs from 1.08V to 1.17V, which is one of the highest recorded Voc without interface modification. The TFAI-incorporated device achieved a champion PCE of 24.81%. The device maintained a steady power output near its maximum power output point, showing almost no decay over 280h testing without pre-processing.

An experimental method of determination and validation of latent thermal energy storage dynamic characteristic by effective enthalpy

The paper draws attention to the problems of evaluating stored heat capacity in a latent heat thermal energy storage (LHTES) that operates with unsteady inlet temperature conditions. These problems are studied for custom-built LHTES designed to be charged/discharged at varying heat transfer rates in a chilled water system. The LHTES incorporates a typical fin and tube heat exchanger and commercially available ATP 20 phase change material (PCM). For the designed storage construction, the ratio of heat transfer area to PCM volume is 354 m2/m3, and the ratio of PCM volume to the total volume (compactness factor) is 0.87. The LHTES thermal characteristics were investigated on a test stand using inlet temperature inputs changing linearly at 1, 2 or 3 K/h. During each test, a complete phase transition in the PCM was ensured. Based on LHTES inlet and outlet temperature profiles, enthalpy distributions versus outlet temperature were evaluated. The experiments proved that these distributions are not a material property as they depend on the geometric characteristics of the LHTES and charging/discharging rates. However, they can describe the thermal behaviour of the PCM filling the LHTES and include the influence of a non-uniform temperature distribution inside the LHTES on the PCM hysteresis and temperature range of the complete melting/solidification. These effects can be modelled by the proposed function of effective enthalpy. The effective enthalpy allows for relatively simple monitoring of phase transition progression in the LHTES based solely on the parameters measurable outside the storage.

Gram-Scale Synthesis of Black Phosphorus through Shock-Induced Phase Transformation.

This article presents the utilization of a cylindrical double-tube shock loading device in conjunction with amorphous red phosphorus as the precursor to investigate the complete phase transformation of red phosphorus into black phosphorus under the influence of shockwaves. Multiple experiments were conducted by varying the shock pressure and temperature parameters. The characterization of the recovered samples involved analysis of the phase composition and microstructure. The obtained experimental results demonstrate that within the cylindrical double-tube shock loading setup, a pressure of 9 GPa and a temperature of 800 K are optimal for achieving the complete phase transition of amorphous red phosphorus into orthorhombic black phosphorus. By precisely controlling these experimental conditions, a high-quality orthorhombic black phosphorus powder with excellent crystallinity was successfully prepared. This method offers several advantages, including simplicity, cost-effectiveness, and high yield. Consequently, this presents a promising pathway for the industrial-scale production of black phosphorus. The implementation of this approach not only reduces the cost involved in black phosphorus synthesis but also contributes to the broad range of applications for this material.

Transport properties and electronic phase transitions in two-dimensional tellurium at high pressure

Utilizing in situ Raman spectroscopy, resistivity, and Hall-effect measurements, we conducted an extensive investigation on the continuous electronic phase transitions and transport properties of two-dimensional (2D) tellurium (Te) under high pressure at room and low temperature (80–300 K). The distinguishable decrease in the A1 Raman mode's full width at half maximum in the trigonal phase (Te-I) indicated an electronic phase transition at 2.2 GPa. The following Hall-effect experiments located the Lifshitz transition and the semiconductor-semimetal transition at 0.9 and 1.9 GPa, respectively, and the semiconductor-semimetal transition was also confirmed by resistivity variation through temperature. The charge carrier types of the Te changed from hole to electron during the phase transition from Te-I to Te-II (triclinic phase) at low temperature, while the transport parameters remained almost unchanged during the phase transition from Te-II to Te-III (monoclinic phase). The results offered complete and thorough electronic phase transitions and transport characteristics of 2D Te, hence great advancing the potential application of Te in electronic devices.

Non-Markovian dynamics of open quantum systems via auxiliary particles with exact operator constraint

We introduce an auxiliary-particle field theory to treat the non-Markovian dynamics of driven-dissipative quantum systems of the Jaynes-Cummings type. It assigns an individual quantum field to each reservoir state and provides an analytic, faithful representation of the coupled system-bath dynamics. We apply the method to a driven-dissipative photon Bose-Einstein condensate (BEC) coupled to a reservoir of dye molecules with electronic and vibronic excitations. The complete phase diagram of this system exhibits a hidden, non-Hermitian phase transition separating temporally oscillating from biexponentially decaying photon density correlations within the BEC. On one hand, this provides a qualitative distinction of the thermal photon BEC from a laser. On the other hand, it shows that one may continuously tune from the BEC to the lasing phase by circumventing a critical point. This auxiliary-particle method is generally applicable to the dynamics of open, non-Markovian quantum systems. Published by the American Physical Society 2024

Strain-driven valley-dependent Berry phase effects and topological transitions in Janus SVGeN2 monolayer

The manipulation of valley-dependent properties in two-dimensional (2D) materials is intriguing for developing valleytronics. Using first-principles calculations, we explore valley-dependent properties of Janus SVGeN2 monolayer and reveal large and tunable valley polarization by tensile strain. The SVGeN2 monolayer possesses excellent stability. Furthermore, strain-driven topological magneto-valley phase transitions are predicted for this monolayer, leading to the valley quantum anomalous Hall (VQAH) phenomenon. The VQAH state, which is featured by the coexistence of complete valley polarization and topological phase, is confirmed by sign reversal of Berry curvature and the nontrivial band topology. The calculated magnetic anisotropy energy indicates that the Janus SVGeN2 monolayer possesses a ferromagnetic ground state and in-plane magnetization. Our investigation provides some physical insights into the strain-driven topological phase transition and manipulation of valley-dependent properties to realize giant valley polarization in the Janus 2D magnet.

Recovery of consistency in thermodynamics of regular black holes in Einstein's gravity coupled with nonlinear electrodynamics

As one of candidate theories in the construction of regular black holes, Einstein's gravity coupled with nonlinear electrodynamics has been a topic of great concerns. Owing to the coupling between Einstein's gravity and nonlinear electromagnetic fields, we need to reconsider the first law of thermodynamics, which will lead to a new thermodynamic phase space. In such a phase space, the equation of state accurately describes the complete phase transition process of regular black holes. The Maxwell equal area law strictly holds when the phase transition occurs, and the entropy obeys the Bekenstein-Hawking area formula, which is compatible with the situation in Einstein's gravity.

Role of isotropic and anisotropic Dzyaloshinskii–Moriya interaction on skyrmions, merons and antiskyrmions in the C nv symmetric system

The lattice Hamiltonian with the presence of a chiral magnetic isotropic Dzyaloshinskii–Moriya interaction (DMI) in a square and hexagonal lattice is numerically solved to give the full phase diagram consisting of skyrmions and merons in different parameter planes. The phase diagram provides the actual regions of analytically unresolved asymmetric skyrmions and merons, and it is found that these regions are substantially larger than those of symmetric skyrmions and merons. With magnetic field, a change from meron or spin spiral (SS) to skyrmion is seen. The complete phase diagram for the C nv symmetric system with anisotropic DMI is drawn and it is shown that this DMI helps to change the SS propagation direction. Finally, the well-defined region of a thermodynamically stable antiskyrmion phase in the C nv symmetric system is shown.

Ultrafast Dynamics Across Pressure-Induced Electronic State Transitions, Fluorescence Quenching, and Bandgap Evolution in CsPbBr3 Quantum Dots.

This work investigates the impact of pressure on the structural, optical properties, and electronic structure of CsPbBr3 quantum dots (QDs) using steady-state photoluminescence, steady-state absorption, and femtosecond transient absorption spectroscopy, reaching a maximum pressure of 3.38GPa. The experimental results indicate that CsPbBr3 QDs undergo electronic state (ES) transitions from ES-I to ES-II and ES-II to ES-III at 0.38 and 1.08GPa, respectively. Intriguingly, a mixed state of ES-II and ES-III is observed within the pressure range of 1.08-1.68GPa. The pressure-induced fluorescence quenching in ES-II is attributed to enhanced defect trapping and reduced radiative recombination. Above 1.68GPa, fluorescence vanishes entirely, attributed to the complete phase transformation from ES-II to ES-III in which radiative recombination becomes non-existent. Notably, owing to stronger quantum confinement effects, CsPbBr3 QDs exhibit an impressive bandgap tuning range of 0.497eV from 0 to 2.08GPa, outperforming nanocrystals by 1.4 times and bulk counterparts by 11.3 times. Furthermore, this work analyzes various carrier dynamics processes in the pressure-induced bandgap evolution and electron state transitions, and systematically studies the microphysical mechanisms of optical properties in CsPbBr3 QDs under pressure, offering insights for optimizing optical properties and designing novel materials.

Phase Diagram of the Ashkin–Teller Model

The Ashkin–Teller model is a pair of interacting Ising models and has two parameters: J is a coupling constant in the Ising models and U describes the strength of the interaction between them. In the ferromagnetic case J,U>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$J,U>0$$\\end{document} on the square lattice, we establish a complete phase diagram conjectured in physics in 1970s (by Kadanoff and Wegner, Wu and Lin, Baxter and others): when J<U\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$J<U$$\\end{document}, the transitions for the Ising spins and their products occur at two distinct curves that are dual to each other; when J≥U\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$J\\ge U$$\\end{document}, both transitions occur at the self-dual curve. All transitions are shown to be sharp using the OSSS inequality. We use a finite-size criterion argument and continuity to extend the result of Glazman and Peled (Electron J Probab 28:1-53, 2023) from a self-dual point to its neighborhood. Our proofs go through the random-cluster representation of the Ashkin–Teller model introduced by Chayes–Machta and Pfister–Velenik and we rely on couplings to FK-percolation.