Phase Transition Changes Research Articles

Dynamics simulation analysis of the melting process of ice on the surface of aramid IIIA fabrics

In many industries, workers are facing the inconvenience caused by icing on fabrics. Fabric is a porous material, and researchers generally hold that porous material is not suitable for being used as an anti-icing material. Therefore, research on the anti-icing properties of fabrics have not attracted researchers' attention, thus relevant research results are few. The influence of sample surface wettability on snow melting has been rarely studied in depth. In this paper, a test device for testing the melting rate of ice on the surface of a sample was developed. Based on this experiment, a simulation model for simulating the melting process of the ice on the aramid IIIA fabric samples was established based on the melting promoting anti-icing theory. This work also indicates that the use of computational models in the study of ice melting processes is successful. Results show that the relative error between the simulated value and the experimental value was 1.63%. These computational models provide details on the phase transition and temperature changes of ice during the melting process, which are difficult to observe in experiments. Meanwhile, the simulated phase transition of ice is consistent with actual observations. The results indicate that the simulation model established in this article can be extended to study the melting process of ice on aramid IIIA fabric samples, and can be used to guide the study of the anti-icing performance of aramid IIIA fabrics.

Comparison of transformation behavior of the peritectic steels with different carbon content and its correlation to the slab quality during solidification

In order to investigate the phase transformation behaviour of peritectic steels, we devise an integrated facility for X-ray transmission imaging combined with Laue diffraction analysis and precise temperature control. This integrated facility can measure the temperature at which the delta phase transforms into the gamma phase during solidification with continuous cooling. The investigation of four alloys with different carbon content reveals the dependence of carbon content on the minimum undercooling required for gamma phase formation. As carbon content increases, the amount of undercooling for the peritectic transformation decreases, and the gamma phase onset temperature necessarily increases. X-ray transmission images, which present the growing dendrites and moving delta-to-gamma interface, confirm that the peritectic reaction is likely to occur with high carbon content, leading to the gamma phase formation before the end of solidification.On the contrary, the low carbon content suppresses the gamma phase formation, and the solid delta and liquid phase exist under equilibrium peritectic temperature. Once after the gamma phase nucleation, the phase change occurs rapidly with increasing undercooling. The delay in gamma phase formation results in massive phase transition and rapid change of interface velocity with a slight variation of undercooling. The fast kinetic of solid phase transformation is associated with a corresponding increase of internal stress, leading to the degradation of slab quality.

Impact of Co doping on the magnetic and transport properties of FeRh

FeRh undergoes a first-order phase transition from the antiferromagnetic (AFM) to ferromagnetic (FM) state at ∼370 K, which is highly sensitive to strain and compositional changes. In this study, we investigate the magnetic and electronic properties of Co-doped FeRh films fabricated using a co-sputtering technique, to address how the magnetic transition behavior is influenced by the doping in FeRh films. By adjusting Co sputtering gun currents (=0, 5, 8, and 10 mA), we achieve Co doping levels from 1 to 2 at. %, where initial Co atoms (for 5 and 8 mA) substitute Rh sites, while doped Co levels (for 10 mA) begin to occupy Fe sites with unchanged Co doping level of 2 at. %. We find that Co substitution significantly lowers the transition temperature, attributed to an enhancement of the FM phase due to the contribution of magnetic Co doping. Furthermore, the Co doping leads to a remarkable increment in the magnetoresistance ratio during the transition, reaching up to 190% for only 2 at. % Co doping, while keeping the magnetization change. The Hall effect measurements indicate a slight reduction in carrier density with Co doping, maintaining changes in carrier type across the phase transition. These results highlight the tunable magnetic phase transition and resistance changes in Co-doped FeRh films. This study provides valuable insights into the complex physics underlying the Co doping in FeRh films, emphasizing their scientific value in understanding the mechanism of the AFM–FM transitions in achieving high magnetoresistance.

Experimental solubility of omeprazole in pure and ethanol-modified subcritical water

The current research aimed to study and measure the solubility of omeprazole (used to treat and reduce stomach acid) for the first time in pure subcritical and ethanol-modified water. These tests have been performed in the 25–130 °C temperature range and constant pressure of 20 bar with the use of 0–10% ethanol weight as the cosolvent. The solubility of omeprazole in subcritical water ranged from 0.0697 × 10–4 to 5.843 × 10–4 mol fraction at temperatures from 25 to 130 °C, respectively. The highest solubility was obtained at 130 °C with a 10% ethanol weight as the cosolvent, which is indicative of a significant trend of improvement in omeprazole solubility with the increase in temperature and the use of ethanol cosolvent in various weight percentages. The solubility experimental data obtained were fitted using the semi-experimental and modified Apelblat linear model, and the findings revealed an excellent correlation between the experimental data and the data received from the linear and modified Apelblat model. Also, at the 25–130 °C temperature range, no degradation, phase transition, or other changes in the structure and physical state of the drug were observed.

Unraveling the origin of conductivity change in Co-doped FeRh phase transition

Phase-changing materials have been a cornerstone of condensed matter physics for decades. A quintessential example is iron-rhodium (FeRh), which undergoes a first-order phase transition from antiferromagnetic to ferromagnetic states near room temperature. The pivotal aspect of this transition is a marked alteration in electrical conductivity. However, its underlying origin still remains elusive, largely due to the difficulties of directly probing fundamental transport during this phase transition. In this study, we investigate the fundamentals of FeRh’s electrical transport employing terahertz time-domain spectroscopy (THz-TDS). Leveraging the Drude model, we discerned the distinct contributions of extrinsic (momentum scattering time, τ) and intrinsic (charge density, n, and effective mass, m*) factors to electrical conductivity independently. Notably, our investigation unveiled a sharp alteration in n and m* during the phase transition, contrasting with the gradual monotonic decrease of τ with rising temperature. Consequently, our findings provide compelling evidence that the conductivity change in FeRh during the phase transition originates from a restructuring of its band structure. This work provides a crucial step towards a comprehensive understanding of the electrical transport changes occurring during the phase transition, offering valuable insights into the behaviour of phase changing materials.

Effect of side ratio on the two-degrees-of-freedom vortex-induced vibrations of the rectangular cross section model

The effect of the mutative side ratio (D/B) on the vortex-induced vibration (VIV) characteristic, aerodynamic characteristics, and the surrounding time-averaged and transient flow field of a rectangular cross section model were simulated numerically. Based on Fluent 19.0 platform, overset grid technology and the fourth-order Runge–Kutta method were used at Re 22 000. First, a rectangular cross section model with D/B = 0.25 was selected, and the simulation method and parameter settings were validated against previous literatures. The subsequent analysis compared and evaluated the effect of side ratio on the VIV response by focusing on statistical values of aerodynamic force coefficients, self-spectra, amplitude ratio, motion trajectory, and phase transition changes for stream-wise and cross-flow directions. Moreover, the study examined the influence of different models at different reduced velocities (Ur) on wake vortex-shedding. The findings suggest that, within a fixed cross-sectional area, a smaller side ratio leads to a weaker VIV characteristic and notably lower aerodynamic performance compared to a larger side ratio. The vortex-shedding mode of the rectangular cross section, particularly with a large side ratio, is less sensitive to changes in Ur compared to the standard square cylinder. An examination of the Reynolds number (Re) effect on the minimum and maximum side ratio models reveals that it has a more pronounced impact on the aerodynamic performance and VIV of the cross-flow when compared to in-line flow. In general, it is noted that larger side ratio model exhibits a stronger sensitivity to the variation of Re.

On the influence of atmospheric pressure plasma treatment on polyethylene terephthalate glycol filaments for 3D printing

Polymers are crucial in a variety of industries; nevertheless, surface modification is required for particular applications. Non-thermal plasma exposure is a viable and environmentally friendly option. Fused deposition molding employs polyethylene terephthalate glycol, but has limits in biomedical applications due to poor mechanical characteristics. This study investigates how atmospheric pressure plasma created by a dielectric barrier discharge system using helium and/or argon affects the modification of polyethylene terephthalate glycol surfaces, variations in wettability properties, and chemical composition alterations. The plasma source was ignited with either helium or argon and the operating conditions were optimized for polymer exposure. The study found that plasma treatment increased polymer surface wettability by up to 30% in helium and 40% in argon. The plasma treatments altered the surface topography, morphology, roughness, and hydrophilicity. After plasma treatment, the material’s mechanical characteristics underwent soft change. Plasma exposure resulted in notable changes in dielectric characteristics, phase transitions, and structure. The experimental results justify the use of atmospheric pressure plasma technologies for environmentally friendly polymer material processing, particularly for applications that require enhanced adhesion and unique criteria.

Distinct High-Pressure Responses of Halide Perovskites from Bulk to Low Dimension

Hybrid organic-inorganic perovskites (HOIPs) are low-cost and highly efficient optoelectronic and photovoltaic materials for applications in solar cells, light emitting diodes (LEDs), and so on, which is correlated with their intrinsic structures. Now the hybrid perovskite families include three-dimensional (3D) (CH3NH3PbBr3), two-dimensional (2D) ((C4H9NH3)2(CH3NH3)n-1PbnI3n+1) and nanostructured ((CH3NH3PbBr3 nanoparticles) materials. Herein, well understanding the relationship between the cystal structures and the related functional properties of HOIP materials is essential to the application point of view. High pressure up to gigapascal, offers a comprehensive way to study the structure-property correlation of solid materials in the atomic level, where both crystal structures and electronic properties are changed dramatically.In this presentation, high pressure induced dramatically inorganic and organic part changes in 2D HOIPs are comprehensively studied[1,2], as shown in Figure 1. On the other hand, structural phase transition and morphology changes are also explored in 3D HOIP and their nanoparticles[3], as shown in Figure 2. All the high pressure-induced inorganic structural transition is resolved by in situ X-ray powder diffraction (XRD) measurements, morphology change is resolved by transmission electron microscopy (TEM), the correlated optical responses are investigated by absorption and photoluminescence spectroscopy. And the rotational isomerism is evidenced by the vibrational properties of the organic BA chain by Raman spectroscopy combined with the Ab initio calculations.Reference:[1] T Yin, B Liu, J Yan, Y Fang, M Chen, WK Chong, S Jiang, J-L Kuo, J Fang, P L, S-H W, K-P Loh, T-C Sum, T J. White, and Z Xiang, J. Am. Chem. Soc. 141, 1235 (2019).[2] Yin T, Yan H, Abdelwahab I, Lekina Y, Lü X, Yang W, Sun H, Leng K, Cai Y, Shen Z, Loh KP, Nat. Commun. 14, 411 (2023).[3] T Yin, Y Fang, WK Chong, KT Ming, S Jiang, X Li, J-L Kuo, J Fang, T-C Sum, T J. White, J Yan, and Z Xiang, Adv. Mater. 30, 1705017 (2018). Figure 1

Effect of charm quark on chiral phase transition in Nf=2+1+1 holographic QCD

We investigate the effect of the charm quark on the chiral phase transition of light quarks at finite temperature based on the four-flavor soft-wall holographic QCD model. In the massless limit, we find that the thermal chiral phase transition is of the second order in the four-quark-flavor system. In the case with the massive charm quark and the massless light and strange quarks, the order of the phase transition changes to the first order. This is due to the quark-flavor symmetry breaking which is associated with the violation of the U(1) axial symmetry. Once the light and strange quarks get massive, the explicit chiral symmetry breaking becomes eminent, and then the crossover phase transition is realized at the physical quark masses. We also map the order of the phase transition on a phase diagram in the quark-mass plane where the light- and strange-quark masses are degenerate but differ from the value of the charm-quark mass. This phase diagram is an extension of the conventional Columbia plot to the four-quark-flavor system. The critical exponents related to the chiral phase transition are also addressed. Published by the American Physical Society 2024

Field-induced effects and ferroelectric critical endpoint in (K0.95Li0.05)(Nb1–x Ta x )O3 single crystals

Dielectric permittivities under dc biasing fields in the temperature range between –169 °C and 75 °C have been investigated in (K0.95Li0.05)(Nb1–x Ta x )O3 (KLNT–x, x = 71% and 74%). Field-induced ferroelectric phase transitions in KLNT–x have been clarified in the dc field applied along the [001] c direction (in the cubic coordinate). The ferroelectric critical endpoints in KLNT–71% and KLNT–74% have been determined to be 43.5 °C, 3.0 kV cm−1, and 30.3 °C, 2.0 kV cm−1, respectively. The tricritical point at which the first-order phase transition changes to the second-order phase transition has been estimated at 10.4 °C and x = 77.4% in the temperature–concentration phase diagram. The field-induced phase transitions and dielectric tunabilities have been discussed on the basis of the Landau-type free energy density.

Phase Transition and Luminescent Property Change Induced by Different Organic Cations in One-Dimensional Double Perovskites.

Double perovskites (DPs) have attracted attention in the field of luminescence due to their inherent broadband emission of self-trapping excitons. In this work, we choose [(CH3)3NCH2CHCH2]+ and [CH3CHOHCH2NH2]+ as organic cations to synthesize two new organic-inorganic hybrid DPs, [(CH3)3NCH2CHCH2]2KInCl6 (1) and [CH3CHOHCH2NH2]2KInCl6 (2). The [KCl6]3- and [InCl6]3- octahedra are interchangeably connected by sharing two opposite faces, forming a one-dimensional coordination chain. Each K atom coordinates with six chlorine atoms in 1, while it coordinates with two oxygen atoms in addition to the six chlorine atoms in 2. The coordination between ions K and O in compound 2 may have significantly reduced its luminescence. As a result, compound 1 shows bright-yellow light with a quantum yield of more than 90%, while 2 shows weak blue light with a quantum yield of only 0.98%. In addition, different from no phase transition found in 2, 1 undergoes a reversible phase transition at 324/307 K in the heating-cooling cycle. Through structural and spectral analysis and density functional theory calculation, we conclude that the larger degree of [InCl6]3- octahedral distortion and the larger anion distance (In···In) also cause the PLQY of compound 1 to be higher than that of compound 2.

Effect of borax on the hydration and hardening of β-hemihydrate gypsum at high water–plaster ratio

The existing methods of preparing lightweight gypsum blocks are to make hollow slats or to make foamed blocks, both of which are defective and fail to meet the standards. In order to prepare lightweight gypsum blocks, this paper investigates the method of increasing the proportion of moisture to reduce the weight of gypsum blocks. To further understand the performance relation between β-hemihydrate gypsum (β-hemihydrate phosphogypsum and β-hemihydrate flue-gas desulfurization gypsum) and its products, the effect of borax on the hydration and hardening of β-hemihydrate gypsum at high water–plaster ratio was studied. The results showed that with an increase in borax dosage, the setting time of β-hemihydrate phosphogypsum (β-HPG) was evidently prolonged; the initial setting time increased from 15 to 62 min, and the final setting time increased from 22 to 93 min. The difference between the initial and final setting times also increased, and the fluidity of the gypsum slurry was improved. When the borax dosage reached 0.5%, the flexural strength of β-hemihydrate flue-gas desulfurization gypsum (β-HFGD) increased from 5.2 to 6.3 MPa and the compressive strength increased from 4.7 to 9.3 MPa after 28 d. By analyzing the changes in phase transition, hydration degree, infrared spectrum, particle size, and crystal microstructure during the hydration of β-hemihydrate gypsum, it was found that β-HPG was more sensitive to borax than β-HFGD at high water–plaster ratio and β-HFGD showed superior mechanical properties. The study findings will provide a theoretical basis for the application of β-hemihydrate gypsum products under humid conditions and expand the application range of gypsum products.

Thermodynamic properties and phase diagram of quark matter within non-extensive Polyakov chiral SU (3) quark mean field model

In the present study, we applied Tsallis non-extensive statistics to investigate the thermodynamic properties and phase diagram of quark matter in the Polyakov chiral SU(3) quark mean field model. Within this model, the properties of the quark matter were modified through the scalar fields , vector fields , ϕ, and Polyakov fields Φ and at finite temperature and chemical potential. Non-extensive effects were introduced through a dimensionless parameter q, and the results were compared to those of the extensive case ( ). In the non-extensive case, the exponential in the Fermi-Dirac (FD) function was modified to a q-exponential form. The influence of the q parameter on the thermodynamic properties, pressure, energy, and entropy density, as well as trace anomaly, was investigated. The speed of sound and specific heat with non-extensive effects were also studied. Furthermore, the effect of non-extensivity on the deconfinement phase transition as well as the chiral phase transition of and s quarks was explored. We found that the critical end point (CEP), which defines the point in the phase diagram where the order of the phase transition changes, shifts to a lower value of temperature, , and a higher value of chemical potential, , as the non-extensivity is increased, that is, 1.

Studies on the Arrott plots of inhomogeneous first order magnetic phase transitions

First order ferromagnetic to paramagnetic phase transition is studied using the Bean-Rodbell model within the mean-field framework. The presence of sample inhomogeneities is modeled by considering distributions of the Bean-Rodbell parameter. The corresponding Arrott plots with and without distributions of the Bean-Rodbell parameter are generated and compared. Results indicate that in the presence of inhomogeneities, ferromagnetic to paramagnetic phase transition is broadened. The initial negative slopes in the Arrott plots due to first order phase transition changes to positive slopes for temperatures lying in the broadened tail region of the ferromagnetic to paramagnetic phase transitions. However, the initial negative slopes in the paramagnetic regime (for temperatures above the broadened tail region) are preserved even in the presence of sample inhomogeneities. Also, the effect of inhomogeneities on the magnetic entropy change near the first order transition is studied.

Influence of the length of end-group double bond substituents on the temperature change of phase transition in liquid crystals

ABSTRACT A series of nematic liquid crystal (LC) monomers, containing a reactive group in the lateral substituent, were designed and synthesised through an organic synthesis reaction. Considerable changes were made to the properties of the liquid monomers by varying the terminal alkyl chain lengths. The molecular structures of the intermediates and the LC monomers were characterised by flourier infrared absorption spectrometry and proton nuclear magnetic resonance (1H NMR) spectroscopy, leading to the identification of the target product. The phase transition temperatures of the LC monomers were observed and analysed using differential scanning calorimetry (DSC) and polarising optical microscopy (POM) with a hot stage. The two-way thermotropic liquid crystalline behaviour was observed during the heating process, providing insight into the effect of substituent changes on the phase transition temperature.

High‐Performance Reversible Oxygen Reduction/Evolution Gas Diffusion Electrodes with Multivalent Cation Doped Core‐Shell Mn/Mn3O4 Catalysts

AbstractThe development of precious‐metal‐free catalysts with bifunctional activities for both oxygen reduction and evolution reactions (ORR/OER) is crucial for the advancement of regenerative fuel cells and rechargeable metal−air batteries. Manganese oxides (MnOx) have emerged as promising bifunctional catalysts. However, MnOx electrodes typically exhibit poor ORR/OER cycling stability owing to polarization‐induced MnOx redox reactions and phase transition. To address this issue, we developed metallic cation (i. e., Co2+, Ni2+, Cu2+, or Bi3+) doped MnOx/carbon electrodes using potentiodynamic, potentiostatic and galvanostatic methods. Among the explored dopant cations Ni2+ intercalated into MnOx under acidic conditions using a slow‐scan cyclic voltammetry method, significantly enhanced the ORR/OER activity and stability of MnOx. Alongside electrochemical doping, MnOx also underwent redox reactions leading to changes in Mn valence and phase transitions. The Ni‐incorporated MnOx gas diffusion electrode (GDE) demonstrated exceptional stability for over 120 accelerated OER and ORR cycles at ±10 mA cm−2 in 5 M KOH, surpassing the performance of the Pt/C−IrO2 benchmark. Furthermore, it achieved OER current densities of approximately 22 mA cm−2 at 1.65 VRHE, which was twice as high as that of Pt/C−IrO2.

Mn-Rich P′2-Na0.67[Ni0.1Fe0.1Mn0.8]O2 As High-Energy-Densityand Long-Life Cathode Material for Sodium-Ion Batteries

P′2-type Na0.67[Ni0.1Fe0.1Mn0.8]O2 is introduced as a promising new cathode material for sodium-ion batteries (SIBs) that exhibits remarkable structural stability during repetitive Na+ de/intercalation. The O-Ni-O-Mn-O-Fe-O bond in the octahedra of transition-metal layers is used to suppress the elongation of the Mn-O bond and to improve the electrochemical activity, leading to the highly reversible Na storage mechanism. A high discharge capacity of ≈220 mAh g−1 (≈605 Wh kg−1) is delivered at 0.05 C (13 mAg−1) with a high reversible capacity of ≈140 mAh g−1 at 3 C and excellent capacity retention of 80% over 200 cycles. This performance is associated with the reversible P′2–OP4 phase transition and small volume change upon charge and discharge (≈3%). The nature of the sodium storage mechanism in a full cell paired with a hard carbon anode reveals an unexpectedly high energy density of ≈542 Wh kg−1 at 0.2 C and good capacity retention of ≈81% for 500 cycles at 1 C (260 mAg−1).

A Ni/Co-free high-entropy layered cathode with suppressed phase transition and near-zero strain for high-voltage sodium-ion batteries

High-entropy layered oxides have emerged as a new class of cathode materials for sodium-ion batteries by providing infinite possibilities to tailor energy storage capabilities. However, owing to the lack of advanced high-entropy layered material, the influence of configurational entropy/compositional disorder on the high-voltage electrochemical performance of sodium-based layered cathode has seldom been explored. In this work, a Ni/Co-free high-entropy layered oxide P2-Na0.65Mn0.65Cu0.2Li0.06Mg0.015Ti0.015Al0.015Zr0.015Y0.015La0.015O2 (Mn-Cu-HEO) was prepared by stirring hydrothermal method, and investigated as a new cathode material for sodium-ion batteries. It is found that high configurational entropy and strong M−O configurations (M = Ti, Al, Zr, Y, and La) greatly stabilize the layered framework structure and MnO6 octahedral local structure, restraining the deleterious phase transition and large volume change during high-voltage cycling, thus resulting in high reversible cationic/anionic redox. In the meantime, disordered atomic arrangement in transition metal layer efficaciously mitigates Na+/vacancy ordering during de-/sodiation, enhancing the Na+ transport kinetics. Benefiting from the high-entropy stabilization effect, complex atomic arrangement, and multielemental composition, Mn-Cu-HEO displays splendid cyclic stability (87.2 % capacity retention after 500 cycles, very small change in cell volume (0.53 %) after 100 cycles), excellent rate capability (55.5 mAh g−1 at 10C), and a usable reversible capacity of 85.1 mAh g−1 at 1C in high-voltage range of 2.0–4.5 V. This work expands the horizons of high-entropy layered materials, providing new insight in the design and construction of highly stable and high-voltage sodium ion host.

Unraveling Complex Hysteresis Phenomenon in 1,2-Dipalmitoyl-sn-Glycero-3-Phosphocholine Monolayer: Insight into Factors Influencing Surface Dynamics.

This study explores the hysteresis phenomenon in DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) monolayers, considering several variables, including temperature, compression and expansion rates, residence time, and subphase content. The investigation focuses on analyzing the influence of these variables on key indicators such as the π-A isotherm curve, loop area, and compression modulus. By employing the Langmuir-Blodgett technique, the findings reveal that all the examined factors significantly affect the aforementioned parameters. Notably, the hysteresis loop, representing dissipated energy, provides valuable insights into the monolayer's viscoelasticity, molecular packing, phase transition changes, and resistance during the isocycle process. These findings contribute to a comprehensive understanding of the structural and dynamic properties of DPPC monolayers, offering insights into their behavior under varying conditions. Moreover, the knowledge gained from this study can aid in the development of precise models and strategies for controlling and manipulating monolayer properties, with potential applications in drug delivery systems, surface coatings, as well as further investigation into air penetration into alveoli and the blinking mechanism.

Static magnetic field improvement of the quality of rice dumpling subjected to freeze–thaw cycles: Roles of phase transition of water and changes in structural and physicochemical properties of glutinous rice flour

This study aimed to investigate the effect of static magnetic field (SMF, 0–10 mT) on the quality of rice dumplings subjected to 7, 14, 21, and 28 freeze–thaw cycles. The underlying mechanism was explored by monitoring changes in water phase transition, water distribution, and structural and physicochemical properties of rice flour. Results suggested that SMF enables the formation of small ice crystals by accelerating freezing rate, shortening phase transition time, and increasing bound water content, which attributes to reducing the mechanical damage on starch granules and thus improves the quality of frozen rice dumpling. After 7–28 freeze–thaw cycles, SMF treatment increased the whiteness by 0.08–1.58, reduced the cracking ratio by 1.67 %–8.34 %, decreased the water loss ratio by 0–0.75 %, and significantly improved the texture of cooked rice dumplings. This study confirmed the feasibility of SMF in improving the quality of rice dumpling, which contributes to expanding the applications of magnetic freezer in the preservation of starch-based foods.