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Pressure-induced polymorphism has recently been demonstrated in several high entropy alloys. This offers a new window into the much-debated issue of phase selection and stability in these systems. Here, we examine the effect of cryogenic temperatures on the pressure-induced transition from face centered cubic to hexagonal close-packed structures of the prototype CoCrFeMnNi (Cantor) alloy. We observe a reduction in the critical pressure for the onset of the polymorphic transition as the temperature decreases, confirming the progressive stabilization of the hexagonal phase with decreasing temperature previously predicted by ab initio calculations accounting for magnetic interactions. We argue that in situ high-pressure experiments at cryogenic temperatures, which suppress time-dependent transformation triggered at higher temperatures, present a unique opportunity to significantly improve our understanding of these complex alloys. [ABSTRACT FROM AUTHOR]

The relaxor ferroelectric crystal Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT), located near the morphotropic phase boundary (MPB), exhibits exceptionally high piezoelectric and electro-optic (EO) responses. Nevertheless, lower optical transparency and phase transition temperature of PMN-PT limit its optical applications. The ternary system Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) holds promise in addressing these challenges with a higher Curie temperature. Additionally, specific ferroelectric domain polarization techniques can eliminate domain scattering, substantially enhancing the transparency of the crystal. In this study, we explore the optical properties of Sm-doped PIN-PMN-PT. We achieve a 2R domain-engineered state by polarizing along the (110) direction of the crystal. The high transparency allows us to extract an effective EO coefficient of up to 431.5 pm/V from the Sm-PIN-PMN-PT crystal at the telecommunications wavelength. Second-harmonic generation (SHG) probing verified the domain-engineered state in Sm-PIN-PMN-PT. The temperature-dependent SHG reveals the ferroelectric phase transition process, laying the groundwork for studying the stability of the EO response. The Sm-PIN-PMN-PT crystal exhibits an exceptionally high EO coefficient, which is crucial for the development of enhanced EO devices with high integration and low driving voltages. [ABSTRACT FROM AUTHOR]

This study explores the dynamics of self-assembly and mesophase formation through molecular dynamics simulations of hexagonal and lamellar systems using a simplified coarse-grained model. We focus on characterizing the order–disorder transitions driven by temperature variations and emphasize the often overlooked disordered regime, which serves as a precursor to periodic mesoscale ordering. Our findings not only underscore the morphological richness of the disordered regime, comparable to that of its periodic counterparts, but also reveal the presence of clustering regimes within isotropic phases, thus corroborating prior experimental and theoretical observations. By employing the dynamic correlation coefficient, this work introduces a novel approach to understanding the fundamental mechanisms of mesophase formation, providing new insights into the complex dynamics of self-assembly. [ABSTRACT FROM AUTHOR]

In this paper, we explored the resistivity behavior of Sb7Se3 thin films on flexible mica. The films maintained their resistance characteristics through various thicknesses and bending cycles. With increasing bends, resistivity and phase transition temperature of both amorphous and crystalline states rose, while the resistance drift coefficient gradually increased. Raman and near infrared experiments confirmed the internal structural changes and bandgap enhancement after bending. Transmission electron microscopy showed enhanced crystallization and uniform element distribution after annealing. Atomic force microscopy observed cracks, explaining the property changes. Additionally, we developed a flexible Sb7Se3 thin-film resistive device with swift reversibility (∼10 ns) regardless of bending, opening new avenues for flexible information storage. [ABSTRACT FROM AUTHOR]

We here present the normal dynamics technique, which recasts the Newton's equations of motion in terms of phonon normal modes by exploiting a proper sampling of the reciprocal space. After introducing the theoretical background, we discuss how the reciprocal space sampling enables us to (i) obtain a computational speedup by selecting which and how many wave vectors of the Brillouin zone will be considered and (ii) account for distortions realized across large atomic distances without the use of large simulation cells. We implemented the approach into an open-source code, which we used to present three case studies: in the first one, we elucidate the general strategy for the sampling of the reciprocal space; in the second one, we illustrate the potential of the approach by studying the stabilization effect of temperature in α-uranium; and in the last one, we investigate the characterization of Raman spectra at different temperatures in MoS2/MX2 transition metal dichalcogenide heterostructures. Finally, we discuss how the procedure is general and can be used to simulate periodic, semiperiodic, and finite systems such as crystals, slabs, nanoclusters, or molecules. [ABSTRACT FROM AUTHOR]

We synthesized the Lu 2 CoCrO 6 compound, multiferroic member of double perovskite system, by sol–gel method and then investigated the crystal structure, magnetization, magnetocaloric effect (MCE), and electrical polarization study. The analysis of powder x-ray diffraction pattern confirms that the monoclinic crystal structure with P2 1 /n space group is better fitting for the Lu 2 CoCrO 6 compound. Distribution between Co and Cr ions at the B-site is not perfectly ordered. Partial ordering between these B-site cations leads to a certain degree of disorder due to the presence of antisite defects and antiphase boundaries. These anti-site disorders (in the B-site) generate various fascinating magnetic phenomena. Although the temperature dependent inverse susceptibility plot shows predominant antiferromagnetic ground state in this system, simultaneously, a second order magnetic phase transition was observed from the Arrott plot. Moreover, the isothermal magnetization study confirms the coexistence of antiferromagnetic (AFM) and ferromagnetic (FM) phases below the transition temperature. The investigation of the magnetocaloric effect shows that the AFM phase of the system converts into the FM phases above critical field values. However, the breakdown of universal behavior of MCE in the paramagnetic region confirms the coexistence of the AFM phase as a secondary phase within the FM matrix. In addition, at lower temperatures, we observe a clear and well-defined ferroelectric hysteresis loop, suggesting ferroelectricity in the material. From these results, we conclude that Lu 2 CoCrO 6 is a multiferroic material in which the coexisting magnetic and multiferroic phases appear to be correlated and weak magneto-electric coupling was also observed. Furthermore, our experimental results help to encourage basic fundamental as well as applied research on rare-earth and transition metal based double perovskite systems due to their complex exchange interaction and multiferroic behavior. [ABSTRACT FROM AUTHOR]

Solid-state refrigeration using barocaloric materials is environmentally friendly and highly efficient, making it a subject of global interest over the past decade. Here, we report giant barocaloric effects in sodium hexafluorophosphate (NaPF6) and sodium hexafluoroarsenate (NaAsF6) that both undergo a cubic-to-rhombohedral phase transition near room temperature. We have determined that the low-temperature phase structure of NaPF6 is a rhombohedral structure with space group R 3 ¯ by neutron powder diffraction. There are three Raman active vibration modes in NaPF6 and NaAsF6, i.e., F2g, Eg, and A1g. The phase transition temperature varies with pressure at a rate of dTt/dP = 250 and 310 K GPa−1 for NaPF6 and NaAsF6. The pressure-induced entropy changes of NaPF6 and NaAsF6 are determined to be around 45.2 and 35.6 J kg−1 K−1, respectively. The saturation driving pressure is about 40 MPa. The pressure-dependent neutron powder diffraction suggests that the barocaloric effects are related to the pressure-induced cubic-to-rhombohedral phase transitions. [ABSTRACT FROM AUTHOR]

The multiferroic Y-type hexaferrites BaxSr2−xMe2Fe12−yAlyO22 (Me = Zn2+, Co2+, Mg2+, etc.) have attracted much attention due to their giant magnetoelectric (ME) effect up to room temperature and low modulated magnetic field by the chemical doping control of the complex magnetic phases. However, the research of substitution between the Me ions is rare. As doping at the Me ion site can combine the advantages of both, e.g., higher magnetic ordering temperature in Co2 and stronger ME coefficient in Mg2 Y-type hexaferrites, herein, we report the stability and switching of magnetoelectric states in the Y-type hexaferrites Ba0.5Sr1.5CoMgFe11AlO22 single crystals. Our results demonstrate that substituting half of the Mg2+ with Co2+ enhances the transition temperature of the alternating longitudinal conical phase to proper screw spin order up to room temperature compared to those Mg2 Y-type hexaferrites. Simultaneous occurrence of in-plane and out-of-plane ferroelectric polarization is observed, alongside comparable spontaneous magnetization. It was found that the in-plane spin-driven polarization can be reversible below 50 K with a substantial ME coefficient α = −8000 ps/m but becomes irreversible at 100 K. This reversal in the sign of the ME coefficient signifies the transition between two distinct ME states at high temperature. The reversibility and irreversibility of spin-induced polarization are discussed within the framework of free energy based on the ferroelectric phase, which prevail in numerous Y-type hexaferrites. Our results provide insights into understanding the role of the Me ions in the magnetoelectric coupling in Y-type hexaferrites. [ABSTRACT FROM AUTHOR]

The multiferroic Y-type hexaferrites BaxSr2−xMe2Fe12−yAlyO22 (Me = Zn2+, Co2+, Mg2+, etc.) have attracted much attention due to their giant magnetoelectric (ME) effect up to room temperature and low modulated magnetic field by the chemical doping control of the complex magnetic phases. However, the research of substitution between the Me ions is rare. As doping at the Me ion site can combine the advantages of both, e.g., higher magnetic ordering temperature in Co2 and stronger ME coefficient in Mg2 Y-type hexaferrites, herein, we report the stability and switching of magnetoelectric states in the Y-type hexaferrites Ba0.5Sr1.5CoMgFe11AlO22 single crystals. Our results demonstrate that substituting half of the Mg2+ with Co2+ enhances the transition temperature of the alternating longitudinal conical phase to proper screw spin order up to room temperature compared to those Mg2 Y-type hexaferrites. Simultaneous occurrence of in-plane and out-of-plane ferroelectric polarization is observed, alongside comparable spontaneous magnetization. It was found that the in-plane spin-driven polarization can be reversible below 50 K with a substantial ME coefficient α = −8000 ps/m but becomes irreversible at 100 K. This reversal in the sign of the ME coefficient signifies the transition between two distinct ME states at high temperature. The reversibility and irreversibility of spin-induced polarization are discussed within the framework of free energy based on the ferroelectric phase, which prevail in numerous Y-type hexaferrites. Our results provide insights into understanding the role of the Me ions in the magnetoelectric coupling in Y-type hexaferrites. [ABSTRACT FROM AUTHOR]

In this study, phase transitions (structural and magnetic) and associated magnetocaloric properties of stoichiometric MnCoGe have been investigated as a function of annealing pressure. Metastable phases were generated by annealing at 800 ° C followed by rapid cooling under pressures up to 6.0 GPa. The x-ray diffraction results reveal that the crystal cell volume of the metastable phases continuously decreases with increasing thermal processing pressure, leading to a decrease in the structural transition temperature. The magnetic and structural transitions merge and form a first-order magnetostructural transition between the ferromagnetic orthorhombic and paramagnetic hexagonal phases over a broad temperature range (>80 K) spanning room temperature, yielding considerable magnetic entropy changes. These findings demonstrate the utility of thermal processing under high pressure, i.e., high-pressure annealing, to control the magnetostructural transitions and associated magnetocaloric properties of MnCoGe without altering its chemical composition. [ABSTRACT FROM AUTHOR]

We report a theoretical investigation of temperature, size, and composition effects on the structural, energetic, and electronic properties of the (La4O6)n, (La2Ce2O7)n, and (Ce4O8)n nanoclusters (NCs) for n = 10, 18. Furthermore, we investigated the single O vacancy formation energy as a function of the geometric location within the NC. Our calculations are based on the combination of force-field molecular dynamics (MD) simulations and density functional theory calculations. We identified a phase transition from disordered to ordered structures for all NCs via MD simulations and structural analysis, e.g., radius changes, radial distribution function, common neighbor analysis, etc. The transition is sharp for La36Ce36O126, La20Ce20O70, and Ce72O144 due to the crystalline domains in the core and less abrupt for Ce40O80, La40O60, and La72O108. As expected, radius changes are abrupt at the transition temperature, as are morphological differences between NCs located below and above the transition temperature. We found a strong dependence on the O vacancy formation energy (Evac) and its location within the NCs. For example, for La40O60, Evac decreases almost linearly as the distance from the geometric center increases; however, the same trend was not observed for Ce40O80, while there are large deviations from the linear trend for La20Ce20O70. Evac has smaller values for Ce40O80 and higher values for La40O60, that is, almost three times, while Evac has intermediate values for mixed oxides, as expected from weighted averages. Therefore, the mixture of one formula unit of La2O3 with two formula units of CeO2 has the effect of increasing the stability of CeO2 (binding energy), which increases the magnitude of the formation energy of the O vacancy. [ABSTRACT FROM AUTHOR]

[001]-textured 0.4P(Mg1/3Nb2/3)O3-0.25PbZrO3-0.35PbTiO3-0.5%MnO2 (Mn-PMN-PZT) ceramics were fabricated by templated grain growth using 2 vol. % BaTiO3 in this paper. Full matrices of dielectric (ɛij), elastic (sij, cij), and piezoelectric (dij) parameters were obtained by the resonance–antiresonance method. The dielectric constant ɛ33T of textured ceramics reaches 2600, which is four times that of random ceramics. Textured Mn-PMN-PZT ceramics exhibit high d33 = 984 pC/N and high k33 = 0.89, which is much larger than d33 = 223 pC/N and k33 = 0.70 of random ceramics. However, ɛ11T of ceramics decreases by about 30% after texturing, and the corresponding shear coupling coefficient k15 also decreases from 0.66 to 0.44, which may be due to the reduction in the angle between spontaneous polarization and transverse direction. Furthermore, the temperature stability of the textured ceramics was evaluated as well. The phase transition temperature TR−T was determined by the impedance method to be 120 °C. The textured Mn-PMN-PZT ceramic shows high temperature stability, which is better than PMN-PT. [ABSTRACT FROM AUTHOR]

UNLABELLED: Invasive mold infections (IMIs) are associated with high morbidity, particularly in immunocompromised patients, with mortality rates between 40% and 80%. Early initiation of appropriate antifungal therapy can substantially improve outcomes, yet early diagnosis remains difficult to establish and often requires multidisciplinary teams evaluating clinical and radiological findings plus supportive mycological findings. Universal digital high-resolution melting (U-dHRM) analysis may enable rapid and robust diagnoses of IMI. A universal fungal assay was developed for U-dHRM and used to generate a database of melt curve signatures for 19 clinically relevant fungal pathogens. A machine learning algorithm (ML) was trained to automatically classify these pathogen curves and detect novel melt curves. Performance was assessed on 73 clinical bronchoalveolar lavage samples from patients suspected of IMI. Novel curves were identified by micropipetting U-dHRM reactions and Sanger sequencing amplicons. U-dHRM achieved 97% overall fungal organism identification accuracy and a turnaround time of ~4 hrs. U-dHRM detected pathogenic molds (Aspergillus, Mucorales, Lomentospora, and Fusarium) in 73% of 30 samples classified as IMI, including mixed infections. Specificity was optimized by requiring the number of pathogenic mold curves detected in a sample to be >8 and a sample volume to be 1 mL, which resulted in 100% specificity in 21 at-risk patients without IMI. U-dHRM showed promise as a separate or combination diagnostic approach to standard mycological tests. U-dHRMs speed, ability to simultaneously identify and quantify clinically relevant mold pathogens in polymicrobial samples, and detect emerging opportunistic pathogens may aid treatment decisions, improving patient outcomes. IMPORTANCE: Improvements in diagnostics for invasive mold infections are urgently needed. This work presents a new molecular detection approach that addresses technical and workflow challenges to provide fast pathogen detection, identification, and quantification that could inform treatment to improve patient outcomes.

Differential scanning fluorimetry (DSF) is a method to determine the apparent melting temperature (Tma) of a purified protein. In DSF, the raw unfolding curves from which Tma is calculated vary widely in shape and complexity. However, the tools available for calculating Tma are only compatible with the simplest of DSF curves, hindering many otherwise straightforward applications of the technology. To overcome this limitation, we designed new mathematical models for Tma calculation that accommodate common forms of variation in DSF curves, including the number of transitions, the presence of high initial signal, and temperature-dependent signal decay. When tested these models against DSFbase, an open-source database of 6235 raw, real-life DSF curves, these models outperformed the existing standard approaches of sigmoid fitting and maximum of the first derivative. To make these models accessible, we created an open-source software and website, DSFworld (https://gestwickilab.shinyapps.io/dsfworld/). In addition to these improved fitting capabilities, DSFworld also includes features that overcome the practical limitations of many analysis workflows, including automatic reformatting of raw data exported from common qPCR instruments, labeling of data based on experimental variables, and flexible interactive plotting. We hope that DSFworld will enable more streamlined and accurate calculation of Tma values for DSF experiments.

Nickel/bismuth (Ni/Bi) bilayers have recently attracted attention due to the occurrence of time-reversal symmetry breaking in the superconducting state. Here, we report on the structural, magnetic, and electric characterization of thin film Ni/Bi bilayers with several Bi thicknesses. We observed the formation of a complex layered structure depending on the Bi thickness caused by the inter-diffusion of Bi and Ni which leads to the stabilization of NiBi 3 at the Bi/Ni interface. The superconducting transition temperature and the transition width are highly dependent on the Bi thickness and the layer structure. Magnetoelectric transport measurements in perpendicular and parallel magnetic fields were used to investigate the temperature-dependent upper critical field within the framework of the anisotropic Ginzburg–Landau theory and the Werthamer–Helfand–Hohenberg model. For thicker samples, we observed a conventional behavior, similar to that shown by NiBi 3 bulk samples, including a small Maki parameter (α M = 0), no spin–orbit scattering (λ S O = 0) and nearly isotropic coherence length (γ = ξ ⊥ (0) / ξ ∥ (0) ≈ 1). The values obtained for these properties are close to those characterizing NiBi 3 single crystals. On the other hand, in very thin samples, the Maki parameter increases to about α M = 2.8. In addition, the coherence length becomes anisotropic (γ = 0.32) and spin–orbit scattering (λ S O = 1.2) must be taken into account. Our results unequivocally show that the properties characterizing the superconducting state in the Ni/Bi are strongly dependent on the sample thickness. [ABSTRACT FROM AUTHOR]

Temperature-dependent Raman spectral studies of BiFeO3 (BFO) films coated on three different substrates, viz., conducting Si (BFO-Si), sapphire (BFO-SAP), and fluorine-doped tin oxide (BFO-FTO), are reported between 123 and 773 K. The activity of Bi–O and Fe–O modes in these samples as a function of temperature shows different spectral features despite having synthesized from the same precursor. To understand the source of these variations, the spectra obtained on the above films were compared with those of bulk BiFeO3 (BFO-bulk) prepared via spark-plasma sintering. As the temperature increases, modes corresponding to the Bi–O activity at low frequency (120–180 cm−1) exhibit a redshift in their positions in all the samples. Between 350 and 550 K, BFO-SAP and BFO-Si samples show discernible anomalies in the positions of modes corresponding to the Fe–O activity (200–500 cm−1), which is not observed in the BFO-bulk and BFO-FTO samples. These anomalies are more pronounced for the modes between 350 and 500 cm−1, suggesting alterations in the Néel transition temperature (∼643 K for BiFeO3). Concurrently, another composite film of BiFeO3–CoFe2O4 coated on the Si substrate is explored. Raman studies on the composite film are used to compare and verify the influence of the substrate and defects on the magnetic ordering as a function of temperature. Our study highlights the significance and relevance of using Raman spectroscopy as a tool to discern various factors leading to local structural and magnetic variation in a given compound. [ABSTRACT FROM AUTHOR]

A thermally driven needle-like (NL) to distorted perovskite (DP) phase transition in SrZrS3 was investigated by means of ab initio free energy calculations accelerated by machine learning. As a first step, a systematic screening of the methods to include long-range interactions in semilocal density functional theory Perdew–Burke–Ernzerhof calculations was performed. Out of the ten correction schemes tested, the Tkatchenko–Scheffler method with iterative Hirshfeld partitioning method was found to yield the best match between calculated and experimental lattice geometries, while predicting the correct order of stability of NL and DP phases at zero temperature. This method was then used in free energy calculations, performed using several approaches, so as to determine the effect of various anharmonicity contributions, such as the anisotropic thermal lattice expansion or the thermally induced internal structure changes, on the phase transition temperature (TNP→DP). Accounting for the full anharmonicity by combining the NPT molecular dynamics data with thermodynamic integration with harmonic reference provided our best estimate of TNL→DP = 867 K. Although this result is ∼150 K lower than the experimental value, it still provides an improvement by nearly 300 K compared to the previous theoretical report by Koocher et al. [Inorg. Chem. 62, 11134–11141 (2023)]. [ABSTRACT FROM AUTHOR]

Antiferromagnetic spintronics is intrigued due to its unique properties that could break through the restrictions in ferromagnets. A 3d/5d transition metal oxide heterostructure is a good platform in antiferromagnetic spintronics research since the strong spin–orbit coupling in 5d oxides may bring about delicate interaction with the correlation energy and motivate unconventional phenomena. Here, the transport and magnetic characters of bilayers composed of antiferromagnetic 3d perovskite NdNiO3 and 5d perovskite SrIrO3 were investigated. The decreased metal–insulator transition and Néel temperature associated with suppressed negative magnetoresistance, emerged spin-glass like phenomenon, and the humped nonlinear Hall effect were observed in NdNiO3/SrIrO3 bilayers, which were absent in NdNiO3 and SrIrO3 pure films. It suggests the important role of interfacial interaction between NdNiO3 and SrIrO3 in modulating heterostructure transport and magnetic behavior and also manifests that complex magnetic structures might be realized in NdNiO3/SrIrO3 bilayers. [ABSTRACT FROM AUTHOR]

PbTiO 3 is a prototypical ferroelectric perovskite that is known to undergo a temperature driven ferroelectric tetragonal to paraelectric cubic phase transition, but the understanding of some key phenomena and associated mechanisms underlying this transition remains unclear. Here, using molecular dynamics simulations based on first-principles effective Hamiltonian, we show the behaviors of the phase transition temperature T c and adiabatic temperature change Δ T of PbTiO 3 under an external electric field and tensile stress along the [001] direction. Our results show that the electric field E induces rising T c via a linear relation T c ∝ 0.3083 E , rendering the phase transition to go from first-order with thermal hysteresis to second-order without thermal hysteresis above ∼ 200 kV/cm; meanwhile, a maximum electrocaloric response Δ T m a x ∼ 34 K is obtained under E = 500 kV/cm. Moreover, external stress (σ z) causes rising T c via a linear relation T c ∝ 160 σ z and improves the electrocaloric response Δ T m a x when combined with the electric field. The present results offer insights into the physical processes and mechanisms that dictate finite-temperature properties of ferroelectric perovskite oxides, laying a foundation for further exploration of this intriguing class of materials. [ABSTRACT FROM AUTHOR]

Carbon-doped Ge2Sb2Te5 (CGST) is a potential candidate in phase change random access memory (PCRAM) with superb thermal stability and ultrahigh cycle endurance. Direct observation of the microstructure evolution of CGST is desirable to uncover the phase transformation mechanism on the relationship of nucleation/crystalline behaviors of the crystalline phase at elevated temperatures and the pristine amorphous phase at room temperature. Here, we investigate the structural evolution of CGST using combined in situ techniques. Our in situ x-ray diffraction and ellipsometry results demonstrate that CGST exhibits a much higher phase transition temperature than undoped one. Temperature-dependent in situ transmission electron microscopy observations further reveal that carbon doping plays a critical role in tailoring the properties of GST by tuning the stochasticity of nucleation/crystallization, stabilizing amorphous and crystalline GST via isolating and refining the grain size at room temperature and elevated temperature. Our work provides detailed information for understanding the microscopic origin of crystallization kinetics of carbon-doped phase change materials toward high-performance PCRAM. [ABSTRACT FROM AUTHOR]

Sr2CoRuO6 in its bulk form shows spin glass behavior with a transition temperature of 95 K, and in its epitaxial thin film, it shows similar behavior with a transition temperature of 135 K. We have studied the structural, electronic, and magnetic properties of a polycrystalline thin film of oxygen-deficient Sr2CoRuO6−δ (SCRO), which shows ferrimagnetic or glassy behavior up to room temperature. The presence of oxygen deficiency causes multivalent cations Co3+ and Co2+ and Ru4+ and Ru5+, which introduces various kinds of magnetic interactions between Co3+–O–Co2+, Co3+–O–Ru4+, Co2+–O–Ru4+, Co3+–O–Ru5+, and Co2+–O–Ru5+ exchange paths, producing unusual exchange bias effects in the single layer thin film of SCRO. The interionic charge transfer between Co and Ru ions as a result of the negative charge transfer energy of the system helps in visualizing the unconventional exchange bias effect in the system. [ABSTRACT FROM AUTHOR]

Vanadium dioxide (VO2) is a highly attractive and multifunctional material for technological applications due to its metal–insulator transition, which is accompanied by several orders of magnitude changes in electrical resistivity and optical transmissivity. In this work, we report on the metal–insulator transition of VO2 nanoparticles which are produced by a simple, efficient, and low-cost two-step preparation method based on infrared laser irradiation of V2O5 powder dispersed in water and subsequent stoichiometric stabilization by vacuum annealing at 773 K. VO2 nanoparticles have an average size of 36 nm with facet-like contours and undergo a structural phase transition from a monoclinic to a tetragonal phase, accompanied by a metal–insulator transition occurring around 323 K, which is about 17 K lower than bulk VO2. No evidence of the formation of intermediary metastable phases is observed. Our findings reveal that the size of VO2 nanoparticles is a key parameter to moving the transition closer to room temperature, which is important for many applications. [ABSTRACT FROM AUTHOR]

The phase transition temperature and crystallization kinetics of phase-change materials (PCMs) are crucial characteristics for their performance, data retention, and reliability in memory devices. Herein, the crystallization behavior and kinetics of a compositionally optimized, N-doped Ge-rich Ge–Sb–Te alloy (GGST) in the slow crystallization regime are systematically investigated using synchrotron x-ray diffraction (XRD) in situ during heat treatment. Uniform thin films (50, 25, 10, and 5 nm) of initially amorphous N-doped GGST are investigated. The specimens were heated up to 450 °C at a rate of 2 °C/min to estimate crystallization onsets by quantifiying the crystallized quantity during material transformation from the XRD patterns. Subsequent isothermal anneals have been performed to assess crystallization behavior and activation energies. Nucleation-controlled crystallization that progresses in two steps is observed, together with the emergence of Ge preceding cubic Ge2Sb2Te5, with a mild dependence of crystallization temperature on film thickness that is inverse to what has been observed in other systems. Ge and GST crystallization may be described occurring in three-time stages: (i) an incubation period; (ii) a fast growth period; and (iii) a very slow-growth period. Very high activation energies (between 3.5 and 4.3 eV) for each phase are found for the incubation time t0. The activation energy for Ge in the fast growth regime is close to the one reported for the crystallization of pure Ge films. In the case of Ge, the incubation time is strongly thickness-dependent, which may have important consequences for the scaling of memories fabricated with this class of materials. [ABSTRACT FROM AUTHOR]

Determining the role of non-native interactions in folding dynamics, kinetics, and mechanisms is a classic problem in protein folding. More recently, this question has witnessed a renewed interest in light of the hypothesis that knotted proteins require the assistance of non-native interactions to fold efficiently. Here, we conduct extensive equilibrium and kinetic Monte Carlo simulations of a simple off-lattice C-alpha model to explore the role of non-native interactions in the thermodynamics and kinetics of three proteins embedding a trefoil knot in their native structure. We find that equilibrium knotted conformations are stabilized by non-native interactions that are non-local, and proximal to native ones, thus enhancing them. Additionally, non-native interactions increase the knotting frequency at high temperatures, and in partially folded conformations below the transition temperatures. Although non-native interactions clearly enhance the efficiency of transition from an unfolded conformation to a partially folded knotted one, they are not required to efficiently fold a knotted protein. Indeed, a native-centric interaction potential drives the most efficient folding transition, provided that the simulation temperature is well below the transition temperature of the considered model system. [ABSTRACT FROM AUTHOR]

Mixed valence manganites are potential functional materials due to their unique electromagnetic properties. In this work, half-doped ceramics with the perovskite structure Sm 0.5 Ca 0.5 MnO 3 polycrystalline samples are synthesized by the solid-state reaction method in open air at different final sintering temperatures. Structures and particle sizes are studied by x-ray diffraction and scanning electron microscopy, respectively. Positron annihilation spectroscopy and density-functional theory calculations are used to characterize the intrinsic vacancies in the bulk. Thereafter, the effect of vacancies on the magnetic and magnetoresistance (MR) properties is investigated. We find that Mn monovacancies (V Mn ) exist in the bulk among all the samples, and the concentration of V Mn is different. We suggest a possible defect model that can be well applied to explain the phenomena of their electromagnetic properties. The transition temperature of the charge-order state (T CO ) and ferromagnetic and anti-ferromagnetic (T N ) are most likely related to the concentration of V Mn and the particle sizes or pore sizes, respectively. The glass spin state transition temperature seems to be independent of the defect concentration and type. The metal conductive behavior does not appear in a high magnetic field and at low temperatures, which may be caused by the presence of a high concentration of V Mn in the bulk and oxygen-related defects in the boundary, and the double exchange interaction is suppressed. At temperatures below T N and under a weak magnetic field, the MR is related to the total defect concentration. In addition, the high concentration of V Mn is unfavorable for obtaining a high MR value. [ABSTRACT FROM AUTHOR]

All-proportional solid solutions of the metal-free perovskite (H2dabco1−y, H2hmtay)(NH4)(BF4)3 ((d,h)-BF4) were crystallized via a mechanochemical method. Their molecular dynamics depend on the ratio y with a compositional boundary at y = 0.43, where H2dabco2+ was deduced to be at a dynamic disorder state, even below phase transition temperature to a plastic crystalline phase seen at y = 0. [ABSTRACT FROM AUTHOR]

Topological antiferromagnetic Mn3Sn crystals exhibit notable magnetic and transport properties, comparable to ferromagnets, and undergo various intriguing magnetic phase transitions during heating or cooling. The spin structures of Mn3Sn crystals are highly influenced by growth conditions and the stoichiometric ratio of Mn and Sn, which in turn affect the phase transition temperature and the transport signatures. In this work, we employed the flux method, carefully controlling factors such as melting temperature, cooling rate, sampling temperature, vacuum, and composition, and fabricated Mn2.991Sn1.009 bulk single crystals successfully. The size of the resulting single crystal after cutting is 6 × 5 × 3 mm3. The microstructure, magnetic and transport properties of the prepared single crystals were characterized parallel to and perpendicular to the z-axis. A strong and a weak magnetic phase transition were observed at 200 K and 280 K, respectively. Our results indicate that the magnetic phase transition of Mn3Sn crystals at 200 K involves a switch in the easy-axis of magnetization from in-plane to out-of-plane, corresponding to the anomalous Hall resistance peak at 200 K. These results show a clear correlation between the spin structure and Berry curvature in Mn3Sn crystals, which significantly affect the magnitude of the anomalous Hall effect. [ABSTRACT FROM AUTHOR]

A new three-step sintering process was presented to produce 0.96(K 0.5 Na 0.5) 0.95 Li 0.05 Nb 0.93 Sb 0.07 O 3 –0.04CaZrO 3 piezoelectric ceramics, this method sets the sintering temperature and holding time for each step based on the traditional solid-state sintering method of the system. Phase structure and polymorphic phase transition temperature were investigated. All of the ceramic samples indicated a perovskite structure, and most of them showed the coexistence of orthogonal and tetragonal phases, according to X-ray diffraction patterns. The dielectric low-temperature spectrum and thermally stimulated depolarization current (TSDC) revealed that the orthogonal-tetragonal phase transition temperature of all ceramics was set below ambient temperature. The crystal structure of the ceramics was changed using the three-step sintering process, which lowered the polycrystalline transformation temperature below room temperature, resulting in excellent piezoelectric properties of the ceramic material. [ABSTRACT FROM AUTHOR]

All-proportional solid solutions of the metal-free perovskite (H2dabco1−y, H2hmtay)(NH4)(BF4)3 ((d,h)-BF4) were crystallized via a mechanochemical method. Their molecular dynamics depend on the ratio y with a compositional boundary at y = 0.43, where H2dabco2+ was deduced to be at a dynamic disorder state, even below phase transition temperature to a plastic crystalline phase seen at y = 0. [ABSTRACT FROM AUTHOR]

Small-scale pumps for controlling microfluidics have promising applications in drug delivery and chemical assays. Liquid metal (LM) demonstrates excellent flow pumping performance due to its simple structure and the electrocapillary effect under an electric field. However, LM droplets risk escaping from constrained structures, which can lead to pump failure. Temperature regulation is also a critical parameter in optimizing chemical reactions in fluidic systems, however, integrating it into a compact system remains challenging. Here, we develop a temperature-triggered gallium-based actuator (TTGA) by introducing a gallium (Ga) droplet wetted on a copper (Cu) plate as the core element for flow actuation. The Cu plate prevents the Ga droplet from escaping the chamber and significantly increases the flow rate. By leveraging the electrochemical method to inhibit the supercooling effect of Ga, the TTGA enables activation/deactivation for flow actuation at different temperatures. We investigate the impact of electrode position, solution concentration, and applied voltage on TTGA’s pumping efficiency. By dynamically tuning the Ga droplet’s temperature to control phase transition, TTGA allows for accurate flow actuation control. Furthermore, placing Ga and eutectic Ga-indium (EGaIn) droplets in different channels enables the expected flow divergence for fluids with different temperatures. The development of TTGA presents new opportunities in microfluidics and biomedical treatment. [ABSTRACT FROM AUTHOR]

This study explores the morphological and structural transformation of boehmite (AlOOH) into transition aluminas during calcination, a pathway crucial for diverse industrial applications. The primary focus is on the topotactic transformation of boehmite into γ‐Al2O3 and its subsequent transitions into higher temperature polymorphs, culminating in α‐Al2O3. Utilizing a combination of in situ X‐ray diffraction, in situ and ex situ transmission electron microscopy, 27Al solid‐state nuclear magnetic resonance, thermogravimetric analysis, nitrogen physisorption, and mercury porosimetry, this work provides insights into the morphological and structural reordering during the calcination process. Furthermore, the study highlights the significant impact of thermal processing on the morphological evolution of boehmite and transition aluminas, characterized by changes in pore structure sizes and shapes. These findings offer valuable insights for optimizing the properties of alumina‐based materials for specific applications. [ABSTRACT FROM AUTHOR]

In this study, we investigate the impact of Cr substitution on the structural, magnetic, impedance, and ac conductivity characteristics of polycrystalline single-phase D y 3 F e 5 - x C r x O 12 x = 0.0 - 0.5 (C r - D y I G) samples. Our findings reveal a reduction in lattice constant values with the increase in Cr concentration and it is attributed to the smaller ionic radii of C r 3 + in comparison to F e 3 + ions. Consecutively, the ferrimagnetic transition temperature (T c) decreases from 549 to 509 K as x varies from 0.0 to 0.5 . The low-temperature magnetization passes through magnetic compensation (T comp) and spin-reorientation transition (T SR) that arises due to the exchange interactions between rare earth ions and F e 3 + moments. Moreover, the substitution of Cr has enhanced the room temperature saturation magnetization of the base material from 3.33 emu / g to 8.92 emu / g . Further, Nyquist plots were analyzed to assess contributions from grains, grain boundaries, and electrodes, while Mott's Variable Range Hopping model was applied to relaxation dynamics to determine hopping length and energies. Also, analysis of ac conductivity using Jonscher's Power Law reveals that the parent sample primarily exhibits large polaron hopping, while Cr -doped samples show small polaron hopping as the main mode of electrical conduction. [ABSTRACT FROM AUTHOR]

The low alloy bainitic steel used in reactor pressure vessels deteriorates during thermal service while the macroscopic thermodynamic parameters that cause thermal aging remains unknown. In this work, a thermal aging restructuring scheme was proposed by step-up aging the steel from 350 °C to 490 °C, with a total duration of 7500 hours. Samples from varied thickness of the steel were characterized in terms of carbides evolution and Charpy impact toughness at 20 °C. The carbide size and its fraction were statistically analyzed showing partial coarsening and dissolution during aging, while the carbide fraction was found linearly correlated with the impact energy for the first time. The critical transition temperature parameter of the aging process was found to be 470 °C for the steel. The macroscopic thermodynamic parameters, including the thermal aging time and temperature, facilitate a comprehensive understanding of the material degradation mechanism and provide a basis for long-term safety of equipment. [ABSTRACT FROM AUTHOR]

Motor systems operate over a range of frequencies and relative timing (phase). We studied the role of the hyperpolarization-activated inward current (Ih) in regulating these features in the pyloric rhythm of the stomatogastric ganglion (STG) of the crab, Cancer borealis, as temperature was altered from 11°C to 21°C. Under control conditions, rhythm frequency increased monotonically with temperature, while the phases of the pyloric dilator (PD), lateral pyloric (LP), and pyloric (PY) neurons remained constant. Blocking Ih with cesium (Cs+) phase advanced PD offset, LP onset, and LP offset at 11°C, and the latter two further advanced as temperature increased. In Cs+ the frequency increase with temperature diminished and the Q10 of the frequency dropped from ~1.75 to ~1.35. Unexpectedly in Cs+, the frequency dynamics became non-monotonic during temperature transitions; frequency initially dropped as temperature increased, then rose once temperature stabilized, creating a characteristic 'jag'. Interestingly, these jags persisted during temperature transitions in Cs+ when the pacemaker was isolated by picrotoxin, although the temperature-induced change in frequency recovered to control levels. Overall, these data suggest that Ih plays an important role in maintaining smooth transitory responses and persistent frequency increases by different mechanisms in the pyloric circuitry during temperature fluctuations. [ABSTRACT FROM AUTHOR]

In this work, two binary carbon-based composite phase change materials consisting of paraffin (PW), lauric acid (LA) and tetradecanol (TD) were prepared. Delignified wood flour (DWF) was obtained through treatment with a mixture of NaOH and Na2SO3. The pore volumes of DWF and wood flour (WF) are 0.01049 and 0.008955 cm3/g, respectively, and the pore volume of DWF increased by 17.16%. The adsorption capacity of DWF for LA-PW and LA-TD reaches 50%, which is 10% higher than the adsorption capacity of WF for LA-PW and LA-TD. The thermal conductivities of LA-PW/DWF and LA-TD/DWF are 0.3762 and 0.3580 W/m k, respectively. The phase transition temperatures of LA-PW/DWF and LA-TD/DWF are 40.86 ℃ and 19.68 ℃, respectively. The phase transition latent heat for LA-PW/DWF and LA-TD/DWF is 88.86 J/g and 62.31 J/g, which are 33.61% and 26.18% higher than those of LA-PW/WF and LA-TD/WF, respectively. After 200 cycles, the maximum value of the change rate in phase transition temperature for LA-PW/DWF and LA-TD/DWF is less than 2.64%, and the peak shape remains consistent before and after the cycle, which have good thermal stability. The adsorption capacity of DWF obtained by alkali delignification of wood flour was enhanced. LA-PW and LA-TD were uniformly adsorbed in the pore structure of DWF by capillary force and surface tension. LA-PW/DWF and LA-TD/DWF have high phase transition latent heat and good thermal and stability. [ABSTRACT FROM AUTHOR]

In this paper, during the heat treatment of TC4 titanium alloy pulsed laser-arc hybrid welded joints, it was found that the degree of V elemental segregation in the β phase of the weld microstructure increased with the slowing down of the cooling rate after holding the weld joint for a certain period above the β phase transition temperature. To reveal the effect of V element segregation in the β phase on the mechanical properties, tensile simulations were carried out using molecular dynamics at different temperatures for different degrees of segregation in the model. The results showed that at the same temperature, when the V elements were segregated in the β phase, the energies of the models were all lower than that of the model with uniform distribution of V elements after relaxation. At the same time, the tensile strengths were all higher than that of the model with a uniform distribution, and the tensile strengths in the x- and y-directions were increased by 17.7% and 8.1%, respectively. In stretching to the maximum stress, the deformation mainly occurred in the β phase, and the deformation mode was a phase transition from BCC to HCP with the formation of nanocrystalline. However, with the increase in temperature and the decrease of the degree of V elemental segregation, the nanocrystalline formed by the deformation gradually decreased, and the grain boundaries also became irregular, which was the main reason for the decrease in the tensile strength. At the same time, after segregation, the start of the BCC phase transition in the tensile process was delayed, which was also beneficial to improving the strength of the model. After exceeding the tensile strength, the deformation was mainly dominated by the slip of dislocations. In addition, with the increase of the degree of V element segregation, the difference in the tensile strength of the model tensile along the parallel and perpendicular grain boundary directions decreased from 0.48 to 0.18 GPa, and the anisotropy of the material was weakened. [ABSTRACT FROM AUTHOR]

Titanium dioxide-enriched phosphate glasses are esteemed for their applicability in the biomaterial area, yet the investigation into the influence of TiO 2 on the crystallization dynamics of glass melts and the spinnability of sodium-calcium-magnesium phosphate glasses remains unclear. To elucidate these effects, sodium-calcium-magnesium phosphate glasses with 0, 5, and 10 mol% of TiO 2 have been prepared using the melt-quenching method, and glass fibers were drawn from the correspondent glass melts. FTIR and Raman spectroscopy have disclosed that the introduction of TiO 2 induces a depolymerization in phosphate network, causing a transition from Q2 species to Q1 units, and reduction in both the theoretical network connectivity (NC theor) and the average chain length (n theor). Meanwhile, the interposition of TiO 2 also gives rise to the replacement of P–O–P linkages with P–O–Ti bonds, along with the formation of [TiO 5 ] groups. This structural transformation resulted in the increase in molar volume and the coefficient of thermal expansion (CTE), concurrently lowering the glass transition and softening points. Evidently, the TiO 2 -free glass exhibited crystallization across a temperature range spanning from its transition to the liquidus temperature. However, the introduction of TiO 2 and the subsequent formation of P–O–Ti bonds effectively inhibited crystallization, which is favorable for drawing glass fibers. Analyses of viscosity-temperature relationships using various rheological models suggested that TiO 2 raises fragility for all glasses, suggesting a more "open" structure in the glass melts, which can be supported by the increment in free volume. The m-D diagram failed to describe the enhancement in spinnability imparted from TiO 2. While, the quantitative fiber spinnability index (K fib) increases with higher TiO 2 content, as a successful indicative of an improved ability to form fibers. [ABSTRACT FROM AUTHOR]

Herein, in order to successfully create high-density La 0.67 Ca 0.33- x Sr x MnO 3 : Ag 0.15 (LCSMO: Ag) ceramics (0 ≤ x ≤ 0.05), this research combines sol-gel and solid-phase processes. LCSMO: Ag ceramics electrical transport and magnetic properties were thoroughly investigated. XRD verified that the high-purity orthorhombic perovskite structure (space group Pnma) was produced. As Sr doping rises, the grain size grows, the single electron bandwidth increases, the metal-insulator transition temperature (T MI) continues to climb, and temperature coefficient of resistance (TCR) and magnetoresistance (MR) steadily drop. When x = 0.04, the T MI reaches 302.2 K. At this time, the TCR peak (TCR peak) reaches 24.0 %·K−1 and the MR peak reaches 49.2 %. These results demonstrate that Sr may effectively raise the T MI of LCMO: Ag ceramics to room temperature while maintaining high TCR and MR Values, which benefits the material's potential applications in devices such as uncooled infrared detectors. [ABSTRACT FROM AUTHOR]

Smart microgels can be used as sorbents, possessing high surface area and rapid stimuli‐responsiveness. A series of poly(N‐isopropylacrylamide) (pNIPAM) and pNIPAM‐co‐starch nanoparticles (pNIPAM‐co‐SNPs) thermo‐responsive microgels were synthesized, presenting different hydrophilic/hydrophobic behavior according to the composition. The adsorption studies were carried out for methylparaben (MPB), ethylparaben (EPB), propylparaben (PPB), butylparaben (BPB), and bisphenol A (BPA), and the extraction and desorption efficiency were determined by high‐performance liquid chromatography and spectrophotometric detection (HPLC‐UV). The effect of microgel phase transition according to the temperature and the copolymerization with SNPs in each sorptive step was investigated. The extraction of less polar compounds (BPA, PPB, and BPB) above the volume phase transition temperature (VPTT) was favored, driven by a predominant hydrophobic interaction. According to microgel composition, the desorption capacity as a function of temperature can be influenced by hydrophilic interactions and water competition. Molecular dynamics (MD) simulations and binding free energy calculations were performed to provide theoretical evidence about binding energies between pNIPAM and BPA, which experimentally showed the best extraction efficiency results. These findings may provide a strategy for designing high‐performance sorptive phases that could remove hydrophilic and hydrophobic compounds from water and a hypothesis about the driving forces of such processes. [ABSTRACT FROM AUTHOR]

Shape memory polymers (SMPs) have been extensively investigated because of their wide range of biomedical and robot applications. In most of SMPs, only one temporary shape can be formed and recovered through the mechanism of melting or glass transition. Herein, a multiple shape memory effect (mSME), i.e., formation of at least two temporary shapes, can be realized in polyvinylidene fluoride (PVDF)‐based ferroelectric polymers by exploiting their expanded ferroelectric–paraelectric (F‐P) phase transition temperature range. Although P(VDF‐TrFE) (TrFE: trifluoroethylene) (55/45) copolymer is thought to be a normal ferroelectric, its ferroelectric phase transforms into a paraelectric phase through an intermediate relaxor ferroelectric‐like state and mSME is observed in this extended phase transition temperature range. By incorporating CTFE (chlorotrifluoroethylene) into P(VDF‐TrFE), P(VDF‐TrFE‐CTFE) becomes a relaxor ferroelectric with a further extended phase transition temperature range. The terpolymer exhibits improved mSME and at least three temporary shapes can be formed and recovered. A comparison of SME and structures of several PVDF‐based copolymer and terpolymers suggests that the amount of polar phase is a critical factor affecting the SME. This study not only demonstrates mSME in ferroelectric polymers, which expands their application potential, but also provides an in‐depth understanding of the shape memory mechanism of the polymers. [ABSTRACT FROM AUTHOR]

While recent experiments confirm the existence of hundreds of topological electronic materials, only a few exhibit the coexistence of superconductivity (SC) and a topological electronic state. These compounds attract significant attention in forefront research because of the potential for the existence of topological SC, paving the way for future technological advancements. SrSn4 is known for exhibiting unusual SC below the transition temperature (TC) of 4.8 K. Recent theory predicts a topological electronic state in this compound, which is yet to be confirmed by experiments. Systematic and detailed studies of the magnetotransport properties of SrSn4 and its Fermi surface characterizations are also absent. For the first time, a quantum oscillation study reveals a nontrivial 흅‐Berry phase, very light effective mass, and high quantum mobility of charge carriers in SrSn4. Magnetotransport experiment unveils large linear transverse magnetoresistance (TMR) of more than 1200% at 5 K and 14 T. Angle‐dependent transport experiments detect anisotropic and fourfold symmetric TMR, with the maximum value (≈2000%) occurring when the angle between the magnetic field and the crystallographic b‐axis is 45°. The results suggest that SrSn4 is the first topological material with SC above the boiling point of helium that displays such high magnetoresistance. [ABSTRACT FROM AUTHOR]

We have used high‐pressure methods to synthesize CaMnTi2O6 single crystals with edge lengths of up to 70 μm. Compared to previously reported synthetic pathways, we were able to use gold capsules and smaller pressures of 4 GPa. X‐ray diffraction analysis of the single crystals at low temperatures between 100 and 230 K confirmed that no phase transitions occur in this temperature range. We found square planar‐coordinated Mn ions to shift further out of the plane with lower temperatures which could lead to a higher polarization. The measured Raman spectrum of CaMnTi2O6 has been compared with quantum chemically calculated Raman spectrum to assign the vibrational modes. Calculated single‐crystal Raman spectrum has also been also analyzed from the point of view of direction dependency of the Raman intensities. [ABSTRACT FROM AUTHOR]

We have used high‐pressure methods to synthesize CaMnTi2O6 single crystals with edge lengths of up to 70 μm. Compared to previously reported synthetic pathways, we were able to use gold capsules and smaller pressures of 4 GPa. X‐ray diffraction analysis of the single crystals at low temperatures between 100 and 230 K confirmed that no phase transitions occur in this temperature range. We found square planar‐coordinated Mn ions to shift further out of the plane with lower temperatures which could lead to a higher polarization. The measured Raman spectrum of CaMnTi2O6 has been compared with quantum chemically calculated Raman spectrum to assign the vibrational modes. Calculated single‐crystal Raman spectrum has also been also analyzed from the point of view of direction dependency of the Raman intensities. [ABSTRACT FROM AUTHOR]

Multiferroic materials can realize the mutual coupling between force, electricity, magnetism and other physical fields, and have important application prospects in the field of small size, fast response and low power consumption of magnetoelectric devices. GaFeO3 is a highly promising multiferroic material featuring high spontaneous magnetization and polarization beyond room temperature. In this study, Ferroelectric Mgx Ga1 - x FeO3 (x = 0. 02, 0. 05, 0. 07 and 0. 10) single crystals with a diameter of about 7 mm were grown by light floating zone method. The effect of Mg2 + on the saturation magnetization and magnetic transition temperature of GaFeO3 (GFO) crystals were studied. The structure and phase of the crystal were analyzed through XRD, the results show that all the prepared samples correspond to the diffraction characteristics of the standard crystal card library GFO (PDF#76-1005), and no other heterophase appears. The XRD refinement results indicate that, the crystal structure is orthogonal and its space group is Pna21. As the concentration of Mg2 + rises, the lattice constant and cell volume initially increase and subsequently decrease. Additionlly, the magnetic properties of the crystal were studied through a comprehensive physical property measurement system, the magnetic transition temperature and saturation magnetization of the grown crytals also increase firstly and then decrease with the increase of Mg2 + doping content. When the Mg2 + doping amount is 0. 07, the magnetic transition temperature and saturation magnetization reach the maximum values of 187. 82 K and 8. 75 emu/g, respectively, which achieves the purpose of doping modification. [ABSTRACT FROM AUTHOR]

Uninterrupted breakthroughs in the room temperature piezoelectric properties of KNN-based piezoceramics have been witnessed over the past two decades; however, poor temperature stability presents a major challenge for KNN-based piezoelectric ceramics in their effort to replace their lead-based counterparts. Herein, to enhance temperature stability in KNN-based ceramics while preserving the high piezoelectric response, multilayer composite ceramics were fabricated using textured thick films with distinct polymorphic phase transition temperatures. The results demonstrated that the composite ceramics exhibited both outstanding piezoelectric performance (d33~467 ± 16 pC/N; S~0.17% at 40 kV/cm) and excellent temperature stability with d33 and strain variations of 9.1% and 2.9%, respectively, over a broad temperature range of 25–180 °C. This superior piezoelectric temperature stability is attributed to the inter-inhibitive piezoelectric fluctuations between the component layers, the diffused phase transition, and the stable phase structure with a rising temperature, as well as the permanent contribution of crystal orientation to piezoelectric performance over the studied temperature range. This novel strategy, which addresses the piezoelectric and strain temperature sensitivity while maintaining high performance, is well-positioned to advance the commercial application of KNN-based lead-free piezoelectric ceramics. [ABSTRACT FROM AUTHOR]

Ferroelastic materials with high phase transition temperature have broad application prospects in information conversion and storage, shape memory, energy conversion, hyperelasticity, etc. However, most of the current reports focus on inorganic ferroelastic materials. Inorganic ferroelastic materials have the disadvantages of high energy consumption and harmful metals, which limit their application in practical work. In contrast, organic ferroelastic materials have the advantages of structural adjustability, environmental protection, easy processing, low cost, mechanical flexibility, and so on, which have great development potential in new ferroelastic materials. Here, we have successfully designed and synthesized a pair of homochiral enantiomers [(R/S)‐4‐fluorobenzoic acid‐2‐amino‐2‐phenylethanol] (R‐ and S‐F) using the chemical design strategy of H/F substitution. Compared with the non‐F substitution [(R/S)‐benzoic acid‐2‐amino‐2‐phenylethanol] (R‐ and S‐H), they undergo 2F1‐type ferroelastic phase transitions at 370 K. Notably, the ferroelastic domains of R/S‐F can be controlled through two physical channels that are temperature and stress, showing great potential in dual‐channel switches. [ABSTRACT FROM AUTHOR]

A comparative specific heat (C P ) study of GdPdAl and TbPdAl compounds crystallizing in hexagonal ZrNiAl-type crystal-structure (space group P 6 ¯ 2 m) is presented. Consistent with earlier reports both the compounds show the signature of two magnetic transitions in magnetization data. The magnitude of the jump in C P at the high-temperature transition at T N 1 (∼ 47 K) in GdPdAl indicates ordering into an amplitude-modulated magnetic structure. The analysis of magnetic entropy change (S 4 f ) showed that about one-half of total S 4 f occurs below low temperature transition at T N 2 . This is in contrast to that seen in TbPdAl, where only one-third of the entropy of transition occurs below T N 2 . For both the compounds S 4 f tends to saturate to about 84% (for T > T N 1 ) of that expected for complete ordering of the rare earth moments, indicating incomplete removal of geometrical frustration. [ABSTRACT FROM AUTHOR]

The critical behavior and the magnetocaloric effect have been researched in rare-earth perovskite EuTiO 3 . Using classical Monte Carlo method, we simulate the phase transition behavior of EuTiO 3 on the Heisenberg model with uniaxial anisotropy and obtain the phase transition temperature T n = 5.4 K, which is almost consistent with the experimental results. The entropy change under isothermal Δ S and temperature change under adiabatic Δ T ad are calculated for different external magnetic fields. The results of the relative cooling power (RCP) are linear with the magnetic field. The critical exponents β =0.269, γ =1.250, and δ =5.602 are obtained by the power laws. These results are almost identical to those calculated using the MCE scaling law. [ABSTRACT FROM AUTHOR]

77 Se NMR measurements confirm that in Fe(Se,Te) a change in the type of nematic transition is observed near its complete suppression. We present the studies of structural phase transitions in FeSe 0.675 Te 0.3 S 0.025 crystals. The data obtained indicate a significant change in the behavior of many characteristics during the transition in this composition compared to the case of the unsubstituted FeSe. Similar to Fe(Se,Te) with a close tellurium content, the resistivity at low temperatures for the studied FeSe 0.675 Te 0.3 S 0.025 is proportional to the square of the temperature, while for pure FeSe below the structural transition it depends almost linearly on temperature. 77 Se NMR proves that these changes are associated with changes in the type of ordering. The NMR data showed a noticeable line broadening below the structural transition and an anomaly in the temperature dependence of the relaxation rate, which was not observed in FeSe. Our results confirm existence of the nematicity change point (NCP) in Fe(Se,Te) at a low Te content and make the phase diagram of quasi-binary Fe(Se,Te) compounds generally consistent with the phase diagram of FeSe under pressure. Thus, in terms of chemical pressure, the effect of isovalent substitution in the series of Fe(Te,Se,S) compounds on the type of ordering can be caused by the anisotropic part of the deformation. [ABSTRACT FROM AUTHOR]

This attempt covers an investigation of cutting temperature at interfaces of Fiber Metal Laminates (FMLs) made of glass fiber-reinforced polymer (GFRP) stacked with an Al2020 alloy. GFRP/Al/GFRP and Al/GFRP/Al composite stacks are both investigated to highlight the effect of stacking arrangement on thermal behavior within the interfaces. In a first test series, temperature history is recorded within the metal/composite stack interfaces using preinstalled thermocouples. In a second test series, a wireless telemetry system connected to K-type thermocouples implanted adjacent to the cutting edge of the solid carbide drill is used to record temperature evolution at the tool tip. Focus is put on the effects of cutting speed and stacking arrangement on the thrust force, drilling temperature, and delamination. From findings, the temperature histories show high sensitivity to the cutting speed. When cutting Al/GFRP/Al, the peak temperature is found to be much higher than that recorded in GFRP/Al/GFRP and exceeds the glass transition point of the GFRP matrix under critical cutting speeds. However, thrust force obtained at constitutive phases exhibits close magnitude when the stacking arrangement varies, regardless of cutting speed. Damage analysis is also discussed through the delamination factor at different stages of FML thickness. [ABSTRACT FROM AUTHOR]