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Hg-based compounds show abundant structural diversity and distinguished properties. Herein, a new phase transition compound CsHg2I5 was reported. The high-temperature phase β-CsHg2I5 with rare [Hg2I5] dimers was synthesized by the flux method at 573 K, and it shows a reversible phase transition at a low temperature of ∼100 K to form the low-temperature phase α-CsHg2I5. The two phases crystallize in the same P21/c space group, with different crystal structures. β-CsHg2I5 is composed of rare [Hg2I5] dimers and [CsI11] polyhedral units, while α-CsHg2I5 is composed of [Hg4I11] and [CsI10] units. The experimental band gap of β-CsHg2I5 was found to be 2.58 eV. Owing to the presence of [Hg2I5]∞ pseudo-layers, β-CsHg2I5 exhibits large optical anisotropy with a calculated birefringence of 0.132@1064 nm. Meanwhile, β-CsHg2I5 is a congruent compound and the congruent point is ∼481 K. Theoretical calculations indicate that the rare [Hg2I5] dimer is a nonlinear active unit, which can be used as a new fundamental building block for the design of advanced nonlinear optical materials. Moreover, a CsI–HgI2 pseudo-binary diagram was drawn. The results enrich the structural diversity of Hg-based halides and give some insights into the development of new functional materials based on rare [Hg2I5] dimers. [ABSTRACT FROM AUTHOR]

Flexible multiplexing chips that permit reconfigurable multidimensional channel utilization are indispensable for revolutionary 6G terahertz communications, but the insufficient manipulation capability of terahertz waves prevents their practical implementation. Herein, we propose the first experimental demonstration of a flexible multiplexing chip for terahertz communication by revealing the unique mechanism of topological phase (TP) transition and perseveration in a heterogeneously coupled bilayer valley Hall topological photonic system. The synthetic and individual TPs operated in the coupled and decoupled states enable controllable on-chip modular TP transitions and subchannel switching. Two time-frequency interleaved subchannels support 10- and 12-Gbit/s QAM-16 high-speed data streams along corresponding paths over carriers of 120 and 130 GHz with 2.5- and 3-GHz bandwidths, respectively. This work unlocks interlayer heterogeneous TPs for inspiring ingenious on-chip terahertz-wave regulation, allowing functionality-reconfigurable, compactly integrated and CMOS-compatible chips. [ABSTRACT FROM AUTHOR]

This research investigates the energy efficiency of a novel double-glazing system incorporating solid–solid phase change materials (SSPCMs), which offer significant advantages over traditional liquid–solid phase change materials. The primary objective of this study is to develop a 3D numerical model using the finite volume method, which will be followed by a parametric study under real climatic boundary conditions. A proposed double-glazing setup featuring a 2 mm layer of SSPCM applied on the inner glass pane within the air gap is modeled and analyzed. The simulations consider various transient temperatures and ranges of the SSPCM to evaluate the energy performance of the system under different weather conditions of Miami, FL during the coldest and hottest days of the year, both in sunny and cloudy conditions. The results demonstrate a notable improvement in energy performance compared to standard double-glazing windows (DGWs), with the most efficient SSPCM configuration exhibiting a phase transition temperature and range of 25 °C and 1 °C, respectively. This configuration achieved energy savings of 24%, 26%, and 23% during summer sunny, winter sunny, and winter cloudy days, respectively, relative to DGWs during cooling and heating degree hours. However, a 3% energy loss was observed during summer cloudy days. Overall, the findings of this study have shown the potential for energy savings by incorporating SSPCM with suitable thermophysical properties into double-glazing systems. [ABSTRACT FROM AUTHOR]

Mechanochromic photonic crystals are attractive due to their force-dependent structural colors; however, showing unrecordable color and unsatisfied performances, which significantly limits their development and expansion toward advanced applications. Here, a thermal-responsive mechanochromic photonic crystal with a multicolor recordability-erasability was fabricated by combining non-close-packing mechanochromic photonic crystals and phase-change materials. Multicolor recordability is realized by pressing thermal-responsive mechanochromic photonic crystals to obtain target colors over the phase-change temperature followed by fixing the target colors and deformed configuration at room temperature. The stable recorded color can be erased and reconfigured by simply heating and similar color-recording procedures respectively due to the thermoswitchable on-off mechanochromism of thermal-responsive mechanochromic photonic crystals along with solid-gel phase transition. These thermal-responsive mechanochromic photonic crystals are ideal rewritable papers for ink-freely achieving multicolor patterns with high resolution, difficult for conventional photonic papers. This work offers a perspective for designing color-recordable/erasable and other stimulus-switchable materials with advanced applications. Mechanochromic photonic crystals are extremely attractive due to their force-dependent structural colors yet are limited by unrecordable color and unsatisfactory performances. Here, the authors report a thermal-responsive mechanochromic photonic crystal with multicolor recordability-erasability. [ABSTRACT FROM AUTHOR]

Resistive random‐access memory (RRAM) is considered the next‐generation nonvolatile memory owing to its simplicity, low power consumption, and high storage density. Resistive switching (RS) occurs in a wide range of materials among the transition metal oxides. Herein, an epitaxial ternary metal oxide layer, LaCoOx (LCO), grown on Nb‐doped SrTiO3 substrates, is utilized as an RRAM device. When voltage is applied, it exhibits excellent RS behavior. More than 900 cycles are obtained, and the retention time reaches up to 104 s. To investigate the RS behavior, high‐resolution transmission electron microscopy and atomic‐scale scanning transmission electron microscopy are used to observe the structural evolution and oxygen ion migration in LCO. The structure exhibits a perovskite–brownmillerite topotactic phase transformation from LaCoO2.5 or LaCoO2.67 to the LaCoO3 conductive regions. The reversible transition between the low‐resistance states and high‐resistance states enables the RS mechanism. Additionally, the valence states are confirmed using high‐resolution X‐ray photoelectron spectroscopy. This study not only illustrates the oxygen‐ion migration mechanism of LCO but also demonstrates its suitability for RRAM applications. [ABSTRACT FROM AUTHOR]

Davemaoite, that is, CaSiO3 perovskite (CaPv), is the third most abundant phase in the lower mantle and exhibits a tetragonal‐cubic phase transition at high pressures and temperatures. The phase boundary in CaPv has recently been proposed to be close to the cold slab adiabat and cause mid‐mantle seismic wave speed anomalies (Thomson et al., 2019, https://doi.org/10.1038/s41586‐019‐1483‐x). This study utilized accurate deep‐learning‐based simulations and thermodynamic integration techniques to compute free energies at temperatures ranging from 300 to 3,000 K and pressures up to 130 GPa. Our results indicate that CaPv exhibits a single cubic phase throughout lower‐mantle conditions. This suggests that the phase diagram proposed by Thomson et al. requires revision, and mid‐mantle seismic anomalies are likely attributable to other mechanisms. Plain Language Summary: Davemaoite, also known as calcium silicate perovskite (CaPv), is one of the most abundant minerals in Earth's lower mantle. It can exist in tetragonal and cubic crystal structures, depending on the pressure and temperature conditions. Determining the crystalline phase of CaPv is important for interpreting seismic observations of the lower mantle. A recent study (Thomson et al., 2019, https://doi.org/10.1038/s41586‐019‐1483‐x) suggested that CaPv's tetragonal‐to‐cubic transition could cause mid‐mantle seismic anomalies. However, this phase transition has been a topic of debate. Previous studies have attempted to determine the phase boundary using ab initio methods. The computational cost and challenges associated with handling strong anharmonicity limited these approaches' accuracy and predictive power. In this study, we utilized deep learning and thermodynamic integration techniques to accurately compute the tetragonal to cubic phase boundary of CaPv across the lower mantle pressure range. Our results satisfactorily explain previous experimental measurements and support the notion that CaPv remains in the cubic phase across lower mantle conditions. These findings challenge the previously proposed phase diagram by Thomson et al. and suggest that mid‐mantle seismic scatterers/reflectors or large low‐shear‐velocity provinces in the lower mantle cannot be attributed to this transition in CaPv. Key Points: A deep‐learning potential is developed to accurately determine CaSiO3 perovskite (CaPv)'s tetragonal‐to‐cubic phase boundary under lower‐mantle conditionsCaPv should exhibit solely a cubic phase throughout the entire lower mantleThe tetragonal‐to‐cubic transition in CaPv is not a viable explanation for the mid‐mantle seismic scatterers/reflectors or large low‐shear‐velocity provinces [ABSTRACT FROM AUTHOR]

Nickel–rich layered oxides of LiNi1–x–yCoxMn(Al)yO2 (where 1–x–y>0.6) are considered promising cathode active materials for lithium‐ion batteries (LIBs) due to their high reversible capacity and energy density. However, the widespread application of NCM(A) is limited by microstructural degradation caused by the anisotropic shrinkage and expansion of primary particles during the H2→H3 phase transition. In this mini–review, we comprehensively discuss the formation of microcracks, subsequent material degradation, and related alleviation strategies in nickel–rich layered NCM(A). Firstly, theories on microcracks′ formation and evolution mechanisms are presented and critically analyzed. Secondly, recent advancements in mitigation strategies to prevent degradation in Ni–rich NCM/NCA are highlighted. These strategies include doping, surface coating, structural optimization, and morphology engineering. Finally, we provide an outlook and perspective to identify promising strategies that may enable the practical application of Ni–rich NCM/NCA in commercial settings. [ABSTRACT FROM AUTHOR]

Lithium cobalt oxide (LCO) has been widely used as a leading cathode material for lithium-ion batteries in consumer electronics. However, unstable cathode electrolyte interphase (CEI) and undesired phase transitions during fast Li+ diffusivity always incur an inferior stability of the high-voltage LCO (HV-LCO). Here, an ultra-thin amorphous titanium dioxide (TiO2) coating layer engineered on LCO by an atomic layer deposition (ALD) strategy is demonstrated to improve the high-rate and long-cycling properties of the HV-LCO cathode. Benefitting from the uniform TiO2 protective layer, the Li+ storage properties of the modified LCO obtained after 50 ALD cycles (LCO-ALD50) are significantly improved. The results show that the average Li+ diffusion coefficient is nearly tripled with a high-rate capability of 125 mAh g−1 at 5C. An improved cycling stability with a high-capacity retention (86.7%) after 300 cycles at 1C is also achieved, far outperforming the bare LCO (37.9%). The in situ XRD and ex situ XPS results demonstrate that the dense and stable CEI induced by the surface TiO2 coating layer buffers heterogenous lithium flux insertion during cycling and prevents electrolyte, which contributes to the excellent cycling stability of LCO-ALD50. This work reveals the mechanism of surface protection by transition metal oxides coating and facilitates the development of long-life HV-LCO electrodes. [ABSTRACT FROM AUTHOR]

Under high pressures, many crystalline metals undergo solid–solid phase transformations. In order to accurately model the behavior of materials under extreme loading conditions, it is essential to understand the kinetics of phase transition. Using molecular dynamics simulations, this work demonstrates the feasibility of characterizing the speeds of a moving phase boundary using atomistic simulations employing a suitable empirical potential for single-crystal magnesium. The model can provide temperature- and tensorial stress-dependent velocity of a moving phase boundary as a rate-limiting contribution to the kinetics of phase transformation in continuum codes. Results demonstrate that a nonlinear interaction exists between plasticity and phase transition, facilitating a jump in the velocity of a moving phase boundary, facilitated by activated plastic deformation mechanisms. [ABSTRACT FROM AUTHOR]

Fluctuations are omnipresent; they exist in any matter, due either to its quantum nature or to its nonzero temperature. In the current review, we briefly cover the quantum electrodynamic Casimir (QED) force as well as the critical Casimir (CC) and Helmholtz (HF) forces. In the QED case, the medium is usually a vacuum and the massless excitations are photons, while in the CC and HF cases the medium is usually a critical or correlated fluid and the fluctuations of the order parameter are the cause of the force between the macroscopic or mesoscopic bodies immersed in it. We discuss the importance of the presented results for nanotechnology, especially for devising and assembling micro- or nano-scale systems. Several important problems for nanotechnology following from the currently available experimental findings are spelled out, and possible strategies for overcoming them are sketched. Regarding the example of HF, we explicitly demonstrate that when a given integral quantity characterizing the fluid is conserved, it has an essential influence on the behavior of the corresponding fluctuation-induced force. [ABSTRACT FROM AUTHOR]

This study delves into the formation, transformation, and impact on coating performance of MgZn2 and Mg2Zn11 phases in low-aluminum Zn-Al-Mg alloy coatings, combining thermodynamic simulation calculations with experimental verification methods. A thermodynamic database for the Zn-Al-Mg ternary system was established using the CALPHAD method, and this alloy's non-equilibrium solidification process was simulated using the Scheil model to predict phase compositions under varying cooling rates and coating thicknesses. The simulation results suggest that the Mg2Zn11 phase might predominate in coatings under simulated production-line conditions. However, experimental results characterized using XRD phase analysis show that the MgZn2 phase is the main phase existing in actual coatings, highlighting the complexity of the non-equilibrium solidification process and the decisive effect of experimental conditions on the final phase composition. Further experiments confirmed that cooling rate and coating thickness significantly influence phase composition, with faster cooling and thinner coatings favoring the formation of the metastable phase MgZn2. [ABSTRACT FROM AUTHOR]

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Orthopyroxene is one of the dominant minerals in the Earth's upper mantle. In this study, we used Raman spectroscopy to investigate the lattice vibration and phase transition of orthopyroxene with four different compositions using diamond-anvil cells up to 34 GPa at 300 K. Our orthopyroxene samples contain 0 (En100), 9% (En91Fs9), 11% (En86Fs11), and 21% (En74Fs21) Fe. At ambient conditions, the Raman modes exhibit a negative dependence on the Fe content, with the exception of the modes at ~850 and 930 cm–1. In contrast, these two Raman modes increase with increasing the Fe content. The phase transition from metastable α- to β-phase was observed at 12.9–15 GPa for samples with <21 mol% Fe and varying Fe content has a minor effect on the phase transition pressure. Besides Fe, incorporation of 2–24 mol% Al can cause an increase in the phase transition pressure from 10–13 to 14–16 GPa. At 29–30.1 GPa, we observed the second apparent change in the Raman spectra for all four investigated samples. For Fe-bearing orthopyroxene, this change in the Raman spectra and frequency shift is associated with the phase transition from β- to γ-phase, whereas for En100, it should be caused by the change of coordination number of Si from 4 to 6 or the presence of α-popx phase. Using the obtained Raman frequency shifts, we calculated the Grüneisen parameters at high pressures. These parameters are useful for understanding the thermoelastic properties of orthopyroxene at high pressures. [ABSTRACT FROM AUTHOR]

In recent years, numerous efforts have been devoted to exploring innovative micro/nano‐optical devices (MNODs) with reconfigurable functionality, which is highly significant because of the progressively increasing requirements for next‐generation photonic systems. Fortunately, phase change materials (PCMs) provide an extremely competitive pathway to achieve this goal. The phase transitions induce significant changes to materials in optical, electrical properties or shapes, triggering great research interests in applying PCMs to reconfigurable micro/nano‐optical devices (RMNODs). More specifically, the PCMs‐based RMNODs can interact with incident light in on‐demand or adaptive manners and thus realize unique functions. In this review, RMNODs based on phase transitions are systematically summarized and comprehensively overviewed from materials, phase change mechanisms to applications. The reconfigurable optical devices consisting of three kinds of typical PCMs are emphatically introduced, including chalcogenides, transition metal oxides, and shape memory alloys, highlighting the reversible state switch and dramatic contrast of optical responses along with designated utilities generated by phase transition. Finally, a comprehensive summary of the whole content is given, discussing the challenge and outlooking the potential development of the PCMs‐based RMNODs in the future. [ABSTRACT FROM AUTHOR]

In this study, two polymorphs of the [1,1′-dibutyl-4,4′-bipyridinium][Ni(mnt)2] salt (1) were synthesized. The dark-green polymorph (designated as 1-g) was prepared under ambient conditions by the rapid precipitation method in aqueous solutions. Subsequently, the red polymorph (labeled as 1-r) was obtained by subjecting 1-g to ultrasonication in MeOH at room temperature. Microanalysis, infrared spectroscopy, thermogravimetry (TG), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD) techniques were used to characterize the two polymorphs. Both 1-g and 1-r exhibit structural phase transitions: a reversible phase transition at ∼403 K (∼268 K) upon heating and 384 K (∼252 K) upon cooling for 1-g (1-r) within the temperature range below 473 K. Interestingly, on heating 1-r to 523 K, an irreversible phase transition occurred at about 494 K, resulting in the conversion of 1-r into 1-g. Relative to 1-r, 1-g represents a thermodynamically metastable phase wherein numerous high-energy conformations in butyl chains of cations are confined within the lattice owing to quick precipitation or rapid annealing from higher temperatures. Through variable-temperature single crystal and powder X-ray diffractions, UV-visible spectroscopy, dielectric spectroscopy, and DSC analyses, this study delves into the mechanism underlying phase transitions for each polymorph and the manual transformation between 1-g and 1-r as well. [ABSTRACT FROM AUTHOR]

Incorporating support structures into solid–liquid phase change materials (SLPCMs) addresses fluid dynamics challenges during phase transitions, albeit at the cost of reduced phase change enthalpy. We propose a novel approach for developing self-sustaining, porous phase change materials. This process begins with the fabrication of self-sustaining poly(acrylic acid) octadecyl ester aerogels through cross-linking polymerization and thermally induced phase separation (TIPS) followed by ambient drying to shape the aerogel. This aerogel demonstrates exceptional energy storage capacity, impressive room-temperature elasticity, and significant load-bearing strength. Leveraging this aerogel as a scaffold, we employ a 'one-step' technique to produce phase change gels (PCGs). This method, in which EI functions both as a solvent and as SLPCMs, yields PCGs with a high latent heat capacity of 192 J g−1, outstanding phase change elasticity, and structural stability, proving highly effective in photoelectric thermal management. Notably, the 'one-step' process for fabricating self-supporting PCGs circumvents conventional steps like solvent extraction and phase change material absorption in traditional porous foam production. This simplification streamlines manufacturing and facilitates the large-scale production of phase change materials that are morphologically stable, possess high latent heat, and exhibit superior mechanical properties. [ABSTRACT FROM AUTHOR]

The separation of rare earth ions (RE3+) from aqueous solutions poses a significant challenge due to their similar chemical and physical characteristics. This study presents a method for synthesizing hematite nanoparticles (Fe2O3 NPs) through the high-temperature phase transition of natural pyrite for adsorbing RE3+ from mine wastewater. The characteristics of Fe2O3 NPs were studied using XRD, SEM, BET, XPS, FTIR, and Zeta potential. The optimal condition for RE3+ adsorption by Fe2O3 NPs was determined to be at pH 6.0 with an adsorption time of 60 min. The maximum adsorption capacities of Fe2O3 NPs for La3+, Ce3+, Pr3+, Nd3+, Sm3+, Gd3+, Dy3+, and Y3+ were 12.80, 14.02, 14.67, 15.52, 17.66, 19.16, 19.94, and 11.82 mg·g−1, respectively. The experimental data fitted well with the Langmuir isotherm and pseudo-second-order models, suggesting that the adsorption process was dominated by monolayer chemisorption. Thermodynamic analysis revealed the endothermic nature of the adsorption process. At room temperature, the adsorption of RE3+ in most cases (La3+, Ce3+, Pr3+, Nd3+, Sm3+, and Y3+) onto Fe2O3 NPs was non-spontaneous, except for the adsorption of Gd3+ and Dy3+, which was spontaneous. The higher separation selectivity of Fe2O3 NPs for Gd3+ and Dy3+ was confirmed by the separation factor. Moreover, Fe2O3 NPs exhibited excellent stability, with an RE3+ removal efficiency exceeding 94.70% after five adsorption–desorption cycles, demonstrating its potential for the recovery of RE3+ from mine wastewater. [ABSTRACT FROM AUTHOR]

We report a joint high-pressure experimental and theoretical study of the structural, vibrational, and photoluminescent properties of pure and Eu3+-doped cubic Y2O3 nanoparticles with two very different average particle sizes. We compare the results of synchrotron X-ray diffraction, Raman scattering, and photoluminescence measurements in nanoparticles with ab initio density-functional simulations in bulk material with the aim to understand the influence of the average particle size on the properties of pure and doped Y2O3 nanoparticles under compression. We observe that the high-pressure phase behavior of Y2O3 nanoparticles depends on the average particle size, but in a different way to that previously reported. Nanoparticles with an average particle size of ~37 nm show the same pressure-induced phase transition sequence on upstroke and downstroke as the bulk sample; however, nanoparticles with an average particle size of ~6 nm undergo an irreversible pressure-induced amorphization above 16 GPa that is completed above 24 GPa. On downstroke, 6 nm nanoparticles likely consist of an amorphous phase. [ABSTRACT FROM AUTHOR]

A new method for analyzing phase transitions in solutions of thermoresponsive polymers is proposed, based on determining the amount of information contained in the curve describing the phase transition. The method is based on the use of an analogy with the Nyquist-Shannon-Kotelnikov theorem, which allows us to bring the analysis of a continuous function to the analysis of its values at discrete points, as well as the results of studies of slowly changing signals from the point of view of modern information theory. This analogy allows us to determine the minimum number of parameters that describe the phase transition. The proposed method was tested using the example of phase transitions in solutions of thermoresponsive copolymers of N-vinylcaprolactam with 2-hydroxyethyl acrylate of various compositions. The effectiveness of this method has been demonstrated; in particular, it has been shown that the number of parameters that describe the phase transition in this case does not exceed four. The possibilities of using the proposed method for constructing a classification of phase transitions in solutions of stimulus-sensitive polymers are discussed. [ABSTRACT FROM AUTHOR]

In this study, the structure and phase transition of kaolin lithium clay at different calcination temperatures were studied and discussed; subsequently, the effects of Li leaching with sulfuric acid under various factors were investigated in detail. The experimental results indicated that an optimal Li leaching rate of 81.1% could be achieved when kaolin lithium clay was calcined at 600 °C for 1 h, followed by leaching with 15.0% sulfuric acid at 80 °C for 2 h. The TG-DSC, XRD, and SEM analyses showed that the layered structure of the clay was not destroyed during the leaching and calcination processes. During the process of calcination, kaolinite was converted to metakaolinite via dehydroxylation. During the process of leaching, the Al on the surface of the metakaolinite was dissolved by sulfuric acid, resulting in the destruction of the Al-O structure; then, Li+ was exchanged for H+ to the surface of the mineral and entered the solution under the action of diffusion. The leaching kinetics showed that the leaching process was controlled by a diffusion model, and the activation energy (Ea) was 41.3 kJ/mol. The rapid extraction of Li from calcined kaolin lithium clay with sulfuric acid leaching offers a high-efficiency, low-energy-consumption strategy for the utilization of new lithium resources. [ABSTRACT FROM AUTHOR]

Orthopyroxene is an abundant mineral in subducting slabs. Studying its phase transitions at high pressure is important to the understanding of mineralogy of subducting slabs in the deep Earth. Synchrotron-based single-crystal X-ray diffraction experiments were conducted on a synthetic Ni-bearing ferrosilite (Ni-En31Fs65) at pressures up to 33.8 GPa. Three phase transitions were observed at 12.1(6), 15.6(6), and 31.3(25) GPa. The first two phase transitions in Ni-En31Fs65 resemble the previously described phase transitions in Ni-free Fe-rich orthopyroxenes, i.e., the initial α-opx (Pbca) transforms to β-opx (P21/c), then the latter transforms to γ-opx (Pbca). This indicates that the incorporation of a few mol% NiSiO3 does not influence the phase transition path of Fe-rich orthopyroxene. After the third phase transition, the structure (P21ca) of Ni-En31Fs65 resembles the previously reported β-popx observed in En90 at high pressure, although the onset pressure of the phase transition in Ni-En31Fs65 is ~7 GPa lower than that in En90. β-popx has a post-pyroxene structure that contains fivefold- and sixfold-coordinated Si cations. Our results indicate that the post-pyroxene structure is β-popx (P21ca) for either Fe-poor or Fe-rich orthopyroxenes, although the phase transition path before the pyroxene → post-pyroxene is compositionally dependent. Additionally, unlike the second and third transitions, whose onset pressures are monotonously decreased by increasing Fe content, the Fe effect on shifting the first transition is much more significant for orthopyroxenes within En <50 mol% than that within En >50 mol%. [ABSTRACT FROM AUTHOR]

The interfaces between the electrode and solid‐state electrolyte play a decisive role in the performance of all‐solid‐state batteries. For example, the formation of the interphase between cathode and solid‐state electrolyte can affect interfacial impedance and thus the rate capability. Herein, the thermal stability at the solid–solid interface between LiMn2O4 cathode and garnet electrolyte LLZTO via combined in situ techniques is studied, including in situ X‐Ray diffraction, in situ transmission electron microscopy, and in situ Raman. The dynamic process of interfacial reaction at different scales is elucidated. Starting from 300 °C, Mn ions from LiMn2O4 would migrate into the solid‐state electrolyte, accompanied with the formation of LiMn3O4 interphase. As the temperature increases to 500 °C, the LiMn3O4 interphase transforms to MnO structure which hinders Li‐ion transportation and therefore increases the interfacial impedance. Although both LiMn2O4 and LLZTO could withstand continuous heating, their interface is inherently thermally unstable at relatively low temperature, which requires special attention during thermal treatment for practical fabrication. Findings provide mechanistic insights into the interfacial reaction which serves as a guidance for the design and manufacturing of all‐solid‐state batteries. [ABSTRACT FROM AUTHOR]

Phase change refers to the process of maturation and transition from the juvenile to the adult stage. In response to this shift, certain species like chestnut lose the ability to form adventitious roots, thereby hindering the successful micropropagation of adult plants. While auxin is the main hormone involved in adventitious root formation, other hormones, such as ethylene, are also thought to play a role in its induction and development. In this study, experiments were carried out to determine the effects of ethylene on the induction and growth of adventitious roots. The analysis was performed in two types of chestnut microshoots derived from the same tree, a juvenile-like line with a high rooting ability derived from basal shoots (P2BS) and a line derived from crown branches (P2CR) with low rooting responses. By means of the application of compounds to modify ethylene content or inhibit its signalling, the potential involvement of this hormone in the induction of adventitious roots was analysed. Our results show that ethylene can modify the rooting competence of mature shoots, while the response in juvenile material was barely affected. To further characterise the molecular reasons underlying this maturation-derived shift in behaviour, specific gene expression analyses were developed. The findings suggest that several mechanisms, including ethylene signalling, auxin transport and epigenetic modifications, relate to the modulation of the rooting ability of mature chestnut microshoots and their recalcitrant behaviour. [ABSTRACT FROM AUTHOR]

Non‐Hermitian Hamiltonians may still possess real eigenvalues in case of the existence of parity‐time (PT) symmetry. Exceptional points (EPs) occur at the phase transition from real to complex eigenvalues due to PT‐symmetry breaking in the parameter space. Magnonic devices use magnons to carry, transport, and process information, which have the advantages of low energy dissipation, wave‐based computing, and nonlinear data processing. The combination of PT‐symmetry and magnonics may lead to novel physics as well as unprecedented functional device applications. Recently, the research of PT‐symmetry in magnetism has developed rapidly. In this review, the theoretical predictions as well as experimental findings of PT‐symmetry in magnetism are summarized. First, a brief introduction to PT symmetry, EPs, and anti‐PT symmetry is presented. Second, the theoretical and experimental progress of magnonic PT symmetry are summarized. Third, the theoretical predictions of higher‐order EPs and anti‐PT symmetry in magnonic systems are given. Finally, the study concludes by discussing the future challenges and research prospects in magnonic PT‐symmetry, and proposals for experimental observations of magnonic higher‐order EPs and anti‐PT symmetry are suggested. [ABSTRACT FROM AUTHOR]

The pressure-induced phase transformations of rare earth orthophosphates (REPO4s) have become increasingly relevant in ceramic matrix composite (CMC) research; however, understanding of the shear-dependence of these transformations remains limited. This study employs diamond anvil cell experiments with three pressure media (neon, KCl, sample itself/no medium) to systematically assess the effect of shear on the phase transformations of TbPO4. Results show a lowering of the TbPO4 transformation onset pressure (Ponset) as well as an extension of the xenotime–monazite phase coexistence range under non-hydrostatic conditions. The TbPO4 Ponset under no medium (4.4(3) GPa) is the lowest REPO4 Ponset reported to date and represents a ~50% drop from the hydrostatic Ponset. Enthalpic differences likely account for lower Ponset values in TbPO4 compared to DyPO4. Experiments also show scheelite may be the post-monazite phase of TbPO4; this phase is consistent with observed and predicted REPO4 transformation pathways. [ABSTRACT FROM AUTHOR]

Water is transported into the deep mantle by subducting slabs, playing important roles in mantle dynamics and evolution. An aluminous hydrous mineral, phase δ with a main component of AlOOH, has been considered an important water carrier in the lower mantle. Recent studies reported that SiO2 stishovite can accommodate weight percent levels of water, indicating another important water carrier in the lower mantle. However, which mineral can mainly carry water is not clear yet. Recent hydrous phase relation studies reported that stishovite is depleted in alumina when coexisting with hydrous phase δ, in which water content of stishovite was not investigated. In this study, we investigated hydrogen partitioning between stishovite and hydrous phase δ at 24–28 GPa and 1000–1200 °C by means of Kawai-type multi-anvil press in combination with Fourier-transform infrared spectroscopy at ambient conditions on recovered samples. Fourier-transform infrared spectra of recovered stishovites showed that water contents of stishovite coexisting with hydrous phase δ were limited to up to ~ 500 ppm. This indicates that coexisting hydrous phase δ causes not only depletion in alumina but also in hydrogen in stishovite and therefore mainly transports water in a cold subducting slab. Once hydrous phase δ becomes thermally unstable, alumina and water contents in silica minerals are increased by the chemical reaction between SiO2 and AlOOH, and aluminous silica minerals such as stishovite and CaCl2-type phase will be a main water carrier in the lower mantle. Presence of small-scale seismic scatterers observed around 1900 km depth, which was considered to be caused by a transition from almost pure SiO2 stishovite to CaCl2-type phase, might also be able to be explained by the phase transition of stishovite coexisting with hydrous phase δ. [ABSTRACT FROM AUTHOR]

Phase change materials can enable temperature self-regulation due to their drastic changes in optical properties accompanying the phase transition. Significant reduction of the optical absorption after the transition is the key ingredient for an enhanced regulating performance. However, the absorptivity of unpatterned vanadium dioxide (VO2) thin films can hardly be reduced after phase transition at visual-to-infrared band. In this work, we combine the direct binary search (DBS) and particle swarm optimization (PSO) algorithms for an optimized design of temperature self-regulating nano-photonic devices on VO2 thin films. For a given incident wavelength, a pixelated structure is firstly inverse-designed by the DBS algorithm which maximizes the absorption contrast before and after the transition. To overcome fabrication challenges as pixel size is at deep sub-wavelength scale, the pixelated structure can then be replaced by geometric shapes which are more tractable in manufacturing processes. The geometrical parameters are optimized by the PSO algorithm where our optimized device brings the absorptivity down to 33% after the transition. These results provide an effective way for the inverse design of optimized nano-photonic structures based on phase change materials. [ABSTRACT FROM AUTHOR]

Ferroelectric polymer-based electrocaloric effect may lead to sustainable heat pumps and refrigeration owing to the large electrocaloric-induced entropy changes, flexible, lightweight and zero-global warming potential. Herein, low-k nanodiamonds are served as extrinsic dielectric fillers to fabricate polymeric nanocomposites for electrocaloric refrigeration. As low-k nanofillers are naturally polar-inactive, hence they have been widely applied for consolidate electrical stability in dielectrics. Interestingly, we observe that the nanodiamonds markedly enhances the electrocaloric effect in relaxor ferroelectrics. Compared with their high-k counterparts that have been extensively studied in the field of electrocaloric nanocomposites, the nanodiamonds introduces the highest volumetric electrocaloric enhancement (~23%/vol%). The resulting polymeric nanocomposite exhibits concurrently improved electrocaloric effect (160%), thermal conductivity (175%) and electrical stability (125%), which allow a fluid-solid coupling-based electrocaloric refrigerator to exhibit an improved coefficient of performance from 0.8 to 5.3 (660%) while maintaining high cooling power (over 240 W) at a temperature span of 10 K. Low-k nanodiamonds are discovered to possess the ability to concurrently enhance the electrocaloric effect, thermal conductivity, and electrical stability of polymeric nanocomposites, providing support for electrocaloric refrigeration. [ABSTRACT FROM AUTHOR]

This work presents the optimization of the crystallization behavior and reliability of Sn15Sb85 thin films by doping Sm element. The phase transition behaviors induced by thermal were investigated by in situ resistance measurement. With the addition of Sm element, Sn15Sb85 film exhibits the superior crystallization temperature (232 °C) and data conservation (172.32 °C for 10 years), larger activation energy of crystallization (4.91 eV) and crystalline resistance (∼103 Ω), which contributes to the increased thermal stability of the amorphous state and decrease in the programming energy. The Sm-doping can broaden the energy band gap from 0.55 to 1.07 eV. The amorphous Sm and Sn compositions could retard grain growth and refine grain size from 21.13 to 11.13 nm, combining with x-ray diffraction and x-ray photoelectron spectroscopy. The surface morphology of Sn15Sb85 film becomes smoother after Sm doping as determined by atomic force microscopy images, resulting in the improved interfacial reliability. Phase change memory devices based on Sm0.095(Sn15Sb85)0.905 films can successfully achieve the complete SET and RESET reversible operation process with high operating speed (200 ns) and low power consumption (1.6 × 10−10 J). The results suggest that doping the proper concentration of Sm element will be an effectual solution to adapt and optimize the crystallization properties of Sn15Sb85 phase change material. [ABSTRACT FROM AUTHOR]

Predicting the compactness of the invasion front and the amount of trapped fluid left behind is of crucial importance to applications ranging from microfluidics and fuel cells to subsurface storage of carbon and hydrogen. We examine the interplay of wettability, macro‐ and pore scale heterogeneity (pore angularity and pore wall roughness), and its influence on flow patterns formation and trapping efficiency in porous media by a combination of 3D micro‐CT imaging with 2D direct visualization of micromodels. We observe various phase transitions between the following capillary flow regimes (phases): (a) compact advance, (b) wetting and drainage Invasion percolation, (c) Ordinary percolation. Plain Language Summary: The study of phase transitions in flow patterns that depend on the heterogeneity, wettability, and surface roughness of the pore space and their classification in phase diagrams is one of the challenges in recent multiphase flow physics. We study the dynamics of thick film and corner flows by visualization experiments with micromodels. Both flow types are characteristic of geologically representative porous media (sands, sandstones) and control the displacement and trapping process. The 2D micromodels accurately reproduce the characteristic geometric, morphological, and topological properties of 3D porous media. All microstructures were derived from μ‐CT images. We fabricated identical microstructures by both DRIE‐ICP etching of silicon wafers and anisotropic chemical etching of glass ceramics to vary the degree of surface roughness. The results are in excellent agreement with previous μ‐CT experiments. We observe various phase transitions between the following flow regimes (phases): (a) frontal/compact advance, (b) Ordinary percolation, and (c) Invasion percolation. We show that they can be classified according to Blunt's "heterogeneity versus wettability" phase diagram. Key Points: Interplay of pore‐scale heterogeneity, wettability, and surface roughness controls displacement patterns and capillary trapping efficiencyThe invasion flow pattern for capillary flow were visualized by micro‐CT‐ and micromodel experiments and classified in a new phase diagramFour generic flow regimes (phases) were observed: frontal advance, wetting and drainage invasion percolation, and ordinary percolation [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have layered structures with excellent tribological properties. Since the energy difference between hexagonal-molybdenum ditelluride (2H-MoTe2) and distorted octahedral-molybdenum ditelluride (1T'-MoTe2) is very small among the transition metal dichalcogenides (TMDCs), MoTe2 becomes one of the most promising candidates for phase engineering. In our experiment, we found that the friction force and friction coefficient (COF) of 2H-MoTe2 were an order of magnitude smaller than those of 1T'-MoTe2 by the atomic force microscope (AFM) experiments. The friction difference between 1T'-MoTe2 and 2H-MoTe2 was further verified in molecular dynamics (MD) simulations. The density functional theory (DFT) calculations suggest that the friction contrast is related to the difference in sliding energy barrier of the potential energy surface (PES) for a tip sliding across the surface. The PES obtained from the DFT calculation indicates that the maximum energy barrier and the minimum energy path (MEP) energy barrier of 2H-MoTe2 are both smaller than those of 1T'-MoTe2, which means that less energy needs to be dissipated during the sliding process. The difference in energy barrier of the PES could be ascribed to its larger interlayer spacing and weaker Mo–Te interatomic interactions within the layers of 2H-MoTe2 than those of 1T'-MoTe2. The obvious friction difference between 1T'-MoTe2 and 2H-MoTe2 not only provides a new non-destructive means to detect the phase transition by the AFM, but also provides a possibility to tune friction by controlling the phase transition, which has the potential to be applied in extreme environments such as space lubrication. [ABSTRACT FROM AUTHOR]

The irreversible oxygen redox and structural degradation of LiNi0.8Co0.1Mn0.1O2 (NCM811) at a 4.5 V high voltage cause a severe decline in cycling performance for lithium‐ion batteries. In this study, a novel approach is proposed to enhance the anionic redox chemistry and stability of NCM811 cathode material by introducing gaseous selenium. Seβ+ species are selectively adsorbed within oxygen vacancies, leading to the continuous replacement of Oα− to form a stable O–TM–Se bond during deep charging. Furthermore, Selenium modification improves cationic redox efficiency and alleviates Oα− (α < 2) outward migration, increases oxygen vacancy formation energy. The redox activity of oxygen is diminished, facilitating improved reversibility of oxygen redox and effectively inhibiting irreversible oxygen escape. Additionally, Selenium increases the energy barrier for phase transition, effectively suppressing irreversible phase transition and Ni migration. Selenium reacts with escaping oxygen to form SeO2, effectively reducing side reactions during cycling. As a result, the proposed approach significantly inhibits irreversible oxygen release, leading to remarkable cyclic stability with 87.5% capacity retention after 300 cycles at 1C at 4.5 V and maintained 192.9 mAh g−1 after 150 cycles under 60C. The Se modification realizes stability anionic redox strategy to design novel high‐energy‐density cathode materials with superior cycling performance. [ABSTRACT FROM AUTHOR]

Light beams bearing orbital angular momentum (OAM) are used in various scientific and engineering applications, such as microscopy, laser material processing, and optical tweezers. Precise topological charge control is crucial for efficiently using vortex beams in different fields, such as information encoding in optical communications and sensor systems. This work presents a novel method for optimizing an emitting micro-ring resonator (MRR) for emitting vortex beams with variable orders of OAM. The MRR consists of a ring waveguide with periodic structures side-coupled to a bus waveguide. The resonator is tunable due to the phase change material Sb2Se3 deposited on the ring. This material can change from amorphous to crystalline while changing its refractive index. In the amorphous phase, it is 3.285 + 0i, while in the transition to the crystalline phase, it reaches 4.050 + 0i at emission wavelength 1550 nm. We used this property to control the vortex beam topological charge. In our study, we optimized the distance between the bus waveguide and the ring waveguide, the bending angle, and the width of the bus waveguide. The optimality criterion was chosen to maximize the flux density of the radiated energy emitted by the resonator. The numerical simulation results proved our method. The proposed approach can be used to optimize optical beam emitters carrying OAM for various applications. [ABSTRACT FROM AUTHOR]

Zr-modified LaNiO3 catalysts (LaNixZr1−xO3; 0 ≤ x ≤ 1) are synthesized by the sol–gel method. The physio-chemical properties of materials are investigated using different characterization techniques and evaluated for the CO2 reforming of methane to syngas. Interestingly, the characterization studies revealed the phase transformation from La-Zr pyrochlore to La-Ni perovskite depending on the Ni:Zr ratio in the material. The formation of the pyrochlore phase is observed for high-Zr-containing catalysts, thus leading to the production of bulk NiO. The formation of La-Ni perovskite is observed for high-Ni-containing catalysts and the ZrO2 acted as a support. The formation of La-Ni perovskite supported on ZrO2 enhanced the Ni dispersion of the catalysts. The high dispersion of Ni enhanced the catalytic activity, and LaNi0.8Zr0.2O3 showed the best performance among all of the studied catalysts in terms of conversions and the H2/CO ratio. [ABSTRACT FROM AUTHOR]