Solid Phase Transition Research Articles

Morphological Change of Cocrystal Bis(8-Quinolinolato) Copper(II): 7,7,8,8-Tetracyanoquinodimethane Polymorphism

We studied cocrystal of bis(8-quinolinolato) copper(II) (CuQ2) and 7,7,8,8-tetracyanoquinodimethane (TCNQ), which change dramatically crystal shape in a moment by adding press on crystal face. Single crystal was prepared by dissolving CuQ2 and TCNQ in chloroform by evaporation of the solution at ambient conditions. We investigated about crystal structure and morphological change properties. We proclaim that this phenomenon is solid phase transition to Form I from Form II, it is caused by pressure on the crystal face (001) of Form II and the crystal expansion direction is the side face (100). We take note of the common structure between polymorph and explain that this transition occurs by the structure like dominoes falling. We obtained a correlation between molecular level structure change and macroscopic shape changes.

Constraining the release of Sn to the ambient melting point following shock loading using time-resolved x-ray diffraction

The formation of liquid following release from a shocked state governs the transition from spall to cavitation and the formation of ejecta in metals. In order to build physics-based models of these processes, it is necessary to critically evaluate the relative importance of kinetics and entropy generation during the release along with the accuracy of multiphase equations of state. Tin (Sn) has served as a testbed for a variety of experiments examining strength and ejecta due to its accessible melt boundary and solid–solid phase transitions. This work presents experiments examining the phase evolution of high purity Sn following the shock and release to ambient stress near the melting point. Sn is found to release to states between its ambient solidus and liquidus from approximately 19 to 33 GPa under uniaxial loading, with the two-phase region being characterized by a reduction in the intensity of the (220), (211) β-Sn doublet. Jetting experiments performed at 27–28 GPa exhibit comparable diffraction patterns with what is observed following the uniaxial release. The solid fractions of β-Sn in the ambient mixed phase region are found to decrease linearly with increasing shock stress as increasing liquid Sn is formed. The results provide much needed information for interpreting measurements of dynamic strength at a high strain rate and experiments examining cavitation and shallow bubble collapse in Sn.

Experimental and molecular dynamic studies of phase transformation and amorphization in silicon during high-energy ball milling

Nano-sized and amorphous silicon (α-Si) have a wide range of properties and applications, but their atomistic structure and the process of crystal evolution are still unclear. In this study, a combined action is used to present a mechanism for the crystal-to-amorphous solid–solid phase transition in silicon during mechanical alloying (MA) at room temperature. For this purpose, the ball milling of silicon was performed and changes in crystallographic structure and amorphous phase were studied by scanning electron microscopy (SEM), X-ray diffraction patterns (XRD), and energy dispersive X-ray spectroscopy (EDX). The process of changing phase was determined by quantitative phase analysis (MAUD/Rietveld refinement). In the simulation part, a crystal structure of silicon consisting of 64 atoms was created and uniaxial and biaxial external pressures were applied randomly by BIOVIA Materials Studio. The time step and simulation time were 1 and 300 Ps, respectively. Important atomic properties including density, mean square displacement (MSD), angle length and bonds distribution, and the fraction of broken bands were measured after applying per compression. Atomic structure and changes in crystalline phase to nano and amorphous phases were studied and these results had a considerable agreement with the experimental part and well-known previous studies. The diamond cubic structure shows a remarkable toughness during the modeling and so amorphization was performed at an exponential evolution. The Results of the simulations showed that the bond angle and length distribution and MSD, were increased significantly, and in contrast, density was decreased to 1.254 g/cm3. The percentage of the broken Si-Si bonds was 58.12 % and a new definition of Si amorphization based on the fraction of covalent bonds was proposed. The amorphization started from the surface of Si and spread by the partial distribution toward the crystal structure. These findings show that the proposed mechanism based on the fraction of breaking bonds and pressure-induced amorphization could be used for the accurate simulation of the solid–solid phase transformation.

Sequence determinants and solution conditions underlying liquid to solid phase transition.

Life consists of numberless functional biomolecules that exist in various states. Besides well-dissolved phases, biomolecules especially proteins and nucleic acids can form liquid droplets through liquid-liquid phase separation (LLPS). Stronger interactions promote a solid-like state of biomolecular condensates, which are also formerly referred to as detergent-insoluble aggregates. Solid-like condensates exist in vivo physiologically and pathologically, and their formation has not been fully understood. Recently, more and more research has proven that liquid to solid phase transition (LST) is an essential way to form solid condensates. In this review, we summarized the regions in the sequence that have different impacts on phase transition and emphasized that the LST is affected by its sequence characteristics. Moreover, increasing evidence unveiled that LST is affected by various solution conditions. We discussed solution conditions like protein concentration, pH, ATP, ions, and small molecules in a solution. Methods have been established to study these solid phase components. Here, we summarized low-throughput experimental techniques and high-throughput omics methods in the study of the LST.

Reinvestigating the Preferential Enrichment of DL-Arginine Fumarate: New Thoughts on the Mechanism of This Far from Equilibrium Crystallization Phenomenon.

Preferential enrichment (PE) is a crystallization process, starting from either a racemic of slightly enantio-enriched solution (ca. +5%) that results in a high enantiomeric excess in the liquid phase (>+90%ee) and a slight opposite excess in the deposited crystals (-2 to -5%ee). The mechanism(s) of this symmetry-breaking phenomenon is (are) still a matter of debate since it eludes rationalization by phase diagram formalism. In this publication, we thoroughly reinvestigate the PE phenomenon of arginine fumarate by using a new approach: the process is monitored by introducing isotopically labeled arginine enantiomers into the crystallization medium to better understand the mass exchanges during crystallization. These experiments are supported by chiral HPLC-MS/MS. This study permits re-evaluating the criteria that were thought mandatory to perform PE. In particular, we show that PE occurs by a continuous exchange between the solution and the crystals and does not require the occurrence of a solvent-mediated solid-solid phase transition.

Thermal Stability of Semiconductor Nanocrystal Solids: Understanding Nanocrystal Sintering and Grain Growth

Nanomaterials are naturally metastable with respect to bulk solids. This raises the very important fundamental problem of their morphological stability, especially when nanoscale crystallites are touching or nearly touching each other, such as in thin-film devices. In some cases, nanostructuring must be preserved under operational conditions (e.g., in quantum dot LEDs, lasers, photodetectors, and nanogranular thermoelectric devices). In other cases, we use nanocrystalline particles as precursors to a material with large crystalline grains and aim to sinter them as efficiently as possible (e.g., in polycrystalline thin-film solar cells). We carried out a systematic study of sintering and grain growth in materials composed of various sub-10 nm semiconductor grains. The boundaries between individual semiconductor grains have been chemically engineered using inorganic surface ligands. We found that the early stages of sintering and grain growth of nanocrystalline semiconductors are controlled by the ion mobility at the nanocrystal surfaces, while the late stages of grain growth are controlled by the mobility of the grain boundaries. This appears to be a general phenomenon for semiconductor nanocrystals, and it leads to several interesting and counterintuitive trends. For example, III–V InAs nanocrystals are generally much more resilient against sintering and grain growth compared to II–VI CdSe nanocrystals even though bulk CdSe has significantly higher melting point temperature than InAs (1268 °C vs 942 °C). Grain growth can be dramatically accelerated when coupled to solid−solid phase transitions. These findings expand our toolbox for rational design of nanocrystal materials for different applications.

Atomistic mechanisms of phase nucleation and propagation in a model two-dimensional system

We present a computational study on the solid–solid phase transition of a model two-dimensional system between hexagonal and square phases under pressure. The atomistic mechanism of phase nucleation and propagation are determined using solid-state Dimer and nudged elastic band (NEB) methods. The Dimer is applied to identify the saddle configurations and NEB is applied to generate the transition minimum energy path (MEP) using the outputs of Dimer. Both the atomic and cell degrees of freedom are used in saddle search, allowing us to capture the critical nuclei with relatively small supercells. It is found that the phase nucleation in the model material is triggered by the localized shear deformation that comes from the relative shift between two adjacent atomic layers. In addition to the conventional layer-by-layer phase propagation, an interesting defect-assisted low barrier propagation path is identified in the hexagonal to square phase transition. The study demonstrates the significance of using the Dimer method in exploring unknown transition paths without a priori assumption. The results of this study also shed light on phase transition mechanisms of other solid-state and colloidal systems.

From Components to Phase-Dependent Dynamics of Diffusivity in Wax Solutions Subjected to Fluid–Solid Phase Transition: Insights from Pulsed Field Gradient NMR

From Components to Phase-Dependent Dynamics of Diffusivity in Wax Solutions Subjected to Fluid–Solid Phase Transition: Insights from Pulsed Field Gradient NMR

Rheological characteristics of cement-sodium silicate grout in its fluid–solid phase transition process

The rheology of quick-setting grout during the phase transition from fluid to solid is a key factor for consideration in grouting diffusion design. In this paper, cement-sodium silicate grout (CS grout) was used in the experiment as a typical quick-setting grout. The rheological properties of quick-setting grout during the entire phase transition period, including phase transition time, grout viscosity, and yield stress, were investigated. The influences of water-cement mass ratio (W/C mass ratio) and cement-sodium silicate ratio (C/S volume ratio) on rheological properties of quick-setting grout were analyzed. Results show that gel reaction process of CS grout can be divided into three stages: fluid phase, fluid–solid phase, and solid phase. Among them, shear stress of CS grout increased rapidly with phase transition from fluid to fluid–solid state. The rheological constitutive relation of CS grout always belonged to the Bingham model with W/C mass ratio ranging from 0.8 to 2.0 and C/S volume ratio ranging from 1 to 3. A rheological model of CS grout was presented, among which the relationship between rheological parameters and reaction time is expressed by exponential functions.

Polyanion order controls liquid-to-solid phase transition in peptide/nucleic acid co-assembly

The Central Dogma highlights the mutualistic functions of protein and nucleic acid biopolymers, and this synergy appears prominently in the membraneless organelles widely distributed throughout prokaryotic and eukaryotic organisms alike. Ribonucleoprotein granules (RNPs), which are complex coacervates of RNA with proteins, are a prime example of these membranelles organelles and underly multiple essential cellular functions. Inspired by the highly dynamic character of these organelles and the recent studies that ATP both inhibits and templates phase separation of the fused in sarcoma (FUS) protein implicated in several neurodegenerative diseases, we explored the RNA templated ordering of a single motif of the Aβ peptide of Alzheimer's disease. We now know that this strong cross-β propensity motif alone assembles through a liquid-like coacervate phase that can be externally templated to form distinct supramolecular assemblies. Now we provide evidence that structured phosphates, ranging from complex structures like double stranded and quadraplex DNA to simple trimetaphosphate, differentially impact the liquid to solid phase transition necessary for paracrystalline assembly. The results from this simple model illustrate the potential of ordered environmental templates in the transition to potentially irreversible pathogenic assemblies and provides insight into the ordering dynamics necessary for creating functional synthetic polymer co-assemblies.

Intrinsic Phase Stability and Inherent Bandgap of Formamidinium Lead Triiodide Perovskite Single Crystals.

Understanding the intrinsic phase stability and inherent band gap of formamidinium lead triiodide (FAPbI3 ) perovskites is crucial to further improve the performance of perovskite solar cells (PSCs). Herein, we explored the α- to δ-phase transition and band gap of FAPbI3 single crystals grown by an inverse temperature solubility method. We found that the residual γ-butyrolactone solvents in the inner empty space of the FAPbI3 single crystal accelerate the phase transition at kinetics. By adopting 2-methoxyethanol as the solvent, over 2000 h of stable α-FAPbI3 crystals could be acquired. This proves that although FAPbI3 is regarded as unstable at thermodynamics, it could own excellent kinetic stability without any doping or additives because of the slow solid to solid phase transition instead of the fast phase transition assisted by the solvents. Furthermore, we revealed that the bulk FAPbI3 single crystal with a size above 100 μm can have an inherent band gap of 1.41 eV. Thus, our work provides key scientific guidance for high-performance FAPbI3 -based PSCs.

Intrinsic Phase Stability and Inherent Bandgap of Formamidinium Lead Triiodide Perovskite Single Crystals

AbstractUnderstanding the intrinsic phase stability and inherent band gap of formamidinium lead triiodide (FAPbI3) perovskites is crucial to further improve the performance of perovskite solar cells (PSCs). Herein, we explored the α‐ to δ‐phase transition and band gap of FAPbI3 single crystals grown by an inverse temperature solubility method. We found that the residual γ‐butyrolactone solvents in the inner empty space of the FAPbI3 single crystal accelerate the phase transition at kinetics. By adopting 2‐methoxyethanol as the solvent, over 2000 h of stable α‐FAPbI3 crystals could be acquired. This proves that although FAPbI3 is regarded as unstable at thermodynamics, it could own excellent kinetic stability without any doping or additives because of the slow solid to solid phase transition instead of the fast phase transition assisted by the solvents. Furthermore, we revealed that the bulk FAPbI3 single crystal with a size above 100 μm can have an inherent band gap of 1.41 eV. Thus, our work provides key scientific guidance for high‐performance FAPbI3‐based PSCs.

Phase transformation path in Aluminum under ramp compression; simulation and experimental study

We present a framework based on non-equilibrium molecular dynamics (NEMD) to reproduce the phase transformation event of Aluminum under ramp compression loading. The simulated stress-density response, virtual x-ray diffraction patterns, and structure analysis are compared against the previously observed experimental laser-driven ramp compression in-situ x-ray diffraction data. The NEMD simulations show the solid–solid phase transitions are consistent to experimental observations with a close-packed face-centered cubic (fcc) (111), hexagonal close-packed (hcp) structure (002), and body-centered cubic bcc (110) planes remaining parallel. The atomic-level analysis of NEMD simulations identifiy the exact phase transformation pathway happening via Bain transformation while the previous in situ x-ray diffraction data did not provide sufficient information for deducing the exact phase transformation path.

Screening Order–Disorder Phase Transition in 1-D Perovskite-like Crystals of [Azetidinium]CdBr3

In search for new polar compounds, we have synthesized the organic–inorganic hybrid [C3H8N]CdBr3 (AZECdBr3). This is a bromide analog of [C3H8N]CdCl3, which has been studied by us earlier. The chloride compound exhibited ferroelectric properties, so it seemed reasonable to check the properties of AZECdBr3. The AZECdBr3 crystals reveal three phase transitions (PTs): the first one (I → II) of the second order at 437.0/436.7 K (heating/cooling), the next (also of the second order) at 231.0 K (II → III), and the last one (classified as a first-order transition) at 197.0/194.0 K (III → IV). On the basis of the DSC data, the thermodynamic parameters have been estimated. The single-crystal X-ray measurements indicate orthorhombic symmetry in all phases investigated, i.e., space groups: Cmcm (phase II 250.0(1) K) and Pbnm for structures at 215.0(1) K (phase III) and 100.0(1) K (phase IV). The anionic substructure is composed of distorted [CdBr6]4– octahedra forming infinite one-dimensional [{CdBr3}−]n chains arranged in the c-direction. The azetidinium cations, C3H8N+, are located between these inorganic chains. The dielectric permittivity, ε′, measured at frequencies from the range between 500 Hz and 2 MHz obtained for single crystals along the [100], [010], and [001] directions evidenced a strong anisotropy. The ferroelastic nature of phases II, III, and IV was confirmed by the polarized light microscopy photographs. On the basis of the obtained results, the mechanisms of the solid–solid PTs have been proposed.

Numerical analysis of inner heating tube position for improving solid-phase transition in a shell-and-tube heat accumulator

Latent heat thermal storage (LHTS) system is vital to reduce environment pollution. In the shell-and-tube heat accumulator, the position of the inner heating tube plays a vital role in the thermal storage. To analyze the effect of the inner tube position on the phase transition, a two-dimensional numerical model is developed. The structure has the minimum full melting time of 3480 s when the inner tube is 12 mm (L = 12 mm) from the center. Compared with L = 0 mm, the full melting time at L = 12 mm can be reduced by 13.4%.

Germ Granules in Animal Oogenesis.

In eukaryotic cells, many macromolecules are organized as membraneless biomolecular condensates (or biocondensates). Liquid-liquid and liquid-solid phase transitions are the drivers of the condensation process. The absence of membrane borders makes biocondensates very flexible in their composition and functions, which vary in different cells and tissues. Some biocondensates are specific for germ line cells and are, thus, termed germ granules. This review summarizes the recent data on the composition of germ granules and their functions in gametes. According to these data, germ granules are involved in the determination of germline cells in some animals, such as Amphibia. In other animals, such as Mammalia, germ granules are involved in the processes of transposons inactivation and sequestration of mRNA and proteins to temporarily decrease their activity. The new data on germ granules composition and functions sheds light on germ cell differentiation and maturation properties.

Phase‐Transitional Bismuth‐Based Metals enable Rapid Embolotherapy, Hyperthermia, and Biomedical Imaging (Adv. Mater. 42/2022)

Embolic Agents In article number 2205002, Xuyang Sun, Jing Liu, and co-workers propose a novel liquid embolic agent with rapid liquid–solid phase-transition capability, for administrating simultaneous embolotherapy, hyperthermia, and biomedical imaging. Through simple syringe injection, the liquid embolic agent can flow and fill the nutrient supply vessels of the hepatoma to realize fast embolization. This high-image-contrast material with good biocompatibility is also demonstrated to produce a large amount of heat under an external electromagnetic field to enhance the therapeutic efficacy of tumor embolization, which holds great promise in future embolism and theranostic platforms.

Density-driven higher-order topological phase transitions in amorphous solids

Amorphous topological states, which are independent of the specific spatial distribution of microscopic constructions, have gained much attention. Recently, higher-order topological insulators, which are a new class of topological phases of matter, have been proposed in amorphous systems. Here, we propose a density-driven higher-order topological phase transition in a two-dimensional amorphous system. We demonstrate that the amorphous system hosts a topological trivial phase at low density. With an increase in the density of lattice sites, the topological trivial phase converts to a higher-order topological phase characterized by a quantized quadrupole moment and the existence of topological corner states. Furthermore, we confirm that the density-driven higher-order topological phase transition is size dependent. In addition, our results should be general and equally applicable to three-dimensional amorphous systems. Our findings may greatly enrich the study of higher-order topological states in amorphous systems.

Mechanochemical activation of Al/V2O5 composites: Thermal transformations

Thermal transformations of mechanochemically activated (MCA) thermites Al/V2O5 (mixtures of Al with bare coarse V2O5 as well as with highly defected nanosized n-V2O5) were analyzed by the methods of X-ray diffraction, calorimetry, EPR spectroscopy, adsorption and SEM. The influence of the treatment time of MCA on stages of thermal transformations during oxidation of aluminum in the reaction 10Al + 3V2O5 → 5Al2O3 + 6V was revealed and the optimal conditions of MCA were established. It was shown that the use of highly defected n-V2O5 does not lead to changing the ignition conditions of mixtures and the dynamics of thermal reactions. For the non-activated mixtures and at short-time of MCA, the intensive oxidation of Al occurred by the liquid-phase mechanism at Т > 680 °C, above melting temperatures of the both components. At the optimal conditions of MCA, transformations are started at temperatures only slightly above 150 °C by the solid-phase mechanism. Reduction of V2O5 occurs via several lower vanadium oxides: V2O5 → V4O9 → V6O13 → VO2-1 → VO2-2 → V3O5 → V2O3 → VO → V. Heating of mixtures is accompanied by the increase of concentrations of paramagnetic centers (PCs) VO2+ of two types up to 420 °C, and by their noticeable decrease at 520 °C. Assumptions concerning relations between PCs and phases V4O9, VO2-1, and on the effect of PCs on initiation of the solid-phase transitions are discussed. MCA treatment carried out upon optimal conditions promotes the explosive way of the reaction at firing the activated samples. Possibility of passing the reaction by the solid-phase mechanism as the result of MCA can be caused by the formation of large surface area of contacts ca. 7–8 m2/g, and also by the formation of vanadyl PCs clusters.

Dissolved water in jet fuels: a low-temperature quality and water solubility study

While undesirable, water contamination of jet fuels is unavoidable. It is essential to understand the impacts of dissolved water on the fuel properties and the water-fuel interactions. In this study, the impacts of dissolved water on low-temperature qualities of aviation fuels were determined. The liquid–solid phase transition temperature was found to increase with the jet fuels saturated with dissolved water under increased temperatures owing to the increase of fuel water solubility. The conductor-like screening model for realistic solvation (COSMO-RS) method was employed to predict the water solubility in petroleum and sustainable aviation fuels (PAFs and SAFs) over a temperature range of −40 to 50 °C based on fuel composition data obtained by comprehensive GC × GC chromatography. The calculation results are in good agreement with experimental values at temperatures below 20 °C, with RMSE = 17.1 and 17.7 ppm for PAFs and SAFs, respectively. Results calculated for these complex fuel chemistries predicted experimental values more closely than calculations performed for simpler PAF and SAF surrogates. COSMO-RS was also employed to calculate water solubility in PAF and SAF blends (RMSE = 18.3 ppm). Results demonstrate that the COSMO-RS method has potential as a tool in new SAF certification.