Crystallization Kinetics Research Articles

The Effects of Electric Fields on Protein Phase Behavior and Protein Crystallization Kinetics.

We experimentally studied the effects of an externally applied electric field on protein crystallization and liquid-liquid phase separation (LLPS) and its crystallization kinetics. For a surprisingly weak alternating current (AC) electric field, crystallization was found to occur in a wider region of the phase diagram, while nucleation induction times were reduced, and crystal growth rates were enhanced. LLPS on the contrary was suppressed, which diminishes the tendency for a two-step crystallization scenario. The effect of the electric field is ascribed to a change in the protein-protein interaction potential.

Regulating Surface Metal Abundance via Lattice-Matched Coordination for Versatile and Environmentally-Viable Sn-Pb Alloying Perovskite Solar Cells.

Narrow-bandgap Sn-Pb alloying perovskites showcased great potential in constructing multiple-junction perovskite solar cells (PSCs) with efficiencies approaching or exceeding the Shockley-Queisser limit. However, the uncontrollable surface metal abundance (Sn2+ and Pb2+ ions) hinders their efficiency and versatility in different device structures. Additionally, the undesired Pb distribution mainly at the buried interface accelerates the Pb leakage when devices are damaged. In this work, a novel strategy is presented to modulate crystallization kinetics and surface metal abundance of Sn-Pb perovskites using a cobweb-like quadrangular macrocyclic porphyrin material, which features a molecular size compatible with the perovskite lattice and robustly coordinates with Pb2+ ions, thus immobilizing them and increasing surface Pb abundance by 61%. This modulation reduces toxic Pb leakage rates by 24-fold, with only ∼23 ppb Pb in water after severely damaged PSCs are immersed in water for 150 h.This strategy can also enhance chemical homogeneity, reduce trap density, release tensile strain and optimize carrier dynamics of Sn-Pb perovskites and relevant devices. Encouragingly, the power conversion efficiency (PCEs) of 23.28% for single-junction, full-stack devices and 21.34% for hole transport layer-free Sn-Pb PSCs are achieved.Notably, the related monolithic all-perovskite tandem solar cell also achieves a PCE of 27.03% with outstanding photostability.

Non-isothermal crystallization kinetics of biocomposites based on PLA/PHBV and spent coffee grounds

AbstractThis study deals with the modification of a predominantly amorphous poly(lactic acid) (PLA) by blending it with a semi-crystalline biopolymer, polyhydroxybutyrate-co-valerate (PHBV), which has a high crystallinity. The blends with different concentrations of PLA and PHBV were compounded with spent coffee grounds (SCGs) and processed by injection moulding. The structural, thermal and mechanical properties of the produced samples were investigated. Particular attention was paid to the effect of the presence of SCG and the concentration of PHBV in the blend on the crystallization kinetics and the heat deflection temperature (HDT). For equimolar blends, only a slight increase in HDT (about 5 °C) was observed, but the addition of PHBV suppressed the cold crystallization of PLA, which otherwise negatively affects the dimensional stability of injection moulded parts. A similar effect, but to a lesser extent, was achieved by adding SCG to the PLA matrix. Thus, it is clear that the material structures of PLA/PHBV blends and composites help to minimize additional shrinkage of the parts and increase their dimensional stability. Due to the co-continuous structure of the symmetric PLA/PHBV blends and the increase in the degree of crystallinity from 36 to 47% by annealing the produced samples, the heat deflection temperature increased from 65 up to 90 °C.

Wafer-scale Te thin film with high hole mobility and piezoelectric coefficients

p-type semiconductors are significant for integrated nanoelectronics. Tellurium (Te), a mono-elemental material, is a p-type semiconductor with high mobility. Its outstanding performance renders it widely applicable in the fields of electronics and optoelectronics. However, the wafer-scale fabrication of Te thin films is challenging. In this study, we reported an ion-bean sputtered Te thin film and investigated the effects of annealing temperatures. Annealing-induced crystallization kinetics were assessed through Raman spectroscopy, x-ray diffraction, and atomic force microscopy. After annealing, the film's conductivity increased from 10−5 to 10−4 S and mobility from 18 to 53 cm2 V−1 s−1. Dual AC resonance tracking switching spectroscopy piezoelectric force microscopy is used to investigate piezo/ferroelectric properties. The coercive voltages are −2 and 4 V respectively, and the effective piezoelectric coefficient (d33) is 40 pm/V. Butterfly and phase-switching loops demonstrate its possible ferroelectricity. The Te thin film has potential applications in optoelectronics, nonvolatile memory devices, and neuromorphic computation.

Crystallization Behavior of the CaO–SiO2–Al2O3–MgO System Inclusions

The crystallization process of low melting point CaO–SiO2–Al2O3–MgO system inclusions during the continuous casting and hot rolling process greatly affects the deformability of inclusions. The effect of Al2O3 and MgO contents on the crystallization characteristics of CaO–SiO2–Al2O3–MgO system melts representing the typical oxide inclusions in Si–Mn deoxidized steels is systematically investigated. The continuous cooling transformation and time–temperature transformation experiments are carried out. The results reveal that the increase of Al2O3 contents restrains the crystallization process of the melt, whereas the crystallization tendency of the melt is promoted with the increase of MgO contents. The precipitated phases are predominately 2CaO·MgO·2SiO2 and 3CaO·MgO·2SiO2, and the primary crystalline phase is unaffected by the changes of Al2O3 and MgO contents. To obtain low melting point plasticized inclusions with limited crystallization ability, it is recommended to control the Al2O3 and MgO contents greater than 15 wt% and below 5 wt%, respectively. The isothermal treatment is suggested to be controlled within a proper temperature range (1175–1250 °C) to decrease the crystallization kinetics. The oxide system's viscosity change is the limiting kinetic factor in the crystallization process, and it can be utilized to predict the system's crystallization tendency.

Evaluation of melting front kinetics in cylindrical phase change materials module using infrared thermography and digital imaging

An experimental study examined buoyancy-driven convection in the unconstrained melting of PCM within a cylindrical module. Melting progress and PCM fraction were analyzed using IRT and digital imaging. Initial symmetric melting led to accelerated phase change at the bottom and a rippled PCM surface. Thermal stratification in the lower module was evident, with molten liquid displacing colder fluid. Observations underestimated bottom PCM waviness and melting. As the melt zone expanded, buoyancy-driven convection intensified, speeding up melting at the top while the bottom relied more on conduction. The study details transient front positions, temperature profiles, solid PCM amounts, and melting times. Unstable fluid layers near the bottom caused waviness due to chaotic fluctuations. Nucleation rates critically impacted PCM crystallization kinetics and properties.

Kinetics study and fragility of (Cu50Zr43Al7)98Y2 bulk metallic glass

Crystallization transformation kinetics and fragility of (Cu50Zr43Al7)98Y2 bulk metallic glass (BMG) were investigated at non-isothermal and isothermal conditions by differential scanning calorimetry. Activation energies for the BMG were calculated for the glass transition, onset crystallization, and crystallization peak using various methods of non-isothermal analysis. Results suggested that atomic rearrangement during glass transition is more complex than crystallization, and growth poses greater challenges than nucleation. Isothermal analysis conducted in the supercooled liquid region provides evidence of crystallization being controlled by diffusion, with a calculated mean Avrami exponent of 2.2. Additionally, the findings of fragility studies and kinetic studies demonstrated a strong correlation with the glass-forming ability (GFA), thereby validating the high GFA of the BMG analyzed in this study. Thus, this research results provide a detailed understanding of the complex crystallization kinetics, thermal behavior, and GFA of (Cu50Zr43Al7)98Y2 BMG, emphasizing its potential in materials science applications.

Tailored Bioactive Glass Coating: Navigating Devitrification Toward a Superior Implant Performance.

The development of well-adherent, amorphous, and bioactive glass coatings for metallic implants remains a critical challenge in biomedical engineering. Traditional bioactive glasses are susceptible to crystallization and exhibit a thermal expansion mismatch with implant materials. This study introduces a novel approach to overcome these limitations by employing systematic Na2O substitution with CaO in borosilicate glasses. In-depth structural analysis (MD simulations, Raman spectroscopy, and NMR) reveals a denser network with smaller silicate rings, enhancing thermal stability, reducing thermal expansion, and influencing dissolution kinetics. This tailored composition exhibited optimal bioactivity (in vitro formation of bone-like apatite within 3 days) and a coefficient of thermal expansion closely matching Ti-6Al-4V, a widely used implant material. Furthermore, a consolidation process, meticulously designed with insights from crystallization kinetics and the viscosity-temperature relationship, yielded a crack-free, amorphous coating on Ti-6Al-4V substrates. This novel coating demonstrates excellent cytocompatibility and strong antibacterial action, suggesting superior clinical potential compared with existing technologies.

Effect of Ni addition on the crystallization behaviors of Cr-Co alloy

Optimizing the crystallization kinetics of Cr-Co alloys through doping is of practical significance to their industrial applications. By employing molecular dynamics (MD) simulations, this study investigates the effect of Ni concentration on the solidification process of Cr30Co70-xNix (x=0, 10, 20, 30, 40) alloys, focusing on crystallization behavior during quenching and microstructural characterization. The evolution of potential energy indicates that higher Ni concentrations promote crystallization, resulting in a lower liquid-solid transition temperature and enhanced relaxation. However, Ni doping does not alter the preference for chemical ordering, with Cr-Co bonding predominant across all the compositions. Microstructural analysis reveals a shift towards fcc-dominant ternary alloys with increased Ni content. Furthermore, Ni addition impacts defect distribution, notably reducing "other" types of defects in the Cr-Co binary alloy. These findings provide a quantitative reference for adjusting the crystallization behavior of Cr-Co alloys through doping, with implications for their design, manufacturing, and utilization.

Scaling Up Perovskite Solar Cell Fabrication: Antisolvent‐Controlled Crystallization of Printed Perovskite Semiconductor

Scaling up perovskite solar cells stands as one of the frontiers in advancing this rapidly growing technology. Yet, controlling perovskite thin‐film crystallization during and post‐printing differs significantly from lab‐scale processes that have yielded record device efficiencies. This study investigates antisolvent treatment for slot‐die‐coated perovskite solar cells using in situ optical spectroscopy and comparing among multiple antisolvents. The antisolvent bath used in slot‐die coating affects the perovskite crystallization and film quality differently when comparing to the established spin‐coating antisolvent treatment process. A novel dynamic antisolvent method, employing either vortex or laminar flow, is developed. It outperforms steady‐bath techniques in generating high‐quality, haze‐free films. Optimization studies identify critical treatment times. Implementing this novel antisolvent treatment leads to a peak average power conversion efficiency of 15.62% and the highest device efficiency of 18.57%, an excellent performance for slot‐die‐coated MAPbI3 devices printed and tested under ambient conditions. The method is validated for an alternative perovskite composition, FA0.9Cs0.1PbI3, and printing technique, blade coating. This research highlights the importance of in situ analysis for enhancing perovskite film quality and introduces scalable approaches for controlling large‐area film crystallization kinetics, driven by the demand for efficient and scalable manufacturing processes in the field of perovskite solar cells.

Phase thermal stability and low thermal stress in MgO–BaO–CaO–Al2O3–B2O3–SiO2 glass-ceramic for long-term solid oxide fuel cells

The crystallization thermal stability plays an essential role in affecting thermal stress of glass-ceramic sealant for long-term planar-type solid oxide fuel cells (SOFC) to prevent fuel leakage during operation. Due to the lack of systematic research on regulating the stable performance of glass-based sealant with the working time at operation temperature, herein, the effect of MgO on crystallization kinetics, phase stability, and thermal and mechanical properties of MgO–BaO–CaO–Al2O3–B2O3–SiO2 (MBCABS) glass-ceramic has been firstly analyzed at heat-treatment of 750 °C with working time of 1∼1000h in this work. Subsequently, the relationship evolution of crystallization thermal stability-coefficient of thermal expansion (CTE) match-thermal stress was established by Finite Element Method (FEM). The main reasons for the decrease of CTE of MBCABS glass-ceramics with low-content MgO are the precipitation of hexagonal BaAl2Si2O8 phase and the transformation of hexagonal BaAl2Si2O8 to low-CTE monoclinic BaAl2Si2O8 phase, bring about that the Von Mises thermal stress of sealant itself and interface having tripled at 1000h (more than 200 MPa) according to FEM simulation results. The thermal stable and high-CTE BaMgSiO4, Ba8Mg16Si16O56, and BaCa2Mg(SiO4)2 phases crystallized in MBCABS glass-ceramics with high-content MgO, therefore the maximum stress at all time parameters was below 100 MPa for 1∼1000h. This study was useful for identifying the optimal phase option and CTE matching of glass-based sealant for efficient and stable long-term operation of solid oxide fuel cells.

Effects of the concentration of seeds, finite time-dependent supersaturations, and viscosity on the crystallization kinetics of monosodium urate monohydrate.

Although the crystallization of monosodium urate monohydrate (MSUM) has a crucial role in the occurrence of gout, which is an inflammatory arthritis disease, theoretical models have not been able to describe all features observed in its seeded growth kinetics. In contrast to previous modeling approaches, we show that our model can reproduce qualitative features typically observed in experiments. In particular, our results show that the higher the initial supersaturation and the lower the viscosity, the faster the crystallization kinetics, and they also indicate that there are distinct growth regimes for low and high concentrations of seeds. In this work, we introduce an alternative approach based on a master equation that allows us to incorporate hypotheses for the seeded growth crystallization of MSUM in a more transparent way. Such an approach includes not only effects that are related to the finite time-dependent supersaturation and concentration of seeds, but it can also be used to determine how the viscosity of the solution can affect the crystallization kinetics of MSUM molecules.

Harvesting nucleating structures in nanoparticle crystallization: The example of gold, silver, and iron.

The thermodynamics and kinetics of nanoparticle crystallization, as opposed to bulk phases, may be influenced by surface and size effects. We investigate the importance of such factors in the crystallization process of gold, silver, and iron nanodroplets using numerical simulations in the form of molecular dynamics combined with path sampling. This modeling strategy is targeted at obtaining representative ensembles of structures located at the transition state of the crystallization process. A structural analysis of the transition state ensembles reveals that both the average size and location of the critical nucleation cluster are influenced by surface and nanoscale size effects. Furthermore, we also show that transition state structures in smaller nanodroplets exhibit a more ordered liquid phase, and differentiating between a well-ordered critical cluster and its surrounding disordered liquid phase becomes less evident. All in all, these findings demonstrate that crystallization mechanisms in nanoparticles go beyond the assumptions of classical nucleation theory.

IoT-driven reflectance-based multimode colorimeter for real-time monitoring of crystallization process: A study on oleogels

This study explores the application of an Internet of Things (IoT)-driven reflectance-based multimode colorimeter for real-time monitoring of the crystallization process in oleogels-a novel class of structured lipids gaining popularity in the food industries. These structured lipids offer a healthier alternative to solid fats, but their texture and stability rely on precise control of crystallization process. Traditional monitoring methods, such as atomic force microscopy and spectroscopy, are expensive and lack real-time capabilities. The proposed device can operate in two modes: quality testing and process monitoring modes. In the quality testing mode, the device exhibits superior color accuracy compared to a commercial device, making it a reliable tool for color assessment (ΔE values < 10). In the process monitoring mode, the device effectively tracks crystallization kinetics at different incubation temperatures (5 °C, 15 °C, and 25 °C), revealing the impact of sunflower lecithin on primary and secondary crystallization phases. Further, the temperature vs. L* data offers more profound insights into oleogel crystallization, validated by Differential Scanning Calorimetry (DSC) analysis. Additionally, the device's performance was tested by monitoring the crystallization process of butter. The results obtained from the device closely matched the DSC findings, which enhanced our understanding of the crystallization processes in butter. This showcases the potential of the device for analyzing food samples.

Mechanistic investigation of nucleation kinetics in heterogeneous ice crystallization: the role of cooling rate, surface energy, surface nanostructure, and wetting state

The mechanism of nucleation in heterogeneous ice crystallization is important but remains unclear in spite of decades-long research. This study aims at investigating the nucleation kinetics in heterogeneous ice crystallization through molecular dynamics simulations, and comprehensively elucidating the effect of cooling rate, surface energy, surface nanostructure, and wetting state on the nucleation behaviours. More than 300 cases were simulated using monatomic water (mW) model based on a modified Stillinger-Weber (SW) potential. The dynamic nucleation and crystallization behaviours, along with the evolution of the largest ice nucleus, total ice clusters, kinetic energy, and interaction energy between nanodroplet and substrate, were investigated. Increasing the cooling rate and higher surface energy could promote the ice nucleation, but may lead to a tendency to transform into metastable interfacial ice and 4-coordinated molecule types, and create ice-free layer near the substrate due to the strong interaction strength. What's more, the effect of size match between the accessible width and ice lattice constant depends on the wetting states. In Cassie-Baxter state, the size match effect could promote the ice nucleation, while in Wenzel state it is not pronounced and decreasing the contact area by increasing the nanogroove width would inhibit the nucleation process. This work will be valuable in understanding the mechanism of nucleation kinetics in heterogeneous ice crystallization and provide guidance in promoting or inhibiting ice formation.

Synergistic Crystallization Modulation and Defects Passivation in Kesterite via Anion-Coordinate Precursor Engineering for Efficient Solar Cells.

It has been validated that enhancing crystallinity and passivating the deep-level defect are critical for improving the device performance of kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. Coordination chemistry interactions within the Cu-Zn-Sn-S precursor solution play a crucial role in the management of structural defects and the crystallization kinetics of CZTSSe thin films. Therefore, regulating the coordination environment of anion and cation in the precursor solution to control the formation process of precursor films is a major challenge at present. Herein, a synergetic crystallization modulation and defect passivation method is developed using P2S5 as an additive in the CZTS precursor solution to optimize the coordination structure and improve the crystallization process. The alignment of theoretical assessments with experimental observations confirms the ability of the P2S5 molecule to coordinate with the metal cation sites of CZTS precursor films, especially more liable to the Zn2+, effectively passivating the Zn-related defects, thereby significantly reducing the defect density in CZTSSe absorbers. As a result, the device with a power conversion efficiency of 14.36% has been achieved. This work provides an unprecedented strategy for fabricating high-quality thin films by anion-coordinate regulation and a novel route for realizing efficient CZTSSe solar cells.

Diffusionless rotator-crystal transitions in colloidal truncated cubes.

Upon osmotic compression, rotationally symmetric faceted colloidal particles can form translationally ordered, orientationally disordered rotator mesophases. This study explores the mechanism of rotator-to-crystal phase transitions where orientational order is gained in a translationally ordered phase, using rotator-phase forming truncated cubes as a testbed. Monte Carlo simulations were conducted for two selected truncations (s), one for s = 0.527 where the rotator and crystal lattices are dissimilar and one for s = 0.572 where the two phases have identical lattices. These differences set the stage for a qualitative difference in their rotator-crystal transitions, highlighting the effect of lattice distortion on phase transition kinetics. Our simulations reveal that significant lattice deviatoric effects could hinder the rotator-to-crystal transition and favor arrangements of lower packing fraction instead. Indeed, upon compression, it is found that for s = 0.527, the rotator phase does not spontaneously transition into the stable, densely packed crystal due to the high lattice strains involved but instead transitions into a metastable solid phase to be colloquially referred to as "orientational salt" for short, which has a similar lattice as the rotator phase and exhibits two distinct particle orientations having substitutional order, alternating regularly throughout the system. This study paves the way for further analysis of diffusionless transformations in nanoparticle systems and how lattice-distortion could influence crystallization kinetics.

Anethole Regulated Crystallization for High Efficiency Carbon‐Based Perovskite Solar Cells

AbstractTwo‐step sequential deposition is a widespread technique for the fabrication of perovskite films, renowned for its better control of the crystallization process. However, achieving a well‐controlled and complete reaction of PbI2 by organic ammonium salts remains a key challenge. Previous studies have predominantly focused on regulating the properties of the PbI2 layer while paying less attention to the high reactivity of organic ammonium salts. In this study, the natural molecule anethole is first explored to control perovskite crystallization during two‐step sequential deposition, focusing on the reactivity modulation of organic formamidine ion (FA+). It is demonstrated that FA+ exhibits strong hydrogen bond interactions with anethole, inhibiting the high reactivity of FA+ and effectively delaying the rapid reaction between FAI and PbI2. This decelerates the crystallization kinetics of perovskite films, facilitating the orderly and complete reaction of PbI2 by FAI while suppressing detrimental δ‐phase formation. Consequently, FA‐based perovskite films with high crystallinity, preferred orientation, and low defect state density are obtained. The fabricated planar hole transport layer‐free carbon electrode perovskite solar cells deliver an efficiency of 20.41% (certified efficiency of 20.0%), which is a new record for this kind of solar cell.

Controlling Water for Enhanced Homogeneities in Perovskite Solar Cells with Remarkable Reproducibility

AbstractTwo‐step sequential deposition of perovskite films is proven efficient and compatible with large‐scale production. Nevertheless, its critically regulated environmental humidity often remains a burden, hindering its applications in reproducible fabrication of perovskite solar cells (PSCs). Herein, by introducing a water ethyl acetate (W‐EA) solution treatment before annealing, improved perovskite crystallinity and homogeneity in FA0.95‐xMAxCs0.05PbI3 films without additional composition regulation is achieved. In situ Grazing‐incidence Wide‐angle X‐ray Scattering experiments highlighted accelerated crystallization kinetics in W‐EA‐treated films, leading to high‐quality perovskite formation. PSCs based on this method reached an optimal power conversion efficiency of 25.01% and demonstrated enhanced moisture resistance, retaining 88% efficiency after 1000 h in ambient conditions. This W‐EA treatment simplifies the fabrication process, greatly reducing the need for controlled humidity, and offers insights into the role of water in perovskite film crystallization, with significant implications to produce high‐performance PSCs.

Crystallization of Poly(ethylene terephthalate): A Review.

Poly(ethylene terephthalate) (PET) is a thermoplastic polyester with excellent thermal and mechanical properties, widely used in a variety of industrial fields. It is a semicrystalline polymer, and most of the industrial success of PET derives from its easily tunable crystallization kinetics, which allow users to produce the polymer with a high crystal fraction for applications that demand high thermomechanical resistance and barrier properties, or a fully amorphous polymer when high transparency of the product is needed. The main properties of the polymer are presented and discussed in this contribution, together with the literature data on the crystal structure and morphology of PET. This is followed by an in-depth analysis of its crystallization kinetics, including both primary crystal nucleation and crystal growth, as well as secondary crystallization. The effect of molar mass, catalyst residues, chain composition, and thermo-mechanical treatments on the crystallization kinetics, structure, and morphology of PET are also reviewed in this contribution.