Crystallization Kinetics Research Articles

Perfluorinated Anionic Surfactant Assisted Homogeneous Crystallization for Efficient and Stable Formamidinium‐Based Sn‐Pb Perovskite Solar Cells

AbstractFormamidinium (FA)‐based Sn‐Pb perovskite demonstrates superior thermal stability, making it well‐suited for all‐perovskite tandem solar cells. However, the uncontrolled crystallization process remains a significant challenge. In this study, an effective strategy is presented to regulate the crystallization of FA‐based Sn‐Pb perovskite by incorporating perfluoroanionic surfactant (perfluorohexanesulfonic acid potassium salt, F13C6SO3K) into the perovskite precursor. The multifunctional sites of F13C6SO3K, including F atoms and SO3− groups, interact with perovskite components to stabilize the colloidal distribution of the precursor and modulate the crystallization kinetics. This results in high‐quality perovskite films with fewer defects. Consequently, the FA‐based Sn‐Pb perovskite solar cell (PSC) achieves a champion efficiency of 24.33%, with an open‐circuit voltage of 0.895 V and a fill factor of 83.2%. After continuous heating at 65 °C for 1008 h, it still maintain 91% of its initial efficiency, which shows enhanced stability. When coupled with a wide‐bandgap subcell, the all‐perovskite tandem solar cell reaches a champion power conversion efficiency (PCE) of 27.57%.

Influence of Low Loadings of Cellulose Nanocrystals on the Simultaneously Enhanced Crystallization Rate, Mechanical Property, and Hydrophilicity of Biobased Poly(butylene 2,5-furandicarboxylate)

In this research, fully biobased composites consisting of poly(butylene 2,5-furandicarboxylate) (PBF) and cellulose nanocrystals (CNC) were successfully prepared through a common solution and casting method. The influence of CNC on the crystallization behavior, mechanical property, and hydrophilicity of PBF was systematically investigated. Under different crystallization processes, the crystallization of PBF was obviously promoted by CNC as a biobased nucleating agent. The Ozawa equation was not suitable to fit the nonisothermal melt crystallization kinetics of PBF and PBF/CNC composites. The nucleation activity of CNC was quantitatively calculated by the Dobreva method; moreover, the nucleation efficiency of CNC was further evaluated through the self-nucleation procedure. The isothermal melt crystallization kinetics of PBF and PBF/CNC composites was well described by the Avrami method; moreover, the crystallization mechanism and the crystal structure of PBF remained unchanged despite the presence of CNC. CNC also greatly enhanced both the mechanical property and hydrophilicity of PBF in the composites. In sum, low loadings of CNC simultaneously improved the crystallization, mechanical property, and hydrophilicity of PBF, which should be of significant importance and interest in fully biobased polymer composites from a sustainable viewpoint.

Effect of NiO, CuO, Co3O4, and Fe2O3 on the crystallization kinetics of glasses based on slags from joint smelting of silicate nickel and copper pyrite ores

ABSTRACT The effect of modification by addition of 6% by mass of a mixture of NiO, CuO, and Co3O4 taken in equal mass portions with the replacement of half of FeO by Fe2O3 of glass (<0.1 mm) based on slag from joint smelting of nickel and copper ores on kinetics of its crystallization has been studied. Using X-ray powder diffraction, scanning electron microscopy, energy-dispersive spectrometry, and differential scanning calorimetry, it was shown that modification does not change the nature of the released phases and the sequence of their appearance during crystallization. A decrease in the activation energy of crystallization from 663 to 527 kJ·mol−1 for the first period (pigeonite and anorthite release) and from 756 to 542 kJ·mol−1 for the second one (SiO2 release) without changing the process mechanism has been established. The results supplement the information necessary to substantiate non-isothermal and isothermal technological modes of glass processing to obtain glass-ceramics.

Effect of Crystallinity on the Printability of Poly(ethylene Terephthalate)/Poly(butylene Terephthalate) Blends

This study explores the impact of blending polyethylene terephthalate (PET) with polybutylene terephthalate (PBT) on the thermal, structural, and mechanical properties of 3D-printed materials. Comprehensive analyses, including Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and mechanical testing, were conducted to assess the influence of blend composition. FT-IR confirmed that PET and PBT blend physically without transesterification, while TGA showed enhanced thermal stability with increasing PET content. XRD revealed that PET and PBT crystallize separately, with the crystallinity decreasing sharply for blends with more than 50% PET. The DSC results indicated that PET effectively slows down the crystallization kinetics of PBT, promoting cold crystallization. Mechanical tests demonstrated that the elastic modulus remains relatively unchanged, but the strain at break decreases with a higher PET content, indicating increased stiffness and reduced ductility. Overall, incorporating PET into PBT improves 3D-printability and dimensional stability, reducing warpage and enhancing print precision, making these blends advantageous for 3D-printing applications.

Uniform single-crystal mesoporous metal-organic frameworks.

The synthesis of mesoporous metal-organic frameworks (meso-MOFs) is desirable as these materials can be used in various applications. However, owing to the imbalance in structural tension at the micro-scale (MOF crystallization) and the meso-scales (assembly of micelles with MOF subunits), the formation of single-crystal meso-MOFs is challenging. Here we report the preparation of uniform single-crystal meso-MOF nanoparticles with ordered mesopore channels in microporous frameworks with definite arrangements, through a cooperative assembly method co-mediated by strong and weak acids. These nanoparticles feature a truncated octahedron shape with variable size and well-defined two-dimensional hexagonally structured (p6mm) columnar mesopores. Notably, the match between the crystallization kinetics of MOFs and the assembly kinetics of micelles is critical for forming the single-crystal meso-MOFs. On the basis of this strategy, we have constructed a library of meso-MOFs with tunable large pore sizes, controllable mesophases, various morphologies and multivariate components.

Multifunctional Organic Molecule for Defect Passivation of Perovskite for High-Performance Indoor Solar Cells.

Perovskite solar cells (PSCs) can utilize the residual photons from indoor light and continuously supplement the energy supply for low-power electron devices, thereby showing the great potential for sustainable energy ecosystems. However, the solution-processed perovskites suffer from serious defect stacking within crystal lattices, compromising the low-light efficiency and operational stability. In this study, we designed a multifunctional organometallic salt named sodium sulfanilate (4-ABS), containing both electron-donating amine and sulfonic acid groups to effectively passivate the positively-charged defects, like under-coordinated Pb ions and iodine vacancies. The strong chemical coordination of 4-ABS with the octahedra framework can further regulate the crystallization kinetics of perovskite, facilitating the enlarged crystal sizes with mitigated grain boundaries within films. The synergistic optimization effects on trap suppression and crystallization modulation upon 4-ABS addition can reduce energy loss and mitigate ionic migration under low-light conditions. As a result, the optimized device demonstrated an improved power conversion efficiency from 22.48% to 24.34% and achieved an impressive efficiency of 41.11% under 1000 lux weak light conditions. This research provides an effective defect modulation strategy for synergistically boosting the device efficiency under standard and weak light irradiations.

Spatially Isomeric Fulleropyrrolidines Enable Controlled Stacking of Perovskite Colloids for High-Performance Tin-Based Perovskite Solar Cells.

The advancement of tin-based perovskite solar cells (TPSCs) has been severely hindered by the poor controllability of perovskite crystal growth and the energy level mismatch between the perovskite and fullerene-based electron transport layer (ETL). Here, we synthesized three cis-configured pyridyl-substituted fulleropyrrolidines (PPF), specifically 2-pyridyl (PPF2), 3-pyridyl (PPF3), and 4-pyridyl (PPF4), and utilized them as precursor additives to regulate the crystallization kinetics during film formation. The spatial distance between the two pyridine groups in PPF2, PPF3, and PPF4 increases sequentially, enabling PPF4 to interact with more perovskite colloidal particles. These interactions effectively enlarge the precursor colloid size and decelerate the crystallization rate of the perovskite, resulting in high-quality PPF4-based perovskite films with reduced defect density and lower exciton binding energy. Additionally, we incorporated a well-defined fullerene bis-adduct, C60BB, as an interlayer between the perovskite and PCBM layers to optimize energy level alignment. Through the synergistic effects of PPF4 and C60BB, our champion device achieved an efficiency of 16.05 % (certified: 15.86 %), surpassing the 16 % efficiency bottleneck and setting a new benchmark for TPSCs. Moreover, the devices exhibited outstanding stability, retaining 99 % of their initial efficiency after 600 hours of maximum power point tracking under 1 sun condition.

Synthesis, characterization, crystallization kinetics of amorphous Fe74.5Zr8.5B17 magnetic nanoparticles, and magnetoelectric properties of Fe74.5Zr8.5B17/BaTiO3 composite

This work reports the facile synthesis of amorphous Fe74.5 Zr8.5 B17 magnetic nanoparticles (MNPs) through a simple NaBH4-assisted chemical reduction method. The obtained MNPs were characterized in terms of amorphous/crystal structure, morphology, magnetic properties, composition, and crystallization kinetics. The saturation magnetization value was determined as 57.83 emu/g. The crystallization peak temperatures (Tp) and activation energy were determined to be 467.18 °C and 294 kJ/mol, respectively. Additionally, the FeZrB MNPs were combined with the BaTiO3 NPs via ball milling at low speed, using a mass ratio of 30/70%, respectively and the magnetoelectric coefficient value for FeZrB/BaTiO3 composite measured at a 1 kHz AC magnetic field is approximately 8.9 mV/Oe/cm. The study outcomes may provide a platform of nanotechnology for the preparation of MNPs with adjustable properties, which will be promising for practical applications.

Comparative study of crystallization kinetics and phase segregation of triple cation and methylammonium lead iodide perovskites on moisture probing using synchrotron X-ray based radiation.

3D mixed perovskites have achieved substantial success in boosting solar cell efficiency, but the complicated perovskite crystal formation pathway remains mysterious. Here we present detailed crystallization kinetics of mixed perovskites FA0.83MA0.17Pb(I0.83Br0.17)3, where FA is formamidinium and MA is methylammonium, with the addition of Cs+ to form a triple cation perovskite (3-CAT), in a comparison with the perovskite building block MAPbI3 (MAPI) via static grazing-incidence wide-angle X-ray scattering (GIWAXS) and micro-diffraction measurements. Spin-coated films produced α-perovskite peaks with no PbI2 or δ-intermediate phases, which was a promising result for the 3-CAT perovskite from micro-diffraction measurements. However, the 3-CAT did not remain stable on probing with varied relative humidity (RH) conditions as segregation back to the δ-intermediate and PbI2 phase after 10 s of exposure to an RH value of 11% was found to occur from the GIWAXS results. When RH levels were elevated to over 100%, segregation peaks of PbI2 and δ-intermediate (2H, 4H and 6H) became conspicuous as the α-phase intensity diminished, unlike for MAPI that remains relatively stable. The possible cause of this is hydrophilic bonds that form between the 3-CAT crystals and the small annealing window of the best composition perovskite (5% Cs+) film.

Structural properties and recrystallization effects in ion beam modified B20-type FeGe films

Disordered iron germanium (FeGe) has recently garnered interest as a testbed for a variety of magnetic phenomena as well as for use in magnetic memory and logic applications. This is partially owing to its ability to host skyrmions and antiskyrmions—nanoscale whirlpools of magnetic moments that could serve as information carriers in spintronic devices. In particular, a tunable skyrmion–antiskyrmion system may be created through precise control of the defect landscape in B20-phase FeGe, motivating the development of methods to systematically tune disorder in this material and understand the ensuing structural properties. To this end, we investigate a route for modifying magnetic properties in FeGe. In particular, we irradiate epitaxial B20-phase FeGe films with 2.8 MeV Au4+ ions, which creates a dispersion of amorphized regions that may preferentially host antiskyrmions at densities controlled by the irradiation fluence. To further tune the disorder landscape, we conduct a systematic electron diffraction study with in situ annealing, demonstrating the ability to recrystallize controllable fractions of the material at temperatures ranging from ∼150 to 250 °C. Finally, we describe the crystallization kinetics using the Johnson–Mehl–Avrami–Kolmogorov model, finding that the growth of crystalline grains is consistent with diffusion-controlled one-to-two dimensional growth with a decreasing nucleation rate.

Investigation of silica crystallization kinetics in rice husk ash for sustainable construction materials

Concrete is one of the most widely used materials in the world, and its utilization is rising drastically with the increasing population. Around 5-8% of global carbon emissions are caused by cement production. On the other hand, approximately 160 million tons of rice husk, considered agrowaste, turn into ash annually. Rice husk ash (RHA) is particularly attractive due to its high silica content and great potential to be used as a cementitious material. However, impurities such as alkali metal oxides and uncontrolled combustion reduce the quality of silica and promote its crystallization. Numerous studies have focused on obtaining active silica through acid leaching to remove impurities, but the study on the reaction kinetics of functionalized rice husk ash is very limited. In this research, 0.1M hydrochloric acid (HCl) was used to leach rice husk at temperatures of 50°C, 60°C, and 70°C for 1.5 hours. The rice husk was then burned at 800°C for 2 hours. Subsequently, the ash was examined using various analytical and computational techniques to develop an in-depth understanding of the burning process, aimed at producing functionalized amorphous silica for sustainable construction. It was observed that 99.39% silica with 95.04% amorphous content was formed by treating rice husk with 0.1M HCl at 70°C for 1.5 hours, followed by combustion at 800°C for 2 hours. Furthermore, reaction kinetics parameters were identified using the Coats-Redfern kinetic model for the two different reaction zones of the burning process.

Revealing the crystallization kinetics of melt-quenched GeTe for realistic phase-change memory applications

Revealing the crystallization kinetics of melt-quenched GeTe for realistic phase-change memory applications

Manipulating Crystallization Kinetics and Vertical Phase Distribution via Small Molecule Donor Guest for Organic Photovoltaic Cells with 20% Efficiency

Precise control over molecular crystallization and vertical phase distribution of photovoltaic bulk-heterojunction (BHJ) films is crucial for enhancing their optoelectronic properties toward high-performing polymer solar cells (PSCs). Herein, a kinetics-controlling...

Stretchable Primary-Blue Color-Conversion Layer: In Situ Crystallization of Phase-Engineered Perovskite Nanocrystals in an Organic Matrix.

Although the use of ultraviolet (UV) light-emitting diode backlight with red, green, and blue color-conversion layers (CCLs) in displays simplifies the manufacturing process and improves display uniformity, research on blue CCLs remains limited and has been mostly reported in the sky-blue region (> 470 nm), which is insufficient to satisfy the Rec. 2020 color standard. As halide perovskites offer a high extinction coefficient, color purity, and photoluminescence quantum yield (PLQY), they become highly competitive color-converting materials for CCLs. This work presents a simple method for the in situ fabrication of perovskite nanocrystal (NC) films for primary-blue CCL and additionally proposes a set of scientific guidance rules regarding significant factors that affect the nucleation and in situ crystallization kinetics of perovskite NCs. The fabricated films are highly stretchable, emit bright primary-blue light (∼460 nm), and have PL that is tolerant to UV irradiation. By introducing fluorinated arylammonium salts, the quantum and dielectric confinement effects are desirably adjusted, which induces efficient energy transfer processes for primary-blue emission. This strategy yields phase-engineered perovskite NCs embedded in an organic matrix, which enables spectrally stable and robust PL under high tensile strain (> 250%) and after prolonged UV irradiation (> 40 d). Consequently, this work demonstrates that the in situ fabricated stretchable blue CCLs achieve 100% agreement with Rec. 2020.

Regulated Crystallization Through Intermolecular Interactions Bridging for Efficient Tin‐Based Perovskite Solar Cells

AbstractTin halide perovskite (THP) has emerged as a promising lead‐free material for high‐performance solar cells, attracting significant attention for their potential use for energy conversion. However, the rapid crystallization of THP due to its high Lewis acidity and easy oxidation of Sn2+ leads to poor morphology and rampant defects in the resulting perovskite films. These strongly hamper the advances in efficiency and stability in THP solar cells. Herein, a comprehensive crystallization regulation strategy is demonstrated by introducing methyl carbazate (C2H6N2O2, MeC) to regulate the crystallization kinetics of perovskite through inter‐molecular interactions. The coordination bonds (O…Sn) and hydrogen bonds (N─H…O) between MeC and perovskite bridge the perovskite lattice together, helping suppress the oxidation of Sn2+, meanwhile, restraining the fast crystallization of perovskite in the precursor solution, by enhancing nucleation sites. More importantly, the connection by MeC can reduce the deep‐level trap state defect density, significantly restraining non‐radiative recombination and improving the carrier lifetime. Consequently, this facile strategy offers valuable insights into THP crystallization kinetics and allows an enhanced high power conversion efficiency from 10.43% to 14.02% to be achieved with good stability.

Generation of Bio-Based, Shape- and Temperature-Stable Three-Dimensional Nonwoven Structures Using Different Polyhydroxyalkanoates.

Recent research has shown the potential of polyhydroxyalkanoates (PHAs), particularly poly(3-hydroxybutyrate) (P3HB), to form nonwoven structures with fine fiber diameter distributions ranging from 2.5 µm to 20 µm during the meltblow process. The shortcomings of existing fabrics of this type include high brittleness, low elongation at break (max. 3%), and a lack of flexibility. Furthermore, the high melt adhesion and the special crystallization kinetics of PHAs have commonly been regarded as constraints in filament and nonwoven processing so far. However, these two properties have now been used to elaborate a three-dimensional fiber arrangement on a matrix, resulting in the creation of dimensionally and temperature-stable "nonwoven-parts". Moreover, this study investigated the PHA copolymer poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), revealing a similar processability to P3HB and PHBV in the meltblow process. A significant increase in the (peak load) elongation in the machine direction was observed, reaching values between 5% and 10%, while the tensile strength retained unaltered. The addition of the bio-based plasticizer acetyltributylcitrate (ATBC) to PHBH resulted on an increase in elongation up to 15%. The three-dimensional fabric structure of PHBH exhibited complete resilience to compression, a property that differentiates it from both P3HB and PHBV. However, the addition of the plasticizer to P3HB did not lead to any improvements. This interesting array of properties results in moderate air permeability and hydrophobicity, leading to impermeability to water.

Influence of centrifugal casting parameters on Al-Mg alloy castings microstructure and mechanical properties

The paper is dedicated to the process of obtaining hollow castings on a horizontal centrifugal casting machine. The influence of mold rotation speed and the melt pouring process mechanical properties of as-cast parts made of AlMg5, alloyed by small amount of transition and rare earth metals, is represented. Mold pouring processes and crystallization kinetics depend on mold rotational speeds 1100, 1500 and 2000 rpm were studied by using numerical modeling. The influence of the specified mold rotation speeds on the structure and mechanical properties of castings is shown. It is also determined that the installation of a foam ceramic filter in the pouring cup of a centrifugal casting machine ensures melt laminar flow when pouring it into a mold. It was determined that 1500 rpm is the most favorable rotating speed from the points of optimal hydrodynamic mold filling processes and casting crystallization kinetics. It was also shown that with the increase of a mold rotation speed from 1100 to 2000 rpm, the thickness of the defective inner layer decreases, the alloy structure refines, and the mechanical properties of as-cast detail increase the next way: at 1500 rpm (σ0.2–by 10%, σB − by 25%, δ − 3 times), at 2000 rpm (σ0.2–by 18%, σB − by 31%, δ − 4 times), compared to products obtained by steel mold gravity casting. Centrifugal casting technology ensures the mechanical properties of cast blanks even higher than those of deformed AlMg5 alloys, the values of which approach those of AlMg6 alloy products.

Simultaneous Improvement of Oxygen Barrier and Stiffness in High-Density Polyethylene via Effective Integration of Interface Engineering with in Situ Ethylene-Vinyl Alcohol Copolymer Nanofibrillation.

In this study, we proposed a novel technique to simultaneously enhance the oxygen barrier properties and stiffness of high-density polyethylene (HDPE) while preserving its ductility. By utilizing in situ nanofibrillation, fiber-in-fiber composites of an HDPE matrix and ethylene-vinyl alcohol (EVOH) nanofibers were fabricated. Due to the high interfacial tension between HDPE and EVOH, stemming from their differences in chemical structure and polarity, styrene/ethylene-butylene/styrene copolymer grafted with maleic anhydride (SEBS-g-MA) was used as a compatibilizer to improve the affinity between the two polymers. SEM images revealed that the presence of the compatibilizer resulted in smaller fiber sizes (reduced to 65 ± 27 nm from 147 ± 54 nm for 6 wt % compatibilized EVOH compared to noncompatibilized samples), higher aspect ratios, and better distribution. Increasing the aspect ratio and improving nanofiber distribution reduced HDPE's oxygen permeability by 61% after incorporating 10 wt % compatibilized EVOH nanofibers. Additionally, the nonisothermal and isothermal crystallization indicated that EVOH nanofibers reduced the amount of crystallinity and slowed crystallization kinetics. The alteration in HDPE crystalline structure and its effect on permeability properties were also addressed. Finally, tensile test results indicated that the incorporation of 10 wt % EVOH nanofibers, regardless of the presence of the compatibilizer, increased HDPE Young's modulus by around 50%. However, without the compatibilizer, there was a significant reduction in HDPE elongation at the break. The incorporation of the compatibilizer allowed for increased stiffness while preserving HDPE ductility. These promising findings underscore potential applications across rigid and soft packaging.

Classical View on Nonclassical Crystal Growth in a Biological Setting.

Crystallization by amorphous particle attachment, a nonclassical crystal growth mode, is prevalent in minerals formed by living tissues. It allows the organism to intervene at every step of crystal growth, i.e., particle formation, stabilization, accretion, and crystallization, and thus to orchestrate biomineral morphogenesis and crystallographic texturing; all toward achieving a required functionality for the organism. Therefore, significant effort is aimed at achieving similar control and crystal growth tunability through bioinspired and biomimetic synthetic means. This Perspective examines the driving forces and the kinetics of crystallization by amorphous particle attachment in a biological setting, and through an analogy to classical molecule-by-molecule crystallization, it establishes distinct crystal growth mechanisms. It underlines the role of physics and chemistry of materials in the "Growth and Form" of biogenic minerals.

Effect of Mixed Surfactant on Evaporation Driven Salt Crystallization Morphology in Sessile Droplets.

Extensive studies have been conducted to manipulate the morphology of sodium chloride salt crystals to tailor their physical and chemical properties. Among the myriad factors considered, the effects of the substrate and additives have profound impacts on the types of salt depositions. Surface charge effects and various ionic surfactants influence ion movement, resulting in diverse crystal morphologies. This manuscript aims to provide a consolidated summary by concurrently studying multiple effects to uncover the salt crystal morphology under the influence of two oppositely charged ionic surfactants on charged and neutral surfaces. The cationic surfactant cetyltrimethylammonium bromide induces skeletal crystal growth by retarding salt precipitation until supersaturation is reached. Conversely, the anionic surfactant sodium dodecyl sulfate hinders ion diffusion at the three-phase contact line. Each surfactant effect is dominant at higher molar concentrations. Surface charge affects the amount of surface adsorption and free-moving ions within the saline surfactant droplets, greatly influencing the number of salt crystals formed on the neutral substrate. However, charge neutralization at the highest concentrations of both surfactants nullifies the surface charge effect, resulting in practically indistinguishable salt crystals with similar sizes and numbers, leading to only a small area difference of 1461 μm2. This study provides insights into the kinetics of crystallization under the combined influence of anionic, cationic, and surface charge interactions. The findings can serve as a future reference for predicting and controlling ionic interactions and crystal morphology.