Crystal Growth Mechanism Research Articles

Organic Molecules Induce the Formation of Hopper-Like NaCl Crystals under Rapid Evaporation As Microcatalytic Reactors To Facilitate Micro/Nanoplastic Degradation.

As representative examples of inorganic ionic crystals, NaCl and KCl usually form cubes during the natural evaporation process. Herein, we report the hopper-like NaCl and KCl crystals formed on the iron surface under rapid vacuum evaporation aided by organic molecules. Theoretical and experimental results indicate that it is attributed to the organic molecules alternating adsorption between {100} and {110} surfaces instead of adsorbing a single surface, as well as the fast crystal growth rate. Following this law, we found hopper-like crystals formed under natural evaporation conditions in salt lake crystals as well as synthesized kilogram-class hopper-like crystals. Interestingly, the hopper-like crystals can act as microcatalytic reactors to efficiently facilitate micro/nanoplastic degradation with ∼91.72% styrene yield, highly decreasing the degradation temperature from ∼400 to ∼275 °C. These findings provide an understanding of the growth mechanism of various crystals and a friendly environmental, low-carbon, and economical microcatalytic reactor for efficient micro/nanoplastic degradation.

Recent Progress and Advances of Perovskite Crystallization in Carbon-Based Printable Mesoscopic Solar Cells.

Carbon-based printable mesoscopic solar cells (p-MPSCs) offer significant advantages for industrialization due to their simple fabrication process, low cost, and scalability. Recently, the certified power conversion efficiency of p-MPSCs has exceeded 22%, drawing considerable attention from the community. However, the key challenge in improving device performance is achieving uniform and high-quality perovskite crystallization within the mesoporous structure. This review highlights recent advancements in perovskite crystallization for p-MPSCs, with an emphasis on controlling crystallization kinetics and regulating perovskite morphology within confined mesopores. It first introduces the p-MPSCs, offering a solid foundation for understanding their behavior. Additionally, the review summarizes the mechanisms of crystal nucleation and growth, explaining how these processes influence the quality and performance of perovskites. Furthermore, commonly applied strategies for enhancing crystallization quality, such as additive engineering, solvent engineering, evaporation controlling, and post-treatment techniques, are also explored. Finally, the review proposes several potential suggestions aimed at further refining perovskite crystallization, inspiring continued innovation to address current limitations and advance the development of p-MPSCs.

Realization of a 2H–Si microneedle with an ultrafast growth rate of 6.7 × 104 Å·s-1

Abstract Nanomaterials have facilitated the development of innovative technologies in various industries. However, most research has been limited to nanoscale phenomena, and the effects of nanoscale phenomena on microscale crystal growth remain obscure. In this study, we demonstrated a straight 2H-Si microneedle with a longitudinal growth rate of 6.7 × 104 Å·s-1, which could not be explained by conventional crystal growth mechanisms, through AlN nanowires. The AlN nanowires were grown using the hydride vapor-phase epitaxy method, which induced the formation of Al membranes when NH3 supply was ceased. At this time, an elliptical Al membrane was created within 0.166 s, in accordance with the principle of Plateau–Rayleigh instability. The average spacing of the Al membrane was 4 μm, and approximately 10,000 elliptical Al membranes absorbed SiCl almost simultaneously to form a 40-mm 2H-Si microneedle within 100 min of growth time. Therefore, we realized straight 2H–Si microneedles with a growth rate of 6.7 × 104 Å·s-1. Differing from the conventional growth mechanism, this new growth method sheds light on the mechanism by which nanoscale phenomena contribute to the growth of microscale crystals.

Preparation of porous ammonium dinitramide crystals and efficient catalytic decomposition of corresponding iron oxide assembled composite particles

In this paper, highly spherical and porous ammonium dinitramide (ADN) crystals were prepared by using solvent-antisolvent crystallization method. To explore the growth mechanism of ADN crystals in different solvent environments,...

Fabrication of regular UiO-66(Ce) nanocubes and their electrochemical catalysis performance

Metal-organic frameworks (MOFs), characterized with highly ordered porous structures and relatively high surface area, exhibit significant application potential in the field of electrochemistry catalysis. In this study, we successfully prepared UiO-66(Ce) particles with uniform nanocube morphology and the size distribution ranging from 90 to 156 nm. Both morphology and size can be precisely tuned by directly adjusting detailed synthesis parameters, including solvent concentration and reaction time. Moreover, the crystal growth mechanism of UiO-66(Ce) was comprehensively investigated through the microstructure characterization. Such uniform particles demonstrated a desirable electrocatalytic performance with hydrogen evolution reaction (HER) overpotential of 118.6 mV (at 10 mA cm−2) in alkaline electrolyte (1 M KOH). This study not only introduces a novel approach for the morphological manipulation of UiO-66(Ce), but also presents new material candidates for the advancement of high-performance electrochemical energy conversion systems.

Role of BPO4 flux in BaBPO5 crystal growth characterized through high-temperature Raman spectroscopy

In this study, we explored the growth of incongruently melting crystals in a starting solution with flux to better understand the role of flux in crystal growth mechanisms. We recorded the spectrum of BaBPO5 crystals across a 200-1400 cm−1 range for detailed Raman spectroscopic analysis. The observed Raman bands corresponded to the vibrations of PO4 and BO4 units. These units link with B-O-P bonds via common corners to form PBO7 groups that serve as basic structural units of the crystal. Notably, these PBO7 structures remain stable at high temperatures up to the crystal melting point, at which the isolated PO4 groups predominantly exist in the melt, as revealed by high-temperature Raman spectroscopy. Further investigations into the Raman spectra of the starting solution enriched with BPO4 self-flux indicate that PBO7 groups are crucial for crystal growth. The addition of PBO4 flux aids in the formation of these PBO7 units. This research paves the way for expanding our understanding to other systems, which will help elucidate the mechanisms behind crystal growth.

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 solution flow field on evaporation-induced NaCl crystallization in acoustically levitated droplets

Acoustically levitated droplets have exhibited great potential in crystallization studies due to their versatility with various solution types and the simplicity of the apparatus. By separating the precursor solution and the solid surface, the crystallization process could be observed and analyzed in a contactless environment. The decoupling of the crystallization system and surface physical/chemical properties greatly boosts the in situ investigation of early-stage nucleation and crystal growth mechanisms. However, the interaction between the precursor solution and applied acoustic field during the crystallization process is often neglected, which imposes significant influences on the crystal products. In this paper, visual experiments were carried out to study the NaCl crystallization process in acoustically levitated droplets. Image processing was employed to acquire the evaporation rate of the droplets, and particle image velocimetry analysis was used to characterize the flow field. Effects of droplet size and initial NaCl concentration were investigated, and the crystallization behaviors in the levitated droplet and sessile droplet were compared. The results indicate that the acoustic field introduced a forced convection of fluid within the levitated droplets, influencing the evaporation rate, supersaturation degree, and the morphology of the crystal product. The obtained mechanism is important for the application of acoustically levitated droplets and can be further applied to other crystallization research based on the acoustic levitation systems.

Fully hot Air-Processed All-Inorganic CsPbI2Br perovskite solar cells for outdoor and indoor applications

The all-inorganic α-CsPbI2Br perovskite has emerged as a promising material for photovoltaic applications due to its superior optoelectronic properties and thermal stability. However, achieving a defect-free, crystalline CsPbI2Br perovskite film remains challenging due to the rapid crystal growth induced via high-temperature hot plate processing, which causes surface defects including pinholes and voids. This study introduces a novel hot plate-free methodology in which the perovskite film is fully processed using a dynamic hot air treatment under ambient conditions. Crystallographic and microscopic analyses reveal that hot air-assisted method produces highly crystalline, uniform, and compact perovskite film. The controlled crystal growth mechanism facilitated by the hot air process involves the formation of an intermediate phase (CsI-DMSO:PbX2), followed by gradual solvent evaporation, resulting in improved film quality. The resulting perovskite solar cells (PSCs) exhibited a champion power conversion efficiency (PCE) of 13.74 % and maintained around 51.60 % of its initial PCE after thermal aging at 85 ℃ under ambient conditions over 1440 h. Furthermore, under indoor white LED illumination (3200 K, 1000 lx), the optimized PSC achieved an impressive PCE of 22.50 %. These findings demonstrate that the dynamic hot air process is a viable and scalable technique for producing high-performance, stable PSCs under ambient conditions.

Approach to Regulating Crystal Nucleation for High-Performance Lithium-Chalcogen Batteries

Chalcogen cathodes, with their high theoretical energy density, have shown promise for advancing lithium-ion battery (LIB) technology. However, the structure of chalcogen crystals significantly impacts cycle performance and could constrain rate capability due to their intrinsic insulating nature. Therefore, this study explores approaches to regulate the nucleation of chalcogen elements to enhance cycle performance beyond that of lithium-sulfur batteries.We investigate the dissolution and deposition mechanisms of the chalcogen cathode materials, as well as nucleation phenomena by using advanced techniques such as operando X-ray diffraction (XRD) and transmission X-ray microscopy (TXM). Particularly, operando TXM imaging captures the growth of chalcogen crystals, shedding light on their nucleation behavior. Expending on these discoveries, we control the crystal nucleation of the chalcogen cathodes, resulting in impressive specific capacity and improved rate capability.This work offers valuable insights into the chalcogen crystal nucleation, paving the way for high-performance lithium-sulfur batteries with improved energy densities and rate performance. Figure 1. The scheme of the chalcogen crystal growth mechanism and the corresponding cycle performance at a current density of 1.0 A g-1. Figure 1

Effective CuSO4 Concentration on Phase Formation and Optical Characteristics of Electrodeposited Ni-Cu Alloy

Ni-Cu alloys play a critical role in various industrial applications due to their exceptional characteristics. Despite extensive study of these alloys for their mechanical and corrosion characteristics, their optical properties have received limited attention. In this research, the electrodeposition of Ni-Cu alloy coatings was conducted using copper sulfate concentrations ranging from 1.25 to 10 g/L, leading to successful film formation with various phases. XRD examination associated with the Rietveld calculation exhibited modified phase fraction, crystallite size, micro-strain, and lattice constant. Scanning Electron Microscopy (SEM) analysis revealed a different thickness and a dendritic microstructure. As an increase in CuSO4, there was observed an increase in the values of the absorption edge (showing 1.61 - 1.90 eV), texture coefficient (0.46 - 0.82), and film thickness (0.63 - 1.74 µm). These various morphologies enhanced the material’s properties. In more added CuSO4 samples, the coatings significantly reveal a modification in the crystal, film growth, and optical properties. The advancements in visible light absorption suggest an enhanced coating for optical technology applications. HIGHLIGHTS The texture coefficient (TC) values of the (111) plane of Cu81Ni0.19 phase were found to increase with higher CuSO4 concentrations. Specifically, the TC values for 1.25Cu-Ni, 2.5Cu-Ni, 5.0Cu-Ni, 7.5Cu-Ni, and 10Cu-Ni were 0.46, 0.48, 0.77, 0.77, and 0.82, respectively. These values, all below 1, indicate low crystallinity but show a trend of increasing crystallinity with higher CuSO4 concentrations. The film thickness also increased with higher CuSO4 The thicknesses were 0.63 µm for 1.25Cu-Ni, 0.65 µm for 2.5Cu-Ni, 1.36 µm for 5.0Cu-Ni, 1.54 µm for 7.5Cu-Ni, and 1.74 µm for 10Cu-Ni. The grain morphology of the coatings evolved from small, elongated platelets in lower CuSO4 concentrations to larger, more dendritic structures at higher concentrations. This change in morphology is attributed to the increased CuSO4 concentration, which affects the crystal growth mechanisms during electroplating. GRAPHICAL ABSTRACT

Three Strikingly Different Crystal Habits of Tadalafil: Design, Characterization, Pharmaceutical Performance, and Computational Studies.

The present study aims at improving the physicochemical properties of a widely used drug Tadalafil through crystal habit modification, without changing the polymorphic form. Three distinct types of crystal habits, namely, needle, plate, and block, were obtained under controlled crystallization protocols with optimized solvent compositions. Complete characterization of these three crystal habits was carried out using powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and Fourier transform infrared spectroscopy. Morphological features were studied by optical and scanning electron microscopy. Evaluation of the pharmaceutical performance of different crystal habits reveals significant improvement in compressibility and flow properties for the block-shaped crystals in comparison to the needle- and plate-shaped crystals. Also, a more linear tablet compression behavior was noted for the plate and block morphologies of the API compared to their needle counterpart. In vitro dissolution studies showed distinct release profiles for the same API form with different crystal habits, i.e., needle > plate > block. Insights into crystal growth mechanism and the role of solvents in affording the observed crystal habits are presented based on molecular dynamics simulations of intermolecular interactions with crystal facets, in conjunction with the experimental crystal face indexing of the single crystals of different habits. These observations were further supported by interaction topology analysis and the electrostatic features on different crystal facets.

Ultra-micro Liquid Crystal in Cosmetic Emulsion with Excellent Moisture Retention and Delivery Selectivity.

Compared with ordinary emulsified cosmetics, liquid crystal emulsified cosmetics have obvious advantages. In this paper, an ultra-micro liquid crystal (ULC) emulsion with particle size less than 4 μm was successfully synthesized using a simple oil-in-water emulsification method, and large liquid crystal (LLC) and non-liquid crystal (NLC) emulsions were also prepared as controls. Three kinds of emulsions were examined by polarizing microscopy, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS) and cryo-transmission electron microscopy (cryo-TEM). Rheological tests, in vivo experiments, reconstructed Raman maps tracking selected markers and thermogravimetric (TG) results showed that the ULC emulsion expressed excellent viscoelasticity, long-term moisturizing property with barrier function and better selective delivery of active substances compared with LLC and NLC emulsions. Molecular dynamics simulation on the ULC system and deuterium order parameter plots respectively indicated that GYY (glyceryl stearate citrate) showed a tendency to form a stable structure by reducing the total interaction energy and enhancing system lamellar ordering. This work not only demonstrates the great potential of ultra-micro liquid crystals in for commercial applications in cosmetics but also offers a deeper understanding of the intrinsic properties and growth mechanisms of ultra-micro liquid crystals at the microscopic level.

Tuning Molten-Salt-Mediated Calcination in Promoting Single-Crystal Synthesis of Ni-Rich LiNixMnyCozO2 Cathode Materials

High Ni-content LiNixMnyCozO2 (NMC) cathodes (with x ≥ 0.8, x + y + z = 1) have gained attention recently for their high energy density in electric vehicle (EV) Li-ion batteries. However, Ni-rich cathodes pose challenges in capacity retention due to inherent structural and surface redox instabilities. One promising strategy is to make the Ni-rich NMC material in the form of single-crystal micron-sized particles, as they resist intergranular and surface degradation during cycling. Among various methods to synthesize single-crystal NMC (SC-NMC) particles, molten-salt-assisted calcination offers distinct processing advantages but at present, is not yet optimized or mechanistically clarified to yield the desired control over crystal growth and morphology. In this project, molten-salt-mediated transformation of Ni0.85Mn0.05Co0.15(OH)2 precursor (P-NMC) particles to LiNi0.85Mn0.05Co0.15O2 particles is investigated in terms of the crystal growth mechanism and its electrochemical response. Unlike previous studies that involved large volumes of molten salt, using a smaller volume of molten KCl is found to result in larger primary particles with improved cycling performance achieved via partial reactive dissolution and heterogeneous nucleation growth, suggesting that the ratio of molten salt volume to NMC mass is an important parameter in the synthesis of single-crystal Ni-rich NMC materials.

Core mechanism for the stability preparation of lithium slag-based SOD zeolite: Evolution of trans-crystallization nucleation/growth kinetics of crystals

SOD nano-zeolite has been widely applied in the separation of small gas molecules since these advantages comprise a high-density framework and favorable acid/alkali resistance. Moreover, the bottleneck for the lithium sector can be ameliorated by industrializing the manufacture of SOD zeolite (SLS) from the hazardous waste lithium slag (LS). However, the stability in industrial production is restricted owing to the ambiguous nature of the lattice nucleation/transformation mechanism. Herein, it was discovered that the highest relative crystallinity (98.8 %) of SLS with a layered spherical structure could be achieved under the crystallization condition of heating at 95 °C for 8 h. The nucleation and growth mechanisms of SLS crystals demonstrated a three-dimensional crystal growth pattern characterized by sporadic and transient nucleation, which is essentially consistent with that of crystallization kinetics. Specifically, the activation energies of the induction, transformation and crystallization phases were 41.33, 27.99 and 46.99 kJ·mol−1, respectively, implying that the directional induction of the transition phase is crucial for obtaining SLS with high crystallinity. Two nucleation processes can also be observed in the transformation stage, involving homogeneous nucleation and polymorphic transformation. Our study explored the crystallization and assembly mechanism of SLS crystals, providing a well-defined concept for the regulation of stability preparation.

Low-temperature flux synthesis of potassium hexatitanate whiskers: Growth mechanism and applications in high-temperature infrared thermal insulation

Potassium hexatitanate whiskers (PHWs, K2Ti6O13) are a promising functional material with high thermal insulation capacity. In this study, PHWs were successfully synthesized using the flux method at temperatures ranging from 725 °C to 1100 °C. The crystal growth mechanism of PHWs in the KCl flux follows a series–parallel pattern. The synthesized PHWs have a near-infrared reflectivity (NIR) exceeding 95%, and the cause of high reflectivity was theoretically analyzed based on the Kubelka–Munk equation. The high temperature stability of near-infrared reflectivity and the thermal stability of the PHWs were further assessed using TG-DSC, XRD, SEM, and UV–VIS-NIR analysis. It was found that PHWs prepared at 800 °C begin to decompose into TiO2 at approximately 1375 °C. Nevertheless, the near-infrared reflectivity remains stable even after heat treatment. Additionally, PHWs were prepared as a composite thermal insulating coating, showing thermal conductivity between 0.177 and 0.569 W/(m K) across the temperature range of 200 °C to 900 °C. The temperature difference between the hot and cold surfaces of the composite coating was significantly greater compared to the control groups at various temperatures, with a p-value of less than 0.01 in the paired t-test. This result demonstrates the great application potential of PHWs as a high-temperature near-infrared thermal insulation material.

Spiral-Concave Prussian Blue Crystals with Rich Steps: Growth Mechanism and Coordination Regulation.

Investigating the formation and transformation mechanisms of spiral-concave crystals holds significant potential for advancing innovative material design and comprehension. We examined the kinetics-controlled nucleation and growth mechanisms of Prussian Blue crystals with spiral concave structures, and constructed a detailed crystal growth phase diagram. The spiral-concave hexacyanoferrate (SC-HCF) crystals, characterized by high-density surface steps and a low stress-strain architecture, exhibit enhanced activity due to their facile interaction with reactants. Notably, the coordination environment of SC-HCF can be precisely modulated by the introduction of diverse metals. Utilizing X-ray absorption fine structure spectroscopy and in situ ultraviolet-visible spectroscopy, we elucidated the formation mechanism of SC-HCF to Co-HCF facilitated by oriented adsorption-ion exchange (OA-IE) process. Both experimental data, and density functional theory confirm that Co-HCF possesses an optimized energy band structure, capable of adjusting the local electronic environment and enhancing the performance of the oxygen evolution reaction. This work not only elucidates the formation mechanism and coordination regulation for rich steps HCF, but also offers a novel perspective for constructing nanocrystals with intricate spiral-concave structures.

Spiral‐Concave Prussian Blue Crystals with Rich Steps: Growth Mechanism and Coordination Regulation

AbstractInvestigating the formation and transformation mechanisms of spiral‐concave crystals holds significant potential for advancing innovative material design and comprehension. We examined the kinetics‐controlled nucleation and growth mechanisms of Prussian Blue crystals with spiral concave structures, and constructed a detailed crystal growth phase diagram. The spiral‐concave hexacyanoferrate (SC‐HCF) crystals, characterized by high‐density surface steps and a low stress‐strain architecture, exhibit enhanced activity due to their facile interaction with reactants. Notably, the coordination environment of SC‐HCF can be precisely modulated by the introduction of diverse metals. Utilizing X‐ray absorption fine structure spectroscopy and in situ ultraviolet‐visible spectroscopy, we elucidated the formation mechanism of SC‐HCF to Co‐HCF facilitated by oriented adsorption‐ion exchange (OA‐IE) process. Both experimental data, and density functional theory confirm that Co‐HCF possesses an optimized energy band structure, capable of adjusting the local electronic environment and enhancing the performance of the oxygen evolution reaction. This work not only elucidates the formation mechanism and coordination regulation for rich steps HCF, but also offers a novel perspective for constructing nanocrystals with intricate spiral‐concave structures.

Exploring the mechanisms of benzanilide crystal growth and morphology: Crystal surface structure, solvent diffusion and solvent-interface interactions

Flaky crystals are fragile, rendering them unsuitable for various applications including use, processing, storage and transportation. This work investigates the growth and morphology regulation mechanisms of flaky crystals using benzanilide as a model material. Initially, block-like crystals are prepared by solvent screening and cooling crystallization with its morphology greatly improved. Subsequently, growth kinetics of (111), (1–10) and (020) faces are established with crystal growth experiments. The crystal growth of (001) face is also determined to follow a two-dimensional nucleation model with the microscopic surface analysis using atomic force microscopy. The changes of the surface integration resistance and the growth step height are regarded as kinetic mechanisms of the growth behavior and crystal morphology modulation by solvent and supersaturation. Finally, the molecular mechanism of the modulation of the solvent in crystal morphology is revealed base on crystal surface structure analysis and molecular dynamics simulations. The weak solvent-interface polar interactions facilitate the incorporation of benzanilide molecules into the weak polarity (001) face, leading to the surface roughening and increased crystal thickness when employing strongly polar solvents such as acetonitrile. Unlike the former, the relatively weak hydrogen bonding interactions between solvents and strong polarity (020) face, and the higher diffusion ability of molecules promote the rapid growth and disappearance of (020) face in ethanol and acetonitrile with strong hydrogen bond formation ability. This study can contribute to a deeper understanding of the solvent effect on crystal morphology and provide guidance for optimizing crystallization conditions to obtain shape-tailored crystal products.

Effect of Mn2+ concentration on the growth of δ-MnO2 crystals under acidic conditions

δ-MnO2 is an important component of environmental minerals and is among the strongest sorbents and oxidants. The crystalline morphology of δ-MnO2 is one of the key factors affecting its reactivity. In this work, δ-MnO2 was initially synthesized and placed in an acidic environment to react with Mn2+ and undergo a crystalline transformation. During the transformation of crystalline δ-MnO2, kinetic sampling was conducted, followed by analyses of the structures and morphologies of the samples. The results showed that at pH 2.5 and 4, δ-MnO2 nanoflakes spontaneously self-assembled into nanoribbons via edge-to-edge assembly in the initial stage. Subsequently, these nanoribbons attached to each other to form primary nanorods through a face-to-face assembly along the c-axis. These primary nanorods then assembled along the (001) planes and lateral surfaces, achieving further growth and thickening. Since a lower pH is more favorable for the formation of vacancies in δ-MnO2, δ-MnO2 can rapidly adsorb Mn2+ directly onto the vacancies to form tunnel walls. At the same time, the rapid formation of the tunnel walls leads to a quick establishment of hydrogen bonding between adjacent nanoribbons, enabling the assembly of these nanoribbons into primary nanorods. Therefore, in a solution with the same concentration of Mn2+, the structure transformation and morphology evolution of δ-MnO2 to α-MnO2 occur faster at pH 2.5 than at pH 4. These findings provide insights into the mechanism for crystal growth from layer-based to tunnel-based nanorods and methods for efficient and controlled syntheses of nanomaterials.