Search

Journal of magnesium and alloys 10(11), 3281-3287 (2022). doi:10.1016/j.jma.2021.08.008, Published by Elsevier, Amsterdam [u.a.]

The main condition for elimination of growth striations is the formation of standing waves in the melt for damping of convection. The formation of standing waves between the crucible bottom and the solid-liquid interface suppresses convection in the melt and eliminates growth striations in single crystals. Growth striations in InSb and GaAs single crystals were eliminated after the ultrasound was switched on at frequencies of 0.65 MHz and 0.15 MHz in their melts with the Rayleigh numbers 0.18×105 and 0.2×105, respectively. The ultrasound intensity was determined from a model experiment with similar conditions to crystal growth using a light cut method. The model experiments demonstrated formation of standing waves above the waveguide with a piezo transducer after switching on the ultrasound that attended appearance of a dome on a liquid surface. The dome dimensions on the liquid surface were used for calculation of the ultrasound intensity. The calculated ultrasound intensity was 0.85 Wcm-2. It was found that the growth striations disappeared a certain time after switching the ultrasound on, which can be explained by the formation time of standing waves and properties of the melt. The time intervals between switching the ultrasound on and the elimination of striations in grown InSb and GaAs single crystals were measured using the experimental images with the striation elimination, and were 10 s and 22 s, respectively. The controlled formation of ultrasonic standing waves in the melt in crystal growth eliminates growth striations, and this technique can be used for the industrial application.

Background: Chlorzoxazone (CHZ) is a water-insoluble drug having bioavailability problems. The absorption rate of such drugs can be improved by reducing their particle size. In this work, the crystal growth kinetics of CHZ–ethanol for different degrees of supersaturation (SS) has been studied. Method: The equilibrium solubility data of CHZ in ethanol is determined by the shake-flask method within the 283.15–313.15 K temperature range. The mole fraction solubility of CHZ is calculated and correlated with the modified Apelblat equation, λh equation, van’t Hoff equation, Wilson, and non-random two liquid (NRTL) equation. Batch crystallization experiments are performed on three different degrees of SS-1.16, 1.18, and 1.20 at 293.15 K as a function of time. Results: The maximum root mean square difference (RMSD) and relative average deviation (RAD) values of 169.24 x10-6 and 0.699 x10-2, respectively, are observed in the NRTL equation model. The dissolution properties such as standard enthalpy, standard entropy, and Gibbs free energy are predicted using van’t Hoff equation. Using a simple integral technique, the average crystal growth rate constant KG is calculated as 1.58 (μm/min) (mg/ml)-1 and the order n=1 for CHZ–ethanol at 293.15 K. Conclusion: The obtained result concludes that the crystals growth size is found to be varied at different SS ratio in batch crystallization. The particle size control in batch crystallization can be achieved by optimizing the operating conditions to get the desired size crystals.

Crystallization often proceeds in media with rich chemical compositions. In pursuit of insight into how foreign compounds interact with the structures and dynamics that comprise crystal growth, we ...

In the last decade, organic-inorganic perovskite solar cells (PSCs) have had tremendous success, raising their power conversion efficiency from 3.8% in 2009(T, A, K, & Y, 2009) to >25.6% (Li et al., 2021). Perovskite material is newly emergent, third-generation solar cells, it generally refers to any composite that has structure like that of calcium titanium oxide (CaTiO2). It has a general formula ABX­3, where A refers to an organic compound, B is an inorganic and X represents the halides. In this research, a Hybrid-Formamidinium Bismuth Bromide Perovskite solar cell (FABi2Br9) was synthesized via a novel crystal growth process and subjected to characterization for determining its optoelectronic properties for solar cells application. The x-ray diffraction (XDR) results revealed the crystal hexagonal structure of FABi2Br9, the crystal sizes were obtained and it gives an excellent size (74nm) for light absorption material. The bandgap was determined using ultraviolet-visible spectroscopy (U.V vis) which was found to be 1.80eV which is within the required range for an absorbing layer in a solar cell architecture. Nuclear magnetic resonance (NMR) and was used to identify the organic content purity of the composite. In conclusion, FABi2Br9 was found to be pure with excellent optoelectronics properties that can readily be used as an absorbent layer in perovskite solar cells architecture

Ti-bearing blast furnace slag is an important reproducible Ti resource. The effective recovery of the Ti component from this slag can not only alleviate the resultant environmental problems but also overcome the shortage of Ti resources. In this study, the mineral and element of Ti-bearing blast furnace slag were analyzed and adjusted according to the gravity center rule of CaO–SiO2–TiO2 ternary phase diagram. The Ti component in the Ti-bearing blast furnace slag was enriched into the perovskite phase by preoxidation treatment and high-temperature selective enrichment & precipitation. The results indicate that, the preoxidized slag was obtained with adding 2.54% of CaO to the original slag at 1025 °C for 30 min. Subsequently, the preoxidized slag with 1.0% of Fe2O3 was melted at 1470 °C for 40 min, and the temperature was thereupon reduced to 1320 °C at 0.5 °C/min and kept constant for 90 min. The modified slag exhibited obvious enrichment and precipitation of perovskite, which had a crystal size of 63.17 μm and a crystallization volume of 30.62%. The perovskite phase was observed to exhibit mainly an orderly cross-shaped, granular, and beaded arrangement. During the selective enrichment and precipitation process, the fine-grain perovskite crystals fused together, and the concentrations of Ca2+ and TiO 3 2 − surrounding the perovskite crystals decreased, which restricted the crystal growth and led to necking. Changes in the surface tension caused the melting point to drop, thereby facilitating remelting and resulting in narrower necking.

An active pharmaceutical ingredient is currently produced in a traditional batch antisolvent crystallization process. Although well-established, this process lacks flexibility to control the crystal size distribution (CSD). Therefore, a new process was developed to enable the control of the CSD according to different specifications. This new process was implemented in continuous in a planar oscillatory flow crystallizer (planar-OFC). In this work, the main goal was to enable the production of small crystals to meet very specific formulation requirements and, simultaneously, promote the aggregation of these small particles to optimize the filtration operation. First, the operating conditions were optimized for continuous operation. Then, the planar-OFC was divided into two spatially independent sections, the nucleation zone (where nucleation is dominant) and the crystal growth zone (where crystal growth is dominant), so as to control the CSD as a function of the residence time in each zone. In particular, the formation of aggregates could be promoted by increasing the residence time in the nucleation zone. Ultimately, the planar-OFC was able to produce smaller particles with significantly narrower CSDs than the traditional batch process. This is particularly important when small particle sizes are required, thus reducing manufacturing time and operating costs.

In this work, three Nitrogen-functionalized graphene (NGs): amino-graphene (G-NH2), graphene-ethanolamine (G-EA), and graphene ethylenediamine (G-EDA) have been synthesized and tested as hole transport layers (HTL) for perovskite solar cells (PSCs) applications. Among the evaluated graphene-based derivatives, the PSCs fabricated with graphene-ethylenediamine (G-EDA) showed best power conversion efficiency of 12.9%. The enhanced PCE of G-EDA based PSCs as compared to other NGs are attributed to the uniform coverage, faster hole transportation, and a template for larger perovskite crystal growth. Moreover, the PCE of the PSCs fabricated with G-EA and G-EDA based HTLs remain stable even after 200 h of light-soaking.

This paper is devoted to the mathematical modeling of a combined effect of directional and bulk crystallization in a phase transition layer with allowance for nucleation and evolution of newly born particles. We consider two models with and without fluctuations in crystal growth velocities, which are analytically solved using the saddle-point technique. The particle-size distribution function, solid-phase fraction in a supercooled two-phase layer, its thickness and permeability, solidification velocity, and desupercooling kinetics are defined. This solution enables us to characterize the mushy layer composition. We show that the region adjacent to the liquid phase is almost free of crystals and has a constant temperature gradient. Crystals undergo intense growth leading to fast mushy layer desupercooling in the middle of a two-phase region. The mushy region adjacent to the solid material is filled with the growing solid-phase structures and is almost desupercooled. © 2021 The Authors. Mathematical Methods in the Applied Sciences published by John Wiley & Sons, Ltd. Russian Science Foundation, RSF: 21-79-10012 The authors gratefully acknowledge financial support from the Russian Science Foundation (project no. 21-79-10012). Open Access funding enabled and organized by Projekt DEAL.

Crystallization of lysozyme is investigated upon rapid cooling to 4°C of undersaturated solutions equilibrated at temperatures in the range 30°C–44°C, and for incubation times varying from 12 to 36...

Surface-enhanced Raman scattering (SERS) provides a novel method for low concentration molecular detection. The performances were highly dependent on the sizes, geometries and distributions of metal nanostructures. Here, highly sensitive SERS fiber probe based on silver nanocubes (Ag NCs) was fabricated, by assembled nanostructures on planar and tapered fiber tips. Ag NCs were synthesized by polyol method, and controlled by reductant content, reaction temperatures and crystal growth durations. Tapered fibers with different cone angles were prepared by chemical etching. The electromagnetic distribution simulation indicated that nanocubes had stronger electric field between two cubes and vertex corners than nanosphere, under 532 nm laser excitation. The intensity could reach 53.52 V/m, for cubes with 70 nm edge length. The SERS performance of probes was characterized using crystal violet analyte. The detectable lowest concentration could reach 10–9 and 10–10 M for planar and tapered fiber probes, respectively. The corresponding enhancement factor could be 9.02 × 107 and 6.22 × 108. The relationship between SERS peak intensities and analyte concentrations showed well linear, which indicated both fiber probes could be applied for both qualitative and quantitative analysis. Furthermore, optimal cone angle of tapered fiber SERS probe was 8.3°. The tapered fiber SERS probes have highly sensitive activity and great potential in substance detection.

A Yb3+:KBaY(MoO4)3 (Yb3+:KBYM) crystal with dimensions of 51 mm × 27 mm × 10 mm was successfully grown by the TSSG method. The characteristics of the crystal structure and probability of good optical properties were analyzed. The absorption and emission spectra of Yb3+:KBYM crystal exhibit broadened bands, with the maximum absorption cross-sections of 1.17 × 10-20, 1.44 ×10-20 and 1.37 × 10−20 cm2 at 976 nm for X-, Y- and Z-polarizations, respectively. The corresponding absorption FWHMs are as wide as 77, 46 and 55 nm. The well-known re-absorption effect of Yb3+ in the crystal is discussed. Two methods, the Fuchtbauer-Ladenburg method (FL) and reciprocity method (RM) were adopted to compute the emission cross-sections and results show a certain discrepancy but the errors are allowable. The laser potentiality of the Yb3+:KBYM crystal was also evaluated by calculations of minimum inversion fraction β min , saturation pump intensity I sat , the minimum pump intensity I min and gain cross-sections spectra. Laser experiment was carried out and Watt-level continuous wave laser has been realized. Results indicate that the Yb3+:KBYM crystal with a disordered structure may be a potential laser media that can be used to generate tunable and ultrashort pulse laser emissions with high quality beam.

A novel type of liquid gating technology has been developed to prepare a polyethylene oxide (PEO) single-crystal film, and the crystal growth was observed via atomic force microscopy. The self-seeding method has been widely used in the preparation of polymer single crystals, but the mechanism through which single polymer crystals are formed via the combination of liquid gating technology and the self-seeding method remains unclear. To elucidate the mechanism of this process, a series of experiments were conducted in which a dilute polymer solution was sprayed onto a mica substrate to form a single-crystal film through liquid gating technology to study the effect of the crystallization time on the morphology of a thiol PEO (mPEO-SH) crystal. Based on this research, it was found that liquid gating helps to prevent twinning during crystal growth. The combination of liquid gating and self-seeding technology thus provides a new strategy for polymer single-crystal growth.

We demonstrate the solvent-free amorphous-to-cocrystalline transformations of nanoscale molecular films. Exposing amorphous films to vapors of a haloarene results in the formation of a cocrystalline coating. This transformation proceeds by gradual strengthening of halogen-bonding interactions as a result of the crystallization process. The gas-solid diffusion mechanism involves formation of an amorphous metastable phase prior to crystallization of the films. In situ optical microscopy shows mass transport during this process, which is confirmed by cross-section analysis of the final structures using focused ion beam milling combined with scanning electron microscopy. Nanomechanical measurements show that the rigidity of the amorphous films influences the crystallization process. This surface transformation results in molecular arrangements that are not readily obtained through other means. Cocrystals grown in solution crystallize in a monoclinic centrosymmetric space group, whereas the on-surface halogen-bonded assembly crystallizes into a noncentrosymmetric material with a bulk second-order nonlinear optical response.

Unformatted post-print version of the accepted article Polylactide is one of the most versatile biopolymers, but its slow crystallization limits its temperature usage range. Hence finding ways to enhance it is crucial to widen its applications. Linear and cyclic poly (L-lactide) (l-PLLA and c-PLLA) of similarly low molecular weights (MW) were synthesized by ring-opening polymerization of L-lactide, and ring-expansion methodology, respectively. Two types of blends were prepared by solution mixing: (a) l-PLLA/c-PLLA, at extreme compositions (rich in linear or in cyclic chains), and (b) blends of each of these low MW materials with a commercial high MW linear PLA. The crystallization of the different blends was evaluated by polarized light optical microscopy and differential scanning calorimetry. It was found, for the first time, that in the l-PLLA rich blends, small amounts of c-PLLA (i.e., 5 and 10 wt%) increase the nucleation density, nucleation rate (1/τ0), spherulitic growth rate (G), and overall crystallization rate (1/τ50%), when compared to neat l-PLLA, due to a synergistic effect (i.e., nucleation plus plasticization). In contrast, the opposite effect was found in the c-PLLA rich blends. The addition of small amounts of l-PLLA to a matrix of c-PLLA chains causes a decrease in the nucleation density, 1/τ0, G, and 1/τ50% values, due to threading effects between cyclic and linear chains. Small amounts of l-PLLA and c-PLLA enhance the crystallization ability of a commercial high MW linear PLA without affecting its melting temperature. The l-PLLA only acts as a plasticizer for the PLA matrix, whereas c-PLLA has a synergistic effect in accelerating the crystallization of PLA that goes beyond simple plasticization. The addition of small amounts of c-PLLA affects not only PLA crystal growth but also its nucleation due to the unique cyclic chains topology. We would like to acknowledge the financial support from the BIODEST project; this project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 778092. This work has also received funding from the Basque Government through grant IT1309-19. R.A.P.-C is supported by PIFI of the Chinese Academy of Science for international postdoctoral researchers (2019PE0004), the China Postdoctoral Science Foundation (2020M670462), and National Natural Science Foundation of China (NSFC) (52050410327) under the program Research Fund for International Young Scientists. O.C. is Senior Research Associate for the F.R.S.-FNRS of Belgium.

The microstructural development during crystallization firing of a commercially-available dental-grade nanostructured lithia-zirconia glass-ceramic (Vita Suprinity® PC) was unraveled using a wide battery of ex-situ and in-situ characterization techniques. It was found that the milling blocks are slightly crystallized glass-ceramics, with a complex chemical composition and consisting of partially de-polymerized glass plus lithium silicate (Li2SiO3) nanocrystals. It was also found that during crystallization firing the glassy matrix first reacts with part of the Li2SiO3 to form lithium disilicate (Li2Si2O5) at ∼810−820 °C, and then lithium orthophosphate (Li3PO4) precipitates from the glass. This results in glass-ceramics with abundant nanocrystals embedded in a sparse zirconosilicate glass matrix (containing many other cations subsumed) that, due to its high viscosity, inhibited crystal growth. Therefore, these dental glass-ceramics are not reinforced with zirconia (ZrO2) crystals unless over-fired above ∼890 °C and at the expense of its singular nanostructure. Finally, this study opens doors for optimizing the clinical performance of these dental glass-ceramics via microstructural tailoring.

Abstract The influence of the precipitant type (LiCl, NaCl, KCl, NiCl2, and CuCl2) on the formation of oligomers (dimers and octamers) in lysozyme crystallization solutions at two protein concentrations has been investigated by small-angle X-ray scattering (SAXS). The same solutions have been used to grow crystals in order to reveal the influence of the oligomeric composition on the crystal growth. The data obtained in this and previous studies on the influence of precipitant concentration yield an inversely proportional dependence of the total content of octamers and dimers on the cation atomic number, which is in agreement with the increase in the ion activity in the lyotropic series for Li+, Na+, and K+ and the increase in the ionic radius for Li+, Na+, K+, Ni2+, and Cu2+. It is shown that a decrease in the protein concentration in a crystallization solution leads to a decrease in octamer volume fraction at an invariable volume fraction of dimers and reduces the probability of crystal formation.

The effect of crystallization of y-Y2Si2O7 (Y-c and Y2S-c2)/Y4.67(SiO4)3O (Y2S-c1) single crystal or simultaneously y-Y2Si2O7, Al6Si2O13 and SiO2 crystals (YMS-c) on the hardness and thermal expansion coefficient (TEC) of Y2O3–Al2O3–SiO2 (YAS) glass is studied. Crystallization activation energy is 591, 650 and 282 kJ/mol for Y, Y2S and YMS glasses, crystallization mechanisms of glasses Y and Y2S (Tc1) are surface crystallization and one-dimensional crystal growth, while YMS glass is two- and one-dimensional growth of crystals. The volume fraction of crystalline phases in Y-c (91.45%), Y2S-c1 (83.00%) and -c2 (92.55%) glass ceramics are larger than that of YMS-c (71.11%), precipitated y-Y2Si2O7 single crystal decrease the TEC ( × 10−6 °C−1/30–1000 °C) of Y and Y2S parent glasses to 3.95 (Y-c) and 5.09 (Y2S-c2) while Y4.67(SiO4)3O single crystal increase the TEC of Y2S-c1 to 7.15, YMS-c has the smallest TEC (3.34) among studied glass ceramics, the enhancing effect of Y4.67(SiO4)3O on the hardness of Y2S glass is more than that of y-Y2Si2O7. Y and YMS glasses could be used as coating, sealing and jointing materials for SiC ceramics used in the high temperature fields.

Experimental results on the growth of cubic diamond on lonsdaleite-bearing diamonds from the Popigai astrobleme at 5.5 GPa and 1450°C in the Fe–Ni–C system are presented. Due to the simultaneous appearance of several crystallization centers, the cubic diamond phase occurred in the form of an aggregate. This is probably due to the specific structure of the paracrystals of impact diamonds from nanosized crystallites (10–100 nm) or polysynthetic twinning inherited from graphite crystals under ultrahigh pressure. The color of the diamond crystals is yellow and is typical of diamonds grown in the Fe–Ni–C system. The predominant morphological shape of diamond crystals is octahedra with additional cubic, rhombic dodecahedron, and tetragonal-trioctahedra faces.

Morphology transformation and crystal growth strategies of metal oxide semiconductors are extensive studied in material science recently, because the morphology and crystallinity of the nanomaterial have significant effect on the physicochemical characteristics. However, understanding the morphology changes of α-MoO3 induced by annealing temperature is still a challenge. Herein, the nanostructure transition of MoO3 induced by calcined temperature has been investigated through XRD and SEM method. It can be found that crystallization is highly dependent on the annealing temperature. In addition, the MoO3 nanoflowers can change into nanosheets at 500 ºC. Afterwards, the nanosheets turn into microrods, especially at 900 ºC due to the growth of MoO3 crystal. On the other hand, MoO3 is a traditional sensing material, which is sensitive to many volatile organic compounds. Thus, the sensing performances of various MoO3 nanostructures were measured. Compared with MoO3 nanoflowers and microrods. The MoO3 nanosheets based sensor has excellent sensing performance towards ethanol, and the maximum gas response value is 8.06.

The development of new infrared (IR) nonlinear optical (NLO) materials with strong second-harmonic generation (SHG) responses and high laser-induced damage thresholds (LIDTs) is urgent but challenging. Herein, the defective diamond-like chalcogenide Hg3P2S8 (HPS) was rationally designed and fabricated by a flexible and rigid tetrahedral motif combined strategy. HPS exhibits a phase-matching SHG response of similar to 3.6 x AGS (the largest one in the reported ternary sulfides), high LIDT (similar to 3 x AGS), wide IR transparent region (0.43-16.3 mu m), moderate birefringence (0.043 at 1064 nm), and good physicochemical stability and crystal growth habits. Theoretical analyses confirm that the large SHG effect originates from the synergistic effects between distorted HgS4, PS4, and vacancy-induced nonbonding electrons. The results indicate that HPS is a promising NLO candidate for high-power, high-efficiency laser output in the mid-IR region, which provides an insight into the exploration of new IR NLO materials.

Kesterite based on Cu2ZnSnS4 composition is considered as a promising absorber material for the next generation of photovoltaics due to raw materials abundance and low toxicity. Developing a superstrate architecture using kesterite as an absorber could be the key to a better performance, which allows new ways of engineering the formation of a kesterite thin film. In this work, we study the effects of the sulfurization temperature on the crystallization of kesterite film when is fabricated in a superstrate architecture, and how this affects the performance of a solar cell. We noted that the temperature affects the final composition of the absorber due to cadmium diffusion at 500 °C from the CdS layer, while the temperature above 530 °C is essential for a complete Zn incorporation into the crystal structure. The crystallinity is highly affected, and a temperature of 550 °C is found to be favorable for the crystal growth, and the fabricated device gave improved performance. Impedance spectroscopy measurements suggest the performance enhancement is due to the reduction of defects and an increase of the depletion width in the p-n junction.

Solvent engineering and antisolvent methods have been used extensively to achieve high-quality, homogeneous, and crystalline perovskite thin films. Usually, highly concentrated (>1.1 M) precursor solutions are used to achieve the maximum power conversion efficiency (PCE), and most fabrication studies focus on iodide-based metal halide perovskites (MHPs). However, high concentrations of precursors are not suitable for semitransparent (ST) MHP solar cells (STPSCs), which require thinner films to achieve a high average visible transmittance (AVT). The deposition of high-quality perovskites with variable concentrations in a one-step method is challenging due to the complexity of the antisolvent crystallization process. Here, we have developed an in situ technique based on photoluminescence (PL) measurements to identify the optimum delay time for antisolvent crystallization in formamidinium lead bromide (FAPbBr3). By monitoring the in situ PL, the nucleation, crystal growth, and early perovskite formation phases are easily identified for a range of concentrations. Subsequently, we fabricated opaque and ST solar cells with optically clear, ST perovskite films formed from precursors with varying concentrations. These all-solution-processed STPSCs achieved AVTs of up to 35.6, 42.5, and 49.2%, with the corresponding PCEs of 5.71, 3.25, and 1.86% in p-i-n type, FAPbBr3 perovskite solar cells with transparent Ag nanowire electrodes. These devices show good stability over several weeks and an impressive Voc as high as 1.24 V for STPSCs and 1.38 V for opaque cells produced with a thick Ag electrode. This work demonstrates the potential use of in situ spectroscopy to tailor the film growth of halide perovskites with varying concentrations and the feasibility of using wide-band-gap perovskites for ST solar cells with exceptional clarity and higher Voc.

Crystallization is an experimental phenomenon that does not always depend on predicted data for efficient processing. It, therefore, becomes important to conduct experiments in the seeded or unseeded crystallization process to gain insight into the growth kinetic parameters. The knowledge of the process and kinetic parameters is proved useful in developing strategies for the optimal design of crystallizers and in control of crystal size distribution. A differential scanning calorimeter (DSC) was used to perform isothermal growth experiments for seeded crystallization, and the kinetics was evaluated using a de-supersaturation curve. In order to get the de-supersaturation curve, the DSC heat flow signal was used to measure and quantify the mass change of seeds during the crystal growth process as a function of time at a particular temperature. Experiments were performed at temperatures ranging from 10 to 40 °C in sealed DSC pans. The growth order g was calculated from the isothermal experiments at varying temperatures, and the mass growth rate coefficient Kg, linear growth rate coefficient kg, mass rate of crystal growth RG and activation energy Ea of benzoic acid in the ethanol–water binary solvent were estimated from growth order g. The kinetic parameters were compared with the data obtained using online measurement techniques and found to be in good agreement. The present work establishes the reliability of calorimetric transformation studies for estimating growth kinetics using a small amount of sample in a very short period, at higher temperatures and pressures.

In this paper, isothermal and non-isothermal crystallization behaviour of neat polypropylene (PP), blends of PP/maleic anhydride grafted polypropylene (PP-g-MA), and PP/PP-g-MA/polyethylenimine (PEI) has been studied by differential scanning calorimetry (DSC). DSC analysis confirmed that PEI promotes crystallization of PP for blends compatibilized with reactive co-agent PP-g-MA, that was confirmed by decreased crystallization time in compatibilized PP-PEI blends as compared to neat PP. The Avrami equation has been used to analyze isothermal crystallization kinetics for all the compositions. Determined Avrami exponent’s (n) values confirmed three-dimensional crystal growth in all the samples and PP sample with 1% PEI and 1% PP-g-MA (PP/1PP-g-MA/1PEI) was found to have the least crystallization half time (t1/2). In addition to this, activation energy (∆Ea) for PP/1PP-g-MA/1PEI blend decreased remarkably as compared to neat PP. The non-isothermal crystallization kinetics was studied by Jeziorny extended Avrami and Mo theories. Application of Jeziorny-Avrami equation showed larger value of log k’ in case of PP/1PP-g-MA/1PEI indicating enhanced rate of crystallization. Lower value of Mo’s parameter F(T) for PP/1PP-g-MA/1PEI than neat PP established higher crystallization rate for the compatibilized blend and hence supported the prior results.

Unformatted post-print version of the accepted article Crystallization of polymeric materials under nanoscopic confinement is highly relevant for nanotechnology applications. When a polymer is confined within rigid nanoporous anodic aluminum oxide (AAO) templates, the crystallization behavior experiences dramatic changes as the pore size is reduced, including nucleation mechanism, crystal orientation, crystallization kinetics, and polymorphic transition, etc. As an experimental prerequisite, exhaustive cleaning procedures after infiltrations of polymers in AAO pores must be performed to ensure producing an ensemble of isolated polymer-filled nanopores. Layers of residual polymers on the AAO surface percolate nanopores and lead to the so-called “fractionated crystallization”, i.e., multiple crystallization peaks during cooling. As the density of isolated nanopores in a typical AAO template exceeds the density of heterogeneities in bulk polymers, the majority of nanopores will be heterogeneity-free. This means that the nucleation will proceed by surface or homogeneous nucleation. As a consequence, a very large supercooling is necessary for crystallization, and its kinetics is reduced to a first-order process that is dominated by nucleation. Self-nucleation is a powerful method to exponentially increase nucleation density. However, when the diameter of the nanopores is lower than a critical value, confinement prevents the possibility to self-nucleate the material. Because of the anisotropic nature of AAO pores, polymer crystals inside AAO also exhibit anisotropy, which is determined by thermodynamic stability and kinetic selection rules. For low molecular weight poly(ethylene oxide) (PEO) with extended chain crystals, the orientation of polymer crystals changes from the “chain perpendicular to” to “chain parallel to” AAO pore axis, when the diameter of AAO decreases to the contour length of the PEO, indicating the effect of thermodynamic stability. When the thermodynamic requirement is satisfied, the orientation is determined by kinetics including crystal growth, nucleation and crystal growth rate. An orientation diagram has been established for PEO/AAO system, considering the cooling condition and pore size. The interfacial polymer layer has different physical properties as compared to the bulk. In poly(L-lactic acid), the relationship between the segmental mobility of the interfacial layer and crystallization rate is established. For the investigation of polymorphic transition of poly(butane-1), the results indicate that a 12 nm interfacial layer hinders the transition of Form II to Form I. Block and random copolymers have also been infiltrated into AAO nanopores, and their crystallization behavior is analogously affected as pore size is reduced. This work was supported by the National Key R&D Program of China (Grant No. 2017YFE0117800) and the National Natural Science Foundation of China (Grant Nos. 21873109, 51820105005, and 21922308). We also acknowledge the financial support from the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 778092. A.J.M. acknowledges funding from MINECO, Grant No. MAT2017-83014-C2-1-P, and from the Basque Government through Grant No. IT1309-19. G.L. is grateful to the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No. Y201908).

The crystal growth kinetics and morphology in germanium disulfide bulk glass and glass surface is described. The structural relaxation taking place below the glass transition is slow and the corresponding volumetric change is negligible. Therefore, it does not affect substantially the crystal growth process. The crystal growth rate of low temperature β-GeS2 and high temperature α-GeS2 polymorphs in the bulk glass is comparable, being slightly decoupled from the shear viscosity below the glass transition. The crystal growth rate of β-GeS2 in an amorphous thin film of the same composition is several orders of magnitude faster than that at the surface of bulk glass. This fast surface crystal growth is strongly decoupled from viscosity. Such behavior resembles the glass-to-crystal fast growth mode observed by several authors in some organic molecular glasses. Taking into account previously reported viscosity and heat capacity data, the crystal growth kinetics of both polymorphs can be quantitatively described by the 2D surface growth model for low and high supercooling. The nonisothermal differential scanning calorimetry experiments are analyzed, providing evidence of a complex nature of the overall crystallization process with apparent activation energy comparable to that obtained from isothermal microscopy measurement of crystal growth in the same temperature range.

The exploration of the synthesis methods of sp2 and sp3 carbon nanomaterials under ambient conditions is very meaningful towards their industrial applications. The existing bottom-up synthesis methods usually need high temperature or high pressure conditions. We report a facile and environmentally-friendly approach enabling the synthesis of almost all types of known carbon nanostructures at room temperature and under atmosphere pressure. They include both sp3-structured n-diamond (not cubic diamond) nanocrystals and sp2-structured graphene, defective multiwalled carbon nanotubes, defective carbon nano-onions as well as graphene polyhedra. The reaction of ethanol and potassium hydroxide at ambient conditions yields n-diamond nanocrystals. To synthesize the sp2 carbon nanomaterials, the assistance of the ultrasonic shock at the early stage of crystallization is necessary to ensure the formation of the carbon ring nucleation seeds. The synthetic yields of n-diamond nanocrystals, graphene polyhedra, defective carbon nano-onions, and graphene are estimated to be 0.37%, 0.30%, 0.04%, and 0.01% (carbon mass ratio), respectively, and all of them have good crystallinity. These results improve our understanding of the low-temperature crystal growth process of the carbon nanostructures.

We observed the growth of salt crystals in sulfate saline soil solution during evaporation at constant relative humidity and temperature and studied the formation mechanism of soil deformation induced by salt crystallization. The growth of salt crystals is recorded by images using a CCD camera under an optical microscope, and the solution supersaturation and crystallization pressure are calculated taking advantage of digital image processing. The growth of sodium sulfate multilayer crystals is observed conforming to the Kossel model. Moreover, it is estimated that the maximum growth rate in the longitudinal direction is almost ten times that in the lateral direction in large pore contribution to the nucleation barrier during crystal formation. The crystals act on the liquid film pushing away soil particles, achieving the "self-cleaning" effect finally. The liquid film shows elastic deformation property in a short time during crystal growth, demonstrating that crystallization pressure is exerted by the liquid film. During mirabilite crystal growth, the crystallization pressure values fluctuate within 0-12.57 MPa because the supersaturation of the film is consumed, destroying pores in sulfate saline soil and eventually expressed by salt expansion.

The present work evaluated for the first time the use of continuous slug flow crystallizer (CSFC) in bulk seeded protein crystallization, using lysozyme (LYZ) as the model protein. LYZ crystals pre-prepared in batch crystallizer were used as seeds. The crystallization was performed at supersaturation level below the metastable-zone-limit. The resultant crystal size distribution (CSD), CSD's reproducibility, LYZ's bioactivity, and crystallization efficiency as characterized by the space-time-yield (STY, mg/h·L) were determined. The results showed that the CSFC's performance was governed by the flowrate, where a trade-off existed between crystal quality and crystallization efficiency upon varying the flowrate. At low flowrates, which reduced the shear rate and prolonged the residence time, well-defined large tetragonal crystals were produced attributed to suppressed secondary nucleation and extended crystal growth, but low STY due to difficulty in transporting the seeds/products crystals. Higher flow rates led to higher STY, but increased production of small non-tetragonal crystals that formed agglomerates. Compared to batch crystallizer, the CSFC produced LYZ crystals of similar average size, morphology, and bioactivity, but with roughly 50% lower STY, as the batch's high-shear environment promoted secondary nucleation, hence higher crystallization rate. The CSD's width and reproducibility was nevertheless significantly improved in CSFC. Ministry of Education (MOE) The authors would like to acknowledge the funding from Ministry of Education Singapore under Academic Research Fund Tier 1RG82/20 (2021).

Two new quaternary sulfides K2TGe3S8(T = Co, Fe) have been synthesized by a high-temperature solid-state routine and flux growth method. The crystal growth process of K2TGe3S8(T = Co, Fe) was elucidated by in situ powder X-ray diffraction and DSC thermal analysis. The millimeter-sized crystals of K2TGe3S8(T = Co, Fe) were grown. K2CoGe3S8 crystallizes in a new structure type in centrosymmetric space group P1 (no. 2) with unit cell parameters of a = 7.016(1) A, b= 7.770(1) A, c = 14.342(1) A, α = 93.80(1)°, β = 92.65(1)°, γ = 114.04(1)°. K2FeGe3S8 crystallizes in the K2FeGe3Se8 structure type and the noncentrosymmetric space group P21 (no. 4) with unit cell parameters of a = 7.1089(5)A, b = 11.8823(8) A, c = 16.7588(11) A, β = 96.604(2)°. There is a high structural similarity between K2CoGe3S8 and K2FeGe3S8. The larger volume coupled with higher degrees of distortion of the [FeS4] tetrahedra compared to the [CoS4] tetrahedra accounts for the structure's shift from centrosymmetric to noncentrosymmetric. The theory simulation confirms that [TS4]T= Co or Fe tetrahedra play a crucial role in controlling the structure and properties of K2TGe3S8(T = Co, Fe). The measured optical bandgaps of K2CoGe3S8 and K2FeGe3S8 are 2.1(1) eV and 2.6(1) eV, respectively. K2FeGe3S8 shows antiferromagnetic ordering at 24 K while no magnetic ordering was detected in K2CoGe3S8. The magnetic measurements also demonstrate the divalent nature of transition metals in K2TGe3S8(T = Co, Fe).

Herein, isotactic polypropylene films with small β-nucleating agent content were fabricated via a melt-extrusion-stretched technology with intended “shear-free” in barrel and die. Compared with neat films, the tensile strength, elongation at break and strain energy density at break of iPP film with 0.05 wt% β-nucleating agent are significantly improved by 13.8%, 39.6% and 90.6%, respectively, indicating the simultaneously enhanced toughness and strength. Additionally, the β-crystal content gradually increases with increasing β-NA content, while the relative total daughter content of α- and β-crystal exhibits opposite tendency. Moreover, nucleation and crystal growth induced by various β-NA contents are different. This work proves an efficient strategy to enhance mechanical properties of isotactic polypropylene film via controlling elongation flow and addition of appropriate β-NA content.

Crystallization of active pharmaceutical ingredients (APIs) from the supercooled liquid state is an important issue in determining the stability of amorphous pharmaceutical dispersions. In the present study, the isothermal crystallization from the supercooled liquid state of the pharmaceutical compound nifedipine was investigated by both rheological and differential scanning calorimetry (DSC) measurements, and the crystallization kinetics was fitted to the Johnson-Mehl-Avrami (JMA) equation. Both the crystallization induction time and completion time from the two methods were used to construct the time-temperature-transformation (TTT) diagram for nifedipine. A model based on a modification of classical homogeneous nucleation and crystal growth theory was employed to fit the induction and completion time curves. Both DSC and rheological methods give similar results for the crystallization kinetics of the nifedipine. From the crystallization kinetics modeling, the solid-liquid interfacial surface tension σSL of nifedipine was estimated and the value was found to be consistent with prior results obtained from melting point depression measurements as a function of crystal size. Evidence is shown that for temperatures below 110 °C, at the early stage of nucleation, NIF first nucleates into the metastable β'-form and later converts into the stable α-form during the isothermal crystallization. We are also able to report the heat of fusion of the γ'-NIF based on the calorimetric experiments.

The strategy of Lewis base modification has been shown to be rather effective in fabricating high-quality perovskite crystals; however, the underlying mechanisms remain controversial owing to the lack of any systematic characterization of the crystallization process. Herein, we report a novel non-invasive optical technique, termed vertical reflection-type in situ, real-time absorption spectroscopy, to investigate the mechanisms of Lewis base-mediated optimization of perovskite crystallinity by visualizing the entire energetic landscape of crystal growth. We show that by virtue of the urea additive, a prototypical Lewis base, the growth kinetics is accelerated prominently by decreasing the activation energy from 73.7 to 41.7 kJ/mol. In addition, the self-passivation of structural disorder during thermal annealing is identified, which is shown to be further strengthened by urea modification toward a shallower distribution of trap states.

The understanding of crystal nucleation and growth has evolved over the past two decades from the conventional atom-by-atom model to a non-classical approach, involving particle aggregation and amorphous transformation pathways. Whereas aggregation of particles instead of individual atoms/ions/molecules has been recognized as a common crystallization pathway at the Earth’s surface conditions, few cases are known for high-temperature (e.g., melt) mineralization, which is of great importance for understanding geological processes.Here, we present texture data for natural (e.g., igneous and metamorphic biotite and muscovite) and synthetic (e.g., fluorophlogopite) phyllosilicates suggesting that a particle attachment formation should be considered, although other crystal growth models cannot be excluded. A nonclassical crystallization model is proposed for phyllosilicates forming at elevated temperatures in magmatic and metamorphic environments whereby oriented attachment of building blocks occurs along the (001) plane or the [001] direction, or both simultaneously. In this model, the crystallization of phyllosilicates occurs in steps, with multi-ion complexes forming nanoparticles, and nanoparticles coalescing (self-assembly) to form nano-flakes that become domains in larger crystallites by oriented attachment. Adjacent domains can share a common crystallographic orientation or may be rotated at various angles relative to each other. Nanoparticles may be associated with distorted bonds or may be space separated. Thus, the phyllosilicate grows into a mosaic crystal.Mosaic crystals can also form following classical crystallization models, but the process differs in that the mosaic character involves the intergrowths of nucleation sites (classical crystal-growth process) instead of the coalescence of nanoparticles building blocks (crystallization by particle attachment). These processes may be discerned by the textural differences that result. Oriented particle attachment of building blocks in phyllosilicates is recognized by a loss of closest packing by bond distortion or by space separation at domain boundaries. Crystallization by atom attachment occurs with closest packing within layers, and particles grow independently. The two processes may occur within a single environment and are not mutually exclusive. However, defects generated, for example, by chemical inhomogeneity, mechanical deformation, or sample preparation, cannot be completely excluded, although the use of synthetic, end-member material (e.g., fluorophlogopite) generated from a melt reduces these possibilities. Nonetheless, a particle attachment model is a viable alternative to classical crystal growth processes for high-temperature phyllosilicates with the presented supporting data, although still not yet proven.

Since crystallization is one of the leading separation, isolation, and purification methods, the present mechanistic work investigated its continuous approach, presenting the precipitation of the benzoic acid molecules in a plug flow crystallizer. In some crystallization experiments, seeding was used in an attempt to eliminate spontaneous nucleation phenomena to allow better control over crystal size distribution by promoting crystal growth. At the same measurement time, a systematic mathematical model, based on mass varying expressions, kinetics and particle balance equations, was applied to predict the properties of the product crystals. Benchmarking the results of validation experiment, the established physical representation sufficiently described operation, which is confirmed by comparing various experimentally and theoretically determined process and product characteristics. Since liquid static mixers were used, a nearly perfect defined regime formation was achieved, which could be demonstrated by comparing simulated, calculated and experimentally-determined differential functional size distribution; therefore, a developed general morphology independent modelling could be built to optimise unit satisfactorily. Although crystallization of benzoic acid was investigated, the methodology can be easily applied to crystallization of other active pharmaceutical ingredients. The utilization of process analytical technologies and simulations can aid optimisation, intensification and automation, which can improve the quality of formulations.

The manipulation of the dimensionality and nanostructures based on the precise control of the crystal growth kinetics boosts the flourishing development of perovskite optoelectronic materials and devices. Herein, a low-dimensional inorganic tin halide perovskite, CsSnBrI2-x (SCN)x , with a mixed 2D and 3D structure is fabricated. A kinetic study indicates that Sn(SCN)2 and phenylethylamine hydroiodate can form a 2D perovskite structure that acts as a template for the growth of the 3D perovskite CsSnBrI2-x (SCN)x . The film shows an out-of-plane orientation and a large grain size, giving rise to reduced defect density, superior thermostability, and oxidation resistance. A solar cell based on this low-dimensional film reaches a power conversion efficiency of 5.01 %, which is the highest value for CsSnBrx I3-x perovskite solar cells. Furthermore, the device shows enhanced stability in ambient air.

Directed electrochemical deposition (DECD) with scanning probes has recently emerged as a bottom-up fabrication alternative to control the 3D morphology at the individual nanostructure level. In order to fabricate functional nanostructures with desired electrical properties, reactivity or stability, it is of utmost importance to control crystal growth. Investigating crystal formation in DECD is not straightforward due to the low fabrication yield and the final structure tending to be an aggregation of multiple particles. Here, we provide a simple method to investigate the early stages of electrochemical growth with atomic force microscopy (AFM). Geometric analysis of AFM topography images provide a rapid and quantitative identification of faceting in nano-crystals, with statistical independence of grain size distribution. We compare the growth evolution in macroscopic electrochemical deposition of Cu on Au with that under directed growth conditions. We find that the directed deposition from micromolar electrolytes in this work is distinctly different than that of conventional copper deposition, but results in similarly shaped spheroidal nuclei as those obtained in macroscopic growth from highly dilute electrolytes. The method presented here opens many possibilities to study in situ electrochemical crystal growth or surface stability in operando under electrochemical conditions.

Design of industrial crystallization processes usually employs laboratory‐scale experimental data which must be correlated with the full‐scale process for effective technology transfer. In this context, the measured growth rates of single crystals of Ibuprofen in stagnant ethanolic solutions are compared with data recorded for a population of crystals crystallized in an agitated 7ml reactor. The single crystal growth rates are found to be rather close to those determined in the agitated reactor, with both being also in good agreement with previously published data at the 750ml scale, suggesting that studies on single crystals can have utility for the purpose of crystallization process design and optimization.

Most studies related to the synthesis of TiO2–SiO2 composites for photocatalytic applications did not systematically evaluate the textural and photocatalytic properties obtained from different integration levels between these two phases. Thus, this work investigates the influence of the heat treatment step on the structural properties and photodegradation activity of TiO2–SiO2 composites synthesized by different sol–gel and hydrothermal routes. The as-prepared samples showed significant textural and photocatalytic differences, whereas the heat-treated samples showed similar structures and properties. However, some critical differences could be observed, such as different resistances to crystal growth due to the distinct location of the silica phase. Moreover, it was possible to identify a great photocatalytic enhancement by comparing the heat-treated and as-synthesized samples, which was mainly attributed to the segregation of SiO2 toward surface sites. Here, it was observed that the crystallization of titania after the heat-treatment step had a minor effect on the composites photoactivity since even the as-prepared samples were crystalline. The heat treatment was shown to be fundamental for a controlled segregation of the two phases, promoting a synchronous effect between the adsorption of MB molecules on the silica-rich portion and photocatalysis in the vicinity of such sites, where the titania phase is present. Such behavior was more pronounced in samples prepared with an early addition of TEOS during the synthesis.

We report the study of supramolecular assembling from both experimental and theoretical points of view. A scanning tunneling microscope (STM) and the Johnson–Mehl–Avrami (JMA) equation were, respec...

Multiple and complex crystallization process of zeolite including complementary single-molecule condensation and particle assembly, and alternately dominant nucleation and growth behavior, plays the critical role in zeolite crystallization but meanwhile makes us hard to study the respective effects. Herein, we strip nuclei from the synthetic solution and find that high-ordered nucleus (subcrystal) is the premise to ignite high-speed growth of zeolite crystal. The high-ordered subcrystals with the size of only 6-10 nm possess regular aperture structure and microporous area similar to zeolite nanocrystal. Interestingly, a unitary oriented aggregation process of the subcrystals towards nanosheets is well observed and characterized where single-molecule addition process is greatly repressed. If a wider range of zeotype nuclei can be expanded, a new synthetic strategy of zeotype materials with heterogeneous framework and active sites may be expected, which may novelize zeolite catalytic properties.

The process dynamics for the vacuum deposition of methylammonium lead iodide (MAPbI3) perovskite was analyzed by in situ X-ray diffraction using synchrotron radiation. MAPbI3 was fabricated by alternatingly supplying PbI2 and methylammonium iodide via a laser deposition system installed at the synchrotron beamline BL46XU at SPring-8, and in situ crystallization analysis was conducted. Microscopic insights into the crystallization were obtained, including observation of Laue oscillation during the PbI2 growth and octahedral unit (PbI6) rotation during the transformation into perovskite. On the basis of this analysis, conditions that favor the construction of atomically flat MAPbI3 perovskite films were deduced.

It is believed that the slow liquid diffusion and geometric frustration brought by a rapid, deep quench inhibit fast crystallization and promote vitrification. Here we report fast crystal growth in charged colloidal systems under deep supercooling, where liquid diffusion is extremely low. By combining experiments and simulations, we show that this process occurs via wall-induced barrierless ordering consisting of two coupled steps: the step-like advancement of the rough interface that disintegrates frustration, followed by defect repairing inside the newly formed solid phase. The former is a diffusionless collective process, whereas the latter controls crystal quality. We further show that the intrinsic mechanical instability of a disordered glassy state subject to the crystal growth front allows for domino-like fast crystal growth even at ultra-low temperatures. These findings contribute to a deeper understanding of fast crystal growth and may be useful for applications related to vitrification prevention and crystal-quality control.

In order to investigate the effect of sulfate in metatitanic acid on crystal transition and crystal growth of TiO2 during the calcination of metatitanic acid from sulfate process, ammonia was used ...

The analysis, development, and implementation of novel complex industrial crystallization processes requires kinetic knowledge of not only crystal growth and nucleation but also breakage, dissoluti...

To gain control over polymorph selection is a pivotal issue in the pharmaceutical, food, and fine chemical industry. However, the mechanisms which affect polymorph selectivity are still not fully chartered. In the present study, we demonstrated the complex crystallization behavior of l -glutamic acid under microfluidic conditions. Amorphous intermediates occur in the early stages of the experiment, which undergo a series of aging steps – such as aggregation/coalescence, growth, or shrinking – before the stable β-polymorph forms. Experiments indicated that the attachment of amorphous particles partly feds crystal growth. This complex mechanism, which was observed under laminar flow conditions, might lead to the preferential formation of a flower-like shape of β- l -glutamic acid. We accompanied these experiments, which were characterized by laminar flow-conditions, with experiments under acoustic levitation in which crystal formation takes place under constant but gentle convection in an evaporating droplet. In these experiments, a similar phenomenon was also observed. However, when crystallization was conducted in a conventional stirred-tank, a mixture of α-form and β-form was formed, characterized by a prism, needle- and plate-like morphologies instead of the distinct flower-like in earlier experiments. This demonstrates that gentle flow conditions, such as a laminar flow in a microfluidic device, preferentially leads to a complex flower-like shape than conventional approaches in a stirred tank.