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The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. It includes a cover image by Gonzalo Campillo-Alvarado and an inside cover image by Shuai Wang and Xiaoyang Dai. The highlighted articles in this issue include one on multiple synthesis routes for atomically precise noble metal nanoclusters by Lizhong He and Tingting Dong, and another on co-crystal formation versus boron coordination in azopyridines by Jesus Daniel Loya, Sidhaesh A. Agarwal, Nicholas Lutz, Eric W. Reinheimer, and Gonzalo Campillo-Alvarado. The document also mentions professional development opportunities and provides a list of papers featured in the journal. [Extracted from the article]

We proved that ice crystallized from water molecules within as-synthesized graphene oxide (GO) can be used as a spacer among individual GO sheets to form an expanded GO aerogel with a three-dimensional porous network structure. This designed specific structure can be retained during further processes to form graphene paper. Due to the fact that the as-fabricated graphene paper contains carbon defects and space in its infrastructure, this creates more electroactive surfaces and interfaces to significantly increase the Faradaic reaction efficiency. With the introduction of redox-electrolyte K3Fe(CN)6 into a KOH electrolyte, we can obtain a 95-fold increase in the specific capacitance compared with the value obtained in the traditional KOH electrolyte. The ice-crystallization formed graphene paper electrode showed high electroactivity because the specific porous structure can favor the fast transfer of electrolyte ions, such as Fe(CN)63- ions. The presented results prove that ice-crystallization formed GO can serve as a chemically tunable platform for electrochemical energy storage applications. [ABSTRACT FROM AUTHOR]

The distribution of impurities within aggregates is crucial for managing overall impurity levels and enhancing product quality. However, current detection methods often fall short to provide accurate information. This paper presents a novel fluorescence-staining method for effective solvent tagging within crystals, which can enhance impurity management. [ABSTRACT FROM AUTHOR]

Solvent induced single-crystal-to-single-crystal transformation has been demonstrated indicating the dynamic behavior of one dimensional arrays obtained from a self-assembled new synthetic cyclic peptide. [ABSTRACT FROM AUTHOR]

The paper discusses the use of ultrasound in separating different polymorphic forms of metacetamol. The study examines the influence of various sonication parameters on the separation process, including nucleation time, morphology, and number of nucleation. The results indicate that lower sonication parameters lead to the nucleation of stable form I, while higher insonation time induces the nucleation of metacetamol hemihydrate. This helps to control the nucleation of stable form I and separate the hemihydrate from pure aqueous solution with reduced nucleation time. In situ optical microscopy was used to confirm the morphology of nucleated polymorphs. Powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) analyses were used to confirm the internal structure and thermal stability of the grown stable form I and hemihydrate crystals, respectively. The study concludes that ultrasonication is a reliable, robust and optimal method that significantly impacts the crystallization and separation of metacetamol polymorphs. [ABSTRACT FROM AUTHOR]

Crystallization is an important unit operation in industry, and proteins are widely studied owing to their biological activity and multiple functions. Protein crystals can not only facilitate the elucidation of protein structural information but also have important prospects in biopharmaceuticals. However, owing to their high molecular weight and complex structure, most proteins are difficult to crystallize or the crystallization processes are difficult to control effectively. This paper aims to provide an overview of recent reinforcement techniques for protein crystallization. Several important additive applications and principles in protein crystallization are comprehensively reviewed, including ionic liquids (ILs), deep eutectic solvents (DESs), and molecularly imprinted polymers (MIPs). The mechanism of external fields, including magnetic, electric, ultrasonic, shear, and light fields, enhancing protein crystallization are described and summarized. Finally, the challenges and future research prospects of protein crystallization are proposed. This work is expected to guide the rational design of the protein crystallization process. [ABSTRACT FROM AUTHOR]

Poly(ε-caprolactone-co-trimethylene carbonate) (PCLTMC) is a biodegradable copolymer, which is widely used for medicine and tissue repair systems, and its morphology, degradation and mechanical properties have been extensively investigated. However, its crystallization behavior with different copolymerization ratios has not been studied systematically, which is of great significance for the study of property regulation and an understanding of the crystallization behavior of random copolymers. In this paper, the relationship between the crystallization temperature Tc, melting point temperature Tm and crystallinity Xc of copolymers with different molar ratios was determined by differential scanning calorimetry (DSC) using a non-isothermal crystallization method. The results show that the melting point and crystallinity of the copolymer decrease with an increase in TMC composition. The equilibrium melting point of the copolymers was predicted by an isothermal crystallization method, using the Hoffman–Weeks extrapolation method and crystallization rate growth fitting method both based on Lauritzen–Hoffman theory. It is proved that Lauritzen–Hoffman theory is of great significance for guiding the kinetic behavior of PCLTMC crystallization. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. It includes articles on various topics such as thermodynamic stability relationships of cocrystals, molecular adducts of an anti-cancer drug, and the design of cocrystals featuring a modified isoniazid derivative. The journal also highlights industrial chemistry and material innovations. The document provides a list of papers and their authors, covering a range of topics related to crystal engineering and materials science. [Extracted from the article]

Membrane crystallization (MCr) is a novel coupling technique, where the membrane can act as the interface of heterogeneous nucleation, aiming to reduce the nucleation barrier and contributing to crystal growth. This review systematically summarized the recent advances in the MCr technique. This paper first focuses on the process intensification of MCr, from model configuration to the regulation of process parameters and the development of membrane modules. Then, we review the applications of MCr in chemical engineering, including optimization of the product properties, the treatment of seawater, and the fixation of carbon dioxide. Although the MCr process displays huge potential in crystal engineering and chemical engineering fields, the problems of membrane fouling and wetting still restrict its industrial application. This review analyzes the mechanisms behind the membrane problems and proposes corresponding strategies to ensure stable and long-term operation. Finally, we propose some future perspectives for further development. [ABSTRACT FROM AUTHOR]

Isotactic polybutene-1 (iPB-1) usually crystallizes into form II from the melt first and it then spontaneously transforms into form I with outstanding properties. The mechanism of the well-known II–I transition of iPB-1 is still an open question. In the present paper, the II–I transitions of iPB-1 samples with different molecular weights were explored via differential scanning calorimetry (DSC) and X-ray scattering (SAXS) techniques after crystallization at various temperatures. It was found that the initial and final stages of the transition process depend on the molecular weight of iPB-1. A slower II–I transition rate was observed with increasing molecular weight. The total crystallinity increases significantly in the initial stages of the transition, especially for iPB-1 with high molecular weight, after crystallization at higher temperature. The long spacing, lamellar thickness, and amorphous layer thickness of iPB-1 samples with different molecular weights increase with the isothermal crystallization temperature. The SAXS results indicated that the initial crystal transition rate of iPB-1 increases with the amorphous size after isothermal crystallization at various temperatures. The transition process was discussed and a mechanism is proposed, which is helpful for understanding the transition. [ABSTRACT FROM AUTHOR]

In this paper, we focused on the influence of common serum cations on monosodium urate monohydrate (MSUM) crystal nucleation determined from cumulative probability distributions (CPDs) of solute crystal nucleation events as a function of time. Surprisingly, with an increase in the concentration of additive ions, striking "opposite effects" were observed for cations, enhancing nucleation at first followed by suppressing nucleation at physiological pH and ionic strength. This enhancing nucleation phenomenon cannot be explained based on colloidal theories or simple descriptors, such as ion size, but it is consistent with the cationic efficacy for inducing an increase in the proportion of growth units of MSUM. [ABSTRACT FROM AUTHOR]

The demand for proteins with high purity, high activity and high stability is increasing, especially in the biopharmaceutical industry. Traditional industrial protein production technologies include chromatography, which is expensive, and salting out and traditional crystallization methods, which require large amounts of salt and have an adverse effect on the environment. In recent years, a new method—solvent freeze-out (SFO) technology for protein crystallization—has been developed. Compared with traditional methods, SFO requires less salt, and can be carried out at low temperatures, resulting in more stable and active proteins. In addition, SFO can control the nucleation and crystal growth process under different supersaturation levels by setting appropriate operating temperatures, which can ensure industrial application of this technology. This paper reviews important advances in SFO technology for the crystallization of proteins. [ABSTRACT FROM AUTHOR]

Emulsions are typically formed in a mixture of immiscible liquids. However, emulsion particles are also found upon mixing miscible liquids. In this paper, we suggest that emulsion particles are formed by ethanol mixed into toluene, as detected via dynamic light-scattering and small-angle X-ray scattering spectroscopy measurements. Furthermore, the addition of ethanol into a homogeneous fullerene solution (C70/toluene) also forms emulsion particles. The emulsion particles could provide a space in which crystallization of C70 occurs via anti-solvent crystallization (ASC). The size change of the emulsion particles through coalescence and shrinkage processes, which depend on the amount of ethanol, explains the change of crystallization environment until a supersaturation state is reached. It is believed to be the previously undiscovered key indicator of the ASC mechanism prior to nucleation. [ABSTRACT FROM AUTHOR]

A general and programmed fast crystallization process (about 12 seconds) was designed to synthesize binary (MOx) and ternary (ABO3, A2BO4) metal oxide nanomaterials with controllable sizes and composition. The fast crystallization process mainly included the burning of metal-nitrate–filter-paper without additional energy supply and it can lead to the formation of exceptionally fine binary and ternary crystallites with sizes of ∼10–20 nm. The thermodynamic reduction potential of the metal-nitrate–filter-paper burning system can be estimated to be between −0.26 and 1.72 V, which can favor the occurrence of redox reactions, i.e. Cu2+→ Cu+→ Cu, Ni2+→ Ni, Co2+→ Co3+, Ce3+→ Ce4+, and Pr3+→ Pr4+. When used as anode materials for lithium-ion batteries, most of the as-burned metal oxides displayed high cycling stability. The discharge capacity of CoO nanoparticles can reach as high as 501.1 mA h g−1 after continuous 50 discharge–charge cycles at a current density of 100 mA g−1. The proposed fast crystallization route provided a versatile, facile and fast method for the synthesis of functional metal oxide nanomaterials with controllable sizes and composition. [ABSTRACT FROM AUTHOR]

For accurate estimation of crystallization driving forces, activity coefficient ratios need to be estimated. Activity coefficients in saturated solutions can be determined from solubility data if accurate pure component thermodynamic data are available. However, activity coefficients in supersaturated solutions can normally not be determined experimentally. In this paper, we investigate whether standard activity coefficient models fitted to data on saturated solutions can be used for estimation of activity coefficients in supersaturated solutions. For this purpose, we use equilibrium data for 9 polymorphic systems, for which activity coefficients can be extracted from the solubility data for each polymorph, respectively. The 3-parameter NRTL and the 2-parameter Wilson equations are fitted to the data for the more stable form, and are then used to predict the activity coefficients in the solution saturated by the metastable form, i.e. a solution that is supersaturated with respect to the stable form. It is shown that the predictions of the activity coefficients in the saturated solution of the metastable form deviate significantly from the corresponding experimental data. The activity coefficients along the solubility curve of one polymorphic form do not contain sufficient information to distinguish the influence of concentration from the influence of temperature, and accordingly the fitted equation cannot provide an independent characterisation of the influence of concentration on the activity coefficient. If the data for two polymorphic forms are used simultaneously in the regression, the models can provide a better estimation of the true driving force in crystallization processes. [ABSTRACT FROM AUTHOR]

A model was proposed for modeling the non-equilibrium crystal growth of single crystals (Y. D. Shu, Y. Li, Y. Zhang, J. J. Liu and X. Z. Wang, CrystEngComm, 2018, 20, 5143–5153). It describes mathematically and digitally the non-equilibrium growth behavior of single crystals using multi-component transfer rate models, as well as considering multi-component phase equilibria, adsorption, orientation and crystallization of individual molecules on crystal faces. In this paper, the model for single crystal growth is extended to modeling a population of crystals in a crystallizer by incorporating it into morphological population balance equations. The resulting modeling approach, i.e. the multi-stage multi-component transfer rate morphological population balance equation (M3PBE) model, is able to predict the spatial and temporal distribution of multi-components inside crystals during the course of crystallization as well as the multi-component composition of the product crystals. The new modeling approach is introduced by reference to a case study of NaNO3 batch cooling crystallization in water. [ABSTRACT FROM AUTHOR]

This paper aims to disseminate an improved technique of horizontal directed crystallization (HDC) which allows several polycrystalline or single-crystalline plates to grow in each growth process. This technique is more productive and cost-effective than the usual HDC method which allows only one plate to grow. The plates are grown under the same process conditions, and if necessary, they can be doped at the same or different impurity concentrations. The main feature of the technique developed is that the growth container is made of a heat-resistant material, for example, graphite, and has several cavities (chambers) for the raw material, sequentially located along the length of the container. For growing single-crystalline plates, all the chambers are interconnected by thin channels. We have applied this technique for growing Na-doped optical germanium plates with an area of up to 400 cm2 used for the industrial manufacturing of protective screens for thermal imaging systems used for night vision. [ABSTRACT FROM AUTHOR]

In this paper, low-temperature crystallization of well aligned TiO2 nanotubes within a record time of 20 seconds is reported. This new super-fast crystallization route with a tremendous technological impact due to its low energy budget and reproducibility involves the doping of TiO2 nanotubes with aluminium at different temperatures from 2 °C to 60 °C by applying a negative voltage to amorphous nanotubes. The process offers formation of doped anatase TiO2 nanotubes with a tuned band gap and improved conductivity. [ABSTRACT FROM AUTHOR]

The classic experiments of crystallisation of sodium chlorate by Kipping and Pope in 1898 showed that when NaClO3, an achiral salt, was crystallized from a tranquil solution, statistically equal numbers of levo and dextro crystals were obtained. Kondepudi et al. in 1990 extended Kipping and Pope's work and revealed that ＞99% of the crystals having the same handedness, i.e. total chiral symmetry breaking, were achieved when constant stirring was applied in evaporation crystallisation. In cooling crystallisation of NaClO3 at supercoolings greater than 7 °C and at a stirring rate of 300 rpm, Denk and Botsaris (1972) reported that a 50 : 50 racemic mixture of product crystals was obtained due to primary nucleation that occurred. In this paper we report, for the first time, that the size of impellers, of the same width, the same thickness, the same material of construction and operated at the same rotational speed and at the same degree of supercooling, is the exception to Denk and Botsaris's work where a stirrer of the smallest surface area led to close to 100% deracemization, while the data from the largest impeller agreed with the results of Denk and Botsaris, displaying a racemic mixture. The effects of shear, pre-seeding and surface roughness on chiral symmetry are examined to establish the likely cause of this new finding. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) is garnering interest in many applications ranging from sensors to high-frequency transducers to energy harvesters due to its piezoelectric properties. It is also an inexpensive, conformable, and more environmentally friendly alternative to polycrystalline ferroelectric ceramic lead zirconate titanate. This paper decouples the thermal and supercritical carbon dioxide (ScCO2) processing of PVDF proposed in our previous study into individual processing steps to elucidate the multi-stage crystallization mechanism of electroactive phase PVDF. Differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy were employed to analyze the processed PVDF samples. As a result, the processing-to-structure relationships with respect to each crystal polymorph (i.e., α, β and γ phases) in different phases during the multi-stage mechanism were successfully identified. The γ phase content in PVDF was predominantly governed by isothermal and non-isothermal crystallization before the ScCO2 injection as well as ScCO2-assisted isothermal crystallization before foam expansion. In contrast, the β phase content in PVDF was governed by the foaming behaviours of PVDF during the ScCO2 foaming phase. It was also observed that foam morphologies, including both cell population density and average cell size, governed the amount of local strain in PVDF matrices and thereby the α to β phase transformation during the foam expansion stage. The highest fraction of the PVDF electroactive phase achieved by the thermal and ScCO2 processing (i.e., 72.2%) was shown to be slightly better than that yielded by mechanically stretching the PVDF film (i.e., 68%). [ABSTRACT FROM AUTHOR]

In this paper, we report the influence of oxygen and hydrogen additives in the metal melt on the growth process, morphology, and defect-and-impurity structure of large single-crystal diamonds. The main experiments were performed in the Ni70Mn25Co5–C system at pressure ranging from 5.5 GPa to 6.5 GPa, temperature from 1250 °C to 1550 °C and C6H8O7 concentration from 0 to 1.0 wt%. It was found that the synthesis conditions (temperature and pressure) increase with the increasing quantity of C6H8O7 additive. As the C6H8O7 content was increased from 0 to 0.8 wt%, the presence of oxygen and hydrogen was more likely to cause defects in the {100} surface. A further increase in the C6H8O7 concentration above approximately 0.9 wt% completely terminated the nucleation and growth of the diamonds and led to the crystallization of graphite alone. FTIR, Raman and XPS test results showed that oxygen and hydrogen coexist in the diamond crystal. [ABSTRACT FROM AUTHOR]

This paper reports a very efficient and reproducible technique for room temperature crystallization of titanium dioxide in a record time of 5 minutes, by application of alternating voltage square pulses. The well aligned tubular formation of crystalline nanotubes is confirmed through various characterization techniques, and the mechanism of crystallization is explained based on the pulse induced electrophilic–nucleophilic reaction. This ultrafast pulsed crystallization method provides a viable alternative for the widely used post fabrication thermal annealing and is highly applicable in device fabrication. [ABSTRACT FROM AUTHOR]

This paper reports the TiO2 seed-assisted hydrothermal growth of VO2 films on a quartz substrate. The rutile TiO2 seed layer can promote the oriented growth of VO2(M) at the initial stage of the hydrothermal reaction, and then, the VO2(D) phase further grows on top of the VO2(M) layer. It was found that a pure VO2(M) thin film can grow on the TiO2 seed layer at a temperature as low as 200 °C. A subsequent annealing treatment can transform the VO2(D) phase to the VO2(M) phase. The VO2(M)/TiO2 composite films display thickness-dependent optical and electrical performance, and nearly 55% infrared modulation at 3 μm and 3 orders of magnitude resistance modulation can be realized. Our results demonstrate important progress in growth of VO2(M) thermochromic thin films, which will find potential application in constructing VO2-based switching devices. [ABSTRACT FROM AUTHOR]

Crystal size and shape control is of great importance to the pharmaceutical industry and is a key factor in product performance. In this paper, we used acoustic streaming to control the crystal size and shape in a drying droplet. [ABSTRACT FROM AUTHOR]

Lead oxide is an important glass modifier not only for affecting the chemical and mechanical stabilities of glasses, but also for improving their thermal and optical properties. Since specific properties are associated with the presence of PbO, its crystallization is important to enhance the material performance. Although considerable advances have been achieved regarding the fabrication of glass-ceramic from lead-based glasses, the spatial confinement of the crystallization remains challenging. Direct laser writing (DLW) has been considered an essential technique to overcome this issue, since material properties can be changed in localized and pre-determined regions. Although DLW with femtosecond laser pulses has been widely used for glass processing, its usage for phase transformations and control of the architecture of crystals has not been much exploited. This paper reports the design and control of β-PbO and 3PbO·H2O crystalline phases in a lead borate glass using fs-DLW followed by chemical etching at room temperature. We demonstrated that the etching in aqueous KOH solution is responsible for the glass crystallization, whereas the grooves produced by fs-laser pulses enable the selective crystallization in a pre-determined 2D pattern. The method described herein is important as it can control phase transformation at the micrometer scale and also permits the growth of lead oxide and lead oxide hydrate phases, which are not achieved by heat treatment. The morphologies of these microcrystals correspond to the structure of the respective compounds, being an octahedral euhedral crystal for 3PbO·H2O and thin sheets for β-PbO crystalline phases. [ABSTRACT FROM AUTHOR]

In this paper, the optimal growth conditions during the physical vapour transport of bulk AlN crystals are evaluated with regard to significantly increased deep UV transparency, while maintaining the high structural quality of the AlN crystals which are grown on N-polar c-facets. We show that carbon concentration [C], oxygen concentration [O], and the ratio between both concentrations [C]/[O] have a significant influence on the deep UV transparency. At 3[C] ＜ [O] with [C] + [O] ＜ 1019 cm−3, deep UV transparent AlN single crystals with absorption coefficients at around 265 nm (α265nm) smaller than 15 cm−1 can be prepared. These conditions can be achieved in the N-polar grown volume parts of the AlN crystals using growth temperatures in the range of TG = 2030–2050 °C and tungsten and tantalum carbide as getter materials for carbon and oxygen, respectively. Deep UV transparent AlN substrates (α265nm ＜ 30 cm−1) ≥10 mm in diameter and of high crystalline perfection (rocking curve FWHM ＜ 15 arcsec) are shown for the first time. [ABSTRACT FROM AUTHOR]

Environments with varying temperatures have been shown to beneficially increase the probability of obtaining protein crystals. Therefore, a cycling temperature strategy (CTS) has been proposed for protein crystallization screening. During the practical application of this strategy, it is necessary to know the effective temperature range that promotes crystallization to design a suitable temperature program. In this paper, the effects of different temperature ranges on lysozyme crystallization (or more specifically, nucleation) were investigated. The results show that a small periodic variation in the temperature range of as little as 0.4 K can have a significant effect on the crystallization success rate under some crystallization concentration conditions, confirming that crystallization of lysozyme is very sensitive to temperature variation. Because practical protein crystallization is always performed in an environment with slight temperature variations, the sensitivity of protein crystallization to temperature may provide an explanation for the poor reproducibility of protein crystallization. Further investigation of the CTS on lysozyme crystallization showed that a cycling temperature strategy exerts an effect on protein crystallization by altering the supersaturation caused by changes in temperature. [ABSTRACT FROM AUTHOR]

The effects of crystallization on the formation of geochemical, biological, and synthetic materials have been motivating decades of research into crystal nucleation and growth processes. The development of crystal growth theories and models can deepen the understanding of physicochemical interactions during the crystal growth process, which facilitates the designing of crystallization approaches in material production. The chemical bonding theory of single crystal growth emphasizes the dominant role of dynamic chemical bonding mechanisms at the growing interfaces. In this paper, we highlight the chemical bonding theory of single crystal growth from the chemical reaction viewpoint, by focusing on the atomic level of the growing interface between the liquid and crystal phases. Using ZnO, CeO2, MnO2 and Y3Al5O12 as examples, we review some typical applications of the chemical bonding theory of single crystal growth in calculating crystal habits, evaluating crystal properties, and guiding practical single crystal growth. Microscopically speaking, the essence of crystal growth and design is to create ideal chemical bonding architectures at both the crystal surface and the growing interface via both thermodynamic and kinetic strategies. [ABSTRACT FROM AUTHOR]

This paper will review the crystal growth mechanism of zeolites and discuss some of the latest findings in this field. A great effort has been dedicated in recent years to improving the fundamental understanding of zeolite crystal growth during the synthesis process, with the overall aim of increasing control over the zeolite properties and structure. The latest studies on zeolite crystallization in colloidal (clear) suspensions, prepared by addition of organic and inorganic structural directing agents, in comparison to traditional gel synthesis and seed-approach will be discussed. Further understanding of the imperative dependence of zeolite crystallization kinetics' on the nature and mode of mixing of the initial reactants, leading to the formation of amorphous particles, intermediates, and final crystalline zeolites will be presented. [ABSTRACT FROM AUTHOR]

Crystallisation of proteins is usually achieved with the help of chemical agents. Because there are few general guidelines in determining what agents will help to crystallise a specific protein, suitable crystallisation agents are often found via exhaustive trial-and-error tests by mixing many chemical agents (the collection of which is called a crystallisation screening kit) one-by-one with the protein. Currently, many commercially available crystallisation screening kits have been developed and utilised in practical crystallisation screen experiments. However, information regarding the design of new screening kits has yet to be expanded using a large amount of experimental data. Here, we show the step-by-step design processes of a polyethylene glycol-based screening kit. It was found that the screening performance could be improved by modifying the crystallisation screening kits according to the accumulated data (such as those in the Biological Macromolecule Crystallisation Database (BMCD)), the screening test results and existing knowledge. The screening kit designed in this paper can be used for practical protein crystallisation screen experiments and the method can be used in the design of other crystallisation screening kits. [ABSTRACT FROM AUTHOR]

In this paper, the effect of Sb2Se on the phase change characteristics of Ge2Sb2Te5 (GST) is systemically studied for applications in phase-change random access memory (PRAM). The crystallization temperature of Sb2Se–GST increases with increasing Sb2Se content, while the archival life of the amorphous state first decreases and then increases. The phase transition from face-centered-cubic (FCC) to hexagonal (HEX) is suppressed when the Se atomic percentage is higher than 9% for Sb2Se–GST films. The wide band gap and high value of B1/2 lead to a contrast in resistance of about five orders of magnitude between the amorphous and crystalline states. Compared with GST, Ge4Sb52Te9Se35 shows a high crystallization temperature, a wider band gap and a fast switching speed, suggesting it is a potential candidate for PRAM. [ABSTRACT FROM AUTHOR]

Perovskite oxide (La1-xSrxMnO3) crystal facet control is rarely reported due to difficulties in modulation, even though it is highly important in surface-dependent catalytic and electrochemical applications. In this paper, we present the shape diversity of La1-xSrxMnO3 crystals evolved from a hydrothermal environment when urea is used as an effective facet modulator. By changing the La/Sr ratio from 1 to 3, the structure changes from pseudo-cubic to P21/a monoclinic, induced by the evolution processes of different facets during crystallization. Our proposed hypothesis is that the NH4+ interaction with octahedral MnO6 may be beneficial in enhancing the activity of La1-xSrxMnO3 for applications, and moves toward strategies for the development of highly active perovskite oxides. [ABSTRACT FROM AUTHOR]

Here we report a study on controlling the shape of particles by regulating the diffusion of chemicals. To change the diffusion rate of the reactive ions, we used a designed three-cell reactor in which the reactive ions were separated by porous membranes. We studied the reduction of hexachloroplatinate ions by sodium borohydride as an example. The experimental results show that control of the chemical diffusion led to the platinum product changing from cubic particles to dendritic particles. Further analysis indicates that the cubic particles were formed by the classic crystallization process via layer-wise deposition, while the dendritic particles were formed by the non-classic crystallization process through cluster aggregation. The control over the chemical diffusion prolongs the nucleation period and produces nuclei continuously, facilitating the aggregation of nuclei, which leads to the crystallization switching from the classic model to the non-classic model. The obtained results in this paper suggest that control over the chemical diffusion is a green and promising process to manipulate the structures of materials. [ABSTRACT FROM AUTHOR]

The main aim of the studies in this paper is to gain knowledge on the path of structural transformations resulting from the photocyclization in 2-tert-butylphenylphenylmethanone crystals at low and high pressures and also to carry out a comparative analysis of the results at different pressures. This work is the first example of these types of studies in scientific literature. We determined the structure of: pure reactant crystals, i.e. only containing reactant molecules, at 0.1 MPa, 0.55 GPa, 1.27 GPa and 1.50 GPa; pure product crystals, i.e. only containing product molecules, at 0.55 GPa and 1.27 GPa; and partly reacted crystals (ten structures), i.e. containing both reactant and product molecules in various proportions to each other, at 0.1 MPa (two structures), 0.55 GPa (three structures), 1.27 GPa (three structures) and 1.50 GPa (two structures). The studies have shown that (a) there is no phase transition when an increase in pressure is imposed onto the crystals, (b) the unit cell parameters change non-linearly with an increase in pressure, (c) the photochemical reaction was conducted in a homogeneous manner in the examined crystals, (d) the reaction brings about different modes of changes in the unit cell parameters at different pressures (e) the reaction proceeds faster at the end rather than at the beginning regardless of the pressure imposed onto the crystals. [ABSTRACT FROM AUTHOR]

The use of knowledge-based methods has been intimately connected with the field of co-crystal design since the seminal papers of Etter and Desiraju in the 1990s. Here we explain and exemplify how rational co-crystal design has been carried out in the past using crystal structure knowledge as well as presenting emerging methodologies for knowledge-based co-former selection. [ABSTRACT FROM AUTHOR]

The triazoylketone discussed in this paper crystallises from racemic solutions as a conglomerate. Here, we report the ternary phase diagram confirming the conglomerate behaviour of this molecule. Through computation we also explore the underlying reasons for the absence of a racemic compound in this system and the evident epitaxial crystallisation leading to crystals of almost racemic compositions but which retain the crystal structure of the pure enantiomer. [ABSTRACT FROM AUTHOR]

A methodology to increase the device purpose yield of a KDP crystal is reported in this paper. The method is based on increasing the cross-section of the prismatic sector {100} of the growing KDP crystal at the expense of the unusable pyramidal cap portion by restricting the growth of the crystal up to a particular height, decided by the solution–air interface in the crystallizer. Due to the lack of solution above the interface, the crystal ceases to grow in the upward direction whereas it continues to grow laterally. This leads to an increase in the usable volume of the grown crystal for the fabrication of crystal elements required for electro-optic switching and frequency conversion applications. An empirical relationship has been introduced as a condition to grow flat-top shaped KDP crystals. It relates the growth parameters with the apparatus design parameters. Several flat-top shaped crystals have been grown as a validation of the growth methodology and the empirical relationship. The influence of the growth methodology on the crystalline quality of the grown crystal was assessed by measuring the defect structure of different sectors of the grown crystal by X-ray topography (XRT). The crystalline perfection was estimated by recording the rocking curve widths using high resolution X-ray diffraction (HRXRD). The optical quality was assessed by measuring the UV-vis-NIR transmission of the different sectors of the crystal and the refractive index homogeneity using interferometric techniques of conoscopy. It is found that restricting the growth of the crystal in the [001] direction by the solution–air interface does not have any detrimental effect on the crystalline and optical qualities of the grown crystal. [ABSTRACT FROM AUTHOR]

This paper explores the selective crystallization of a metastable phase and the possible role played by the internal fluid dynamics characteristic of microdroplets. The density-driven convection is suppressed inside the microdroplets due to its high surface tension. It is suggested that as a consequence, this lowered the solute concentration at the area near the growing crystal. This phenomenon is thought to suppress the second crystallization near the first grown crystal and the transition from a thermodynamically metastable phase to a stable phase. [ABSTRACT FROM AUTHOR]

The control over crystal polymorphism is a well-established subject in crystallization and materials chemistry. In recent years, self-assembled monolayers (SAMs) with different functionalized groups have been used as a new chemical approach to control crystal nucleation and polymorphism. In this paper, we focus on a study of the different mechanisms involved in polymorphism control by crystallization onto SAMs. We study the crystallization of l-glutamic acid on SAMs with various functionalized end groups: R–OH, R–CH3 and R–COOH. Furthermore, in this work we select crystallization conditions in which we can identify different mechanisms of polymorphism stabilization and show that functionalized SAMs can be used to stabilize crystal polymorphism by means of crystal adsorption from the crystallization solution onto SAMs, and not merely by nucleation and crystal growth onto the SAMs. [ABSTRACT FROM AUTHOR]

In this paper, we have built up the organic-inorganic hybrid co-crystal (1) by using the derivative of ethylenediammonium cations (N,N,N′,N′-tetra-p-methoxybenzyl-ethylenediamine, L1) and [CuCl4]2−anions. The reaction was carried out by mixing MeOH solution of CuCl2·2H2O and HCl/MeOH solution of L1at room temperature. Two types of inclusion compounds can be formed when using different guest molecules. When guest molecules, such as anthracene or phenanthrene, were included, it resulted in the formation of interlayered structures: anthracene ⊂ [H2L1]2+·[CuCl4]2−(2) and phenanthrene ⊂ [H2L1]2+·[CuCl4]2−(3). When β-naphthyl phenol were included, it led to the formation of pillared-layered complexes of [1-chloride-β-naphthyl phenol]1.0·[β-naphthyl phenol]0.5·[methanol]1.0⊂ 2[H2L1]2+·2Cl−·[CuCl4]2−(4). [ABSTRACT FROM AUTHOR]

The paper reports on the molecular and crystal structure of the diastereomeric salt (4) formed by the (11-oxo-11H-dibenzo[b,f][1,4]thiazepin-10-yl)-acetate (H−12) and the brucinium resolving agent. Experimental evidences suggest that the salt was obtained by a crystallization-induced dynamic resolution of the tricyclic compound 2, which seems to constitute the first example of successful application of this technique to tricycles of this kind. A systematic comparison with already published structural data of compounds containing brucine (molecule/ion) evidences that in 4the resolving cation assembles in an unusual host framework. A review of the solid state structures containing brucine/brucinium moieties available in the literature provides some simple rules which help to exclude/identify a priorithe supramolecular host (brucine molecule/ion) framework. [ABSTRACT FROM AUTHOR]

This paper investigates crystal growth modifiers based on 1,3,5-substituted benzene derivatives. The results show that as expected, the phosphonated derivative inhibits calcite precipitation to a much greater degree than the analogous sulfonate. However, on barium sulfate, both molecules show some crystallization promotion behaviour, with the phosphonate being the more potent promoter overall. Thus, the functional group alone does not determine the impact the organic molecule will have on crystallization. This opens the way for additives that have dual purposes (inhibiting the crystallization of one phase while not impacting or promoting the crystallization of other phases). [ABSTRACT FROM AUTHOR]

Twelve new crystalline products (1–12) presented in the paper are the result of different or similar recognition of N-(4-nitrobenzoyl)-d- and N-(4-nitrobenzoyl)-l-serine by brucine dependent on the solvent used (methanol or ethanol), as well as how the sample for crystallization was prepared. Depending on the temperature at which the samples for crystallization were prepared, racemic resolution of N-(4-nitrobenzoyl)-dl-serine can be efficient or inefficient (4and 1). [ABSTRACT FROM AUTHOR]

This paper reports the first evidence of the contribution of T-shaped aromatic CHπ interactions to the crystallization of 2-aryl-2-methoxypropanoic acid and amide. The crystal structures of (S)-2-methoxy-2-(9-phenanthryl)propanoic acid [(S)-M9PP acid, (S)-3] and a diastereomeric amide 6, prepared from (R)-2-methoxy-2-(1-naphthyl)propanoic acid [(R)-MαNP acid, (R)-1] and (S)-1-(1-naphthyl)ethylamine [(S)-4], were determined by X-ray crystallography. Like those of M9PP and MαNP esters, the carbonyl and methoxy groups of (S)-3exhibited synconformation. The crystal structure of (S)-3was stabilized by consecutive intermolecular OHO hydrogen bonds between the carboxy groups. In addition, the 9-phenanthryl groups formed a herringbone structure viaaromatic CH π interactions. The anticonformation of the carbonyl and methoxy groups was observed in the crystal of amide 6, indicating an NHO hydrogen bond. The two 1-naphthyl groups were parallel to one another and located on the same side of the MαNP plane, forming a herringbone structure with adjacent molecules. NMR analyses suggest that, in solution, intramolecular aromatic CHπ interactions induce the 1-naphthyl groups to form a slant-parallel conformation. Namely, both the length and interactions between the substituents are important for crystallization. Normal-phase HPLC separation of diastereomeric amides is also discussed. [ABSTRACT FROM AUTHOR]

In a recent paper, Yang (CrystEngComm, 2015, 17, 577) proposed a complicated summation equation to relate the induction time to the metastable zone width (MSZW) in cooling crystallization based on the classical nucleation theory. In Yang's model, nucleation is assumed to occur when the accumulated nucleation potential approaches the critical nucleation potential in both the induction time and the MSZW experiments. However, the definition of the accumulated nucleation potential and critical nucleation potential is ambiguous. In this comment, the MSZW limit is defined, the same as the induction time as the time needed for the number density of accumulated crystals to reach a fixed (but unknown) value, fN. An integral equation is developed to predict MSZW from the induction time results based on the classical nucleation theory. [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented which discusses various papers published within the issue, including one on mesocrystal formation and non-classical crystallization of pre-synthesized nanoparticles, one on the crystallization of metal nanoparticles with self-assembled monolayers of ligands, and another on the assembly of semiconductor metal-chalcogenide nanorods.

Olefin block copolymer (OBC) is a novel thermoplastic elastomer possessing multiblock features but has limited mechanical property due to a partial-branched hard segment. In this study, olefin block copolymer was blended with linear polyethylene (PE) with varying molecular chain lengths in order to investigate the influence of linear polyethylene on the mechanical performance, crystallization behavior and crystalline morphology of OBCs. It was found that the addition of PE is in favor of enhancing the mechanical properties of OBC. The long PE chains are more effective for reinforcing, and thus a rubber-to-plastic transition occurs when a large amount of ultra-long PE chains is introduced. At the same time, a small addition of PEs can be fully miscible with OBC and induces co-crystallization behavior. In this way, the tie effect from the PE chains was gradually enhanced particularly for OBC/PE samples blended with ultra-long chains. In addition, crystal orientation can be further enhanced in OBC/PE blends when shear flow is applied. More interestingly, shish–kebab structure is achieved where ultra-long PE chains act as the shish, while hard segments of OBC grow epitaxially on the shish to form kebabs. Our study shows a highly effective self-reinforcing mechanism through the regulation of crystalline morphologies for OBC multiblock copolymers, in which the unique shish–kebab structure was successfully established based on an entangled system. [ABSTRACT FROM AUTHOR]