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Experimental and simulation studies were conducted for surface segregation-limited kinetics of nitrogen incorporation into a 4H-SiC crystal during physical vapor transport (PVT) crystal growth. It was revealed that the nitrogen incorporation is kinetically limited by the step-flow velocity on the growing crystal surface of a 4H-SiC crystal; in this study, the surface step-flow velocity at the growth front was deduced from the local inclination angle of the growth front measured from the (000 1 ¯) plane, assuming a uniform growth rate along the c-axis (crystal growth direction) across the growth front, and the nitrogen concentration across the growth front was measured using Raman scattering microscopy. The step-flow velocity dependence of nitrogen incorporation was theoretically analyzed using a two-site-exchange model, and the simulated dependence using the model was in good agreement with the experimental data. On the basis of these experimental and simulation results, kinematical and energetical aspects of nitrogen incorporation at the growth front of a 4H-SiC crystal during PVT growth are discussed. [ABSTRACT FROM AUTHOR]

Salt solubility is generally determined under isotropic stress conditions. Yet, in the context of salt weathering of porous media, mechanical constraints on the in-pore growth of salt crystals are likely to be orientation-dependent, resulting in an anisotropic stress state on the crystal. In this paper, we determine by molecular simulation the solubility of NaCl in water when the crystal is subjected to anisotropic stress. Such anisotropy causes the chemical potential of the crystal to be orientation-dependent, and proper thermodynamic formulation requires describing the chemical potential as a tensor. The solute and crystal chemical potentials are computed from free energy calculations using Hamiltonian thermodynamic integration, and the usual condition of solubility is reformulated to account for the tensorial nature of the crystal chemical potential. We investigate in detail how the uniaxial compression of the crystal affects its solubility. The molecular simulation results led to revisiting the Correns law under anisotropic stress. Regarding the solute, the non-ideal behavior of the liquid phase is captured using Pitzer's ion interaction approach up to high concentrations of interest for in-pore crystallization and beyond the concentrations addressed in the existing literature. Regarding NaCl crystals, the validity of the generalized Gibbs–Duhem equation for a tensorial chemical potential is carefully verified, and it is found that crystallization progresses almost orthogonally to the crystal surface even under high shear stresses. Comparing uniaxial and isotropic compression highlights the major differences in solubility caused by stress anisotropy, and the revisited Correns law offers an appropriate framework to capture this phenomenon. [ABSTRACT FROM AUTHOR]

The generation of sub-grains during the preparation of AlN crystals by physical vapor transport (PVT) method can reduce crystal quality, and even lead to the development of polycrystallization. In this paper, the generation and evolution of sub-grains were studied by adjusting the thermodynamic and kinetic growth conditions, and effective suppression methods were proposed to regulate crystal growth mode. The experimental results show that the large temperature fluctuation leads to the large fluctuation of the gaseous substances supersaturation on the crystal surface. It promotes the formation probability of highindex facets, which are difficult to achieve perfect coalescence due to non-uniformity. The influence of the transport path of gaseous substances on the crystal growth mode under the condition of a stable temperature field was also studied. The experimental and simulation results show that during the crystal growth under the traditional crucible structure, the transmission path of gaseous substances migrates from the edge to the center on the crystal surface, which is opposite to the direction of the growth step. The crystal surface is prone to forming step clusters and evolving into Stranski-Krastanov growth mode. A novel crucible was designed to enable the migration of gaseous substances along the crystal growth step direction, which met the basic conditions of layer-by-layer growth. The experimental results of growth temperature from 2 200 ℃ to 2 300 ℃ show that as the decrease of temperature, crystal growth exhibits c-axis dominant growth, and lateral expansion capability decreases. As the temperature increases, the lateral expansion capability increases, but the probability of the formation of high-index crystal facets increases continuously. When the temperature is about 2 250 ℃, the two reach a balance, which is suitable for the suppression and elimination of sub-grains. Combined with BCF theory analysis, reducing the supersaturation enhances the two-dimensional tiling ability of screw dislocation-driven growth, and increases the growth step width, which is conducive to dispersing sub-grain boundaries into step flow. The optimized experimental results show that the Stranski-Krastanov growth mode gradually changes to a screw dislocation-driven growth mode, and the sub-grains are gradually annihilated. The high-quality AlN crystals were obtained, with an X-ray single crystal rocking curve full width at half maximum values of 58″ on AlN (0002) surface, a Raman spectrum E2 (High) full width at half maximum value of 3. 3 cm-1, and a dislocation density on the crystal surface of 2. 87 ×103 cm-2. [ABSTRACT FROM AUTHOR]

Organic solvents host the synthesis of high-value crystals used as pharmaceuticals and optical devices, among other applications. A knowledge gap persists on how replacing the hydrogen bonds and polar attraction that dominate aqueous environments with the weaker van der Waals forces affects the growth mechanism, including its defining feature, whether crystals grow classically or nonclassically. Here we demonstrate a rare dual growth mode of etioporphyrin I crystals, enabled by liquid precursors that associate with crystal surfaces to generate stacks of layers, which then grow laterally by incorporating solute molecules. Our findings reveal the precursors as mesoscopic solute-rich clusters, a unique phase favored by weak bonds such as those between organic solutes. The lateral spreading of the precursor-initiated stacks of layers crucially relies on abundant solute supply directly from the solution, bypassing diffusion along the crystal surface; the direct incorporation pathway may, again, be unique to organic solvents. Clusters that evolve to amorphous particles do not seamlessly integrate into crystal lattices. Crystals growing fast and mostly nonclassically at high supersaturations are not excessively strained. Our findings demonstrate that the weak interactions typical of organic systems promote nonclassical growth modes by supporting liquid precursors and enabling the spreading of multilayer stacks. Organic solvents are used to produce high-value crystals such as pharmaceuticals, organic semiconductors, and optical devices, but our understanding of the fundamental processes of crystal growth from organic solutions is limited. Here, the authors use time-resolved in situ atomic force microscopy to show a nonclassical, dual growth mode of etioporphyrin I crystals from mesoscopic solute-rich clusters. [ABSTRACT FROM AUTHOR]

Context: Ammonium perchlorate (NH4ClO4, abbreviated as AP) has the advantages of high oxygen content, high density, and good compatibility, and has significant application prospects in the field of energetic materials. The crystal morphology has a great influence on the properties and sensibility of energetic materials, and a single experimental means is difficult in exploring the crystals; therefore, the crystal morphology of AP is investigated using molecular dynamics simulation complemented with experiments, to theoretically analyze the differences in AP crystal habit and the interactions between solvent molecules and the main growing crystal surfaces of AP. The results show that AP crystal is mainly composed of five independent crystal surfaces (0 0 1), (0 1 0), (1 0 0), (1 0 1), and (1 0 −1) in vacuum using the BFDH laws, with (0 0 1) surface being the main growth crystal surface. In contrast, in H2O solvent, the (1 0 1) and (1 0 −1) surfaces disappear, and the AP mainly consists of (0 0 1), (0 1 0), and (1 0 0) surfaces with a rectangular shape. The crystal morphology obtained from theoretical prediction is in good agreement with that obtained from experimental culture. This paper can provide a new idea for the cultivation and preparation of AP large crystals, and promote the application of AP crystals in energetic materials. Methods: The crystal morphologies of AP in vacuum and H2O solvent under Dreiding force field were predicted based on attachment energy model by using molecular dynamics method in Materials Studio 2019 software. The entire molecular dynamics simulation was carried out under the NTV system, the temperature control method was selected as Anderson, and the system temperature was set to 298 K. The simulation time was set to 40 ps, the step size was set to 1 fs, and the data were outputted every 5000 steps. [ABSTRACT FROM AUTHOR]

Context: Ammonium perchlorate (NH4ClO4, abbreviated as AP) has the advantages of high oxygen content, high density, and good compatibility, and has significant application prospects in the field of energetic materials. The crystal morphology has a great influence on the properties and sensibility of energetic materials, and a single experimental means is difficult in exploring the crystals; therefore, the crystal morphology of AP is investigated using molecular dynamics simulation complemented with experiments, to theoretically analyze the differences in AP crystal habit and the interactions between solvent molecules and the main growing crystal surfaces of AP. The results show that AP crystal is mainly composed of five independent crystal surfaces (0 0 1), (0 1 0), (1 0 0), (1 0 1), and (1 0 −1) in vacuum using the BFDH laws, with (0 0 1) surface being the main growth crystal surface. In contrast, in H2O solvent, the (1 0 1) and (1 0 −1) surfaces disappear, and the AP mainly consists of (0 0 1), (0 1 0), and (1 0 0) surfaces with a rectangular shape. The crystal morphology obtained from theoretical prediction is in good agreement with that obtained from experimental culture. This paper can provide a new idea for the cultivation and preparation of AP large crystals, and promote the application of AP crystals in energetic materials. Methods: The crystal morphologies of AP in vacuum and H2O solvent under Dreiding force field were predicted based on attachment energy model by using molecular dynamics method in Materials Studio 2019 software. The entire molecular dynamics simulation was carried out under the NTV system, the temperature control method was selected as Anderson, and the system temperature was set to 298 K. The simulation time was set to 40 ps, the step size was set to 1 fs, and the data were outputted every 5000 steps. [ABSTRACT FROM AUTHOR]

In this study, a novel MgO–C refractory, fabricated through high–temperature nitriding, was developed by incorporating Si–Al 4 SiC 4 to in–situ form plate–like Mg–sialon ceramic bonding phase in situ. The influences of Al 4 SiC 4 content and nitriding temperature on the phase transformation, microstructure, and mechanical properties of MgO–C refractories were examined. The synergistic effect of Si co–existed with Al 4 SiC 4 promoted the in–situ formation of plate–like Mg–sialon, thereby accelerating the densification of MgO–C refractories. The primary crystal growth surface for Mg–sialon was identified as the (100) facet. The plate–like Mg–sialon was integrally bonded within the matrix, enhancing the interfacial bonding with MgO particles, rather than merely adhering to the surface. The incorporation of 2 wt% Al 4 SiC 4 significantly optimized the microstructure of MgO–C refractories, culminating in superior mechanical properties when nitrided at 1400 °C. Furthermore, the formation mechanism and morphological evolution of the plate–like Mg–sialon in MgO–C refractories were explored. • Novel in–situ Mg–sialon enhanced low–carbon MgO–C refractories have been developed. • The coexistence of Si with Al 4 SiC 4 synergistically facilitated the in-situ formation of plate-like Mg-sialon. • The addition of 3 wt% Si and 2 wt% Al 4 SiC 4 demonstrated optimal properties for the novel refractories. • The thermodynamics of the nitridation process was simulated and calculated. • Mg–sialon formation occurs predominantly through a solution–precipitation mechanism. [ABSTRACT FROM AUTHOR]

The second formation stage of a surface martensite (SM) crystal is associated with a layer-by-layer extension of its faces. A dynamic pattern of every layer formation is similar to a rapid crystal growth in the first stage. The role of dislocation nucleation centers belongs to the dislocations framing the crystal-face surfaces. By the example of the (10-1) face it is shown that the proposed dynamic mechanism is compatible with the observed polar growth of the SM crystal trace on the (100) surface of the sample and the range of its visually observed growth. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) plays a vital role in devices used in several fields, such as communications, displays, and lighting. The quality of SiC growth is critical to the fabrication of high-performance SiC devices; thus, it is important to explore its growth mechanism. Herein, we used approaches based on molecular dynamics to simulate the induced crystallization process of 3C-SiC crystal based on a solid–liquid model. In addition, we proposed an expression for the degree of nonuniform crystal growth, allowing us to dynamically and quantitatively describe the crystal growth process. The results show that the crystal growth quality is unsatisfactory at low temperatures, with a high defect density and uneven growth of crystal faces. In addition, the process of SiC crystal growth generates rival growth patterns across each crystal growth direction, with the crystal preferentially proliferating along the direction with relatively lower growth competition. Although the system exhibits dislocation and void defects, the number of these defects exhibits opposing trends during relaxation. In addition, as crystal faces grow progressively, the process involving the filling of concave surfaces with crystal atoms is gradually transferred to the amorphous gaps within the system. Finally, this study provides insights into the formation of SiC crystal. [ABSTRACT FROM AUTHOR]

Mixed-dimensional van der Waals (vdW) heterostructures offer promising platforms for exploring interesting phenomena and functionalities. To exploit their full potential, precise epitaxial processes and well-defined heterointerfaces between different components are essential. Here, we control the growth of one-dimensional (1D) vdW microwires on hexagonal crystals via plasma treatment of the growth templates. AgCN serves as a model 1D system for examining the dependence of the nucleation and growth parameters on the surface treatment conditions and substrate types. The oxygen-plasma-treated transition metal dichalcogenides form step edges mediated by formation of surface metal oxides, leading to robust AgCN epitaxy with an enhanced nucleation density and low horizontal growth rates. Monte Carlo simulations reproduce the experimentally observed growth behaviors and unveil the crucial growth parameters, such as surface diffusivity. The plasma treatment results in distinct effects on graphite and hexagonal boron nitride templates, which undergo plasma-induced amorphization and deactivation of the AgCN vdW epitaxy. We achieve the selective growth of AgCN microwires on graphite using the deactivated vdW epitaxy. This study offers significant insights into the impact of surface treatment on 1D vdW epitaxy, opening avenues for controlled fabrication of mixed-dimensional vdW heterostructures. [ABSTRACT FROM AUTHOR]

ZnO microcrystal arrays have been grown on a (111) silicon substrate by the vapor‒liquid‒crystal deposition, where the liquid phase is gold. The differences between the crystals obtained for growth times of 5, 10, and 15 min are described. The lattice parameters of the microcrystals have been calculated with increasing growth time: а = 3.316 Å, c = 5.281 Å; а = 3.291 Å, c = 5.270 Å; and а = 3.286 Å, c = 5.258 Å. A change in the Au content in the microcrystals during their growth has been found to vary from 0.520 at % at the substrate to 0.035 at % on the surface of the crystals after the 15-min growth. Elemental distribution maps are presented, and the deviation of the lattice parameters of the obtained crystals from the reference values is explained. [ABSTRACT FROM AUTHOR]

Crystal‐hosted melt embayments and melt inclusions partially record magmatic processes at depth, but it is not always obvious how to interpret this record. One impediment is our incomplete understanding of how embayments and melt inclusions form. In this study, we investigate the formation mechanism of embayments and melt inclusions during quartz growth to quantify the relationship between the compositions of the entrapped and average melt. We study the growth of embayments and inclusions through direct numerical simulations that couple the growth of a crystal surface with the evolution of the concentrations of incompatible components in the surrounding melt. We find that H2O is more enriched in the interior of defects on crystal surface compared to the exterior. The resultant lower disequilibrium in the defect interior causes lower growth rate than in the exterior, elongating the defect into an embayment. If crystal growth stops, the composition in the embayment equilibrates with the average melt within days to months. If crystal growth continues until the embayment neck closes, a melt inclusion forms. The melt entrapped by both embayments and melt inclusions is enriched in incompatible components, such as H2O and CO2. In addition to inclusion size, the enrichment of incompatible components in melt inclusions also depends on component diffusivity and the crystal growth regime. High‐diffusivity components like H2O have similar enrichment levels in all scenarios, while lower‐diffusivity components like CO2 are more enriched in melt inclusions with smaller sizes or formed in continuous crystal growth. Plain Language Summary: Embayments and melt inclusions are small droplets of melt entrapped by crystals. These droplets may contain valuable clues for understanding processes inside volcanoes inaccessible to direct observation, because they typically form at depth before the onset of eruptions. Embayments are partially connected to exterior melt and can record processes during eruption. Melt inclusions are fully isolated and can record magma compositions at depth. However, we do not yet understand how they form. Our lack of understanding hinders our ability to interpret this data. Here, we use numerical simulations to quantify how the enrichment of dissolved water in the melt near the crystal affects the formation of embayments and melt inclusions during quartz growth. There is a positive feedback between the water enrichment in the embayment interior and embayment elongation, because water is not integrated into the quartz as it grows. Our simulations put constraints on the application of embayments and melt inclusions to constrain volcanic processes: For embayments, component enrichment likely equilibrates with surrounding melt prior to eruption. For melt inclusions, high‐diffusivity components like water are similarly enriched in all scenarios, while lower‐diffusivity components like carbon dioxide are more enriched in smaller inclusions formed in continuous crystal growth. Key Points: Embayments can form from crystal defects because water is more enriched inside the defect than outsideEnrichment of incompatible components in embayments likely equilibrates in pre‐eruptive magma storageCarbon dioxide is more enriched in smaller melt inclusions formed in continuous crystal growth but water has similar enrichment in all cases [ABSTRACT FROM AUTHOR]

Polar crystal surfaces play an important role in the functionality of many materials and have been studied extensively over many decades. In this article, a theoretical framework is presented that extends existing theories by placing the surrounding solution environment on an equal footing with the crystal itself; this is advantageous, e.g., when considering processes such as crystal growth from solution. By considering the polar crystal as a stack of parallel plate capacitors immersed in a solution environment, the equilibrium adsorbed surface charge density is derived by minimizing the free energy of the system. In analogy to the well-known diverging surface energy of a polar crystal surface at zero temperature, for a crystal in solution it is shown that the "polar catastrophe" manifests as a diverging free energy cost to perturb the system from equilibrium. Going further than existing theories, the present formulation predicts that fluctuations in the adsorbed surface charge density become increasingly suppressed with increasing crystal thickness. We also show how, in the slab geometry often employed in both theoretical and computational studies of interfaces, an electric displacement field emerges as an electrostatic boundary condition, the origins of which are rooted in the slab geometry itself, rather than the use of periodic boundary conditions. This aspect of the work provides a firmer theoretical basis for the recent observation that standard "slab corrections" fail to correctly describe, even qualitatively, polar crystal surfaces in solution. [ABSTRACT FROM AUTHOR]

Ag2MoO4 crystals were prepared by a precipitation method by mixing parent solutions of silver nitrate and sodium molybdate. The effects of experimental parameters such as temperature, concentration, and pH were studied. The samples were found to be crystalline, pure, and monophasic in all cases, except in the case of very low pH. The precipitation leads to the formation of the cubic phase β and no secondary phase is present within the limits of detection of XRD and Raman spectroscopy. However, in some cases, at high temperature and high pH, silver oxide nanoparticles form on the surfaces of the crystals, which create a fluorescence background in the Raman spectra, which is otherwise absent. Analyses with the electron microscope have highlighted that the most common crystalline shape is octahedral, which is the most prevalent at low temperatures and pH around 7, but others are also possible, in particular at high temperatures. No growth occurs after precipitation, so crystals with different appearances form at the same time. [ABSTRACT FROM AUTHOR]

In this work, the modified attachment energy model was used to predict the crystal morphology of isosorbide mononitrate (ISMN) in the dichloromethane (CH2Cl2) solvent system and dichloromethane-n-hexane (CH2Cl2-C6H14) mixed solvent system. The solvent effect can significantly affect the crystal morphology, which can profoundly impact both the drug's physicochemical properties and the subsequent technological treatment process. In addition, the interactions between solvent molecules and crystal faces were investigated using molecular dynamics simulation, and radial distribution function (RDF) analysis was performed to determine the types of interactions. The structural parameter S was introduced to characterize the roughness of each crystal surface; the change in the CH2Cl2 diffusion coefficient before and after the addition of C6H14 was analyzed using mean square displacement (MSD). The calculation results of the modified attachment energy from the two solvent systems revealed that C6H14 could accelerate crystal growth, while the crystal morphology was not greatly affected, which is of some significance as a guide for the industrial crystallization process. [ABSTRACT FROM AUTHOR]

This paper summarizes an approach to crystal growth that was published in parts in various articles over the course of 25 years by the present author and his colleagues. Evidence for this approach, which is confirmed in detail by data in the cited publications and in the figures and equations in the supplementary material that accompanies this paper (see the Online Materials Deposit item AM-24-18851. Online Materials are free to all readers. Go online, via the table of contents or article view, and find the tab or link for supplemental materials.), comes mainly from the shapes of crystal size distributions (CSDs). Such distributions reveal the growth histories of natural minerals and synthetic compounds, histories that can be used to make geological interpretations and to guide industrial syntheses. CSDs have three fundamental shapes: log-normal, asymptotic, and Ostwald. These shapes result from different degrees of supersaturation near the time of nucleation. The first two distribution shapes form according to the Law of Proportionate Efect (LPE) at moderate supersaturation, and the latter rare distribution forms by Ostwald ripening at large supersaturation. Initially, the first two distributions have mean diameters of up to tens of nanometers and grow by surface-limited growth kinetics. The slow step in this reaction is the incorporation of nanoparticles (bits of crystal or adparticles) onto the crystal surface. As the crystals become larger, their demand for nutrients, as calculated by the LPE, increases exponentially. Then the slow step in the reaction changes to the rate of transfer of nutrients to the crystal (supply- or transport-limited growth). Crystal diameters often grow the most during this latter stage, and the initial CSD shapes that originally formed during surface-limited growth are retained and scaled up proportionately. Proportionate growth during the supply-limited stage can be simulated approximately by multiplying the diameter of each crystal in a distribution by a constant. Crystals can also grow by a constant rate law in which a constant length is added to each crystal diameter in the distribution. This rare process causes the original CSD to narrow so that its initial shape is not preserved. The growth law that prevails, either proportionate or constant, is determined by the manner in which nutrients are supplied to the crystal. Supply is by advective flow during proportionate growth, with the nutrient solution moving with respect to the crystals. Constant growth relies on the random difusion of nutrients through a quiescent solution. Proportionate growth is by far the most common growth law, and therefore, nutrient supply by difusion alone during crystal growth is uncommon. Distributions formed by Oswald ripening and those formed by other rare processes are also discussed. During Ostwald ripening, nucleation caused by mixing reactants at large supersaturation forms crystals that are extremely fine and numerous. The larger crystals grow at the expense of the finer, less stable crystals, thereby forming, on completion, the universal steady-state CSD shape predicted by the Lifshitz-Slyozov-Wagner (LSW) theory. This unique CSD shape, as well as other rare shapes, then are scaled up to larger sizes by supply limited proportionate growth. [ABSTRACT FROM AUTHOR]

Surface crystallization in fine powder Se70Te30 chalcogenide glass was studied by differential scanning calorimetry (DSC) and optical microscopy. A complex kinetic analysis of these experimental data reveals that the contracting sphere mechanism (R3 model) is the rate determining step of crystal growth, and the conventional Johnson–Mehl–Avrami–Kolmogorov model cannot be used in this case. Moreover, it is clearly shown that the particle size distribution should be considered in crystallization studies. Actually, when the particle size effect is taken into account, the simulated DSC curves for the R3 model agree very well with the experimental data over the entire temperature range. The crystallization kinetics determined from the nonisothermal DSC data are consistent with previously reported isothermal crystallization data for the same powder fraction. The crystal growth rate calculated from isothermal and nonisothermal DSC data agrees very well with the microscopically measured surface and bulk crystal growth rate. [ABSTRACT FROM AUTHOR]

The roughness of crystal surfaces and the shape of crystals play important roles in multiscale phenomena. For example, the roughness of the crystal surface affects the frictional and optical properties of materials such as ice or silica. Theoretical studies on crystal surfaces based on the symmetry principle proposed that the growing surfaces of crystal growth could be classified in the universal class of Kardar–Parisi–Zhang (KPZ), but experiments rarely observe KPZ properties. To fill this the gap, extensive numerical calculations of the crystal growth rates and the surface roughness (surface width) have been performed for a nanoscale lattice model using the Monte Carlo method. The results indicate that a (001) surface is smooth within the single nucleation growth region. In contrast, the same surface is atomically smooth but thermodynamically rough in the poly-nucleation growth region in conjunction with a KPZ roughness exponent. Inclined surfaces are known to become Berezinskii–Kosterlitz–Thouless (BKT) rough surfaces both at and near equilibrium. The two types of steps associated with the (001) and (111) terraces were found to induce KPZ surface roughness, while the interplay between steps and multilayered islands promoted BKT roughness. [ABSTRACT FROM AUTHOR]

Biominerals are inherently organic‐inorganic crystal composites. Drawing inspiration from this biomineral structure, functionalized single crystals can be synthesized using the gel‐grown method, resulting in the incorporation of gel‐networks into the host crystals. By incorporating gel‐networks, diverse guest materials, such as nanoparticles and dye molecules, can be uniformly and isotropically distributed within the crystals, thereby imparting non‐intrinsic optical or magnetic properties to the host crystals. Additionally, gel‐incorporation enhances the toughness and stability of the crystals as the incorporated gel‐fibers and accompanying guest materials act as bridges to prevent crack propagation. Furthermore, gel‐incorporation enables protein crystals to exhibit self‐healing properties, which can be attributed to the dynamic bonding interaction between gel‐networks and crystals. Notably, recent research has demonstrated that the incorporation of zwitterionic gel‐networks enhances the charge effects on crystal morphology evolution as the charged groups become bound to the developing crystal surfaces, and their detachment is impeded by the interconnected gel‐networks. Therefore, preparing single crystals with gel‐incorporation is a remarkable strategy for synthesizing functionalized crystal materials. [ABSTRACT FROM AUTHOR]

Crystal growth is often described as either interface-controlled or diffusion-controlled. Here, we study crystal growth in an intermediate scenario where reaction rates at the crystal-melt interface are similar to the rates of diffusive transport of ions through the melt to the advancing crystal surface. To this end, we experimentally investigated euhedral plagioclase crystal shapes in dry mafic (basaltic) and hydrous silicic (haplodacitic) melts. Aspect ratios and inferred relative growth rates of the 3D short (S) and intermediate (I) crystal dimensions vary significantly between mafic and silicic melts, with δS:δI  = 1:6–1:20 in basalt and 1:2.5–1:8 in hydrous haplodacite. The lower aspect ratios of plagioclase grown in the silicic melt coincide with 10 to 100× lower melt diffusion rates than in the mafic melt. Using an anisotropic growth model, we show that such differences in melt diffusivity can explain the discrepancy in plagioclase aspect ratios: if interface reaction and melt diffusion rates are of similar magnitude, then the growth of a crystal facet with high interfacial reaction rates may be limited by melt diffusion, while another facet of the same crystal with lower interfacial reaction rates may grow uninhibited by melt diffusivity. This selective control of melt diffusion on crystal growth rates results in progressively more equant crystal shapes as diffusivity decreases, consistent with our experimental observations. Importantly, crystals formed in this diffusion-moderated, intermediate growth regime may not show any classical diffusion-controlled growth features. The proposed model was developed for plagioclase microlites but should be generalisable to all anisotropic microlite growth in volcanic rocks. [ABSTRACT FROM AUTHOR]

This study is concerned with the question of what is the shape of a dendritic tip grown from an undercooled melt in the presence of external impacts? To answer this question we extend the recent theory (Alexandrov and Galenko in Philos Trans R Soc A 378:20190243, 2020) to the case of external processes influencing the crystal growth phenomenon. The tip shape function is derived and tested against experimental data and numerical simulations when forced convection and dissolved impurities play a decisive role. It is shown that the tip shape function taking external impacts into account is in good agreement with the theory, experiments and computations. Using our well tested formula for the dendrite tip shape we show that the mechanisms of heat and mass transfer in inclined fluid currents can be essentially different. Namely, heat and mass fluxes at the crystal surface can be described by Fick's or Newton's laws or even by a more general mixed-type heat and mass transfer formula. [ABSTRACT FROM AUTHOR]

During the growth of crystals in impure solution, impurities can pin the flow of the elementary steps and decrease the growth rate or even arrest the crystal growth. In this work, for the first time, we showed that curcumin crystals can grow in impure solution that contains two structurally similar impurities, following a non-classical crystallisation pathway that deviates from the pinning mechanism. We showed that, in a highly impure solution that contains 20 wt% of impurities, a high supersaturation can initiate the crystal growth via sympathetic nucleation that involves the formation of new growth surfaces on the seed crystals. These new surfaces formed on the seed crystals at the expense of higher supersaturation act like active growth surfaces and dictate the entire crystal growth kinetics especially at lower supersaturations. We showed that, if we can artificially create new surfaces that look like giant macrosteps at the micron scale on the crystal surface, then these macrosteps can not only speed-up the crystallisation rate but also control the rate of transfer of impurities into the bulk crystals. [ABSTRACT FROM AUTHOR]

How to effectively control the growth behavior of gypsum crystal in solution system has become one of the urgent problems to be solved in desulfurization industry, and the effective information of crystal growth process can' t be detected online timely and effectively. In this work, molecular dynamics simulation ( MS ) was used to calculate adhesion energy, face-center distance and area of specific plane of gypsum crystal, to determine morphologically dominant crystal planes and surface structure, and to theoretically study the interaction mechanism between sodium chloride and the main growth planes. The effect of sodium chloride on the crystal morphology of gypsum was obtained through experiments, which was compared with the results of MS. Results showed that sodium chlorides have varied effects on each crystal planes of gypsum crystals, which further changing the crystal morphology of gypsum. The simulation results are consistent with the experiment. MS can provide a theoretical support for morphology control of gypsum crystals. [ABSTRACT FROM AUTHOR]

Centimeter‐sized monoclinic BiVO4 (BVO) crystals are successfully grown by Bridgman method, and the physical and chemical properties of their exposed crystal surfaces have been studied. It is found that the atomic alignment and atomic density on different types of crystal facets of BiVO4 are different, which results in significant differences in its bandgap, charge lifetime, Raman scattering, and thermal diffusivity. Compared with other exposed crystal surfaces, the (010) oriented BiVO4 crystal has the lowest bandgap and the longest charge lifetime, with corresponding values of 2.26 eV and 11.44 ns, respectively. Besides, the (010) oriented BiVO4 crystal has a good thermal stability. This result indicates that the (010) oriented BiVO4 crystal has a wider optical absorption range, higher photogenerated charge mobility and stability, which is very important for understanding the influence of crystal orientation on electrode properties and the preparation of high‐efficiency photoelectrochemical photoanode. [ABSTRACT FROM AUTHOR]

Sheet‐like ZSM‐5 has been regarded as a promising material for catalytic applications due to its diffusion superiority. However, it still remains a challenge to obtain a desirable sheet‐like morphology because of the complex synthesis process of zeolites. Here, a facile strategy for synthesizing sheet‐like ZSM‐5 is developed by only adding ethanol as zeolite growth modifier in the synthesis gel. It is thought that ethanol might be preferentially absorbed on the {010} surface of zeolite crystals, interact with the exposed silicon hydroxyl groups on the crystal {010} facet, and suppress the growth of b axis, resulting in the sheet‐like shape. Through finely tunning synthesis parameters, sheet‐like ZSM‐5 crystals with thin b‐axis thickness of 90 nm and different aspect ratios could be obtained. Owing to its shorter diffusion path and optimized acidity, sheet‐like ZSM‐5 exhibits better catalytic performance than conventional ZSM‐5 in the alkylation of benzene with ethanol. [ABSTRACT FROM AUTHOR]

Organic single crystals with low defect density are key functional materials for next‐generation electronics. Classical crystallization commonly results in a high density of molecular steps, which are defects that can trap charge carriers and reduce the mobility of organic semiconductors. Herein, a novel nonclassical crystallization mechanism involving nucleation, fusion, and growth is designed. The introduction of the fusion stage changes the crystal growth mode from three‐dimensional island growth to two‐dimensional layer‐by‐layer growth and leads to large‐area two‐dimensional molecular crystals with almost no molecular steps. Therefore, the average mobility is observed to improve from 1.26 to 2.07 cm2 V−1 s−1. The nonclassical crystallization mechanism paves the way for atomically flat single crystals to probe the intrinsic optoelectronic properties of organic semiconductors. [ABSTRACT FROM AUTHOR]

To investigate the crystallization of DNTF in modified double-base propellants, glycidyl azide polymer (GAP) was used as the coating material for the in situ coating of DNTF, and the performance of the coating was investigated to inhibit the crystallization. The results show that GAP can form a white gel on the surface of DNTF crystals and has a good coating effect which can significantly reduce the impact sensitivity and friction sensitivity of DNTF. Molecular dynamics was used to construct a bilayer interface model of GAP and DNTF with different growth crystal surfaces, and Molecular dynamics calculations of the binding energy and mechanical properties of the composite system were carried out. The results showed that GAP could effectively improve the mechanical properties of DNTF. The values of K/G, γ and ν are higher than those of DNTF crystals, and the values of C12-C44 are positive, indicating that GAP can improve DNTF ductility while also improving toughness. Combining the experimental results with the simulation calculations, energetic binder GAP can be referred to as a better cladding layer for DNTF, which is feasible for inhibiting the DNTF crystallization problem in propellants. [ABSTRACT FROM AUTHOR]

As a wide bandgap semiconductor material, silicon carbide has promising prospects for application. However, its commercial production size is currently 6 inches, and the difficulty in preparing larger single crystals increases exponentially with size increasing. Large-size single crystal growth is faced with the enormous problem of radial growth conditions deteriorating. Based on simulation tools, the physical field of 8-inch crystal growth is modeled and studied. By introducing the design of the seed cavity, the radial temperature difference in the seed crystal surface is reduced by 88% from 93 K of a basic scheme to 11 K, and the thermal field conditions with uniform radial temperature and moderate temperature gradient are obtained. Meanwhile, the effects of different processing conditions and relative positions of key structures on the surface temperature and axial temperature gradients of the seed crystals are analyzed in terms of new thermal field design, including induction power, frequency, diameter and height of coils, the distance between raw materials and the seed crystal. Meanwhiles, better process conditions and relative positions under experimental conditions are obtained. Based on the optimized conditions, the thermal field verification under seedless conditions is carried out, discovering that the single crystal deposition rate is 90% of that of polycrystalline deposition under the experimental conditions. Meanwhile, an 8-inch polycrystalline with 9.6 mm uniform deposition was successfully obtained after 120 h crystal growth, whose convexity is reduced from 13 mm to 6.4 mm compared with the original scheme. The results indicate that the optimized conditions can be used for single-crystal growth. [ABSTRACT FROM AUTHOR]

For goethites synthesized at low (∼1–2) and high (∼13–14) extremes of pH, the values of 1000ln18α gt-w at ca. 25 °C are, respectively, +6.2 (±0.6) and + 0.9 (±0.6). Note that 18α gt-w = (18O/16O) gt /(18O/16O) w and gt = goethite (α-FeOOH); w = liquid water. A steady-state, flux-balance model indicates that this pH-related difference in values of 1000ln18α gt-w arises because of an effectively irreversible oxygen flux associated with aqueous Fe(III) hydroxide adsorption on, and incorporation in, goethite during growth at crystal surfaces. The model predicts that the transition from a low-pH to a high-pH value of 1000ln18α gt-w is relatively abrupt. At 22 to 25 °C, extant data indicate that the transition occurs in the interval of pH from about 6 to 8. Consequently, uncertainty about the pH of ancient waters could be a factor in interpretations of goethite δ 18O values. However, an experimentally determined equation for the temperature dependence of 1000ln18α (LpH) has been applied with apparent success to natural goethites that formed in the presence of meteoric waters (18α (LpH) = low-pH 18α gt-w). This suggests that those ancient waters may have been acidic (pH < 6) in the immediate environments of goethite crystallization. Published values of D/H fractionation between synthetic goethite and water (Dα gt-w) show no systematic effect of either pH or temperature (T) over a range of pH from 1 to 14 and a range of T from 22 °C to 62 °C. Within these ranges, the average value of Dα gt-w is 0.905 (±0.005) – a value which seems to characterize the D/H fractionation observed in natural goethites. If hydrogen in transitional, chemisorbed Fe(III) hydroxides – represented here as Fe(OH) 3 A – rapidly exchanges D/H with ambient water during crystal growth, there is a model-based expectation that Dα gt-w will not be affected by pH. This postulated D/H exchange would cease when Fe(OH) 3 A irreversibly transitions to FeOOH during crystallization – i.e., when Fe, O, and H are incorporated in the structure of the growing crystal. Thus, the flux balance model suggests that the observed dichotomy in the effects of pH on 18α gt-w and Dα gt-w is a result of distinctly different exchangeabilities of 18O/16O and D/H in transitional Fe(III) hydroxides that are chemisorbed on growing surfaces of goethite crystals. Observed values of 18α gt-w and Dα gt-w may represent steady-state – but not necessarily thermodynamic equilibrium – distributions of isotopes between H 2 O and the oxygen or hydrogen in the interiors of crystallizing goethites. Nevertheless, these steady-state values of Dα gt-w and 18α gt-w are generally reproducible and systematically relate δ 18O and δ D values of goethite to environmental variables. [ABSTRACT FROM AUTHOR]

The single crystal of hydroxyethylammonium D‐tartrate monohydrate (HEDT) is grown along the (1 1 0) plane using the Sankaranarayanan–Ramasamy method. The powder X‐ray diffraction and the high‐resolution X‐ray diffraction analyses are used to corroborate the growth plane and perfection of the crystallinity, respectively. The birefringence experiment has proven crystalline homogeneity and estimated birefringence value (Δn) is 0.109. The surface morphology of the grown crystal is examined by chemical etching analysis and irregular hillock patterns are found. The transmittance for the (1 1 0) plane of the HEDT is inspected by a UV‐Vis analysis. The second harmonic generation efficiency of the HEDT crystal is 1.7 times that of potassium dihydrogen phosphate (KDP). The third‐order nonlinear optical (TONLO) properties of the grown HEDT crystal are scrutinized by the Z‐scan experiment. The estimated TONLO susceptibility of HEDT crystal is 6.827 × 10−8 esu. The laser damage threshold value of HEDT is discovered to be 5.24 GW cm−2. The 3D Hirshfeld surface visualizes the interaction between HEDT molecules and analyzes the distance from the surface of the molecule to the farthest and the nearest atom. The important contributions of crystal packing are explored by 2D‐fingerprint plots. [ABSTRACT FROM AUTHOR]

In the last 100 years, the study of polymer crystallization theory has achieved many breakthroughs, and a large number of models and theories have been proposed. However, each of them can only partially explain the crystallization behavior of polymers. A uniform understanding of polymer crystallization remains a huge challenge. In this paper, we try to understand the crystallization of polymers from the motion of polymer chains, and a universal model, the diffusion and conformational transition (DCT) model, is proposed. The DCT model can provide a unified understanding of the current polymer crystallization models. We propose that the nature of polymer crystallization is the synergy and competition between the diffusion (D) and the conformational transition (CT) processes. Moreover, by dividing the types of D and CT into D 1 to D 3 and CT 1 to CT 6 , respectively, the homogeneous nucleation process and the growth of polymer crystals on the surface of an existing crystal are discussed. Some important results on the number of stems for critical nuclei, the type of nucleation, the origin of the conformation of chain segments on the end surface of lamellar crystals, etc. have been achieved. These results not only provide a good explanation of the experimental findings in the literature, but also contain some new findings. The DCT model may further be used to resolve disputes, explain and predict new phenomena, and teach beginners in polymer crystallization in the future. [Display omitted] • A universal polymer crystallization model is proposed. • The nature of polymer crystallization is the synergy and competition between the D and the CT processes. • Intermolecular nucleation is easier for small nuclei and intramolecular nucleation is easier for larger nuclei. • The number of stems for critical primary and secondary nuclei is independent of the type of nuclei. • The competition between CT 4 /CT 5 and D 3 results in tightly folded-chains, loops, cilia, and tie chains. [ABSTRACT FROM AUTHOR]

[Display omitted] • The rapid synthesis was achieved by adding H 2 O 2 and seeds; • 0·.4H 2 O 2 + 20 %-2d had excellent NH 3 -SCR performance; • H 2 O 2 could facilitate the Si-O-Si bond formation; • Seeds provided the surface of growth and accelerated the crystallization process. The ZK-5 zeolite was synthesized using an eco-friendly and rapid method by incorporating H 2 O 2 and seeds, omitting the traditional organic template. And the rapidly synthesized Cu-ZK-5 catalyst exhibit excellent NH 3 -SCR performance and hydrothermal stability. The synthesis mechanism is hypothesized to result from the synergistic effects of the seeds and H 2 O 2. The seeds inclusion could avoid non-uniform nucleation during the synthesis process and promote the crystal growth and crystallization process by providing a surface for crystal growth. The innovative addition of H 2 O 2 facilitated the formation of Si-O-Si bonds, thereby accelerating the zeolite crystallization process initiated by the seeds, which resulted in a more rapid incorporation of Si into the zeolite framework. Furthermore, characterization results indicated that the rapidly synthesized samples were rich in acidic sites and active Cu2+ species, with excellent NO adsorption capacity. These features likely contributed to the enhanced NH 3 -SCR performance and hydrothermal stability. [ABSTRACT FROM AUTHOR]

• A quadratic power-law growth model is employed in simulations of KDP growth. • Rotation and temperature effects were investigated. • The pyramidal surface supersaturation responds more sensitively to temperature. • The strategies for optimizing growth parameters are proposed. Numerical simulations of the turbulent hydrodynamics and concentration in the rapid growth of potassium dihydrogen phosphate (KH 2 PO 4 or KDP) crystals have been performed. In this work, a quadratic power-law growth model is applied, concerning the mass transfer occurring at the crystal surface during the growth process under low supersaturations. The mass transfer boundary condition is discretized by using the Over-Relaxed approach. The effects of the growth temperature and rotation rate on surface supersaturation distribution and the diffusion layer are investigated, which are critically involved in the processes of surface morphological instability and inclusion formation. Due to the kinetic limitation, the response of different types of crystal surfaces to temperature varies, with a pyramidal surface about twice as high as a prismatic face. In addition, the contour map of the growth rate combined with the coefficient of variation (C. V) for various temperatures and rotation rates is used. Uniformity of surface supersaturation is provided by lowering the growth temperature and increasing the rotation rate. Furthermore, the criteria of crystal growth strategies are proposed to optimize the process parameters and obtain favorable conditions for crystal growth, thereby facilitating defect-free and high-quality crystal formation at an appropriate growth rate. [ABSTRACT FROM AUTHOR]

Recently, one of the uranium-based heavy fermion systems, UTe2, has attracted enormous attention because of its potential spin triplet superconductivity, whose superconducting properties are closely related to their compositions and states of crystallization. In this work, the crystal growth of UTe2 crystals was systematically studied by the CVT method. Various growth parameters, including growth temperature, the ratio of uranium to tellurium, and the type and amount of transport agents, were investigated. A lower growth temperature (710 °C) results in a smaller size of the UTe2 crystals, and too high of a growth temperature (1060 °C) makes the nucleation rate go out of control. The ingredients with higher tellurium content (U : Te = 2 : 5) lead to larger single crystals, while a shortage of tellurium (U : Te = 2 : 3) tends to form polycrystals with smaller sizes. Among the three types of transport agents we used, iodine forms larger crystal sizes than AgBr and TeBr4. When the amount of iodine is excess (2.45 mg cm−3), the crystal surface becomes rough, while not enough iodine makes the crystal thin and even bent. We have found that centimetre-sized high quality UTe2 single crystals can be grown by using an appropriate amount of iodine as the transport agent at 860 °C. The nucleation rate of UTe2 crystals is mainly determined by temperature and iodine partial pressure, while the growth rate is more sensitive to the tellurium partial pressure. The oxidation process of UTe2 crystals was observed and is also discussed in this paper. [ABSTRACT FROM AUTHOR]

We propose a cubic B-spline finite element method to solve the optimal control problem governed by nonlinear parabolic equation depicting crystal surface growth. Considering that both the state equation and the adjoint equation are fourth-order nonlinear parabolic equations, we select the cubic B-spline functions as shape functions. We establish a fully-discrete scheme of the optimality system and use an iterative method to solve it. In the end, a numerical example is demonstrated for the purpose of verifying the feasibility and effectivity of the suggested method. [ABSTRACT FROM AUTHOR]

The narrow bandgap (≈1.2 eV) Pb‐Sn alloyed perovskite solar cell is a promising bottom component cell for all‐perovskite tandem devices that are expected to offer higher efficiency than the theoretical Shockley–Queisser limit of the single‐junction solar cells. The density functional theory (DFT) study reveals that the Pb‐Sn perovskite film with the (100) orientation would render significantly reduced trap density, which is a critical figure‐of‐merit for perovskite device performance. Alkyl diamine is therefore designed to first anchor onto the surface as a nucleation agent to modulate the Pb‐Sn perovskite growth to proceed preferentially along with the (100) orientation. It is observed that the diamine cations not only effectively induced the crystal growth at the nucleation stage, but also remained on the crystal surface to eventually passivate the resultant perovskite film. As a result, the diamine‐based films show (100) preferred orientation with superior optoelectronic properties, as predicted by the DFT investigation. Consequently, the champion power conversion efficiency of 20.03% is achieved, one of the highest for this type of device. These findings provide a practicable strategy to theoretically design surface nucleation to induce preferential growth of perovskite material for better optoelectronic performance. [ABSTRACT FROM AUTHOR]

Through adjusting the pH of the silver ammonia solution (Ag(NH3)2OH), different microstructure of silver phosphate (Ag3PO4) was prepared via simple precipitation method. The effect of pH on the microstructure and photocatalytic properties was studied. Preliminary results indicate that the pH of silver ammonia solution played a key role in crystal growth and microstructure of Ag3PO4. When the pH is 9, the preferential crystal growth of the Ag3PO4 oriented along the (1 1 0) crystal surface. Thus, the cubic Ag3PO4 shows excellent photocatalytic properties. Based on the Ostwald's ripening rule, a possible formation mechanism of cubic Ag3PO4 was proposed. Controlling the microstructure of Ag3PO4 through pH-control of the silver ammonia solution. When the pH of the silver ammonia solution is 9, the preferential crystal growth of the Ag3PO4 oriented along the (1 1 0) crystal surface. Based on the Ostwald's ripening rule, a possible formation mechanism of cubic Ag3PO4 was proposed. [ABSTRACT FROM AUTHOR]

In this work, we study the effect of increasing temperature on the structure parameters (lattice, sulfur–sulfur distance, and ruthenium–sulfur distance) and the energy gap of RuS2. However, it was very challenging to obtain a sample of RuS2 due to many factors, some of which are discussed in the introduction. To prepare the crystal growth of RuS2, we have used the chemical vapor transport technique. The crystals obtained show a pyrite structure, of which we studied its crystallographic structure, including the structure of crystals in surface (100). The sample was then characterized by X-ray diffraction and by microprobe analysis. We determine the relationship between the energy gap and the sulfur–sulfur distance. We analyzed the S-S bond compared with the S2 molecule. [ABSTRACT FROM AUTHOR]

In this paper, the growth rates of spherical and ellipsoidal crystals evolving in metastable melts and solutions are derived. Different scenarios and aspects of crystal growth (steady-state, unsteady-state, the phase transition temperature shift due to the curvature of the crystal surface and the kinetics of attaching atoms to it) are considered. The derived crystal growth laws under various process conditions are generalized and compared to experimental data. [ABSTRACT FROM AUTHOR]

2D hybrid halide‐layered perovskites have been compelling candidates for photovoltaics and optoelectronics owing to their remarkable electrical and optical properties. However, high‐quality crystals are usually obtained either through complicated and energy‐consuming procedures or using toxic solvents, which remains a significant challenge to the crystal synthesis. To address the issue, a facile, universal, ecofriendly, and energy‐saving approach to synthesize the Ruddlesden−Popper‐ and Dion−Jacobson‐phase 2D‐layered potassium‐passivated perovskites at room temperature is reported. By involving potassium iodide to the reaction, potassium ions can assist both the crystal growth and surface passivation, improving their stability and passivated trap states. Potassium‐passivated (R‐MBA)2PbI4 exhibits superior optoelectronic features than pristine (R‐MBA)2PbI4 as well as outstanding strain stability. The findings herein may not only improve synthetic methods to obtain high‐quality crystals, but also motivate more fundamental investigations for potential optoelectronic and flexible applications. [ABSTRACT FROM AUTHOR]

In the crystal growth of Na–Si clathrate (type I, Na8Si46) during Na evaporation from a Na–Si–Sn solution at 723 K, the composition of a Na–Sn flux in the starting material strongly influences the morphology and size of the formed clathrate crystals. In this study, the crystals obtained using this flux were larger than the crystals prepared without a flux, and some of them had faceted surfaces. At the Na4Si4 (precursor):4Na–Sn (flux) = 1:4 ratio, multiple dents were observed on crystal surfaces, indicating that the precipitation of a Na9Sn4 solid phase prevented the growth of Na–Si clathrate crystals. In addition, synthesis conditions, under which type I crystals could be obtained by conventional thermal decomposition in vacuum, were established. The results of this work suggest that type I Na–Si clathrate crystals are stable even at temperatures as high as 723 K due to the suppressed evaporation of Na. [ABSTRACT FROM AUTHOR]

Impurities are frequently encountered during the crystallisation of active pharmaceutical compounds. Impurities can either adsorb onto active sites or replace atoms of the crystal lattice. Locating the impurities, especially structurally-similar impurities, on the crystal surface is challenging. In this work, we showed that time-of-flight secondary ion mass spectrometry (TOF-SIMS) can be successfully used to simultaneously quantify the composition of the two structurally-similar impurities, demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC), on the surface of the curcumin (CUR) crystals obtained from crystal growth and cooling crystallisation experiments. The distribution of the three curcuminoids on the crystal surface was evaluated through imaging of the specific ions that correspond to intact molecules of the curcuminoids. In terms of location, both BDMC and DMC were evenly distributed on the surfaces of the facets of the curcumin crystals. Additionally, we found that BDMC and DMC occupy their own sites or they are located on the same site on the crystal surface providing evidence for lattice replacement of these molecules. Thus our results demonstrate the potential of TOF-SIMS to provide new information that can help to understand crystallisation. [ABSTRACT FROM AUTHOR]

• Modulation of crystal surface growth. • Enhancing the active phase of MoS 2 and the ratio of S vacancy. • Alkaline earth metal-doped MoS 2 -based materials as selective adsorbents. • Sr-MoS 2 with a high partition coefficient K d of Pb2+ (31.34 L g - 1 ). It was a challenge to prepare an adsorbent with excellent selectivity for target heavy metals, especially when treating real wastewater contaminated with various heavy metals. In the present study, MoS 2 with a specific binding capacity for Pb, was selected as the substrate material. And alkaline earth metal doped SM(Sr-MoS 2) adsorbent was synthesized via a simple one-step hydrothermal method. The morphology and structure of SM were characterized and the results confirmed that Sr was successfully anchored to MoS 2. In addition, it indicated that Sr played a role in expanding the MoS 2 spacing, increasing the ratio of 1 T phrases, and modifying the crystal growth (such as the growth direction and growth rate). Therefore, it suggested that SM had a high selectivity factor (171.26) and partition coefficient K d (31.34 L g - 1 ). More importantly, SM maintained good adsorption performance (∼90 % removal) after six adsorption–desorption cycles, using NaOH or Na 2 -EDTA as desorbent. Therefore, this work provided a new idea for the preparation of selective adsorbents based on MoS 2 , which was expected to be used for the remediation of Pb2+-contaminated wastewater. [ABSTRACT FROM AUTHOR]

• Frost crystal growth process on single frozen droplet is divided into three stages. • The longitudinal and radial frost crystal growth characteristics are quantified. • Droplet size notably impacts the frost crystal collapse and distribution patterns. • The number of frost crystal collapses per arc length increases with the droplet size. The frosting phenomenon poses a potential threat to both industrial production and daily life. Typically, a frost layer consists of frost crystals that grow on various micro-sized frozen droplets, and its development is significantly affected by the frost crystal behaviors. To better understand the frosting mechanism, a series of experiments are conducted to investigate the growth characteristics of frost crystals on single frozen droplets with sizes from 1.83 to 0.02 μL. The results show that the whole growth process of frost crystals on a frozen droplet can be categorized into three stages: crystal rapid growth, crystal growth and collapse, and crystal growth fully stages. As the droplet size decreases, the durations of the crystal rapid growth stage and the crystal growth and collapse stage exhibit an upward fluctuation. The maximum height of frost crystals increases with droplet size, while the net crystal height does not follow this trend. Specifically, the maximum net crystal heights on frozen droplets of 1.83, 0.97, 0.43, 0.05, and 0.02 μL at 1,800 s are 1.681, 1.386, 1.476, 1.134 and 1.355 mm, respectively. The growth rate of the highest crystal in the case of 1.83 μL shows a downward trend over time due to the consistently increased crystal surface temperature. Conversely, the growth rates in the cases of 0.97, 0.43, 0.05, and 0.02 μL initially increase and then decrease over time due to the combined effect of crystal surface temperature and water vapor competition. Both the total number of crystal collapses and the number per unit arc length increase with an increase in droplet size. The study contributes to developing accurate frost prediction models and offers insights for optimizing the defrosting control strategy of air source heat pumps or refrigerators. [ABSTRACT FROM AUTHOR]

• The magnesium hydroxide thin films have the characteristic of regeneration. • More oriented and scalable in hydrothermal environments. • The conversion of hexagonal wafers expansion into crystal films were achieved. • Correlation between growth units and the addition of TEA for the selective growth of crystal planes was found. Thin film crystal materials have excellent properties such as a fine-scale structure, high strain strength, and flame retardancy. In this work, the preparation of magnesium hydroxide thin films was achieved by analyzing the main exposed groups on the surface of magnesium hydroxide and utilizing self-assembly film technology in a hydrothermal system with triethanolamine as a crystal additive. By combining experimental and simulation calculations, the study explored the alterations in morphology and growth mode of magnesium hydroxide thin films, the adsorption of triethanolamine on different crystal surfaces of magnesium hydroxide, and the control of magnesium hydroxide crystal growth by dynamically adjusting growth unit diffusion in the system under the influence of triethanolamine concentration. The results showed that the addition of triethanolamine increased the concentration of OH– ions in the solution, facilitating the adsorption of Mg(OH) 6 4− growth units on the (1 0 1) surface with more Mg-O bonds. This allows the magnesium hydroxide (1 0 1) crystal surface to serve as tangential growth drivers for the system, the normal growth of the crystal surface transitions to tangential extension, promoting the gradual expansion of the hexagonal wafer into crystal films. The regrowth mechanism of magnesium hydroxide thin films promotes the regrowth of crystals under hydrothermal conditions, and realizes the high value-added utilization of magnesite resources. [ABSTRACT FROM AUTHOR]

Uniform nitrogen doping in SiC crystals is crucial for high-yield production of SiC power devices. This paper tries to provide clues to implementing uniformly nitrogen-doped 4H–SiC crystals by considering the nitrogen doping kinetics during physical vapor transport (PVT) growth of 4H–SiC crystals. We measured the doping uniformity in PVT-grown 4H–SiC crystal using Raman scattering microscopy, finding that the doping uniformity improved as the nitrogen doping concentration increased. Using data from doping variations in PVT-grown SiC crystals, we deduced the step-flow velocity dependence of nitrogen incorporation at the growth front of three variable nitrogen-doped (mid-1017 to more than 1019 cm−3) PVT-grown 4H–SiC crystals, where the step-flow velocity was estimated from the local inclination angle of the growth front surface from the (000 1 ¯) plane. The results were analyzed using the two-site exchange model for surface segregation of impurity atoms on the growing crystal surface. The model reproduced the experimental results of nitrogen incorporation well. This analysis provides two critical physical parameters for the surface segregation of nitrogen on growing 4H–SiC crystal surfaces: the Gibbs energy and kinetic barrier height for surface segregation, which were extracted from the experimental data. The Gibbs energy and the kinetic barrier height for surface segregation of nitrogen atoms decreased for greater nitrogen doping concentrations. These results are discussed with the improved mechanism of nitrogen doping uniformity in 4H–SiC crystals at greater nitrogen doping concentrations. [ABSTRACT FROM AUTHOR]

• The emission wavelength of the CsCu 2 Br 3 single crystal is at 580 nm only. • CsCu 2 Br 3 single crystals treated by Isopropanol leads to precipitation of CuBr. • The 460 nm emission origins from CuBr rather than CsCu 2 Br 3. Lead-free low-dimensional perovskites have attracted much attention due to their advantages of high Photoluminescence quantum yield (PLQY) and visible light emission. In this paper, a new one-dimensional CsCu 2 Br 3 single crystal has been prepared successfully, and the differences in the optical properties influenced by surface cleaning treatments were investigated. The CsCu 2 Br 3 single crystal without surface damage can be obtained by the N 2 purging process without any solution rinsing. The photoluminescence peak of the pure CsCu 2 Br 3 phase is located at 580 nm, arising from the self-trapped exciton with the binding energy of about 173 meV. After the treatment of the isopropanol rinsing, the CuBr phase was formed on the surface of the as-grown CsCu 2 Br 3 single crystal. The stronger photoluminescence intensity can be directly observed by the naked eye, which was dominated by the CuBr phase with the emission peak at 460 nm. The above results show the importance of surface treatment and can explain the misunderstanding of the PL mechanism attributed to the dual self-trapped excitons. [ABSTRACT FROM AUTHOR]

• The mechanism of the influence of dextran on trehalose crystal morphology was revealed through experiments and MD simulation. • The bulk trehalose crystals have excellent powder properties. • The Bulk trehalose products have better mixing uniformity and more stable starch protection. The residual dextran impurities in the upstream process significantly impact the crystallization of starch-based functional sugar and the related food properties. This study intends to reveal the mechanism of dextran's influence on trehalose crystallization, and build a relationship among the dextran in syrup and the physicochemical and functional properties of trehalose. Instead of incorporating into the crystal lattice, dextran changes the assembly rate of trehalose molecules on crystal surface. The different sensitivity and adsorption capacity of the crystal surface to the chain length of dextran determines the growth rate of crystal surfaces, resulting in different crystal morphology. The bulk trehalose crystals, which were obtained from syrups with short chain dextran, have excellent powder properties, including best flowability (35◦), highest crystal strength (2.7 N), lowest caking rate (62.22 %), and the most uniform mixing with other sweeteners (sucrose/xylitol) in food formulations, achieving more stable starch preservation. [ABSTRACT FROM AUTHOR]

Scaling has been a major technical challenge in the membrane distillation (MD) process, hindering the broader application of MD processes. Despite the increasing number of studies on MD scaling, there are limited prediction tools to describe the scaling process and help make informed decisions about the experimental conditions to prevent scaling and its irreversible damage. In this paper, a semi-analytical model was developed based on the classical nucleation theory and crystal growth to model the membrane area reduction caused by the deposition of inorganic salt crystals on the membrane surface, which is equivalent to the decrease in permeate flux resulting from scaling. The model was developed using calcium sulphate, a model scalant. The model was validated and verified with available literature data, and it has been proved that the model has the capability to produce reasonable predictions on the onset of flux decline and the declining rate with respect to the experimental data with the coefficient of determination (R2) ranging from 0.74 to 0.96. The sensitivity analysis was applied on the model, which revealed that flux decline would happen earlier in the case of higher feed temperature, higher feed velocity, and higher initial feed concentration. • A semi-analytical was developed for gypsum scaling prediction in DCMD. • Nucleation and crystal growth kinetics were used for the model development. • Model gave good prediction for flux decline compared to experimental data. • Higher feed temperature, feed velocity and feed concentration advance scaling. [ABSTRACT FROM AUTHOR]