Crystal Shape Research Articles

Distinctive Photomechanical Shape Change of p‐Phenylenediacrylic Acid Dimethyl Ester Single Crystals Induced by a Spatially Heterogeneous Photoreaction

AbstractUnderstanding photoreaction dynamics in crystals is important for predicting the dynamic property changes accompanying these photoreactions. In this work, we investigate the photoreaction dynamics of p‐phenylenediacrylic acid dimethyl ester (p‐PDAMe) in single crystals that show reaction front propagation, in which the photoreaction proceeds heterogeneously from the edge to the center of the crystal. Moreover, we find that p‐PDAMe single crystals exhibit a distinctive crystal shape change from a parallelogram to a distorted shape resembling a fluttering flag, then to a rectangle as the photoreaction proceeds. Density functional theory calculations predict the crystal structure after the photoreaction, providing a reasonable explanation of the distinctive crystal shape change that results from the spatially heterogeneous photoreaction. These results prove that the spatially heterogeneous photoreaction dynamics have the ability to induce novel crystal shape changes beyond what would be expected based on the equilibrium reactant and product crystal shapes.

Distinctive Photomechanical Shape Change of p-Phenylenediacrylic Acid Dimethyl Ester Single Crystals Induced by a Spatially Heterogeneous Photoreaction.

Understanding photoreaction dynamics in crystals is important for predicting the dynamic property changes accompanying these photoreactions. In this work, we investigate the photoreaction dynamics of p-phenylenediacrylic acid dimethyl ester (p-PDAMe) in single crystals that show reaction front propagation, in which the photoreaction proceeds heterogeneously from the edge to the center of the crystal. Moreover, we find that p-PDAMe single crystals exhibit a distinctive crystal shape change from a parallelogram to a distorted shape resembling a fluttering flag, then to a rectangle as the photoreaction proceeds. Density functional theory calculations predict the crystal structure after the photoreaction, providing a reasonable explanation of the distinctive crystal shape change that results from the spatially heterogeneous photoreaction. These results prove that the spatially heterogeneous photoreaction dynamics have the ability to induce novel crystal shape changes beyond what would be expected based on the equilibrium reactant and product crystal shapes.

Advanced PPS/MOFs composite nanofiltration membranes derived from contra-diffusion synthesis for precise molecular separation

To meet the separation requirements of polyphenylene sulfide (PPS) membranes in extremely harsh environments and to enhance the separation performance of PPS membrane material, this study utilizes Zeolitic imidazolate framework (ZIF) material with a porous structure to modify the structure of the PPS membranes. Using the Contra-diffusion synthesis method, we successfully created PPS composite membranes that were modified by ZIF-8. At the end of the three-hour reaction time, a continuous and dense layer of ZIF-8 crystals with uniform crystal size and regular crystal shape was produced on the matrix membrane's surface. The permeance to rhodamine B aqueous solution is 42.54 L m−2 h−1 bar−1, and the retention rate is 99.5 %, which has high permeability and retention performance. In the anti-pollution performance test, the composite membrane's flux recovery rate is 72.9 %, which has good anti-pollution performance. After immersion in strong acids, strong alkalis, and a variety of organic solvents, the appearance shows no evident flaws, and the separation performance in strong alkalis and five different types of organic solvents stays steady, demonstrating excellent alkali and solvent resistance. This proves that composite membranes have great potential for application in dye wastewater treatment.

Amino Acid-Assisted Synthesis of Zeolites with Improved Catalytic Properties.

Conventional zeolites are limited in their ability to catalyze macromolecular reactions due to micropore constraints, resulting in sluggish reactant and product diffusion and subsequently pore clogging and catalyst deactivation. Consequently, the pore and textural refinement of zeolites to meet industrial demands has become a research hotspot. Herein, we review the amino acid-assisted methods in zeolite synthesis and scrutinize the principle and influential factors governing amino acid involvement in zeolite synthesis. Additionally, we analyze the advantages and challenges associated with the amino acid-assisted method. Certain amino acids can interact with zeolite precursors or crystal surface, thus altering the crystal growth rate and enabling precise control over the crystal size and shape. On the other hand, amino acids can serve as structure-directing agents to orchestrate the generation of mesoporous pores. These capabilities enable the production of zeolites with well-defined pores, particle sizes and/or crystal shapes that satisfy catalytic requirements. Moreover, the unique properties of amino acids allow their complete elimination from the solid product through a simple aqueous washing process, facilitating their recovery for subsequent usage. As result, the amino acid-assisted synthesis methods offer a convenient, green route to zeolites with modulated textual properties for high-performance catalysis.

Insights into the K–Pg extinction aftermath: The Danish Cerithium Limestone Member

The Cretaceous–Palaeogene (K–Pg) mass extinction about 66 Ma ago was one of Earth's largest mass extinction events. The demise of calcifiers, among others, influenced biogeochemical cycles and changed the conditions for carbonate deposition in the global ocean. This study addresses the sedimentology and carbonate microfacies of the Cerithium Limestone Member of the Rødvig Formation within the renowned Stevns Klint succession in Denmark. The limestone was deposited in the earliest Danian Stage, immediately after the K–Pg mass extinction. It is a pale yellow, partly cemented unit with a dense network of Thalassinoides burrows and numerous flint nodules. Studies of the thin sections revealed that the Cerithium Limestone Member is more variable than expected from its overall homogeneous appearance at the macroscopic scale. The thin sections and scanning electron microscope (SEM) images showed that the highly bioturbated limestone consists of four principal microfacies: a mudstone, a wackestone and two different packstones. The 30 to 120-cm thick Cerithium Limestone Member fills depressions between low-amplitude mounds in the Maastrichtian chalk. The lowermost part constitutes a thin layer of a bryozoan-rich packstone, probably reworked from the crests of the Maastrichtian mounds. The successive part of the member is dominated by wacke stone with mainly foraminifera (planktic and benthic), molluscs and echinoderm debris, and in some areas an abundance of peloids. The foraminifera- and mollusc rich packstone appears in lenses. The mudstone contains few foraminifera and is linked to burrows and syn-sedimentary fractures. SEM observations revealed that the Cerithium Limestone Member corresponds to a dispersed micrite, with small calcite crystals ~1–4 µm in size. The general shape of these calcite crystals suggests precipitation from cyanobacterial activity and, thus, a microbial genesis for the micrite of the Cerithium Limestone Member.

Enhancement of KCl flotation through crystallization regulation during carnallite decomposition

Particle size and surface morphology have a substantial influence on flotation. Conventional grinding methods usually destroy the surface morphology while controlling the particle size. In this work, we propose a new strategy to control particle size and morphology through crystalizing regulation instead of grinding to protect the crystal face in the flotation process. Scanning electron microscopy results illustrate that the surface morphology of crystallization-regulated particles is better protected than grinding-regulated particles. The superior flotation effect of the crystallization-regulated products was validated by micro-flotation tests. The mechanism of enhanced flotation by crystalline modulation was further analyzed with the help of induction time, adhesion-desorption force, collector adsorption, and theoretical calculations, which showed that the crystallization-regulated products were more hydrophobic and had more stable adherence to the flotation bubbles. The innovative method of crystalline modulation developed in this work to improve the flotation effect provides a novel way to protect the crystal shape for the efficient flotation of potash salts, which is of great significance for the reduction of cost and increase of efficiency in the flotation process of potash salts.

Application of confocal laser scanning microscopy to investigation of micro crystals in transparent amorphous media: Photoluminescence tomography and spectroscopy of CdZnSSe crystallites in historical silicate glass

Recently, photoluminescence tomography based on the confocal laser scanning microscopy with two-photon excitation has been developed to study the distribution of point and extended defects in the bulk of ZnSe laser crystals. This article presents the use of the tomography to investigate luminescent micro inclusions in transparent amorphous media such as silicate glass. Studies of CdZnSSe crystals synthesized in a silicate glass melt have been carried out using the tomography with both two-photon and single-photon excitation of luminescence. Zn-rich glass manufactured in the 19th century has been found to contain micron-sized crystals of CdξZn1−ξSζSe1−ζ (ξ≈0.5, ζ≈0.5) of hexagonal crystal system exhibiting intense photoluminescence. The photoluminescence band of these crystals has been found to peak at about 2.1 eV (∼590nm) at 300 K. Minor shifts in the maximum of bands and changes in their shape in individual crystals or at tomogram points within the crystal are associated with variations in their composition. Changes in the photoluminescence band shape and maximum due to the excitation of luminescence in CdZnSSe crystallites by laser radiation of different energies have also been observed in this study.

Preparation and Growth Mechanism of Pyramid‐Shaped Cu2ZnSnS4 Monocrystal and the Simulation of Its Monograin Layer Solar Cells

AbstractThe Cu2ZnSnS4(CZTS) monocrystal as an important component of the optical absorption layer in monograin layer solar cells, has excellent crystallization characteristics and adjustable photogenerated carrier concentration. The shape of the CZTS monocrystal directly affects the utilization of incident light and the contact area during the preparation of the back electrode when they are densely packed to form a single‐layer absorption layer. Herein, a kesterite‐phase pyramid‐shaped CZTS monocrystal prepared by the molten salt method is reported, which can improve the efficiency of incident light utilization and increase the contact area during back electrode preparation. The X‐Ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy are used to characterize the crystallinity and crystal shape of pyramid‐shaped CZTS monocrystal. Besides, Finite‐Difference simulation calculation is employed to reveal the optical response and corresponding monograin layer solar cells performance of densely packed CZTS. The results show that the pyramid‐shaped structure exhibited excellent incident light trapping ability, and the simulated device achieves a cell efficiency with above 13.6% after parameter optimization. The work provides a method for preparing pyramid‐shaped CZTS monocrystal, and a new strategy to further improve the efficiency of CZTS‐based monograin layer solar cells.

Prediction of the sound transmission loss of shape-varied sonic crystals: A transfer matrix approach.

This paper proposes a transfer matrix method (TMM) for modeling sonic crystals to predict the transmission loss of noise exiting an air extraction system. Because the crystals may be of different shapes (e.g., square, circular, or standardized airfoil profile to minimize airflow resistance) and must account for thermo-viscous losses, a discrete version of the TMM is used. Similar to the finite element method, a discretization of the geometry is first performed. Each element is modeled with a transfer matrix (TM) that includes the local thermo-viscous losses which attenuate the sound wave. For each element in parallel, the parallel TMM is employed. For the subsequently created elements in series, the classic TMM is used. This generates a global TM from which the sound transmission loss of the crystal network is deduced. The predictions obtained by the proposed method are compared to measurements in an acoustic tube for three different shapes of sonic crystals. The results show that a geometric tortuosity correction is necessary for the predicted bandgap center frequency to match the measurement. A correction is proposed, but this requires a possible refinement for more complicated profiles.

Physical Properties of HfO2 Nano Structures Deposited using PLD

On Quartz substrates, high purity transparent conductive the Di-Oxide of the (HfO2) Nano and micro-structure films were successfully coated. The method of (PLD) Deposition using Pulsed Laser, and the influence of laser energy was investigated. The XRD results revealed two distinct phases, cubic and monoclinic crystal shapes. Peaks in the Fourier-transform infrared (FTIR) spectra showed that HfO2 nanofilm was forming.The findings of the optical characteristics reveal an excellent transparency of nearly 80% (89 percent). As the laser wavelength decreases, the optical energy band gap values for Nanostructure of HfO2 were prepared, with values ranging from 5.24 to 5.53 eV. Also, the EDX results showed the appearance of hafnium peaks and oxygen peaks in varying proportions, which confirms that hafnium oxide is definitely obtained The results of the AFM reveal that when the pulsed laser intensity increases, the average grain diameter values increase from 52.96 to 74.54 nm. With regard to optimum pulsed laser energy, the based on I-V characterization, the generated factor ideality for created diodes was discovered to be decreasing, and the corresponding values of the barrier height grew. The ideality factor of the diode made the optimum pulsed laser energy (1800 mJ) was greater (n=3.1).

Growth strategies for widening thick heavily boron-doped (113)-oriented CVD diamond

In the present study, a growth strategy allowing widening thick heavily boron doped (113)-oriented diamonds is proposed. It relies on a geometrical model developed at the LSPM, which is used to visualize the evolution of the deposited crystal shape. This model helped us to identify the specific growth parameters allowing to slow down the growth rate along 〈113〉 direction and, at the same time, continuously increase the area of this crystalline face. Depositions have been carried out and has resulted in a significant increase of 145% of the top-surface area, giving a functional surface of 3.7mm in diameter after a growth of 930µm, starting from 2.3mm. The resistivity, measured by four-point probe system, reaches a value as low as 5mΩ.cm, which is comparable to the best results obtained on thick layers grown on the conventional (100) orientation.

Fixed-Magnetization Ising Model with a Slowly Varying Magnetic Field

The motivation for this paper is the analysis of the fixed-density Ising lattice gas in the presence of a gravitational field. This is seen as a particular instance of an Ising model with a slowly varying magnetic field in the fixed magnetization ensemble. We first characterize the typical magnetization profiles in the regime in which the contribution of the magnetic field competes with the bulk energy term. We then discuss in more detail the particular case of a gravitational field and the arising interfacial phenomena. In particular, we identify the macroscopic profile and propose several conjectures concerning the interface appearing in the phase coexistence regime. The latter are supported by explicit computations in an effective model. Finally, we state some conjectures concerning equilibrium crystal shapes in the presence of a gravitational field, when the latter contributes to the energy only to surface order.

Mechanochemical Transformations of Pharmaceutical Cocrystals: Polymorphs and Coformer Exchange.

Transformations of solid samples under solvent-free or minimal solvent conditions set the future trend and define a modern strategy for the production of new materials. Of the various technologies tested in recent years, the mechanochemical approach seems to be the most promising for economic and ecological reasons. The aim of this review article is to present the current state of art in solid state research on binary systems, which have found numerous applications in the pharmaceutical and materials science industries. This article is divided into three sections. In the first part, we describe the new equipment improvements, which include the innovative application of thermo-mechanochemistry, sono-mechanochemistry, photo-mechanochemistry, electro-mechanochemistry, as well as resonant acoustic mixing (RAM), and transformation under high-speed sample spinning ("SpeedMixing"). A brief description of techniques dedicated to ex-situ and in-situ studies of progress and the mechanism of solid matter transformation (PXRD, FTIR, Raman and NMR spectroscopy) is presented. In the second section, we discuss the problem of cocrystal polymorphism highlighting the issue related with correlation between mechanochemical parameters (time, temperature, energy, molar ratio, solvent used as a liquid assistant, surface energy, crystal size, crystal shape) and preference for the formation of requested polymorph. The last part is devoted to the description of the processes of coformer exchange in binary systems forced by mechanical and/or thermal stimuli. The influence of the thermodynamic factor on the selection of the best-suited partner for the formation of a two-component stable structure is presented.

Comparison Study Between Inherited and Biogenic Calcium Carbonate Formation on The Surface Roots of Eucalyptus Trees Using X-Ray Technique and Field Observations

Background: This study aims to explain the mechanism of formation of calcite and it's to shed light on the synthetic carbonate crystallization on the surface of roots due to this mechanism is poorly understood and highly controversial. It is accepted that calcite formed originally from parent rocks and not in soils. Method: The origin of calcite in calcareous soil, in Aldiwaniya city, Iraq was investigated, by selecting two soil samples, one from the contact zone with root surface and the other sample from bulk soil and out of the root system. Results: X-ray diffraction showed that the calcite has two types, first one is well crystallized and ordered, with only minor deviations in lattice unit cell parameters relative to typical calcite. The clay-sized calcite (active calcite) is enriched in A and C-horizons relative to biogenic calcite and this mineral exist in larger size separates, and it's clearly appears in the shape of white crystals around eucalyptus root surfaces as shown in graphs. The results of X-ray showed that the appearance of smectite mineral which was diagnosed by the peak 14.21 A° in air dry magnesium-saturated treatment which expanded to 16.28 A° when saturated with ethylene glycol, where clarity of peak was increased, Also, the results showed that the appearance of peak 14.21 A° in magnesium saturation air dried, as a shoulder on the peak of the mica (10.14 A°). Conclusion: In general, calcite minerals have characteristic x-ray diffraction peaks at the following angles: 29.5, 31.7, 34.5, 35.7, 47.3, 56.4, and 63.4 degrees.

Monitoring a batch crystallization process by acoustic emission

Crystallization is regarded as an important unit operation for separation and purification, as well as the production of solid particles with specified end-use properties. However, it is still difficult to control or to optimize the crystallization process due to the complexity of the coupled phenomena taking place simultaneously in the liquid and solid phases. In order to overcome such drawback, different analytical technologies have been implemented in the literature for monitoring (in situ, at best) the key crystallization parameters, e.g. solute concentration and crystal size distribution, which in turn enhances the comprehension about this operation. In our work, a multi-probe monitoring system composed of acoustic emission, ATR-FTIR and imaging probes was applied to the crystallization of a model system (an aqueous solution of adipic acid) in a semi-batch crystallizer. The crystallization was carried out under two different feed rates and under vacuum or atmospheric pressure. The goal was to demonstrate the usefulness of the multi-probe system for monitoring the crystallization process and to study the influence of the process (stirring rotation speed, cooling speed, etc.) on the acoustic emission. As a matter of fact, the multi-probe system tracked information about the dissolved adipic acid in the liquid phase with the ATR-FTIR spectrometry, while the crystal size, shape and number were monitored with the help of the imaging probe (with image treatment methods). The acoustic emission probes were used to detect the beginning of crystallization and the phenomena of crystal growth and agglomeration

Giant Thermosalient Effect in a Molecular Single Crystal: Dynamic Transformations and Mechanistic Insights.

The exploration of mechanical motion in molecular crystals under external stimuli is of great interest because of its potential applications in diverse fields, such as electronics, actuation, or sensing. Understanding the underlying processes, including phase transitions and structural changes, is crucial for exploiting the dynamic nature of these crystals. Here, we present a novel organic compound, PT-BTD, consisting of five interconnected aromatic units and two peripheral alkyl chains, which forms crystals that undergo a drastic anisotropic expansion (33% in the length of one of its dimensions) upon thermal stimulation, resulting in a pronounced deformation of their crystal shape. Remarkably, the transformation occurs while maintaining the single-crystal nature, which has allowed us to follow the crystal-to-crystal transformation by single-crystal analysis of the initial and expanded polymorphs, providing valuable insights into the underlying mechanisms of this unique thermosalient behavior. At the molecular level, this transformation is associated with subtle, coordinated conformational changes, including slight rotations of the five interconnected aromatic units in its structure and increased dynamism in one of its peripheral alkyl chains as the temperature rises, leading to the displacement of the molecules. In situ polarized optical microscopy reveals that this transformation occurs as a rapidly advancing front, indicative of a martensitic phase transition. The results of this study highlight the crucial role of a soft and flexible structural configuration combined with a highly compact but loosely bound supramolecular structure in the design of thermoelastic materials.

SrCoNiO3-δ perovskite nanozyme for deep-learning-assisted intelligent detection of dopamine hydrochloride and Cd2+

SrCoO3, SrNiO3, and SrCoNiO3-δ were produced by high-temperature calcination method. Among them, SrCoNiO3-δ trimetallic perovskite exhibited outstanding peroxidase and oxidase activity. Various characterization analyses revealed that the addition of Ni2+ partially replaced Co2+ in the initial perovskite coordination environment, conferring a unique catalytic ability that altered the crystal shape of the original perovskite structure and resulted in a richer electron transfer. This causes the material's surface to exhibit oxygen vacancies (Ovs) and OH radicals, which are the primary source of enzyme activity. Based on the material's excellent enzyme activity, we successfully developed a flexible, intelligent, fast, and instant colorimetry detection platform for the detection of dopamine hydrochloride (DAH) and Cd2+ using a smartphone, assisting in the detection of antibiotic residues in soil and water. The linear ranges of DAH and Cd2+ are 2–20 μM, and their respective detection limits are 0.098 μM and 0.343 μM.

Electromechanical properties and piezoelectric potentials of one-dimensional GaN nanostructures: A bond relaxation investigation

From the viewpoint of atomic bond relaxation, an analytical approach was put forward to elucidate the physical origins of crystal size and cross-sectional shape dependency of piezoelectric potentials in GaN nanowires and nanotubes. It is demonstrated that (i) size-induced increase in piezoelectric potential is attributed to the coupling effect of the rising piezoelectric coefficient and both the reducing dielectric constant and elastic constant caused by the surface atomic coordination number loss, bond energy perturbation, and surface-to-volume ratio rising; (ii) as the number of sides for polygonal nanowires or nanotubes with the same equivalent radius decreases, the surface-to-volume ratio rises, and the piezoelectric potential increases; and (iii) the nanotubes can generate a piezoelectric potential higher than their nanowire counterparts due to their larger surface-to-volume ratios. The proposed formulation offers a scientific basis for the fabrication, optimization, and modulation of one-dimensional GaN-based piezoelectric nanometer devices.

Estimation of the Uncertainty in Daytime Cirrus Cloud Radiative Forcing and Heating Rates Due to Ice Crystal Optics

Abstract The uncertainties in absolute daytime top-of-the-atmosphere (TOA) net cirrus cloud radiative forcing (CRF) and radiative heating rates are estimated at five Micro-Pulse Lidar Network (MPLNET) sites spanning the tropics to high-latitudes. One year of semi-transparent cirrus cloud (optical depth < 3.0 and cloud top temperature < −37 °C) measurements are subject to spectrally-consistent optical properties for nine different ice crystal habits, thus providing a range of possible forcing values. The annual average absolute daytime TOA net CRF is positive at Barbados, Kanpur, and, Singapore (0.59–0.67, 0.61–0.65, and 1.94–2.09 W∙m−2, respectively), negative at Fairbanks (−0.67 to −0.28 W∙m−2), and can regularly become positive or negative at Goddard Space Flight Center (GSFC) (−0.06 to 0.32 W∙m−2). The TOA CRF depends on ice crystal shape; in particular, plates lead to relatively large absolute values that decreases for bullet rosettes and columns. Uncertainties in daytime cirrus cloud radiative properties are estimated as the standard deviation of all possible outcomes when considering the different particle habits individually. Annually, the average uncertainty of the absolute daytime TOA net CRF ranges from 0.50–1.80 W∙m−2. In-cloud daytime net radiative heating rates are positive, on average, at all five sites (0.25–3.84 K/day) and have an estimated uncertainty of less than 0.30 K/day. The uncertainties in cirrus radiative forcing and heating that are characterized by assumptions regarding the ice crystal optical properties must be considered in downstream applications, including satellite retrievals and numerical weather prediction.

Features of water crystallization

Water is mainly composed of ice nanocrystals. The peculiarities of water crystallization can be explained on the basis of its nanostructural structure and nanostructural crystallization. Atmospheric air molecules dissolve well in water and are adsorbed by its nanocrystals. It is shown that the amount of expansion of ice, when water solidifies, is proportional to the concentration of air dissolved in it. The concentration of air dissolved in water decreases significantly with an increase in its temperature. Hot water solidifies faster than cold water because there is less air concentration in hot water. Its bubbles, released on ice crystals, reduce the rate of crystallization of water. A large supercooling of water occurs as a result of the blocking action of adsorbed air, which prevents the unification of ice nanocrystals into crystallization centers. Shaking a bottle of supercooled water leads to desorption of air and accelerated crystallization of water. Air bubbles released on dendritic ice crystals reduce the degree of branching of these crystals. It has been shown that music increases the intensity of removal of gas bubbles and is able to influence the shape of dendritic ice crystals during water crystallization. It has been shown that an increase in the volume of sound and (or) a decrease in its frequency increase the intensity of removal of air bubbles from dendritic ice crystals and increase the branching of these crystals.