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The dissolution behavior of the largest exposed crystal face of Baloxavir marboxil Form I crystal, an anti-influenza drug, was investigated by in-situ atomic force microscopy (AFM) at near molecular scale in water. The largest exposed crystal surface is the (020) face, the microstructure features of layered steps and spiral dislocations appear before dissolution. The in-situ AFM tests show that there are two main dissolution mechanisms: step retreat and pit expansion dissolution. The step retreat dissolution mechanism mainly occurs at the crystal faces where growth steps remain, and the dissolution is promoted by gradual retreat of layered steps. There are two forms of pits in pit expansion dissolution mechanism: regular pits and inverted spiral dislocation pits. The formation of inverted spiral dislocation pits is related to the defect initiated-dissolution at the spiral dislocation sites; the regular quadrilateral pits mainly appear at the relatively smooth and perfect crystal faces, because this characteristic crystal surface can only promote the dissolution process through spontaneous pitting nucleation. When the crystal face is dissolved by the regular pit dissolution mechanism, the critical size of the pit-dissolution exists, meaning only pits above a certain size can promote dissolution. [ABSTRACT FROM AUTHOR]

Achieving diffraction‐limited performance in fourth‐generation synchrotron radiation sources demands monochromator crystals that can preserve the wavefront across an unprecedented extensive range. There is an urgent need for techniques of absolute crystal diffraction wavefront measurement. At the Beijing Synchrotron Radiation Facility (BSRF), a novel edge scan wavefront metrology technique has been developed. This technique employs a double‐edge tracking method, making diffraction‐limited level absolute crystal diffraction wavefront measurement a reality. The results demonstrate an equivalent diffraction surface slope error below 70 nrad (corresponding to a wavefront phase error of 4.57% λ) r.m.s. within a nearly 6 mm range for a flat crystal in the crystal surface coordinate. The double‐edge structure contributes to exceptional measurement precision for slope error reproducibility, achieving levels below 15 nrad (phase error reproducibility < λ/100) even at a first‐generation synchrotron radiation source. Currently, the measurement termed double‐edge scan (DES) has already been regarded as a critical feedback mechanism in the fabrication of next‐generation crystals. [ABSTRACT FROM AUTHOR]

The article presents a model of the thickness of the surface layer of YBCO crystals, from which its domain structure follows. It is shown that in the surface nanolayer, the temperature of the transition to the superconducting state increases by 2 times compared to the bulk phase. Lamels in the monodomain are determined as Abrikosov vortices, and there are 15 of them in the surface layer of YBCO. [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]

Phosphoric acid etching combined with hydrothermal treatment was used to construct a Sc2O3-ZnO coating on the Zn anode surface to tune the content of Zn (002) crystal surface. The (002) crystalline surface of Zn surface became the preferred crystal face for the H3PO4 etching time of 7 min and hydrothermal reaction for 2 h at 160°C. The polarization curve results showed that in 2 M of ZnSO4 solution, the corrosion potential of Zn anode with (002) crystallographically optimal orientation was positively shifted by 663 mV and the corrosion current density was reduced by about four orders of magnitude compared with the bare Zn. The results of LSV and XRD showed that the Zn anode with (002) preferred crystal face possessed a more negative hydrogen evolution potential, which effectively hindered the occurrence of the H2 evolution side reaction and significantly inhibited the corrosion of metal Zn and the generation of alkaline zinc sulfate hydrate as a byproduct. Dense Sc2O3-ZnO coatings composed of crosslinked nanofibers provided a long-lasting and effective shielding protection. The coating facilitated the induction of Zn (002) crystal face oriented deposition, and the bonding of N or P enhanced the stability of coating, which significantly enhanced the corrosion resistance. [ABSTRACT FROM AUTHOR]

The rapid release of gas by a chemical reaction to generate momentum is one of the most fundamental ways to elicit motion that could be used to sustain and control the motility of objects. We report that hollow crystals of a three‐dimensional supramolecular metal complex that releases gas by photolysis can propel themselves or other objects and advance in space when suspended in mother solution. In needle‐like regular crystals, the reaction occurs mainly on the surface and results in the formation of cracks that evolve due to internal pressure; the expansion on the cracked surface of the crystal results in bending, twisting, or coiling of the crystal. In hollow crystals, gas accumulates inside their cavities and emanates preferentially from the recess at the crystal terminus, propelling the crystals to undergo directional photomechanical motion through the mother solution. The motility of the object which can be controlled externally to perform work delineates the concept of "crystal microbots", realized by photoreactive organic crystals capable of prolonged directional motion for actuation or delivery. Within the prospects, we envisage the development of a plethora of light‐weight, efficient, autonomously operating robots based on organic crystals with high work capacity where motion over large distances can be attained due to the large volume of latent gas generated from a small volume of the crystalline solid. [ABSTRACT FROM AUTHOR]

The current study aimed to establish an experimental model in vitro and in vivo of urinary crystal deposition on the surface of ureteral stents, to evaluate the ability to prevent crystal adhesion. Non-treated ureteral stents were placed in artificial urine under various conditions in vitro. In vivo, ethylene glycol and hydroxyproline were administered orally to rats and pigs, and urinary crystals and urinary Ca were investigated by Inductively Coupled Plasma-Optical Emission Spectrometer. in vitro, during the 3- and 4-week immersion periods, more crystals adhered to the ureteral stent in artificial urine model 1 than the other artificial urine models (p < 0.01). Comparing the presence or absence of urea in the composition of the artificial urine, the artificial urine without urea showed less variability in pH change and more crystal adhesion (p < 0.05). Starting the experiment at pH 6.3 resulted in the highest amount of crystal adhesion to the ureteral stent (p < 0.05). In vivo, urinary crystals and urinary Ca increased in rat and pig experimental models. This experimental model in vitro and in vivo can be used to evaluate the ability to prevent crystal adhesion and deposition in the development of new ureteral stents to reduce ureteral stent-related side effects in patients. [ABSTRACT FROM AUTHOR]

We present the development of a heat flow model utilizing a scintillating crystal for heat and light detection. By analyzing the measured light signals from α - and β / γ -induced events in a CaMoO 4 crystal, we describe the time-dependent behavior of the scintillation emission and the subsequent generation of delayed phonons in the crystal. The phonon detection channel model incorporates both prompt and delayed generation of a thermal phonons; these are absorbed in a phonon collector film on the crystal surface or converted into a thermal phonon distribution in the crystal. A reasonable agreement is observed in the comparison between the measured signals and the simulated signals derived from the model study. We attribute the observed pulse shape discrimination to the presence of the delayed phonons associated with the scintillation process. [ABSTRACT FROM AUTHOR]

Rate maps quantify the variability of surface rates during the dissolution of crystalline matter. Recently, highly spatially resolved rate maps revealed the existence of rhythmic pulses of the material flux from the crystal surface. The mechanism underpinning this behavior is not yet understood but the two potential influencing factors are surface-controlled or transport-controlled conditions that may govern the resulting pulsating reaction kinetics in the system. In this study, we apply two numerical methods to identify the dominating mechanism of pulsating dissolution. First, the influence of solute transport is simulated using a reactive transport model, which yields dissolution rates and concentration distribution due to the flow field, i.e., extrinsic reactivity. Second, the influence of intrinsic surface reactivity inherent to the material is simulated using kinetic Monte Carlo (KMC) simulations, where the distribution of reactive sites over time is observed on an atomic scale. Local dissolution rates can be reproduced with the reactive transport model, but no kinetically effective periodic changes of the concentration gradients can be observed and no new dissolution pulses are generated. Control via periodic changes in extrinsic reactivity is thus ruled out as a governing mechanism. In contrast, pulsating dissolution is clearly observed in the KMC simulation, leading to the conclusion that the self-assembly of varying reactive surface building blocks causes the pulsating dissolution. The simulation results suggest that etch pits generate regions with a high number of steps of single crystal layers and, consequently, with sites of increased reactivity at periodic intervals. These steps move over the crystal surface outward from the pit center and are followed by a region with a low number of surface steps. Only when the steps reach a certain spacing to the center new steps are generated at the transition between the hollow core and the etch pit. This self-assembly is observed as a fundamental behavior of crystalline dissolution in KMC models, without any additional parametrization. It thus represents a fundamental mechanism in crystal dissolution and should be considered for an accurate atomic understanding of crystal dissolution. [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]

GaN nanostructures are promising for a broad range of applications due to their 3D structure, thereby exposing non-polar crystal surfaces. The nature of the exposed crystal facets, i.e., whether they are a-, m-plane, or of mixed orientation, impacts the stability and performance of GaN nanostructure-based devices. In this context, it is of great interest to control the formation of well-defined side facets. Here, we show that we can control the crystal facet formation at the nanowire sidewalls by tuning the III–V ratio during selective area growth by molecular beam epitaxy. Especially, the N flux serves as a tool for controlling the growth kinetics. In addition, we demonstrate the growth of GaN nanofins with either a- or m-plane side facets. Based on our observations, we present the underlying nanostructure growth mechanisms. Low temperature photoluminescence measurements show a correlation of the formation of structural defects like stacking faults with the growth kinetics. This article demonstrates the controlled selective epitaxy of GaN nanostructures with defined crystal side facets on large-scale available AlN substrates. [ABSTRACT FROM AUTHOR]

Precisely introducing topological defects is an important strategy in nanographene crystal engineering because defects can tune π‐electronic structures and control molecular assemblies. The synergistic control of the synthesis and assembly of nanographenes by embedding the topological defects to afford two‐dimensional (2D) crystals on surfaces is still a great challenge. By in‐situ embedding ladder bipyrazinylene (LBPy) into acene, the narrowest nanographene with zigzag edges, we have achieved the precise preparation of 2D nonbenzenoid heteroacene crystals on Au(111). Through intramolecular electrocyclization of o‐diisocyanides and Au adatom‐directed [2+2] cycloaddition, the nonbenzenoid heteroacene products are produced with high chemoselectivity, and lead to the molecular 2D assembly via LBPy‐derived interlocking hydrogen bonds. Using bond‐resolved scanning tunneling microscopy, we determined the atomic structures of the nonbenzenoid heteroacene product and diverse organometallic intermediates. The tunneling spectroscopy measurements revealed the electronic structure of the nonbenzenoid heteroacene, which is supported by density functional theory (DFT) calculations. The observed distinct organometallic intermediates during progression annealing combined with DFT calculations demonstrated that LBPy formation proceeds via electrocyclization of o‐diisocyanides, trapping of heteroarynes by Au adatoms, and stepwise elimination of Au adatoms. [ABSTRACT FROM AUTHOR]

Our understanding of quantum materials is commonly based on precise determinations of their electronic spectrum by spectroscopic means, most notably angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy. Both require atomically clean and flat crystal surfaces, which are traditionally prepared by in situ mechanical cleaving in ultrahigh vacuum chambers. We present a new approach that addresses three main issues of the current state-of-the-art methods: (1) Cleaving is a highly stochastic and, thus, inefficient process; (2) fracture processes are governed by the bonds in a bulk crystal, and many materials and surfaces simply do not cleave; and (3) the location of the cleave is random, preventing data collection at specified regions of interest. Our new workflow is based on focused ion beam machining of micro-strain lenses, in which shape (rather than crystalline) anisotropy dictates the plane of cleavage, which can be placed at a specific target layer. As proof-of-principle, we show ARPES results from micro-cleaves of Sr2RuO4 along the ac plane and from two surface orientations of SrTiO3, a notoriously difficult to cleave cubic perovskite. [ABSTRACT FROM AUTHOR]

To investigate the mechanism underlying high acid resistance of enamel after erbium laser etching. Forty-five premolars were collected and assigned to three groups. A 4×4×1 mm enamel sample was prepared, the left side was the control side, the right side was the treated side, which was treated with different surface treatments, including 35% phosphoric acid etching, Er:YAG laser etching, and Er,Cr:YSGG laser etching. The hydroxyapatite crystal size on the enamel surface of the samples was observed. The contents of Ca, P, O, F, Cl, C, Mg were detected. The crystallinity of the hydroxyapatite crystal was analyzed. After erbium laser etching, the enamel surface had high hydroxyapatite crystal size, beneficial content of chemical elements and crystallinity. The morphological and composition changes of crystals in the enamel surface after erbium laser etching may be one of the crucial mechanisms underlying the enhancement of acid resistance of enamel after erbium laser etching. [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]

Laser induced damage sites on the surface of a KDP crystal component tend to grow with subsequent laser irradiation, which substantially decrease the lifetime of these optics. The structural investigation suggests that this may be related to the surface damage products of the crystals. In this work, the differences in the crystal structures, electronic properties and optical absorption between the KDP crystal and its surface laser-induced decomposition products K2H2P2O7 and KPO3 are investigated by using first-principles calculations. The theoretical results show that the nonlinear optical active units of KDP crystals are disrupted after irradiation dehydration to K2H2P2O7 and KPO3, which leads to the optical properties at the surface damage being deteriorated. In terms of the electronic structure, the dehydration products K2H2P2O7 and KPO3 have a shorter band gap compared with the KDP crystal. In addition, K2H2P2O7 and KPO3 have a wider optical absorption band than that of the KDP crystal and introduce more ultraviolet absorption in the optical elements. Compared to polycrystalline KDP at the bulk damage sites, the dehydration products at the surface damage increase the ultraviolet absorption of the crystals and cause the surface damage to continually grow under subsequent irradiation, whereas the bulk damage does not continue to increase in subsequent laser irradiation. [ABSTRACT FROM AUTHOR]

We report a photochemical bismuth vanadate (BiVO4) sensing material, which possesses a large proportion of (110) and (011) facets combined with the additional (111) facets, for the selective detection of ultra‐low concentration hydrogen sulfide (H2S) driven by visible light. Specifically, the obtained octadecahedron BiVO4 (Octa‐BiVO4) performs a high response value (67) and short response time (47.4 s) to 100 ppm H2S with good stability for nearly 100 days, as well as undisturbedness by moist air. With the combination of experimental and theoretical calculation results, the adsorption and carrier transfer behaviors of H2S molecules on the Octa‐BiVO4 crystal surface are investigated. By adjusting the ratio of different crystal facets and controlling the facets with characteristic adsorption, we achieve improved anisotropic photoinduced carrier separation and high selectivity for a specific gas. Furthermore, this facial facet engineering can be extended to the synthesis of other sensing materials, offering huge opportunities for fundamental research and technological applications. [ABSTRACT FROM AUTHOR]

Phosphogypsum (PG) is a solid waste generated during the "wet phosphoric acid process." The phosphorus (P) impurities and low‐value‐added recycling products seriously constrain PG re‐utilization, which results in its massive accumulation and thus occupies large land areas and poses a severe pollution threat to the environment. In this study, by regulating gypsum crystal and P species in CaCl2–HCl solutions under mild conditions, efficient removal of P impurities (leaching efficiency of 97.78%) and synchronous preparation of high‐strength α‐CaSO4·0.5H2O (α‐HH) (compressive strength of 35.2 MPa) from PG were achieved during the phase transition from CaSO4·2H2O (DH) to α‐HH, which was a reaction of DH dissolution, followed by α‐HH crystallization. The co‐crystalline P was fully released during the dissolution process, which was necessary to efficiently eliminate P impurities. HCl dissolved the released P and transformed them into the protonated specie (H3PO4) with less similarity to SO42−, which prevented the recombination of the released P with gypsum during the crystallization process. Furthermore, α‐HH morphology and size were controlled by seeding in the mixed solutions. The formation of regular large α‐HH crystals with a low‐specific surface area significantly weakened the surface adsorption of P in solutions and further increased the P leaching efficiency. More importantly, the large stumpy α‐HH was identified as high‐strength gypsum with high added value. This work would provide innovative guidance to efficiently remove impurities from gypsum and pioneer a cost‐effective approach for clean and high‐value utilization of industrial gypsum residues. [ABSTRACT FROM AUTHOR]

To realize organic integrated optoelectronic circuits, there is a need for anisotropic optical waveguides at the micro/nanoscale. Anisotropic alignment of one‐dimensional‐ordered supramolecular structures composed of light‐emissive π‐conjugated molecules in a crystal may meet the requirements of such waveguides. Here, a bipyridyl‐appended acrylonitrile‐based π‐conjugated molecule was designed, which produced a one‐dimensional supramolecular polymer constructed through non‐covalent bonding between a lone pair in bipyridyl and a σ‐hole in 1,4‐diiodo‐2,3,5,6‐tetrafluorobenzene. The one‐dimensional copolymer of bipyridyl and 1,4‐diiodo‐2,3,5,6‐tetrafluorobenzene is aligned horizontally with the two‐dimensional crystal surface because of the angle‐controlled supramolecular synthons. As a result of control over the non‐covalent bonding direction, anisotropic photoluminescence and photon transport (optical waveguiding) characteristics are realized by orienting the transition dipole moment horizontally with respect to the two‐dimensional surface. Compared with the loss coefficient αL=52 dB cm−1 for the long‐axis direction of the two‐dimensional platelet cocrystal, a very large difference of αS=2111 dB cm−1 is present in the crystal short‐axis direction. The anisotropic waveguiding ability, αL/αS, is estimated to be 41, which is more than an order of magnitude greater than previously reported two‐dimensional platelet crystal waveguides. This supramolecular synthon provides an approach to designing anisotropic photon transporters and highly regulated optical logic circuits. [ABSTRACT FROM AUTHOR]

The presence of tetrazine units in the organic nodes of UiO‐68‐TZCD controls the formation of ultrathin coatings of single‐wall nanotubes that decorate the surface of the crystal. These crystal hybrids can be prepared straightforwardly in one step and are extraordinarily respectful with the properties of the framework for combination of mesoporosity and surface areas ≈4.000 m2 g−1, with excellent stability in water, and conductivities at room temperature of 4 × 10−2 S cm−1 even at very low carbon weight contents (2.3 wt.%). [ABSTRACT FROM AUTHOR]

The formation of chiral magnetic soliton lattice (CSL) is investigated in monoaxial chiral dichalcogenide CrTa3S6 crystals in terms of a surface barrier, which prevents the penetration of chiral solitons into the system and is an intrinsic origin of hysteresis for the continuous phase transition of nucleation-type, as discussed in the system of quantized vortices in type-II superconductors. The magnetoresistance (MR) was examined with microfabricated platelet samples in different dimensions with regard to the c-axis direction of the crystal. The CSL formation was confirmed by the discrete MR changes, reflecting the number of chiral solitons, as well as by the presence of a surface barrier, recognized as a fixed ratio of critical magnetic fields during the hysteresis field cycle. We also argue the influence of the surface barrier in bulk CrTa3S6 crystals. [ABSTRACT FROM AUTHOR]

The crystal morphology of glucosamine hydrochloride (GAH) during antisolvent crystallization was investigated in this work. Particles of different shapes, such as plate-like crystals, leaflike clusters, fan-like dendrites, flower-like aggregates, and spherulites, were produced by tuning the type of antisolvents and crystallization operating conditions. The hierarchical structures of GAH crystals tended to be formed in a water + isopropanol mixture. The effects of operation parameters on the polycrystalline morphology were studied, including crystallization temperature, solute concentration, feeding rate of GAH aqueous solution, solvent-to-antisolvent mass ratio, and stirring rate. The evolution process of GAH spherulites was monitored using SEM, indicating a crystallographic branching mode. The crystal habit was predicted to identify the dominant faces. Molecular dynamics simulations were performed and the interaction energy of solute or solvent molecules on crystal surfaces was calculated. The experimental and simulation studies help to understand the branching mechanism and design a desired particle morphology. [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]

As a photoelectric material, the luminescent efficiency improvement of organic–inorganic perovskite material is a hot topic. This work fabricated a nanoporous distributed Bragg reflector based on GaN with a periodic structure using electrochemical etching methods. Considering the fact that hybrid perovskite materials are difficult to prepare on an inorganic GaN-based substrate, ultraviolet ozone treatment was implemented to enhance the surface activity of the prepared distributed Bragg reflector substrate. Cubic CH3NH3PbBr3 crystals with smooth surfaces and precise edges were successfully prepared on the ozone-treated distributed Bragg reflector substrate by a two-step immersion method in the air environment. The structural property of the prepared CH3NH3PbBr3 crystals was investigated using X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy. The structural analysis results showed that CH3NH3PbBr3 crystals grown on the prepared distributed Bragg reflector and reference substrates have the same structure, with a good crystal quality. The photoluminescence intensity of CH3NH3PbBr3 crystals grown on the distributed Bragg reflector was significantly enhanced. The enhancement is approximately 3.11-fold compared with CH3NH3PbBr3 crystals grown on the unetched reference GaN substrate. Moreover, there is a 7.2 nm spectral blue shift. The enhancement of the photoluminescence intensity could be attributed to the out-coupling of emission light in the prepared crystals, and the blue shift could be attributed to the stress relaxation caused by the nanoporous GaN structure of the distributed Bragg reflector substrate. [ABSTRACT FROM AUTHOR]

The application range of potassium dihydrogen phosphate (KDP) crystals can be expanded by enhancing their surface quality properties. Therefore, a method for controlling the surface-temperature field of various materials was developed to expand the plastic zone to overcome the difficulty in processing KDP crystals. The ductile/brittle transition depth of the KDP crystals was determined using a 38 nm nanoindentation experiment. The nanoscratch experiment revealed the rules of how the transformation depth of the KDP crystals changes with temperatures, and the effect of temperature on the microstructure of the KDP crystals was studied. Finally, KDP crystal surfaces were processed using a UPDFC machine at elevated temperatures. According to our experiments, the surface roughness of the KDP crystal reached 5.275 nm as temperature increased, thus enhancing its surface quality. This method could be applied to other brittle materials. [ABSTRACT FROM AUTHOR]

In a previous paper [Sasso et al. (2023). J. Appl. Cryst.56, 707–715], the operation of a triple‐Laue X‐ray interferometer having the splitting or recombining crystal cylindrically bent was studied. It was predicted that the phase‐contrast topography of the interferometer detects the displacement field of the inner crystal surfaces. Therefore, opposite bendings result in the observation of opposite (compressive or tensile) strains. This paper reports on the experimental confirmation of this prediction, where opposite bendings were obtained by copper deposition on one or the other of the crystal sides. [ABSTRACT FROM AUTHOR]

To achieve ultra-precision polishing of soft, brittle, and water-soluble KDP crystals and obtain high-quality scratch-free surfaces, new anhydrous-based shear-thickening slurry is developed in this study. By comparing the molecular properties of the multi-chain polyhydroxy polymer and the single-chain polyhydroxy polymer, a prediction model is established for the contact between particles and the dispersive media. Subsequently, the rheological properties of the experimental groups are measured using different dispersive media. The results demonstrate that the multi-chain polyhydroxy polymer exhibits a shear-thickening effect and higher peak viscosity at a lower mass fraction. Therefore, it is more suitable for application as anhydrous shear-thickening slurry. In this study, KDP crystals with dimensions of 30 mm × 30 mm × 12 mm are used as a workpiece, and abrasive solutions at varying concentrations of the abrasive agent are used to polish the crystal. The results reveal that when the polymer mass fraction is 55.2%, the surface roughness of the polishing slurry made of single-chain polyhydroxy polymer reaches Ra 8.69 nm at 3 wt% abrasive concentration. Further, the surface roughness of the multi-chain polyhydroxy polymer polishing slurry reaches Ra 2.23 nm at an abrasive concentration of 6 wt%. According to this study, the anhydrous-based shear-thickening slurry with multi-chain polyhydroxy polymer as the dispersed phase has better rheological properties and is more suitable for the processing of KDP crystal surface compared with the single-chain polyhydroxy polymer. In addition, owing to the flexible machining characteristics of shear-thickening polishing slurry, the workpiece surface can be processed without scratches. [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]

A complete processing technology for ZnGeP2 (ZGP) crystals was developed to meet the requirement of subnanoscale surface roughness for them in high energy applications. Firstly, the semi-finished ZGP crystal is cut into a cuboid of size 7 mm x 7 mm x 15 mm using an inner circle cutter. Secondly, the ZGP crystal was mechanically lapped with diamonds preferentially 5 μm in size which was selected based on the comparison experiments to reduce its surface roughness (Sa) to about 150 nm rapidly. Thirdly, based on the chemical mechanical polishing (CMP) technique, a "rough" CMP step in an aqueous suspension of diamonds with a size of 3 μm and a "fine" CMP step in a SiO2 slurry were adopted. The result of single-factor experiment showed that the best duration for both the "rough" and "fine" CMP steps should be one hour. The slurry composition and operation conditions of the "fine" CMP step was optimized by orthogonal test as follows: SiO2 (particle size 0.05 μm) 4wt%, H2O2 3wt%, pH = 8, polishing pressure 17.24 kPa, rotation speed 13.5 r/min, and slurry flow rate 300 mL/min. Finally, super-smooth ZGP crystals with a surface roughness of 0.106 μm could be obtained. [ABSTRACT FROM AUTHOR]

The impregnation of poorly water-soluble drug onto the surface of a suitable pharmaceutical excipient, used as a hydrophilic carrier, can lead to the preparation of systems with improved dissolution properties due to the separation of drug crystal particles on the carrier surface. For this purpose, a method based on impregnation of hydrophilic matrix by the hydrophobic poorly water-soluble drug Meloxicam (MX) solution in volatile organic solvent was used. After the evaporation of the solvent, the method resulted in coverage of the carrier surface by drug crystals. The influence of the amount and concentration of the impregnating solution on the formed MX crystal size and the dissolution rate was evaluated. Firstly, the impregnation forming crystals on the planar surface was studied and the MX maximum dissolution flux from that surface was determined. The optimum preparation method was further used to produce a volume of impregnated granules. The dissolution performance of the granules was evaluated, and the dissolution kinetics was described by mathematical models. The polymorphic modification of impregnated API and influence of impregnated drug amount on the hydrophilic carrier surface coverage were considered. From the results of this work, it is clear that the impregnated drug amount and the number of impregnations cycles can be optimized to achieve maximum drug release rate. [ABSTRACT FROM AUTHOR]

The chirality of biopolymers and its emergence from the racemic prebiotic world is one of the key mysteries of science. There are many versions on how the total chiral balance breaking occurred, but they all face an insoluble challenge—the impossibility of a total shift of the chiral balance towards the formation of biopolymers based only on D-sugars and L-amino acids. A possible solution to this problem lies in the asymmetric autocatalysis on chiral crystals. Since the reaction is heterogeneous, it is important to study the features of adsorption on the surface of crystals. In this paper, the adsorption of limonene, α-pinene, and menthol enantiomers on γ-glycine and CsCuCl3 crystals was studied. Single-crystal X-ray crystallography, SEM, and porosimetry were used as auxiliary methods. The t-test was used to determine the reliability of chiral recognition. It was shown that both crystals were capable of chiral recognition at high coverages. The mechanism of supramolecular chiral recognition was identical to that of the chiral crystals studied previously. However, neither γ-glycine nor CsCuCl3 showed chiral recognition with respect to all enantiomers. In fact, γ-glycine crystals showed recognition for limonene enantiomers, and very high recognition in the case of menthol enantiomers. CsCuCl3 crystals showed the capability to recognize enantiomers of α-pinenes only. This led to the conclusion that the recognition of enantiomers by a supramolecular chiral surface is not universal. [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]

The results of an experimental study of the abnormal domain structure kinetics in lithium niobate single crystals with a surface layer modified by soft proton exchange are presented. Domain switching in a wide field range allowed two qualitatively different types of domain structure evolution to be revealed: (1) the traditional growth of hexagonal domains in fields higher than 21.5 kV/mm and (2) the abnormal growth of stripe domains oriented along the Y crystallographic directions in the field range from 3.8 to 21.5 kV/mm. The stripe domains had a width up to 4 µm and depth up to 30 µm. It was shown that the time dependence of the total length of stripe domains could be analyzed in terms of the modified Kolmogorov–Avrami approach, taking into account the transition from the one-dimensional β-model to the one-dimensional α-model. The possibility of the controllable creation of a quasi-periodic structure of stripe domains with an average period of 5 µm by a two-stage polarization switching process was demonstrated. The formation and growth of stripe domains were considered in terms of the kinetic approach to the evolution of the domain structure as a result of the domain walls' motion under inefficient screening conditions caused by the presence of a modified surface layer. The abnormally low threshold fields were attributed to a presence of a "built-in" field facilitating switching, created by a composition gradient induced by soft proton exchange. [ABSTRACT FROM AUTHOR]

The 2H (sp. gr. Р63mc) polytypes of the CdInAlS4 (а = 3.87 Å and с = 24.65 Å), Fe0.75Ga0.25InS3 (a = 3.78 Å and c = 24.44 Å), and Mg0.7Ga1.4In0.8S4 (a = 3.81 Å and c = 24.39 Å) compounds have been established from electron diffraction patterns obtained by special tilting of a crystal holder with a single-crystal film and its subsequent rotation. The single-crystal films of the first two compounds are located on the surface of the crystal holder, and the film of the third compound makes a certain angle with it. For this case, a diagram explaining the origin of some of the reflections positioned unconventionally (beyond the ellipse line) is presented. This diagram can be used in further electron diffraction study of the structure of nanoobjects oriented arbitrarily on a crystal holder. [ABSTRACT FROM AUTHOR]

Within the framework of the available theories, the initiation of plastic shear and nucleation cracks in perfect crystals is possible only at a deforming stress close to the theoretical strength. It is shown that a perfect crystal, treated as an open system of nuclei and electrons, loses its stability at applied stresses that are orders of magnitude smaller than the theoretical strength. This helps avoiding the use of the concept of various types of defects present in the bulk and in the surface layer of the crystal. The physical reason for the instability is the excitation of dynamic displacements determined by nonadiabatic transitions of Landau-Zener atoms between the intersecting potential energy surfaces in open nonequilibrium systems. A qualitative explanation of the experimentally observed results is given. [ABSTRACT FROM AUTHOR]

Gypsum (calcium sulfate dihydrate) is one of the most used inorganic binding materials in the world. During calcination, calcium sulfate subhydrates are formed and, for technical reasons, are mixed with water to form dihydrate again. Therefore, the dehydration process of gypsum and the rehydration of hemihydrate were investigated. This dehydration process is technically performed in three different ways. Heating up, i.e., in a rotary kiln, leads to a preferred formation of β-hemihydrate, which crystallizes in comparatively small crystals. Similar results can be achieved by recrystallization from gypsum slurry around 100 °C in an autoclave or under a water steam atmosphere. However, in contrast, the recrystallization process here leads to the formation of a larger, needle-like morphology and sometimes branched α-hemihydrate crystals. The synthesis of β-hemihydrate was investigated in detail with a special thermal stage for optical microscopy on natural single gypsum crystals. It was observed that the crystal loses transparency because of the breaking surface of the crystals due to water evaporation. Furthermore, within a deeper layer of the crystal, new crystals become visible but disappear during dehydration of the upper layers. These are expected to be α-hemihydrate. This theory of the formation of α-hemihydrate inside of a gypsum crystal is experimentally proven in the present work. This work firstly shows that the observed crystallization inside of gypsum during dehydration is the formation of alpha-hemihydrate. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel acylhydrazone based molecule was designed and synthesized that exhibit bright solid state luminescence. • The crystals exhibit multi-stimuli responsive property such as, mechanochromic, thermochromic and vapochromic luminescence switching. • The crystals display fascinating macroscopic surface cracking, movements when 365 nm or 405 nm light is illuminated on the crystal surface. • The examples of such single molecular material that have capability to respond to multiple stimuli is extremely rare. In this manuscript, we report a novel diphenylamine-acylhydrazone based compound namely (E)-N'-(4-(diphenylamino)benzylidene)-4-hydroxybenzohydrazide (DPAhydrzOH) which showed multi-stimuli responsive behavior by displaying pronounced mechanochromic luminescence (MCL), thermochromic luminescence and photomechanical effect in solid state. Single crystal structure of the compound revealed that the molecule is tied with different types of H-bonding interactions. Detailed mechanistic study suggests that the MCL switching in solid crystal is rooted to the shear pressure induced structural rearrangement. The captivating photomechanical effect in the crystal was expressed in the form of cracking, small movement under 365 nm light due to photoinduced trans to cis isomerization in solid state. [ABSTRACT FROM AUTHOR]

• The crystal morphology of the CL-20/TFAZ cocrystal was predicted using modified attachment energy in solvent. • Crystal shape becomes closer to a stereoscopic shape in IPA/EA solvents. • The interaction between CL-20/TFAZ cocrystal and various solvents was analyzed using radial distribution function. • Mean square displacement method was used to analyze the diffusion coefficients of various solvents in CL-20/TFAZ cocrystal. Crystal morphology of CL-20/TFAZ cocrystal in vacuum was predicted using the attachment energy (AE) model. Additionally, the modified attachment energy (MAE) model and molecular dynamics (MD) method were utilized to predict the crystal morphology of CL-20/TFAZ cocrystal in four different binary solvents, namely, isopropyl alcohol (IPA)/acetone (AC), IPA/dimethyl sulfoxide (DMSO), IPA/ethyl acetate (EA), and IPA/water (H 2 O). The radial distribution function (RDF) between the solvent and crystal surface and the mean square displacement (MSD) of the solvent were calculated. The findings showed that the morphology of CL-20/TFAZ cocrystal in vacuum was an irregular polyhedron with eleven important growth surfaces: (0 0 1), (1 −1 0), (1 1 0), (1 0 0), (0 1 1), (0 −1 1), (1 0 −1), (0 2 0), (0 −2 0), (1 1 −1), and (1 −1 −1), with the (0 0 1) surface having the highest area ratio of 31.693 %. The crystalline morphology in IPA/AC, IPA/DMSO, and IPA/EA solvents was block-shaped, while it was rod-shaped in IPA/H 2 O. Comparing the RDF values of the four solvents, IPA/H 2 O exhibited the largest g(r) value and could more easily adsorb onto the crystal surface of CL-20/TFAZ cocrystal. Interestingly, IPA/H 2 O solvent had the smallest MSD value, suggesting the slowest diffusion rate, while IPA/AC solvent exhibited the fastest diffusion rate. Overall, IPA/EA solvents were more suitable for the formation of CL-20/TFAZ cocrystal. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) crystal is a third-generation semiconductor material, which is widely used in the fields of radio frequency components, aerospace, new energy vehicles, etc. The anisotropy of 4H–SiC leads to differences in material removal characteristics of different crystal surfaces, which influences the design of process parameters for SiC crystal polishing. A model of single abrasive scratching 4H–SiC crystal was established using molecular dynamics. The effect of scratching speed and depth on the material removal characteristics and the wafer surface morphology was investigated when a single abrasive scratches the C surface and Si surface. Scratching experiments were conducted to verify the model by measuring scratch cross-sectional area, scratch profile, and surface roughness. The simulation results reveal that compared to the Si surface, the distribution range of high hydrostatic stress of the C surface is less, resulting in fewer amorphous atoms and easier dislocation, which means the C surface is more favorable for getting plastic removal and obtaining better surface quality. The experiment data suggested that the C surface has a smaller surface roughness and a friction coefficient, and the cross-sectional area of the scratch is larger than that of the Si surface. Under low-speed conditions, the influence of anisotropy is more pronounced. Consistent with the simulation result, the material removal characteristics of the C surface are better than those of the Si surface when single abrasive scratching 4H–SiC crystal. [ABSTRACT FROM AUTHOR]

To analyze the influences of surfaces topography on the laser damage and performance of KH2PO4 (KDP) crystal, the frequency features of machined surface KDP crystal surfaces were extracted and reconstructed by power spectral density and continuous wavelet transform. Wave optics theory was used to analyze the influences of frequency features on the subsurface light temperature fields of KDP crystals irradiated by 1.064 µm laser wavelength with the power of 20 MW/µm² for Ins. The results show that temperature of KDP crystals becomes larger with wavelength of surface frequencies closer to incident laser wavelength(1.064 µm). If the wavelength is over 20 µm, temperature of KDP crystals is unchanged with the changing of frequency features. The obvious wavelengths on the machined surface of KDP crystals obtained by cutting experiments are as 14 µm, 50 µm and 140 µm respectively, and the subsurface temperature of KDP crystal affected by these frequency features rises are as 56K, 22K and 12K. Maximum temperature of KDP crystals Increases with the increasing of amplitude under the same wavelength. With the increasing of surface frequency wavelength, the positon of the maximum temperature extends to the interior of the KDP crystals. [ABSTRACT FROM AUTHOR]

We investigated the adhesion of polyvinyl chloride (PVC) to 2D crystal flakes on SiO2/Si substrates. Although the anchoring effect cannot be used to explain adhesion to atomically flat surfaces, PVC is sufficiently strongly adhesive to 2D crystal flake surfaces to allow pickup from SiO2/Si substrates via surface contact alone. Results of the pickup test, whether pickup is possible or impossible, were plotted on a map of contact surface area ratio vs. contact edge length ratio, which allowed us to identify the conditions under which flakes can be picked up using PVC and to discuss the adhesion strengths of the surface and edge. This study provides a method for the evaluation of adhesion forces between polymers and 2D flakes and demonstrates that PVC is a useful polymer for deterministic transfer and versatile manipulation of 2D flakes. [ABSTRACT FROM AUTHOR]

Accurate corrections for the effects of alpha ejection (the loss of daughter He near grain or crystal surfaces due to long alpha stopping distances) are central to (U-Th)/He thermochronometry. In the case of apatite (U-Th)/He dating, alpha-ejection correction is complicated by the fact that crystals are often broken perpendicular to the c axis. In such cases, the correction should account for the fact that only some parts of the crystal are affected by alpha ejection. A common current practice to account for such broken crystals is to modify measured lengths of broken crystals missing one termination by a factor of 1.5, and those missing both terminations by a factor of 2. This alpha-ejection "correction correction" systematically overestimates the actual fraction of helium lost to alpha ejection, and thus overcorrects the measured date relative to that determined for an otherwise equivalent unbroken crystal. The ratio of the alpha-ejection-affected surface area to the volume of a fragmented crystal is equivalent to the surface-area-to-volume ratio of an unbroken crystal that is either twice as long (for fragments with one termination) or infinitely long (for fragments with no termination). We suggest that it is appropriate to revise the fragmentation correction to multiply the lengths of crystals missing one c -axis termination by 2, and those missing both c -axis terminations by some large number ≳20. We examine the effect of this revised correction and demonstrate the accuracy of the new method using synthetic datasets. Taking into account alpha ejection, the rounding of the He concentration profile due to diffusive loss, and the accumulation of radiation damage over a range of thermal histories, we show that the revised fragmentation alpha-ejection correction proposed here accurately approximates the corrected date of an unbroken crystal ("true" date) to within <0.7 % on average (±4.2 %, 1 σ), whereas the former method overcorrects dates to be ∼3 % older than the "true" date on average. For individual grains, the former method can result in dates that are older by a few percent in most cases, and by as much as 12 % for grains with aspect ratios of up to 1:1. The revised alpha-ejection correction proposed here is both more accurate and more precise than the previous correction, and does not introduce any significant systematic bias into the apparent dates from a sample. [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]

We analyze point defect bulk and surface diffusion near the crystal–vacuum interface and show that bulk diffusion is coupled with surface diffusion via the atomic processes in the intermediate subsurface layer. A set of self-contained differential equations describing the interaction of self-interstitials and bulk vacancies with the surface of crystal is proposed. The results show the existence of the fundamental relation between the equilibrium concentrations of the point defects in bulk and at the surface of the crystal. For the case of silicon, the energy barrier differences that restrict the point defect fluxes between the bulk and surface of the crystal are estimated. [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]

KDP crystals constitute the only laser-frequency conversion and electro-optical switches that can be used in laser systems for inertial confinement fusion. However, KDP crystals are difficult to produce because of their inherent softness, brittleness, water-solubility, and temperature sensitivity. The authors' group developed a water-dissolution polishing method in previous studies to obtain near-damage-free KDP surfaces. In this article, the effect of the wetting characteristics of the water dissolution polishing fluid on the crystal surface—a factor rarely considered in the usual process optimization—on the polished surface quality was comprehensively studied. The mean radius of micro water droplets at 5 wt.% and 7.5 wt.% water content was approximately 0.6 nm and 1.2 nm, respectively. Theoretically, the smaller micro water droplet size is beneficial to the polished surface quality. When the water content was 5 wt.%, due to the poor wetting characteristics of the polishing fluid, surface scratches appeared on the polished surface; when the water content was 7.5 wt.%, the effects of the wetting characteristics and the radius of the micro water droplets reached a balance, and the polished surface quality was the best (Ra 1.260 nm). These results confirm that the wetting characteristics of the polishing fluid constitute one of the key factors that must be considered. This study proves that the wetting characteristics of the polishing fluid should be improved during the optimization process of polishing fluid composition when using oil-based polishing fluids for ultra-precision polishing. [ABSTRACT FROM AUTHOR]

In this paper, the molecular adsorption behavior and photoelectric properties of tungsten trioxide monohydrate (WO 3 ·H 2 O) (002) crystal plane into tungsten trioxide (WO 3) (002) crystal plane were studied by Density Functional Theory (DFT) and Electrochemical Impedance Spectrum (EIS). DFT simulation shows that the adsorption active sites change from two to one after the transformation of WO 3 ·H 2 O (002) crystal plane to WO 3 (002) crystal plane, which further affects the molecular adsorption behavior of the crystal plane. The crystal plane conversion leads to the decrease of the adsorption energy of water (H 2 O) molecules and the increase of the adsorption energy of oxygen (O 2) molecules, which reduces the adverse effect of water molecules on the gas sensing performance of the material and enhances the adsorption of O 2 molecules. Like O 2 molecules and H 2 O molecules, the adsorption of four kinds of organic molecules on two crystal planes will lead to an increase in the conductivity of the crystal plane. The competitive adsorption of organic molecules with O 2 molecules leads to the decrease of the conductivity of both crystal planes. However, acetone (C 2 H 6 CO) molecules are combined in the form of hydrogen bond on the WO 3 ·H 2 O (002) crystal plane, and the contribution to the increase of the conductivity of the crystal plane is significantly higher than that of O 2 molecules. After the conversion to the WO 3 (002) crystal plane, this hydrogen bond disappears. These results were confirmed by EIS test experiments. The UV-Vis diffuse reflectance absorption spectra and photocurrent spectra show that the band gap increases after the WO 3 ·H 2 O (002) crystal plane is converted into the WO 3 (002) crystal plane. Understanding the influence of crystal plane transformation on molecular adsorption behavior and photoelectric properties is of great significance for optimizing the gas sensing properties and regulating the photoelectric properties of materials. • Crystal transformation affects the surface adsorption and photoelectric properties. • Density functional theory is used to simulate the crystal plane molecular adsorption. • The change of the active sites affects the molecular adsorption behavior. • Different molecules have competitive adsorption at the same adsorption active site. • The adsorption of molecules will change the crystal surface conductivity. [ABSTRACT FROM AUTHOR]

We study avenues to shape multistability and shape morphing in flexible crystalline membranes of cylindrical topology, enabled by glide mobility of dislocations. Using computational modeling, we obtain states of mechanical equilibrium presenting a wide variety of tubular crystal deformation geometries, due to an interplay of effective defect interactions with out-of-tangent-plane deformations that reorient the tube axis. Importantly, this interplay often stabilizes defect configurations quite distinct from those predicted for a two-dimensional crystal confined to the surface of a rigid cylinder. We find that relative and absolute stability of competing states depend strongly on control parameters such as bending rigidity, applied stress, and spontaneous curvature. Using stable dislocation pair arrangements as building blocks, we demonstrate that targeted macroscopic three-dimensional conformations of thin crystalline tubes can be programmed by imposing certain sparse patterns of defects. Our findings reveal a broad design space for controllable and reconfigurable colloidal tube geometries, with potential relevance also to architected carbon nanotubes and microtubules. [ABSTRACT FROM AUTHOR]

Stannous oxide (SnO) is prepared by a sol–gel reaction, and the intermediate product is a white gel material, Sn6O4(OH)4, which is decomposed by a constant temperature heat treatment to form a regular black crystal, and the size reach 300 μm approximately. TG-DSC analysis shows that under air atmospheric conditions, SnO undergoes an oxidation and thermal decomposition reactions at 350 °C, which to form SnO2, Sn, and Sn3O4. With the temperature increasing, the reaction will continue and the final product will be SnO2. X-ray photoelectron spectroscopy (XPS) analysis shows that SnO is sensitive to oxygen. It is placed in air for about 2 months, and 81.8% of the crystal surface is oxidized to SnO2, but the inside of the crystal remains as SnO. Few layer crystal sheets was prepared by mechanical exfoliation with a thickness of 85 nm and a surface roughness of 1.02 nm, which provides a possibility for the application of few layers of SnO crystals to transparent and flexible electronic devices. [ABSTRACT FROM AUTHOR]

The self-sputtering yield of the (100) face-centered cubic crystal surface consisting of particles interacting with the Lennard–Jones (LJ) potential is presented as a function of the normalized incident particle kinetic energy for normal incidence. Because the self-sputtering yield depends only on the normalized incident energy, the yield curve presented here is the universal curve, independent of the Lennard–Jones parameters, and therefore serves as the fundamental reference data for the LJ system. The self-sputtering yield data are also compared with experimentally obtained self-sputtering yields of some metals, which shows reasonable agreement at relatively low ion incident energy where mostly deposition occurs. At higher ion energy, the self-sputtering of such an LJ material does not represent those of real solids. This is because the repulsive interactions of the LJ potential do not represent those of actual atoms at short distances. The angle dependence of the self-sputtering yield is also presented for some selected normalized energies. [ABSTRACT FROM AUTHOR]