Growth Of Large Crystals Research Articles

Giant plagioclase in the Steens Basalt, southeast Oregon, USA: Tracking the balance of differentiation processes in continental flood basalt evolution

Giant plagioclase basalts (GPBs), flows that contain abundant and conspicuous plagioclase crystals ≥1 cm in length, exist at many continental flood basalt provinces, and their presence can provide a window into the crustal differentiation processes and storage conditions that produced the magmas prior to eruption. GPB flows occur in the Steens Basalt of southeast Oregon, USA, one of the earliest members of the Columbia River Flood Basalt Group, but their origin in this province has not been studied in detail. We conducted quantitative textural analysis utilizing crystal size distributions (CSDs) at the outcrop and thin section scale, as well as in situ plagioclase trace element and isotopic compositional analysis, in order to elucidate the processes responsible for generating two end-member textural types of GPB found in the Steens Basalt: daisy stone glomerocryst clusters composed of radiating plagioclase laths and single isolated plagioclase. CSD patterns suggest a changing balance of multiple differentiation processes affected the magmas that created each GPB textural type. In the daisy stone plagioclase, crystals rarely exhibit resorption textures, trace element abundances are comparatively low with minimal variability, and Sr isotopes are commonly in equilibrium with groundmass. In the single isolated plagioclase, resorption textures are common, trace element abundances are generally higher and display within crystal variation, and Sr isotopes are typically not in equilibrium with groundmass. These distinctive characteristics require separate mechanisms to generate each end-member GPB texture. Daisy stone GPBs form by growth of large crystals following mafic recharge events that completely resorb entrained cumulate plagioclase. A large amount of plagioclase may then grow with minimal cooling following recharge due to saturation in plagioclase components. In contrast, single isolated GPBs are the result of partial resorption of both entrained and resident plagioclase following less voluminous and less primitive recharge events; regrowth then occurs on the partially resorbed cores when cooling resumes. Both GPB types are formed by thermal cycling, but each texture reflects the differentiation processes that were prevalent during different eruptive stages of the Steens Basalt, as the balance between recharge, crystal fractionation, and assimilation varied in time.

Interfacial epitaxy of multilayer rhombohedral transition-metal dichalcogenide single crystals.

Rhombohedral-stacked transition-metal dichalcogenides (3R-TMDs), which are distinct from their hexagonal counterparts, exhibit higher carrier mobility, sliding ferroelectricity, and coherently enhanced nonlinear optical responses. However, surface epitaxial growth of large multilayer 3R-TMD single crystals is difficult. We report an interfacial epitaxy methodology for their growth of several compositions, including molybdenum disulfide (MoS2), molybdenum diselenide, tungsten disulfide, tungsten diselenide, niobium disulfide, niobium diselenide, and molybdenum sulfoselenide. Feeding of metals and chalcogens continuously to the interface between a single-crystal Ni substrate and grown layers ensured consistent 3R stacking sequence and controlled thickness from a few to 15,000 layers. Comprehensive characterizations confirmed the large-scale uniformity, high crystallinity, and phase purity of these films. The as-grown 3R-MoS2 exhibited room-temperature mobilities up to 155 and 190 square centimeters per volt second for bi- and trilayers, respectively. Optical difference frequency generation with thick 3R-MoS2 showed markedly enhanced nonlinear response under a quasi-phase matching condition (five orders of magnitude greater than monolayers).

Assembly of π-Conjugated [B3O6] Units by Mer-Isomer [YO3F3] Octahedra to Design a UV Nonlinear Optical Material, Cs2YB3O6F2.

Achieving the extreme balance of the key performance requirements is the crucial to breakthrough the application bottleneck for nonlinear optical (NLO) materials. Herein, by assembly of the π-conjugated [B3O6] functional species with the aid of structure-directing property of mer-isomer [YO3F3] octahedra, a new ultraviolet (UV) NLO material, Cs2YB3O6F2 with aligned arrangement of coplanar [B3O6] groups has been synthesized. The polar material exhibits the rare coexistence of the largest second harmonic generation response of 5.6×KDP, the largest birefringence of 0.091 at 532 nm, the shortest Type I phase-matching down to 200.5 nm and deep-ultraviolet transparency among reported acentric rare-earth borates with [B3O6] groups. Remarkably, benefiting from the enhanced bonding force among functional units [B3O6], a firm three-dimensional framework is constructed, which facilitates the growth of large crystals. This can be proved by a block shape crystal with dimensional of 6×5×4 mm3, indicating that it was a promising UV NLO crystal. This work provides a powerful strategy to design UV NLO materials with good performances.

Assembly of π‐Conjugated [B3O6] Units by Mer‐Isomer [YO3F3] Octahedra to Design a UV Nonlinear Optical Material, Cs2YB3O6F2

AbstractAchieving the extreme balance of the key performance requirements is the crucial to breakthrough the application bottleneck for nonlinear optical (NLO) materials. Herein, by assembly of the π‐conjugated [B3O6] functional species with the aid of structure‐directing property of mer‐isomer [YO3F3] octahedra, a new ultraviolet (UV) NLO material, Cs2YB3O6F2 with aligned arrangement of coplanar [B3O6] groups has been synthesized. The polar material exhibits the rare coexistence of the largest second harmonic generation response of 5.6×KDP, the largest birefringence of 0.091 at 532 nm, the shortest Type I phase‐matching down to 200.5 nm and deep‐ultraviolet transparency among reported acentric rare‐earth borates with [B3O6] groups. Remarkably, benefiting from the enhanced bonding force among functional units [B3O6], a firm three‐dimensional framework is constructed, which facilitates the growth of large crystals. This can be proved by a block shape crystal with dimensional of 6×5×4 mm3, indicating that it was a promising UV NLO crystal. This work provides a powerful strategy to design UV NLO materials with good performances.

Crystal growth of the [formula omitted]PdSi3 ([formula omitted] rare earth) materials using the optical floating zone technique

The rare-earth palladium silicides host an array of complex magnetic phases. In this paper, we report the growth of large single crystals of the R2PdSi3 family, (where R= Ce, Nd, Gd, Tb, Ho and Er) by the floating zone technique using a high-power xenon arc-lamp furnace. The crystal boules obtained have been examined for their quality using x-ray diffraction techniques, elemental analysis, and their magnetic properties have been investigated through temperature dependent magnetisation measurements.

Growth of large norsethite crystals in aqueous ammonium nitrate solutions

Crystallization of norsethite [BaMg(CO3)2] receives considerable attention as a key for solving geological problems, and environmental and resource issues. Noresthite is poorly soluble in water, and is synthesized via witherite [BaCO3] by solution-mediated transformation. In contrast, owing to the difficulties such as tremendous growth time and consideration of multi-step reactions, the shape and size of norsethite were not satisfactory for further investigations so far. Here we tried to increase the solubility of the crystals to overcome these difficulties of the growth by adding NH4NO3. The solubilities of norsethite and witherite in the presence of NH4NO3 were ∼35 and ∼45 times higher than those in the absence of NH4NO3, respectively. At 90 °C, the growth rate of norsethite in NH4NO3 solutions was ∼17 times higher than that in NH4NO3-free solutions, and norsethite in NH4NO3 solutions nucleated immediately after mixing the raw materials. Finally, we succeeded in synthesizing bulky norsethite crystals of 170 μm size only in one month, utilizing 0.1–1 M NH4NO3 solutions of 90 °C. We could explain the appearance of large norsethite, considering that norsethite dominantly consumes the solute by adding NH4NO3 compared with witherite. The findings provide a breakthrough in the growth technique of double carbonates.

Balanced anchoring sites and volatile matter in biochar render Ni/biochar with higher metal dispersion and superior activity in hydrogenation of vanillin

Metal/carbon catalysts could be prepared via simple calcination of biochar impregnated with salt of metal precursors. Abundance of oxygen-containing functionalities on biochar affects dispersion of nickel via influencing availability of anchoring sites for nickel ions in impregnation step. Biochar with high content of volatile matter tended to have more oxygen-containing species, but the volatiles released in calcination of Ni/biochar could experience secondary condensation, forming carbonaceous deposit and covering nickel sites. Therefore, the balanced distribution of oxygen-containing functionalities and volatile matter in biochar on dispersion of nickel were investigated via preparation of Ni/biochar catalysts with biochar support obtained at varied pyrolysis temperature (200, 300, 400 and 500 °C). The results indicated that the calcination of Ni/biochar-200 with biochar produced via pyrolysis at 200 °C encapsulated nickel from the deposit of secondary condensation of the volatiles, while the lack of abundance of O-containing species of biochar-400 and biochar-500 led to the growth of nickel species large crystals in their supported catalysts. In comparison, Ni/biochar-300 showed the highest dispersion of nickel and thus the highest activity for hydrogenation of vanillin to produce 2-methoxy-4-methylphenol (yield: 89.4%). The in-situ IR characterization of functionalities of biochar versus temperature and residence time indicated that the pyrolysis at 300 °C enhanced formation of –OH groups, the main anchoring sites of nickel ions. Nonetheless, abundant C = O at 400 °C and developed aromatic ring structures at 500 °C were not effective for dispersion of nickel species.

Development of continuous solution growth method for growth of large and high-quality perovskite single crystals

Large perovskite single crystals with high quality cannot be obtained by traditional batch-type solution growth techniques, impeding their use in commercial applications. We report on developing a continuous solution growth (CSG) method that enables the growth of large, high-quality perovskite single crystals such as methylammonium lead tribromide (MAPbBr3), as well as triple-cation mixed hybrid. A 40 × 40 × 2 mm3 MAPbBr3 single crystal grown by this method, has a high mobility-lifetime (µτ) product of 3.3 × 10−3 cm2·V−1 and a low trap density of 8.22 ± 0.02 × 108 cm−3. Photoconductors (Au-MAPbBr3-Au) with a low dark current density of 3.9nA·cm−2 at 0.83 V·mm−1 exhibit excellent photons detection of both UV–visible and X-ray photons. For UV–visible photons, the responsivity is about 1.5 A·W−1 and 1.3 A·W−1 to 405 nm and 532 nm photons, respectively; for X-ray sensitivity is up to 2.35 × 105 µC Gyair−1 cm−2 and the lowest detection limit is 15.7 nGyair·s−1. High-contrast X-ray images were obtained with a large (40 mm × 40 mm) pixelated detector with 800 µm × 800 µm pixels. These results demonstrate that the CSG technique can produce high-quality, large perovskite single crystals for commercial applications, including photodetection and ionization radiation detection.

Direct observation for relative-humidity-dependent mixing states of submicron particles containing organic surfactants and inorganic salts

Abstract. Aerosol mixing state plays an important role in heterogeneous reactions and cloud condensation nuclei (CCN) activity. Organic surfactants could affect aerosol mixing state through bulk–surface partitioning. However, the mixing state of surfactant-containing particles remains unclear due to the lack of direct measurements. Here, direct characterizations of the mixing state for 20 kinds of submicron particles containing inorganic salts (NaCl and (NH4)2SO4) and atmospheric organic surfactants (organosulfates, organosulfonates, and dicarboxylic acids) were conducted upon relative humidity (RH) cycling by environmental scanning electron microscopy (ESEM). As the RH increased, the surfactant shells inhibited water diffusion being exposed to the inorganic core, leading to notably increased inorganic deliquescence RH (88.3 %–99.5 %) when compared with pure inorganic aerosol. Meanwhile, we directly observed an obvious Ostwald ripening process (that is, the growth of larger crystals at the expense of smaller ones) in 6 out of 10 NaCl–organic surfactant systems. As a result of water inhibition by the organic surfactant shell, Ostwald ripening in all systems occurred at RH above 90 %, which were higher than the reported RH range for pure NaCl measured at 27 ∘C (75 %–77 %). As RH decreased, eight systems underwent liquid–liquid-phase separation (LLPS) before efflorescence, showing a strong dependence on the organic molecular oxygen-to-carbon ratio (O:C). Quantitatively, LLPS was always observed when O:C≤0.43 and was never observed when O:C>∼0.57. Separation RH (SRH) of inorganic salt–organic surfactant mixtures generally followed the trend of (NH4)2SO4 < NaCl, which is consistent with their salting-out efficiencies reported in previous studies. Solid-phase separations were observed after efflorescence for systems without LLPS. Our results provide a unique insight into the consecutive mixing processes of the inorganic salt–organic surfactant particles, which would help improve our fundamental knowledge of model development on radiative effect.

Single selenium atom to control nucleic acid conformation and large crystal growth

Single selenium atom to control nucleic acid conformation and large crystal growth

Ultra-thin silver films grown by sputtering with a soft ion beam-treated intermediate layer

Silver thin films have wide-ranging applications in optical coatings and optoelectronic devices. However, their poor wettability to substrates such as glass often leads to an island growth mode, known as the Volmer–Weber mode. This study demonstrates a method that utilizes a low-energy ion beam (IB) treatment in conjunction with magnetron sputtering to fabricate continuous silver films as thin as 6 nm. A single-beam ion source generates low-energy soft ions to establish a nominal 1 nm seed silver layer, which significantly enhances the wettability of the subsequently deposited silver films, resulting in a continuous film of approximately 6 nm with a resistivity as low as 11.4 µΩ.cm. The transmittance spectra of these films were found to be comparable to simulated results, and the standard 100-grid tape test showed a marked improvement in adhesion to glass compared to silver films sputter-deposited without the IB treatment. High-resolution scanning electron microscopy images of the early growth stage indicate that the IB treatment promotes nucleation, while films without the IB treatment tend to form isolated islands. X-ray diffraction patterns indicate that the (111) crystallization is suppressed by the soft IB treatment, while growth of large crystals with (200) orientation is strengthened. This method is a promising approach for the fabrication of silver thin films with improved properties for use in optical coatings and optoelectronics.

Traversing the nucleation-growth landscape through heterogeneous random walks.

The nucleation-growth process is a crucial component of crystallization. While previous theoretical models have focused on nucleation events and postnucleation growth, such as the classical nucleation theory and Lifshitz-Slyozov-Wagner model, recent advancements in experiments and simulations have highlighted the inability of classical models to explain the transient dynamics during the early development of nanocrystals. To address these shortcomings, we present a model that describes the nucleation-growth dynamics of individual nanocrystals as a series of reversible chain reactions, with the free energy landscape extended to include activation-adsorption-relaxation reaction pathways. By using the Monte Carlo method based on the transition state theory, we simulate the crystallization dynamics. We derive a Fokker-Planck formalism from the master equation to describe the nucleation-growth process as a heterogeneous random walk on the extended free energy landscape with activated states. Our results reveal the transient quasiequilibrium of the prenucleation stage before nucleation starts, and we identify a postnucleation crossover regime where the dynamic growth exponents asymptotically converge towards classical limits. Additionally, we generalize the power laws to address the dimension and scale effects for the growth of large crystals.

Experimental study on visualization of TBAB hydrate formation in confined small channels

Hydrate crystals' microscopic characteristics and agglomerating morphologies play an important role in the hydrate reaction equipment's flow assurance and heat transfer. In order to study the formation process of hydrate, experimental quartz tubes with small diameters were selected, and a fully visualized flow loop system was established. The study investigated the effects of supercooling, solution concentration, tube diameter, and flow rate on hydrate blockage time and agglomeration morphology. The results show that under the same supercooling conditions, the density of single crystal hydrate formed in 10 wt%-20 wt% TBAB (Tetra-n-butylammonium bromide) hydrate solution is low, and the crystal front appears needle-like or sword-like, which is conducive to mass and heat transfer. High concentration TBAB solution(30 wt%-40 wt%) can form dense hydrate crystals, and the tip effect was significantly weakened. For low concentration TBAB solution, the increased flow rate can accelerate the formation of new nuclei and inhibit the growth of large crystals. Grout solutions with different particle sizes can be obtained by adjusting the flow rate. It was found that the initial morphology of TBAB hydrate crystals included spherical and cylindrical shapes, and the morphological evolution process of a single hydrate crystal was similar. Finally, a microscopic physical model of the TBAB hydrate growth and aggregation process was established.

Optimizing HVPE flow field to achieve GaN crystal uniform growth

In the process of large size GaN crystal growth by hydride vapor phase epitaxy (HVPE), whether the parameters of reactants or the structure of the reactor are changed, the crystal growth is affected by the flow rate and concentration of reactants at different positions in the reactor, namely the flow field in the reactor. Therefore, the crystal quality is very sensitive to the flow field distribution in the reaction chamber. In this paper, the simulation software COMSOL Multiphysics is used to simulate the flow field in the horizontal HVPE reaction chamber. The results show that gravity has an important influence on the uniformity of GaCl and NH3 concentrations on the substrate surface. The method of improving the concentration uniformity of GaCl and NH3 on the substrate surface by changing the different dip angles of the substrate was studied, and the substrate dip angles corresponding to the optimum uniformity of GaCl and NH3 flow fields in HVPE system were obtained. The results were applied to the actual growth, and 2 inch GaN crystals with uniform growth thickness were obtained.

Growth and characterization of large centimetre-size levoglucosan single crystals

Levoglucosan is a typical orientationally disordered crystalline material (the molecules are long-range positionally ordered but orientationally disordered). At present, experimental research on its glass transition is mainly focused on polycrystals, while the study of the corresponding single crystals is rarely reported. Centimetre-size (maximum dimensions of 2.1 × 0.9 × 0.4 cm) levoglucosan single crystals of high quality were grown by the solution method, laying a necessary foundation for experimental measurements of the glass transition mechanism in the material.

A novel two-step route to unidirectional growth of multilayer MoS2 nanoribbons

Alkali-assisted chemical vapour deposition (CVD) of transition metal dichalcogenides (TMDs) has been shown to promote the growth of large single crystals of TMD monolayers. The morphology control of TMDs is a key parameter for the scalable synthesis of versatile layered materials. This work demonstrates that the alkali-assisted synthesis provides a route toward fabricating highly crystalline MoS2 nanoribbons. Our proposed method involves a vapour-liquid–solid phase reaction between MoOx(2 < x < 3) precursors grown by Pulsed Laser Deposition (PLD) and metal alkali halide (i.e., NaF). The growth process evolves via the emergence of the Na–Mo–O liquid phase, which mediates the formation of MoS2 multilayer nanoribbons in a sulfur-rich environment. Moreover, the as-grown MoS2 nanoribbons are surrounded by mono- and multilayer triangles of MoS2 and exhibit a preferential alignment defined by both MoS2 crystal symmetry and the underlying Al2O3 substrate. In addition, we observe a significant built-in strain in the as-grown MoS2 nanostructures, which increase in magnitude from the multilayer nanoribbons to the triangular monolayers, and which can be effectively released upon transfer onto another substrate. The growth method developed here can enable flexibility in designing nanoelectronic devices based on TMDs with tunable dimensions.

Absolute Configuration Determination of Chiral API Molecules by MicroED Analysis of Cocrystal Powders Formed Based on Cocrystal Propensity Prediction Calculations.

Establishing the absolute configuration of chiral active pharmaceutical ingredients (APIs) is of great importance. Single crystal X-ray diffraction (scXRD) has traditionally been the method of choice for such analysis, but scXRD requires the growth of large crystals, which can be challenging. Here, we present a method for determining absolute configuration that does not rely on the growth of large crystals. By examining microcrystals formed with chiral probes (small chiral compounds such as amino acids), absolute configuration can be unambiguously determined by microcrystal electron diffraction (MicroED). Our streamlined method employs three steps: (1) virtual screening to identify promising chiral probes, (2) experimental cocrystal screening and (3) structure determination by MicroED and absolute configuration assignment. We successfully applied this method to analyze two chiral API molecules currently on the market for which scXRD was not used to determine absolute configuration.

Comparative study on the microstructure, mechanical properties and fracture mechanism of wire arc additive manufactured Inconel 718 alloy under the assistance of alternating magnetic field

In this study, the microstructure, mechanical properties and fracture mechanism of wire arc additive manufactured Inconel 718 alloy fabricated by cold metal transfer process under the action of the alternating magnetic field (AMF) are studied by changing the excitation current. The results show that the AMF deflects the droplet and changes the direction of the molten pool maximum temperature gradient, which inhibits the growth of large columnar crystals and refines the grains so that the index of {100}<001> texture decreases significantly. The microstructure of the 0 A and 40 A samples is composed of γ(Ni) + (TiN) [nucleus]/(NbC + TiC)[shell] + NbC + Laves. The length of γʹʹ-Ni3Nb of the 0 A sample (98 nm) is greater than that of the 40 A sample (84 nm). The AMF suppresses the large columnar crystals, and the average grain size is reduced to 161 μm. The volume fraction of the Laves phases is significantly reduced from 2.4% to 1.3%, and the Laves phases morphology changes from long stripe to granular under the action of the AMF. AMF increases the ultimate tensile strength and decreases the anisotropy.

Preparation of large Cu3Sn single crystal by Czochralski method

Cu3Sn was recently predicted to host topological Dirac fermions, but related research is still in its infancy. The growth of large and high-quality Cu3Sn single crystals is, therefore, highly desired to investigate the possible topological properties. In this work, we report the single crystal growth of Cu3Sn by Czochralski (CZ) method. Crystal structure, chemical composition, and transport properties of Cu3Sn single crystals were analyzed to verify the crystal quality. Notably, compared to the mm-sized crystals from a molten Sn flux, the cm-sized crystals obtained by the CZ method are free from contamination from flux materials, paving the way for the follow-up works.

Solubility Measurements of NaTaO3 in Molten Na2MO4 (M = Mo, W, and S) and Growth of Milli-Order Crystals at High Frequency.

Sodium tantalate (NaTaO3) is an attractive functional material for photocatalysis. To understand its physical properties, significant efforts for milli-sized single-crystal growth of NaTaO3 have been made. However, the growth was difficult due to the smaller size in solid-state growth or probable decomposition and melting in melt growth. Recently, we grew milli-order NaTaO3 single crystals in Na2MoO4 flux. However, the reproducibility of the growth was not sufficient and hindered the stable supply of the crystal for physicochemical evaluations and further growth. The poor reproducibility was assumed to be due to the inhomogeneous, unstable growth field in response to the external atmosphere provided by nonoptimal experimental conditions. A saturated solution is considered the most suitable crystal growth field because it has the highest solubility and facilitates crystal growth with suppressed nucleation. Since supersaturation is the driving force for crystal growth, we considered that large crystals could be obtained with high frequency if growth could be controlled in the region where solubility changes rapidly. To compile a guideline for crystal growth under the control of supersaturation, the solubility of NaTaO3 in Na-based fluxes, including Na2MoO4, was studied. Using NaTaO3 molding pellets immersed in molten flux, the solubility curve for NaTaO3 was successfully measured. Based on the solubility, the optimal experimental conditions, that is, the heating temperature, the slow-cooling section, and the amount of flux as a solvent, were determined. Finally, we demonstrated the growth of NaTaO3 in Na2MoO4 flux and achieved milli-order crystals with high frequency. Our findings regarding the solubility of NaTaO3 in molten flux may assist in the stable supply of milli-order single crystals for material evaluation and larger crystal growth.