•Symmetry breaking by the seed crystals can redirect growth toward hierarchy.•Branching may be triggered by the intrinsic electronic properties of nanoparticles.•Hierarchy can develop through coupled ...interfacial nucleation and assembly.
The development of structural hierarchy on various length scales during crystallization process is ubiquitous in biological systems and is also observed in synthetic nanomaterials. The driving forces for the formations of complex architectures range from local interfacial interactions, that modify interfacial speciation, local supersaturation, and nucleation barriers, to macroscopic interparticle forces. Although it is enticing to interpret the formation of hierarchical architectures as the assembly of independently nucleated building blocks, often crystallization pathways follow monomer-by-monomer addition with structural complexity arising from interfacial chemical coupling and strongly correlated fluctuation dynamics in the electric double layers. Here, the mechanism of the development of structural hierarchy through heterogeneous nucleation, coupled interfacial nucleation and assembly, and oriented attachment of independently nucleated particles is discussed. The emphasis is made on the discussion of the underlying interfacial forces and chemical coupling that drives crystallization pathways towards the formation of structural hierarchy.
•Single crystal silicon ribbons at M2-M6 can be made by the Floating Silicon Method.•A new type of crystal morphology called an “internal side effect” is described.•The crystal growth process is ...proposed in 3D via facet flow from a thin platelet.•The silicon wafers are lower in oxygen than Czochralski-derived material.
The Floating Silicon Method (FSM) has been established as a viable, stable method for growing single crystal ribbons directly from a silicon melt. With intense helium jet cooling to drive the linear progress of a 111 facet, pulled in the 〈110〉 direction, ribbons in the 0.6 – 3.0 mm thickness range can be grown at linear growth rates from 0.3 mm/s to >6 mm/s as reported in the literature. We report on recent progress towards growing (100) oriented ribbons with a net thickness of <200 µm and a ribbon width up to 18 cm using a stable, continuous process in the Leading Edge prototype furnace. The 3D details of the single crystal growth are explained using the mechanics of the Limit Cycle Theory, with novel Internal Side Effect morphology described by a proposed Facet Flow Theory. Grown-in crystalline defect distributions are described as well as values of critical impurities like oxygen, carbon, dopants, and metals that are relevant for use as wafers for solar cells.
This overview begins with observations of capillary-mediated effects on crystal-melt interfaces in microgravity and attempts to interpret them using the LeChâtelier–Braun effect and Kelvin’s ...equation—both local equilibrium requirements applicable at curved interfaces. Numerical studies of interfacial kinetics followed, using Greens function distributions that simulated evolving sharp solid–liquid interfaces undergoing pattern formation. Those methods exposed a need for more incisive steady-state techniques. Grain boundary grooves were used as constrained, stationary, microstructures. Their steady-state profiles derive from variational calculus and were analyzed for their imputed Gibbs–Thomson thermopotentials for comparative thermodynamic studies. Variational profiles, however, have unrealistic zero-thickness transitions between phases, and thus lack fluxes of energy or solute that occur on real interfaces. The exact formulation of variational profiles, however, advantageously supports field-theoretic calculations of their first-order formation free energy, thermodynamic stability, capillary-mediated chemical potentials, interfacial gradients and scalar divergences. These linked fields all depend on an interface’s curvature distribution, i.e., its geometry, but others, for example tangential fluxes of energy and solute, also depend on interface thickness and structure, i.e., thermodynamics. We comparatively analyzed capillary-mediated fields up to 4th-order, including the surface Laplacian of a profile’s chemical potential. This Laplacian is proportional to scaled divergences of fluxes that appear on counterpart real or simulated microstructures with congruent shapes. Divergent energy fluxes manifest as cooling distributions, which cause depression of the thermochemical potential measured along diffuse-interfaces simulated with phase-field. Cooling distributions are visualized to explain qualitative and quantitative features of a microstructure’s steady-state thermal maps. Evidence is included of how thickness and shape of crystal-melt interfaces co-determine whether, and to what extent, interfacial transport occurs. Understanding the origin and actions of interfacial capillary fields might offer improved control of microstructure at mesoscopic levels, accessible with these deterministic fields through physical and chemical means.
•Curvature-driven transport phenomena are analyzed for solid–liquid microstructures.•Surface-modulated thermocapillary effects are integrated with thermodynamic analyses.•Integration of disparate ideas advances crystal growth and interfacial thermodynamics.
Induction heating is crucial to various crystal growth techniques, including the Floating Zone (FZ) method, which is used for producing high-quality single silicon crystals. In this work, 3D and 2D ...axisymmetric numerical models for the high-frequency induction heating in the FZ process are implemented in open-source software tools Elmer and OpenFOAM. The models are compared and validated with in-situ measurements conducted on a model experiment of the FZ process, consisting of a flat inductor that heats a tin rod. The magnetic flux density distribution around the inductor is measured using a 3D induction coil probe, and the rod’s surface temperature is measured using an infrared camera. Both numerical models were found to be in good agreement with the experimental data, with deviations mainly due to geometric approximations and simplified thermal modeling. The present measurement setup can be used as a benchmark for other numerical models of high-frequency induction processes.
•New model experiment for induction heating in the FZ process developed.•Measurement of the 3D magnetic field vector performed with a novel induction coil probe.•Geometric imperfections of the inductor are visible in magnetic field measurements.•3D and 2D open-source models show good agreement with measurements.•Simple boundary condition for 2D modeling of complex 3D inductor shapes validated.
•Process informatics characteristics for crystal growth based on their differences with material informatics are discussed.•Applications of information science to crystal growth are ...reviewed.•Challenges and prospects informatics applications are discussed.
The application of information science and technology has led to a paradigm shift in scientific and technological research and crystal growth is no exception. Various types of application research have been conducted, and research methods that combine real experiments and simulations with information techniques are becoming increasingly complex. In this paper, I focus on the application of information science and technology to the field of crystal growth. In the first half, I discuss the characteristics of process informatics, including applications to crystal growth, from the perspective of how it differs from materials informatics. In the second half, by reviewing various application studies to crystal growth, I aim to highlight the characteristics and discuss future issues.
•The mechanism of microinclusion formation in Ti-sapphire crystals was studied.•The components of the medium oxidize Mo and W and reduce their condensed oxides•A mass transfer mechanism with the ...formation of Mo and W inclusions has been proposed.
The formation mechanism of micro-inclusions in titanium-sapphire crystals grown with the method of horizontal directional crystallization in a gas atmosphere was studied. It has been shown that the micro-inclusions of metallic tungsten and/or molybdenum are mainly formed at the surface of the unmelted charge. The thermodynamic analysis of the possible reactions of Mo and W among the charge components, the products of charge dissociation, and the components of the technological atmosphere was carried out. It is shown that CO2, CO, H2O, as well as suboxides of Al and Ti, can serve both as oxidizers of Mo and W and as reducing agents of their condensed oxides. The mechanism of mass transfer within which gaseous Mo and W oxides are reduced on the charge surface to form metal micro-particles was proposed. These particles further fall into the melt and then are transported with convective flows to the crystallization front and embedded into the crystal as micro-inclusions.
A new kinetic Monte Carlo simulation approach for crystal growth from solution is presented. The simulations include an explicit representation of an extended volume of solution above the crystal ...face and realistically treats voids within the forming crystal, step overhangs and concentration gradients in the mother solution. The effect of impurities on step growth is investigated and it is shown that the results depend on a complex interplay between concentration gradients in solution driven by the consumption of material during step growth, the lifetime of impurities on the crystal surface and the geometry of the steps.
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•A new kinetic Monte Carlo approach to the simulation of crystal growth from solution.•Application to step growth in the presence of impurities.•Discussion of effects of concentration gradients in the mother solution.•Discussion of effects of terrace size.•Discussion of effects of impurity adatom lifetime.
•Alternative escape route from the dead zone that does not involve an increase in supersaturation.•3D island formation via cluster merging can lead to less contaminated crystal ...surfaces.•Cluster-mediated crystal growth occurring in heterogeneous media effectively leads to stop-and-go dynamics.
Impurities control the formation of bio-crystals and can fully paralyze crystal growth at low levels of supersaturation. Traditional impurity models predict that an escape from this so-called “dead zone” requires an increase in the driving force (i.e. supersaturation). In this work, using protein crystals as a model system, we uncover an alternative escape route from the dead zone that does not involve an increase in supersaturation. We demonstrate that the merger of a protein cluster with the crystal surface triggers the formation of an ordered multi-layered island. The newly created surface on top of the resulting 3D island is initially devoid of impurities and therefore characterized by near-pure step growth kinetics. The accelerated step advancement on this relatively uncontaminated surface limits the available time for impurities to adsorb on the emerging terraces and by extension their resulting surface density. Cluster-mediated crystal growth occurring in heterogeneous media can therefore lead to stop-and-go dynamics, which offers a new model to explain crystallization taking place under biological control (e.g. biomineralization).
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•A synthesis method was structured that made it possible to obtain CuO-NPs in a controlled way.•The synthesized CuO-NPs showed good crystallization with a size of 72.87 nm and a ...spherical morphology.•The synthesized CuO-NPs showed good stability with a zeta potential of –32.51 mV.•The deposition of synthesized CuO-NPs on the wire surface has a significant impact on CHF enhancement.
There are several ways to synthesis nanoparticles, including chemical, physical, and biological processes. In general, chemical approaches are thought to be the most effective for producing uniformly sized and stable nanoparticles. This study deals with the synthesis and characterization of copper oxide nanoparticles (CuO-NPs) that could be used in pool boiling heat transfer in the form of nanofluid. The wet chemical synthesis method was used in order to prepare copper oxide nanoparticles (CuO-NPs) using precursor copper nitrate trihydrate (Cu(NO3)2⋅3H2O) and citric acid in a molar ratio of 5:1 in ethylene glycol (C2H6O2) solvent. The nanoparticles were identified using their stability, crystal size, and particle size. FTIR, XRD, and UV–Visible Spectroscopy all provide evidence that CuO-NPs exist. The typical nanoparticle size, as determined by Zetasizer, was 72.87 nm. The Scherrer formula was used to ascertain the average crystallite size of nanoparticles, which was determined to be approximately 19.82 nm. Positive findings from the stability test on nanoparticles were obtained, and their zeta potential was about –32.51 mV. According to morphological analyses by SEM, the synthesized CuO-NPs were made up of evenly dispersed spheroid-shaped particles that were agglomerated. The amount of reducing agent and calcination temperatures has a significant impact on the nanoparticle's size. The results of the experiment show that the addition of nanoparticles has a significant impact on the value of critical heat flux (CHF).
•To improve the bottom heat extraction by helium gas flow under the bottom retort.•The convexity of the melt crystal interface was maintained for the whole growth.•The impurity concentration of the ...grown mc-Si is not sufficient to form the LID effect and SiC formation.•The uniform temperature gradient and distributions are maintained by the helium gas flow under the retort.
The quality improvement of the mc-Si ingot is achieved by numerical simulation using the finite volume method. We have done the numerical simulation on a 2D symmetric Directional solidification furnace with helium gas flow at the bottom of the retort. In this process, the first nucleation starts at the bottom centre of the crucible due to spot cooling. The spot cooling process achieves the convex melt crystal interface during the growth process. It will push the impurity from the centre to the peripheral region of the ingot. This spot cooling method results show the acceptable range of the dislocation density and stress of the grown ingot. The melt-crystal interface, thermal stress, dislocation density and impurity formation of spot cooling system grown mc-Si have been analysed and compared with the conventional DS system of the grown mc-Si ingot. It is seen from the results that the LID effect, SiC formation and dislocation density are reduced in the spot cooling system grown mc-Si ingot.
