Growth kinetics of solid-liquid Ga interfaces: Part II. Theoretical

Peteves, S. D.; Abbaschian, R.

doi:10.1007/bf02660659

Cited by 89 publications

(80 citation statements)

References 60 publications

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“…8b. As a graphitic layer nucleates on the melt, it expands laterally and normally by 2D nucleation and faceted growth, in a manner similar to that observed for 2D nucleation and growth of faceted materials [37]. The Raman spectrum shown in Fig.…”

Section: Resultssupporting

confidence: 60%

Growth of graphene and graphite nanocrystals from a molten phase

et al. 2011

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We report on the development of a new technique for the growth of graphene and graphite nanocrystals from a metal-carbon melt. The process involves dissolving carbon inside molten nickel or copper at a specified temperature and then allowing the dissolved carbon to nucleate and grow on top of the melt at a lower temperature. The morphology of graphite forming inside nickel is shown to depend on the melt composition and cooling rate. The results indicate that the graphene layers contain a wrinkled structure due to thermal expansion coefficient mismatch between the grown layers and substrate. The graphene layers, however, preserve their continuity over these wrinkles. Although the formation of wrinkles was found not to depend on the type of metal substrate, the substrate had strong effect on the quality of grown layers. The films on copper contained quite a few defects including cracks and entrapped vacancies, whereas the films grown on nickel were pristine and defects free.

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Section: Resultssupporting

confidence: 60%

Growth of graphene and graphite nanocrystals from a molten phase

et al. 2011

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“…In the first case, it is considered that a new layer nucleates only when the previous layer has spread over the corresponding crystal facet, this is the so-called MNG (mono-layer growth) process [23]. Following Tiller [24], we can ask the question: "What is the radius of disk, R, of a crystal facet which has unit probability that a new nucleus will form on top of the disk in the time t that it takes to the original disk to grow to its maximal extension?"…”

Section: Growth Kineticsmentioning

confidence: 99%

“…The other alternative is the so-called PNG (poly-layer growth) mechanism [23] that is controlled by the growth rate and not by the nucleation rate. The growth rate G is now given as [17]:…”

Section: Growth Kineticsmentioning

confidence: 99%

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A 2-D nucleation-growth model of spheroidal graphite

2017

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a b s t r a c tAnalysis of recent experimental investigations, in particular by transmission electron microscopy, suggests spheroidal graphite grows by 2-D nucleation of new graphite layers at the outer surface of the nodules. These layers spread over the surface along the prismatic direction of graphite which is the energetically preferred growth direction of graphite when the apparent growth direction of the nodules is along the basal direction of graphite. 2-D nucleation-growth models first developed for precipitation of pure substances are then adapted to graphite growth from the liquid in spheroidal graphite cast irons. Lateral extension of the new graphite layers is controlled by carbon diffusion in the liquid. This allows describing quantitatively previous experimental results giving strong support to this approach. IntroductionGraphite spheroids in spheroidal graphite cast iron are known to consist of piling up of graphite layers having their c axis oriented parallel to the spheroid radius. To accommodate for the change in orientation in the tangential direction, the spheroids appear to be divided in adjacent sectors which are easily observed by optical microscopy as illustrated in Fig. 1. The change in orientation of the c axis at the boundary between two sectors may amount from 10 to several tens of degrees, while the orientation changes within sectors are more limited [1,2].It has long been recognized that graphite layers within spheroids are arranged in growth blocks which are elongated along the prismatic a direction of the graphite structure [3]. This would imply that graphite grows along the prismatic (tangential) direction during spheroidal growth even though the overall (apparent) growth direction is the radial one. Two types of models have been suggested in the past to account for this tangential growth: i) those based on screw dislocations [4] or cone-helix growth [5e7]; and ii) those based on the continuous growth of a graphite layer folding around the spheroid [8,9]. In the first type, tangential growth proceeds around screw dislocations or cones emanating from the spheroid's centre (Fig. 2-a), giving features that would agree with the observation of sectors. However, transmission electron microscopy (TEM) observations have shown that the orientation of the c axis along a sector tilts at random and in either ways [10] which implies that continuous growth around a screw dislocation did not occur. The second type of models (Fig. 2-b) would hardly explain the formation of sectors as already stressed by Gruzleski [9]. However, a slight modification where nucleation of new layers proceeds at the step between two neighbouring sectors which was suggested by Double and Hellawell [11] would (Fig. 2-c).There has been a renewed interest these last years for investigating the growth mechanism of spheroidal graphite [12e14]. Qing et al. [14] report observation of defects and dislocations in graphite, but do not seem to have observed long range ordered arrangements of these defects that would support the ...

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“…The site factor for a ledge is typically much larger than that for a surface since ledges are usually rough; 15 we thus take f l E 1. The number of molecules in a critical layer nucleus is small and we approximate i s * E 1.…”

confidence: 99%

Crystallization of undercooled liquid fenofibrate

Amstad

Spaepen

Weitz

2015

Phys. Chem. Chem. Phys.

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Formulation of hydrophobic drugs as amorphous materials is highly advantageous as this increases their solubility in water and therefore their bioavailability. However, many drugs have a high propensity to crystallize during production and storage, limiting the usefulness of amorphous drugs. We study the crystallization of undercooled liquid fenofibrate, a model hydrophobic drug. Nucleation is the ratelimiting step; once seeded with a fenofibrate crystal, the crystal rapidly grows by consuming the undercooled liquid fenofibrate. Crystal growth is limited by the incorporation of molecules into its surface. As nucleation and growth both entail incorporation of molecules into the surface, this process likely also limits the formation of nuclei and thus the crystallization of undercooled liquid fenofibrate, contributing to the good stability of undercooled liquid fenofibrate against crystallization.

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Growth kinetics of solid-liquid Ga interfaces: Part II. Theoretical

Cited by 89 publications

References 60 publications

Growth of graphene and graphite nanocrystals from a molten phase

Growth of graphene and graphite nanocrystals from a molten phase

A 2-D nucleation-growth model of spheroidal graphite

Crystallization of undercooled liquid fenofibrate

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