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Showing papers on "Nucleation published in 2005"


Journal ArticleDOI
TL;DR: A method for growing vertical ZnO nanowire arrays on arbitrary substrates using either gas-phase or solution-phase approaches is presented and the nanorod arrays made in solution have a rod diameter, length, density, and orientation desirable for use in ordered Nanorod-polymer solar cells.
Abstract: A method for growing vertical ZnO nanowire arrays on arbitrary substrates using either gas-phase or solution-phase approaches is presented. A ∼10 nm-thick layer of textured ZnO nanocrystals with their c axes normal to the substrate is formed by the decomposition of zinc acetate at 200−350 °C to provide nucleation sites for vertical nanowire growth. The nanorod arrays made in solution have a rod diameter, length, density, and orientation desirable for use in ordered nanorod−polymer solar cells.

1,437 citations


Journal ArticleDOI
TL;DR: In this paper, a double-moment bulk microphysics scheme predicting the number concentrations and mixing ratios of four hydrometeor species (droplets, cloud ice, rain, snow) is described.
Abstract: A new double-moment bulk microphysics scheme predicting the number concentrations and mixing ratios of four hydrometeor species (droplets, cloud ice, rain, snow) is described. New physically based parameterizations are developed for simulating homogeneous and heterogeneous ice nucleation, droplet activation, and the spectral index (width) of the droplet size spectra. Two versions of the scheme are described: one for application in high-resolution cloud models and the other for simulating grid-scale cloudiness in larger-scale models. The versions differ in their treatment of the supersaturation field and droplet nucleation. For the high-resolution approach, droplet nucleation is calculated from Kohler theory applied to a distribution of aerosol that activates at a given supersaturation. The resolved supersaturation field and condensation/deposition rates are predicted using a semianalytic approximation to the three-phase (vapor, ice, liquid) supersaturation equation. For the large-scale version of the scheme, it is assumed that the supersaturation field is not resolved and thus droplet activation is parameterized as a function of the vertical velocity and diabatic cooling rate. The vertical velocity includes a subgrid component that is parameterized in terms of the eddy diffusivity and mixing length. Droplet condensation is calculated using a quasi-steady, saturation adjustment approach. Evaporation/deposition onto the other water species is given by nonsteady vapor diffusion allowing excess vapor density relative to ice saturation.

913 citations


Book
01 Jan 2005
TL;DR: In this paper, the authors present a model for diffusion in non-crystalline materials based on the Diffusion Equation, and a model of diffusion in Cerystals.
Abstract: Preface. Bibliography. Acknowldegments. Notation. Symbol Table-Roman. Symbol Table-Greek. 1. Introduction. PART I: MOTION OF ATOMS AND MOLECULES BY DIFFUSION. 2. Irreversible Thermodynamics: Coupled Forces and Fluxes. 3. Driving Forces and Fluxes for Diffusion. 4. The Diffusion Equation. 5. Solutions to the Diffusion Equation. 6. Diffusion In Multi-Component Systems. 7. Atomic Models for Diffusion. 8. Diffusion in Cerystals. 9. Diffusion Along Crystal Imperfections. 10. Diffusion in Noncrystalline Materials. PART II: MOTION OF DISLOCATIONS AND INTERFACES. 11. Motion of Dislocations. 12. Motion of Crystalline Surfaces. 13. Motion of Crystalline Interfaces. PART III MORPHOLOGICAL EVOLUTION DUE TO CAPILLARY AND APPLIED MECHANICAL FORCES. 14. Surface Evolution due to Capillary Forces. 15. Coarsening due to Capillary Forces. 16. Morphological Evolution, Diffusional Creep, and Sintering. PART IV: PHASE TRANSFORMATIONS. 17. General Features of Phase Transformations. 18. Spinodal and Order-Disorder Transformations. 19. Nucleation. 20. Growth of Phases in Concentration and Thermal Fields. 21. Concurrent Nucleation and Growth. 22. Solidification. 23. Precipitation. 24. Martensitic Transformations. Appendix A: Densities, Fractions, and Atomic Volumes of Components. Appendix B: Structure of Crystalline Interfaces. Appendix C: Capillarity and Mathematics of Space Curves and Interfaces. Illustration Credits. Cited Author Index. Figure Index. Topic Index.

633 citations


Journal Article
TL;DR: In this paper, a simple route to the production of high-quality CdE (E = S, Se, Te) semiconductor nanocrystallites is presented, based on pyrolysis of organometallic reagents by injection into a hot coordinating solvent.
Abstract: A simple route to the production of high-quality CdE (E = S, Se, Te) semiconductor nanocrystallites is presented. Crystallites from ∼ 12 A to ∼ 115 A in diameter with consistent crystal structure, surface derivatization, and a bigh degree of monodispersity are prepared in a single reaction. The synthesis is based on the pyrolysis of organometallic reagents by injection into a hot coordinating solvent. This provides temporally discrete nucleation and permits controlled growth of macroscopic quantities of nanocrystallites. Size selective precipitation of crystallites from portions of the growth solution isolates samples with narrow size distributions (<5% rms in diameter). High sample quality results in sharp absorption features and strong "band-edge" emission which is tunable with particle size and choice of material. Transmission electron microscopy and X-ray powder diffraction in combination with computer simulations indicate the presence of bulk structural properties in crystallites as small as 20 A in diameter.

597 citations


Journal ArticleDOI
TL;DR: The analysis indicates that the nucleation rate of OCP is substantially higher than that of HA, while HA is most thermodynamically stable in SBF, while DCPD precipitation is the most likely because of its highest nucleation rates among Ca-P phases.

508 citations


Journal ArticleDOI
TL;DR: In this article, the authors obtained quasi-static, two-dimensional solutions for earthquake nucleation on faults obeying Dieterich's "aging" version of the rate and state friction equations.
Abstract: We obtain quasi-static, two-dimensional solutions for earthquake nucleation on faults obeying Dieterich's “aging” version of the rate and state friction equations. Two distinct nucleation regimes are found, separated by roughly a/b ∼ 0.5, where a and b are the constitutive parameters relating changes in slip rate V and state θ to frictional strength. When fault healing is unimportant (Vθ/D_c ≫ 1, where D_c is the characteristic slip distance for the evolution of θ), the nucleation zone spontaneously evolves toward a state of accelerating slip on a patch of fixed half length L_ν ≈ 1.3774(μ′D_c /bσ), where μ′ is the intrinsic stiffness of the medium and σ is the normal stress. This is the fixed length solution for which the stress intensity factor K = 0. Although this solution does not depend upon a/b explicitly, only for a/b < 0.3781 does healing remain unimportant as instability is approached. For a/b ≳ 0.5 and a wide range of slow loading conditions, Vθ/D_c ultimately approaches a quasi-constant value near 1, and the nucleation zone takes on the appearance of an expanding slip-weakening crack. A fracture energy balance indicates that in this regime the nucleation length asymptotically approaches π−1[b/(b − a)]2(μ′D_c /bσ), a result that is consistent with the numerical simulations despite considerable complexity asa approaches b. This suggests that nucleation lengths can sometimes be much larger than those found by Dieterich (e.g., by a factor of 100 for a/b = 0.95). For surfaces this close to velocity neutral, nucleation might produce signals detectable by surface seismometers for values of D_c at the upper end of the lab range (100 μm). However, the attributes of the aging law that give rise to such large nucleation lengths may be nonphysical; additional laboratory experiments are needed to address this issue.

453 citations


Journal ArticleDOI
TL;DR: The entire range of observed spherulite morphologies can be reproduced by this generalized phase field model of polycrystalline growth, which describes and explores three physically prevalent sources of disorder that lead to this kind of growth.
Abstract: Many structural materials (metal alloys, polymers, minerals, etc.) are formed by quenching liquids into crystalline solids. This highly nonequilibrium process often leads to polycrystalline growth patterns that are broadly termed "spherulites" because of their large-scale average spherical shape. Despite the prevalence and practical importance of spherulite formation, only rather qualitative concepts of this phenomenon exist. It is established that phase field methods naturally account for diffusional instabilities that are responsible for dendritic single-crystal growth. However, a generalization of this model is required to describe spherulitic growth patterns, and in the present paper we propose a minimal model of this fundamental crystal growth process. Our calculations indicate that the diversity of spherulitic growth morphologies arises from a competition between the ordering effect of discrete local crystallographic symmetries and the randomization of the local crystallographic orientation that accompanies crystal grain nucleation at the growth front [growth front nucleation (GFN)]. This randomization in the orientation accounts for the isotropy of spherulitic growth at large length scales and long times. In practice, many mechanisms can give rise to GFN, and the present work describes and explores three physically prevalent sources of disorder that lead to this kind of growth. While previous phase field modeling elucidated two of these mechanisms--disorder created by particulate impurities or other static disorder or by the dynamic heterogeneities that spontaneously form in supercooled liquids (even pure ones)--the present paper considers an additional mechanism, crystalline branching induced by a misorientation-dependent grain boundary energy, which can significantly affect spherulite morphology. We find the entire range of observed spherulite morphologies can be reproduced by this generalized phase field model of polycrystalline growth.

449 citations


Journal ArticleDOI
01 Dec 2005-Small
TL;DR: The quintessence of the hot-injection method, a synthesis route for monodisperse, highly luminescent semiconductor nanocrystals, is reviewed and the numerous adaptations of the original synthesis that currently provide colloidal nanocry crystals with well-defined, size-dependent optical, electrical, and magnetic properties are reviewed.
Abstract: The quintessence of the hot-injection method, a synthesis route for monodisperse, highly luminescent semiconductor nanocrystals, is reviewed. The separate stages of nucleation and growth of the nanocrystals are discussed in the framework of classical nucleation theory and an equilibrium model proposed by Debye. We also review the numerous adaptations of the original synthesis that currently provide colloidal nanocrystals with well-defined, size-dependent optical, electrical, and magnetic properties. The availability of these remarkable materials is one of the most promising developments in nanoscience and nanotechnology.

447 citations


Journal ArticleDOI
TL;DR: In this paper, the nucleation and growth during Al2O3 atomic layer deposition (ALD) were explored on a variety of polymer films at 85 °C, using sequential exposures of Al(CH3)3 [trimethylalumi...
Abstract: Nucleation and growth during Al2O3 atomic layer deposition (ALD) were explored on a variety of polymer films at 85 °C. Al2O3 ALD was performed using sequential exposures of Al(CH3)3 [trimethylalumi...

396 citations


Journal ArticleDOI
TL;DR: The development and application of high-temperature nanoindentation testing, and the introduction of statistical methods to quantitatively evaluate data, suggest an unexpected picture of incipient plasticity that involves heterogeneous nucleation sites, and which has not been anticipated by atomistic simulations.
Abstract: Nanoindentation has become ubiquitous for the measurement of mechanical properties at ever-decreasing scales of interest, including some studies that have explored the atomic-level origins of plasticity in perfect crystals. With substantial guidance from atomistic simulations, the onset of plasticity during nanoindentation is now widely believed to be associated with homogeneous dislocation nucleation. However, to date there has been no compelling quantitative experimental support for the atomic-scale mechanisms predicted by atomistic simulations. Our purpose here is to significantly advance the quantitative potential of nanoindentation experiments for the study of dislocation nucleation. This is accomplished through the development and application of high-temperature nanoindentation testing, and the introduction of statistical methods to quantitatively evaluate data. The combined use of these techniques suggests an unexpected picture of incipient plasticity that involves heterogeneous nucleation sites, and which has not been anticipated by atomistic simulations.

392 citations


Journal ArticleDOI
TL;DR: A survey of the state of the art on homogeneous and heterogeneous nucleation can be found in this paper, where the authors survey the state-of-the-art on the underlying mechanisms of nucleation in the troposphere.
Abstract: Ice in the troposphere affects a variety of processes, including the formation of precipitation, and cloud lifetime, albedo, dynamics, and electrification. A lack of understanding of the ways in which ice is created and multiplied hampers progress in understanding all of these processes. We survey the state of knowledge, starting with homogeneous nucleation, where current formulations for freezing from both pure water and solutions have considerable predictive power. However, debate still exists on the underlying mechanisms of nucleation. Using the concepts and framework that homogeneous nucleation provides, heterogeneous nucleation, where neither a commonly agreed upon theory nor even standard measurement technique exists, is considered. Investigators have established the ice-nucleating characteristics of broad classes of substances, such as mineral dust and soot, which are important ice nuclei in t he atmosphere, but a coherent theory of why these substances act as they do has yet to emerge. All ice in ...

Journal ArticleDOI
TL;DR: In this paper, a formulation of the Gibbs-Thomson equation is proposed and different approximation solutions of this equation found in the literature are discussed, based on simple thermodynamics considerations, and different approximations are discussed.

Journal ArticleDOI
TL;DR: In this article, the effect of ultrasonic vibration on the nucleation and growth of aluminum alloy A356 melt was evaluated and it was shown that cavitations-induced heterogeneous nucleation plays a more important role than dendrite fragmentation in the formation of globular grains.

Journal ArticleDOI
TL;DR: In this article, a thermochemical study of the temperature effects on the Zn-Cl-H 2 O system by means of potential-pH, solubility and species repartition diagrams is presented with the view to better understand the effect of temperature on the deposition mechanism and composition of zinc oxide thin films.

Journal ArticleDOI
12 Aug 2005-Science
TL;DR: In this article, the authors use a most unexpected strategy for forming large single crystals such as those that make up mineralized skeletal parts, which allows organisms to mold the crystals into unusual shapes and orient them at will.
Abstract: Many organisms use a most unexpected strategy for forming large single crystals such as those that make up mineralized skeletal parts. Although nucleation and growth of a crystal occur from a solid disordered phase that has the characteristics of a melt phase, the process is accomplished at ambient temperatures and pressures. This strategy allows organisms to mold the crystals into unusual shapes and orient them at will.

Journal ArticleDOI
15 Feb 2005-Langmuir
TL;DR: A diffusion-limited growth model is developed to theoretically explain the observed d(f)(V) behavior and quantitatively retrieve the measured amplitude and exponent and can therefore predict and generate in the room temperature range, monodisperse particles of a targeted size by simply adjusting the rate of addition.
Abstract: Control over the synthesis of monodisperse silica particles up to mesoscopic scale is generally made difficult due to intrinsic limitation to submicrometric dimensions and secondary nucleation in seeded experiments. To investigate this issue and overcome these difficulties, we have implemented single step processing by quantifying the effects of the progressive addition of a diluted tetraethyl orthosilicate solution in ethanol on the size and monodispersity of silica particles. Contrary to particles grown in seeded polymerization, monodisperse particles with size up to 2 μm were synthesized. Moreover, the particles exhibit a final diameter (df), which varies with V-1/3 over more than 2 orders of magnitude in rate of addition (V). On the basis of a kinetic study in the presence of addition showing that particle growth is limited by the diffusion of monomer species, we developed a diffusion-limited growth model to theoretically explain the observed df(V) behavior and quantitatively retrieve the measured amp...

Journal ArticleDOI
TL;DR: Simulations of the transformation between a gel and a fluid phase in dipalmitoyl-phosphatidylcholine bilayers using a coarse grained (CG) model show that the nature of the ordered phase obtained with the CG model is indeed a gel rather than a crystalline phase.

Journal ArticleDOI
TL;DR: In this article, the state-of-the-art in understanding the mechanism of eutectic nucleation and growth in Al-Si alloys, inspecting samples, both quenched and uninterrupted, on the macro, micro and nano-scale.
Abstract: Recent increasing applications for cast Al–Si alloys are particularly driven by the need for lightweighting components in the automotive sector. To improve mechanical properties, elements such as strontium, sodium and antimony can be added to modify the eutectic silicon from coarse and plate-like to fine and fibrous morphology. It is only recently being noticed that the morphological transformation resulting from eutectic modification is also accompanied by other, equally significant, but often unexpected changes. These changes can include a 10-fold increase in the eutectic grain size, redistribution of low-melting point phases and porosity as well as surface finish, consequently leading to variations in casting quality. This paper shows the state-of-the-art in understanding the mechanism of eutectic nucleation and growth in Al–Si alloys, inspecting samples, both quenched and uninterrupted, on the macro, micro and nano-scale. It shows that significant variations in eutectic nucleation and growth dynamics occur in Al–Si alloys as a function of the type and amount of modifier elements added. The key role of AlP particles in nucleating silicon is demonstrated.

Journal ArticleDOI
TL;DR: In this article, the authors studied the kinetics of crystal nucleation of an undercooled Lennard-Jones liquid using various path-sampling methods and obtained the rate constant and elucidate the pathways for crystal nucleations, in which critical solid nuclei can be small, compact and face centered cubic, but also large, less ordered, and more body centered cubic.
Abstract: We study the kinetics of crystal nucleation of an undercooled Lennard-Jones liquid using various path-sampling methods. We obtain the rate constant and elucidate the pathways for crystal nucleation. Analysis of the path ensemble reveals that crystal nucleation occurs along many different pathways, in which critical solid nuclei can be small, compact, and face centered cubic, but also large, less ordered, and more body centered cubic. The reaction coordinate thus includes, besides the cluster size, also the quality of the crystal structure.

Journal ArticleDOI
TL;DR: In this article, isothermal and non-isothermal crystallization kinetics of polypropylene (PP)/surface-treated SiO 2 nanocomposites were extensively studied, and the effective energy barrier was estimated as a function of the relative degree of crystallinity using the isoconversional analysis of calorimetric data.

Journal ArticleDOI
TL;DR: The lag time as well as the rate of aggregation were found to depend on peptide concentration and addition or formation of seeds, implying that the nucleation event is under influence of a stochastic factor that can manifest itself in profound macroscopic differences in the aggregation kinetics of otherwise indistinguishable samples.
Abstract: We report here a recombinant expression system that allows production of large quantities of Alzheimer’s Aβ(1–40) peptide. The material is competent to dissolve in water solutions with “random-coil properties,” although its conformation and factual oligomerization state are determined by the physico-chemical solution conditions. When dissolved in 50 mM sodium phosphate buffer (pH 7.4) at 37°C, the peptide is able to undergo a nucleated polymerization reaction. The aggregation profile is characteristically bipartite, consisting of lag and growth phase. From these curves we determined the lag time as well as the rate of aggregation. Both values were found to depend on peptide concentration and addition or formation of seeds. Moreover, they can vary considerably between apparently identical samples. These data imply that the nucleation event is under influence of a stochastic factor that can manifest itself in profound macroscopic differences in the aggregation kinetics of otherwise indistinguishable samples.

Journal ArticleDOI
TL;DR: This work shows that mineral dissolution can be understood through the same mechanistic theory of nucleation developed for mineral growth, and reveals that the “salt effect,” recognized almost 100 years ago, arises from a crossover in dominant nucleation mechanism to greatly increase step density.
Abstract: The central control of mineral weathering rates on biogeochemical systems has motivated studies of dissolution for more than 50 years. A complete physical picture that explains widely observed variations in dissolution behavior is lacking, and some data show apparent serious inconsistencies that cannot be explained by the largely empirical kinetic “laws.” Here, we show that mineral dissolution can, in fact, be understood through the same mechanistic theory of nucleation developed for mineral growth. In principle, this theory should describe dissolution but has never been tested. By generalizing nucleation rate equations to include dissolution, we arrive at a model that predicts how quartz dissolution processes change with undersaturation from step retreat, to defect-driven and homogeneous etch pit formation. This finding reveals that the “salt effect,” recognized almost 100 years ago, arises from a crossover in dominant nucleation mechanism to greatly increase step density. The theory also explains the dissolution kinetics of major weathering aluminosilicates, kaolinite and K-feldspar. In doing so, it provides a sensible origin of discrepancies reported for the dependence of kaolinite dissolution and growth rates on saturation state by invoking a temperature-activated transition in the nucleation process. Although dissolution by nucleation processes was previously unknown for oxides or silicates, our mechanism-based findings are consistent with recent observations of dissolution (i.e., demineralization) in biological minerals. Nucleation theory may be the missing link to unifying mineral growth and dissolution into a mechanistic and quantitative framework across the continuum of driving force.

Journal ArticleDOI
Tao He1, Dairong Chen1, Xiuling Jiao1, Yingling Wang1, Yongzheng Duan1 
TL;DR: In this paper, a liquid phase redox process was designed to prepare monodispersed Co3O4 nanocrystals with particle sizes of 2 nm (spherical), 2.5 nm (cubelike), and 4.7 nm (closest to ours).
Abstract: A liquid-phase redox process has been designed to prepare monodispersed Co3O4 nanocrystals with particle sizes of 2 nm (spherical), 2.5 nm (cubelike), and 4.7 nm (cubelike). The nanocrystals were characterized by transmission electron microscopy (TEM), high-resolution TEM, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric techniques. The nucleation and growth, which were tracked by UV−visible spectroscopy, can be separated by adjusting the solubility of sodium nitrate, and the smallest possible Co3O4 nanocubes, 2.5 nm on a side, were obtained. A solubility-controlled mechanism for the redox reaction is discussed which is critical in avoiding secondary nucleation and interparticle ripening growth of Co3O4 nanocrystals.

Journal Article
TL;DR: In this article, a review of the nucleation, crystallization, thermal properties and morphology of diblock and triblock copolymers with one or two crystallizable components is presented.
Abstract: Crystallization of block copolymer microdomains can have a tremendous influence on the morphology, properties and applications of these materials. In this review, particular emphasis is placed on the nucleation, crystallization, thermal properties and morphology of diblock and triblock copolymers with one or two crystallizable components. The issues of the different types of nucleation processes (i.e., homogeneous nucleation and heterogeneous nucleation by different types of heterogeneities and surface nucleation) and their relation to the crystallization kinetics of the components is addressed in detail in a wide range of polymeric materials for droplet dispersions, blends and block copolymers. The case of AB double crystalline diblock copolymers is discussed in the light of recent works on biodegradable systems, while the nucleation, crystallization and morphology of more complex materials like ABC triblock copolymers with one or two crystallizable components are thoroughly reviewed.

Journal ArticleDOI
TL;DR: In this article, the formation and growth mechanisms of transcrystallinity layers in semi-crystalline polymer composites were reviewed, as well as the factors that affect TC layers, and the influences of TC on the interfaces of fiber/polymer and the properties of composites.

Journal ArticleDOI
TL;DR: The evolution in the understanding of the recrystallization phenomena is summarized in this article, where the main developments concerning recrestallization are presented from a historical perspective, as well as definitions and concepts involving recrasing are presented regarding it as a solid-state reaction that occurs by nucleation and growth.
Abstract: The evolution in the understanding of the recrystallization phenomena is summarized in this paper. Initially the main developments concerning recrystallization are presented from a historical perspective. Definitions and concepts involving recrystallization are presented regarding it as a solid-state reaction that occurs by nucleation and growth. The recrystallization nucleation mechanisms are subsequently discussed. Finally, the growth step is highlighted, emphasizing boundary and sub-boundary mobilities and the forces acting on the high angle grain boundaries that sweep the microstructure during recrystallization.

Journal ArticleDOI
TL;DR: In this article, a GLObal Model of Aerosol Processes (GLOMAP) was developed as an extension to the TOMCAT 3-D Eulerian off-line chemical transport model.
Abstract: . A GLObal Model of Aerosol Processes (GLOMAP) has been developed as an extension to the TOMCAT 3-D Eulerian off-line chemical transport model. GLOMAP simulates the evolution of the global aerosol size distribution using a sectional two-moment scheme and includes the processes of aerosol nucleation, condensation, growth, coagulation, wet and dry deposition and cloud processing. We describe the results of a global simulation of sulfuric acid and sea spray aerosol. The model captures features of the aerosol size distribution that are well established from observations in the marine boundary layer and free troposphere. Modelled condensation nuclei (CN>3nm) vary between about 250–500 cm-3 in remote marine boundary layer regions and are generally in good agreement with observations. Modelled continental CN concentrations are lower than observed, which may be due to lack of some primary aerosol sources or the neglect of nucleation mechanisms other than binary homogeneous nucleation of sulfuric acid-water particles. Remote marine CN concentrations increase to around 2000–10 000 cm

Journal ArticleDOI
TL;DR: The kinetics and mode of nucleation and growth of fibers by 5α-cholestan-3β-yl N-(2-naphthyl)carbamate (CNC), a low-molecular mass organogelator (LMOG), in n-octane and n-dodecane have been investigated as their sols were transformed isothermally to organogels as discussed by the authors.
Abstract: The kinetics and mode of nucleation and growth of fibers by 5α-cholestan-3β-yl N-(2-naphthyl)carbamate (CNC), a low-molecular-mass organogelator (LMOG), in n-octane and n-dodecane have been investigated as their sols were transformed isothermally to organogels. The kinetics has been followed in detail by circular dichroism, fluorescence, small-angle neutron scattering, and rheological methods. When treated according to Avrami theory, kinetic data from the four methods are self-consistent and describe a gelation process involving one-dimensional growth and “instantaneous nucleation”. As expected from this growth model, polarized optical micrographs of the self-assembled fibrillar networks (SAFINs) show fibrous aggregates. However, their size and appearance change abruptly from spherulitic to rodlike as temperature is increased. This morphological change is attended by corresponding excursions in static and kinetic CD, fluorescence and rheological data. Furthermore, the rheological measurements reveal an un...

Journal ArticleDOI
TL;DR: In this paper, the influence of phase-change material composition on amorphous phase stability, crystallization rate, nucleation probability, optical constants and media noise is reported for materials with a growth dominated crystallization mechanism.
Abstract: The influence of phase-change material composition on amorphous phase stability, crystallization rate, nucleation probability, optical constants and media noise is reported for materials with a growth dominated crystallization mechanism. Two material classes have been studied, doped Sb–Te and doped Sb-based compositions. The material properties of both are greatly influenced by their composition, and in a similar way. For both materials systems hold that the antimony content especially influences the crystallization rate, amorphous phase stability and media noise of the phase-change material. Compositions rich in antimony generally show high crystallization rates, low archival life stability and high media noise. The material properties are further influenced by the presence of dopants like tellurium, germanium, gallium, indium or tin. Germanium and tellurium reduce the crystallization rate, but are essential to increase the amorphous phase stability. Dopants like tin or indium are added to increase the c...

Journal ArticleDOI
TL;DR: Cavitation bubbles appear to be important during the fragmentation process, possibly melting any ice crystals in their path, and Flow patterns around cavitation bubbles have also been observed, and these may be responsible for the fragmentation of ice crystals.