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Crystallization processes of amorphous germanium–tin (GeSn) under low-energy electron-beam irradiation were examined using transmission electron microscopy (TEM). Freestanding amorphous GeSn thin films were irradiated with a 100 keV electron beam at room temperature. The amorphous GeSn was athermally crystallized by electron-beam irradiation, when the electron flux exceeded the critical value. Heterogeneous structures consisting of nano- and micro-crystallites were formed after crystallization of amorphous GeSn with ∼24 at. % Sn in the as-sputtered amorphous state. In situ TEM observations of structural changes under electron-beam irradiation revealed that random nucleation and growth of nanocrystallites occur at the early stage of crystallization, followed by rapid formation of micro-grains surrounding the nanocrystals. It has been suggested that the growth of micro-grains progresses via supercooled liquid Sn at the amorphous/crystalline interface. The resultant GeSn grains with a size of a few micrometers contained ∼15 at. % Sn, much larger than the solubility limit of Sn in Ge (∼1 at. % Sn). [ABSTRACT FROM AUTHOR]

[Display omitted] • Anthracene-appended poly(ʟ-lactide)s (AAP) were synthesized by ROP of ʟ-lactide. • The excimer emission was observed in the low molecular weight AAP. • The monomeric emission is observed in amorphous and single crystals of AAP. • In crystallized AAP, fluorescence arises from anthracene excimers and monomers. • In the gel state AAP (e form), only the excimer emission was observed. The design and development of solid-state excimer-emitters bear great potential for attaining efficient solid-state luminescent materials. In this study, we have synthesized anthracene-appended poly(ʟ-lactide)s (AAPs) to regulate the arrangement of anthracene moieties by controlling the crystallization and polymorphic form of covalently linked poly(ʟ-lactide) (PLLA). In the high molecular weight AAP, the fluorescence intensity mainly arises from the monomeric anthracene moieties, whereas in the low molecular weight AAP, the excimer emission was observed depending on the structure and morphology of covalently-linked PLLA. The monomeric emission is predominantly observed in amorphous polymer due to the molecular level dispersion of covalently-linked anthracene moieties throughout the polymer matrix. When the polymer was crystallized under different conditions, covalently-linked anthracene moieties were excluded from polymer crystals or crystalline lamellae and are located on the surface or at the interface, which is advantageous for regulating the geometry of anthracene moieties. In the case of single crystals of PLLA, covalently-linked anthracene moieties assemble on the surface and emit mainly in their monomeric state due to the lack of π-stacking. In the melt-crystallized sample (α form), covalently-linked anthracene moieties reside at the interface of crystalline and amorphous domains by either dipolar interactions or π-stacking and fluorescence arising from anthracene excimers and monomers. In the gel state (ε form), only the excimer emission was observed due to the effective interactions between the anthracene moieties in the presence of excess solvent in the amorphous domains. In this way, polymer crystallization played a significant role in determining the arrangement of covalently-linked anthracene moieties in AAP. This study reveals the role of polymer crystallization on the excimer evolution in fluorophore-appended semicrystalline polymers and provides new insight into the design and development of fluorophore-appended polymers for optoelectronic devices. [ABSTRACT FROM AUTHOR]

Solid-phase epitaxy (SPE) and other three-dimensional epitaxial crystallization processes pose challenging structural and chemical characterization problems. The concentration of defects, the spatial distribution of elastic strain, and the chemical state of ions each vary with nanoscale characteristic length scales and depend sensitively on the gas environment and elastic boundary conditions during growth. The lateral or three-dimensional propagation of crystalline interfaces in SPE has nanoscale or submicrometer characteristic distances during typical crystallization times. An in situ synchrotron hard x-ray instrument allows these features to be studied during deposition and crystallization using diffraction, resonant scattering, nanobeam and coherent diffraction imaging, and reflectivity. The instrument incorporates a compact deposition system allowing the use of short-working-distance x-ray focusing optics. Layers are deposited using radio-frequency magnetron sputtering and evaporation sources. The deposition system provides control of the gas atmosphere and sample temperature. The sample is positioned using a stable mechanical design to minimize vibration and drift and employs precise translation stages to enable nanobeam experiments. Results of in situ x-ray characterization of the amorphous thin film deposition process for a SrTiO3/BaTiO3 multilayer illustrate implementation of this instrument. [ABSTRACT FROM AUTHOR]

[Display omitted] • The crystallization process of amorphous YAG oxide is investigated from an atomic point of view. • The crystallization proceeds on the surface and interior of the amorphous YAG separately, and which show the preferential crystallization of the surface atoms. • Some atoms in the amorphous phase were controlled by the periodic potential field of the crystal atoms and produced dynamically changing semi-ordered structures at the amorphous/crystalline interface with mainly concentrated within 1–2 nm from the interface. The transformation from amorphous materials to crystals and the corresponding microscopic mechanism have become a research focus in materials science, condensed matter physics, and biophysics etc. In this paper, taking Y 3 Al 5 O 12 (YAG) as an example, the crystallization process of amorphous YAG oxide is investigated from an atomic point of view through the combination of spherical aberration-corrected transmission electron microscopy (SCTEM) with an in situ heating method, and the morphology and structural evolution of the surface and interface are explored. It is observed that the crystallization proceeds on the surface and interior of the amorphous YAG separately. Through atomic-scale imaging, it is determined that semi-ordered structures are formed in a few atomic layers at the amorphous/crystalline interface and that the structural transformation process from the amorphous to the semi-ordered state and then to the crystal structure may be the main reason for the multiple stages of the crystallization of amorphous oxides. This study demonstrates the mechanism of the amorphous-to-crystal transformation on the atomic scale and contributes to gaining a better understanding of the crystallization process of bulk oxides, especially complex metal oxides. [ABSTRACT FROM AUTHOR]

We present the results of molecular dynamics simulations of the crystal nucleation rate in a supercooled Lennard-Jones liquid. The nucleation rate as a function of the pressure has been calculated by the method of determining the expectation time for liquid crystallization at temperatures higher than that of the triple point (T*=0.865), close to the temperature of the terminal critical point of the metastable extension of the melting curve (T*=0.55) and below this temperature (T*=0.4). In computer experiments the nucleation rate varied from 1032 to 1035 s-1 m-3. The dimensions of critical nuclei and the pressure inside them, the surface free energy at a critical crystal nucleus-liquid interface, the height of the nucleation barrier, and the Zeldovich factor have been determined from the results of molecular dynamics simulations and their comparison with classical homogeneous nucleation theory. It is shown that the surface free energy at a curved crystal-liquid interface, as distinct from a flat interface, has also been determined at temperatures lower than the temperature of the terminal critical point of the melting curve and is a monotonically increasing function of the temperature. [ABSTRACT FROM AUTHOR]

Presents information on a study which developed a theory of behavior of foreign solid inclusions in a liquid being crystallized. Methodology of the study; Results and discussion on the study; Conclusions.

Presents a study which examined thermal and diffusion-induced stresses in crystalline solids. Description of the preliminary relation of thermodynamics; Components of the total strain; Details of numerical calculations for the directional crystallization method.

Analyzing the orientation of polymeric crystalline lamella at the surface of thin films can be challenging. Even though atomic force microscopy (AFM) is often sufficient for this analysis, there are cases when imaging is not sufficient to confidently determine lamellar orientation. Here, we used sum frequency generation (SFG) spectroscopy to analyze the lamellar orientation at the surface of semi-crystalline isotactic polystyrene (iPS) thin films. The SFG orientation analysis indicated that the iPS chains are oriented perpendicular to the substrate (flat-on lamellar orientation), which was confirmed by AFM. By analyzing the evolution of the SFG spectral features with the progress of crystallization, we demonstrated that the ratios of the SFG intensities of the phenyl ring resonances are a good indication of the surface crystallinity. Furthermore, we explored the challenges associated with SFG measurements of heterogeneous surfaces, which is commonly present in many semi-crystalline polymeric films. To the best of our knowledge, this is the first time that the surface lamellar orientation of semi-crystalline polymeric thin films was determined by SFG. Also, this work pioneers in reporting the surface conformation of semi-crystalline and amorphous iPS thin films by SFG and in linking the SFG intensity ratios to the progress of the crystallization and the surface crystallinity. This study demonstrates the potential applicability of SFG spectroscopy in the conformational analysis of polymeric crystalline structures at interfaces and opens the way to the investigation of more complex polymeric structures and crystalline arrangements, especially for the case of buried interfaces, where AFM imaging is not an option. [Display omitted] • Surface lamellar orientation of polymer thin films determined by SFG. • Surface of semi-crystalline iPS thin films is dominated by flat-on crystals. • SFG intensity ratios are directly linked to the surface crystallinity. • Higher level of backbone ordering in semi-crystalline films than in amorphous films. [ABSTRACT FROM AUTHOR]

We reversibly controlled phase conversion between a microdroplet of a NaClO3 unsaturated aqueous solution and a metastable single crystal, which is usually a short-lived phase in spontaneous crystallization, simply by irradiating a tightly focused visible continuous-wave (CW) laser to the microdroplet. The laser irradiation allowed the metastable crystal to generate and stably grow without a polymorphic transformation. This successful metastable phase control is attributed to the combination of the advantage of optical trapping-induced nucleation that nucleation takes place from unsaturated mother solution and the advantage of microdroplet method, which suppresses additional nucleation leading to the transformation. In situ observation shows the crystal dissolves when the laser irradiation is stopped, whereas the laser irradiation stabilizes the crystal even if the size of the crystal becomes larger than that of focal spot. These observations indicate that a change in the relative magnitudes of chemical potentials between solution/crystalline phases. This change is possibly promoted via crystal growth by trapping of crystalline clusters in optical potential well formed on a crystal surfaces originating from “light propagation” through the crystal. Our results shed a light not only on polymorph control but also on a method to prepare a longer-lived achiral precursor for analysis on achiral–chiral transition by “freezing” a kinetic pathway of chiral crystallization. [ABSTRACT FROM AUTHOR]

The aim of this review is to summarize studies conducted by temperature-modulated differential scanning calorimetry (TMDSC) on polymer crystallization. This technique can provide several advantages for the analysis of polymers with respect to conventional differential scanning calorimetry. Crystallizations conducted by TMDSC in different experimental conditions are analysed and discussed, in order to illustrate the type of information that can be deduced. Isothermal and non-isothermal crystallizations upon heating and cooling are examined separately, together with the relevant mathematical treatments that allow the evolution of the crystalline, mobile amorphous and rigid amorphous fractions to be determined. The phenomena of 'reversing' and 'reversible' melting are explicated through the analysis of the thermal response of various semi-crystalline polymers to temperature modulation. [ABSTRACT FROM AUTHOR]

In the present paper, crystallization behavior and glass forming ability (GFA) of Cu64Zr36 bulk metallic glass (BMG) were studied based on the crystal phase competition. Electrical resistivity and X-ray diffraction results indicate that Cu64Zr36 glass underwent a two-stage crystallization process, during which Cu10Zr7 and Cu51Zr14 crystals precipitate at first and then there are only Cu10Zr7 and Cu8Zr3 phases at the end of the second stage. Intriguingly, it was found that it is the competing phase Cu10Zr7 that weakens GFA of the Cu64Zr36 alloy, because the Cu10Zr7 precipitate is fully restrained in the cast rod when substituting Zr with 7.5at%Ti and thereby its diameter with fully amorphous structure is enlarged from 1 mm to 2 mm. [ABSTRACT FROM AUTHOR]

Abstract: Poly(epsilon-caprolactone) (PCL) nanocomposites containing carbon nanotubes, layered silicates, sepiolite or polyhedral oligomeric silsesquioxane (POSS) were characterized by advanced thermal analysis. Adding carbon nanotubes or layered silicates increases the excess heat capacity in quasi-isothermal crystallization experiments by MTDSC, pointing to an increased fraction of reversibly melting and crystallizing material. In situ AFM during isothermal crystallization and SAXS during subsequent heating reveal an altered PCL semi-crystalline morphology. The nucleating ability of the carbon nanotubes induces a striking transcrystalline morphology, promoting the growth of secondary PCL crystals with an increased fold surface energy and a reduced melting temperature. The altered crystalline-amorphous interphase at the crystal fold surface houses the material that reversibly crystallizes and melts under quasi-isothermal crystallization conditions. A fraction of this interphase is not able to crystallize but converts into glassy, rigid amorphous material upon cooling prior to reaching the PCL main glass transition temperature. Low aspect ratio sepiolite and POSS nanofillers barely nucleate the PCL crystallization and therefore hardly affect the PCL semi-crystalline morphology and thermal behavior. [Copyright &y& Elsevier]

Abstract: The influences of solvent solubility and solution aging on the crystallization of poly(3-hexylthiophene) (P3HT) films were investigated. The solubility difference rather than the evaporation rate of solvent determined the final morphology and crystallinity of film. Marginal solvents (toluene and xylene) with large solubility difference caused crystalline aggregations in solutions during the aging process and then densely stacked network-like structures in solid films. Few crystalline aggregates in good solvent chloroform resulted in a thin layer of fibrillar crystals on the substrate, while dot-like crystals deposited on the substrate from good solvent chlorobenzene since no crystalline aggregates formed in the solution. [Copyright &y& Elsevier]

3,4,5-Trimethoxy N-(salicylidene) aniline was synthesized and characterized by IR spectroscopy, ¹H NMR and x-ray single crystal analysis. UV-visible spectroscopy was used for physicochemical tests. X-ray data reveals that the crystalline network cohesion of this compound is essentially assured by CH/pi type hydrogen bounds. It crystallized in the orthorhombic Pbcn space group. Electronic spectroscopy shows that the title compound doesn't present photochromic property but thermochromic one. Intermolecular interactions analysis confirms for this compound a thermochromic structural predisposition. [ABSTRACT FROM AUTHOR]

Abstract: A study of the epitaxial growth of InP on SrTiO3(001) (STO) substrates is presented. Reflection high energy electron diffraction (RHEED) and X-ray diffraction experiments evidence the strong influence of STO surface reconstruction on the InP crystalline orientation. When grown on unreconstructed (001) STO surfaces, the InP lattice has its [111] direction perpendicular to the growth plane. When grown on (2×1) reconstructed STO surfaces, InP is (001) oriented on the (001) STO substrate. In both cases, at least one [110] InP in-plane direction is aligned to one of the [100] STO direction. [Copyright &y& Elsevier]

Deformation-induced crystallization is correlated with thermal-induced crystallization in alloys with different compositions in a single amorphous alloy system. In Al87Y6Ni5Co2 and Al85Y8Ni5Co2 alloys, which undergo primary crystallization during heating, deformation-induced crystallization of fcc-Al has been observed. In Al83Y10Ni5Co2 alloy, which undergoes eutectic-like crystallization, no deformation-induced crystallization was observed. These observations can be explained by the presence or absence of quenched-in nuclei and the work required for the creation of an amorphous/crystalline interface under compressive stress. [ABSTRACT FROM AUTHOR]

Abstract: The structure of the crystalline–amorphous interface of poly(R-3-hydroxybutyrate) (PHB) of different molar mass is evaluated by analysis of the rigid amorphous fraction and by analysis of the degree of reversible melting and crystallization. The rigid amorphous fraction of low-molar-mass PHB of 5kDa is only 5–10%, and at best half of that of high-molar-mass PHB of almost 500kDa, despite identical crystallinity. This result is paralleled by observation of distinctly larger degree of reversible melting and crystallization in PHB of high molar mass. The larger rigid amorphous fraction and higher degree of reversible melting and crystallization in PHB of high molar mass, consistently and independently, prove enhanced covalent coupling of crystals and amorphous structure, and/or de-coupling of segments of macromolecules which traverse between phases, respectively. The distinct isolation of crystals in PHB of low molar mass is discussed in terms of absence of wide loops/folds, long-chain cilia, and tie-molecules. [Copyright &y& Elsevier]

It was well known that the defects in the polymer chains could significantly influence the crystallization process of semi-crystalline polymers. In this work, the role of defect distribution in the melt memory effects was studied by comparatively investigating a pair of Ziegler-Natta and metallocene-made isotactic polypropylene (ZN-iPP and M-iPP) fraction specimens with the same total defect content which were obtained from two raw parent samples through the solvent extraction. The characterization results of melting behaviors, polymorphic structures, and the successive self-nucleation and annealing analysis demonstrated that these two fractions exhibited the different distribution of defects, i.e. , the defect distribution in the M-iPP specimen was random while that in the ZN-iPP specimen was nonstatistical. The results of self-nucleation (SN) experiments indicated that the M-iPP exhibited much wider temperature range of Domain II than the ZN-iPP with similar total defect content, which indicated that the M-iPP showed a much stronger melt memory effect. Considering the effect of the microstructure on the crystallization behavior and the sequences containing defects could be excluded from the crystalline regions during the formation of crystal, we speculated that the random distributed defects in M-iPP could form a continuous interface between the crystalline regions and amorphous phase which could cause a heterogeneous melt and strengthen the melt memory effect. [Display omitted] • Defect distribution influenced the melt memory effect of iPP. • The defect in M-iPP was random while that was nonstatistical in ZN-iPP. • The M-iPP with random distributed defects exhibited stronger melt memory effect. [ABSTRACT FROM AUTHOR]

Abstract: Transitions from one microphase separated structure in the solid state to a different one in the molten state in polyethylene-graft-poly(ethylene oxide) copolymers, PE-g-PEO, were investigated by variable temperature X-ray scattering measurements and thermal analyses. Small-angle X-ray scattering patterns from polymers with PEO grafts with 25, 50 and 100 ethylene oxide (EO) units show that the polymer passes through three distinct structures at ∼10nm length scales with increase in temperature (T): lamellar structures of PE and PEO at T < T m PEO, PE lamellae surrounded by molten PEO at T m PEO < T < T m PE, and microphase separated structures at T > T m PE when both PE and PEO are molten (T m refers to the melting temperature). These phase transformations also occur during cooling but with hysteresis. Crystalline phases of PEO side chains and PE main chains could be identified in the wide-angle X-ray diffraction profiles indicating that the PE backbone and PEO grafts crystallize into separate domains, especially with longer grafted chains (50 and 100 units). At EO segment lengths>50, PEO shows the expected increase in melting and crystallization temperatures with the increase in the grafted chain length. PE does not affect T m PEO but does decrease the onset of crystallization upon cooling. PEO grafts result in fractionation of PE, decrease the melting point of PE and increase the undercooling for the onset of crystallization of PE. [Copyright &y& Elsevier]

Abstract: The phase composition of ultra-high molecular weight polyethylene of two different molecular weights has been estimated using Raman spectroscopy. Materials have then been irradiated in air to give a received doses of 3.5 and 10Mrad, and crystallinity change with time has been monitored by differential scanning calorimetry (DSC), wide and small angle X-ray diffraction (WAX and SAX) and Raman spectroscopy. Analysis by DSC and X-ray diffraction involved melting and re-crystallisation. Raman spectroscopy demonstrated that the material consists of three phases, fully crystalline, fully amorphous and an intermediate all-trans non-crystalline phase. Following irradiation the mass fraction of this latter phase reduces as total crystal content increases. SAX results indicate a refinement of the original lamellae and the emergence of a population of smaller crystals. It is thought that the all-trans material exists as an interfacial phase and that scission within this phase facilitates the observed crystal changes. [Copyright &y& Elsevier]

Polycrystalline silicon obtained by the crystallization of thin amorphous silicon films has been an important material for microelectronics technology during the last decades. Many properties are improved in crystallized amorphous silicon compared to the as-deposited polysilicon such as larger grain size, smoother surface, and higher-carrier mobility. In this work, the crystallization of amorphous silicon is investigated by combining transmission electron microscopy (TEM) observations and molecular dynamics calculations. TEM observations on a series of specimens have shown that the majority of the silicon grains are oriented with a $$ {\left\langle {110} \right\rangle} $$ zone axis normal to the surface. In order to understand the crystallization mechanism molecular dynamic simulations were performed. It is found that the $$ {\left\langle {110} \right\rangle} $$ c/amorphous interface exhibits the lowest reduced interfacial energy density while the $$ {\left\langle {111} \right\rangle} $$ c/amorphous has the lowest reduced energy differences per unit interfacial area. The most energetically unfavorable interface is $$ {\left\langle {001} \right\rangle} $$ c/amorphous. [ABSTRACT FROM AUTHOR]

Abstract: The chemical potential of a curved interface contains a term that is proportional to the product of the interface curvature and the interface stiffness. In crystalline materials, the interface stiffness is a tensor. This paper examines several basic issues related to the properties of the interface stiffness, especially the determination of the interface stiffness in particular directions (i.e. the commonly used scalar form of the interface stiffness). Of the five parameters that describe an arbitrary grain boundary, only those describing the inclination are crucial for the scalar stiffness. We also examine the influence of crystal symmetry on the stiffness tensor for both free surfaces and grain boundaries. This results in substantial simplifications for cases in which interfaces possess mirror or rotational symmetries. An efficient method for determining the interface stiffness tensor using atomistic simulations is proposed. [Copyright &y& Elsevier]

Lipids provide a wide range of functional properties utilized in technical applications, and the mechanisms usually are based on the physical properties of the liquid‐crystalline phases. Even the solid state of lipids can sometimes provide similar functions, which are described in this article. Crystallization from an aqueous dispersion of the lamellar liquid‐crystalline phase of monoglycerides can form hydrophilic lipid crystals, which are able to attach large proportions of water to the dominating surfaces of the leave‐shaped crystals formed by the polar head group planes. Such lipid crystal dispersions have been utilized as a general ointment base and as stabilizers in food applications.Many lipid‐based emulsions are prepared by cooling during a mixing process. A general mechanism for stabilization of such emulsions is the formation of crystals of polar lipids at the oil/water interface. These lipid crystals form an interfacial film, which expose hydrophilic surfaces toward the water phase and hydrophobic surfaces toward the inner oil core. The interfacial tension versus temperature at the corresponding oil/water interface starts to decrease abruptly at the same temperature as crystals of the polar lipid start to form in the oil phase, as identified by x‐ray diffraction. The crystal formation in the corresponding binary system triglyceride oil/polar lipid followed in the polarizing microscope shows a simple eutectic behavior. The polar lipid crystal formation at the oil/water interface requires that the triglyceride oil/polar lipid composition of the binary system corresponds to the polar lipid side of the eutecticum. Examples of both oil‐in‐water and water‐in‐oil emulsions formed in this way are described. Other aspects of lipid crystals in emulsions, which involve the oil core, are also discussed. An interesting phenomenon is the formation of a beta‐crystal gel state, which recently has been characterized. [ABSTRACT FROM AUTHOR]

This is a critical survey of the phenomenon of strain-induced crystalline phase changes in semi-crystalline polymers. This paper is not concerned with the strain induced crystallization of glassy polymers. An examination is made of the experimental data reported in literature, together with a discussion about the mechanism of crystalline phase transitions and about the benefits or prejudices which result on the materials properties. Special attention has been paid to the most largely documented polymers which include materials having either van der Waals, or hydrogen or polar interchain bonding. This concerns polypropylene, polyamide 6, ethylene/vinyl-alcohol copolymers, poly(vinylidene fluoride) polyesters, and polyethylene. An additional section is devoted to several series of much less documented polymers, from the standpoint of crystal phase changes. Although most of the cases are dealing with films and fibers submitted to tensile drawing, some of the reported studies are concerned with bulk materials. An attempt is made to establish guidelines for the mechanisms of crystalline phase changes based on chain conformation, thermodynamic stability, and plasticity defects. [ABSTRACT FROM AUTHOR]

The most widely used memory materials for rewritable phase-change optical disks are the GeTe—Sb2Te3 pseudobinary compounds. Among these compounds, Ge2Sb2Te5 crystallizes into a cubic close-packed structure with a six-layer period (metastable phase) in the non-thermal equilibrium state, and a trigonal structure with a nine-layer period (stable phase) in the thermal equilibrium state. The structure of the stable phase has Ge/Sb layers in which Ge and Sb are randomly occupied, as does the structure of the metastable phase, while the conventionally estimated structure had separate layers of Ge and Te. The metastable and stable phases are very similar in that Te and Ge/Sb layers stack alternately to form the crystal. The major differences between these phases are: (i) the stable phase has pairs of adjacent Te layers that are not seen in the metastable phase and (ii) only the metastable phase contains vacancies of ca 20 at. % in the Ge/Sb layers. [ABSTRACT FROM AUTHOR]

Abstract: We postulate that almost any motion of an interface between two crystals can produce a coupled tangential motion of the two crystals relative to each other which is proportional to the normal motion of the interface. Such translations can produce grain rotations; the special case of the rotations of shrinking included circular cylindrical grains which increase misorientation, as seen in the molecular dynamics simulations, is reinterpreted with this postulate. When this postulate is added to other principles of interface motion, several phenomena associated with grain boundary mechanics and motion are unified into a single theoretical formulation: normal motion of a grain boundary resulting from a shear stress applied tangential to it which results in tangential motion and its converse, tangential motion resulting from coupling to normal motion; rigid sliding of one grain with respect to the other along a “greased” boundary; grain rotation due to tangential motion along curved grain boundaries, produced by either by sliding or by coupling to the normal motion. When the motion is driven by the reduction in the total surface free energy ∫γda, if the grain rotation is due to sliding alone, then γ itself (the surface free energy per unit area) is reduced; if it is due to coupled motion, then increases in γ can occur if there is a large enough decrease in area that ∫γda is decreased. We explore the predictions for rotations of circular cylindrical grains moving to reduce total surface free energy. Among the surprising results is that certain combinations of coupling and surface free energy functions can result in increases rather than decreases in radii; these conditions, if achievable, can only occur far from small tilt misorientations. We also show that sliding alone must lead to misorientations with minimum γ – or no misorientation – before the crystal shrinks to zero radius. For coupling alone, limiting misorientations (which need not, and often do not, coincide with minima in γ) are never reached for non-zero radii. A more thorough exploration of sliding and coupling, including application to non-circular crystals and a variational model, is being published elsewhere. [Copyright &y& Elsevier]

In this article, the melting blend was used to prepare the Micro-ZnO/LDPE, Nano-ZnO/LDPE and Micro-Nano-ZnO/LDPE with different inorganic particles contents. The effect of Micro-ZnO and Nano-ZnO particles doping on interface microdomain and corona-resistance breakdown characteristics of LDPE composite could be explored. Based on the energy transfer and heat exchange theory of energetic electrons, the inner electrons energy transfer model of different ZnO/LDPE composites was built. Besides, the microstructure and crystalline morphology of inorganic ZnO-particles and polymer composites were detected by SEM, XRD, FTIR, PLM and DSC test, and the AC breakdown and corona-resistance breakdown characteristics of composites could be explored. From the experimental results, the Nano-ZnO particles after surface modification dispersed uniformly in LDPE matrix, and the nanoparticles agglomeration almost disappeared. The inorganic particles doping acted as the heterogeneous nucleation agent, which improved the crystallization rate and crystallinity of polymer composites effectively. The ZnO particles with different size doping constituted the different interface structure and crystalline morphology, which made different influence on composites macroscopic properties. When the Nano-ZnO particle size was 40nm and the mass fraction was 3%, the breakdown field strength of Nano-ZnO/LPDE was the highest and 15.8% higher than which of pure LDPE. At the same time, the shape parameter β of Micro-Nano-composite was the largest. It illustrated the microparticles doping reduced the probability of nanoparticles agglomeration in matrix. Besides, both Micro-ZnO and Micro-Nano-ZnO particles doping could improve the ability of corona corrosion resistance of LDPE in varying degrees. The corona-resistant breakdown time order of four samples was as follows: LDPE < Micro-ZnO/LDPE < Nano-ZnO/LDPE < Micro-Nano-ZnO/LDPE. When the mass fraction of Micro-ZnO and Nano-ZnO particles was 2% and 3% respectively, the corrosion depth and area of Micro-Nano-ZnO/LDPE was the least, and the ability of corona corrosion resistance was the strongest. [ABSTRACT FROM AUTHOR]

We have measured the density of Pd[sub 40]Ni[sub 40-x]Cu[sub x]P[sub 20] (x=0–40) alloys in the amorphous and crystalline states. For x>30, the alloys are denser in the amorphous than in the crystalline states, which is contrary to the behavior of all known metallic glasses. For Pd[sub 40]Ni[sub 40-x]Cu[sub x]P[sub 20] and all other bulk metallic glasses where density data are available in both the amorphous and crystalline states, we find a correlation between the stability of the supercooled liquids and the difference between the molar volumes of the glassy and crystalline phases. The supercooled liquid region is largest for those alloys that show no change in molar volume upon crystallization. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents an ion-beam-induced epitaxial crystallization (IBIEC)/amorphization model at the amorphous silicon interface. Use of IBIEC for recrystallizing damaged layers; Relationship between recrystallization and amorphization; Dependence of crystallization rate on interface orientation.

The article presents a setup which combines SAXS, WAXS and XAFS to study the crystallization processes of inorganic solids in depth. The purpose of this study is to follow the changes that occur with time at the molecular, nanoscopic and crystalline level with a time resolution in the order of a few minutes. The setup enables the observation of the various stages of zinc-substituted microporous aluminophosphate formation in one experiment and represents the first data of its kind.