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In this study, we have studied the influence of nitrogen content on the mechanical properties of nanostructure medium entropy (TiVCrAl)Nx films prepared by magnetron sputtering. A transition from body-centered cubic nanocrystalline phases to an face-centered cubic columnar crystal structure has been observed in the medium entropy films as the nitrogen flow increases. With increasing nitrogen flow, the lattice constant of the film first increases and then decreases due to the change of composition from substoichiometric to overstoichiometric, resulting in the different bond length of Metal-N. The hardness of the films first increases and then decreases with the increase of nitrogen flow. When the nitrogen flow was 25 sccm, the hardness reached the maximum value of 23.1 GPa. Moreover, the film has shorter cracks length and a higher hardness/modulus ratio, exhibiting enhanced fracture toughness. The increased hardness primarily results from the formation of bonds between metals and nitrogen and the strengthening of a solid solution and a grain boundary. [ABSTRACT FROM AUTHOR]

The thermal transport behavior of polycrystalline graphene is studied using molecular dynamics simulations, with focus on the effects of grain size, tensile strain, and temperature on the thermal conductivity. All the simulation samples have the same overall dimensions of 30×30 nm with average grain sizes ranging from 2.5 to 12.5 nm. It is found that polycrystalline graphene exhibits a significant reduction in thermal conductivity compared to single-crystalline graphene, and the smaller the grain size is, the more the thermal conductivity drops. The thermal conductivity of polycrystalline graphene with average grain size of 2.5 nm is only about 20% of single-crystalline graphene. However, the thermal conductivity of polycrystalline graphene is less sensitive to both the applied strain and temperature than that of single-crystalline graphene. The underlying mechanisms for the differences in thermal behavior are examined and discussed. These findings are important for the thermal management of graphene-based devices. [ABSTRACT FROM AUTHOR]

Recently, nanoglass (NG) was found to exhibit a surprising homogeneous superplastic deformation behavior. However, how the presence of notch affects its mechanical properties remains unexplored. Here, we perform molecular dynamics simulations on a superplastic Cu50Zr50 NG containing a pre-existing notch under tensile loading, with focus on the notch sensitivity. Our results show that when the notch size is smaller than or comparable to the average grain size (d), the NG still exhibits a superplastic deformation and shows notch-insensitivity. When the notch size is larger than d, however, the NG fails by localized shear banding emanating from the notch root and shows notch-sensitivity. The origin of this transition arises from the competition between the shear band nucleation induced by the stress concentration at the notch root and the growth of shear transformation zones distributed in the glass-glass interfaces. Our results provide useful guidelines for the design and engineering of NG with notch for structural applications. [ABSTRACT FROM AUTHOR]

Composition profile across an interface in a core/shell or axial heterojunction nanowire often plays an important role in dictating its electronic, optical and magnetic properties. The control of composition profiles to achieve optimal performance still remains a challenge. In the present work, we formulate a theoretical model which accounts for three key factors that completely control the interface composition profile: the deposition flux of individual components, the atomic exchange rate between the surface and its sub-surface layer, and the thermodynamic driving force for surface segregation. We validate the model by matching its predictions with the experimental results for thin film growth. We then apply the model to the growth of core/shell and axial heterojunction nanowires and show that both abrupt and diffuse interface composition profiles can be achieved by tuning the growth parameters, providing a predictive approach for controlling interface composition distribution. [ABSTRACT FROM AUTHOR]

InxGa1-xN alloys (0 ≤ x ≤ 1) have been grown on GaN/sapphire templates by molecular beam epitaxy. Growth temperature controlled epitaxy was proposed to modulate the In composition so that each InxGa1-xN layer was grown at a temperature as high as possible and thus their crystalline quality was improved. The bandgap energies of the InxGa1-xN alloys have been precisely evaluated by optical transmission spectroscopy, where the effect of residual strain and electron concentration (the Burstein-Moss effect) on the bandgap energy shift has been considered. Finally, a bowing parameter of ∼1.9 ± 0.1 eV has been obtained by the well fitting In-composition dependent bandgap energy. [ABSTRACT FROM AUTHOR]

We investigate the bifurcation instabilities of swelling circular hydrogel plates programed with a space-varying cross-linking density along the radial direction. Depending on the distribution of the cross-linking density and the aspect ratio of the plate, different buckling patterns are observed. When the cross-linking density is lower at the center and increases monotonically outwards, a global buckling occurs, and the hydrogel plate forms an axisymmetric bowl-shaped container. When the cross-linking density is higher at the center and decreases monotonically outwards, edge wrinkling occurs. These wrinkles can be either localized near the edge or penetrate deep into the plate, depending on the detailed distribution of the cross-linking density. The rich post-buckling morphologies exhibited by the programed hydrogel plate provide a powerful route to fabricate smart hydrogel components, such as, self-adjusting containers and microlenses. [ABSTRACT FROM AUTHOR]

The interfaces between graphene and graphane play an important role in developing graphene-graphane-based electronic devices. We identify three most common types of graphane-graphene interface, and perform atomistic simulations to determine three key parameters that characterize the interface structural properties: mismatch strain, tilt angle, and interfacial stress. Further through atomistic simulations, we find that the composite sheets can develop complex morphologies, such as ripples, warps and wedges. These morphologies can be accurately reproduced by our finite-element modeling with interfacial properties explicitly included. We further show that mismatch in the lattice parameters between graphene and graphane is the dominant factor that causes the complex morphologies. Our work provides a quantitative framework for analyzing and designing graphene-graphane composite sheet architectures, and further for exploring their electronic properties. [ABSTRACT FROM AUTHOR]

We investigate the mechanical instabilities of hydrogel microlenses triggered by concentrated loadings. Depending on hydrogel microlenses, geometries, and loading conditions, a series of nontrivial instability pathways is observed, including transitions of localized polyhedral faceted shapes with multifold vertices created by bifurcation, snapping through curvature inversion and large load drop, and wrinkling driven by combined in-plane stretching and compression. These pathways reveal the richness of the mechanical behavior of hydrogel microlenses and provide potential strategies to control the design and shape of complex hydrogel microlenses. [ABSTRACT FROM AUTHOR]

We have developed an effusive laser photodissociation radical source, aiming for the production of vibrationally relaxed radicals. Employing this radical source, we have measured the vacuum ultraviolet (VUV) photoionization efficiency (PIE) spectrum of the propargyl radical (C3H3) formed by the 193 nm excimer laser photodissociation of propargyl chloride in the energy range of 8.5-9.9 eV using high-resolution (energy bandwidth=1 meV) multibunch synchrotron radiation. The VUV-PIE spectrum of C3H3 thus obtained is found to exhibit pronounced autoionization features, which are tentatively assigned as members of two vibrational progressions of C3H3 in excited autoionizing Rydberg states. The ionization energy (IE=8.674±0.001 eV) of C3H3 determined by a small steplike feature resolved at the photoionization onset of the VUV-PIE spectrum is in excellent agreement with the IE value reported in a previous pulsed field ionization-photoelectron study. We have also calculated the Franck-Condon factors (FCFs) for the photoionization transitions C3H3+(...;vi, 1 - 12) ← C3H3(...). The comparison between the pattern of FCFs and the autoionization peaks resolved in the VUV-PIE spectrum of C3H3 points to the conclusion that the resonance-enhanced autoionization mechanism is most likely responsible for the observation of pronounced autoionization features. We also present here the VUV-PIE spectra for the mass 39 ions observed in the VUV synchrotron-based photoionization mass spectrometric sampling of several premixed flames. The excellent agreement of the IE value and the pattern of autoionizing features of the VUV-PIE spectra observed in the photodissociation and flames studies has provided an unambiguous identification of the propargyl radical as an important intermediate in the premixed combustion flames. The discrepancy found between the PIE spectra obtained in flames and photodissociation at energies above the IE(C3H3) suggests that the PIE spectra obtained in flames might have contributions from the photoionization of vibrationally excited C3H3 and/or the dissociative photoionization processes involving larger hydrocarbon species formed in flames. [ABSTRACT FROM AUTHOR]

Atomistic simulations of the structures and stability of defect-free multiwalled carbon toroidal rings were performed using the second-generation empirical bond-order potential and a Morse-type van der Waals potential. It was found that a multiwalled toroidal ring improves the structural stability over its outermost single-walled counterpart, implying a stabilizing effect from the inner rings. This can be explained by the superlinear relation between the critical ring diameter and its tube diameter existing in single-walled rings. However, the findings that the critical diameter of an armchair ring is larger than that of a zigzag ring with the same tube diameters, and that the inclusion of torsion exhibits a negative effect on the stability of a multiwalled ring, are in contrast to that of a single-walled nanoring. In addition, the instability of a multiwalled nanoring always starts with the formation of many short-wavelength ripples on the compressed side of the outermost tube. Subsequently, some of the ripples develop into buckles, resulting in buckling failures. [ABSTRACT FROM AUTHOR]

Mechanical oscillatory behavior of multiwalled carbon-nanotube-based oscillators is investigated using molecular-dynamics simulations. The second-generation reactive bond-order potential and a Morse-type van der Waals potential based on the local-density approximation are used to describe bonding and nonbonding atomic interactions, respectively. It is found that the oscillatory frequency saturates as the number of outer tubes reaches three. The simulations show that the oscillatory frequency, amplitude decay rate, and stability of the oscillators depend on the diameter and helicity of the outer tubes, the extrusion distance, as well as the length of the outer tubes. [ABSTRACT FROM AUTHOR]

The mechanical oscillatory behavior of a C60 molecule tunneling through a carbon nanotube induced by van der Waals interaction are investigated by molecular-dynamics simulations. It is found that the C60 performs a decaying oscillation with a gradual decrease of the oscillatory amplitude and a gradual decrease of the oscillatory frequency. It is shown that this decay is due to the transformation of thermal energy and is sensitive to the change in the diameter and the degree of the helicity of the nanotube. In addition, the nanotube length can be used to tune the oscillation frequency of the C60-nanotube oscillators. [ABSTRACT FROM AUTHOR]

A three-dimensional concurrent atomistic/continuum analysis is performed to study the stress distributions in an epitaxial island. The island and the adjacent substrate are modeled by the molecular dynamics method, and the surrounding zone is modeled by the finite element method in which the nonlinear elasticity is governed by the atomic potential. An overlapping zone is defined to be the location where the atomistic and continuum models exchange necessary material information. It is found that the nonlinear elasticity based on the atomic potential is required for a smooth stress transition in the overlapping zone, and that the linear elasticity assumption significantly overestimates the stress levels at moderate and high loading levels. The implications of the present results on surface roughening driven by strain energy are discussed. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Many experimental observations have clearly shown that dislocation interaction plays a crucial role in the kinetics of strain relaxation in epitaxial thin films. A set of evolution equations are presented in this article. The key feature of the equations is the incorporation of dislocation interactions into the kinetic process by introducing a resistance term. The resistance to threading dislocation gliding is characterized by a hardening function, which depends only on the relaxed plastic strain. The evolution equations are tested on the Ge[sub x]Si[sub 1-x]/Si(100) materials system. Existing fundamental parameters are incorporated into the present model. The evolution equations successfully reproduce a wide range of experimental data on strain relaxation in Ge[sub x]Si[sub 1-x]/Si heterostructures. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Provides information on a study that analyzed the dynamic propagation of an atomistic crack tip using a molecular dynamics method. Methodology of the study; Results and discussion on the study.

Presents a study which analyzed the nucleation and emission of dislocations from the crack tip under mode II loading by the molecular dynamics method in which Finnis-Sinclair potential has been used. Experimental details; Results and discussion; Conclusions.

Sputtered metal-nonmetal granular films tend to exhibit growth-induced perpendicular magnetic anisotropy. In this work, Co/HfN multilayers were synthesized to suppress the development of columnar clusters along the deposition direction. The results reveal that a HfN interlayer thickness of less than 0.4 nm is insufficient to separate the columnar clusters; however, increasing the interlayer thickness to 0.8 nm with increasing the sputtering duration successfully led to typical in-plane magnetic anisotropy with a coercivity as low as 3 Oe. The Co(4 nm)/HfN(1.5 nm) multilayers exhibited high permeability of approximately 260 up to 1.6 GHz. The resonance frequency increased from 1.8 to 2.3 GHz with increasing annealing temperature, which is attributed to the increased magnetic anisotropy. Our results suggest that the multilayers still show high-frequency performance even after annealing at 450 °C, which would be a big advantage for complementary metal-oxide-semiconductor (CMOS) fabrication technology. [ABSTRACT FROM AUTHOR]

An instrument used for measuring multiple scintillators' light output and energy resolution was developed. The instrument consisted of a light sensor array which was composed of 64 discrete SiPMs (Silicon Photomultipliers), a corresponding individual channel readout electronics system, and a data processing algorithm. A Teflon grid and a large interval between adjacent SiPMs were employed to eliminate the optical cross talk among scintillators. The scintillators' light output was obtained by comparing with a reference sample with known light output. Given the SiPM temperature dependency and the difference among each SiPM, a temperature offset correction algorithm and a non-uniformity correction algorithm were added to the instrument. A positioning algorithm, based on nine points, was designed to evaluate the performance of a scintillator array. Tests were performed to evaluate the instrument's performance. The uniformity of 64 channels for light output measurement was better than 98%, the stability was better than 98% when temperature varied from 15 °C to 40 °C, and the nonlinearity under 511 keV was better than 2%. This instrument was capable of selecting scintillators and evaluating the packaging technology of scintillator arrays with high efficiency and accuracy. [ABSTRACT FROM AUTHOR]

Using both theoretical analysis and phase field simulation, we reveal robust and facile selfassembly routes, which allow the growth of different stable and ordered nanostructures on various polyhedral nanocrystals (NCs) heteroepitaxially. Our studies show that by increasing the NC's size, transitions from formal growth to ordered quantum dots on the facets and further to ordered quantum dots on the corners take place. The predicted morphologies and their transitions are in excellent agreement with existing widely scattered experimental results. Our study presents a facile and potentially practical route for mass-producing hybrid NCs with well-defined size, shape, composition, and architecture. [ABSTRACT FROM AUTHOR]

Taking advantages of broad tunability of carrier density in electric-double-layer transistors (EDLTs) with ionic-liquid gating, we demonstrate evidence of parallel conduction from both p-type bulk and n-type surface in Mg-doped InN EDLTs by comparing their transport properties, especially Hall effect, with those in non-doped InN. Large anomalous oscillation in Hall coefficients with decreasing gate bias was observed in Mg-doped samples, which can be well simulated by two-carrier model. Our results provide the proof for the p-type bulk conduction in Mg-doped InN by showing its prominent effects on electrical transport. [ABSTRACT FROM AUTHOR]

Nanoscale pattern formation on surfaces by ion beam sputtering is driven by the competition between the erosion and the diffusion processes. In alloys, these processes are component-dependent. We present a kinetic Monte Carlo model for sputtering of alloy surfaces which exhibits morphological ripples and compositional patterns. The evolution of the ripple amplitude shows a crossover from an early stage exponential growth to a later stage power-law growth. We also present a nonlinear dynamic model which shows both the crossover and the surface patterns, confirming the importance of nonlinear terms in understanding the dynamics of alloy sputtering. [ABSTRACT FROM AUTHOR]

Stretchable and flexible electronics offer the performance of conventional wafer-based systems but can be stretched like a rubber band, twisted like a rope, and bent over a pencil. Such a technology offers new application opportunities, in areas of surgical and diagnostic implements that naturally integrate with the human body to provide advanced capabilities, to curvilinear devices such as hemispherical 'eyeball' cameras. In practice, stretchable and flexible electronic systems require encapsulation layers to provide mechanical and environmental protection. This paper establishes a simple, analytical model for the optimal design of encapsulation. [ABSTRACT FROM AUTHOR]

Both previous theoretical and experimental work showed that the bending rigidity of a liquid membrane decreases with increasing temperature. We demonstrate that the elastic energy forms for a solid membrane and a liquid membrane are identical under equal-biaxial stretching, implying the bending rigidity of a solid membrane should decrease with increasing temperature. We perform molecular dynamics simulations to study how thermal fluctuation affects the bending rigidity of graphene, and find that the bending rigidity decreases exponentially with increasing temperature. This is in contrast with recent atomistic Monte Carlo simulation result that the bending rigidity of graphene increases with increasing temperature. [ABSTRACT FROM AUTHOR]

ZnO based oxide system Zn1-x-yBexMgyO has been prepared by pulsed laser deposition. By incorporating different amounts of beryllium and magnesium into ZnO, the bandgap of ZnBeMgO has been modulated from 3.7 to 4.9 eV continuously. The crystal quality of ZnBeMgO film has been improved significantly comparing with that of either ZnMgO or BeZnO. These ZnBeMgO films are promising for fabricating high-efficiency optoelectronic devices such as solar-blind UV detectors. [ABSTRACT FROM AUTHOR]

The oscillatory characteristics and the instability of double- and triple-walled carbon nanotube-based oscillators containing a vacancy or a Stone–Wales (SW) defect were investigated by molecular dynamics simulations. It was found that the existence of these defects markedly affects the oscillation period and amplitude. The defect-free oscillators are most stable, followed by oscillators containing a SW defect, while oscillators containing a vacancy are least stable. The origin of the defect-induced instability is due to the change in potential energy profile and the resulting force fluctuation. [ABSTRACT FROM AUTHOR]

Spontaneous generation and propagation of a class of transverse and coaxial traveling waves in multiwalled carbon nanotubes annealed at high temperatures were observed by molecular dynamics simulation. It was found that these traveling waves are generated by end resonance. The observed wave velocity is consistent with that predicted by a continuum multiwalled shell model. The observed phenomenon may be used to measure the mechanical properties of carbon nanotubes or as a vibration generator in nanomechanical devices. [ABSTRACT FROM AUTHOR]

We have presented a detailed resonant Raman scattering investigation for the alloying effect in hexagonal Zn1-xMgxO (x≤0.323) thin films grown by pulsed laser deposition. Alloy-induced longitudinal optical (LO) phonon resonance effect has been achieved from the Raman peak shift, lineshape, and intensity through changing the Mg composition and temperature to tune the ZnMgO bandgap. By the aid of theoretical analysis combining with the extrinsic Fröhlich interaction mediated via a localized exciton, we demonstrate the pronounced outgoing resonance behavior for the LO phonons in ZnMgO, where the localized exciton due to alloy disorder dominates the resonance processes [ABSTRACT FROM AUTHOR]

Epitaxial n-ZnO/MgO/TiN/n+-Si heterostructured light-emitting diodes have been fabricated. The epitaxial growth of MgO/TiN on Si(111) was established by pulsed laser deposition, which was further employed as a buffer layer for epitaxial growth of ZnO layer by metal-organic chemical-vapor deposition. Good epitaxial quality was found using high-resolution x-ray diffraction and transmission electron microscopy. A strong wide electroluminescence band, ranging from 350 to 850 nm and centered at ∼530 nm, was observed from the diode when a positive voltage was applied on Si substrate. The diode exhibited a linear light-output-current characteristic with an injection current up to 192 mA. [ABSTRACT FROM AUTHOR]

We examine the dynamics of surface pattern formation during both annealing and vapor deposition of a heteroepitaxial thin film on prepatterned substrate surfaces, predicting a sustained propagation of regular surface waves via surface diffusion driven by strain relaxation. Both the wavelength and propagation speed are found to be insensitive to the surface prepatterns, growth rate and film thickness. [ABSTRACT FROM AUTHOR]

The variation in dot density, dot size, and photoluminescence intensity in two series of 1.8 and 2.5 ML InAs quantum dots (QDs) as a function of InAs growth rate has been investigated. As the growth rate increases from 0.14 to 3.60 ML/s, the average dot lateral size reduces by half, whereas the dot density increases five times. Nonlinear relationships were observed between dot density, dot size, and growth rate. The dot density is found to saturate at a growth rate of 3 ML/s. High dot density of 7.76×1011 cm-2 has been demonstrated and is beneficial for applications in high power QD devices. [ABSTRACT FROM AUTHOR]

Three-dimensional computer simulations are performed to obtain the phase diagrams for heteroepitaxially grown ordered quantum dots and quantum rings by surface prepatterning. Concave patterning in a squared array may lead to the formation of ordered dots, whereas convex patterning in a squared array may initially lead to the formation of ordered quantum rings, then a transition into quantum dots with further growth. The evolution of the surface chemical potential during growth explains the formation of the ordered surface structures. [ABSTRACT FROM AUTHOR]

The formation, self-assembly, and shape transition of heteroepitaxial islands during Stranski-Kranstonov growth are studied by three-dimensional computer simulations. It is shown that calculations considering surface energy anisotropy and elastic anisotropy reproduce many features of experimental results, and demonstrate the significance of their influence on island formation and self-assembly in epitaxial growth. [ABSTRACT FROM AUTHOR]

First-order perturbation analysis has been performed to investigate the stability and the fastest growth mode of a biaxially strained epitaxial thin film surface by stress-induced surface diffusion. It is found that the normalized critical wavelength along one principal direction depends on the Poisson’s ratio of the film, and also the perturbed wavelength and stress level along the other principal direction. The fastest growth analysis shows that when the absolute value of the ratio of the two principal stresses deviates from unity, a gradual transition from nanoisland formation to nanowire formation occurs. The larger the deviation, the stronger the tendency for the formation of a nanowire; finite element simulations confirm the tendency. [ABSTRACT FROM AUTHOR]

We report long-wavelength photoluminescence emission (∼1.6–1.7 μm) from self-organized InAs surface quantum dots (SQDs) grown on GaAs substrate without any capping layers. Photoluminescence (PL) properties of these quantum dots (QDs) are strongly affected by the surface states and strain relaxation mechanism. Compared to the case of capped InAs QDs, a large redshift of about 466 nm observed in the PL spectrum of SQDs can be attributed to the strain relaxation and the strong coupling of the confined states with the surface states. The PL properties of these SQDs can also be influenced by the presence of quasi-infinite surface potential. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations are performed to investigate the bending behavior of tubular graphite cones (TGCs). The second-generation reactive bond-order potential and four different van der Waals potentials are used to describe bonding and nonbonding atomic interactions, respectively. It is shown that the bending behavior is insensitive to the choice of the van der Waals potentials. An increase in the cone apex angle of TGCs moderately improves the bending stiffness due to the low shear resistance between the nanotube walls. A TGC with a high cone apex angle is preferred to a TGC with a low cone apex angle in terms of bending stiffness and stress level. It is also shown that an increase in the diameter of the innermost nanotube effectively increases the bending stiffness of TGCs. [ABSTRACT FROM AUTHOR]

Dislocation formation in homoepitaxial pyramidal [001] Cu islands under tensile stress is studied using molecular dynamics simulations. It is found that 90° Shockley partial dislocations are dominant in the island strain relaxation. For a low-aspect-ratio island, the dislocations are nucleated from the island surface and propagate downwards to form misfit dislocations. For a high-aspect-ratio island, a pair of the dislocations on the same slip plane are simultaneously nucleated respectively from the two island edges, propagate inwards, and react to form a 90° Shockley misfit partial dislocation. These dislocations can form sequentially and cooperatively. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The self-organization of three-dimensional quantum-dot superlattices that spontaneously form during heteroepitaxial growth is investigated by using a three-dimensional kinetic model. The model predictions show that the multilayer arrays of quantum dots can be fully or partially aligned vertically, or completely misaligned with respect to the buried islands, depending on the thickness of the spacer layer and the growth interruption time. In particular, there is a growth window in which a nearly uniform and regular array of dots is arranged in a squared lattice with an alternating stacking sequence; namely, the A-B-A-B stacking sequence. [ABSTRACT FROM AUTHOR]

A continuum model of shape transitions in strained heteroepitaxial islands predicts that small islands are hut shaped, while larger islands are domed. The volume of a stable hut can exceed that of a stable dome, however, indicating that the stability of hut-shaped islands plays an important role in shape transition, in addition to energy changes associated with the transition. A hut-shaped island loses stability upon reaching a critical volume, which depends on the anisotropy in surface energy. Impingement between islands reduces the critical volume by nucleating new facets at the base of a hut, which subsequently trigger a shape transition. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Bulk waves radiated into an anisotropic half-space by an interdigital transducer are studied theoretically. The mechanical displacements of excited waves are obtained by asymptotic evaluation of an integral whose singularities give rise to both Rayleigh surface waves and angularly focused bulk waves. By applying the analysis to singly rotated Y cuts of quartz with propagation normal to the x axis, it is shown that the orientation and width of the main lobe are very sensitive to frequency and crystal orientation. [ABSTRACT FROM AUTHOR]

Atomistic simulations revealed that the spatial correlations of plastic displacements in three metallic glasses, FeP, MgAl, and CuZr, follow an exponential law with a characteristic length scale ℓc that governs Poisson's ratio ν, shear band thickness tSB, and fracture mode in these materials. Among the three glasses, FeP exhibits smallest ℓc, thinnest tSB, lowest ν, and brittle fracture; CuZr exhibits largest ℓc, thickest tSB, highest ν, and ductile fracture, while properties of MgAl lie in between those of FeP and CuZr. These findings corroborate well with existing experimental observations and suggest ℓc as a fundamental measure of the shear transformation zone size in metallic glasses. [ABSTRACT FROM AUTHOR]

Presents a correction to the article "Molecular Dynamics Simulation of Bending Behavior of Tubular Graphite Cones," published in the November 8, 2004 issue of "Applied Physics Letters," which made an error on the position of point A in the inset of Figure 4.

Dense, crack-free, uniform, and homogeneous (RE[sub 2]O[sub 3])[sub 0.08](ZrO[sub 2])[sub 0.92] (RE=Sc, Y) nanocrystalline thin films were fabricated by a simple sol-gel method and characterized by impedance studies. At temperatures beyond 600 °C, the electrical conductivity of (Sc[sub 2]O[sub 3])[sub 0.08](ZrO[sub 2])[sub 0.92] and (Y[sub 2]O[sub 3])[sub 0.08](ZrO[sub 2])[sub 0.92] nanocrystals in pure cubic phase was ten times higher than that of the corresponding bulk materials. The decrease of grain boundary resistance related to interfacial effect is predominately responsible for the electrical conductivity enhancement. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]