Materials Literature
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Piezoresponse force microscopy (PFM) has emerged as a primary tool for imaging, domain engineering, and switching spectroscopy on ferroelectric materials. Quantitative interpretation of PFM data, including measurements of the intrinsic width of the domain walls, determination of geometric parameters of the domain belo…
Among the large Au n - clusters for n > 20, the photoelectron spectra of Au 34 - exhibit the largest energy gap (0.94 eV) with well-resolved spectral features, making it a good candidate for structural consideration in conjunction with theoretical studies. Extensive structural searches at several levels of density fun…
Relying on first principles simulations of stoichiometric MgO, ZnO, and NaCl (1x1) ultrathin (111) films, we demonstrate the existence of a critical thickness below which polarity is uncompensated: the surface charges are bulklike, and the total dipole moment and the formation energy grow linearly with thickness. This…
Abstract Polymeric scaffolds play a crucial role in engineering process of new tissues and effect the cell growth and viability. PLCL copolymers are found to be very useful during cell growth due to their elastic behavior and mechanical strength. Thus, low molecular weight PLCL copolymers of various ratios viz. PLCL(9…
Abstract Hybrid composites of wood flour/kenaf fiber and polypropylene were prepared at a fixed fiber to plastic ratio of 40 : 60 and variable ratios of the two reinforcements namely 40 : 0, 30 : 10, 20 : 20, 10 : 30, and 0 : 40 by weight. Polypropylene was used as the polymer matrix, and 40–80 mesh kenaf fiber and 60…
Large-scale atomistic simulations, which we define as containing more than 100 000 atoms, are becoming more commonplace as computational resources increase and efficient classical molecular dynamics algorithms are developed. With the advent of grid-computing methods, it is now possible to simulate even larger systems…
Nanoporous composite electrodes for lithium ion batteries were successfully fabricated by coating porous carbon with V 2 O 5 gel, and their high rate capability was demonstrated. The porous carbons prepared by using SiO 2 colloidal crystals as templates exhibited ordered three dimensionally interconnected pores. The p…
Electronic band structure and optical properties of zinc monochalcogenides with zinc-blende- and wurtzite-type structures were studied using the ab initio density functional method within the LDA, GGA, and LDA+U approaches. Calculations of the optical spectra have been performed for the energy range 0-20 eV, with and…
The authors study a simple model of a nematic liquid crystal made of parallel ellipsoidal particles interacting via a repulsive Gaussian law. After identifying the relevant solid phases of the system through a careful zero-temperature scrutiny of as many as eleven candidate crystal structures, they determine the melti…
Heteroepitaxial self-assembled quantum dots (SAQDs) will allow breakthroughs in electronics and optoelectronics. SAQDs are a result of Stranski-Krastanow growth whereby a growing planar film becomes unstable after an initial wetting layer is formed. Common systems are Ge$_{x}$Si$_{1-x}$/Si and In$_{x}$Ga$_{1-x}$As/GaA…
Palladium and platinum are important catalytic metals, and it would be highly advantageous to be able to use surface enhanced Raman spectroscopy (SERS) to study reactive species and intermediates on their surfaces. In this paper we describe the use of templated electrodeposition through colloidal templates to produce…
We have investigated decorrelation of samples in Quantum Monte Carlo (QMC) ground-state energy calculations for large Li and H$_{2}$O nanoclusters. Binning data as a way of eliminating statistical correlations, as is the common practice, is found to become increasingly impractical as the system size grows. We demonstr…
The optical conductivity of charge carriers coupled to quantum phonons is studied in the framework of the one-dimensional spinless Holstein model. For one electron, variational diagonalization yields exact results in the thermodynamic limit, whereas at finite carrier density analytical approximations based on previous…
Capacitance-voltage characteristics of individual germanium nanowire field effect transistors were directly measured and used to assess carrier mobility in nanowires for the first time; thereby removing uncertainties in calculated mobility due to device geometries, surface and interface states and gate dielectric cons…
We address the role of excitonic coulping on the nature of photoexcitations in the conjugated polymer regioregular poly(3-hexylthiophene). By means of temperature-dependent absorption and photoluminescence spectroscopy, we show that optical emission is overwhelmingly dominated by weakly coupled H-aggregates. The relat…
This report examines the thickness dependence of the reorientation phase transition in ferromagnetic films with perpendicular anisotropy. That is, we find the exact boundary of metastability of uniformly magnetized in-plane states as the solution to a set of transcendental algebraic equations, and find the profile of…
In recent years, there has been increasing interest in the specific heat $C$ of insulators and semiconductors because of the availability of samples with different isotopic masses and the possibility of performing \textit{ab initio} calculations of its temperature dependence $C(T)$ using as a starting point the electr…
The thermal behavior of free and alumina-supported iron-carbon nanoparticles is investigated via molecular-dynamics simulations, in which the effect of the substrate is treated with a simple Morse potential fitted to ab initio data. We observe that the presence of the substrate raises the melting temperature of medium…
The authors numerically study a simple fluid composed of particles having a hard-core repulsion, complemented by two short-ranged attractive (sticky) spots at the particle poles, which provides a simple model for equilibrium polymerization of linear chains. The simplicity of the model allows for a close comparison, wi…
Ultralong nanobelts (>0.3 mm) have been fabricated from an asymmetric perylene tetracarboxylic diimide (PTCDI) molecule via a seeded self-assembly processing. The long length of nanobelts facilitates the construction of two-electrode devices employing the nanobelt as channel material, and the long-range one-dimensiona…