Materials Literature
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By molecular dynamics simulation, we study the charge inversion phenomenon of a rod macroion in the presence of polyelectrolyte counterions. We simulate electrophoresis of the macroion under an applied electric field. When both counterions and coions are polyelectrolytes, charge inversion occurs if the line charge den…
This letter reports a giant magnetocaloric effect (GMCE) in a novel series of materials based on the shape memory alloy Ni2MnGa. The origin of an enhanced GMCE is traced to the coincidence of a first-order magnetic transition and its attendant structural phase transition with a second-order magnetic transition. This c…
Polarized first- and second-order Raman scattering and infrared reflection spectra of hexagonal HoMnO 3 single crystals in the temperature range 10–300 K are reported. Based on the symmetry analysis and comparison with the results of lattice dynamics calculations the observed lines are assigned to the lattice eigenmod…
We investigate the gradual crossover from ferroelectric to relaxor behaviour versus substitution in lead-free ceramics. We show that the Vogel–Fulcher law in the relaxor state is the extrapolation of the ferroelectric line. To explain this extrapolation, we suggest that both the host matrix and the impurity induced cl…
Bead packs of up to 150,000 mono-sized spheres with packing densities ranging from 0.58 to 0.64 have been studied by means of X-ray Computed Tomography. These studies represent the largest and the most accurate description of the structure of disordered packings at the grain-scale ever attempted. We investigate the ge…
We review a recent proposal of a first principles approach to the electronic structure of materials with strong electronic correlations. The scheme combines the GW method with dynamical mean field theory, which enables one to treat strong interaction effects. It allows for a parameter-free description of Coulomb inter…
Frequency dependence of magnetoelectric (ME) coupling is investigated in trilayers of ferromagnetic alloy and piezoelectric lead zirconate titanate (PZT). The ferromagnetic phases studied include permendur, a soft magnet with high magnetostriction, iron, nickel, and cobalt. Low frequency data on ME voltage coefficient…
We give a detailed description of a recently proposed first principles approach to the electronic structure of strongly correlated materials. The method combines the GW approximation with dynamical mean field theory. It is designed to describe Coulomb interactions and screening effects without adjustable parameters, t…
The observation of strong magnetoelectric effects is reported in thick film bilayers and multilayers of ferrite-lead titanate zirconate (PZT) and lanthanum nanganite-PZT. The ferrites used in our studies included pure and zinc substituted cobalt-, nickel- and lithium ferrites. Samples were prepared by sintering 10-40…
We discuss a model that considers the bulk composite as a homogeneous medium with piezoelectric and magnetostrictive subsystems. We solve combined elastostatic, electrostatic and magnetostatic equations to obtain effective composite parameters (piezoelectric modules, magnetostriction factors, compliances, magnetoelect…
Gold nanoclusters are grown by 1.8 MeV Au++ implantation in silica matrix and subsequent air annealing in the temperature range of 873K-1273K. Post-annealed samples show plasmon resonance in the optical region (~ 2.38-2.51 eV) for average cluster radii ~1.04-1.74 nm. A blueshift of the plasmon peak is observed with de…
We report electronic structure calculations within density functional theory for the hydrated superconductor Na_{1/3}CoO_2(1.33)H_2O and compare the results with the parent compound Na_{0.3}CoO_2. We find that the intercalation of water into the parent compound has little effect on the Fermi surface outside of the pre…
Large high-quality single crystals of Bi2Sr2Can-1CunO2n+4+d (n = 2, 3) were successfully grown using an improved traveling solvent floating zone (TSFZ) method, which features a slow growth rate and steep temperature gradient along the melting zone. By measuring anisotropic resistivities and susceptibilities of Bi2Sr2C…
We study both linear and nonlinear surface waves localized at the interface separating a left-handed (LH) medium (i.e., a medium with both negative dielectric permittivity and negative magnetic permeability) and a conventional [or right-handed (RH)] dielectric medium. We demonstrate that the interface can support both…
We recently demonstrated that the diphenylalanine recognition motif of the Alzheimer's β-amyloid polypeptide self-assembles into ordered and discrete nanotubes. Here, we reveal that diphenylglycine, a highly similar analogue and the simplest aromatic peptide, forms spherical nanometric assemblies. As the nanotubes, th…
Single-walled carbon nanotube (SWNT) reinforced polymer composite membranes have been fabricated using the electrospinning technique. Nanofibers with a diameter in the range 50−100 nm were obtained by electrospinning SWNT-filled polystyrene composites. TEM observations revealed incorporation of small SWNT bundles orie…
Abstract Creep motion of ferroelectric domain walls in epitaxial Pb(Zr 0.2 Ti 0.8 )O 3 thin films was studied by atomic force microscopy. The dynamical exponent μ was found to be smaller than in previous reports, with values significantly lower than 1 observed in samples with a‐axis inclusions.
An antimony-doped germanium single crystal was grown by the axial heat processing (AHP) method from the melt to study the influence of facets on the morphological stability of a solid/liquid interface. A mathematical model together with experimental data was utilized to predict the solute concentration and stability i…
We investigate the time evolution of the density of interfaces in a two-phase mixture, with particular emphasis on the role of compressibility, dilatability and phase transitions. Two different and complementary routes are considered: a rather intuitive one based on exact results for dilute mixtures which are then int…
Abstract Pulse field gradient (PFG) NMR measurements have been made to study the diffusion of diethyl ether in blends of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA). The blends have 10–30 wt % PEO, a composition range within which these materials are amorphous glasses. The diffusion of diethyl ethe…