Materials Literature
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We formulate a theory of doped magnetic semiconductors such as Ga(1-x)Mn(x)As which have attracted recent attention for their possible use in spintronic applications. We solve the theory in the dynamical mean field approximation to find the magnetic transition temperature T(c) as a function of magnetic coupling streng…
Dielectric measurements are reported for liquid crystalline dimers consisting of two mesogenic groups joined through ether links by a flexible alkyl chain. Results are presented for the odd-symmetric dimer, α,ω-bis[(4-cyanobiphenyl)-4′-yloxy]undecane (BCB.O11), and the odd-asymmetric dimer, α-[(4-cyanobiphenyl)-4′-ylo…
Surface glass transition behaviors of monodisperse α,ω-diamino-terminated and α,ω-dicarboxy-terminated polystyrenes (α,ω-PS(NH 2 ) 2 and α,ω-PS(COOH) 2 ) were studied by scanning force microscopy and were compared with the results of proton-terminated polystyrene (PS−H). All surface glass transition temperatures, T g…
Late-stage coarsening in off-critical vapor-liquid phase separation is reexamined. In the limit of bubbles of vapor distributed throughout a continuous liquid phase, it is argued that coarsening proceeds via inertial hydrodynamic bubble collapse. This replaces the Lifshitz-Slyozov-Wagner mechanism seen in binary liqui…
Detailed microscopic image of polymer crystallization from the melt is searched for by molecular dynamics simulation. In order to accelerate crystallization, a simple model of polymethylene chain is devised; the polymer chain is made of 100 beads (CH2 united atoms) connected by harmonic springs and the lowest energy c…
We present a finite-temperature study of ferroelectric phase transitions in ${\mathrm{BaTiO}}_{3}$ ultrathin films using an atomic-level simulation approach. This is based on a shell model for ${\mathrm{BaTiO}}_{3}$ with parameters obtained from first-principles calculations. While transitions involving in-plane elect…
The location of poly(styrene- b -poly(methyl methacrylate)) (PS- b -PMMA) block copolymers in PMMA/poly(cyclohexyl methacrylate) (PCHMA) melt mixed blends was determined. Among all these components, only the PS portion of the block copolymer can be stained by ruthenium tetroxide and appears dark in transmission electr…
Temperature and dc magnetic-field dependencies of the electrical resistivity (4.3--300 K, 0--40 kOe) and heat capacity (3.5--14 K, 0--100 kOe) of polycrystalline ${\mathrm{Gd}}_{5}{\mathrm{Ge}}_{4}$ have been measured. The electrical resistivity of ${\mathrm{Gd}}_{5}{\mathrm{Ge}}_{4}$ shows a transition between the lo…
In this paper, we investigate the two mechanisms that are responsible for the release of a chemical substance from water-in-oil-in-water double emulsions. (i) One is due to the coalescence of the thin liquid film separating the internal droplets and the oil globule surface. (ii) The other mechanism occurs without film…
Native cellulose consists of a set of parallel chains composed of glucose. Most of the time, these chains are highly ordered and form a structure that is known as a microfibril. On the other hand, highly crystalline forms of cellulose are more difficult to process and often are unpredictable in their behavior. If an o…
The reaction of di-2-pyridyl ketone, (2-py)2CO, with Ni(O2CMe)(2).4H2O yields the cage [Ni9(OH)2(O2CMe)8((2-py)2CO2)4], which reacts further with N3- ions to give the structurally similar cluster [Ni9(N3)2(O2CMe)8((2-py)2CO2)4] containing extremely rare eta 1,mu 4-N3- groups; magnetic studies reveal that the spin grou…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTAg5PV2Mo10O40, a Heterogeneous Catalyst for Air-Based Selective Oxidation at Ambient TemperatureJeffrey T. Rhule, Wade A. Neiwert, Kenneth I. Hardcastle, Bao T. Do, and Craig L. HillView Author Information Department of Chemistry, Emory University Atlanta, Georgia 3032…
Tl$_{2}$Mn$_{2}$O$_{7}$ pyrochlores present colossal magnetoresistance (CMR) around the long range ferromagnetic ordering temperature (T$_{C}$). The character of this magnetic phase transition has been determined to be first order, by purely magnetic methods, in contrast to the second order character previously report…
The temperature dependences of spin-lattice relaxation time $T_1$ of $^{133}$Cs in CsFeCl$_3$ and $^{87}$Rb in RbFeCl$_3$ were measured in the temperature range between 1.5 K and 22 K, at various fields up to 7 T applied parallel (or perpendicular) to the c-axis, and the analysis was made on the basis of the DCEFA. Th…
The locally self-consistent real space multiple scattering technique has been applied to calculate the electronic structure and chemical binding for the c(2x2)O/Cu(001) system, as a function of $d_{O-Cu1}$ -- the height of oxygen above the fourfold hollow sites. It is found that the chemical binding between oxygen and…
The effects of adsorbates on nucleation and growth of two-dimensional islands is investigated by kinetic Monte Carlo simulations and rate equation theory. The variation of island morphology with adsorbate parameters is discussed and the temperature-dependence of island density in the case of immobile adsorbates is stu…
The relaxation dynamics of photoexcited CdSe nanoparticles (NPs) were studied with femtosecond pump−probe spectroscopy in the spectral range from 450 nm to 5 μm. Thus, the intraband relaxation of the electron and the hole were monitored with femtosecond time resolution. The transition from delocalized electronic to lo…
A Landau-Ginsburg-Devonshire-type nonlinear phenomenological theory is presented, which enables the thermodynamic description of dense laminar polydomain states in epitaxial ferroelectric thin films. The theory explicitly takes into account the mechanical substrate effect on the polarizations and lattice strains in di…
We investigate numerically the spectrum of plasmon resonances for metallic nanowires with a nonregular cross section, in the $20--50 \mathrm{nm}$ range. We first consider the resonance spectra corresponding to nanowires whose cross sections form different simplexes. The number of resonances strongly increases when the…
By use of in situ atomic force microscopy, polyelectrolyte multilayers were shown to swell on exposure to solutions containing salt. The quasilinear swelling response, used to estimate swelling coefficients and equilibria, exhibits orders of magnitude of difference, depending on the pair of polyelectrolytes constituti…