Materials Literature
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We use molecular-dynamics computer simulations to study the dynamics of amorphous (Na2O)2(SiO2). We find that the Na ions move in channels embedded in a SiO2 matrix. The characteristic distance between these channels gives rise to a prepeak in the structure factor at q approximately equal to 0.95 A(-1). The dynamics o…
We report the characterization of electronic shell filling in metallic single-walled carbon nanotubes by low-temperature transport measurements. Nanotube quantum dots with average conductance approximately (1-2)e(2)/h exhibit a distinct four-electron periodicity for electron addition as well as signatures of Kondo and…
The study of randomness in low-dimensional quantum antiferromagnets is at the forefront of research in the field of strongly correlated electron systems, yet there have been relatively few experimental model systems. Complementary neutron scattering and numerical experiments demonstrate that the spin-diluted Heisenber…
We have measured the thermoelectric power (S) of high purity single-walled carbon nanotube mats as a function of temperature at various hydrostatic pressures up to 2.0 GPa. The thermoelectric power is positive, and it increases in a monotonic way with increasing temperature for all pressures. The low temperature (T <…
Using the Boltzmann equation for electrons in metals, we show that the optical phonons soften and have a dispersion due to screening in agreement with the results reported recently [M. Reizer, Phys. Rev. B {\bf 61}, 40 (2000)]. Additional phonon damping and frequency shift arise when the electron--phonon interaction i…
Multifilamentary MgB2/Fe wires and tapes with high transport critical current densities have been fabricated using a straightforward powder-in-tube (PIT) process. After annealing, we measured transport jc values up to 1.1 * 105 A/cm2 at 4.2 K and in a field of 2 T in a MgB2/Fe square wire with 7 filaments fabricated b…
We demonstrate how three "state-of-the-art" techniques may be combined to build a bridge between atomistics and microstructure: (1) first-principles calculations, (2) a mixed-space cluster expansion approach, and (3) the diffuse-interface phase-field model. The first two methods are used to construct the driving force…
We propose a new mechanism of indirect exchange interaction, which can be responsible for the ferromagnetic ordering in Mn-doped semiconductors (like GaMnAs) at low carrier concentration. The mechanism is based on the interplay of the hybridization of band states (conduction or valence) with localized impurity (donor…
We study, using noise reduction techniques, layer by layer epitaxial growth in limited mobility solid-on-solid nonequilibrium surface growth models, which have been introduced in the context of kinetic surface roughening in ideal molecular beam epitaxy. Multiple hit noise reduction and long surface diffusion length le…
A new ternary Na–Sn–O compound, Na4Sn3O8, has been synthesized from a mixture of Na2CO3 and SnO2 by heating at 1270–1400 °C for 6–24 h in air using a powder bed. The crystal structure of Na4Sn3O8 has been refined by the Rietveld analysis of the powder X-ray diffraction data. Na4Sn3O8 crystallizes in the cubic system (…
Abstract Different adsorber and ion exchange resins have been sonicated with ultrasound of different frequencies in a fixed bed. Afterwards, the sonicated particles were investigated by scanning electron and light microscopy. Also, different mechanical properties, like fracture load, maximum flattening and Young's mod…
We have found that the long wavelength fundamental absorption edge of CdS x Se 1x nanocrystals grown in an oxide glass follows to the generalized Urbach rule that takes into account both the dynamic (phonon induced) and static (defect induced) disorders of nanocrystal lattice. Temperature intervals with the dominant i…
This work attempts an estimation of partial discharge inception and extinction voltages (PDIV and PDEV) of sheet samples of solid dielectrics due to void inclusions of different sizes using an ANN. The effect of void dimensions and also the dielectric thickness of three common insulating materials, namely, Leatherite…
The impregnation of a fluorescent probe [4-(hexadecylamino)-7-nitrobenz-2-oxa-1,3-diazole or NBD] into polypropylene from supercritical carbon dioxide is presented. Confocal microscopy was combined with traditional thermodynamic and spectroscopic studies to demonstrate distinct differences between supercritical fluid…
This paper reports a crystallographic and EPR study of pseudo-Jahn–Teller fluxionality in [Cu(L1)2][BF4]2 (1; L1 = 2,6-dipyrazol-1-ylpyridine). For 50 ≤ T ≤ 350 K, the Cu(II) ion in crystalline 1 is fluxional, with its axis of pseudo-Jahn–Teller elongation being disordered about the two N{pyrazole}–Cu–N{pyrazole} axes…
We propose a new picture for superconductivity in kappa-(BEDT-TTF)2X salts arguing that small- q electron-phonon scattering dominates the pairing. We reproduce the distinct X-shaped d-wave gap reported recently by magneto-optic measurements and we argue that the softness of the momentum structure of the gap and the ne…
Abstract Poly(styrene‐maleic anhydride)‐montmorillonite nanocomposites were prepared by intercalation of layered montmorillonite with the polymer ions. Synthetic approaches including polymerization and phosphonium salt formation have been used for polymer intercalation and dispersion of the host layers in the polymer…
The crystal and magnetic structures of the two related phases, Sr2MnGaO5 and Ca2MnAlO5 are reported. Rietveld analysis of neutron powder diffraction has revealed that both phases adopt the brownmillerite structure. Subtle differences in structure lead to the structure of Sr2MnGaO5 being best described by the space gro…
Abstract The solubility of 1‐hexene was measured for linear low‐density polyethylenes (LLDPEs) produced over a heterogeneous Ziegler–Natta catalyst, Mg(OEt) 2 /DIBP/TiCl 4 –TEA (ZN), and over a homogeneous metallocene catalyst, (2‐MeInd) z ZrCl 2 –MAO (MT). The 1‐hexene solubility in LLDPEs was well represented by the…
Abstract The synthesis of liquid single crystal hydrogels (“LSCH”) in suitable molds offers an innovative concept to realize bifocal contact‐ or intraocular‐lenses. LSCH combine the properties required for applications as bifocal ophthalmic lenses: the soft and water‐containing hydrogel enables oxygen permeation and e…