Materials Literature
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We determined experimentally two critical points in elastic electron scattering by argon where the differential cross section (DCS) attains its smallest values. The points were found to be at and at . Special attention was given to improve the angular resolution in order to determine the exact positions of the minima.…
A novel graft copolymer of unsaturated propylene with methyl methacrylate (uPP-g-PMMA) was added to binary blends of isotactic polypropylene (iPP) and atactic poly(methyl methacrylate) (aPMMA) with a view to using such a copolymer as a compatibilizer for iPP/aPMMA materials. Optical microscopy (OM), scanning electron…
A new silicon-containing maleimide monomer, N-(tert-butyldimethylsilyloxy)-maleimide (SiOMI) has been synthesized. SiOMI was radically copolymerized with styrene derivatives (XSt) to obtain alternating copolymers, P(SiOMI/XSt), in high conversions. The copolymers have high glass transition temperatures above 190°C, an…
The effect of toluene diisocyanate (TDI) index on the physical properties, structure, and morphology of flexible slabstock polyurethane foams was investigated. Foams based on a 2700 molecular weight triol, 6 pph water, and varying amounts of an 80/20 mixture of 2,4- and 2,6-TDIs were characterized using a number of ph…
In this work, the melt crystallization of immiscible blends of isotactic polypropylene (iPP) and branched polyethylenes (PE) was followed by oscillatory shear measurements during controlled cooling. All the blends contained 20% iPP finely dispersed in several ethylene/α-olefin copolymer matrices (with and without a nu…
Stokesian Dynamics has been used to investigate the origins of shear thickening in concentrated colloidal suspensions. For this study, we considered a monolayer suspension composed of charge-stabilized non-Brownian monosized rigid spheres dispersed at an areal fraction of ϕ a =0.74 in a Newtonian liquid. The suspensio…
We present first-principles band calculations as well as structural optimization of the orthorhombic K$_1$C$_{60}$ polymerized phase. We found three-dimensional inter-fullerene bonding/anti-bonding characters consisting of $t_{1u}$ molecular orbitals with $p$-like symmetry in the conduction bands. The formation of the…
Spin polarized B12 nuclei were produced in a B11(d,p)12B nuclear reaction and recoil implanted into a type Ib diamond sample at doses below 1011 cm−2. β-radiation detected nuclear magnetic resonance spectra were measured directly after implantation at sample temperatures ranging from 300 to 800 K. The polarization asy…
We formulate and apply the EOM-CC method to determine, recursively, any order and any process frequency dependent hyperpolarizability. Combining the theory with systematically chosen n-aug-cc-pVXZ bases, we attempt to converge to the basis set limit. Our best “relaxed” result is −9.8±0.5 a.u. for βSHG compared to an e…
Domain–wall contribution to the longitudinal piezoelectric coefficient d33 is calculated theoretically for prepolarized tetragonal ferroelectric thin films epitaxially grown on cubic substrates. To that end, translational vibrations of ferroelastic 90° domain walls induced by a weak measuring electric field are analyz…
We propose a hierarchical classification of kink species in dislocation cores which considers three sources of broken symmetry, host lattice structure, character of the dislocation, and core reconstruction effects. Kink multiplicity in bcc and diamond cubic lattices is examined and verified directly by atomistic calcu…
Computer simulations of the short-time, vibrational dynamics of the network-forming ionic melts, LaCl3 and ZnCl2, and of their mixtures with network-breaking alkali halides are described. In the mixtures, high frequency peaks in the vibrational density of states are shown to be describable in terms of the normal coord…
Efficient recording of polarization gratings in dye-doped liquid crystals is reported. By exploiting the effect of light-induced anchoring of the molecular director, it has been possible to write stable holographic gratings with a diffraction efficiency of 8% at a resolution of 1000 lines/mm. The required surface ener…
Barium ferrite (BaFe12O19) was elaborated and investigated in this work in terms of its capacitance-temperature characteristics. The curve taken at the fixed frequency of 1 kHz shows anomalous negative values of capacitance over the high-temperature regime. A complete analysis of this effect is carried out by performi…
A new technology utilizing a self-limiting mechanism for the Bi content is demonstrated for Bi2Sr2CuOy (2201) thin film growth by an atomic layer controlled molecular beam epitaxy. This technology is based on peculiar behavior of the Bi sticking coefficient that depends on the kinds of oxide thin films to be grown. Wh…
Vanadium dioxide thin films have been synthesized by pulsed laser deposition from pure vanadium metal targets. The electrical characteristics of these films were measured as a function of externally applied strain, based on three-point bend geometry. It is observed that strain significantly affects the resistance of t…
The room temperature thermal diffusivity evolution of electrochemically formed porous silicon as a function of the etching time is investigated. The measurements were carried out using the open-cell photoacoustic technique. The experimental data were analyzed using a composite two-layer model. The results obtained str…
Direct experimental evidence of half-metallic density of states (DOS) is observed by scanning tunneling spectroscopy on ferromagnetic ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$, which exhibits colossal magnetoresistance (CMR). Tunneling conductance data taken at 77 K, well below the Curie temperature $…
The spin dependence of the lifetime of electrons excited in ferromagnetic cobalt is measured directly in a femtosecond real-time experiment. Using time- and spin-resolved two photon photoemission, we show that the lifetime of majority-spin electrons at 1 eV above the Fermi energy is twice as long as that of minority-s…
The low-energy theory for single-wall carbon nanotubes including Coulomb interactions is derived and analyzed. It describes two fermion chains without interchain hopping but coupled in a specific way by the interaction. The strong-coupling properties are studied by bosonization, and consequences for experiments on sin…