Materials Literature
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We demonstrate dispersion and exfoliation of nanotubes in two new solvents for nanotubes, cyclohexyl-pyrrolidone (CHP) and 1-benzyl-2-pyrrolidinone (NBenP). Both solvents are structural analogues of the well-known nanotube solvent N -methyl-pyrrolidone. Each solvent can disperse nanotubes at high concentrations, up to…
We applied matrix-assisted laser desorption/ionization (MALDI) for mass analysis of Au clusters stabilized by poly(vinyl-pyrrolidone) (PVP) and discovered a series of magic numbers for Au cluster size: 35 +/- 1, 43 +/- 1, 58 +/- 1, 70 +/- 3, 107 +/- 4, 130 +/- 1, and 150 +/- 2. Magic numbers smaller than approximately…
X-ray diffraction studies on Sr1-x Cax TiO3 in the temperature range 12 to 300 K reveal cubic to tetragonal (I4/mcm) antiferrodistortive and tetragonal to orthorhombic (Ic2m) polar phase transitions at ∼170 and 225, 32, 34 K, respectively, for x=0.02 and 0.04. It is shown that the polarization in the orthorhombic phas…
We discuss the crucial role played by finite-size effects and inhomogeneity on the Berezinskii-Kosterlitz-Thouless (BKT) transition in two-dimensional superconductors. In particular, we focus on the temperature dependence of the resistivity, that is dominated by superconducting fluctuations above the BKT transition te…
The composite material based on whole stem kenaf fiber (WSK) and Ecoflex (biodegradable thermoplastic) were prepared by melt blending technique and characterized. The composites were prepared using different fiber loadings and the fiber was treated with various concentrations of NaOH solution by soaking for 3 h. The c…
We theoretically showed that the spontaneous polarization in ferroelectric (FE) nanowires (NWs) can be considerably enhanced due to the nanosize confinement by the first-principles calculations. The spontaneous polarization along the wire direction in a fully relaxed PbTiO3 NW with 1.8 nm diameter is 1.26 times higher…
We explore NOT gate response in a mesoscopic ring threaded by a magnetic flux $ϕ$. The ring is attached symmetrically to two semi-infinite one-dimensional metallic electrodes and a gate voltage, viz, $V_a$, is applied in one arm of the ring which is treated as the input of the NOT gate. The calculations are based on t…
Jerky elasticity was observed by dynamical mechanical analyzer measurements in a single crystal of the shape memory alloy Cu74.08Al23.13Be2.79. Jerks appear as spikes in the dissipation of the elastic response function and relate to the formation of avalanches during the transformation between the austenite and the ma…
We demonstrate an approach to improve poly-3-hexylthiophene field effect transistors by modifying the gold contacts with monolayer thick pentacenequinone (PQ) or naphthalene (NL). The effective contact resistance is reduced by a factor of two and sixteen for interlayers of PQ and NL, respectively. The observation is a…
Quantum transport properties through single polycyclic hydrocarbon molecules attached to two metallic electrodes are studied by the use of Green's function technique. A parametric approach based on the tight-binding model is introduced to investigate the electronic transport through such molecular bridge systems. The…
By performing angle-resolved photoemission spectroscopy of the bilayer colossal magnetoresistive (CMR) manganite, ${\text{La}}_{2\ensuremath{-}2x}{\text{Sr}}_{1+2x}{\text{Mn}}_{2}{\text{O}}_{7}$, we provide the complete mapping of the Fermi-level spectral weight topology. Clear and unambiguous bilayer splitting of the…
First-principles calculations are used to investigate the electronic properties of neutral and negatively charged n-pyrrole oligomers with n= 2-18. Chains of neutral oligomers are bent while the negatively charged oligomers become almost flat due to accumulation of negative charge at the end monomers. Several isomers…
We present a minimal but crucial microscopic theory for epitaxial graphene and graphene nanoribbons on the 4H-SiC(0001) surface -- protopypical materials to explore physical properties of graphene in large scale. Coarse-grained model Hamiltonians are constructed based on the atomic and electronic structures of the sys…
A general approach to simulate the mechanical behavior of textile materials by taking into account all their constitutive elementary fibers and contacts between them is presented in this paper. A finite element code, based on an implicit solver, is develop to model samples of woven fabrics as assemblies of beams submi…
Motivated by recent transport experiments and proposed atomic-scale semiconductor devices, we present measurements that extend the reach of scanned-probe methods to discern the properties of individual dopants tens of nanometers below the surface of a silicon sample. Using a capacitance-based approach, we have both sp…
We report a size-dependent change in the morphology of superlattices self-assembled from monodisperse colloidal PbS nanocrystals. Superlattices of large (>7 nm) PbS nanocrystals showed a strong tendency to form multiply twinned face-centered cubic superlattices with decahedral and icosahedral symmetry, exhibiting crys…
Well-aligned ZnO nanoneedle and nanorod arrays were grown on an aluminum-doped zinc oxide (AZO) buffer layer by chemical vapor deposition and used as templates for making gold-coated ZnO (ZnO/Au) composite nanoarrays. The coverage of Au nanoparticles on ZnO nanoneedle and nanorod was controlled by varying the concentr…
Thermal conductance of graphene nanoribbons (GNRs) with the width varying from 0.5 to 35 nm is systematically investigated using nonequilibrium Green’s function method. Anisotropic thermal conductance is observed with the room temperature thermal conductance of zigzag GNRs up to ∼30% larger than that of armchair GNRs.…
Abstract Thermosensitive graphene‐polymer composites have been prepared by attaching poly( N ‐isopropylacrylamide) (PNIPAAm) onto the basal plane of graphene sheets via π‐π stacking. Pyrene‐terminated PNIPAAm was synthesized using reversible addition fragmentation chain transfer (RAFT) polymerization via a pyrene‐func…
The extremely high thermal conductivity of individual carbon nanotubes, predicted theoretically and observed experimentally, has not yet been achieved for large nanotube assemblies. Resistances at tube-tube interconnections and tube-electrode interfaces have been considered the main obstacles for effective electronic…