Materials Literature
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Transport properties of SrTiO3-channel field-effect transistors with parylene organic gate insulator have been investigated. By applying gate voltage, the sheet resistance falls below R◻∼10kΩ at low temperatures, with carrier mobility exceeding 1000cm2∕Vs. The temperature dependence of the sheet resistance taken under…
Solid solutions in the (x)PbTiO3–(1−x)Bi(Zn3∕4W1∕4)O3 system have been examined by x-ray diffraction, dielectric measurements, and thermal analysis. Bi(Zn3∕4W1∕4)O3 increases the tetragonality and Curie temperature of PbTiO3 which reach a value of 1.08 and 530°C, respectively, at the limit of the single-phase perovski…
Field-effect transistors made of individual CdSe nanoribbons were fabricated and characterized. The CdSe nanoribbon showed n-type semiconducting characteristics, while the transistors revealed a threshold voltage of 20.9V, an on-off ratio >104, and an electron mobility of 9.6cm2∕Vs in the dark. CdSe nanoribbons…
Abstract The effect of onium‐ion exchanged montmorillonite clay (organoclay) on the rheology and physical properties of maleated ethylene–octene copolymer and ethylene–propylene rubber elastomers has been examined. The formation of a nanocomposite hybrid, containing substantial amounts of exfoliated clay, was accompan…
We present a model for electromagnetic enhancements in surface enhanced Raman optical activity (SEROA) spectroscopy. The model extends previous treatments of SEROA to substrates, such as metal nanoparticles in solution, that are orientationally averaged with respect to the laboratory frame. Our theoretical treatment c…
The authors studied the Li concentration dependence of the internal efficiency and extraction efficiency contributions to the enhanced photoluminescence (PL) brightness of the Li-doped Y2O3:Eu thin films. Experiments conducted with excitation at a wavelength of 254nm showed that adding 20mol% Li2CO3 to conventional Y2…
The nature of room-temperature ferromagnetism in diluted magnetic semiconductors, ZnO:M (M is Ni, Co, Fe, etc.), remains in debate, most likely because previous theoretical and experimental studies have excluded the magnetic contribution from secondary phases of transition metal oxide nanocrystals including NiO and Co…
Quasi-two-dimensional bidisperse amorphous systems of steel beads are fluidized by a uniform upflow of air, so that the beads roll on a horizontal plane. The short-time ballistic motion of the beads is stochastic, with non-Gaussian speed distributions and with different average kinetic energies for the two species. Th…
In this study, a series of smart polymer fibers with a shape memory effect were developed. Firstly, a set of shape memory polyurethanes with varying hard-segment content were synthesized. Then, the solutions of the shape memory polyurethanes were spun into fibers through wet spinning. The thin films of the polyurethan…
Optical absorption and photoluminescence techniques were used to investigate the energy band gap of CdSe∕ZnS core/shell nanocrystals matrixed into a resin. The band gap is measured as a function of temperature for several samples with different nanocrystal diameters. Debye and Einstein temperatures were obtained by fi…
The origin of the species: The first principles method reveals the origin and activity of a heterogeneous Au monomer in the catalysis of a selective 1,3-butadiene hydrogenation. The active Au species is an AuI complex, produced from AuIII in situ by reduction, stabilized by ZrO2 defects. The high catalytic activity an…
Visible quantum cutting under excitations at 212 and 172nm in a green-emitting phosphor K2GdF5:Tb3+ (11%) via a downconversion mechanism is investigated. The authors measured the vacuum ultraviolet (VUV) excitation and emission spectra and proposed mechanisms to rationalize the quantum-cutting effect. One short-UV or…
A two-dimensional electron gas was observed in Zn polar ZnMgO∕ZnO (ZnMgO on ZnO) heterostructures grown by radical source molecular beam epitaxy. The electron mobility of the ZnMgO∕ZnO heterostructures dramatically increased with increasing Mg composition and the electron mobility (μ∼250cm2∕Vs) at RT reached a value m…
The authors report on the assembly and electrical properties of ultralong copper oxide (CuO) nanofibers prepared by electrospinning method. The prepared CuO nanofibers were polycrystalline, with diameter of ∼60nm and length over 100μm. By a specially designed fiber collector, single CuO nanofiber field-effect transist…
In the absence of scientific clarity about the potential health effects of occupational exposure to nanoparticles, a need exists for guidance in decisionmaking about hazards, risks, and controls. An identification of the ethical issues involved may be useful to decision makers, particularly employers, workers, investo…
Using quantum mechanics (QM, Density Functional Theory) we show that all four phases of barium titanate (BaTiO(3)) have local Ti distortions toward 111 (an octahedral face). The stable rhombohedral phase has all distortions in phase (ferroelectric, FE), whereas higher temperature phases have antiferroelectric coupling…
The properties of hot dense helium at megabar pressures were studied with two first-principles computer simulation techniques, path integral Monte Carlo and density functional molecular dynamics. The simulations predicted that the compressibility of helium is substantially increased by electronic excitations that are…
We report on the dc and pulsed electric field sensitivity of the resistance of mixed valent Mn-oxide-based ${\mathrm{La}}_{5∕8\ensuremath{-}y}{\mathrm{Pr}}_{y}{\mathrm{Ca}}_{3∕8}{\mathrm{MnO}}_{3}$ $(y\ensuremath{\sim}0.4)$ single crystals as a function of temperature. The low-temperature regime of the resistivity is…
Raw [as-prepared (AP)] and purified single-walled carbon nanotubes (SWNTs) were utilized for the preparation of SWNT-epoxy composites. Purified functionalized SWNTs provide a significantly greater enhancement of the thermal conductivity, whereas AP-SWNTs allow the best electrical properties because of their ability to…
Ni/hexagonal-ferrite (Co2Z or Zn2Y barium ferrites)/polymer composites were prepared for electromagnetic interference (EMI) shielding materials. In comparison with the hexagonal-ferrite/polymer or Ni/polymer composites, such three-phase composites exhibit excellent microwave absorption properties in the X-band frequen…