Materials Literature
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Electronic and optical properties of silicon nanocrystals are calculated and discussed within a semiempirical tight-binding approach, which allows to study systems composed of thousands of atoms. Oscillator strengths, frequency-dependent optical absorption cross sections, and static dielectric constants are investigat…
We report the preparation of p-type ZnO thin films on Al2O3(0001) substrates with phosphorus doping by pulsed laser deposition using Zn3P2 as the dopant source material. The results of the Hall effect measurements taken at room temperature indicate that the 3-mol% phosphorus-doped ZnO films thermally annealed at tempe…
We propose an isotropic three-dimensional (3D) negative-refractive-index medium using transmission lines loaded with reactive elements. The medium is referred to as the 3D dual transmission line (TL). Analytical expressions are derived which provide insight into the backward-wave propagation supported by the proposed…
We report the synthesis of aggregated diamond nanorods (ADNRs) from fullerene C60 at 20(1) GPa and 2200 °C using a multianvil apparatus. Individual diamond nanoroads are of 5–20 nm in diameter and longer than 1μm. The x-ray and measured density of ADNRs is ∼0.2%–0.4% higher than that of usual diamond. The extremely hi…
This paper consists of an investigation of the structural arrangement of the sp2 phase in amorphous unhydrogenated carbon nitride (a-CNx) films and its effect on their physical properties. The a-CNx films (0.16<x<0.25) were synthesized using a hybrid deposition system combining laser ablation of graphite…
We provide an experimental demonstration of novel form-birefringent computer-generated holograms at wavelengths of 1.55 and 10.6 microm. These novel devices utilize a 2-D array of cells that can be fabricated with a single lithographic step. Each cell contains a subwavelength binary grating whose orientation controls…
In this paper we will report an experimental approach for directly determining the photogenerated current at individual junctions within the triple junction solar cell. The method is based on the measurement of different current-voltage curves; one with the usual illumination system, normally AM0 or AM1.5G, and the ot…
We present anisotropic, zero applied magnetic field, temperature dependent resistivity measurements on hexagonal, non-magnetic, YPtIn and LuAgGe single crystals. For these materials the in-plane resistivity, $ρ_{ab}$, is significantly higher than the $c$ - axis one, $ρ_c$, with $ρ_{ab}/ρ_c \approx 1.4$ for YPtIn and $…
The expression of the free energy density of a classical crystalline system as a gradient expansion in terms of a set of order parameters is developed using classical density functional theory. The goal here is to extend and complete an earlier derivation by L{ö}wen et al (Europhys. Lett.9, 791, 1989). The limitations…
The amount of screening of a proton in a metal, migrating under the influence of an applied electric field, is calculated using different theoretical formulations. First the lowest order screening expression derived by Sham (1975) is evaluated. In addition 'exact' expressions are evaluated which were derived according…
A cluster consisting of many atoms or molecules may be considered, in some circustances, to be a single large molecule with a well defined polarizability. Once the polarizability of such a cluster is known, one can evaluate certain properties, e.g. the cluster's van der Waals interactions, using expressions derived fo…
We studied the crystal and magnetic structure of the ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ compound for $(0.11\ensuremath{\leqslant}x\ensuremath{\leqslant}0.175)$ using stoichiometric samples. For $x<0.13$ the system's ground state is insulating canted antiferromagnetic. For $0.13\en…
The photocatalytic characteristics of the tetrapod-branched ZnO nanostructures synthesized by thermal evaporation method are investigated. The fitting of absorbance maximum plot versus time indicates an exponential decay, suggesting the photodegradation of Rhodamine B catalyzed by the ZnO nanotetrapod is a pseudo firs…
The intraband relaxation between the 1Pe and 1Se state of CdSe colloidal quantum dots is studied by pump-probe time-resolved spectroscopy. Infrared pump-probe measurements with approximately 6-ps pulses show identical relaxation whether the electron has been placed in the 1Se state by above band-gap photoexcitation or…
A series of copper-doped zinc oxide films were grown by pulsed-laser ablation. Films grown under conditions that produced n-type ZnO were nonmagnetic while those grown under conditions that produced p-type were ferromagnetic with a Curie temperature above 350 K. The magnetic moment per copper atom decreased as the cop…
The electric transport properties of an individual vertical multiwall carbon nanotube (MWCNT) were studied in situ at room temperature in a scanning electron microscope chamber. It was found that the single MWCNT has a large current-carrying capacity, and the maximum current can reach 7.27 mA. At the same time, a very…
The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is…
We present a detailed electron diffraction study of individual single-walled carbon nanotubes. A novel sample preparation procedure provides well-separated, long and straight individual single-shell nanotubes. Diffraction experiments are carried out at 60kV, below the threshold for knock-on damage in carbon nanotubes.…
We study the temporal growth pattern of surface fluctuations on a series of spinodally unstable polymer films where the degree of instability is controlled by the film thickness. For films in the deep spinodal region, the growth rate function of the surface modes as a function of the wavevector,, fits well to the mean…
The first synthesis of a series of glutamic acid based dendrimers having a central ferrocene core is described. The materials were fully characterized spectroscopically and display strong intramolecular H-bonding. This H-bonding can be disrupted with DMSO. The redox properties of the core are attenuated by the increas…