Materials Literature
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Abstract This article presents original multi‐scale porous nanocrystalline transition‐metal oxide materials (MO 2 , where M = Ti, Zr, Ce) that have many potential applications. They were prepared through a one step method that combines sol–gel chemistry, multi‐scale templating approaches, aerosol processing, and speci…
We present studies of the photoluminescence (PL), absorption and Raman scattering from poly[2,7-(9,9'-bis(2-ethylhexyl))fluorene] under hydrostatic pressures of 0-100 kbar at room temperature. The well-defined PL and associated vibronics that are observed at atmospheric pressure change dramatically around 20 kbar in t…
We introduce the Korringa-Kohn-Rostocker non-local coherent potential approximation (KKR-NLCPA) for describing the electronic structure of disordered systems. The KKR-NLCPA systematically provides a hierarchy of improvements upon the widely used KKR-CPA approach and includes non-local correlations in the disorder conf…
In this paper we present some of the most important magnetic and transport properties of mixed-valence manganite nanoparticles. The samples were prepared by a sol–gel method, which allows us to control particle size and, in this way, to obtain new properties of the archetypal ferromagnetic- metallic compound La 2/3 Ca…
A major challenge to the development of a fundamental understanding of transport and retardation mechanisms of trace metal contaminants (<10 ppm) is their identification and characterization at the nanoscale. Atomic-scale techniques, such as conventional transmission electron microscopy, although powerful, are limited…
CdSe hollow spherical assemblies composed of 5 nm nanoparticles have been synthesized sonochemically. During the process, amorphous Cd(OH) 2 , which acts as the in‐situ template, directs the growth of primary CdSe nanoparticles on its surface and their assembly into hollow spherical structures. The Figure is a schemat…
We study theoretically diffusion of one-dimensional Frenkel excitons in J-aggregates at temperatures that are smaller or of the order of the J-band width. We consider an aggregate as an open linear chain with uncorrelated on-site (diagonal) disorder that localizes the exciton at chain segments of size smaller than the…
YMnO3 thin films have been grown on n - type Si substrates by nebulized spray pyrolysis in the Metal - Ferroelectric - Semiconductor (MFS) configuration. The C-V characteristics of the film in MFS structure exhibit hysteretic behavior consistent with the polarization charge switching direction, with the memory window…
Abstract Polyhedral oligomeric silsesquioxanes (POSS) anchored to poly(2‐methoxy‐5‐(2‐ethylhexyloxy)‐1.4‐phenylenevinylene) (MEH‐PPV) (MEH‐PPV–POSS), and to poly(9,9‐dihexylfluorenyl‐2,7‐diyl) (PFO) (PFO–POSS) were synthesized. Compared with the corresponding parent polymers, MEH‐PPV and PFO, MEH‐PPV–POSS and PFO–POSS…
Hydrogen incorporation depths of &gt;25 μm were obtained in bulk, single-crystal ZnO during exposure to H2 plasmas for 0.5 h at 300 °C, producing an estimated diffusivity of ∼8×10−10 cm2/V⋅s at this temperature. The activation energy for diffusion was 0.17±0.12 eV, indicating an interstitial mechanism. Subsequent…
The ability to grow carbon nanotubes/nanofibres (CNs) with a high degree of uniformity is desirable in many applications. In this paper, the structural uniformity of CNs produced by plasma enhanced chemical vapour deposition is evaluated for field emission applications. When single isolated CNs were deposited using th…
We have synthesized ferromagnetic Heusler alloy Ni2FeGa using the melt-spinning technique. The Ni2FeGa ribbon, having a high chemical ordering L21 structure, exhibits a thermoelastic martensitic transformation from cubic to orthorhombic structure at 142 K and a premartensitic transformation. The alloy has a relatively…
Sulfonated multiwalled carbon nanotubes (MWNT‐(OSO 3 H) n ) can act simultaneously as a dopant and template for the formation of conducting polyaniline(PANI) nanostructures. By controlling the aniline/MWNT‐(OSO 3 H) n ratio, two kinds of nanotubes—PANI‐coated MWNT‐(OSO 3 H) n nanotubes and PANI nanotubes doped with MW…
Cadmium selenide nanocrystals are reproducibly synthesized at high-temperature in continuous flow, chip-based microfluidic reactors and exhibit size distributions comparable to those for conventional macroscale syntheses. Nanocrystal size, probed by fluorescence, is precisely controlled by independently varying the te…
Reverse bias current–voltage measurements of ∼100-μm-diameter gold Schottky contacts deposited on as-received, n-type ZnO(0001̄) wafers and those exposed for 30 min to a remote 20% O2/80% He plasma at 525±20 °C and cooled either in vacuum from 425 °C or the unignited plasma gas have been determined. Plasma cleaning re…
Quantized Pancharatnam–Berry phase diffractive optics using computer-generated space-variant subwavelength dielectric grating is presented. The formation of the geometrical phase is done by discrete orientation of the local subwavelength grating. We discuss a theoretical analysis and experimentally demonstrate a quant…
Abstract We have shown recently that the use of high‐aspect‐ratio inorganic nanorods in conjunction with conjugated polymers is a route to obtaining efficient solar cells processed from solution. Here, we demonstrate that the use of binary solvent mixtures in which one of the components is a ligand for the nanocrystal…
Defects such as oxygen vacancies play a crucial role in the surface properties of transition metal oxides. By means of time-resolved, high-resolution scanning tunneling microscopy, we unraveled an adsorbate-mediated diffusion mechanism of oxygen vacancies on rutile TiO2(110). Adsorbed oxygen molecules mediate vacancy…
Carbon nanotube field-effect transistors commonly comprise nanotubes lying on SiO 2 surfaces exposed to the ambient environment. It is shown here that the transistors exhibit hysteresis in their electrical characteristics because of charge trapping by water molecules around the nanotubes, including SiO 2 surface-bound…
Abstract Functional oxides are the fundamentals of smart devices. This article reviews novel nanostructures of functional oxides, including nanobelts, nanowires, nanosheets, and nanodiskettes, that have been synthesized in the authors’ laboratory. Among the group of ZnO, SnO 2 , In 2 O 3 , Ga 2 O 3 , CdO, and PbO 2 ,…