Materials Literature
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Stoichiometric and cation-deficient magnetite Fe3−δO4 and γ-Fe2O3 particles have been prepared by the chemical method followed by heat treatments. The magnetic and structural properties were studied using neutron diffraction, magnetic measurements, and Mössbauer spectroscopy. Charge ordering of Fe3+ and Fe2+ and latti…
This paper reports on results taken to validate the extension to the theory of the magnetomechanical effect reported recently. This theory is based on a “law of approach” but the underlying equations have been generalized to include linear and nonlinear terms which are analogous to those in the well-known Rayleigh law…
Cubic magnetocrystalline anisotropy constants, K1 and K2, for Fe1−xGax alloys were measured using magnetization curves with x=0.05, 0.125, 0.14, 0.18, and 0.20. Thin circular (110) disks all with 〈100〉, 〈110〉, and 〈111〉 in the plane of the disk were used to measure K1 and K2. K1 was also measured with (100) circular d…
Vertically aligned carbon nanotubes were synthesized by plasma enhanced chemical vapor deposition using nickel as a metal catalyst. High resolution transmission electron microscopy analysis of the particle found at the tip of the tubes reveals the presence of a metastable carbide Ni3C. Since the carbide is found to de…
A novel zeolite–ceramic composite monolith with a hierarchical bimodal (nano‐, macroscale) pore system (see Figure) has been prepared by coating the internal cell walls of microcellular polymer‐derived ceramic foams (cell size ∼ 8 μm) with a thin layer of MFI‐type zeolite. Applications are envisaged as microreactors a…
Tuning of a dye‐doped cholesteric liquid crystal mirrorless laser in the violet– ultraviolet wavelength range is achieved using two different strategies for controlling the periodicity of the cholesteric helical structures. Both methods are shown produce a shift of the lasing wavelength by 30–40 nm, and smooth variati…
Abstract The thermal conductivity of nanometric objects or nanostructured materials can be determined using nonequilibrium molecular dynamics (NEMD) simulations. The technique is simple in its principle, and resembles a numerical guarded hot plate experiment. The “sample” is placed between a hot source and a cold sour…
The properties of the ZnO thin films prepared by metalorganic vapor phase epitaxy under various oxygen partial pressures were thoroughly studied. It was found that the conduction type in undoped ZnO epilayers could be controlled by adjusting the family VI precursor, oxygen partial pressure during growth. The films wer…
Titanium dioxide (TiO2) thin films were deposited on unheated quartz (SiO2) substrates in “pure oxygen” plasma by reactive radio-frequency (rf) magnetron sputtering. The structural and optical properties of deposited films were systematically studied by changing the deposition parameters, and it was very recently foun…
Several classes of materials are currently under investigation as potential high-spin-polarization materials. Unfortunately, the proposed half-metallic materials, including the semi-Heusler alloys, the manganese perovskites, and the “simpler” oxides such as chromium dioxide and magnetite, suffer from fundamental limit…
The physical behavior of condensed matter can be drastically altered in the presence of interfaces. Using a high-energy x-ray transmission-reflection scheme, we have studied ice-SiO2 model interfaces. We observed the formation of a quasiliquid layer below the bulk melting temperature and determined its thickness and d…
First-principles calculations based on the generalized gradient approximation to the density functional theory are performed to explore the global geometries, ground-state spin multiplicities, relative stabilities, and energetics of neutral and anionic V(n)(Bz)(m) (n=1-3, m=1-4, with n<m) complexes. The calculated res…
Abstract Photocatalytic decomposition of H2O over NiO-loaded Ga2O3, one of the oxides with a d10 electron configuration, was confirmed. Without pretreatment, both H2 and O2 have been continuously produced in stoichiometric amounts under the irradiation of high pressure Hg lamp.
Irradiance dependence of excitonic nonlinear absorption in cadmium sulfide (CdS) nanocrystals has been studied by using Z-scan method with nanosecond laser pulses. The wavelength dependence of nonlinear absorption has also been measured near the excitonic transition of 1S(e)–1S3/2(h). We observe the saturable absorpti…
We have studied the electronic properties, in relation to their structural properties, of monolayers of 1-octadecene attached on a hydrogen-terminated (111) silicon surface. The molecules are attached using the free-radical reaction between C=C and Si-H activated by an ultraviolet illumination. We have compared the st…
We report on the synthesis of low doping Zn1−xCoxO (0&lt;x&lt;0.1) thin films on (0001)-Al2O3 substrates. The films were prepared in an oxidizing atmosphere, using the pulsed-laser deposition technique starting from Zn and Co metallic targets. We first studied the influence of the strains of ZnO and their stru…
We report detailed shape measurements of the tips of three-dimensional ammonium chloride dendrites grown from supersaturated aqueous solution. For growth at small supersaturation, we compare two different models: parabolic with a fourth-order correction, and power law. Neither is ideal, but the fourth-order fit appear…
We have found that various Mn oxides have the universal resistivity and thermopower in the high temperature limit. The resistivities and thermopowers of all the samples go toward constant values of 7±1 mΩ cm and −79±3 μV/K, which are independent of carrier density and crystal structures. We propose that the electric c…
The effect of layer-by-layer heterostructuring and epitaxial strain on lattice instabilities and related ferroelectric properties is investigated from first principles for the $[001]\ensuremath{-}({\mathrm{PbTiO}}_{3}{)}_{1}({\mathrm{PbZrO}}_{3}{)}_{1}$ superlattice and pure ${\mathrm{PbTiO}}_{3}$ on a cubic substrate…
Polymer diodes require cathodes that do not corrode the polymer but do have low work function to minimize the electron injection barrier. First-principles calculations demonstrate that the work function of the (1000) surface of the compound Ca2N is half an eV lower than that of the elemental metal Ca (2.35 vs. 2.87 eV…