Materials Literature
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Interest in developing an oxidizer matrix for reaction with nano-aluminum for energy-intensive applications involving explosives and propellants have led to the development of an aerosol-based sol−gel method (Aero-sol−gel) for preparing nanoporous iron-oxide nanoparticles with high internal surface area. We have emplo…
Single-wall and multiwall carbon nanotubes at high temperature are irradiated with the focused electron beam in an electron microscope. Nanotubes can be tailored with monolayer precision, and new morphologies of nanotubes are created. Atoms from layers of multiwall tubes can be removed and the tubes can be bent by a p…
ZnO films grown by pulsed-laser deposition on c-plane Al2O3 substrates were annealed at temperatures up to 600 °C to produce n-type carrier concentrations in the range 7.5×1015–1.5×1020 cm−3. After high-dose (3×1016 cm−2) Mn implantation and subsequent annealing at 600 °C, all the films show n-type carrier concentrati…
Many optoelectronic devices could achieve much higher efficiencies if the excess energy of electrons excited well above the conduction band minimum could be used to promote other valence electrons across the gap rather than being lost to phonons. It would then be possible to obtain two electron–hole pairs from one. In…
The optical absorption and charge transport properties of a series of discotic molecules consisting of peripherally alkyl-substituted polycyclic aromatic cores have been investigated for core sizes, n, of 24, 42, 60, 78, 96, and 132 carbon atoms. In dilute solution, the wavelength maximum of the first absorption band…
The adsorption of thin water overlayers on the (101) surface of TiO 2 anatase has been studied through Car-Parrinello molecular dynamics (CPMD) simulations. We compared the structural and dynamic properties of one and two H 2 O monolayers adsorbed on defect-free and partially reduced surfaces at 160 K. As for an isola…
We report the basic thermodynamic properties of the new geometrically frustrated beta-pyrochlore bulk superconductor RbOs2O6 with a critical temperature Tc = 6.4 K. Specific heat measurements are performed in magnetic fields up to 12 T. The electronic density of states at the Fermi level in the normal state results in…
We report the observation of large ($\sim 40%$) laser-induced above-bandgap transparency in GaAs at room temperature. The induced transparency is present only during the pulse width of the driving midinfrard laser pulses and its spectral shape is consistent with a laser-induced blue shift of the band edge. Our simulat…
Thin films of Co2MnSi have been grown on a-plane sapphire substrates from three elemental targets by dc magnetron cosputtering. These films are single phase, have a strong (110) texture, and a saturation magnetization of 4.95μB/formula unit at 10 K. Films grown at the highest substrate temperature of 715 K showed the…
In this Communication, we show that nanometer scale control of semiconducting polymer chain conformation is possible using host/guest chemistry in highly ordered and macroscopically oriented thin films of mesoporous silica. This control leads to a thin film composite material that is optically transparent, densely fil…
An ultrahigh vacuum apparatus for the deposition of thin films with controlled three-dimensional nanometer-scale structure is described. Our system allows an alternate, faster, cheaper way of obtaining nanoscale structured thin films when compared to traditional procedures of patterning and etching. It also allows cre…
Negative refraction can occur at the interface between vacuum and an indefinite medium—an anisotropic medium for which not all elements of the permittivity and permeability tensors have the same sign. We show experimentally and via simulations that a metamaterial composed of split ring resonators, designed to provide…
The electronic structure and chemical bonding of B 7 - and B 7 have been investigated using photoelectron spectroscopy and ab initio calculations. Complicated, but well-resolved, photoelectron spectra were obtained for B 7 - at several photon energies and were shown distinctly to contain contributions from different B…
The phase transformation dynamics induced in Ge2Sb2Te5 films by picosecond laser pulses were studied using real-time reflectivity measurements with subnanosecond resolution. Evidence was found that the thermal diffusivity of the substrate plays a crucial role in determining the ability of the films to crystallize and…
Using thermoelectric compatibility, efficient thermoelectric generators are rationally designed. With examples, compatible and incompatible systems are explained and materials proposed for targeted development. The compatibility factor explains why segmentation of (AgSbTe2)0.15(GeTe)0.85 (TAGS) with SnTe or PbTe produ…
Water-soluble magnetite nanocrystals of different sizes have been prepared by a one-pot reaction through thermal decomposition of ferric triacetylacetonate in 2-pyrrolidone.
In this paper a novel synthetic route of pure MFe 2 O 4 (M = Mg, Co, and Ni) spinel ferrites is reported. The key feature of this method is using a single molecular precursor. The pure spinel ferrites can be obtained by calcination of tailored hydrotalcite-like layered double hydroxides (LDHs) of the type [M 1 - X - Y…
Boron nitride (BN) nanotubes have the same nanostructure as carbon nanotubes but are found to exhibit significant resistance to oxidation at high temperatures. Our systematic study has revealed that BN nanotubes are stable at 700 °C in air and that some thin nanotubes (diameter less than 20 nm) with perfect multiwalle…
The first example of ferromagnetism in a compound crystallizing with the filled beta-manganese structure is reported. Magnetometry and neutron diffraction show that Fe 1.5 Pd 0.5 Mo 3 N is ferromagnetic below 160 K, with a saturation magnetization of 2.44 μ B /formula unit which is associated with the Fe/Pd sublattice…
A wet-chemical deposition method of synthesizing highly oriented, transparent ZnO films on a crystalline template is described. Multi-nucleation and the subsequent growth of ZnO nanodomains at an early stage of wet-chemical deposition leads to the formation of thin hexagonal platelike ZnO crystals spread over the temp…