Materials Literature
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Six-coordinated Fe(II) complex ions [FeL 3 ] 2+ (L = en, amp, bpy, dmbpy, phen, and dmphen), prepared in a supercage of zeolite Y, were characterized by UV−vis, XRD, Mössbauer spectroscopy, and IR. The UV−vis spectra and XRD patterns of the zeolite encapsulating the Fe(II) complex ions show that [Fe(en) 3 ] 2+, [Fe(am…
The interaction of isolated Cu, Pd, and Cs atoms on regular and defect sites of the SiO 2 surface has been studied with cluster models. Hartree−Fock, density functional theory, and multireference configuration interaction methods have been used to characterize the bonding of the metal atoms at the following sites: bri…
Directional solidification of lamellar eutectic structures submitted to uniaxial stress is investigated. In the spirit of an approximation first used by Jackson and Hunt, we calculate the stress tensor for a two-dimensional crystal with triangular surface, using a Fourier expansion of the Airy function. crystal with t…
The structure−property relationships of nanostructured Ru/carbon aerogel composite materials have been evaluated. These new materials were prepared via a novel two-step metal vapor impregnation method which enables one to control the Ru loading through repetition of the process. The resulting microstructure is charact…
A one dimensional experiment in granular dynamics is carried out to test the thermodynamic theory of weakly excited granular systems [Hayakawa and Hong, Phys. Rev. Lett. {\bf 78}, 2764(1997)] where granular particles are treated as spinless Fermions. The density profile is measured and then fit to the Fermi distributi…
The photoluminescence (PL) from 100 nm diamond particles induced by infrared (IR) pulsed excitation [λexc=1064 nm (1.16 eV), τ=10 ns] was observed. The laser light intensity dependence of the PL yield shows that this is the five-photon absorption process (the total energy of excitation 5.8 eV). The PL results from str…
We report that common gases (such as He, Ar, ${\mathrm{H}}_{2}$, ${\mathrm{O}}_{2}$, ${\mathrm{N}}_{2}$, CO) experience adsorption at oxidized silicon surfaces at 300 K via electrostatic coupling. This is deduced using contact potential measurements of the work function for gas pressure in the range ${10}^{\ensuremath…
Time-resolved degenerate-four-wave-mixing measurements were used to study the nonlinear optical response (intensity-dependent refractive index) of Ge nanocrystallites embedded in a silica matrix. Nanocrystals were fabricated by ion-implanting silica with 1.0 MeV Ge ions to fluences in the range from 0.6 to 3×1017 Ge c…
Ferroelectric films with composition gradients normal to the substrate have recently been reported to exhibit anomalously large polarization offsets when hysteresis loops are driven with an ac voltage and measured using a Sawyer–Tower (ST) circuit. These offsets have been reported in graded Pb(Zr, Ti)O3 (over 400 μC/c…
The phase Hamiltonian of armchair carbon nanotubes at half filling and away from it is derived from the microscopic lattice model by taking the long-range Coulomb interaction into account. We investigate the low-energy properties of the system using the renormalization group method. At half filling, the ground state i…
Using scanning tunneling microscopy, low-energy ion scattering, and quantitative low-energy electron diffraction, we find about $17%$ metal vacancies on the oxygen-covered Cr(100) surface. The oxygen atoms occupy all the hollow sites of the first layer, including those neighboring a Cr vacancy. We argue that the vacan…
A parallel approach for fabricating nanocrystal-based semiconductor–insulator–metal tunnel diodes is presented. The devices consisted of a Au electrode, a monolayer of 38 Å CdSe nanocrystals, an insulating bilayer of eicosanoic acid (C19H39CO2H), and an Al electrode. Each device was approximately 100 μm2. Conductance…
We report on a photoinduced phenomenon in solids, namely, photomelting at low temperature. We have found that both trigonal and amorphous selenium can be molten by illumination with light at a temperature of ∼77 K. This phenomenon is pure optical (athermal) and it is associated with light-induced breaking of the inter…
A simple method of making reliable electrical contact to multiwalled carbon nanotubes is described. With these contacts, current in the mA range can be routinely passed through individual multiwalled nanotubes without adverse consequences, thus allowing their resistance to be measured using a common multimeter. The co…
We have fabricated light-emitting diodes (LEDs) with Schottky contacts on a single ultrathin amorphous silicon (Si) layer containing Si nanocrystals formed by simple techniques as used for standard Si devices. Orange electroluminescence (EL) from these LEDs could be seen with the naked eye at room temperature when a r…
Magnetic tunneling junctions are fabricated from epitaxially grown La0.8Sr0.2MnO3/SrTiO3/La0.8Sr0.2MnO3 trilayers. A large tunneling magnetoresistance of 150% is observed for a junction with a thin barrier layer (1.6 nm) under a low switching field (<10 Oe) at 5 K. A small tunneling magnetoresistance is observe…
Third-order optical nonlinearity of the carbon nanotubes was investigated with both 30-ps-wide and 8-ns-wide Nd:YAG laser beams. Both 1064 and 532 nm were used in each case. The nonlinear optical temporal response was obtained both on the picosecond scale and on the nanosecond scale, and the corresponding mechanism is…
Compression of purified, unoriented, highly crystalline single-wall carbon nanotube material reveals an exceptionally large and reversible volume reduction. Density increases rapidly with increasing pressure, approaching that of graphite, and recovers completely upon pressure release. The reversible work done in compr…
The three-dimensional orientation of polarization vectors at the surface of ferroelectric barium–titanate (BaTiO3) ceramics is evaluated using voltage-modulated scanning force microscopy (SFM). By applying an ac voltage to the conductive SFM tip, we measure the relative amount of the three orthogonal components Px, Py…
The electrochromic mechanism in amorphous tungsten oxide films is studied using Raman scattering measurements. The Raman spectra of as-deposited films show two strong peaks at 770 and 950 cm−1 due to vibrations of the W6+–O and W6+=O bonds, respectively, and a weaker peak at 220 cm−1 that we attribute to the W4+–O bon…