Materials Literature
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Bond contraction in the surface layers induces a compressive stress on the inner part of a grain and results in a size effect for ferroelectric materials in the nanometer size range. By using the Landau-Ginsburg-Devonshire free energy approach, the phase transitions and intrinsic ferroelectric properties of the lead z…
We investigate the highly frustrated spin and orbital superexchange interactions in cubic vanadates. The fluctuations of t(2g) orbitals trigger a novel mechanism of ferromagnetic interactions between spins S = 1 of V3+ ions along one of the cubic directions which operates already in the absence of Hund's rule exchange…
The piezoelectric properties of (1−x) Pb(Mg1/3Nb2/3)O3–xPbTiO3 (x=0.3–0.35), ceramics with a high degree of 〈001〉 fiber texture were investigated for possible actuator applications. Piezoelectric coefficients (d33) in excess of 1200 pC/N associated with strain levels up to >0.3% were observed in samples prepare…
The Peierls distortions in a two-dimensional electron-lattice system described by a Su-Schrieffer-Heeger type model extended to two-dimensions are numerically studied for a square lattice. The electronic band is just half-filled and the nesting vector is ($π/a$, $π/a$) with $a$ the lattice constant. In contrast to the…
The charge-density-wave transition in $\mathrm{TiSe}{}_{2}$, which results in a commensurate $(2\ifmmode\times\else\texttimes\fi{}2\ifmmode\times\else\texttimes\fi{}2)$ superlattice at temperatures below $\ensuremath{\sim}200\mathrm{K}$, presumably involves softening of a zone-boundary phonon mode. For the first time,…
We investigate theoretically the switching characteristics of semiconducting carbon nanotubes connected to gold electrodes under an external (gate) electric field. We find that the external introduction of holes is necessary to account for the experimental observations. We identify metal-induced gap states (MIGS) at t…
We calculate the interaction between two spherical colloidal particles embedded in the isotropic phase of a nematogenic liquid. The surface of the particles induces wetting nematic coronas that mediate an elastic interaction. In the weak wetting regime, we obtain exact results for the interaction energy and the textur…
Waves propagate through disordered systems in a variety of regimes. There is a threshold of disorder beyond which waves become localized and transport becomes restricted. The intensity I of the wave transmitted through a system has a dependence on the length L of the sample that is characteristic of the regime. For ex…
Application of the so called mxing-roughness-information depth (MRI)-model to the quantitative reconstruction of the in-depth distribution of composition is demonstrated by comparing SIMS and AES depth profiles. A GaAs/AlAs reference sample consisting of two layers of AlAs (1 ML and 36 ML) separated by 44 ML of a GaAs…
X-ray photoelectron spectroscopy (XPS) has been used to study the electronic structures of indium tin oxide (ITO) surfaces treated by O+, Ar+, and NHx+ plasmas. The XPS data show that there is a significant change in core level energies (In 3d5/2 O 1s, and Sn 3d5/2), in donor concentration (Sn4+), in valence band maxi…
Abstract The silane coupling agent 3‐glycidoxypropyl trimethoxylsilane (GPS) was grafted onto the surface of silica gel, P 2 glass beads and TiO 2 oxide particles. FT‐IR, thermogravimetric and elemental analysis were used to characterize the modified particles. The effects of various factors on the GPS grafting effici…
The friction behavior of a diamond-like carbon coating was studied in reciprocating sliding contact at speeds from 0.01 to 5 mm/s, in dry nitrogen. “Superlow” friction coefficients of 0.003–0.008 were obtained in continuous sliding at the higher speeds (>1 mm/s). However, friction coefficients rose to values ty…
We have measured the Raman spectrum of individual single walled carbon nanotubes in solution and compare it to that obtained from the same starting material where the tubes are present in ordered bundles or ropes. Interestingly, the radial mode frequencies for the tubes in solution are found to be approximately 10 cm…
Amorphous silicon quantum dots (a-Si QDs), which show a quantum confinement effect were grown in a silicon nitride film by plasma-enhanced chemical vapor deposition. Red, green, blue, and white photoluminescence were observed from the a-Si QD structures by controlling the dot size. An orange light-emitting diode (LED)…
The structures of the polar surfaces of ZnO are studied using ab initio calculations and surface x-ray diffraction. The experimental and theoretical relaxations are in good agreement. The polar surfaces are shown to be very stable; the cleavage energy for the (0001)-Zn and (0001;)-O surfaces is 4.0 J/m(2) comparable t…
Field emitters comprised of aligned carbon nanotubes are shown to be promising as a primary electron source in an x-ray tube working in a nonultrahigh vacuum ambience. At a pressure of 2×10−7 Torr, the nanotube emitters continue to emit electrons for more than 1 h, and yield better resolved x-ray images than do thermi…
The origin of ultrahigh piezoelectricity in the relaxor ferroelectric ${\mathrm{PbZn}}_{1/3}{\mathrm{Nb}}_{2/3}{\mathrm{O}}_{3}\ensuremath{-}{\mathrm{PbTiO}}_{3}$ was studied with an electric field applied along the [001] direction. The zero-field rhombohedral $R$ phase starts to follow the direct polarization path to…
We have measured, as a function of temperature and frequency, the velocity and attenuation of sound down to the glass transition of the fragile glass-forming molecular liquid m-toluidine. The mechanical relaxation process is compared with the dielectric one recently studied on the same substance. The Arrhenius plot of…
We have used molecular dynamics simulation and thermodynamic arguments to analyze the pressure-area curve resulting from the compression of a monolayer of nanoparticulates at a liquid–vapor interface. The pressure–area isotherm produced by molecular dynamics simulation shows characteristics common to experimental isot…
To study the liquid–solid and solid–solid phase transitions of a confined O2, we performed x-ray diffraction measurements of O2 confined inside the cylindrical pores of six kinds of regular mesoporous adsorbents (MCM-41 and SBA-15) with different pore radii (R=2.1, 2.9, 3.9, 4.5, 5.3, and 7.0 nm) as a function of temp…