A misting free dental mirror is obtained near the human temperature under the saturated humidity atmosphere by use of the sheet electron beam irradiation treatment. It is shown that electron beam irradiation treatment decreases the time to clear vision in a misted mirror. This effect is due to an enhancement of the interfacial energy between the dental mirror glass and water.

A resonant Raman study of single-wall carbon nanotubes (SWNT) using several laser lines between 0.94 and 3.05 eV is presented. A detailed lineshape analysis shows that the bands associated with the nanotube radial breathing mode are composed of a sum of individual peaks whose relative intensities depend strongly on the laser energy, in agreement with prior work. On the other hand, the shape of the Raman bands associated with the tangential C–C stretching motions in the 1500–1600 cm−1 range does not depend significantly on the laser energy for laser excitation energies in the ranges 0.94–1.59 eV and 2.41–3.05 eV. However, new C–C stretching modes are observed in the spectra collected using laser excitations with energies close to 1.9 eV. The new results are discussed in terms of the difference between the 1D electronic density of states for the semiconducting and metallic carbon nanotubes.

Crystallization of amorphous titania prepared by hydrolysis of ethoxide was accelerated even by a small amount of water in the vapor phase. The existence of water promoted the change of localized structure of the amorphous titania to anatase structure, which resulted in acceleration of anatase nucleation. The anatase crystals grew in steam by solid-state epitaxial growth, but stopped growing in a short time. The growth of anatase crystals under hydrothermal conditions could be divided into the following two stages: the first stage with fast growth rate by the solid-state epitaxial growth and the second stage with slow growth rate by the dissolution and deposition process.

We have developed a process for the fabrication of (001) oriented SrTiO3 buffer layers onto (001) MgO substrates by rf magnetron sputtering followed by a post-deposition heat treatment in air. Precursor films with Tl :Ba : Ca : Cu ratio 2 : 2 : 2 : 3 were deposited by dc magnetron sputtering onto both these buffered substrates and directly onto (001) SrTiO3 single-crystal substrates, and thalliated at elevated temperatures. Because of Sr diffusion from the substrate/buffer layer, and its subsequent substitution for Ba in the superconducting film, the single Tl–O layer phase Tl(Ba1−xSrx)2Ca2Cu3Oy was stabilized. Diffusion of Ba and Ca in the opposite direction led to the formation of a Ba–Ca–Ti–O compound at the interface. The Tl(Ba1xSrx)2Ca2Cu3Oy films typically have superconducting transition temperatures (Tc's) > 103 K and critical current densities (Jc's) > 2.9 × 105 A cm−2 at 77 K. Rs values measured on these films and scaled to 10 GHz were 3.0 mΩ at 80 K and <200 µΩ at 50 K for the film grown on SrTiO3 buffered MgO, and 2.0 mΩ and 1.0 mΩ at 50 K for the film grown directly onto the (001) SrTiO3 substrate. Films fabricated on (001) SrTiO3 using an in situ deposition technique with a substrate temperature around 100 °C lower than the ex situ thalliation temperature showed no evidence of an interfacial reaction layer.

The particle segregation mode of two different inclusion phases of Y2BaCuO5 (Y211: a dissolving phase in a Ba–Cu–O liquid phase) and BaCeO3 (a nondissolving phase) was investigated in the melt-textured YBa2Cu3O7−y (Y123) with BaCeO3 addition (0–20 wt. %), and with 30 wt.% Y211 plus BaCeO3 (0–20 wt. %). The segregation mode of the inclusion phases is dependent not only on the type of the inclusion phases but also their amounts. When the trapped amount of the Y211 is small, they make an X-like pattern on the diagonal planes of the Y123 crystal. When the amount of the Y211 is large, meanwhile, the Y211 particles are trapped within four tetrahedral spaces (normal to the c-axis) bounded by the diagonal planes of the Y123 crystal, with no Y211 trapping within two tetrahedral spaces parallel. On the other hand, the nondissolving BaCeO3 particles make linear tracks normal to the {100} growth fronts of the Y123 crystal.

We have investigated the wetting angle, side band growth, and intermetallic compound formation of seven SnPb alloys on Cu ranging from pure Sn to pure Pb. The wetting angle has a minimum near the middle composition and increases toward pure Sn and pure Pb, but the side band growth has a maximum near the middle composition. The intermetallic compounds formed are Cu6Sn5 and Cu3Sn for the eutectic and high-Sn alloys, yet for the high-Pb alloys, only Cu3Sn can be detected. While no intermetallic compound forms between Cu and pure Pb, the latter nevertheless wets the former with an angle of 115°. The driving force of a wetting reaction, which may be affected by the free energy gain in compound formation, is discussed by assuming that rate of compound formation is fast.

A temperature programmed method for determining diffusivities has been previously applied to oxygen diffusivity in V2O5. In this communication we extend the method to the case of oxygen diffusivity in MoO3. The reduction of MoO3 to MoO2 using NH3 is utilized to obtain experimental parameters such as the temperature of reduction and the activation energy for oxygen diffusion. These parameters are in turn used to solve Fick's equation for the oxygen diffusivity D0. The utility of this temperature programmed method for obtaining diffusivities has now been clearly established by extension to MoO3.

An amorphous carbon-boron nitride (C-BN) solid was prepared by ball milling the mixture of graphite and hexagonal BN powders for a period of 120 h. After annealing the amorphous C-BN solid for 1 h at atmosphere in the temperature range from 800 to 900 K and then quenching it to room temperature, a small amount of cubic C-BN solid solutions with diamond-like structure, which belong to a high energy phase and can only be synthesized previously under high pressure and temperature (30 GPa, 2000 K), were observed in the annealed amorphous C-BN solid. The lattice constant of the cubic C-BN solid solution was 0.3587 nm, and its grain size was in the range of 10 to 50 nm.

Environmental and internal-hydrogen embrittlements in stress-relieved and recrystallized Ni−16.5Al−8Cr−0.8Hf−0.1B−0.03Y (at. %) have been studied. The stress-relieved Ni3Al-based alloy showed environmental embrittlement when tested in air or in hydrogen gas. The embrittlement is more severe in hydrogen gas than that in air. The recrystallized Ni3Al-based alloy was not susceptible to air, but it was embrittled severely by hydrogen gas and exhibited not only a grain interior but a severer grain boundary embrittlement. When tested in air, the stress-relieved Ni3Al was insensitive to internal hydrogen; however, the recrystallized Ni3Al showed a certain susceptibility to internal hydrogen. With increasing the internal hydrogen content in the alloy, the ductility of the recrystallized Ni3Al decreased steadily and a certain degree of grain boundary embrittlement was observed.

With the advent of new multijunction thin film solar cells, amorphous silicon photovoltaic technology is undergoing a commercial revival with about 30 megawatts of annual capacity coming on-line in the next year. These new a−Si multijunction modules should exhibit stabilized conversion efficiencies on the order of 8%, and efficiencies over 10% may be obtained in the next several years. The improved performance results from the development of amorphous and microcrystalline silicon alloy films with improved optoelectronic properties and from the development of more efficient device structures. Moreover, the manufacturing costs for these multijunction modules using the new large-scale plants should be on the order of $1 per peak watt. These modules may find widespread use in solar farms, photovoltaic roofing, as well as in traditional remote applications.

A new quenching technique was used for detailed microstructural examination of quenched YBa2Cu3O6+δ/liquid interfaces. The examination revealed that the growth rate and the amount of excess Y2BaCuO5 (211) had a strong influence on the growth morphology of YBa2Cu3O6+δ (123). The maximum growth rate at which single crystal growth could be obtained increased from 1 μm/s to 1.5 μm/s as excess 211 content increased from 0 to 20 wt. %. It then decreased to 1 μm/s as excess 211 increased to 40 wt. %. Dendritic growth with distinguishable secondary arms occurred for stoichiometric 123 samples in the regime of cellular/dendritic growth. A highly curved 123 envelope was formed on 211 particles located at the 123 growth interface for stoichiometric 123 samples in the regime of single crystal growth. The microscopic 123 growth interface became flat as excess 211 content increased to 20 wt. %. The engulfment of 211 particles into 123 matrix is discussed based on detailed microstructural examination. It is found that the formation of a small highly curved 123 envelope on 211 particles for stoichiometric 123 samples is due to the large 211 particle spacing.

The stibiotantalite (ABO4) family includes a number of ferroelectrics and antiferroelectrics with excellent potential for applications. We report the deposition of phase-pure, polycrystalline thin films of BiNbO4 on Si(100) substrates using pulsed laser ablation. The deposition conditions were optimized with respect to substrate temperature, laser parameters, and the ambient oxygen pressure. The films were characterized by x-ray diffraction, energy dispersive x-ray analysis, and Raman spectroscopy, while their microstructure was studied by atomic force microscopy and scanning electron microscopy. Dielectric hysteresis studies indicated that films with a thickness below ≈250 nm are ferroelectric, while thicker ones are antiferroelectric.

The commonly held view that metallothermic reduction is strictly a chemical reaction and that the process is rate limited by mass transfer has been found to be incomplete. In a study of the production of tantalum powder by the reaction of K2TaF7 with sodium, it has been shown that there are two dominant kinetic pathways, both involving electron transfer. Furthermore, the overall rate of reaction is limited by electron transport between the reactants. This indicates that metallothermic reduction is an “electronically mediated reaction” (EMR). Experiments found that the location of the tantalum deposit and its morphology are governed by the reaction pathway.

Errors are noted in two publications on the theory for Mirage-effect measurements of the thermal diffusivity of materials. The works include theory for interpreting Mirage experiments on homogeneous samples mounted on a support with ambient (typically air) above and theory for interpreting Mirage experiments on coated substrates with ambient both above and below.

Measurements of structural and electrical properties as a function of the molding pressure in Y1Ba2Cu3O7−δ superconductors have been performed to investigate the texturing behavior. The magnitudes of the molding pressure were 0.5 × 103 N/cm2, 1 × 103 N/cm2, 2 × 103 N/cm2, and 4 × 103 N/cm2. As the molding pressure increases, the anisotropy of the crystal structure decreases and the crystal grows preferentially along the c-axis. As the molding pressure increases, since the size of the grain becomes larger due to the decreased porosity, denser textures are formed. This result indicates that the critical current density is improved, resulting in increased thermal stability at higher molding pressure. While the molding pressure does not affect the oxygen mole fraction below 500 °C, increases in the molding pressure have a remarkable effect on the formation of textures and on the onset temperature for the superconducting transition in Y1Ba2Cu3O7−δ. These results indicate that structural and electrical properties in Y1Ba2Cu3O7−δ superconductors are affected by the molding pressure during growth.

A systematic study of material quality has been performed for intrinsic a–Si:H layers deposited by plasma enhanced chemical vapor deposition at excitation frequencies between 30 and 80 MHz (VHF). The process conditions were optimized not only for “device quality” opto-electronic properties but also for a uniformity in layer thickness better than 5% over the 10 cm × 10 cm substrate area. We found optimized homogeneities at different pressures depending on the excitation frequency. The effect of frequency at these optimum conditions on the material quality is small. VHF-intrinsic layers have been used in a–Si:H p+-i-n+ solar cells, in which both the p+ and n+ layer were made using 13.56 MHz. There is a clear correlation between material quality and solar cell parameters. Material deposited at low power densities is of so-called “device quality,” which is confirmed by demonstrating an initial efficiency of 10% for cells deposited at 65 MHz using a low power density. The deposition rate still is 2–3 times higher than the one at 13.56 MHz. Light-soaking of the cell leads to stabilization at 6% for the best cells, which compares well to conventional 13.56 MHz cells.

Fine particles of nickel aluminides were synthesized for the first time by reducing mixtures of AlCl3 + NiCl2 vapors by hydrogen. A thermodynamic equilibrium calculation was carried out in the Ni–Al–H–Cl–Ar system to evaluate the effect of the reactant partial pressures and temperature on the formation of intermetallic phases. A single intermetallic phase was found to be feasible only in a very narrow range of the reactant partial pressures. For all other conditions the predicted solid product was a mixture of two phases. Experimentally, Ni3Al was formed along with metallic Ni. Though the coreduction of NiCl2 and AlCl3 by H2 to form Ni3Al is thermodynamically favorable at 1100 °C, it did not happen experimentally under the conditions of this work. However, with a small addition of aluminum vapor, the coreduction reaction proceeded as expected by thermodynamics. The effects of reactant partial pressures and temperature were studied. The content of Ni3Al was maximized to 52 mol% at 1050 °C under the partial pressures of H2, AlCl3, and NiCl2 at 57, 1.5, and 0.5 kPa, respectively. The product particles, as observed by TEM, were very fine, but usually agglomerated. The electron diffraction analysis identified the particles of NiAl and NiAl3 along with Ni3Al and metallic Ni.

High temperature heat treatment of single wall carbon nanotube bundles in flowing H2 was used to produce a significant fraction (∼40%) of diameter-doubled, or coalesced tubes with a mean diameter corresponding to that of ∼(20, 20) tubes. At three laser excitation wavelengths (514.5, 647, and 1064 nm), a reduction in the Raman scattering intensity of the strong radial and tangential modes was observed in the H2-treated sample, consistent with the reduced fraction of tubes in the sample after coalescence. However, using 488 nm excitation, little or no change is observed in the Raman spectrum after the H2 treatment, suggesting that this excitation wavelength couples only to chiral symmetry tubes. Using the 647 nm excitation, the effect of H2 treatment on the tangential band is quite unique, and a significant change in the shape of the tangential band was observed. Our lineshape analysis, and other results reported in this issue, suggest that this unique change of shape is due to lost scattering intensity from metallic tubes partially compensated by tangential mode scattering from the coalesced tubes. The normally prominent radial breathing mode band, which would be expected at ∼90 cm−1 for ∼(20, 20) tubes was not observed, indicating that these larger diameter tubes do not exhibit strong resonant scattering, at least at any of the wavelengths used in this study.

The experimental determination of x-ray elastic constants are performed by in situ measurements of the dependence of the strain state in selected crystallites for different applied external compressive stresses. The use of compressive applied stresses instead of tensile applied stresses is of interest for x-ray elastic constant determinations for materials which exhibit brittle crack-like behavior, which cannot be loaded to high tensile stresses in, for example, four-point bending devices. The x-ray elastic constants for {146} α–Al2O3 are determined with the pressing device and compared to calculated as well as experimentally determined values which were tested in tensile loading devices.

Three types of antimonic acid (Sb2O5 · nH2O) films, (111)-oriented and nonoriented polycrystalline films of cubic Sb2O5 · nH2O and amorphous Sb2O5 · nH2O films, were prepared on quartz glass substrates with a spin-coating technique using aqueous slurries, which were formed by reacting H2O2 with metallic Sb powder or Sb(O-n-C3H7)3. The morphologies and structures of the films were observed, and the electrical conductivity of the films was determined at 20 °C in the relative humidity range 9–100%. The electrical conductivity of the (111)-oriented film, which increases from 1.69 × 10−5 to 2.89 × 10−3 S cm−1 as the relative humidity changes from 11 to 85%, is approximately one order of magnitude larger than those of the nonoriented and amorphous films.