Electrodeposition was used to grow epitaxially BaTiO3 thin films on SrTiO3 single-crystal substrates with La0.7Sr0.3MnO3 (LSMO) conducting buffer layers. The epitaxial films appeared to consist of very small (ø10 nm) particles. The film completely covered the substrate when the reaction was performed at temperatures between 60 and 90 °C with LSMO potentials of –0.5 to –1.0 V against a Pt counter-electrode. It appeared that an electrophoretic force, acting on BaTiO3 nuclei within the solution, facilitated the deposition of the film.

The interlayer space of a thin film of layered titanate, Cs0.68Ti1.83‪0.17O4, was successfully expanded by SiO2 pillaring. Ion exchange of the Cs ions in the interlayer to alkylammoniuim cations, n-CnH2n+1NH3+ (n = 8, 12, 18), expanded the interlayer space, and enabled intercalation of tetraethylorthosilicate. X-ray diffraction and the cross section of transmission electron microscopy images revealed that tetraethylorthosilicate-treated thin film maintained the expansion of interlayer space by SiO2 pillaring after calcination at 773 K. X-ray photoelectron spectroscopy after etching the thin film about 100 nm from the surface further confirmed the existence of SiO2 in the interlayer space.

Multiwall open-end and closed carbon nanotubes with the wall thickness from several to more than 100 carbon layers were produced by a principally new method— hydrothermal synthesis—using polyethylene/water mixtures in the presence of nickel at 700–800 °C under 60–100 MPa pressure. An important feature of hydrothermal nanotubes is a small wall thickness, which is about 10% of the large inner diameter of 20–800 nm. Closed nanotubes were leak-tight by virtue of holding encapsulated water at high vacuum and can be used as test tubes for in situ experiments in transmission electron microscope (TEM). Raman microspectroscopy analysis of single nanotubes shows a well-ordered graphitic structure, in agreement with high-resolution TEM. The hydrothermal synthesis has the potential for producing multiwall nanotubes for a variety of applications. The fabrication of nanotubes under hydrothermal conditions may explain their presence in coals and carbonaceous rocks and suggests that they should be present in natural graphite deposits formed under hydrothermal conditions.

Metal–intermetallic Ni/Ni3Al multilayered thin films were synthesized by the magnetron sputtering technique. The synthesized films possessed high hardness that could be compared with intermetallic Ni3Al films. The constituent layers of Ni and Ni3Al were fully adherent to one another at the multilayered boundaries. The fracture surface of the multilayered films on bending showed the characteristics of local ductile fracture. This novel type of multilayered thin films is expected to be used as hard coatings and miniaturized parts of apparatus in micro-electromechanical systems.

Oxygen diffusion in bicrystal SrTiO3 was investigated with the aid of resistive anode encoder of secondary-ion mass spectrometry. The diffusion profiles of 18O on volume, grain boundary (joining interface), and dislocation were separately determined from the three-dimensional distribution of 18O in the bicrystal SrTiO3. The volume diffusion of oxygen is found to be dependent on (i) Nb doping concentration, (ii) crystallographic orientation, and (iii) nonequilibrium oxygen defects that are annihilated by thermal annealing. The feature of 18O diffusion image along the dislocation in (100) and (110) bicrystals can be explained by the dislocation array introduced by the mechanical polishing.

A new approach was used for combining GaN and porous Si with the goal of producing high-quality GaN epitaxial layers for optoelectronic integrated circuit devices based on Si substrates. Reflection high-energy electron diffraction (RHEED), x-ray diffraction (XRD), photoluminescence (PL), and Van der Pauw–Hall effect measurements were performed to investigate the structural, optical, and electrical properties of the GaN epitaxial films grown on porous Si(100) by plasma-assisted molecular-beam epitaxy with a two-step method. The RHEED patterns were streaky with clear Kikuchi lines, which was direct evidence for layer-by-layer two-dimensional growth of GaN epitaxial layers on porous Si layers. The XRD curves showed that the grown layers were GaN(0001) epitaxial films. The results of the XRD and the PL measurements showed that the crystallinities of the GaN epilayers grown on porous Si by using a two-step growth were remarkably improved because the porous Si layer reduced the strains in the GaN epilayers by sharing them with the Si substrates. Hall-effect measurements showed that the mobility of the GaN active layer was higher than that of the GaN initial layer. These results indicate that high-quality GaN epitaxial films grown on porous Si(100) by using two-step growth hold promise for potential applications in new kinds of optoelectronic monolithic and ultralarge integrated circuits.

Real-time x-ray reflectivity and diffraction measurements under in situ sputtering conditions were employed to study the growth behavior of LaNiO3 thin films on a Si substrate. Our results clearly show there is a transition layer of 60 Å, which grew in the first 6 min of deposition. The in situ x-ray-diffraction patterns indicated that this transition layer is amorphous. Subsequently, a polycrystalline overlayer grew as observed from the in situ x-ray reflectivity curves and diffraction patterns. Nucleation and growth took place on this transition layer with random orientation and then the polycrystalline columnar textures of (100) and (110) grew on the top of this random orientation layer. By comparing the integrated intensities of two Bragg peaks in the plane normal of x-ray diffraction, it was found that a crossover of the growth orientation from the ⟨110⟩ to the ⟨100ߩ direction occurred and the ability of (100) texturization enhanced with increasing film thickness beyond a certain critical value.

Experiments were performed to evaluate the mechanical and water barrier properties of corn-protein-based materials that were compression molded from thermoplastic resins. The influence of varying concentrations of water, glycerol, and octanoic acid was studied. At 0% relative humidity, the material exhibited a linear elastic deformation and a brittle fracture at any glycerol or octanoic acid content. Raising relative humidity from 0% to 97.3%, progressively decreased the tensile strength (from 24.1 to 2.2 MPa and 19.4 to 1.0 MPa), and the modulus of elasticity (from 1.67 to 0.03 GPa and 1.87 to 0.13 GPa), respectively, for the octanoic acid- or glycerol-plasticized materials. Increasing water content did not increase the tensile strain at break of the glycerol-plasticized material, whereas this parameter changed from 1.6 to 52.3% for octanoic-acid-plasticized material. This last material was waterproof during 21 h and its water transmission rate was then 0.05 mmolmm-2 s -1. Differences in water absorption were related to plasticizer solubility and material structure.

The first part of this article reports on the reactive synthesis and characterization of Al–Ti–C alloys intended as master alloys for aluminum grain refining. The alloys were produced from elemental powders by the thermal explosion mode and analyzed with x-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. Parameters were the titanium concentration (15 and 30 wt%) and the Ti/C ratio (9/1, 20/1, and 120/1) in the reactant powder mixture and the cooling rate after the reactive synthesis (1 and 120 °C/min). Full conversion of titanium and carbon into Al3Ti and TiC was achieved for the 30 wt% Ti mixtures but not for the 15 wt% Ti mixtures where the reaction was not exothermic enough. The Ti/C ratio did not affect the phase composition after reactive synthesis in the 30 wt% Ti alloys and could be used to tailor the microstructure of the alloy. The formation of Al4C3 was suppressed with a high cooling rate after the exothermic formation reactions.

This article, Part II in a series, reports on the grain refining performance of the Al–Ti–C alloys produced by reactive synthesis. Grain refinement was tested as a function of the following parameters in the reaction synthesis process: Ti content, Ti/C ratio, and cooling rate after the reaction. The grain refining performance of the alloys in the as-synthesized condition was limited due to either a shortage of TiC particles or an insufficient amount of aluminum matrix. Dilution of the alloys to a nominal composition of 3 wt% Ti, followed by extrusion improved the grain refinement to the level of commercially available Al–Ti–C grain refining alloys. A prerequisite for successful secondary processing is that the conversion of carbon is completed in the reaction synthesis; otherwise Al4C3 is formed rather than TiC.

Recently, highly oriented WSe2 thin films, with the c axis of the crystallites perpendicular to the substrate, were reproducibly obtained by interposing a Ni/Cr thin layer between the substrate and a WO3 precursor film. In the present work the preparation conditions were varied to elucidate the growth mechanism of such films. A model for the growth mode is proposed. Based upon this analysis, WSe2 thin films with improved crystalline and electronic properties were obtained. The photoresponse spectrum for photoelectrochemical cells with the WSe2 electrode immersed into a selenosulfate solution was measured. Quantum efficiency of 0.1% was calculated from this spectrum.

Short segments of YBa2Cu3O7-y (YBCO) coated conductors were fabricated on rolling-assisted biaxially textured substrates (RABiTS) with a layer sequence of CeO2/YSZ/Ni using an ex situ BaF2 precursor process. Pulsed laser deposition (PLD) was used to deposit both YSZ and CeO2 layers. The YBCO films were grown using e-beam coevaporated Y–BaF2–Cu precursors followed by postannealing. An overall engineering current density, JE, of 28,000 A/cm2 and critical current, Ic, of 147 A/cm width at 77 K were achieved for a 1.6-μm-thick YBCO film. This result demonstrates the possibility of using both the ex situ BaF2 precursor approach and the RABiTS process for producing long lengths of high-JE coated conductors.

Thermogravimetric analysis, x-ray photoelectron spectroscopy, and x-ray diffraction results and the humidity sensing properties of poly(vanadium–molybdenum acid) H2V9.5Mo2.5O32.0 · 8.8H2O xerogel thin films, which were fabricated by the sol-gel process, are described in this paper. The conductance and the capacitance of the thin films strongly depend on the relative humidity. Different electrodes have different influences on the humidity-sensing properties of the thin films.

We showed, by high-resolution transmission electron microscopy and spatially resolved electron energy-loss spectroscopy, that silver atoms have been introduced into single- walled carbon nanotubes (SWCNTs) produced by the arc-discharge method with solution phase chemistry by capillary filling, and a high efficiency of filling may be realized. Both partially filled and completely filled SWCNTs were observed, and the metal inside the tube may be regarded as one-dimensional silver nanowires with high length-to-diameter ratios. The length of filling ranged from several to tens of nanometers. Under strong electron beam irradiation the filling metal condensed to a particle, while the silver-containing SWCNT shrank and disintegrated.

Ce3+ luminescence in Ce3+ –activated yttrium aluminium borates was studied. A substantial red shift in photoluminescence and low-voltage cathodoluminescence spectra was found to be induced by Ce concentration increase. Complicated concentration dependence of emission intensity and strong influence of cerium content on emission wavelength suggest strong activator–host interaction in rare-earth borates.

Surface oxidation of an iridium film and the possibility of epitaxial growth of PZT spin-coated film on sputtered iridium were investigated. The free surface on the iridium film oxidized over 400 °C with random orientation. Nevertheless, both the PZT(111)/Ir(111) and PZT(100)/Ir(100) interfaces were realized using the highly oriented iridium layer. These results suggest that PZT nucleation has priority over iridium surface oxidation.

The 1 MHz dielectric properties for mixed-phase polycrystalline ceramics in the system Bi4Ti3O12–Bi(InxSb1x)O3 were reported. In the vicinity of ambient temperature, the dielectric constants for the Sb and In end-members were approximately 430 and 160, respectively, and the temperature coefficients of dielectric constant (TCKs) were approximately -7600 and +430 ppm/deg. At an overall composition of Bi4Ti3O12:Bi(In0.37Sb0.63)O3 a dielectric constant of 144 and a low TCK were found. Powder x-ray diffraction and electron microscopy analyses indicated that the optimal composition contained three major phases. Deviation of any of the elements from the above ratio leads to degradation of the properties.

Boron nitride films were synthesized on silicon substrates by radio frequency-bias- assisted direct current jet chemical vapor deposition in Ar–N2–BF3–H2 system. The formation and content of cBN phase were investigated by means of Fourier transform infrared spectroscopy, glancing-angle x-ray diffraction, and scanning electron microscopy. The influences of the experimental parameters, i.e., bias voltage, substrate temperature, and gas composition, on the cBN content in the deposited films were systematically studied, and an experimentally optimum window for the deposition of cBN films was observed. Under optimized conditions, a boron nitride film with cBN content higher than 85% was deposited and a growth rate of about 70 nm/min was achieved.

In this paper, we describe a new method for creating nanostructures, and demonstrate its use by depositing Au, Ni, and Zn on a SiO2 passivated Si substrate. The method combined the spatial control of electron-beam lithography with the ease of fabrication of self-assembled arrays. The technique enabled the selective electrochemical deposition of nanostructures by creating specific nucleation sites by nanoindentation. This offered the possibility of accurately creating nanostructures ranging in size from one to hundreds of nanometers. We showed that it is possible to electrically isolate the nanostructures from the substrate and each other by a thermal oxidation process. In principle, this technique allowed fabrication of quantum devices of any geometry.

We investigated the photoluminescence as well as the crystal structure and optical energy gaps of the Zn1-xCdxAl2Se4-4xS4x solid solution system based on the Al-related compounds of ZnAl2Se4, ZnAl2S4, CdAl2Se4, and CdAl2S4. The single crystals of the system with 0.0 ≤ x ≤ 1.0 were grown by the chemical transport reaction technique. The Zn1-xCdxAl2Se4-4xS4x crystallizes in a defect chalcopyrite structure for a whole composition and has an optical energy gap ranging from 3.525 to 3.577 eV at 13 K. The photoluminescence spectra at 13 K showed a strong emission band in the blue spectral region and a weak broad emission band in the visible region due to donor–acceptor pair recombination. The composition and temperature dependence of these bands were examined in the investigated regions. The simple energy band scheme for the radiative mechanisms of the Zn1-xCdxAl2Se4-4xS4x is proposed on the basis of our experimental results along with photo-induced current transient spectroscopy measurements.