In this Communication we discuss how unimplanted and implanted films (Y and Au implanted) of C60, when hot isostatically pressed (HIPed) at a pressure of 170 MPa (1.7 kbar) of Ar and temperatures of 300 or 400 °C, show substantial uptake of Ar into the film. Rutherford backscattering (RBS) provides an effective method for elucidating film composition, showing the films to have ∼1.5 at.% of Ar, consistent with a stoichiometry close to Ar1 C60. The Ar was found to diffuse from the films when these were held in a vacuum at 300 °C. It could subsequently be reincorporated into the film by re-HIPing, with uptake of a similar amount of Ar. IR spectroscopy showed that the C60 IR absorptions remain unchanged throughout uptake of the Ar and its subsequent loss during heating at 300 °C. It appears that the Ar is trapped interstitially in the films outside the C60 cages.

The microstructure of rapidly solidified Ti3Al−2Nb alloy consists of an ordered orthorhombic α″0 phase. In the foil samples for transmission electron microscopy prepared by chemical thinning, the α″0 → β0 transformation took place due to the charging of hydrogen during thinning. The β0 → α″0 transition in the rapidly solidified alloy can be explained by a shape deformation mechanism, and the β0/α″0 interface (habit) plane is near to {334}β0. The orientation relationships between the β0 and α″0 phases are , and .

The orientational crossover phenomena in a radio-frequency (rf) sputtering growth of TiN films were studied in a real-time synchrotron x-ray scattering experiment. Following the initial random nucleation and growth stage, the growth was dominated by the grains with the (002) planes aligned with the substrate surface. Surprisingly, at later stages, the grains with the (002) growth front tilted away from the surface by about 60° became dominant. The tilting of the growth front resulted in a faceted surface topology that was confirmed by an ex situ AFM study. Our x-ray results suggest that the crossover was driven by the competition between the surface and the strain energy

The kinetics of formation, phase stabilities, and dielectric constants of Pb(Li1/4Fe1/4W1/2)O3 and BaTiO3-added Pb(Li1/4Fe1/4W1/2)O3 have been compared. The addition of 2 mol% BaTiO3 in Pb(Li1/4Fe1/4W1/2)O3 was confirmed to promote the complete formation of the perovskite phase at 700 °C. Also, the thermal stability of the perovskite phase was significantly enhanced, which resulted in an increase of the dielectric permittivity.

Information about the nature of formed switching structures in amorphous hydrogenated silicon has been found from features of the electroluminescence (EL) spectrum. Several small peaks have been detected in the region of 1.8 to 2.4 eV, on the shoulder of the usual a-Si : H peak at 1.32 eV. The intensity of the latter is found to depend on the voltage across the film rather than the current. The EL fine structure can be explained in terms of a model of the switching where there are small metal-rich inclusions in the film. The apparent dependence of EL intensity on voltage is explained in terms of this model with parallel current paths in the structure.

With the growing potential for use of Bi-2212 powders in high temperature superconducting applications, it is important to understand the processing characteristics of the material. To meet this need, the present work established the relationship between confining pressure and green density for powders of different particle sizes and morphologies. Mechanical properties, including elastic and plastic behavior, of the resulting green compacts were also measured as a function of relative density. Particle size and size distribution are shown to have a significant impact on the properties of interest. The implications of such findings are discussed with respect to the powder-in-tube process for making high temperature superconducting wire and tape.

X-ray diffraction line profile analysis (LPA) has been carried out on a set of superconducting thin films of MBa2Cu3O7−δ (MBCO, M = Y, Gd), deposited by pulsed and continuous physical vapor deposition (PVD) techniques on different single-crystal substrates. The choice of appropriate deposition conditions, substrates, and buffer layers promoted a high degree of [00l] preferred orientation, leading to a well-defined columnar grain morphology in the MBCO films. Under such conditions, the LPA of diffraction patterns, collected with the widely spread Bragg–Brentano geometry, gives detailed information on the distributions of coherent scattering domain (crystallite) size and microstrain along the [00l] growth direction; considering the particular MBCO film microstructure, the mean crystallite size () can be regarded as the mean distance between extended planar defects parallel to the film surface. The significance of goes beyond a merely statistical value. As long as the morphology of the films is similar, is found to be strictly connected with the average microstrain by a simple proportionality relation. Moreover, the correlation extends to important superconducting transport parameters, like the transition width ΔTc. These regular behaviors are irrespective of deposition techniques, substrate, and film materials, and are a clear indication of some fundamental relation between the defects and the overall properties of the films.

Directional solidification of YBa2Cu3O7 has been carried out through a Bridgman technique, and the influence of Y2BaCuO5 and CeO2 additives on the size of Y2BaCuO5 precipitates has been investigated. It is demonstrated in this work that the most efficient procedure to reduce the size of the Y2BaCuO5 precipitates is to increase the concentration of nucleation centers present in the peritectic decomposition of YBa2Cu3O7−x. A small concentration (0.3−1 wt. %) of CeO2 has a strong influence on the solidification process and on the size of Y2BaCuO5 precipitates. It is shown that when CeO2 is added, further refinement of the size of precipitates results from the formation of nanometric Y2O3 particles which further enhance the multinucleation effect. We have also observed that coarsening effects are avoided with CeO2 additives.

Oxygen content is a very important factor influencing the electrical properties of YBa2Cu3Oy. In this work the electrical properties of laser deposited YBa2Cu3Oy thin films on LaAlO3(100), in the whole range 6 ≤ y ≤ 7, are studied. An electrical network model, which randomly assigns oxygen contents and R(T) characteristics to the different elements in the circuit according to an arbitrary distribution, is used to analyze several features in the measured R(T) characteristics as a function of oxygen homogeneity. The model takes into account both short-range and long-range oxygen inhomogeneities. Good agreement between estimated oxygen contents from x-ray diffraction data in our samples and the average oxygen contents used to reproduce their R(T) characteristics is found.The model points out that oxygen homogeneity is very important in order to get the best and reproducible properties, and for conduction and superconductivity analysis through the shape or derivatives of R(T) characteristics.

Microelectromechanical systems (MEMS) devices are made of doped single-crystal silicon, LPCVD polysilicon films, and other ceramic films. Very little is understood about tribology and mechanical characterization of these materials on micro- to nanoscales. Micromechanical and tribological characterization of p-type (lightly boron-doped) single-crystal silicon (referred to as “undoped”), p+-type (boron doped) single-crystal silicon, polysilicon bulk, and n+-type (phosphorous doped) LPCVD polysilicon films have been carried out. Hardness, elastic modulus, and scratch resistance of these materials were measured by nanoindentation and microscratching using a nanoindenter. Friction and wear properties were measured using an accelerated ball-on-flat tribometer. It is found that the undoped silicon and polysilicon bulk as well as n+-type polysilicon film exhibit higher hardness and elastic modulus than the p+-type silicon. The polysilicon bulk and n+-type polysilicon film exhibit the lowest friction and highest resistance to scratch and wear followed by the undoped silicon and with the poorest behavior of the p+-type silicon. During scratching, the p+-type silicon deforms like a ductile metal.

Deformation of HfN thin films deposited by the reactive sputtering method on silicon and alumina substrates has been investigated using depth-sensing indentation. The experiments performed in a low load range (2−50 mN) revealed that even extremely shallow indentations were affected by the elastic/plastic response of the substrate. The analysis of the shape of the indentation load-depth hysteresis loops and of conventional hardness data was supplemented by considerations based on the recently proposed energy principle of indentation.

Fluorine doping of silicon dioxide films in tetraethylorthosilicate (TEOS)-based plasma enhanced chemical vapor deposition (PECVD) processes was investigated using two fluorine dopant sources, C2F6 and 1,2 bis[methyldifluorosilyl]ethane (FASi-4). Much as TEOS-based undoped silica glass (USG) films display improved step coverage over silane-based USG films, it was suspected that fluorinated silica glass (FSG) films deposited using the relatively new TEOS-based fluorine source FASi-4 might have improved gap fill capabilities as compared to FSG films deposited using gas-based C2F6 fluorine sources. The physical properties and intermetal gap filling capabilities of FSG films deposited using FASi-4 as a fluorine dopant source were compared with the properties of FSG films deposited using C2F6 as a fluorine source. Fluorine dopant levels in the films were found to be linear functions of C2F6TEOS and FASi-4yTEOS ratios. The RI, film stress, and gap fill capability were found to be strongly dependent on the Si–F content in the film regardless of dopant source reagents. Improved gap fill characteristics were observed in films doped with FASi-4 at a given Si–F/Si–O% as compared to C2F6-based FSG films. Dopant source dependence of doping characteristics, physical properties, and gap filling capability of FSG films is reported.

The short-range order in the near surface region of the Cu3Au(001) face was investigated above the critical temperature by glancing-incidence x-ray diffraction, measuring the diffuse intensity throughout a two-dimensional region of reciprocal space. This intensity was analyzed quantitatively to obtain the two-dimensional Cowley–Warren short-range-order parameters and atomic displacements. Monte-Carlo simulation based on these values has revealed that the atomic configurations in the surface consist of ordered domains and clusters in a disordered matrix. There is a large number of {10} antiphase domain boundaries (APDB).

Small angle neutron scattering investigations performed on Fe1−x–Nix alloys with 0.26 ≤ x ≤ 0.45 revealed a thermodynamically driven decomposition below 800 °C. The miscibility gap extends at least from 30 at.% Ni to 45 at.% Ni. The diffusioncontrolled decomposition produces fractal morphologies during the early stages of the process. During annealing the structure of the precipitated phase densifies continuously from mass fractals with small dimensionality (1 ≤ dm ≤ 3) to surface fractals with 2 ≤ ds ≤ 3. The results are compared with recent simulations of aggregation and growth as well as with a new analysis of spinodal decomposition, both predicting fractal morphologies.

We performed embedded atom method calculations of surface energies and unstable stacking fault energies for a series of intermetallics for which interatomic potentials of the embedded atom type have recently been developed. These results were analyzed and applied to the prediction of relative ductility of these materials using the various current theories. Series of alloys with the B2 ordered structure were studied, and the results were compared to those in pure body-centered cubic (bcc) Fe. Ordered compounds with L12 and L10 structures based on the face-centered cubic (fcc) lattice were also studied. It was found that there is a correlation between the values of the antiphase boundary (APB) energies in B2 alloys and their unstable stacking fault energies. Materials with higher APB energies tend to have higher unstable stacking fault energies, leading to an increased tendency to brittle fracture.

Silicon suboxides thin films obtained by sol-gel and dip-coating methods, starting from a sol containing different percentages of TEOS (tetraethoxysilane) and MTEOS (methyltriethoxysilane), were grown onto silicon substrates. The samples were annealed at 100, 300, and 500 °C, and the electronic and compositional properties of the surface were studied by x-ray photoelectron spectroscopy (XPS) detecting the Si “Auger parameter” and the valence band. The effects produced by an ion-sputtering treatment of the samples were also studied.

The effect of ultraviolet irradiation on the xerographic sensitometry of organic photoreceptors was studied. Absorbed ultraviolet light decreased both the dark decay and the photoinduced discharge rates, and an increased buildup of the residual potential was observed. Above a threshold dose of ultraviolet irradiation, the residual potential was seen to decrease, and at the same time a slight increase of the hardness of the photoreceptor surface was detected. These behaviors originate from a decrease in the density of charge transport sites which is caused by the photochemical changes in the charge transport layer system.

Ceramics were prepared by hot pressing of chemical mixtures of turbostratic boron nitride with copper. A positive effect of copper on boron nitride crystallization and densification has been found. Preferred orientation of boron nitride grains has been revealed in such ceramics, being opposite to general experience: the c-axis of boron nitride crystallites was arranged preferably within a plane perpendicular to the direction of uniaxial pressure. Such an arrangement is interpreted as a result of the uniaxial compression of the boron nitride grains extensively growing within the c crystallographic axis.

Nanometer-sized In particles (5−45 nm) embedded in the Al matrix were prepared by using melt-spinning and ball-milling techniques. Different crystallographic orientationships between In nanoparticles and the Al matrix were constructed by these two approaches. Melting behavior of the In particles were investigated by means of differential scanning calorimetry (DSC). It was found that the epitaxially oriented In nanoparticles (with the Al matrix) in the melt-spun sample were superheated to about 0−38 °C, whereas the randomly oriented In particles in the ball-milled sample melted below its equilibrium melting point by about 0−22 °C. We suggest that the melting temperature of In nanoparticles can be either enhanced or depressed, depending on the epitaxy between In and the Al matrix.

The Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation is frequently used to describe phase transformations involving nucleation and growth. The assumptions used in the derivation of this equation, however, are frequently violated when making experimental measurements; use of the JMAK equation for analyzing such data can often produce invalid results. Finite-size effects are among the most serious of these problems. We present modified analytic JMAK equations that correct for the finite-size effects and are roughly independent of both the sample shape and the shape of the growing nuclei. A comparison with computer simulations shows that these modified JMAK equations accurately reproduce the growth behavior over a wide range of conditions.