In order to elucidate a mechanism for exoelectron emission from metallic glasses during heat treatment, metallic glasses Fe40Ni38Mo4B18, which have a 140 K lower crystallization temperature than the metallic glasses Fe78B13Si9 reported previously, were heated up to 723 K with a constant heating rate of 0.5 K/s under ultrahigh vacuum condition. Although specimens were not excited by ionizing radiations, mechanical treatment, or chemical processes prior to measurements, exoelectrons have been detected for the first heating cycle. However, in the subsequent heating cycles, the counting rate does not exceed the background level. These results agree well with our previous report about metallic glasses Fe78B13Si9, but it is recently found that from the present glasses exoelectrons are emitted from the lower temperature region, and the total number of emitted exoelectrons is larger than that from the previous glasses. An atomic force microscopy (AFM) study reveals many crystallites formed on the surface of the heated specimen, and the spatial density of crystallites on the surface is much higher than that of previous glasses. Both results of exoelectron measurements and AFM observations show that the number of emitted exoelectrons increases with increasing the number of crystallites on the surface. This result implies that exoelectrons are emitted associated with the crystallites formation process on the surface.

Direct observations of dislocation arrangements about a range of microindentations into the [100] face of an Fe−3 wt. % Si single crystal have been accomplished. Dislocations of both large loop character initiated from the indenter and small loop character initiated as secondary reactions are found. Analysis of these allows the various contributions to the plastic strain gradient around the indentation to be assessed, with the experimental observations being reasonably consistent with continuum models.

Particle size distributions derived from SEM micrographs of well-separated diamond particles, deposited on Si(100) substrates by the hot filament CVD method, have been analyzed in connection with previous measurements of particle growth rates. Rates of nucleation have been obtained from this analysis in an extended range of deposition conditions. A previously developed nucleation model has been utilized, and the kinetic parameters provide a framework for modeling the nucleation process from the gas phase.

Thermodynamic and structural properties of fcc- and hcp-based Ti–Al alloys are calculated from first-principles and are used to perform an ab initio study of phase stability for the intermetallic compounds in this system. The full potential linear muffin tin orbital method is used to determine heats of formation and other zero-temperature properties of 9 fcc- and 7 hcp-based intermetallic compounds, as well as of elemental fcc and hcp Ti and Al. From the results of these calculations, sets of effective cluster interactions are derived and are used in a cluster variation method calculation of the solid-state portion of the composition-temperature phase diagram for fcc- and hcp-based alloy phases. The results of our calculations are compared with those of experimental studies of stable and metastable phases in the Ti–Al system.

Zone-melting recrystallization (ZMR) with a graphite strip heater is used to improve the material quality of thin film structures for microelectronic applications. The process takes place in a sealed chamber filled with an inert gas such as argon or helium. The effect of natural convection and conduction at the interface between the gas and film structure was studied both numerically and experimentally. Numerical simulations of the temperature profile in the film structure, and the flow pattern and temperature field in the gas were developed. Experimental observations in a scaled setup using a liquid medium verified the flow patterns calculated from the numerical model of the gas flow in the chamber. Results indicated that the gas is stagnant in the region below the strip heater; consequently, conduction from the strip heater to the wafer is prevalent. Outside the stagnant region, natural convection cools the film structure. These two effects combine to create a steeper thermal gradient across the entire wafer which can increase the thermal stresses in the film. The magnitude of this thermal gradient depends strongly on the thermal diffusivity of the gas. The configuration of the strip heater may significantly affect the amount of heat conduction in the stagnant region.

In the framework of a previously developed kinetic model, a discriminating criterion is established to distinguish between classical and nonclassical nucleation of diamond at solid surfaces. The two-step model gives the non-steady-state nucleation density function in terms of the rate constants for active site → germ, germ → active site, and germ → nucleus kinetic steps. The criterion states that α/β > 6 is a necessary condition for classical nucleation at surfaces to occur, α and β being functions of the rate constants which can be obtained by appropriate analysis of the experimental data. This criterion is applied to recent results on diamond nucleation at silicon surfaces and indicates nonclassical results The expression of the nonequilibrium Zeldovich factor, Z, is also found in the form Z = [1 + K/nd]−1, K and nd being the rate constants for the germ → nucleus and germ → active site steps, respectively. An estimation of the rate constants is reported and the corresponding Zeldovich factor is evaluated to be 0.6 for nucleation at both Si(100) and Si(111) substrates.

A combination of in situ transmission electron microscopy and thermogravimetric techniques has been used to follow the manner by which phosphorus addition to graphite influences its interaction with oxygen. Direct observation of the process shows that the additive completely inhibits the reaction at temperatures below 830 °C. At higher temperatures phosphorus species are found to bond preferentially to the graphite “armchair”{1120} faces leaving the “zigzag” {100} faces vulnerable to attack by oxygen. In situ electron diffraction analysis indicates the formation of a chemical bond between the phosphorus and graphite edge atoms at high temperatures, which involves the formation of a complex believed to become an integral part of the structure. This unique type of chemical bonding is believed to be responsible for the observed thermal stability of P–O species on the graphite atoms at temperatures up to 1050 °C. In a further series of experiments, phosphorus was found to poison the catalytic activity of cobalt, which in its unadulterated state is a very effective promoter of the graphite-oxygen reaction.

Sequential deposition of Pd/AuGe/Ag/Au and rapid thermal annealing at 450 to 550 °C were employed to form a shallow ohmic contact to n–Alx Ga1−x As. Contact resistivity was in the range of (0.7–1) × 10−5 at x = 0.3 to (2–4) × 10−5 ohm-cm2 at x = 0.55. Limited interfacial reaction was verified by ion backscattering and x-ray diffraction techniques and attributed to the stability of Au–Ag solid solutions against underlying substrates. Contacts form at 450 to 500 °C, possibly via solid-state reaction, whereas liquid phase reaction may take place at 550 °C.

In2O3–SnO2 films were produced by thermal decomposition of a deposit which was dip coated on borosilicate glass substrates from an acetylacetone solution of indium and tin acetoacetonate. Thermal analysis showed complete pyrolysis of the organics by 400 °C. The thermal decomposition reaction generated acetylacetone gas and was found to be first order with an activation energy of 13.6 Kcal/mole. Differences in thermal decomposition between the film and bulk materials were noted. As measured by differential scanning calorimetry using a 40 °C/min temperature ramp, the glass transition temperature of the deposited oxide film was found to be ∼462 °C, and the film crystallization temperature was found to be ∼518 °C. For film fabrication, thermal decomposition of the films was performed at 500 °C in air for 1 h followed by reduction for various times at 500 °C in a reducing atmosphere. Crystalline films resulted for these conditions. A resistivity of ∼1.01 × 10−3 Ω · cm, at 8 wt. % tin oxide with a transparency of ∼95% at 400 nm, has been achieved for a 273 nm thick film.

On the basis of an analysis of experimental data on nucleation rates performed in the preceding paper in this issue, patterns of the process of diamond nucleation from the gas phase on Si(100) substrates have been drawn. A kinetic scheme is proposed which is apparently able to describe the complex behavior of the system in the temperature range 750 K−1225 K, at (CH4/H2) ratios between 0.5 and 2% and at a total pressure of 100 mbar. The model postulates a distribution function of the nucleation centers over the heats of adsorption of active gaseous species and introduces a cut-off criterion based on the necessary condition that adjacent active sites coexist for times longer than the characteristic time of germ growth. Nucleation centers, active sites, germs, and nuclei have been defined by simple molecular models and their rates of transformation discussed, using available literature data.

A new method for tensile testing of thin films is presented. The strain is measured directly on the unsupported thin film from the displacement of laser spots diffracted from a thin grating applied to its surface by photolithography. The diffraction grating is two-dimensional, allowing strain measurement both along and transverse to the tensile direction. In principle, Young's modulus, Poisson's ratio, and the yield stress of a thin film can be determined. Cu, Ag, and Ni thin films with strong ⟨111⟩ texture were tested. The measured Young moduli agreed with those measured on bulk crystals, but the measured Poisson ratios were consistently low, most likely due to slight transverse folding of the film that developed during the test. The yield stresses of the evaporated Cu and Ag thin films agreed well with an extrapolation of the Hall-Petch relation found for bulk materials. Ni thin films are known to deviate from a bulk Ni Hall–Petch relation for submicron grain sizes, and sputtered Ni films show much higher yield stresses than electrodeposited or vapor-deposited films of similar grain size. Our sputtered Ni films had higher yield stresses than other sputtered films from the literature.

6061 alloy matrix composites reinforced with β–SiC whiskers were fabricated both by squeeze casting and by hot-pressing and were heat-treated in the temperature range between 600 °C and 800 °C. The changes in interface microstructure were observed by transmission electron microscopy. In all treatment conditions, no special reaction product, e.g., Al4C3, were observed except for fine γ–Al2O3 particles adhering to the whiskers. A direct lattice connection at the whiskers/matrix interfaces was observed in all composites. β–SiC whiskers were proved to be quite stable in the 6061 matrix.

High-resolution transmission electron microscopy (HRTEM), electron diffraction, and electron energy-loss spectroscopy (EELS) were used to characterize electron-beam-induced structural transformations in crystalline samples of C60 and C70. During these transformations, the electron-diffraction patterns became progressively more diffuse, with the outer diffraction spots disappearing first, followed in succession by the disappearance of the inner spots. We interpret this course of evolution in the diffraction patterns as evidence of degradation of the crystalline structure via the destruction of individual molecules, as opposed to electron-beam-induced motion of intact fullerene molecules. EELS analyses of the data indicate that the final state of these transformations was amorphous carbon.

An incubation time exists for the formation of MoSi2 by mechanical alloying (MA). For the particular milling conditions employed, the bulk of MoSi2 formation occurs between 3 h and 12 min and 3 h and 13 min. This abrupt formation of MoSi2 during MA suggests that the reaction occurs by a form of self-propagating high-temperature synthesis (SHS), when a critical amount of stored energy (in the form of interfacial energy and cold work) is introduced by MA, and increases the adiabatic reaction temperature sufficiently to make the reaction self-sustaining.

Diamond films were grown by microwave plasma-assisted chemical vapor deposition using mixtures of 13CH4 and CO. Mass spectrometry was used to identify CO, CH4, and C2H2 as the stable gaseous products in the reactor exhaust gas. By comparing gaseous 13C compositions with that of the diamond films, the efficiency of diamond growth from methane (possibly via the methyl radical) is found to be about two orders of magnitude higher than that for carbon monoxide. Most of the diamond that is formed from the CO reagent results from the conversion of CO to hydrocarbons. The conversion of CO to hydrocarbons is attributed to activation of CO by high-energy electrons in the plasma.

Thin copper films are deposited onto glass and irradiated, in air, by means of a scanned Ar+ laser beam. The kinetics of oxidation are measured by an interferometric method. The laser-synthesized oxide films are characterized by optical microscopy, scanning tunneling microscopy, and optical spectroscopy. It is shown that the oxidation kinetics, as well as the structural and optical properties of the oxide, depend on the laser beam power and on the initial thickness of the copper film. It is argued that these facts are related to the thermal history of the samples under laser irradiation.

The carbon deposits on graphite electrodes formed during the electric discharge in a chamber used for fuUerene production contained nanotubules and fullerenes. X-ray and high resolution transmission electron microscopy investigation revealed that the deposits consisted of strongly deformed graphite microblocks. The nanotubules were found at boundaries of microblocks where carbon hexagonal planes were strongly distorted, suggesting that nanotubules were formed during atomic carbon condensation.

Mechanical attrition of intermetallic compound TiNi powder was carried out in two different ball mills and as a function of milling temperature. The microstructural changes with milling time were followed by x-ray diffraction, TEM, and DSC. The more energetic Spex shaker mill provided a higher degree of lattice strain and rapidly refined the grain size to the nanometer size regime. Amorphization was observed in the Spex mill with a linear increase in the milling time for amorphization with increasing milling temperature. No amorphization was observed in the less energetic vibratory mill, and the grain size saturated to a constant value of 15 nm after ≥60 h of milling. A critical grain size for the amorphization of 4–5 nm was estimated from the temperature dependent studies in the Spex mill. The grain boundary energy (706 mJ/m2), estimated from the vibratory mill experiments, and the above critical grain sizes (5 nm) for amorphization were used to calculate the enthalpy supplied by the nanocrystalline grain boundaries. The calculated value of 4.1 kJ/mol was comparable to the measured enthalpy of crystallization of 3.2 kJ/mol. It is concluded that the nanocrystalline grain boundary energy is responsible for driving the crystalline-to-amorphous phase transformation induced by mechanical attrition in TiNi.

Indium-doped zinc oxide (IZO) films were prepared by the spray pyrolysis technique. The effect of gradual incorporation of indium cations on the structural, electrical, and compositional properties of IZO films was studied in detail. It was observed that even a small addition of indium modifies the preferred growth of IZO film from the [002] direction to the [101] direction. Such a modification in growth pattern is a result of more nucleating centers created by indium doping. Indium dopant improves the electrical properties of the films. The carrier concentration depends mainly on the indium dopant level while the mobility is affected by the changes in crystal orientation that take place due to addition of dopants. X-ray photoelectron spectroscopy results show that indium doping does not lead to any stoichiometric changes in the IZO films and the dopant incorporation in the film is linearly proportional to that in the solution.

When NB is moles of oxygen atoms dissolved into an Si wafer of NA moles, the concentration of oxygen atoms in the Si wafer is given by mole fraction as XB = NB/(NA + NB), and the degree of supersaturation is defined by σ = (XB/XBS,T) – 1 where XBS,T is the mole fraction of the saturated state at temperature T. We have proved that σ is equal to the chemical potential difference of oxygen atoms in between saturated and supersaturated states if σ ≪ 1. Here the spontaneous generation rate is proportional to σγ, where γ is the number of the oxygen atoms in the critical oxide particles in the Si wafers. Duration time of a low temperature heating (at about 700 °C) will determine the number of nuclei for oxide precipitates, and a treatment near 950 °C is very effective on growth of oxide particles, because growth of the oxide particles is determined by diffusion of the atoms. Before the low temperature treatments, preheating at a temperature higher than 1000 °C is effective in dissolving Si–O pairs and making interstitial oxygen atoms, where the Si–O pairs have been generated by the cooling stage after the crystal growth.