Binary alloys of Re–Ta, Os–Ta, Ir–Ta, Os–W, and Ir–W were vapor deposited. A wide amorphous formation range was found for all systems, except Ir–W. The crystallization temperatures were generally very high—between 800 and 1000 K.

Incorporation of bis (trifluoroacetylacetonato) copper (II), Cu (TFA)2 into poly (amide acid) prior to imidization produces bi-and trilayered composite films upon curing. Choice of curing atmosphere and concentration of dopant control the formation of a particular layered structure. Dry air and 100% relative humidity are the curing atmospheres used. The trilayered films are typified by a zero-valent copper layer sandwiched between a thin polyimide overlayer and the bulk polyimide. Curing in 100% relative humidity produces the thinnest overlayer. By doubling the dopant concentration used to prepare the trilayered films, bilayered films will result upon curing. In this instance the lack of a polyimide overlayer affords the oxidation of copper at the surface to copper (II) oxide. In each case the formation of the copper layer results from the migration of all Cu (TFA)2 from a depth of approximately 2000 Å to the surface where subsequent reactions take place. Several [Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM)] analytical techniques are used to characterize the physical and chemical nature of the films.

The adhesion of diamondlike hard carbon films to silicide forming metals was improved by using an interfacial silicon film several atomic layers thick. The use of thicker (> 10nm) silicon layers results in a decrease in the adhesion, probably due to a degradation of the structural integrity by excessive silicide formation.

The sintering process at 840°C and at 925°C, of Zr-7.2 wt. % Fe was studied by room-temperature Mössbauer spectroscopy, x-ray diffractometry, and scanning electron microscopy. According to phase analysis, most of the αFe phase disappeared after 20 h of sintering at 840°C and after 4 h at 925°C. During the sintering, small quantities of the intermetallic compound ZrFe2 as an intermediate phase were observed clearly by the Mössbauer technique and very weakly by x-ray diffractometry. The relationship among the relative quantities of αFe, ZrFe2, and Zr3Fe phases was determined. The change in density as a function of sintering time was measured, and the results were explained on the basis of the different sintering stages and phase transformations.

Nickel foils, 165 μm thick, have been carbon implanted at 300 K with 2, 3, and 4.2 × 1017 C ions/cm2 and implanted with a two-step implantation of 2.1 × 1017 C/cm2 at 300 K followed by 2.1 × 1017 C/cm2 at 77 K. All implantations performed at 300 K result in the formation of the metastablc phase Ni3C while the two-step implantation produces an amorphous Ni/C alloy. Surface mechanical property studies showed that both the surface hardness and wear properties are correlated with chemistry (carbon dose), and that the friction coefficient is additionally dependent on the surface microstructure. It was found that both the wear rate and coefficient of friction were reduced as the volume fracion of Ni3C increased. At the highest dose implanted 4.2 × 1017 C/cm7, the coefficient of friction was found to be lower for the sample implanted half at 300 K and half at 77 K and possessing an amorphous structure compared to the sample implanted entirely at 300 K and possessing a crystalline Ni3C structure. Increases in the surface hardness were also observed with increasing carbon content, with the greatest hardness observed in samples implanted to a total dose of 4.2 × 1017 C/cm2. The hardness at this dose was not dependent on the implant conditions or the metastable phase formed.

The alloy system Al–Li–Cu was investigated extensively over the composition range 5.8–8 Al–Cu–3Li to develop a detailed understanding of the formation and properties of the icosahedral phase, known as T2. Material from the various charges was analyzed by optical and electron microscopy, energy dispersive x-ray analysis, differential thermal analysis, and differential scanning calorimetry. The role of the melt composition and the solidification velocity were found to be crucial in determining the micro- and macrostructure and the existence of the icosahedral phase. A pseudobinary phase diagram for the region around Al6CuLi3, is presented based on these analyses. Based on this phase diagram the largest single icosahedral crystals of Al5.1CuLi3 yet reported, with diameters greater than 1 cm, were produced by Bridgman methods.

A Cu47Zr53 alloy was surface processed with a directed-energy electron beam. Optical microscopy, x-ray diffraction, and transmission electron microscopy were used to identify the resolidified phases obtained under systematically varied rapid solidification conditions. The results of the investigation indicate that the underlying bulk substrate always nucleates the growth of a crystalline phase that was identified as a metastable CuZr phase with an ordered bcc (B2) structure. The maximum growth velocity of this phase was determined to be between 0.05 ± 0.02 m/s. This limit was compared under different assumptions to the predictions of a reaction rate growth theory. As the solidification speed increased beyond this limit, the crystalline growth eventually ceased and glass formation occurred in the remaining undercooled liquid under rapid cooling conditions. Crystalline particles also nucleated and grew in the liquid at intermediate cooling rates. These particles had a dendritic morphology and were also a CuZr phase with the B 2 structure.

The limiting substitution of Co or Fe for Cu in the orthorhombic superconducting phase YBa2Cu3O7−δ yields the tetragonal, semiconducting compositions YBa2Cu2CoO7.25 and YBa2Cu2.5 Fe0.5O7.19 after annealing at 400°C and slow cooling in O2. Single-crystal x-ray structural analyses, conductivity and magnetic-susceptibility measurements, and thermogravimetric analysis (TGA) data provide evidence for Co or Fe substitution at the Cu (1) position and intercalation of peroxide ions (O2)2− The two compositions decompose for disintercalation of oxygen beyond O6.7 for Co and O6.4 for Fe when heated in N2. The Cu(2) atoms of tetragonal YBa2Cu4O6 appear to be antiferromagnetic below a Tn ∼ 240 K, which is similar to comparable Cu–O planar nets in stoichiometric La2CuO4.

A treatment of diffusion limited growth of a coherent spherical precipitate into supersaturated solution is presented. It is found that the growth kinetics are affected by dilatational coherency strains and by compositionally induced strains in the matrix phase. Numerical solutions to the time-dependent problem are obtained and are compared to the quasistationary solution. The parabolic growth coefficient is a function of the transformation strain, partial molar volumes of the components, elastic constants in each phase, interfacial compositions and far-field composition while, in contrast, the growth coefficient in the absence of stress is a function only of the reduced supersaturation. Elastic effects shift the interfacial concentration of the matrix in the direction of the far-field concentration, reducing the effective driving force for growth. At the same time, compositionally induced strains increase the diffusive flux, increasing the growth rate.

Numerical calculations of the diffuse scattering near Bragg reflections from coherent solute precipitates in a dilute alloy have been made. Results are presented for spherical precipitates in an elastically isotropic continous medium where the calculations have been reduced to a one-dimensional numerical integral. The scattering is separated into direct scattering from the precipitates, the Huang scattering from the lattice distortions, and the higher-order distortion scattering; calculations are presented for 50 Å radius precipitates with an internal strain of – 1.5%, and the sensitivity of the scattering to changes of the size and the internal strain of the precipitates is demonstrated. The possibility of using such scattering for the determination of the concentration, size distribution, and internal strain of solute precipitates is discussed.

With analogy to the “highly accurate” summation of cluster diagrams for hard sphere fluids à la Carnahan-Starling, a simple real space free-energy density functional for arbitrary potential systems is proposed, based on a generalization of the second virial coefficient to inhomogeneous systems, which when applied to ordered and amorphous solid hard-sphere systems yields pressures in remarkable agreement with experiment. Possibilities for corrections and extensions toward a simple density functional theory of nonuniform solids are noted.

The dynamics of a very thin dislocation loop under the influence of an externally applied, time dependent, stress field is studied in the context of continuum elasticity, where very thin means that the dislocation core is small compared to the loop's typical radius of curvature as well as to any relevant acoustic wavelengths. This is done using energy and momentum conservation as derived from a variational principle for conservative motion of the loop. Energy conservation alone does not suffice, since it is insensitive to forces that do no work. The idea is to have a theory of sources (dislocation loops) interacting with a field (particle displacement) in the same sense that classical electrodynamics is a theory of point-charged particles interacting with the electromagnetic field. The sum of elastic strain and particle velocity generated by a dislocation loop and those generated by external agents are replaced in the action functional whose extrema give the equations of classical dynamic elasticity, thus obtaining a functional of the loop's trajectory. Extrema of the action with respect to variations of the dislocation history select the trajectory that will be followed by the loop under prescribed external stresses. In general, the evolution of the loop will be governed by an integrodifferential equation. Differential equations are obtained when the work done by external forces is much greater than the elastic energy radiated, and the motion of any one point of the loop is affected only by those other loop points in its immediate neighborhood (local approximation). These equations are explicitly written down. They describe the dynamics of a string with mass and line tension of purely elastic origin. The cutoff procedure needed to give meaning to logarithmically divergent expressions is carefully described. The main ideas can be understood in the case of a screw dislocation, which is worked out in detail. The general case with two characteristic velocities, although algebraically more cumbersome, is not essentially different physically. Additional examples include the gliding edge, pinned dislocation segments, and kinks. Results presented are valid in a homogeneous, isotropic, infinite elastic solid, and ways in which these various restrictions might be lifted is discussed.

The epitaxial recrystallization rates of self-ion amorphitized layers in silicon wafers with 〈100〉 substrate orientation were measured by in situ, high precision, isothermal cw laser interferometry. With this one-sample technique the changes produced by implanted boron impurity concentrations (NB) in the activation energy Ea and preexponential V0 of solid phase epitaxy were measured for concentrations in the range 5 × 1018 cm−3 < NB < 3 × 1020 cm−3 and for temperatures from 450 to 550°C. The differential changes in Ea produced were measured to within ± 23 meV when systematic errors were eliminated. Changes in activation energy and entropy [Ea and log (V0)] were found to be linearly correlated for all concentrations. This observation is consistent with the idea that electronically active impurities alter regrowth velocities by reducing the critical temperature for disordering at some of the interfacial sites at which elementary reconstructive processes are driven by thermal fluctuations. For small Nn, the critical temperature of the impurity-modified reconstruction is estimated at 1200K, approximately 200 K below the melting temperature of amorphous silicon. The Ea decreased exponentially with NB to a concentration Ninfl, larger than the estimated equilibrium solubility limit, where there was an inflection point in the V vs NB curve. The Ea increased for values of NB larger than Ninfl, showing that the differential increase in V for higher concentrations was due to a differential increase in the activation entropy. A change in the correlation between Ea and log (V0) at Ninfl indicated that larger NB produced an additional reduction of the critical temperature of the reconstruction. For small NB, the data support a simple Fermi level shifting model for the “electronic effect” of impurities on SPE (solid phase epitaxial) regrowth.

A photoluminescence technique to characterize, for lasing wavelength, the channeled substrate buried heterostructure wafer grown for fabricating lasers for undersea transmission applications, is described. The technique consists of photopumping a piece from the as-grown wafer at 80 K to achieve lasing action and determining the lasing wavelength at 300 K after correcting for the temperature shift of the bandgap. By comparing the optically determined wavelength against the lasing wavelength measured on the device, the accuracy of the technique to predict wavelength is found to be ± 20 nm. The factors that limit the accuracy are discussed.

A memory (lock-on) phenomenon was observed in the semiconducting glasses belonging to the As–Se–Te system, and this phenomenon was studied through electrical, calorimetric, and x-ray diffraction methods. The structural characteristics were also correlated to the time it takes to reach the memory state. The growth process in composition As0.40Se0.30Te0.30 exhibited a dependence on electrode polarity in such a way that it began at the positive electrode and finished at the negative one. The growth speed of the conductive filament was found to be approximately 22μm s−1. The crystalline nature of the lock-on filament was confirmed, and the peaks corresponding to the x-ray diffraction pattern of the surface of a sample of composition As0.45 Se0.10Te0.45, partially covered by filaments, correspond to monoclinic As2Te3. The memory effects found agree with those predicted through Ovshinsky's criterion, as the average coordination numbers for the noncrystalline structures of the alloys analyzed are 2.4 and 2.3, respectively.

Damage in single-crystal β-SiC(100) as a result of ion bombardment has been studied using Rutherford backscattering/channeling and cross-section transmission electron microscopy. Samples were implanted with Al (130 keV) and Si (87 keV) with doses between 4 and 20 × 1014 cm−2 at liquid nitrogen and room temperatures. Backscattering spectra for He+ channeling as a function of implantation dose were initially obtained in the [110] direction to determine damage accumulation. However, the backscattered yield along this direction was shown to be enhanced as a result of uniaxial implantation-induced strain along [100]. Spectra obtained by channeling along this latter direction were used along with the computer program TRIM to calculate the critical energy for amorphization. The results for amorphization of β-SiC at liquid nitrogen and room temperature are ∼ 14.5 eV/atom and ∼ 22.5 eV/atom, respectively.

A well-established stability model for hydrocarbon molecules is reviewed and then applied to organometallic compounds used in the epitaxial growth of HgCdTe films. For hydrocarbon molecules, the strength of carbon-hydrogen bonds is modified by neighboring organic groups. The mechanism for this effect is delocalization of the free radical electronic charge by the neighboring groups. The delocalization effect is present in organometallic compounds and is illustrated for tellurium, mercury, and cadmium compounds. An important application of the delocalization effect is the development of a low-temperature approach for pyrolytic metalorganic growth of HgCdTe.

Here a-Si:H is prepared by ion bombardment-activated reactive evaporation of Si in a H2O residual gas pressure ranging from 10−9 to 10−7 Torr. The Si+ ions (2.7keV) are bombarding the substrate and the walls during evaporation. Two hydrogen incorporation mechanisms are revealed by H evolution experiments, depending on the H2O residual gas pressure during evaporation. In the first mechanism H is sputtered from the walls of the system by the ion bombardment; this mechanism contributes 10 at. % to the hydrogen content. In a second mechanism Si+ bombardment on the growing layer injects H from H2O molecules adsorbed on the film surface; at least 5 at. % H is incorporated by this process. The second mechanism has a remarkable influence on the microstructure as revealed from the electrical conductivity, electron spin resonance, and infrared transmission. Indeed, Si+ bombardment-induced injection of H changes the conductivity type from variable range hopping to an activated behavior, while the dangling bond density remains low (< 1018 cm −3). The growth of [SiH2]n bundles, observed by the resonance frequency and absorption strength of the stretch mode of the Si–H dipole, is also a consequence of the H injection mechanism. It is concluded that the properties of the a-Si:H, prepared by ion bombardment-activated reactive evaporation, are explained by a microstructure, dependent on the specific hydrogen incorporation mechanism.

This paper describes the complexity of the spinel iron oxides in thin-film configuration. First, the experimental deposition conditions are determined for the parameters of substrate temperature and oxygen flow such that only the “Fe3O4” phase is formed. Then a study is made of how the structural (grain size, lattice parameter, texture), magnetic (M), and optical (visible and infrared transmission) properties of the films depend on the deposition and postdeposition (air annealing) conditions. The experimental deposition region is defined where the films have the most similar physical properties to bulk Fe3O4 and subsequently, after annealing, to bulk gamma Fe2O3. Finally, a discussion is presented of a model that accounts for the anomalous, low values of the magnetic moment for the samples deposited at room temperature. The model proposes an overpopulation of the iron tetrahedral A sites.

A nominally γ-Fe2O3 thin film (oxidized from an Fe3O4 film) has been structurally depth profiled using x-ray scattering in a grazing incidence, asymmetric Bragg geometry. By varying the grazing incidence angle, the x-ray penetration depth is varied from tens of Angstroms to several thousand Angstroms, slightly larger than the film thickness. At small incidence angles a diffraction pattern characteristic of α-Fe2O3 is observed, while at larger angles the pattern is predominantly from γ-Fe2O3, showing that there is a surface layer of α-Fe2O3. These results are quantified and the thickness of the α phase found to be 90 Å. The presence of the α phase explains a nonferromagnetic layer observed previously. These data together with magnetic and chemical data suggest that the nonferromagnetic layer forms during oxidation of the Fe3O4 film due to outward diffusion of Fe ions and their subsequent oxidation to form α-Fe2O3