The annihilation of thermal donors in silicon by rapid thermal annealing (RTA) has been studied with deep-level transient spectroscopy. The electron trap AO (Ec – 0.13 eV) observed after heat treatment at 450 °C for 10 h, which is identified with the thermal donor, disappears by RTA at 800 °C for 10 s. However, four electron traps, A1 (Ec 0.18 eV), A2 (Ec – 0.25 eV), A3 (Ec – 0.36 eV), and A4 (Ec – 0.52 eV), with the concentration of ∼1012 cm−3 are produced after annihilation of thermal donors by RTA. These traps are also observed in silicon which receives only RTA at 800 °C. This indicates that traps A1–A4 are thermal stress induced or quenched-in defects by RTA, not secondary defects resulting from annealing of thermal donors.

Liquid binary alloys Cs–Sb and Cs–As are able to intercalate into graphite, provided that their compositions are neither too rich nor too poor in cesium. Several phases, whose stage varies between 1 and 4 in the case of antimony, and between 1 and 3 in the case of arsenic, have been observed. These new ternary compounds have been characterized by x-ray measurements.

We have used transmission electron microscopy and optical microscopy to examine the effect that grain size and heat treatment have on twinning and microcracking in polycrystalline Y1Ba2Cu3O7−δ. It is shown that isothermal oxygenation heat treatments produce twin structures consisting of parallel twins, with a characteristic spacing that increases with increasing grain size. Slow cooling through the temperature range where the orthorhombic-to-tetragonal transformation induces twinning, however, produces a structure consisting of a hierarchical arrangement of intersecting twins, the scale of which appears to be independent of grain size. It is also shown that the microcracking induced by anisotropic changes in grain dimensions on cooling or during oxygenation can be suppressed if the grain size of the material is kept below about 1 μm. The results are examined in the light of current models for transformation twinning and microcracking and the models used to access the effect other processing variables such as oxygen content, doping or heat treatment may have on the microstructure of Y1Ba2Cu3O7−δ.

Films of Y–Ba–Cu–O have been reproducibly prepared with metal stoichiometry near 1-2-3 by sputter deposition from a single sintered target. Twenty-seven depositions resulted in films with a standard deviation in composition of 1%. For 30 samples deposited on (100) SrTiO3 and annealed, the mean and standard deviation of the critical temperature, Tc (10% above ρ = ο), was 86.2 ± 1.4 K with a transition width (10–90%) of 1.8 ± 1.1 K. The composition and Tc were independent of film thicknesses from 0.09 to 2.5 μm. Critical currents were calculated for samples as a function of thickness from transport and from magnetization measurements. Within the considerable scatter observed of ± half an order of magnitude, the two methods agreed with each other over the thickness range studied. They were both fit with an initial Jc independent of thickness, t, for films up to about 0.3 μm thick followed by a 1/t decrease in Jc for thicker films. Metallographic examination of these films indicated microstructural features consistent with this behavior. Planar TEM images of 0.10 μm thick films showed that high Jc correlated with a film which predominantly has its c-axis normal to the film plane. An alternative structure was also seen, in which regions of the firm had their c-axis along each of the three 〈100〉 SrTiO3 directions, two in the film plane, and one normal to it. This type of film has a much lower Jc.

The kinetics of the reactions that lead to the formation of YBa2Cu3O7−x was investigated starting from various powder mixtures containing different reactants as sources of Ba, Cu, and Y (BaCO3, BaO, CuO, Y2O3. Y2Cu3O5. and BaCuO2). These powders were calcined at 940 °C for various time intervals. Quantitative x-ray analysis was used to determine the relative amounts of the compounds present in the calcined powders. When BaCO3 was used as the source of barium, long calcination times were required to obtain the single phased YBa2Cu3O7−x because of the slow decomposition of BaCO3. This leads to large particles and broad particle size distributions and hence to a lower density of the sintered superconducting pellets. Procedures to attain high density superconducting material are identified on the basis of the kinetic studies. Each of them isolates the slow reaction in a first step and prepares the superconducting material via a rapid reaction in a second step. The kinetic studies reveal the reaction mechanisms that were followed in different cases.

We report the effect of inhomogeneities on the electrical resistivity and ac magnetic susceptibility in Aurivillius-like bismuth mixed phase oxides of the BiO–CuO–(Sr0.5,Ca0.5)O system and propose a crystal structure of the major phase having highest Tc. Nominal Aurivillius compositions with molar ratios of BiO/(Sr0.5,Ca0.5)O = 1/2 are superconductors with Tc ranging from 83 to 107 K, and are accompanied by a large expansion during sintering due to the formation of Kirkendall voids. Tc increases with decreasing of the c lattice parameter. An oxide BiSrCaCu2Ox (n = 2) shows a maximum Tc value of 107 K and an onset of superconductivity at a much higher temperature. It seems that the structure of Bi2Sr2CaCu2Ox consists of an Aurivillius-like phase having two perovskite layers and a Popper mixed phase. The ac magnetic susceptibility showed an overall decrease in susceptibility with time up to 220 days. This appears to be related to the relief of intralattice strain.

Two upper critical fields normal (Bc2⊥) and parallel (Bc2∥) to the surfaces of both single-crystal and polycrystalline Nb films are studied at 4.2 K in relation to the purity and morphology of the films, in order to make properties of the single-crystal films clear. High-quality single-crystal Nb films (with transition temperature Tc of ∼9.3 K and normal resistivity ρn of ∼0.2 μΩ · cm) are found to have magnetic properties characterized by Bc2⊥ of 0.31 T as low as Bc2 (bulk upper critical field) of bulk Nb, and Bc2∥/Bc2⊥ of ∼1.85 as high as Bc3/Bc2 (where Bc3 is the surface nucleation critical field) of pure Nb. These properties depend strongly on high purity and surface smoothness of the films, which is naturally accompanied by superconductivity. Polycrystalline Nb films have higher Bc2⊥ and lower Bc2∥/Bc2⊥, which result from a decrease in purity of the films and a presence of normal-conducting niobium-suboxide layers at the surfaces of the films, and thereby a decrease of the surface effect in the films.

The microstructure of boron-doped Ni3Al powder has been characterized by optical and transmission electron microscopy. Remarkable variations in the solidification morphology and phase reaction were observed as a function of powder size. The degree of boron segregation appeared to be reduced significantly, as the formation of M23B6 boride was suppressed in powder below ∼30 μm diameter. The primary solidification phase was disordered γ–Ni, which underwent a solid-state ordering transition to produce fine γ′–Ni3Al antiphase domains. A bi-modal distribution of domain sizes was observed due to Al segregation. The solidification morphology was dendritic for particles above ∼20 μm, and it changed to cellular below. In powder less than 40 μm diameter, second-phase particles of β–NiAl were found in intergranular regions, likely due to a metastable eutectic reaction of L ⇉ γ + β. The β phase was suppressed only for powder sizes below ∼2 μm. Judging from the tendency of second-phase formation, the Ni3Al–B powder appeared to cool slower than arc-hammer foil and melt-spun ribbon.

This paper describes the effect of grain shape on environmental embrittlement in boron-doped Ni3Al (24 at. % Al). The alloy showed severe embrittlement when tested at 600 and 760 °C in air. The embrittlement can be alleviated by control of grain shape, and the material with a columnar-grained structure produced by directional levitation zone remelting shows good tensile ductilities when tested in oxidizing environments. The columnar-grained structure with vertical grain boundaries minimizes the normal stress and consequently suppresses nucleation and propagation of cracks along the boundaries.

Iron-chromium-phosphorus (Fe–Cr–P) alloys were prepared by electrodeposition from an acidic citrate electrolyte using sodium hypophosphite as the source of phosphorus. These alloys form a passive oxide layer when exposed to air and are useful as protective coatings on steel. The current efficiency of the plating process reaches a maximum of 20% at a current density of 100 mA/cm2 where the alloy has 10% Cr and 19% P. X-ray diffraction patterns and TEM analysis show that the alloy is amorphous. TEM results also indicate that small oxide particles (5–20 nm) are dispersed in the amorphous structure. Besides Fe, Cr, and P, the alloys contain a low level of oxygen (4–7%) in the form of mixed iron and chromium oxides, as confirmed by AES analysis. When heated, the amorphous structure transforms into a mixture of Fe3P and Cr3P, along with α–Fe–Cr grains. This phase transformation occurs in the temperature range of 450–460 °C for alloys with 19% P.

A lattice statics Green's function method is described for calculating the atomistic structure of a solid near a grain boundary interface. First, a reference state is defined which is ‘near’ the equilibrium state. The Green's function for the reference state is obtained in terms of the perfect lattice Green's function by mapping the lattice sites of the reference state to the perfect lattice sites and solving the Dyson's equation within a supercell. This Green's function gives the response of the reference state which determines the atomic relaxations under the net forces which would be present in the reference state. The specific case of a ∑5 tilt boundary in a fec lattice has been considered, assuming the validity of the harmonic approximation.

The lattice statics Green's function method for calculation of the atomistic structure of grain boundary interfaces in solids as described in Part I is extended to include anharmonic effects. It is shown that the ‘anharmonic’ response of a solid to ‘anharmonic’ forces can be represented in terms of the ‘harmonic’ response of the solid to an effective anharmonic force. The Green's function method then requires solving a finite order nonlinear matrix equation, which is done by using standard numerical methods. For the purpose of illustration, the method is applied to calculate the atomistic structure of a ∑5 tilt boundary in fec copper.

Using TEM, Auger spectroscopy, EDX, and convergent beam electron diffraction, a thorough characterization of the interphase region between SCS6 fibers and Ti–6Al–4V matrix in a metal matrix composite has been performed. The interphase region is shown to be very complex, consisting of numerous layers of varying compositions and thicknesses. The chemical interaction of the fiber and matrix results in a 0.5–1.5 μm thick TiC layer. Evidence for the existence of a Tix Siy (C) layer is also presented. The SCS6 overlayer on the fibers has inhibited any chemical interaction between the matrix and the SiC filament itself, 60% of the interphase region originating from the SCS6 protective coating. In situ fracture experiments (in an Auger spectrometer) reveal that fracture takes place between the TiC and an amorphous carbon layer.

Lateral diffusion couples containing Al islands on Pd–Si multiple layers are used to study Al–Pd2Si reactions. The Pd2Si phase was first formed in the Pd–Si multiple-layer region after furnace annealing at 225 °C. Then, the Al–Pd2Si lateral couples were in situ annealed in a transmission electron microscope at temperatures ranging from 377–438 °C. The laterally growing region is composed of the Al3Pd2 compound and Si precipitates, as identified by selected area diffraction (SAD). During the in situ anneals, transmission electron microscopy (TEM) images were recorded by a video cassette recorder allowing thereafter a kinetic study. The lateral growth is parabolically dependent on the annealing time. An activation energy of 1.7 eV is found for this diffusion process.

The microstructure of Al films deposited on SiO2 using the partially ionized beam (PIB) deposition technique is studied. It is shown that by employing less than 1% ions (ion-to-atom ratio) derived from the evaporated material and about 1–2 kV bias voltage at the substrate during deposition, one can grow highly (111) oriented Al films at room temperature. For a fixed bias potential, the value of the ion-to-atom ratio to achieve the optimum orientation effect is determined. At the optimum condition for the (111) preferred orientation growth, no significant enhancement in the grain size is observed. It is also found that a drastic reduction in the degree of the preferred orientation occurs when the films are deposited at a substrate temperature greater than 150 °C.

Isotropic hexagonal BN (h-BN) films were deposited on SiO2 crucibles used for synthesis of GaAs. Deposited films were analyzed for composition, morphology, and growth rates using proton resonant scattering, optical absorption, x-ray and electron diffraction, and transmission electron microscopy. The silicon concentration of GaAs synthesized in BN coated crucibles was approximately one order of magnitude higher than that for GaAs synthesized in uncoated crucibles under identical synthesis conditions.

Mechanical properties of GaP crystals are investigated in the temperature range 600–900 °C by means of compression tests. Stress-strain characteristics of a GaP crystal in the temperature range 600–800 °C are very similar to those of a GaAs crystal in the temperature range 450–600 °C. The dynamic state of dislocations during deformation is determined by means of the strain-rate cycling technique. The deformation of GaP is found to be controlled by the dislocation processes the same as those in other kinds of semiconductors such as Si, Ge, and GaAs. The velocity v of dislocations that control deformation is deduced to be v = v0 τ exp(–2.2 eV/kT) as a function of the stress τ and the temperature T, where v0 is a constant and k the Boltzmann constant. The Portevin-LeChatelier effect is observed in the stress-strain behavior in the deformation at high temperatures and under low strain rates, which may be attributed to the locking of dislocations by impurities or impurity-defect complexes.

The mechanical behavior of GaAsP alloy semiconductor was investigated by means of compressive deformation and compared with those of GaAs and GaP. The nature of collective motion of dislocations during deformation was determined by strain-rate cycling tests. The dynamic characteristics of dislocations in GaAsP were found to be similar to those in elemental and compound semiconductors such as Si, Ge, GaAs, and GaP. An alloy semiconductor has a component of the flow stress that is temperature-insensitive and is absent in compound semiconductors.

The deposition of hydrogenated and fluorinated silicon-germanium alloys (Si1−xGex:H.F) by glow discharge decomposition of silicon tetrafluoride (SiF4) and germane (GeH4) mixtures has been studied. Optical emission spectroscopy (OES), for the analysis of the emitting species in plasma phase, and mass spectroscopy (MS) for the analysis of the stable species, are used for the plasma diagnostics. In addition, in situ measurements of the deposition rate by laser interferometry are performed. A series of alloys with germanium content ranging from 0 to 55% has been prepared by varying the gas compositional ratio. Data on the optical gap (Ec), sub-gap absorption, and photo-to-dark conductivity ratio (δσ/σ) are used to evaluate the quality of the materials. An alloy a–Si0.75Ge0.25: H, F having Ec δ 1.5 eV and δσ/σ = 104 has been prepared by adding 1% of GeH4 to SiF4 in the feed.

Thin carbon films grown from a low pressure methane-hydrogen gas mixture by microwave plasma enhanced CVD have been examined by Auger electron spectroscopy, secondary ion mass spectrometry, electron and x-ray diffraction, electron energy loss spectroscopy, and electron microscopy. They were determined to be similar to natural diamond in terms of composition, structure, and bonding. The surface morphology of the diamond films was a function of position on the sample surface and the methane concentration in the feedgas. Well-faceted diamond crystals were observed near the center of the sample whereas a less faceted, cauliflower texture was observed near the edge of the sample, presumably due to variations in temperature across the surface of the sample. Regarding methane concentration effects, threefold {111} faceted diamond crystals were predominant on a film grown at 0.3% CH4 in H2 while fourfold {100} facets were observed on films grown in 1.0% and 2.0% CH4 in H2. Transmission electron microscopy of the diamond films has shown that the majority of diamond crystals have a very high defect density comprised of {111} twins, {111} stacking faults, and dislocations. In addition, cross-sectional TEM has revealed a 50 Å epitaxial layer of β3–SiC at the diamond-silicon interface of a film grown with 0.3% CH4 in H2 while no such layer was observed on a diamond film grown in 2.0% CH4 in H2.