The structure of Ti4Ni4Si7 is studied using powder neutron diffraction and Rietveld analysis. Prccise determination of the crystalline parameters, atomic positions, and temperature factors is achieved. A criterion previously elaborated for the phase TiFeSi2 is used to determine the coordination number. From the arrangement of the atoms in the unit cell and their interbond distances, we find that Si atoms are nearest neighbors to Ti and Ni. An extension of the same criterion shows that Ti–Ni and Ni–Si hybridization is likely to be strong while Ti–Ni hybridization is weak. A comparison with mono- and disilicides is made.

Differential scanning calorimetry and transmission electron microscopy have been used to study thermal fatigue due to diffusionless phase transformation cycling in pure cobalt. Thermal cycling through the allotropic (hcp ↔ fcc) transformation results in a temperature shift of the calorimetric peaks, which means a delay of the transformation. In addition, the transformation enthalpy, which is greater on heating than on cooling, diminishes when the number of transformation cycles increases. This is interpreted as being due to an evolution of the microstructure. Transmission electron microscopy shows the appearance of transformation-induced defects, which are mainly sessile dislocations. We can interpret the calorimetry results (enthalpy evolution and transformation delay) as due to the interactions between interface dislocations and these sessile dislocations.

Compositional analysis of thin nanoscale native oxide films formed on {001} silicon wafer surfaces at room temperature was done with an electron energy loss spectrometer coupled to an analytical electron microscope having a field emission source, with better than 4 nm spatial resolution. The electron energy loss spectra show a shift in the threshold onset energy of the Si–L edge of the native oxide from ∼99 eV loss corresponding to pure elemental silicon to ∼105 eV loss, and elemental analysis using the ionization regions of the core loss edges showed the composition to be SiO, within a few percent. Microdiffraction and high resolution electron microscopy (HREM) results showed that the native oxide was completely amorphous, and did not contain detectable nanocrystals. The native oxide can be removed from the Si surface by heating in UHV for a short time at 1000 °C. However, this procedure resulted in the formation of small amounts of a crystalline phase on the Si wafer surface, which was shown to be β-SiC by the same methods.

The structure of a near coincidence Ge tilt grain boundary, containing a step, has been derived from a high resolution electron micrograph. There are two possible interpretations of portions of this interface, one of which is the existence of a sheet of fivefold coordinated atoms between the Σ = 19 and Σ = 27 coincidence misorientations. This finding may represent the first experimental evidence that overcoordinated atoms are present at semiconductor grain boundaries free of a screw dislocation.

The chemical stability of the surface of stainless steel (SUS) 304 in acid immersion tests is greatly improved by the laser implant-deposition (LID) process, i.e., the simultaneous deposition and incorporation of silicon by KrF excimer laser irradiation. The etching depths of the treated samples in 1.32 N HCl solution are substantially zero at the laser irradiation conditions of more than 40 pulses and of more than 400 mJ/cm2 at the surface. By the quantitative verification of cathodic polarization in 1 N H2SO4, the highest polarization resistance is estimated to be 26.7 times that of the nontreated sample.

The decomposition of the intermetallic compound PdSi by adding a small amount of Ag has been investigated by thermal analysis, metallographic measurement, and x-ray photoemission spectroscopy (XPS). Within the range of Ag concentration from 0 to 6 at.%, PdSi is decomposed in linear proportion to the concentration of Ag into Si and the ternary compound Pd2Si(Ag), which has the ratio of 16 PdSi molecules per single Ag atom. The PdSi is fully decomposed at Ag 10 at.%. In the ternary alloy included in the Pd–Si–Ag alloy involving Ag below 12 at. %, the atomic ratio of Si to metal atoms, which are Pd plus Ag, is nearly the same as the ratio in Pd-rich Pd2Si. Metallographic and XPS measurements indicate that the Ag atom included in the PdSi behaves as an electron donor with a large radius of the wave function; the Ag electron transfers to the anti-bonding state of PdSi and acts to decompose the compound. The Ag atoms seem to occupy the sites of Pd atoms in Pd2Si(Ag) which has been decomposed from PdSi.

Diamond films grown by Bias-Controlled Hot Filament Chemical Vapor Deposition (BCCVD) on silicon (Si) substrates were characterized by Transmission Electron Microscopy (TEM). Both plan-view and cross-sectional TEM samples were made from diamond films grown under different biasing conditions. It was found that defect densities in the films were substantially reduced under zero and reverse bias (substrate negative relative to the filament) as compared to forward bias. Furthermore, the diamond/Si interface of the reverse and zero bias films consisted of a single thin interfacial layer whereas multiple interfacial layers existed at the diamond/Si interface of films grown under forward (positive) bias. Tungsten (W) contamination was also found in the interfacial layers of forward bias films. It is concluded that forward biasing in the present condition is not favorable for growing high quality, low defect density, diamond films. The possible mechanisms which induced the microstructural differences under different biasing conditions are discussed.

The Nb donor concentration and cation stoichiometry dependence of grain growth in SrTiO3 has been studied. The so-called donor anomaly, where grain growth is enhanced at low donor but suppressed at high donor concentrations, is observed only in nonstoichiometric compositions with an excess of B-site cations. Scanning transmission electron microscopy (STEM) observations indicate that this phenomenon is entirely a result of changes in the distribution of residual silicate phases. Exaggerated grain growth at low donor concentrations results from the presence of a continuously wetting grain boundary silicate, whereas inhibited growth at higher donor concentrations occurs in microstructures where the silicate phase is nonwetting. In stoichiometric compositions, however, grain growth rates are both slower and independent of donor concentration. In this composition regime grain growth appears to be limited by solid solution drag. The presence of residual silicates only in nonstoichiometric compositions implies a strong stoichiometry dependence of the silica solubility.

A Raman microprobe study of as-compacted nanophase TiO2 was carried out to investigate the spatial inhomogeneity of its anatase and rutile phases. Also, changes in the observed Raman spectra (line shifts and broadening) were investigated as a function of annealing at temperatures up to 600°C in argon or air. Microscopic phase inhomogeneity is observed and Raman spectral changes are shown to result from inhomogeneous oxygen deficiency in the nanophase TiO2. The line positions corresponding to the Raman active Eg modes in both anatase and rutile are found to be sensitive to this oxygen deficiency and are potential quantitative indicators of such deviations from stoichiometry.

Continuous indentation testing was used to measure the hardness as a function of indentation depth, of three micron thick copper films deposited on silicon with an intermediate layer of 20 nm thick chromium or titanium. Three different indenters, a nearly perfect Vickers, a Vickers with a 1.2 μm2 flat, and a Pyramid with a 25 μm2 flat were employed. The hardness data suggest that the titanium interlayer produced significantly greater film/substrate adhesion than the chromium interlayer. A compressive residual stress, which relaxed with time, was detected in the samples with the titanium interlayer.

Polyacetylene shows catalytic activity in an aqueous solution for electroless deposition of amorphous alloys. The catalytic activity of polyacetylene is comparable to the activity of some highly catalytic metals, i.e., Cu, steel, and Pt. Modifications of the Shirakawa technique led to the formation of a foam-like polyacetylene, which is highly porous and has a low degree of crystallinity. This material can be used as a catalytic substrate for the preparation of amorphous metals in bulk form. The amorphous Ni–Co–B and Ni–Co–P alloys deposited on a PAc substrate were investigated by magneto-thermogravimetry and x-ray diffraction. These investigations gave a Curie temperature of about 413 K and a crystallization temperature of about 600 K for the metal-metalloid component of the system.

This paper reports a study of the structure and fracture mode of Pt3Ga. The results show that the structure of this compound is a tetragonal distortion of the L12 structure with lattice parameters of a = 5.47 Å and c = 7.89 Å. If the gallium concentration decreases from 22.8 at.% to 21.5 at.%, a disordered face-centered cubic phase also forms. This phase is Pt-rich and appears to form along the grain boundaries of the Pt3Ga phase. The fcc phase can also contain coherent Pt3Ga precipitates. Single phase Pt3Ga fails in a very brittle manner, and the fracture mode is intergranular. Boron additions have no effect on the fracture mode, since boron does not segregate to the grain boundaries. The fracture of an alloy containing a small amount of the disordered fcc phase is also brittle, but the fracture mode is predominantly transgranular.

Electron energy loss spectral analysis of the π and (π + σ) electron plasma resonances are used to analyze the structure of hydrogenated diamond-like carbon (a-C:H) films. Energy loss peaks associated with the resonances of the π and (π + σ) plasmons in a-C:H are identified by comparison with reference spectra taken on natural diamond and on highly oriented pyrolytic graphite. The decrease in energy of the π plasmon with increasing hydrogen atom fraction provides direct experimental evidence that addition of hydrogen serves to reduce the density of π bonds in a-C:H. Under several important assumptions, the mass density, the sp3/sp2 site ratio, and the average coordination number are related to the resonance energies of the π and (π + σ) plasmons. The mass density of a-C:H samples inferred from the energy of (π + σ) electron plasma resonance is in the range from 1.46 to 1.69 g/cm3, which is in general agreement with an independent sink-float measurement. The ratio of sp3 (tetrahedral) to sp2 (trigonal) carbon sites increases from 0.29 to 0.75 and the average coordination number of each atomic site decreases from 2.6 to 2.3 as the hydrogen increases from 28 to 44 at.%. The fully constrained covalent network model is used to discuss the experimental results. The measured ratio of sp3/sp2 carbon sites and the average coordination numbers are in agreement with the predictions of the model, particularly at high hydrogen concentration.

Buried amorphous layers were produced by implantation of MeV Si+ ions in silicon single crystal at room temperature and liquid nitrogen temperature. The damage is characterized structurally both in the as-implanted condition and after post-implantation furnace annealing. Growth of the amorphous layer during room temperature implantation is found to occur by a layer-by-layer mechanism with relatively sharp interfacial transition regions. A wide region ahead of the buried amorphous region extending to the surface is observed to be free of any extended defects. Recrystallization of the damaged region during thermal annealing occurs by solid-phase epitaxial growth at both interfaces. A lower growth velocity is found at the upper interface, which is attributed to a higher hairpin dislocation density grown-in at this interface. Results of irradiation at liquid nitrogen temperature, on the other hand, show that nucleation and growth of the amorphous damage occurs over a wide region and is not confined to the interfacial region. This results in a very diffuse upper interface composed of a mixture of amorphous and crystalline phases. Substantial reordering is observed in this mixed-phase region after 400°C annealing, even though this temperature is too low for normal interfacial solid-phase epitaxial growth. Cross-sectional transmission electron microscopy, as well as Rutherford backscattering spectroscopy, were used in this study.

Titanium reacts with pure Ge in two different ways: At low temperatures one observes the formation of Ti6Ge5 with some characteristics typical of diffusion-controlled reaction. Upon completion of this first stage Ti6Ge5 reacts with remaining Ge to form TiGe2, isomorphous with C54 TiSi2, in a process which is clearly controlled by nucleation. The same observations apply to reactions with a Ge alloy containing 25 at.% Si. With an alloy containing 50 at.% Si the two stages become merged, so that while remaining identifiable, they are much less distinct than with the previous conditions. The reaction behavior observed with a Ge alloy containing 80 at.% Si resembles that generally obtained with pure Si: there are no easily identifiable steps between the initial Si–Ti sample and the final one, Si–TiSi2. With both the 50-50 and 80-20 Si–Ge alloys the formation of the C54 structure is preceded by that of the C49 structure (ZrSi2 type), as with pure Si. The gradual merging of the diffusion-controlled reaction and that controlled by nucleation as the concentration of Si in the substrate increases implies that nucleation plays a significant role in the formation of TiSi2, even if that role cannot be easily isolated. Effects due to gas impurities on the path of the metal-substrate reaction have been analyzed. The resistivities of several pure and alloyed phases have been measured. Alloy scattering in the system TiSi2–TiGe2 is briefly discussed.

Growth of amorphous-titanium-silicidc and crystalline C49 TiSi2 in titanium/amorphous-silicon multilayer films was investigated using a combination of differential scanning calorimetry (DSC), thin film x-ray diffraction, Auger depth profiling, and cross-sectional transmission electron microscopy. The multilayer films had an atomic concentration ratio of 1Ti to 2Si and a modulation period of 30 nm. In the as-deposited condition, a thin amorphous-titanium-silicide layer was found to exist between the titanium and silicon layers. Heating the multilayer film from room temperature to 700 K caused the release of an exothermic heat over a broad temperature range and an endothermic heat over a narrow range. The exothermic hump was attributed to thickening of the amorphous-titanium silicide layer, and the endothermic step was attributed to the homogenization and/or densification of the amorphous-silicon and amorphous-titanium-silicide layers. An interpretation of previously reported data for growth of amorphous-titanium-silicide indicates an activation energy of 1.0 ± 0.1 eV and a pre-exponential coefficient of 1.9 × 10−7 cm2/s. Annealing at high temperatures caused formation of C49 TiSi2 at the amorphous-titanium-silicide/amorphous-silicon interfaces with an activation energy of 3.1 ± 0.1 eV. This activation energy was attributed to both the nucleation and the early stages of growth of C49 TiSi2. The heat of formation of C49 TiSi2 from a reaction of amorphous-titanium-silicide and crystalline titanium was found to be –25.8 ± 8.8 kJ/mol and the heat of formation of amorphous-titanium-silicide was estimated to be –130.6 kJ/mol.

Optical metallography, scanning electron microscopy, electron microprobe analysis, and transmission electron microscopy were used to characterize metallurgical grade silicon, produced in an electric are furnace. Coincidence fraction determinations were assumed to be Σ7 and Σ9 when grain boundaries are underlined by precipitated phases and Σ3 when they are not. The study of intergranular compounds was emphasized; ten compounds were found, the main ones being Si2Ca, Si8Al6Fe4Ca, Si2Al2Ca, Si2FeTi, and Si2.4Fe (α leboitc). The precipitation of these compounds was discussed according to the principal impurity concentrations in silicon. The crystalline structure of Si8Al6Fe4Ca was determined to be triclinic with a = 1.3923 nm, b = 1.3896 nm, c = 1.3900 nm and α = 92.4°, β = 110.3°, γ = 119.9°.

The early-stage kinetics of interdiffusion in compositionally modulated films have been studied by Monte-Carlo simulations on an Ising lattice in two and three dimensions, using nearest-neighbor interactions. For a negative heat of mixing and below the order-disorder transition temperature, if a short-wavelength modulation is along a direction that is not consistent with long-range order, then its temporal evolution does not follow the Cahn-Hilliard-Cook theory. The modulation amplitude decreases as a function of time, rather than increases; i.e., no one-dimensional spinodal ordering is observed. This disagreement with the theory implies that ordering in three dimensions cannot be described by a one-dimensional theory.

Phase equilibria in the ternary systems M–Si–N and M–B–N (M = Cu, Ag, Au, Zn, Cd, Al, In, Tl, Sn, Pb, Sb, and Bi) at temperatures 50–100 °C below the melting point of the metal components were investigated by means of x-ray powder analysis and are represented in the form of isothermal sections. No ternary compound formation was observed in any of the combinations M–Si–N and M–B–N. Silicon nitride and boron nitride, respectively, coexist with all metals investigated and with all binary compounds stable at the chosen temperatures. From unit cell dimensions negligible mutual solid solubilities are indicated between Si3N4 or BN and the metal components.

The internal gettering of nickel in (100) silicon wafers implanted with 2.5 ⊠ 1015 argon-ions/cm2 at 280 keV has been studied by electron microscopy. Nickel deposited on the back surface is gettered by forming a discontinuous layer of nickel silicide, NiSi2, in the argon-implanted region near the front surface. Electron microdiffraction and high-resolution electron microscopy indicate that the layers of nickel silicide probably grow epitaxially on the undamaged silicon surrounding the silicide.