The glass-forming region of the BiO1.5–CuO–Ca0.5Sr0.5O system has been determined by melting 5 g batches. Glass rods 4 mm in diameter and 75 mm long have been made. The glass transition temperatures (TG) and the onset crystallization temperatures (Tx) are around 390 °C and 440 °C, respectively. Densities of these glasses range from 5.5 to 7.0 g/cm3. The glass structure consists of the [BiO3] and [BiO6] units, and the conversion between these two polyhedra mainly depends on the Ca0.5Sr0.5O amount. The molecular volume of the glasses indicated that increasing Ca0.5Sr0.5O caused loose glass structures.

Phase formation was studied for Ni/Ti/Si and Ni/TiSi2 structures processed by vacuum RTP. Intermetallic compounds Ni3Ti and Ti2Ni form sequentially above 425 °C for metal bilayers Ni/Ti on Si, as Ni diffuses into Ti. When the temperature reaches 550 °C, Si becomes mobile and diffuses into the Ni–Ti compound, resulting in the growth of a ternary phase Ti4Ni4Si7, (V phase). If Ni is in excess with respect to this ternary silicide, a separate layer of Ni silicide grows between the substrate and the V phase, due to the fact that Ni is the main diffusing species. For the case of an excess Ti, the Si atoms are the most mobile species during Ti silicidation. Below 700 °C, TiSi2 grows with a C 49 structure whereas a mixture of TiSi2 C 54 and V phase forms at high temperature, without phase separation in distinct layers. Ni is also a fast diffuser in TiSi2. The activation energy for the diffusion along the grain boundaries of the Ti silicide is about 1.25 ± 0.2 eV. For these Ni/TiSi2 samples too, the same V phase starts to grow at the metal/silicide interface.

Thermal and anodic oxide films of beta silicon carbide are analyzed using Auger electron spectroscopy. Auger depth-composition profiles are obtained in order to determine the chemical composition of the oxide films. The position and shape of silicon spectral peaks are used to estimate the chemical bonding of the oxide constituents. It is found that the wet thermal oxide is almost stoichiometric but contains about 14% carbon. Dry oxide, on the other hand, has less than 3% carbon but is highly nonstoichiometric. The carbon content in the anodic oxide is 12%. Anodic oxide films, like dry-oxide films, are nonstoichiometric. A model of the SiC oxidation process is presented.

In the interfacial reaction zone between AlN and a Ag Cu–Ti braze alloy, a previously unreported phase belonging to the η family (M6X) has been found by transmission electron microscopy. The compound has an approximate stoichiometry of (Ti3−x Cu3−xAl2x)N and space group symmetry of Fd3m, with a cubic lattice parameter of a0 = 1.13 ± 0.02 nm. Large (>1 μm diameter), defect-free grains are present with occasional {111} twinning. Grain boundaries are free of second phases and amorphous interlayers. The formation of continuous layers that grow with reaction time indicate possible stability of the η nitride at 900 °C. The presence of this phase is integral to the chemical and structural development of the ceramic-metal interface.

The surface composition and bonding of a wide variety of silicon carbide powders and whiskers have been characterized by x-ray photoelectron spectroscopy (XPS). Ultrafine SiC powders, grown by a radio frequency plasma process, have been shown to exhibit graphitic carbon and a thin suboxide coating. Whiskers of SiC, grown in a vapor-liquid-solid or proprietary commercial process, were generally covered by heavier oxides than the powders and to a variable degree showed silica-like bonding. Most of the materials were subject to sample charging. Procedures were developed to estimate these charging effects and interpret the complete catalog of XPS spectra from these materials with respect to Fermi-level assignments. Charge independent quantities, such as oxygen Auger parameter and O(1s)–Si(2p) peak position difference, were found to agree with accepted values in the literature while exhibiting trends consistent with suboxide and silica bonding assignments. The data give a broad basis for understanding the feedstock surface chemistry which is involved during fabrication of monolithic or composite silicon carbide materials.

Titanium carbide may be readily produced in high purity via direct reaction between the solid phases of titanium and carbon in the process of combustion synthesis, also known as self-propagating high-temperature synthesis (SHS). The high temperatures generated by this exothermic reaction (<3000 °C) melt the titanium phase which subsequently flows to and reacts with the solid carbon. As a result, with lightly or uncompressed green bodies a product is obtained which retains most of the carbon precursor powder morphology down to the μm scale. The effect of three distinctly different carbon precursor powders on the final titanium carbide morphology has been examined. Subsequent effects of particle size and microstructure on the quality of the titanium carbide product are also noted.

Oxygen ions were implanted into (100) oriented single crystal Si at energies in the range of 0.6 to 2 MeV at normal and oblique (60°) incidences. Oxygen concentration profiles were measured using the 16O(d, α)14N nuclear reaction for 900 keV deuterons. The experimentally measured oxygen distributions were subsequently fitted to the theoretical profiles calculated assuming the Pearson VI distribution. The distribution moments (Rp, ΔRp, ΔR⊥ skewness, and kurtosis) were deduced as the best fit parameters and compared to the computer simulation results (TRIM 87 and PRAL). Whatever the calculation method, the measured Rp and ΔRp values are close to those predicted by the theory. Deeply buried SiO2 layers were formed using a single step implantation and annealing process. A dose of 1.8 × 1018/cm2 of 2 MeV O+ was implanted into the Si substrate maintained at a temperature of 550 °C. The implanted samples were characterized using the Rutherford backscattering (RBS)/channeling technique and cross-sectional transmission electron microscopy (XTEM). The implanted samples were subsequently annealed at 1350 °C for 4 h in an Ar ambient. The annealing process results in creating a continuous SiO2 layer, 0.4 μm thick below a 1.6 μm thick top single crystal silicon overlayer. The buried SiO2 layer contains the well-known faceted Si inclusions. The density of dislocations within the top Si layer remains lower than the XTEM detection limit of 107/cm2. Between the Si overlayer and the buried SiO2 a layer of faceted longitudinal SiO2 precipitates is present. A localized dislocation network links the precipitates to the buried SiO2 layer.

Diamond synthesis from the vapor phase has been studied using hot filament assisted CVD, microwave plasma assisted CVD in an open system, and chemical transport process in a closed system using a gas mixture of hydrocarbon diluted with hydrogen gas. The deposited materials were identified as a cubic diamond with x-ray diffraction and Raman scattering measurement. The deposition process of diamond was considered on the basis of these experimental results and a review of the relevant field. The results suggest that the diamond synthesis proceeded by the deposition process, with the etching process operating simultaneously, and that atomic hydrogen played a very important role as the etching agent for non-diamond carbon. Also, the deposition process would be considered as the method that utilizes the bonding energy difference on each crystal surface of the diamond. The complicated problems on diamond synthesis originate from the fact that a third allotropic form exists in carbon, that is, the carbyne group.

Solid-state reactions between niobium and gallium arsenide in both thin film and bulk forms were studied in the temperature range 400 to 1000 °C using transmission electron microscopy (TEM), metallography, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Initially Nb4As3 and Nb5Ga3 formed at the interface and grew very slowly. Following an incubation period, NbAs and NbGa, nucleated and grew at rates several orders of magnitude faster than the initial phases. The resulting metastable diffusion path, Nb/NbGa3/NbAs/GaAs, was observed even after relatively long-term annealing and is believed to be kinetically stabilized. Formation of the other Nb–Ga binary compounds as predicted by the phase diagram was inhibited by nucleation and kinetic barriers. The observed reaction sequence is discussed considering the thermodynamics, kinetics, and possible growth mechanisms involved in the reaction.

Trace oxygen contamination of metal fluoride glasses degrades their performance in applications such as optical fibers or x-ray phosphors. Traditional methods for oxygen determination based on reaction with carbon to form carbon monoxide are slow and insensitive. We have used nuclear reaction analysis, in particular the 18O(p, α) reaction, to determine oxygen content in a variety of metal fluorides. Careful choice of the energy of the incident proton eliminates interference from fluorine. Standardless quantification of our measurements yields good agreement with the known oxygen content of mixtures of oxides and fluorides and with several (non-fluoride) NBS standards over four orders of magnitude. Measurement of 30 ppm oxygen has been demonstrated.

The solid-phase epitaxy of LiNbO3 following ion implantation of Ti dopant for the purpose of producing optical waveguides has been studied. Implanting 360-keV Ti at liquid nitrogen temperature produces a highly damaged region extending to a depth of about 400 nm. This essentially amorphous region can be recrystallized epitaxially by annealing in a water-saturated oxygen atmosphere at temperatures near 400 °C. though complete removal of all irradiation-induced damage requires temperatures in excess of 600 °C. The activation energy of the regrowth is 2.0 eV for implanted fluences below 3 ⊠ 1016 Ti/cm2. At higher fluences the regrowth proceeds more slowly, and Ti dopant segregates at the regrowth interface. Complete recrystallization following high-dose implantation requires annealing temperatures in excess of 800 °C.

The injection and storage characteristics of electrical charge in off-stoichiometric SiO2 films have been studied using two types of capacitor structures: (A) a simple capacitor formed with an off-stoichiometric SiO2 film deposited on either p- or n-type silicon substrate and a metallic (Al) contact, and (B) a structure similar to (A) but with a thin (100 Å or 500 Å) SiO2 layer between the Si substrate and the off-stoichiometric SiO2. The flat band voltage shifts measured from high frequency capacitance versus voltage curves of these devices were used to study the accumulation of charge in the off-stoichiometric SiO2 layer induced by applied voltage pulses. The width of these pulses was in the range of 10 ms to 100 μs and the amplitude was in the range of 0 to 80 volts. The role of the SiO2 layer in the (B) type structures is to inhibit or reduce charge injection to or from the Si substrate at low applied voltage amplitudes. This effect originates initial shifts of the flat band voltage of opposite polarity to those observed in the case of (A) type structures. The relaxation of the stored charges was monitored by measuring the shifts of the flat band voltage as a function of time when both electrical contacts were connected to ground potential.

Beta–SiC thin films have been epitaxially grown on 6H–SiC {0001} substrates via chemical vapor deposition (CVD). The growth rate increased linearly with the source/carrier gas flow rate ratio. The activation energy for the growth of β–SiC grown on the Si face of the 6H–SiC substrate was 12 Kcal/mole. These observations are consistent with a surface reaction-controlled process. The as-grown surface morphology is dependent on the terminal layer of the substrate, the growth temperature, and the source/carrier gas flow rate ratio. The C face of a 6H–SiC {0001} substrate caused a higher growth rate and thus poorer surface morphology than the Si face under the same growth conditions. The optimum temperature range for growth of a flat, mirror-like β–SiC surface was determined to be 1773–1823 K in the present CVD system. The microstructure and nucleation of double positioning boundaries were investigated via transmission and scanning electron microscopies. Triangular defects and their modifications were also observed, and their origins have been discussed.

Thallium (III) oxide is a degenerate n-type semiconductor with high optical transparency and electrical conductivity. Films of thallium(III) oxide can be electrochemically deposited onto conducting and p-type semiconducting substrates, and photoelectrochemically deposited onto n-type semiconducting substrates. Films deposited at currents below the mass transport limit onto platinum or stainless steel were columnar, and the current efficiency on stainless steel was 103 ±2%. Dendritic films were deposited at mass-transport-limited currents. Films were deposited with thicknesses ranging from 0.1 μm on n-silicon, to 170 μm on stainless steel. The photoelectrochemically deposited films were “direct-written” onto n-silicon, since the material was deposited only at irradiated portions of the electrode. Thin films were grown by irradiating the n-silicon with 450 nm monochromatic light, since the light was strongly absorbed by the thallium(III) oxide. The most uniform thin films were deposited when the n-silicon was initially irradiated with a short pulse of high intensity light. The pulse apparently promoted instantaneous nucleation of a high density of thallium(III) oxide nuclei.

C-cut sapphire was implanted with 400 keV Co+ ions to doses of 3 × 1017/cm2 and 5 × 1017/cm2 and then annealed in air sequentially at 1273, 1373, and 1473 K. Before and after the annealing, the implanted surfaces were examined by RBS and XRD methods. A nearly homogeneous layer of 350 nm thickness was formed on the surface when sapphire was implanted to a dose of 5 × 1017/cm2 and then annealed at 1473 K. For sapphire implanted to a dose of 3 × 1017/cm2 and then annealed at 1473 K, the implanted layer had a complex structure: the top surface layer of 70 nm thickness was α-alumina with Co3+ ions at the substitutional sites and the near-surface layer (70 nm–300 nm) was a mixed phase of CoAl2O4 and α-alumina.

Using the double pulse technique with two synchronized lasers, we studied the conditions of ignition and evolution of explosive crystallization. The structure of the resulting crystallized layers is analyzed by TEM. Results of calculations are reported describing the development of the two phase fronts: amorphous/molten and molten/crystalline. It is shown that the system takes more than 500 ns to reach the steady state. The experimental results support the model of creating first a melt nucleus in the amorphous layer followed by the formation of the crystalline nucleus in the molten sphere. Competitive solid phase nucleation and growth in the amorphous layer limit the temperature-time interval of melt nucleation. Defined explosively crystallized areas in laterally structured SOI layers are presented.

The thermodynamic activity of sodium oxide (Na2O) in the Nasicon solid solution series, Na1+xZr2SixO12, has been measured in the temperature range 700–1100 K using solid state galvanic cells: Pt|CO2 + O2|Na2CO3∥Na1+xZr2SixP3−xO12∥(Y2O3)ZrO2∥In + In2O3|Ta, Pt for 1 ≤ ⊠ ≤ 2.5, and Pt∥CO2 + O2∥Na2CO3∥β-alumina∥Na1+xZr2SixP3−xO12∥Ar + O2∥Pt for x = 0, 0.5, 2.5, and 3. The former cell, where the Nasicon solid solution is used as an electrolyte along with yttria-stabilized zirconia, is well suited for Nasicon compositions with high ionic conductivity. In the latter cell, β-alumina is used as an electrolyte and the Nasicon solid solution forms an electrode. The chemical potential of Na2O is found to increase monotonically with x at constant temperature. The partial entropy of Na2O decreases continuously with x. However, the partial enthalpy exhibits a maximum at x = 2. This suggests that the binding energy is minimum at the composition where ionic conductivity and cell volume have maximum values.

The influence of coherency strains on phase equilibria in a two-phase microstructure is examined for a binary or pseudobinary alloy system possessing a consolute critical point (chemical miscibility gap). The qualitative features of phase equilibria, including the limits of metastability (chemical spinodal), are shown to depend critically on the mechanical loading conditions and the geometric arrangement of the phases in the microstructure. If the elastic state of a phase in a two-phase coherent system is independent of the presence of the other phase, then the equilibrium characteristics usually associated with fluid systems should be observed, even though the system is nonhydrostatically stressed. If the elastic state of a phase depends upon the presence of the other phase, then the equilibrium characteristics that have come to be associated with coherent systems should be observed; tie lines and field lines do not coincide, the common tangent construction is invalid, and Gibbs phase rule is not applicable.

The effects of ArF excimer laser irradiation on β–SiC in UHV were examined for a variety of laser intensities and pulse densities. The samples were analyzed in situ with Auger and electron loss spectroscopies, and ex situ with x-ray photoelectron spectroscopy. With progressively higher laser intensities, the SiC surface was initially cleaned of carbon and oxygen surface contaminants, and the Si–LVV Auger lineshape changed from the oxide to the carbide. Still higher laser intensities then partially reordered the surface. A carbon surface layer developed, and the C-KLL lineshape transformed from carbidic to graphitic. Finally, the surface segregated into an almost pure Si layer and an underlying carbon-rich layer, followed by ablation and pitting. Bulk heating during laser exposure may enhance reordering of sputtered or implanted material.

Amorphous carbon films have been deposited on silicon 〈111〉 and quartz substrates by pulsed ruby laser vaporization from pyrolytic graphite. Depositions have been carried out at different substrate temperatures, and the properties of the deposited carbon films have been studied using IR and UV–VIS transmission, ellipsometry, and laser-Raman spectroscopies. Chemical and electrical resistivity measurements have also been performed. It is shown that the film properties depend critically on the substrate temperature and that at the substrate temperature of 50 °C films with substantial proportion of sp3 hybridized orbitals are obtained.