Epitaxial Nb thin films were grown via molecular beam epitaxy (MBE) at different substrate temperatures on α–Al2O3(0001) substrates. For temperatures of 900 °C to 1100 °C, it was found that Nb grows in the Volmer–Weber growth mode (formation of three-dimensional crystallites). Depending on the growth temperature, different epitaxial orientations of Nb films can be found. At a growth temperature of 900 °C, the Nb{111} planes are parallel to the sapphire basal plane whereas at 1100 °C the Nb grows with the {110} planes on the basal plane of sapphire. These orientations are present even in the initial stages of growth at both temperatures. The formation of two different epitaxial orientations of thick Nb films can be conclusively explained only by considering both the change in the total density of Nb islands with temperature and the influence of island size on the total energy of the islands. The Nb island growth process has been investigated in situ using reflection high energy electron diffraction (RHEED) and Auger electron spectroscopy (AES). Scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM) were employed to determine the morphology and structure of Nb islands, Nb films, and Nb/α–Al2O3 interfaces.

Nanocrystalline aluminum powders have been prepared by the gas phase condensation method. Samples have been synthesized in a conventional preparation chamber for gas phase condensation and also in the pretreatment chamber of an XPS (x-ray photoelectron spectroscopy) spectrometer so that in situ studies of the passivation process of nanocrystalline aluminum can be performed. For the range of particle sizes (12–41 nm) studied in the present work, we found a universal behavior during passivation with oxygen of the nanocrystalline Al0. An Al2O3 overlayer of 4 nm, which protects the material from further oxidation, was obtained for all samples independently of the route of oxygen dosage. A careful analysis of the photoelectron parameters (binding energy and Auger parameters) for Al and O shows that in the early stages of passivation the alumina overlayer is so thin (<2.5 nm thickness) that the Al2O3 –Al interface induces an increase in the relaxation energy of the photoholes as compared to that of bulk alumina. Conclusions have been drawn about the best way to proceed during passivation of Al ultrafine particles before exposure to an air atmosphere.

For very fine, acicular particles of α–Fe prepared for audio/video magnetic recording media, the relationship between their chemical property and surface flatness of the tape material made from the particles was investigated experimentally. It was found that adsorption capacity of acidic resin on the particle surface can be a very good index to predict the flatness of the magnetic tape. Because this index depends strongly on the acidic and basic properties of the particle surface, the tape performance can be well controlled by chemically designing the particle surface of α–Fe.

We have developed a new technique for the analysis of particulate contaminants in liquids (or gases) with an elemental detectability limit as low as 0.1 parts per trillion, and a particle concentration detectability limit as low as 1 particle/ml for particles greater than 0.2 μm in diameter. Samples are prepared using extraction replication and analyzed using analytical transmission electron microscopy. The methodology has been applied to the analysis of H2O2 and HF, important chemicals in integrated circuit fabrication. The new methodology should become an important tool in the identification of submicron-sized particles which adversely affect integrated circuit fabrication.

A method of forming TiN films for Si/Cu metallization by using plasma source ion implantation (PSII) of nitrogen into Ti is described. The PSII process utilizes a dose of 1 × 1017 ions/cm2 and peak voltages of –10, –15, and –20 kV. The properties of such TiN films as diffusion barriers between Cu and Si were investigated by annealing Cu(2000 A)/TiN/Ti/Si films in vacuum from 500 °C to 700 °C, and by analyzing with four-point probe sheet resistance measurements, Rutherford backscattering spectrometry (RBS), and Auger electron spectroscopy (AES). The TiN films made at peak voltages of –15 and –20 kV were stable barriers against Cu diffusion after annealing at temperatures higher than 600 °C.

A round robin test has been performed on sol-gel processing for the deposition of silica and silica-titania films on silicon substrates by spin-coating. Three solution preparation processes for silica coatings and three for silica-titania coatings were used to prepare samples at each of the participating laboratories. The films have been characterized mainly by thickness (profilometry and ellipsometry measurements), refractive index, porosity, and optical scattering. Different processes gave different thicknesses. Thickness differences were found in films prepared by the same process and by the same deposition parameters, but in different laboratories, when heat-treated at 500 °C. Variations were reduced in samples annealed at 1000 °C. Refractive index and porosity measurements suggest that variations were due to structural differences, particularly porosity. Furthermore, films heat-treated at 500 °C were not completely stabilized, and showed index and porosity variations after six months.

X-ray photoelectron spectroscopy has been used to examine the chemical states of fluorine in the glasses of composition xCaF2(50 – x)CaO · 50SiO2 (x = 5, 10, 15, 20, and 25 mol %) and xCaF2(50 – x/2)CaO(50 – x/2)SiO2 (x = 5, 10, 15, and 20 mol %). The analysis of the F1s spectra indicated that Ca2+ and F- ions introduced as CaF2 are favorably located among the Si–O skeleton forming Ca–F clusters. The fraction of the bridging and nonbridging oxygen atoms was derived from the O1s spectra, and the network of the fluorine-containing glasses was concluded to depend only on the ratio CaO/SiO2.

The uncertainties inherent to experimental differential scanning calorimetric data are evaluated. A new procedure is developed to perform the kinetic analysis of continuous heating calorimetric data when the heat capacity of the sample changes during the crystallization. The accuracy of isothermal calorimetric data is analyzed in terms of the peak-to-peak noise of the calorimetric signal and base line drift typical of differential scanning calorimetry equipment. Their influence in the evaluation of the kinetic parameter is discussed. An empirical construction of the time-temperature and temperature-heating rate transformation diagrams, grounded on the kinetic parameters, is presented. The method is applied to the kinetic study of the primary crystallization of Te in an amorphous alloy of nominal composition Ga20Te80, obtained by rapid solidification.

Mixed crystalline tin-titanium phosphates with variable tin-to-titanium molar ratio have been prepared by precipitation of soluble salts of the metal (IV) with phosphoric acid and refluxing the amorphous solids in 17 M H3PO4. The new materials are characterized by chemical textural and thermal analysis and x-ray powder diffraction. The tin-titanium phosphates are solid solutions showing an isomorphic substitution of tin by titanium in the α-tin phosphate lattice and tin substitution in the γ-titanium phosphate lattice. In both cases, the solubility is partial. The coexistence of both saturated phases is observed in samples of composition between the solubility limits.

Gel fibers have been prepared by extruding cellulose acetate spinning solution into transition metal (Ti, Zr, Hf, Nb, Ta) acetone solution as a coagulation bath. Gel formation must be due to the coordination of metal to OH and CO groups on the pyranose ring. The resultant gel fibers have been converted into carbide fibers by pyrolyzing them in Ar and N2 atmospheres at temperatures lower than for powder processing. This precursor gel can give a molecular scale mixture of metal and carbon sources.

The development of crystallographic texture in hot-forged polycrystalline Bi2Te3 samples was studied. Texture was evaluated with the use of the March–Dollase model in conjunction with a Rietveld analysis of x-ray diffraction data. It was determined that during forging a strong (0001) texture develops along the loading axis. The magnitude of the (0001) texture increases systematically with the amount of height reduction during hot-forging. The correlation between the observed deformation and the March–Dollase texture model suggests that grain rotation is the primary mechanism for texture development in Bi2Te3.

We have characterized heteroepitaxial diamond films on Pt(111) using the nondestructive technique of confocal Raman spectroscopy to investigate the variation in structure and strain with depth. The spectral depth profiles of heteroepitaxial diamond showed the diamond peak at 1332–1335 cm-1 and four bands centered at 1230 cm-1, 1470–1490 cm-1, 1530–1580 cm-1, and 1640 cm-1 near the surface. The diamond peak shifted to the single crystal peak position at 1332 cm-1 as the linewidth was broadened with free surface proximity. The compressive strain in the heteroepitaxial diamond crystal decreased and turned into the random strain. At the same time, the Raman band at 1470–1490 cm-1 grew in intensity. The constituents of non-diamond phase in the heteroepitaxial growth regions are different from those formed in the randomly oriented regions.

Microstructures of ulexite were investigated by CTEM and low electron dose HREM. It was found that the longitudinal grains in ulexite were oriented to c-direction to form a bundle structure. There were a number of small-angle grain boundaries and stacking faults inside a grain in the ulexite. Cleavage microcracks and stacking faults were mostly introduced on the {010} of the ulexite. The high-angle grain boundaries mainly consisted of high coincidence boundaries, which was confirmed by a comparison of observed contact angles and calculated degree of coincidence at the boundaries. The light transmittance properties of the ulexite would depend on the defects such as stacking fault, small-angle grain boundary, and high-angle grain boundary.

Based on the experimental observation that high pressure will considerably enhance the crystallization onset temperature of amorphous alloys, an attempt was made to consolidate the melt-spun amorphous ribbons into fully densed three-dimensional bulk amorphous materials under high pressures. An amorphous Ni69Cr7Fe2.5Si8B13.5 (at. %) alloy was used as a model material. Under a pressure of 1.5 GPa, the crystallization onset temperature was found to be increased by about 40 K, resulting in a widened supercooled liquid temperature region (about 68 K) beneath the onset of crystallization. The high pressure consolidation of the amorphous ribbons in this temperature region yielded bulk amorphous compacts with the same density of the melt-spun ribbons. This achievement was attributed to the significant homogeneous viscous flow of materials in the supercooled liquid state that could be maintained at higher temperatures during the high pressure compaction.