The lattice location of several transition metal (Hf, Ta) and rare-earth (Nd, Eu) impurities has been investigated in LiNbO3 by ion-beam channeling methods, including Rutherford backscattering and the 7Li(p, α)4 He nuclear reaction. From the detailed analysis of the angular scans near crystallographic axes and planes and the comparison between the two methods, it has been concluded that Hf lies at a Li site, but Ta at a Nb site, whereas Eu and Nd present double occupancy. By using additional results on other impurities, a wider picture of location behavior is described and possible physical mechanisms are discussed.

Si3N4 deposited by CVD on the surface of single crystal SiC was studied by SEM, x-ray diffraction, and TEM techniques. Characterization of the thick Si3N4 deposit was made by SEM and x-ray diffraction. The main emphasis, however, was on the analysis of the Si3N4/SiC interface and this analysis was carried out by electron diffraction studies in TEM. Both x-ray diffraction and TEM studies revealed that the CVD Si3N4 deposit has almost entirely the α-form except for occasional large β crystals. The structure of the SiC substrate in the interior was 6H but the surface structure close to the interface was always microtwinned β. Diffraction studies of the bulk Si3N4 deposit showed not only the presence of preferred growth directions but also different growth orientations near the substrate interface. TEM investigations at the interface also revealed that preferred growth orientations at the Si3N4/SiC interface are different from those in the bulk. The prominent orientation relationship at the interface is [0001]Si3N4//[101]SiC; Si3N4//SiC; a second one, namely Si3N4//[101]SiC; Si3N4//SiC relationship was also occasionally observed. Microindentation tests at the interface indicated that the Si3N4/SiC interface bonding is strong at ambient temperatures but weakens at high temperatures.

SiC whiskers were synthesized by the carbothermal reduction of silica with an addition of halide (3NaF · AlF3 or NaF) as an auxiliary bath. The whiskers were β phase (3C) and grew in the [111] direction. Three distinctive morphologies were observed: (1) Type A: thin and straight; (2) Type B: thick and bamboo-like; and (3) Type C: thick, straight, and smooth. Type A whiskers contained a high density of basal plane (111) stacking faults along their entire length, whereas Type B whiskers showed periodic changes between stacking faults and well-defined single crystals. Type C whiskers showed stacking faults on the other {111} planes instead of on the basal (111) plane. Silica formed molten fluorosilicate with halide and SiC grew via a vapor-solid reaction mechanism through gaseous SiO. These reactions can be expressed as (SiO2) + C (s) = SiO (g) + CO (g) and SiO (g) + 3CO (g) = SiC (s) + 2CO2 (g). The effects of processing parameters on the morphology and size of the whiskers were examined and the relationship between the morphological development of the whiskers and the stacking fault energy was determined.

The structural evolution of amorphous and microcrystalline SiC prepared from polycarbosilane was studied using various spectroscopic methods, 13C CPMAS NMR (cross-polarization, magic angle spinning nuclear magnetic resonance), ESR (electron spin resonance), FTIR (Fourier transformation infrared spectroscopy), and Raman. These studies indicate that the carbon-rich a-SiC has two major structural defects, C==C double bonds and C-dangling bonds. Both defect concentrations vary with firing conditions. The effect of hydrogen on the defect concentrations was also investigated by heat-treating the sample under hydrogen atmosphere. The mechanisms of the conversion process were discussed and the structural models for both amorphous and microcrystalline SiC were also proposed.

To determine the influence of volume constraint, the crystallization behavior of bulk anorthite glass was compared with that of anorthite glass situated at intergranular pockets in an alumina ceramic. Near-100% crystallization of the glass was obtained in both cases. Examination of the crystallized microstructures using SEM and TEM revealed several interesting features. The resulting microstructures, together with the very high degree of crystallization, are discussed with reference to a thermodynamic model for the constrained crystallization of glass.

A study of the effects of titanium ion implantation on the structural, mechanical, and tribological properties of single crystal and polycrystalline α-alumina has been carried out. Rutherford Backscattering Spectrometry (RBS) in channeling geometry shows that a great proportion of implanted titanium ions are substitutional at low fluence. This fraction falls to near zero as an amorphous layer is formed. The chemical states for implanted titanium are determined by X-ray Photoelectron Spectroscopy (XPS). Titanium is present in the Ti3+ state near the surface and as metallic Ti0 and as Ti3+ at depths corresponding to higher local concentration of titanium. The same behavior is observed for polycrystalline and single crystal α–alumina. Nanoindentation experiments show that low fluence implantation of titanium results in an increase of mechanical properties whereas high fluence implanted samples exhibit reduced hardness and Young's modulus compared to unimplanted samples. The friction coefficient is not changed by titanium ion implantation. Likewise, the wear characteristics were not changed by low fluence implantation, but amorphization at high fluence leads to a greater disk wear rate.

The chemical stability of the surface of metals, such as aluminum and stainless steel (SUS304), exposed to acid solutions is remarkably improved by the digital growth of Al2O3 using the sequential surface chemical reaction of trimethylaluminum (TMA) and water vapor. Samples thus coated with Al2O3 thin films were not etched by 1 N HCl or 1 N H2SO4 completely, and no change in the surface morphology was observed by these immersion tests. By the quantitative verification of polarization measurement in 1 N HCl and 1 N H2SO4, the polarization resistance was estimated to be 1.4 × 101–5.18 × 103 times that of noncoated samples. Anticorrosion coating of SUS304 pipe walls was also demonstrated.

The effects of heating rate on the sintering of BaTi5O11 ceramics from an alkoxide-derived powder were investigated, and the microwave properties were measured. Density and the crystalline phase of the sintered bodies varied with heating rate. Density increased with an increase in heating rate up to 30 °C/min and decreased at one exceeding 30 °C/min. BaTi5O11 ceramics with >99% theoretical density were obtained by sintering at 1120 °C for 48 h with a heating rate at 30 °C/min. The sintering with a heating rate at 100 °C/min resulted in a decomposition of BaTi5O11 to Ba2Ti9O20 and rutile that hindered sintering. The dielectric constant εr and Q volume, neither sensitive to microstructure or the crystalline phase, were 42 and ca. 6100 at 9.7 GHz, respectively. The temperature coefficient of resonant frequency τf was 39.3 ppm/°C at 7 GHz.

Ceramic dielectrics in the PbO–MgO–Nb2O5 based system, doped with several dopants such as Ti, Co, and Zn, were characterized for their microstructure and composition by transmission electron microscopy (TEM) and energy dispersive x-ray microanalysis (EDS). The ceramics exhibited a microstructure comprised of the matrix and many crystalline inclusions. The inclusions are compositionally enriched with magnesium and a smaller concentration of cobalt. Based on the selected area electron diffraction pattern (SADP) of the inclusion, the calculated interplanar spacings match those of (Mg, Co)O while those of the matrix match those of Pb(Mg0.33Nb0.67)O3. X-ray spectrometry (EDS) does not reveal a PbO phase in the matrix grain boundaries. The matrix exhibits finer features upon prolonged irradiation by the 200 keV electron beam. This does not affect the composition or interplanar spacings even though they exhibit polycrystalline diffraction patterns, and the high resolution micrographs show moiré patterns.

We previously reported bond strength measurements of metal/ceramic interfaces using shock waves to separate the bond by spallation. The technique relies on interpretation of the free surface velocity of a metal film as it is spalled from its substrate. A number of questions have been raised concerning the details of the interaction of the shock and interface. We provide answers by numerically modeling the experiments. We rederive the relationship between the maximum stress at the bond interface and the free surface velocity of the metal overlayer. We compare the analytical result with numerical calculations based on less restrictive assumptions, thereby supporting the analysis. We illustrate important design considerations of the experiment with numerical calculation and in the process, evaluate the effect of the artificial damping on the numerical results.

We have prepared a series of SnxSiO2)100−x granular metal films by RF magnetron sputtering with nominal Sn compositions from x = 30 to x = 90 at. %. X-ray diffraction and transmission electron microscopy measurements confirm that these films consist of small Sn particles, ranging from about 10 nm to 200 nm in mean diameter, embedded in an amorphous SiO2 matrix. These measurements also indicate that the mean Sn particle size decreases and the particle size distribution becomes more narrow as the Sn concentration is reduced. A differential scanning calorimeter has been used to study the size dependence of the melting temperature of the Sn particles. The melting temperature has been found to be increasingly depressed from the bulk value as the Sn particle size decreases. No evidence of an enhancement in the melting temperature at any particle size has been found. The evolution of the melting behavior of each sample with repeated melting and solidification cycles has also been studied.

The effect of starting materials purity, crucible material, and melting conditions on the optical scattering of AlF3-based glasses has been investigated. Platinum and vitreous carbon crucibles have been used to melt the glasses under nitrogen and reactive atmosphere (RAP) conditions. The optical quality of the bulk glass was evaluated by molecular light scattering in the Mie and Rayleigh regimes as a function of scattering angle and polarization at 0.647 μm. From an analysis of the angular scattering of both vertically and horizontally polarized beams, the sizes of the scattering sites have been estimated to be in the range of 0.02 to 2.0 μm. Glasses made with EM (BDH Limited) materials and melted in platinum crucibles without any reactive atmosphere exhibit lower values of scattering losses than those melted in the vitreous carbon crucibles under RAP.

To obtain quantitative details about the structure of binary tellurite glasses, the thermal properties have been measured. The thermal properties (linear thermal expansion coefficient α and transformation temperature Tg) of a set of tellurite glasses containing rare earth oxides in the form (TeO2)0.9 (AnOm)0.1 have been measured. The vitreous systems containing the rare earth cations are La, Ce, and Sm. The coefficient of thermal expansion in the range of 300–500 K and the transformation temperatures were determined to detect local structural changes that might be induced by the modifiers. The thermal properties α and Tg are discussed in terms of (i) structure, by calculating the volume of structure unit, the average crosslink density, and the average stretching force constant of each glass system; (ii) vibrations, by correlating the mean long wavelength acoustic mode Griineisen parameter γel and the expansion coefficient α.

X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were employed to investigate the effects of the ion beam implantation upon the chemical bonding and the final microstructure in the irradiated polyimide layer. XPS results show an increase of graphite cells with irradiation dose until a threshold is reached. A decomposing approach of data analysis for the experimental Raman spectra further discloses that the implantation parameters, i.e., dose, beam current density, and target temperature, play important but different roles in the formation of the final structure. By the current spectroscopic investigation, a deeper insight has been achieved into the origin of the enhanced conductivity, which shows the conductivity of modified layers are partly, even mainly, determined by their inner established order. This conclusion may serve as a guide in conductive polymer preparations.

Diamond, silicon carbide, gallium nitride, aluminum nitride, and boron nitride are currently under development for both electronic and optoelectronic semiconductor devices. Predictions based on their physical properties indicate that devices made from these materials should be far superior to currently available devices in high power, high frequency, and short wavelength applications. Yet actual device implementation requires that adequate materials processing technology exists. In this review, the current state of the art for producing semiconductor devices from these materials is evaluated, and recommendations for areas needing further research are outlined.