The growth of ferroelectric lead zirconate titanate (PZT) films by rf-sputtering using a facing targets geometry is described. This study focuses on the influence of the substrate on PZT thin film composition, structure, and electrical properties. The deposition temperatures ranged from room temperature to 700 °C and the process gas was a mixture of argon and oxygen. Effects of deposition conditions and post-deposition annealing on film composition, microstructure, and properties were evaluated using Rutherford backscattering spectroscopy (RBS), x-ray diffraction, electron microscopy, and measurements of the permittivity and polarization. The microstructure, composition, and permittivity of the films were found to be strongly dependent on the substrate temperature and on the preparation history of the films.

Tungsten-containing amorphous hydrogenated carbon (W–C:H) films were prepared on silicon substrates by reactive rf sputtering (13.56 MHz). Elastic recoil detection (ERD) and Rutherford backscattering (RBS) of MeV He+ ions have been performed to determine the hydrogen concentration and mass density of the films, respectively. The mechanical properties, i.e., the microhardness, Young's modulus, and the adhesion on substrates, have been studied by depth-sensing indentation equipment (nanoindenter) and a scratch tester with an acoustic emission (AE) detector, respectively. The electric conductivity of the films was also measured. The results show that these properties depend mainly on the tungsten concentration. X-ray diffraction suggests that the W–C:H films consist of an a–C: H polymeric matrix with WC1−x(β) particles embedded. With increasing tungsten concentration the films change from polymeric a–C:H dominant to crystalline WC1−x(β) dominant W–C:H, resulting in different film properties.

The compatibility of phases in the Ti–Si–C system was studied for pressures from 10 to 20 kbars (1 to 2 GPa) and temperatures from 1200 °C to 1500 °C via an interfacial reaction between titanium and silicon carbide. The interface was characterized by backscattered electron imaging and electron probe microanalysis. Ti3Si was stabilized at high pressures exhibiting an appreciable solubility for carbon (up to 9 at. %). At higher temperatures and lower pressures, it decomposed to Ti5Si3, Ti(Si, C), and TiCx according to the relation Ti3Si (Cz) = (0.70588)TiCx + (0.32437)Ti5Si3 + (0.67227)Ti (Si, C), where the mathematical coefficients were calculated using z = 0.4 and x = 0.5. No detectable quantities of carbon dissolved in Ti5Si3 under these conditions. A clapeyron slope of 0.08 (±0.01) kbar/K was measured for this reaction. The microstructure of the reaction zone and other general thermodynamic and kinetic characteristics are discussed for different experimental conditions.

Diffusion bonds of Ni/ZrO2 and Ni/NiO/ZrO2 fabricated in vacuum have been investigated using flexural 4-point bending tests and optical and electron microscopy. It is found that subsequent annealing in air after bonding improves bond strength, and annealing in vacuum reduces strength. This is attributed to the formation of a thin oxide layer during annealing in air which enhances adhesion to the ceramic, whereas annealing in vacuum creates debonding voids at the specimen edges. The transformation of NiO in vacuum to Ni explains why the strength of bonds using preoxidized Ni foil does not show any increase, as it is essentially still the diffusion bonding of Ni to ZrO2 in the configuration of Ni/NiO/Ni/ZrO2. The presence of extensive void necklaces on grain boundaries in the metal where they intersect the bonding interface shows the importance of the metal grain boundaries acting as vacancy sinks during diffusion bonding.

Ultrafine particles (UFPs) of aluminum oxide were prepared by an arc discharge, sintered in a custom-built ultrahigh vacuum (UHV) furnace system, and characterized in a high resolution electron microscope (HREM) operating under UHV conditions. The UFPs produced range in size from 20 to 50 nm and have highly faceted surfaces. The atomic structure of the UFPs corresponds to the cubic (γ) and orthorhombic (δ) variants of the spinel structure. Sintering in these UFPs demonstrates three major issues. Surface faceting plays a major role in determining the final sintering geometry with sintering occurring predominantly on the close-packed {111} facets. Surface diffusion is the predominant mechanism for sintering, as evidenced by the fact that many sintered particles have their initial adhesion structure ‘locked-in’ during sintering with no reorientation occurring. Furthermore, the necks formed during sintering have well-defined, atomically sharp contact angles which suggests that the neck growth process is controlled by the faceted structures and may be modeled by a mechanism similar to crystal growth due to ledges, grain boundaries, and twins. The driving force for sintering can be considered as a chemical potential difference between facet surfaces and the neck region.

Shock consolidation experiments were conducted via flyer impact on synthetic diamond (6–12 μm) and cubic boron nitride (c-BN) (4–8 μm) admixed with SiC whisker (SCW), Si3N4 whisker (SNW), SiC powder, and Si powder contained in stainless steel capsules under the shock pressure range of 10–30 GPa. Scanning electron microscopy and transmission electron microscopy imaging of the samples revealed no plastic deformation or melting of diamond and virtually no deformation of c-BN, whereas the SCW and SNW were extensively melted and recrystallized into bundle-shaped crystallites. In contrast, SiC powder mixed with diamond was also melted but demonstrated equant grain growth. A new method to calculate the shock temperature and melt fraction is formulated on the basis of Milewski's sphere-rod packing data. The new method assigns excess bulk volume to the zone around whiskers and yields a better description of the energy deposition mechanism of the consolidation of powder-whisker systems. Some of the experiments employed Sawaoka's post-shock annealing technique, in which the sample is sandwiched between two layers of a mixture of titanium powder plus carbon. Very well consolidated samples were obtained with post-shock heating under shock pressures of only about 11 GPa. Micro-Vickers hardness values up to 27 GPa were obtained for c-BN plus SCW at a low impact velocity of 1.45 km/s with post-shock heating. This hardness is similar to that obtained at a higher impact velocity of 1.95 km/s without post-shock heating. To understand the post-shock heating process, one-dimensional time dependent temperature profile calculations were conducted for the sample and Ti + C layers. Post-shock heating appears to be very important in the consolidation of powder and whisker admixture. The calculated optimum Ti + C thickness is about 0.8–1.7 mm at a porosity of 40% for a typical sample thickness of 2 mm. The heating and cooling time is a few milliseconds. Good compacts with micro-Vickers hardness values up to 28 GPa were also obtained upon shock consolidation of diamond plus Si admixtures.

The versatility of mechanochemical processing was investigated in a number of nonmetallic inorganic systems. It is shown that high energy grinding can be used to produce amorphous carbon from synthetic graphite and some forms of natural graphite. Elemental sulfur can likewise be amorphized by prolonged high energy grinding. Phase transformations of αFe2O3 (hematite) and mechanochemical reactions of this phase with ZnO and NiO are strongly influenced by the presence of iron resulting from wear of the grinding media. Thus spinel type ferrites were obtained by grinding of such mixtures for short times (1–3 h in a Spex mill); however, longer grinding times resulted in the formation of FeO or (Fe,Zn)O (when grinding ZnO) or FeO or (Fe, Ni)O (when grinding NiO), presumably as a result of the reaction of mill wear debris with the mill charge. The suspected (Fe, Zn)O phase is most likely a nonequilibrium solid solution. Negligible were accompanied the mechanochemical synthesis of NiS and ZnS from elemental powders. These sulfides were formed for short milling times. In contrast, sulfides of tungsten were not formed even when rather long milling times were employed. The survey of mechanochemical reactions presented here further reinforces the concept that this low temperature synthesis method is a robust process route for production of a wide range of materials.

Sulfur has been purified by a dynamic pyrolysis procedure that takes into account the unique viscosity-temperature relationship of the liquid. An apparatus is described that incorporates gas-bubbling and rocking to overcome diffusion-limited kinetics. For the first time, a mechanism is proposed for the pyrolytic purification of sulfur based upon Carsul formation and the H2S ↔ H2Sx equilibrium. Infrared methods are delineated for qualitative analysis and quantitative estimates of anion contaminants, including the omnipresent hydrocarbon impurities. Our purified sulfur has a total carbon, oxygen, and hydrogen impurity level of <10 μg/g.

A glass based on ZrF4 was synthesized by a combination of sol-gel and reactive atmosphere processing. Infrared spectroscopy and combustion analysis show that the fluorination process reduces the concentration of organic and hydroxide impurities. Chemical changes have occurred during fluorination; this is indicated by different x-ray diffraction traces and crystallization characteristics for the fluorinated sample compared to the oxide gel product. Chemical analysis from x-ray fluorescence indicates that the fluorinated gel is chemically similar to a melted glass of the same composition. Differential scanning calorimetry gives a glass transition temperature of 290 °C and a crystallization temperature of 390 °C. These values are consistent with those expected for a fluoride glass prepared by conventional methods.

A new family of modified ZBLAN glass compositions has been synthesized which provides better stability against crystallization. A preliminary study of the Hruby factor HR shows higher values as compared to a ZBLAN glass prepared under the same conditions, utilizing similar high purity starting materials. Large rods of clear glass with a 1.5 cm diameter and up to 17 cm in length were easily obtained. Results will be presented on the physical properties and crystallization behavior of these high stability glasses.

The microstructure and microchemistry of ceramic/polymer interfaces in a calcium aluminate/polyvinyl alcohol composite material have been studied using transmission electron microscopy (TEM), high resolution electron microscopy (HREM), x-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopy (EDS). Interfaces consisted of an amorphous interphase layer, inside of which were dispersed metastably retained CaAl2O5 · 8H2O crystallites. The amorphous phase was a mixture of the hydration products of calcium aluminate and aluminum–crosslinked, polyvinyl alcohol. The crystalline hydration product CaAl2O5 · 8H2O was metastably retained due to polymer poisoning of nucleation sites and significant reduction of conversion kinetics.

Since its first application to thin films in the 1950's the bulge test has become a standard technique for measuring thin film mechanical properties. While the apparatus required for the test is simple, interpretation of the data is not. Failure to recognize this fact has led to inconsistencies in the reported values of properties obtained using the bulge test. For this reason we have used the finite element method to model the deformation behavior of a thin film in a bulge test for a variety of initial conditions and material properties. In this paper we will review several of the existing models for describing the deformation behavior of a circular thin film in a bulge test, and then analyze these models in light of the finite element results. The product of this work is a set of equations and procedures for analyzing bulge test data that will improve the accuracy and reliability of this technique.

The indentation load-displacement behavior of six materials tested with a Berkovich indenter has been carefully documented to establish an improved method for determining hardness and elastic modulus from indentation load-displacement data. The materials included fused silica, soda–lime glass, and single crystals of aluminum, tungsten, quartz, and sapphire. It is shown that the load–displacement curves during unloading in these materials are not linear, even in the initial stages, thereby suggesting that the flat punch approximation used so often in the analysis of unloading data is not entirely adequate. An analysis technique is presented that accounts for the curvature in the unloading data and provides a physically justifiable procedure for determining the depth which should be used in conjunction with the indenter shape function to establish the contact area at peak load. The hardnesses and elastic moduli of the six materials are computed using the analysis procedure and compared with values determined by independent means to assess the accuracy of the method. The results show that with good technique, moduli can be measured to within 5%.

Experiments on thin mica sheets are used to demonstrate that coplanar cracks in double-cantilever beam specimens do not universally attract each other, as conventionally portrayed, but, at long range, actually repel. An elasticity analysis explains the repulsion in terms of a compression zone, ≍0.35 times the beam half-thickness ahead of the crack tip, generated by bending moments from the cantilever arms on the remaining specimen section.