The use of sulfur-containing organic monolayer films improves adhesion between gold and silicon dioxide. The structures of these monolayers were analyzed using contact angle, ellipsometry, and XPS. The zone of adhesive failure was at or near the gold-monolayer interface.

It has recently been suggested that the rate of structural relaxations in amorphous chalcogenide glasses is inversely proportional to the viscosity and the latter obeys the Vogel-Tammann-Fulcher relationship. In this paper, Differential Scanning Calorimetry (DSC) and Thermomechanical Analysis (TMA) experiments examining the glass transformation in a–Se are reported which have been carried out over as wide range of heating rates as practically possible on the available instrumentation covering more than three decades of heating rate variation from r = 0.05 °C/min to r = 100 °C/min. The observed glass transformation temperatures in DSC and TMA ranged from 30 °C to 65 °C. The a–Se films were vapor deposited by thermal evaporation onto A1 substrates (at ∼70 °C) under identical conditions and well aged over an equal period of time so that all the films had an identical initial structure. Analysis of the glass transition temperature, Tg, vs heating rate, r, data obtained from the DSC endotherms shows that the structural relaxation rate is non-Arrhenius and can be described reasonably well by a Vogel expression of the form exp[–A/(T – T0)] which may have a weak structure dependent factor of the form exp[–c(H – HE)] where (H – HE) is the deviation of the structural enthalpy from its equilibrium value. It was found that a phenomenological single parameter Vogel description for the retardation time over the whole temperature range accessed leads to A and T0 values comparable with those obtained from the Vogel analysis of the viscosity-temperature data of Cukiermann and Uhlmann (1972), as well as the recent thermomicrohardness data of the present authors (1989). Furthermore, it is shown that the wide differences reported for the crystallization activation energy in a–Se can be readily interpreted by a viscosity limited crystallite growth rate. The Vogel interpretation is also found to be consistent with the temperature dependence of the mean dielectric relaxation time in the Debye loss observed by Abkowitz, Pochan, and Pochan (1980). It is suggested that in the elemental chalcogenide a–Se, the relaxation rate of enthalpy, microhardness, and dielectric polarization, as well as the crystallization rate, all scale inversely with the viscosity. TMA measurements, on the other hand, although still interpretable in terms of a Vogel behavior, did not indicate a softening behavior which paralleled the viscosity.

A simple expression for the Gibbs free energy of formation of a pure component or a eutectic alloy glass, relative to the stable crystalline phase (or phases) at the same temperature is deduced by use of thermodynamic arguments. The expression obtained is supposed to apply to both monocomponent and multicomponent liquid alloys that might become glasses from the supercooled liquid state, irrespective of the critical cooling rate needed to avoid crystallization.

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.

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.

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.

We prepared and characterized PbO–MgO–Nb2O5 ceramics near the Pb(Mg⅓Nb⅔)O3 stoichiometric composition. We examined microstructures, sintering behavior, and phase compositions in this system and prepared several new compositions, which have a single phase perovskite structure and a high dielectric constant (28000), by low sintering temperature (950–1020 °C). These compositions have a high electrical resistivity (1013 ohm-cm), which is about 1000 times higher than those of Pb(Fe½Nb½)O3 and Pb(Fe⅔W⅓)O3 based ceramics. The new compositions can be readily prepared into a single phase perovskite without a detectable amount of pyrochlore second phase by a simple method of mixing and calcining the constituent oxide and carbonate powders. Our dielectric measurements and XRD data establish the correlation between the decrease in dielectric constant and the presence of pyrochlore second phase. The effects of PbTiO3 dopant were quantitatively measured and our data showed that at a low (10 mole %) PbTiO3 concentration, the Curie temperature increases 6.6 °C for every mole % PbTiO3 dopant in the new compositions. The dielectric constant increases from 18000 in the undoped composition to 27 100 and 29000 by a PbTiO3 dopant concentration of 5% and 10%, respectively. The maximum dissipation factor also decreases from 0.10 in the undoped composition to 0.055 in the 10% PbTiO3 doped composition. The electrical resistivity, ρ, decreases with the PbTiO3 dopant concentration, t, following the ρ = ρ0 exp (–t/t0) relation where ρ0 ≍ (9.6 ± 0.2) × 1012 Ωcm and t0 ≃ 0.044.

We studied the effects of 15 dopants on the dielectric properties of the Pb1–x–yMgxNb2yO1+4y perovskite system. The investigated dopants are Ba, Ag, La, Bi, and Nd, which substitute in the Pb sublattice, and Co, Ni, Zn, Mn, Cr, Dy, Al, Fe, Zr, and Ti, which substitute in the sublattice occupied by Mg and Nb. While the dielectric constants of Pb1−x–yMgxNb2yO1+4y) are not affected by Al, Zr, and Ni dopants, their dielectric constants are increased by Ti dopant and decreased by other dopants. The rates of change in the Curie temperatures of Pb1–x–y MgxNb2yO1+4y with different dopant concentrations were quantitatively measured. The relative effectiveness of these dopants in altering the Curie temperature is correlated to the bond strengths between oxygen and the dopants in either the Pb sublattice or the Mg/Nb sublattice. The effects of these dopants on the dissipation factors and electrical resistivities were investigated. Cobalt and manganese oxides were identified as the most effective dopants in reducing the dissipation factor and lanthanum and barium oxides are effective in increasing the resistivity. We have also observed that zinc oxide promotes densification and reduces the temperature coefficient of capacitance in these compositions. Ternary and quaternary systems based on selected combinations of these dopants were prepared and characterized. Compositions in the Pb(Zn⅓Nb⅔)O3 + Pb(Co⅓Nb⅔O3 + PbTiO3 + Pb1–x–yMgxNb2yO1+4y quaternary systems were shown to be promising candidates for capacitor applications. Furthermore, multilayer capacitors of these promising compositions were fabricated and they were shown to have favorable device properties.

A new method of producing alumina powder is described. Aluminum basic acetate is first synthesized from alkoxide precursor. The chemical reactions which control the precipitation of this salt are followed, using IR spectroscopy. Alumina powder is obtained by further thermal decomposition, and the thermal evolution of the precipitate is studied.

The growth mechanism for small precipitates of Al2O3 formed by internal oxidation in the Nb–Al2O3 interface is studied in detail. The observations show that the Nb (001)/Al2O3 (00.1) interface is almost atomically flat and that there are no interface compounds. We suggest that the final layer on the Al2O3 side of this interface consists of oxygen atoms. The effects of image forces on misfit dislocations are found to result in a standoff distance between dislocation cores and the interface, in good agreement with the recent theory. The implications of this for the strength of metal-ceramic bonding are discussed.

The reactions of vacuum deposited thin films of lithium with various complex glasses have been explored using x-ray photoelectron spectroscopy (XPS). In contrast to lithium reactions with simple glasses such as silica or boron oxides, the reactions are predominantly those of the network modifiers such as sodium, potassium, and magnesium. XPS and x-ray induced Auger lineshapes indicate the migration of the network modifier to the near surface region followed by its reduction. In the case of magnesium, there is evidence for stable alloy formation with unreacted lithium following these migration and reduction steps.

The freeze-fracture technique has been developed to study solid-liquid dispersions. In this technique, a sample of dispersion is frozen, then fractured. A replica of the fracture surface is made and observed using a scanning electron microscope. The physical form of the solid thickener in dispersion can be studied, and the structure of the thickener can be revealed as well as a combination of rupture properties of the solid and the frozen liquid. The application of this technique is on lubricant greases. Greases are two-phase dispersed systems composed of mineral oil gelled with solid particles of soap. Three lithium 12-hydroxystearate greases are examined. Two different kinds of washing of the replica are used, the first eliminating the liquid phase. The configuration of soap particles and the network formed by them are observed, and artifacts such as twisting soap fibers are avoided. The second washing eliminates the solid and liquid phase. Examination of the fracture surface of the soap provides information on crystalline arrangement. The observed structures by freeze fracture are related to the thermal treatments during grease manufacture. The results are compared with the observations obtained from an electron transmission microscope analysis after preparation by the usual dispersion technique.

Epitaxial crystallization of polyphenylene sulfide (PPS) from 1-chloronaphthalene solution on NaCl (001) surface has been studied using electron microscopy and electron diffraction techniques. Three different epitaxial morphologies were observed: (1) conventional rodlike structures (fold plane epitaxy); (2) platelet structures (fold surface epitaxy); and (3) roselike structures whose growth mechanism and molecular packing are not completely understood at present. Of primary importance is the fact that a possible new crystal structure β-phase) of PPS was formed in the fold surface epitaxy through a true two-dimensional lattice matching by lateral lattice dimensional adjustment of PPS. Lattice match criterion again shows its merit in explaining the formation of fold surface epitaxy and the new crystal structure of PPS. Solution concentration, crystallization temperature, and time have significant influence on crystal growths, orientations, molecular packing, and morphological arrangements.

The investigation of dilute solution epitaxy of polyphenylene sulfide (PPS) has been carried out on a series of inorganic substrates, which cover a wide range of interatomic spacings, surface energies, and geometries. A variety of morphological arrangements of PPS on various substrates were observed. Both 〈100〉 and 〈110〉 epitaxial orientations were observed on monovalent alkali halides. While the 〈100〉 epitaxy is generally thought to grow upon nucleation on surface steps along the 〈100〉 direction, 〈110〉 epitaxy may also be nucleated on these surface steps. Changes in ionic lattice dimensions and ionic nature of the substrate have a substantial effect on the molecular packing of PPS and the resulting crystal orientations. Four new crystalline phases of PPS have resulted from the fold surface epitaxies on NaCl, KCl, KBr, and mica with favorable one- or two-dimensional lattice matching. This is a direct indication of the important role of lattice matching in inducing and defining the epitaxies and polymorphism of PPS.

Transparent silica gel–polymer composites have been prepared by the impregnation of porous gels with organic monomer and polymerization in situ. The relative amount of each phase was adjusted by varying the porosity of the silica gel prior to impregnation. These materials constitute a new class of transparent composites. Properties, such as density, refractive index, modulus of rupture, compressive strength, abrasion rate, and Vickers hardness, have been measured over the compositional range of 100% silica to 100% polymethyl methacrylate (PMMA).

The microstructures of carbon fibers prepared from coal tar mesophase pitch and heat-treated at 2500 °C were studied by transmission electron microscopy (TEM). The degree of preferred orientation of the carbon fibers along the fiber axis was not significantly changed: by spinning, while stirring the pitch above the capillary; by changing the viscosity of the pitch in spinning from 60 poise to 250 poise, keeping the diameter of the pitch precursor fiber about 11.5 μm, which is that of the as-spun fiber; and by controlling the diameter of the pitch fiber from 8 μm to 18 μm, keeping the viscosity of the pitch at about 250 poise. Such a weak dependency of the degree of preferred orientation of the carbon fibers on the spinning conditions is qualitatively consistent with the relationships between the degree of preferred orientation of a pitch precursor fiber and the spinning conditions. The graphite layers of the carbon fibers heat-treated at 2500 °C showed shrinkage in the transverse fiber cross section. The degree of shrinkage was significantly increased by stirring the pitch above the capillary while spinning, and the shrinkage also increased when the viscosity of the pitch was increased for spinning, and when the diameter of the fibers was decreased. Roughly speaking, the degree of shrinkage was proportional to the mean size of the mesophase domains in the transverse section of pitch precursor fibers.

The cells in living bone are embedded in a charged, organic-inorganic solid permeated by ionic fluids flowing through a complex network of channels (diameter ∼10−1–102 μm). The solid matrix, which has a high degree of composite material organization beginning at the macromolecular level, has even finer pores of diameter ≳10−3 μm containing extracellular fluids. Since bone cells are thus bathed in fluid environments of varying ionic composition and concentration, it is likely that the physiology of bone depends on its electrical and electromechanical properties. This hypothesis is supported by the known effects of externally applied mechanical and electrical signals on physiological functions. Contrary to the earlier perception of bone as an insulating material, it is now recognized that the fluid content of bone endows it with physiologically significant conductivity. Mechanoelectric transduction in bone, at low frequencies, is most likely an electrokinetic process associated with the solid-fluid interfaces in bone. Electromechanical properties of bone have been determined experimentally by measurements of stress-generated potentials and streaming potentials in wet bone specimens and electrophoretic mobility of bone particles. Interpretation of results has been difficult due to the complexity of the solid-fluid interfaces in bone and the often undefinable alterations of the pores and interfaces due to specimen preparation. This paper is a review of the present state of knowledge of mechanoelectric transduction in bone and its physiological significance.