The present investigation is the first comprehensive comparative study of x-ray diffraction (XRD) and transmission electron microscopy (TEM) results to address the important issue of fcc Ti formation in nanoscale multilayers. Ti/Al multilayers with 7.2 and 5.2 nm composition modulation wavelengths were studied by reflection and transmission XRD as well as transmission electron diffraction (ED), high-resolution TEM, and energy-filtered TEM. Previous reports have claimed deposition of fcc Ti in multilayer systems. Our results demonstrate that the Ti in Ti/Al multilayers deposits in the hcp form and that fcc Ti is merely an artifact of producing specimens for cross-sectional TEM.

Polycrystalline TiN/VN, NbN/VN, and TiN/NbN superlattices with periods Λ between 2 and 160 nm were deposited onto steel substrates using an opposed-cathode reactive magnetron sputtering system. The nitrogen partial pressure and the substrate bias values were optimized in order to obtain dense stoichiometric films, which yielded the highest Vickers hardnesses HV. HV for TiN/VN and TiN/NbN superlattices reached maximum values of ≈5000 kgf/mm2 at Λ ≈ 5–10 nm, compared with ≈2000 kgf/mm2 for homogeneous TiN, NbN, and VN films. In contrast, HV ≈ 2000 kgf/mm2 was obtained for VN/NbN superlattices independent of Λ. Model calculations in which the hardness enhancement was proportional to the difference in layer shear moduli gave good agreement with the data. The lack of hardness enhancement in VN/NbN indicates that any other hardening mechanisms, such as coherency strains and dislocation blocking by interfacial misfit dislocations, were not important.

Bi12TiO20 (BTO); Bi12GaxBi1−xO19.5 (BGaO); and Bi12(M1/3P2/3)O20, M = Cd, Zn, and Ni (BMPO) thin films were prepared by pulsed laser deposition using a KrF excimer laser on (100)Y-stabilized zirconia (YSZ), (100)Bi12GeO20 (BGO), and (110)Bi12SiO20 (BSO) crystalline substrates. All these films have a sillenite structure. On (100)YSZ the sillenite is oriented as {310} with the 〈130〉 direction parallel to the 〈021〉YSZ directions (〈130〉{310}BTO〈021〉{100}YSZ). On (100)BGO and (110)BSO the sillenite film reproduces the substrate orientation, and the films formed are able to channel He+ particles. The optimum deposition temperatures for BTO and BGaO are 600 and 550 °C, respectively. Higher temperatures must be avoided to minimize the nucleation of Bi-deficient phases due to the diffusion of Bi into the YSZ substrates. BMPO films are polycrystalline. The lattice parameters of these films were determined. The crystalline films support guided optical modes. The refractive indices obtained for the films are close to those measured in bulk crystals, being slightly larger for films deposited on isomorphous sillenite substrates. The crystalline films deposited on YSZ are photoconductors when excited in the green and blue spectral regions.

A detailed study of the second-order Raman spectrum of the polymer polyparaphenylene (PPP) prepared according to the Kovacic method and heat treated at temperatures THT between 650 and 750 °C is presented. The Raman experiments have been performed with five different laser excitation energies in the visible range between 1.92 and 3.05 eV. Several Raman bands in the region between 2400 and 3400 cm−1 have been detected and assigned to the overtones and combination bands of the two conformations of the PPP polymer (benzenoid and quinoid) that co-exist in our samples. Due to the carbonization process, these bands broaden and decrease in intensity with increasing heat treatment temperature, as is also observed for the corresponding first-order Raman features. The complete absence of these high-frequency Raman bands for PPP with heat treatment temperatures in excess of 750 °C indicates complete transformation of the polymer into a disordered carbon material.

Hydrogen interaction with solid iridium complexes IrXH2(PPr i3)2 (X = Cl, I) was investigated. Gaseous hydrogen was found to react reversibly with solid chloro-iridium complex IrClH2(PPri3)2, forming IrClH2(PPri3)2H2 The relative partial molal enthalpy and entropy were obtained from equilibrium isotherms at different hydrogen concentrations. The decrease in entropy with increasing hydrogen concentration and the absence of plateaus in the equilibrium isotherms were consistent with a single phase solid solution with two chemical components. Hydrogen release from solid iodo-iridium complex IrIH2(PPri3)2H2 was not observed at temperatures up to 350 K, indicating stronger hydrogen bonding.

The influence of uniaxial compressive stress, T3, applied parallel to the electrical field, on the electromechanical parameters of 0.9Pb(Mg1/3Nb2/3)O3−0.1PbTiO3 ceramics in the dc electrical field-biased state and at temperatures near the dielectric constant maximum Tm was investigated. It was found that T3 reduces both the dielectric constant and polarization level, which results in a reduction of the piezoelectric coefficient with stress. However, the compliance of the material does not show much change with stress. As a consequence, the coupling factor k33 is also reduced with stress. On the other hand, the existence of the local micropolar region in the material causes anomalous changes in the aforementioned properties when the material is subjected to a high electric field, which induces a macropolar state. The transformation of this macropolar state back to a micropolar state under stress involves a large volume strain and results in an enhancement of the hydrostatic piezoelectric response.

Ferroelectric properties of SrBi2TaNbO9 (SBTN) thin films were changed by the amount of Bi content in SBTN. We proposed that the addition of excess Bi to the SBTN thin films could be accomplished by heat treating the SBTN/Bi2O3/SBTN heterostructure fabricated by the radio frequency magnetron sputtering method. The Bi composition was controlled by changing the thickness of the inserted Bi2O3 from 50 to 400Å in the SBTN/Bi2O3/SBTN heterostructure. As the thickness of Bi2O3 films was increased from 0 to 100 Å, the grain grew faster and the ferroelectric properties improved. On the other hand, when the thickness, of Bi2O3 films was thicker than 150 Å, the ferroelectric properties deteriorated. In particular, when a 400 Å Bi2O3 layer was inserted between SBTN films, a Bi2Pt phase appeared and the Bi2O3 films remained between SBTN films, resulting in poor ferroelectric properties. A Bi2Pt phase was formed by the reaction between the platinum bottom electrode and Bi2O3 films. On the other hand, the leakage current density of SBTN thin films decreased with the increase of inserted Bi2O3 film thickness. As the thickness of inserted Bi2O3 films was increased from 0 to 50 Å, leakage current density abruptly decreased because Bi content of the SBTN thin films was increased from 8 mol% deficient to stoichiometric composition. As the thickness of inserted Bi2O3 films increased from 100 to 400 Å, leakage current density gradually decreased because the remaining Bi2O3 layer in SBTN thin films increased.

The solvent-induced stresses in glassy polymers were investigated. The mass transport accounts for case I, case II, and anomalous transport. Case I transport is attributed to the concentration gradient, whereas case II transport is attributed to stress relaxation. Anomalous transport is the mixture of case I and case II. Both one-side and two-side mass transports with the boundary condition of constant surface concentration are considered. The stresses and longitudinal displacement arising from the mass transport are formulated based on the linear elasticity theory. The maximum stress is always located at the surface at the initial time. The stresses are a function of the partial molal volume, Young's modulus, and Poisson's ratio. From the longitudinal displacement data, the partial molal volume was determined.

Dense and smooth BaTiO3 thin films were prepared on SrTiO3 (100) substrates by the dipping-pyrolysis process using a mixed precursor solution of barium and titanium naphthenates. Combination effects of prefiring [at 150–450 °C in air or low oxygen partial pressure, p(O2)[ and final heat treatment [at 850 °C in air or low p(O2)[ on preparation of BaTiO3 thin films were examined. An epitaxial BaTiO3 thin film with a dense and smooth surface consisting of nanosized grains about 70 nm was prepared by prefiring under low p(O2) at 250 °C and final heat treatment under low p (O2) at 850 °C.

The film that forms spontaneously when boron oxide (B2O3) is exposed to humid air is a solid lubricant. This film is usually assumed to be boric acid (H3BO3), the stable bulk phase. We describe the nanometer-scale surface morphology, mechanical properties, and tribological properties of these films and compare them with crystals precipitated from saturated solutions of boric acid. Scanning force microscopy (SFM) and low-load indentation were the primary experimental tools. Mechanical properties and their variation with depth are reported. In all cases, the surfaces were covered with a layer that has different mechanical properties than the underlying bulk. The films formed on boron oxide showed no evidence of crystalline structure. A thin surface layer was rapidly removed, followed by slower wear of the underlying film. The thickness of this initial layer was sensitive to sample preparation conditions, including humidity. Friction on the worn surface was lower than on the as-formed surface in all cases. In contrast, the SFM tip was unable to cause any wear to the surface film on the precipitated crystals. Indentation pop-in features were common for precipitated crystals but did not occur on the films formed on boron oxide. The surface structures were more complex than assumed in models put forth previously to explain the mechanism of lubricity in the boron oxide–boric acid–water system.

Plastic deformation behavior of impure nanocrystalline ceramics (NCC) was modeled using the percolative composite model in conjunction with models for plastic deformation by grain boundary sliding. The “glass transition temperature” concept was used to determine the threshold strain rate criterion below which the impure nanocrystalline ceramic would deform plastically. Threshold strain rate is stress independent. It increases with the temperature increase and with the grain size decrease. Using the dissolution-precipitation model, dependence of the strain rate on temperature, stress, and grain size in the nanometer regime for impure NCCs was calculated. As an example, the critical conditions for plasticity in impure yttria-tetragonal zirconia polycrystals (Y-TZP) were evaluated. At 600 °C, strain rates as high as 10−4 s−1 were expected in 10 nm impure Y-TZP. Comparison of the published data extrapolated into the nanometer range to the calculated threshold level showed that increase in the applied stress is associated with increase in the grain size and strain rate onsets for plastic deformation.

Single-phase nanocrystalline Co9S8 was prepared by hydrothermal treatment of Co(Ac)2 and NH2CSNH2 in hydrazine solution at 170 °C. The products were characterized by x-ray powder diffraction (XRD) technique, transmission electron microscope (TEM), and wet chemical analysis. XRD indicated the product was the cubic Co9S8 phase. The relative crystallite size was 6.3 nm as determined by the Scherrer method. TEM images showed the particles were agglomerative. The electron diffraction pattern also revealed their nanocrystalline nature. In this hydrothermal formation process of Co9S8, hydrazine was a critical factor. The formation process is discussed.

A negative temperature coefficient–positive temperature coefficient (NTC-PTC) composite thermistor with high performance was designed by glass/ceramic composing. The material exhibited low resistivity and a large negative temperature coefficient of resistivity. The minimum resistivity was the magnitude of 102 Ω cm, and the negative temperature coefficient of resistivity was better than −3% °C−1. The results showed that the large negative temperature coefficient of resistivity was closely related to the glass phase, and the NTC-PTC functional composite material was a kind of grain-boundary–controlled material.

Doped ceria, which has a higher oxygen ion conductivity than yttria-stabilized zirconia, is one of the possible electrolytes for solid oxide fuel cell at low temperatures. This study concerns powder preparation and densification of rare-earth-doped ceria. Rare-earth-doped ceria powders with a composition of Ce0.8R0.2O1.9 (R = Yb, Y, Gd, Sm, Nd, and La) were prepared by heating the oxalate coprecipitate when a mixed rare earth/cerium nitrate solution was added to an oxalic solution. The oxalate and derived-oxide powders were characterized by x-ray diffraction (XRD), thermogravimetry differential thermal analysis (TG-DTA), particle size analyzer with laser diffraction, inductively coupled plasma (ICP), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). This method provided the oxalate solid solutions containing Ce and R, which were calcined to form the oxide solid solutions at 600 °C in air. The lattice parameter of oxide powders increased linearly with increasing ionic radius of doped rare earth. The size of platelike particles of oxalates and oxides depended on the concentration of oxalic acid and showed a minimum at 0.4 M oxalic acid. Dry milling of oxide powder with α–Al2O3 ball was effective in reducing the size and aspect ratios of particles with little contamination of Al2O3. These rare-earth-doped ceria powders with various sizes were formed by uniaxial pressing (49 MPa) followed by cold isostatic pressing (294 MPa), and sintered at 900–1600 °C in air for 4 h. The micrometer-sized-doped CeO2 powders were densified above 95% of the theoretical density at 1200 °C. The grain size of rare-earth-doped ceria after sintering at 1600 °C was larger in the samples with the larger rare-earth element.

We discuss substrate temperature ramping effects during chemical vapor deposition of aluminum on nucleation density, texture, surface roughness, and resistivity of the resulting films. Results from three different process protocols are presented. Ramping the temperature down during the deposition from 673 K resulted in a larger fraction of small nuclei compared to deposition at a constant temperature of 573 K. From among the protocols studied, the lowest surface roughness was obtained by initially depositing for a short time while ramping the temperature down from 673 K, followed by deposition at 573 K, compared to all the other films. The same process protocol resulted in the highest Al(111) texturing, highest reflectivity, and lowest resistivity.

The effects of reaction temperature (150–300 °C), chemical composition of the starting cerium salt (cerium nitrate and cerium chloride), and doping with trivalent cations (Sc3+ and Y3+) on the coarsening of CeO2 particles in dilute suspensions under hydrothermal conditions were investigated. The particle size was measured by x-ray line broadening and by transmission electron microscopy. The particle coarsening kinetics followed a parabolic law, indicating that the interfacial reaction (dissolution) was the rate-controlling step. Furthermore, the particle size distribution data can be well-described by the Lifshitz–Slyozov–Wagner theory of Ostwald ripening controlled by the interfacial reaction. Doping with 6 at.% Y3+ produced a significant reduction in the coarsening rate but almost no change in the activation energy. At the same concentration, Sc3+ was more effective than Y3+ in reducing the coarsening rate. Particles synthesized from a starting solution of cerium(III) chloride coarsened at a markedly slower rate than that for particles synthesized from cerium(III) nitrate. The mechanisms controlling the coarsening of the particles are discussed.

New segmented polyurethanes containing phospholipid moieties in the main chains and long-chain alkyl groups in the side chains were synthesized. The soft segments used in this study were poly(butadiene), poly(isoprene), hydrogenated poly(isoprene), and poly(1,6-hexyl-1,2-ethylcarbonate) diol. The hard segments of these polyurethanes were 4,4′-methylenediphenyl diisocyanate, bis[2-(2-hydroxyethyldimethylammonio)ethyl]2-cetyl- 1,3-propanediphosphate, and 1,4-butanediol. The blood compatibilities of the new polymers were evaluated by platelet-rich plasma contact studies and viewed by scanning electron microscopy using medical grade BioSpan® and nonphospholipid polyurethane as references. These new materials have good surfaces in terms of platelet adhesion, and the morphology of adhered platelets undergoes a relatively low degree of variation.

Laser-induced-surface-flaw experiments on fused silica at 351 nm and 500 ps pulse duration are reported here. Specimens with surface flaws produced at a measured exit-surface damage threshold fluence of Fexit/th = 10 J/cm2 were irradiated at a constant fluence of FL = 1.8 × Fexit/th by different numbers of laser pulses, N = 110 to 520. Micrograph observations show that (i) the produced cracks have a semielliptical shape and (ii) the material strength predictions based on the radial crack depth (normal to the surface) instead of the crack surface length (parallel to the surface) are in good agreement with measured strengths obtained using a four-point bending fixture. The underlying basis of conventional crack analysis is first examined critically and is argued to be deficient in the way the failure strength for the cracks is related to the characteristic parameters of crack geometry. In general, it is necessary to incorporate a residual term into the failure strength formulation. The crack depth and the failure strength are found to increase and decrease with the number of laser pulses, respectively.

Substrate effects on the measurement of thin film mechanical properties by nanoindentation methods have been studied experimentally using a model soft film on hard substrate system: aluminum on glass. The hardness and elastic modulus of aluminum films with thicknesses of 240, 650, and 1700 nm sputter-deposited on glass were systematically characterized as a function of indenter penetration depth using standard nanoindentation methods. Scanning electron and atomic force microscopy of the hardness impressions revealed that indentation pileup in the aluminum is significantly enhanced by the substrate. The substrate also affects the form of the unloading curve in a manner that has important implications for nanoindentation data analysis procedures. Because of these effects, nanoindentation measurement techniques overestimate the film hardness and elastic modulus by as much as 100% and 50%, respectively, depending on the indentation depth. The largest errors occur at depths approximately equal to the film thickness.

The reaction mechanisms observed when sintering loose Cr2O3–CaF2 powder mixtures were analyzed, and the influence of the sintering parameters on the reaction behavior is presented. Using x-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and differential thermal analysis (DTA) measurements, CaCrO4 was shown to be the reaction product when sintering in air. The reaction occurs in two steps: CaF2 transforms to CaO at the Cr2O3–CaF2 interface, followed by a CaO–Cr2O3 interaction, which creates the reaction product. Scanning electron microscopy (SEM) and x-ray fluorescence (XRF) analysis showed an increasing loss of CaF2 with increasing sintering temperature and heating rate, while an opposite evolution of the amount of reaction product was observed.