The polymerization mechanism of a modified Pechini process was investigated by 87Sr nuclear magnetic resonance spectroscopy for the mixed solution of strontium nitrate, citric acid, and ethylene glycol. The C-ratio (the ratio of citric acid to metal ions in the polymer complex) is suggested to have a strong influence on the quality of the derived film. An analysis of the chemical shift variation, as a function of C-ratio, indicates the presence in the solution of two species: solvated strontium ions and strontium ions bound to the polymer complex, with a stoichiometry of 1:7. A polymeric precursor model based on this stoichiometry is proposed. Through a relaxation rate study of the strontium sites, it was found that the polymerization mechanism is predominantly bimolecular within the concentration region being studied. The equilibrium rate constant for the polymerization was calculated to be 104 s−1. A kinetic study of the fast cation exchange between the two identified strontium sites indicates that the inhomogeneity of the polymeric network leads to film cracking during pyrolysis.

Elemental germanium was mechanically milled with magnesium oxide with the intention of forming disperse nanoparticulate germanium in a soluble matrix. The crystallite size was determined by x-ray diffraction (XRD) and Raman spectroscopy using a phonon confinement model. The crystallite size was found to decrease exponentially with milling time; however, the size determined by XRD was typically five to ten times greater than that by Raman. This was attributed to the presence of two separate crystallite sizes, which were averaged when using the Scherrer equation for the XRD data. Sonication of the powder resulted in the breakup of >20 μm aggregates into individual particles of approximately 40 nm. These particles are thought to compose a single crystal core with a crystallite size of approximately 28 nm surrounded by a layer of smaller crystallites (approximately 5 nm), which showed quantization during Raman spectroscopy. Separation of the germanium from the magnesium oxide was readily achieved using a simple acid leach, although some oxidation of germanium was evident when using an aqueous leach.

Layered MnPS3 and CdPS3 powders were used to prepare M1−xK2xPS3/poly(ethylene glycol) (PEG) and M1−xK2xPS3/poly(vinyl pyrrolidone) (PVP) (M = Cd, Mn) intercalation nanocomposites. The structure of these compounds was studied by x-ray diffraction. The host layers in Cd0.8K0.4PS3 (PEG)2.0 and Mn0.8K0.4PS3(PEG)2.0 nanocomposites were 3-dimensional crystals with a monoclinic unit cell. The in-plane spacings were slightly expanded from original monoclinic MPS3 (0.2% for CdPS3 and 0.5% for MnPS3), while the inter-layer spacing was expanded by 8.87 Å for Cd0.8K0.4PS3(PEG)2.0 and 8.86 Å for Mn0.8K0.4PS3(PEG)2.0. The Cd0.8K0.4PS3(PVP)1.1 and Mn0.8K0.4PS3(PVP)1.1 nanocomposites, on the other hand, had an expanded interlayer spacing of about 30 Å and the diffraction patterns contained only (00l) and (hk0) peaks, and no mixed (hkl) peaks were observed. The (hk0) peaks were 2-dimensional, with strongly asymmetric line shapes, and there was excellent agreement with pattern calculations for single molecular layers. This demonstrated that the host layers in Cd0.8K0.4PS3(PVP)1.1 and Mn0.8K0.4PS3(PVP)1.1 nanocomposites were tubostratically stacked layered systems.

Hydrazine was used as a coreactant with tetrakis(dimethylamido)titanium for the low-temperature chemical vapor deposition of TiN between 50 and 200 °C. The TiN film-growth rates ranged from 5 to 45 nm/min. Ti:N ratios of approximately 1:1 were achieved. The films contain between 2 and 25 at.% carbon, as well as up to 36 at.% oxygen resulting from diffusion after air exposure. The resistivity of these films is approximately 104 μΩ cm. Annealing the films in ammonia enhances their crystallinity. The best TiN films were produced at 200 °C from a 2.7% hydrazine–ammonia mixture. The Ti:N ratio of these films is approximately 1:1, and they contain no carbon or oxygen. These films exhibit the highest growth rates observed.

New Ni-based bulk amorphous alloys in the alloy system Ni–Ti–Zr–(Si,Sn) were developed through systematic alloy design based upon the empirical rules for high glass forming alloys. Small additions of Si and/or Sn significantly improved the glass forming ability (GFA) of the alloys Ni57Ti23−xZr20 (Si,Sn)x leading to a Ni-based bulk amorphous alloy. The amorphous ribbons of the alloys Ni57Ti23−xZr20 (Si,Sn)x exhibited very high glass transition temperatures (Tg > 823 K), crystallization temperatures (Tx > 883 K), and large undercooled liquid regions (δTx > 50 K) implying the high GFA of the alloys. Fully amorphous rods with the diameter of up to 2 mm can be fabricated by a copper mold casting method. Development of the new Ni-based bulk amorphous alloys having high Tg,Tx, and δTx expands the practical applications of amorphous alloys as structural materials.

The effect of ZrO2 addition on sintering behavior and mechanical properties of both hot-pressed and pressureless-sintered B4C was investigated. The addition of ZrO2 improved the densification behavior of B4C remarkably via a reaction with the B4C to form ZrB2 at elevated temperatures. When B4C was densified at 2000 °C by hot pressing, only a small amount (approximately 2.5 vol%) of ZrO2 was necessary to achieve a full densification. Excellent mechanical properties (hardness, elastic modulus, flexural strength, and fracture toughness) were observed in those specimens. As the amount of ZrO2 was increased further, the mechanical properties were reduced, except for the fracture toughness, apparently due to the formation of too much ZrB2 in the specimen. Without the applied pressure, larger amounts of ZrO2 should be added to obtain a body with high relative density. When the B4C was sintered at 2175 °C with addition of 10 vol% ZrO2, the specimen has a density higher than 95% of the theoretical, and hardness and flexural strength of 25 GPa and 400 MPa, respectively.

A combined investigation of stress relaxation in WOxNy thin films sputter deposited on silicon wafers in an Ar–N2–O2 gas mixture by in situ substrate curvature measurements and of structural properties by ex situ x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy (TEM), electron energy loss spectroscopy, and transmission electron diffraction is reported. It was found that the W2N films deposited under oxygen-free conditions had a high compressive stress of 1.45 GPa. As the oxygen concentration was increased, the stress became smaller and reached almost zero for films near 10–15 at.% oxygen. These results can be understood in terms of the decrease in the lattice parameter caused by substituting nitrogen atoms with oxygen in the lattice sites and the development of an amorphous network in the WOxNy films as the incorporation of oxygen was increased. Plan view and cross-sectional TEM analyses showed that 150-nm-thick oxygen-free crystalline W2N films had a columnar microstructure with an average column width of 15–20 nm near the film surface, whereas oxygen imbedded in the films provided a finer grain structure. The effect of oxygen in stabilizing the W2N structure was also elucidated and explained on the basis of structural and thermodynamic stability.

LiNbO3 thin films were grown on (0001) sapphire substrates by a chemical route, using the polymeric precursor method. The overall process consists of preparing a coating solution from the Pechini process, based on metallic citrate polymerization. The precursor films, deposited by dip coating, are then heat treated to eliminate the organic material and to synthesize the phase. In this work, we studied the influence of the heat treatment on the structural and optical properties of single-layered films. Two routes were also investigated to increase the film thickness: increasing the viscosity of the coating solution and/or increasing the number of successively deposited layers. The x-ray diffraction θ-2θ scans revealed the c-axis orientation of the single- and multilayered films and showed that efficient crystallization can be obtained at temperatures as low as 400 °C. The phi-scan diffraction evidenced the epitaxial growth with two in-plane variants. A microstructural study revealed that the films were crack free, homogeneous, and relatively dense. Finally, the investigation of the optical properties (optical transmittance and refractive index) confirmed the good quality of the films. These results indicate that the polymeric precursor method is a promising process to develop lithium niobate waveguides.

Epitaxial La0.7Ca0.3MnO3 thin film and [Y0.7Ca0.3MnO3/La0.7Ca0.3MnO3]10 multilayers of about 140 nm in thickness were grown by pulsed laser deposition on (001)LaAlO3. Their microstructures were investigated by transmission electron microscopy and associated techniques. It was found that both the film and the multilayers contain an almost defect-free layer near the substrate, followed by columnar grain grown. The columns were separated by strained regions in the top layer. No interfacial dislocations were observed at either of the La0.7Ca0.3MnO3/LaAlO3 or the Y0.7Ca0.3MnO3/La0.7Ca0.3MnO3 interfaces. Interestingly, both the epitaxial film and the multilayers exhibited layered crystallographic domains. The formation mechanisms of the layered domain structures observed are discussed.

Lanthanum phosphate glasses were synthesized by melt quenching and characterized by x-ray diffraction, electron microprobe analysis, and solid-state nuclear magnetic resonance spectroscopy. A range of compositions near the metaphosphate composition (75 mol% P2O5) was examined. Comparison of 31P chemical shifts and shielding anisotropies of glasses with those of the crystalline phases of La(PO3)3 (metaphosphate) and LaP5O14 (pentaphosphate) were consistent with the presence of primarily chainlike Q2 phosphate groups.

A simple model was presented for intrinsic stress generation in thin films resulting from surface stress effects. This mechanism can explain the origin of compressive stresses often observed during island growth prior to coalescence, as well as intrinsic compressive stresses reported for certain continuous, fully grown films. In some cases, surface stress effects may contribute to a sudden change in the intrinsic stress during island coalescence.

The original equation of Spence and Taftø for quantitative determination of site occupancy using atom location by channeling enhanced microanalysis method has been extended to take into account both delocalization effect and the influence of point defects (antisite atomic distribution and vacancies). The outcome of this treatment suggests that, for crystals free of antisite defects, the accuracy of site occupancy is influenced by delocalization effect but is independent of both thermal and structural vacancies. For crystals free of structural vacancies, the accuracy of site occupancy is influenced by both delocalization effect and antisite defects, but is independent of thermal vacancies. The delocalization effect was shown to vary with channeling strength at a given channeling condition. For a binary ordered phase in which at least one of the host elements exhibits weak delocalization effect (as is the case for many transition-metal aluminides), a tangent-line method for obtaining the value of k (a parameter necessary for the calculation of site occupancy) was proposed, allowing the determination of the delocalization correction factor for the other host element. Application of this method to estimating the delocalization effect of Al in Ti3Al and TiAl under axial and planar channeling conditions, respectively, was demonstrated.

Nanocomposite ceramic materials were fabricated by conventional sintering of composite powders obtained by sol-gel coating of submicron powders. The microstructure of these MgAl2O4–ZrO2 materials was studied by transmission electron microscopy. All zirconia grains were in the tetragonal phase. In addition, the intragranular zirconia crystals exhibited heteroepitaxial orientation relationships with the surrounding spinel grains, (hkl)zirconia//(hkl)spinel. Semi-coherent interfaces along {111} planes were observed by high-resolution microscopy. The transformation toward the orthorhombic or the monoclinic phase retained the epitaxial relationships as far as possible. The presence of such heteroepitaxial intragranular crystals in sintered ceramic materials, which did not involve a melting stage, was attributed to the specificity of the material preparation process.

Magnetization measurements, transmission electron microscopy (TEM), and high-resolution micro-x-ray fluorescence (μ-XRF) using a synchrotron radiation source (Advanced Photon Source) were used to examine Fe3O4 particle agglomerates of nominally 10-nm particles at low concentrations (down to 0.03%) in thick epoxy resin samples. The magnetization measurements showed that at low concentrations (<0.5%) the magnetite particles, although closely packed in the agglomerates, did not interact magnetically. Predicated on a 2-μm sample step scan, the μ-XRF results were compatible with the presence of spherical agglomerates due to magnetostatic attraction, and these ranged in size from 100 to several thousand nanometers, as observed in TEM measurements. At smaller step scans the resolution could be significantly improved. Thus, the synchroton μ-XRF method was very useful in detecting very small concentrations of particles in thick samples and could probably be used to detect particles in amounts as low as 10−16 g.

Time-of-flight measurements performed on micron-thick films of liquid-crystalline zinc octakis(β-octoxyethyl) porphyrin indicated that charge carriers possess significantly high drift mobilities, attaining approximately 0.01 cm2 V−1s −1 and 0.008 cm2 V−1s −1 for holes and electrons, respectively, at room temperature. Upon heating the samples from 300 to 420 K, causing the porphyrin to go from the solid-crystalline to the discotic mesophase, the mobilities did not decrease drastically, and remained at values slightly larger than half those observed at room temperature. Charge transport in this material conformed to the Scher–Montroll model, which attributes a distribution of hopping times to the propagation of the initially formed charged carrier packet. Analysis of the “universal” plots prescribed by this model yielded a dispersion factor of 0.5 for both charge carriers.

A detailed study on the sintering behavior of zirconium diboride powder produced by the self-propagating high-temperature synthesis (SHS) process was carried out in the temperature range of 1500–1800 °C. The fine powder prepared by the SHS process exhibited excellent sinterability and could be sintered at 1800 °C for 1 h to approximately 94% of the theoretical density. The apparent activation energy of densification in the range of 1500–1800 °C was estimated to be 248 ± 4 kJ mol−1. A zirconium dioxide layer formed on the surface of the sintered body and was attributed to boron oxide formation during sintering and concurrent surface oxidation by the oxygen generated from the reduction of boron oxide in the carbonaceous atmosphere. Sintering aids like Fe and Cr appeared to help in densification of ZrB2 powder.

This work was directed toward developing a database for the long-term reliability of the transverse piezoelectric coefficient d31 under both unipolar and bipolar drive. Under unipolar drive, the films showed excellent reliability, with 99% of the devices surviving to 109 cycles. However, both aging and low amplitude bipolar drive resulted in rapid degradation of d31 due to backswitching of the ferroelectric domains. Both thermal and ultraviolet (UV) imprint prevented backswitching and resulted in improved aging and bipolar degradation behavior. Additionally, the UV imprinted samples showed nonlinear aging due to the presence of an internal space charge field that developed from photo-induced charge carriers.

The synthesis of AlN–SiC solid solutions from Si3N4, Al, and C was investigated using the induction-field-activated/self-propagating high-temperature synthesis/static pseudo-isostatic compaction technique. Careful x-ray diffraction analyses were made on the products of combustion to determine reaction routes. Optical microscopy as well as scanning electron microscopy with an electron probe microanalysis was used for microstructural analysis. It was found that initially molten aluminum reacted with silicon nitride producing an Al–Si alloy. At higher temperatures, aluminum evaporated from the Al–Si liquid and the synthesis of AlN via a vapor phase process took place. Subsequently, dissolution of AlN into molten Si resulted in the formation of an AlN–SiC solid solution from the Al–N–Si–C liquid phase. However, below 1850 °C, the resulting solid solution of 4AlN–3SiC was not fully crystallized. Combustion temperatures above or equal to 1850 °C were required to prepare a highly crystallized solid solution with a morphology exhibiting hexagonal platelets. Based on these observations, a model for the formation of AlN–SiC solid solution is proposed.

A new route for obtaining calcium-deficient apatites with a Ca/P ratio lower than 1.5 is described, in order to study their proton conduction at temperatures lower than 400 °C. The process is based on the hydrolysis of a mixed solution of Ca(NO3)2 and NH4H2PO4 in the presence of hexamethylenetetramine at a pH of approximately 5 and temperatures of 85–90 °C. The resulting spherical particles of 14 μm in average diameter were aggregates of smaller needles with approximate composition Ca8.5(HPO4)2(PO4)4OH · H2O. The effects of the reagent concentrations, pH, aging time, and temperature were studied, and the solids were characterized by x-ray diffraction, infrared absorption spectroscopy, and electron microscopy. The ionic conduction measured by alternating-current impedance spectroscopy yielded a value of 3 μSm−1 at 200 °C.

Ni3Sn4 intermetallic was formed by the depletion of Ni from electroless Ni–P, and a Ni3P layer was formed simultaneously due to solder reaction-assisted crystallization during solder reflow. Both Ni3Sn4 and Ni3P grew rapidly due to the solder reaction-assisted crystallization and their growth was diffusion controlled during the first 15 min of annealing at 220 °C. After that, the growth rate of Ni3Sn4 was greatly reduced and the crystallization of electroless Ni–P to Ni3P was no longer induced. Based on kinetic data and scanning electron microscope morphology observations, underlying mechanisms causing this specific phenomenon are proposed. This finding is indeed very crucial since we may control the growth of Ni–Sn intermetallics by monitoring the solder reaction-assisted crystallization of electroless Ni–P.