The mechanisms are studied for enhanced formation of C54–TiSi2 at about 700 °C when rapid thermal annealing at 3 °C/s in N2 is performed on 32-nm-thick codeposited Ti–5.9 at.% Ta on Si(100) single-crystal substrates. The enhancement is related to an increased C54–TiSi2 nucleation rate due to the development of a multilayered microstructure. The multilayer microstructure forms at temperatures below 600 °C with the formation of an amorphous disilicide adjacent to the Si substrate and a M5Si3 (M = Ti, Ta) capping layer. This amorphous disilicide crystallizes at higher temperatures to C49–TiSi2. The multilayer microstructure introduces an additional interface that increases the area available for the heterogeneous nucleation of C54. The capping layer is identified as hexagonal Ti 5Si3 or its isomorphous compound (Ti1–xTax)5Si3. Crystal simulations demonstrate that C54(040) has a lattice mismatch of 6–7% relative to Ti5Si3(300) suggesting that a pseudomorphic epitaxial relationship may lower the interfacial energy between these two phases and reduce the energy barrier for C54 nucleation. A C40 disilicide phase was also observed at temperatures above that required to form C54–TiSi2 suggesting that, in the present experiments, the C40 phase does not play a major role in catalyzing C54 formation.

An epitaxial BaTiO3 film with 290-nm thickness was prepared on a MgO(001) single-crystal substrate by radio-frequency magnetron sputter deposition. The structural characteristics of the film were studied as a function of temperature in in situ, real-time synchroton x-ray scattering experiments. We found that the as-grown film was strained at room temperature and tetragonally distorted with the c axis normal to the film surface. Interestingly, its lattice parameters were found to be expanded 1.28% and 0.64% in both the in-plane and the out-of-plane directions, respectively (i.e., biaxially), comparing to those of a bulk BaTiO3. More importantly, as it was heated to 600 °C, the tetragonal structure was kept up without the phase transition, which is usually observed in other epitaxial ferroelectric thin films.

Results of ion implantation of nitrogen into electrodeposited hard chromium and pure aluminum by a high-dose ion-beam source are presented and compared to plasma-source ion implantation. The large-area, high current density ion-beam source can be characterized, with respect to surface modification use, by a uniform emitted dose rate in the range of 1016 to 5 × 1017 N cm−2 min−1 over an area of <100 cm2 and with acceleration energies of 10–50 keV. The implantation range and retained dose (measured using ion-beam analysis), the surface hardness, coefficient of friction, and the change in the wear coefficient (measured by nanohardness indentation and pin-on-disk wear testing) that were obtained with an applied dose rate of ∼1.7 × 1017 N cm−2 min−1 at 25 kV are given, and they are compared to results obtained with plasma-source ion implantation.

A scanning acoustic microscope (SAM) has been used to investigate the structure of thermoplastic leather. This material is formed by pressing fibers of leather under high pressure and moderate temperature. The result is a matrix from transformed, melted fibers in which leftover fibers act as reinforcement. Unlike the scanning electron microscope (SEM), the SAM is able to distinguish between completely and incompletely transformed fibers and also to penetrate the material beneath the surface. The results show that the matrix is built as a domain structure. The advantages of the SAM over the SEM for organic materials are indicated.

A new self-propagating high-temperature synthesis (SHS) process has been developed for synthesis of AlN powder under low nitrogen pressures. Al and NH4X (X = F, Cl, Br, or I) powders were mixed and pressed into a compact, which was placed in a reaction chamber filled with nitrogen. The combustion synthesis reaction was ignited by heating directly the compact, and high product yields (∼90%) were obtained under nitrogen pressures of around 0.5 MPa. The product yield was affected by the reactant composition, the nitrogen pressure, and the compact-forming pressure. The powder as synthesized consists mainly of fibers, coarse granules, and agglomerated fine particles, which become mostly smaller than 10 μm after grinding. A reaction process was also proposed that explains the effects of the experimental parameters on the product yield.

Using inorganic chemicals, such as niobium pentachloride, titanium tetrachloride, lead nitrate, and magnesium nitrate, as the starting materials, 0.9PMN–0.1PT has been fabricated via a simple and low cost sol-gel processing route. A colloidal solution was first prepared by adding an aqueous lead nitrate solution into an ethanol solution of niobium and titanium chlorides. Magnesium nitrate was then mixed into the solution when chloride ions were removed by forming precipitates of PbCl2 with the excess lead nitrate. The gelation of the colloidal solution was facilitated in the presence of a small amount of polyethylene glycol (PEG 300) at 70 °C. A fine perovskite 0.9PMN–0.1PT powder was obtained when the resulting gel was dried at 300 °C for 4 h and subsequently calcined. It was observed that the sol-gel derived precursor underwent a pyrochlore phase at 500–600 °C, prior to the formation of a perovskite single phase at a calcination temperature of 850 °C. A sintered density of ˜98% theoretical density was obtained when the fine 0.9PMN–0.1PT powder was sintered at 1250 °C for 2 h and the sintered ceramic shows a maximum dielectric constant of 26,682, together with a room temperature dielectric constant of 19,206 at 1 kHz. The superb dielectric properties are correlated to the microstructural features of the sol-gel derived 0.9PMN–0.1PT, which has been characterized using techniques such as XRD, SEM, and TEM.

Lanthanum-modified lead zirconate titanate ferroelectric ceramics (Pb0.96La0.04)(Zr0.40Ti0.60)0.99O3 were synthesized by the conventional powder processing technique. X-ray diffraction experiments revealed that the samples belong to the tetragonal phase with a = b = 0.4055 nm, c = 0.4109 nm, and c/a = 1.013. After being poled, the samples were indented with a 5-kg Vickers indenter, and lateral electric fields of 0.4 Ec, 0.5 Ec, and 0.6 Ec (Ec = 1100 V/mm) were applied, respectively. Field-emission scanning electron microscopy showed that 90° domain switching appeared near the tip of the indentation crack under a lateral electric field of 0.6 Ec. A mechanism of 90° domain switching near the crack tip under an electric field is discussed.

The correlations between coarsening (including grain and pore growth) and densification, and the effects of mass transport on particle coarsening and densification were discussed based on the simple particle array models and for the real particle compacts. Grain boundary motion could cause particle coarsening only under a certain particle size distribution but not densification; mass transport is reasoned to contribute to both grain growth (particle coarsening) and shrinkage for one-dimensional particle arrays. Under a certain limitation for the change of the particle size aspect ratio during sintering, very limited effects of grain grown by itself on the shrinkage of particle a rrays throughreinitiating the sintering could be found. For a real powder compact system, mass transport between the particles, which surround a pore, contributes to the particle coarsening and densification when the pore is thermodynamically unstable and only to particle coarsening when the pore is thermodynamically stable. The mass transport mechanism for both particle coarsening and densification would be the same, which cannot exclude, at least on thermodynamics, the contribution from surface diffusion in the intermediate stage of sintering.

A comprehensive study of the chemical vapor deposition of SiC from methyltrichlorosilane at atmospheric pressure was conducted in this study; its main objectives were to identify the range of operating parameters in which stoichiometric SiC could be deposited and the generation of reliable kinetic data that could be used for the design of atmospheric pressure processes of chemical vapor deposition or chemical vapor infiltration of SiC. Deposition experiments were conducted in a hot-wall, cylindrical reactor at temperature ranging from 1273 to 573 K on flat graphite substrates or thin molybdenum wires aligned with the axis of the reactor. The obtained results showed that the deposition rate and the deposit stoichiometry varied markedly with the distance from the entrance of the reactor. The deposition rate exhibited, depending on the reaction temperature, one or two pronounced maxima before the beginning of the isothermal zone of the reaction, whereas the deposit stoichiometry showed an abrupt transition from almost silicon to stoichiometric silicon carbide after the first maximum. Experiments with HCl added in the feed showed that the presence of HCl could cause complete suppression of the deposition of silicon and lead to smoother variation of the SiC deposition rate with the residence time in the reactor. It is believed that this effect could be exploited to improve the uniformity of SiC deposition in chemical vapor deposition reactors or in the interior of porous preforms.

The paraelectric–ferroelectric structural transition of potassium lithium tantalite niobate has been studied by both Raman scattering and thermal measurements. A condensed soft lattice vibrational mode at the phase transition has been analyzed. It originates from the symmetric O2/O3–Nb/Ta–O3/O2 in-plane bending of the Nb/TaO6 group. The soft optical phonon mode concerns the extraordinary transverse optical phonons propagating along the [1 1 0] direction. The thermal expansion experiments show a displacive phase transition and a big thermal contraction in the c direction of the crystal, with an average linear expansion coefficient αc = −4.52 × 10−5 K−1. The phase transition temperature and enthalpy are 358 K and 0.50 J/g, respectively. Curie temperature measured by four methods is within 353 and 360 K.

The suitable conditions for growth of KGd(WO4)2 (KGW) and KGd1–xREx(WO4)2— RE = Nd, Er, Yb, Ho, Tm, Pr—by the top-seeded-solution-growth method, using K2W2O7 as solvent, are discussed. The relation between crystal size, mean growth rate, distribution coefficient of the substituting element, and the presence of macrodefects is analyzed. The optical absorption corresponding to the band-gap transition of KGW has been found to be temperature dependent; the absorption threshold energy changes from 34405 cm−1 at 300 K to 35330 cm−1 at 7 K. Narrow pre-edge absorption bands at about 32000 and 32600 cm−1 have been ascribed to Gd3+ intraconfigurational transitions. The photoluminescence of most RE3+ ions has been observed under ultraviolet (UV) excitation close to the absorption threshold of KGW. This suggests the contribution of charge transfer bands. In Pr-doped samples the presence of a minor concentration of Pr4+ could also contribute in this region. The irradiation with UV light does not introduce any significant coloration of our samples.

The effect of La2O3 substitutions on structure and dielectric properties of Bi2O3 –ZnO–Nb2O5-based ceramics was investigated. Bi1.5-xLaxZn0.5(Zn0.5Nb1.5)O7 samples were prepared by conventional ceramic processing technology. The crystal structure of the Bi1.5Zn0.5(Zn0.5Nb1.5)O7 sample was characterized as a pure cubic pyrochlore. With a lower amount of La2O3 substitution, the crystal structures were still cubic pyrochlore. Superlattice x-ray diffraction line was identified for some compositions. With the increasing amount of La2O3 substitution, the crystal structure gradually transformed from pure cubic pyrochlore to LaNbO4 phase. The dielectric properties regularly changed with the structure change. The structure-properties relations of the ceramics are discussed.

Coarsening (including grain growth and pore growth) and densification behavior of superfine Y-TZP and YSZ powder compacts in the intermediate stage were investigated. It has been found that grain growth in the compacts is basically not affected by the compaction properties, and pore growth is driven by both grain growth and densification. Grain growth alone leads to size-proportional pore growth, and densification results in pore shrinkage. The relation between grain size and density is analyzed to be linear when grain growth and densification are believed to be driven by different stresses under an identical diffusion process. Both theoretical and experimental results show that compaction properties and the heating rate do not alter this linear relation between grain size and density but influence the slope of the linear relation. Larger dihedral angle, higher green density, and narrower particle and pore size distributions are found favorable for the achievement of the grain size-density trajectory with promoted densification and minimized grain growth.

A new method of synthesizing silicon-based polymer films by excimer laser ablation of hexaphenyldisilane (HPDS) has been studied. The polymerized films were formed on a substrate by laser ablation deposition of HPDS at 248 nm. The structure of the polymerized films depended strongly on the laser fluence and repetition rates. The thermal stability and hardness of the deposited films were estimated by thermogravimetry and a Vickers microhardness meter. The films showed good thermal stability, depending on the laser processing parameters.

Ammonia-monochloroborane, NH3BH2Cl, has been synthesized from the reaction of ammonia-borane with HCl in Et2O. Decomposition of the solid under NH3 to 600 °C produced amorphous BN in 97% yield. The 11B magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectrum of the amorphous BN is indicative of boron in the same environment as in hexagonal BN. Subsequent pyrolysis of the amorphous BN to 1000 °C produced turbostratic BN. Pyrolysis of NH3BH2Cl under vacuum to 1100 °C led to the formation of turbostratic BN as confirmed by x-ray diffraction (XRD) analysis. Gas evolution during this pyrolysis confirmed that the precursor loses H2 and HCl.

Ag, S, Ag + S, and S + Ag single and double ion implantations in silica glass were performed at room temperature. The implantation energies were chosen in order to get a projected range of 40 nm. The fluences were 2 × 1016 S+ cm−2 and 5 × 1016 Ag+ cm−2. Silver interacts weakly with the host silica matrix and forms essentially metallic clusters; this weak interaction between Ag and SiO2 induces formation of silver silicate rather than silver oxide. Double ion implantations of silver and sulfur lead to chemical interaction between the two species that is critically influenced by the implantation sequence. In particular, in the Ag + S sample silver and sulfur atoms react to form crystalline core (Ag)–shell (Ag2S) nanoclusters.

(Mg0.22Mn0.07Fe0.71)3–δO4 ferrites with different oxygen nonstoichiometry (δ) were prepared in the range of −0.006 ≤ δ ≤ 0.0050 by a solid-state electrochemical technique, and their lattice parameter–nonstoichiometry correlation was examined. It was found that the lattice parameter decreases with increasing deviation (|δ|) from the stoichiometric composition (δ = 0). The electrochemical technique is detailed, and the correlation is discussed in light of defect structure of the ferrite.

Epitaxial, continuous, approximately 40-nm-thick films of SrZrO3 on SrTiO3 substrates prepared by a chemical solution deposition method including a postdeposition heat treatment at 900–1000 °C were subjected to further heat treatments at higher temperatures (approximately 1200–1300 °C) to investigate their high temperature stability. Experimental investigations included scanning electron microscopy, atomic force microscopy, and conventional transmission electron microscopy. The investigations have demonstrated a morphological instability of the films. Concentration profiles of the cations determined by energy dispersive x-ray spectroscopy, as well as investigations by x-ray diffraction, revealed that the film islands consisted of a solid solution. As shown by high-resolution electron microscopy, the reaction between film and substrate also led to an increase in the separation distance of the misfit dislocations that were introduced during the lower temperature heat treatment to relax the lattice mismatch strain. The morphological and structural changes of the films are reported and discussed in this paper.

The microstructure evolution of Pb(Mg1/3Nb2/3)O3 –PbTiO3 (PMN-PT) based ceramics has been investigated to determine the influence of the presence of PbO content in excess of stoichiometric values. The microstructure of the different materials showed a different evolution of secondary phases (free PbO and pyrochlore type) related to the PbO excess. The pyrochlore phase appeared in a layer near the top surface of the specimens. The thickness of the layer and the grain size of this secondary phase increased with the amount of PbO excess. A transmission electron microscopy (TEM) study of the sintered specimens revealed a core-shell structure in more than 30% of grains. The shell of these grains was Ti-rich PMN, and it is related to the presence of a liquid-phase-assisted sintering mechanism.

Interface stress is a surface thermodynamics quantity associated with the reversible work of elastically straining an internal solid interface. In a multilayered thin film, the combined effect of the interface stress of each interface results in an in-plane biaxial volume stress acting within the layers of the film that is inversely proportional to the bilayer thickness. We calculated the interface stress of an interface between {111} textured Ag and Ni on the basis of direct measurements of the dependence of the in-plane elastic strains on the bilayer thickness. The strains were obtained using transmission x-ray diffraction. Unlike previous studies of this type, we used freestanding films so that there was no need to correct for intrinsic stresses resulting from forces applied by the substrate that can lead to large uncertainties of the calculated interface stress value. Based on the lattice parameters of the bulk, pure elements, an interface stress of −2.02 ± 0.26 N/m was calculated using the x-ray diffraction results from films with bilayer thicknesses greater than 5 nm. This value is somewhat smaller than previous measurements obtained from as-deposited films supported by substrates. For smaller bilayer thicknesses the apparent interface stress becomes smaller in magnitude, possibly due to a loss of layering in the specimens.