We successfully deposited high-quality TiN films on c-plane sapphire by using the pulsed laser deposition technique. TiN grew on sapphire with two in-plane epitaxial relationships: (111)TiN//(0001)sapphire and [101]TiN//[1100]sapphire or (111)TiN// (0001)sapphire and [101]TiN//[1100]sapphire. The TiN unit cell showed a ±30° in-plane rotation for sapphire. The misfit between the TiN film and the sapphire substrate was calculated by using the near coincidence site lattice approach. The deposited films were analyzed by x-ray diffraction, transmission electron microscopy, atomic force microscopy, Rutherford backscattering or channeling spectrometry, electrical, and spectrophotometric measurements. The dependence of the film's crystalline quality on the deposition temperature has been investigated. The full width half-maximum of the rocking curve of the TiN 111 peak was 0.2–0.3°. The minimum ion channeling was 5%, and the room temperature resistivity was as low as 13 μω cm.

PbTiO3 powders and heteroepitaxial thin films were produced by the hydrothermal method at 110–200 °C using different bases (Na–, K–, Rb–, Cs–, TMA–, and TBA–OH). Microstructural characterization showed that the tetragonal perovskite films were epitaxial on the SrTiO3 substrates, with a c-axis out-of-plane orientation. Sequential growth experiments showed that the growth initiates by the formation of 100 nm {100} faceted PbTiO3 islands followed by coalescence. Small cation bases (Na–, K–, Rb–OH) produced 1.5-μm {100} faceted blocky powders, whereas larger cation bases (Cs–, TMA–, and TBA–OH) formed fewer 500-nm interpenetrating platelets. Nuclear magnetic resonance results showed cation incorporation in the perovskite structure with local disorder on the Pb sites increasing cation size.

The types and structures of oxide phases produced during the incongruent reduction of sapphire (single-crystal Al2O3) by molten magnesium were examined. Polished faces of sapphire were exposed to molten magnesium at 1000 °C for 100 h. Such exposure resulted in the formation of a continuous, epitaxial layer of spinel (MgAl2O4) on sapphire and a continuous, epitaxial layer of magnesia (MgO) on the spinel. X-ray pole figure analyses indicated that two variants of spinel and magnesia had formed in a manner consistent with the following orientation relationships:

The occurrence of segregation and its influence on microstructural and phase evolution have been studied in MgO–MgAl2O4 powders synthesized by thermal decomposition of aqueous nitrate precursors. When the nitrate solutions of Mg and Al were spray-pyrolyzed on a substrate held at 673 or 573 K, homogeneous mixed oxides were produced. Spraying and drying the nitrate solutions at 473 K resulted in the formation of compositionally inhomogeneous, segregated oxide mixtures. It is suggested that segregation in the dried powders was caused by the difference in solubility of the individual nitrate salts in water which caused Mg-rich and Al-rich salts to precipitate during dehydration of the solutions. The occurrence of segregation in the powders sprayed at 473 K and not 573 or 673 K is ascribed to the sluggish rate at which the early stages of decomposition occurred during which the cations segregated. The phase evolution in segregated and segregation-free MgO–MgAl2O4 powders has been compared. The distinguishing feature of the segregated powders was the appearance of stoichiometric periclase grain dimensions in excess of 0.3 μm at temperatures as low as 973 K. By comparison, the segregation-free powders displayed broad diffraction peaks corresponding to fine-grained and nonstoichiometric periclase. The grain size was in the range 5–30 nm at temperatures up to 1173 K. The key to obtaining fine-grained periclase was the ability to synthesize (Mg Al)O solid solutions with the rock salt structure. In the temperature range 973–1173 K, spinel grain size varied from 5 to 40 nm irrespective of its composition and did not appear to be influenced by segregation.

Ba1−xSrxTiO3-based positive temperature coefficient resistance (PTCR) ceramics were prepared by use of a vapor-doping method. When doped with Bi, the PTCR effect is improved; when doped with lead, however, the effect is weakened. The different influences of Bi and Pb doping on the ceramic properties are discussed in terms of the defect chemistry.

The electrical properties of hydrothermally grown epitaxial pseudocubic BaTiO3 thin films formed on epitaxial electrode layers of SrRuO3 on SrTiO3 single crystal substrates have been evaluated by variable frequency dielectric testing. The initial as-synthesized BaTiO3 film displayed a dielectric constant of 450 with very high losses (tan δ ˜ ~ 100%) at 10 kHz due to OH− and H2O, incorporated during growth, contributing to migration losses within the film. Improvements were seen with increasing postprocessing heat-treatment time and temperature with improved properties seen after a heat treatment at 300 °C for 24 h (ε ˜ ~ 200, tan δ ˜ ~ 8%). Relationships were established for dielectric constant and loss tangent with structural changes observed by Fourier transform infrared spectroscopy, thermal gravimetric analysis, nuclear magnetic resonance spectroscopy, and x-ray diffraction.

The Ni/(ZrO2 + 9.5 mol% Y2O3) interface was used as a model system to investigate decomposition reactions of a yttria-stabilized ZrO2 electrolyte in contact with a metal at elevated temperature. In the present study, the sample was a diffusion-bonded symmetrical galvanic cell Ni‌ZrO2 + 9.5 mol% Y2O3‌Ni. Various electron microscopy techniques were used to study the morphology and structure of the reaction products at the Ni–ZrO2 electrolyte phase boundary after current flow. Below a critical oxygen partial pressure of approximately 10−27 atm, an intermetallic reaction layer formed at the Ni–electrolyte interface. Between the intermetallic layer and electrolyte a thin Y2O3 layer was present, which acted as a diffusion barrier for Zr and Ni, slowing down the overall chemical reaction. At several locations at the interface the Y2O3 layer broke up, leading to a morphological instability of the interface between electrolyte and Ni5Zr, allowing further reaction. The thickness of the total reaction layer varied widely as a consequence of such an instability.

Rutile TiO2 nanowhiskers have been synthesized by annealing a precursor powder in which NaCl and Ti(OH)4 particles were homogeneously mixed. The precursor powder was prepared by mixing three kinds of inverse microemulsions (μE) containing TiCl4 aqueous solution, ammonia, and NaCl aqueous solution, respectively, followed by washing with acetone. Annealing temperature and packing density of Ti(OH)4 in the precursor powder influenced the formation of rutile nanowhiskers. The optimum temperature was 750 °C. TiO2 nanowhiskers obtained by annealing a precursor powder in which the molar ratio of sodium to titanium was 400 at 750 °C for 2 h had diameters of 10–50 nm and lengths of several micrometers. They were straight rods with square cross sections, and the side surfaces were composed of four equivalent {110} planes.

An α–Fe2O3 powder of nanosized particles has been successfully prepared by effectively dispersing the precipitated hydroxide precursor in a sodium chloride matrix. In particular, the hydroxide precursor was converted into crystalline α–Fe2O3 particles approximately 10 nm in size when it was mechanically activated in the sodium chloride matrix for 1 h. The subsequent calcination at 600 °C for 1 h resulted in a limited degree of coarsening in particle size while the crystallinity of α–Fe2O3 was further established. The effectiveness of obtaining ultrafine a–Fe2O3 powders by mechanical activation in the sodium chloride matrix was demonstrated by comparing the powder with those obtained via other routes, such as mechanical activation without sodium chloride as the matrix, calcination at 600 °C, and then mechanical activation in sodium chloride matrix, respectively. None of these processing routes led to a powder comparable in particle characteristics to that derived by the precursor dispersion.

Using a pulse electric current sintering (PECS) method, β–SiC and α–SiC powders doped with a few weight percent of Al2O3–Y2O3 oxide or Al4C3–B4C–C nonoxide additives were rapidly densified to high densities (95.2–99.7%) within less than 30 min of total processing time. When Al2O3–Y2O3 additive was used, both ceramics resulting from β–SiC and α–SiC had fine, equiaxed microstructures. In contrast, when Al4C3–B4C–C additive was used, the ceramic resulting from α–SiC had a coarse, equiaxed microstructure, whereas the ceramic resulting from β–SiC was composed of large elongated grains whose formation was accompanied by the β →?α phase transformation of SiC. Compared with the Al2O3–Y2O3-doped SiC ceramics, the Al4C3–B4C–C-doped SiC ceramics had higher densities, lower fracture toughness, and higher hardness. The fracture mode of the oxide-doped SiC was mainly intergranular, whereas the nonoxide-doped SiC exhibited almost complete intragranular fracture that was attributed to the higher interfacial bonding strength.

Characterization of bulk defects was successfully accomplished in alumina with a transmission optical microscope. The characterization technique used is based on the fact that many ceramics are essentially transparent. Most defects in this particular ceramic were found to be pore. Their size distribution was found to follow a simple power function. With these characteristics of defects, the strength distribution of the ceramics was calculated with Baratta's model and compared to the measured strength of the ceramics. A good agreement was found between them when the pore was assumed to be accompanied with cracks 4 times the length of the grain size.

Biphase dielectric ceramics in the system of (1 − x)Ba4Nd2Ti4Ta6O30/ x(La0.1Bi0.9) 2Ti2O7 were investigated to obtain a near-zero temperature coefficient of dielectric constant. With the increase in x, the dielectric constant increased slightly, and the temperature coefficient changed from negative to positive. High dielectric constant of ε = 143 and good temperature stabibility (τ ε = −48 ppm/ °C) were achieved in a composition of x = 0.45, and the increased dielectric loss became the new problem.

High molecular weight anionic polymers have been incorporated into the calcium silicate hydrate (C–S–H) structure during precipitation of quasicrystalline C–S–H from aqueous solution. The anionic polymers studied were poly(methacrylic acid), poly(acrylic acid), and the sodium salt of poly(vinyl sulfonic acid). Expansion of the interlayer spacing coupled with high-carbon contents confirmed that the polymers intercalated between the layers. D-gluconic acid behaves similarly. Intercalation characteristics strongly depended on both the type of polymer and Ca/Si molar ratio of C–S–H; intercalation reached a maximum at an initial Ca/Si = 1.3 in all cases. Poly(vinyl alcohol) was the only nonionic polymer among those studied that was incorporated into C–S–H. Evidence for interlayer intercalation is less definite. The C–S–H/polymer complexes were examined by Fourier transform infrared spectroscopy, 29Si nuclear magnetic resonance magic angle spinning, and 13C cross-polarization, magic angle spinning nuclear magnetic resonance spectroscopy.

Some high molecular weight cationic polymers, poly(diallyldimethylammonium chloride) (PDC) and poly(4-vinylbenzyltrimethylammonium chloride) (PVC), have been incorporated into the calcium silicate hydrate (C–S–H) structure during precipitation of quasicrystalline C–S–H from aqueous solution. Expansion of the interlayer spacing [0.9 nm (PDC), 1.5 nm (PVC)] and a high-carbon content provided evidence that these polymers were intercalated between layers of C–S–H when Ca/Si <1.0. Intercalation characteristic properties strongly depended on both of the type of polymer and Ca/Si ratio in C–S–H. Poly(4-vinyl-1-methylpyridinium bromide) and methyl glycol chitosan (iodide) also interacted with C–S–H, probably by surface adsorption. The C–S–H/polymer complexes were examined by Fourier transform infrared spectroscopy, 29Si nuclear magnetic resonance magic angle spinning, and 13C cross-polarization, magic angle spinning nuclear magnetic resonance spectroscopy. Mechanisms of intercalation of different kinds of polymers between the C–S–H layers are discussed.

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.

A fractional factorial design was implemented to optimize the experimental conditions for the preparation of ultrafine lanthanum-doped strontium titanate from titanyl acylate precursors. The effects of preparation conditions such as the molar ratio of acetic acid to titanium alkoxide, the water to titanium alkoxide ratio, pH value, the reaction temperature, and stirring speed were systematically studied by using Taguchi orthogonal array design. Results indicated that the effects of the reaction temperature and stirring speed on the reaction were the key variables influencing the average particle size of powders obtained. By combining the optimal settings of the two influential processing variables, it was possible to obtain an ultrafine powder with a particle size of about 340 Å. This was put to a test in the laboratory, and a polycrystalline, narrow size distribution ultrafine SrTiO3 powder that had a particle size of about 380 Å and readily sintered at 1150–1250 °C was obtained.

A polymerized organic–inorganic complexion route is introduced for the synthesis of yttrium aluminum garnet, YAG (Y3Al5O12) and cordierite (Mg2Al4Si5O18) powders. Long-chain polymers such as polyvinyl alcohol (–[CH2–CHOH]-n or PVA) or polyethylene glycol (H[O–CH2–CH2]nOH or PEG) were used as the organic carriers for a precursor ceramic gel. Calcined powders were very porous and homogeneous in distribution of components. Experimental studies by differential thermal analysis and thermogravimetric analysis, x-ray diffraction, solid-state nuclear magnetic resonance, and Fourier transform infrared spectrometry indicated that metal-ion chelation is not the primary mechanism for obtaining molecularly homogeneous precursor powders. Water-soluble cations of mixed oxides in the PVA or PEG process were sterically entrapped in the entangled network and resulted in fine and pure, mixed oxide powders.

A low-temperature method was used to synthesize a nickel–chromium–zinc ferrite from stainless steel pickling liquor, a waste product of the steel industry, which is listed in most industrialized countries as a toxic and hazardous waste. This article reports the recovery (as a valuable ferric product) of the total metal content of this waste (namely, iron, chromium, nickel, and minor manganese), by coprecipitation of the multi-ionic solution and Zn2+ (provided by ZnO) with 1 M n-butylamine at room temperature. The spinel-type ferrite produced was characterized by x-ray diffraction, thermogravimetric analysis and differential scanning calorimetry, and scanning electron microscopy. Its recorded magnetization of 2600 emu cm−3 allows its use in different magnetic applications. Furthermore, the synthesis method is a low-cost technology that yields a more environmentally friendly final effluent.

Interfacial reactions of Co/Si0.76Ge0.24 and Co(Si0.76Ge0.24)/Si0.76Ge0.24 by pulsed KrF laser annealing as a function of energy density and pulse number were studied. For the Co/Si0.76Ge0.24 samples annealed at an energy density of 0.2–0.6 J/cm2, three germanosilicide layers, i.e., amorphous structure and/or nanocrystal, Co(Si1−xGex), and Co(Si1−xGex)2, were successively formed along the film-depth direction. At 0.3 J/cm2 Ge segregated to the underlying Si0.76Ge0.24 film, inducing strain relaxation in the residual Si0.76Ge0.24 film. At 0.8 J/cm2 the reacted region was mostly transformed to a single layer of Co(Si1−xGex)2, whereas Ge further diffused to the Si substrate. At 1.0 J/cm2, constitutional supercooling appeared. Even the Co(Si0.76Ge0.24) film used as the starting material for laser annealing could not prevent the occurrence of constitutional supercooling at energy densities >1.6 J/cm2. The energy densities at which Co(Si1−xGex) transformation to Co(Si1−xGex)2, Ge segregation to the underlying Si, and constitutional supercooling occurred were higher for the Co(Si0.76Ge0.24)/ Si0.76Ge0.24 system than for the Co/Si0.76Ge0.24 system. Higher energy density and/or pulse number enhanced the growth of Co(Si1−xGex)2 film. In the present study, the Co/Si0.76Ge0.24 samples subjected to annealing at 0.2 J/cm2 for 20 pulses produced a smooth Co(Si0.76Ge0.24)2 film without inducing Ge segregation out of the germanosilicide and strain relaxation in the unreacted Si0.76Ge0.24 film.

The incorporation of vacancies, H atoms, and sp2 bond defects into single-crystal homoepitaxial (100) (2 × 1)–and (111)-oriented chemical-vapor-deposited diamond was simulated by atomic-scale kinetic Monte Carlo. Simulations were performed for substrate temperatures from 600 to 1200 °C with 0.4% CH4 in the feed gas, and for 0.4–7% CH4 feeds with a substrate temperature of 800 °C. The concentrations of incorporated H atoms increased with increasing substrate temperature and feed gas composition, and sp2 bond trapping increased with increasing feed gas composition. Vacancy concentrations were low under all conditions. The ratio of growth rate to H atom concentration was highest around 800–900°C, and the growth rate to sp2 ratio was maximum around 1% CH4, suggesting that these conditions are ideal for economical diamond growth under simulated conditions.