Phase-pure perovskite lead titanate with various morphologies has been synthesized by a hydrothermal method at 150 °C. Particle shapes include cubic, tabular, and aggregated platelike shapes. The feedstock concentration greatly influences particle morphology of the hydrothermally derived PbTiO3. At a concentration of 0.05 M, the tabular particles form while cubic particles are produced at 0.1 M. Aggregated plateletlike particles are synthesized at 0.125 M. It was observed that both tabular and cubic particles directly precipitate from the coprecipitated precursor gel. In contrast, the plateletlike shaped intermediate phase appears during the initial stage of reaction at 0.125 M and in situ transforms into perovskite PbTiO3 during further hydrothermal treatment. The intermediate phase preserves its particle shape during transformation and, acting as a template, gives rise to the final tabular PbTiO3 particles. It is demonstrated that only base reagents such KOH and NaOH, which provide a highly basic condition (i.e., pH > 14), promote transformation of the coprecipitated gel into the perovskite PbTiO3. A Hancock and Sharp kinetic analysis in conjunction with microstructural evidence suggests that the formation mechanism is dissolution and recrystallization in which the degree of supersaturation plays an important role in dictating the crystallographic particle phase and morphology of the particles. An experimentally constructed solubility diagram indicates that an excess lead condition is necessary to compensate for loss of lead species and to increase supersaturation to expedite precipitation of PbTiO3 at highly alkaline conditions.

An attempt has been made to improve the intermediate temperature strength of cryomilled NiAl by utilizing third element solid solution or precipitation strengthening mechanisms. To this end an NiAl–0.7 (at.%) Zr alloy was cryomilled, densified by hot extrusion, and tested between 1000 and 1400 K. Although over 3 wt% nitrogen was introduced via cryomilling, mechanical testing revealed that the cryomilled NiAl–0.7Zr was significantly weaker than the base alloy between 1000 and 1200 K. Chemical and microstructural analyses revealed that, in addition to ∼ 16 vol% AlN, all the Zr had been converted into ZrN. A thermodynamic analysis of cryomilling indicated that the formation of ZrN could have been anticipated since it is a more stable nitride than AlN. While Zr was an unsatisfactory addition in NiAl, thermodynamics also suggest several alloying elements that might lead to good intermediate temperature strength after cryomilling.

Several experiments have been conducted to assess the possible mechanisms for the inhibition of reduction of Ca2+-doped barium titanate in a reducing atmosphere. Three methods, i.e., conventional, semiwet, and citrate processes, have been used to prepare the powders. It was found that the formation mechanism would influence the occupation of Ca2+ in the B site. Moreover, it was concluded that Ca2+ occupation of the B site is the major cause for the inhibition of reduction of Ca2+-doped barium titanate. Ti deficiency would be the driving force for Ca2+ to occupy the B site.

The effects of borosilicate glass (BSG) on the kinetics and mechanism of anataseto- rutile phase transformation have been investigated. The displacive anatase-to-rutile phase transformation kinetics of TiO2 were greatly enhanced in the presence of BSG. The transformation kinetics followed the Avrami equation, and the results showed an apparent activation energy of 260–370 kJ/mol, which was close to the bond strength of Ti–O, suggesting a reaction-controlling mechanism. The values of the Avrami exponent were in the range of 1.4–2.3, which could be interpreted as two-dimensional reaction-controlled growth at zero nucleation rate. The rutile particles obtained by the phase transformation were always much larger than the starting anatase powders, which was explained by a mechanism of phase-transformation–induced particle coalescence.

In situ transmission electron microscopy (TEM) was performed to study dislocation motion during temperature cycles in aluminum films passivated with a SiO2 layer. The films were cycled from room temperature to 450 °C. Wedge-haped cross-sectional TEM samples were used to retain the constraint of the Si substrate. Besides interactions between dislocations and interfaces, the movement of threading dislocations within the constrained aluminum film was observed. This observation provides an experimental corroboration of the occurrence of threading dislocation motion, which is the basis for rationalizing the high-ield strength of thin films in available models of thin-film plasticity.

6H(α)-SiC fine powder was sintered at normal pressure with additives of between 0.67 to 2.7 wt.% of AlB2 and 2 wt.% of C. The powder could be densified at 1850 °C. This sintering temperature was lower than that for SiC with B and C additives by 150–300 °C. During sintering, 6H-SiC partially transformed into 4H-SiC, and the transformation caused grain to grow and develop a nonspherical shape. The fracture toughness of sintered SiC increased with increases in the amount of AlB2 additive, the mean grain size, and the mean aspect ratio of grain shape. AlB2 and C additives are believed to have formed an Al8B4C7 compound which melted below 1800 °C and enhanced sintering and grain growth.

Carbon microcoils were grown by the Ni-catalyzed pyrolysis of acetylene. The growth patterns and the tip morphologies of the carbon coils are examined in detail, and a growth mechanism is proposed. Basically, six thin fibers grew from a Ni catalyst grain during the initial growth stage immediately followed by the coalescence of the four fibers to form two fibers and then forming double-helixed carbon coils. A small amount of S and O, as well as C and Ni, was observed on the periphery of the cross section of the Ni catalyst grain. On the other hand, S and O were not observed in the central part. The driving force of the coiling of the straight fibers to form carbon coils is considered to be the strong anisotropy of the carbon deposition between different crystal faces.

PbTe thin films with fine grains were successfully fabricated by the gas evaporation method. Thermoelectric properties, i.e., Seebeck coefficient and electrical conductivity, both decreased with decreasing grain size. This was attributed to the decrease in carrier mobility exceeding the increase in carrier concentration with decreasing grain size. It was clarified that the effects of grain boundaries and of oxidation on carrier mobility are considerably large.

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.

Six thermophysical properties of both solid and liquid zirconium measured using the high-temperature electrostatic levitator at the Jet Propulsion Laboratory are presented. These properties are density, thermal expansion coefficient, constant pressure heat capacity, hemispherical total emissivity, surface tension, and viscosity. For the first time, we report the densities and the thermal expansion coefficients of both the solid as well as liquid Zr over wide ranges of temperatures. Over the 1700–2300 K temperature span, the liquid density can be expressed as ρ1(T) = 6.24 × 103 – 0.29(T – Tm) kg/m3 with Tm = 2128 K, and the corresponding volume expansion coefficient as α1 = 4.6 × 10−5/K. Similarly, over the 1250–2100 K range, the measured density of the solid can be expressed as ρs(T) = 6.34 × 103 – 0.15(T – Tm), giving a volume expansion coefficient αs = 2.35 × 10−5/K. The constant pressure heat capacity of the liquid phase could be estimated as Cpl(T) = 39.72 – 7.42 × 10−3(T – Tm) J/(mol/K) if the hemispherical total emissivity of the liquid phase εT1 remains constant at 0.3 over the 1825–2200 K range. Over the 1400–2100 K temperature span, the hemispherical total emissivity of the solid phase could be rendered as εTs(T) = 0.29 – 9.91 × 103 (T – Tm). The measured surface tension and the viscosity of the molten zirconium over the 1850–2200 K range can be expressed as ς(T) = 1.459 × 103 – 0.244 (T – Tm) mN/m and as η(T) = 4.83 – 5.31 × 10−3(T – Tm) mPa s, respectively.

Effects of borosilicate glass (BSG) on densification and dielectric and thermal expansion properties of a binary composite of BSG + TiO2 ceramics have been investigated. Two different phases of TiO2 including anatase and rutile are used. A much greater densification is observed with anatase because it has a much better wetting with BSG than rutile. With increasing BSG content, the densification of BSG + TiO2 increased. Activation analysis shows that the densification is controlled by viscous flow of BSG. Both dielectric constant and coefficient of thermal expansion of the binary composite of BSG + TiO2 increase with decreasing BSG content and increasing the degree of anatase-to-rutile transformation, as well.

The behaviors of a crack in body-centered-cubic metal Mo under different loading modes were studied using the molecular dynamics method. Dislocation emission was observed near the crack tip in response to mode II loading with θ = 0° in which θ is the inclination angle of the slip plane with respect to the crack plane, and two full dislocations were observed at the stress level of KII = 1.17 MPa m1/2 without any evidence of crack extension. Within the range of 0° ≤ θ ≤ 45°, crack extension was observed in response to mode I loading, and the effect of crystal orientation on the crack propagation was studied. The crack propagated along the [111] slip direction without any evidence of dislocations emission.

The epitaxial PbTiO3 thin films of different thickness were prepared on MgO(001) substrates by the reactive direct-current magnetron sputtering. The volume fraction of c domains, α, which was measured by x-ray diffractometry, increased rapidly from zero with the film thickness, being saturated at about 90% above 100 nm. The films were annealed in a PbO atmosphere at 700 °C for 8 h, and they were used to study the composition change in the Pb/(Pb + Ti) ratio and the relaxation of the residual intrinsic stress. The relationship between change of α and composition was weak. The stress state was calculated through the finite-element method. As for the small thickness, the tensile epitaxial stress overwhelmed compressive intrinsic and thermal stresses, and the domain structure was a-domain oriented. As for the large thickness, the compressive intrinsic stress together with the thermal stress overcame the tensile epitaxial stress, and the population turned into c domain.

The perovskite compounds with the composition of (1 – x) Pb(Ni1/3Nb2/3)O3 –xPbZrO3 have been successfully prepared from hydrothermally treated precursors. During calcination, the primary intermediate compound is pyrochlore phase in the Pb(Ni1/3Nb2/3)O3-rich composition, while it is PbZrO3 on the PbZrO3-rich side. On calcination at 800 °C, all precursors convert into perovskite phases. In the formed solid solutions, increasing PbZrO3 content results in a rise in the apparent Curie temperature as well as the maximum dielectric permittivity. The Pb(Ni1/3Nb2/3)O3-rich perovskites (x < 0.8) possess the characteristics of relaxor ferroelectrics. With increasing PbZrO3 content, the dielectric response gradually becomes less diffuse and dispersive, reflecting a reduction in the relaxor characteristics of the formed perovskites.

Equal-channel angular (ECA) pressing is a procedure having the capability of introducing an ultrafine grain size into a material. Experiments were conducted to examine the effect of the low stacking fault energy in pure Cu on microstructural development during ECA pressing at room temperature. The results show that the low 0stacking fault energy and the consequent low rate of recovery lead to a very slow evolution of the microstructure during pressing. Ultimately, a stable grain size of −0.27 μm was established in pure Cu but the microstructure was not fully homogeneous even after pressing to a total strain of ∼10. It is shown by static annealing that the as-pressed grains are stable up to ∼400 K, but at higher temperatures there is grain growth. These results lead to the conclusion that a low stacking fault energy is especially favorable for the introduction of an exceptionally small grain size using the ECA pressing procedure.

Formation of TiSi2 on nitrogen ion implanted (001)Si has been investigated. Nitrogen ion implantation was found to suppress the B and As diffusion in silicon. For Ti on 30 keV BF2+−20 keV N2+ and 30 keV As+−20 keV N2+ implanted samples, a continuous low-resistivity TiSi2 layer was found to form in all samples annealed at 700–900 °C. For Ti on 1 ×1015/cm2 N2+ 1- and As+ implanted samples, end-of-range defects were completely eliminated in all samples annealed at 700–900 °C. The results indicated that with appropriate control, N+-implantation can be successfully implemented in forming low-resistivity TiSi2 contacts on shallow junctions in deep submicron devices.

X-ray diffraction and microstructural studies were carried out on 2 : 17 type Sm–Co alloys containing Fe, Cu, and Zr (13–14 at.% Sm, 57–60 at.% Co, 20–22 at.% Fe, 4 at.% Cu, and 3 at.% Zr) in as-cast and heat-treated conditions. Microstructural studies revealed that the as-cast alloys contain three phases. It was observed that the samples subjected to sintering at 1463 K for 45 min followed by a solution treatment at 1448 K for 1 h resulted in nearly a single-phase, rhombohedral crystal structure (Th2Zn17-type). Subsequent isothermal aging at 1123 K and ramp-cooling to 673 K resulted in a mixture of Sm2Co17- and SmCo5-type phases with the former as major phase. It was also found that samples (Sm > 13 at.%) sintered at temperatures >1463 K showed incipient melting and multiphase formation.

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.

Precise and accurate knowledge of the optical properties of aluminum nitride (AlN) in the ultraviolet (UV) and visible (VIS) regions is important because of the increasing application of AlN in optical and electro-optical devices, including compact disks, phase shift lithography masks, and AlN/GaN multilayer devices. The interband optical properties in the vacuum ultraviolet (VUV) region of 6–44 eV have been investigated previously because they convey detailed information on the electronic structure and interatomic bonding of the material. In this work, we have combined spectroscopic ellipsometry with UV/VIS and VUV spectroscopy to directly determine the optical constants of AlN in this range, thereby reducing the uncertainty in the preparation of the low-energy data extrapolation essential for Kramers–Kronig analysis of VUV reflectance. We report the complex optical properties of AlN, over the range of 1.5–42 eV, showing improved agreement with theory when contrasted with earlier results.

Nickel hydroxide powders currently used in the positive electrode of nickel-metal hydride (Ni–MH) batteries require cobalt or cobalt oxides to make them viable and attractive. As a step to eliminate the cobalt-containing materials, spherical nickel hydroxide powders coprecipitated with Zn(OH)2 were prepared by a spraying technique. These powders, which have a higher tapping density and a much smaller pore volume than conventional powders, were used as the active materials of nickel hydroxide electrodes. The effects of the Zn(OH)2 additions on the electrode properties, such as percentage utilization and cycle life, were studied, and the relationship between the electrode performance and the formation of γ–NiOOH was investigated. The cycle life was increased because there was less electrode swelling due to much reduced formation of γ–NiOOH.