Epitaxial thin films of LaVO3 were grown on (001) LaAlO3 substrates by pulsed laser deposition from a LaVO4 target in a vacuum ambient at substrate temperatures ≥500 °C. X-ray diffraction studies showed that epitaxial LaVO3 films consist of mixed domains of [110] and [001] orientations. Thermoprobe and four-probe conductivity measurements demonstrated the p-type semiconducting behavior of the epitaxial LaVO3 films. The temperature dependence of the conductivity is consistent with a thermally activated hopping mechanism with an activation barrier of 0.16 eV.

Relationships between melt heat treatment and undercooling of alloy melts were clarified with Bi95Sb5 through four-factor, three-level orthogonal experiments. The results show that the cooling rate plays the most important role in the undercooling of Bi95Sb5 alloy melts. Undercooling as large as 121 K was obtained in the bulk Bi95Sb5 alloy melt. It is presently the highest undercooling of this alloy system. A metastable phase with tetragonal structure was found in the Bi95Sb5 alloy with undercooling of 121 K.

The average dislocation velocity in hydrogenated Ni3Al single crystals was directly measured as a function of resolved shear stress (RSS) at room temperature (293 K) by the etch-pit technique. It was found that the dislocation velocity with hydrogen is about 5–25 times faster than that without hydrogen for the same RSS, and hydrogen decreases activation energy for dislocation motion in Ni3Al single crystals. The reason hydrogen can enhance dislocation velocity in this compound is briefly discussed. These preliminary results quantitatively provide the first evidence of hydrogen-enhancing dislocation mobility in Ni3Al material.

Self-propagating high-temperature synthesis (SHS) has been successfully developed for the fabrication of cellular NiTi intermetallic compounds, which have an open cellular structure with about 60 vol% porosity and more than 95% open-porosity ratio. The SHS reactions lead to the formation of TiNi, Ti2Ni, Ni3Ti, and Ni4Ti3 intermetallics. The SHS process can be controlled by regulating the preheating temperature, which has effects on the phase amount and the shape as well as macrodistribution of pores in the products.

A 3-μm-thick Fe–Ni alloy thin film was deposited on a 0.2-mm-thick low-carbon steel substrate by radio-frequency magnetron sputtering, and the properties of the film were investigated. The film exhibits a columnar growth structure and a fiber texture with the relationship of (110)film//(111)substrate. A thermal cycle test showed good adhesion between the film and the substrate. Most importantly, the Fe–Ni alloy deposition results in a significant reduction in thermal expansion of the whole specimen. These results suggest that a properly deposited Fe–Ni alloy film could be applied to a low-carbon steel sheet to significantly reduce its thermal expansion. Such reduced thermal expansion would enhance the image resolution of a shadow mask made of a low-carbon steel sheet.

In the process of developing electro-optic devices from ferroelectric z-cut LiNbO3 wafers, a repolarization throughout the wafer thickness occurs due to a localization of electric charges on the wafer. The repolarization not only generates microdomains causing light to scatter but also large defects in the crystal that become the origin of wafer fracture. The size of such defects is comparable to the wafer thickness (0.5 mm), and an anomaly in the chemical and crystalline structures can be found in them. X-ray diffractometry and x-ray photoelectron spectroscopy confirm that a chemical reduction in the defective region occurs.

The optical transparencies and electrical conductivities of thin films of In2O3 mixed with ZrO2 have been investigated. These films were deposited on glass substrates at room temperature using pulsed-laser deposition. Indium–zirconium oxide films with a ZrO2 content up to a 15 wt% were conducting and more than 80% transparent from 450 to 700 nm. As the ZrO2 content increased from 0 to 15 wt%, the electrical resistivities increased from 1.28 × 10−3 to 6.48 × 10−2 Ω cm, the carrier densities were decreased from 2.14 × 1020 to 1.0 × 1018/cm3, and the Hall mobilities decreased from 21 to 5 cm2 V−1 s−1, all monotonically.

Nanocrystalline-diamond particles were produced in the form of a coating by depositing Ni-clad graphite powder in a high-velocity thermal spray experiment. Particles were accelerated to impact and formed a thick film (>20 μm) on a steel substrate, with the high-velocity impact generating a shock wave, which propagates through the particle and the underlying deposits. Transmission electron microscopy revealed that this deposit contains cubic diamond nanocrystals having a size range of 5 to 10 nm in graphite. In addition to diamond, it was observed that a portion of the deposit contains “closed-curved graphite.”

Due to growth tensile stress, which evolves in diamond films during deposition, thick diamond films are easily cracked. In this study we successfully prevented growth cracks by introducing thermal compressive stress with step-down control of deposition temperatures during growth. Three deposition temperature drops of 10 °C each during deposition enabled us to successfully synthesize crack-free four-inch diamond wafers several hundred micrometers in thickness. This method is very simple and may be applicable to coating of films of various materials different from those of substrates.

A large, single-grain Nd–Ba–Cu–O (NdBCO) composite consisting of superconducting NdBa2Cu3O7-δ containing nonsuperconducting Nd4Ba2Cu2O10 phase inclusions was fabricated up to 2 cm in diameter using a top-seeded melt-textured growth technique. A MgO single-crystal seed was used to provide a heterogeneous nucleation site at the center of a presintered pellet heated above its peritectic temperature and cooled continuously in a conventional tube furnace in reduced oxygen partial pressure. This process produces individual grains with the c axis oriented at ≈10° to the seed surface which, from vibrating-sample magnetization measurements, exhibit a pronounced peak effect in their magnetic moment over a wide temperature range (50–90 K) when the supercurrent flows in the a-b planes. A very high irreversibility field (>9 T at 77 K) is also observed in these grains for field applied both perpendicular and parallel to the crystallographic c axis which is significantly greater than that observed in good-quality melt-processed Y–Ba–Cu–O. These results underline the potential of NdBCO for high-field engineering applications.

Neutron powder diffraction methods with Rietveld analysis are utilized to determine GaN lattice parameters from 15 to 298.1 K. Using these measurements and literature data, we calculated the thermal expansion of gallium nitride (GaN) and predicted its higher temperature thermal expansion. The results are compared with available experimental data and earlier work.

This paper presents an x-ray diffraction and transmission electron microscopy analysis of Al1−xInxAs grown by molecular beam epitaxy. Two samples grown on (001) InP at temperatures of 370 and 400 °C are characterized. The first, which contains a high density of twin lamellae, exhibits triple-period short-range ordering with a rather short correlation range normal to the (111) planes. Within these (individual) planes, the concentration, however, is uniform over a considerably greater distance, leading to a highly anisotropic scattering. This is the first observation of triple-period short-range ordering in a sample that exhibits 2 × 1 surface reconstruction. The second sample exhibits CuPt-type short-range ordering with scattering that is significantly streaked, suggestive of lamellar-shaped ordered domains. Both samples contain high densities of stacking faults leading to additional sharp streaking along symmetry-allowed 〈111〉 directions.

Nano-icosahedral phases were prepared by melt-spinning in the AlMnCe system (Al ≥ 89 at.%). Ce-induced structure alterations are reported by x-ray diffraction for the icosahedral (i) AlMnCe phase. They comprise apparition of superstructure diffraction lines, due to chemical ordering in the 6-dimensional icosahedral lattice, which gradually changes from a simple to a face-centered (FCI) type. Also, strong anomalies of diffracted intensities, with reference to model FCI phases, support Ce preferential location on a special set of sites. Microstructure investigations show a nanodispersion of i-AlMnCe in an Al-rich matrix, suggesting a low nucleation barrier of this metastable phase in the melt.

The effect of alloying additions of Ti and B on the process of micropyretic synthesis on NiAl and on the microstructure of the synthesized alloy was examined. It was observed that the combustibility of the quaternary alloy is good despite the presence of the alloying elements because of an additional combustion reaction between Ti and B. The microstructure of the quaternary alloy was found to consist primarily of the NiAl and Ti boride phases. The effect of preheating of the specimen prior to synthesis on the process of synthesis was also examined. It was observed that preheating not only can change the morphology of the phases but also influence the nature of the phases present in the alloy. The mechanism of the formation of the two phase microstructure during the synthesis from the elemental powders was established by stopping the combustion front and by carrying out a detailed microstructural characterization of regions around the stopped combustion front.

Cavitation was examined in an Al–Mg solid-solution alloy deformed in tension at 400 °C under conditions providing solute-drag creep, which can produce tensile ductilities from 100% to over 300%. Two nondestructive evaluation techniques were employed to measure the extent of cavitation: ultra-high-resolution x-ray computed tomography and pulse-echo ultrasonic evaluation. Subsequent to nondestructive evaluation, the sample was sectioned for examination by standard metallographic techniques. Metallographic examination confirmed that both nondestructive techniques accurately indicated the extent of cavitation. Ultrasonic testing provided a practical means of distinguishing material with cavities from that without cavities. Ultrahigh- resolution x-ray computed tomography provided an accurate three-dimensional image of internal cavitation.

The photoacoustic technique and the thermal relaxation method were used to determine the thermal conductivity of some representative samples obtained from an aluminumsilicon casting alloy A319. This material was solidified with an imposed unidirectional thermal gradient to obtain samples with different microstructures characterized by the secondary dendrite arm spacing, which increases as the solidification rate decreases. It was found that the thermal conductivity of the alloy decreases with an increase in the secondary dendrite arm spacing and a decrease in the integral dendrite perimeter.

This work deals with the measurement of pyrocarbon anisotropy on very thin fiber coatings used to control the interfacial behavior in carbon/carbon composites. Differentiation of the various pyrocarbons was performed through computerized image analysis of the electron diffraction patterns by measuring the azimuth opening of the carbon 002 diffraction arcs. This orientation angle decreases when the texture switches from rough to smooth laminar. The relationship with the polarized light measurement technique at a lower resolution is discussed.

Cobalt-chloride- and dextrose-containing silica gels were reduced in situ under nitrogen atmosphere in the temperature range of 600 to 950 °C. Analysis of kinetic data on the in situ reduction shows that, in the temperature range of 600 to 750 °C, the contracting geometry type and, in the temperature range of 800 to 950 °C, the nucleation and growth type of mechanisms remain operative. The shape and size of the reduced cobalt nanoparticles in the silica matrix was studied by examining the transmission electron micrographs of the reduced Co/SiO2 samples. The morphology of the reduced metallic particles was found to be influenced by the change in reduction mechanism.

Computer simulations have been designed to elucidate the evolution of microcracking in a nanocomposite using appropriate material values for alumina and silicon carbide. These are compared to a single-phase material using elastic and thermal expansion coefficients for alumina. It is found that the region and the fracture mode where microcracking ensues are determined by the intensity and the length scale of the residual stress fields, which interact. Of specific interest are the region, fracture mode, and length of ensuing microcracks for materials with different inclusion locations (at the grain boundary or within the grain) and with different grain size to inclusion size ratios.

Thin films of highly (100) textured fine-grain (lateral grain size ≅0.1 to 0.15 μm) PbZrxTi1−xO3 (PZT) (x = 0 to 0.7) were grown on conductive perovskite LaNiO3-buffered platinized Si substrates by metalorganic chemical vapor deposition. Domain configuration and crystalline orientation were studied using x-ray diffraction and transmission electron microscopy. The predominant domain boundaries of Ti-rich tetragonal-phase PZT and Zr-rich rhombohedral-phase PZT were found to be on the (110) planes and (100) planes, respectively. The equilibrium domain widths were observed and estimated numerically on the basis of transformation strain, grain size, and domain boundary energy. The peak value of the dielectric constant was 790 near the morphotropic boundary. Hysteresis behavior of these PZT thin films was demonstrated. A decrease in coercive field with the increment of Zr content was found; this variation was attributed to domain density and the multiplicity of polarization axes. Furthermore, the low leakage current (J ≤ 5 × 10−7 A/cm2 at V = 4 V) was observed for all samples, and the involvement of several possible conduction mechanisms was suggested.