Dislocations have been observed in deformed Cu/Nb nanolayer composites of wavelength 17 and 7 nm. The dislocations thread through the Cu/Nb interfaces even though there is a change of Burgers vector. Conventional and high resolution transmission electron microscopy studies show that the in-plane bowing direction of these dislocations in the Cu layers is opposite to that in the Nb layers, so that the dislocations appear to zig-zag. These observations are explained by the presence of residual tensile stresses in Cu and residual compressive stresses in Nb, which make dislocations bow in opposite directions in the alternating layers.

The effects of gravity on the crystal nucleation of heavy metal fluoride fibers have been studied in preliminary experiments utilizing NASA's KC-135 reduced gravity aircraft and a microgravity sounding rocket flight. Commercially produced fibers were heated to the crystallization temperature in normal and reduced gravity. The fibers processed in normal gravity showed complete crystallization while the fibers processed in reduced gravity did not show signs of crystallization.

In this work the properties of polycrystalline silicon layers obtained by rapid thermal annealing have been discussed. Amorphous silicon layers with thickness of 3000 Å have been deposited on silicon wafers in rf sputtering system. The layers were annealed for 15 s to 5 min at temperatures in the range 800–1200 °C in vacuum 5 × 10−5 Torr. A correlation was established between structure, morphology, sheet resistance, and the parameters of the RTA annealing.

The microstructure of rapidly solidified Ti3Al−2Nb alloy consists of an ordered orthorhombic α″0 phase. In the foil samples for transmission electron microscopy prepared by chemical thinning, the α″0 → β0 transformation took place due to the charging of hydrogen during thinning. The β0 → α″0 transition in the rapidly solidified alloy can be explained by a shape deformation mechanism, and the β0/α″0 interface (habit) plane is near to {334}β0. The orientation relationships between the β0 and α″0 phases are , and .

RuO2 thin films have been produced on silicon-based substrates by in situ pulsed laser deposition for the first time. The electrical properties, the surface characteristics, the crystalline structure, and the film-substrate interface of deposited samples have been investigated by 4-probe resistance versus temperature technique, scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray diffraction, and transmission electron microscopy, respectively. The films show good electrical properties. The RuO2-substrate interface is very thin (≈3 nm), since it is not degraded by any annealing process. These two characteristics render our films suitable to be used as electrodes in PZT-based capacitors.

The orientational crossover phenomena in a radio-frequency (rf) sputtering growth of TiN films were studied in a real-time synchrotron x-ray scattering experiment. Following the initial random nucleation and growth stage, the growth was dominated by the grains with the (002) planes aligned with the substrate surface. Surprisingly, at later stages, the grains with the (002) growth front tilted away from the surface by about 60° became dominant. The tilting of the growth front resulted in a faceted surface topology that was confirmed by an ex situ AFM study. Our x-ray results suggest that the crossover was driven by the competition between the surface and the strain energy

Sintering of a fine cubic boron nitride (cBN) particle with a grain size of less than 2 μm was successfully carried out under 5.5 GPa pressure at 1720 K for 30 min. TiN–TiB2-coated cBN particles were used as the starting powder without adding any other binding materials. The coating was carried out by dipping the cBN particles in molten salts. The obtained cBN sintered compact shows a smooth microstructure with a well-controlled grain boundary; TiN–TiB2 is distributed over the cBN-grain boundary in the shape of a net mesh similar to tiled floors. The Vickers microhardness of the obtained compact was found to be higher than that of commercially available typical cBN-cutting tools.

Differential thermal analysis, in air and argon, in concert with x-ray diffraction, was performed on 2- and 3-component mixtures of Al, B2O3, and TiO2, to foster an understanding of the reaction path involved in the TiB2-forming thermite reaction. In argon, aluminum reacted with B2O3 to form elemental boron, and reacted with TiO2 to form AlTi3. These two products reacted just after boron was made available at ∼1060 °C to form TiB2. Formation of Al18B4O33 by reaction between B2O3 reactant and Al2O3 product attenuated the yield of TiB2, but facilitated its formation by extraction of Al2O3 reaction barriers.

Planar defects were observed in a hot isostatically pressed Al–Cu–Fe alloy. The defects were determined to be perpendicular to the fivefold direction. They were also found to be regions where the quasiperiodicity in the five-fold direction was disrupted, resulting in a periodicity along this direction of 1.06 nm. The defects were stable up to approximately 750 °C. The defects were determined to be formed by the applied shear forces associated with the consolidation process. The displacement vector of the defects was determined to be in a twofold direction perpendicular to the periodic direction.

Al2O3−34 wt.% TiC ceramics have been machined with a KrF (248 nm) excimer laser under normal atmosphere. In the initial steps of the irradiation process both the roughness and the removal rate present a strong variation with the number of pulses. After approximately 200 pulses the process reaches a stationary regime where the roughness and the removal rate become constant. Characterization of the machined areas by scanning electron microscopy showed that the variations in roughness and removal rate are related to the evolution of the surface topography of the samples. Also, as a consequence of laser irradiation, TiC and Al2O3 are partially transformed into TiO2, TiC0.7N0.3, and an Al–Ti solid solution.

Nd1+xBa2−xCu3O6+d (Nd123) single crystals have been successfully grown by the top-seeded solution-growth method. Compositions of Nd123 could be controlled by applying two different methods: control of the oxygen partial pressure of the atmosphere and control of the liquid composition in air. The critical temperatures of Nd123 obtained by these two methods were 96 K (oxygen control) and 95 K (liquid composition control), respectively. The relationship between the peak effect in the Jc-H curve and heat treatment was investigated. The peak effect was found not to be an intrinsic property of Nd123; consequently it could be controlled by heat treatment.

We discuss the magnetic properties of lead doped Bi-2223 bulk samples obtained through combined magnetic melt texturing and hot pressing (MMTHP). The ac complex susceptibility measurements are achieved over a broad ac field range (1 Oe < hac < 100 Oe) and show highly anisotropic properties. The intergranular coupling is improved in the direction perpendicular to the applied stress and magnetic field direction, and an intragranular loss peak is observed for the first time. A comparison is made with other bismuth-based compounds and it is shown that the MMTHP process shifts the ac irreversibility line (ac IL) toward higher fields. It is also shown that all the ac IL's for quasi 2D bismuth-based compounds show a nearly quadratic temperature dependence and deviate therefore strongly from the linear behavior observed in quasi 3D compounds and expected from a critical state model.

Melt textured single crystals of YBa2Cu3O6.5 (123) superconductors were produced by isothermal solidification from a semisolid melt using single crystal NdBa2Cu3O6.5 or SmBa2Cu3O6.5 seeds. The microstructure within the single crystals shows an inhomogeneous segregation of Y2BaCO5 (211) particles trapped in the 123 crystals during solidification. The concentration of 211 particles varies with the crystal axes in 123 crystals produced from precursors with compositions of 80 wt.% 123 powder and 20 wt.% excess 211. The 211 particle concentration along the c-axis in the crystal is much lower than that along the a- or b-axes during initial crystallization. This concentration increases in both directions as the crystal grows larger. The 211 concentration along the c-axis increases more quickly than the concentration along the other axes during solidification, which allows the 211 concentration to approach that on the other axes as the solidification continues. 211 particle segregation in stoichiometric 123 samples formed “X”-shaped tracks instead of the variations in 211 concentration described above. A single crystal growth model of 123 is proposed and employed to interpret these experimental observations. Quenched samples were prepared to investigate the volume fraction of 211 particles in the liquid phase. A constant distribution of 211 particles was observed in the liquid, except very near the crystal interface, where the 211 concentration decreased rapidly. Copper oxide content in the liquid was also measured. It is found that the copper content is lower at the (001) interface compared with (100) or (010) interfaces.

A simple melt-infiltration processing route has been developed for the fabrication of TiC/Ni3Al ceramic/intermetallic composites, which involves a combination of infiltration and subsequent liquid phase sintering. For Ni3Al contents from 8 to 25 vol. %, densities in excess of 98% of theoretical are readily obtained when processing at 1450 °C. TiC and Ni3Al are the only phases detected in the densified materials. Ni3Al ductility is retained after processing, leading to the possibility of ductile phase toughened TiC composites for elevated temperature applications (up to ∼1100 °C).

Pb(ZrxTi1−x)O3 and PbZrO3 heteroepitaxial thin films were produced in an aqueous solution (10 M KOH) at ambient pressure and low temperatures (90–150 °C) on (001) SrTiO3 and LaAlO3 single crystal substrates. Growth of the Pb(ZrxTi1−x)O3 and PbZrO3 thin films initiates by the formation of {100} faceted islands. Energy dispersive spectroscopy (EDS) analysis of the Pb(ZrxTi1−x)O3 thin film shows that the Zr: Ti ratio is 45: 56, nearly identical to the molar ratio of the precursors. This route might provide a viable low temperature alternative for the formation of high dielectric constant thin films for applications such as dynamic random access memory (DRAM).

Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) investigation of tetracyanoquinodimethane (TCNQ) and the related C60-TCNQ thin films is presented. Periodic molecular chains of the TCNQ on highly oriented pyrolytic graphite (HOPG) substrates were imaged, which demonstrated that the crystalline (001) plane was parallel to the substrate. For the C60-TCNQ thin films, we found that there were grains on the film surface. STM images within the grain revealed that the well-ordered rows and terraces, and the parallel rows in different grains were generally not in the same orientation. Moreover, the grain boundary was also observed. In addition, AFM was employed to modify the organic TCNQ film surface for the application of this type of materials to information recording and storage at the nanometer scale. The nanometer holes were successfully created on the TCNQ thin film by the AFM.

Ferroelectric thin films of Pb(Zr, Ti)O3 (PZT) were fabricated on platinum-coated silicon using the process of direct-current glow discharge assisted laser deposition, where the substrate was electrically grounded. The films deposited at 730 °C with +800 V discharge voltage are oriented mostly with the c-axis perpendicular to the substrate surface, and exhibit good ferroelectric hysteresis loops. A possible mechanism for the improvement of the deposition process has been proposed.

The ordering structure of lanthanum-substituted Ba(Mg0.33Ta0.67)O3 was investigated using x-ray diffraction. It was observed that the ordering type of this solid solution transformed from 1: 2 to 1: 1 with 10 mol% substitution of La(Mg0.67Ta0.33)O3. These two types of ordering coexist over a wide range of composition. This coexistence of ordering types was considered as phase coexistence and its physical origin was investigated using microwave measurements. Based on the intensity of superlattice reflections and the discontinuity in dielectric properties, it was suggested that the coexistence of two ordering types originates from the overlap of the two stability regions.

Lead zirconate titanate powders are derived from a novel aqueous-based citrate-nitrate/oxynitrate sol-gel combustion process. Aqueous solutions of metal nitrates or oxynitrates are transformed into gels with citric acid under heating. The received gels undergo a self-propagating combustion reaction on heating to 180 °C and subsequently yield voluminous ashes. These ashes form single phase perovskite Pb(Zr0.53Ti0.47)O3 powder with a specific surface area of 8 m2/g upon calcination at 550 °C. The ashes show a homogeneous distribution of lead, zirconium, and titanium ions which guarantees short diffusion paths in solid state formation of PZT perovskite. The redox behavior of the gels was studied with the help of DTA experiments. Powders are characterized in terms of XRD, SEM, and EDX analysis.

We demonstrate that the formation temperature of the C54 TiSi2 phase from the bilayer reaction of Ti on Si is lowered by approximately 100 °C by placing an interfacial layer of Mo or W between Ti and Si. Upon annealing above 500 °C, the C49 TiSi2 phase forms first, as in the reaction of Ti directly on Si. However, the temperature range over which the C49 phase is stable is decreased by approximately 100 °C, allowing C54 TiSi2 formation below 700 °C. Patterned submicron lines (0.25−1.0 μm wide) fabricated without the Mo layer contain only the C49 TiSi2 phase after annealing to 700 °C for 30 s. With a Mo layer less than 3 nm thick between Ti and Si, however, a mixture of C49 and C54 TiSi2 was formed, resulting in a lower resistivity. The enhanced formation of the C54 TiSi2 is attributed to an increased density of nucleation sites for the C49-C54 phase transformation, arising from a finer grained precursor C49 phase.