Nd2−xCexCuO4 (x = 0 to 0.15) thick films were grown directly on LaAlO3 substrates and surface-oxidized Ni tapes by fast liquid-phase processing methods. The films had a smooth surface and a very good biaxial texture, with the full width at halfmaximum equal to 0.8° and 5° on LaAlO3 substrates and surface-oxidized Ni tapes, respectively. Films of thickness of 5–15 μmm were grown at rates in excess of 2 μm/min. Nd2−xCexCuO4 has a good lattice and thermal-expansion match to rare-earth Ba2Cu3O7−δ (REBCO), minimum reaction with the high-temperature CuO:BaO solutions, and is nonpoisoning to superconductivity. It is an ideal buffer for liquidphase expitaxy processing of REBCO thick films.

It is well known that plastic deformation induced by conventional forming methodssuch as rolling, drawing or extrusion can significantly increase the strength of metalsHowever, this increase is usually accompanied by a loss of ductility. For example, Fig.1 shows that with increasing plastic deformation, the yield strength of Cu and Almonotonically increases while their elongation to failure (ductility) decreases. Thesame trend is also true for other metals and alloys. Here we report an extraordinarycombination of high strength and high ductility produced in metals subject to severeplastic deformation (SPD). We believe that this unusual mechanical behavior is causedby the unique nanostructures generated by SPD processing. The combination ofultrafine grain size and high-density dislocations appears to enable deformation by newmechanisms. This work demonstrates the possibility of tailoring the microstructures ofmetals and alloys by SPD to obtain both high strength and high ductility. Materialswith such desirable mechanical properties are very attractive for advanced structuralapplications.

The chemical durability of crystalline matrices loaded with actinides can be stronglyreduced when α-decays generate enough disorder to induce a crystalline to amorphoustransition. The alpha decay of actinides in SrTiO3 (α-recoils and α-particles) was simulated using Pb and He irradiation. This study shows that the He-ion annealingprocess that operates in some apatitic structure is negligible in SrTiO3 where thedisorder evolution at room temperature has a strong sigmoid dependence on dose. Thedirect-impact/defect-stimulated model, the cascade quenching/epitaxial recrystallizationmodel, and a direct-impact/cascade-overlap model were used to reproduce the SrTiO3-disorder evolution under Pb-ion irradiation.

Microcrystalline Cr-O-C films, synthesized by the plasma immersion ion processing technique, were annealed in vacuum and air at 700 °C for different times so their thermal stability could be evaluated. The study showed that annealing does not greatly change the chemical composition of the Cr–O–C films but induces a transformation ofthe film structure from the mixed phases of Cr2O3, CrO2, and CrC1.13O0.12 to the dualphases of Cr3C2, and Cr2O3. In addition, the annealed Cr–O–C films exhibit excellentnonwetting qualities to liquid aluminum despite the presence of pin holes. The contactangle of resolidified molten aluminum against the Cr–O–C films was found to be ashigh as 120–150°. The aluminum contact angle was found not to vary with thermal aging of the Cr–O–C films. The Cr–O–C films showed high hardness (16–24 GPa) and good wear resistance as compared to the steel substrates (H13 and 304 stainless steels)used in this study.

To estimate the effect of the spherical interface of the T-type joint structure on bonding strength, thermal residual stress on the outer surface and in the interface were investigated by thermal elastoplastic finite element analysis, in terms of principal stress and principal axis direction. These numerical results were compared with experimental fracture patterns and the tensile strength. The relationship between the maximum principal stress around the interface edge and the joint angle was studied. As a result,an optimal joint angle was shown by the experimental data and also by the principal stress calculated.

Ferroelectric SrBi2Ta2O9 (SBT) thin films and Bi2O3 interfacial layers were depositedonto the Pt/Ti/SiO2/Si substrates via liquid-delivery metalorganic chemical vapordeposition. The SBT films with a 5-nm-thick Bi2O3 interfacial layer were well crystallized without c-axis orientation, even at deposition temperature of 540 °C and showed a stronger (115) orientation than those without a Bi2O3 layer with increasing annealing temperature. The remanent polarizations of SBT films with Bi2O3 interfacial layer were significantly improved in comparison with those without Bi2O3 layer. The remanent polarization (2Pr) and coercive field (Ec) of SBT films without and with aBi2O3 interfacial layer annealed at 750 °C were 12 and 21 μC/cm2 and 60 and38 kV/cm, respectively, at an applied voltage of 5 V.

We have analyzed Tb L3-edge x-ray absorption near-edge structure spectra of Tb-doped phosphor compounds for plasma display panel applications. Intensity and lifetime of the green emission from the Tb3+:5D4→7F5 transition were measured with respect to nominal terbium concentration in the host compounds, i.e., YBO3, YPO4,and Y4Al2O9, all of which were made through the solid-state reaction. Typical concentration quenching was evident on the fluorescence intensity and the fluorescing level lifetime in our samples. From the analyses of white line absorption peaks at TbL3-edge, it was verified that terbium is essentially trivalent in all the samples, even invery highly concentrated ones. Thus, this implies that the concentration quenching was not caused by presence of mixed-valent states of terbium. Instead, it is believed that anonradiative energy transfer route among Tb3+ ions might be responsible for thebehavior.

This paper reports on a study of stress in thin silicon plates sectioned from wafers by a near-infrared transmission technique. Phase stepping was incorporated to determine the magnitude and orientation of stress from fractional birefringence fringe images. The anisotropic relative optic-stress coefficient of (100) silicon was determined and the limitation of the stress orientation measurement is discussed.

Interfacial phase and microstructure, solder hardness, and joint strength of Sn–3.5Ag–X (X = Cu, In, Ni; compositions are all in wt% unless specified otherwise) solder alloys were investigated. Considering the melting behavior and the mechanical properties, five compositions of Sn–3.5Ag–X solder alloys were selected. To examine the joint characteristics, they were soldered on under bump metallurgy isothermally at 250 °C for 60 s. Aging and thermal cycling (T/C) were also performed on the solder joint. The interfacial microstructure of the joint was observed by scanning electron microscopy. X-ray diffraction and energy dispersive x-ray analyses were made toidentify the type of solder phase and to measure compositions. Excessive growth of an interfacial intermetallic layer in the Sn–3.5Ag–6.5 In solder joint led to a brittle fracture. In the other four solder joints, ductile fractures occurred through the solder region and the solder hardness was closely related with the joint strength.

The joining of a Ti3SiC2 ceramic with a Ti–6Al–4V alloy was carried out at the temperature range of 1200–1400 °C for 15 min to 4 h in a vacuum. The total diffusion path of joining was determined to be Ti3SiC2/Ti5Si3Cx/Ti5Si3Cx + TiCx/TiCx/Ti. The reaction was rate controlled by the solid-state diffusion below 1350 °C and turned to the liquid-state diffusion controlled with a dramatic increase of parabolic rate constant Kp when the temperature exceeded 1350 °C. The TiCx tended to grow at the boundarywith the Ti–6Al–4V alloy at a higher temperature and longer holding time. TheTi3SiC2/Ti–6Al–4V joint is expected to be applied to implant materials.

We have examined electrochemical properties and thermal stability of the amorphous Mg67Ni28Pd5 alloy produced by melt-spinning subjected to electrochemical hydrogen charge. In the cyclic life test, the discharge capacity of the alloy increases significantly with increasing cycle number and reaches 411 mA h/g at the 15th cycle. Thehydrogen-absorbed amorphous alloy crystallizes through two stages of primarycrystallization of Mg2Ni, followed by precipitation of Mg2NiH4 at the second stage.The completed crystallization temperature of the hydrogen-absorbed alloy increases by 65 K as compared with the as-solidified one. It is thus concluded that stability of theMg-based amorphous alloy against crystallization increases by hydrogen absorption.

High-strain-rate superplastic behavior of powder-metallurgy processed 0%, 10%, 20%,and 30% SiC particulate reinforced 6061 Al composites was studied over a range of temperatures from 430 to 610 °C. The strength of the 6061 Al composites was lowerthan that of the 6061 Al matrix alloy in the temperature range where grain boundarysliding is believed to control the plastic flow. The difference in their strength was alsoobserved to be temperature dependent, increasing with increase in temperature.Abnormally high activation energy for superplastic flow was another important featureof the 6061 Al composites. These behaviors in particle weakening and activationenergy have strong resemblance to those noted in the high-strain-rate superplastic 2124Al composites studied previously. The observed particle weakening was attributed toliquid-enhanced superplastic flow and discussed by adopting the concept of effectivediffusivity considering mass flow through liquid phase formed at the solute-segregatedregion near SiC/Al interfaces.

The negative transverse magnetoresistance of boron-doped graphite at liquid-nitrogen temperature has been studied in detail using 3000 °C-treated Grafoil(commercially available graphite foil), with the measurements of interlayer spacingd002 at room temperature, the Hall coefficient and electrical resistivity at liquid-nitrogen temperature, and temperature dependence of the resistivity in a temperature range 1.7–273 K. The negative transverse magnetoresistance can be measured for the specimens with hole carriers having the Fermi energy lower than −0.07 eV, estimatedby the Slonczewski–Weiss–McCure (SWMcC) band model using the Hall coefficient data. Characteristic feature of the negative transverse magnetoresistance has been investigated in terms of the SWMcC band model and a weak localization theory obtained by extending Kawabata's theory.

Fine needlelike crystals of C60 have been formed by a liquid–liquid interfacial precipitation method which uses an interface of the concentrated toluene solution of C60/isopropyl alcohol. The needlelike crystals of C60 with a diameter of submicrons (“C60 nanowhiskers”) were found to be single crystalline and composed of thin slabswith a thickness of about 10 nm. The intermolecular distance of the C60 nanowhiskerswas found to be shortened along the growth axis as compared with the pristine C60crystals, indicating a formation of strong bonding between C60 molecules. TheC60 nanowhiskers are assumed to be polymerized via the “2 + 2” cycloaddition inthe close-packed [110]c direction.

Prediction of density–time curves, i.e., using the sintering curves for one green density to predict those of another during isothermal sintering, was demonstrated for 3 mol% yttria-stabilized zirconia and titania, as well as for data from the literature on various ceramic powder compacts. The predictions utilized only a median green pore size term as the scaling parameter for densification rates between samples of different green densities. Despite the simplicity of the approach, the resulting predictions of density–time curves were in relatively good agreement with the measured data.

The behavior of steps on the basal surface of alumina under conditions of evaporativemass transport has been investigated. Steps on a clean surface of alumina tend to be uniformly spaced indicating a repulsive interaction between the steps. The presence of foreign particles causes step bunching that leads to the formation of a new facet. The lower energy of the macrofacet may provide a driving force for the bunching process.

The atomic layer deposition technique was used to deposit TaN thin films from TaCl5 and TaBr5 and tert-butylamine or allylamine as a reductive nitrogen source with and without ammonia. The films were characterized with time-of-flight elastic recoil detection analysis, energy-dispersive x-ray spectroscopy, x-ray diffraction, and the standard four-point probe method. The films deposited from tert-butylamine and ammonia with both tantalum precursors had reasonably low halide contents. When allylamine was used as a nitrogen source, on the contrary, the films contained larger amounts of chlorine and other impurities. The resistivity increased markedly as the deposition temperature was decreased. The lowest resistivities (below 1500 μΩ cm) were obtained when the films were deposited from TaCl5 or TaBr5 with tert-butylamine at 500 °C.

Sol-gel-derived metal oxide ceramic thin films deposited onto amorphous iron-rich substrates were found to form self-organized nanoporous structures dependent upon the extent to which the substrate is de-alloyed, a function of the substrate alloycomposition, acid concentration of the sol, and film drying conditions. Field emission scanning electron microscopy, transmission electron microscopy, and x-ray energy dispersive analysis were used to investigate details of the porous structure formation.Our studies showed the more electrochemically active elements in the amorphous substrate are de-alloyed by the sol in high-humidity environments, whereupon the liberated elements form oxides replicating the de-alloyed substrate matrix resulting in athree dimensional porous network structure.

The diffuse dielectric anomaly observed in the temperature range of 400–700 °C was investigated in MnO2-doped Pb0.9La0.1TiO3 ceramic. The frequency and the temperature dependence of the dielectric relaxation behavior in the diffuse dielectric anomaly were analyzed with the modified Debye equation. The dielectric relaxation strength was considered an important fitting variable in the modified Debye equation. The temperature-dependent behavior of the diffuse dielectric anomaly was successfully described by introduction of the exponential decay form for the relaxation strength inthe modified Debye equation.

A novel photochromic complex composed of Keggin-type tungstophosphate acid (PW12) and polyacrylamide (PAM) was prepared. Atomic force microscopy (AFM), thermogravimetric study, Fourier transform infrared spectra (FTIR), ultraviolet–visiblea bsorption spectra (UV-VIS), and electron resonance spectra (ESR) were used to investigate the surface topography, composition, and photochromic behavior and mechanism of the film. Under UV irradiation, the film was reduced photochemically to yield a blue species. AFM images indicated that surface topography of the polymer matrix changed after adding PW12. FTIR results showed that the Keggin geometry of PW12 was still preserved inside the matrix, and a charge-transfer bridge was built between PW12 and PAM by hydrogen bonding. The characteristic signal of W (V) and the formation of a radical signal in ESR spectra indicated that PAM was a hydrogen donor and the photoreduced process was in accordance with the radical mechanism.The diffusion of oxygen in the polymeric network plays an important role in the reversibility of photochromism.