Eu2CuO4 (ECO) has been used as a buffer layer for growing of Yba2Cu3O7–δ (YBCO) thin films on SrTiO3(100) and Y-stabilized ZrO2(100) substrates. The epitaxy, crystallinity, and surface of YBCO thin films have been significantly improved by using ECO buffer layer as investigated by x-ray diffraction, rocking curves, scanning electron microscope, surface step profiler, and x-ray small-angle reflection. The best value of the full width at half-maximum of the YBCO(005) peak can be greatly reduced down to less than 0.1°. The scanning-electron-microscope photos indicate a very smooth surface for the YBCO thin films. The average roughness is less than 5 nm over a wide scanning region of 2000 mm. The results of x-ray small-angle reflection indicate a very clear and flat interface between YBCO and ECO layers. Meanwhile, the resistivity of ECO is about 20 times higher than that of PrBa2Cu3Oy at the boiling point of liquid nitrogen. Our results suggest that ECO should be a good barrier candidate for fabricating high-Tc superconductor junctions.

The nucleation and growth of the c-axis-aligned Yba2Cu3Ox on SrTiO3 and CeO2, from precursor films, were studied by examining quenched and fully processed specimens using transmission electron microscopy techniques. The precursor films, a stoichiometric mixture of fine-grained Y, Cu, and BaF2, were deposited using physical vapor deposition methods. An Y-Ba oxy-fluoride formed from the precursor contributed to the nucleation of Yba2Cu3Ox, while a liquid layer between the unreacted precursor and the Yba2Cu3Ox layer played an important role in the growth of Yba2Cu3Ox. However, the process of nucleation of Yba2Cu3Ox on SrTiO3 and CeO2 were significantly different.

A new experimental technique for determining mechanical properties of polymer–metal interfaces was developed by replacing the conventional mechanical testing machine with a piezoelectric actuator. The actuator was made from a thin ferroelectric ceramic beam attached to a bilayer polymer-metal composite specimen. The trilayer specimen was loaded by applying ac electric fields on the piezoelectric actuator to drive crack growth along the polymer-metal interface. Subcritical crack growth was observed along the epoxy/aluminum interface, and the growth rate was found to depend on the magnitude of the applied electric field. The fracture mechanics driving force for the crack growth was computed from the finite element analysis as a function of crack length, applied field, material properties, and specimen geometry. Kinetics of the crack growth was correlated with the piezoelectric driving force.

A nanocomposite (Mg–V)nano made of 90 wt% Mg and 10 wt% V was prepared by high-energy ball-milling during 40 h. The activation characteristics of (Mg–V)nano are rather poor, the hydrogen content [H] reaching 4 wt% after more than 100 h (t4wt%) following the initial exposure of the material to H2. Adding 9 wt% graphite to (Mg–V)nano and resuming the milling operation for 30 min leads to the formation of (Mg–V)nano /G, which exhibits a t4wt% value of only 10 min. The addition of more than 9 wt% graphite to (Mg–V)nano does not lead to any significant reduction of the t4wt% value. However, extending the milling period with graphite over 30 min leads to a steady increase in t4wt% and, thus, to a deterioration of the activation characteristics. Comparison of the behavior of graphite with other C-based compounds revealed that perylene (C20H12) and pentacene (C22H14), which are made of linked benzene rings, and thus have a 2D structure similar to that of the graphene sheet, are as effective as graphite in improving the activation characteristics of (Mg–V)nano. A structural investigation of (Mg–V)nano /G as a function of the milling time through both C 1s core-level x-ray photoelectron spectroscopy and C K edge x-ray absorption near-edge spectroscopy has shown that the integrity of graphite is progressively lost as the milling period is extended over 30 min. On the basis of these results, it is hypothesized that the adsorption of graphene layer on freshly created Mg surfaces and the formation of highly reactive C species during milling prevents the re-formation of the surface oxide layer responsible for the poor activation characteristics of untreated (Mg–V)nano

Al alloys were infiltrated into alumina preforms without the aid of pressure in N2 as well as in air at and above 750 °C. It was possible to eliminate termination of infiltration that was seen in open conditions (where N2 was in continuous contact with the melt) by modifying the infiltration geometry. This configuration enables the infiltration to continue for longer periods of time, consequently producing greater thickness of composite. In air, Mg placed at the interface getters the in-coming oxygen until the alloy billet melts and seals off the front from the ingress of the furnace atmosphere thereby eliminating the need for prealloying Al with Mg and N2 atmosphere. In addition, experiments in argon revealed that the infiltration requires some critical amount of N2 in the atmosphere.

The microstructure and shear strength changes of SnAgCu/Cu and SnAgCu/Ni–P/Cu surface mount solder joints during thermal aging at 150 °C and thermal cycling between ?40 and 150 °C were investigated. The reaction rate between SnAgCu and Cu is higher than that between SnAgCu and Ni–P. After long aging time, the SnAgCu/Cu interface becomes the weakest region in the SnAgCu/Cu solder joint, whereas the shear-force-induced cracks in the SnAgCu/Ni–P solder joint appear at the interface of Ni–P/Cu. During thermal cycling, cracks develop in both solder joints and the shear strength decreases. After extensive thermal cycling, the Ni–P layer separates from the Cu substrate and the shear strength of the SnAgCu/Ni–P solder joint decreases drastically.

The in situ reduction method was used to prepare nanocrystalline PbSe in a poly(acrylic acid-co-styrene) matrix. Metal precursor-doped polymer film was treated with selenium and reducing reagent (NaBH4) in ethylenediamine, leading to the formation of assemblies of crystalline semiconductive PbSe in polymer. The preparation was done at room temperature and ambient pressure. X-ray diffraction, x-ray photoelectron spectroscopy, infrared, scanning electron microscopy, transmission electron microscopy, and ultraviolet-visible spectra were used to characterize the as-prepared materials. The key factor for successful preparation of this composite was also discussed.

The heterogeneous photocatalytic oxidation of rhodamine B in aqueous solution containing pure or zinc (iron)-doped titania films has been studied. N-deethylation of rhodamine B was accelerated by iron(III) and zinc(II) doping as compared with pure titania film. It is shown that improvement of electron transfer from dye molecules to the film may be responsible for the high N-deethylation rate for iron-doped (0.5 mol%) film, while for zinc-doped (20 mol%) film, high surface roughness may be the main reason. In addition, both iron and zinc doping brought a new shallow trap to the intragap meaning that the surface defects had increased after doping; this is a possible reason doped films present relative low photoreactivity to catalyze the direct degradation of dye molecules.

Silver nanoparticles (10–20 nm) embedded into silica thin films have been obtained through the use of a silver organometallic precursor compound dissolved in Spin-On-Glass and subsequently spinned onto suitable substrates. In this paper we present a study of the shape, size, and distribution of silver particles through the use of microscopes, x-ray diffraction, and optical extinction. It has been observed that the obtained films are stable for annealing up to 500 °C with a progressive degradation above this temperature. Furthermore it is possible to obtain high-density silver particles up to 15% in weight without affecting the cluster size and shape.

The effect of oxygen on the reaction mechanisms in the Si/Ta/Cu metallization system was studied experimentally and by utilizing the thermodynamically assessed Ta–O binary system. It was presented that an interfacial tantalum oxide was formed between Cu and Ta and that it established an additional barrier layer for Cu diffusion. The formation of additional barrier layer was supported by the following observations: (i) No detectable amount of Cu was found from the Ta layer with the combined transmission electron microscopy and energy dispersive spectroscopy at temperatures as high as 650 °C. (ii) Secondary ion mass spectrometry measurements indicated that significant amount of oxygen was incorporated into the films already after the sputtering stage. (iii) 181Ta16O molecular ion signals were detected from the Ta/Cu interface, indicating that the additional layer was in fact some form of tantalum oxide. The diffusion of Cu through the Ta layer could not proceed until the interfacial oxide had been dissolved by the Ta matrix. Since the oxygen solubility in Ta matrix is high in the temperature range of interest, the interfacial oxide dissolution was kinetically controlled. It is to be noted that the threshold temperature range of the dissolution reaction was found to coincide with that of the β–Ta to the bcc-Ta transition, which was anticipated to enhance the kinetics of the dissolution.

Initial growth features of Yba2Cu3Oy (YBCO) crystal on an MgO substrate by a liquid-phase epitaxy (LPE) process were investigated and compared with homoepitaxial growth on a YBCO substrate. The partial dissolution of the seed grains in the initial stage of the LPE growth was influenced by the crystallinity of in-plane alignment of the seed grains, which could be explained by the preferential dissolution and growth mechanism. Concurrently, the slope angle of the growth grain varied with growth time. The opposite tendency of the slope angle change between the hetero- and the homoepitaxial growth was observed and could be explained by considering the difference in the step-advancing rates on each interface. It could be understood that the formation of entrapped liquid inclusions was the combination phenomena of both the small step-advancing rate of YBCO crystal on the MgO surface and the roughening of the MgO surface due to the partial dissolution of MgO to the solution.

Microstructures of La1-xCaxMnO3 compounds (x = ⅓ and 0.5) prepared with and without intermediate grinding were studied using transmission electron microscopy. A high density of antiphase boundaries (APBs) with displacement vector 1/2 〈111〉, indexed in orthorhombic unit cell, has been observed in bulk samples with no or minimum intermediate grinding. The nature of this APB is analyzed and found to bedue to the symmetry breaking introduced by the tilting of MnO6 octahedra relative to the ideal perovskite structure. Samples prepared using two intermediate grinds do not show these defects indicating that the microstructure can be controlled through synthesis routes. The effect of domain boundaries on the colossal magnetoresistance effect is discussed.

The crystallization process of SrxBiyTa2O5+x+3y/2 thin films grown by metalorganic chemical vapor deposition was investigated. Phase formation and crystal growth is greatly affected by the film composition and crystallization temperature. Phase diagrams for varying Sr or Bi contents were determined as a function of the crystallization temperature. The higher the Sr or Bi content in the film, the lower the phase transition temperature from the amorphous to the fluorite-type phase and from the fluorite-type to the Bi-layered Aurivillius phase. Low Sr and Bi contents support pyrochlore-type phase formation as a second phase. During annealing, excess Bi is not lost due to evaporation, but due to migration to the bottom electrode. Contrary to the fluorite-type phase, the Aurivillius phase is not able to incorporate the excess of Bi atoms. Decreasing grain size and pyrochlore-type phase formation entail decreasing remanent polarization.

Nanoindentation is a technique commonly used for measuring thin film mechanical properties such as hardness and stiffness. In this study, we used the finite element method to investigate the effect of substrate and pileup on hardness and stiffness measurements of thin film systems. We define a substrate effect factor and construct a map that may be useful in the interpretation of indentation measurements when it is not possible to make indentations shallow enough to avoid the influence of the substrate on the measurements. A new technique for measuring mechanical properties of thin films by nanoindentation is suggested at the end of this article.

This paper reports a study of plasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD) as a suitable technique for depositing dense, crack-free thin layers of yttria-stabilized zirconia onto porous substrates, as a step in the fabrication of anode-supported planar solid oxide fuel cells (SOFC). Our objective is to present an alternative method by which an SOFC assembly may be fabricated at lower temperature than by conventional methods. PE-MOCVD using zirconium tertbutoxide (ZrTB) -and yttrium hexafluoroacetylacetonate dihydrate (Y6FA) is capable of producing the electrolyte in thin dense layers on smooth surfaces, as demonstrated for Si(110) wafers. If a porous substrate is used, the average surface pore size should not exceed 1–2 μm to obtain a dense film. The crystalline phase of the film was related to the Y6FA concentration in the gas phase using x-ray diffraction. Depth profiling, using x-ray photoelectron spectroscopy, showed that Y is present (fairly uniform) at all depths of the film. Growth rates are dependent on the applied power but independent of substrate temperature. Film density, however, shows a significant dependence on substrate temperature.

The alignment degree of sintered Nd–Fe–B magnets and its dependence on applied field and compacting mode were studied by magnetic force microscopy. By analyzing the magnetic force images to illustrate the magnetic-domain structure, an experimental method for quantitatively evaluating the alignment degree of sintered Nd–Fe–B magnets was given. The results show that if the compacting mode is the same, the alignment of magnets will be better as field increases. Under the same field, the alignment degree for rubber isostatic pressing with vibration is better than that for nonmagnetic metal die pressing. However, if the sample is compacted by rubber isostatic pressing without vibration, the alignment degree decreases significantly.

A polymer-coated glass fiber with a low-modulus coating at the ends is considered. The objective of the analysis is to find out if there is sufficient incentive to use such a dual coating system for lower interfacial thermally induced stresses. These are due to the different coefficients of thermal expansion (contraction) of the dissimilar materials in the trimaterial structure. The study is restricted to the evaluation of the shearing stresses only and is based on a simplified strength-of-materials model, rather than on a rigorous theory-of-elasticity method. Such a approach seems to be justified, since the most accurate predictions of the magnitude and the distribution of the induced stresses are beyond the scope of this analysis. On the basis of the calculated data, we conclude that there is a definite incentive for employing a bimaterial coating system, in which “conventional” (high modulus) polymeric material is used in the midportion of the fiber, while a low-modulus material (typically, with a higher coefficient of expansion) is applied at its ends. Such a system could be recommended, when there is a need to bring down the interfacial stresses, and the possible increase in the manufacturing cost is not viewed as an obstacle.

Lead zirconate titanate (PZT) thin films were deposited in a reactive argon/oxygen gas mixture by radio-frequency-magnetron sputtering. The use of a metallic target allows us to control the oxygen incorporation in the PZT thin film and also, using oxygen 18 as a tracer, to study the oxygen diffusion in the thin films. Electrical properties and crystallization were optimized with a 90-nm PZT thin film grown on RuO2 electrodes. These PZT films, annealed with a very modest thermal budget (550 °C) show very low leakage current densities (J = 2 × 10−8 A/cm2 at 1 V). In this article we show that a strong correlation exists between the oxygen composition in the PZT film and the leakage current density.

Strontium barium niobate (SBN) thin films were crystallized by conventional electric furnace annealing and by rapid-thermal annealing (RTA) at different temperatures. The average grain size of films was 70 nm and thickness around 500 nm. Using x-ray diffraction, we identified the presence of polycrystalline SBN phase for films annealed from 500 to 700 °C in both cases. Phases such as SrNb2O6 and BaNb2O6 were predominantly crystallized in films annealed at 500 °C, disappearing at higher temperatures. Dielectric and ferroelectric parameters obtained from films crystallized by conventional furnace and RTA presented essentially the same values.