Simplification of the ion-beam-assisted deposition (IBAD) buffer architecture is one of the key issues for reduced manufacturing cost of second-generation superconducting wire production. In this work, we studied various radio frequency magnetron sputter deposition conditions for epitaxial growth of LaMnO3 (LMO) layers, with varying thicknesses, directly on IBAD-MgO without homo-epitaxial MgO layers. Performance of the simplified LMO/IBAD-MgO samples was qualified by pulsed-laser-deposited 1-μm-thick YBa2Cu3O7−δ (YBCO) coatings. Detailed property characterizations revealed that though the growth temperature has a substantial effect on the texture of LMO layers, neither LMO thickness nor different sputter gas compositions had a significant effect on the performance of YBCO films. The superconducting properties of YBCO on LMO/IBAD-MgO are found to be similar to those obtained on templates having homo-epitaxial MgO layers. The present results underscore the strong potential of LMO as a single cap layer directly on IBAD-MgO for the development of a simplified IBAD architecture.

Differential speed rolling (DSR) has been carried out on AZ31 alloys with Mn additions of 0 to 0.6 wt% for investigating the effects of Mn on microstructure, texture, mechanical properties, and formability. The Al–Mn compounds were formed in the sample with a Mn addition of only 0.2 wt% because of its low solid-solubility limit. There were tiny differences among the DSR-processed AZ31 alloys with different Mn contents, while the AZ31 alloy without Mn addition exhibited a more homogeneous microstructure, a weaker basal texture intensity, and a much superior formability together with a larger likelihood of grain growth during annealing. The Mn dissolving in αMg matrix exerted a far stronger influence on the resulting properties compared with those existing in form of the Al–Mn compounds. The Mn solute atoms induced an increase in c/a ratio, which may suppress activity of nonbasal slips and in turn degrade the deformation capability.

Mechanical properties of silicon are of high interest to the microelectromechanical systems community as it is the most frequently used structural material. Compression tests on 8 μm diameter silicon pillars were performed under a micro-Raman setup. The uniaxial stress in the micropillars was derived from a load cell mounted on a microindenter and from the Raman peak shift. Stress measurements from the load cell and from the micro-Raman spectrum are in excellent agreement. The average compressive failure strength measured in the middle of the micropillars is 5.1 GPa. Transmission electron microscopy investigation of compressed micropillars showed cracks at the pillar surface or in the core. A correlation between crack formation and dislocation activity was observed. The authors strongly believe that the combination of nanoindentation and micro-Raman spectroscopy allowed detection of cracks prior to failure of the micropillar, which also allowed an estimation of the in-plane stress in the vicinity of the crack tip.

Nanocomposite Cr–B–N coatings were deposited from CrB0.2 compound targets by reactive arc evaporation using an Ar/N2 discharge at 500 °C and −20 V substrate bias. Elastic recoil detection (ERDA), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and selected-area electron diffraction (SAED) were used to study the effect of the N2 partial pressure on composition and microstructure of the coatings. Cross-sectional scanning electron microscopy (SEM) showed that the coating morphology changes from a glassy to a columnar structure with increasing N2 partial pressure, which coincides with the transition from an amorphous to a crystalline growth mode. The saturation of N content in the coating confirms the formation of a thermodynamically stable CrN–BN dual-phase structure at higher N2 fractions, exhibiting a maximum in hardness of approximately 29 GPa.

A finite element analysis was used to determine how patterned, nanoscale interfacial roughness could potentially increase the apparent interfacial toughness of brittle, thin-film material systems. The pattern analyzed was composed of parallel channels with either a rectangular-toothed or a rippled cross-section. Results are presented for a thin, linear elastic, bimaterial strip loaded by displacing the top edge relative to the bottom edge. The finite element calculations indicate that the interface does not unzip in a steady, continuous manner. Instead, the crack tip stalls as it tries to kink in a direction that is offset from its original path. The apparent interfacial toughness is found to depend on the intrinsic interfacial toughness, the ratio of real-to-nominal interfacial area, the extent of ligament, tooth-tip damage that occurs before crack propagation, strain energy locked in by persistent contact, and the level of energy dissipation associated with dynamic fracture.

High-temperature titanium matrix composites reinforced with hybrid reinforcements are synthesized by common casting and hot working technologies. Tensile properties are tested at different temperatures and strain rates. Ultimate strengths of the composites are significantly enhanced under all conditions and decrease when the strain rate is lower. Equicohesive temperature of the matrix is around 873 K at the strain rate 10−3s−1 and well below 873 K at 10−5s−1. At higher temperature or lower strain rate, interfacial debonding is more drastic and reduces the strengths of composites. The materials are embrittled under creep-rupture conditions. Strict reinforcement morphology is required for more complex service conditions at high temperatures in metal matrix composites.

Hard transparent conducting oxide films of hex-element AlxCoCrCuFeNi were deposited by reactive direct current (dc) magnetron sputtering using homogeneous alloy targets. The composition–property relation was investigated by changing the aluminum molar ratio, x value, from 0.5 to 2. The films comprise only a cubic spinel phase without other accompanying crystalline oxide phases and exhibit a high hardness up to 22.2 GPa. A small, negative deviation from Vegard’s law was observed for the spinel phase, which indicated changes in cation distribution. The optical transmittance in both the visible and infrared region is increased with aluminum content, however, together with a loss of film conductivity. The Hall measurements reveal a p-type conducting behavior for the Al0.5CoCrCuFeNi oxide film with a conductivity of 40.1 Ω−1cm−1, a carrier density of 5.81 × 1018 cm−3, and a mobility as high as 43.2 cm2V−1s−1. Moreover, Hall measurements show metallic conduction behavior for the Al0.5CoCrCuFeNi oxide film and thermal activated semiconducting properties for the Al1CoCrCuFeNi and Al2CoCrCuFeNi oxide films. Combine the crystal field theory and the x-ray photoelectron spectroscopy (XPS) measurements, the decrease of film conductivity is explained by the decreases of available carriers and mobility due to the fact that increasing aluminum content reduces the number of conducting cations at octahedral sites and increases the activation energy for electrical conduction. XPS analyses also show lots of excess oxygen originated from anion-rich growth condition in the films deposited at high oxygen partial pressure that produce p-type carriers lowering the electrical resistivity. The amount of excess oxygen decreases with increasing Al content and also contributes to the variation of conductivity with x value.

Oxyfluoride aluminosilicate glasses with compositions of 50SiO2–20Al2O3–20BaF2–10GdF3–0.5PrF3–xYbF3(x = 0, 1.0, 2.5, 5, 7.5, 10, 15, 20, 25, and 30 mol%) have been prepared to study their thermal and optical properties. From the differential thermal analysis (DTA) measurement, glass-transition temperatures and onset crystallization temperatures have been evaluated and from them, glass-stability factors against crystallization were calculated. Glass stabilities were decreased gradually with fluoride content increment in all the studied glasses. The photoluminescence and decay measurements have also been carried out for these glasses. In these glasses, an efficient near-infrared (NIR) quantum cutting with optimal quantum efficiency approaching 160% have been demonstrated, by exploring the cooperative downconversion mechanism from Pr3+ to Yb3+ with 481 nm (3P0 → 3H4) excitation wave length. These glasses are promising materials to achieve high-efficiency silicon-base solar cells by means of downconversion in the visible part of the solar spectrum.

This work reports for the first time the synthesis of γ-(Al1-xFex)2O3 solid solutions with a high specific surface area (200-230 m2/g) by the decomposition of metal oxinate [(Al1-xFex)(C9H6ON)3] and investigated the potential of these materials as catalysts for the synthesis of carbon nanotubes by catalytic chemical vapor deposition using methane or ethylene as carbon the source. The nanocomposite powders prepared by reduction in H2-CH4 contain carbon nanotubes (CNTs), which are mostly double-walled but also contain a fair amount of undesirable carbon nanofibers, hollow carbon particles, and metal particles covered by carbon layers. Moreover, abundant metallic particles are observed to cover the surfaces of the matrix grains. By contrast, the nanocomposite powders prepared by reduction in N2-C2H4 are not fully reduced, and the CNTs are much more abundant and homogeneous. However, they are multiwalled CNTs with a significant proportion of defects. The powders were studied by several techniques including Mössbauer spectroscopy and electron microscopy.

The dielectric anomalies and their structure dependence were evaluated and discussed in Sr4(LaxNd1-x)2Ti4Nb6O30 ceramics, together with the analysis of ultrasonic velocity shift and attenuation spectra in the low-temperature range. The room-temperature structure was confirmed as the tetragonal in space group P4bm for all compositions. One diffuse ferroelectric peak and three relaxor ferroelectric peaks corresponding to the commensurate/incommensurate modulation of oxygen octahedra, polar clusters of A-site ion ordering, and B-site ion ordering, respectively, were observed in the composition with x = 0.25. With decreasing the radius difference between A1- and A2-ions (increasing x), the dielectric relaxations, especially the one originating from the polar clusters of A-site ion ordering, tended to increase significantly and overlap the diffuse ferroelectric peak, which was completely overlapped for x ⩾ 0.75. This process just reflected the increased disordering degree of both A- and B-site ions, and the analysis of ultrasonic attenuation strongly supported the above conclusions on dielectric relaxations and their structural origins. The ultrasonic attenuation peak at approximately 100 K corresponded to the freezing process of the dielectric relaxations, and the fluctuation with composition of the ultrasonic attenuation peaks between 150 and 260 K suggested the possible structure variation.

Guidelines for selecting the shape formed by metal discharged from a narrow Al line were developed. By controlling electromigration in the line, either relatively large microspheres, thin wires, or relatively small microspheres could be formed. Our starting point was a passivated polycrystalline Al line with a slit and small holes at the anode end of it. In the discussion, we describe how the temperature of a part of a wire, T*, at the moment when the part is completely discharged from the hole, affects the shape of the microstructural feature formed from the metal. High, intermediate, and low values of T* were found to correspond to the formation of large microspheres, thin wires, and small microspheres, respectively. The experimental results are explained in the discussion.