A fully dense nanocrystalline (nc) Cu with mean grain size of 72 nm and a broad grain size distribution was synthesized by electrodeposition. Uniaxial tensile tests were done at different strain rates and room temperature. A very high strength of 1.04 G was obtained at strain rate of 0.1 s−1. The nearly perfect plasticity with a large strain of close to 20% was displayed at specific low strain rates of 4 × 10−5 to 10−4 s−1. With increasing strain rate, the nearly perfect plasticity disappeared. Strain rate sensitivity and activation volume of the nc Cu were estimated from the flow stress at a fixed strain of 1% and a strain rate change (jump) test. It was deduced from the high strain rate sensitivity exponent of 0.08 and small activation volume of 12b3 that both dislocation and grain boundary activities would take place in this nc Cu, which explained the nearly perfect plasticity observed in the tensile test.

A comparison of microcompression and microtensile methods to study mechanical properties of electrodeposited nanocrystalline (nc) nickel has been performed. Microtensile tests that probe a volume of more than 2 × 106 μm3 show reasonable agreement with results from microcompression tests that probe much smaller volumes down to a few μm3. Differences between the two uniaxial techniques are discussed in terms of measurements errors, probed volume and surface effects, strain rate, and influence of stress state. Uniaxial solicitation in compression mode revealed several advantages for studying stress–strain properties.

A combustion-synthesized AlN powder was investigated for use as a starting material in obtaining a high thermal conductivity AlN by microwave sintering followed by microwave reheating under a reducing atmosphere. Microwave sintering was found to proceed very quickly so that a density of 99.5% of theoretical with a thermal conductivity of 165 W/mK was achieved after sintering at 1900 °C for 5 min. The thermal conductivity could be improved by prolonging the soaking time, which is attributed to decreases in both oxygen content and secondary phases by evaporation and sublimation of the secondary phases. The reducing atmosphere was created by adding carbon particles to the AlN packing powder surrounding the specimen. The thermal conductivity could be significantly improved by microwave reheating of the sintered specimen under the reducing atmosphere. This is considered to be due to enhanced removal of the secondary phases by the reducing atmosphere. Sintering under the reducing atmosphere was found to retard densification because of the earlier removal of the secondary phases, thus resulting in a poor densification and a low thermal conductivity.

The optical and electrical properties of “tilted” and “spiral” indium tin oxide (ITO) thin films are reported. The influence of the flux incident angle on the optical and electrical properties is investigated. When the flux incident angle is increased, both the refractive index and extinction coefficient of the film are decreased, but the resistivity is increased. Thus, the physical properties of the film can be modified over a wide range by adjusting the flux incident angle and substrate rotation scheme. It is suggested that the oblique angle deposition technique provides ITO films with more application possibilities by allowing their optical and electrical properties to be tailored.

Chemical vapor deposition of diamond has opened up new applications in microelectronics, microelectromechanical systems (MEMS), and coating technologies. This paper compares and contrasts the high-temperature electrical behavior of microcrystalline versus nanocrystalline diamond films. Through-thickness current–voltage characteristics between room temperature and 823 K are presented for a series of films synthesized with different gas phase concentrations of nitrogen and argon. One set of samples was characterized by measurements between room temperature and 823 K and a second set by two-step thermal cycling from room temperature to 573 and 823 K. It was found that with increasing nitrogen concentration (up to 0.1% N2), the resistivity slightly increased followed by a decrease at higher concentrations. Activation energies and barrier heights were in general lower for the more defective films. These results in conjunction with material characterization indicated that more defective diamond films were synthesized at higher nitrogen concentrations in the gas phase.

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.

The poly-2-hyroxyethyl methacrylate (PHEMA)/clay nanocomposite was synthesized by in situ atom transfer radical polymerization (ATRP) from initiator moieties immobilized within the silicate galleries of the clay particles. To produce organically modified montmorillonite (MMT) that has ATRP initiator moiety, a new catalyst that consists of quaternary ammonium salt moiety and an initiator moiety was synthesized. This initiator was intercalated into the interlayer spacing of the MMT. The polymerization reaction was carried out in a mixed solvent system consisting of methyl ethyl ketone and 1-propanol at 50 °C, using the initiator that has been already synthesized with a copper bromide catalyst. The 2, 2′-bipyridyl (bpy) complex was used as ligand. The products were characterized via Fourier transform infrared, nuclear magnetic resonance (1H NMR, 12C NMR), transmission electron microscopy, x-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry.

Crystallographic ordering and defects in WSe2 thin films with ultralow thermal conductivity are characterized by electron imaging and diffraction in cross-sectional geometry. The results show that the film consists of oriented, coherent crystallites that are a few nanometers in diameter. Two films of different thickness with different thermal conductivity are compared. We show that the film with a lower thermal conductivity is characterized by less coherent crystallites with a greater degree of misorientation.

The relations among the process, microstructure, and nanomechanical properties of cosputtered Ta–Si–N thin films have been investigated. The microstructure evolution and varied hardness and elastic modulus property of Ta–Si–N were influenced by nitrogen flow ratios [FN2% = FN2/(Far + FN2) × 100%] during cosputtering together with phase formation and the composition of films. The microstructure of Ta–Si–N formed at a low 2–10 FN2% was an amorphous-like phase with nanocrystalline grains embedded in an amorphous matrix, while polycrystalline Ta–Si–N was obtained at a high 20–30 FN2%. The cubic TaN phase or (Ta1–x,Six)N solid solution is much easier to form polycrystallites than noncubic Ta5Si3, Ta2Si, and Ta2N phases from grazing incidence x-ray diffractometry results. Amorphous-like Ta–Si–N films had much higher nanohardness, stiffness, elastic recovery percentage, and a closer boundary compared to polycrystalline films. A maximum nanohardness of 15.2 GPa was obtained at 3 FN2%. An increased hardness of polycrystalline films at 20–30 FN2% is attributed to the higher amount of the hard TaN phase.

Luminescence properties of Yb-doped Ca-α-SiAlON phosphors with composition of Ca1−xYbxSi12−(m+n)Alm+nOnN16−n were investigated by using cathodoluminescence (CL). The ratio of Yb to Ca was kept constant while the host lattice was changed by replacing m+n(Si–N) bonds with m(Al–N) and n(Al–O) bonds. The luminescence of these phosphors consists of three peaks in the ultraviolet (UV), green (VIS), and infrared (IR) regions, which are attributed to the emissions from secondary phases, Yb2+ and Yb3+, respectively. The UV emission depends on the Si/Al ratio: the UV peak is centered at 310 nm for the Si-rich mix and at 360 nm for the Al-rich mix. We have found that Yb exists in the divalent state in α-SiAlON and in the trivalent state in the secondary phases.

Al/Ni multilayer foils were sputter-deposited with an in-plane residual stress state that was altered midway through the thickness of the foils by changing the bilayer spacing. The difference in stress between the top and bottom halves of the foil caused these systems to curl when they were removed from their substrates. As predicted, the radius of curvature increased linearly as the difference in stress between the upper and lower halves decreased and as foil thickness increased, demonstrating the ability to fabricate layered foils with specific curvatures. Unexpectedly, however, the radii of curvature of all the free-standing foils decreased with time after removal from their substrates, suggesting that a time-dependent relaxation mechanism was operating. An explanation based on stress driven, time-dependent deformation is offered to explain the relaxation, and an elasticity-based curvature model is presented for comparison with the measured steady state curvatures.

Fe–Ni alloy cluster-assembled films were obtained by a plasma–gas-condensation-type cluster-deposition method. We studied the magnetic and electrical properties of these assemblies prepared on an electrically grounded substrate [bias voltage (Va) = 0 kV] and on a negatively biased substrate (Va = −20 kV). The packing density and saturation magnetization per volume, Ms, are much larger for the assemblies prepared at Va = −20 kV than those prepared at Va = 0 kV, while the magnetic coercivity, Hc, and electrical resistivity, ρ, are much lower for the assemblies prepared at Va = −20 kV than those prepared at Va = 0 kV. For Ni-rich Fe–Ni alloy cluster-assembled films obtained at Va = −20 kV, the Hc values can become smaller than 160 A/m (the precision limit of our superconducting quantum interference device magnetometer) by adjusting the initial cluster size. The magnetic and electrical properties of Fe–Ni cluster-assembled films are much improved in comparison with those of pure Fe cluster-assembled films.

The present study shows that the as-melt-spun Zr28Y28Al22Co22 amorphous ribbon undergoes solid-state phase separation into Zr- and Y-rich regions when heated below the glass transition temperature (Tg). Dynamic mechanical measurements show that two types of low-temperature relaxation occur below Tg, and transmission electron microscopy observation confirms the solid-state phase-separated microstructure. The diffusion coefficient of solid-state phase separation is calculated by the measured separation distance.

Temperature-dependent photoluminescence (PL) spectra were measured to characterize the In-doped cadmium zinc telluride (CdZnTe, or CZT) crystals along the growth direction in the range of 10 to 60 K. High-resistivity CZT samples with 1.2 ppm In dopant at the tip and low-resistivity samples with 60 ppm In dopant at the heel have been assessed. The PL intensity quenching of D0X were fitted with two activation energies for high-resistivity CZT sample and only one activation energy for low-resistivity sample, respectively, suggesting different recombination mechanisms. The C-line was observed in the PL spectra of low-resistivity CZT sample and considered to the results of the isoelectronic complexes, InCd–VCd–InCd, while in high-resistivity CZT sample, shallow donor accepted pair (DAP) transition was identified, and thought to be related to InCd–VCd. The A-center in PL spectra was observed in low-resistivity CZT sample, which is indicative of more cadmium vacancies. It turns out that indium in low-resistivity CZT sample has not been doped as efficiently as in high-resistivity CZT sample because of the self-compensation.

A new type of Ti–Si–C–N coatings deposited on high-speed steel substrate by means of pulsed direct current (dc) plasma-enhanced chemical vapor deposition was investigated. The as-deposited coatings were characterized systematically by using energy-dispersive x-ray spectroscopy, x-ray diffraction (XRD), transmission electron microscopy (TEM), and microhardness with particular attention paid to the microstructure of the coatings. It has been shown that C content has a profound effect on the microstructure and hardness of coatings. TEM and XRD analyses revealed that these coatings consist of the dominate Ti(C, N) with a silicide (TiSi2, Si3N4, or SiC, depending on the C content in the coatings). The crystallite sizes are in the range of 8–35 nm, which decrease with increasing C content. The Ti–Si–C–N coatings with high C content (25.2–38.6 at.%) possess superhardness (41–48 GPa). This can be attributed to the grain refinement/grain boundary hardening and dispersion hardening of the hard, nanosized crystalline Si3N4 or SiC formed in the deposition.

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.

Electromigration at 5 × 104 A/cm2 and 100 °C was conducted to grow composite Pb/Sn whiskers from SnPb solders, in which a Pb whisker grows first and then a whisker of Sn grows. In some cases, small Sn islands are embedded in Pb whiskers. The diameter of a composite whisker is <1 μm, which is much smaller than that of spontaneous Sn whisker growth on leadframes. The growth orientation of Pb whiskers was in the [110], [1¯11], and [112] directions. This investigation proposes that compressive stress generated by electromigration at the anode provides the force driving whisker growth. Therefore, accelerated tests of whisker growth at higher temperatures using electromigration are feasible.

In the present work, the oxide layers developed at elevated temperature on three vanadium-free titanium alloys, of interest as implant biomaterials, were studied by Rutherford backscattering spectroscopy, elastic recoil detection analysis, and scanning electron microscopy. The chemical composition of the alloys investigated, in wt%, was Ti–7Nb–6Al, Ti–13Nb–13Zr, and Ti–15Zr–4Nb. Upon oxidation in air at 750 °C, an oxide scale forms, with a chemical composition, morphology, and thickness that depend on the alloy composition and the oxidation time. After equal exposure time, the Ti–7Nb–6Al alloy exhibited the thinnest oxide layer due to the formation of an Al2O3-rich layer. The oxide scale of the two TiNbZr alloys is mainly composed of Ti oxides, with small amounts of Nb and Zr dissolved. For both TiNbZr alloys, the role of the Nb-content on the mechanism of the oxide formation is discussed.

A co-sputtering system was used to deposit silicon nanoclusters embedded in zinc oxide matrix (Si:ZnO) at low temperature without post-annealing. By adjusting the radio frequency power of the Si target during co-sputtering, Si:ZnO films with various crystallographic structures can be obtained. Silicon nanoclusters embedded in the zinc oxide matrix were examined using a high-resolution transmission electron microscope, x-ray diffractometer, and Fourier transformation infrared spectrometry. By comparing with photoluminescence spectra, we can clearly identify quantum confinement effect of silicon nanoclusters embedded in the ZnO matrix.

In situ scanning electron microscopy was performed during elevated-temperature (⩽760 °C) tensile-creep deformation of a face-centered-cubic cobalt-based Udimet 188 alloy to characterize the deformation evolution and, in particular, the grain boundary-cracking evolution. In situ electron backscatter diffraction observations combined with in situ secondary electron imaging indicated that general high-angle grain boundaries were more susceptible to cracking than low-angle grain boundaries and coincident site-lattice boundaries. The extent of general high-angle grain-boundary cracking increased with increasing creep time. Grain-boundary cracking was also observed throughout subsurface locations as observed for postdeformed samples. The electron backscattered diffraction orientation mapping performed during in situ tensile-creep deformation proved to be a powerful means for characterizing the surface deformation evolution and in particular for quantifying the types of grain boundaries that preferentially cracked.