To improve the properties of the eutectic Sn–Ag lead-free solder alloy, various amounts of mixed rare-earth (RE) elements, mainly Ce and La, were added. The microstructure, wetting properties, melting behavior, mechanical properties, and creep behavior were studied. It was revealed that RE elements can refine the intermetallics, and with 0.5% RE addition, the RE-bearing phase can be detected in the microstructure of the slow-cooled alloy. The results of differential scanning calorimetry indicate that the melting points of the RE-doped alloys are slightly lower than that of the Sn–3.5Ag and have a eutectic peak. The wetting property and creep resistance of the Sn–3.5Ag–0.25RE alloy are better than those of the Sn–3.5Ag alloy. The creep properties were studied at the temperatures of 303, 348, and 393 K, at various stress levels between 8 and 34 MPa. The stress exponents of the Sn–3.5Ag and Sn–3.5Ag–0.25RE were obtained at these temperatures. Tensile, creep, and wetting properties were found to improve with the addition of RE elements. The improvement of creep resistance is due to the fine dispersion of intermetallics and the decrease in interface energy between matrix and intermetallics. The wettability improvement is mainly due to the accumulation of RE elements at the solder/flux interface, leading to the reduction of the interfacial tension between solder and flux.

Computational fluid dynamic techniques were used to analyze the gas flow behavior of a typical atomization configuration. The calculated results are summarized as follows. The atomization gas flow at the atomizer's exit may be either subsonic at ambient pressure or sonic at an underexpanded condition, depending on the magnitude of the inlet gas pressure. When the atomization gas separates to become a free annular gas jet, a closed recirculating vortex region is formed between the liquid delivery tube and the annular jet's inner boundary. Upon entering the atomization chamber, an underexpanded sonic gas flow is further accelerated to supersonic velocity during expansion. This pressure adjustment establishes itself in repetitive expansion and compression waves. A certain protrusion of the liquid delivery tube is crucial to obtain a stable subatmospheric pressure region at its exit. The vortex flow under the liquid delivery tube tends to transport liquid metal to the high kinetic energy gas located outside the liquid delivery tube, thereby leading to an efficient atomization.

The development of denser and higher powered integrated circuits has led to a corresponding demand on the performance of dielectric substrates. This paper reports on the fabrication and properties of an AlN multilayered sandwich substrate comprising porous tape-cast layers sandwiched between nonporous layers. Tapes were produced by nonaqueous tape casting, with the porous tapes produced using polymer microspheres as sacrificial molds. Starting from initially Al2O3-rich tapes, the multilayered sandwich substrates were reaction sintered to produce AlN substrates. No interface cracking or delamination was observed in the substrates as a result of the processing. The added porosity resulted in a decrease in the substrate dielectric constant in correspondence to porosity volume. Mechanical strength of the sandwich substrates was improved over that of nonsandwich porous substrates, while substrates having noninterconnected pores showing higher mechanical strength than substrates with connected pores. Substrates with more than 2% porosity showed porosity-dependent thermal conductivity values, while thermal conductivity of substrates with less than 2% porosity was dependent on grain boundary effects. Thermal expansion coefficient of the substrates was unaffected by porosity levels.

In this paper, we report on a study of the surface effect on nanoindentation and introduce the apparent surface stress that represents the energy dissipated per unit area of a solid surface in a nanoindentation test. The work done by an applied indentation load contains both bulk and surface work. Surface work, which is related to the apparent surface stress and the size and geometry of an indenter tip, is necessary in the deformation of a solid surface. Good agreement is found between theoretical first-order approximations and empirical data on depth-dependent hardness, indicating that the apparent surface stress plays an important role in depth-dependent hardness. In addition, we introduce a critical indentation depth. The surface deformation predominates if the indentation depth is shallower than the critical depth, while the bulk deformation predominates when the indentation depth is deeper than the critical depth.

Well-dispersed SiC slurries in the presence of binder and plasticizer were prepared and investigated in this series of work. In this part, poly(vinyl alcohol) (PVA) 1788 was investigated as a potential binder for aqueous tape casting process. The minimum amount of binder was determined through a primary calculation. Effects of the binder on SiC slurries properties were analyzed in term of zeta potential measurement and rheological test. Coupled with PEI as dispersant and glycerol as plasticizer, they lead to homogeneous systems which seem compatible. The suspensions (formulated with 47.9 wt% SiC powder, 1 wt% dispersant, 3.5 wt% binder, and 3.5 wt% plasticizer) exhibited a shear-thinning behavior with a very limited time-dependent character. After tape casting and drying process, the properties of green tapes were evaluated in term of solid content and gap height. The optimal solid content of SiC was found to be near 22.25 vol%, and the gap height, near 200 μm. The microstructure of green tape was characterized by TEM. Results showed that preparation of homogeneous green tapes with relative densities at about 51 vol% was feasible.

We report on the magnetic and transport properties of the antiperovskite GaCMn3 film epitaxially grown on LaAlO3 using the pulsed laser deposition technique. Upon cooling from room temperature, the GaCMn3 film undergoes magnetic transitions from paramagnetic to ferromagnetic to antiferromagnetic. The Curie and Neél temperatures of the film shift to lower and higher temperatures, respectively, by comparison with those of the bulk sample. This discrepancy is mainly ascribed to the compressive strain effect induced by the lattice-mismatch between film and substrate. Negative magnetoresistance, which is about 20% at 0.5 T, is observed near the Neél temperature.

Numerous previous investigations on the magnetic properties of Fe–Cr–Ni or similar alloys show that the Néel temperature of this class of material is usually in the range 20–40 K and never exceeds 60 K. In this paper, we report on the discovery that the Ne’el temperature of a Fe–Cr–Ni–Mo alloy can be substantially increased to approximately 80–100 K by long-term thermal aging at 800 °C and above. This discovery has raised many questions on the detailed mechanism of magnetic transition on this class of material and is expected to open up a new line of investigation for researchers in this field.

In modulus measurement by depth-sensing indentation, previous considerations assume elastic recovery to be the sole process during unloading, but in reality creep and thermal drift may also occur, causing serious errors in the measured modulus. In this work, the problem of indentation on a linear viscoelastic half-space is solved using the correspondence principle between elasticity and linear viscoelasticity. The correction term due to creep in the apparent contact compliance is found to be equal to the ratio of the indenter displacement rate at the end of the load hold to the unloading rate. A condition for nullifying the effect of thermal drift on modulus measurement is also proposed. With this condition satisfied, the effect of thermal drift on the calculated modulus is negligible irrespective of the magnitude of the drift rate.

This report studies the electromigration performance of W-plug via structures under the reservoir effect. The lifetime improvement factor M was observed to be a weak function of the stressing current and approximately equal to 2. A Simple model is included in the report to explain this observation. The model also predicts the most effective reservoir length for electromigration lifetime improvement.

Morphology and analysis of composition of inclusions were done by secondary electron microscopy and spatially resolved energy-dispersive analysis of x-ray on semiintrinsic CdTe:Cl and CdTe:Zn:Cl crystals grown from the vapor phase by the modified Markov technique and on undoped CdTe crystals grown from the melt by the Bridgman method. In CdTe:Cl and CdTe:Zn:Cl crystals nonstoichiometric inclusions of about 10–20 μm were found, which contain high concentrations of Cl and Na impurities. The Cl is concentrated in small precipitates of 1–2 μm inside these inclusions. After short-time low-temperature annealing (600 °C), the inclusions mostly disappeared.

An Al2O3–5 at% SiO2 specimen was levitated in an Aero-Acoustic Levitation apparatus and then melted when a continuous-wave CO2 laser beam heating system was incorporated. The sample can be highly undercooled when decreasing the laser power. Rapid solidification by splat quenching can be realized at defined temperatures, using well-polished copper as chilling anvils. Microstructure transition from nonfaceted colony to strong faceted dendrites was observed when the melt was quenched at ΔT = 50 K, indicating that a kinetic contribution for roughening the microstructure may be significant for the morphology transition. The impacting, spreading, and solidifying processes were analyzed on the basis of microstructure observation. The additional undercooling was suggested to vary per an exponential relation with distance when the kinetic effect was taken into account. The nucleation behavior was also discussed according to the proposed additional undercoolings to demonstrate the difference in nucleation population at various regions. When the melt undercooling increases to 190 K, a double-phase structure with small polycrystalline inclusion embedded into amorphous matrix was obtained. The continuous cooling transformation profile was proposed to account for the phase selection upon quenching. The present observation and suggested model for acquiring high additional undercoolings are useful in elucidating the work of others.

Thin films of CsxTi(2−x/4)□x/4O4 (CsTiO), K4Nb6O17 (KNbO), and their proton-exchanged forms, i.e., HxTi(2−x/4)□x/4O4 (HTiO) and H4Nb6O17 (HNbO), were prepared using the electrophoretic deposition technique. The amine- and thiol-intercalated HTiO and HNbO films were prepared by exfoliation of powders in aqueous ethylamine and (mercaptoethyl)amine hydrochloride solutions, respectively. The heat-induced phase transformation of these films was investigated. Evidently, the CsTiO and thiol-intercalated HTiO films underwent phase transformation at relatively high temperatures due to the cations within the interlayer. CsTiO and HTiO films lost their layered structure and transformed, in turn, into the anatase and rutile phases with increasing temperature. However, the intercalated samples exhibited unidentified phases at in-between temperatures, eventually transforming to TiO2. The KNbO film transformed into a layered KNb3O8 structure, while the HNbO lost its layered structure completely to form Nb2O5. Thus, the phase change depended on the modification of the interlayers, and the heat treatment resulted in thin films with new crystal structures for the amine- and thiol-intercalated samples.

Recent experimental work by a number of researchers has demonstrated that unusual high porosity thin films may be obtained in physical deposition systems by combining glancing angle deposition with in situ substrate motion control. The microstructure of these films consists of isolated columns engineered into shapes such as helices, posts, or chevrons. Due to the isolated nature of the columns, the films present a unique opportunity to study fundamental thin film growth behavior and, in particular, the influence of the self-shadowing mechanism in three dimensions. Apart from this academic motivation, there is the need to characterize the physical constraints imposed on the engineering of these films. In particular, this study will have implications for the realization of isolated, periodically arranged nanostructures envisioned for certain applications such as photonic band gap crystals. Results from an ongoing study of growth dynamics, morphology, porosity, and scaling behavior, and the dependence of these features on deposition parameters are presented.

The effects of energetic treatments, crosslinking, and plasma modification on the surface mechanical properties and deformation behavior of ultrahigh molecular weight polyethylene (UHMWPE) were examined in light of nanoindentation experiments performed with a surface force microscope. Samples of UHMWPE were subjected to relatively high-dose gamma irradiation, oxygen ion implantation, and argon ion beam treatment. A range of crosslinking was achieved by varying the radiation dose. In addition, low-temperature plasma treatment with hexamethyldisiloxane/O2 and C3F6 was investigated for comparison. The surface mechanical properties of the treated UHMWPE samples are compared with those of untreated UHMWPE samples used as controls. Surface adhesion measurements obtained from the nanoindentation material responses are also discussed in terms of important treatment parameters. Results demonstrate that high-dose oxygen ion implantation, argon ion beam treatment, and low-temperature C3F6 plasma modification are effective treatments for enhancing the surface mechanical properties of UHMWPE.

Bauxite ore (industrial raw material) and aluminum dross tailings (a local industrial waste material of the Aluminium Company of Egypt, Egyptalum) were used as two different parent materials to produce alumina. A set of six different preparation methods was applied to aluminum extracts from both materials. X-ray powder diffractometry, thermal and chemical analyses, and surface area and charge measurements were used to characterize the alumina products. The results indicate that catalytic grade, high-purity alumina products of uniform particle sizes could be obtained in large yields, depending solely on the preparation method applied, i.e., irrespective of the raw material used. Thus, aluminum dross tailings chemical waste is proved to be a feasible parent material for specialty alumina, which is an important finding both economically and environmentally.

Neodymium(III) oxide nanocrystals prepared by an inverse microemulsion technique have been dispersed in sol-gel titania/(γ-glycidoxypropyl)trimethoxysilane composite thin films at low temperature. Transmission electron microscopy and x-ray diffraction were used to characterize the phosphor nanoparticles and show that the neodymium(III) oxide nanoparticles have a nanocrystal structure and the size of the nanoparticles is in the range from 5 to 60 nm. An intense up-conversion emission in violet (399 nm) color from neodymium(III) oxide nanocrystals upon excitation with a yellow light (577 nm) has been observed. Two ultraviolet emissions at 347 and 372 nm and a blue emission at 466 nm have also been observed, and those are assigned to electronic transitions appropriately. A relatively strong room-temperature photoluminescence emission at 1064 nm corresponding to the 4F3/2 → 4I11/12 transition of neodymium ion has been measured as a function of the heat treatment temperature. In addition to this emission, two other emissions at 890 and 1336 nm have also been observed. Especially, a clear shoulder peak at 1145 nm, which could probably be resulting from the host matrix, was observed in all measured samples, and this shoulder peak reached a maximum intensity after a heat treatment at 300 °C.

Oxygen diffusion into c-axis-oriented YBa2Cu3O7-δ epitaxial thin films was observed using real-time spectroscopic ellipsometry. The experiments were conducted under controlled atmospheres of 10% O3/90% O2 and 80% O3/20% O2. At 2 × 10-5 torr, oxidation of the films began at temperatures as low as 100–125 °C for heating rates ≤3 °C/min. Full oxidation was seen by 190 °C at these rates. Based on these data, the activation energy of oxygen diffusion into YBa2Cu3O7-δ from an ozone/oxygen atmosphere was found to be between 0.43 and 0.52 eV. This was appreciably smaller than for in-diffusion in a molecular oxygen atmosphere. Higher ozone content atmospheres did not improve the oxidation kinetics. These atmospheres did, however, delay the onset of reduction in the films by 60–70 °C at higher temperatures.

The thickness dependence of the dielectric properties of epitaxial BaTiO3 thin films was investigated for thicknesses ranging from 15 to 320 nm. The films were deposited by low-pressure metalorganic chemical vapor deposition on (100) MgO substrates. The relative dielectric permittivity and the loss tangent values decreased with decreasing thickness. High-temperature dielectric measurements showed that with decreasing film thickness, the ferroelectric-to-paraelectric transition temperature decreased, the relative dielectric permittivity decreased, and the phase transition was diffuse. The c/a ratio also decreased with decreasing film thickness. The observed behavior for epitaxial films of BaTiO3 was attributed to the presence of strain in the films.

We fabricated MgB2 tapes by a powder-in-tube method using sheath materials of Fe and carbon steel (CS). In the as-rolled state, the CS-sheathed tapes showed higher transport critical current density (Jc) values than the Fe-sheathed tape did. This is due to the higher-density MgB2 layer associated with the high mechanical strength of the CS. Furthermore, heat treatment above 800 °C was very effective in increasing the Jc of these tapes. The heat-treated CS-sheathed tapes showed Jc values of 10 kA/cm2 at 4.2 K and 7.5 T and still above 2 kA/cm2 at 10 T. These values are the highest ever reported for MgB2 tapes. An extrapolation to 0 T in the Jc-B data gave about 1 MA/cm2, which was independent of the sheath materials. Microstructural observations suggest that the high Jc and the small field dependence of the Jc properties of the CS-sheathed tapes can be ascribed to the improved grain connectivity and grain alignment produced by the high mechanical strength of CS.

Gallium–indium–oxide films (GaxIn2⊟xO3), where x = 0.0–1.1, were grown by low-pressure metalorganic chemical vapor deposition using the volatile metalorganic precursors In(dpm)3 and Ga(dpm)3 (dpm = 2,2,6,6-tetramethyl-3,5-heptanedionato). The films were smooth (root mean square roughness = 50–65 Å) with a homogeneously Ga-substituted, cubic In2O3 microstructure, randomly oriented on quartz or heteroepitaxial on (100) yttria-stabilized zirconia single-crystal substrates. The highest conductivity of the as-grown films was found at x = 0.12, with σ = 700 S/cm [n-type; carrier density = 8.1 × 1019 cm⊟3; mobility = 55.2 cm2/(V s); dσ/dT<0]. The optical transmission window of such films is considerably broader than that of Sn-doped In2O3, and the absolute transparency rival or exceeds that of the most transparent conductive oxides known. Reductive annealing, carried out at 400–425 C° in a flowing gas mixture of H2 (4%) and N2, resulted in increased conductivity (σ 1400 S/cm; n-type), carrier density (1.4 × 1020 cm⊟3), and mobility as high as 64.6 cm2/(V s), with little loss in optical transparency. No significant difference in carrier mobility or conductivity is observed between randomly oriented and heteroepitaxial films, arguing in combination with other data that carrier scattering effects at high-angle grain/domain boundaries play a minor role in the conductivity mechanism.