We examined the interfacial morphology and shear deformation of flip chip solder joints on an organic substrate (chip-on-board). The large differences in the coefficients of thermal expansion between the board and the chip resulted in bending of the 1-cm2 chip with a curvature of 57 ± 12 cm. The corner bump pads on the chip registered a relative misalignment of 10 μm with respect to those on the board, resulting in shear deformation of the solder joints. The mechanical properties of these solder joints were tested on samples made by sandwiching two Si chips with electroless Ni(P) as the under-bump metallization and 25 solder interconnects. Joints were sheared to failure. Fracture was found to occur along the solder/Ni3Sn4 interface. In addition, cracking and peeling damages of the SiO2 dielectric layer were observed in the layer around the solder balls, indicating that damage to the dielectric layer may have occurred prior to the fracture of the solder joints due to a large normal stress. The failure behavior of the solder joints is characterized by an approximate stress analysis.

Real-time x-ray reflectivity and diffraction measurements under in situ sputtering conditions were employed to study the growth behavior of LaNiO3 thin films on a Si substrate. Our results clearly show there is a transition layer of 60 Å, which grew in the first 6 min of deposition. The in situ x-ray-diffraction patterns indicated that this transition layer is amorphous. Subsequently, a polycrystalline overlayer grew as observed from the in situ x-ray reflectivity curves and diffraction patterns. Nucleation and growth took place on this transition layer with random orientation and then the polycrystalline columnar textures of (100) and (110) grew on the top of this random orientation layer. By comparing the integrated intensities of two Bragg peaks in the plane normal of x-ray diffraction, it was found that a crossover of the growth orientation from the ⟨110⟩ to the ⟨100ߩ direction occurred and the ability of (100) texturization enhanced with increasing film thickness beyond a certain critical value.

The oxidation behavior and the effect of oxidation on the flexural strength of Si3N4/SiC nanocomposites were investigated. Parabolic weight gains, with respect to the oxidation time, were observed for all the specimens containing different amounts of SiC. However, the parabolic rate constant decreased with increasing SiC content. The main oxidation product, being in equilibrium with SiO2, was Y2Si2O7. The oxidation product became denser and retained more crystalline phase as the amount of SiC increased. The flexural strength of the nanocomposites increased by up to 40%, while that of pure Si3N4 decreased after oxidation at 1300 or 1400 %C for 100 h. This excellent oxidation resistance of Si3N4 nanocomposite was attributed to the enhancement of the crystallization of the oxidation product and the grain boundary phase by the SiC nanoparticles.

This paper supplies new interpretation of nanoindentation data for silicon, germanium, and gallium arsenide based on Raman microanalysis of indentations. For the first time, Raman microspectroscopy analysis of semiconductors within nanoindentations is reported. The given analysis of the load-displacement curves shows that depth-sensing indentation can be used as a tool for identification of pressure-induced phase transformations. Volume change upon reverse phase transformation of metallic phases results either in a pop-out (or a kink-back) or in a slope change (elbow) of the unloading part of the load-displacement curve. Broad and asymmetric hysteresis loops of changing width, as well as changing slope of the elastic part of the loading curve in cyclic indentation can be used for confirmation of a phase transformation during indentation. Metallization pressure can be determined as average contact pressure (Meyer's hardness) for the yield point on the loading part of the load-displacement curve. The pressure of the reverse transformation of the metallic phase can be measured from pop-out or elbow on the unloading part of the diagram. For materials with phase transformations less pronounced than in Si, replotting of the loaddisplacement curves as average contact pressure versus relative indentation depth is required to determine the transformation pressures and/or improve the accuracy of data interpretation.

Quasicrystals (QCs) are known to exhibit unique properties as a result of their unique quasiperiodic structure. Real quasicrystalline (QC) materials, however, may exhibit complex phase structures, and as a consequence, their properties may differ from expectations. In the present work, QC coatings of the Al–Cu–Fe, Al–Cu–Fe–Cr, and Al–Pd–Mn systems were prepared by a plasma spray process, followed by heat treatments in the range 500–800 °C. The phase structure and evolution of the coatings were evaluated, and thermal diffusivity, hardness, and friction coefficient were measured. The presence of quasicrystalline and crystalline phases and their influence on these properties is systematically considered for the first time. Broadly, the coatings exhibit the properties expected of QC materials, low thermal diffusivity, high hardness, and low coefficients of friction, but it is also shown that these properties can be sensitive to the phase structure of the coatings. This suggests that phase structure may be manipulated by heat treatment to optimize the properties of QC coatings.

Experiments were performed to evaluate the mechanical and water barrier properties of corn-protein-based materials that were compression molded from thermoplastic resins. The influence of varying concentrations of water, glycerol, and octanoic acid was studied. At 0% relative humidity, the material exhibited a linear elastic deformation and a brittle fracture at any glycerol or octanoic acid content. Raising relative humidity from 0% to 97.3%, progressively decreased the tensile strength (from 24.1 to 2.2 MPa and 19.4 to 1.0 MPa), and the modulus of elasticity (from 1.67 to 0.03 GPa and 1.87 to 0.13 GPa), respectively, for the octanoic acid- or glycerol-plasticized materials. Increasing water content did not increase the tensile strain at break of the glycerol-plasticized material, whereas this parameter changed from 1.6 to 52.3% for octanoic-acid-plasticized material. This last material was waterproof during 21 h and its water transmission rate was then 0.05 mmolmm-2 s -1. Differences in water absorption were related to plasticizer solubility and material structure.

SrBi2Ta2O9 was synthesized by the modified polymeric precursor method using precursor reagents such as carbonate, nitrate, or oxide. The films were deposited onto Pt/Ti/SiO2/Si(100) substrates by spin coating and crystallized at temperatures ranging from 700 to 800 °C in air. Microstructural and phase evaluation were followed by grazing incidence x-ray diffraction, scanning electron microscopy, and atomic force microscopy. The films displayed rounded grain structures with a superficial roughness of approximately 10 nm. The dielectric constant values were 362 and 617 for films treated at 700 and 800 °C, respectively. The remanent polarization and coercive field were 12.3 μC/cm2 and 61 kV/cm and 18.48 μC/cm2 and 47 kV/cm for the film treated at 700 and 800 °C, respectively. This method generally allows for the use of readily available reagents such as oxides, carbonates, or nitrate as cation sources, with the added advantage that it requires no special apparatus or atmosphere control.

We investigated the photoluminescence spectra as well as the crystal structure and optical energy gaps of the Zn1-xCdxAl2Se4 single crystals grown by the chemical transport reaction method. It was shown from the analysis of the observed x-ray diffraction patterns that these crystals have a defect chalcopyrite structure for a whole composition. The lattice constant a increases from 5.5561 A for x = 0.0 (ZnAl2Se4) to 5.6361 A for x = 1.0 (CdAl2Se4) with increasing x, whereas the lattice constant c decreases from 10.8890 A for x = 0.0 to 10.7194 A for x = 1.0. The optical energy gaps at 13 K were found to range from 3.082 eV (x = 1.0) to 3.525 eV (x = 0.0). The temperature dependence of the optical energy gaps was well fitted with the Varshni equation. We observed two emission bands consisting of a strong blue emission band and a weak broad emission band due to donor–acceptor pair recombination in the Zn1-xCdxAl2Se4 for 0.0 ⩽ x ⩽ 1.0. These emission bands showed a red shift with increasing x. The energy band scheme for the radiative mechanism of the Zn1-xCdxAl2Se4 was proposed on the basis of the photoluminescence thermal quenching analysis along with the measurements of photo-induced current transient spectroscopy. The proposed energy band model permits us to assign the observed emission bands.

Superconducting YBa2Cu3O7−x (YBCO) thin films grown by pulser-laser-assisted deposition were studied by micro-Raman spectroscopy. This technique was used to estimate the epitaxial quality of the films in terms of the presence of c-axis- and a-axis-oriented areas. The advantage of micro-Raman spectroscopy is its high lateral resolution, and this was used to study the homogeneity of the films at submicrometric level. Local structural changes from a large number of intergrain regions were revealed by changes of the Raman parameters. For example, the aggregation of a-axis-oriented grains formed needle-shaped macrograins. Micro-Raman measurements suggest that these grains were seeded at large-angle grain boundaries in c-axis-oriented areas.

Anodic conversion films of vanadium oxides on vanadium were potentiodynamically generated at high voltages in an acetate electrolyte system. The microstructure of the anodic VOx coatings was characterized by surface and solid-state techniques such as scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. An amorphous structure is proposed in which network-forming [VO4] tetrahedra in various degrees of condensation are connected by distorted [VO5] and [VO6] units. Such polyhedra lead to the formation of nanocrystalline phases of stoichiometric and substoichiometric vanadium oxides, which were observed in the amorphous phase.

Zinc powder reacts with equivalent elemental selenium in solvent ethylenediamine at 120 °C for 6 h to form a complex, which is converted to ZnSe nanoparticles by pyrolysis or protonization. X-ray diffraction results suggest that the as-formed products have wurtzite structure. Transmission electron microscopy observation show that particles with spherical and laminar morphology were produced by pyrolysis and protonization, respectively. The formation of ZnSe nanoparticles is also investigated by infrared and thermal analysis.

Tests with actual ground water from Hanford site, and fundamental studies of 2Na+ → Sr2+ exchange equilibria revealed that a synthetic clay is extremely selective for 90Sr with a high capacity for uptake. Comparative studies with existing Sr selective ion exchangers clearly revealed that the present synthetic clay exhibited the best performance for 90Sr removal from actual ground water collected from three different locations at Hanford. This novel Sr ion sieve is expected to be useful for the decontamination of the environment after accidental release and contamination with 90Sr.

A solid metal-bearing precursor route has been used to fabricate Ag-sheathed Bi2Sr2Ca1Cu2O8±x (2212) superconducting tapes. Intimately mixed Bi2O3–Sr–Ca–Cu-bearing powder was first synthesized by a two-stage, high-energy/low-energy mechanical alloying process. The powder was then packed into silver tubes and formed into tapes by drawing and biaxial (Turk's-head) rolling. The precursor tapes were oxidized and converted into Ag-sheathed 2212 by heat treatment at 350–860 °C in oxygen. Subsequent annealing at 897 °C, followed by slow cooling and subsolidus annealing at 850 °C, yielded 2212 grains with enhanced c-axis alignment. The resulting tapes exhibited average and maximum transport Jc (4.2 K, self-field) values of 3.2 × 104 and 6.8 × 104 A/cm2, respectively.

Highly ordered ZnO nanowire arrays were fabricated by oxidizing the metal Zn that was electrodeposited in the pores of anodic alumina membranes (AAMs). The diameters of ZnO nanowires range from 15 to 90 nm. Atomic force microscope, x-ray diffraction, and transmission electron microscopy observations indicate the polycrystalline ZnO nanowires were uniformly assembled into the hexagonally-arranged nanochannels of the AAM. A green emission band caused by the singly ionized oxygen vacancy in the ZnO nanowires was also reported.

Nanocrystalline-diamond particles were produced in the form of a coating by depositing Ni-clad graphite powder in a high-velocity thermal spray experiment. Particles were accelerated to impact and formed a thick film (>20 μm) on a steel substrate, with the high-velocity impact generating a shock wave, which propagates through the particle and the underlying deposits. Transmission electron microscopy revealed that this deposit contains cubic diamond nanocrystals having a size range of 5 to 10 nm in graphite. In addition to diamond, it was observed that a portion of the deposit contains “closed-curved graphite.”

Single-point diamond turning tests were carried out in two different [001]-oriented semiconductors, InSb and Si single crystals. The analysis of the conditions in which the machining is in ductile or brittle mode indicates that the plasticity presented by semiconductor crystals during micromachining can be correlated to the value of the transition pressure. It is shown that the ductility presented by different semiconductor single crystals is inversely related to the transition pressure value of the material.

The first part of this article reports on the reactive synthesis and characterization of Al–Ti–C alloys intended as master alloys for aluminum grain refining. The alloys were produced from elemental powders by the thermal explosion mode and analyzed with x-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. Parameters were the titanium concentration (15 and 30 wt%) and the Ti/C ratio (9/1, 20/1, and 120/1) in the reactant powder mixture and the cooling rate after the reactive synthesis (1 and 120 °C/min). Full conversion of titanium and carbon into Al3Ti and TiC was achieved for the 30 wt% Ti mixtures but not for the 15 wt% Ti mixtures where the reaction was not exothermic enough. The Ti/C ratio did not affect the phase composition after reactive synthesis in the 30 wt% Ti alloys and could be used to tailor the microstructure of the alloy. The formation of Al4C3 was suppressed with a high cooling rate after the exothermic formation reactions.

Material characterization of sol-gel-derived and electrodeposited MnO2 thin films showed that their microstructures are highly porous in nature. While sol-gel-derived films are nanoparticulate, electrodeposited films showed macropores of random and irregular platelike structures, comprising much denser surface layers and highly porous underlying layers. On the basis of calculated and theoretical density values of 1 and 4.99 g/cm3, respectively, the porosity of sol-gel-derived MnO2 films was determined to be as high as 80%, which is substantially higher than electrodeposited films at 67%. Apart from their higher specific capacitance, sol-gel-derived MnO2 films appeared to exhibit higher cycling stability and reversibility than electrodeposited MnO2 films. In the case of sol-gel films, thinner films appeared to exhibit higher cycling stability than thicker films. There was less alteration in surface morphology and microstructure, and the rate of loss in charge-storage capacity upon voltammetric cycling was not as significant for sol-gel MnO2 thin films

Homogenous (Bi3Pb)Sr3Ca3 (Cu4−nCrn)Ox (n 4 0 to 0.20) type glassy precursors become high-Tc superconductors by annealing at 840 °C. The suppression of Tc with increase of Cr concentration supports the pair-breaking mechanism. The feeble semiconducting behavior shown by the doped samples above their respective Tc values followed Mott's variable range hopping conduction mechanism. Like Ti- and Fe-doped samples, studied earlier, the thermoelectric power (TEP) of the present Cr-containing sample showed small positive peak above Tc, which was considered to be associated with the phonon-drag effect. The linear part of the temperature-dependent TEP (above Tc) well fitted the two-band model.

A promising approach to control Pb stoichiometry during crystallization of sol-gel-derived lead zirconate titanate (PZT) layers is presented. Pyrolyzed layers were encapsulated in a quartz ampoule containing PbZrO3 powder and crystallized in a lamp furnace. For moderate heating rates, the PbO ambient created by the powder resulted in a pronounced sharpening of the preferential (111) texture, while the remanent polarisation Pr increased by 50% compared to nonencapsulated samples. A significant reduction of the coercive field was seen for layers crystallized under PbO ambient, reflected in a lowering of the switching voltage by 0.5 V compared to standard hotplate crystallized films. The results highlighted the key role of Pb stoichiometry control for further lowering the switching voltage of PZT films.