The effect of lanthanum (La) addition on the piezoelectric properties of lead zirconate titanate–lead zinc niobate (PZT–PZN) was investigated. When small amounts of La were added to the 0.82PZT–0.18PZN, the phase of the specimen changed from rhombohedral to tetragonal and the grain size was steadily reduced. To retain the morphotropic phase boundary (MPB) condition of the specimens with La contents of up to 4 mol%, the Zr/Ti ratio in the PZT was increased to 54/46. When more than 5 mol% La was added, pyrochlore phases were formed, and the piezoelectric properties were reduced. Therefore, the optimum piezoelectric properties (d33 = 545 pC/N, kp = 0.64, and s33 = 0.39% at 2 kV/mm) were observed in the specimen having MPB composition and with an La content of 4 mol%.

Vapor-grown carbon fibers and carbon micro-beads were produced in the absence of catalysts from a natural precursor, camphor, by a thermal chemical vapor deposition process, at different temperatures in an argon medium. Scanning and transmission electron microscopy, Raman spectra, and electrical conductivity studies were used to characterize these fibers. It was observed that cylindrical fibers (diameter ∼3 μm) were obtained at 1033 K and rippled fibers (diameter ∼5 μm) were formed at 1273 K while carbon beads (diameter ∼0.5–1 μm) were formed at 1173 K. It is proposed that agglomeration of carbon beads predominate at pyrolysis temperature greater than 1173 K, resulting into rippled type fibers.

The microstructural features of highly damaged 4H–SiC implanted with Al22+ ions at 450 K were studied using transmission electron microscopy (TEM) and electron energy-loss spectroscopy. Conventional TEM images reveal that the crystalline SiC domains are highly strained/distorted when the relative disorder on the Si sublattice ranges between about 0.4 and 0.8, as determined by Rutherford backscattering spectrometry in channeling geometry. As the relative disorder approaches 1.0, the high strain contrast appears to be relieved, and localized amorphized domains are observed. Plasmon-loss energy shows a red shift following the implantation, and the magnitude of the red shift increases with increasing relative disorder. Based on the red shift, the estimated volume expansion is approximately 8% for highly damaged crystalline SiC and approximately 16% for the amorphous state. Energy-loss near-edge-structure of both the C and Si K edge reveals the existence of Si–Si and C–C bonding in the Al22+ implanted SiC.

Partial-melt processing of Bi2+xSr2-x-yCa1+yCu2O8+δ (Bi-2212) thick-film conductors with additions of nanophase Al2O3 was studied for dual purposes of increasing flux pinning and inhibiting Sr—Ca—Cu—O phase defect formation. Nanophase Al2O3 (<50% mole fraction) was added to Bi:Sr:Ca:Cu:O powders with four different compositions: three with Bi:Cu approximately 2:2 and one (Bi2Sr2.38Ca1.15Cu2.92O9.7+δ) closer to the ideal Bi-2223 composition. The effect of Al2O3 addition on film microstructural and superconducting properties was studied for a range of partial-melt temperatures (865 to 900 °C). Results were compared to Al2O3-free films with compositions lying within the single-phase solid-solution 2212 region. Nanophase Al2O3 reacted with 2212-type precursors to form a composite of micron size or smaller particles of solid-solution (Sr,Ca)3Al2O6 in a solid-solution 2212 superconducting matrix. The Ca content of the (Sr,Ca)3Al2O6 particles formed approximated that of the 2212 precursor (≤6% mole fraction difference). Addition of 6–25% volume fraction of (Sr,Ca)3Al2O6 to Bi-2212 (by reaction between Al2O3 and Bi-2212) only slightly reduced superconducting transition temperatures and c-axis texturing; however this addition improved film quality by reducing Sr—Ca—Cu—O defect volume fraction by factors of 2 to 6 and significantly increased the critical current density by over one order of magnitude for 0 to 2 T applied fields at 20 to 30 K.

Amorphous thin films of different Al–Fe compositions were produced by plasma/vapor quenching during pulsed laser deposition. The chosen compositions Al72Fe28, Al40Fe60, and Al18Fe82 correspond to Al5Fe2 and B2-ordered AlFe intermetallic compounds and α–Fe solid solution, respectively. The films contained fine clusters that increased with iron content. The sequences of phase evolution observed in the heating stage transmission electron microscopy studies of the pulsed laser ablation deposited films of Al72Fe28, Al40Fe60, and Al18Fe82 compositions showed evidence of composition partitioning during crystallization for films of all three compositions. This composition partitioning, in turn, resulted in the evolution of phases of compositions richer in Fe, as well as richer in Al, compared to the overall film composition in each case. The evidence of Fe-rich phases was the B2 phase in Al72Fe28 film, the L12- and DO3-ordered phases in Al40Fe60 film, and the hexagonal ε–Fe in the case of the Al18Fe82 film. On the other hand, the Al-rich phases were Al13Fe4 for both Al72Fe28 and Al40Fe60 films and DO3 and Al5Fe2 phases in the case of Al18Fe82 film. We believe that this tendency of composition partitioning during crystallization from amorphous phase is a consequence of the tendency of clustering of the Fe atoms in the amorphous phase during nucleation. The body-centered cubic phase has a nucleation advantage over other metastable phases for all three compositions. The amorphization of Al18Fe82 composition and the evolution of L12 and ε–Fe phases in the Al–Fe system were new observations of this work.

The growth of tin whiskers formed on sputtered tin layers deposited on brass was studied using electron microscopy. The occurrence of whiskers appeared to be largely independent of the macroscopic stress state in the film; rather it was microscopic compressive stresses arising from the formation of an intermetallic phase that appeared to be the necessary precursor. Whisker morphology was a result of whether nucleation had occurred on single grains or on multiple grains. In the latter case, the whiskers had a fluted or striated surface. The formation of whiskers on electron transparent samples was demonstrated. These samples showed the whiskers were monocrystalline and defect free, and that the growth direction could be determined.

Dielectric ceramics in the system (Zn1−xNix)TiO3, x = 0 to 1 were synthesized by the solid-state reaction route. The phase distribution, microstructure, and dielectric properties were characterized using powder x-ray diffraction analysis, electron microscopy, and microwave measurement techniques. Three phase composition regions were identified in the specimens sintered at 1150 °C: [spinel + rutile] at 0 ≤ x ≤ 0.5, [spinel + ilmenite + rutile] at 0.5 < x ≤ 0.8, and [ilmenite] phase at 0.8 < x ≤ 1. For the 0 ≤ x ≤ 0.5 region, the amount of Ti-rich precipitates incorporated into the spinel phase decreased with the Ni content at 0 ≤ x ≤ 0.5, with a concomitant increase of the rutile phase. The microwave dielectric properties depended on the phase composition and volume according to the three typical phase regions, where the relative amount of rutile to the spinel or ilmenite determined the dielectric properties. The dielectric constant as a function of Ni addition was modeled with a Maxwell mixing rule. An optimum phase distribution was determined in this system with dielectric constant of 22, a Q × f of 60,000, and a low temperature coefficient of the resonant frequency.

Effects of Ni and Au from Ni/Au substrate metallizations on the interfacial reactions of solder joints in flip-chip packages during long-term thermal aging were systematically investigated. It was found that both Au and Ni influenced the solid-state interfacial reactions, underbump metallization (UBM), and intermetallic compound (IMC) evolution. Because large amounts of Ni could incorporate into IMC to form a multicomponent (Cu, Ni)6Sn5 phase during assembly reflow, while Au could only affect the reaction during thermal aging through the reconfiguration of AuSn4 phase, Ni had stronger effects on solid-solution type Ni–V UBM consumption than Au. It was found that the UBM consumption process was faster in the eutectic SnPb solder system than that in the SnAgCu solder system during aging. A porous structure was formed in the UBM layer after Ni in UBM was consumed. Electrical resistance of flip-chip packages increased significantly after the porous structure reached certain extents. The results showed that the diffusion process of Ni from UBM and Sn from solder in the presence of (Cu, Ni)6Sn5 or (Ni, Cu)3Sn4 phase at solder joint interfaces could be much faster than that in the case of binary Cu6Sn5 or Ni3Sn4 IMC.

The creep behavior of mullite was studied under different stresses and in the temperature range 1200–1450 °C, and an analysis of creep curves was proposed. The study of creep behavior of mullite at high temperatures clearly indicates that this material exhibits concurrent creep and slow crack growth. An effective transition stress exists at each temperature. The analysis takes account of the total creep curve; in particular, the primary and stationary stages. It is now possible to determine by extrapolation the steady-state creep rate for specimens that break in the transient domain during tests. Thus, one can verify the influence of the stress on the steady-state creep rate over a wide stress range. On the other hand, this analysis clearly indicates the existence of two values of the activation energy around 1300 °C; this suggests a change of creep mechanism at this temperature.

Improvements in the tribological properties of pure aluminum and “aeronautical” alloy AA7075-T651 were obtained by oxygen-ion implantation [(0.7 to 5) × 1017 O/cm2, 30 keV] using our pulsed electron cyclotron resonance plasma source. This oxygen plasma source ion implantation process produced oxide nanoprecipitates that enhanced the hardness up to three times in the surface layer and caused reductions in the scratch depths and the friction coefficients by similar factors. A spectrum of tribological properties was obtained depending on temperature and ion dose. Temperature measurement and control were obtained through an integrated thermocouple and by changing the duty-cycle of the microwave source. The oxygen content and the depth-resolved chemical composition were measured and optimized using x-ray photoelectron spectroscopy (XPS) combined with Ar-ion etching. The tribological properties were investigated by (i) depth-sensing nanoindentation for hardness and Young's modulus, (ii) scratching and scratch-depth measurement via atomic force microscopy (AFM), and (iii) friction force measurements using AFM. Low-temperature (≤160°C) implantations with optimal O-ion doses produced, in both pure and alloyed Al, an approximately 50-nm-thick, smooth, and extremely fine-grained metal–alumina nanocomposite. The resulting surface was hard and stiff but nonbrittle and displayed high scratch resistance and low friction. High-temperature (~430°C) implantation had different effects on pure Al and AA7075. On pure Al, it produced a very hard but brittle Al2O3 layer for which yield points (displacement excursions) were observed at critical load values in the nanoindentation force–displacement curves. On AA7075, XPS chemical profiling revealed an effect of extreme Mg surface segregation and complete Al surface depletion; MgO crystallites formed a rather rough but surprisingly thick layer (>100 nm). The resulting AA7075 surface showed a hardness increase that was substantial but slightly smaller than that obtained at low temperature.

Microstructures of a TiC/Ni80Cr20 cermet, subjected to single high-current-density electropulsing, were characterized by x-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. Under the electropulsing, the shift of NiCr peaks versus the reverse change of TiC counterparts illustrates that the treatment gives rise to strong thermal stress impacting on the cermet. The stress, accompanied by the transient rise of temperature, led to microstructural evolutions of the cermet. Some nanostructured TiC grains, consisting of many nanocrystallites with small-angle grain boundaries, developed during electropulsing. Also, many regions teemed with coexisting nanosized TiC and NiCr crystallites, which possessed good bonding. Within the NiCr regions, large amounts of deformation twins were produced by the electropulsing.

Biaxially oriented Ba1−xSrxTiO3 (BST) thin films were fabricated under a highly reducing atmosphere (oxygen partial pressure ∼10−18 atm) on base metal substrates (〈100〉 Ni) using a fluorinated chemical solution deposition method. The degree of film orientation was investigated with respect to film annealing temperature and composition (x = 0, 0.33, 0.5, 0.67, 1). The solution synthesis route included fluorinated solvents, donor-dopants, and chelating agents for control of orientation, defect chemistry, and morphology. Free-energy and phase diagrams guided solution development using halide addition to avoid intermediate BaCO3 formation and instead produce direct crystallization of BaTiO3-type materials from BaF2. The degree of (200) orientation of BST films deposited on 〈100〉 Ni substrates displayed a compositional dependence for 0 < x < 1, with a maximum orientation Lotgering factor approaching unity. Low-temperature (500 °C) crystallization of highly oriented films was demonstrated for solution-derived BST on Ni, which may have enabling materials integration implications for capacitors and other applications.

Near-threshold ultraviolet-laser (355 nm) ablation of 125-μm thick Kapton films was investigated in detail using x-ray photoelectron spectroscopy. Different from the irradiation at higher fluences, the contents of the oxygen, amide group, and C–O group on the ablated surface increased with an increase in the pulse number, whereas the carbon contents decreased, although the contents of the nitrogen and the carbonyl group (C = O) decreased slightly. This implied that there was no carbon-rich residue on the ablated surface. Near the ablation threshold, only photolysis of the C–N bond in the imide rings and the diaryl ether group (C–O) took place due to a low surface temperature rise, and the amide structure and many unstable free radical groups were created. Sequentially, the oxidation reaction occurred to stabilize the free radical groups. The decomposition and oxidation mechanism could explain the intriguing changes of the chemical composition and characteristics of the ablated surface. In addition, the content of the C–O group depended on the opposite factors: the thermally induced decomposition of the ether groups and the pyrolysis of the Caryl–C bond. Upon further irradiation, the cumulative heating may induce the breakage of the Caryl–C bond and enhance the oxidation reaction, resulting in an increase of the content of the C–O group.

An experimental study of the inelastic deformation of bulk metallic glass Zr41.2Ti13.8Cu12.5Ni10Be22.5 under multiaxial compression using a confining sleeve technique is presented. In contrast to the catastrophic shear failure (brittle) in uniaxial compression, the metallic glass exhibited large inelastic deformation of more than 10% under confinement, demonstrating the nature of ductile deformation under constrained conditions in spite of the long-range disordered characteristic of the material. It was found that the metallic glass followed a pressure (p) dependent Tresca criterion τ = τ0 + βp, and the coefficient of the pressure dependence β was 0.17. Multiple parallel shear bands oriented at 45° to the loading direction were observed on the surfaces of the deformed specimens and were responsible for the overall inelastic deformation.

The evolution of an interfacial microstructure between Cu/Ni/Au bond-pad metallization and Pb-free or Pb-containing solder bumps during solid-state aging was investigated. A distinctive difference between the Pb-containing and Pb-free solder bumps was observed. A continuous (Au,Ni)Sn4 intermetallic compound layer was readily detected in the Pb-containing solder bump on the bond-pad. No such layer exists in the Pb-free case; instead a large number of (Au,Ni)Sn4 particles scatter in the bulk of the solder. The different morphologies of the (Au,Ni)Sn4 have been explained on the basis of the contact angle in Young's equation and of the growth of a flat layer by ripening. A simple kinetic analysis of ripening between a set of monosize spheres and a flat surface is given to describe the layered growth having a time dependence around 0.5.

A silica-colloidal template approach was used to prepare monodisperse nanospheres of TiO2. Close-packed arrays of silica spheres were infiltrated with a sucrose precursor used as a source of carbon. The infiltrated sucrose was carbonized by calcination at 800 °C in flowing argon. After removal of the silica spheres by washing with HF, a porous carbon replica remained. The resulting pores in the replica were then filled with a chloroform solution of titanium alkoxide. Nanospheres of TiO2 approximately 200 nm in diameter were obtained after calcination of the organic component at 600 °C in an argon atmosphere and subsequent sintering in air at 700 °C.

This study evaluated a novel approach for acoustic emission (AE) monitoring of nanoindentation. The technique utilizes a miniature AE sensor integrated into a calibrated diamond indenter tip on a commercial nanoindentation system. The evaluation focused on the yield -point phenomenon in W (100); MgO (100); and sapphire C (0001); R (1012); A (1210); and M (1010) single-crystal surfaces. The minimum amount of elastic energy release sufficient to produce AE signal detectable with the indenter tip sensor was nearly two orders of magnitude lower than the minimum energy level required for conventional AE sensors. Wave forms detected with the indenter tip sensor were independent of sample size. A linear relationship between released elastic energies and the corresponding AE energies was observed for all three evaluated materials. The scaling coefficient of the linear relationship was independent of indenter tip size/shape and indentation depth. The differences between the mechanisms of the initial stages of plasticity for the various crystallographic orientations of sapphire were reflected in the following aspects of AE activity: detection of a specific type of AE wave form that correlated to the presence of linear surface features near the indentation sites; AE signal associated with the yield point, consisting either of one or two distinct wave forms; and presence or absence of AE signals after the yield point. The possibility of plasticity onset in sapphire involving both slip and twinning is discussed.

We fabricated melt-processed (Sm0.33Eu0.33Gd0.33)Ba2Cu3Oy superconductors with fine Gd2BaCuO5 (Gd-211) particles and studied microstructure and magnetic properties as a function of the Gd-211 content and the initial particle size. Microstructure observation by scanning electron microscopy and transmission electron microscopy confirmed the presence of submicron secondary-phase particles and nanometer-sized RE1+xBa2-xCu3Oy (x ≫ 0) clusters. At 77 K, the critical current densities of 107 and 83 kA/cm2 were achieved at 0 T (self-field) and 2.2 T, respectively (superconducting quantum interference device data).

Alkali activation of dehydroxylated kaolin or clay yielded high-strength polymeric materials, so-called geopolymers. They were synthesized by mixing the aluminosilicate with solutions of sodium metasilicate and KOH followed by adding 45 wt.% of ground-granulated blast furnace slag. The influence of the aluminosilicate source, its activation temperature, and the order of mixing raw materials were studied on the workability of the blending paste, the microstructure, and the Vickers hardness of the geopolymer samples. The polymeric material is completely amorphous according to x-ray diffraction. Solid-state 27Al and 29Si magic-angle-spinning nuclear magnetic resonance showed that the geopolymer consists of AlO4 and SiO4 tetrahedra linked together through a polymeric network constituted by branched entities SiQ4(4Al) and SiQ4(3Al), but also by less-polymerized silicates SiQ1 and SiQ2. Scanning electron microscopy showed a homogeneous polymeric gel matrix containing unreacted slag (and quartz) grains; thermogravimetric analysis and differential scanning calorimetry exhibited a high content of water and an elevated melting point (1260°C). Vickers hardness values are in the range of 200 MPa.

Hafnium oxide thin films for use in a gate dielectric were deposited at 300 °C on p-type Si(100) substrates using a Hf[OC(CH3)3]4 precursor in the absence of oxygen by plasma-enhanced chemical vapor deposition. A comparison of films deposited in the absence and presence of oxygen indicated that oxygen was an important determinant in the electrical properties of HfO2 films, which were subsequently annealed in N2 and O2 ambients. The capacitance equivalent oxide thickness of the as-deposited Pt/HfO2/Si capacitor was approximately 17 Å and abruptly increased at an annealing temperature of 800 °C in both N2 and O2 ambients. The hysteresis of the as-deposited gate dielectric was quite small, about 40 mV, and that of the gate dielectric annealed at 800 °C in an O2 ambient was reduced to a negligible level, about 20 mV. The interface trap density of the Pt/HfO2/Si capacitors was approximately 1012 eV−1 cm−2 near the silicon midgap. The leakage current densities of the as-deposited Pt/HfO2/Si capacitor and those annealed at 800 °C in N2 and O2 were approximately 8 × 10−4, 8 × 10−5, and 3 × 10−7 A/cm2 at –1 V, respectively.