The structural model for metallic glasses and the topological instability criterion for multicomponent alloy systems have been combined to formulate a design protocol for bulk metallic glasses (BMGs). New Ni-Nb-Zr bulk metallic glasses with high corrosion resistance have been discovered. The experimental results in literature also support the use of this approach as a practically efficient method to select bulk metallic glass-forming compositions.

In the course of a systematic field study, anisotropic alkali and alkaline earth vanadates have been accessed through a straightforward, one-step hydrothermal process. They are formed quantitatively from V2O5 and alkali- or alkaline earth halide solutions after a few days of autoclave treatment in the temperature range between 100 and 220 °C. The presence of ionic additives leads to an interplay between the formation of isotropic crystalline phases and the production of fibrous oxide materials, such as a novel magnesium vanadate. The influence of the hydrothermal parameters and of the alkali/alkaline earth halides on the emerging phases and morphologies has been investigated in the course of a systematic study. The results are compared with other vanadate- and transition metal oxide-based hydrothermal systems, and the emerging trends are discussed with respect to the development of predictive synthetic concepts for nanostructured vanadium oxides.

We investigated the role of particle potential symmetry on self-assembly by Monte Carlo simulation with a particular view toward synthetically creating structures of prescribed form and function. First, we established a general tendency for the rotational potential symmetries of the particles to be locally preserved upon self-assembly. Specifically, we found that a dipolar particle potential, having a continuous rotational symmetry about the dipolar axis, gives rise to chain formation, while particles with multipolar potentials (e.g., square quadrupole) having discrete rotational symmetries lead to the self-assembly of “random surface” polymers preserving the rotational symmetries of the particles within these sheet structures. Surprisingly, these changes in self-assembly geometry with the particle potential symmetry are also accompanied by significant changes in the thermodynamic character and in the kinetics of the self-assembly process. Linear chain growth involves a continuous chain growth process in which the chains break and reform readily, while the growth of the two-dimensional polymers only occurs after an “initiation” or “nucleation” time that fluctuates from run to run. We show that the introduction of artificial seeds provides an effective method for controlling the structure and growth kinetics of sheet-like polymers. The significance of these distinct modes of polymerization on the functional character of self-assembly growth is illustrated by constructing an artificial centrosome structure derived from particles having continuous and discrete rotational potential symmetries.

The influence of different borazinic precursors on mesoporous boron nitride synthesis by using a nanocasting process of a mesoporous CMK-3 carbon is presented. Two borazinic precursors, the tri(methylamino)borazine (MAB) and the tri(chloro)borazine (TCB), have been converted to boron nitride (BN) inside the mesopores of a CMK-3 carbon mesoporous template by using thermal or chemical polycondensation processes. Ordered mesoporous boron nitride with a specific surface area around 800 m2/g, a mesoporous volume around 0.6 cm3/g, and a pore-size distribution located at 6 nm in diameter was synthesized by thermal condensation of a molecular MAB precursor. In addition, chemical condensation of TCB led to a disordered mesoporous boron nitride.

Luminescence properties of a series of samples of Y2O3:Eu+3 red phosphor of particle sizes ranging from 50 to 300 nm were investigated as a function of time to decipher the long-standing mystery of the effect of reduction of particle size on the luminescence efficiency of the phosphor. The samples were found to lose luminescence efficiency and suffer a change in the excitation profile with time. Infrared studies showed that although the samples at their freshly prepared stage were almost free from contaminated water, on aging in air at room temperature, they absorbed the latter. The phenomenon of hydration-induced coupling of the excitonic state of Y2O3 with one of its Fu modes was detected in the case of the aged sample, which was shown to be instrumental in introducing newer nonradiative channels in the system. Because of larger surface-to-volume ratio, the effect was most pronounced in the case of nanocrystalline samples.

In this work, the shear strengths and interfacial reactions of Sn–8Zn–3Bi and Sn–8Zn–1Bi (wt%) solders with Au/Ni/Cu ball grid array (BGA) pad metallization were systematically investigated after multiple reflows. The peak reflow temperature was fixed at 230 °C. After the shear test, fracture surfaces were investigated using a scanning electron microscope equipped with an energy dispersive x-ray spectrometer. Cross-sectional studies of the interfaces were also conducted to correlate with the fracture surfaces. Two failure modes, ball cut and pad lift, were assessed for the different solders and reflow cycles. It was found that the shearing forces of both the Sn–Zn–Bi solder joints tended to increase slightly with an increase in the number of reflow cycles due to augmentation of the shearing area. A layer-type spalling of the interfacial intermetallic compounds (IMCs) was observed very early in the liquid-state reaction for the solder alloys. The active nature of the Zn confirmed an instant reaction zone at the interface to maintain the bonding between the solder and the substrate.

A solvothermal method was used to prepare zirconia and yttria-stabilized zirconia (YSZ) particles using zirconium hydroxide and yttrium hydroxide particles as precursors and ethanol or isopropanol as reaction media. The particle properties were characterized with x-ray diffractometry, scanning electron microscopy, transmission electron microscopy, thermal analysis, laser particle-size analysis, nitrogen adsorption (Brunauer–Emmett–Teller method) and Zeta potential analysis. Cubic/tetragonal ZrO2 and YSZ nanocrystals with crystallite size around 5 nm were obtained. The effect of different hydroxide precursors, attrition milling of hydroxide precursors, solvothermal processing conditions, and mineralizer was investigated and discussed by referring to the crystallization process of zirconium hydroxides.

Drag reduction (DR) agents are used in several ppm concentrations to accelerate significantly the flow through conduits in oil pipelines, oil well operations, flood water disposal, fire fighting, field irrigation, transport of suspensions and slurries, sewage systems, water heating and cooling systems, airplane tank filling, marine systems, and also in biomedical systems including blood flow. The drag reduction agents are typically high molecular mass polymers; in industrial applications they undergo mechanical degradation in turbulent flow. We provide an equation that describes quantitatively the degradation, thus predicting drag reduction as a function of time and of the concentration of the drag reduction agent. We report how grafting a polymer on the backbone of a different polymer affects the drag reduction efficacy. Our grafted polymer undergoes degradation by flow turbulence more slowly and also provides high levels of drag reduction efficacy at much lower concentrations than homopolymers do.

The precipitation kinetics of growth and coarsening of γ′(Ni3Al) and θ (Ni3V) in Ni75AlxV25−x alloys were investigated by microscopic phase-field simulation incorporated with elastic interactions. For the elastic interactions, γ′ aligned along the 〈001〉 direction and θ aligned along the [100] direction, which resulted in plate shape. For the lower (x < 4, at.%) and higher (x > 6) content regions, the growth of first precipitates was dominant at the initial stage and then coarsening was dominant, but the growth and coarsening proceeded simultaneously for the second precipitates. The growth and coarsening of γ′ and θ were dominant, respectively, at the initial and late stages for middle content regions. In addition, dynamic scaling was analyzed in the two-phase systems. It was shown that the dynamic scaling regimes were attained simultaneously at late-stage coarsening for γ′ and θ, despite the different precipitation order.

The high temperature structural stability of nanograined NiCr alloys reinforced with nanoscale yttria and alumina dispersoids, fabricated by electron beam physical vapor deposition (EBPVD), was examined. The yttria particles coarsened very little and also inhibited grain growth in the matrix successfully, whereas the alumina dispersoids coarsened rapidly and were not as effective in restricting matrix grain growth. A hierarchy of phase transformations took place in the Al2O3 particles present as nano dispersoids in a nanograined NiCr matrix , on annealing. Coarsening of the alumina particles was accompanied by these phase transitions. The phase evolution is attributed to differences in free energies between the metastable and stable phases and a kinetic hierarchy in nucleation, brought about by structural and hence interfacial energy considerations.

The SrFeO3/SiO2/Si thin film system has been studied using transmission electron microscopy (TEM). The thin films of SrFeO3 were grown by pulsed laser deposition onto silicon substrates with a SiO2 buffer layer at room temperature (RT) and 700 °C and subjected to annealing for various periods of time at temperature T = 700 °C. Transmission electron microscopy characterization showed that the microstructure of the film deposited at room temperature contained crystalline and amorphous layers. Silicon diffusion into SrFeO3 films occurred at the SiO2 interface for the samples deposited at 700 °C and for those films annealed at 700 °C. The silicon diffusion-induced interfacial reactions resulted in the phase transformations and the growth of complex crystalline and amorphous phases. The principal compositions of these phases were Sr(Fe,Si)12O19, SrOx and amorphous [Sr-Fe-O-Si].

Cu, Pt, Ag, and Au were deposited on (100)-oriented ceramic substrates (SrTiO3, LaAlO3, and MgO). Over a wide range of temperatures (room temperature to 600 °C), Cu films were (100)-oriented and exhibited cube-on-cube epitaxy. Epitaxial Pt(100) films were obtained only at high temperature; oriented Pt(111) films were obtained at lower temperatures. Ag and Au were never obtained as purely (100)-oriented samples, although the amount of (100)-film increased with increasing temperature. Three-dimensional islands formed for all metals at higher temperatures, while flatter film surfaces developed at lower temperatures. At any given temperature, the surface roughness of films on SrTiO3(100) increased in the order Pt < Cu < Au < Ag. The variations in film structural characteristics are described well by considering the metals’ (i) surface/interfacial energies, (ii) surface energy anisotropies, and (iii) surface diffusion coefficients. Flat, epitaxial growth is promoted by low-energy interfaces, low surface energy anisotropies, and slow surface diffusion.

High quality, uniform PbZrxTi1-xO3(PZT) films were prepared on the 4 inch wafers by chemical solution deposition (CSD) of 1,3-propanediol precursors. Film uniformity was studied as a function of deposition conditions including spinning rates and co-solvents. Measurements of the surface tension and composition evolution during evaporation and spinning stages showed that the surface tension increases significantly when the co-solvent is nearly completely evaporated. The evaporation of the propanol co-solvent and volatile by-products occurs within the first 5 s of spinning giving rise to defects, whereas octanol is slowly evaporated during 60 s producing uniform coatings. Other co-solvents such as hexanol and pentanol produced uniform films as well. Therefore stabilization of the surface tension in the initial spinning stage is a key to prevent the defect formation. These findings facilitate the deposition of uniform PZT films over large substrates by a simple, scalable, and cost-effective process.

Sn–8Zn–3Bi solder paste and Sn–3.2Ag–0.5Cu solder balls were reflowed simultaneously at 240 °C on Cu/Ni/Au metallized ball grid array substrates. The joints without Sn–Zn–Bi addition (only Sn–Ag–Cu) were studied as a control system. Electrical resistance was measured after multiple reflows and aging. The electrical resistance of the joint (R1) consisted of three parts: the solder bulk (Rsolder bulk, upper solder highly beyond the mask), interfacial solder/intermetallic compound (Rsolder/IMC), and the substrate (Rsubstrate). R1 increased with reflows and aging time. Rsolder/IMC, rather than Rsolder bulk and Rsubstrate, seemed to increase with reflows and aging time. The increase of R1 was ascribed to the Rsolder/IMC rises. Rsubstrate was the major contribution to R1. However Rsolder/IMC dominated the increase of R1 with reflows and aging. R1 of Sn–Zn–Bi/Sn–Ag–Cu samples were higher than that of Sn–Ag–Cu samples in various tests.

This paper presents the design, fabrication, and mechanical testing of a bioinspired composite structure with characteristic dimensions on the order of tens of microns. The microarchitecture, designed and fabricated using microelectromechanical systems (MEMS) technology, involves two distinct length scales and represents the first attempt at mimicking the crossed-lamellar microstructure of molluscan shells such as the giant Queen conch, Strombus gigas, which contains features with dimensions spanning five distinct length scales. The displacement control capabilities of a nanoindenter enabled the observation of the graceful failure of the micro-composite under three point bending and, in turn, the measurement of its post-peak load–displacement response and work of fracture.

A novel polymeric composite material, polystyrene (PS)-grafted carbon nanocapsules (CNCs), has been prepared. sec-butyllithium was first used to introduce negative charges on CNCs, and these CNC carbanions acted then as initiators for anionic polymerization of styrene. Based on a weight loss at the decomposition temperature of the butyl groups, the quantity of the butyls attached to the CNC surface was determined as 1.18 wt%, corresponding to 0.25 mol% initiator per mol of carbon atom on the CNC surface. Furthermore, the decomposition temperature of butylated CNCs was lower than that of the pristine CNCs by nearly 200 °C. The polystyrene content in our PS-grafted CNC sample was approximately 20%, and the molecular weight of the grafted PS on the surface of CNCs was calculated as 1200 gmol−1. Compared with the molecular weight of the ungrafted PS, the molecular weight of grafted PS was lower, thus indicating rates of initiation and/or propagation for CNC-bound carbanions lower than those of the free sec-butyllithium. The PS-grafted CNCs had good dispersion in toluene, tetrahydrofuran, cyclohexane, and other common organic solvents in which polystyrene was dissolvable and thus indicated good compatibility when further blended with other styrenic polymers. The PS-grafted CNCs were characterized and examined by Fourier transform infrared, thermogravimetric analysis, atomic force microscopy, differential scanning calorimetry, ultraviolet-visible spectroscopy, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electron microscopy images indicated that the PS-grafted CNCs were homogeneous composites containing uniform polymer/CNC ratios.

The hardness and elastic modulus of ultra thin amorphous carbon overcoat (COC) films were measured using a recently developed sub-nm nanoindentation system. The carbon overcoat film thickness was varied to be 2.5 nm, 5 nm, and 10 nm on a glass substrate with a 2 nm titanium interlayer. A very sharp indenting tip, which was a cube corner tip with a radius of 44 nm, was used for the experiments. It was found that the mechanical properties of sub-10 nm film thicknesses can be reliably measured using the sub-nm indentation system and a sharp indenting tip. As the thickness of the carbon overcoat increased, so too did the surface roughness. For all three film thickness samples, the trends of hardness and elastic modulus values with the contact depth are very similar. When the contact depth is smaller than the film thickness, the measured values of hardness and elastic modulus are higher than those of the glass substrate, and gradually decrease and then approach the values of glass substrate. When the contact depth is larger than the film thickness, the measured values approximate those of the glass substrate. The thinner film shows higher values of hardness and elastic modulus near the surface, which indicates that mechanical properties do change with film thickness and that measurements made on thicker films and extrapolated to thinner films may lead to incorrect conclusions.

Electromigration (EM) in Cu dual-damascene interconnects with extensions (also described as overhangs or reservoirs) ranging from 0 to 120 nm in the upper metal (M2) was investigated by an analytical model considering the work of electron wind and surface/interface energy. It was found that there exists a critical extension length beyond which increasing extension lengths ceases to prolong electromigration lifetimes. The critical extension length is a function of void size and electrical field gradient. The analytical model agrees very well with existing experimental results. Some design guidelines for electromigration-resistant circuits could be generated by the model.

Strontium barium niobate (Sr2.5Ba2.5Nb10O30) thin films were deposited on (001) SrTiO3 single-crystalline substrates by pulsed laser deposition. The growth nature was investigated by transmission electron microscopy (TEM). Selected-area electron diffraction and high-resolution transmission electron microscopy revealed the existence of six types of grains. These grains grew on the substrate in a partially epitaxial fashion. Geometrical models were built, which were confirmed by TEM observations. Based on the TEM results and geometrical analysis, a crystallographic model was developed. The strain nature resulting from the growth columns is discussed in this report.

For extensive applications of bulk metallic glasses as structural materials, Fe-based bulk metallic glasses Fe73.8−xC7.0Si3.5BxP9.6Cr2.1Mo2.0Al2.0 (at.%, x = 3, 5, 7, 9) have been developed using hot metal, commercial grade pure elements, and industrial ferro-alloys. The alloy Fe68.8C7.0Si3.5B5P9.6Cr2.1Mo2.0Al2.0 can be cast into a fully amorphous rod of 5 mm in diameter through a suction casting method. The glass forming ability of the alloys can be successfully assessed by the difference of Gibbs free energy between liquid and solid phases obtained through thermodynamic calculations.