We report the fabrication of micron-sized rodlike particles of nonstoichiometric Co and Ni ferrites by aging coprecipitated Fe(OH)2 and M(OH)2—where M is either Ni or Co—at 90 °C in the presence of an external magnetic field (B ≈ 405 mT). Potassium nitrate was used as a mild oxidant. Resultant particles were analyzed by means of electron microscopy, x-ray powder diffraction (XRD), magnetometry, energy dispersive x-ray (EDX) spectrometry, and atomic absorption spectroscopy. Rodlike particles of both types of ferrite exhibited a relatively uniform thickness, an average aspect ratio close to 10, and have a spinel crystalline structure. EDX spectrometry and atomic absorption spectroscopy confirmed the incorporation of Ni2+ and Co2+ in the respective ferrite particles. The incorporation of Co2+ led to non-negligible remanence and coercivity. The incorporation of Ni2+ led to a lower saturation magnetization, whereas the remanence and coercivity of the Ni ferrite were very low, still typical of a soft ferrimagnetic material. The mechanism of formation of the rodlike particles was investigated by the time-dependent observation of growing Ni ferrite rods.

Borides of high electron density metals such as Os show promise as hard materials. Arc-melting elemental osmium and boron under an argon atmosphere produced osmium diboride (OsB2). Both a Vickers diamond microindenter and a Berkovich nanoindenter were used to measure hardness. Vickers microindentation indicates that the hardness of OsB2 increases significantly with decreasing applied load. The average hardness reaches approximately 37 GPa as the applied load is lowered to 0.245 N. The hardness is found to be highly dependent on the crystallographic orientation. For the {010} grains, along the 〈100〉 direction, the average hardness is significantly higher than that in the orthogonal 〈001〉 direction. Cracks associated with pop-in events in the nanoindentation load–displacement curves are observed in the {010} grains. The measured Young’s modulus of OsB2 is 410 ± 35 GPa, which is comparable to that obtained from first-principles calculations.

The surface enthalpy of ZnO nanoneedles has been measured by oxide melt solution calorimetry of samples with different surface areas. Water adsorption calorimetry was carried out to characterize the stabilization effect of surface hydration. The surface enthalpies of hydrated and anhydrous surfaces (8.21 ± 0.67 and 9.81 ± 0.69 J/m2, respectively) are larger than those of nanorods. The less stable surface of nanoneedles provides a driving force for the transformation of nanoneedles into nanorods during aging. The formation of bushlike assemblies of nanoneedles is also discussed.

Dynamic indentation techniques are often used to determine mechanical properties as a function of depth by continuously measuring the stiffness of a material. The dynamics are used by superimposing an oscillation on top of the monotonic loading. Of interest was how the oscillation affects the measured mechanical properties when compared to a quasi-static indent run at the same loading conditions as a dynamic. Single crystals of nickel and NaCl as well as a polycrystalline nickel sample and amorphous fused quartz and polycarbonate have all been studied. With respect to dynamic oscillations, the result is a decrease of the load at the same displacement and thus lower measured hardness values of the ductile crystalline materials. It has also been found that the first 100 nm of displacement are the most affected by the oscillating tip, an important length scale for testing thin films, nanopillars, and nanoparticles.

Delamination at an interface with the weakest adhesion strength, which is found to be between the SiC(N) capping layer and the SiOCH low-k dielectric, is a potential failure mechanism contributing to time-dependent dielectric breakdown (TDDB) reliability. Bond breaking at that interface is believed to be driven by a field-enhanced thermal process and catalyzed by leakage current through the capping layer based on physical analyses and TDDB measurements. Delamination is found to be easier in terminated tips and corners than in parallel comb lines due to the layout orientation of the Cu lines. Moreover, TDDB activation energy Ea can be an indicator of the ease of delamination, whereby a lower Ea corresponds to an easier delamination.

By spark-eroding Fe75Si15B10 in water/ethanol mixtures, spherical particles with nanostructured cores consisting of mixed amorphous and crystalline phases were produced. The relative volume fractions of the amorphous and crystalline phases were dependent on the water/ethanol ratio. In the same process, continuous oxide layers were formed on the particle surfaces. The basic mechanisms responsible for the formation of the surface oxide layers and the core nanostructures were modeled. At frequencies ranging from 1 to 100 MHz, the combination of the core nanostructures and the insulating oxide shells yielded exceptionally low-loss magnetic behavior.

The long-duration oxidation behavior of a pressureless liquid-phase-sintered (LPS) α-SiC with 10 vol% Y3Al5O12 additives was studied by furnace oxidation tests in ambient air at 1100 to 1450 °C. The oxidation of this LPS SiC ceramic was found to be passive throughout these temperatures due to the formation of oxide scales, with a change in the oxidation behavior occurring at 1350 °C. It was also found that the oxidation behavior is very complex, exhibiting two distinct stages at all temperatures: (i) initial nonparabolic oxidation, where the rate-limiting mechanism is the outward diffusion of Y3+ and Al3+ cations from the secondary intergranular phase into the oxide scale with the activation energy of the oxidation being 504 ± 32 kJ/mol, followed by (ii) parabolic oxidation below 1350 °C, where the rate-determining mechanism is the inward diffusion of oxygen through the oxide scale with the activation energy being 310 ± 47 kJ/mol, or paralinear oxidation at and above 1350 °C, where oxidation is controlled by some mixed reaction/diffusion process. The existence of two oxidation regimes reflects the progressive crystallization of the oxide scale during the oxidation. Finally, guidelines are provided for the design and fabrication of low-cost, highly oxidation-resistant LPS SiC or other LPS nonoxide ceramics.

A viscoelastic solid was contacted by a pointed indenter using low-frequency large-amplitude sinusoidal load functions to determine its contact stiffness in a manner similar to that of the continuous stiffness measurement (CSM) technique but in a quasi-static condition. The contact stiffness of a viscoelastic solid determined by the CSM technique, or the dynamic stiffness, is known, from previous CSM-based studies, to overestimate the quasi-static contact stiffness. The contact stiffness of a viscoelastic solid determined in a quasi-static manner is thus hypothesized to help predict the contact depth more accurately. A new analysis procedure based on truncated Fourier series fitting was developed specifically to process the large amplitude sinusoidal indentation data. The elastic modulus of the material characterized in this work was in agreement with that determined by dynamic mechanical analysis, thereby providing evidence for the validity of the present method in characterizing other viscoelastic materials.

Three-dimensional x-ray diffraction (3DXRD) allows nondestructive characterization of grains, orientations, and stresses in bulk microstructures and, therefore, enables in situ studies of the structural dynamics during processing. The method is described briefly, and its potential for providing new data valuable for validation of various models of microstructural evolution is discussed. Examples of 3DXRD measurements related to recrystallization and to solid-state phase transformations in metals are described. 3DXRD measurements have led to new modeling activity predicting the evolution of metallic microstructures with much more detail than hitherto possible. Among these modeling activities are three-dimensional (3D) geometric modeling, 3D molecular dynamics modeling, 3D phase-field modeling, two-dimensional (2D) cellular automata, and 2D Monte Carlo simulations.

A series of novel epoxy/clay nanocomposites (EPOCg-x) were prepared with a selected epoxy resin and x wt% of a mechanically ground phosphorus-containing organoclay (POCg). The results of x-ray diffraction (XRD), Fourier transform infrared, and field emission scanning electron microscopy measurements showed that POCg was size-reduced, and its silicate layers were disordered by the grinding process. The results of XRD and transmission electron microscopy of the nanocomposites suggested that the POCg particles were well-dispersed in the epoxy matrix with a combination of intercalation and destruction platelet structures. The as-prepared nanocomposites remained thermally stable above 376 °C. Furthermore, the storage modulus in the glass state, surface hardness, char residue, and limiting oxygen index (LOI) of the as-prepared nanocomposite were all significantly increased with increasing the POCg content. The large increment of LOI, 10 units higher than that of neat epoxy, indicated that an extraordinary enhancement on flame retardancy was obtained from EPOCg-5.

Herein we compare the lattice parameters, room temperature shear and Young’s moduli, and phonon thermal conductivities of Ti2AlC0.5N0.5 and Ti3Al(C0.5, N0.5)2 solid solutions with those of their end members, namely Ti2AlC, Ti2AlN, Ti3AlC2, and Ti4AlN2.9. In general, the replacement of C by N decreases the unit cell volumes and increases the elastic moduli and phonon thermal conductivities. The increase in the latter two properties, however, is sensitive to the concentrations of defects, most likely vacancies on one or more of the sublattices.

There is often a tradeoff between strength and ductility, and the low ductility of ultrafine-grained (UFG) materials has been a major obstacle to their practical structural applications despite their high strength. In this study, we have achieved a ∼40% tensile ductility while increasing the yield strength of FeCrNiMn steel by an order of magnitude via grain refinement and deformation-induced martensitic phase transformation. The strain-rate effect on the inhomogeneous deformation behavior and phase transformation was studied in detail.

Experimental studies were conducted to investigate the microwave (MW) heating behavior of soda-lime glass beads with added iron powder. These studies were intended to obtain fundamental knowledge for vitrification solidification and for the fabrication of metal-reinforced glass-matrix composites. The glass beads (0.2 mm diameter) did not heat very well by themselves at temperatures greater than 200 °C within 600 s in a multimode applicator at a power of 0.67 W. The addition of iron powder (average 70 μm, volume fraction 18%) made it possible to heat the glass beads above 700 °C within 60 s. At lower fractions of 3–11 vol%, however, a sudden temperature rise [thermal runaway (TRW)] occurred after the incubation time period. A single-mode MW applicator was used for clarifying the electric (E)-field and magnetic (H)-field contributions to the heating of each material and their mixtures. The results of this study demonstrated that the H-field contributed to the heating of the iron and then triggered the heating of the glass. The E-field component is necessary for heating the glass to a temperature higher than 800 °C. The factors determining the threshold values of the volume fraction causing TRW are discussed.

An in situ surface-reaction approach has been developed for the synthesis of microcrystals Cu4I4(C6H5N)4, Cu4I4(C9H7N)4, and Cu2I2(C8H6N2) in solid films. Microcrystals of Cu4I4(C6H5N)4, Cu4I4(C9H7N)4, and Cu2I2(C8H6N2) were easily formed on a copper substrate at the solid Cu–liquid pyridine (C6H5N),–quinoline (C9H7N), and–quinoxaline (C8H6N2) interfaces. The resulting microcrystal films were characterized by photoluminescence spectroscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, and electrochemical impedance spectroscopy. The effect of ligands on the morphology of the film materials and their chemical properties were also discussed. These microcrystal films possessing reversible photocurrent and photovoltage properties were studied in detail. The photoactive and mechanically stable complex films described here may provide new strategies for fabricating photoluminescence solid films, photomodulation potential, and current films. The potential applications of the microcrystal films are for small light-induced electronic junction and photoluminescence sensors.

The current study revealed the effects of strain rate on tensile strength and ductile-to-brittle transition of Sn–3Cu/Cu joints in the strain rate range of 4.2 × 10−5 to 2.4 × 10−1 s−1. Experimental results indicate that these joints broke in a ductile manner at low strain rates with a rapid increase in the tensile strength but displayed a brittle manner at higher strain rates with a slow increase in the tensile strength, indicating a typical ductile-to-brittle transition feature. A method was proposed to estimate the interfacial strength between the solder and the intermetallic compounds.

Hydrogenated In-doped ZnO (ZIO:H) films grown at different ratios, R, of hydrogen to argon were deposited at a substrate temperature of 100 °C for the organic light-emitting diodes (OLEDs). The OLEDs with the ZIO:H (R = 0.08) anode achieved a maximum luminance efficiency of 3.4 cd/A and a power efficiency of 0.6 lm/W, which are as good as the values of the control device fabricated on a tin-doped indium oxide (ITO) anode. This indicates that the efficiency of the OLEDs is critically affected by the ratio of injected hydrogen gas during the deposition of the ZIO and that the ZIO:H developed herein is promising as an alternative to conventional ITO.