Nanoindentation measurements of the grain interiors of an ultra-fine grained (UFG) pure Al produced by equal channel angular pressing were taken to evaluate the contribution of the matrix strength. Specimens were subjected to 0, 1, 2, 4, and 8 passes at ambient temperature. The nanohardness of the deformed samples was always higher than that of the undeformed sample 0P in the range of the indentation depth that was investigated, suggesting a strengthening of the matrix in the UFG Al. The increase in hardness that was contributed by the matrix to the macroscopic scale hardness was significantly large in about 40% of the deformed samples. The microstructural characterization and the deformation response analysis with the pop-in event during indentation suggested that the strengthening of the matrix originated from dislocation strengthening and some other presumable factors in the grain interiors.

The thermoelectric LaFe3CoSb12 nanopowders were synthesized by the hydro/solvo thermal method. The effects of different solvents were investigated by using only the potassium antimony tartrate as Sb source. Also, the effects of the different Sb sources were investigated by using only water as solvent on the morphologies of the resulting nanopowders. The results show that a mixture of nanoparticles and nanorods can be obtained in aqueous solution of cetyltrimethylammonium bromide or ethylenediamine-tetra-acetic disodium salt. In ethylenediamine only nanorods can be obtained, and in ethylene glycol only nanoparticles can be obtained. The other morphologies of the LaFe3CoSb12, such as particle-like, nest-shaped, branch-shaped, or feather-like crystalline, can be synthesized in water by selecting a suitable Sb source.

Large-scale, well-aligned, and oriented ZnS nanorod arrays were fabricated by a novel and original template-free hydrothermal method. The ZnS nanorods were grown on the pulse-plating Zn nanocrystallines along a certain Zn crystalline direction. It was found that reaction factors such as hydrothermal reaction time, zinc source, and sulfide source concentration in the precursor solution, the acid–base property of the precursor solution, and the substrate where ZnS nanorod arrays were grown greatly influence the morphology of the final products. The growth mechanism of ZnS nanorod arrays was also studied. Pulse-plating Zn nanocrystallines were found to be essential for the growth of ZnS nanorod arrays. These ZnS nanorod arrays could be theoretically fabricated on almost any raw base plate as long as Zn nanocrystallines could be pulse-plated on it. Therefore, the as-synthesized ZnS nanorod array might be one of the promising candidates for field-emission or sensitive nanomaterials in the future.

Molecular organization of self-assembled n-dimethyl-n-octadecyl-3-aminopropyltrimethoxysilychloride (DMOAP) layers on indium tin oxide (ITO) coated glass substrates was thoroughly investigated. The layer thickness for each deposition was determined by variable angle spectroscopic ellipsometry (VASE), while from static contact-angle measurements we deduced valuable information regarding the ordering of the molecular structures at the solid-air interface. In particular, the DMOAP thin film formation was studied for two different drying temperatures (85 °C and 120 °C). While at Tdrying = 85 °C we observed the formation of a molecular monolayer characterized by a close packed structure, at the higher temperature the DMOAP molecules “bend” at the substrate as they stack in relatively disordered clusters. A qualitative interpretation of this phenomenon is given, in good agreement both with the obtained experimental data and experimental investigation reported in the scientific literature. The observations regarding the DMOAP molecular level organization as a function of substrate temperature could bring essential information to the self assembly research community and also explain some important physical phenomena occurring at interfaces.

Poly(vinyl alcohol) (PVA) and poly(tetrafluoroethylene) (PTFE) emulsion were blended with different mass concentrations and the blended spinning solutions were electrospun into composite nanofibers. The influence of the blend ratio of PVA to PTFE and electrospinning technical parameters on the morphology and diameter of the composite nanofibers were investigated. According to the result of thermogravimetric analyzer analysis, the composite membrane was sintered at 390 °C. The membranes were then characterized by differential scanning calorimetry, attenuated total reflection-Fourier transform infrared (ATR-FTIR), and scanning electron microscopy, respectively. The mechanical properties of the membranes before and after sintering were analyzed through tensile testing. The results show that the PTFE porous membranes could be electrospun effectively, thus demonstrating their potential application as filter media.

By optimizing the heating rate during spark-plasma-sintering (SPS) processing, a high-strength transparent spinel (MgAl2O4) can be successfully fabricated for only a 20-min soak at 1300 °C. For the heating rates of ≤10 °C/min, the spinel exhibits an excellent combination of in-line transmission (50–70%), four-point-bending strength (>400 MPa), and hardness (>15 GPa). The excellent optical and mechanical properties can be ascribed to the superimposed effects of the sub-micrograin size, fine-pore size, and low porosity, which are related closely to the heating rate during the SPS processing. The present study demonstrates that to attain a high-strength transparent spinel at low temperatures and short sintering times, the low-heating-rate SPS processing is more efficient compared with the high-heating-rate SPS processing.

The unique structure and mechanical properties of platelet-reinforced biological materials such as bone and seashells have motivated the development of artificial composites exhibiting new, unusual mechanical behavior. On the basis of designing principles found in these biological structures, we combined high-performance artificial building blocks to fabricate platelet-reinforced polymer matrix composites that exhibit simultaneously high tensile strength and ductility. The mechanical properties are correlated with the underlying microstructure of the composites before and after mechanical loading using transmission electron microscopy. The critical role of the strength of the platelet–polymer interface and its dependence on the platelet surface chemistry and the type of matrix polymer are studied. Thin multilayered films with highly oriented platelets were produced through the bottom-up layer-by-layer assembly of submicrometer-thin alumina platelets and either polyimide or chitosan as polymer matrix. The tensile strength and strain at rupture of the prepared composites exceeded that of nacre, whereas the elastic modulus reached values similar to that of lamellar bones. In contrast to the brittle failure of clay-reinforced composites of similar or higher strength and stiffness, our composites exhibit plastic deformation in the range of 2–90% before failure. In addition to the high reinforcing efficiency and ductility achieved, several toughening mechanisms were identified in fractured composites, namely friction, debonding, and formation of microcracks at the platelet–polymer interface, as well as plastic deformation and void formation within the continuous polymeric phase. The combination of high strength, ductility, and toughness was achieved by selecting platelets that exhibit an aspect ratio high enough to carry significant load but small enough to allow for fracture under the platelet pull-out mode. At high concentrations of platelets, the ductility gets lost because of out-of-plane misalignment of the platelets and incorporation of voids in the microstructure during processing. The designing principles applied in this study can potentially be extended to other types of platelets and polymers to obtain new, hybrid materials with tunable mechanical properties.

Effect of H2O2 on synthesis and powder properties such as surface area and agglomerate size of nanocrystalline Ce0.8M0.2O1.90 (M: Sm, Gd) was explored by treating cerium nitrate and rare-earth nitrate with NaOH in the presence/absence of H2O2. The resultant products were characterized by x-ray diffraction, Raman spectroscopy, thermo-gravimetry–differential thermal analysis, dynamic light scattering, surface area analysis, high-resolution transmission electron microscopy, and x-ray photoelectron spectroscopy. The presence of H2O2 was found to have a profound effect on powder properties such as surface area and particle size of these doped ceria samples and results in smaller crystallite size, softer agglomerates, and larger surface area. A mechanism is proposed to explain the observed better powder properties of the samples. It was also shown that the samples prepared in the presence of H2O2 can lower the conversion temperature of CO to CO2, proving these to be better catalysts. Interestingly, temperature-programmed reduction studies on Sm3+-doped samples showed that the doping in conjunction with the use of H2O2 leads to enhanced reduction properties of the samples over multiple cycles.

The effects of ultraviolet (UV) radiation on ultra-low-k dielectric (ULK) thin film fracture toughness were studied. This work discusses both critical and subcritical crack growth behavior under different environments. The critical fracture toughness was measured as a function of applied phase angle by using the four-point bend flexure and mixed-mode double cantilever beam techniques. Results of critical fracture toughness obtained under different loading configurations and phase angles were found to increase with the UV treatment time. In contrast, mode I subcritical fracture toughness thresholds and the crack propagation velocity appeared to be insensitive to UV curing processes. This study revealed that subcritical fracture toughness values reduced with the moisture concentration in the environment.

New Cu-based bulk glassy alloys (BGAs) with high glass-forming ability (GFA) were synthesized in a Cu-Zr-Al-Ag system. As the compositions of Cu-Zr-Al-Ag alloys with lower Ag and Al content shifted to the Cu-rich range, the supercooled liquid region, reduced glass transition temperature, and γ value increased, leading to the improvement of GFA. The best GFA is located around Cu47Zr45Al5Ag3, which is close to eutectic. Fully glassy samples with diameters up to 15 mm were fabricated by copper mold casting. These Cu-based BGAs exhibit excellent mechanical properties under compression. A large Young's modulus of 104–111 GPa, high fracture strength of 1905–1942 MPa, and distinct plastic strain of 0.002–0.011 were obtained. Additionally, the BGAs also show good corrosion resistance in 1 N H2SO4 solution.

We introduce a novel method to correct for imperfect indenter geometry and frame compliance in instrumented indentation testing with a spherical indenter. Effective radii were measured directly from residual indentation marks at various contact depths (ratio of contact depth to indenter radius between 0.1 and 0.9) and were determined as a function of contact depth. Frame compliance was found to depend on contact depth especially at small indentation depths, which is successfully explained using the concept of an extended frame boundary. Improved representative stress-strain values as well as hardness and elastic modulus were obtained over the entire contact depth.

Correlated force and contact resonance versus displacement responses have been resolved using load-dependent contact-resonance atomic force microscopy (AFM) to determine the elastic modulus of low-k dielectric thin films. The measurements consisted of recording simultaneously both the deflection and resonance frequency shift of an AFM cantilever probe as the probe was gradually brought in and out of contact. As the applied forces were restricted to the range of adhesive forces, low-k dielectric films of elastic modulus varying from GPa to hundreds of GPa were measurable in this investigation. Over this elastic modulus range, the reliability of load-dependent contact-resonance AFM measurements was confirmed by comparing these results with those from picosecond laser acoustic measurements.

The growth mechanism for the out-of-plane orientation of Nd–Fe–B films has been interpreted by the adparticle mobility during film growth, from the point view of the extended structure zone model. The growth mode changes sequentially from zone II to zone Ic, with the lowered thermally induced adparticle mobility on the surface as the film grows. As such, the whole Nd–Fe–B film evolves from [00l] out-of-plane orientation to more randomly out-of-plane alignment. With the growth of the out-of-plane–oriented Nd–Fe–B film, the correlation between the magnetic properties and the alignment evolution has been studied. The coercivity variation with the film growth is understood by analyzing the nucleation-dominant reversal processes for the out-of-plane–oriented Nd–Fe–B films.

An environmentally friendly route to prepare stable concentrated aqueous dispersions of silver nanoparticles is described. It was found that Arabic gum, a well known stabilizing agent, can also rapidly and completely reduce Ag2O to metallic silver in alkaline solutions (pH > 12.0) and elevated temperature (65 °C). The average size of the silver nanoparticles could be tailored from 10 to 30 nm by varying the experimental conditions. By hydrolyzing either enzymatically or chemically the polysaccharide, it was possible to isolate dispersed silver nanoparticles suitable for both biological and printable electronics applications. For the latter purpose, concentrated dispersions of silver particles were prepared and used for depositing thin uniform layers, which could be sintered into conductive films at low temperatures.

The effects of ruthenium (Ru)-oxidation states were investigated on Ru dissolution from PtRu thin-film electrodes, with the 200 cycles between 0.4 and 1.05 V (versus normal hydrogen electrode). The Ru-oxidation states of the PtRu thin films were systematically modified by an anodic (oxidation) treatment. The anodic-treated PtRu electrodes, whose methanol-oxidation activity was similar to untreated electrodes before the 200 cycles, showed a remarkable decrease in methanol oxidation after the cycles, because of the Ru dissolution from the PtRu surface. The results suggest that the Ru-oxide species are the origin of Ru dissolution in the PtRu alloy.