Relaxor ferroelectrics of Pb(Zn1/3Nb2/3)0.5(Zr0.47Ti0.53)0.5O3 (0.5PZN-0.5PZT) were prepared using the conventional oxide mixing method. Both x-ray diffraction analysis and Raman spectroscopy indicate that the amounts of rhombohedral phase are close to tetragonal phase, implying the presence of the morphotropic phase boundary (MPB) in the system of 0.5PZN-0.5PZT, and this result was further confirmed by transmission electron microscopy (TEM) micrographs. At MPB composition, the excellent piezoelectric properties, such as kp (0.66) and d33 (425pC/N), were obtained due to the more possible polarization directions of domains and high dc resistivity of 6.5 × 1010 Ω·cm. Meanwhile, the dielectric studies revealed that the indicator of the degree of diffuseness γ value is 1.73, implying that the relaxor nature of the 0.5PZN-0.5PZT is ceramic. The activation energy related to the dc conductivity was estimated from a linear fitting of the Arrhenius law. The value of 0.09 and 1.04 eV for low and high temperature range corresponds well to the activation energies of migration and first ionization of the oxygen vacancies.

The electrical resistivity ρ of palladium (Pd) films prepared by using magnetron sputtering at different pressures φ ranging from 2 to 15 mTorr showed very different hydrogen (H)-induced response. This reaction is because the mean free path of the particles in vacuum changes substantially with φ, such that the structure of the deposits is altered accordingly. A film prepared at a moderate φ value of 6 mTorr has a moderate strength. After a few hydrogenation-dehydrogenation cycles, some cracks are generated because of the great difference in the specific volumes of the metal and hydride phases. Breathing of the cracks in subsequent switching cycles occurred, which led to the response gain of ρ, defined as the resistivity ratio of the dehydrogenated-to-hydrogenated states during a cycle, to increase to 17. This result demonstrates the attractiveness of using the Pd films in H2 detection application. The H-induced resistive response of the films prepared at other φ values was found to be much smaller.

In instrumented indentation tests for a thin film coating on a substrate (film/substrate composite), it is well known that the substrate-affected contact area estimated through conventional approximations includes significant uncertainties, leading to a crucial difficulty in determining the elastic modulus and the contact hardness. To overcome this difficulty, an instrumented indentation microscope that enables researchers to make an in situ determination of the contact area is applied to an elastoplastic film on substrates having various values of their elastic moduli. Using the indentation microscope, the substrate-affected indentation contact parameters including contact hardness of the film/substrate composites are determined directly as well as quantitatively without any undesirable assumptions and approximations associated with the contact area estimate. The effect of a stiffer substrate on the contact profile of impression is significant, switching the profile from sinking in to piling up during penetration, and resulting in the substrate-affected contact hardness being highly enhanced at deeper penetrations. Through the present experimental study, it is demonstrated how efficient that instrumented indentation microscopy is in determining the substrate-affected elastoplastic contact parameters of film/substrate composite systems.

The crystal structure of VOBDC (BDC = 1,4-benzenedicarboxylate) has a 1-dimensional channel system with apertures of ∼8 Å, and shows remarkable flexibility upon adsorption/desorption of various guest molecules in the channels. VOBDC can selectively and rapidly adsorb organic molecules containing sulfur on exposure to a 5% CH4/He stream with different contents of thiophene or dimethyl sulfide at ambient temperature. Selective uptake of thiophene from liquid octane with thiophene concentrations from 2000 ppmw down to 100 ppmw is also observed. X-ray crystallographic data show that the adsorbed thiophene molecules adopt a herringbone packing arrangement within the channels of VOBDC while adsorbed dimethyl sulfide molecules are disordered among several positions in the channels with the sulfur atoms pointing toward the channel walls. The observed adsorptive capacities for thiophene and dimethyl sulfide are 155 mg and 208 mg sulfur per gram of VOBDC, respectively, consistent with the crystal structure data.

The structure and the response of the effective electrical resistivity 〈ρ〉 in hydrogenation–dehydrogenation processes of palladium-coated/magnesium-nickel (Pd/Mg–Ni) films were investigated as functions of Mg-to-Ni ratio, substrate temperature, and thickness of Pd overcoat. Films of noncrystalline structures with various Mg-to-Ni ratios showed prominent hydrogen-(H-)induced switching effect of 〈ρ〉. A film is supposed to contain segregated noncrystalline regions of different Mg-to-Ni ratios. The regions of an Mg-to-Ni ratio close to 2 are responsible for the switching processes. At room temperature, a dehydrogenation process is much slower than a hydrogenation process. Crystallization hindered the H-induced switching effect of 〈ρ〉. The use of a thicker Pd overcoat accelerated the change of 〈ρ〉 in the initial hydrogenating process but diminished the contrast. Results led to some discussions on the mechanisms governing the switching effects.

Bulk NaYF4:Yb,Er particles (∼1.4 μm particle size) were synthesized using a hydrothermal method. As-synthesized particles were subsequently ball milled to three average particle sizes, namely, ∼260 nm, 160 nm, and 100 nm. The x-ray diffraction pattern showed an hcp phase for as-synthesized and ball-milled particles with a predominant (100) peak. Room temperature emission spectra showed no size dependent peak shifts or peak broadening. The intensities of both green and red emissions decreased with increasing milling time. Segregation of Er ions was detected on the surfaces of milled particle that reduced the sensitizer-activator transition probability, resulting in decreased emission intensities. The green-to-red emission ratio was correlated to the surface enrichment of Er, which affected the cross-relaxation of luminescence dynamics.

A study was made to investigate cavity growth behavior during the superplastic deformation of submicrometer-grained titanium alloy and to compare that to cavity growth in a coarse-grained counterpart. A series of tension tests were performed at a temperature of 973 K and a strain rate of 10−4 s−1. Microstructures revealed that both the size and the volume fraction of the cavities obviously decreased as the grain size decreased. Working within the framework provided by creep models for understanding cavity growth behavior, we found the dominant growth mechanism to be superplastic diffusion, which leads to high-tensile ductility in submicrometer-grained titanium alloy.

Effects of Fe incorporation into Al–Ti–B4C reactants on the combustion behaviors, reaction mechanism, synthesized products, and possible natural convection of fluids were investigated. The incorporation of Fe significantly promotes the self-propagating reaction and decreases the reaction dependence on the B4C particle size. The prior reaction of Fe with B4C leads to the decomposition of B4C and formation of Fe2B and free carbon. On the other hand, the reaction of Fe with Ti and Al gives rise to the emergence of Fe–Ti and Fe–Ti–Al eutectic liquids. As a result, the diffusivity and reactivity of the dissociated carbon and boron atoms are greatly facilitated and the reaction is substantially promoted, yielding a desirable product of TiC, TiB2, and FeAl phases. Moreover, the incorporation of Fe may enhance free convection of the molten phase in the reaction zone and thus contribute to the combustion synthesis process.

We report on the formation of ultrafine-grained Ti66Nb13Cu8Ni6.8Al6.2 composites with in situ precipitated micrometer-sized β-Ti(Nb) phase by spark plasma sintering with crystallization. Microstructure analysis indicated that all alloys consisted of soft (Cu, Ni)Ti2 regions surrounded by hard β-Ti(Nb) regions but displayed different microstructures. The alloys exhibited high fracture strength of more than 2200 MPa and remarkable plasticity of ∼25%. The results provided a promising method for fabricating large-sized bulk composites with excellent mechanical properties by powder metallurgy.

Targeted cancer therapies focus on molecular and cellular changes that are specific to cancer and hold the promise of harming fewer normal cells, reducing side effects, and improving the quality of life. One major challenge in cancer nanotechnology is how to selectively deliver nanoparticles to diseased tissues while simultaneously minimizing the accumulation onto the nanoparticle of unwanted materials (e.g., proteins in the blood) during the delivery process. Once therapeutic nanoparticles have been created, very often they are linked or coated to other molecules that assist in targeting the delivery of nanoparticles to different cell types of the body. These linkers or coatings have been termed targeting ligands or “smart molecules” because of their inherent ability to direct selective binding to cell types or states and, therefore, confer “smartness” to nanoparticles. Likewise, “smartness” can be imparted to the nanoparticles to selectively repel unwanted entities in the body. To date, such smart molecules can consist of peptides, antibodies, engineered proteins, nucleic acid aptamers, or small organic molecules. This review describes how such smart molecules are discovered, enhanced, and anchored to nanoparticles, with an emphasis on how to minimize nonspecific interactions of nanoparticles to unintended targets.

Current semiconductor technology demands the use of compliant substrates for flexible integrated circuits. However, the maximum total strain of such devices is often limited by the extensibility of the metallic components. Although cracking in thin films is extensively studied theoretically, little experimental work has been carried out thus far. Here, we present a systematic study of the cracking behavior of 34- to 506-nm-thick Cu films on polyamide with 3.5-to 19-nm-thick Ta interlayers. The film systems have been investigated by a synchrotron-based tensile testing technique and in situ tensile tests in a scanning electron microscope. By relating the energy release during cracking obtained from the stress-strain curves to the crack area, the fracture toughness of the Cu films can be obtained. It increases with Cu film thickness and decreases with increasing Ta film thickness. Films thinner than 70 nm exhibit brittle fracture, indicating an increasing inherent brittleness of the Cu films.

Spark plasma sintering (SPS) of MgAl2O4 powder was investigated at temperatures between 1200 and 1300 °C. A significant grain growth was observed during densification. The densification rate always exhibits at least one strong minimum, and resumes after an incubation period. Transmission electron microscopy investigations performed on sintered samples never revealed extensive dislocation activity in the elemental grains. The densification mechanism involved during SPS was determined by anisothermal (investigation of the heating stage of a SPS run) and isothermal methods (investigation at given soak temperatures). Grain-boundary sliding, accommodated by an in-series {interface-reaction/lattice diffusion of the O2− anions} mechanism controlled by the interface-reaction step, governs densification. The zero-densification-rate period, detected for all soak temperatures, arise from the difficulty of annealing vacancies, necessary for the densification to proceed. The detection of atomic ledges at grain boundaries and the modification of the stoichiometry of spinel during SPS could be related to the difficulty to anneal vacancies at temperature soaks.

The effect of Li3N additive on the Li-Mg-N-H system was examined with respect to the reversible dehydrogenation performance. Screening study with varying Li3N additions (5, 10, 20, and 30 mol%) demonstrates that all are effective for improving the hydrogen desorption capacity. Optimally, incorporation of 10 mol% Li3N improves the practical capacity from 3.9 wt% to approximately 4.7 wt% hydrogen at 200 °C, which drives the dehydrogenation reaction toward completion. Moreover, the capacity enhancement persists well over 10 de-/rehydrogenation cycles. Systematic x-ray diffraction examinations indicate that Li3N additive transforms into LiNH2 and LiH phases and remains during hydrogen cycling. Combined structure/property investigations suggest that the LiNH2 “seeding” should be responsible for the capacity enhancement, which reduces the kinetic barrier associated with the nucleation of intermediate LiNH2. In addition, the concurrent incorporation of LiH is effective for mitigating the ammonia release.

In this work load–penetration curves obtained by nanoindentation were analyzed, using a spherical tip approximation and applying the stress/strain concept by Tabor. Nanoindentation experiments were done on sapphire, pure TiC, and a mixed ceramic with in situ formed TiCx layer, using a sharp cube-corner indenter at very low loads and penetration depths. With the implemented method it is possible to display the elastic to elastic–plastic transition of each investigated phase, and much more information can be extracted than by conventional analysis. Regarding the mixed ceramic, it was found that the present TiC phases exhibit slightly lower hardness than the alumina phase, but they can sustain much higher stresses during the transition from the elastic to the elastic–plastic regime. This is considered to be beneficial for the application as cutting material. No correlation was found between the nanomechanical behavior of the model materials sapphire and TiC and the corresponding phases of the mixed ceramic.