Transport properties in the a-b plane of Nd0.75Sr1.25CoO4 thin film as fabricated via a pulsed laser deposition technique have been investigated by means of measurements of resistivity and thermopower, respectively, in the temperature ranges of 76-300 and 80-310 K. The thermopower of the specimen revealed a mechanism of spin-dependent scattering of the charge carriers where its conduction could be well interpreted by the small polaron hopping conduction in the nonadiabatic regime at high temperatures and the two-dimensional variable range hopping of small polarons at low temperatures. Possible mechanisms for the polaronic conduction were also discussed in the article where several physical parameters of the specimen were determined using a small polaron hopping model and a better understanding of the strongly correlated electron system was achieved.

This article investigates the effect of grain structure on electromigration (EM) reliability of dual-damascene Cu interconnects with a CoWP capping layer, including the lifetime and statistics. Downstream EM tests were performed on two sets of CoWP-capped Cu interconnects with different grain sizes. Compared to Cu interconnects with the standard SiCN cap layer, the CoWP capping clearly improved the EM lifetime by ∼24× for the small grain structure and by another ∼14× for the large grain structure. Here, the effect of grain structure on EM lifetime was attributed to the grain boundary contribution to mass transport. The lifetime improvement, however, was accompanied with an increase in the statistical deviation, increasing from 0.27 for the SiCN cap to 0.53 for the small grain structure and to 0.88 for the large grain structure with the CoWP cap. This was attributed to the effect of grain structure in changing the statistical distribution of flux divergence sites and thus the failure statistics.

The temperature-dependent thermoelectric (TE) and structural properties of n-type filled skutterudites were measured from 300–625 K. In0.2Co4Sb12, and In0.2Ce0.05Yb0.1Co4Sb12 exhibited figure of merit (ZT) values as high as 1.2 at 625 K and In0.2Ce0.15Co4Sb12 showed ZT values of ∼1.4 at 625 K. The room temperature Young’s modulus, Poisson’s ratio, and coefficient of thermal expansion (at 298–673 K) of In0.2Ce0.15Co4Sb12, In0.2Co4Sb12, and In0.2Ce0.05Yb0.1Co4Sb12 compositions were found to be lower than that for the unfilled Co4Sb12 skutterudite material. It was discovered that thermal cycling of n-type In0.15Ce0.1Co4Sb12 and In0.2Ce0.17Co4Sb12 materials from 323–673 K (200 cycles) actually increased their power factors by 13.6–36% at 510–525 K without appreciably changing the Young’s modulus or the Poisson’s ratio. The transport and structural properties characterized in this work are critical to transitioning these materials into operating TE devices and systems.

Organic plasma polymers are currently attracting significant interest for their potential in the areas of flexible optoelectronics and biotechnology. Thin films of plasma-polymerized polyterpenol fabricated under varied deposition conditions were studied using nanoindentation and nanoscratch analyses. Coatings fabricated at higher deposition power were characterized by improved hardness, from 0.33 GPa for 10 W to 0.51 GPa for 100 W at 500-μN load, and enhanced wear resistance. The elastic recovery was estimated to be between 0.1 and 0.14. Coatings deposited at higher RF powers also showed less mechanical deformation and improved quality of adhesion. The average (Ra) and root mean square (Rq) surface roughness parameters decreased, from 0.44 nm and 0.56 nm for 10 W to 0.33 nm and 0.42 nm for 100 W, respectively.

(Pb0.87La0.02Ba0.1)(Zr0.75Sn0.25–xTix)O3 (PLBZST, 0.07 ≤ x ≤ 0.09) ceramics were prepared by the conventional solid state reaction process, and their crystal structural, ferroelectric (FE), dielectric, and pyroelectric properties were systemically investigated. A transformation from antiferroelectric (AFE) phase to FE phase was observed when x was higher than 0.08. With the content of Ti increasing from 0.07 to 0.09, the dielectric peak was steeper and the pyroelectric coefficient was greater under direct current (DC) bias fields. As the DC bias field increased from 300 V/mm to 600 V/mm, the pyroelectric coefficient increased from 4500 to 10500 μC/m2·K for PLBZST specimens with 0.09. Thus, large pyroelectric response is beneficial for the development of infrared sensors.

We report the processing and immobilization of enzyme Ribonuclease A (RNase A) onto SiO2 glass collectors using the matrix assisted pulsed laser evaporation (MAPLE) technique. The experiments were performed inside a stainless steel irradiation chamber. A pulsed UV KrF* (λ = 248 nm, τFWHM ≈ 25 ns, ν = 10 Hz) excimer laser source was used for the irradiations. The laser fluence was varied in the range 0.4–0.7 J/cm2. The morphology of the obtained films was investigated by atomic force microscopy (AFM) and their structure and composition by Fourier transform infrared spectroscopy (FTIR). The FTIR spectra of the films obtained from composite MAPLE targets consisting of 1% (w/v) RNase A in Hepes-KOH 10 mM pH 7.5 buffer exhibit the same bands as the spectrum of the initial, nonirradiated material. The enzymatic activity of the obtained structures was analyzed using synthetic substrate polycytidylic acid (poly(C)). The poly (C) cleavage by the immobilized enzyme and the products of formation were analyzed by means of reverse phase high performance liquid chromatography (HPLC).

Nitrogen-doped multiwalled carbon nanotubes (N-doped MWNTs) were synthesized in a large quantity by the pyrolysis of pyridine at various temperatures in the range of 750–950 °C. The influence of temperature on the morphology, composition, thermal stability, and bonding nature of N-doped MWNTs was investigated. It is found that the yield of N-doped MWNTs increases linearly with the increase of the growth temperature. The maximum N content (4.6 at%) in MWNTs was obtained from a sample grown at 900 °C. N-doped MWNTs synthesized at 950 °C possess a unique drumlike morphology with the highest oxidizing temperature (535 °C). It is evidenced that N atoms are incorporated into the graphitic network in three different bonding forms and their relative content is affected by the growth temperature, which shows a clear influence on the morphology of N-doped MWNTs.

It was observed that the cement line (CL), namely the border of the osteon in cortical bone, plays an important role in bone fracture: arresting and deflecting cracks. The underlying mechanism was speculated to be that each CL behaves as a weak interface, and thus, it attracts and deflects the bone cracks due to the debonding at the CL. This speculation of a weak CL has not been experimentally verified due to the CL’s challengingly small width. In this study, nanoindentation arrays were carefully conducted to characterize the CLs in ovine and bovine femurs. We found that the modulus and hardness of the CLs are about 30% less than those of the surrounding bone tissues in both species. Thus, for the first time, we characterized the mechanical properties of the CL and verified the speculation of a weak CL, providing a quantitative/constitutive basis for the theoretical modeling of bone micromechanics involving the CL.

The failure mechanism of lead-free solder interconnections of chip scale package–sized Ball Grid Array (BGA) component boards under thermal cycling was studied by employing cross-polarized light microscopy, scanning electronic microscopy, electron backscatter diffraction, and nanoindentation. It was determined that the critical solder interconnections were located underneath the chip corners, instead of the corner most interconnections of the package, and the highest strains and stresses were concentrated at the outer neck regions on the component side of the interconnections. Observations of the failure modes were in good agreement with the finite element results. The failure of the interconnections was associated with changes of microstructures by recrystallization in the strain concentration regions of the solder interconnections. Coarsening of intermetallic particles and the disappearance of the boundaries between the primary Sn cells were observed in both cases. The nanoindentation results showed lower hardness of the recrystallized grains compared with the non-recrystallized regions of the same interconnection. The results show that failure modes are dependent on the localized microstructural changes in the strain concentration regions of the interconnections and the crack paths follow the networks of grain boundaries produced by recrystallization.

In- and Yb-doped CoSb3 thin films were prepared by pulsed laser deposition. Process optimization studies revealed that a very narrow process window exists for the growth of single-phase skutterudite films. The electrical conductivity and Seebeck coefficient measured in the temperature range 300–700 K revealed an irreversible change on the first heating cycle in argon ambient, which is attributed to the enhanced surface roughness of the films or trace secondary phases. A power factor of 0.68 W m−1 K−1 was obtained at ∼700 K, which is nearly six times lower than that of bulk samples. This difference is attributed to grain boundary scattering that causes a drop in film conductivity.

Here we present a microemulsion route to prepare core–shell structured NaGdF4:Yb,Er@Carbon nanoparticles, in which a thin layer of hydrophilic carbon was covered on hydrophobic NaGdF4:Yb,Er nanocrystals. The prepared NaGdF4:Yb,Er@Carbon nanoparticles were uniform in a size of 25 nm, water-dispersible, and displayed good biocompatibility and strong upconversion fluorescence. Their potential for use as efficient cell-imaging probes is also demonstrated.

Although highly magnetostrictive thin films of Terfenol-D have been produced by a variety of methods, high-quality thick films have proved to be far more challenging to produce. To date, thick film processes have resulted in nanoparticulate films that contain significant porosity that reduces stiffness and results in oxidation and poor magnetostrictive performance. With the goal of understanding microstructural and compositional factors that affect performance, nanoparticulate Terfenol-D thick films were produced by laser ablation of microparticle aerosols combined with supersonic impaction. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, x-ray photon spectroscopy, and magnetic measurements were performed on nanoparticles and on films as-deposited and after annealing in vacuum or in a reducing atmosphere. These measurements show that segregation occurs during oxidation of the films, prior to annealing, and results in films with poor magnetostriction. The segregation persists during annealing with no visible changes to the morphology or density of the nanoparticulate films exposed to temperatures as high as 800 °C. These results suggest that oxidation and segregation must be avoided to produce highly magnetostrictive thick films.

B2O3-SiO2 is shown to act as a transient liquid phase sintering aid that reduces the sintering temperature of Nd:YAG ceramics to 1600 °C. 1 at.% Nd3xY3-3xAl5O12 (Nd:YAG) ceramics were doped with 0.34–1.35 mol% B2O3-SiO2 and sintered between 1100 and 1700 °C. Dilatometric measurements show that B2O3-SiO2 doping increases the densification rate during intermediate-stage sintering relative to SiO2-doped samples. B3+ content is reduced to <5 ppm in samples heated to 1500 °C, as determined by mass spectrometry. For B2O3-SiO2-doped samples, final stage densification and grain growth follow a more densifying sintering trajectory than SiO2-doped 1 at.% Nd:YAG ceramics because there is less SiO2 during final-stage densification. The increased densification kinetics during intermediate-stage sintering lead to highly transparent Nd:YAG ceramics when sintered at 1600 °C in either vacuum or oxygen. Thus, transparent Nd:YAG ceramics can be sintered without the need for expensive refractory metal vacuum furnaces or pressure-assisted densification.

Copper/diamond-like carbon (DLC) was fabricated using pulsed laser deposition, and the effects of copper on the properties of DLC composites were studied. Experimental results showed that the presence of copper promoted surface evolution through the formation of nanoclusters, accentuated the formation of Si–C but graphitized the diamond bondings of DLC matrix. By considering the interaction of laser with copper/carbon composite target, the presence of copper may have increased the energy absorbed during laser deposition, as envisaged by Saha’s equation. Thus, upon the impingement of ions on substrate during deposition, the carbon and silicon atoms may have been redistributed to form Si–C bonding while the excess energy was released as heat to promote the formation of nanoclusters but graphitize the sp3 bonding in DLC. Although sp3 bonding was reduced with the presence of copper, mechanical characterization showed that the adhesion strength of the composite films was approximately five times higher compared to undoped DLC, as a result of the decrease in internal stress and the formation of Si–C bondings in DLC.

La2NiMnO6 (LNMO) was prepared by a combustion method followed by heating at high temperature. Subsequently, the preformed LNMO was annealed in air, oxygen, or N2 atmosphere and characterized by powder x-ray diffraction (XRD), neutron diffraction, superconducting quantum interference device magnetometry, and dielectric analysis. Structural studies by XRD and neutron diffraction revealed the coexistence of partially cation disordered monoclinic (31%) and rhombohedral (69%) phases in the sample annealed in air. However, the sample annealed in oxygen shows about 50:50% of monoclinic and rhombohedral phases. Relaxor-like behavior with relative permittivity of the order of 104 was observed in the sample annealed in air, while relative permittivity decreases to about 200 in samples annealed in oxygen atmosphere. The magnetic properties indicate a well-defined ferromagnetic phase in the oxygen-annealed sample compared to a feeble ferromagnetic signature in the air-annealed one. The dielectric and ferromagnetism of LNMO samples have been related to formation and annihilation of oxygen vacancies.

Epoxy–dicyandiamide (Dicy) formulations frequently contain a free accelerator for reducing the curing temperature and the time for network formation, which reduces the shelf life of these adhesives. This study compared the reaction kinetics during the storage at 60 °C for a precured epoxy adhesive (EP = diglycidyl ether of bisphenol A and Dicy, mass ratio 100:6.7, precured at 150 °C for 1 h) mixed either with free accelerator (=EPacc) or with the same concentration of accelerator immobilized in micro- or nanozeolite fillers (EPμ-filled and EPn-filled, respectively). During storage, the infrared (IR) study probed the chemical modifications. They lead to increasing cross-linking density and a loss of free volume as detected by positron annihilation lifetime spectroscopy (PALS). Cross-linking precedes to the chemical vitrification. Additionally, the glass transition and the free-volume parameters were investigated for the three EP’s as a function of temperature by PALS after thermal curing.

Synthesis of titania (TiO2) nanorods on various substrates has recently attracted attention for energy and environmental applications. Herein, we report growth of nanostructured TiO2 on Si(111) and glass borosilicate substrates by a two-step method. A thin film of anatase TiO2 was first laid down by spin coating and annealing, followed by the growth of rutile TiO2 nanorods with a hydrothermal method. To understand the role of the polycrystalline anatase TiO2 seed layer, we selected a relatively high temperature for the hydrothermal reaction, e.g., 175 °C at which no rutile TiO2 nanorods could grow without the precoated anatase TiO2 layer. The morphology and microstructure of both the polycrystalline anatase and rutile nanorod layers were characterized by electron microscopy and x-ray powder diffraction. Such a two-step fabrication method makes it possible to grow TiO2 nanorods on almost any substrate.

Nanoparticles of Cd1–xCuxS (x = 0–0.15) were synthesized by chemical coprecipitation using thiophenol as a capping agent. The x-ray diffraction patterns reveal that the pure and doped CdS nanoparticles are single phase with cubic zinc blende structure. The transmission electron microscopy shows the average size of the nanoparticles is about 8.5 nm. Optical absorption spectra indicate the energy gap decreases with increasing Cu2+ concentration. The broad emission peak around 520 nm is completely quenched with increasing Cu2+ content. The electron spin resonance analysis also confirms the Cu (II) ion to be doped substitutionally in CdS nanoparticles and the Lande factor of all the samples with sharp resonance is g = 2.0.

A contact for a micromechanical switch has been fabricated using electroplated gallium (Ga) on silicon to create an electrical switch contact that can be annealed to recover its original properties after mechanical damage. The resistivity of the electroplated Ga appears to be similar to pure Ga. The resistance increased with cycling but recovered to the original value after a thermal reflow process at 120 °C for 10 min. The hardness of thermally reflowed Ga droplets was 2 MPa when the droplets were unconstrained and was up to 95 MPa for constrained droplets, suggesting that all switching in this study caused permanent deformation at room temperature and that defects formed during plastic deformation are likely candidates for the increased resistance during cycling. Up to 300 switching cycles were investigated for contacts involving up to four Ga droplets to measure contact behavior under high-current and load-switching applications. Oxidation behavior was characterized for the thermal reflow process on the Ga droplets, suggesting a passivating 30-nm oxide form at 100 °C, and electrical contact resistance nanoindentation suggests the oxide breaks during mechanical contact.

An oleylamine-assisted solvothermal approach has been developed for the synthesis of nickel hydroxide nanomaterials. α-Ni(OH)2 flower-like spheres and β-Ni(OH)2 hexagonal sheets were obtained by tuning the water volume in the synthesis system. The water-induced phase and morphology evolution from α-Ni(OH)2 spheres to β-Ni(OH)2 sheets were investigated in detail by controlled experiments based on their crystal structures. Moreover, NiO spheres and sheets were obtained by direct thermal decomposition of corresponding nickel hydroxides. N2 adsorption/desorption, temperature-programmed reduction with H2, and catalytic activity tests reveal that NiO spheres exhibit higher surface area, larger pore volume, higher reducibility, and better catalysis activities for CO oxidation than NiO sheets.