Resistive memory devices have the potential to replace flash technology due to their increased scalability, low voltage of operation, and compatibility with silicon semiconductor manufacturing. We report a spin-on resistive switching material, hydrogen silsesquioxane (HSQ), which is a commonly used electron beam resist. We demonstrate device scalability from 100 μm to 48 nm and show that the switching properties do not depend on the device size. Set voltages were typically <3 V, while reset voltages were <1 V when analyzing the positive unipolar switching properties of these devices. The ratio of the high resistance to the low resistance was ranged from 101 to 102, creating a distinct memory window between the memory states. Composition–depth profiling revealed that copper from the bottom electrode migrated into the HSQ films as a result of annealing. It is therefore speculated that copper may play a role in the switching properties of devices based on this material.

Cu–In–Ga precursor thin films were deposited onto soda lime glass by magnetron cosputtering CuIn and CuGa alloy targets. After that, Cu(In,Ga)Se2(CIGSe) absorbers were formed by selenizing those alloy precursors with Se vapor at 550 °C. The influence of the precursor temperature on the properties of CIGSe thin film was investigated. The results show that a lot of pinholes existed in the CIGSe thin film produced by selenizing the Cu–In–Ga alloy precursor, which was sputtering deposited at ambient temperature. After sputtering substrate temperature of 250 °C was applied, pinholes were avoided. The surface roughness of Cu–In–Ga precursor increased with the increase of sputtering substrate temperature. Due to the volume expansion of selenization process, even the precursor with high surface roughness could be converted to smooth and compact CIGSe thin film.

One-dimensional (1D) nanofibers of polypyrrole (PPY) are fabricated on glass substrates in the presence of different dopants, namely, hydrochloric acid (HCl), ferric chloride (FeCl3·6H2O), p-toluene sulfonic acid, camphor sulfonic acid, and polystyrene sulfonic acid using a simple in situ vapor phase chemical oxidative polymerization method. Preliminary morphological details investigated using light microscopic study reveal 1D configuration for all the doped PPY structures, indicating a fibrous/tubular appearance. Furthermore, scanning electron microscopy confirms preferential growth of these PPY structures as fine fibers arranged in a brush-/comb-like pattern, having an average diameter of 70 nm. Such brush-like growing pattern observed for the PPY nanostructures without the aid of nanoporous membranes and/or sophisticated techniques is not very commonly reported in the literature. The undertaken work suggests applications of nanodimensioned fabricated PPY structures in the practical nanodevices and/or functional glass for sensing, optoelectronic, photocatalysis, and solar energy systems.

In this work, different methods to estimate the value of thin film residual stresses using instrumented indentation data were analyzed. This study considered procedures proposed in the literature, as well as a modification on one of these methods and a new approach based on the effect of residual stress on the value of hardness calculated via the Oliver and Pharr method. The analysis of these methods was centered on an axisymmetric two-dimensional finite element model, which was developed to simulate instrumented indentation testing of thin ceramic films deposited onto hard steel substrates. Simulations were conducted varying the level of film residual stress, film strain hardening exponent, film yield strength, and film Poisson’s ratio. Different ratios of maximum penetration depth hmax over film thickness t were also considered, including h/t = 0.04, for which the contribution of the substrate in the mechanical response of the system is not significant. Residual stresses were then calculated following the procedures mentioned above and compared with the values used as input in the numerical simulations. In general, results indicate the difference that each method provides with respect to the input values depends on the conditions studied. The method by Suresh and Giannakopoulos consistently overestimated the values when stresses were compressive. The method provided by Wang et al. has shown less dependence on h/t than the others.

A clickable surface was prepared using nanoporous SBA-15 support. Methylimidazolium, an ionic liquid, was immobilized on this surface through the click reaction. Detailed characterization using nitrogen adsorption, elemental analysis, x-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis showed that the ionic system was fixed inside the channels and the ordered porous structure remained stationary. Influence of this material on photoluminescence emission of 5-amino-4-hydroxy-7-sulfonaphthalene-2-sulfonate anion (H-acid) in aqueous solutions was evaluated. This click reaction product can be used effectively for H-acid removal from wastewater.

We investigated the conductivity of high-density bulk-anatase samples with a grain size between 24 and 56 nm prepared by high pressure field-assisted sintering. When exposed to humid atmosphere, the insurgence of proton conductivity was observed for temperatures below 350 °C. Below this temperature, the samples showed a conductivity several orders of magnitude higher than that measured under dry oxygen atmosphere. The protonic conductivity strongly increased as grain size decreased, while a negligible dependence from porosity was observed when the latter ranged between 8 and 25 vol%. If compared with zirconia- and ceria-based nanomaterials with similar grain size, bulk nanometric anatase showed the highest low temperature protonic conductivity as well as the highest crossover temperature between dry and humid conduction behavior.

Characterizing the residual stress of thick nanocrystalline electrodeposits poses several unique challenges due to their fine grain structure, thickness distribution, and matte surface. We use a three-dimensional profilometry-based approach that addresses each of these complicating factors and enables quantitative analysis of residual stress with reasonable accuracy. The specific emphasis of this work is on thick (10–100 μm), nanocrystalline Ni-W electrodeposits of the finest grain sizes (4–63 nm), in which residual stresses arise during the deposition process as well as during postdeposition annealing. The present measurements offer quantitative insight into the mechanisms of stress development and evolution in these alloys, suggesting that the grain boundary structure is out of equilibrium (unrelaxed) and contains the excess free volume that controls the resulting residual stress levels in these films. There are apparently two factors contributing to this stress: the percentage of excess free volume contained in the grain boundaries, which is affected by the processing conditions, and the total volume fraction of grain boundaries, which is controlled by the grain size.

Carbide precipitation within low carbon AISI H13 hot work tool steel that had either been quenched at 80 °C or cryogenically treated at −196 °C prior to tempering has been examined using micrometer-scale synchrotron diffraction mapping. Vanadium-rich cubic M8C7 carbide, lattice parameter of approximately 0.8610 nm, not identifiable using laboratory powder x-ray diffraction (PXRD), was found to be present in all samples. The concentration of this phase was greatest in the rapidly cooled cryogenically treated sample. However, all cryogenic treatments resulted in greater carbide concentrations than in the quenched sample. In addition rapid cryogenic cooling by immersion in liquid nitrogen (N2), as compared with slow cooling to −196 °C over a 3 h duration, results in greater order within the carbide phase subsequent to tempering, as interpreted by analysis of unit cell size variation, and the smallest stress, as interpreted by diffraction peak full width half maximum height distributions.

An analysis of indentation hardness data from three ceramic materials, zirconium diboride, silicon carbide, and titanium nitride, is presented to extract the fundamental deformation parameters at 295 to 623 K. The measured activation volume was of the order of 1 × b3 to 4 × b3 (b is the Burgers vector). The calculated activation energies were in the range of 0.75 to 1.61 eV and are typical of lattice-controlled dislocation glide mechanism. Using finite difference simulations, it was demonstrated that there is a significant difference between the plastic strain rate and the total strain rate for materials showing substantial elastic deformation (i.e., large hardness/elastic modulus ratio). Therefore, the measured total strain rates must be converted into plastic strain rates, which require a reduction during loading and an increase during the dwell at maximum load. Additionally, importance of quantification of instrumental thermal drift was discussed and use of either short duration indentation tests or high loads was emphasized.

A freestanding bulk nanoporous copper with ultralow density has been fabricated through dealloying of as-cast dual-phase Cu1Mn1Al8 alloy, and the dealloying behavior was investigated systematically. The experimental results show that due to different electrochemical activities, the Al11Cu5Mn3 phase of the dual-phase precursor alloy dissolved before AlCu2Mn, which corresponds to the dramatical evolutions of microstructure and composition. Additionally, a formation pattern based upon a mechanism combined “dissolution–redeposition” pattern, “phase-separation” pattern, and “coarsening” process has been built to describe the evolution process, which includes four stages, sequentially defined as “dissolution of Al11Cu5Mn3,” “redeposition of Cu atoms,” “dealloying of AlCu2Mn,” and “coarsening.”

Nanomechanical testing of silicon is primarily motivated toward characterizing scale effects on the mechanical behavior. “Defect-free” nanoscale silicon additionally offers a road to large deformation permitting the investigation of transport characteristics and surface instabilities of a significantly perturbed atomic arrangement. The need for developing simple and generic characterization tools to deform free-standing silicon beams down to the nanometer scale, sufficiently equipped to investigate both the mechanical properties and the carrier transport under large strains, has been met in this research through the design of a versatile lab-on-chip. The original on-chip characterization technique has been applied to monocrystalline Si beams produced from Silicon-on-Insulator wafers. The Young’s modulus was observed to decrease from 160 GPa down to 108 GPa when varying the thickness from 200 down to 50 nm. The fracture strain increases when decreasing the volume of the test specimen to reach 5% in the smallest samples. Additionally, atomic force microscope-based characterizations reveal that the surface roughness decreases by a factor of 5 when deforming by 2% the Si specimen. Proof of concept transport measurements were also performed under deformation up till 3.5% on 40-nm-thick lightly p-doped silicon beams.

Polyaniline (PANI) microtubes were successfully synthesized by a simple way without using any templates. Their structure was characterized by scanning electron microscopy, transmission electron microscopy, x-ray diffraction, ultraviolet–visible absorption spectra, and Fourier transform infrared spectroscopy. The average length and diameter of the microtubes were about 12.0 and 3.0 μm, respectively. In addition, silver microrods were further prepared using the PANI microtubes as templates. Scanning electron microscopy, energy-dispersive x-ray spectra, x-ray diffraction, and ultraviolet–visible absorption spectra analyses were performed to characterize the structure of the sample. The results indicated the formation of silver microrods inside PANI microtubes. Moreover, the microwave absorption and electrical properties of PANI microtubes, PANI particles, and silver microrods were compared. It shows that the silver microrods coated with PANI have good microwave absorption and electrical properties, which can apply on electromagnetic interference shielding and microwave absorption materials.

Electrical conductivity and magnetic properties of core-shell silver-coated magnetite composite nanoparticles prepared by electroless deposition of silver on magnetite nanopowder are found to be affected mainly by the pressure used when preparing the nanoparticles sample cylinder and the Ag content in the nanoparticles. The electrical conductivity can be enhanced by increases of both the pressure and the Ag content. Direct current volume electrical resistivity of the nanoparticles with 40 wt% silver content is close to the order of 10−4 Ω cm when the pressure is larger than 1 × 106 Pa. The saturation magnetization of the nanoparticles almost reduces linearly with increasing the silver content. According to the rule of mixtures, the resistivity of the nanoparticles is calculated. But it shows that the calculated values have a large deviation with the corresponding measured ones. As a comparison, resistivity and saturation magnetization of the mixtures consisting of silver and magnetite nanopowder are also measured. It will be an effective method to adjust the electromagnetic properties of the nanoparticles by changing the silver content.

Forced chemical mixing during severe plastic deformation was investigated at Cu-Nb face-centered-cubic (fcc)/body-centered-cubic (bcc) interfaces using molecular-dynamics simulations. Three Cu-Nb interfaces were considered, with either Kurdjumov-Sachs or Nishiyama-Wassermann orientation relationship (OR) between fcc and bcc phases. Forced mixing of a spherical bcc-Nb precipitate in fcc-Cu was also studied for comparison. Deformation was imposed by shape-preserving cycles using two different modes, biaxial compression and biplanar shearing to investigate the effects of strain path. For biplanar shear, the chemical mixing rate is strongly dependent on structure of the interface, with the Kurdjumov-Sachs OR and a (111)Cu‖(110)Nb habit plane being particularly resistant to mixing. During compression, no such dependence was found. Influences of interface diffuseness and roughness on stability were also investigated. The simulations show the interface mixing is inversely related to interface shear strength during shear deformation, but dominated by dislocation-glide through the Cu phase and subsequent absorption at Cu-Nb interfaces during compression deformation.

A nanoparticle catalyst of PtRuAu/C was synthesized by including an Au precursor in the radiolytic process for preparing a PtRu/C catalyst. Their methanol oxidation activity and electrochemical durability were measured by linear sweep voltammetry before and after potential cycling treatment. PtRuAu/C had a significantly higher durability than PtRu/C while maintaining a comparable high activity. The morphology and substructure of the nanoparticles were investigated by energy-dispersive x-ray spectroscopy, x-ray diffraction, and x-ray absorption fine structure spectroscopy. Metallic nanoparticles with diameters of about 2 nm were obtained; they probably had Pt-core/PtRu-shell structures. Transmission electron microscopy observations after potential cycling revealed that 2-nm-diameter nanoparticles containing Au did not coarsen, whereas nanoparticles without Au coarsened significantly to 3.7 nm. Some crystal defaults were observed in the coarsened particles, implying that the coarsening was caused by Ostwald ripening. The Au addition to catalyst particles consisting of PtRu inhibits coarsening and consequently improves the electrochemical durability.

Porous platinum thin films were prepared by thermal decomposition at temperatures from 25 to 675 °C of platinum oxide films deposited by a pulsed reactive sputtering technique. The samples’ chemistry and structure were investigated by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and x-ray absorption near edge structure (XANES), showing that the decomposition of the oxide begins as low as 400 °C and follows a sigmoidal trend with increasing annealing temperature. In the XRD spectra, only an amorphous-like signature was observed for temperatures below 575 °C, while Pt 4f XPS showed that the deposited oxide was a mixture of PtO2 and PtO. Pt-L3 edge XANES and Pt 4f XPS spectra showed that the Pt concentration and electronic structure are predominant for temperatures equal to or above 575 °C. The morphologies of the films were investigated by the area-perimeter method from atomic force microscopy and scanning electron microscopy (SEM) images, indicating that the surfaces exhibit a combination of Euclidian and fractal characteristics. Moreover, the thermal evolution of these characteristics indicates the agglomeration of the grains in the film as observed by SEM.

Nitrogen-doped titanium dioxide (denoted as N-doped TiO2) nanomaterials were prepared through the ion exchange of sodium titanate nanotube (the precursor; denoted as STN) with aqueous NH4Cl and follow-up sintering at different temperatures in air. The morphology, structure, surface component, and optical properties of as-obtained N-doped TiO2 nanomaterials have been analyzed by transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and ultraviolet–visible light diffuse reflectance spectrometry. The formation mechanism and the origin of the visible light absorption for N-doped TiO2 nanomaterials have been discussed. Moreover, the thermogravimetric analysis and differential thermal analysis of N-doped TiO2 nanomaterial calcined at 100 °C are conducted as an example to examine the thermal stability of as-synthesized N-doped TiO2. It has been found that, as the calcination temperature rises, the initial nanotubular morphology of STN is transformed to the final nanoscale granular one, accompanied by a phase transformation from orthorhombic crystalline system to anatase TiO2. The N content in N-doped TiO2 is 7.04%, 6.22%, 3.20%, 1.14%, 0.61%, and 0.40% (atomic percentage), depending on calcination temperature rising from 100 to 600 °C. Moreover, N-doped TiO2 samples experience three stages of weight losses, and that calcinated at 300 °C and above have strong visible light absorption, due to the formation of Ti–O–N bonds thereat.

The asymmetrical hysteresis loops of the longitudinal field annealed Co58Fe5Ni10Si11B16 amorphous ribbons were studied. Longitudinal magnetic training was deliberately performed on the annealed samples with exchange bias behavior. It was found that the shifted loops can be technically controlled by training the ribbons to modulate the abnormal magnetic features. The scanning probe microscope results reveal that the AC longitudinal magnetic training can decrease the vertical magnetic signal on the sample surface to a great extent. This skillful magnetic training method provides an approach to tailor the exchange bias behavior in the Co-based amorphous ribbons for potential applications.

Physical and chemical properties of solid materials are modified by introducing defects, which disarrange the atomic periodic structure. Typical example is oxygen vacancies on titanium dioxide (TiO2) surfaces. Oxygen vacancies on TiO2 surfaces provide new physical and chemical surface properties, such as conductivity, catalytic activity, hydrophilicity, etc. To date, annealing, electron-/photo-stimulated desorption, and chemical reaction have been reported to create oxygen vacancies on TiO2 surfaces. However, these techniques do not allow position control of the defects at the atomic scale. We report the creation of single oxygen vacancy using a scanning tunneling microscope (STM). This technique creates oxygen vacancy at desired site. In addition, based on the experimental findings, we discuss the mechanism of manipulating atomic defects using the STM.

Friction forces for a nanowire (NW) elastically bent on flat substrate were investigated both theoretically and experimentally. Models based on elastic beam theory were proposed considering balance of external, frictional, and elastic forces along the NW. The distributed friction force was determined for two cases: (i) the NW was uniformly dragged at its midpoint and bent by kinetic friction forces and (ii) the NW was held in a bent state by static friction forces. The first case considers a uniform distribution of kinetic friction along the NW and enables the measurement of the friction force from the elastically deformed NW profile. The second case exploits the interplay between static friction and elastic forces inside the NW to find the distributed friction force. An original method for the measurement of frictional forces in both cases while maintaining total force and momentum equilibrium was introduced and demonstrated for ZnO NWs on a Si wafer. Averaged kinetic and static friction forces were compared for the same individual NW.