Amorphous zinc tin oxide (ZTO) was investigated to determine the effect of deposition and postannealing conditions on film structure, composition, surface contamination, and thin-film transistor (TFT) performance. X-ray diffraction results indicated that the ZTO films remain amorphous even after annealing to 600 °C. Rutherford backscattering spectrometry indicated that the bulk Zn:Sn ratio of the sputter-deposited films were slightly tin rich compared to the composition of the ceramic sputter target. X-ray photoelectron spectroscopy indicated that residual surface contamination depended strongly on the sample postannealing conditions where water, carbonate, and hydroxyl species were adsorbed to the surface. Electrical characterization of ZTO TFTs indicated that the best devices had mobilities of 17 cm2/Vs, threshold voltages of −1.5 V, subthreshold slopes of 0.9 V/dec, turn-on voltages of −12 V, and on-to-off ratio of >107. Annealing ZTO in vacuum assisted in the removal of adsorbed species, which may reduce defects in the films and improve device performance.

Indentation load–displacement curves for Mo (100) single crystals reveal clear displacement bursts from spherical indenters with various radii from ∼0.1 to ∼130 μm. There are two different size-dependent mechanisms for dislocation evolution involved during the displacement bursts. It has been postulated that these bursts are triggered by the nucleation of dislocations for a small indenter radius and the activation of preexisting dislocations for a large indenter radius. We present a simple model with which the displacement bursts from a larger indenter radius can be rationalized. This model relates the load and the excursion length during the first displacement burst. The correspondence between the model and experimental data indicates that the displacement bursts are initiated by the activation of preexisting dislocations and the model can accurately describe the mechanism for the displacement bursts from large indenters.

To enhance the reliability of Pb-free solders in high temperature and high humidity conditions, the minor alloying elements of Be and Co are investigated in terms of the growth of Sn whiskers and various properties of Sn-based Pb-free solders. Sn whisker growth is suppressed by adding up to 0.02 wt% Be to Sn-based solders. Adding Be and Co can effectively reduce the undercooling of Sn–1.0Ag–0.5Cu (wt%) solders. And the microstructures of Sn–1.0Ag–0.5Cu–0.02Be solders are similar to those of Sn–1.0Ag–0.5Cu. Furthermore, adding Co to solders increases the microhardness number as a result of the solid solution hardening. Adding Be causes no changes in the morphology or thickness of Cu6Sn5 at the Cu/OSP (organic solderability preservative) under bump metallurgy interface. However, the scallop-like Cu6Sn5 microstructure changes to a flat (Cu,Co)6Sn5 microstructure when 0.05 wt% of Co is added to Sn–1.0Ag–0.5Cu–0.02Be solders.

Nonstoichiometric mixed ionic and electronic conductors (MIECs) find use as oxygen permeation membranes, cathodes in solid oxide fuel cells, oxygen storage materials in three-way catalysts, and chemoresistive gas sensors. Praseodymium–cerium oxide (PrxCe1−xO2−δ) solid solutions exhibit MIEC behavior in a relatively high and readily accessible oxygen partial pressure () regime and as such serve as model systems for investigating the correlation between thermodynamic and kinetic properties as well as exhibiting high performance figures of merit in the above applications. In this paper, we extend recently published results for Pr0.1Ce0.9O2−δ to include values of x = 0, 0.002, 0.008, 0.1, and 0.20 (in PrxCe1−xO2−δ) to test how both defect and transport parameters depend on Pr fraction. Important observed trends with increasing x include increases in oxygen ion migration energy and MIEC and reductions in vacancy formation and Pr ionization energies. The implications these changes have for potential applications of PrxCe1−xO2−δ are discussed.

Phosphonated polysulfones in the acid form (PPSU-As) with degree of phosphonation (DP) = 0.4, 0.75, and 0.96 were successfully synthesized and utilized for the preparation of polymer blend with sulfonated poly(ether ether ketone) (SPEEK) having a degree of sulfonation (DS) = 75. The resulted blend membranes were characterized and investigated as new polyelectrolyte membrane for fuel cells applications. SPEEK/PPSU-A blend membranes formed ionic networks through hydrogen bonding bridges between the strong sulfonic acid groups and the amphoteric phosphonic acid groups. These ionic interactions resulted in enhanced membrane properties in terms of water swelling, methanol uptake, methanol permeability, mechanical strength, and thermal stability, without significant loss of proton conductivity. All the blend membranes were transparent to visible light with presence of microphases in the order of 10–20 nm. When compared to parent SPEEK membranes, the new SPEEK/PPSU-A blend membranes showed slightly lower methanol permeability compared to neat SPEEK membrane. Membranes with 30 wt% phosphonic acid content with DP = 0.75 and 0.96, exhibited slightly higher proton conductivities at temperatures above 50 °C in comparison with Nafion membrane.

In the analysis of instrumented indentation data, it is common practice to incorporate the combined moduli of the indenter (Ei) and the specimen (E) in the so-called reduced modulus (Er) to account for indenter deformation. Although indenter systems with rigid or elastic tips are considered as equivalent if Er is the same, the validity of this practice has been questioned over the years. The present work uses systematic finite element simulations to examine the role of the elastic deformation of the indenter tip in instrumented indentation measurements and the validity of the concept of the reduced modulus in conical and pyramidal (Berkovich) indentations. It is found that the apical angle increases as a result of the indenter deformation, which influences in the analysis of the results. Based upon the inaccuracies introduced by the reduced modulus approximation in the analysis of the unloading segment of instrumented indentation applied load (P)–penetration depth (δ) curves, a detailed examination is then conducted on the role of indenter deformation upon the dimensionless functions describing the loading stages of such curves. Consequences of the present results in the extraction of the uniaxial stress–strain characteristics of the indented material through such dimensional analyses are finally illustrated. It is found that large overestimations in the assessment of the strain hardening behavior result by neglecting tip compliance. Guidelines are given in the paper to reduce such overestimations.

Time stability of the solid oxide fuel cells (SOFCs) has been a significant concern toward realization of their practical applications. Its operation at elevated temperatures and in oxidizing atmospheres makes the cathode current collector one of the most vulnerable components of the SOFCs. Silver and silver-based metal oxide [lanthanum–strontium manganite (LSM) and yttria-stabilized zirconia] composites were investigated for the development of low-cost current collectors with long-term stability. While densification of pure silver limited its use as current collector, incorporation of oxide particles to the silver matrix led to formation of porous composites. However, addition of YSZ particles did not result in a stable porosity. Analysis of the impedance spectra allowed further investigations on the obtained microstructures and the formed contacts. No microstructural degradation has been observed in the porous Ag–LSM composite current collector and its electrical properties remained stable for over 5000 h of measurements at 800 °C in air.

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.

In this article, the sizes of the volumes sampled by nanoindentation tests for hardness and modulus measurements are studied using finite element simulations. The zones of influence for hardness and modulus in single-phase systems are determined by modeling a hemispherical particle in a matrix, with properties close to those of each other, and monitoring the deviation of the measured values from those of the particle. It is found that, for hardness testing of elastic-perfectly plastic materials, the intrinsic hardness of the particle is measured as long as the plastic region is still within the particle, i.e., the contact radius is one half or less of the particle radius. Thus, in a hardness test of a single-phase material, all of the plastically deforming material, and only the plastically deforming material, contributes to the hardness measured. In contrast, the zone influencing the modulus is not restricted to a specific volume near the indenter. The modulus measured from the elastic response at the indentation point is dependent upon the entire specimen. A relationship is developed to describe the observed behavior of the measured modulus, that holds true for both sink-in and pile-up material behavior and for different indenter cone angles.

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.