3D spatially-resolved polychromatic microdiffraction was used to nondestructively obtain depth-dependent elastic strain gradients and dislocation densities in the constituent phases of a directionally solidified NiAl–Mo eutectic composite consisting of ∼500–800 nm Mo fibers in a NiAl matrix. Measurements were made before and after the composite was compressed by 5% and 11%. The Mo fibers were analyzed both in their embedded state and after the matrix was etched to expose them as pillars. In the as-grown composite, due to differential thermal contraction during cooldown, the Mo phase is under compression and the NiAl phase is in tension. After the prestrains, the situation is reversed with the Mo phase in tension and NiAl matrix in compression. This result can be explained by taking into account the mismatch in yield strains of the constituent phases and the elastic constraints during unloading. The dislocation density in both the Mo and NiAl phases is found to increase after prestraining. Within experimental uncertainty there is little discernible difference in the total dislocation densities in the Mo phase of the 5% and 11% prestrained specimens. However, the density of the geometrically necessary dislocations and the deviatoric strain gradients increase with increasing prestrain in both the Mo and NiAl phases.

Vertically aligned nanowire arrays of copper indium diselenide (CuInSe2 or CIS) of controllable diameter and length were fabricated by simultaneously electrodepositing Cu, In, and Se from an acid bath into the pores of anodized aluminum oxide (AAO) formed on top of an aluminum sheet. X-ray diffraction measurements revealed a preferential [112] orientation and the energy dispersive x-ray analysis (EDX) measurements indicated an overall composition close to stoichiometric CuInSe2. Ohmic contact to CIS was formed by depositing a 100 nm thick of gold layer on top, and thus a Schottky diode device of the Au/CIS nanowires/Al configuration was obtained. Analysis of the current–voltage characteristics of these devices yielded diode ideality factor and reverse saturate current density values slightly higher than those reported in the literature for bulk CIS/Al junctions. Capacitance–voltage measurements were performed on the diodes to get the estimates of space charge density and the junction potential.

We used conductive-atomic force microscopy (c-AFM) for electrical characterization of self-assembled epitaxial iron silicide nanowires (NWs) on Si (110). The NWs, 6 nm high by 10 nm wide and several micrometers long, were partially covered by a macro-gold-pad as one electrode. Another electrode is the conductive AFM tip. The resistance of a single FeSi2 NW was measured to be 29.7 kΩ, corresponding to a resistivity of 150 ± 30 μΩ·cm. A Schottky barrier formed between NWs and silicon substrate was clearly demonstrated, which offers electrical isolation for NWs. An equivalent circuit model based on the Schottky barrier was proposed and was correlated with measurement results. This simple electrical characterization approach may find wide applications for various one-dimensional nanostructures.

In this study, we report the synthesis of uniform and narrowly size-distributed ZnO nanoparticles with sizes of approximately 3 nm; the nanoparticles were prepared by means of organic-ligand-assisted hydrothermal conditions with various organic modifiers. The results obtained herein revealed that among the various functional groups tested (alcohols, aldehydes, carboxylic acids, and amines), only hexanol effectively controlled the nucleation and crystal growth of spherical ZnO nanoparticles. The use of hexanol also caused the surface of the ZnO particles to change from hydrophilic to hydrophobic, which would enhance the dispersion of these particles in polymer matrices, paints, cosmetics, and other organic application media.

Cr3+-doped LiInSiO4 phosphors were prepared by a solid-state reaction method. X-ray diffraction measurement was carried out for crystalline phase identification. Absorption, photoluminescence, excitation, and time-resolved spectra were measured to investigate the optical properties of the phosphors. Two broadband near-infrared emissions centered at 920 and 1172 nm were observed. Time-resolved spectra show that the emission at 1172 nm decays more quickly than the emission at 920 nm. The electron spin resonance spectra exhibit a broad resonance signal at g = 1.96 because of exchange-coupled Cr3+ pairs. The value of Dq/B for low and intermediate crystal fields was evaluated. We suggest that Cr3+ incorporated into different octahedral sites of the crystal is responsible for the different near-infrared luminescence.

The Ce-doped yttrium ortho- and pyrosilicate powders were prepared in a powder form by the formamide-modified sol-gel method. Crystal structure was checked by x-ray diffraction and sample morphology by transmission electron microscopy measurements. Both ortho- and pyrosilicate pure phases were obtained by the previously mentioned preparation procedure and proper annealing temperature was determined to obtain the maximum scintillation efficiency. Luminescence spectra and decays were measured to better evaluate the source of efficiency losses in the scintillator mechanism of samples heat-treated at lower temperatures. The potential of this preparation method for manufacturing the nanocomposite scintillators was discussed.

Congruent Er:Mg:LiNbO3 crystals were grown by the Czochralski method from the melts containing fixed 0.5 mol% Er2O3 while varied MgO content ranged from 0.0 to 8.0 mol%. The Mg and Er contents in the crystals were determined by neutron activation analysis. In the presence of Er codopant, the Mg threshold concentration with respect to optical damage is determined from the measured OH absorption spectra. The results show that the Er codopant has less effect on both the Mg threshold concentration and Mg segregation coefficient, which is within 1.13–1.23 as the Mg concentration is below the threshold while within 0.88–0.98 when above the threshold, consistent with the only MgO doping case. On the other hand, the practical Er concentration in the crystal is closely related to the Mg content and shows definite Mg threshold effect. Below the threshold, the Er concentration decreases linearly with the increased Mg concentration in the crystal; above the threshold, the decrease is more remarkable and follows another linear function. The Mg concentration effect on the Er segregation coefficient is discussed from the viewpoint of the Mg doping effect on the solubility of Er ions in the crystal.

There is a concerted effort to develop lead-free piezoelectric ceramics. (Na0.5K0.5)NbO3-based ceramics have good electrical properties, and are a potential replacement material for lead zirconate titanate piezoelectric ceramics. In this work a commercial powder based on (Na0.5K0.5)NbO3 with an initial particle size of ∼260 nm was consolidated by spark plasma sintering (SPS). To avoid volatilization, high mechanical pressures were used to minimize the densification temperature. It was found that under a uniaxial pressure of 100 MPa, fully densified compacts can be prepared at 850 °C. Ceramics densified at such a low temperature demonstrate an unusually high remanent polarization (30 μC/cm2) and high d33 (146 pC/N). The improved ferroelectric properties are ascribed to the homogeneous, dense, and submicron grained microstructure achieved.

Polycrystalline δ-phase Sc4Zr3O12 was irradiated with 200 keV Ne+ ions at cryogenic temperature to fluences ranging from 2 × 1018 to 1 × 1021 Ne/m2. Irradiation-induced structural evolution was examined by using grazing incidence x-ray diffraction and cross-sectional transmission electron microscopy. An order-to-disorder (O-D) crystal structure transformation (from an ordered δ-phase to a disordered, fluorite phase) was observed to initiate by a fluence of 2 × 1018 Ne/m2, corresponding to a peak ballistic damage dose of ∼0.075 displacements per atom. This displacement damage dose is much lower than the O-D transformation dose threshold found in previous heavy ion irradiation experiments on δ-Sc4Zr3O12 [J.A. Valdez et al., Nucl. Instrum. Methods B250, 148 (2006); K.E. Sickafus et al., Nat. Mater.6, 217 (2007)]. In this study, we contrast the O-D transformation efficiency of the light Ne ions used in these experiments, to the heavy (Kr) ions used previously, and interpret the differences in terms of enhanced damage efficiency for light ions (greater fraction of surviving defects per defect produced). To better quantify this surviving defect phenomenon, we also present new, additional ion irradiation results on δ-Sc4Zr3O12, obtained from 300 keV Kr2+ and 100 keV He+ ion irradiation experiments.

This paper reports that the homogeneous nanocrystalline LCMO(core)/SFMO(shell) and SFMO(core)/LCMO(shell) series composites are successively synthesized using polymer-network sol-gel method. With the increase of SFMO content in the composites, the remanence magnetization Mr increases while the coercivity Hc decreases. This fact indicates that the ferromagnetic phase boosts up. Moreover, the LFMR (1 T) of the composites succeeds the preponderances of both SFMO and LCMO; i.e., the magnetoresistance (MR) value increases from 300 to 5 K and keeps a high level. In particular, the MR value of the LS-8 composite reaches 55% at 5 K and 7 T.

Strontium titanate (SrTiO3) is widely used in electronic devices, and it is a model material for understanding the structural and dielectric properties of grain boundaries (GBs). In such materials, the GBs often play a dominant role in sintering and microstructural behavior. Abnormal grain growth (AGG) is a commonly observed phenomenon. Most studies explained that GBs contain continuous liquid films, and this liquid assists interface diffusion resulting in fast growth. However, few studies investigate the AGG behavior without any liquid. In this study, GB morphology and chemistry have been characterized by high-resolution transmission electron microscopy and x-ray energy-dispersive spectrometry, respectively. Different distributions of GB morphology have been observed in abnormal grains and matrix grains, and GB chemistry varies with different morphological type GBs. By correlating GB morphology and chemistry, a possible mechanism for AGG is proposed.

This study examined the degradation of the device performance of InGaZnO4 (IGZO)-based thin-film transistors after annealing at high temperatures in air ambient. Using various characterization methods including scanning electron microscopy, x-ray diffraction, and transmission electron microscopy, we were able to disclose the details of a two-stage phase transformation that led to the device performance degradation. The Mo electrodes first succumbed to oxidation at moderate temperatures (400∼500 °C) and then the Mo oxide further reacted with IGZO to produce an In–Mo–O compound with some Ga at higher temperatures (600∼700 °C). We analyzed our results based on the thermodynamics and kinetics data available in the literature and confirmed that our findings are in agreement with the experimental results.

A sequential procedure of alkaline treatment followed by SiCl4 or hydrothermal treatment has been investigated to obtain a tailored ZSM-5 catalyst for the synthesis of pyridine bases. The major function of alkaline treatment is desilication; however, it is accompanied by the extraction of framework aluminum, which formed the extra-framework alumina and amorphous alumina by realumination. Moreover, a large number of intracrystalline meso- and macropores and silanol groups are created. The desilication and realumination cause the ratio of Lewis acid sites to Brönsted acid sites (L/B) to increase. The subsequent SiCl4 or hydrothermal dealumination increases both L/B ratio and acid strength. The introduced hierarchical pores and changed acid strength distribution by the alkaline treatment improve the stability of the catalysts; the generated stronger acid sites by dealumination benefits the yields of pyridine bases; and the increased L/B by the sequential treatment promotes the selectivity of pyridine over 3-picoline.

Zr52.5Cu17.9Ni14.6Al10Ti5 bulk metallic glass (BMG) alloy samples in both rod and plate geometry were prepared. Different free volume states were obtained through thermal treatment. The plastic deformation ability of the BMGs was investigated through both a three-point bending test and compression test. The three-point bending results reveal the important role of free volume content on the formation of multiple shear bands, as the shear band propagation can be efficiently stopped due to the existence of the stress gradient from the surface to the neutral plane. In compression, the sample size rather than free volume controls the shear banding behavior.

This investigation elucidates stress evolution in situ in tin strips under electromigration using synchrotron radiation x-ray. Minute variations in stress are determined precisely using intense x-rays. Back stresses gradient with the values of 5.5 and 16.5 MPa/cm, which are induced by the current densities of 1 × 103 and 5 × 103 A/cm2, respectively, are measured directly. The effective diffusivities that include both grain and lattice diffusion at various current densities are determined. The Joule heating is observed, ranging from 5 to 15 °C, according to various current densities passed through the stripes. Results of this study suggest that the protective oxide layer on the surfaces significantly influences the kinetics of stress evolution.

This article reports on low (below 800 °C) melting temperature characteristics of a Zr-Ti-Ni-Cu alloy system, designed by adding a small amount of Cu to a Zr-Ti-Ni eutectic alloy system in the Zr-rich corner of the Zr-Ti-Ni system. A series of Zr-Ti-Ni-Cu-based alloy buttons of varying Cu content was fabricated by an arc melting machine. The melting temperature ranges of the quaternary alloys were systematically examined by differential thermal analysis (DTA). As a result, a quaternary eutectic alloy of composition Zr54Ti22Ni16Cu8 with a low melting temperature range from 774 °C to 783 °C was found. In addition, structural and chemical analysis results for the slowly solidified, quaternary eutectic alloy sample revealed equivalent quaternary eutectic structure and phases to those of the ternary eutectic Zr50Ti26Ni24 alloy, except for a small amount of Cu dissolved in individual constituent phases. The wetting angle tested at 800 °C for 60 s on the commercially pure titanium was about 25°.

To eliminate the Bi segregation and interfacial embrittlement of the SnBi/Cu joints, we deliberately added some Ag or Zn elements into the Cu substrate. Then, the reliability of the SnBi/Cu–X (X = Ag or Zn) solder joints was evaluated by investigating their interfacial reactions, tensile property, and fatigue life compared with those of the SnBi/Cu and SnAg/Cu joints. The experimental results demonstrate that even after aging for a long time, the addition of the Ag or Zn elements into the Cu substrate can effectively eliminate the interfacial Bi embrittlement of the SnBi/Cu–X joints under tensile or fatigue loadings. Compared with the conventional SnAg/Cu joints, the SnBi/Cu–X joints exhibit higher adhesive strength and comparable fatigue resistance. Finally, the fatigue and fracture mechanisms of the SnBi/Cu–X solder joints were discussed qualitatively. The current findings may pave the new way for the Sn–Bi solder widely used in the electronic interconnection in the future.

Understanding the interaction between atomic hydrogen and solid tungsten is important for the development of fusion reactors in which proposed tungsten walls would be bombarded with high energy particles including hydrogen isotopes. Here, we report results from periodic density-functional theory calculations for three crucial aspects of this interaction: surface-to-subsurface diffusion of H into W, trapping of H at vacancies, and H-enhanced decohesion, with a view to assess the likely extent of hydrogen isotope incorporation into tungsten reactor walls. We find energy barriers of (at least) 2.08 eV and 1.77 eV for H uptake (inward diffusion) into W(001) and W(110) surfaces, respectively, along with very small barriers for the reverse process (outward diffusion). Although H dissolution in defect-free bulk W is predicted to be endothermic, vacancies in bulk W are predicted to exothermically trap multiple H atoms. Furthermore, adsorbed hydrogen is predicted to greatly stabilize W surfaces such that decohesion (fracture) may result from high local H concentrations.

Minor Fe additions are necessary to enhance the corrosion resistance of commercial Cu-Ni alloys. The present paper aims at optimizing the Fe content in three alloy series Cu90(Ni,Fe)10, Cu80(Ni,Fe)20, and Cu70(Ni,Fe)30 (at.%) from the viewpoint of their corrosion performance in a 3.5% NaCl solution. An Fe/Ni = 1/12 solid solubility limit line was revealed in the Cu-Ni-Fe phase diagram. Three Fe/Ni = 1/12 alloys, Cu90Ni9.23Fe0.77 (at.%) = Cu-8.6Ni-0.7Fe (wt.%), Cu80Ni18.46Fe1.54 = Cu-17.3Ni-1.4Fe, and Cu70Ni27.7Fe2.3 = Cu-26.2Ni-2.1Fe, show the best corrosion performances in their respective alloy series. The Fe/Ni = 1/12 solubility limit is explained by assuming isolated Fe-centered FeNi12 cuboctahedral clusters embedded in a Cu matrix. The three Fe/Ni = 1/12 alloys can be respectively described by cluster formulas [Fe1Ni12]Cu117, [Fe1Ni12]Cu52, and [Fe1Ni12]Cu30.3. The Fe/Ni = 1/12 rule may serve an important guideline in the industrial Cu-Ni alloy selection because above this limit, easy precipitation would negate the corrosion properties of the Cu-Ni-based alloys.

We evaluate Vickers hardness and true instrumented indentation test (IIT) hardness of 24 metals over a wide range of mechanical properties using just IIT parameters by taking into account the real contact morphology beneath the Vickers indenter. Correlating the conventional Vickers hardness, indentation contact morphology, and IIT parameters for the 24 metals reveals relationships between contact depths and apparent material properties. We report the conventional Vickers and true IIT hardnesses measured only from IIT contact depths; these agree well with directly measured hardnesses within ±6% for Vickers hardness and ±10% for true IIT hardness.