In this work, the influence of Al-solutes on the mechanical behavior of Cu–AlX solid solutions has been studied using indentation strain rate jump tests for single crystalline and ultrafine-grained (UFG) microstructures from high pressure torsion (HPT) processing. Al-solutes in Cu classically lead to a solid solution strengthening, coupled with a decrease in stacking fault energy, which influences also the grain size after HPT processing. For all alloys, a higher hardness is found at lower indentation depths, which can be nicely described by a modified Nix/Gao model down to 100 nm indentation depth. Among the single crystals, the largest size effects are found for the higher solute contents, indicating a stronger work hardening at small length scales for the solid solutions. The dilute UFG solid solutions showed a strong softening after a strain rate reduction test, with a pronounced transient region. Cu–Al15 is, however, quite stable, showing abrupt changes in hardness without strong transients. This indicates that solute solution strengthening does not only influence the indentation size effect and structure formation during HPT processing but also stabilizes the grain structure during subsequent deformation.

Tungstate based phosphors have efficient absorption in the UV region and can be used for UV-pumped light emitting. For novel and effective materials and synthesis methods in this system, a series of Eu3+ and Tb3+ co-doped NaY(WO4)2 phosphors have been synthesized via the molten salt method. The powder X-ray diffraction (PXRD) patterns, scanning electronic microscope (SEM), and photoluminescent spectra have been characterized for the prepared samples. The results show the flux (NaCl) not only decreases the reaction temperature (700–900 °C) than the normal solid state synthesis (∼1000 °C), but also controls the morphology of the products. The shape and size of products can be changed simply and effectively by the reaction conditions, such as temperature and heating time. It is also found that the emission colors of the samples can be tuned from red to green by simply adjusting the doping concentrations of Eu3+ and Tb3+ ions under the same wave length excitation, which has potential applications for multi-color display and illumination as a single-component phosphor.

The development of ceramic nanomaterials with unique structure is necessary for discovery of novel property. We developed a novel niobium oxide nanoparticles with a spiky morphology. The spiky structure was composed of two kinds of component: niobium oxide hydrate sphere core and niobium pentoxide nanorods. These spiky niobium oxide nanoparticles are easily synthesized by hydrothermal treatment of niobium oxalate solution at 200 °C for 2 h, and their particle size could be tuned from 80 to 300 nm with 5–10 nm of nanorod on the surface by adjusting niobium concentration in the niobium oxalate solution. The band gap energy of the spiky nanoparticles was around 3.4 eV, and the spiky niobium oxide nanoparticles showed a light absorption in a wide wave length range from 380 to 700 nm. The niobium oxide nanoparticles are applicable as both solid acid catalyst and photocatalyst because of their spiky and two-layer structure.

Hill’48 yield function has been widely used to describe the anisotropic behaviors of material in FE simulation of tube and sheet metal forming process. To obtain the material behaviors of small-sized H96 brass extrusion double-ridged rectangular tube (DRRT) in bending process, an inverse method combining response surface method and three-point bending was proposed to identify the parameters of Hill’48 yield function. It was found that comparing with Hill’48 yield function only considering the normal anisotropy and Mises yield function, Hill’48 yield function with the identified parameters performs the best in reproducing the material behavior of H96 brass DRRT in three-point bending process. And then Hill’48 yield function with the identified parameters was also adopted in the FE simulations of rotary draw bending of DRRT. It was observed that the prediction accuracy of cross sectional deformation of DRRT in rotary bending process was improved effectively by using Hill’48 yield function with the identified parameters. This proves that the proposed inverse method is suitable to the real forming process.

Recently, solution combustion synthetic approach has emerged as a potential route to synthesize a wide range of catalytic oxides. Nano TiO2 was synthesized by solution combustion methods using glycine, urea, and oxalyldihydrazide as fuels. X-ray diffraction and field emission scanning electron microscopy analyses revealed the structural and morphological differences of TiO2 synthesized with different fuels. The oxidizer to fuel ratio from lean to rich conditions also played a crucial role in determining the polymorphic percentage concentration in the synthesized TiO2 powders. However, diffuse reflectance spectroscopy and photoluminescence spectroscopy studies did not show any significant differences in the electronic properties of the synthesized TiO2. As the polymorphic composite phases synergistically influence the catalytic performances, photodegradation of methylene blue (MB) and photo hydrogen production were studied with the synthesized catalysts. The synergistic role crucially depended on the specific reaction. The presence of different TiO2 polymorphs due to difference in fuels during combustion controlled the photocatalytic efficiency of the catalysts toward MB degradation and hydrogen production.

Two series of lithium iron phosphate (LiFePO4) nanocomposites are prepared by a solvothermal method coupled with high temperature calcination using mononuclear and binuclear metal hexaaminophthalocyanines as modulatory additives, respectively. Physical and electrochemical performances of the composites as cathode materials of lithium-ion batteries are characterized by inductively coupled plasma (ICP), X-ray diffraction (XRD), infrared (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical techniques. The results indicate that the as-synthesized samples modified with binuclear metal phthalocyanines can improve electrochemical properties of LiFePO4 (LFP) for lithium-ion batteries. The composite using binuclear manganese hexaaminophthalocyanine as additive can achieve the highest initial specific discharge capacity of 152.3 mAh/g at 0.1 C, higher than that of ones modified with the corresponding mononuclear phthalocyanine 143.0 mAh/g. Furthermore, the most excellent product exhibits a pretty good capacity retention of 93.0% after 50 cycles at 0.1 C, cycling stability, and low charge transfer resistance of 58.7 Ω.

With an aim to develop novel Cu–Zn alloys with high mechanical properties, in this study, Ni and Si elements were added to Cu–10Zn and Cu–20Zn alloys, and four kinds of Cu–Zn alloys were synthesized through gravity casting. The effect of the addition of Ni and Si on the microstructure and mechanical properties has been systematically investigated. Results revealed that the addition of Ni and Si not only refined the microstructure but also played significant roles to improve the mechanical properties of Cu–Zn alloys; δ-Ni2Si precipitates were formed in the Cu–20Zn–1.5Ni–0.34Si alloy, which obeyed a crystal orientation relationship of (001)Cu‖(001)δ and [110]Cu‖[100]δ. As compared with the Cu–20Zn alloy, the tensile strength of the studied Cu–20Zn–1.5Ni–0.34Si alloy was increased from 373.2 MPa to 776.4 MPa, and the yield strength increased from 242.1 MPa to 718.4 MPa. Operative strengthening mechanisms in the Cu–20Zn–1.5Ni–0.34Si alloy with different thermal-mechanical treatment states will be discussed in detail with the aim to draw a new strategy to develop high strength brass alloys.

Isolated single quantum dots (QDs) enable the investigation of quantum-optics phenomena for the application of quantum information technologies. In this work, ultralow-density InAs QDs are grown by combining droplet etching epitaxy and the conventional epitaxy growth mode. An extreme low density of QDs (∼106 cm−2) is realized by creating low-density self-assembled nanoholes with the high temperature droplet etching epitaxy technique and then nanohole-filling. The preferred nucleation of QDs in nanoholes has been explained by a theoretical model. Atomic force microscopy and the photoluminescence technique are used to investigate the morphological and optical properties of the QD samples. By varying In coverages, the size of InAs QDs can be controlled. Moreover, with a thin GaAs cap layer, the position of QDs remains visible on the sample surface. Such a low density and surface signature of QDs make this growth method promising for single QD investigation and single dot device fabrication.

Ni/Sn–xZn/Ni (x = 1, 5, 9 wt%) joints were used to investigate the effect of Zn content on interfacial reactions during reflow under a temperature gradient. Asymmetrical growth and transformation of intermetallic compounds (IMCs) occurred between the cold and hot end interfaces. Faster IMC growth at the cold end and a more prompt IMC transformation at the hot end in a lower Zn content solder joint were identified due to the more thermomigration-induced Zn and Ni atomic fluxes toward the cold end. The main diffusion species into IMC layers changed from Zn atoms at the early stage to Sn and Ni atoms at the later stage. As a result, the IMC evolution followed (Ni,Zn)3Sn4 → Ni3Sn4 in the Ni/Sn–1Zn/Ni joint, Ni5Zn21 → τ phase → Ni3Sn4 in the Ni/Sn–5Zn/Ni joint, and Ni5Zn21 → τ phase in the Ni/Sn–9Zn/Ni joint along with the reflow time. A higher Zn content could effectively inhibit the dissolution of the hot-end Ni substrate and restrain the growth rate of the cold-end interfacial IMCs.

Probing the distribution of donor and acceptor molecules in the active layer of polymer solar cells requires high-resolution methods that provide chemical contrast. A combination of the synchrotron-based soft X-ray technique near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and scanning transmission X-ray microscopy (STXM) can map surface composition and local composition in lateral phase-separated domains, as well as identify molecular signatures of degradation. Here we illustrate, by way of selected results, the relevance of these complementary techniques to the field of organic photovoltaics. We demonstrate firstly that the determination of local composition from X-ray absorption spectra requires cautious use of fitting techniques. Furthermore, we show that drop-like clusters of PC70BM formed during the transfer of spin-coated polymer:PC70BM blend films onto Cu-grids lead to an underestimation of PC70BM/polymer concentration ratios. Finally, we show that the selective degradation of one of the components can impair the accurate determination of local blend composition.

Comparative studies between doped conducting polymers and electrochemical deposited organometallic compounds reveals the interplay between crystalline-amorphous phases with significant contributions to the internal quantum efficiency in the OLED devices. The coexistence of the amorphous and crystalline phase in the electrodeposited film is revealed by the minor micro-crystal products which are present in the amorphous phase in thin films, while the many micro-crystals are randomly distributed in the thick films. Concerning the doped conducting polymers, the level of doping induces crystalline effects as a result of the π–π stacking between molecules, due to the Forester energy transfer processes in which the transfer rate is increased with decreasing of the distances between neighboring molecules. The crystallization processes change the emission properties of the active layers both for the luminance level and all over color, ranging from yellow to red in the case of IrQ(ppy)2 compounds.

Bulk metallic glasses own unique mechanical properties such as high strength and excellent elastic behavior due to their amorphous atomic structure. Nonetheless, they usually fail catastrophically by shear localization without showing any macroscale plastic deformation under tension and therefore are notoriously brittle. In this study, graphene was proposed as an effective reinforcement to improve the ductility and toughness of metallic glass for possessing a unique combination of strong in-plane strength and weak interbonding with the metal matrix based on molecular dynamics simulations. Both continuous and discontinuous graphene sheets with various configurations and lengths were taken into account. It was found that with proper dispersion of the graphene reinforcements, more than 100% increase in the ductility and more than 150% increase in the toughness can be achieved in the nanocomposites as compared to the monolithic metallic glass of similar size, which was enabled by spreading and delocalizing the plastic shearing deformation in the nanocomposites because of the dual effects of the added graphene.

CoxPb1−x nanowire arrays within an anodic aluminum oxide (AAO) template were electrodeposited from an appropriate acetate bath by applying alternating current (ac). The effect of the Pb content on magnetic properties of nanowire arrays was investigated. By adding Pb2+ to an electrolyte containing Co2+, the coercivity field of nanowires decreased from 1508 Oe in Co100 to 921 Oe in Co92.5Pb7.5 while squareness increased from 0.74 for Co nanowires to about 0.82 for Co92.5Pb7.5 nanowire alloy sample. The effect of annealing on the magnetic properties of nanowires in the temperature range between 300 °C and 600 °C was also investigated. It was observed that the coercivity field of Co97.5Pb2.5 nanowire increases from 1290 Oe at room temperature to 1785 Oe at 600 °C. Furthermore, the effect of electrodeposition frequency on the magnetic properties of Co97.5Pb2.5 nanowires was studied. The coercivity was enhanced with increasing frequency; however, after annealing all samples exhibited enhanced coercivity regardless of the electrodeposition frequency.

By using a combination of experiments and molecular dynamics simulations, our studies show that the elastic response of silica glass to initial compression gradually changes from abnormal to normal with increasing quench pressure, helium content or alkali modifier added in the glass matrix. We uncovered the structural origin of the elastic anomaly in silica glass as localized structural transitions between motifs of different stiffness that are similar to those found in its crystalline counterparts. Pressure-quenching, helium-stuffing, or alkali-modifying plays a different role in changing the structure of silica glass, but all of the resulting structures reduce the propensity for such local structural transitions to take place, thus the degree of elastic anomaly. Our studies demonstrate that by processing in ways that gradually eliminates the elastic anomaly, the degree of silica glass to undergo irreversible densification can be eventually eradicated. This provides a solid foundation for the bottom-up design of new glasses with tunable structure and properties.

Mg–3Al–Zn alloy with the addition of Al and Si as a eutectic alloy was subjected to conventional hot rolling. The corresponding mechanical properties, microstructure evolution, and dynamic recrystallization mechanism were investigated by optical microscope, scanning electron microscope, electron backscattered diffraction (EBSD), and tensile tests. The experimental results indicated that the Mg–3(Al–Si)–Zn alloy had a microstructure refinement, thus rendering an enhanced mechanical properties in comparison with the Mg–3Al–Zn alloy. The refined Mg2Si particles could act as potential nucleation sites for recrystallization in as-rolled Mg–3(Al–Si)–Zn alloy sheets, which resulted in more completely recrystallized regions through particle stimulated nucleation and a weakened basal texture compared to Mg–3Al–Zn alloy. The improvement in the tensile strength of the as-rolled Mg–3(Al–Si)–Zn alloy can be attributed to grain refinement and second phase strengthening caused by the refined Mg2Si particles.