With 2 mol% Zn2+ codoping and 2 mol% K+ charge compensation, the red-emitting phosphor [K0.8Y0.63Eu3+0.08Zn0.02][Mo0.2W0.8O4] was synthesized by solid-state reaction. X-ray powder diffraction spectrum indicates that it owns single phase. Through its emission spectra, excitation spectra, and fluorescence decay curves measured, its emission mechanism was mentioned and it was calculated for its partial J-O parameters and quantum efficiency of Eu3+ 5D0 energy level under 395 nm excitation. The results indicate that Eu3+ 5D0 → 7F2 red luminescence in the host can be excited by 395 nm, but its quantum efficiency can be improved in space and it has potential applications for white light-emitting diode as the red luminescent materials.

Ni- and Cu-free Zr–Al–Co–Ag bulk metallic glasses (BMGs) with diameters up to 20 mm were synthesized by copper mold casting. The effects of Ag alloying on the superior glass-forming ability (GFA) of Zr–Al–Co–Ag alloys were studied based on the localized atomic structure and crystallization behavior. High-energy synchrotron radiation x-ray diffraction result reveals that Ag addition in Zr–Al–Co system results in a more homogeneous local atomic structure, which could be an origin for the improved GFA of the Zr–Al–Co–Ag alloy. Crystallization products of the Zr–Al–Co–Ag glassy alloy are more complex than those of the Zr–Al–Co glassy alloy. The Zr–Al–Co–Ag BMGs free from highly toxic elements Ni and Cu exhibited a combination of superior GFA, high compressive fracture strength over 2000 MPa, low Young’s modulus of 93 to 94 GPa, and good corrosion resistance in phosphate-buffered solution (PBS), inspiring their potential biomedical applications.

The macroscopic electromechanical coupling properties of ferroelectric polycrystals are composed of linear and nonlinear contributions. The nonlinear contribution is typically associated with the extrinsic effects related to the creation and motion of domain walls. To quantitatively compare the macroscopic nonlinear properties of a lead zirconate titanate ceramic and the degree of domain orientation, in-situ neutron and high-energy x-ray diffraction experiments are performed and they provide the domain orientation density as a function of the external electric field and mechanical compression. Furthermore, the macroscopic strain under the application of external electrical and mechanical loads is measured and the nonlinear strain is calculated by means of the linear intrinsic piezoelectric effect and the linear intrinsic elasticity. The domain orientation density and the nonlinear strain show the same dependence on the external load. The scaling factor that relates to the two values is constant and is the same for both electrical and mechanical loadings.

Oxidized starch (OSt) films reinforced with natural halloysite were prepared by adding modified natural halloysite nanotubes into an OSt matrix. The halloysite/OSt films were characterized by x-ray diffraction, scanning electron microscopy, and ultraviolet spectrometry. The mechanical properties and moisture absorbability of the films were also studied. The modified halloysite nanotubes were well distributed in the starch matrix, and the tensile strength (TS) of the films was greatly enhanced, but the moisture adsorption ability of the films only changed slightly. The flexibility of the films was improved by adding glycerol but at a cost of reducing the TS. Incorporating a small amount of poly(vinyl alcohol) (PVA) improved both the TS and the percent elongation at break of the halloysite/OSt films.

Shape control of nanocrystals has become an indispensable part in material research, such as developing new battery raw materials and synthesizing high activity catalysts. In this work, one-dimensional LiV3O8 nanorods have been fabricated by high temperature solid-state reaction using V2O5 nanowires as precursors obtained via a hydrothermal method. The as-prepared LiV3O8 nanorods were characterized by x-ray diffraction, transmission electron microscopy, scanning electron microscopy, and galvanostatic tests, compared with LiV3O8 samples synthesized by the traditional one-step solid-state method. The results show that LiV3O8 nanorods exhibited better electrochemical performance than those synthesized by the traditional method, indicating that a different shape will lead to huge distinctions in electrochemical properties. This work demonstrates that Li-insertion/deintercalation dynamics might be crystal morphology-sensitive.

We present a low-temperature, hydrothermal synthesis method for Ta-doped TiO2. Here, alkoxide-based precursors are mixed at low temperatures to suppress differential hydrolysis and phase separation. This method ensures homogeneous, molecular mixing of the Ta dopant with the native oxide up to a concentration of ∼2.5 at.%. X-ray diffraction and energy dispersive spectrometer analyses confirm a uniformly doped rutile TiO2. Scanning electron microscopy and transmission electron microscopy analyses reveal a highly branched structure. Optoelectronic properties of these structures were investigated using ultraviolet-visible spectroscopy and low-temperature photoluminescence.

Al–AlN composite powders containing 9–55 vol%AlN were fabricated in situ by nitriding a powder mixture of AA6061–2% Mg–1% Sn at 560 °C. Transmission electron microscopy (TEM) revealed that the in situ formed AlN reinforcements are present as nanoscale AlN whiskers on each powder particle. The composite powder was consolidated by hot extrusion at 450 °C with an extrusion ratio of 11:1. This produced an AlN-free and an AlN-containing lamellar structure along the extrusion direction. The nanoscale AlN is dispersed in the AlN-containing lamella and shows excellent bonding with the Al matrix, free of decohesion and voids. The lamellar composite containing 9 vol%AlN has an ultimate tensile strength of 332 MPa and tensile elongation of 3%. Composites containing ≥17.5 vol%AlN achieve much higher tensile strengths (538 MPa) but zero tensile elongation. However, they show a low coefficient of thermal expansion up to 450 °C and may therefore have potential for selected elevated temperature applications.

A nanoindentation strain-rate jump technique has been developed for determining the local strain-rate sensitivity (SRS) of nanocrystalline and ultrafine-grained (UFG) materials. The results of the new method are compared to conventional constant strain-rate nanoindentation experiments, macroscopic compression tests, and finite element modeling (FEM) simulations. The FEM simulations showed that nanoindentation tests should yield a similar SRS as uniaxial testing and generally a good agreement is found between nanoindentation strain-rate jump experiments and compression tests. However, a higher SRS is found in constant indentation strain-rate tests, which could be caused by the long indentation times required for tests at low indentation strain rates. The nanoindentation strain-rate jump technique thus offers the possibility to use single indentations for determining the SRS at low strain rates with strongly reduced testing times. For UFG-Al, extremely fine-grained regions around a bond layer exhibit a substantial higher SRS than bulk material.

We evaluated the optical and electrical characteristics of SnO2 hybrid films with various contents (0, 0.05, 0.1, 0.15, and 0.2 at.%) of Pt nanoparticles. The Pt nanoparticles were synthesized by a methanol reduction method, and their size was restricted to an average of 3 nm using poly(N-vinyl-2-pyrrolidone) as a protecting agent. An enhancement in electrical properties was observed due to the addition of Pt nanoparticles; the lowest resistivity (1.36 × 10−2 Ω·cm) and the highest figure of merit (1.18 × 10−4 Ω−1) were obtained with SnO2 film containing 0.15 at.% Pt nanoparticles after annealing at 600 °C, and the average transmittance in the visible region was 86.61%. Well-defined 30-μm-wide direct-patterned SnO2 films containing Pt nanoparticles were formed by photochemical metal-organic deposition through a simple process including a photosensitive starting precursor, ultraviolet exposure, and removal of the unexposed area with solvent rinsing.

We demonstrate Er3+ diffusivity and solubility increases in off-congruent, Li-deficient LiNbO3 crystal. Li-poor vapor transport equilibration was used to reduce Li2O content in initial congruent crystals. Local Er3+ in-diffusion was then performed in a wet O2 atmosphere. Before and after the Er3+ diffusion procedure, surface Li2O content was evaluated from measured birefringence. The results show that the Er3+ diffusion procedure resulted in 0.3–0.5 mol% Li2O content loss at crystal surface. Secondary ion mass spectrometry was used to measure the Er3+ depth profiles, from which the diffusivity and solubility are determined. It is shown that the Er3+ diffusivity is nearly doubled and the solubility increases at least 0.6 mol% as the Li2O content decreases by 1.0 mol%. From the known Li2O content reduction, the solubility increase is also predicted and the results show that the predicted data are considerably smaller than the experimental results, suggesting that the Er3+ ions occupy also the Nb5+ site, besides the Li+ site.

Microstructural investigation and thermodynamic simulation were carried out to study precipitation during the solidification of AZ31 Mg alloy containing up to 1wt% Sr. Increasing Sr content from 0.01 to 1 wt% led to the formation of an Al–Sr line compound (Al4Sr) and to the suppression of Al–Mg precipitate (β-Mg17Al12). Transmission electron microscopic (TEM) investigation and energy dispersive spectroscopic analysis on extracted precipitates revealed Mg and Zn solubility in the Al4Sr particles. It is shown that Sr content also affects the precipitation of Al–Mn precipitates. Thermodynamic calculations predict that the increase in Sr content limits the Al–Mn reaction and the precipitation of Al–Mn precipitates with low Al/Mn ratio. Microstructural investigations determined the presence of two Al–Mn precipitates (Al8Mn5 and AlMn), either in the form of large dendritic plates or small nano-scale particles in the Mg matrix. It has been calculated by the thermodynamic model and confirmed by TEM that by increasing the Sr content, solubility of Al solid decreases whereas the level of Mn increases slightly.

We report on the electrochromic response of as-deposited and annealed nanostructured molybdenum trioxide films prepared with the glancing angle deposition (GLAD) technique. Morphology of the as-deposited films, obtained with an atomic force microscope (AFM), showed a typical grain size of 10 to 50 nm diameter. After annealing, the AFM images clearly showed the dominant presence of a layered structure, characteristic of the orthorhombic (α) phase of molybdenum trioxide, with typical grain dimensions of a few micrometers. The annealed samples showed pronounced coloration in the visible and near-infrared regions of the electromagnetic spectrum, while the as-deposited samples showed significant coloration only in the visible region.

To answer the fundamental questions of p-type skutterudites, systematical study on the influence of chemical composition on the electrical transport properties of RyFexCo4−xSb12 (R = Ce and Yb) has been carried out. By adjusting the filling fraction of fillers, the optimized electrical properties are obtained at the specific Fe content. It is found that the hole concentration increases with Fe content. Fe doping can also enhance the effective mass of holes significantly, which is beneficial for improving electrical performance. Because of the limit of electron supply, for trivalent Ce filling system CeyFexCo4−xSb12, the maximum figure of merit (ZT) value is achieved when Fe content is around x = 3, and for divalent Yb filling system YbyFexCo4−xSb12, the maximum ZT value is obtained even at lower Fe content. At high temperature above 700 K, the bipolar diffusion leads to great increase of total thermal conductivity and therefore deteriorates the thermoelectric properties.

Oxygen vacancy-related surface defects on porous TiO2 films were reduced by oxygen ion-beam treatment, and the effect of such defects on the performance of dye-sensitized solar cells was examined. An oxygen ion-beam treatment of a TiO2 film caused a significant decrease in particle agglomeration and an increase in surface area of the resulting TiO2 film. In addition, the increased hydrophilicity of the TiO2 film by the ion beam treatment led to an increase in dye adsorption. The oxygen ion beam treatment at 500 and 1000 eV caused a significant decrease in oxygen vacancies and increase in the open-circuit voltage (Voc). Oxygen ion beam–treated TiO2 film electrodes showed the maximum solar-to-electricity conversion efficiency (η%) of 8.04% compared to the 6.15% obtained from an untreated TiO2 electrode.

Epitaxially oriented silicon nanowires (SiNWs) were grown on (111) Si substrates by the vapor–liquid–solid technique in an atmospheric-pressure chemical vapor deposition (APCVD) system using Au as the catalyst and SiCl4 as the source gas. The dependencies of SiNW growth rate on the growth temperature and SiCl4 partial pressure (PSiCl4) were investigated, and the experimental results were compared with calculated supersaturation curves for Si obtained from a gas phase equilibrium model of the SiCl4–H2 system. The SiNW growth rate was found to be weakly dependent on temperature but strongly dependent on the PSiCl4, exhibiting a maximum value qualitatively similar to that predicted from the equilibrium model. The results indicate that SiNW growth from SiCl4 is limited by gas phase chemistry and transport of reactant species to the growth surface under APCVD conditions. The experimental results are discussed within the context of a gas phase mass transport model that takes into account changes in equilibrium partial pressure due to curvature-related Gibbs–Thomson effects.

This work uses a method based on indentation to characterize a polydimethylsiloxane (PDMS) elastomer submerged in an organic solvent (decane, heptane, pentane, or cyclohexane). An indenter is pressed into a disk of a swollen elastomer to a fixed depth, and the force on the indenter is recorded as a function of time. By examining how the relaxation time scales with the radius of contact, one can differentiate the poroelastic behavior from the viscoelastic behavior. By matching the relaxation curve measured experimentally to that derived from the theory of poroelasticity, one can identify elastic constants and permeability. The measured elastic constants are interpreted within the Flory–Huggins theory. The measured permeability indicates that the solvent migrates in PDMS by diffusion, rather than by convection. This work confirms that indentation is a reliable and convenient method to characterize swollen elastomers.

Self-separated Pb(Zr0.52Ti0.48)O3 (PZT) films were processed by a hydrothermal deposition and a rapid thermal separation method, followed by a sol–gel filling and sintering process. The films possess excellent piezoelectric and electromechanical properties close to those of bulk material. The maximum remnant polarization is over 30 μC/cm2 and the electromechanical coupling factor (kt) reaches as high as 0.52. The unique microstructure characteristics of the PZT films, such as their highly dense structure, columnar grains, well-connected grain boundaries, and well-dispersed nanopores, could all contribute to the enhanced piezoelectric and electromechanical properties.

A novel nanoparticle self-assembly process is demonstrated. Nanoparticles were fabricated by a DC magnetron sputtering process. A silicon substrate was initially patterned with arrays of peak and valley photoresist structures using inexpensive patterning techniques. When the nanoparticles were deposited onto the prepatterned substrate, due to surface topography induced local increase in the electric field created by the charges on the nanoparticles, the nanoparticles were self-assembled onto the peaks of the structures and formed long nanowire arrays.

The hexagonal mesoporous silica MCM-41 nanospheres with Au nanorods (AuNRs) as core have been synthesized via a modified Stöber method by a process of hydration and condensation of tetraethoxysilane in a water–ethanol mixture. The AuNR@MCM-41 nanocomposites combine the photothermal characteristic with the mesopore of MCM-41 in one body. We utilized these core–shell materials for ibuprofen encapsulation and release in the simulated body fluid (pH 7.4) for the first time. The results certificated AuNR@MCM-41 nanocomposites as novel dual-functional materials could realize the light-driven release of drug due to the photothermal effect of the AuNRs. Such novel nanomaterials offer a new way for cancer treatment which combine hyperthermia with the chemotherapeutic drugs by synergistic effect.

Near-infrared quantum cutting involving the conversion of one visible photon into two near-infrared photons was demonstrated in Ca0.99−xYbxWO4: Tb0.01 phosphors. From the analysis of the refinement of x-ray diffraction patterns, the suitable concentration range of Yb3+ in Ca0.99WO4: 0.01Tb3+ was determined to be 0–20%. By investigating their luminescent spectra and decay lifetimes, second-order downconversion from Tb3+ to Yb3+ were proved and the possible quantum cutting mechanism was proposed. Quantum efficiency related to Yb3+ concentration was calculated and the maximum efficiency was reached at 140.4%. Because the energy of Yb3 + 2F7/2 → 2F5/2 transition matches well with the band gap of the crystalline Si, the Ca0.99−xYbxWO4: Tb0.01 phosphors could be potentially applied in silicon-based solar cells.