Low temperature solid oxide fuel cells (SOFCs) are a promising solution to revolutionize stationary, transportation, and personal power energy conversion efficiency. Through investigation of fundamental conduction mechanisms, we have developed the highest conductivity solid electrolyte, stabilized bismuth oxide (Dy0.08W0.04Bi0.88O0.36). To overcome its inherent thermodynamic instability in the anode environment, we invented a functionally graded bismuth oxide/ceria bilayered electrolyte. For compatibility with this bilayared electrolyte, we developed high performance bismuth ruthenate–bismuth oxide composite cathodes. Finally, these components were integrated into an anode-supported cell with an anode functional layer, resulting in an exceptionally high power density of ∼2 W/cm2 at moderate temperatures (650 °C) and sufficient power down to 300–400 °C for most applications. Moreover, because SOFCs can operate on conventional fuels, these low temperature SOFCs provide one of the most efficient energy conversion technologies available without relying on a hydrogen infrastructure.

In this paper, ink-jet printing was used to deposit poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester blend as active layer and a comparison study of three printing methods [multiarray (MA), single layer array, and multilayer array] was performed. For organic photovoltaics (OPVs) fabricated using MA or multilayer arrays, the efficiency was less than 1% independent of printing parameters. When single layer print pattern was used, the device performance improved significantly and an efficiency of 1.29% was obtained, indicating that the thin films fabricated using a single layer are more suitable for OPVs than films obtained by overlapping of multiple layers. The influence of annealing parameters on electrical and optical thin film properties was also investigated. The study found that the optimum annealing condition for the printed OPVs is solvent annealing at 60 °C, yielding an efficiency of 1.99%.

In this article, the sol-gel methodology was used for coating an acrylonitrile butadiene styrene (ABS) polymer prepared by the rapid prototyping technology with a colloid containing the europium III dipicolinic complex, which presents high emission when excited in the ultraviolet region. Either acid or base was used for treatment of the ABS polymer, with a view to activating its surface. The thermal analysis evidenced a residual mass after 600 °C, which indicated that the coating adhered to the substrate. X-ray diffraction analysis showed that the structure of the ABS polymer was not affected by the sol-gel treatment. The large band centered at 287 nm, ascribed to ligand-metal charge transfer, can be used to excite the europium III dipicolinic complex in the ultraviolet C and ultraviolet B regions. The emission appears in the characteristic red region of the electromagnetic spectrum. These results indicate that the obtained material is a candidate for use as ultraviolet sensor.

The good quality single crystal ZnWO4:Yb3+ was grown by Czochralski method and the spectra were measured. The fluorescence lifetime at 1017 nm was measured to be 644 μs and the radiative lifetime was 209 μs. The laser parameters, βminIsat as well as Imin have been calculated to be 4.6%, 14.4 Kw/cm2, 0.66 Kw/cm2, respectively. The Stark-level components of the 2F7/2 and 2F5/2 were also determined. End-pumping crystal ZnWO4:Yb3+ with 975 nm laser diode, we investigated the laser output property. The highest output power at wavelength 1017 nm was obtained to be 0.5 W, corresponding to the pumping power of 10 W and the threshold was about 2 W.

PACS: 71.20.Eh; 78.20.-e; 65.60. +a, 42.55.Xi, 42.55.Ye, 42.60.Gd.

Synthesis of well-defined sodium yttrium fluoride (NaYF4) nanocrystals has been achieved in nonpolar solvents, but these nanocrystals possess a hydrophobic surface and need to be surface-modified for various biological applications. Development of facile aqueous solution method to synthesize one-dimensional NaYF4 with a hydrophilic surface still remains challenging. Herein, we demonstrate a simple route to prepare hydrophilic NaYF4 nanorods by using hydrophobic NaYF4 nanospheres as precursor. It is interesting to find that hydrothermal treatment of oleic acid-capped NaYF4 nanocrystals can not only induce anisotropic growth of these nanocrystals but also change their surface properties. The hydrophilic NaYF4 nanorods synthesized in this work has been well characterized and possible formation mechanism has also been discussed.

Yb3+:Sr3Y2(BO3)4 crystals have been grown successfully by Czochralski method. The compound crystallizes in orthorhombic system, space group Pnma, with a = 7.4062(3) Å, b = 16.0030(7) Å, c = 8.7130(4) Å, α = β = γ = 90°, and Z = 4. Yb3+:Sr3Y2(BO3)4 has three cationic sites and two kinds of boron sites. The crystalline quality of the Yb3+:Sr3Y2(BO3)4 single crystal was verified by the width of the x-ray diffraction peak in the x-ray rocking curves measurement. The absorption spectrum, emission spectrum, and fluorescence lifetime of the Yb3+:Sr3Y2(BO3)4 crystal were detected at room temperature. The laser performance parameters βmin, Ipsat, and Imin were calculated.

We report on the absorption, static, and transient luminescence spectra of Sm3+-doped glasses. The dependences between absorption and emission cross sections as well as between luminescence quantum efficiencies and Sm3+ doping concentration are examined. The large stimulated absorption cross section and emission cross section combined with the long fluorescent lifetime make phosphate glasses doped with Sm3+ promising material for visible fiber lasers. Moreover, ΔT(Tx − Tg) of these glasses is about 290 °C, which guarantees their thermal stability against crystallization during the fiber drawing process.

We propose a new method of synthesis of crystalline yttrium and lutetium orthoborates in thin (2.5–20.0 μm thick) layers of molten borate oxide glasses. The method is based on interaction of nanosized lutetium and yttrium oxide powders with boron anhydride in the melt. X-ray diffractometry and electron microscopy investigations have revealed that in the case of lead-content glasses, the method shows a very strong orienting effect in the texture of the resulting orthoborate particles. This highly oriented texture results in good transparency of the obtained glass–ceramic films. Studies of the luminescence and scintillation spectra of the glass–ceramic composites show that they can be used as highly effective phosphors with a light yield comparable to that of single crystalline scintillators.

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.

Large quasicrystals up to ∼10 μm in size with a volume fraction of ∼30% have been identified in a nitrogen gas-atomized marginal glass-forming alloy Al85Ni5Y6Co2Fe2 by detailed transmission electron microscopy. The formation of the large quasicrystal (Q) phase is discussed through the configuration of the valence electrons of its constituent elements, and the thermodynamic and kinetic factors associated with the solidification of this marginal glass-forming alloy during gas atomization. The finding leads to an important inference that marginal glass-forming alloys could be ideal systems for the formation of bulk quasicrystals under appropriate kinetic conditions. The Q phase is stable up to ∼500 °C and decomposes thereafter. The activation energy for the decomposition of the Q phase is similar to the self-diffusion of Al. Two new intermetallic phases associated with the formation and decomposition of the Q phase have also been identified and characterized.

The mechanical properties of submicron scale columnar zinc structures, with average diameters between 130 and 1060 nm, were characterized by uniaxial microcompression tests. The zinc pillars were fabricated by electron beam lithography and electroplating and were found to be generally single crystalline, with a preferred out-of-plane orientation close to the [0001] directions. Post deformation microstructural analysis suggests that the zinc pillars maintain their single-crystalline structure, but without twin boundary formation. Interestingly, the engineering flow stress results indicate that small-scale zinc structures are insensitive to both strain rate and size.

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.

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.

A method is presented for the identification of plastic material properties, i.e., yield strength and work hardening rate, using the residual imprint geometry formed by a spheroconical indentation. A corresponding finite element simulation with the same tip geometry and maximum as applied in the indentation experiment yields a numerical imprint profile. Then, the imprint profiles resulting from simulation and experiment are compared, and the material parameters of the simulation are varied by an optimization procedure until a satisfying agreement between simulation and experiment is established. At this stage, the material parameters used for the simulation represent the true material properties. It is shown that this procedure yields unique results that are furthermore verified by independent uniaxial straining experiments. Finally, the reliability of this method with special emphasis on its sensitivity with respect to measurement errors of the imprint geometry is demonstrated. Hence, it is concluded that the residual imprint can be regarded as the fingerprint of a material that contains sufficient information on plastic material behavior to uniquely extract values for yield strength and work hardening rate.