The well-ordered TiO2 nanotube arrays with controlled aspect ratio are fabricated via potentiostatic anodization. The aspect ratio of TiO2 nanotube array can be tuned conveniently by changing the water content in electrolyte and anodization time. The formation of well-ordered TiO2 nanotube array is good for the photogenerated electron transfer. So, the well-ordered TiO2 nanotube array photoelectrodes have been used to fabricate dye-sensitized solar cells (DSSCs). It is found that, with the optimum nanotube length and aspect ratio, DSSCs with TiO2 nanotube array photoelectrodes show better photoelectric conversion efficiency (2.60%) than that with TiO2 nanoparticles on Ti foil photoelectrode. It is elucidated by the interfacial electron transport of DSSCs, which are characterized quantitatively, using the electrochemical impedance spectra. The DSSC with optimal nanotube length and aspect ratio displays the fastest interfacial electron transfer and longer electron lifetime.

The fabrication of Ce3+-doped lutetium oxyorthosilicate (Lu2SiO5:Ce, LSO:Ce) scintillation ceramics was investigated by pressureless sintering starting from synthetic submicrometer polycrystalline LSO:Ce powder. It was found that translucent LSO ceramics were densified successfully with relative density of 99.5% under sintering condition of 1720 °C for 4 h. As-sintered LSO ceramics were pore-free with average grain size of 5 μm and exhibited a translucent state. The broad emission spectra centered at 419 nm of the LSO:Ce ceramics under vacuum ultraviolet (VUV) and UV excitation at room temperature. Under x-ray excitation, the overall emission intensity of obtained LSO ceramics achieved twice of that of bismuth germanium oxide (also known as bismuth germanate) single crystal at room temperature. Under excitation of 356 nm and emission of 420 nm, the luminescence decay time of the obtained LSO scintillation ceramics reached only 21.2 ns. The light yield of the LSO ceramics was 21,300 ph/MeV, which reached 91% of that of LSO single crystal.

A systematic experimental study on the exchange bias (EB) effect in a ferromagnet/antiferromagnet bilayer system is performed both in the static (dc) and dynamic (high frequency) timescale to clarify the effects of temperature and antiferromagnetic (AFM) layer thickness on the system's stability and magnetic properties. Our system consists of NiFe/IrMn. Both parallel and perpendicular domain walls are suggested to explain the static EB and coercivity behaviors. In the microwave region, peaks, which can only be suppressed at high temperatures with strong external fields, were observed in the AFM thickness dependencies of the dynamic effective field and resonance frequency. The temperature dependence of both static and dynamic parameters suggests different values of Néel temperatures. The dynamic results show a rotatable anisotropy contribution, which has a peak value at the blocking temperature and vanishes at the dynamic Néel temperature.

The aim of this study is to assess the time-dependent mechanical properties of rat femoral cortical bone in a lifespan model from growth to senescence. New nanoindentation protocol was performed to assess the time-dependent mechanical behavior. The experimental data were fitted with an elastic–viscoelastic–plastic–viscoplastic mechanical model allowing the calculus of the mechanical properties. Variation of mechanical response of bone as a function of the strain rate and age were highlighted. The most representative variations of the mechanical properties with age were found to be statistically significant (P < 0.001) from 1 to 4 months for elastic properties, from 1 to 9 months for viscoelastic properties and during all lifespan for plastic and viscoplastic properties, highlighting different maturation ages for elastic, viscoelastic, plastic and viscoplastic behaviors. These results suggest that different physical–chemical and structural processes occur at different ages reflecting bone modeling and remodeling activities in the rat's whole lifespan.

A low-temperature thin-film processing method for BaTiO3 is studied to understand microstructure development in the presence of a liquid-forming phase. The addition of a eutectic barium borate flux is found to prevent nucleation of BaTiO3 during pulsed-laser deposition on sapphire substrates at 400 °C. Subsequent thermal annealing above the flux's eutectic temperature dramatically enhances the film's microstructural development and crystallinity. A secondary reaction phase of barium aluminate is identified at the substrate interface in both unfluxed and fluxed films, although it is more pronounced in the fluxed films. This barium aluminate phase in conjunction with the liquid flux serves to nucleate {111} twins in the barium titanate, which subsequently lead to enhanced grain growth. The resulting large-grained and dense thin films result in markedly improved dielectric properties.

Additive manufacturing has provided a pathway for inexpensive and flexible manufacturing of specialized components and one-off parts. At the nanoscale, such techniques are less ubiquitous. Manufacturing at the nanoscale is dominated by lithography tools that are too expensive for small- and medium-sized enterprises (SMEs) to invest in. Additive nanomanufacturing (ANM) empowers smaller facilities to design, create, and manufacture on their own while providing a wider material selection and flexible design. This is especially important as nanomanufacturing thus far is largely constrained to 2-dimensional patterning techniques and being able to manufacture in 3-dimensions could open up new concepts. In this review, we outline the state-of-the-art within ANM technologies such as electrohydrodynamic jet printing, dip-pen lithography, direct laser writing, and several single particle placement methods such as optical tweezers and electrokinetic nanomanipulation. The ANM technologies are compared in terms of deposition speed, resolution, and material selection and finally the future prospects of ANM are discussed. This review is up-to-date until April 2014.

In this review, we discuss the recent developments of high-performance and improved-stability of indium-oxide-based transparent amorphous-oxide semiconductor (TAOS) thin-film transistors (TFTs) properties. TAOSs are widely explored with the aim of producing high-performance semiconductors suitable for the channel layer of TFTs which enable to survive under light and thermal-bias-induced stress conditions. Numerous TAOSs have been invented with some improved performance characteristics of TFTs such as mobility, light and thermal induced bias stress. However, there has been no clear elucidation of the mechanisms driving these improvements. In this review, we discuss the progression of innovations of high performance indium-oxide-based TAOS TFTs from its first reported amorphous indium gallium zinc oxide (a-IGZO) to present, and their properties that are correlated with the Lewis acid strength (L) and bonding strength of dopant and oxygen as a carrier suppressor and strong binder. The proposed mechanism can be practical to develop novel TAOS TFTs with high mobility and stability.

Methods for the solution deposition of organic semiconductors (OSCs) show great potential for the production of large-area, inexpensive, and flexible organic electronics. A solution deposition method called solution shearing has consistently been shown to yield thin film transistors with improved performance over those created via other solution-based approaches. However, the need for discrete, electronically isolated devices requires the parallel development of a facile means of pattern definition compatible with the solution shearing process. In our work, we use a simple chemical prepatterning method to enable the solution shearing deposition of the small molecule OSC TIPS-pentacene on substrates with feature sizes as small as 100 µm. Grazing incidence x-ray diffraction (GIXD) was also used to confirm the existence of high performance TIPS-pentacene polymorphs in the patterned thin films. Mobilities as high as 1.13 cm2 V−1 s−1 were obtained on 400 µm wide patterns by depositing a high-performance, metastable polymorph of TIPS-pentacene.

For a better understanding of the local fracture behavior of semi-brittle materials, we carried out bending experiments on notched microcantilevers of varying sizes in the micrometer range using NiAl single crystals. Smaller and larger beams were milled with a focused ion beam in the so-called “soft” <110> and “hard” <100> orientation and were tested in situ in a scanning electron microscope and ex situ with a nanoindenter, respectively. The measurements were evaluated using both linear-elastic fracture mechanics and elastic–plastic fracture mechanics. The results show that (i) the fracture toughness is in the same range as the macroscopically determined one which is around 3.5 MPa$\sqrt {\rm{m}}$ for the soft orientation and around 8.5 MPa$\sqrt {\rm{m}}$ for the hard orientation, that (ii) there is a strong influence of the anisotropic behavior of NiAl on the fracture toughness values, and that (iii) the J-integral technique is the most accurate quantification method.

Transparent 0.67(Pb1−xLax)(Mg1/3Nb2/3)O3–0.33(Pb1−xLax)TiO3 (x = 0–0.05) ceramics were successfully prepared without using a hot-pressing technique. The optical transmittance at the wave length of 400–2000 nm increased with increasing lanthanum (La) content, x from 0 to 0.03. The transmittance at 600–2000 nm further increased (with the highest transmittance of 68% at 2000 nm for ceramics with thickness of 0.5 mm) at x = 0.04 and 0.05, while the transmittance at 400–600 nm decreased. X-ray diffraction patterns suggested that the overall increase in the transmittance with x was associated with a change in the crystal systems from a monoclinic phase to a pseudocubic phase, and the decrease at x = 0.04 and 0.05 was related to the formation of an impurity second phase. Their microstructures and dielectric properties were also studied.

Zr-based bulk metallic glasses are promising engineering materials due to their good glass-forming abilities and unique combination of good strength (∼1.9 GPa) and medium stiffness. In this study, the corrosion behaviors of Zr–Co–Al–Ag BMGs, with silver content from 0 to 11 at.%, in NaCl and H2SO4 solutions were investigated. The corrosion resistance increased when the silver content increased. The oxidation behaviors of Zr–Co–Al–Ag BMGs were also studied. The oxidation kinetics of all the samples obeyed a two-stage parabolic rate law, which consisted of an initial transient oxidation followed by a steady-state oxidation stage. The addition of Ag was found to reduce the oxidation resistance of Zr–Co–Al–Ag BMGs. Some white nodules, possibly cobalt oxide, were observed when the Zr–Co–Al–Ag BMG with 8 at.% Ag was oxidized at high temperature.

The present work investigates inorganic–organic nanocomposite polymer electrolytes (NCPEs) for lithium-ion battery applications. Nanoscale TiO2 particles were dispersed into boron comprising poly(vinyl alcohol) (PVA)-g-poly(ethylene glycol) methyl ether (PEGME) host polymer at several percentages. During preparation, nanocomposite matrices were doped with CF3SO3Li at several compositions and homogeneous soft solid materials were obtained. The interactions between host copolymer and inorganic additive and dopant were studied by Fourier transform infrared spectroscopy. The surface morphology of the NCPEs was investigated by scanning electron microscopy and their thermal properties were studied by thermogravimetric analysis and differential scanning calorimetry. The ionic conductivity of these novel NCPEs was studied by dielectric-impedance spectroscopy. High ambient temperature Li+ ion conducting (∼10−4 S/cm) NCPE matrices can be suggested for lithium battery applications.

Ag–TiO2 hybrids are useful in various applications, such as photocatalysis, solar energy conversion, and biosensoring. In this study, oil-decorated TiO2 films were used to induce the formation of Ag nanoplates in AgNO3 solution via a photocatalytic method. Ag nanoplates in the products can be controlled by changing the oil-decoration time of films or changing the AgNO3 concentration of the solution. Oil decoration was found to be necessary in the formation of Ag nanoplates, and a critical concentration of AgNO3 solution was needed. The oil layer on the TiO2 films was demonstrated to play a role in the prevention of the reoxidation of the Ag atoms, and a growth model was proposed to interpret the formation of Ag nanoplates on the oil-decorated TiO2 films.

Extension of microelectromechanical systems (MEMS) into more extreme operating conditions will require a wider range of material properties than are currently available in conventional systems. Successful integration of new materials is dependent on concurrent development of compatible fabrication routes and scale appropriate evaluation techniques. This review focuses on emerging material classes that have potential to replace silicon-based MEMS in elevated temperature applications. Basic silicon mechanical properties and micromachining methods are reviewed to provide context for developing material systems such as silicon carbide, silicon carbonitrides, and several nickel-based alloys. Potential improvements in strength, thermal stability, and reliability are juxtaposed with fabrication, reproducibility, and economic feasibility issues that must also be addressed.

Hematite has been considered as one of the most promising materials for solar water splitting, although its photoelectrochemical performance is still not very high and limited by its intrinsic properties. In the past few years, sizable advances in the development of hematite photoelectrodes for enhanced water splitting activities have been achieved by a variety of rational modification strategies, including nanostructure design for efficient charge collection, metal ion doping for promoted charge carrier transfer, heterojunctions for efficient charge separation, and surface and/or interface modification for retarded charge recombination and enhanced light absorption. In this article, research work and milestone achievement actually focused on hematite photoelectrodes for water splitting is reviewed in detail. A review on this topic by answering the key question, “how to modify or design hematite photoelectrode to improve its conductivity, enhance charge separation as well as catalyze surface water oxidation,” in authors' view, can be potentially helpful to enable hematite for further efficient solar energy conversion, which will be very inspiring and important to this field.

The nature of morphological instabilities in sputtered titanium and niobium nitride thin films grown on amorphous borosilicate glass and single-crystal Si (311) substrates is investigated. All the films were grown by RF magnetron sputtering at constant power and pressure but with thickness varying from 40 to 400 nm and substrate temperatures of 250–300 °C. The surfaces of the thin films can be divided into two areas: one in which the morphology is smooth with densely packed grains and the other in which there are morphological instabilities. A closer observation of the morphological instabilities reveals the coexistence of elastic strain-induced Asaro–Tiller–Grinfeld (ATG) type of instability and dendritic and snowflake structures due to diffusion-limited aggregation (DLA). The ATG instabilities extend over lengths of several tens of micrometers, whereas the DLA structures are confined to lengths of less than 10 μm in the same film. At low thickness (40–100 nm) only the elastic strain-induced instabilities emerge. High growth rates and a thickness of 150 nm are required to cause DLA and coexistence of the two kinds of instabilities. It has also been found that crystallization is not a prerequisite for the formation of dendritic structures.

The effects of surface modifications of multiwalled carbon nanotubes (MWCNTs) on their dispersibility in different solvents and poly(ether ether ketone) (PEEK) have been studied. MWCNTs were treated by mixed acids to obtain acid-functionalized MWCNTs. The acid-functionalized MWCNTs were modified with five different chemical agents separately, 1,6-diaminohexane, hexadecyltrimethyl ammonium bromide, silane coupling agent 3-aminopropyltriethoxysilane, anhydrous sulfanilic acid, and ethanolamine. Multiwalled carbon nanotube and PEEK (MWCNT/PEEK) composite films were fabricated to explore systematically the dispersibility of differently modified MWCNTs in PEEK as well as in different solvents. The morphology and structures of MWCNTs and the compatibility between MWCNTs and PEEK have been investigated. It was observed that the MWCNTs modified with anhydrous sulfanilic acid have an excellent dispersion in the PEEK grafted by sulfonic acid groups and that the MWCNTs modified with ethanolamine are also dispersed well in pure PEEK. The results herein provide useful insights into the development of MWCNT/PEEK composites for a wide variety of applications.

Comprehensive intermetallic compound phase analysis at wire bond interfaces was performed for a side-by-side comparative study between 18 µm Pd-only coated Cu wire and 18 µm Pd-coated Cu wire followed by Au flash coating. Scanning electron microscopy and transmission electron microscopy results combined with nanobeam electron diffraction and structure factor calculation identified the formation of metastable θ′-CuAl2 and Cu9Al4 in both of the wire bonds before and after high temperature storage test. In particular, nanobeam electron diffraction and structure factor calculation unambiguously revealed that the two intermetallic compound phases grow in size after high storage temperature test in a manner that they maintain their epitaxial relationships that minimize lattice mismatch at the Cu/Al wire bond interface. Nanobeam electron diffraction and energy dispersive x-ray spectroscopy results found no significant Au flash coating effects in terms of intermetallic compound morphology, phase, and thermal evolution.

Two phases of nickel sulfide (α-NiS and β-NiS) nanoarchitectures were successfully and controllably synthesized by a facile solvothermal method with two different solvents of alcohol and water, respectively. The products were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV-vis diffuse reflectance spectrophotometer. The sphere-like shape for α-NiS and cross-like shape composed of nanorods for β-NiS are uniform and well distributed as well as their size. Both α-NiS and β-NiS powders were used as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). It is found that the DSSC with an α-NiS CE performs much better than the one with a β-NiS CE. The energy conversion efficiency of the former was 5.2%, whereas the latter was 4.2%, about 20% increment.

Titanium dioxide (TiO2), a widely used inorganic semiconductor owing to its superb photoelectric properties, has frequently been fabricated into composites to reduce its relatively large band gap and overcome its limited visible light absorption. In this article, a “layer-by-layer” method has been developed to prepare the composite structure of nitrogen (N)-doped graphene quantum dots (GQDs)-sensitized TiO2 nanofibers. The as-prepared structure shows considerable luminescence and exhibits excellent photoelectric properties. Various factors including the crystalline phase of TiO2, amount of N in GQDs, and irradiation wavelength were investigated to find the optimal conditions for enhanced photoelectric activity. It is demonstrated that the combination of highest N amount GQDs with TiO2 nanofibers of mixed phases (750 °C-sintered TiO2 nanofibers) possess the best photoelectric properties. The enhancement of properties using TiO2 nanofibers with mixed phases mainly contributes to the transfer of electrons between conduction bands of different phases in TiO2 and the distinctive photoluminescence (PL) property of N-GQDs. Furthermore, this enhancement can be achieved in most areas of the visible light range. The general mechanism of the electron generation and transfer of the structure is based on the normal PL and upconversion PL property of N-GQDs which serve as the sensitizer. We consider it a feasible method to improve the photoelectric conversion efficiency in photovoltaic devices.