Y2SiO5 has potential applications as a high-temperature structural ceramic and environmental/thermal barrier coating. In this work, we synthesized single-phase Y2SiO5 powders utilizing a solid–liquid reaction method with LiYO2 as an additive. The reaction path of the Y2O3/SiO2/LiYO2 mixture with variation in temperatures and the role of the LiYO2 additive on preparation process were investigated in detail. The powders obtained by this method have good sinterability. Through a pressureless sintering process, almost fully dense Y2SiO5 bulk material was achieved with a very high density of 99.7% theoretical.

We have observed efficient damage recovery in large-scale molecular dynamics simulations of 30 keV Zr recoils in pure zirconia and yttria-stabilized zirconia, which is in stark contrast to radiation damage accumulation in zircon. Dynamic annealing is highly effective in zirconia during the first 5 ps of damage evolution, especially in the presence of oxygen structural vacancies. This results in near-complete recovery of damage. Damage recovery on the cation sublattice is assisted by the anion sublattice recovery, which explains the remarkable radiation tolerance of stabilized zirconia. Ceramics engineered to heal themselves in this fashion hold great promise for use in high-radiation environments or for safely encapsulating high-level radioactive waste over geological time scales.

In this paper, YNbO4:0.05Tb3+ and GdTaO4:0.05Eu3+ phosphors were chosen to study the influence of the firing temperature on the phase and morphologies using novel modified in situ chemical coprecipitation technology. Results show that until the temperature reaches 1000 °C, the formation of YNbO4 and GdTaO4 were realized; with the increasing firing temperatures, those samples present better crystalline structure and better morphologies. The luminescent properties of Eu3+ and Tb3+ have shown that after calcinations at 1000 °C, the intensity of Eu3+ and Tb3+ increases strongly with the increasing of the calcinations temperature, while remaining relatively unchanged at the temperatures ranging between 600 and 800 °C. Furthermore, other rare earth ion doped GdTaO4 and Y1−xGdxTaO4:5 mol% Eu3+ with the different yttrium content were also synthesized after calcinating at the preferable temperature using the same method. The photoluminescence of Y1−xGdxTaO4:5 mol% Eu3+ revealed that the red emission intensity of Eu3+ increases with the increasing of gadolinium content, indicating that Gd ion plays an important role in the energy transfer process. Also, the concentration quenching has been studied in the GdTaO4:Eu3+/Dy3+ systems. Moreover, the characteristic emission lines of Tb3+, Pr3+, and Er3+ in GdTaO4 were observed, showing that the energy transfer process appears between host and those activators.

Bulk metallic glasses have been formed over a fairly wide composition range (54–62 at.% Ni, 32–36 at.% Nb, and 3–11 at.% Sn) in the Ni–Nb–Sn ternary system. Partial substitution of Co for Ni and Hf for Nb improves the glass-forming ability, eventually leading to 4 mm glassy rods at the Ni56Co3Nb28Hf8Sn5 composition. The positive effects of these alloying elements have been explained based on a systematic monitoring of the amount and morphology of the competing crystalline phases as a function of the Co and Hf contents.

Amorphous Ti66Nb13Cu8Ni6.8Al6.2 alloy powders with different tungsten carbide (WC) contents were synthesized by mechanical alloying. Outstanding differences in particle size, thermal stability, glass-forming ability, and phase evolution are found for the synthesized Ti-based glassy powders with different WC contents. This is attributed to the fact that the WC was partially alloyed into the glassy matrix and the matrix element Ti was also partially alloyed into the WC particles. The obtained glassy powders exhibit a wide supercooled liquid region above 64 K. Meanwhile, the main crystalline phase is the ductile β-Ti with a high volume fraction in the crystallized alloy powders. These two aspects offer the possibility of easily preparing a plasticity-enhanced bulk composite in the supercooled liquid region by powder metallurgy, which couples the nanosized WC particles with in situ precipitated ductile β-Ti phase.

This article introduces and considers the fundamental understanding of ionic polymer–metal composites (IPMCs) functioning as electroactive actuators and sensors. IPMCs consist of ion-exchange polymers acting as base materials and metal layers functioning as electrodes. The actuation and sensing abilities of IPMCs are dependent upon the components of ion-exchange polymers (ionic groups and cations) and electrode materials. In order to improve the bending and sensing performance of the IPMCs, an integral, two-step electroplating technique and a requisite dispersion agent are used during fabrication. Electroding materials also play a key role in determining the properties of IPMCs, and numerous methods in electroding have been tried, making use of various metals, carbon nanotubes, and composites. So far, IPMCs have been adapted as robotic actuators, artificial muscles, and electrical sensors. In the future, it is expected that IPMCs will broadly spread their roles from small-sized biomedical devices to large-scale actuators for aerospace as well as many industrial applications.

The in vitro behaviors of the etched, electrochemically anodized, and hydroxyapatite (HA)-coated Ti6Al4V alloys were investigated through microstructural analysis, electrochemical measurements, and immersion tests in the Hank’s solution. A nanometer-scale, bonelike porous structure with a layer of TiO2 on top was formed during the anodization process. The surface of the coated substrate was composed of a thin TiO2 layer adjacent to the substrate, a thick monolithic HA on the outside, and a composite layer of TiO2 and HA in the middle. The anodization significantly improved the stability of the Ti6Al4V alloy in Hank’s solution due to a layer of TiO2 formed on the surface. The precoated HA further improved the stability of the Ti6Al4V alloy due to a composite layer of TiO2 and HA. The barrier layer of the composite of TiO2 and HA was suggested by the capacitive behavior of the HA-coated substrate in the electrochemical impedance spectroscopy. The electrochemical measurements implied a high tendency for the new formation of HA on the precoated HA and the anodized substrates, which was confirmed through the immersion tests. The newly formed HA on the anodized substrate was scattered over the entire surface. The newly formed HA on the HA-precoated surface mingled with the precoated HA, and gradually a new layer of HA was formed on top. These proved the favorable condition of the anodized surface as a prerequisite step for coating HA and the conductive promotion of new HA formation on the precoated surface. The new formation of HA during the immersion might suggest that artificial joints pretreated through anodization and HA coating could induce strong bonding to the bone due to the easy growth of new HA.

A series of Ti–Cx–Ny thin films with solid-solution and nanocomposite structures were deposited at 500 °C by reactive, unbalanced, direct-current magnetron sputtering. These films were subsequently vacuum annealed at 600, 700, 800, 900, and 1000 °C for 1 h. The effect of C content on the thermal stability of Ti–Cx–Ny thin films was investigated by way of studying the nanostructure and mechanical behaviors of pre- and postannealed samples using x-ray diffraction, high-resolution transmission electron microscopy, Raman spectroscopy, and microindentation measurements. The result indicated that C content played a great role in the nanostructure of Ti–Cx–Ny thin films. A small amount of C fully dissolved in the TiN lattice and produced SS Ti(N,C) thin films. Nanocomposite nanocrystalline (nc)-Ti(N,C)/amorphous-(C, CNx) thin films were followed to be formed with the incorporation of more C. On the other hand, the addition of C had a positive effect on the structural stability of Ti–Cx–Ny thin films. This effect was further enhanced after the formation of a nanocomposite structure. However, neither C content nor film structure had an effect on the thermal stability of mechanical behaviors. Both microhardness and residual stress were successively decreased with temperature and did not show any temperature retardation. The decrease in hardness values was found to be attributed to a decrease of residual compressive stress because of defect annihilation and an increase in nc size.

Based on microindentation experiments of three different metals, Guelorget et al. [J. Mater. Res. 22, 1512 (2007)] have compared the performance of five different indentation methods on extracting material plastic properties—among them, three papers were proposed by Cao and Lu [Acta Mater.52, 4023 (2004); J. Mater. Res.20, 1194 (2005); J. Mech. Phys. Solids53, 49 (2005)] and two papers were published by our group [Ogasawara et al., Scripta Mater.54, 65 (2006); Zhao et al. Acta Mater.54, 23 (2006)]. They argued that the performances of our techniques in [Ogasawara et al., Scripta Mater.54, 65 (2006); Zhao et al. Acta Mater.54, 23 (2006)] were quite poor. Here we show that Guelorget et al. [J. Mater. Res. 22, 1512 (2007)] have made quite a few mistakes and problematic steps when they handled the experiment data and performed reverse analysis. Indeed, the material plastic properties extracted from the correct procedures based on our papers [Ogasawara et al., Scripta Mater.54, 65 (2006); Zhao et al. Acta Mater.54, 23 (2006)] are much better and more stable than that reported in Guelorget et al. [J. Mater. Res. 22, 1512 (2007)]. Several general issues related to interpreting microindentation data and reverse analysis are also discussed, which may serve as important guidelines for similar studies in the future.

Ti–Si–O thin films were deposited using an aerosol chemical vapor deposition process at atmospheric pressure. The film structure and microstructure were analyzed using several techniques before and after thermal annealing. Diffraction results indicate that the films remain x-ray amorphous after annealing, whereas Fourier transform infrared spectroscopy gives evidence of a phase segregation between amorphous SiO2 and well-crystallized anatase TiO2. Crystallization of anatase TiO2 is also clearly shown in the Raman spectra. Transmission electron microscopy analysis indicates that anatase TiO2 nanograins are embedded in a SiO2 matrix in an alternated SiO2/TiO2 multilayer structure.

Subcritical cracking of thin glass films caused by stress-corrosion phenomena cannot be neglected when it comes to application and manufacturing processes that involve exposure to aqueous environments. A protocol is introduced to allow for a quantitative study of stress corrosion through channel cracking experiments. By this method, an exponential dependence of the crack propagation rate on the pH of the aqueous environment is revealed. Therefore, this behavior should be accounted for through the use of an appropriate pre-exponential factor in the expression of channel cracking rate. This factor should reflect the reduced crack resistance of the glass film caused by the weakening of the silica bonds behind the crack tip in the aqueous environment. A direct comparison between commercial slurries and reference solutions confirms that the crack resistance is a function of the pH of the ambient.

In this paper, the growth of thin and dense films of vertically aligned carbon nanotubes (CNTs) on Fe–Co/TiN/Si(100) substrates is reported. Special attention is held to the preparation of the TiN buffer layers. This layer is deposited by pulse laser deposition at high temperature with a high texturation according to [TiN(100)//Si(100)]. Further ammonia heat treatment is performed at 623 K to control a Ti:N stoichiometry and remove oxygen impurity. Fe and Co as catalysts are subsequently deposited at high temperature (923 K) at the monolayer level with two ultrahigh vacuum evaporator cells. The growth of CNTs is performed by a direct-current plasma-enhanced and hot filaments-assisted catalytic chemical vapor deposition (dc HF CCVD) process. Highly dense films of CNTs, are obtained with only 0.5 nm Fe(Co) evaporated. Observations by transmission electron microscopy show that most of the CNTs display sizes in the 2.5–6 nm range, most of them with a double-wall (DW). This is in agreement with spectral features of the Raman radial breathing modes (RBM) in the 70–130 cm−1 range. Generally, these large-diameter DWCNTs display a high defect density with morphologies partially collapsed into flattened twisted shapes.

Conjugated polymer artificial muscles fill a unique niche in the electroactive polymer portfolio. They combine high strength, low voltage, and reasonable speed with versatile fabrication and design. This article reviews the actuation mechanism in these materials and presents some of the designs that have been developed for applications such as Braille displays, catheters, and bioMEMS devices.

Palladium hydrides have important applications. However, the complex Pd–H alloy system presents a formidable challenge to developing accurate computational models. In particular, the separation of a Pd–H system to dilute (α) and concentrated (β) phases is a central phenomenon, but the capability of interatomic potentials to display this phase miscibility gap has been lacking. We have extended an existing palladium embedded-atom method potential to construct a new Pd–H embedded-atom method potential by normalizing the elemental embedding energy and electron density functions. The developed Pd–H potential reasonably well predicts the lattice constants, cohesive energies, and elastic constants for palladium, hydrogen, and PdHx phases with a variety of compositions. It ensures the correct hydrogen interstitial sites within the hydrides and predicts the phase miscibility gap. Preliminary molecular dynamics simulations using this potential show the correct phase stability, hydrogen diffusion mechanism, and mechanical response of the Pd–H system.

We have studied the lattice structure of variously oriented lead iron niobate (PFN) thin films with thicknesses of 50 < t < 500 nm that were deposited by pulsed laser deposition (PLD). We have identified that (001)-, (110)-, and (111)-oriented PFN thin films have tetragonal, orthorhombic, and rhombohedral phases at room temperature, respectively. The change in phase stability, when deposited on substrates of different orientations, is discussed with respect to the influence of epitaxial stress.