Anatase nitrogen and fluoride codoped TiO2 sol (N–F–TiO2) catalysts were fabricated by a modified sol-gel hydrothermal method, using tetrabutyl titanate as precursor. The microstructure and morphology of sol sample were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible dielectric relaxation spectroscopy (UV-VIS-DRS), x-ray photoelectron spectroscopy (XPS), etc. It was shown that N–F–TiO2 particles in sol were partly crystallized to anatase structure and dispersed in the aqueous medium homogeneously. The average particle size was ∼12.0 nm calculated from XRD patterns, and the particle size distribution was narrow. It was noteworthy that the N–F-codoped TiO2 sol particles showed strong visible-light response and high photocatalytic activity for formaldehyde degradation under irradiation by visible light (400–500 nm); we suggested that it may result from the generation of additional band of N 2p in the forbidden band and the synergetic effect of codoping nitrogen and fluorine.

Nanocrystalline LiCoO2 powders (10–50 nm) were synthesized by a citrate-nitrate combustion process followed by calcination at different temperatures (300–800 °C) in air. Thermogravimetric analyses indicated a sharp combustion at a low temperature of 225 °C, producing fine crystallites. Quantitative phase analyses from the x-ray diffractograms showed that while annealing at 500 °C produced mixed phases of cubic and rhombohedral LiCoO2, annealing at 800 °C resulted in single-phase rhombohedral LiCoO2. Electronic transitions related to the Co 3d bands were investigated by ultraviolet-visible reflectance spectra in absorbance mode and were ascribed to the Co 3d intra-band transition involving t2g and eg orbitals. The d-d transitions underwent a blue shift of about 0.3 eV as the cubic LiCoO2 transformed into the rhombohedral structure with band gap values of about 1.4 and 1.7 eV.

In this work, the shear strengths and interfacial reactions of Sn–8Zn–3Bi and Sn–8Zn–1Bi (wt%) solders with Au/Ni/Cu ball grid array (BGA) pad metallization were systematically investigated after multiple reflows. The peak reflow temperature was fixed at 230 °C. After the shear test, fracture surfaces were investigated using a scanning electron microscope equipped with an energy dispersive x-ray spectrometer. Cross-sectional studies of the interfaces were also conducted to correlate with the fracture surfaces. Two failure modes, ball cut and pad lift, were assessed for the different solders and reflow cycles. It was found that the shearing forces of both the Sn–Zn–Bi solder joints tended to increase slightly with an increase in the number of reflow cycles due to augmentation of the shearing area. A layer-type spalling of the interfacial intermetallic compounds (IMCs) was observed very early in the liquid-state reaction for the solder alloys. The active nature of the Zn confirmed an instant reaction zone at the interface to maintain the bonding between the solder and the substrate.

An in situ electrical measurement technique for the investigation of nanoindentation using a Hysitron Triboindenter is described, together with details of experiments to address some technical issues associated with the technique. Pressure-induced phase transformations in silicon during indentation are of particular interest but are not fully understood. The current in situ electrical characterization method makes use of differences in electrical properties of the phase-transformed silicon to better understand the sequence of transformations that occur during loading and unloading. Here, electric current is measured through the sample/indenter tip during indentation, with a fixed or variable voltage applied to the sample. This method allows both current monitoring during indentation and the extraction of current-voltage (I-V) characteristics at various stages of loading. The work presented here focuses on experimental issues that must be understood for a full interpretation of results from nanoindentation experiments in silicon. The tip/sample contact and subsurface electrical resistivity changes dominate the resultant current measurement. Extracting the component of contact resistance provides an extremely sensitive method for measuring the electrical properties of the material immediately below the indenter tip, with initial results from indentation in silicon showing that this is a very sensitive probe of subsurface structural and electrical changes.

Two TiO2layers formed in TiAl oxidation for 50 h at 900 °C were studied using scanning transmission electron microscopy. The main efforts were placed on the investigation of the distribution of niobium. It was found that Nb enriched in TiO2grains of mixture layer but did not exist in the outer TiO2layer. High-resolution electron microscopy (HREM) Z-contrast image revealed that Nb substitute for Ti site leading to Nb enrichment in TiO2grains of the mixture layer. The formation mechanism of the two TiO2layers and the potential effect of Nb doping in the mixture layer were also discussed.

A kind of novel poly-L-lactide (PLLA)/β-calcium metaphosphate (β-CMP) fracture-fixation composite rod was prepared by a two-step compression-molding method. The in vitro bioactivity of the composite rod was evaluated by investigating the effects of dissolved products from the composite rod on osteoblasts. In addition, the in vitro biocompatibility of the composite rod was evaluated by an osteoblast adhesion-and-proliferation assay. The products from composite rod dissolution significantly promoted cell growth. Furthermore, osteoblasts adhered and spread well on the rod. This PLLA/β-CMP composite rod has potential applications for clinical use following the assessment of adaptation during in vivo studies.

N-doped and (Al,N)-codoped ZnO films were synthesized by oxidative annealing of (Zn + Zn3N2) films, which were fabricated by reactive magnetron sputtering. Both n- and p-type conductions were obtained in these ZnO:N and ZnO:AlN films. Optimal oxidation treatments for achieving p-type ZnO are annealing at 400–600 °C for 10–60 min, depending on the film thickness and morphology. The electric properties were found to be very sensitive to the annealing conditions and film structure. As-deposited (Zn + Zn3N2) films with and without Al addition had carrier concentrations of 1021–1022 cm−3. After conversion to ZnO, the n-type films had a carrier concentrations up to 1019 cm−3, whereas the p-type ZnO:N films had hole concentrations of 1014–1016 cm−3. (Al,N)-codoping increased the hole concentration of p-type film to 1018 cm−3 despite a decrease in Hall mobility. The photoluminescence properties of the p-type ZnO films were also investigated. The synthesis of p-type ZnO:AlN by oxidative annealing is believed to provide an alternative approach to realize p-type conduction in codoped ZnO film by using N2 as the N source.

Hexagonal cerium oxide nanoflakes have been synthesized by using a surfactant-free route. Transmission electcron microscopy (TEM), x-ray diffraction (XRD), infrared spectroscopy (FTIR), thermogravimetric and differential thermal analysis (TG-DTA), Brunauer–Emmett–Teller adsorption isotherm (BET), photoluminescence (PL), and ultraviolet–visible (UV–VIS) were used to characterize the sample. The mean size of the nanoflakes is about 30 nm and the specific surface is about 70.08 m2·g−1 when annealed at 400 °C. The acidity and superfluous NH4NO3 play a key role on the formation of nanoflakes in which there exists Ce (IV) and very little Ce (III). The nanoflakes exhibit a wide PL emission peak among 350–400 nm, strong absorption ranged from 200–450 nm, and strong reflection in the visible region. As the sizes of as-prepared samples decrease, a clear blue shift in the absorbing edge is observed. The linear relationship between ΔEg and D is shown in a log–log plot. The as-prepared cerium oxide nanoflakes can be widely used as UV absorbent and polishing materials.

The ferroelectric and magnetic properties of the perovskite solid solution, (1 − x)LaCrO3–xBiCrO3, have been investigated. While pure LaCrO3 does not show ferroelectric hysteresis even at 77 K, the solid solution of La1−xBixCrO3 with x = 0.1, 0.2, 0.3, and 0.35 displays ferroelectric hysteresis, with the remanent polarization increasing with the increase of the Bi3+ content. Using a superconducting quantum interference device, the magnetization was measured versus temperature under field cooling (FC) and zero field cooling (ZFC) conditions. Magnetic hysteresis has been found in La1−xBixCrO3 (0.1 ⩽ x ⩽ 0.3) below the Néel temperature, TN. With the increase of Bi3+ content, TN decreases, while the magnetization below TN is enhanced. While the ferroelectric and magnetic properties could be due to different origins, the Bi substitution results in both ferroelectric and magnetic enhancements in the (1 − x)LaCrO3–xBiCrO3 solid solutions.

Dry aerosol synthesis applying the flame spray pyrolysis was used to manufacture and directly (in situ) deposit tin dioxide nanoparticles on sensor substrates. For the first time this technique was used to synthesize a combination of two porous layers for gas-sensor fabrication. Two different sensing layers were deposited on ceramic substrates, i.e., pure tin dioxide and palladium-doped tin dioxide. The top layer was a palladium-doped alumina as a filter. The fabricated sensors were tested with methane, CO, and ethanol. In the case of CH4, the pure tin dioxide sensor with the Pd/Al2O3 filter showed higher sensor signals and improved selectivity with respect to water vapor compared to single tin dioxide films. At temperatures up to 250 °C the Pd doping of the tin dioxide strongly increased the sensitivity to all gases. At higher temperatures the sensor signal significantly decreased for the Pd/SnO2 sensor with a Pd/Al2O3 filter, indicating high catalytic activity.

NixCo1−xO/ZrO2(CaO) directionally solidified eutectics (DSEs) form a ductile metallic interphase after they are chemically reduced at high temperatures. Vickers indentation tests have previously shown a significant change in the crack propagation behavior of the reduced composites due to plastic deformation and strain energy absorption mechanisms operating in the system after reduction. This paper focuses on structural and chemical characterization of NixCo1−xO/ZrO2(CaO) DSEs after reduction. Analytical transmission electron microscopy techniques such as energy dispersive x-ray spectroscopy (EDXS) and electron energy loss spectroscopy (EELS) show elimination of oxygen and formation of nanoscale Ni(Co) solid.

The review of corrosion performance of a number of alloy systems documents several metallic glasses with corrosion resistance superior to that of crystalline metals. In other cases, the metallic glasses do not have superior corrosion resistance. The nature of corrosion resistance of the metallic glasses is often directly related to the development of a passive film (protective layer) on the reactive alloy substrate, increased durability of the passive film, or enhanced resistance to localized corrosion where the passive film is broken or damaged. Potential mechanical/environmental degradation processes include stress-corrosion cracking, corrosion fatigue, various forms of hydrogen damage, wear, and abrasion. The availability of bulk metallic glasses in significant three-dimensional sizes will stimulate important work in these areas that will enhance the fundamental understanding of the corrosion behavior and mechanical interactions and develop design guidelines and materials properties database for designers and engineers.

The synthesis, physicochemical characterization, and catalytic evaluation of ordered mesoporous aluminophosphate oxynitride (MAPN) materials are presented here. The solid-base materials were prepared through treating aluminophosphate with an ordered mesostructure with ammonia at high temperatures. The MAPNs are well ordered, and possess high surface and pore volume. The amount of nitrogen incorporated increased with prolonged nitridation times. At the same time, the intensity of basicity is consistent with the nitrogen content, which is affirmed by Knoevenagel condensation reaction. The obtained ordered MAPN materials also possess acidity. The easy preparation and control of the nitrogen content of ordered MAPN materials, providing acidity and basicity, make them attractive as alternatives to a solid-base or acid-base catalyst, especially for the interactions of large molecules.

Cao and Huber [J. Mater. Res., 21, 1810 (2006)] proposed parameter-dependent representative strains, which have the potential to measure plastic properties from one conical indentation test. However, the potential performance of such a technique was not systematically analyzed. In this commentary, through a comprehensive numerical investigation, it is found that the two basic variables in Cao and Huber’s formulation are not completely independent, and it is difficult to obtain the two independent (sufficiently separated) representative stress–strain points needed for determining the plastic properties. Consequently, systematic errors (which could well exceed 100%) are generated for a wide range of materials, and the results are quite sensitive to small perturbations. As a complementary and critical examination of the original article, this commentary suggests that it is unreliable to use the representative strains proposed by Cao and Huber [J. Mater. Res., 21, 1810 (2006)] to measure the material plastic properties from one indentation.

Much has been learned from electrochemical properties of boron-doped diamond (BDD) thin films synthesized using microwave plasma-assisted chemical vapor deposition about the factors influencing electrochemical activity, but some characteristics are still not entirely understood, such as its electrical conductivity in relation with microscale structure. Therefore, to effectively utilize these materials, understanding both the microscopic structure and physical (electrical, in particular) properties becomes indispensable. In addition to topography using atomic force microscopy, electrostatic force microscopy (EFM) in phase mode measuring the long-range electrostatic force gradients, helps to map the electrical conductivity heterogeneity of boron-doped micro-/nanocrystalline diamond surfaces. The mapping of electrical conductivity on boron doping and bias voltage is investigated. Experimental results showed that the BDD films’ surfaces were partially rougher with contrast of conductive regions (areas much less than 1 μm2 in diameter), which were uniformly distributed. Usually, the EFM signal is a convolution of topography and electrostatic force, and the phase contrast was increased with boron doping. At the highest boron doping level, the conductive regions exhibited quasi-metallic electrical properties. Moreover, the presence of a “positive–negative–positive” phase shift along the line section indicates the presence of “insulating–conducting–insulating” phases, although qualitative. Furthermore, the electrical properties, such as capacitance and dielectric constants at operating frequency, were quantitatively evaluated through modeling the bias-dependent phase measurements using simple and approximate geometries. It was found that decreasing grain size (or increasing the boron concentration) lowers the dielectric constant, which is attributed to the change in the crystal field caused by surface bond contraction of the nanosized crystallites. These findings are complemented and validated with scanning electron microscopy, x-ray diffraction, and “visible” Raman spectroscopy revealing their morphology, structure, and carbon-bonding configuration (sp3 versus sp2), respectively. These results are significant in the development of electrochemical nano-/microelectrodes and diamond-based electronics.

A thermodynamic approach was used to describe the formation and magnetoelectric response of composite multiferroic films. Experimental and theoretical results that address the origins of different phase morphologies in epitaxial spinel-perovskite nanostructures grown on differently oriented substrates are presented. A theoretical model of magnetoelectric coupling in multiferroic nanostructures that considers a microscopic mechanism of magnetization in single-domain magnetic nanorods is described. This model explains a discontinuous electromagnetic coupling, as observed experimentally, and predicts a hysteretic behavior of magnetization under external electric fields.

Starting with a bulk metallic glass-forming alloy Mg65Cu18Ni6Y11, we prepared in situ composites by increasing the Mg content in a series of alloys, Mgx(Cu0.51Ni0.17Y0.32)100−x (65 ≤ x ≤ 90), via copper mold casting of rods 4 mm in diameter. The fully glassy alloy at x = 65 showed a compressive fracture strength of 755 MPa but no observable macroscopic plasticity prior to failure. Metallic glass-based composites were formed when the Mg content was increased. For x > 80, the glassy phase no longer existed in the as-cast rods. In the composition range of 80 ≤ x ≤ 85, needle-shaped Mg solution with a 14H-type long period stacking (LPS) structure appeared as the primary phase in the as-cast microstructure. On further increase of the Mg content up to x = 90, the solidified primary phase became 2H-Mg, coexisting with the remaining eutectic structure. The best combination of mechanical properties was obtained for the alloy at x = 81.5, which showed a fracture strength of 665 MPa and a compressive plastic strain of 11.6%. The specific strength of this alloy was 2.8 × 105 N m kg−1, much higher than conventional cast magnesium alloys. The mechanical properties are discussed in light of the phase selection and microstructural features uncovered in microscopy examinations.

The objective of this study is to investigate the corrosion susceptibility of surgical AZ91 magnesium alloys in simulated body fluids (SBFs) consisting of bovine serum albumin (BSA) and acidic SBFs (pH 5) using electrochemical methods. The addition of BSA significantly moves the open-circuit potential toward a more positive value and suppresses the corrosion reaction. The corrosion resistance under the open-circuit conditions in the SBFs with 1 g/L BSA is approximately twice that in the SBFs. A higher BSA concentration decreases the corrosion susceptibility. In addition, the acidic SBF results in a higher alloy dissolution rate. The possible mechanisms are discussed.

In this paper, we report the results of a transmission electron microscopy investigation on WC–6 wt% ZrO2nanocomposite, spark plasma sintered at 1300 °C, for varying times of up to 20 min. The primary aim of this work was to understand the evolution of microstructure during such a sintering process. The investigation revealed the presence of nanocrystalline ZrO2particles (30–50 nm) entrapped within submicron WC grains. In addition, relatively coarser ZrO2(60–100 nm) particles were observed to be either attached to WC grain boundaries or located at WC triple grain junctions. The evidence of the presence of a small amount of W2C, supposed to have been formed due to sintering reaction between WC and ZrO2, is presented here. Detailed structural investigation indicated that ZrO2in the spark plasma sintered nanocomposite adopted an orthorhombic crystal structure, and the possible reasons for o-ZrO2formation are explained. The increase in kinetics of densification due to the addition of ZrO2is believed to be caused by the enhanced diffusion kinetics in the presence of nonstoichiometric nanocrystalline ZrO2.

Dielectric response of the perovskite ceramics (1–x)La(Mg1/2Ti1/2)O3–x(Na1/2Bi1/2)TiO3 [(1–x)LMT–xNBT] (0 ⩽ x ⩽ 0.6) has been characterized at radio, microwave, and far infrared frequency ranges. Temperature variations of the dielectric permittivity and loss estimated by different methods were compared and analyzed. It was revealed that the low temperature dielectric response of the compositions with x ⩾ 0.2 is frequency-dependent over a wide range (102–109 Hz) below the resonant frequencies of the polar phonon modes. Contributions of different factors (both extrinsic and intrinsic) to the microwave dielectric loss of the ceramics were considered. The dielectric relaxation has been associated with the amount of bismuth in the system. The relaxation in LMT–NBT was considered in the context of similar effects observed in other Bi-containing, A-site disordered oxygen-octahedral compositions.