Transparent mesoporous silica films were prepared by sol-gel spin coating on silicon wafers at room temperature. An erbium complex, erbium tris 8-hydroxyquinoline (ErQ), was homogeneously impregnated into the pores of the mesoporous silica films, and its concentration was easily controlled by using a solution immersing technique. The ErQ-impregnated mesoporous silica films show a room-temperature photoluminescence at 1.5 µm.

High-quality Hg1−xCdxTe epilayers on CdTe buffer layers were grown by molecular beam epitaxy using various growth methods. The reflection high-energy electron diffraction, scanning electron microscopy, and atomic force microscopy measurements showed that the crystallinity and electrical properties of the Hg1−xCdxTe epilayers grown on CdTe buffer layers deposited by using a two-step annealing growth method were improved. These results indicate that high-quality Hg1−xCdxTe films can be obtained by using CdTe buffer layers grown by the two-step annealing growth method and that the grown Hg1−xCdxTe epilayers hold promise for potential applications in optoelectronic devices in the area of infrared detectors.

CeO2 films are technologically important as buffer layers for the integration of superconducting YBa2Cu3O7−δ films on {100}-biaxially textured Ni substrates, yielding a Ni–CeO2–YBa2Cu3O7−δ layer sequence. The Ni–CeO2 interface is a metal–oxide interface, and the misfit between substrate and film is about 9%. An epitaxial growth model was suggested for this system in the literature. The investigated films were deposited by a reactive thermal evaporation process at substrate temperatures of 650–670 °C with a thickness of 100 nm after deposition. The CeO2 films were characterized by plan-view and cross-section transmission electron microscopy, atomic force microscopy, and scanning electron microscopy. The CeO2 films had a strong {100} biaxial texture with a roughness of approximately 90 nm. No intermediate layer could be found by cross-section transmission electron microscopy at the Ni–CeO2 interface. The films had columnar grains with diameters of 20–50 nm, much smaller than the grain size of the Ni substrate, which was larger than 1 μm. Small-angle grain boundaries and small amounts of 〈111〉-oriented grains were evidenced in plan-view samples by diffraction patterns. The Moiré fringes technique was applied and was ideally suited to image the small rotations (≤3°) of the small CeO2 grains with respect to the Ni substrate. These small rotations of small grains showed that the growth was nonepitaxial, however, biaxially textured. In the CeO2 film samples, nanovoids 5–10 nm in size were observed and were mostly located close to the film surface. A model for the growth of CeO2 thin films on nickel substrates can be proposed on the basis of our results.

The synthesis of BaSn(OH)6 acicular crystals by precipitation at 100 °C from aqueous solutions and their transformation in the perovskitelike compound BaSnO3 was investigated. Single acicular crystals 100–200 μm in length were obtained from a 0.05M solution, whereas bundlelike aggregates of 20–40 μm were precipitated from 0.2–0.6 M solutions. The x-ray diffraction pattern of barium hexahydroxostannate was indexed according to monoclinic symmetry with cell parameters a = 11.029 ± 0.002 Å, b = 6.340 ± 0.001 Å, c = 10.563 ± 0.001 Å = 128.51 ± 0.01°, α = γ = 90°. The BaSn(OH)6 particles decomposed to BaSnO3 and water at approximately 270 °C and the original morphology was retained. The resulting product had specific surface area up to 30–40 m2/g and consisted of 10–20 nm crystallites. The larger unit cell edge in comparison to the reference value and the continuous weight loss up to 1200 °C indicate that water is not completely released during decomposition and a substantial amount of proton defects (up to 0.4 mol per mole of BaSnO3) is incorporated in the perovskite lattice as OH− groups. Normal crystallographic properties of BaSnO3 are restored only after calcination at 1300 °C.

The study presents evidence of the microstructural evolution during cyclic indentation of monocrystalline silicon with a spherical indenter. Transmission electron microscopy examination of microindentation on cross-section view samples showed that the structure change in the transformation zone features a decomposition of the amorphous phase to R8/BC8 crystals. Outside the zone, cyclic loading gives rise to bending of pristine silicon, slip penetration, and radial cracking. The development of the load–displacement curves during consecutive indentations is justified in terms of the phase transformation events observed.

Crystalline CuO and Cu2O nanowires with an average diameter of about 10 nm and lengths of several tens of microns were successfully synthesized, depending on synthesis conditions, using precursor Cu(OH)2 nanowires as templates. The crystallinity, purity, morphology, and structural features of the as-prepared nanowires were characterized by powder x-ray diffraction, selected-area electron diffraction, and high-resolution transmission electron microscopy. The results showed that the precursor polycrystalline Cu(OH)2 nanowires served as both reactants for the growth of CuO and Cu2O nanowires, and as templates controlling the size and shape of the resulting nanowires.

A series of novel liquid-crystalline polymer (LCP) systems, including a heterocyclic 2,5-thiophene unit, were synthesized and studied using a modified thin-film polymerization method as part of a continuing investigation of molecular structural effects on liquid crystallinity. The monomers used in the reaction included p-acetoxybenzoic acid (ABA)/2,6-acetoxynaphtholic acid (ANA), 4,4′-biphenol (BP)/4,4′-diacetoxybiphenyl (DABP)/p-acetoxyacetanilide (AAA), and 2,5-thiophenedicarboxylic acid (TDA). Polarizing light microscopy and Fourier transform infrared spectra were used to study, in situ record the evolution of morphological change in the thin-film polymerization process, and confirm the occurrence of polymerization. Experimental results indicated that monomer structure and composition as well as temperature influence the formation of the liquid crystalline (LC) phase greatly and revealed that 2,5-thiophene structure is a viable mesogenic core unit. It is more effective than isophthalic acid (IA) in assisting in the LC formation as polymers containing TDA have a better developed LC phase and lower critical ABA content than those with IA. Stripe texture was observed in the ANA/DABP/TDA system, possibly due to the structural characteristics and matching of the monomers. The decrease of isotropic round areas in the LC phase and the annihilation between two pairs of defects with reaction time were also studied.

Ultralow dielectric constant values were measured on Ni–Zn ferrites prepared using Fe2O3 as a starting material and sintered in a microwave field. Significant differences in microstructure, magnetic, and dielectric properties were observed between microwave-sintered Ni–Zn ferrites prepared using Fe3O4 (T34) and those starting with Fe2O3 (T23) ingredients. Higher magnetization values observed in T23 ferrite are attributed to large grain size, possibly containing abundant domain walls and the presence of fewer Fe2+ ions. The ultralow dielectric constant values observed on T23 ferrites show that this procedure is highly suitable to prepare Ni–Zn ferrites for high-frequency switching applications.

Electron microscopy observations of α–ZrP whiskers with the NaCl structure, grown by chemical vapor deposition at 1300 °C, showed that there exists a hexagonal structure region (a = 0.369 nm and c = 1.248 nm) near the surface of the whiskers. High-resolution lattice image observations revealed that the method of stacking the eight-layered hexagonal structure is different from the reported hexagonal β–ZrP. In addition to the eight-layered structure, 12-layered and 16-layered structures were also observed, indicating a variety of ZrP polymorphisms.

Gaseous bubble inclusions in bismuth germanate (BGO) and bismuth germanium silicon oxide (BGSO) crystals were studied by means of Raman spectroscopy at room temperature. Their Raman spectra in the range from 60 to 70 cm−1 showed three peaks for the rotational Raman modes of O2 and N2. Vibrational Raman modes of O2 and N2 were also recorded for BGO and BGSO crystals. It was found that all the rotational and vibrational modes were blue shifted from those of free molecules due to the hydrostatic pressure in the bubbles. Internal pressure in the bubbles was estimated from the rotational and vibrational Raman mode frequencies. O2 gas pressure in the bubble was estimated as 140 GPa, and N2 gas pressure, as 31 GPa. The pressure coefficient of the vibrational mode frequency of O2 (0.368 cm−1/GPa for O2 vibrational mode of 1580 cm−1) and N2 (0.322 cm−1/GPa for N2 vibrational mode of 2331 cm−1) was also obtained from the blue shift and the calculated bubble pressure.

Conventional methods of analysis for depth-sensing indentation test data use the slope of the elastic unloading portion of the load–displacement response in conjunction with the elastic equations of contact for a rigid cone. It is common practice to incorporate the combined modulus of the indenter and specimen in these equations although the validity of this practice never appears to have been verified. This work demonstrates the validity of using the combined elastic modulus in depth-sensing indentation testing in conjunction with the elastic equations of contact for a conical indenter.

Matrix-mediated in situ synthesis of monodispersed magnetite and maghemite nanoparticles (2–16 nm) was carried out using the cavities present in gels of globular proteins such as egg white and bovine serum albumin. Under stringent conditions, spatial-charge-distribution-assisted molecular recognition of proteins for inorganic ions led to the site- and polymorph-specific synthesis of superparamagnetic iron oxide particles. A transformation from magnetite to maghemite as a nucleating phase could be observed by partially denaturing the egg white protein, signifying the delicate role of quaternary structure of proteins under different reaction conditions, in determining the size and shape of the polymorph.

A LiNbO3/ZnO multilayer with a preferred c-axis orientation normal to the plane of the substrate was grown on glass and SiO2/Si substrates by laser ablation. The piezoelectric activity in as-deposited films was demonstrated using a novel approach to the atomic force microscope. In the presence of an in-plane, low-frequency (0.1–5 Hz) alternating current electric field, we monitored and imaged the induced piezoelectric response normal to the film plane between two electrodes.

Silicon nitride (Si3N4) whiskers were synthesized via a carbothermal reduction and nitridation process from silica-containing natural substances, such as volcanic ash, diatomaceous earth, white sand, and rice hull, using the flux effect of cryolite. It was clarified that the volcanic ash, whose Fe2O3 content contributed to the formation ratio of the α-type, was suitable as a raw material for the synthesis of Si3N4 whiskers. Fe2O3, Al2O3, and TiO2 contributed to the growth in the whisker-axis direction by the formation of droplets inducing the vapor-liquid-solid mechanism. CaO and MgO led to an increase in the diameter of the whiskers by vapor-solid and vapor-liquid-solid mechanisms, and the Fe2O3 content was the highest in the volcanic ash, whose Fe2O3 content was the highest among the natural substances.

Despite their interesting properties, nanostructured materials have found limited use as a result of the cost of preparation and the difficulty in scaling up. Herein, the authors report a technique, friction stir processing (FSP), to refine grain sizes to a nanoscale. Nanocrystalline 7075 Al with an average grain size of 100 nm was successfully obtained using FSP. It may be possible to further control the microstructure of the processed material by changing the processing parameters and the cooling rate. In principle, by applying multiple overlapping passes, it should be possible to produce any desired size thin sheet to nanostructure using this technique. We expect that the FSP technique may pave the way to large-scale structural applications of nanostructured metals and alloys.

Transmission electron microscopy, x-ray diffraction, relative permittivity as a function of temperature, and polarization versus field loops were used to study the antiferroelectric/ferroelectric (AFE/FE) phase boundary in Pb1–1.5xLaxZr0.9Ti0.1O3 (PLZT, 100x/90/10) ceramics. X-ray diffraction and electrical measurements indicated a FE rhombohedral (R) to AFE tetragonal (T) phase transition between PLZT 2/90/10 and 4/90/10. Both phases exhibited superstructure reflections in electron-diffraction patterns at ½{hkl} positions consistent with rotations of the octahedra in antiphase. Previously, neutron diffraction suggested that the FER has an a−a−a− tilt system (Glazer notation), in agreement with its macroscopic symmetry. By analogy, it is proposed that the AFET phase has an a0a0c− tilt system. The AFE phase was also characterized by incommensurate superstructure along pseudocubic 〈110〉p directions, whereas the FE phase had extra commensurate superlattice reflections at 1/2{hk0}p positions. 1/2{hk0}p reflections are forbidden in both tilt systems, but their presence is explained by Pb ion displacements averaged along 〈111〉 but with short coherence antiparallel components along 〈110〉 directions. The antiparallel Pb displacements are coupled to an a−b−b− (a ≈ b) monoclinic tilt system in the vicinity of the AFE/FE boundary.

This work reports on the processes involved in the wear of hydroxyapatite sliding against slip-cast, glass-infiltrated alumina. Synthetic hydroxyapatite was used as a model material representing tooth enamel, while the alumina used was designed for tooth restorations. The wear tests were conducted in distilled water using a pin-on-disk tribometer under contact conditions that mimic the oral environment. To investigate the wear process for this material system, the surfaces of the hydroxyapatite “pin” and the alumina “disk” were examined by scanning electron microscopy and atomic force microscopy. Transmission electron microscopy was used to examine wear debris fragments collected from the hydroxyapatite wear scar and, for comparison, the bulk structure of the pin and crushed fragments from an unworn pin. Wear tracks on glass-infiltrated alumina showed only minor damage consisting of removal of glass from intergranular pockets in this material. In contrast, the hydroxyapatite wear surfaces were covered by an adhered debris layer, which obscured the rough, underlying surface. When dried, this adhered layer was found to contain both single-crystal and polycrystalline hydroxyapatite fragments, together with porous amorphous particulates, containing Ca, P, and O as major elements and Al and La as minor constituents. The composition of this amorphous wear product suggests a tribochemical reaction of hydroxyapatite and infiltrated alumina with water. The wear process, therefore, consists of material removal by fracture and deformation of the hydroxyapatite, followed by mixing of the crystalline fragments with the reaction products and the glass-infiltrate to form a uniform debris layer on the hydroxyapatite wear surface. The effects of this surface layer on wear are considered to include moderation of the local contact stresses and control of the immediate environment under which wear occurs. Our wear data, represented in terms of the wear factor, are found to be consistent with published data on the wear of tooth enamel sliding against different types of ceramic restorations.

Nanoporous tungsten oxide (WO3), with pores of 50 to 100 nm in diameter, has been obtained by galvanostatic (constant-current) anodization of tungsten in a 0.25 M oxalic acid electrolyte. At room temperature, the optimum current density for nanoporous formation is approximately 6.5 to 8 mA/cm2. Monitoring of the anodization voltage during the fabrication process reveals a close match with the theoretical model of Parkhutik et al. [V.P. Parkhutik and V.I. Shershulsky, J. Phys. D 25, 1258 (1992)] for growth of nanoporous Al2O3. The as-anodized films are amorphous and crystallize upon annealing at 350 °C in an oxygen atmosphere.

Two age-hardenable AlCuMg alloys (Cu 4.5 wt.% and Cu/Mg ratios of 2.5 and 8) were studied by electrical resistivity, differential scanning calorimetry, and microhardness measurements during natural and artificial aging at 110 °C. The results were interpreted in terms of Guinier–Preston/Guinier–Preston–Bagariatskij zone formation followed by a modification in θ″ and S″ intermediate phases.

Composites consisting of particles of α-iron dispersed in silicon carbonitride (SiCN) were fabricated by a polymer route. The composites had iron inclusions with the same magnetization as bulk iron, but they resisted oxidation up to 500°C and had a hardness of 5-7 GPa. The composites behaved as ferromagnets, albeit with a low susceptibility attributed to the pinning of the domains by imperfect interfaces and to the elastic resistance from the SiCN matrix. This low-cost, low-temperature processing method can be used to make different kinds of ceramic composites with multifunctional properties.