A new finding is reported for the surface corrugation induced in the superplastic deformation and flow of 3 mol% yttria-partially stabilized tetragonal zirconia polycrystal and β-spodumene glass ceramic, the former including no secondary phase and the latter having a plenty of glassy phase at grain boundaries. A significant test specimen size effect on the resistance to superplastic deformation is also addressed. These findings are related to the microscopic processes and mechanisms of cooperative grain-boundary sliding.

Transition of a SrBi2Ta2O9 precursor film from amorphous to crystalline was inducedby excimer laser irradiation. Both fluorite and perovskite crystalline structures in suchfilms were obtained by excimer laser irradiation at substrate temperatures between 200and 500 °C. Either an addition of excess bismuth in the precursor film or an increasein the substrate temperature enhanced the formation of the perovskite structure in theexcimer laser-induced annealing process, resulting in the perovskite crystalline phase ata relatively lower temperature of 500 °C. Such a low temperature is preferred whenSrBi2Ta2O9 is used in ferroelectric devices. The mechanism involved in thislaser-induced crystallization is also discussed.

Thin films of La0.67Sr0.33MnO3 (LSMO) were prepared at 670 °C on LaAlO3 (LAO) and SrTiO3 (STO) substrates by liquid-delivery metalorganic chemical vapor deposition. X-ray diffraction analysis 2¸/¸ and pole figure scans showed that the films are epitaxial with (001)LSMO//(001)LAO and (001)LSMO//(001)STO. The crystal structure of LSMO/LAO was indexed as face-centered cubic with a double cell and LSMO/STO as simple cubic. Electron microscopy revealed square facets and elongated grain features. Films heat-treated between 700 and 800 °C on LAO resulted in a structural change, while those on STO showed an increase in texture.

Blue photoluminescent emission was observed in pure nanometer-sized γ–Al2O3 powders prepared by the sol-gel process, with aluminum alkoxide as the precursor. The photoluminescent excitation spectrum detected at »em = 422 nm showed four peaks located at 238, 255, 278.5, and 348.5 nm, respectively, the first having the strongest intensity. The photoluminescent emission spectra were made up of a broad band with four peaks located at 404.5, 422, 447, and 484.5 nm. The emission band of 422 nm had the intensity. We suggest that the defect level in the nanometer alumina powder also is the main reason for the appearance of new luminescent emission bands.

A magnesium (Mg) solid solution with a long periodic hexagonal structure was found in a Mg97Zn1Y2 (at.%) alloy in a bulk form prepared by warm extrusion of atomized powders at 573 K. The novel structure has an ABACAB-type six layered packing with lattice parameters of a = 0.322 nm and c = 3 × 0.521 nm. The Mg solid solution has fine grain sizes of 100 to 150 nm and contains 0.78 at.% Zn and 1.82 at.% Y. In addition, cubic Mg24Y5 particles with a size of about 7 nm are dispersed at small volume fractions of less than 10% in the Mg matrix. The specific density (ρ) of the extruded bulk Mg–Zn–Y alloy was 1.84 Mg/m3. The tensile yield strength (σy) and elongation (δ) are 610 MPa and 5%, respectively, at room temperature, and the specific yield strength defined by the ratio of σy to ρ is as high as 3.3 × 105 Nm/kg. High σy values exceeding 400 MPa are also maintained at temperatures up to 473 K. It is noticed that the σy levels are 2.5 to 5 times higher than those for conventional high-strength type Mg-based alloys. The Mg-based alloy also exhibits a high-strain-rate superplasticity with large δ of 700 to 800% at high strain rates of 0.1 to 0.2 s−1 and 623 K. The excellent mechanical properties are due to the combination of the fine grain size, new long periodic hexagonal solid solution containing Y and Zn, and dispersion of fine Mg24Y5 particles. The new Mg-based alloy is expected to be used in many fields.

Stoichiometric barium titanate (BaTiO3) was synthesized in aqueous solution with acetone and/or methanol as additives to control the crystallization process. Adjusted nano-sized particles and narrow particle size distributions were achieved at 60 °C with additive concentrations up to 243 ml/ l. The growth kinetics showed that the additives influence the nucleation of the BaTiO3 particles and tend to suppress Ostwald ripening.

Nano-sized barium titanate (BaTiO3) particles prepared by the sol-to-precipitate method in aqueous/organic medium served to obtain thin-layer ceramic films of the tetragonal electroactive phase. Poly(methacrylic acid) works efficiently to process the suspensions and to obtain green films. Sintering the green films under O2–Ar atmosphere gave thin-layered ceramics of a thickness of 0.5–1.0 mm with a dielectric constant of 3750 at 20 °C (1 kHz).

Precise control of porosity and microstructure of porous ceramics is essential. This paper describes a method for the preparation of porous ceramics with porosity from 0.0 to 0.4. The ceramics were prepared via hot pressing a powder mixture to a definite dimension, and the porosity was easily adjusted by the powder amount. As examples, porous Si3N4 or SiC ceramics were produced by powder mixtures that contained Si3N4 or SiC and a sintering additive of oxide. It was demonstrated that the present method is advantageous for producing ceramics with controllable porosity and microstructure.

A study was made of the effects of whisker content and dimensions on the R-curve behavior of an alumina matrix composite reinforced with silicon carbide whiskers. Experiments showed that the rising R-curve behavior is strongly enhanced by the increase in the volume fraction and the size of whiskers. Simulation based on a model of crack face whisker bridgings was made to elucidate the effects on the R-curve of the composite. The validity of the simulation was confirmed by good agreement between the experimental and the calculated R-curves. In addition to the R-curve, the distribution of crack closure stresses as well as crack tip opening displacements was also calculated, which directly reflects crack face whisker bridging processes in the composite. Then the dependence of whisker content and dimensions on the R-curve was analytically discussed taking the bridging processes into account.

The fabrication of rodlike Ca α-sialon crystals through a combustion synthesis process is reported in this paper. The main morphological features in the product included rodlike crystals, two dimensional elongated platelets, and equiaxed particles. By proper adjustment of the combustion parameters, a high productivity of rodlike Ca α-sialon crystals in the final product could be achieved. The combustion reaction mechanism and the relationship between the combustion parameters and the particle morphology were investigated.

Twinned and detwinned Yba2Cu3O7−y (Y123) single crystals were observed by transmission electron microscopy to investigate the influences of the lattice defects on the peak effect for Y123 single crystals. Twin boundaries with the spacing of 0.2–0.5 μm were seen only in the twinned Y123 single crystals. Antiphase boundaries (APBs) along the (110)Y123 plane were observed in both twinned and 0.5h-detwinned samples, which showed the peak effect in high magnetic field over 3 T at 70 K. In contrast, APBs were not found in 100h-detwinned sample. Critical current densities of this sample were small all over the range of the applied magnetic field. In conclusion, we suggest that APBs have a significant influence on the peak effect of Y123 single crystals in the high magnetic field.

Electrodeposited thin films of CdTe and CdxHg1−xTe with 1 − x = 0 and approximately 0.1 were characterized by x-ray photoelectron spectroscopy. The composition of the bulk and the thickness and composition of the native surface oxide before and after Ar+ ion sputtering were determined. A surface oxide layer 20-Å thick constituted mainly of alloyed TeO2 and CdO was found over a nearly stochiometric bulk. Chemical diffusion of Hg, Cd, and Te to the surface was observed. Hg appears to inhibit oxidation of the telluride, mainly of Te. Ar sputtering removed undesirable oxides and impurities off the films.

The effect of microstructure on residual stress in diamond thin film was investigated. The diamond thin film was deposited by the hot filament chemical vapor deposition process with hydrogen/methane precursor gas and followed by annealing at 1150 °C for 1–30 min. The residual stresses of the diamond thin film were measured by Raman spectroscopy. A model to estimate the residual stress was proposed on the basis of grain boundary relaxation mechanism and microstructural analysis of diamond thin film. It is confirmed that the residual stress in diamond thin film is proportional to a microstructural factor, 1/ [D( f + 1)]1/2, where D is the grain size of diamond and f is the volume ratio of nondiamond carbon/diamond.

The structure and hardness of C60 bulk specimens compressed under 5.5 GPa at room temperature to 600 °C are investigated by high-resolution transmission electron microscopy, x-ray diffraction, and micro-Vickers hardness tests. A strong accumulation of the [1 1 0]tr orientation of high-pressure-treated C60 specimens was developed along the compression axis, and stacking faults and nano-sized deformation twins were introduced into the C60 specimens compressed at 450–600 °C. Curved lattice planes indicating a polymerization of C60 were observed by high resolution transmission electron microscopy (HRTEM). The polymerization of the high-pressure-compressed C60 is also supported by the computer simulation of HRTEM images.

Chemical stresses induced by grain-boundary diffusion in thin films were analyzed. The stress distribution consisted of both tension and compression fields, and its characteristics were similar to those obtained for a semi-infinite solid. At a given time, the maximum stress (tension or compression) increased with increasing film thickness for both constant and instantaneous sources; it was generally higher than that in the semi-infinite system. The maximum stress (tension or compression) decreased as the diffusion time increased and at a given time and film thickness it increased with decreasing diffusivity ratio. The buildup of local stress is likely to cause damage and malfunctions of the film when used in an electronic device.

Silica–polyimide nanocomposites were prepared by hot-pressing mixtures of polyimide and highly porous silica powder. The silica powder was produced using a sol-gel process that generates pores as small as 15 Å. The effects of loading, cure, and post-cure temperature on fracture toughness were investigated. The addition of silica particles improved the fracture toughness from 0.5 to a maximum of 1.9 MPa m0.5. However, fracture toughness dropped at silica weight percentages ≥30%. The cure and post-curing temperatures have a strong influence on toughness; post-curing exposure ≥400 °C reduced toughness. Transmission electron microscopy examination of the fracture surfaces indicated that the toughness improvements may occur at the nanometer scale due to crack pinning and branching induced by the nanoporous silica particles.

Conducting polyaniline/barium titanate (PANI/BaTiO3) composites exhibiting piezoresistivity properties have been synthesized by the in situ deposition technique by placing a fine grade powder of BaTiO3 in the polymerization reaction mixture. The polyaniline was formed preferentially on the ceramic particles giving a much higher yield for PANI than in absence of the BaTiO3 These composites exhibited piezoresistivity with the piezosensitivity being maximum at a certain composition. The current–voltage characteristics clearly revealed a nonlinear space charge controlled charge transport process. A large hysteresis in these characteristics was also observed which was dependent on the BaTiO3 content in a composite. The various results have been explained on the basis of the charge transport mechanism in the heterogeneous conducting material having insulating domains dispersed in it.

Rectifying and thermocouple junctions have been achieved using electrically dissimilar Portland cement pastes. The preferred junction is a pn-junction involving steel fiber cement paste (n-type) and carbon fiber cement paste (p-type). For this junction, the thermocouple sensitivity is 70 εV/°C.

The objective of this paper is to report on the anelastic, i.e., reversible and time-dependent, deformation behavior of precursor-derived amorphous ceramics. Therefore compression experiments under constant and varying stresses up to 250 MPa were performed at a temperature of 1400 °C. In the stress change experiments anelasticity was observed. By comparison of both types of experiments, the anelastic strain rate was determined. It decreased inversely proportional to the time after the stress change and was independent of the preceding duration of the test. Furthermore, deviations from the deformation behavior expected according to the free-volume-model, which were observed in compression creep tests, could be explained by anelastic behavior.

The microstructural characteristics of ion-beam-sputtered conductive SrRuO3 films, such as interfacial reactions, which govern growth behavior, defects, and thermal stability, were investigated using transmission electron microscopy. On a Si substrate, two binary constituents of SrRuO3, i.e., SrO and RuO2 were shown to have quite different reaction behaviors. The reduction of the RuO2 constituent to elemental Ru by Si led to an unstable contact of SrRuO3 on the Si substrate. Possible reaction thermodynamics are suggested, which are based on the formation energies of the corresponding reactions. In the case of films grown in an oxygen-deficient atmosphere, stacking faults were observed. The stacking faults originated from twinning on the {111}pc plane to accommodate the oxygen deficiency in the growth atmosphere by changing the arrangement of RuO6 octahedra from corner to one of face sharing.