The occupation of volume in large ceramic injection mouldings solidified under different pressures using two moulding techniques is considered. Large (60 × 45 × 25 mm) alumina injection mouldings were prepared in cavities fitted with conventional (metallic) and insulated [poly(ether ether ketone)] sprues. These provide quite distinct solidification histories which, in turn, influence the physical properties of the moulding and the extent and type of defects it contains. In the former case, the gate solidified after 26 s whereas, in the latter, the hold pressure could be applied for over 240 s. In insulated sprue moulding, the advance of the solid liquid boundary during packing and solidification was traced by fractography. Pressure was varied from 5 to 120 MPa. The interdependencies of moulding mass, apparent density, local density, polymer crystallinity, and microstructure were accounted for as a function of pressure and pressure transmission method. Changes in polymer crystallinity due to different cooling rates at different positions in the mouldings were insufficient to account for observed density differences. Systematic changes in the mass as a function of hold pressure were related to macroporosity in conventional mouldings and to microporosity in insulated sprue mouldings.

Zn2−xMnxSiO4 phosphors were synthesized by a hydrothermal process using ZnO and SiO2. Prismatic Zn4Si2O7(OH)2 · H2O particles were formed through heterogeneous nucleation on the surface of the ZnO particles. The Zn2SiO4 phase was formed through an isometric phase transition of Zn4Si2O7(OH)2 · H2O. Water pressure, as well as the particle size of the raw materials, had a profound effect on the temperature of phase formation. The effect of solution pH on the morphology and growth of the particles was investigated. The photoluminescence of the synthesized Zn2−xMnxSiO4 phosphor was also examined. The color coordinate of the Zn2−xMnxSiO4 phosphor obtained in this study showed a green color, which was shifted toward short wavelength.

Films of poly(ether sulfone) have been implanted with 50-keV As+ in the dose range of 1015 to 1017 ions/cm2. Nanoindentation tests were then conducted on these films using a conical diamond tip with a 90° included angle, applying loads from 10 μN to 2 mN. The modulus and hardness were evaluated from the load–displacement data using the elastic unloading [J. Mater. Res. 7, 1564 (1992)] and the elastic–plastic unloading [J. Mater. Res. 13, 421 (1998)] models. The latter approach gave more reliable values for the mechanical properties since it is not as sensitive to creep-in effects. The implanted film showed as much as a twofold increase in hardness compared to the unimplanted polymer. However, the films with the highest dose did not exhibit the maximum values for the mechanical properties. Hardness and modulus values increased with increasing implantation dose up to 1 × 1017 ions/cm2 but dropped at higher doses, presumably due to a combination of sputtering of material and surface roughening. The dose dependence of the mechanical properties is observed to have the same trend as are reported for the electrical properties.

A chemical vapor deposition process has been developed for titanium dioxide (TiOx) for applications as capacitor dielectric in sub-quarter-micron dynamic random-access memory devices, and as gate insulators in emerging generations of etal-oxide-semiconductor transistors. Studies using the β-diketonate source precursor (2,2,6,6-tetramethyl-3,5-heptanedionato) titanium were carried out to examine the underlying mechanisms that control film nucleation and growth kinetics and to establish the effects of key process parameters on film purity, composition, texture, morphology, and electrical properties. Resulting film properties were thoroughly analyzed by x-ray diffraction, x-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, scanning electron microscopy (SEM), focused-ion-beam SEM, and capacitance–voltage (C–V) measurements. The study resulted in the identification of an optimized process for the deposition of an anatase–rutile TiOx film with a dielectric constant approximately 85 at 1 MHz for a 330-nm thickness, and a leakage current below 2 × 10−8 A/cm2 for bias voltage values up to 3.5 V.

The hydrophilic properties of amorphous TiOx films prepared by different methods, e.g., radio frequency (rf) sputtering and plasma-enhanced chemical vapor deposition (PECVD), were studied. It was found that the hydrophilicity strongly depends on the film structure. The best hydrophilicity was realized with the PECVD amorphous film having distorted Ti–O bonds due to a large amount of OH groups. These characteristics of the PECVD amorphous film suggest that such a low-density film including distorted Ti–O bonds could increase the photoenhancement efficiency by ultraviolet radiation. This reason is also supported from the results that a low-density rf sputtered film presented a higher hydrophilicity compared to a high-density radio frequency sputtered film. Furthermore, both electrical and chemical effects of OH groups will also contribute to the good hydrophilicity of the PECVD film.

We present a numerical method to find specific composite microstructures with targeted effective properties. The effective properties that may be prescribed are quite diverse and include transport, mechanical, and electromagnetic properties, as well as properties associated with coupled phenomena, such as piezoelectric and thermoelectric coefficients. We formulated the target problem as an optimization problem. To illustrate our general target optimization technique, we have successfully found two-phase composite microstructures having specified effective electrical or thermal conductivities at fixed volume fractions. The method can also be used to design microstructures with multifunctional characteristics.

Thin films of lanthanum cuprate were grown on SrTiO3 substrates by pulsed laser deposition and made superconducting (Tc ∼ 38 K) through the process of post-deposition fluorination using elemental fluorine. A microstructural analysis showed that the [110] zone of the film grows parallel to the [100] zone of the SrTiO3 substrate, reducing the lattice mismatch from 37.5% to 2.4%. At the film–substrate interface there is an intermediate layer 3–4 nm thick and twin-related grains emanate from this region. Stacking faults are present in the bulk of the film, with misoriented subgrains present at the deposit surface.

The mechanical deformation of crystalline silicon induced by micro-indentation has been studied. Indentations were made using a variety of loading conditions. The effects on the final deformation microstructure of the load–unload rates and both spherical and pointed (Berkovich) indenters were investigated at maximum loads of up to 250 mN. The mechanically deformed regions were then examined using cross-sectional transmission electron microscopy (XTEM), Raman spectroscopy, and atomic force microscopy. High-pressure phases (Si-XII and Si-III) and amorphous silicon have been identified in the deformation microstructure of both pointed and spherical indentations. Amorphous Si was observed using XTEM in indentations made by the partial load–unload method, which involves a fast pressure release on final unloading. Loading to the same maximum load using the continuous load cycle, with an approximately four times slower final unloading rate, produced a mixture of Si-XII and Si-III. Slip was observed for all loading conditions, regardless of whether the maximum load exceeded that required to induce “pop-in” and occurs on the {111} planes. Phase transformed material was found in the region directly under the indenter which corresponds to the region of greatest hydrostatic pressure for spherical indentation. Slip is thought to be nucleated from the region of high shear stress under the indenter.

Prealloyed powders of the intermetallic γ–TiAl phase and the ceramic Ξ–Ti5Si3 phase were high-energy milled and hot-isostatically pressed (HIP) to produce silicide dispersed composite materials with grain sizes in the submicron and nanometer range. The amorphous state of the as-milled powders crystallizes via a multistep decomposition reaction during degassing at 440 °C and HIP. At a pressure of 200 Mpa HIP-temperatures as low as 750 °C are sufficient for a complete densification of the milled powder. The microstructure of the compacts is very homogeneous and consists of equiaxed γ–TiAl crystals and Ξ–Ti5(Si,Al)3 particles. Depending on the silicon content, these particles are interspersed within the grain boundary network of the γ–TiAl phase or dispersed inside the γ grains. With respect to technical applications, submicron-grained composites are regarded as promising precursor materials that should allow for easy hot working in the as-prepared state as well as for high-temperature structural applications after a suitable transformation of the microstructure.

Solid-state foaming of commercial purity titanium was achieved by hot-isostatic pressing of titanium powders in the presence of argon, followed by expansion of the resulting high-pressure argon bubbles at ambient pressure and elevated temperature. The foaming step was performed under isothermal conditions or during thermal cycling around the α/β allotropic temperature of titanium. Such thermal cycling is known to induce transformation superplasticity (TSP) in bulk titanium due to the complex superposition of internal transformation stresses and an external biasing stress; TSP was found to be active during foaming, where the deviatoric biasing stress was provided by the internal pore pressure. As compared to isothermal control experiments where foam expansion occurred by creep only, TSP foaming under thermal cycling conditions led to significantly higher terminal porosity (41% as compared to 27%). The foaming rates were also higher for the TSP case before pore growth ceased. Additionally, foaming experiments were conducted under an externally applied uniaxial tensile stress of 1 MPa. This procedure resulted in foaming kinetics and porosities similar to those achieved without an external stress and, for the TSP case, led to high aspect ratio pores elongated in the direction of the applied external stress.

The more-stringent requirements for densification of new out-of-equilibrium powders have created a growing demand for nonconventional rapid sintering processes. Among those, field-assisted sintering techniques (FASTs) have seen a recent renewed interest motivated by their ability to consolidate a large variety of powder materials into high densities in short times. Characterization of a range of FAST-consolidated materials displayed relevant associated surface effects, such as grain boundary cleaning with direct grain-to-grain contact and advanced densification without sintering aids. These effects may be attributed to phenomena ranging from dielectric breakdown to a possible nonconventional plasma generation. Such surface effects provided a better intergranular bonding of powder particles during subsequent sintering

To investigate the photovoltaic effect in Sn2P2S6 ferroelectrics, Sn2P2S6 crystal and ceramic sample that had a high relative density of 95% and a grain size of below 1 μm were fabricated. The steady-state photovoltaic currents under infrared light illumination on both Sn2P2S6 crystal and ceramic sample were observed for the first time. The photovoltaic currents ipv on Sn2P2S6 ceramic sample and crystal were 5 and 25 nA/cm, respectively. The difference in the magnitude of the photovoltaic current resulted from the difference in the remanent polarization Pr between the crystal and the ceramic sample. The values of the photovoltaic field Epv determined from I–V curve for Sn2P2S6 ceramic sample and crystal were 0.2 and 6 V/cm, respectively; these values were several orders lower than that observed on the perovskite-type ferroelectric ceramics. The photovoltaic fields observed in this study were discussed with the conductivity of the crystal and the ceramic sample, in consideration of the figure of merit for the photostriction.

Undoped and Sm3+-doped BaAl2S4 and BaAl2Se4 single crystals were grown by the chemical transport reaction method. The optical energy band gaps of the BaAl2S4 and BaAl2Se4 were found to be 4.10 and 3.47 eV, respectively, at 5 K. In their photoluminescence spectra measured at 5 K, broad emission peaks at 459 and 601 nm appeared in the BaAl2S4 and at 486 and 652 nm in the BaAl2Se4. These emissions are assigned to donor–acceptor pair recombinations. Sharp emission peaks were observed in the Sm3+-doped BaAl2S4 and BaAl2Se4 single crystals at 5 K. Taking into account the ionic radii of the cations and Sm3+, these sharp emission peaks are attributed to the electron transitions between the energy levels of Sm3+ substituting with the Ba site.

The effects of low-energy electron bombardment during the chemical vapor deposition of diamond were studied. The film growth was monitored in real time with in situ phase-modulated ellipsometry, in order to trigger the electron bombardment at different growth stages. Ex situ Raman spectroscopy and scanning electron microscopy were employed to evaluate the crystalline quality and the morphology of the grown films, respectively. The results indicated that triggering the electron bombardment after high-quality scattered diamond crystallites had formed results in finely grained smoother films of similar diamond yield and crystalline quality as those grown without bombardment. However, the electron bombardment deteriorates the film crystalline quality and the diamond yield when it was triggered from the start of deposition.

A simple method for kinetic analysis of solid-state processes has been developed. A criteria capable of classifying different processes is explored here with a view toward visualizing the complexity of solid-state kinetics. They provide a useful tool for the determination of the most suitable kinetic model. The method has been applied to the analysis of crystallization processes in amorphous ZrO2 and RuO2. It is found that the crystallization kinetics of as-prepared sample exhibits a complex behavior under nonisothermal conditions. This is probably due to an overlapping of the nucleation- and crystal-growth processes at the beginning of crystallization. As a consequence, the Johnson–Mehl–Avrami nucleation-growth model cannot be applied. A two-parameter autocatalytic model provides a good description of the crystallization process under isothermal and nonisothermal conditions.

Nanocrystalline yttria-stabilized zirconia (nc-Y-TZP) powders coated with 10 vol% sodium strontium silicate glass were prepared by the sol-gel method. The glass is found to uniformly coat the zirconia particles or particle aggregates. The presence of the glass was found to enhance the densification of the powder compacts leading to 97% of the theoretical density compared to 90% in the pure nc-Y-TZP. It also resulted in a fine microstructure, homogeneous particle shape, and narrow size distribution. The polyhedral-shaped faceted grains in the sintered pure Y-TZP were converted to round-shaped grains in the glass containing specimens

The orientation dependence of the ferroelectricity of epitaxially grown Bi4Ti3O12 thin films was investigated. The (001)-, (118)-, and (104)-oriented Bi4Ti3O12 films were epitaxially grown on (100)cCaRuO3//(100)SrTiO3, (110)cSrRuO3//(110)SrTiO3, and (111)cSrRuO3//(111)SrTiO3 substrates, respectively, by metalorganic chemical vapor deposition. Ferroelectric property with different magnitude was observed for (001)- and (118)-oriented films but for (104)-oriented film due to its large leakage current. The remanent polarization and the coercive field were 1.5 mC/cm2 and 15 kV/cm, 16.5 νC/cm2 and 132 kV/cm for the (001)- and (118)-oriented thin films, respectively. The spontaneous polarization (PS) was 4.0 νC/cm2 and 27.0 νC/cm2 for (001)- and (118)-oriented films, respectively. This was different from the result of SrBi2Ta2O9 in that the ferroelectricity was not observed for (001)-oriented one, and was in good agreement with the estimation from the crystal structure. The estimated PS values along the c and a axes of Bi4Ti3O12 were 4.0 and 48.4 νC/cm2, respectively, and agreed well with the reported values for the single crystal. Furthermore, both films showed good fatigue endurance after 7.8 × 1010 switching cycles measured with 500 kHz rectangular pulses.

The structure and composition of SiNx/Si/SiNx films were investigated by means of x-ray reflectivity, x-ray photoelectron spectroscopy, and atomic force microscopy. The three-layer films were prepared by radio-frequency magnetron sputtering under the condition of constant nitrogen flow and the argon flow. It was found that the deposition rate and surface structure of the silicon nitride films were mainly determined by the nitrogen flow rather than the argon flow. But the composition of the silicon nitride films was controlled by the gas flow ratio (FAr/FN2) used during sputtering.