We first measured the thermoelectric properties of layer-structured homologous compounds, (ZnO)mIn2O3 (m = integer), and reported that they would becomecandidate materials for high-temperature thermoelectric energy conversion.1–4 We further tried to improve their thermoelectric properties by partially substituting yttrium for indium in (ZnO)5In2O3. Though the ionic radius of Y3+ is larger than that of In3+, the a-axis (hexagonal system) elongated and c-axis shrank as Y was substituted for In. The thermoelectric properties were found to vary with a varying amount of Y substitution; 3% Y substitution gave rise to the largest thermoelectric figure of merit, i.e., 1.1 - 1.3 × 10-4 K-1 at 960–1100 K. The abnormal change in the lattice structure by Y substitution was responsible for the unusual behavior of the thermoelectric properties.

Epitaxial Tl2Ba2CaCu2O8 (Tl-2212) films ∼5500 Å thick are grown on LaAlO3(100) substrates using a new hybrid two-zone/crucible furnace process enabling precise control of thallination. This method combines the best features of both conventional crucible and two-zone processing for the first time: superb film properties and reduced handling of hazardous Tl-oxide powders. Single-phase, highly caxis oriented Tl-2212 films are grown with smooth morphology, Meissner transition ∼103 K, and critical current density ∼1.1 × 107 A/cm2 at 5 K for twenty consecutive runs without having to change or add to the Tl-oxide source.

Thin films of (Y0.92Eu0.08)2O3 were synthesized through chemical vapor deposition of β-diketonate precursors onto glass and sapphire substrates. The films were weakly luminescent in the as-deposited condition and were composed of spherical particles 3 μm in diameter. A KrF laser was pulsed for 25 ns from 1–3 times on the surface of the films. One pulse was sufficient to melt the film and repeated pulses caused ablation of the material. Melting of the film smoothed the surface, increased the density, and increased the photoluminescent emission intensity.

Based upon the analysis of materials cycling and processing on the earth, a thermodynamic concept for energetical and environmental problems has been proposed. It concludes that solution processing using aqueous solutions should be the most important processing even for advanced materials. According to this concept, energetical and environmental features of soft solution processing (SSP) are discussed in general, using also some particular examples, such as BaTiO3. Applications of the SSP are shown with special emphasis on hydrothermal and/or electrochemical synthesis of thin films and integration issues. Soft solution processing allows one to fabricate in aqueous solutions shaped/sized/oriented ceramics in only one step, without excess energies for firing/sintering or melting and without expensive equipment, providing an environmentally friendly route for the preparation of advanced ceramic materials.

Complex three-point junctions of single-walled carbon nanotubes are proposed as building blocks of nanoscale electronic devices. Both T- and Y-junctions, made up of tubes with differing diameters and chiralities, are studied as prototypes. All the proposed complex junctions have been found to be local minima of the total energy on relaxation with a generalized tight-binding molecular dynamics scheme.

Plastic instabilities were observed to appear during dynamic ultramicrohardness testing of a solid solution Al–3.3 wt.% Mg alloy. The tests were carried out at room temperature with a Vickers hardness indenter in a computer-controlled dynamic ultramicrohardness testing machine. During the tests the applied load was increased from 0 to 2000 mN at constant loading rate. The instabilities appear as characteristic steps in the continuously recorded load-indentation depth curves. The physical basis for the occurrence of the instabilities is the interaction between moving dislocations and solute atoms, a phenomenon termed in the literature as serrated yielding, jerky flow, or Portevin-Le Châtelier effect. The instabilities start at a critical load, Fc, in the depth-load curve. Varying the loading rate, μ, by two orders of magnitude Fc was found to increase linearly with the loading rate.

The microstructure and ductility of directionally solidified Ni50Al20Fe30 were studied. Calculation and experiment show that the elastic modulus of the sample with completely eutectic lamellar structure is higher than that of the sample with dendritic structure. During deformation, in the samples with dendritic structure, some load is transferred from the proeutectic area to the γ-rich eutectic area and enhances the ductility of the sample.The existence of thick interdendritic γ phase and thick lamellar γ phase in the eutectic area of the dendritic sample is very effective in suppressing the microcrack propagation and also contributes to the ductility enhancement.

The advancement of the photovoltaic technology is closely linked to the standard evaluation of the product, the diagnosis of problems, the validation of materials and cell properties, and the engineering and documentation of the ensemble of device properties from internal interfaces through power outputs. The focus of this paper is on some of the more common, visible, and important techniques dealing with physical-chemical through electro-optical parameters, which are linked intimately to the performance quality of materials and devices. Two areas, defined by their spatial-resolution qualities, are emphasized: macroscale and microscale measurement technologies. The importance, strengths, and limitations of these techniques are stressed, especially their significance to photovoltaics. Included are several techniques that have been developed specifically to address problems and requirements for photovoltaics. The regime of measurement literally covers arrays through atoms.

Zeolite P was formed from class F fly ash under hydrothermal conditions. The fly ash was reacted with 2.8 or 5 M NaOH at 100 °C. Zeolite of the above type was produced regardless of the NaOH concentration or the addition of quartz, thus indicating its formation over a wide range of conditions. The zeolite produced was of the NaP-type with a fibrous morphology. Analysis of the pore structure of this zeolite by the BET method indicates a type II isotherm. The specific surface areas of synthesized zeolites increased from 28.5 to 41.1 m2/g when the NaOH concentration was increased from 2.8 to 5.0 M. This zeolite showed a significant selectivity for the uptake of Cs and Sr. Cs uptake ranged from 7.67 to 8.61 meq/100 g while that of Sr ranged from 9.8 to 10.54 meq/100 g. The value obtained depended on the specific synthesis conditions. These values are higher than those observed for tobermorite prepared from the same fly ash even though the tobermorite exhibited a higher specific surface area.

The characteristic inhomogeneous distribution of nonsuperconducting Y2BaCuO5 (211) inclusions in melt-processed YBa2Cu3O7−δ (123) grains has generally been attributed to 211 particle pushing by 123 growth fronts during peritectic solidification on the basis of reduced total surface free energy. Analysis of the morphology of the interfaces at the 211–211–123 and 211–211-liquid triple points in seeded melt-processed samples invalidates this assumption for the pure YBCO system and has implications of the mechanism of 211 particle segregation.

We have developed a unique method to produce smooth diamond films using a modified microwave plasma process system. This method consists of sequential in situ deposition and planarization in an electron cyclotron resonance plasma system. Diamond films were deposited to a thickness of 3.0 μm in this system at a pressure of 1.000 Torr from gas mixtures of methanol and hydrogen. Deposition was followed by planarization using a two-grid ion beam extraction process with a pure oxygen plasma at 10 mTorr. The average roughness of the diamond films so produced was as low as 30 nm, which was a factor of two lower than that of the as-deposited diamond films.

Methods for synthesizing ceramic materials from aqueous solutions at ordinary temperature and pressure are advantageous because of the applicability to making films with wide areas and/or complicated shapes with no requirement of vacuum or high temperature, and because of lower cost. Powder of ZrO2 or LnMeO3 (Ln = La, Nd; Me = Cr, Mn, Fe, Co) perovskite was dissolved in hydrofluoric acid and a solution of fluoro-complex ions was obtained. Boric acid was added to the solution, the fluoride ions were consumed by the formation of BF4-, and then the fluoro-complex ions were hydrolyzed to ZrO2 or LnMeO3 in order to increase the amount of fluoride ions. A number of synthesized particles of ZrO2 or LnMeO3 were observed on the substrates in scanning electron microscope images.

The photovoltaic properties of the polycrystalline silicon depend on the crystallinity and the purity of the material. The thermal plasma process gives us an alternative method of silicon preparation since it is possible to produce an ultrahigh purity with simultaneously a passivation of crystalline defects and active impurities. We demonstrate the efficiency of the plasma purification process and particularly the influence of the atomic hydrogen in an argon thermal plasma on the photovoltaic properties of silicon. The results of the diffusion lengths measured by the photoelectrochemical method show that locally it rises up to 200 μm. We correlate these photovoltaic measurements with the properties of the crystal (defects and purity) by means of measurements by Fourier transform infrared spectroscopy (FTIR) at low temperature (6 K), four probes resistivity technique, scanning electronic microscopy, inductively coupled plasma (ICP), and neutronic activation analyses. We show that the increase of the purity explains the high me asured diffusion lengths. Nevertheless, the thermal conditions of the crystallization of the silicon, due to the specificity of the plasma, lead to defects such as dislocations for which density is particularly high (>106 dis/cm2). The results show that chemical reactions between the atomic hydrogen of the plasma and the oxygen of the silicon occur. They decrease the oxygen content in silicon from 3 × 1017 at./cm3 down to 2 × 1016 at./cm3, while the residual hydrogen in silicon is close to 2 × 1015 at./cm3. This passivates the dangling bonds of ultrapure silicon with a high thermal stability up to 1000 K. The objective of this paper is to demonstrate that the hydrogen in the plasma modifies the electronic properties of the material to achieve a very good photocurrent even though the dislocation density of the silicon is very high.

Epitaxial β–SiC film has been grown on a mirror-polished Si(111) substrate using bias-assisted hot filament chemical vapor deposition (BA-HFCVD) at a substrate temperature of 1000 °C. A graphite plate was used as the only carbon source, and hydrogen was the only feeding gas to the deposition system. Atomic hydrogen, produced by hot filaments, reacted with the graphite to form hydrocarbon radicals which further reacted with the silicon substrate and deposited as β–SiC. The effect of negatively biasing the substrate is the key factor for epitaxial growth. Under the same growth conditions without negative bias, polycrystalline β–SiC resulted.

We present two microinstruments for submicron scale material characterization. One of the instruments applies torsion on two single crystal silicon bars with square cross sections,1 and 2.25 μm2, until fracture. The maximum shear stress prior to fracture is found tobe 5.6 and 2.6 GPa, respectively. The second instrument applies tension on a composite (aluminum-silicon dioxide) beam, 1 × 1.5 μm2 in cross section. The beam fails at 220 μN.In both the experiments, the samples are designed, patterned, and cofabricated with the instruments. The microinstruments' small size, low thermal mass, vacuum compatibility, and built-in vibration isolation allow material characterization to be performed over a wide range of environmental conditions: high vacuum (electron microscopy and surface analysis), high humidity, high pressure, and high and low temperatures.

Borosilicate glasses with different waste loadings were prepared by ambient melting, quenching, and annealing. Some melt compositions partially crystallize to durable phases of zircon and forsterite. The coexisting liquid quenches to glass and endures the leach tests. The waste loading dependent leach rate trends of these glasses are reminiscent of the mixed alkali effect. Raman spectra suggest initial increase in durability with increases in the depolymerization of silicate species. Fluorine and hydroxyl ions also contribute to depolymerization. Tetraborate and metaborate rings are identified in the Raman spectra. The durability is enhanced when tetraborate bands are more intense than the metaborate bands.

The problems encountered to tailor simultaneously various specific chemical or physical properties are discussed. Selected polymeric precursors used in association with fine powders allow the control of the nano/microstructure of composites and hence the preparation of functional (FGM) and hierarchical reinforced (HRC) composites, making it possible to combine several kinds of fibers, interphases, and matrices in the same composite (hot microwave absorbent), to control the fiber/matrix interface (long life times composites), to achieve net-shape sintering of 3D composite matrices, and to prepare thick films of metal-ceramic composites with tailored microwave absorption (radar stealthiness).

A kind of fullerenes, carbon nanoparticle encapsulating β–SiC grain, was precipitated during cooling Al2O3–Y2O3 –CaO oxide melt containing SiC and C from 2023 K. The SiC grains with a diameter of 5–20 nm were covered with 2–4 graphitic carbon layers with the spacing of 0.34 nm as revealed by high resolution transmission electron microscopy. The result provides a new preparation method of carbon nanoparticles through a ceramic process, which contrasts with previous physical methods applying electric arc discharge or electron irradiation in vacuum.

(Ba1−xLax)3Cu3(O, F)y films were prepared using a sol-gel method. Phases, the c lattice parameters of which are about 13.8, 13.1, and 11.6 Å, respectively, were formed in the films. The compound with the c parameter of ˜13.8 Å is considered to be a Ba2−xLaxCuO2F2+δ which has the La2CuO4-type structure inserted with fluorine. The compound with the c parameter of ˜11.6 Å is thought to have a three-layered structure of the perovskite block which is arisen by ordering between La and Ba elements. The films containing these compounds showed some interesting anomalies in SQUID measurements. However, no film showed a drastic decrease of electrical resistance.

Alumina powders were synthesized by the emulsion combustion method, using w/o (water in oil) type emulsions with different aqueous microsphere sizes. The effects of microsphere size on the size and shape of the synthesized powder were evaluated. The powders were spherical and hollow in shape with a very thin shell (from 10 to 20 nm in thickness) when synthesized from large aqueous microspheres (from 200 nm to 1 μm). The sizes and specific surface areas of the powders were consistent with those calculated. Large particles, which did not correspond to the microsphere size, were obtained from small aqueous microspheres (6 nm). The short distance (7 nm) between microspheres causes the adhesion of particles during the firing process.