Nanocrystalline (20 nm) lead magnesium niobate (PMN) powders were prepared via a chemical process. This process involved the addition of aqueous niobium tartrate, lead-ethylenediaminetetraacetic acid, and magnesium-polyvinyl alcohol complex to produce a homogeneous solution. After the complete evaporation of the resulting homogeneous solution, the complexes decomposed and produced a black, fluffy precursor material. The precursor material on calcination up to 850 °C/2 h produced nanocrystalline PMN powders with the corresponding average particle size 20 nm. PMN powders modified with lead iron niobate (PFN) (1 – x)PMN–xPFN (x = 0.1, 0.2, and 1) were also prepared using this route and investigated through x-ray diffraction studies.

Ba-filled skutterudite compounds, BayFexCo4−xSb12, were synthesized by a two-step solid reaction method. A binary compound of Sb3Ba and a ternary compound of FexCo1−xSb2 were first synthesized at 900 and 973 K, respectively. The presynthesized Sb3Ba and FexCo1−xSb2 were then mixed with Sb and heated at 973 K in an Ar atmosphere. The resulting powder was of single phase with a composition of BayFexCo4−xSb12, having skutterudite structure with the Sb–dodecahedron voids fractionally filled by Ba. The lattice constant of BayFexCo4−xSb12 increased with Ba and Fe content. The maximum filling fraction of Ba (ymax) in BayFexCo4−xSb12 was found to be greater than that of Ce or La in LnyFexCo4−xSb12, especially in the lower Fe content region. The ymax varied from 0.35 to near 1.0 when Fe content (x) changed from 0 to 4.

Measurement of the electrical conductivity in high-resistance insulators is made difficult by previously unrecognized limits in the electric guarding technique. Electron irradiation experiments on single-crystalline Al2O3, performed for studying the effects of irradiation on the electrical conductivity, revealed that radiation-induced electrical degradation effects in ceramic insulators, previously reported to occur after electron, ion, and neutron irradiation, are an artifact.

Interfacial reactions between an Al thin film and a single-crystal (001) 6H–SiC substrate were investigated using x-ray diffraction and cross-sectional transmission electron microscopy. Aluminum thin films were prepared by radio-frequency magnetron sputtering method on 6H–SiC substrates at room temperature and then annealed at various temperatures from 500 to 900 °C. A columnar-type polycrystalline Al thin film was formed on a 6H–SiC substrate in the as-deposited sample. No remarkable microstructural change, compared to the as-deposited sample, was observed in the sample annealed at 500 °C for 1 h. However, it was found that the Al layer reacted with the SiC substrate at 700 °C and formed an Al–Si–C ternary compound at the Al/SiC interface. Samples annealed at 900 °C showed a double-layer structure with an Al–Si mixed surface layer and an Al–Si–C compound layer below in contact with the substrate.

A significant improvement (40–60%) was reported in the low voltage (100–1000V) cathodoluminescence efficiency of ZnS phosphors coated with SiO2 by the sol-gel technique. The properties of the coatings were found to be critically dependent upon the precursor concentration, pH value and the temperature of the solution with optimum performance being obtained for a SiO2 concentration of 1.0 wt%, pH values between 7–9, and a solution temperature of 83 °C. The efficiency curves exhibited a characteristic voltage dependence which was analyzed by a one-dimensional numerical model. Enhanced low voltage efficiency was attributed to a reduction of surface recombination and the actual shape of the efficiency curve was determined by the interplay between the reduction of surface recombination and energy losses in the SiO2 coating.

BN films consisting of c-BN and h-BN phases were synthesized using an ion-beam-assisted deposition process. In contrast to conventional observations, the c-BN and h-BN phases did not form separate layers, but were distributed in the form of nano-sized grains throughout the film thickness. No distinctly aligned h-BN layer was observed before the c-BN phase. Such a mixed character of the film was attributed to a localized ion bombardment effect instead of the macro-stress. Possibly because of the presence of scattered h-BN phases, the thin film described here possessed a low hardness of about 20 GPa and a low stress of about 5 GPa, compared with other reported c-BN-containing films.

This research involves using molten magnesium (Mg) to remove neodymium (Nd) from NdFeB magnet scrap by diffusion. Mg was melted over pieces of NdFeB scrap and held at temperatures in the range 675–705 °C for 2–8 h. The Mg was allowed to solidify, and the castings were then sectioned and characterized using scanning electron microscopy, x-ray diffraction, and chemical analysis. Nd was found to have diffused out of the solid scrap into the molten Mg. The thickness of the diffusion layer was measured, the diffusion of Nd through the NdFeB scrap into liquid Mg was described, and the diffusion coefficient of Nd in liquid Mg was estimated.

Highly ordered ZnO nanowire arrays were fabricated by oxidizing the metal Zn that was electrodeposited in the pores of anodic alumina membranes (AAMs). The diameters of ZnO nanowires range from 15 to 90 nm. Atomic force microscope, x-ray diffraction, and transmission electron microscopy observations indicate the polycrystalline ZnO nanowires were uniformly assembled into the hexagonally-arranged nanochannels of the AAM. A green emission band caused by the singly ionized oxygen vacancy in the ZnO nanowires was also reported.

A promising approach to control Pb stoichiometry during crystallization of sol-gel-derived lead zirconate titanate (PZT) layers is presented. Pyrolyzed layers were encapsulated in a quartz ampoule containing PbZrO3 powder and crystallized in a lamp furnace. For moderate heating rates, the PbO ambient created by the powder resulted in a pronounced sharpening of the preferential (111) texture, while the remanent polarisation Pr increased by 50% compared to nonencapsulated samples. A significant reduction of the coercive field was seen for layers crystallized under PbO ambient, reflected in a lowering of the switching voltage by 0.5 V compared to standard hotplate crystallized films. The results highlighted the key role of Pb stoichiometry control for further lowering the switching voltage of PZT films.

Al/Al2O3 composites were fabricated by a displacement reaction between SiO2 and molten Al. In this study, fabrication of Al/Al2O3 composites was attempted by means of reactive infiltration to provide variation of their mechanical properties. SiO2 preforms having various porosities and pore size distributions were prepared by sintering the powder at different temperatures between 1273 and 1723 K. Molten Al was infiltrated at 1373 K without application of pressure. Infiltration kinetics were studied and the microstructures of the composite bodies were observed by means of scanning electron microscopy (with energy dispersive x-ray microanalysis), wave dispersive x-ray microanalysis, and x-ray diffractions. The infiltrated specimens were mainly composed of Al and α–Al2O3 phases, and the Si content was less than 5 at.%. Volume fraction of Al phase in the composite bodies was not altered very much with the porosities of the SiO2 preforms because of the difficulty in filling out the entire pore space. Properties and microstructures of Al/Al2O3 composites, however, were dependent on the sintering temperature of the SiO2 preforms. In the case of low sintering temperature, a thick Al channel existed, which deformed upon compression. In the case of high sintering temperature, the microstructure became homogeneous and had thinner Al channels. The composite bodies became brittle. The deformation behavior was shown to be changed from ductile to brittle as an increase of the sintering temperature of the preforms.

Bimodally porous titania powders with controlled phase composition and porosity were made by hydrolysis of titanium tetraisopropoxide (TTIP) and calcination. The extent of calcination was followed by thermogravimetric differential thermal analysis and Fourier transform infrared spectroscopy. The specific surface area (SSA) of the powders ranged from 10 to 500 m2/g as determined by nitrogen adsorption. The SSA increased by decreasing either the water concentration during hydrolysis or the calcination temperature. The pore size distribution was bimodal with fine intraparticle pore diameters at 1–6 nm and larger interparticle pore diameters at 30–120 nm as determined by nitrogen adsorption isotherms. The particle phase composition as determined by x-ray diffraction ranged from amorphous to crystalline anatase and rutile largely proportional to the calcination temperature and to a lesser extent on the initial H2O/TTIP molar ratio.

It is known that diamond films display poor adhesion on metals such as copper and steel. One solution to overcome the poor adhesion is to use interlayer materials. In this study we report results of an investigation of the adhesion behavior of diamond on pure chromium (Cr) and titanium (Ti) substrates. Cr and Ti are promising interlayer materials for adhering diamond to stainless steel. The coating adhesion was studied using indentation tests combined with acoustic emission signals during loading. It was found that a 105-N load indentation caused the film to delaminate from the Cr substrate, while the diamond film remained attached to the titanium even after the indentation at 180 N. Micro-Raman spectroscopy was used to monitor the film stress. The diamond films grown on Ti substrates were found to be less stressed than the films grown on Cr substrates. Therefore, Ti was used in thin-film form to obtain adherent diamond coatings on steel.

NdBCO large-grain materials can improve the performance of engineering devices based on superconducting bulk materials if c-axis-oriented large grains can be produced in large quantities under simple processing conditions. This study concentrates on exploring the factors dictating the seeding behavior and the subsequent growth morphology of Ag-doped NdBCO grains under relatively high oxygen partial pressure using NdBCO seeds and a simple processing system. It was found that seeding temperature, aspect ratio of seed, and amount of Ag were all important factors affecting the success rate of inducing c-axis-oriented growths. With the optimized seeding conditions and in view of the simplicity of the processing system, the processing conditions derived from this study could lead to the up-scaling of NdBCO–Ag large-grain materials production.

PbS/ZrO2 optical films were prepared by the dip-coating method from a mixed sol containing two precursors, Zr(OC3H7)4 and Pb(CH3COO)2. The phase structure and size of PbS nanoparticles were characterized by x-ray diffraction and transmission electron microscopy, respectively. Optical absorption and fluorescence spectra were taken on the PbS/ZrO2 films. Larger blue shifts of band edge and weak fluorescence emission of PbS were observed. The third-order nonlinear properties of PbS/ZrO2 films were studied. The calculated values of nonlinear refractive indexes n2 varied between 10−8 and 10−9 cm2/W.

The fatigue resistance of the interface between electroless–nickel and the eutectic tin–lead solder alloy was examined in the as-reflowed and aged conditions and compared to fatigue behavior of the copper/solder interface under the same conditions. In the as-reflowed state, the fatigue resistance of the solder/electroless-nickel interface was slightly superior to that of the solder/copper interface. However, after long-term aging, the fatigue resistance of the solder/electroless-nickel interface became far worse in the high crack growth rate regime. Examinations of interfacial microstructures and crack growth mechanisms indicated that the differences in fatigue resistance between the two interfaces were not directly related to the thickness of the intermetallic phase at the interface, as commonly believed, but were due to differences in crack growth mechanisms.

Precursor powders with antimony-to-iron (Sb/Fe) atomic ratios ranging from 0 to 2.0 were prepared by chemical coprecipitation. The origin of enhanced gas-sensing behavior at a higher calcining temperature was investigated, based on phase evolution and microstructure characterized by means of thermal analysis, x-ray diffraction, Brunauer–Emmett–Teller surface area measurement, and electron microscopy. Only one iron–antimony oxide (i.e., FeSbO4) could be obtained under present experimental conditions. Pure FeSbO4 exhibited a high gas sensitivity, only when calcining temperature was below 600 °C. A rapid crystallite growth, as well as hard agglomeration, occurred in pure FeSbO4 powder calcined at 600–1000 °C, and thus led to poor gas-sensing behavior. However, there existed an optimal Sb/Fe ratio range (i.e., 0.25 to 0.65) in which crystallite growth of both α–Fe2O3 and FeSbO4 could be efficiently depressed up to 800 °C. The samples (with Sb/Fe ratio in the range 0.25–0.65) calcined at 600–800 °C displayed a high sensitivity to liquid petroleum gas due to their large specific surface area and poor crystallinity.

We prepared Ce3+-doped silica by the sol-gel method and studied the effect of annealing on fluorescence of these samples. Different fluorescence was observed for samples annealed at different temperatures, changing gradually from solution like fluorescence to fluorescence similar to that observed in the Ce3+-doped silica prepared by chemical vapor deposition. It was found that the emission intensity first decreased with increasing annealing temperature until 500 °C, and then increased with the temperature ranging from 500 to 950 °C. Meanwhile, the emission peak showed a large red shift and an obvious broadening. These changes were attributed to the annealing-induced structural evolution in silica: Ce3+ ions changed from coordinating with water and terminal OH-groups to embedding in silica network.

A method was presented for the formation and metallization of cylindrical tubules from a diacetylenic lipid. This improved technique allowed for the production of metal microcylinders without the need for preliminary lipid purification and in large quantities. The physical and electrical properties of the material were investigated, and composites were used to form parallel plate capacitors. A comparison of the conductivity of the bulk material with the derived conductivity of a composite showing electromagnetic percolation showed the proportionality of the specific packing density and the critical volume fraction characteristic of percolating systems.

Stoichiometric yttrium aluminate garnet (Y3Al5O12) precursors with a wide range of chemical compositions were precipitated by dripping a mixed solution of ammonium aluminum sulfate and yttrium nitrate into ammonium bicarbonate solutions. The resultant precursors were characterized by chemical analysis, infrared spectroscopy, differential thermal analysis/thermogravimetry, x-ray diffractometry, and scanning electron microscopy. The effects of reaction temperature, precipitant concentration, dripping speed of the salt solution, and the molar ratio of precipitant/total-cations on the composition, thermal behavior, and particle morphology of the resultant precursors were investigated. The precipitation conditions that yield carbonate precursors composed of ammonium dawsonite [NH4Al(OH)2CO3] and yttrium normal carbonate [Y2(CO3)3 · 3H2O] were determined.

Stability of submicron contacts under high current density has been an outstanding reliability issue in advanced Si devices. Polarity effect of failure was observed in Ni and Ni2Si contacts on n+-Si and p+-Si. In this report, we studied the failure due to high current density in contacts to n+- and p+-silicon-on-insulator (SOI). We found similar polarity effects below certain current: the p+-SOI failed preferentially at the cathode, while the n+-SOI failed preferentially at the anode. At higher current, damage occurred at both contacts. The effect of current crowding was evident in both cases.