On-line monitoring of the dissolved impurities in molten metals is important for better process control during alloying and metal refining operations. Disposable-type oxygen sensors are commercially available and are used in the iron and steel industry worldwide. However, there is a need for developing low-cost, reliable, long-life oxygen sensors for continuous monitoring of dissolved oxygen in molten metals. In this paper we present the results of the physical and electrical characterization of the solid electrolyte material ZrO2 (8 mol%Y2O3). The experimental results of the application of long-life solid-state electrochemical sensors designed using yttria-stabilized zirconia solid electrolyte for the measurement of oxygen potential in molten tin between 823 to 1273 K and standard Gibbs energy of formation of SnO2 from its elements are also reported.

Strontium bismuth niobate vanadates, SrBi2 (VxNb1-x)2O9 (with 0 ≤ x ≤ 0.1), were prepared by reaction sintering of powder mixtures of constituent oxides. With partial substitution of niobium by vanadium cations (up to 10 at.%), the single-phase layered perovskite structure was preserved, and the sintering temperature of the system was significantly lowered (∼200 °C). The incorporation of vanadium into the layered perovskite structure resulted in a shift of the Curie point to higher temperatures from 435 to 457 °C, with 10 at.% vanadium doping, and an increase in dielectric constant from ∼700 to ∼1100, with 10 at.% vanadium doping, at their respective Curie points. The remanent polarization increased from ∼2.4 to ∼8 µC/cm2, while the coercive field decreased from ∼63 to ∼45 kV/cm with 10 at.% V5+ doping.

Material damage caused by fretting wear is of significant concern in many engineering applications. This paper describes the design and performance of a new machine for the laboratory investigation of fretting wear under oscillating normal force (fretting mode II). The test machine uses an electromagnetic actuator to impose an oscillating normal force between the contacting bodies at a constant force amplitude over a wide range of frequencies. The principle of the actuation mechanism and the fretting wear induced with this particular wear test configuration are outlined in detail. Normal force and electrical contact resistance were measured on-line during fretting mode II wear tests. The performance of the wear test machine is illustrated by data obtained for different materials combinations, namely, hard materials, such as high-speed steel and (Ti,Al)N coatings oscillating against alumina ball counterbodies, and soft materials, such as a tin coating oscillating against the same. In general, wearing of the counterbodies was observed in the slip region. It has been observed that hard coatings and bulk ceramics are prone to fretting fatigue cracking. The evolution of electrical contact resistance in the case of the self-mated soft tin coatings tested under fretting mode II conditions is also reported.

Distribution characteristics of boundary phase in BaB2O4 added BaTiO3 ceramics were investigated with a focus on the curvature difference of solid–liquid interfaces at two-grain and triple junctions. High-resolution transmission electron microscopy revealed that the triple junction of solid grains showed the positive curvature of solid–liquid interface and consisted of the mixture of liquid phase and crystallized BaB2O4 phase. On the other hand, flat amorphous thin film of 2.5-nm thickness was observed at the two-grain junction. This kind of boundary phase distribution characteristic was explained by the solubility difference between two kinds of junctions of solid grains that had different curvature of solid–liquid interfaces.

When a eutectic melt is undercooled below its liquidus T1 by a critical amount, it undergoes metastable liquid-state spinodal decomposition. The resulting morphologies can be described as intermixing undercooled liquid networks of characteristic wavelength λ. At a temperature substantially below T1, λ can be <100 nm. When λ ≤ 100 nm, the undercooled liquid networks break up into nanometer-size droplets/strips driven apparently by surface tension. The morphologies of the tiny droplets/strips can be frozen by subsequent crystallization. The as-crystallized specimen is a nanostructured material. It is microvoid free and the size of the constituent grains is rather uniform. Two systems, Pd40.5Ni40.5P19 and Pd82Si18, were chosen to illustrate the synthesis process.

The aim of this study is to demonstrate that the electronic and structural properties of II–VI substrates, here ZnTe, can be dramatically affected by thermal heating at temperatures in the range of those typically used in the epitaxial metalorganic chemical vapor deposition processes. Photoluminescence response shows that annealing at these temperatures produces a reduction of the sample crystalline quality, decreasing the free exciton emission relative to the deep level related one. Some factors, like the change in the charge and stress state of dislocations, Cu diffusion, and oxygen incorporation, could be responsible for changes in the substrate properties, which can produce stresses and contamination in the deposited sample.

The reaction of the bulk glass forming alloy Zr41Ti14Cu12Ni10Be23 (Vit 1) with W, Ta, Mo, AlN, Al2O3, Si, graphite, and amorphous carbon was investigated. Vit 1 samples were melted and subsequently solidified after different processing times on discs of the different materials. Sessile drop examinations of the macroscopic wetting of Vit 1 on the discs as a function of temperature were carried out in situ with a digital optical camera. The reactions at the interfaces between the Vit 1 sample and the different disc materials were investigated with an electron microprobe. The structure and thermal stability of the processed Vit 1 samples were examined by x-ray diffraction and differential scanning calorimetry. The results are discussed in terms of possible applications for composite materials.

Al2O3–TiB2 composites were synthesized by the combustion reaction 3TiO2 + 3B2O3 – (10 + x)Al, with x ranging from 0 to 4.71. The products consisted of corundum, TiB2, and a trace of Ti2O3 for the reactions with x = 0 and x = 1.4. However, the products of the reaction with x = 2.96 contained corundum and TiB2 only. For products of samples with x = 0, 1.4, and 2.96, similar room-temperature absorption spectra were observed in the ultraviolet and visible range at wavelengths of 265, 706, and 844 nm. Room-temperature photoluminescence spectra of the composites showed one visible band at about 720 nm. Room-temperature cathodoluminescence (CL) spectra of the composites synthesized by reactions with x = 0 and 1.4 exhibited two visible bands centered at 400 and 710 nm, respectively. From samples synthesized with x = 2.96, another visible band centered at 570 nm was observed in the CL spectrum. Comparing secondary electron images to panchromatic and monochromatic CL images of the composites, it was found that the light-emitting phase is TiB2-containing corundum. The 710-nm band is attributed to the transition between 1T1 (et) and 3T2 (et) excited states, and the 570- and 400-nm bands to the transitions between 3T1 (et) or 3A2 (e2) and 1T1 (et) excited states and 3T1 (t2) ground state of Ti2+ in corundum, respectively.

The crystallization kinetics and film microstructure of poly-SiGe layers obtained by solid-phase crystallization of unimplanted and C- and F-implanted 100-nm-thick amorphous SiGe films deposited by low-pressure chemical vapor deposition on thermally oxidized Si wafers were studied. After crystallization, the F- and C-implanted SiGe films showed larger grain sizes, both in-plane and perpendicular to the surface of the sample, than the unimplanted SiGe films. Also, the (111) texture was strongly enhanced when compared to the unimplanted SiGe or Si films. The crystallized F-implanted SiGe samples showed the dendrite-shaped grains characteristic of solid-phase crystallized pure Si. The structure of the unimplanted SiGe and C-implanted SiGe samples consisted of a mixture of grains with well-defined contour and a small number of quasi-dendritic grains. These samples also showed a very low grain-size dispersion.

The ferrite with composition Cu0.5Fe2.5O4 was heat treated in air and in reducing atmospheres to different temperatures within the solid solution region confirmed by dynamic high-temperautre x-ray characterization. The samples were quenched in oil and air, and lattice parameter, Curie temperature, and saturation magnetization measurements were completed. The magnetization measurements for these samples showed a maximum 4πMs of 0.7729 and 0.5426 T at 10 and 300 K, respectively. The cationic distribution based on the low-temperature 4πMs measurements is (Cu+0.24Fe3+0.76)A[Cu+0.26Fe3+1.74]BO4 → 4.9 µ B. X-ray-pure Cu0.5Fe2.5O4 samples were also synthesized by slow cooling from the formation temperature to 900 °C in a reducing atmosphere. A temperature–PO2 diagram for the stability of Cu0.5Fe2.5O4 under the conditions of the experiment was determined. Low-temperature 4πMs measurements did not indicate an increase in the Cu+ A site occupancy for the samples cooled to 900 °C in a reducing environment above those samples that were quenched from high temperature. Curie temperatures for all Cu0.5Fe2.5O4 samples ranged from 348 to 369 °C. Lithium additions (0.1 mol/unit formula) to copper ferrite Li0.1Cu0.4Fe2.5O4 decreased the room-temperature 4πMs values to 0.5234 T with a corresponding decrease in the 10 K measurements to 0.7047 T. From the low-temperature magnetization measurements, the distribution was (Cu+0.15Fe3+0.85)A[Cu+0.25Li+0.1Fe3+1.65]BO4 → 4.48 µ B.