Some metal-graphite and metal-ceramic composites for use as high energy brake lining materials

Materials were studied as candidates for development as potential new aircraft brake lining materials. These families were (1) copper-graphite composites; (2) nickel-graphite composites; (3) copper - rare-earth-oxide (gadolinium oxide (Gd2O3) or lanthanum oxide (La2O3)) composites and copper - rare-earth-oxide (La2O3) - rare-earth-fluoride (lanthanum fluoride (LaF3)) composites; (4) nickel - rare-earth-oxide composites and nickel - rare-earth-oxide - rare-earth-fluoride composites. For comparison purposes, a currently used metal-ceramic composite was also studied. Results showed that the nickel-Gd2O3 and nickel-La2O3-LaF3 composites were comparable or superior in friction and wear performance to the currently used composite and therefore deserve to be considered for further development

High efficiency thermal to electric energy conversion using selective emitters and spectrally tuned solar cells

Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1500 K. Depending on the nature of parasitic losses, overall thermal-to-electric conversion efficiencies greater than 20 percent are feasible

Single-Phase Rare-Earth Oxide/Aluminum Oxide Glasses

Glasses that comprise rare-earth oxides and aluminum oxide plus, optionally, lesser amounts of other oxides, have been invented. The other oxide(s) can include SiO2, B2O3, GeO2, and/or any of a variety of glass-forming oxides that have been used heretofore in making a variety of common and specialty glasses. The glasses of the invention can be manufactured in bulk single-phase forms to ensure near uniformity in optical and mechanical characteristics, as needed for such devices as optical amplifiers, lasers, and optical waveguides (including optical fibers). These glasses can also be formulated to have high indices of refraction, as needed in some of such devices

W Field Emission Cathode Covered with Rare Earth Oxide Mono-Layer. : PEEM analysis and FEM analysis

When the apex of tungsten field emitter modified by rare earth oxide mono-layer, the work function of W(100) surface is reduced. The low work function surface is expected to be much emission current. The work function of W(100) surface modified by rare earth oxide mono-layer are measured by PEEM (Photo Emission Electron Microscope). The field emission characteristics were observed with the tungsten field emitter modified by rare earth oxide. And, the work function was estimated from the F-N plots特集 : 「希土類研究プロジェクトの軌跡」 2. 希土類の特性を活かした高度なサスティナビリティを有する材料およびプロセス開

Gibbs energies of formation of rare earth oxysulfides

The standard Gibbs energy change accompanying the conversion of rare earth oxides to oxysulfides by reaction of rare earth oxides with diatomic sulfur gas has been measured in the temperature range 870 to 1300 K using the solid state cell: Pt/Cu+Cu2S/R2O2S+R2O3||(CaO)ZrO2||Ni+NiO, Pt where R=La, Nd, Sm, Gd, Tb, and Dy. The partial pressure of diatomic sulfur over a mixture of rare earth oxide (R2O3) and oxysulfide (R2O2S) is fixed by the dissociation of Cu2S to Cu in a closed system. The buffer mixture of Cu+Cu2S is physically separated from the rare earth oxide and oxysulfide to avoid complications arising from interaction between them. The corresponding equilibrium oxygen partial pressure is measured with an oxide solid electrolyte cell. Gibbs energy change for the conversion of oxide to the corresponding oxysulfide increases monotonically with atomic number of the rare earth element. Second law enthalpy of formation also shows a similar trend. Based on this empirical trend Gibbs energies of formation of oxysulfides of Pr, Eu, Ho, and Er are estimated as a function of temperature

Selective Emitters

This invention relates to a small particle selective emitter for converting thermal energy into narrow band radiation with high efficiency. The small particle selective emitter is used in combination with a photovoltaic array to provide a thermal to electrical energy conversion device. An energy conversion apparatus of this type is called a thermo-photovoltaic device. In the first embodiment, small diameter particles of a rare earth oxide are suspended in an inert gas enclosed between concentric cylinders. The rare earth oxides are used because they have the desired property of large emittance in a narrow wavelength band and small emittance outside the band. However, it should be emphasized that it is the smallness of the particles that enhances the radiation property. The small particle selective emitter is surrounded by a photovoltaic array. In an alternate embodiment, the small particle gas mixture is circulated through a thermal energy source. This thermal energy source can be a nuclear reactor, solar receiver, or combustor of a fossil fuel

Biocompatible Nano Rare Earth Oxide Upconverters for Imaging and Therapeutics

Methods and systems for doping cerium oxide and other therapeutically valuable nanoparticles with rare earth ions either singly or in combinations so that infrared light is absorbed and visible light is emitted through the process of up conversion. A novel type of therapeutic nanoparticle with rare earth doping to provide for up conversion emission is invented that makes possible identification, tracking and evaluating the functionality of the nanoparticles and further elucidation of ROS scavenging mechanism. The present invention may be applied to a wide variety of therapeutic agents under investigation

Metal-doped rare earth oxide catalysts for condensations to ketones

Metal-doped supported rare earth oxide catalysts were examined to determine their suitability for the decarboxylative condensation of two carboxylic acids to produce ketones. The catalysts were characterized based on chemisorption tests, coke analysis using thermo-gravimetric analysis and X-ray absorption spectroscopy. Effect of catalyst particle size on rate of reaction was studied for various supported cerium oxide catalysts. Catalysts were tested for activity, selectivity, and stability using isothermal fixed bed reactors. Optimal operating conditions for the production of diisopropyl ketone and methyl nonyl ketone were determined. It was found that supported cerium oxide catalysts effectively catalyzed the condensation of isobutyric acid to diisopropyl ketone for up to 12 hours of operation at weight hourly space velocities of ~4-5. On most occasions these catalysts showed no sign of deactivation at the end of 12 hours. Reactivation with air at 540 °C was sufficient to maintain long-term activity. The optimal temperature range was 470-480 °C. Activity could by improved by using catalyst particle sizes \u3c 1 mm. Doping (0.1 - 2.4 wt.%) a supported cerium oxide catalyst with a transition metal such as Mn or Pd deactivated the catalyst but the addition of 0.8 wt.% Co increased the molar yield to diisopropyl ketone. For methylnonyl ketone production from acetic acid and decanoic acid the optimal operating conditions using supported cerium oxide catalysts were 400-420 °C at weight hourly space velocities of ~4-6. Buildup of coke on the catalyst was observed. However, yield loss due to this coke formation was negligible, and the coke was easily removed by reactivation with air at 520 °C. Doping a supported cerium oxide catalyst with a transition metal such as Co or Pd increased both the activity and selectivity. Reaction results indicate a ketene-like surface intermediate is involved in the mechanism. The role of the transition metal dopants may be to facilitate the recombination of atomic hydrogen, produced during the formation of a ketene-like intermediate, with surface -OH groups, thereby increasing the reaction rate of ketone formation