Browsing by Author "Smith, R. J."

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Ion beam induced adhesion in Al/diamond bilayer
(1991-07-01) Saleh, Adli A.; Smith, R. J.; Shutthanandan, Vaithiyalingam; Bao, Z. X.; Schmidt, V. Hugo
Diamond anvil cells are often used to study phase transitions in materials under high pressure. To probe these transitions, electrodes with low resistance and good adhesion properties are desired. Such electrodes were obtained using ion beam mixing techniques. The diamond anvil was first irradiated with a 100 keV Ar+ beam with an ion dose of 1016 ions/cm 2. Resistance measurements of the irradiated area indicated that ion beam damage induced a low-resistance phase of carbon. A thin Al film (≈ 500 Å) was then deposited on the diamond anvil followed by Ar+ irradiation. The deposition and irradiation processes were repeated, followed by resistance measurements after each irradiation. The measurements indicate the formation of a low resistance layer (R ≈ 10gW). A qualitative test of adhesion was performed by scratching the formed layer with the resistance probes. The resistance of the electrode showed an acceptably small increase as a function of scraping. These results can be understood on the basis of recoil mixing in the Al/diamond system.
Low temperature sintering of Ba(Zr0.8‑xCexY0.2)O3-δ using lithium fluoride additive
(2010) Tsai, Chih-Long; Kopczyk, Michael; Smith, R. J.; Schmidt, V. Hugo
Lithium fluoride (LiF) was selected as a liquid phase sintering additive to lower the sintering temperature. The effects of LiF on the sinterability, microstructure, and electrochemical properties of Ba(Zr0.8 − xCexY0.2)O3 − δ (0 ≤ x ≤ 0.4) (BZCYs) ceramics were investigated. Using LiF as an additive, high density BZCYs ceramics can be obtained at sintering temperatures 200–300 °C lower than the usual 1700 °C with much shorter soaking time. Nuclear reaction investigations showed no lithium and a small amount of fluorine reside in the sample which indicates the non-concomitant evaporation of lithium and fluorine during the sintering process. Scanning electron microscopic investigations showed the bimodal structure of BZCYs ceramics and grain growth as Ce content increases. In a water saturated hydrogen containing atmosphere, BZCYs ceramics have higher conductivity when LiF is used in the sintering process. LiF-added BZCYs electrolyte-supported fuel cells with platinum electrodes were tested at temperatures from 500 to 850 °C. Results show that LiF is an excellent sintering additive for lowering the sintering temperature of BZCYs.