We have investigated the damage induced by irradiation in silver added samples. The samples were prepared with 0 and 6.5 wt% of silver and irradiated by high-energy irradiation (50-150 Mrad). The roles of silver and dosage irradiation are discussed in terms of their effects on microstructure, crystallinity, critical temperature and zero-resistance temperature . After irradiation, decreased while the room-temperature electrical resistance increased by a factor of 8 for some of the samples. The difference in between irradiated and non-irradiated YBCO samples was of the order of 10 K. We have found that the difference is bigger for silver-added samples. We have also observed several changes in diffraction patterns of YBCO and YBCO-silver samples. SEM images, EDS and XPS analysis showed that silver resided inside the grains as single atoms and as metallic clusters. The relative concentrations of the elements in samples were quantified by Auger electron spectroscopy. The values showed a gradual increase for radiation doses ranging between 0 and 100 Mrad. For doses up to 100 Mrad, decreased because of the weak-link breakage induced by high doses of rays.
Bi 2 MO 6 (M=Mo, W) compounds were prepared for low-temperature oxidation. The catalysts were prepared by solid-state reaction. The structural changes were followed by X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy and BET nitrogen absorption. Auger analysis shows that Bi 2 WO 6 catalysts have more bismuth on the surface than γ- Bi 2 MoO 6, although both samples are bismuth deficient as compared to the stoichiometric compound. The results regarding catalytic activity show that Bi 2 WO 6 prepared at 1073 K reaches total conversion of CO (100%) at a lower temperature when compared to γ- Bi 2 MoO 6. This indicates that Bi 2 WO 6 is a potential candidate to be used as catalyst in the CO to CO 2 oxidation.
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