Microstructural study of samples irradiated with rays at high doses

Abstract

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.

Point and extended defects in superconductors

“…As discussed in the introduction, the regions of the grains are largely insensitive to γ-rays, while the regions of the grain boundaries of the polycrystalline HTSC material are expected to be very sensitive to γ-irradiation doses, causing either a net enhancement at low doses and might cause a net suppression of the transport properties (mostly at high doses). This result has been confirmed by experiments on HTSCs polycrystals [19] and crystals [34,35]. Thus, we may conclude that the major changes to the critical current density observed in our results are mainly due to the nature of the regions of the grain boundaries combined with their high sensitivity to γ-rays.…”

The effects of γ-irradiation on some physical properties of Cu–13.5 wt.%Al–4 wt.%Ni shape memory alloy

“…Second, the Compton electrons are produced by g-photons from some atoms and part of the energy will be imparted to the atoms by the momentum conversation [21]. g-Irradiation may also be evaluated that irradiation affects atomic structure of the alloy and g-irradiation is the reason for defects consisted in the structure [22]. The nominal displacement per atom (dpa) level was estimated as 1.03 Â 10 À 9 dpa.…”

XPS studies of YBa2Cu3O7??/Ag high-TC superconductor

“…So, for a low silver concentration (YBC/Ag5), incorporation of Ag in the YBC structure can be considered according to Rangel et al 9 Silver atoms diffuse into the YBC structure, leading to the occupation of some Cu sites by Ag: the atomic Cu 2C radius (0.72Å) is very close to the Ag C radius (1.13Å). Therefore, incorporation of silver atoms would result in an increase in Cu 3C formal content, which corresponds to the increase of parameters (I s /I m and Cu 2p 2/Cu 2p 3 intensity ratio) obtained from our XPS measurements.…”

“…5 -11 Most of the literature reported that Ag does not react with YBC whatever the temperature up to 960°C. 5 -7 Some works also suggested that Ag can occupy Cu sites in the YBC lattice 8,9 for a very low amount of silver. It must be mentioned that high-resolution interfacial studies using XPS or high-resolution transmission electronic microscopy (HRTEM) were carried out on thin films or crystals presenting a given orientation.…”