Microstructure of Ybco Irradiated with 200 Kev Protons and 1 Mev Fluorine Ions

Abstract

Transmission electron microscopy (TEM) has been used to study the effects of 200 keV proton and 1 MeV fluorine ion irradiation on the microstructure of YBa2Cu3O7-δ (YBCO). Proton irradiation at fluences on the order of 1016 cm−2 results in more visible defects than can reasonably be expected solely from high energy transfer events; medium energy transfer events also contribute to visible defects. Defects arising from cascade events can be as large as 2 to 3 nm, and high resolution imaging suggests that they consist of small volumes of structurally disordered material. Fluorine irradiation to similar displacement levels results in significantly more visible defects.

Experimental study of microstructure and critical current density of YBCO/Ag thick films under silver addition and electron irradiation

“…The changes detected in T c and T 0 bring as a consequence an increase of the width of transition, T c = T c − T 0 , from 12 to 38 K. In a recent experience with YBCO-silver samples irradiated with gamma rays, we found an increase in T c and T c of 2 and 5.3 degrees, respectively, when the samples were irradiated at 1500 kGy [11]. Because the majority of the high T c superconductors contains a granular structure the increase in T c is cited as a common result of the damage reached via irradiation at the grain boundaries [21][22][23]. The T c value depends on the natural characteristics of the material and also it is dependent on the material preparation.…”

“…On the other hand, the critical temperature, T c , has increased from 80 to 88 K; this result seems striking if we consider the results obtained in bulk [18] or YBCO single crystals [19,20] where T c is reported to change by order of 2 or 3 degrees. Other irradiation sources such as protons [21], fluorine [21] or helium ions [22] have been also employed to modify the transport properties of YBCO films. In those cases a J c increase is reported at moderate irradiation dosage with a subsequent decreasing of the T c value.…”