Oxygen doping tuning in superconducting oxides by thermal annealing and hard X-ray irradiation

Bi2Sr2CaCu2O8+δ (Bi-2212) superconducting whiskers, owing to their microscopic size, are good candidates for the fabrication of miniaturized devices for production/sensing of THz-radiation based on their Intrinsic Josephson Junctions (IJJ) properties. With this respect, several studies demonstrated the possibility of controlling whisker IJJ parameters by modifying the oxygen content. In this paper we show that both thermal annealing and hard X-ray irradiation are effective ways to tune the oxygen doping. In particular, we monitored the effect of an annealing process at 363 K and of irradiation by 17 keV micro- and nano-beams on the structural and superconducting properties of selected Bi-2212 whiskers. Moreover we modeled by a finite element simulation the temperature field induced by the X-ray beam to try to clarify the origin of the measured changes.