Effect of Energetic Charged Particle Bombardment on the Properties of Thin Films of High Tc Superconductors

摘要

The effects of low fluence ( < 10 to the 14th power/sq cm) 63 MeV H(+) and 65 MeV He2(+) irradiation of prototype thin films of YBa2Cu3O(7 - delta), produced by a plasma arc spray technique are examined. The observed change in the resistance versus temperature behavior is much more dramatic than that observed for films produced by other techniques and resembles qualitatively a bond percolation threshold. The radiation sensitivity of these plasma-arc spray films is concluded to be due to poor intergranular characteristics. This information is being used to modify the processing steps to improve the properties of films produced by this technique. In contrast, high energy H and He ion irradiation of the laser evaporated films resulted in a negligible change in the resistance-temperature behavior. The low energy B and N ion irradiation of the laser evaporated films had the effect of a gradual lowering of the completion temperature of the superconducting transition (T sub C - completion). The gradual lowering of T sub C - completion with fluence, d (delta T sub c) / d phi, with similar results by other groups. This behavior is interpreted as a progressive decoupling of the grains and extrinsic to that of the bulk YBa2Cu3O(7-delta). (JHD)