IMPROVED TRANSPORT-PROPERTIES OF POLYCRYSTALLINE YBCO THIN-FILMS

Resistive evaporation technique was used to fabricate polycrystalline Y-Ba-Cu-O and Y-Ba-Na-Cu-O thin films on MgO substrates. Heat treatmen t was carried out in a low oxygen partial pressure. Polycrystalline YB CO and Na doped YBCO thin films samples were thus obtained using the s ame technique and conditions. The critical current density of Na doped YBCO sample was measured to be significantly higher than that of the undoped YBCO one. The results are discussed in terms of the Na contrib ution to the intragrain conductivity.