EFFECT OF AG2O ADDITION IN Y0.9CA0.1BA2CU4O8 ON THE STRUCTURE AND CONTACT RESISTIVITY OF Y0.9CA0.1BA2CU4O8 AG/

Effects of Ag2O addition in Y0.9Ca0.1Ba2Cu4O8 on the structure and the contact resistivity of Y0.9Ca0.1Ba2Cu4O8/Ag interfaces have been inve stigated by tile measurements of X-ray diffraction and contact resisti vity. For Ag2O-free specimens, they must be sintered three times at 80 0 degrees C for 24 h with intermediate grinding to obtain the pure 124 phase. However, with addition of 25 wt% Ag2O in Y0.9Ca0.1Ba2Cu4O8, th e single 1-2-4 phase can be formed with sinted only one time at 800 de grees C for 24 h. The lowest ohmic-contact resistivity about 4.55 x 10 (-5) Omega . cm(2) at 300 K and less than 10(-8)Omega . cm(2) below T- c for Ag2O-free system are observed by annealing at 600 degrees C for 1 h under one oxygen atmosphere. With addition of 25 wt% Ag2O in Y0.9C a0.1Ba2Cu4O8, the optimal annealing temperature to obtain the lowest o hmic-contact resistivity call be improved down to 400 degrees C. ill f act, a low-resistivity ohmic contact for the Y0.9Ca0.1Ba2Cu4O8/Ag inte rface can be achieved without any thermal annealing just by the additi on of 25 wt% Ag2O in Y0.9Ca0.1Ba2Cu4O8. These results indicate that th e addition of Ag2O can aid the formation of the 1-2-4 phase and upgrad e effectively the characteristics of Y0.9Ca0.1Ba2Cu4O8/Ag interfaces t o get better ohmic contact even without annealing, resulting in a lowe r annealing temperature and contact resistivity.