Preparation of YBaCuO and BiSrCaCuO thin films and low temperature annealing effects

Abstract

YBaCuO and BiSrCaCuO thin films were prepared by a laser deposition method and characterized by electric and magnetic measurements. The substrate temperature and oxygen pressure during the cooling process were found to be the two important parameters for the growth of in situ YBaCuO thin films. For the bismuth compounds, the ([ Bi]:[ Sr]:[ Ca]:[ Cu] = ) 2:2:1:2 phase was reproducibly prepared on MgO substrates with critical temperatures of 80–83 K and critical current densities above 10 3 A cm −2 at 77 K. Low temperature annealing treatments (at 350 °C in an argon atmosphere) can increase the critical temperature up to 89 K. The same behaviour is reported for lead-doped 2:2:1:2 films, with critical temperatures of 72–76 K before and 82–85 K after the 350 °C post-annealing treatment.The 2:2:2:3 phase was also investigated and the best film showed a critical temperature of 110 K and a critical current density of 5×10 4 A cm −2 at 77 K.