Josephson Junction and DC SQUID of Y-Ba-Cu-O Thick Film at 77 K

YBa2Cu3O7-x thick films were farbricated by the method of screen printing. Zero resistance temperature of 89 K and critical current density of 130 A/cm2 at 77 K of the films were obtained. The observation of ac Josephson effect at 77 K from weak link Junction of the thick film is reported. The successful dc SQUID operation at 77 K fabricated from the thick film is described. The observation of clear periodic patterns due to the macroscopic quantum interference effect assures promising application of this device at liquid nitrogen temperature.