RF-SQUID EFFECT IN HG(TL)-BA-CA-CU-O HIGH-T-C THIN-FILM UP TO 121 K

Hg(TI)-Ba-Ca-Cu-O high-T-c films have been prepared by the spray pyrol ysis technique. The process involves preparation of a precursor film o f Ba-Ca-Cu-O followed by annealing in a Hg-TI atmosphere. The resultan t film had T-c approximate to 127.5 K and predominantly consisted of 1 223 phase. An rf-SQUlD has been fabricated using natural grain boundar y weak links. The SQUID shows good voltage-flux modulations at 77 K an d the peak-to-peak voltage of the modulation remains constant up to 11 8.5 K. It starts decreasing above 118.5 K and finally disappears at 12 2 K. The flux noise density of the SQUID at 2 Mt and 77 K is 2 x 10(-3 ) Phi(0) Hz(-1/2). If does not change much up to 117.4 K and shows a p eak at 120.5 K.