INDUCTANCE PROBE EXAMINATION OF SUPERCONDUCTING TL-BA-CA-CU-O CERAMICS

Sintered pellets of 2212 and 2223 Tl-Ba-Ca-Cu-O superconducting ceramics have been prepared using the sealed gold tube technique and examined by the inductance probe methods recently described by the authors. The L-T data show T(c)'s in the range 110 to 120 K in good agreement with previous alternative methods; at 77 K the observed drop in inductance indicated that 55% of the volume of material was superconducting by contrast to the behaviour of YBCO, the inductance falls steadily from about 250 K before the main superconducting transition is reached. Inductance-field measurements made below T(c) show that H(cl) almost-equal-to 10 G. Q-factor versus temperature data were also obtained. This method proved very sensitive for detecting and characterizing the separate phases present in multiphase material in addition to providing dielectric data. Above T(c) the dielectric loss of 2212 Tl-Ba-Ca-Cu-O was found to be epsilon" = 7.9 x 10(-2) with a temperature coefficient partial-epsilon"/partial T of 4.3 x 10(-4) K-1 over the range 160 to 220 K. These values are comparable with those previously reported for Y-Ba-Cu-O superconducting ceramics.