Abstract
對Tl1212作電阻,磁性及粉膜X光繞射測量和不可逆線研究If we dope rare erath element (Pr,Y,Gd) to the Tl1212, we findthe superconducting temperature rise to the maximum value, thendecrease to the nonsuperconducting state, and when the rareearth is more the a-axis is large. If we measure theirreversibility line for these compounds, we find they obeypowder law:mlog(1-T/Tc) where m=4.5 . These irreversibilityline separate the vortex-solid and vortex-liquid state.