POSSIBLE HIGH A1 SUBSTITUTION IN THE T1-Ba-Ca-Cu-O SUPERCONDUCTING SYSTEM

The A1 substitution in the T1-Ba-Ca-Cu-O superconducting system was studied.Up to 70%of Tl can be substituted by Al,without significant reduction of Tc.X-ray diffraction indicates partial A1 substitution does not alter the crystal structure of the 2223 phase.Excessive A1 formed Al-Cu alloy and unidentified phases,which gradually destroyed the superconductivity.