X-RAY DIFFRACTION STUDY OF A NEW SUPERCONDUCTOR Tl2-xEuxBa2Ca2Cu3O10

Ⅰ. INTRODUCTIONAfter H. Maeda et al. discovered a high T_c superconductor in the Bi-Sr-Ca-Cu-O system, which does not contain any notable rare-earth element, Z. Z. Sheng et al. discovered subsequently another high T_c superconductor in T1-Ba-Ca-Cu-O system. Its T_c seems higher than Bi-system. The crystal structure and superconductivity of both oxides were stated to be either identical or isomorphous. There are two or three superconductive phases with T_c～85 K and ～105 K or even higher. These phases are of 2212 and 2223, or even of more different in chemical composition, usually called as the lower and the higher superconductive phases. A number of studies were carried out to explore a pure single superconductive phase with different treatments and to find out their structure relation for these phases.