Synthesis,X‐ray data,and Hall effect measurements of Li‐doped Tl‐Ba‐Ca‐Cu‐O superconductor

Lithium‐doped Tl‐based superconductor was prepared by adding an amount of 0.3 mol.% to the Tl_1.8Ba₂Ca_2.2Cu₃O_x compound. The usual solid‐state reaction method has been applied under optimum conditions. The x‐ray data of the sample show a tetragonal structure with a high ratio of Tl‐2223 superconducting phase. The sample showed a transition at 125 K and the zero resistance was observed at 117 K. Longitudinal (transport) and transverse (Hall) resistivities were measured at different temperatures under different magnetic fields and the data were interpreted. A positive Hall coefficient was observed at normal state and a sign reversal appears at temperatures lower than the critical temperature. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)