Preparation and characterisation of PbSr(YCa)CuO superconducting crystals

Basic magnetic properties of Pb₂Sr₂Y_1-xCa_xCu₃O_{8+ delta} have been studied. Results of the measurements of the AC susceptibility of the powder samples with x=0.2-0.8 and DC magnetic moment and susceptibility of the Pb₂Sr₂Y_0.7Ca_0.3Cu₃O_{8+ delta} single crystal are presented. Temperature dependence of the magnetic moment in various cooling procedures was measured. Zero-field cooling (ZFC), field cooling (FC) and remanent (REM) magnetic moments are given. A lower critical field H_c1 has been determined for the magnetic field oriented perpendicular (H_{perpendicular to} ) and parallel to (H/sub ///) to the Cu-O planes. A new more sensitive procedure of H_c1 determination has been proposed.