Magnetic flux penetration into (Tl0.6Pb0.5)(Ba0.1Sr0.9)2Ca2Cu3Ox and(Tl0.8Bi0.3)(Ba0.1Sr0.9)2Ca2Cu3Oy bulk pellet samples

Magnetic field penetration into (Tl0.6Pb0.5)(Ba0.1Sr0.9)2Ca2Cu3Ox and (Tl0.8Bi0.3)(Ba0.1Sr0.9)2Ca2Cu3Oy bulk pellet samples was investigated by two methods: (i) by the volume magnetization and (ii) by the local scanning Hall method. Pb-doping resulted in stronger inter-grain links and improved the intra-grain critical current densities. Bi-doping instead of Pb-doping increased the critical temperature from 113 K to 116 K. Considering that bulk pinning of the doped Tl-1223 samples is low and that the magnetic field penetration is predominantly determined by geometrical barrier effects, the characteristic magnetic penetration fields obtained by the two methods are in excellent agreement.