THE EFFECT OF HO TO THE FLUX-PINNING AND MICROSTRUCTURE OF POWDER MELTING PROCESS Y(HO)BCO SAMPLES

Magnetic relaxation and magnetization are measured for powder melting Y1-xHoxBa2Cu3O7 (x = 0.2, 0.4, and 0.6) samples within a wide temperature range. The pinning potential U and magnetization critical current densities J(c) are obtained according to the theory of Anderson and Kim and Bean's model. It is found that both U and J(c) are a affected by the addition of the rare-earth element Ho. In the sample with x = 0.4 the pinning potential U and the critical current J(c) have maximum values when the magnetic field is parallel to the c-axis. An unusual behaviour of U as a function of temperature T, which may be related to the pinning potential distribution in the sample is observed.