Abstract
Relaxation phenomena of oriented grained YBa 2Cu 3O x bulk material were investigated by vibrating sample magnetometry and inductive flux profile measurements. The applied magnetic field was directed parallel and perpendicular to the a - b plane. Since the agreement of shielding and transport critical currents presented in Part 1 ruled out granularity, experimental data could by analysed in terms of thermally activated flux creep. A survey of the theory of flux creep is given with special emphasis on the relationship between voltage versus current characteristics and time dependent decay of the magnetic moment. Temperature and field dependent activation energies were determined. Sweep rate dependent measurements of d.c. magnetization and a.c. flux profiles allowed access to short time relaxation phenomena. The time dependent decay of the critical current was found to deviate from the In t behaviour on this time scale.
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