ANISOTROPY OF AC MAGNETIC-SUSCEPTIBILITY AND J(C) IN YBCO BULK TEXTURED SAMPLES AND SINGLE-CRYSTALS

a.c. magnetic susceptibility chi of single crystals and two types of bulk textured slabs, differing by in c-axis orientation, have been studied. The measurements are carried out in the condition of the simple relation between chi and J(c). The results obtained do not depend on the geometrical sample factors but are defined by the d.c. magnetic field H > H-p orientation in relation to the crystallographic axis. We observe a qualitative difference of the angular dependence of the critical current density J(c) for the textured samples and single crystals. The results are discussed and connected with structural features of these materials.