STUDY OF MAGNETIC-PROPERTIES OF HTSC CERA MICS RBA2CU3O7-DELTA (R=Y, GD, DY, YB, EU) IN CONSTANT AND VARIABLE FIELDS

The magnetic properties (magnetization, magnetic hysteresis, magnetic susceptibility (chi1', chi1'', chi3') of HTSC ceramics RB12Cu3O7-delta (R = Y, Gd, Dy, Yb, Eu) are studied in temperature range 4,2 K less-t han-or-equal-to T less-than-or-equal-to T(c) at constant (0 less-than- or-equal-to H less-than-or-equal-to 5.10(4) Oe) and variable (0.184 le ss-than-or-equal-to h0 less-than-or-equal-to 36.8 Oe) fields as well a s with their combined action. Most attention is concentrated on the pr ocesses in weak links. It is found that the second critical field of w eak links H(c2J) is analogous to the field of full penetration for sup erconducting granules, H(g). The temperature-field dependences of sus ceptibility display a number of peculiar features indicative of the ex istence of the hierarchy of weak links, i.e. the existence of distribu tion function of H(c1J) and H(c2J) for these links.