ENHANCED FLUX-PINNING AND CRITICAL CURRENTS BY V-SUBSTITUTION IN YBA2CU3O7-DELTA

V substituted samples with stoichiometric composition YBa2(Cu1-xVx)3O7 -delta, Where 0 < x < 0.04, prepared under identical conditins have be en characterized by resistivity, AC susceptibility and DC magnetizatio n measurements. DC magnetization measurements on randomly-oriented pow dered systems, as a function of temperature and field, exhibit pronoun ced M(H) hysteresis loops, indicative of large flux pinning even as T approaches T(c). We feel that this flux pinning arises due to the pref erential substitution of V on the Cu(I) site, which acts as a pinning centre. A critical current density, J(c), of approximately 7.4 x 10(5) A cm-2 is deduced from M(H) data at T = 13 K in an 8 kOe field for sa mples with x = 0.01, 0.02 and 0.04, which is nearly seven times higher than the J(c) of the pristine 1-2-3 powdered sample.