INFLUENCE OF STRONTIUM ON SUPERCONDUCTING AND MAGNETIC-PROPERTIES OF DYBA2-XSRXCU3O7-DELTA

The influence of substitution of Ba2+ with Sr2+ on the superconducting and magnetic properties of ceramic DyBa2Cu3O7-delta samples with vari ous oxygen contents has been investigated. The temperature and field d ependences of magnetization and magnetic susceptibility of DyBa2-xSrxC u3O7-delta compounds with x= 0, 0. 5, and 1.0, were measured. The diam agnetic effect, the value of the intergrain critical field H(clJ), and the superconducting transition temperature T(c), were found to decrea se while the intragrain critical field H(cl) and the width of the supe rconducting transition increased as the strontium content increased. T he magnetic phase diagram H-T constructed for DyBa1.5Sr0.5Cu3O7-delta and DyBaSrCu3O7-delta compounds is topologically identical with the ph ase diagram of DyBa2Cu3O7-delta where one H(c)(T) line of the antiferr omagnetic-paramagnetic transition in the magnetic field is seen. It wa s shown that the replacement of Ba2+ by Sr2+ leads to an enhancement o f the low-dimensional properties. This is manifested by the appearance of a significant difference between the temperature of maximum chi(T) , characterizing 2D magnetic correlations, and the Neel temperature; T (N), corresponding to a 3D ordering. In the DyBa2-xSrxCu3O7-delta syst em there is a structural phase transition with a heat absorption at th e temperature of about 2.4 K.