Izvorni znanstveni članak
Homogeneity and percolation in ceramic high temperature superconductors
Emil Babić
Mladen Prester
Dinko Babić
Željko Marohnić
Đuro Drobac
Sažetak
The main results of systematic investigation of the electric transport properties and ac susceptibility of ceramic high temperature superconductors (HTS) are presented. An effort has been made to deduce a suitable description for these properties. Due to the presence of the weak links at the grain boundaries the superconducting and the normal state properties of these systems deviate strongly from those of the corresponding homogeneous compounds. Becasue of this, ceramic HTS can be modeled as the two phase systems consisting of grains and 3D disordered array of intergrain links. The variation in the strength of the coupling between the grains determines the bulk critical currents (Ic) of these systems. A more detailed analysis shows that properties of ceramic HTS depend strongly on density and the ratio between the dimensions of the sample and the grain size. Therefore only some properties of fine-grained dense samples can probably be described by averaging the local properties over the volume of the sample. In contrast to that, the resistivity at lower densities, the diamagnetic transition below Tc and the transition to the dissipative state above Ic all exhibit the percolation effects.
Ključne riječi
Hrčak ID:
299272
URI
Datum izdavanja:
1.2.1992.
Posjeta: 185 *