Dependency of c-lattice parameter, activation energy and its magnetic power constant on x in Y1-xYbx/2Gdx/2Ba2Cu3O7-y superconductors

Abstract

To investigate the effect of x on c-lattice parameter, the activation energy, and the magnetic power constant of activation energy, the nominal composition of Y1-xYbx/2Gdx/2Ba2Cu3O7-y superconducting samples for x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 were prepared by solid-state reaction technique. c-Lattice parameters of the samples were calculated using XRD data. From the resistivity curves which were obtained under 11 different magnetic fields from 0 up to 5 T in the temperature range from 70 to 100 K steps by 0.25 K in zero field cooling regime, the activation energies of the samples were determined using Arrhenius activation energy law. The magnetic power constants of activation energy of the samples were calculated from the slopes of the plots ln U versus ln H. The results showed that the value of c-lattice parameters of samples x = 0 (Y123), and x = 1.0 (YbGd123) are in good agreement with the reported works. It was found that c-lattice parameter decreased with the increasing the content x except samples of x = 0.4 and 1.0. It was thought that the origin of the separation from the linearity comes from the lack of Y in nominal composition for x = 1.0. As for the sample x = 0.4, it was thought to be due to the fact that Y, Yb and Gd atoms affect the superconductivity properties dominantly. On the other hand, there is a similarity among U(0 T), U(1 T), its magnetic power constant and the c-lattice parameter with increasing content x. The desired activation energy and its magnetic field dependency constant can be controlled with x and then this can be useful for the superconducting applications. © 2007 Elsevier B.V. All rights reserved.