Effect of praseodymium on the electrical resistance of YBa2Cu3O7-δ single crystals

The electrical resistivity in the ab-plane of the Y1-yPryBa2Cu3O7-delta single crystals with high degree of perfection in the interval of T-c - 300 K was investigated. The increasing of praseodymium content leads to the reduction of the critical temperature (T-c) from 92 to 30 K. The experimental results can be approximated by the expression, taking into account the scattering of electrons by phonons, defects, the fluctuation conductivity in the 3D Aslamazov-Larkin model, as well as the transition to a semiconductor type behavior of the resistivity at the high praseodymium concentrations. The concentration dependences of all fitting parameters indicate a structural transition in the region 0.35 <= y <= 0.43. In particular, the Debye temperature changes in this range from 350 to 550 K, and the transverse coherence length passes through a maximum xi(C)(0) approximate to 5 angstrom. The concentration dependence of the critical temperature testifies the d-pairing of the BCS model. (C) 2014 Elsevier Ltd. All rights reserved.