EFFECT OF REPLACEMENT OF THE Cu VITAL ENVIRONMANT FOR La ON THE TRANSPORT PROPERTIES OF YBa2(Cu x-1 Lax)3O -7

Abstract

To be able to produce high quality superconducting material, the effect of substitution of copper in YBa2(Cu x-1 Lax)3O -7 δ superconductor by La content ( x=0 – 0.06 ) have to be understood . The study of transport properties of YBa2(Cu x-1 Lax)3 O -7 δ in this work using temperature measurements indicated that the best superconducting properties can be obtained for substitution of Cu by La concentration within the range (x=0.02- 0.04). The highest Tc (≈90K), sharpest transition to superconductivity (Δ=5 K) and lowest electrical resistivity (𝜌= 9.2𝜇Ω.cm) are corresponding to the substitution samples of x=0.02 and 0.04. Depression and degradation of the superconducting state as (x) increases above this rang is observed. Excess dopant of La (x ≤ 0.06) results in a strong decoupling of chains and planes whereas optimal La doping (0.02 ≤ x ≤ 0.04) can be adopted an alternate route to extensive oxygen anneal.