Effect of Sr substitution on the stability of CuO chains in oxygen and nitrogen annealed YBa2-xSrxCu3O(x = 0.0, 0.50, 1.0) superconducting system

TL;DR

This study investigates how strontium substitution affects the stability of CuO chains and the superconducting transition temperature in YBa2-xSrxCu3O7-d, revealing that Sr substitution and nitrogen annealing both suppress Tc and influence structural stability.

Contribution

It provides new insights into the effects of Sr substitution and nitrogen annealing on the structural and superconducting properties of YBa2-xSrxCu3O7-d.

Findings

Superconducting Tc decreases with increasing Sr content.

Nitrogen annealing further suppresses Tc significantly.

Orthorhombic distortion decreases as Sr content increases.

Abstract

Samples of YBa2-xSrxCu3O7-d (x = 0.0, 0.50, 1.0) series were synthesized by solid-state reaction and first annealed in flowing O2 gas. All samples crystallized in orthorhombic structure, where orthorhombic distortion was found to decrease with an increase in x. Four probe resistivity measurements showed that superconducting transition temperature (Tc) decreases monotonically with x at a rate of dTc/dx = 1.3 K/at%. The sample with x=0 had a Tc = 91 K. The samples were further annealed in flowing N2 gas at 450 0C. The Tc of all samples decreased by nitrogen annealing. Interestingly, the decrease in Tc(x) became nearly three times larger at a rate of dTc/dx = 3.7 K/at%. The sample with x=0 had a Tc = 42 K. We discuss possible reasons and implications of the Tc(x) suppression vis stability of CuO chains. Key words: Y-123, Sr substitution, Superconducting transition