Relationship Between Electronic and Crystal Structure in Nd1 + xBa2 − xCu3O6 + δ

Abstract

In accordance with a relation between the lattice parameter c and the concentration of holes p, which has been found earlier for the YBa2Cu3O6+δcompound, we obtain the p parameter in the same manner for the solid solution Nd1.2Ba1.8Cu3O6+δwith substitution of Nd3+for Ba2+in barium sites. For this, structural and superconducting properties of the Nd1.2Ba1.8Cu3O6+δsamples stored for specified times τ after quenching from annealing temperatures have been studied. The investigation shows that Nd1.2Ba1.8Cu3O6+δstored for a long time has quite a low critical temperature Tcextending only to Tconset = 55 K for the most oxidized sample with δ = 0.953. We find that the δ-dependence of the lattice parameter c significantly changes with time τ. When using the relation between c and p, the existence of electron doping of 0.045 per Cu in Nd1.2Ba1.8Cu3O6+δcan be inferred. This doping explains well-reduced Tcin Nd1.2Ba1.8Cu3O6+δ. In addition, we observe a local drop of Tcby up to 20 K for the samples with p˜0.095 (δ˜0.8) similar to decreasing Tcknown as “anomaly 1/8”. © 2017, Springer Science+Business Media New York.