Neutron diffraction studies on Pr1+xBa2-xCu3O7-δ

PrBa2Cu3O7-δ is not superconducting and exhibits antiferromagnetic ordering of the Pr moments with TN of ≅17 K. In Pr1+xBa2-xCu3O7-δ, TN decreases with increasing x. In order to understand this behaviour, we have carried out powder neutron diffraction studies on various Pr1+xBa2-xCu3O7-δ samples. The structure transforms from orthorhombic for x=0.0 and 0.2 to tetragonal for x=0.4 and 0.6. An overall contraction in the unit cell volume and a decrease in the distance of Pr from Cu-O2 plane is observed with increasing x. The oxygen content increases with increasing x but is not sufficient to neutralize the excess electrons contributed by Pr substituting at the Ba2+ site. The decrease in TN may be due to the decrease in carrier density caused by above substitution. (orig.)