Abstract
Magnetic measurement and powder X-ray Rietveld analysis are performed on oxygenated Pri 1.5 Ba 1.5 Cu 3 O 7.2 cuprate. This tetragonal compound with lattice parameters a = 0.38916 nm and c = 1.16177 nm is found to form the TlBa 2 CaCu 2 O 7 1212-type structure when written as Cu[Ba 1.5 Pr 0.5 ]PrCu 2 O 7.2 . Low temperature magnetic data indicate that anomalous Pr order temperature T N (Pr) decreases from 18 K for orthorhombic PrBa 2 Cu 3 O 6.9 to 10.5 K for Pr 1.5 Ba 1.5 Cu 3 O 7.2 . The increasing Pr-O bond length with decreasing TN indicates that Pr ordering is closely correlated with the wave function overlap between Pr-4f orbital and O-2p π orbital in the CuO 2 bi-layers.