Praseodymium deficiency effects on the physical properties of Pr1.2–x□xSr1.8Mn2O7 bilayer manganese oxides

The praseodymium deficiency effects on the structural, magnetic and electrical properties of the lacunar bilayers manganese oxides Pr1.2–x□xSr1.8Mn2O7 (0 ≤ x ≤ 0.15) were studied. Rietveld refinements of the X-ray diffraction patterns show that all our samples are single phase and crystallize in the tetragonal structure with I4/mmm space group. All our samples exhibit a paramagnetic-ferromagnetic transition on cooling. The praseodymium deficiency leads to a decrease of the Curie temperature. Resistivity measurements as a function of temperature show that only the parent sample Pr1.2Sr1.8Mn2O7 exhibits a semiconducting-metallic transition with decreasing temperature. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)