Praseodymium deficiency effects on the physical properties of Pr0.7-x square Sr0.3MnO3 perovskite manganites

The praseodymium deficiency effects on the structural, magnetic, and electr ical properties of the lacunar perovskite manganite oxides Pr(0.7-x)square xSr0.3MnO3 (0 less than or equal to x less than or equal to 0.23) have been investigated. This study is of great interest because it gives more inform ation on the role of the Mn cation oxidation degree. Powder X-ray diffracti on patterns are indexed in the rhombohedral perovskite structure with the R (3) over barc space group for x = 0 to 0.1 and in the orthorhombic one wit h the Pbnm space group for x = 0.15 to 0,23, Magnetization and resistivity measurements versus temperature show that all of our samples exhibit semico nducting paramagnetic-metallic ferromagnetic transition when the temperatur e decreases. (C) 2001 Academic Press.