Praseodymium Deficiency Effects on the PhysicalProperties of pr_(0.7-x) Sr_(0.3)MnO_3 Perovskite Manganites

摘要

The praseodymium deficiency effects on the structural, magnetic, and electrical properties of the lacunar perovskite manganite oxides Pr_(0.7-x)square _xSr_(0.3)MnO_3 (0<-x<- 0.23) have been investigated. This study is of great interest because it gives more information on the role of the Mn cation oxidation degree. Powder X-ray diffraction patterns are indexed in the rhombohed-ral perovskite structure with the R3c space group for x = 0 to 0.1 and in the orthorhombic one with the Pbnm space group for x = 0.15 to 0.23. Magnetization and resistivity measurements versus temperature show that all of our samples exhibit a semiconducting paramagnetic—metallic ferromagnetic transition when the temperature decreases.