Structure, Magnetism, and Transport Properties of Pr1 -xSrxMnO3 (x = 0.45-0.75) up to 1200 K

The perovskite manganites Pr1-xSrxMnO3 in the region 0.45 x 0.75 exhibit two crystallographic modifications at room temperature-orthorhombic Ibmm and tetragonal I4\mcm-with boundary situated at x ~ 0.48. The high-temperature X-ray diffraction data show that for x 0.6 the tetragonal phase of I4\mcm symmetry transforms on heating directly to the cubic Pm3m symmetry. On the other hand, for x < 0.6 the I4\mcm phase transforms successively to orthorhombic Ibmm through a two-phase region, then to rhombohedral Rc, and finally to cubic Pm3m. The transient rhombohedral Rc phase is present also for orthorhombic compounds Pr1-xSrxMnO3 with x < 0.48. High-temperature structural transitions are not associated with any observable anomalies in electrical transport and paramagnetic properties while the occurrence of three magnetically ordered phases (FM, A-type and C-type AFM) at low temperature influence resistivity and thermopower essentially