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

The perovskite manganites Pr 1 - x Sr x MnO 3 in the region 0.45 ≤ x ≤ 0.75 exhibit two crystallographic modifications at room temperature orthorhombic Ibmm and tetragonal I 4/ 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 I 4/ mcm symmetry transforms on heating directly to the cubic Pm 3 m symmetry. On the other hand, for x < 0.6 the I 4/ mcm phase transforms successively to orthorhombic Ibmm through a two-phase region, then to rhombohedral R 3̄ c, and finally to cubic Pm 3 m . The transient rhombohedral R 3̄ c phase is present also for orthorhombic compounds Pr 1 - x Sr x MnO 3 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.