Structure-Property Relationships in Pr 1-x Sr 1+x CoO 4 , (0 ≤ x ≤ 0.40)

The structural, magnetic and electric properties of Pr1−xSr1+xCoO4 layered perovskite have been investigated systematically over the range of doping, 0 ≤ x ≤ 0.40. The Rietveld refinements of X- ray powder diffraction (XRD) patterns at room temperature indicate that the samples crystallize in the K2NiF4-type structure with group symmetry I4/mmm. The samples of 0 ≤ x < 0.20 show Curie-Weiss paramagnetic behavior. With increasing x (0.20 ≤ x ≤ 0.40), three magnetic transition temperatures can be identified. The ground state exhibits a spin glass (SG) phase below the spin glass transition temperature TSG . Above, there is a mixture of ferromagnetic (FM) and antiferromagnetic (AFM) short-range order for TSG< T < TM with TM denoting the temperature of the corresponding anomaly in the magnetic susceptibility data. The third state can be attributed to a Griffiths phase for TM < T transition temperature between the Griffiths phase and the paramagnetic high temperature state. While the SG phase was suppressed with increasing applied field, both TM and TG shifted towards lower temperatures. No indications for a single pure ferromagnetic phase were observed even for applied magnetic fields up to 60 kOe. The electrical resistivity of the samples shows either thermally activated semiconducting behavior or 2D variable range hopping. The results are summarized in (x− T) phase diagram and discussed with respect to structure-property relationships.