Structural, Magnetic, and Electrical Study of Polycrystalline Pr0.55Sr0.45-xNaxMnO3 (x=0.05 and 0.1)

Structural, magnetic, magnetocaloric, and electrical properties of Pr0.55Sr0.45-x Na (x) MnO3 (x = 0.05 and 0.1) have been investigated. Our samples were elaborated using the conventional ceramic method at high temperature. Rietveld refinement of the X-ray diffraction patterns shows that all our compounds are single phase and crystallize in the orthorhombic structure with Pbnm space group. Low field magnetic measurements indicate that all investigated samples exhibit a paramagnetic-ferromagnetic transition with decreasing temperature. This transition takes place at room temperature. A large magnetocaloric effect has been observed in all our compounds. The maximum value of the magnetic entropy change is found to be 3.87 J K-1 kg(-1) for the sample with x = 0.05 under 5T. The values of relative cooling power (RCP) are 246.52 J kg(-1) for x = 0.05 and 262.73 J kg(-1) for x = 0.1, respectively, for an applied magnetic field of 5T. The electrical resistivity measurements reveal a metal-semiconductor transition with increasing temperature with the presence of a resistivity minimum at low temperature which is attributed to the electron-electron columbic interactions.