Rapid synthesis, structure, electrical and magnetic properties of (La1-xPrx)0.8Na0.2MnO3 (0.0 x 0.8) perovskite phases

Solid solutions of (La1-xPrx)0.8Na0.2MnO3 (0.0  x  0.8) perovskite oxide phases have been synthesized by the nitrate-citrate gel combustion method at relatively low temperature (825 C) and shorter duration of 5 h. Structural parameters were determined by the Rietveld refinement method using room temperature powder X-ray diffraction data. XRD results reveal that, on substitution of Pr3+ - ion to La3+- site in the perovskite phase, the structural transition was observed from rhombohedral (space group, R-3c, No. 167) to orthorhombic symmetry (space group, Pbnm, No. 62). The change in symmetry is attributed to smaller ionic radii of Pr3+ - ion (rPr3+ = 1.179 A) than La3+-ion (rLa3+ = 1.36 A). When x = 0.0, La0.80Na0.20MnO3, compound crystallizes in the rhombohedral structure and show ferromagnetic metallic (FMM) property, whereas x = 0.80, Pr0.80Na0.20MnO3 compound crystallized in the orthorhombic structure and exhibit low temperature ferromagnetic insulating (FMI) behavior.