Magnetic and Charge-Ordering Properties of Bi0.2−xPrxCa0.8MnO3 (0.0=x=0.20) Perovskite Manganite

We have studied structure, magnetic and transport properties of polycrystalline samples synthesized with nominal compositions Bi 0.2− x Pr x Ca 0.8 MnO 3 ( x =0.00, 0.02, 0.04, 0.08, 0.12, 0.16 and 0.20) via a solid-state reaction route. Magnetic measurements show that substitution of Pr at Bi site strongly affect the magnetic and charge-ordering properties. It has been found that the charge-ordering temperature ( T CO ) decreases with increasing x up to x =0.12 and then after it increases with x up to x =0.20. A spin glass (SG) state has been observed at ∼105 K in all the samples. Pr doping also leads to enhancement in the magnetic moment up to x =0.12 and then after a decrease in magnetic moment up to x =0.20. A concomitant increase in resistivity up to x =0.04 and then decrease in resistivity up to x =0.20 is also observed. We propose that the local lattice distortion induced by the size mismatch between the A-site cations and 6s 2 character of Bi 3+ lone pair electron are responsible for the observed variation in the physical properties with doping content of Pr.