Magnetic and Transport Properties of Bi0.5-x Pr x Ca0.5MnO3(0.0 ≤ x ≤ 0.50) Manganites

In this work, the effect of Pr doping at the Bi site on the critical behavior and magnetocaloric and transport properties of Bi0.5-x Pr (x) Ca0.5MnO3 (0.0 ae< 0.50) manganite synthesized by sol-gel method is reported. An increase in Curie temperature (T (C)) with an increase in Pr content is observed. The samples with x = 0.0-0.40 show first-order phase transition whereas the sample with x = 0.50 shows second-order phase transition near T (C). The estimated values of critical exponents beta = 0.75 and gamma = 0.82 for the sample with x = 0.50 do not fall into any universality class. The sample with x = 0.50 shows maximum magnetic entropy change (|Delta S (m)| = (1.22 J kg(-1) K-1) at T (C) in an applied magnetic field of 40 kOe, which is associated with magnetocaloric effect (MCE). All the samples show semiconducting behavior and also follow Mott's variable range hopping (VRH) model below the charge ordering temperature (T (CO)). The changes in magnetic and transport properties are correlated with the changes in the structural parameters of the samples. The results are discussed in view of the effect of Pr doping on the 6s(2) lone pair character of Bi3+ ions and disorder in the samples.