Structural and magnetic properties of Bi doped in the A site of (Pr1-xBix)0.6Sr0.4MnO3 (0≤x≤0.4) perovskite manganites

We studied the effect of Bi doping in the A-site on the structural, magnetic, and magneto-caloric properties of the (Pr(1-x)Bi(x))(0.6)Sr(0.4)MnO(3) (0 <= x <= 0.4) perovskite manganese oxides. In this study, the average ionic radius <r(A)> of the A cation site was systematically varied while keeping fixed the carrier concentration (Mn(3+)/Mn(4+) ratio). All our samples have been elaborated by the conventional solid state reaction at high temperature. X-ray powder diffraction at room temperature showed that all our synthesized samples are single phase and crystallize in the orthorhombic system with Pbnm space group. The unit cell volume decreases linearly with increasing Bi content. Magnetization measurements versus temperature in a magnetic applied field of 50 mT show that all our samples exhibit a paramagnetic to ferromagnetic transition when temperature decreases. The Curie temperature T(C) decreases from 310 K for x = 0 to 252 K for x = 0.4.The critical exponent gamma defined by M(sp)(T) = M(sp)(0) (1-T/T(C))(gamma) and deduced from M(H) curves is found to be 0.315 for Pr(0.54)Bi(0.06)Sr(0.4)MnO(3) sample. Furthermore, a large magnetocaloric effect near T(C) has been detected with a maximum of magneto-entropy change, of 1.11 Jkg(-1) K(-1) and 4.78 Jkg(-1)K(-1) at 1 T and 7 T, respectively, for Pr(0.54)Bi(0.06)Sr(0.4)MnO(3) sample.