A large magnetocaloric effect of La0.8Na0.2Mn0.97Bi0.03O3 manganite synthesized by pechini Sol-Gel method and compared to the sample synthesized by solid-state route

Abstract

Abstract In this work, the physical properties of the compounds La0.8Na0.2Mn0.97Bi0.03O3 prepared by solid-state (S1) and Sol-Gel (S2) methods are compared. Both compounds were found to crystallize in the rhombohedra structure with R-3c space group. They also exhibited a Ferromagnetic (FM)-Paramagnetic (PM) phase transition around the Curie temperature (TC). Curie temperature TC and magnetization decreased with the decrease of the crystallite size. The maximum of the magnetic entropy change ΔSM at 5 T, were about 4.73 J·K−1·kg−1 and 5.88 J·K−1·kg−1 for S1 and S2, respectively. We proved the second order character via the normalization curves and through the Banerjee criteria. Moreover, we determined the critical exponents values of β, γ and δ with the extrapolation of Arrott plots, the Kouvel fisher technique and the critical isotherm, respectively. The validity of the exponents values was confirmed with the scaling hypothesis; the M (T, e) curves collapsed onto two independent universal branches below and above Tc.