Effects of synthesis route on the structural, magnetic and magnetocaloric properties of Pr0.8K0.2MnO3

Pr0.8K0.2MnO3 ceramics are prepared by solid-state reaction and Pechini sol-gel method. The influence of the powder synthesis method on the structural, morphological, magnetic and magnetocaloric properties of the samples are investigated. The X-ray diffraction pattern shows reflections typical of the perovskite structure with orthorhombic symmetry. The experimental results reveal that both samples undergo a second-order phase transition. The maximum magnetic entropy changes, deduced from the M-µ0H measurements, are 3.77 and 7.23 J/kg K under the magnetic field change of 5 T for Pr0.8K0.2MnO3 synthesized by using solid-state reaction and sol-gel methods respectively. The field dependence of magnetic entropy change is analyzed showing the power law dependence, ΔS(T,µ0H)=a(T)(μ0H)n(T,H) at the Curie temperature. Using the scaling laws of ∆S, the experimental ∆S collapse onto a universal curve for both ceramics. These results suggest that the physical properties of our samples are strongly depended on synthesis techniques. It is found that Pechini sol-gel method is more efficient and stable to obtain ceramic materials with good magnetic properties. Consequently, a substantial increase of the ferromagnetic to paramagnetic transition temperature and an enhancement of magnetocaloric properties are observed in the sol-gel made sample making it more suitable for magnetic refrigeration applications.