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

Abstract

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 7.23J/kgK under the magnetic field change of 5T 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.