(La0.8Gd0.2)0.85Ag0.15MnO3 Perovskit Manganit Sisteminde Gd Yer Değiştirmesinin Yapısal Manyetik ve Manyetokalorik Özellikleri Üzerine Etkisi

Abstract

In this paper, the effect of Gd substitution with La on structural, magnetic and magnetocaloric properties in (La 0.8 Gd 0.2) 0.85 Ag 0.15 MnO 3 manganite sample prepared by sol-gel method has been studied. The crystal properties have been investigated by x-ray diffraction technique that shows the sample is in rhombohedral structure with R3 ̅ c space group. In addition to this structure, small amount of reflections belongs to GdMn 2 O 5 phase is detected. Scanning electron microscope images show that the sample is constituted from square shaped grains. Energy dispersive x-ray spectroscopy analysis shows that the sample includes all expected elements. The sample exhibits magnetic phase transition from ferromagnetic to paramagnetic phase at around 149 K temperature. Applied field dependence of magnetization under isothermal process M(H) shows that the nature of the phase transition is second order and maximum magnetic entropy change (-ΔS M) value calculated from M(H) curves is found as 1.73 J/kgK under 50 kOe external magnetic field change.