Özet:
In this study, the effect of Pb substitution with Sr on structural, magnetic and magnetocaloric properties in Pr(Sr1-xPbx)Mn2O6 (0.1x0.3) double perovskite manganite compounds prepared by the sol-gel method has been reported. Crystallinity has been worked by X-ray diffraction measurement and the Rietveld refinement method, which shows all samples are in monoclinic structure with P21/n space group without impurity phase. Scanning electron microscope analysis shows that all samples constituted from square-shaped grains with distinct grain boundaries, and energy-dispersive X-ray spectroscopy analysis shows that all expected elements are detected and there is no impurity element in the sample. All samples exhibit a magnetic phase transition from ferromagnetic to paramagnetic phase at T-C determined as 274, 282 and 286K for x=0.1 (PSPM-1), 0.2 (PSPM-2) and 0.3 (PSPM-3) in the PrSr1-xPbxMn2O6 structure, respectively. Isothermal magnetisation curves near T-C are used to determine the nature of the magnetic phase transition and the magnetic entropy change values (-S-M), which are found as 2.78, 3.11 and 3.52Jkg(-1)K(-1) for PSPM-1, PSPM-2 and PSPM-3 samples, respectively. Relative cooling power (RCP) values of the samples are also determined as 241, 311 and 246Jkg(-1) for PSPM-1, PSPM-2 and PSPM-3 samples, respectively. S-M and RCP values are also calculated by using the Landau theory and the results are in accordance with the experimental results, which indicate the role of electron condensation energy and magneto-elastic coupling in magnetic entropy change value of the samples.
